We review the current understanding of time-like virtual photon emission from QCD matter. The phenomenology of dilepton emission is discussed and basic theoretical concepts are introduced. The experimental findings are presented, grouped into production of lepton pairs in elementary processes, production off cold nuclear matter and emission from heavy-ion collisions. The review emphasizes the role

The strange quark plays a unique role in QCD, reflecting its intermediate mass between the light and heavy quarks. In recent years, remarkable progress has been made in the spectroscopy of baryons with strangeness. Many new features of the strange baryon spectrum have been revealed by accurate experimental data with novel techniques, as well as systematic developments of theoretical framework to describe

The generalization of the color gauge group SU(3) to SU(Nc), with Nc taking arbitrarily large values, as had been proposed and developed by ’t Hooft, has allowed for a decisive progress in the understanding of many qualitative, as well as quantitative, aspects of QCD in its nonperturbative regime. In particular, the notion of valence quarks receives there a precise meaning. The present work reviews

Dark matter represents currently an outstanding problem in both cosmology and particle physics. In this review we discuss the possible explanations for dark matter and the experimental observables which can eventually lead to the discovery of dark matter and its nature, and demonstrate the close interplay between the cosmological properties of the early Universe and the observables used to constrain

In this review article we discuss the present status of direct nuclear reactions and the nuclear structure aspects one can study with them. We discuss the spectroscopic information we can assess in experiments involving transfer reactions, heavy-ion-induced knockout reactions and quasifree scattering with (p,2p), (p,pn), and (e,e′p) reactions. In particular, we focus on the proton-to-neutron asymmetry

Quasifission competes with fusion, and can suppress the cross sections for formation of heavy elements by orders of magnitude. Its understanding is important both to map out opportunities to synthesise superheavy elements and isotopes, and to understand the non-equilibrium dynamics that controls heavy ion reactions. A review of experimental studies of quasifission is presented, summarising significant

Nuclear processes not only generate the energy and drive the evolution of stars, but also are responsible for the synthesis of the elements in the Universe. Helium (4He, or α) is the second most abundant element after hydrogen, thus α-particle induced reactions such as (α,γ), (α,n) and (α,p) play a crucial role in nuclear astrophysics, especially for understanding stellar helium burning. Direct measurement

The Spin Physics Detector (SPD) is a future multipurpose experiment foreseen to run at the NICA collider, which is currently under construction at the Joint Institute for Nuclear Research (JINR, Dubna, Russia). The physics program of the experiment is based on collisions of longitudinally and transversely polarized protons and deuterons at s up to 27 GeV and luminosity up to 1032 cm−2 s−1. The SPD

Depending on the point of view, the Casimir force arises from variation in the energy of the quantum vacuum as boundary conditions are altered or as an interaction between atoms in the materials that form these boundary conditions. Standard analyses of such configurations are usually done in terms of ordinary, equal-time (Minkowski) coordinates. However, physics is independent of the coordinate choice

The inclusive production of hadrons through electroweak currents can be rigorously analysed with short-distance theoretical tools. The associated observables are insensitive to the involved infrared behaviour of the strong interaction, allowing for very precise tests of Quantum Chromodynamics. The theoretical predictions for σ(e+e−→hadrons) and the hadronic decay widths of the τ lepton and the Z, W

The importance of S-matrix unitarity in realistic meson spectroscopy is reviewed, both its historical development and more recent applications. First the effects of imposing S-matrix unitarity on meson resonances are demonstrated in both the elastic and the inelastic case. Then, the static quark model is revisited and its theoretical and phenomenological shortcomings are highlighted. A detailed account

The standard model (SM) of elementary particles involves particle symmetry and the mechanism of its breaking. It finds no contradictions in the collider experiments, but appeals to extensions for solutions of its internal problems and in view of its evident incompleteness. The paradigm of the modern cosmology is based on inflationary models with baryosynthesis and dark matter/energy that involves physics

