119202012
Bridging light-cone and NRQCD approaches: asymptotic behavior of Bc electromagnetic form factor
This work aims at illustrating that, for a class of leading-twist hard exclusive reactions involving two heavy quarkonia, the light-cone approach, when equipped with the strategy of refactorization of the light-cone distribution amplitude of quarkonium, can be employed to elegantly reproduce the corresponding predictions made in the nonrelativistic QCD (NRQCD) factorization approach, order by order in perturbative expansion. Taking the electromagnetic form factor of the Bc meson at large momentum transfer, Q2, as a concrete example, we compare the results obtained from both NRQCD-based and light-cone-based calculations through the next-to-leading order (NLO) in αs, while at the leading order (LO) in both velocity and 1/Q2 expansion, and explicitly confirm their mutual agreement. As a byproduct, we apply our NLO result to explore certain features about the asymptotic behavior of the heavy-light meson form factor. We also address the major theoretical obstacles that prevent us from establishing an analogous equivalence between these two approaches for the double charmonium production process of phenomenological interest, e+e− → J/ψ + ηc.
118444783
The QED contribution to $J/\psi$ plus light hadrons production at B-factories
To understand the direct $J/\psi+X_{\mathrm{non-c\bar{c}}}$ production mechanism in $e^{+}e^{-}$ annihilation, in this work, we propose to measure the inclusive $J/\psi$ plus light hadrons (LH) production at B-factories and present a detailed study on its QED production due to $\psi(2S)$ feed-down, where the $\psi(2S)$ are produced in $e^{+}e^{-}\to \psi(2S)+\gamma$ and $e^{+}e^{-}\to \psi(2S)+f\bar{f}, f=lepton,light quark$, and QED contribution to direct $J/\psi+q\bar{q}$ production with $q=u,d,s$ quark. We find that the QED contribution is huge in the whole phase space region, but can be reduced largely and is in the same order as the QCD contribution when a suitable cut on the angel $\theta_{J/\psi}$ between $J/\psi$ and the $e^{+}e^{-}$ beam is made. In this way, the cross section of $J/\psi+LH$ QCD production %which was predicted theoretical at next-to-leading order QCD together with relativistic correction, can be obtained by subtracting the QED contribution from the experimental measurement on inclusive $J/\psi$ plus light hadrons. To help to remove the QED background, we also calculate the angular and momentum distribution of $J/\psi$ in the QED contribution.
123106617
Prospects for a new boson W±1 in the minimal Higgsless model at the LHC
The author list originally given in the above article (Ming-Shui Chen, Jian-Guo Bian, Guo-Ming Chen, Hong-Jian He, Chun-Hua Jiang, Zu-Hao Li, Song Liang, Xiang-Wei Meng, Yong-Hui Qi, Zhi-Cheng Tang, Jun-Quan Tao, Zheng Wang, Jian Wang, Jian Wang, Xian-You Wang, Jian-Xiong Wang, Hong Xiao, Min Yang, Jing-Jing Zang, Bin Zhang, Zhen Zhang and Zhen- Xia Zhang) is incorrect. The correct author list is: Ming-Shui Chen, Jian-Guo Bian, Guo-Ming Chen, Chun-Hua Jiang, Zu-Hao Li, Song Liang, Xiang-Wei Meng, Zhi-Cheng Tang, Jun-Quan Tao, Zheng Wang, Jian Wang, Jian Wang, Xian-You Wang, Jian-Xiong Wang, Hong Xiao, Min Yang, Jing-Jing Zang, Bin Zhang, Zhen Zhang and Zhen-Xia Zhang. Hong-Jian He and Yong-Hui Qi did not take part in the writing of this text and do not bear any responsibility for its contents. Also, reference [4] in the paper should be corrected to: [4] Hong-Jian He et al 2008 Phys. Rev. D 78 031701(R)
37724150
FDCSUSYDecay: An MSSM decay package
FDCSUSYDecay is a FORTRAN program package generated by FDC (Feynman Diagram Calculation) system fully automatically. It is dedicated to calculate at tree-level all the possible 2-body decays of SUSY and Higgs particles in the Minimal Supersymmetric extension of the Standard Model (MSSM). The format of its output files complies with SUSY Les Houches Accord and can be easily imported by other package.
28828852
EtabFDC: An etab event generator in hadroproduction at LHC
The EtabFDC is a matrix-element event generator package for eta(b) hadroproduction at LHC. It generates pp -> eta X-b events for all possible parton-level 2 -> 2 leading-order processes with three commonly used 116 decay channels being implemented. The PYTHIA interface is used for parton-shower and hadronization to obtain the hadronic events. The FORTRAN codes of this package are generated by FDC (Feynman Diagram Calculation) system automatically. Program summary Program title: EtabFDC (Version 1.01) Catalogue identifier: AEBV_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEBV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast. N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 1840204 No. of bytes in distributed program, including test data, etc.: 18 018379 Distribution format: tar.gz Programming language: FORTRAN 77 Computer: Any computer with Linux operating system and GNU 77 Fortran compiler Operating system: Linux (with GNU FORTRAN 77 compiler) Classification: 11.1 External routines: CERNLIB 2001 (or CERNLIB 2003) Nature of problem: This package generates pp -> eta X-b events for partonic 2 -> 2 tree-level processes with implementing three eta(b) decay channels. It then interfaces with PYTHIA for parton-shower and hadronization to obtain the hadronic events. Solution method: The FORTRAN codes of this package are generated by FDC system [ I) automatically. Additional comments: This program could not be tested by the CPC Program Library as it requires the CERNLIB libraries. Running time: To generate 1000 events on a 3.2G Intel-P4 CPU platform (with hyper-technology). it will take approximate 20, 30 and 300 seconds for decay channel eta(b) J/psi gamma,eta(b)-> J/psi J/psi and eta b -> J/psi ccbar, respectively. References: [1] J.X. Wang, Nucl. Instrum. Methods A 534 (2004) 241, arXiv:hep-ph/0407058. (C) 2008 Elsevier B.V. All rights reserved.
