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  • Transplanckian censorship and the local swampland distance conjecture
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-21
    Patrick Draper, Szilard Farkas

    Abstract The swampland distance conjecture (SDC) addresses the ability of effective field theory to describe distant points in moduli space. It is natural to ask whether there is a local version of the SDC: is it possible to construct local excitations in an EFT that sample extreme regions of moduli space? In many cases such excitations exhibit horizons or instabilities, suggesting that there are bounds on the size and structure of field excitations that can be achieved in EFT. Static bubbles in ordinary Kaluza-Klein theory provide a simple class of examples: the KK radius goes to zero on a smooth surface, locally probing an in- finite distance point, and the bubbles are classically unstable against radial perturbations. However, it is also possible to stabilize KK bubbles at the classical level by adding flux. We study the impact of imposing the Weak Gravity Conjecture (WGC) on these solutions, finding that a rapid pair production instability arises in the presence of charged matter with q/m ≳ 1. We also analyze 4d electrically charged dilatonic black holes. Small curvature at the horizon imposes a bound log (MBH) ,≳ |∆𝜙|, independent of the WGC, and the bound can be strengthened if the particle satisfying the WGC is sufficiently light. We conjecture that quantum gravity in asymptotically flat space requires a general bound on large localized moduli space excursions of the form |∆𝜙| ≲ | log(RΛ)|, where R is the size of the minimal region enclosing the excitation and Λ−1 is the short-distance cutoff on local EFT. The bound is qualitatively saturated by the dilatonic black holes and Kaluza-Klein monopoles.

    更新日期:2020-01-27
  • The dynamical diquark model: fine structure and isospin
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-21
    Jesse F. Giron, Richard F. Lebed, Curtis T. Peterson

    Abstract We incorporate fine-structure corrections into the dynamical diquark model of multiquark exotic hadrons. These improvements include effects due to finite diquark size, spin-spin couplings within the diquarks, and most significantly, isospin-dependent couplings in the form of pionlike exchanges assumed to occur between the light quarks within the diquarks. Using a simplified two-parameter interaction Hamiltonian, we obtain fits in which the isoscalar JPC = 1++ state — identified as the X (3872) — appears naturally as the lightest exotic (including all states that are predicted by the model but have not yet been observed), while the closed-charm decays of Zc(3900) and Zc(4020) prefer J/𝜓 and hc modes, respectively, in accord with experiment. We explore implications of this model for the excited tetraquark multiplets and the pentaquarks.

    更新日期:2020-01-27
  • From bulk loops to boundary large-N expansion
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-24
    Dmitry Ponomarev

    Abstract We study the analytic structure of loop Witten diagrams in Euclidean AdS represented by their conformal partial wave expansions. We show that, as in flat space, amplitude’s singularities are associated with non-trivial cuts of the diagram and factorize into products of the coefficient functions for the subdiagrams resulting from these cuts. We consider an example of a one-loop four-point diagram in detail and then briefly discuss how the procedure can be extended to more general diagrams. Finally, we show that this analysis reproduces simple relations that follow from the large-N considerations on the boundary.

    更新日期:2020-01-26
  • Gravitational corner conditions in holography
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-24
    Gary T. Horowitz, Diandian Wang

    Abstract Contrary to popular belief, asymptotically anti-de Sitter solutions of gravitational theories cannot be obtained by taking initial data (satisfying the constraints) on a spacelike surface, and choosing an arbitrary conformal metric on the timelike boundary at infinity. There are an infinite number of corner conditions that also must be satisfied where the initial data surface hits the boundary. These are well known to mathematical relativists, but to make them more widely known we give a simple explanation of why these conditions exist and discuss some of their consequences. An example is given which illustrates their power. Some implications for holography are also mentioned.

    更新日期:2020-01-26
  • The Higgs mechanism — Hasse diagrams for symplectic singularities
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-24
    Antoine Bourget, Santiago Cabrera, Julius F. Grimminger, Amihay Hanany, Marcus Sperling, Anton Zajac, Zhenghao Zhong

    Abstract We explore the geometrical structure of Higgs branches of quantum field theories with 8 supercharges in 3, 4, 5 and 6 dimensions. They are symplectic singularities, and as such admit a decomposition (or foliation ) into so-called symplectic leaves, which are related to each other by transverse slices. We identify this foliation with the pattern of partial Higgs mechanism of the theory and, using brane systems and recently introduced notions of magnetic quivers and quiver subtraction, we formalise the rules to obtain the Hasse diagram which encodes the structure of the foliation. While the unbroken gauge symmetry and the number of flat directions are obtainable by classical field theory analysis for Lagrangian theories, our approach allows us to characterise the geometry of the Higgs branch by a Hasse diagram with symplectic leaves and transverse slices, thus refining the analysis and extending it to non-Lagrangian theories. Most of the Hasse diagrams we obtain extend beyond the cases of nilpotent orbit closures known in the mathematics literature. The geometric analysis developed in this paper is applied to Higgs branches of several Lagrangian gauge theories, Argyres-Douglas theories, five dimensional SQCD theories at the conformal fixed point, and six dimensional SCFTs.

    更新日期:2020-01-26
  • 4d N$$ \mathcal{N} $$ = 1 from 6d D-type N$$ \mathcal{N} $$ = (1, 0)
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-23
    Jin Chen, Babak Haghighat, Shuwei Liu, Marcus Sperling

    Abstract Compactifications of 6d \( \mathcal{N} \) = (1, 0) SCFTs give rise to new 4d \( \mathcal{N} \) = 1 SCFTs and shed light on interesting dualities between such theories. In this paper we continue exploring this line of research by extending the class of compactified 6d theories to the D- type case. The simplest such 6d theory arises from D5 branes probing D-type singularities. Equivalently, this theory can be obtained from an F-theory compactification using −2- curves intersecting according to a D-type quiver. Our approach is two-fold. We start by compactifying the 6d SCFT on a Riemann surface and compute the central charges of the resulting 4d theory by integrating the 6d anomaly polynomial over the Riemann surface. As a second step, in order to find candidate 4d UV Lagrangians, there is an intermediate 5d theory that serves to construct 4d domain walls. These can be used as building blocks to obtain torus compactifications. In contrast to the A-type case, the vanishing of anomalies in the 4d theory turns out to be very restrictive and constraints the choices of gauge nodes and matter content severely. As a consequence, in this paper one has to resort to non- maximal boundary conditions for the 4d domain walls. However, the comparison to the 6d theory compactified on the Riemann surface becomes less tractable.

    更新日期:2020-01-26
  • Isolated zeros destroy Fermi surface in holographic models with a lattice
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-23
    Floris Balm, Alexander Krikun, Aurelio Romero-Bermúdez, Koenraad Schalm, Jan Zaanen

    Abstract We study the fermionic spectral density in a strongly correlated quantum system described by a gravity dual. In the presence of periodically modulated chemical potential, which models the effect of the ionic lattice, we explore the shapes of the corresponding Fermi surfaces, defined by the location of peaks in the spectral density at the Fermi level. We find that at strong lattice potentials sectors of the Fermi surface are unexpectedly destroyed and the Fermi surface becomes an arc-like disconnected manifold. We explain this phenomenon in terms of a collision of the Fermi surface pole with zeros of the fermionic Green’s function, which are explicitly computable in the holographic dual.