We review lattice studies of the color screening in the quark–gluon plasma. We put the phenomena related to the color screening into the context of similar aspects of other physical systems (electromagnetic plasma or cold nuclear matter). We discuss the onset of the color screening and its signature and significance in the QCD transition region, and elucidate at which temperature and to which extent

The last decade has seen a marked shift in how the internal structure of hadrons is understood. Modern experimental facilities, new theoretical techniques for the continuum bound-state problem and progress with lattice-regularised QCD have provided strong indications that soft quark+quark (diquark) correlations play a crucial role in hadron physics. For example, theory indicates that the appearance

The interest to perform laser spectroscopy in the heaviest elements arises from the strong impact of relativistic effects, electron correlations and quantum electrodynamics on their atomic structure. Once this atomic structure is well understood, laser spectroscopy also provides access to nuclear properties such as spins, mean-square charge radii and electromagnetic moments in a nuclear-model independent

In the understanding of the fundamental interactions, the origin of an arrow of time is viewed as problematic. However, quantum field theory has an arrow of causality, which tells us which time direction is the past lightcone and which is the future. This direction is tied to the conventions used in the quantization procedures. The different possible causal directions have related physics — in this

This article presents a number of technical tools and results that may be instrumental to discern the nature of the Higgs particle. In scenarios where an additional strongly interacting sector is present in the electroweak theory, resulting in a composite Higgs and longitudinal components of the massive gauge bosons, unitarity, analyticity and related techniques will be crucial to understand the properties

Exascale computing could soon enable a predictive theory of nuclear structure and reactions rooted in the Standard Model, with quantifiable and systematically improvable uncertainties. Such a predictive theory will help exploit experiments that use nucleons and nuclei as laboratories for testing the Standard Model and its limitations. Examples include direct dark matter detection, neutrinoless double

Storage rings have been employed over three decades in various kinds of nuclear and atomic physics experiments with highly charged ions. Storage ring operation and precision physics experiments benefit from the availability of beam cooling which is common to nearly all facilities. The basic aspects of the storage ring components and the operation of the ring in various ion-optical modes as well as

Experimental observations and theoretical arguments at galactic and larger scales pointed out that a large fraction of the Universe is composed of Dark Matter (DM) particles. This has motivated the pioneer DAMA experimental efforts to investigate the presence of such particles in the galactic halo, by exploiting a model independent signature and very highly radio-pure apparatus in deep underground

Since the discovery of CP violation more than 5 decades ago, this phenomenon is still attracting a lot of interest. Among the many fascinating aspects of this subject, this review is dedicated to direct CP violation in non-leptonic decays. The advances within the last decade have been enormous, driven by the increasingly large samples of b- and c-hadron decays, and have led to very interesting results

A Review on attempts to propose alternative theories to the General Relativity is presented. The restriction is on classical models/theories and comprise rather algebraic extensions of the theory of General Relativity. First, possible algebraic extensions of the space–time coordinates and metric extensions are presented, with a discussion of their problems and limits. The pseudo-complex General Relativity

The nucleons (protons and neutrons) are by far the most abundant form of matter in our visible Universe; they are composite particles made of quarks and gluons, the fundamental quanta of Quantum Chromo Dynamics (QCD). The usual interpretation of the nucleon dynamics in high energy interactions is often limited to a simple one-dimensional picture of a fast moving nucleon as a collection of co-linearly

The first activities of the Canfranc Underground Laboratory (“Laboratorio Subterráneo de Canfanc”, LSC) started in the mid-eighties in a railway tunnel located under the Spanish Pyrenees; since then, it has become an international multidisciplinary facility equipped with different services for underground science. The research activity at LSC is about Astroparticle Physics, dark matter searches and

We review the current understanding of heavy quark parton distributions in nucleons and their impact on deep inelastic scattering, collider physics, and other processes at high energies. The determination of the heavy-quark parton distribution functions is particularly significant for the analysis of hard processes at LHC energies, including the forward rapidity high xF domain. The contribution of