118674100
J/ψ production via photon fragmentation at hadron colliders
The transverse momentum (p(t)) distributions of production and polarization for J/psi measured by CDF Collaboration are still challenging our understanding of the heavy quarkonium production mechanism even with recent significant theoretical progresses on the next-to-leading-order (NLO) QCD calculation. We investigate an interesting mechanism for J/psi production at hadron collider, pp((p) over bar) -> gamma* (J/psi) + X with J/psi from a virtual photon gamma* fragmentation. Our calculations show that the J/psi p(t) distribution in the photon fragmentation process up to NLO in alpha(s) will be larger than that of the conventional J/psi production from the color-singlet mechanism at NLO when p(t) > 26 (35) GeV at the Tevatron (LHC) and reach about 6 (10) times of the conventional one when p(t) = 50 (100) GeV at the Tevatron (LHC), in spite of a suppression factor (alpha/alpha(s))(2) that is associated with the QED and QCD coupling constants. In addition, it also has large impact on the p(t) distribution of J/psi polarization in large p(t) region. Therefore, it is an important mechanism for J/psi production at large p(t) region especially for the LHC. (c) 2012 Elsevier B.V. All rights reserved.
209048432
Search for supersymmetry in hadronic final states with missing transverse energy using the variables alphaT and b-quark multiplicity in pp collisions at sqrt(s) = 8 TeV
119247224
The Development of the Linac Coherent Light Source RF Gun
The Linac Coherent Light Source (LCLS) is the first x-ray laser user facility based upon a free electron laser (FEL). In addition to many other stringent requirements, the LCLS XFEL requires extraordinary beam quality to saturate at 1.5 angstroms within a 100 meter undulator.[1] This new light source is using the last kilometer of the three kilometer linac at SLAC to accelerate the beam to an energy as high as 13.6 GeV and required a new electron gun and injector to produce a very bright beam for acceleration. At the outset of the project it was recognized that existing RF guns had the potential to produce the desired beam but none had demonstrated it. This paper describes the analysis and design improvements of the BNL/SLAC/UCLA s-band gun leading to achievement of the LCLS performance goals.
122659262
Identification and filtering of uncharacteristic noise in the CMS hadron calorimeter
Commissioning studies of the CMS hadron calorimeter have identified sporadic uncharacteristic noise and a small number of malfunctioning calorimeter channels. Algorithms have been developed to identify and address these problems in the data. The methods have been tested on cosmic ray muon data, calorimeter noise data, and single beam data collected with CMS in 2008. The noise rejection algorithms can be applied to LHC collision data at the trigger level or in the offline analysis. The application of the algorithms at the trigger level is shown to remove 90% of noise events with fake missing transverse energy above 100 GeV, which is sufficient for the CMS physics trigger operation.
118350998
Next-to-leading order QCD predictions for graviton and photon associated production in the Large Extra Dimensions model at the LHC
We present the calculations of the complete next-to-leading order (NLO) QCD corrections to the inclusive total cross sections for the Kaluza-Klein (KK) graviton and photon associated production process pp{yields}{gamma}G{sub KK}+X in the large extra dimensions model at the LHC. We show that the NLO QCD corrections in general enhance the total cross sections and reduce the dependence of the total cross sections on the factorization and renormalization scales. When jet veto is considered, the NLO corrections reduce the total cross sections. We also calculate some important differential cross sections for this process at NLO: the missing transverse momentum distribution, the transverse momentum distribution, and the pseudorapidity distribution of photon.
118291411
Next-to-Leading-Order QCD corrections to $J/\psi (\upsilon) + \gamma$ production at the LHC
In this work, we calculate the next-to-leading-order (NLO) QCD corrections to the process $p+p \to J/\psi + \gamma$ via the color-singlet mechanism at the LHC. The results show that the partial cross section ($p_t^{J/\psi}>$3GeV and $|y^{J/\psi,\gamma}|<$3) is enhanced by a factor of about 2.0, and the differential cross section can be enhanced by two orders of magnitude in the large transverse momentum region of $J/\psi$. Furthermore, the polarization of $J/\psi$ changes from transverse polarization at leading-order to longitudinal polarization at NLO. For the inclusive $J/\psi$ hadroproduction, it is known that the color-octet contributions are one order of magnitude larger than the color-singlet contribution, and the polarization distribution is dominated by the color-octet behavior at NLO. In contrast, for $J/\psi+\gamma$ production the color-singlet contribution is of the same order as the color-octet contribution, and the polarization distribution arises from both the color-singlet and color-octet. Therefore, measurements of $J/\psi$ production associated with a direct photon at the hadron collider could be an important supplement to testify the theoretical framework treating with the heavy quarkonium. In addition, an NLO QCD correction to $\Upsilon+\gamma$ production at the LHC is also presented in this paper.