    更新日期:2020-01-26
  • Generalised power series expansions for the elliptic planar families of Higgs + jet production at two loops
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-23
    F. Moriello

    Abstract We obtain generalised power series expansions for a family of planar two-loop master integrals relevant for the QCD corrections to Higgs + jet production, with phys- ical heavy-quark mass. This is achieved by defining differential equations along contours connecting two fixed points, and by solving them in terms of one-dimensional generalised power series. The procedure is efficient, and can be repeated in order to reach any point of the kinematic regions. The analytic continuation of the series is straightforward, and we present new results below and above the physical thresholds. The method we use allows to compute the integrals in all kinematic regions with high precision. For example, per- forming a series expansion on a typical contour above the heavy-quark threshold takes on average O(1 second) per integral with worst relative error of O(10−32), on a single CPU core. After the series is found, the numerical evaluation of the integrals in any point of the contour is virtually instant. Our approach is general, and can be applied to Feynman integrals provided that a set of differential equations is available.

    更新日期:2020-01-26
  • Off-shell unimodular N = 1 , d = 4 supergravity
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-22
    Jesus Anero, Carmelo P. Martin, Raquel Santos-Garcia

    Abstract We formulate a unimodular N = 1, d = 4 supergravity theory off shell. We see that the infinitesimal Grassmann parameters defining the unimodular supergravity trans- formations are constrained and show that the conmutator of two infinitesinal unimodular supergravity transformations closes on transverse diffeomorphisms, Lorentz transforma- tions and unimodular supergravity transformations. Along the way, we also show that the linearized theory is a supersymmetric theory of gravitons and gravitinos. We see that de Sitter and anti-de Sitter spacetimes are non-supersymmetric vacua of our unimodular supergravity theory.

    更新日期:2020-01-26
  • Modular A 4 invariance and leptogenesis
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-22
    Takehiko Asaka, Yongtae Heo, Takuya H. Tatsuishi, Takahiro Yoshida

    Abstract We consider a model with three right-handed neutrinos in which Yukawa coupling constants and Majorana masses are obtained by requiring the modular A4 symmetry. It has been shown that the model can explain mass hierarchies and mixing patterns of charged leptons and neutrinos with the seesaw mechanism. In this article we investigate the leptogenesis by decays of right-handed neutrinos in this model. It is shown that masses of right-handed neutrinos are about 1013 GeV in order to account for the observed baryon asymmetry of the universe. Furthermore, the positive sign of the baryon asymmetry is obtained only for the limited ranges of mixing angles and CP violation phases of active neutrinos, which can be tested by future neutrino experiments.

    更新日期:2020-01-26
  • BPS states, conserved charges and centres of symmetric group algebras
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-22
    Garreth Kemp, Sanjaye Ramgoolam

    Abstract In \( \mathcal{N} \) = 4 SYM with U(N) gauge symmetry, the multiplicity of half-BPS states with fixed dimension can be labelled by Young diagrams and can be distinguished using conserved charges corresponding to Casimirs of U(N). The information theoretic study of LLM geometries and superstars in the dual AdS5× S5 background has raised a number of questions about the distinguishability of Young diagrams when a finite set of Casimirs are known. Using Schur-Weyl duality relations between unitary groups and symmetric groups, these questions translate into structural questions about the centres of symmetric group algebras. We obtain algebraic and computational results about these structural properties and related Shannon entropies, and generate associated number sequences. A characterization of Young diagrams in terms of content distribution functions relates these number sequences to diophantine equations. These content distribution functions can be visualized as connected, segmented, open strings in content space.

    更新日期:2020-01-26
  • A left-right mirror symmetric model: common origin of neutrino mass, baryon asymmetry and dark matter
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-23
    Wei-Min Yang

    Abstract I suggest a left-right mirror symmetric particle model as the natural and aes- thetic extension of the SM. As the left-right mirror symmetry breaking, the tiny neutrino mass is generated by the radiative mechanism, the baryon asymmetry through the lepto- genesis arises from the characteristic decay of the TeV-scale mirror charged lepton, and a KeV-mass sterile Dirac fermion eventually becomes the CDM. The model can completely account for the common origin of the neutrino mass, the baryon asymmetry and the dark matter, moreover, profoundly uncover the internal connections among them. Finally, I discuss several feasible approaches to test the model predictions and probe the new physics by near future experiments.

    更新日期:2020-01-24
  • Logarithmic loop corrections, moduli stabilisation and de Sitter vacua in string theory
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-23
    Ignatios Antoniadis, Yifan Chen, George K. Leontaris

    Abstract We study string loop corrections to the gravity kinetic terms in type IIB com- pactifications on Calabi-Yau threefolds or their orbifold limits, in the presence of D7-branes and orientifold planes. We show that they exhibit in general a logarithmic behaviour in the large volume limit transverse to the D7-branes, induced by a localised four-dimensional Einstein-Hilbert action that appears at a lower order in the closed string sector, found in the past. Here, we compute the coefficient of the logarithmic corrections and use them to provide an explicit realisation of a mechanism for Kähler moduli stabilisation that we have proposed recently, which does not rely on non-perturbative effects and lead to de Sit- ter vacua. Our result avoids no-go theorems of perturbative stabilisation due to runaway potentials, in a way similar to the Coleman-Weinberg mechanism, and provides a counter example to one of the swampland conjectures concerning de Sitter vacua in quantum grav- ity, once string loop effects are taken into account; it thus paves the way for embedding the Standard Model of particle physics and cosmology in string theory.

    更新日期:2020-01-24
  • Anomalies of QFTs from M-theory and holography
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-21
    Ibrahima Bah, Federico Bonetti, Ruben Minasian, Emily Nardoni

    Abstract We describe a systematic way of computing the ’t Hooft anomalies for continuous symmetries of Quantum Field Theories in even dimensions that can be geometrically engineered from M5-branes. Our approach is based on anomaly inflow, and characterizes the anomaly polynomial of the QFT in terms of the geometric definition of the field theory. In particular, when the QFT admits a holographic dual, the topological data of the solution is sufficient to compute the anomalies of the dual field theory, including finite terms in N. We study several classes of examples in four and six dimensions, with or without known M5-brane probe configurations.

    更新日期:2020-01-23
  • UV-finite “old” conformal bootstrap on AdS: scalar case
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-21
    Boris L. Altshuler

    Abstract The double-trace from UV to IR flow subtraction of infinities used earlier for the UV-convergent calculations of the Witten tadpole diagrams being applied to the bubble self-energy diagrams gives for them the amazingly simple expressions in case of the four- dimensional boundary space. For every N = 1 … 4 in the O(N) symmetric scalar fields model with the conformal Hubbard-Stratonovich field there are three roots of the “old” conformal bootstrap spectral equations that obey unitarity bound demand.

    更新日期:2020-01-23
  • Relating quantum mechanics and kinetics of neutrino ascillations
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-21
    A. Kartavtsev

    Abstract Simultaneous treatment of neutrino oscillations and collisions in astrophysical environments requires the use of (quantum) kinetic equations. Despite major advances in the field of quantum kinetics, the structure of the kinetic equations and their consistency with the uncertainty principle are still debated. The goals of the present work are threefold. First, it clarifies the structure of the Liouville term in the presence of mixing. Second, we derive evolution equation for neutrinos propagating in vacuum or matter from the Schrödinger equation and show that in the relativistic limit its form matches the form of the (collisionless part of the) kinetic equation derived by Sigl and Raffelt. Third, by constructing solutions of the evolution equation from the known solutions of the Schrödinger equation, we show that the former also admits solutions consistent with the uncertainty principle and accounts for neutrino wave packet separation. The obtained results speak in favor of a (quantum) kinetic approach to the analysis of neutrino propagation in exploding supernovae where neutrino oscillations and collisions, as well as the effect of wave packet separation, might be equally important.

