438 research outputs found
Isolated-photon production in polarized hadronic collisions
After a short discussion on the definition of isolated-photon cross sections
in perturbative QCD, I present phenomenological predictions relevant for
polarized hadron-hadron collisions in the RHIC energy range. The possibility of
measuring is investigated.Comment: 3 pages Latex; npb.sty and 2 ps figures included. Talk given at
DIS99, 19 - 23 April 1999, Zeuthen, D
A_{LT} in the polarized Drell-Yan process at RHIC and HERA energies
We present a leading order (LO) estimate for the longitidinal-transverse spin
asymmetry (A_{LT}) in the nucleon-nucleon polarized Drell-Yan process at RHIC
and HERA- energies in comparison with A_{LL} and A_{TT}. A_{LT}
receives contribution from g_1, the transversity ditribution h_1, and the
twist-3 distributions g_T and h_L. For the twist-3 contribution we use the bag
model prediction evolved to a high energy scale by the large-N_c evolution
equation. We found that A_{LT} (normalized by the asymmetry in the parton
level) is much smaller than the corresponding A_{TT}. Twist-3 contribution
given by the bag model also turned out to be negligible.Comment: 12 pages in Latex. 5 figures included as eps files using epsbox.sty.
Minor corrections for typos and notations incorporate
Detect Gluon Polarisation at BNL-RHIC Through J/\psi Pair Production Process
Our recent study shows that the double spin asymmetry of J/\psi pair
production is measurable in polarised p-p collision at RHIC in near future. And
hence it enables us to extract the polarised gluon distribution function \Delta
G (x).Comment: Contribution to ICHEP, July 24 - 27, 2002. Amsterdam, the Netherland
Demonstration: A cloud-native digital twin with adaptive cloud-based control and intrusion detection
Digital twins are taking a central role in the industry 4.0 narrative. How-ever, they are still illusive. Many aspects of the digital-twins have yet to materialize.For example, to what degree will they be integrated into cloud and industry 4.0 sys-tems as well as how and if they should augment their physical counterpart. Thosechoices are accompanied by challenging security aspects, many of which have to bestudied partially. In this paper, we present a novel digital-twin demonstrator that en-ables experimentation and advanced research on such systems. The demonstrator iscloud-native, has a distributed adaptive control system, incorporates edge and publicclouds, a PLC, intrusion detection, a wireless network emulator, and an attacker
HERA prospects on Compositeness and New Vector Bosons
The absence of deviations from the Standard Model for the differential cross
section at HERA is used to set limits on electron quark
compositeness scale and on new vector bosons, especially the hadrophilic one
recently introduced as a possible explanation for LEP/SLC and CDF anomalies.Comment: Latex file, 7 pages and 1 ps fig, few comments on others experiments
are added, results are unchanged. To appear in Phys. Let.
Threshold resummation of Drell-Yan rapidity distributions
We present a derivation of the threshold resummation formula for the
Drell-Yan rapidity distribution. Our argument is valid for all values of
rapidity and to all orders in perturbative QCD and can be applied to all
Drell-Yan processes in a universal way, i.e. both for the production of a
virtual photon \gamma^{*} and the production of a vector boson W^{\pm}, Z^{0}.
We show that for the fixed-target experiment E866/NuSea used in current parton
fits, the NLL resummation corrections are comparable to NLO fixed-order
corrections and are crucial to obtain agreement with the data.Comment: 10 pages, 3 figures, Final versio
W boson production at hadron colliders: the lepton charge asymmetry in NNLO QCD
We consider the production of W bosons in hadron collisions, and the
subsequent leptonic decay W->lnu_l. We study the asymmetry between the rapidity
distributions of the charged leptons, and we present its computation up to the
next-to-next-to-leading order (NNLO) in QCD perturbation theory. Our
calculation includes the dependence on the lepton kinematical cuts that are
necessarily applied to select W-> lnu_l events in actual experimental analyses
at hadron colliders. We illustrate the main differences between the W and
lepton charge asymmetry, and we discuss their physical origin and the effect of
the QCD radiative corrections. We show detailed numerical results on the charge
asymmetry in ppbar collisions at the Tevatron, and we discuss the comparison
with some of the available data. Some illustrative results on the lepton charge
asymmetry in pp collisions at LHC energies are presented.Comment: 37 pages, 21 figure
NNLO corrections to massive lepton-pair production in longitudinally polarized proton-proton collisions
We present the full next-to-next-to-leading order (NNLO) coefficient
functions for the polarized cross section for the Drell-Yan
process . Here denotes any inclusive hadronic
state and represents the invariant mass of the lepton pair. All QCD
partonic subprocesses have been included provided the lepton pair is created by
a virtual photon, which is a valid approximation for GeV. Unlike the
differential distribution w.r.t. transverse momentum the dominant subprocess
for the integrated cross section is given by and
its higher order corrections so that massive lepton pair production provides us
with an excellent tool to measure the polarized anti-quark densities. Our
calculations are carried out using the method of -dimensional regularization
by making a special choice for the matrix. We give predictions for
double longitudinal spin asymmetry measurements at the RHIC.Comment: 45 pages, 22 figures. Due to a bug in our program the mass
factorization plots in fig. 8-11 are changed. All parton density sets, in
particular the set BB1 (J. Blumlein, H. Bottcher), lead to an improvement in
the scale dependence while going from LO to NLO and then to NNL
Scaling and Diffraction in Deep Inelastic Scattering
We pursue the hypothesis that the events with a large rapidity gap, observed
at HERA, reflect the scattering of electrons off lumps of wee partons inside
the proton. A simple scaling behaviour is predicted for the diffractive
structure functions, which are related to the inclusive structure function
at small values of the scaling variable . The results are
compared with recent measurements of the diffractive structure function
.Comment: 8 page
Deeply virtual Compton scattering in next-to-leading order
We study the amplitude of deeply virtual Compton scattering in
next-to-leading order of perturbation theory including the two-loop evolution
effects for different sets of skewed parton distributions (SPDs). It turns out
that in the minimal subtraction scheme the relative radiative corrections are
of order 20-50%. We analyze the dependence of our predictions on the choice of
SPD, that will allow to discriminate between possible models of SPDs from
future high precision experimental data, and discuss shortly theoretical
uncertainties induced by the radiative corrections.Comment: 10 pages, LaTeX, 3 figure
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