119213652
Production of $B_c$ or $\bar{B}_c$ meson and its excited states via $\bar{t}$ quark or $t$ quark decays
The production of (bc)-quarkonium (B{sub c} meson and its excited states) or (cb)-quarkonium (B{sub c} meson and its excited states) via top quark t or top antiquark t decays, t{yields}(bc)+c+W{sup +} or t{yields}(cb)+c+W{sup -}, respectively, is studied within the framework of NRQCD. In addition to the production of the two color-singlet S-wave states |(bc)({sup 1}S{sub 0}){sub 1}> or |(cb)({sup 1}S{sub 0}){sub 1}> and |(bc)({sup 3}S{sub 1}){sub 1}> or |(cb)({sup 3}S{sub 1}){sub 1}>, the production of the P-wave excited (bc) or (cb) states, i.e. the four color-singlet P-wave states |(bc)({sup 1}P{sub 1}){sub 1}> or |(cb)({sup 1}P{sub 1}){sub 1}>, and (bc)({sup 3}P{sub J}){sub 1}> or (cb)({sup 3}P{sub J}){sub 1}> (with J=(1,2,3)), is also studied. According to the velocity scaling rule of NRQCD, for the production of P-wave excited states the contributions from the two color-octet components |(bc)({sup 1}S{sub 0}){sub 8}> or |(cb)({sup 1}S{sub 0}){sub 8}> and |(bc)({sup 3}S{sub 1}){sub 8}> or |(cb)({sup 3}S{sub 1}){sub 8}> are also taken into account. We quantitatively discuss the possibility and the advantages in experimental studies of B{sub c} or B{sub c} meson and its excited states via the indirect production at LHC in high luminosity runs and at LHC possible upgraded versions such as SLHC, DLHC,more » TLHC, etc. in the future.« less
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)
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.
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.
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.
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.
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.
201238536
Measurements of spin correlation in top-antitop quark events from proton-proton collisions at √s =7 TeV using the ATLAS detector
Measurements of spin correlation in top quark pair production are presented using data collected with the ATLAS detector at the LHC with proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 4.6 fb(-1). Events are selected in final states with two charged leptons and at least two jets and in final states with one charged lepton and at least four jets. Four different observables sensitive to different properties of the top quark pair production mechanism are used to extract the correlation between the top and antitop quark spins. Some of these observables are measured for the first time. The measurements are in good agreement with the Standard Model prediction at next-to-leading-order accuracy.
118146782
Amplitude analysis and the branching fraction measurement of $\bar{B}^0_s \to J/\psi K^+K^-$
An amplitude analysis of the final state structure in the Bs0→J/ψK+K- decay mode is performed using 1.0  fb-1 of data collected by the LHCb experiment in 7 TeV center-of-mass energy pp collisions produced by the LHC. A modified Dalitz plot analysis of the final state is performed using both the invariant mass spectra and the decay angular distributions. Resonant structures are observed in the K+K- mass spectrum as well as a significant non-resonant S-wave contribution over the entire K+K- mass range. The largest resonant component is the ϕ(1020), accompanied by f0(980), f2′(1525), and four additional resonances. The overall branching fraction is measured to be B(Bs0→J/ψK+K-)=(7.70±0.08±0.39±0.60)×10-4, where the first uncertainty is statistical, the second systematic, and the third due to the ratio of the number of Bs0 to B- mesons produced. The mass and width of the f2′(1525) are measured to be 1522.2±2.8-2.0+5.3  MeV and 84±6-5+10  MeV, respectively. The final state fractions of the other resonant states are also reported.
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.
16824048
How Saturated Are Absorption Lines in the Broad Absorption Line Quasar PG 1411+442?
Recently, convincing evidence was found for extremely large X-ray absorption by column densities greater than 1023 cm-2 in broad absorption line quasars. One consequence of this is that any soft X-ray emission from these QSOs would be the scattered light or leaked light from partially covering absorbing material. A detection of the unabsorbed soft X-ray and absorbed hard X-ray component will allow us to determine the total column density as well as the effective covering factor of the absorbing material, which are difficult to obtain from the UV absorption lines. Brinkmann et al. recently showed that both the unabsorbed and absorbed components are detected in the nearby very bright broad absorption line quasar PG 1411+442. In this Letter, we make a further analysis of the broadband X-ray spectrum and the UV spectrum from the Hubble Space Telescope and demonstrate that broad absorption lines are completely saturated at the bottom of absorption troughs.