    更新日期:2020-01-23
  • Exclusive displaced hadronic signatures in the LHC forward region
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-20
    Xabier Cid Vidal, Yuhsin Tsai, Jose Zurita

    Abstract The LHCb detector provides accurate vertex reconstruction and hadronic particle identification, which make the experiment an ideal place to look for light long-lived particles (LLP) decaying into Standard Model (SM) hadrons. In contrast with the typical search strategy relying on energetic jets and a high multiplicity of tracks from the LLP decay, LHCb can identify LLPs in exclusive, specific hadronic final states. To illustrate the idea, we study the sensitivity of LHCb to an exotic Higgs decay h → SS, followed by the displaced decay of GeV-scale scalars into charged kaons S → K+K−. We show that the reconstruction of kaon vertices in narrow invariant mass windows can efficiently eliminate the combinatorial backgrounds from B-meson decays. While the same signal is extremely difficult to probe in the existing displaced jet searches at ATLAS/CMS, the LHCb search we propose can probe the branching ratio BR(h → SS) down to 0.1% (0.02%) level with 15 (300) fb−1 of data. We also apply this projected bound to two scenarios with Higgs portal couplings, where the scalar mediator S either couples to a) the SM quarks only, or b) to both quarks and leptons in the minimal flavor violation paradigm. In both scenarios we compare the reach of our proposed search with the expected constraints from ATLAS and CMS on the invisible Higgs width and with the constraints from rare B-decays studies at LHCb. We find that for 1 GeV < mS< 2 GeV and 0.5 mm ≲ cτ ≲ 10 mm our proposed search will be competitive with the ATLAS and CMS projections, while at the same time providing crucial information of the hadronic interactions of S, which can not be obtained from the indirect measurement of the Higgs invisible width.

    更新日期:2020-01-23
  • EFT of interacting spin-2 fields
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-21
    Lasma Alberte, Claudia de Rham, Arshia Momeni, Justinas Rumbutis, Andrew J. Tolley

    Abstract We consider the effective field theory of multiple interacting massive spin-2 fields. We focus on the case where the interactions are chosen so that the cutoff is the highest possible, and highlight two distinct classes of theories. In the first class, the mass eigenstates only interact through potential operators that carry no derivatives in unitary gauge at leading order. In the second class, a specific kinetic mixing between the mass eigenstates is included non-linearly. Performing a decoupling and ADM analysis, we point out the existence of a ghost present at a low scale for the first class of interactions. For the second class of interactions where kinetic mixing is included, we derive the full Λ3-decoupling limit and confirm the absence of any ghosts. Nevertheless both formulations can be used to consistently describe an EFT of interacting massive spin-2 fields which, for a suitable technically natural tuning of the EFT, have the same strong coupling scale Λ3. We identify the generic form of EFT corrections in each case. By using Galileon Duality transformations for the specific case of two massive spin-2 fields with suitable couplings, the decoupling limit theory is shown to be a bi-Galileon.

    更新日期:2020-01-23
  • Viscoelastic hydrodynamics and holography
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-21
    Jay Armas, Akash Jain

    Abstract We formulate the theory of nonlinear viscoelastic hydrodynamics of anisotropic crystals in terms of dynamical Goldstone scalars of spontaneously broken translational symmetries, under the assumption of homogeneous lattices and absence of plastic deformations. We reformulate classical elasticity effective field theory using surface calculus in which the Goldstone scalars naturally define the position of higher-dimensional crystal cores, covering both elastic and smectic crystal phases. We systematically incorporate all dissipative effects in viscoelastic hydrodynamics at first order in a long-wavelength expansion and study the resulting rheology equations. In the process, we find the necessary conditions for equilibrium states of viscoelastic materials. In the linear regime and for isotropic crystals, the theory includes the description of Kelvin-Voigt materials. Furthermore, we provide an entirely equivalent description of viscoelastic hydrodynamics as a novel theory of higher-form superfluids in arbitrary dimensions where the Goldstone scalars of partially broken generalised global symmetries play an essential role. An exact map between the two formulations of viscoelastic hydrodynamics is given. Finally, we study holographic models dual to both these formulations and map them one-to-one via a careful analysis of boundary conditions. We propose a new simple holographic model of viscoelastic hydrodynamics by adopting an alternative quantisation for the scalar fields.

    更新日期:2020-01-23
  • Triple (and quadruple) soft-gluon radiation in QCD hard scattering
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-20
    Stefano Catani, Dimitri Colferai, Alessandro Torrini

    Abstract We consider the radiation of three soft gluons in a generic process for multi- parton hard scattering in QCD. In the soft limit the corresponding scattering amplitude has a singular behaviour that is factorized and controlled by a colorful soft current. We compute the tree-level current for triple soft-gluon emission from both massless and massive hard partons. The three-gluon current is expressed in terms of maximally non-abelian irreducible correlations. We compute the soft behaviour of squared amplitudes and the colour correlations produced by the squared current. The radiation of one and two soft gluons leads to colour dipole correlations. Triple soft-gluon radiation produces in addition colour quadrupole correlations between the hard partons. We examine the soft and collinear singularities of the squared current in various energy ordered and angular ordered regions. We discuss some features of soft radiation to all-loop orders for processes with two and three hard partons. Considering triple soft-gluon radiation from three hard partons, colour quadrupole interactions break the Casimir scaling symmetry between quarks and gluons. We also present some results on the radiation of four soft gluons from two hard partons, and we discuss the colour monster contribution and its relation with the violation (and generalization) of Casimir scaling. We also compute the first correction of 𝒪(1/\( {N}_c^2 \)) to the eikonal formula for multiple soft-gluon radiation with strong energy ordering from two hard gluons.

    更新日期:2020-01-23
  • Enhanced Ehlers transformation and the Majumdar-Papapetrou-NUT spacetime
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-21
    Marco Astorino

    Abstract The transformation which adds (or removes) NUT charge when it is applied to electrovacuum, axisymmetric and stationary space-times is studied. After analysing the Ehlers and the Reina-Treves transformations we propose a new one, more precise in the presence of the Maxwell electromagnetic field. The enhanced Ehlers transformation proposed turns out to act as a gravitomagnetic duality, analogously to the electromagnetic duality, but for gravity: it rotates the mass charge into the gravomagnetic (or NUT) charge. As an example the Kerr-Newman-NUT black hole is obtained with the help of this enhanced transformation. Moreover a new analytical exact solution is built adding the NUT charge to a double charged black hole, at equilibrium. It describes the non-extremal generalisation of the Majumdar-Papapetrou-NUT solution. From the near-horizon analysis, its microscopic entropy, according to the Kerr/CFT correspondence, is found and the second law of black hole thermodynamics is discussed.

    更新日期:2020-01-22
  • Finite volume expectation values in the sine-Gordon model
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-21
    Árpád Hegedűs

    Abstract Using the fermionic basis discovered in the 6-vertex model, we derive exact formulas for the expectation values of local operators of the sine-Gordon theory in any eigenstate of the Hamiltonian. We tested our formulas in the pure multi-soliton sector of the theory. In the ultraviolet limit, we checked our results against Liouville 3-point functions, while in the infrared limit, we evaluated our formulas in the semi-classical limit and compared them up to 2-particle contributions against the semi-classical limit of the previously conjectured LeClair-Mussardo type formula. Complete agreement was found in both cases.