Neutrino-less double-beta decay (0νββ) is a hypothetical nuclear transition which violates lepton-number conservation and is therefore forbidden by the Standard Model of particle physics. Its observation would unambiguously demonstrate that neutrinos are Majorana particles and would provide unique information about the ordering and absolute scale of neutrino masses. This would have fundamental implications

Heavy flavor hadrons have long been considered as a probe of the quark–gluon plasma created in high energy nuclear collisions. In this paper, we review the heavy flavor properties under extreme conditions and the realization in heavy ion experiments. After a short introduction on heavy flavor properties in vacuum, we emphasize the cold and hot nuclear matter effects on heavy flavors, including shadowing

The existing CERN accelerator infrastructure is world unique and its research capacity should be fully exploited. In the coming decade its principal modus operandi will be focused on producing intense proton beams, accelerating and colliding them at the Large Hadron Collider (LHC) with the highest achievable luminosity. This activity should, in our view, be complemented by new initiatives and their

We construct a generalized effective field theory approach to dense compact-star matter that exploits the Cheshire Cat Principle for hadron–quark continuity at high density, adhering only to hadronic degrees of freedom, hidden topology and hidden symmetries of QCD. No Landau–Ginzburg–Wilsonian-type phase transition is involved in the range of densities involved. The microscopic degrees of freedom of

This article aims at covering various low energy nuclear physics themes that can benefit from taking advantage of active targets and time projection chambers. They are naturally oriented towards the study of short-lived radioactive nuclei, for which high efficiency and thick targets are necessary to boost the luminosity of the experiments due to the weak intensity of the available beams. The use of

(1) The classical way to determine the electron anti-neutrino mass is the single Beta Decay of Tritium [3H → 3He + e− + νec] (Particle Physics Booklet, 2014; Aker et al., 2019). This special decay is favored by the small Q-value Q=18.5737 ± 0.00025 keV (Aker et al., 2019). Presently KATRIN (Aker et al., 2019) yields an upper limit of 1.1 eV (90% CL) for the neutrino mass the best result. (2) Electron

We review lattice determinations of the charm- and bottom-quark masses and the strong coupling constant obtained by different methods. We explain how effective field theory approaches, such as Non-Relativistic QCD (NRQCD), potential Non-Relativistic QCD (pNRQCD), Heavy Quark Effective Theory (HQET) and Heavy Meson rooted All-Staggered Chiral Perturbation Theory (HMrASχPT) can help in these determinations

Axion-like particle (ALP) dark matter shows distinctive behavior on scales where wavelike effects dominate over self-gravity. Ultralight axions are candidates for fuzzy dark matter (FDM) whose de Broglie wavelength in virialized halos reaches scales of kiloparsecs. Important features of FDM scenarios are the formation of solitonic halo cores, suppressed small-scale perturbations, and enhanced gravitational

Recent results connected to nuclear collision dynamics, from low up to relativistic energies, are reviewed. Heavy ion reactions offer the unique opportunity to probe the complex nuclear many-body dynamics and to explore, in laboratory experiments, transient states of nuclear matter under several conditions of density, temperature and charge asymmetry. Transport models are an essential tool to undertake

The diffuse backgrounds of relic gravitons with frequencies ranging between the aHz band and the GHz region encode the ultimate information on the primeval evolution of the plasma and on the underlying theory of gravity well before the electroweak epoch. While the temperature and polarization anisotropies of the microwave background radiation probe the low-frequency tail of the graviton spectra, during

General Relativity is today the best theory of gravity addressing a wide range of phenomena. Our understanding of physical laws, from cosmology to local scales, cannot be properly formulated without taking into account its concepts, procedures and formalism. It is based on one of the most fundamental principles of Nature, the Equivalence Principle, which represents the core of the Einstein theory of

