190 research outputs found
Proton-deuteron asymmetry in Drell-Yan processes and polarized light-antiquark distributions
We discuss the relation between the ratio of the proton-deuteron (pd)
Drell-Yan cross section to the proton-proton (pp) one \Delta_{(T)}
\sigma_{pd}/2 \Delta_{(T)} \sigma_{pp} and the flavor asymmetry in polarized
light-antiquark distributions. Using a recent formalism of the polarized pd
Drell-Yan process, we show that the difference between the pp and pd cross
sections is valuable for finding not only the flavor asymmetry in
longitudinally polarized antiquark distributions but also the one in
transversity distributions. It is especially important that we point out the
possibility of measuring the flavor asymmetry in the transversity distributions
because it cannot be found in W production processes and inclusive lepton
scattering due to the chiral-odd property.Comment: 10 pages, LATEX2e with epsfig.sty, 4 eps figures. Complete postscript
file including the figures is available at http://www-hs.phys.saga-u.ac.jp .
Email: [email protected], [email protected]
Recent tests for the statistical parton distributions
We compare some recent experimental results obtained at DESY, SLAC and
Jefferson Lab., with the predictions of the statistical model, we have
previously proposed. The result of this comparison is very satisfactory.Comment: 12 pages, 6 eps figures, version to appear in Mod. Phys. Lett.
Spin-Spin Asymmetries in Large Transverse Momentum Higgs Boson Production
We examine the spin-dependence of standard model Higgs boson production at
large transverse momentum via the processes , , and . The partonic level
spin-spin asymmetries () for these processes are large at SSC/LHC
energies.Comment: 10 pages, 4 figures (not included), LaTeX; PSU/TH/113, MAD/PH/70
Eikonal representation in the momentum-transfer space
By means of empirical fits to the differential cross section data on pp and
p(bar)p elastic scattering, above 10 GeV (center-of-mass energy), we determine
the eikonal in the momentum - transfer space (q^2- space). We make use of a
numerical method and a novel semi-analytical method, through which the
uncertainties from the fit parameters can be propagated up to the eikonal in
the - space. A systematic study of the effect of the experimental
information at large values of the momentum transfer is developed and discussed
in detail. We present statistical evidence that the imaginary part of the
eikonal changes sign in the q^2- space and that the position of the zero
decreases as the energy increases; after the position of the zero, the eikonal
presents a minimum and then goes to zero through negative values. We discuss
the applicability of our results in the phenomenological context, outlining
some connections with nonperturbative QCD. A short review and a critical
discussion on the main results concerning "model-independent" analyses are also
presented.Comment: 18 pages, 17 figures, 4 tables, svjour.cls. Revised discussion on the
proton's electromagnetic form factor and references added. To appear in Eur.
Phys. J.
Stringent constraints on the scalar K pi form factor from analyticity, unitarity and low-energy theorems
We investigate the scalar K pi form factor at low energies by the method of
unitarity bounds adapted so as to include information on the phase and modulus
along the elastic region of the unitarity cut. Using at input the values of the
form factor at t=0 and the Callan-Treiman point, we obtain stringent
constraints on the slope and curvature parameters of the Taylor expansion at
the origin. Also, we predict a quite narrow range for the higher order ChPT
corrections at the second Callan-Treiman point.Comment: 5 pages latex, uses EPJ style files, 3 figures, replaced with version
accepted by EPJ
A Transient New Coherent Condition of Matter: The Signal for New Physics in Hadronic Diffractive Scattering
We demonstrate the existence of an anomalous structure in the data on the
diffractive elastic scattering of hadrons at high energies and small momentum
transfer. We analyze five sets of experimental data on
scattering from five different experiments with colliding beams, ranging from
the first-- and second--generation experiments at GeV to the
most recent experiments at 546 GeV and at 1800 GeV. All of the data sets
exhibit a localized anomalous structure in momentum transfer. We represent the
anomalous behavior by a phenomenological formula. This is based upon the idea
that a transient coherent condition of matter occurs in some of the
intermediate inelastic states which give rise, via unitarity, to diffractive
elastic scattering. The Fourier--Bessel transform into momentum--transfer space
of a spatial oscillatory behavior of matter in the impact--parameter plane
results in a small piece of the diffractive amplitude which exhibits a
localized anomalous behavior near a definite value of . In addition, we
emphasize possible signals coming directly from such a new condition of matter
that may be present in current experiments on inelastic processes.Comment: 25 pages, LaTeX (12 figures, not included). A complete postscript
file (except figures 1 and 11, which are available upon request) is available
via anonymous ftp at ttpux2.physik.uni-karlsruhe.de (129.13.102.139) as
/ttp94-03 /ttp94-03.ps, Local preprint# TTP94-03 (March 1994
Experimental Evidence for Simple Relations between Unpolarized and Polarized Parton Distributions
The Pauli exclusion principle is advocated for constructing the proton and
neutron deep inelastic structure functions in terms of Fermi-Dirac
distributions that we parametrize with very few parameters. It allows a fair
description of the recent NMC data on and at
, as well as the CCFR neutrino data at and . We
also make some reasonable and simple assumptions to relate unpolarized and
polarized quark parton distributions and we obtain, with no additional free
parameters, the spin dependent structure functions and
. Using the correct evolution, we have checked that they
are in excellent agreement with the very recent SMC proton data at and the SLAC neutron data at .Comment: 17 pages,CPT-94/P.3032,latex,6 fig available on cpt.univ-mrs.fr
directory pub/preprints/94/fundamental-interactions /94-P.303
Gluon Fusion: A Probe of Higgs Sector CP Violation
We demonstrate that CP violation in the Higgs sector, \eg\ of a multi-doublet
model, can be directly probed using gluon-gluon collisions at the SSC. %
requires phyzzx.tex macro packageComment: UCD-93-
Statistical approach for unpolarized fragmentation functions for the octet baryons
A statistical model for the parton distributions in the nucleon has proven
its efficiency in the analysis of deep inelastic scattering data, so we propose
to extend this approach to the description of unpolarized fragmentation
functions for the octet baryons. The characteristics of the model are
determined by using some data on the inclusive production of proton and
in unpolarized deep inelastic scattering and a next-to-leading
analysis of the available experimental data on the production of unpolarized
octet baryons in annihilation. Our results show that both parton
distributions and fragmentation functions are compatible with the statistical
approach, in terms of a few free parameters, whose interpretation will be
discussed.Comment: 14 pages, 7 eps figures, to appear in Phys. Rev.
Hadronic production and the Gottfried Sum Rule
The difference in production rate between and at hadron colliders
is very sensitive to the the difference between up- and down-quark
distributions in the proton. This sensitivity allows for a variety of useful
measurements. We consider the difference in the sea
distributions and the difference in the
polarized parton distribution functions. In both cases we construct an
asymmetry to reduce systematic uncertainties. Although we discuss measurements
at the Tevatron and future hadron colliders, we find that the Brookhaven
Relativistic Heavy Ion Collider (RHIC) is the most appropriate hadron collider
for these measurements.Comment: 19 pages (20 figures available from the authors), MAD/PH/74
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