    更新日期:2020-01-22
  • Scalar gauge dynamics and Dark Matter
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-21
    Dario Buttazzo, Luca Di Luzio, Parsa Ghorbani, Christian Gross, Giacomo Landini, Alessandro Strumia, Daniele Teresi, Jin-Wei Wang

    Abstract We consider theories with one gauge group (SU, SO or Sp) and one scalar in a two-index representation. The renormalizable action often has accidental symmetries (such as global U(1) or unusual group parities) that lead to one or more stable states, providing Dark Matter candidates. We discuss the confined phase(s) of each theory and compute the two Higgs phases, finding no generic dualities among them. Discrete gauge symmetries can arise and accidental symmetries can be broken, possibly giving pseudo-Goldstone Dark Matter. Dark Matter candidates can have a complicated sub-structure characteristic of each group and can be accompanied by extra dark radiation.

    更新日期:2020-01-22
  • Aspects of nonlinear effect on black hole superradiance
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-21
    Hajime Fukuda, Kazunori Nakayama

    Abstract Under some conditions, light boson fields grow exponentially around a rotating black hole, called the superradiance instability. We discuss effects of nonlinear interactions of the boson on the instability. In particular, we focus on the effect of the particle production and show that the growth of the boson cloud may be saturated much before the black hole spin is extracted by the boson cloud, while the nonlinear interactions also induce the boson emission. For application, we revisit the superradiant instability of the standard model photon, axion and hidden photon.

    更新日期:2020-01-22
  • Non-local order parameters and quantum entanglement for fermionic topological field theories
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-20
    Kansei Inamura, Ryohei Kobayashi, Shinsei Ryu

    Abstract We study quantized non-local order parameters, constructed by using partial time-reversal and partial reflection, for fermionic topological phases of matter in one spatial dimension protected by an orientation reversing symmetry, using topological quantum field theories (TQFTs). By formulating the order parameters in the Hilbert space of state sum TQFT, we establish the connection between the quantized non-local order parameters and the underlying field theory, clarifying the nature of the order parameters as topological invariants. We also formulate several entanglement measures including the entanglement negativity on state sum spin TQFT, and describe the exact correspondence of the entanglement measures to path integrals on a closed surface equipped with a specific spin structure.

    更新日期:2020-01-22
  • Production asymmetry of ν τ neutrinos and ν¯τ$$ {\overline{\nu}}_{\tau } $$ antineutrinos from a fixed target experiment SHiP
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-20
    Rafał Maciuła, Antoni Szczurek, Jakub Zaremba, Izabela Babiarz

    Abstract We discuss how to calculate cross sections as well as rapidity, transverse momentum and energy distributions of ντ and \( {\overline{\nu}}_{\tau } \) produced from the direct \( {D}_s^{\pm}\to {\nu}_{\tau }/{\overline{\nu}}_{\tau } \) and chain \( {D}_s^{\pm}\to {\tau}^{+}/{\tau}^{-}\to {\nu}_{\tau }/{\overline{\nu}}_{\tau } \) decays in p+96 Mo scattering with proton beam Elab = 400 GeV i.e. at \( {\sqrt{s}}_{NN} \) = 27.4 GeV. The τ decays are simulated with the help of the Tauola code and include multiple decay channels of τ in amounts proportional to their branching ratios. In our calculations we include \( {D}_s^{\pm } \) from charm fragmentation c →\( {D}_s^{+} \) and \( \overline{c}\to {D}_s^{-} \) as well as those from subleading fragmentation of strange quarks/antiquarks s →\( {D}_s^{-} \) and \( \overline{s}\to {D}_s^{+} \). The \( s\ne \overline{s} \) asymmetry of the strange quark content of proton is included. The different contributions to \( {D}_s^{+} \) and \( {\nu}_{\tau }/{\overline{\nu}}_{\tau } \) are shown explicitly. We discuss and quantify a not discussed so far effect of asymmetries for production of ντ and \( {\overline{\nu}}_{\tau } \) caused by subleading fragmentation mechanism and discuss related uncertainties. A potential measurement of the asymmetry is discussed. Estimates of a number of observed \( {\nu}_{\tau }/{\overline{\nu}}_{\tau } \) in the \( {\nu}_{\tau }/{\overline{\nu}}_{\tau } \) +208Pb reaction, with 2m long target are given with the help of the NuWro program. We refer also to the production of the high-energy (anti)neutrinos in the atmosphere.

    更新日期:2020-01-22
  • Complexity for charged thermofield double states
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-20
    Mehregan Doroudiani, Ali Naseh, Reza Pirmoradian

    Abstract We study Nielsen’s circuit complexity for a charged thermofield double state (cTFD) of free complex scalar quantum field theory in the presence of background electric field. We show that the ratio of the complexity of formation for cTFD state to the thermo- dynamic entropy is finite and it depends just on the temperature and chemical potential. Moreover, this ratio smoothly approaches the value for real scalar theory. We compare our field theory calculations with holographic complexity of charged black holes and confirm that the same cost function which is used for neutral case continues to work in presence of U(1) background field. For t > 0, the complexity of cTFD state evolves in time and contrasts with holographic results, it saturates after a time of the order of inverse temper- ature. This discrepancy can be understood by the fact that holographic QFTs are actually strong interacting theories, not free ones.

    更新日期:2020-01-22
  • Semi-classical Virasoro blocks: proof of exponentiation
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-20
    Mert Beşken, Shouvik Datta, Per Kraus

    Abstract Virasoro conformal blocks are expected to exponentiate in the limit of large central charge c and large operator dimensions hi, with the ratios hi/c held fixed. We prove this by employing the oscillator formulation of the Virasoro algebra and its representations. The techniques developed are then used to provide new derivations of some standard results on conformal blocks.

    更新日期:2020-01-21
  • Coscattering in next-to-minimal dark matter and split supersymmetry
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-20
    F. Brümmer

    Abstract In some models of thermal relic dark matter, the relic abundance may be set by inelastic scattering processes (rather than annihilations) becoming inefficient as the universe cools down. This effect has been called coscattering. We present a procedure to numerically solve the full momentum-dependent Boltzmann equations in coscattering, which allows for a precise calculation of the dark matter relic density including the effects of early kinetic decoupling. We apply our method to a simple model, containing a fermionic SU(2) triplet and a fermionic singlet with electroweak-scale masses, at small triplet-singlet mixing. The relic density can be set by either coannihilation or, at values of the mixing angle θ ≲ 10−5, by coscattering. We identify the parameter ranges which give rise to the observed relic abundance. As a special case, we study bino-like dark matter in split supersymmetry at large μ.

    更新日期:2020-01-21
  • Anomaly inflow, accidental symmetry, and spontaneous symmetry breaking
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-20
    Ibrahima Bah, Federico Bonetti

    Abstract We consider the 6d (1,0) SCFT on a stack of N M5-branes probing a ℂ2/ℤ2 singularity. In particular, we study its compactifications to four dimensions on a smooth genus-g Riemann surface with non-trivial flavor flux, yielding a family of 4d CFTs. By tracking the M-theory origin of the global symmetries of the 4d CFTs, we detect the emergence of an accidental symmetry and the spontaneous symmetry breaking of a U(1) generator. These effects are visible from geometric considerations and not apparent from the point of view of the compactification of the 6d field theory. These phenomena leave an imprint on the ’t Hooft anomaly polynomial of the 4d CFTs, which is obtained from recently developed anomaly inflow methods in M-theory [1]. In the large-N limit, we identify the gravity dual of the 4d setups to be a class of smooth AdS5 solutions first discussed by Gauntlett-Martelli-Sparks-Waldram. Using our anomaly polynomial, we compute the conformal central charge and a non-Abelian flavor central charge at large N , finding agreement with the holographic predictions.

