3,887 research outputs found
Double longitudinal-spin asymmetries in production at RHIC
The double longitudinal-spin asymmetry, , of the production
in polarized proton-proton collisions is presented in this paper at QCD
next-to-leading order. It is found that the obtained values of are in
general consistent with the PHENIX measurements. Various sets of the
long-distance matrix elements (LDMEs) are employed in our calculation to study
the possible theoretical uncertainties. It is found that, for p_t<5\gev, all
these LDMEs lead to almost the same results, which are within the tolerance of
the experimental data uncertainties
production and suppression in high energy proton-nucleus collisions
We apply a Color Glass Condensate+Non-Relativistic QCD (CGC+NRQCD) framework
to compute production in deuteron-nucleus collisions at RHIC and
proton-nucleus collisions at the LHC. Our results match smoothly at high
to a next-to-leading order perturbative QCD + NRQCD computation.
Excellent agreement is obtained for spectra at RHIC and LHC for
central and forward rapidities, as well as for the normalized ratio of
these results to spectra in proton-proton collisions. In particular, we observe
that the data is strongly bounded by our computations of the same for
each of the individual NRQCD channels; this result provides strong evidence
that our description is robust against uncertainties in initial conditions and
hadronization mechanisms.Comment: 7 pages, 4 figure
QCD corrections to Upsilon production via color-octet states at the Tevatron and LHC
The NLO QCD corrections to Upsilon production via S-wave color-octet states
Upsilon(^1S_0^8,^3S_1^8) at the Tevatron and LHC is calculated. The K factors
of total cross section (ratio of NLO to LO) are 1.313 and 1.379 for
Upsilon(^1S_0^8) and Upsilon(^3S_1^8) at the Tevatron, while at the LHC they
are 1.044 and 1.182, respectively. By fitting the experimental data from the
D0, the matrix elements for S-wave color-octet states are obtained. And new
predictions for Upsilon production are presented. The prediction for the
polarization of inclusive Upsilon contains large uncertainty rising from the
polarization of Upsilon from feed-down of chi_b. To further clarify the
situation, new measurements on the production and polarization for direct
Upsilon are expected.Comment: 13 pages, 10 Figure
- β¦