The aim of the hadron physics research programs conducted at J-PARC is to explore the structure of hadronic matter using the world’s highest-intensity meson beams. Since the first beam was extracted at the hadron experimental facility in February 2009, a wide variety of physics experiments have been proposed and performed to address open questions regarding quantum chromodynamics (QCD) at low energy

Second order β-decay processes with and without neutrinos in the final state are key probes of nuclear physics and of the nature of neutrinos. Neutrinoful double-β decay is the rarest Standard Model process that has been observed and provides a unique test of the understanding of weak nuclear interactions. Observation of neutrinoless double-β decay would reveal that neutrinos are Majorana fermions

We review the present status of the experimental and theoretical developments in the field of strangeness in nuclei and neutron stars. We start by discussing the K̄N interaction, that is governed by the presence of the Λ(1405). We continue by showing the two-pole nature of the Λ(1405), and the production mechanisms in photon-, pion-, kaon-induced reactions as well as proton–proton collisions, while

The Global and Modular Beyond-Standard Model Inference Tool (GAMBIT) is an open source software framework for performing global statistical fits of particle physics models, using a wide range of particle and astroparticle data. In this review, we describe the design principles of the package, the statistical and sampling frameworks, the experimental data included, and the first two years of physics

Applications of cosmic-ray muons have grown in numbers in the last decades. This was possible thanks to the development of detectors and techniques employed in particle and nuclear physics. Indeed the first famous application, the scanning of the Chephren’s pyramid, was performed by L. W. Alvarez, that was a great expert in particle detectors and indeed was awarded a Nobel prize for his work on the

Nuclear-structure studies with reaccelerated radioactive ion beams at the ISOLDE facility, CERN commenced with the REX-ISOLDE facility and continued after a major upgrade of the facility with the HIE-ISOLDE post-accelerator. The experiments are based on in-beam high-resolution γ-ray spectroscopy with Miniball, a spectrometer which comprises 24 six-fold segmented, encapsulated high-purity germanium

Despite decades of research, we still lack a detailed quantitative understanding of the way quantum chromodynamics (QCD) generates the spectrum of hadrons. Precise experimental studies of the hadron excitation spectrum and the dynamics of hadrons help to improve models and to test effective theories and lattice QCD simulations. In addition, QCD seems to allow hadrons beyond the three-quark and quark–antiquark

The spectrum of hadrons is the manifestation of color confinement of quantum chromodynamics. Hadronic resonances correspond to poles of the S-matrix. Since 2003, lots of new hadron resonant structures were discovered in the mass regions from light mesons to hadrons containing a pair of a heavy quark and an antiquark. Many of them are candidates of exotic hadrons, and they are usually observed as peaks

A century ago, nuclear physics entered astrophysics, giving birth to a new field of science referred to as “Nuclear Astrophysics”. With time, it developed at an impressive pace into a vastly inter- and multidisciplinary field bringing into its wake not only astronomy and cosmology, but also many other sub-fields of physics, especially particle, solid-state and computational physics, as well as chemistry

Cosmic rays are energetic particles composed primarily of protons and helium nuclei but including, with varying abundances, all atomic nuclei species, electrons and even antiparticles. They originate from sources that, save for the highest energies, are located in the Galaxy. After more than one century from their discovery and except for a clear contribution, particularly important at energies lower

Hadron properties and interactions are emergent from QCD. Atomic and condensed matter physics are emergent from QED. Could the local gauge symmetries of particle physics also be emergent? We give an introduction to this question and recent ideas connecting it to the (meta)stability of the Standard Model Higgs vacuum. With an emergent Standard Model the gauge symmetries would “dissolve” in the ultraviolet

This review gives an update on virtual Compton scattering (VCS) off the nucleon, γ∗N→γN, in the low-energy regime. We recall the theoretical formalism related to the generalized polarizabilities (GPs) and model predictions for these observables. We present the GP extraction methods that are used in the experiments: the approach based on the low-energy theorem for VCS and the formalism of Dispersion