    更新日期:2020-01-21
  • The electroweak effective field theory from on-shell amplitudes
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-20
    Gauthier Durieux, Teppei Kitahara, Yael Shadmi, Yaniv Weiss

    Abstract We apply on-shell methods to the bottom-up construction of electroweak amplitudes, allowing for both renormalizable and non-renormalizable interactions. We use the little-group covariant massive-spinor formalism, and flesh out some of its details along the way. Thanks to the compact form of the resulting amplitudes, many of their properties, and in particular the constraints of perturbative unitarity, are easily seen in this formalism. Our approach is purely bottom-up, assuming just the standard-model electroweak spectrum as well as the conservation of electric charge and fermion number. The most general massive three-point amplitudes consistent with these symmetries are derived and studied in detail, as the primary building blocks for the construction of scattering amplitudes. We employ a simple argument, based on tree-level unitarity of four-point amplitudes, to identify the three-point amplitudes that are non-renormalizable at tree level. This bottom-up analysis remarkably reproduces many low-energy relations implied by electroweak symmetry through the standard-model Higgs mechanism and beyond it. We then discuss four-point amplitudes. The gluing of three-point amplitudes into four-point amplitudes in the massive spinor helicity formalism is clarified. As an example, we work out the ψcψ Zh amplitude, including also the non-factorizable part. The latter is an all-order expression in the effective-field-theory expansion. Further constraints on the couplings are obtained by requiring perturbative unitarity. In the ψcψ Zh example, one for instance obtains the renormalizable-level relations between vector and fermion masses and gauge and Yukawa couplings. We supplement our bottom-up derivations with a matching of three- and fourpoint amplitude coefficients onto the standard-model effective field theory (SMEFT) in the broken electroweak phase. This establishes the correspondence with the usual Lagrangian approach and paves the way for SMEFT computations in the on-shell formalism.

    更新日期:2020-01-21
  • Maximum value of the spin-independent cross section in the 2HDM+a
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-20
    Tomohiro Abe, Motoko Fujiwara, Junji Hisano, Yutaro Shoji

    Abstract We investigate the maximum value of the spin-independent cross section (σSI) in a dark matter (DM) model called the two-Higgs doublet model + a (2HDM+a). This model can explain the measured value of the DM energy density by the freeze-out mechanism. Also, σSI is suppressed by the momentum transfer at the tree level, and loop diagrams give the leading contribution to it. The model prediction of σSI highly depends on values of c1 and c2 that are the quartic couplings between the gauge singlet CP-odd state (a0) and Higgs doublet fields (H1 and H2), \( {c}_1{a}_0^2{H}_1^{\dagger }{H}_1\kern0.33em and\kern0.33em {c}_2{a}_0^2{H}_2^{\dagger }{H}_2 \). We discuss the upper and lower bounds on c1 and c2 by studying the stability of the electroweak vacuum, the condition for the potential bounded from the below, and the perturbative unitarity. We find that the condition for the stability of the electroweak vacuum gives upper bounds on c1 and c2. The condition for the potential to be bounded from below gives lower bounds on c1 and c2. It also constrains the mixing angle between the two CP-odd states. The perturbative unitarity bound gives the upper bound on the Yukawa coupling between the dark matter and a0 and the quartic coupling of a0. Under these theoretical constraints, we find that the maximum value of the σSI is ∼ 5 × 10−47 cm2 for mA = 600 GeV, and the LZ and XENONnT experiments can see the DM signal predicted in this model near future.

    更新日期:2020-01-21
  • The holographic landscape of symmetric product orbifolds
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-20
    Alexandre Belin, Alejandra Castro, Christoph A. Keller, Beatrix Mühlmann

    Abstract We investigate the growth of coefficients in the elliptic genus of symmetric product orbifolds at large central charge. We find that this landscape decomposes into two regions. In one region, the growth of the low energy states is Hagedorn, which indicates a stringy dual. In the other, the growth is much slower, and compatible with the spectrum of a supergravity theory on AdS3. We provide a simple diagnostic which places any symmetric product orbifold in either region. We construct a class of elliptic genera with such supergravity-like growth, indicating the possible existence of new realizations of AdS3/CFT2 where the bulk is a semi-classical supergravity theory. In such cases, we give exact expressions for the BPS degeneracies, which could be matched with the spectrum of perturbative states in a dual supergravity description.

    更新日期:2020-01-21
  • Realizing IR theories by projections in the UV
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-17
    Fabian Klos, Daniel Roggenkamp

    Abstract We show how (topologically twisted) quantum field theories in the IR of bulk RG flows can be represented within the respective UV theories by means of codimenion- one projection defects. Indeed, from this perspective, RG flows of bulk theories can be described in terms of RG flows of the codimension-one identity defect in the fixed UV bulk theory. We illustrate this in the example of RG flows between supersymmetric Landau- Ginzburg orbifold models, for which the respective defects can be described in terms of matrix factorizations.

    更新日期:2020-01-21
  • Properties of the new N$$ \mathcal{N} $$ = 1 AdS 4 vacuum of maximal supergravity
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-17
    Nikolay Bobev, Thomas Fischbacher, Krzysztof Pilch

    Abstract The recent comprehensive numerical study of critical points of the scalar potential of four-dimensional \( \mathcal{N} \) = 8, SO(8) gauged supergravity using Machine Learning software in [1] has led to a discovery of a new \( \mathcal{N} \) = 1 vacuum with a triality-invariant SO(3) symmetry. Guided by the numerical data for that point, we obtain a consistent SO(3) × ℤ2-invariant truncation of the \( \mathcal{N} \) = 8 theory to an \( \mathcal{N} \) = 1 supergravity with three chiral multiplets. Critical points of the truncated scalar potential include both the \( \mathcal{N} \) = 1 point as well as two new non-supersymmetric and perturbatively unstable points not found by previous searches. Studying the structure of the submanifold of SO(3) × ℤ2-invariant supergravity scalars, we find that it has a simple interpretation as a submanifold of the 14-dimensional \( {\mathbb{Z}}_2^3 \)-invariant scalar manifold (SU(1, 1)/U(1))7, for which we find a rather remarkable superpotential whose structure matches the single bit error correcting (7, 4) Hamming code. This 14-dimensional scalar manifold contains approximately one quarter of the known critical points. We also show that there exists a smooth supersymmetric domain wall which interpolates between the new \( \mathcal{N} \) = 1 AdS4 solution and the maximally supersymmetric AdS4 vacuum. Using holography, this result indicates the existence of an \( \mathcal{N} \) = 1 RG flow from the ABJM SCFT to a new strongly interacting conformal fixed point in the IR.

    更新日期:2020-01-21
  • Collider phenomenology of a gluino continuum
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-17
    Christina Gao, Ali Shayegan Shirazi, John Terning

    Abstract Continuum supersymmetry is a class of models in which the supersymmetric partners together with part of the standard model come from a conformal sector, broken in the IR near the TeV scale. Such models not only open new doors for addressing the problems of the standard model, but also have unique signatures at hadron colliders, which might explain why we have not yet seen any superpartners at the LHC. Here we use gauge- gravity duality to model the conformal sector, generate collider simulations, and finally analyze continuum gluino signatures at the LHC. Due to the increase in the number of jets produced the bounds are weaker than for the minimal supersymmetric standard model with the same gluino mass threshold.

