Dominant spin-flip effects for the hadronic-produced J / ψ polarization at the Tevatron

We study the first-order relativistic correction to the associated production of J/ψ with light hadrons at B factory experiments at √ s = 10.58 GeV, in the context of NRQCD factorization.We employ a strategy for NRQCD expansion that slightly deviates from the orthodox doctrine, in that the matching coefficients are not truly of "short-distance" nature, but explicitly depend upon physical kinematic variables rather than partonic ones. Our matching method, with validity guaranteed by the Gremm-Kapustin relation, is particularly suited for the inclusive quarkonium production and decay processes with involved kinematics, exemplified by the process e + e − → J/ψ + gg considered in this work. Despite some intrinsic ambiguity affiliated with the orderv 2 NRQCD matrix element, if we choose its value as what has been extracted from a recent Cornell-potential-model-based analysis, including the relative order-v 2 effect is found to increase the lowest-order prediction for the integrated J/ψ cross section by about 30%, and exert a modest impact on J/ψ energy, angular and polarization distributions except near the very upper end of the J/ψ energy. The order-v 2 contribution to the energy spectrum becomes logarithmically divergent at the maximum of J/ψ energy. A consistent analysis may require that these large end-point logarithms be resummed to all orders in α s .

Color-singlet relativistic correction to inclusiveJ/ψproduction associated with light hadrons atBfactories

Jia

2010

Relativistic correction to color-octetJ/ψproduction at hadron colliders

Liu

et al. 2012

The relativistic corrections to the color-octet J/ψ hadroproduction at the Tevatron and LHC are calculated up to O(v 2 ) in nonrelativistic QCD factorization frame. The short distance coefficients are obtained by matching full QCD with NRQCD results for the partonic subprocessThe short distance coefficient ratios of relativistic correction to leading order for color-octet1 , and 3 P [8] J at large p T are approximately -5/6, -11/6, and -31/30, respectively, for each subprocess, and it is 1/6 for color-singlet state 3 S[1]1 . If the higher order long distance matrix elements are estimated through velocity scaling rule with adopting v 2 = 0.23 and the lower order long distance matrix elements are fixed, the leading order cross sections of color-octet states are reduced by about a factor of 20 ∼ 40% at large p T at both the Tevatron and the LHC. Comparing with QCD radiative corrections to color-octet states, relativistic correction is ignored along with p T increasing. Using long distance matrix elements extracted from the fit to J/ψ production at the Tevatron, we can find the unpolarization cross sections of J/ψ production at the LHC taking into account both QCD and relativistic corrections are changed by about 20 ∼ 50% of that considering only QCD corrections. These results indicate that relativistic corrections may play an important role in J/ψ production at the Tevatron and the LHC. PACS numbers: 12.38.Bx,12.39.St,13.85.Ni * Electronic address:

Heavy quarkonium production through the semi-exclusivee+e−annihilation channels round theZ0peak

Sun

Chen

et al. 2013

Self Cite

Within the framework of the non-relativistic QCD, we present a detailed discussion on the heavy quarkonium production at the leading order in αs at a e + e − collider with the collision energy around the Z 0 peak. Quarkonia are produced through the semi-exclusive channels e + e − → |H QQ + X with X = QQ or gg, where Q indicates a heavy quark (respectively b or c). It is noted that in addition to the color-singlet 1S-level quarkonium states, the 2S and 1P color-singlet states and the color-octet |(QQ)[1 3 S1 ]g state also provide sizable contributions. The heavy quarkonium transverse momentum and rapidity distributions for the e + e − collision energy Ecm = mZ are presented. For both charmonium and bottomonium production via the Z 0 propagator, there is approximate "spin degeneracy" between the spin-triplet and spin-singlet quarkonium states. Uncertainties for the total cross sections are estimated by taking mc = 1.50 ± 0.15 GeV and m b = 4.90 ± 0.15 GeV. Around Ecm = mZ, due to the Z 0 -boson resonance effect, total cross sections for the channels via the Z 0 -propagator become much larger than the channels via the virtual photon propagator. We conclude that, in addition to the B factories as BaBar and Belle and the hadronic colliders as Tevatron and LHC, such a super Z-factory will present an excellent platform for studying the heavy quarkonium properties.