12501278
An upgraded version of the generator BCVEGPY2.0 for hadronic production of Bc meson and its excited states
An upgraded version of the package BCVEGPY2.0: [C.-H. Chang, J.-X. Wang, X.-G. Wu, Comput. Phys. Common. 174 (2006) 241] is presented, which works under LINUX system and is named as BCVEGPY2.1. With the version and a GNU C compiler additionally, users may simulate the B-c-events in various experimental environments very conveniently. It has been manipulated in better modularity and code reusability (less cross communication among various modules) than BCVEGPY2.0 has. Furthermore, in the upgraded version a special execution is arranged as that the GNU command make compiles a requested code with the help of a master makefile in main code directory, and then builds an executable file with the default name run. Finally, this paper may also be considered as an erratum, i.e., typo errors in BCVEGPY2.0 and corrections accordingly have been listed.
43082728
Polarization for prompt J/ψ and ψ(2s) production at the Tevatron and LHC.
With nonrelativistic QCD factorization, we present the first complete next-to-leading order study on the polarization of prompt J/ψ hadroproduction by including feeddown from χ(c)((3)P(J)(1),(3)S(1)(8)) and ψ(2s) which turn out to be very important parts. By using the color-octet long-distance matrix elements obtained from a combined fit of the measurements at the Tevatron and LHC for J/ψ, ψ(2s) and χ(c), the prompt J/ψ polarization predictions are presented, and the results are in agreement with the CDF run I data (except two points), but in conflict with the CDF run II data, while they are close to the ALICE data (inclusive J/ψ). The measurements at the LHC are expected to clarify the situation.
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)
118483137
Production of a heavy quarkonium with a photon or via ISR at Z peak in e+e− collider
Considering the possibility to build an e+e− collider at the energies around Z-boson resonance with a luminosity so high as L ∝ 1034 cm−2 s−1 (even higher) and the abilities of a modern synthesis detector, we systematically calculate the exclusive two body processes of the heavy quarkonium production: e+e− annihilates into a heavy quarkonium and a photon, involving the initial state radiation (i.e. ISR) cases, at the energies around the Z-boson resonance. Since the couplings of Z-boson to quarks contain an axial vector term as well as a vector one, a charmonium such as J/ψ or ηc or hc or χcJ …, or a bottomonium such as ϒ or ηb or hb or χbJ …, associating with a photon, may be produced respectively via Z-boson annihilation. If we call such a collider with so high luminosity and running around the Z-boson resonance as a Z-factory, then our results obtained here indicate that experimental studies of the various heavy quarkona (their ground and excited states) via the two-body processes at a Z-factory have outstanding advantages, especially, the production of the possible states with quantum numbers JPC = 1−− via ISR.
119228404
Discovery potential of new boson W1± in the Minimal Higgsless model at LHC
Abstract In this paper, we demonstrate the LHC discovery potential of new charged vector boson W 1 ± predicted by the Minimal Higgsless model in the process p p → W 1 ± q q ′ → W ± Z 0 q q ′ → l ± l + l − ν q q ′ ( l = e , μ ) by analyzing the generator level events of the signal and backgrounds. The generator for the signal p p → W 1 ± q q ′ → W ± Z 0 q q ′ at tree level is developed with the Minimal Higgsless model and then interfaced with PYTHIA for the parton showers and hadronization. The backgrounds are produced with PYTHIA and ACERMC. We give integrated luminosities required to discover 5σ signal as a function of W 1 ± mass.
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.