    更新日期:2020-01-21
  • Safe use of jet pull
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-17
    Andrew Larkoski, Simone Marzani, Chang Wu

    Abstract Jet pull is an observable designed to probe colour flow between jets. Thus far, a particular projection of the pull vector, the pull angle, has been employed to distinguish colour flow between jets produced by a colour singlet or an octet decay. This is of particular importance in order to separate the decay of a Higgs boson to a pair of bottom quarks from the QCD background. However, the pull angle is not infra-red and collinear (IRC) safe. In this paper we introduce IRC safe projections of the pull vector that exhibit good sensitivity to colour flow, while maintaining calculability. We calculate these distributions to next-to- leading logarithmic accuracy, in the context of the hadronic decay of a Higgs boson, and compare these results to Monte Carlo simulations. This study allows us to define an IRC safe version of the pull angle in terms of asymmetry distributions. Furthermore, because of their sensitivity to wide-angle soft radiation, we anticipate that these asymmetries can play an important role in assessing subleading colour correlations and their modelling in general-purpose Monte Carlo parton showers.

    更新日期:2020-01-21
  • Dynamics of phase separation from holography
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-17
    Maximilian Attems, Yago Bea, Jorge Casalderrey-Solana, David Mateos, Miguel Zilhão

    Abstract We use holography to develop a physical picture of the real-time evolution of the spinodal instability of a four-dimensional, strongly-coupled gauge theory with a first-order, thermal phase transition. We numerically solve Einstein’s equations to follow the evolution, in which we identify four generic stages: a first, linear stage in which the instability grows exponentially; a second, non-linear stage in which peaks and/or phase domains are formed; a third stage in which these structures merge; and a fourth stage in which the system finally relaxes to a static, phase-separated configuration. On the gravity side the latter is described by a static, stable, inhomogeneous horizon. We conjecture and provide evidence that all static, non-phase separated configurations in large enough boxes are dynamically unstable. We show that all four stages are well described by the constitutive relations of second-order hydrodynamics that include all second-order gradients that are purely spatial in the local rest frame. In contrast, a Müller-Israel-Stewart-type formulation of hydrodynamics fails to provide a good description for two reasons. First, it misses some large, purely-spatial gradient corrections. Second, several second-order transport coefficients in this formulation, including the relaxation times τπ and τΠ, diverge at the points where the speed of sound vanishes.

    更新日期:2020-01-21
  • Correlators of the symmetric product orbifold
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-17
    Andrea Dei, Lorenz Eberhardt

    Abstract We exploit null vectors of the fractional Virasoro algebra of the symmetric product orbifold to compute correlation functions of twist fields in the large N limit. This yields a new method to derive correlation functions in these orbifold CFTs that is purely based on the symmetry algebra. We explore various generalisations, such as subleading (torus) contributions or correlation functions of other fields than the bare twist fields. We comment on the consequences of our computation for the AdS3/CFT2 correspondence.

    更新日期:2020-01-21
  • Phenomenology of keV scale sterile neutrino dark matter with S 4 flavor symmetry
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-17
    Nayana Gautam, Mrinal Kumar Das

    Abstract We study the possibility of simultaneously addressing neutrino phenomenology and the dark matter in the framework of inverse seesaw. The model is the extension of the standard model by the addition of two right handed neutrinos and three sterile fermions which leads to a light sterile state with the mass in the keV range along with three light active neutrino states. The lightest sterile neutrino can account for a feasible dark matter (DM) candidate. We present a S4 flavor symmetric model which is further augmented by Z4 × Z3 symmetry to constrain the Yukawa Lagrangian. The structures of the mass matrices involved in inverse seesaw within the S4 framework naturally give rise to correct neutrino mass matrix with non-zero reactor mixing angle θ13. In this framework, we conduct a detailed numerical analysis both for normal hierarchy as well as inverted hierarchy to obtain dark matter mass and DM-active mixing which are the key factors for considering sterile neutrino as a viable dark matter candidate. We constrain the parameter space of the model from the latest cosmological bounds on the mass of the dark matter and DM-active mixing.

    更新日期:2020-01-21
  • Higher-form symmetries, Bethe vacua, and the 3d-3d correspondence
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-17
    Julius Eckhard, Heeyeon Kim, Sakura Schäfer-Nameki, Brian Willett

    Abstract By incorporating higher-form symmetries, we propose a refined definition of the theories obtained by compactification of the 6d (2, 0) theory on a three-manifold M3. This generalization is applicable to both the 3d \( \mathcal{N} \) = 2 and \( \mathcal{N} \) = 1 supersymmetric reductions. An observable that is sensitive to the higher-form symmetries is the Witten index, which can be computed by counting solutions to a set of Bethe equations that are determined by M3. This is carried out in detail for M3 a Seifert manifold, where we compute a refined version of the Witten index. In the context of the 3d-3d correspondence, we complement this analysis in the dual topological theory, and determine the refined counting of flat connections on M3, which matches the Witten index computation that takes the higher-form symmetries into account.

    更新日期:2020-01-21
  • Chaotic dynamics of string around charged black brane with hyperscaling violation
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-17
    Da-Zhu Ma, Dan Zhang, Guoyang Fu, Jian-Pin Wu

    Abstract By fast Lyapunov indicator (FLI), we study the chaotic dynamics of closed string around charged black brane with hyperscaling violation (HV). The Hawking temperature, Lifshitz dynamical exponent and HV exponent together affect the chaotic dynamics of this system. The temperature plays the role of driving the closed string to escape to infinity. There is a threshold value z∗ = 2, below which the string is captured by the black brane no matter where the string is placed at the beginning. However, when z > 2, the string escapes to infinity if it is placed near the black brane at the beginning, but if the initial position of string is far away from the black brane, it oscillates around the black brane till eternity, which is a quasi-periodic motion. HV exponent plays the role of driving the string falling into the black brane. With the increase of HV exponent θ, the falling velocity becomes faster. We find that when we heat the system with large HV exponent, the chaotic system does not essentially changes. It indicates that the HV exponent plays a very important role in determining the state of the chaotic system. Also we study the effect from the winding number of the string. The study indicates that the chaotic dynamics of the string is insensitive to the winding number.

    更新日期:2020-01-21
  • Searches for other vacua. Part II. A new Higgstory at the cosmological collider
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-17
    Anson Hook, Junwu Huang, Davide Racco

    Abstract The detection of an oscillating pattern in the bispectrum of density perturbations could suggest the existence of a high-energy second minimum in the Higgs potential. If the Higgs field resided in this new minimum during inflation and was brought back to the electroweak vacuum by thermal corrections during reheating, the coupling of Standard Model particles to the inflaton would leave its imprint on the bispectrum. We focus on the fermions, whose dispersion relation can be modified by the coupling to the inflaton, leading to an enhanced particle production during inflation even if their mass during inflation is larger than the Hubble scale. This results in a large non-analytic contribution to non-Gaussianities, with an amplitude fNL as large as 100 in the squeezed limit, potentially detectable in future 21-cm surveys. Measuring the contributions from two fermions would allow us to compute the ratio of their masses, and to ascribe the origin of the signal to a new Higgs minimum. Such a discovery would be a tremendous step towards understanding the vacuum instability of the Higgs potential, and could have fascinating implications for anthropic considerations.

    更新日期:2020-01-21
  • Excitations in strict 2-group higher gauge models of topological phases
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-17
    Alex Bullivant, Clement Delcamp

    Abstract We consider an exactly solvable model for topological phases in (3+1) d whose input data is a strict 2-group. This model, which has a higher gauge theory interpretation, provides a lattice Hamiltonian realisation of the Yetter homotopy 2-type topological quantum field theory. The Hamiltonian yields bulk flux and charge composite excitations that are either point-like or loop-like. Applying a generalised tube algebra approach, we reveal the algebraic structure underlying these excitations and derive the irreducible modules of this algebra, which in turn classify the elementary excitations of the model. As a further application of the tube algebra approach, we demonstrate that the ground state subspace of the three-torus is described by the central subalgebra of the tube algebra for torus boundary, demonstrating the ground state degeneracy is given by the number of elementary loop-like excitations.

