当前位置: X-MOL 学术Eur. Phys. J. C › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Bottomonia production and polarization in the NRQCD with $$k_T$$kT -factorization. II: $$\Upsilon (2S)$$Υ(2S) and $$\chi _b(2P)$$χb(2P) mesons
The European Physical Journal C ( IF 4.2 ) Pub Date : 2020-05-30 , DOI: 10.1140/epjc/s10052-020-8056-x
N. A. Abdulov , A. V. Lipatov

The \(\Upsilon (2S)\) production and polarization at high energies is studied in the framework of \(k_T\)-factorization approach. Our consideration is based on the non-relativistic QCD formalism for bound states formation and off-shell production amplitudes for hard partonic subprocesses. The direct production mechanism, feed-down contributions from radiative \(\chi _b(3P)\) and \(\chi _b(2P)\) decays and contributions from \(\Upsilon (3S)\) decays are taken into account. The transverse momentum dependent gluon densities in a proton were derived from the Ciafaloni–Catani–Fiorani–Marchesini evolution equation, Kimber-Martin-Ryskin prescription and Parton Branching method. Treating the non-perturbative color octet transitions in terms of the mulitpole radiation theory, we extract the corresponding non-perturbative matrix elements for \(\Upsilon (2S)\) and \(\chi _b(2P)\) mesons from a combined fit to \(\Upsilon (2S)\) transverse momenta distributions measured by the CMS and ATLAS Collaborations at the LHC energies \(\sqrt{s} = 7\) and 13 TeV and from the relative production rate \(R^{\chi _b(2P)}_{\Upsilon (2S)}\) measured by the LHCb Collaboration at \(\sqrt{s} = 7\) and 8 TeV. Then we apply the extracted values to investigate the polarization parameters \(\lambda _\theta \), \(\lambda _\phi \) and \(\lambda _{\theta \phi }\), which determine the \(\Upsilon (2S)\) spin density matrix. Our predictions have a good agreement with the currently available data within the theoretical and experimental uncertainties.

中文翻译:

NRQCD中的$ k_T $$ kT分解导致的足底分泌和极化。II:$$ \ Upsilon(2S)$$Υ(2S)和$$ \ chi _b(2P)$$χb(2P)介子

\(k_T \)分解方法的框架下研究了高能量下的\(\ Upsilon(2S)\)的产生和极化。我们的考虑是基于非相对论性QCD形式主义的,用于结合态形成和硬部分子过程的脱壳产生幅度。直接生产机制,辐射\(\ chi _b(3P)\)\(\ chi _b(2P)\)的馈电衰减和\(\ Upsilon(3S)\)的衰减衰减被考虑在内。质子中与横向动量有关的胶子密度取决于Ciafaloni-Catani-Fiorani-Marchesini演化方程,Kimber-Martin-Ryskin处方和Parton分枝法。根据多极辐射理论处理非扰动的彩色八位位组跃迁,我们从组合中提取\(\ Upsilon(2S)\)\(\ chi _b(2P)\)介子的相应非扰动矩阵元素根据LHC能量\(\ sqrt {s} = 7 \)和13 TeV并根据相对生产率\(R ^ { ,拟合CMS和ATLAS合作测量的\(\ Upsilon(2S)\)横向动量分布。\ chi _b(2P)} _ {\ Upsilon(2S)} \)由LHCb协作在\(\ sqrt {s} = 7 \)和8 TeV下测量。然后,我们将提取的值应用于研究极化参数\(\ lambda _ \ theta \)\(\ lambda _ \ phi \)\(\ lambda _ {\ theta \ phi} \)来确定\( \ upsilon(2S)\)自旋密度矩阵。在理论和实验不确定性范围内,我们的预测与当前可获得的数据具有很好的一致性。
更新日期:2020-05-30
down
wechat
bug