119192167
GALAXY DISKS DO NOT NEED TO SURVIVE IN THE ΛCDM PARADIGM: THE GALAXY MERGER RATE OUT TO z ∼ 1.5 FROM MORPHO-KINEMATIC DATA
About two-thirds of present-day, large galaxies are spirals such as the Milky Way or Andromeda, but the way their thin rotating disks formed remains uncertain. Observations have revealed that half of their progenitors, six billion years ago, had peculiar morphologies and/or kinematics, which exclude them from the Hubble sequence. Major mergers, i.e., fusions between galaxies of similar mass, are found to be the likeliest driver for such strong peculiarities. However, thin disks are fragile and easily destroyed by such violent collisions, which creates a critical tension between the observed fraction of thin disks and their survival within the ΛCDM paradigm. Here, we show that the observed high occurrence of mergers among their progenitors is only apparent and is resolved when using morpho-kinematic observations that are sensitive to all the phases of the merging process. This provides an original way of narrowing down observational estimates of the galaxy merger rate and leads to a perfect match with predictions by state-of-the-art ΛCDM semi-empirical models with no particular fine-tuning needed. These results imply that half of local thin disks do not survive but are actually rebuilt after a gas-rich major merger occurring in the past nine billion years, i.e., two-thirds of the lifetime of the universe. This emphasizes the need to study how thin disks can form in halos with a more active merger history than previously considered and to investigate what is the origin of the gas reservoir from which local disks would reform.
119230969
Measurement of the inclusive Z cross section via decays to tau pairs in pp collisions at $ \sqrt {s} = 7 $ TeV
The first measurement of inclusive Z → τ+τ− production in pp collisions at the LHC is presented, in the final states μ + hadrons, e + hadrons, e + μ, and μ + μ. The data sample corresponds to an integrated luminosity of 36 pb−1 collected with the CMS detector. The measured cross section is σ (pp → ZX) × B (Z → τ+τ−) = 1.00 ± 0.05(stat.) ± 0.08(syst.) ± 0.04(lumi.)nb, which is in good agreement with the next-to-next-to-leading order QCD prediction and improves on previous measurements in the Z → e+e− and μ+μ− channels. The reconstruction efficiency for hadronic τ decays is determined with a precision of 7%.
119107795
Improved Resummation Prediction on Higgs Boson Production at Hadron Colliders
We improve the resummation calculations in the ResBos program for the Higgs boson production via gluon-gluon fusion by including the NNLO Wilson coefficient functions and G-functions. The improvement leads to increasing the total cross section predictions of the new ResBos program, dubbed as ResBos2, for Higgs boson production by about 8% and 6% at the Tevatron and the LHC, respectively, as compared to the old ResBos program. Furthermore, the improved predictions are compared with those from the programs HNNLO and HqT2. We find that they agree well for the total cross sections but differ slightly for the transverse momentum QT distributions. With ResBos2, we present the distributions of the two variables aT and � � , which can have better experimental resolutions than QT, for the process of Higgs boson decaying into a photon pair. Theoretical uncertainties of the ResBos2 predictions are also discussed.
10328357
Results of the SLAC LCLS gun high-power RF tests
The beam quality and operational requirements for the Linac coherent light source (LCLS) currently being constructed at SLAC are exceptional, requiring the design of a new RF photocathode gun for the electron source. Based on operational experience at SLAC's GTF and SDL and ATF at BNL as well as other laboratories, the 1.6 cell s-band (2856 MHz) gun was chosen to be the best electron source for the LCLS, however a significant re-design was necessary to achieve the challenging parameters. Detailed 3-D analysis and design was used to produce near-perfect rotationally symmetric rf fields to achieve the emittance requirement. In addition, the thermo-mechanical design allows the gun to operate at 120 Hz and a 140 MV/m cathode field, or to an average power dissipation of 4 kW. Both average and pulsed heating issues are addressed in the LCLS gun design. The first LCLS gun is now fabricated and has been operated with high-power RF. The results of these high-power tests are presented and discussed.
47642067
Measurement of b-hadron masses
Measurements of b-hadron masses are performed with the exclusive decay modes B+ -> J/\psi\ K+, B0 -> J/\psi\ K*0, B0 -> J/\psi\ K0S, B0s -> J/\psi\ \phi\ and {\Lambda}b -> J/\psi\ \Lambda\ using an integrated luminosity of 35 pb-1 collected in pp collisions at a centre-of-mass energy of 7 TeV by the LHCb experiment. The momentum scale is calibrated with J/\psi\ -> \mu+\mu- decays and verified to be known to a relative precision of 2 x 10-4 using other two-body decays. The results are more precise than previous measurements, particularly in the case of the B0s and {\Lambda}b masses.