69 research outputs found
Next-to-leading order QCD corrections to A_TT for prompt photon production
We present a next-to-leading order QCD calculation of the cross section for
isolated large-p_T prompt photon production in collisions of transversely
polarized protons. We devise a simple method of dealing with the phase space
integrals in dimensional regularization in the presence of the cos(2 phi)
azimuthal-angular dependence occurring for transverse polarization. Our results
allow to calculate the double-spin asymmetry A_TT for this process at
next-to-leading order accuracy, which may be used at BNL-RHIC to measure the
transversity parton distributions of the proton.Comment: 19 pages, LaTeX, 2 figures as eps file
Non-perturbative effects and the resummed Higgs transverse momentum distribution at the LHC
We investigate the form of the non-perturbative parameterization in both the
impact parameter (b) space and transverse momentum (p_T) space resummation
formalisms for the transverse momentum distribution of single massive bosons
produced at hadron colliders. We propose to analyse data on Upsilon
hadroproduction as a means of studying the non-perturbative contribution in
processes with two gluons in the initial state. We also discuss the theoretical
errors on the resummed Higgs transverse momentum distribution at the LHC
arising from the non-perturbative contribution.Comment: 22 pages, 10 figure
New Fits for the Non-Perturbative Parameters in the CSS Resummation Formalism
We update the non-perturbative function of the Collins-Soper- Sterman
resummation formalism in hadron collisions. Two functional forms in impact
parameter space are considered, one with a pure Gaussian form with two
parameters and the other with an additional linear term. The results for the
two parameter fit are found to be g1=0.24+0.08-0.07 GeV^2, g2=0.34+0.07-0.08
GeV^2. The results for the three parameter fit are g1=0.15+004-0.03 GeV^2,
g2=0.48+0.07-0.05 GeV^2, and g3=-0.58+0.26-0.20 GeV^-1. We discuss the
potential for the full Tevatron Run I Z boson data for further testing of the
universality of the non-perturbative function.Comment: 22 pages, 12 figures, LaTe
Tau neutrino deep inelastic charged current interactions
The nu_mu -> nu_tau oscillation hypothesis will be tested through nu_tau
production of tau in underground neutrino telescopes as well as long-baseline
experiments. We provide the full QCD framework for the evaluation of tau
neutrino deep inelastic charged current (CC) cross sections, including
next-leading-order (NLO) corrections, charm production, tau threshold, and
target mass effects in the collinear approximation. We investigate the
violation of the Albright-Jarlskog relations for the structure functions F_4,5
which occur only in heavy lepton (tau) scattering. Integrated CC cross sections
are evaluated naively over the full phase space and with the inclusion of DIS
kinematic cuts. Uncertainties in our evaluation based on scale dependence, PDF
errors and the interplay between kinematic and dynamical power corrections are
discussed and/or quantified.Comment: 28 pages, 10 figure
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Multiple scattering theory for space filling potentials
Multiple scattering theory (MST) provides an efficient technique for solving the wave equation for the special case of muffin-tin potentials. Here MST is extended to treat space filling non-muffin tin potentials and its validity, accuracy and efficiency are tested by application of the two dimensional empty lattice test. For this test it is found that the traditional formulation of MST does not coverage as the number of partial waves is increased. A simple modification of MST, however, allows this problem to be solved exactly and efficiently. 15 refs., 3 tabs
How To Find Charm in Nuclear Collisions at RHIC and LHC
Measurements of dilepton production from charm decay and Drell-Yan processes
respectively probe the gluon and sea quark distributions in hadronic
collisions. In nucleus-nucleus collisions, these hard scattering processes
constitute a `background' to thermal contributions from the hot matter produced
by the collision. To determine the magnitude and behavior of this background,
we calculate the hard scattering contribution to dilepton production in nuclear
collisions at RHIC and LHC at next to leading order in perturbative QCD.
Invariant mass, rapidity and transverse momentum distributions are presented.
We compare these results to optimistic hydrodynamic estimates of the thermal
dilepton production. We find that charm production from hard scattering is by
far the dominant contribution. Experiments therefore can measure the gluon
distribution in the nuclear target and projectile and, consequently, can
provide new information on gluon shadowing. We then illustrate how experimental
cuts on the rapidity gap between the leptons can aid in reducing the charm
background, thereby enhancing thermal information.Comment: 32 pages, latex, 19 figure
Detection of Salmonella enteritidis-specific immunoglobulin A antibodies in crop samples from chickens infected with Salmonella enteritidis
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