Reactions with radioactive nuclear beams at relativistic energies have opened new doors to clarify the mechanisms of stellar evolution and cataclysmic events involving stars and during the big bang epoch. Numerous nuclear reactions of astrophysical interest cannot be assessed directly in laboratory experiments. Ironically, some of the information needed to describe such reactions, at extremely low

We review the last two decades of using photon beams to measure the production of mesons, and in particular the information that can be obtained on the spectrum of light, non-strange baryons. This is a compendium of experimental results, which should be used as a complement to theoretical reviews of the subject. Lists of data sets are given, together with a comprehensive set of references. An indication

Particle acceleration in collisionless plasma systems is a central question in astroplasma and astroparticle physics. The structure of the acceleration regions, electron–ion energy equilibration, preacceleration of particles at shocks to permit further energization by diffusive shock acceleration, require knowledge of the distribution function of particles besides the structure and dynamic of electromagnetic

At high energy, exclusive meson photo- and electro-production give access to the structure of hadronic matter. At low momentum transfers, the exchange of a few Regge trajectories leads to a comprehensive account of the cross-sections. Among these trajectories, which are related to the mass spectrum of families of mesons, the Pomeron plays an interesting role as it is related to glue-ball excitations

Deuteron stripping and pick-up experiments - (d,p) and (p,d) - have been used for a long time to study the structure of nuclei. Today these experiments are often carried out in inverse kinematics in state-of-the-art radioactive beams facilities around the world, extending the boundaries of our knowledge of the nuclear chart. The nuclear structure information obtained from these experiments relies entirely

We review the BCS (Bardeen–Cooper–Schrieffer)–BEC (Bose–Einstein condensation) crossover phenomenon discussed in an ultracold Fermi atomic gas and a neutron superfluid in the low-density crust regime of a neutron star. A purpose of this paper is to show that these two very different atomic and nuclear systems can be closely related to each other from the viewpoint of this quantum many-body phenomenon

A number of anomalous results in short-baseline oscillation may hint at the existence of one or more light sterile neutrino states in the eV mass range and have triggered a wave of new experimental efforts to search for a definite signature of oscillations between active and sterile neutrino states. The present paper aims to provide a comprehensive review on the status of light sterile neutrino searches

We review recent studies of the cluster structure of light nuclei within the framework of the algebraic cluster model (ACM) for nuclei composed of k α-particles and within the framework of the cluster shell model (CSM) for nuclei composed of k α-particles plus x additional nucleons. The calculations, based on symmetry considerations and thus for the most part given in analytic form, are compared with

Coupled-channel dynamics for scattering and production processes in partial-wave amplitudes is discussed from a perspective that emphasizes unitarity and analyticity. We elaborate on several methods that have driven to important results in hadron physics, either by themselves or in conjunction with effective field theory. We also develop the use of the Lippmann–Schwinger equation in near-threshold

We review the production of the matter–antimatter asymmetry in the early Universe, that is baryogenesis, in out-of-equilibrium conditions induced by decays of heavy particles or by the presence of phase boundaries. The most prominent examples are given by leptogenesis and electroweak baryogenesis, respectively. For both cases, we derive the equations that govern the production of the asymmetries. We

The status and prospects of heavy ion charge exchange reactions are reviewed. Their important role for nuclear reaction, nuclear structure, and beta-decay investigations is emphasized. Dealing with peripheral reactions, direct reaction theory gives at hand the proper methods for single (SCE) and double charge exchange (DCE) ion–ion scattering. The microscopic descriptions of charge exchange ion–ion

In this review we highlight a few physical properties of neutron stars and their theoretical treatment inasmuch as they can be useful for nuclear and particle physicists concerned with matter at finite density (and newly, temperature). Conversely, we lay out some of the hadron physics necessary to test General Relativity with binary mergers including at least one neutron star, in view of the event