    更新日期:2020-01-21
  • Axion dark matter, proton decay and unification
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-16
    Pavel Fileviez Pérez, Clara Murgui, Alexis D. Plascencia

    We discuss the possibility to predict the QCD axion mass in the context of grand unified theories. We investigate the implementation of the DFSZ mechanism in the context of renormalizable SU(5) theories. In the simplest theory, the axion mass can be predicted with good precision in the range ma = (2–16) neV, and there is a strong correlation between the predictions for the axion mass and proton decay rates. In this context, we predict an upper bound for the proton decay channels with antineutrinos, \( \tau \left(p\to {K}^{+}\overline{\nu}\right)\lesssim 4\times {10}^{37} \) yr and \( \tau \left(p\to {\pi}^{+}\overline{\nu}\right)\lesssim 2\times {10}^{36} \) yr. This theory can be considered as the minimal realistic grand unified theory with the DFSZ mechanism and it can be fully tested by proton decay and axion experiments.

    更新日期:2020-01-17
  • Composite Higgs at high transverse momentum
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-16
    Andrea Banfi, Barry M. Dillon, Wissarut Ketaiam, Sandra Kvedaraitė

    In this paper we explore composite Higgs scenarios through the effects of light top-partners in Higgs+Jet production at the LHC. The pseudo-Goldstone boson nature of the Higgs field means that single-Higgs production via gluon fusion is insensitive to the mass spectrum of the top-partners. However in associated production this is not the case, and new physics scales may be probed. In the course of the work we consider scenarios with both one and two light top-partner multiplets in the spectrum of composite states. In compliance with perturbativity and experimental constraints, we study corrections to the Higgs couplings and the effects that the light top-partner multiplets have on the transverse momentum spectrum of the Higgs. Interestingly, we find that the corrections to the Standard Model expectation depend strongly on the representation of the top-partners in the global symmetry.

    更新日期:2020-01-17
  • Implications of ANEC for SCFTs in four dimensions
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-16
    Andrea Manenti, Andreas Stergiou, Alessandro Vichi

    Abstract We explore consequences of the Averaged Null Energy Condition (ANEC) for scaling dimensions ∆ of operators in four-dimensional \( \mathcal{N} \) = 1 superconformal field theories. We show that in many cases the ANEC bounds are stronger than the corresponding unitarity bounds on ∆. We analyze in detail chiral operators in the \( \left(\frac{1}{2}j,0\right) \) Lorentz representation and prove that the ANEC implies the lower bound \( \Delta \ge \frac{3}{2}j \), which is stronger than the corresponding unitarity bound for j > 1. We also derive ANEC bounds on \( \left(\frac{1}{2}j,0\right) \) operators obeying other possible shortening conditions, as well as general \( \left(\frac{1}{2}j,0\right) \) operators not obeying any shortening condition. In both cases we find that they are typically stronger than the corresponding unitarity bounds. Finally, we elucidate operator-dimension constraints that follow from our \( \mathcal{N} \) = 1 results for multiplets of \( \mathcal{N} \) = 2, 4 superconformal theories in four dimensions. By recasting the ANEC as a convex optimization problem and using standard semidefinite programming methods we are able to improve on previous analyses in the literature pertaining to the nonsupersymmetric case.

    更新日期:2020-01-17
  • Reheating after swampland conjecture
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-16
    Vahid Kamali

    Abstract The evolution of the universe started from a hot and dense Big Bang point. Temperature fluctuation map of cosmic microwave background (CMB) radiation and initial seeds of large scale structures (LSS) are explained by an inflationary period in a very early time. Inflaton as quanta of the inflation field is responsible for the accelerated expansion of the universe. Potentials of the self-interacting single field models are constrained by observational data as well as quantum gravity. Some forms of the potential are rolled out by data of Planck satellite and some of them by quantum gravity constraints. In the standard model of inflation or cold inflation firstly universe expands where the inflaton rolls the nearly flat part of the potential and in the second part, the universe reheats where the inflaton oscillates around the minimum of the potential which leads to thermalized radiation dominated universe. String theory as the best model of quantum gravity forbids the oscillation around the minimum of the potential during the thermalized epoch of the reheating. But in the warm model of inflation thermalization happens during the accelerated expansion of the universe where the inflaton rolls nearly steep potential and the universe will be radiation dominated without any separated reheating epoch.

    更新日期:2020-01-17
  • Leading-logarithmic threshold resummation of Higgs production in gluon fusion at next-to-leading power
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-16
    Martin Beneke, Mathias Garny, Sebastian Jaskiewicz, Robert Szafron, Leonardo Vernazza, Jian Wang

    Abstract We sum the leading logarithms \( {\alpha}_s^n{\ln}^{2n-1}\left(1-z\right) \), n = 1, 2, . . . , near the kinematic threshold \( z={m}_H^2/\hat{s}\to 1 \) at next-to-leading power in the expansion in (1 − z) for Higgs production in gluon fusion. We highlight the new contributions compared to Drell-Yan production in quark-antiquark annihilation and show that the final result can be obtained to all orders by the substitution of the colour factor CF → CA, confirming previous fixed-order results. We also provide a numerical analysis of the next-to-leading power leading logarithms, which indicates that they are numerically relevant.

    更新日期:2020-01-17
  • Erratum to: Quantum tasks in holography
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-15
    Alex May

    As one of the results in this article, I stated a connection between bulk causal structure and boundary entanglement in the AdS/CFT correspondence.

    更新日期:2020-01-17
  • Sequences of 6 d SCFTs on generic Riemann surfaces
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-15
    Shlomo S. Razamat, Evyatar Sabag

    We consider compactifications of 6d minimal (DN+3, DN+3) type conformal matter SCFTs on a generic Riemann surface. We derive the theories corresponding to three punctured spheres (trinions) with three maximal punctures, from which one can construct models corresponding to generic surfaces. The trinion models are simple quiver theories with \( \mathcal{N} \) = 1 SU(2) gauge nodes. One of the three puncture non abelian symmetries is emergent in the IR. The derivation of the trinions proceeds by analyzing RG flows between conformal matter SCFTs with different values of N and relations between their subsequent reductions to 4d. In particular, using the flows we first derive trinions with two maximal and one minimal punctures, and then we argue that collections of N minimal punctures can be interpreted as a maximal one. This suggestion is checked by matching the properties of the 4d models such as ’t Hooft anomalies, symmetries, and the structure of the conformal manifold to the expectations from 6d. We then use the understanding that collections of minimal punctures might be equivalent to maximal ones to construct trinions with three maximal punctures, and then 4d theories corresponding to arbitrary surfaces, for 6d models described by two M5 branes probing a ℤk singularity. This entails the introduction of a novel type of maximal puncture. Again, the suggestion is checked by matching anomalies, symmetries and the conformal manifold to expectations from six dimensions. These constructions thus give us a detailed understanding of compactifications of two sequences of six dimensional SCFTs to four dimensions.

