119110977
QED contribution to the production of J/psi + c anti-c + X at the Tevatron and LHC
We calculate {alpha}{sup 2}{alpha}{sub s}{sup 2} order QED contribution to J/{psi} production in the pp(p){yields}J/{psi}+cc color-singlet process at the Tevatron and LHC in the framework of nonrelativistic QCD. The contribution of the interference between the {alpha}{sup 2}{alpha}{sub s}{sup 2} QED and {alpha}{sub s}{sup 4} QCD is also taken into account. The J/{psi} production associated with a charm-quark pair could be a measurable signal at hadron collider experiment. Our calculations show that by including the QED contribution, the p{sub t} distribution is enhanced by a factor of 1.5 (1.9) at the Tevatron (LHC) at p{sub t}=50(100) GeV. In addition, the polarization of J/{psi} turns from unpolarized in all regions to increasingly transverse when p{sub t} becomes larger.
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.
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.
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.
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.
37672579
Search for heavy neutrinos and $$\mathrm {W}$$W bosons with right-handed couplings in proton–proton collisions at $$\sqrt{s} = 8\,\text {TeV} $$s=8TeV
A search for heavy, right-handed neutrinos, $$\mathrm {N}_{\ell }$$Nℓ ($$\ell = \mathrm {e}, \mu $$ℓ=e,μ), and right-handed $$\mathrm {W}_{\mathrm {R}}$$WR bosons, which arise in the left-right symmetric extensions of the standard model, has been performed by the CMS experiment. The search was based on a sample of two lepton plus two jet events collected in proton–proton collisions at a center-of-mass energy of 8$$\,\text {TeV}$$TeV corresponding to an integrated luminosity of 19.7 $$\mathrm{fb}^{-1}$$fb-1. For models with strict left-right symmetry, and assuming only one $$\mathrm {N}_{\ell }$$Nℓ flavor contributes significantly to the $$\mathrm {W}_{\mathrm {R}}$$WR decay width, the region in the two-dimensional $$(M_{\mathrm {W}_{\mathrm {R}}}, M_{\mathrm {N}_{\ell }})$$(MWR,MNℓ) mass plane excluded at a 95 % confidence level extends to approximately $$M_{\mathrm {W}_{\mathrm {R}}} = 3.0\,\text {TeV} $$MWR=3.0TeV and covers a large range of neutrino masses below the $$\mathrm {W}_{\mathrm {R}}$$WR boson mass, depending on the value of $$M_{\mathrm {W}_{\mathrm {R}}}$$MWR. This search significantly extends the $$(M_{\mathrm {W}_{\mathrm {R}}}, M_{\mathrm {N}_{\ell }})$$(MWR,MNℓ) exclusion region beyond previous results.
119257780
Model independent analysis of top quark forward-backward asymmetry at the Tevatron up to $\mathcal{O}(\as^2/\Lambda^2)$
We present the complete calculations of the forward-backward asymmetry ($A_{\rm FB}$) and the total cross section of top quark pair production induced by dimension-six four quark operators at the Tevatron up to $\mathcal{O}(\as^2/\Lambda^2)$. Our results show that next-to-leading order (NLO) QCD corrections can change $A_{\rm FB}$ and the total cross section by about 10%. Moreover, NLO QCD corrections reduce the dependence of $A_{\rm FB}$ and total cross section on the renormalization and factorization scales significantly. We also evaluate the total cross section and the charge asymmetry ($A_{\rm C}$) induced by these operators at the Large Hadron Collider (LHC) up to $\mathcal{O}(\as^2/\Lambda^2)$, for the parameter space allowed by the Tevatron data. We find that the value of $A_{\rm C}$ induced by these operators is much larger than SM prediction, and LHC has potential to discover these NP effects when the measurement precision increases.
49389105
DESIGN OF MAIN RING DIPOLE POWER SUPPLY FOR HIRFL-CSR *
This paper introduces the main circuit topologic, control method and double reference setting system of a dipole power supply which is the pivotal device of the HIRFL-CSR (Heavy Ion Research Facility in LanzhouCooling Storage Ring). The power supply works at the pulse mode, with the peak output power of 3.15MW (3000A, 1045V). To fulfil difficult requirements especially for the tracking error, which is needed less than 300ppm, a special topologic is adopted. The power supply has two parts: SCR rectifier provides the most energy and PWM converter provides correcting current and perfect reaction for tracking current setting. Now the dipole power supply is performing well during the CSR commissioning, with the perfect tracking error, well longtime stability and low ripple current. INTRODUCTION OF THE POWER SUPPLY The power supply is a pivotal device of HIRFL-CSR (Heavy Ion Research Facility in Lanzhou-Cooling Storage Ring), and it is a synchronized one. This synchronized power supply’s output current must track the setting as Fig. 1. Figure 1: Plots of current and ideal voltage. In Fig. 1, the output voltage only happens at the ideal state. For heavy iron beam acceleration, the most important requirements on the power supply are listed below: Peak output power 3.15MW (3000A/1045V) Tracking error less than 200ppm Current stability better than 3×10 This power supply works at two modes, one is the DC output mode and the other is Pulse output mode, in most cases the control system’s parameters are different at the two modes. DIPOLE POWER SUPPLY’S SCHEMATIC DIAGRAM To fulfil these stringent requirements as mentioned above, our dipole power supply has two parts: SCR rectifier and switching mode DC converter. Fig. 2 shows the schematic diagram of the power supply. In part one, we use 12 SCRs and connect them into two serial normal 3-phases SCR rectifiers. The transformer’s input comes from 10KV power line, and the second side output voltage is 495V.This part provides the most output power (95%). IGBT is adopted in part two, which consists of 4 DC converters. Each DC converter uses a full-Bridge topologic and be connected in serial mode to supply the high-voltage output capability. As we all know, the traditional SCR rectifier has advantages of high power output ability, high credibility and low-cost. But the SCR rectifier also has disadvantage of slow response in synchronized power supply. For the reason mentioned above, the switching mode converter is used to improve the fast-response ability. The very high switching frequency of IGBT makes it easy to control the power supply’s output with a small tracking error. But the switching mode rectifier is of high-cost. In our power supply, we use the advantages of the two modes. It means that the SCR rectifier provides the most output power and the switching mode rectifier provides the fast-response ability for current tracking. There is a balance between the output powers of the two parts. In this power supply, the switching part can supply maximum current up to 200A, but in most cases this part’s maximum output is less than 200A. The maximum output is controlled by a constant input, which is introduced in the following part of this paper.
41932053
Probing color coherence effects in pp collisions at $$\sqrt{s}=7\,\text {TeV} $$s=7TeV
A study of color coherence effects in pp collisions at a center-of-mass energy of 7$$\,\text {TeV}$$TeV is presented. The data used in the analysis were collected in 2010 with the CMS detector at the LHC and correspond to an integrated luminosity of 36 pb$$^{-1}$$-1. Events are selected that contain at least three jets and where the two jets with the largest transverse momentum exhibit a back-to-back topology. The measured angular correlation between the second- and third-leading jet is shown to be sensitive to color coherence effects, and is compared to the predictions of Monte Carlo models with various implementations of color coherence. None of the models describe the data satisfactorily.