Total J/Psi and Upsilon production cross section at the LHC: theory vs. experiment
J. P. Lansberg
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Contributed to the 35th International Conference on High Energy Physics -- ICHEP 2010, Paris, France, July 22-28, 2010. 5 pages, 4 figures, uses PoS.cls (included)
We evaluate the production cross section for direct J/Psi and Upsilon integrated in P_T for various collision energies in the QCD-based Colour-Singlet Model (CSM). We consider the LO contribution from gluon fusion whose P_T-integrated cross section shows a very good agreement with the Tevatron and LHC data, both for J/Psi and Upsilon. The rapidity distribution of this yield is evaluated in the central region relevant for the ATLAS and CMS detectors, as well as in the more forward region relevant for the ALICE and LHCb detectors. The results obtained here are compatible with those of other approaches within the range of the theoretical uncertainties which are admittedly very large. This suggests that the "mere" measurements of the yield at the LHC will not help disentangle between the different possible quarkonium production mechanisms. Yet, the comparison with the first LHC results by ALICE, ATLAS, CMS and LHCb confirms that the CSM correctly accounts for the P_T-integrated yield at sqrt(s)=7 TeV.
Closed-flavor pi + J/psi and pi + Upsilon Cross Sections at Low Energies from Dipion Decays
轻强子低能c-cbar和b-bbar截面的标度对于利用重夸克偶素抑制信号寻找夸克-胶子等离子体具有重要意义。不幸的是，目前对这些近阈值截面知之甚少，最近的理论估计跨越了许多数量级。本文利用已观测到的四个闭味重夸克偶素强子衰变的实验数据，结合简单的跃迁振幅模型，估算了c-cbar和b-bbar介子在阈附近的π散射截面.具体地说，我们考虑了闭味反应pi J/psi-> pi psi'、pi Upsion-> pi Upsion '、pi Upsion-> pi Upsion'和pi Upsion '-> pi Upsion'以及它们的时间反演类似物。我们的结果可能有助于约束重夸克偶素强相互作用的理论模型，并且可以通过对双介子衰变的进一步研究得到系统的改进，特别是psi '-> pi pi J/psi和U'-> pi pi Upperdance.
We revisit inclusive J/psi and Upsilon photoproduction at lepton-hadron colliders, namely in the limit when the exchanged photon is quasi real. Our computation includes the next-to-leading-order (NLO) alpha_s corrections to the leading-order contributions in v. Similarly to the case of NLO charmonium-hadroproduction processes, the resulting cross sections obtained in the MS-bar factorisation scheme are sometimes found to be negative. We show that the scale-fixing criteria which we derived in a previous study of eta(c) production successfully solves this problem from the EicC all the way up to …
Remarks on CLEO New Measurements for Upsilon(1S) Decays to Charmonium Final States and Investigations on Associate Strange Particle Enhancement in Upsilon to J/Psi +X
本文分析了CLEO合作组最近对Uppermont（1 S）衰变中J/Psi和Psi（2S）产生的测量结果和我们以前的计算结果。J/Psi动量谱和Psi（2S）与J/Psi的产生比支持J/Psi（Psi（2S））+ ccbar g作为主要贡献。我们指出，实验数据和我们以前的结果之间的差异主要是由于参数粲夸克质量的设置。我们进一步提出伴随的奇异粒子增强可以作为J/Psi（Psi（2S））+ ccbar g Upplanet中开粲粒子的探针。
Gluon shadowing effects on J/psi and Upsilon production in p+Pb collisions at sqrt s_NN = 115 GeV and Pb+p collisions at sqrt s_NN = 72 GeV at AFTER@LHC
Branching ratios of the decays of psi(3770) and Upsilon(10580) into light hadrons
考虑到关于D^{ \ast \pm }（2010）的全宽的新数据以及带电和中性美介子B^ \pm、B^0、\bar B^0的质量差，衰变的分支比为psi（3770）、Uppermance（10580）到pi^+pi^-、K bar K、ρ（omega）pi、ρ（omega）eta、ρ（omega）eta^prime、K^ast bar K+ c. c，rho^+ rho^-和K^ast bar K^ast在模型中被重新评估，在该模型中，由于在psi（3770）的情况下的真实中间状态D \bar D和在Uppersion（10580）的情况下的B \bar B，Okubo-Zweig-Iizuka规则被违反。本文讨论了Psi（3770）和Uppersons（10580）到轻强子的包容性湮灭。
On theoretical uncertainty of color dipole phenomenology in the J/Psi and Upsilon photoproduction in pA and AA collisions at the CERN Large Hadron Collider
Hadronic and Electromagnetic Interactions of Quarkonia
我们研究了夸克偶素的强子相互作用，重点研究了衰变psi（2s）->psi pi pi和衰变updates（2s）-> updates pi pi。多极展开中的主要胶子算子被匹配到手征拉格朗日量上，手征拉格朗日量的系数与现有的数据相拟合，无论是在手征展开中的树级还是环级。与天真的期望松散的基础上的大$N_c$限制QCD在努力确定这一限制的可靠性，为其他观测，如绑定的$\ps$的核。交叉对称性用于估计非弹性$π\ps\toπ\pss$散射的截面，可能与重离子碰撞有关。在树水平上确定了手征拉格朗日量中的辐射衰变psi（2s）->psi pi pi gamma和upper（2s）-> upper pi pi gamma。对这种衰变的测量将提供对多极展开和手征展开的检验。我们简要地讨论了从uppertons（3s）的衰变，也从介子的夸克偶素的电磁极化率的贡献。
Upsilon (1S) decay to Xi_cc +anything is studied. It is shown that the branching ratio can be as significant as that of Upsilon (1S) decay to J/Psi +anything. The non-relativistic heavy quark effective theory framework is employed for the calculation on the decay width. Measurements on the production of Xi_cc and likely production characteristic of the partonic state with four charm quarks at BELLE2 are suggested.
We study the Single-Parton-Scattering (SPS) production of double quarkonia (J/psi+J/psi, J/psi+Upsilon, and Upsilon+Upsilon) in pp and pp(bar) collisions at the LHC and the Tevatron as measured by the CMS, ATLAS, LHCb, and D0 experiments in the Colour-Evaporation Model (CEM), based on the quark-hadron-duality, including Next-to-Leading Order (NLO) QCD corrections up to alpha_s^5. To do so, we also perform the first true NLO --up to alpha_s^4-- study of the p_T-differential cross section for single-quarkonium production. This allows us to fix the non-perturbative CEM parameters at NLO accuracy …
We investigate the potentialities offered by the study of J/psi exclusive photo-production in ultra-peripheral collisions at a fixed-target experiment using the proton and lead LHC beams (generically denoted as AFTER@LHC) on hydrogen targets and at RHIC in the collider mode. We compare the expected counting rates in both set-ups. Studying Single-Transverse-Spin Asymmetries (A_N) in such a process provides a direct path to the proton Generalised Parton Distribution (GPD) E_g(x,xi,t). We evaluate the expected precision on A_N for realistic conditions with the LHCb detector in pH(pol) and PbH(pol…