    更新日期:2020-01-17
  • Solution of the self-dual Φ 4 QFT-model on four-dimensional Moyal space
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-15
    Harald Grosse, Alexander Hock, Raimar Wulkenhaar

    Abstract Previously the exact solution of the planar sector of the self-dual Φ4-model on 4-dimensional Moyal space was established up to the solution of a Fredholm integral equation. This paper solves, for any coupling constant λ > −\( \frac{1}{\uppi} \), the Fredholm equation in terms of a hypergeometric function and thus completes the construction of the planar sector of the model. We prove that the interacting model has spectral dimension 4 − 2 \( \frac{\arcsin \left(\uplambda \uppi \right)}{\uppi} \) for |λ| <\( \frac{1}{\uppi} \). It is this dimension drop which for λ > 0 avoids the triviality problem of the matricial \( {\varPhi}_4^4 \)-model. We also establish the power series approximation of the Fredholm solution to all orders in λ. The appearing functions are hyperlogarithms defined by iterated integrals, here of alternating letters 0 and −1. We identify the renormalisation parameter which gives the same normalisation as the ribbon graph expansion.

    更新日期:2020-01-16
  • Completing the scalar and fermionic universal one-loop effective action
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-15
    Michael Krämer, Benjamin Summ, Alexander Voigt

    Abstract We extend the known Universal One-Loop Effective Action (UOLEA) by all operators which involve scalars and fermions, not including contributions arising from open covariant derivatives. Our generic analytic expressions for the one-loop Wilson coefficients of effective operators up to dimension six allow for an application of the UOLEA to a broader class of UV-complete models. We apply our generic results to various effective theories of supersymmetric models, where different supersymmetric particles are integrated out at a high mass scale.

    更新日期:2020-01-16
  • An exact symmetry in λ -deformed CFTs
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-15
    George Georgiou, Eftychia Sagkrioti, Konstantinos Sfetsos, Konstantinos Siampos

    Abstract We consider λ-deformed current algebra CFTs at level k, interpolating between an exact CFT in the UV and a PCM in the IR. By employing gravitational techniques, we derive the two-loop, in the large k expansion, β-function. We find that this is covariant under a remarkable exact symmetry involving the coupling λ, the level k and the adjoint quadratic Casimir of the group. Using this symmetry and CFT techniques, we are able to compute the Zamolodchikov metric, the anomalous dimension of the bilinear operator and the Zamolodchikov C -function at two-loops in the large k expansion, as exact func- tions of the deformation parameter. Finally, we extend the above results to λ-deformed parafermionic algebra coset CFTs which interpolate between exact coset CFTs in the UV and a symmetric coset space in the IR.

    更新日期:2020-01-16
  • A subtraction scheme for massive QED
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-15
    T. Engel, A. Signer, Y. Ulrich

    Abstract We present an extension of the FKS subtraction scheme beyond next-to-leading order to deal with soft singularities in fully differential calculations within QED with mas- sive fermions. After a detailed discussion of the next-to-next-to-leading order case, we show how to extend the scheme to even higher orders in perturbation theory. As an application we discuss the computation of the next-to-next-to-leading order QED corrections to the muon decay and present differential results with full electron mass dependence.

    更新日期:2020-01-16
  • Complexity geometry and Schwarzian dynamics
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-15
    Henry W. Lin, Leonard Susskind

    A celebrated feature of SYK-like models is that at low energies, their dynamics reduces to that of a single variable. In many setups, this “Schwarzian” variable can be interpreted as the extremal volume of the dual black hole, and the resulting dynamics is simply that of a 1D Newtonian particle in an exponential potential. On the complexity side, geodesics on a simplified version of Nielsen’s complexity geometry also behave like a 1D particle in a potential given by the angular momentum barrier. The agreement between the effective actions of volume and complexity succinctly summarizes various strands of evidence that complexity is closely related to the dynamics of black holes.

    更新日期:2020-01-16
  • Bosonic sectorized strings and the ( DF ) 2 theory
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-15
    Thales Azevedo, Renann Lipinski Jusinskas, Matheus Lize

    Abstract In this work, we investigate the bosonic chiral string in the sectorized inter- pretation, computing its spectrum, kinetic action and 3-point amplitudes. As expected, the bosonic ambitwistor string is recovered in the tensionless limit. We also consider an extension of the bosonic model with current algebras. In that case, we compute the effective action and show that it is essentially the same as the action of the mass-deformed (DF )2 theory found by Johansson and Nohle. Aspects which might seem somewhat contrived in the original construction — such as the inclusion of a scalar transforming in some real representation of the gauge group — are shown to follow very naturally from the worldsheet formulation of the theory.

    更新日期:2020-01-16
  • N$$ \mathcal{N} $$ -extended D = 4 supergravity, unconventional SUSY and graphene
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-15
    L. Andrianopoli, B.L. Cerchiai, R. D’Auria, A. Gallerati, R. Noris, M. Trigiante, J. Zanelli

    Abstract We derive a 2+1 dimensional model with unconventional supersymmetry at the boundary of an AdS4\( \mathcal{N} \) -extended supergravity, generalizing previous results. The (unconventional) extended supersymmetry of the boundary model is instrumental in describing, within a top-down approach, the electronic properties of graphene-like 2D materials at the two Dirac points, K and K′. The two valleys correspond to the two independent sectors of the OSp(p|2) × OSp(q|2) boundary model in the p = q case, which are related by a parity transformation. The Semenoff and Haldane-type masses entering the corresponding Dirac equations are identified with the torsion parameters of the substrate in the model.

    更新日期:2020-01-16
  • Approximate symmetries and gravity
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-15
    Sylvain Fichet, Prashant Saraswat

    There are strong reasons to believe that global symmetries of quantum theories cannot be exact in the presence of gravity. While this has been argued at the qualitative level, establishing a quantitative statement is more challenging. In this work we take new steps towards quantifying symmetry violation in EFTs with gravity. First, we evaluate global charge violation by microscopic black holes present in a thermal system, which represents an irreducible, universal effect at finite temperature. Second, based on general QFT considerations, we propose that local symmetry-violating processes should be faster than black hole-induced processes at any sub-Planckian temperature. Such a proposal can be seen as part of the “swampland” program to constrain EFTs emerging from quantum gravity. Considering an EFT perspective, we formulate a con- jecture which requires the existence of operators violating global symmetry and places quantitative bounds on them. We study the interplay of our conjecture with emergent symmetries in QFT. In models where gauged U(1)’s enforce accidental symmetries, we find that constraints from the Weak Gravity Conjecture can ensure that our conjecture is satisfied. We also study the consistency of the conjecture with QFT models of emergent symmetries such as extradimensional localization, the Froggatt-Nielsen mechanism, and the clockwork mechanism.

    更新日期:2020-01-16
  • Revisiting non-Gaussianity in multifield inflation with curved field space
    J. High Energy Phys. (IF 5.833) Pub Date : 2020-01-14
    Sebastian Garcia-Saenz, Lucas Pinol, Sébastien Renaux-Petel

    Recent studies of inflation with multiple scalar fields have highlighted the importance of non-canonical kinetic terms in novel types of inflationary solutions. This motivates a thorough analysis of non-Gaussianities in this context, which we revisit here by studying the primordial bispectrum in a general two-field model. Our main result is the complete cubic action for inflationary fluctuations written in comoving gauge, i.e. in terms of the curvature perturbation and the entropic mode. Although full expressions for the cubic action have already been derived in terms of fields fluctuations in the flat gauge, their applicability is mostly restricted to numerical evaluations. Our form of the action is instead amenable to several analytical approximations, as our calculation in terms of the directly observable quantity makes manifest the scaling of every operator in terms of the slow-roll parameters, what is essentially a generalization of Maldacena’s single-field result to non-canonical two-field models. As an important application we derive the single-field effective field theory that is valid when the entropic mode is heavy and may be integrated out, underlining the observable effects that derive from a curved field space.

    更新日期:2020-01-16
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