213 research outputs found
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Polarized proton-neutron total cross sections from proton-deuteron data
Simple expressions are derived for the polarized proton-deuteron total cross sections. Possibilities of extraction of the polarized proton-neutron cross sections from the proton-deuteron data are discussed. 19 references
Strangeness-Conserving Hadronic Parity Violation at Low Energies
The parity-violating nucleon-nucleon interaction is the key to understanding
the strangeness-conserving hadronic weak interaction at low energies. In this
brief talk, I review the past accomplishments in and current status of this
subject, and outline a new joint effort between experiment and theory that
tries to address the potential problems in the past by focusing on parity
violation in few-nucleon systems and using the language of effective field
theory.Comment: 8 pages, to appear in the proceedings of the Second Meeting of the
APS Topical Group on Hadronic Physics, Nashville, TN, USA, Oct. 22-24, 200
Evidence for Color Fluctuations in Hadrons from Coherent Nuclear Diffraction}
A QCD-based treatment of projectile size fluctuations is used to compute
inelastic diffractive cross sections for coherent
hadron-nuclear processes. We find that fluctuations near the average size give
the major contribution to the cross section with contribution
from small size configurations.
The computed values of are consistent with the limited
available data. The importance of coherent diffraction studies for a wide range
of projectiles for high energy Fermilab fixed target experiments is emphasized.
The implications of these significant color fluctuations for relativistic heavy
ion collisions are discussed.Comment: Report number DOE/ER 40427-13-N93 11 pages, 3 figures available from
author Mille
Parity Violation in gamma proton Compton Scattering
A measurement of parity-violating spin-dependent gamma proton Compton
scattering will provide a theoretically clean determination of the
parity-violating pion-nucleon coupling constant . We
calculate the leading parity-violating amplitude arising from one-loop pion
graphs in chiral perturbation theory. An asymmetry of ~5 10^{-8} is estimated
for Compton scattering of 100 MeV photons.Comment: 6 pages, 1 figure, latex. Reference adde
Probing Short Range Nucleon Correlations in High Energy Hard Quasielastic pd Reactions
We show that the strong dependence of the amplitude for hard scattering
on the collision energy can be used to magnify the effects of short range
nucleon correlations in quasielastic scattering. Under specific
kinematical conditions the effect of initial and final state interactions can
be accounted for by rescaling the cross section calculated within the plane
wave impulse approximation. The feasibility to investigate the role of
relativistic effects in the deuteron wave function is demonstrated by comparing
the predictions of different formalisms. Binding effects due to short range
correlations in deuteron are discussed as well.Comment: 18 pages (LaTex) + 10 postscript figs (available on request
Dijet production as a centrality trigger for p-p collisions at CERN LHC
We demonstrate that a trigger on hard dijet production at small rapidities
allows to establish a quantitative distinction between central and peripheral
collisions in pbar-p and p-p collisions at Tevatron and LHC energies. Such a
trigger strongly reduces the effective impact parameters as compared to minimum
bias events. This happens because the transverse spatial distribution of hard
partons (x >~ 10^{-2}) in the proton is considerably narrower than that of soft
partons, whose collisions dominate the total cross section. In the central
collisions selected by the trigger, most of the partons with x >~ 10^{-2}
interact with a gluon field whose strength rapidly increases with energy. At
LHC (and to some extent already at Tevatron) energies the strength of this
interaction approaches the unitarity ('black-body') limit. This leads to
specific modifications of the final state, such as a higher probability of
multijet events at small rapidities, a strong increase of the transverse
momenta and depletion of the longitudinal momenta at large rapidities, and the
appearance of long-range correlations in rapidity between the forward/backward
fragmentation regions. The same pattern is expected for events with production
of new heavy particles (Higgs, SUSY). Studies of these phenomena would be
feasible with the CMS-TOTEM detector setup, and would have considerable impact
on the exploration of the physics of strong gluon fields in QCD, as well as the
search for new particles at LHC.Comment: 17 pages, Revtex 4, 14 EPS figures. Expanded discussion of some
points, added 3 new figures and new references. Included comment on
connection with cosmic ray physics near the GZK cutoff. To appear in Phys Rev
Quadrupole deformation of deuterons and final state interaction in scattering on tensor polarized deuterons at CEBAF energies
The strength of final state interaction (FSI) between struck proton and
spectator neutron in scattering depends on the alignment of
the deuteron. We study the resulting FSI effects in the tensor analyzing power
in detail and find substantial FSI effects starting at still low missing
momentum p_m \gsim 0.9 fm^{-1}. At larger p_m \gsim 1.5 fm^{-1}, FSI
completely dominates both missing momentum distribution and tensor analyzing
power. We find that to a large extent FSI masks the sensitivity of the tensor
analyzing power to models of the deuteron wave function. For the transversely
polarized deuterons the FSI induced forward-backward asymmetry of the missing
momentum distribution is shown to have a node at precisely the same value of
as the PWIA missing momentum distribution. The position of this node is
not affected by FSI and can be a tool to distinguish experimentally between
different models for the deuteron wave function.Comment: 24 pages, figures available from the authors on reques
Elastic Nd scattering at intermediate energies as a tool for probing the short-range deuteron structure
A calculation of the deuteron polarization observables , ,
, and the differential cross-section for elastic
nucleon-deuteron scattering at incident deuteron energies 270 and 880 MeV in
lab is presented. A comparison of the calculations with two different deuteron
wave-functions derived from the Bonn-CD -potential model and the dressed
bag quark model is carried out. A model-independent approach, based on an
optical potential framework, is used in which a nucleon-nucleon -matrix is
assumed to be local and taken on the energy shell, but still depends on the
internal nucleon momentum in a deuteron.Comment: 15 pages, 4 figure
Thermal Properties of an Inflationary Universe
An energetic justification of a thermal component during inflation is given.
The thermal component can act as a heat reservoir which induces thermal
fluctuations on the inflaton field system. We showed previously that such
thermal fluctuations could dominate quantum fluctuations in producing the
initial seeds of density perturbations. A Langevin-like rate equation is
derived from quantum field theory which describes the production of
fluctuations in the inflaton field when acted upon by a simple modeled heat
reservoir. In a certain limit this equation is shown to reduce to the standard
Langevin equation, which we used to construct "Warm Inflation" scenarios in
previous work. A particle physics interpretation of our system-reservoir model
is offered.Comment: 28 pages, 0 figures, In Press Physical Review D 199
Reggeon and pion contributions in semi-exclusive diffractive processes at HERA
A detailed analysis of semi-exclusive diffractive processes in e-p DIS at
HERA, with the diffractive final states in the forward direction is presented.
The contributions of the subleading f_2, \omega, a_2, \rho reggeons and the
pion exchanges to the diffractive structure function with the forward proton or
neutron are estimated. It is found that the (a_2,\rho) reggeons are entirely
responsible for the forward neutron production at x_P < 10^{-3}. The \pi N
production in the forward region is estimated using the Deck mechanism. The
significance of this reaction for the processes measured at HERA, especially
with the leading neutron, is discussed.Comment: Strongly revised version accepted for publication in Phys.Rev.D.
Latex, 14 pages with 5 eps figures include
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