748 research outputs found
Coherent Vector Meson Photo-Production from Deuterium at Intermediate Energies
We analyze the cross section for vector meson photo-production off a deuteron
for the intermediate range of photon energies starting at a few GeVs above the
threshold and higher. We reproduce the steps in the derivation of the
conventional non-relativistic Glauber expression based on an effective
diagrammatic method while making corrections for Fermi motion and intermediate
energy kinematic effects. We show that, for intermediate energy vector meson
production, the usual Glauber factorization breaks down and we derive
corrections to the usual Glauber method to linear order in longitudinal nucleon
momentum. The purpose of our analysis is to establish methods for probing
interesting physics in the production mechanism for phi-mesons and heavier
vector mesons. We demonstrate how neglecting the breakdown of Glauber
factorization can lead to errors in measurements of basic cross sections
extracted from nuclear data.Comment: 41 pages, 13 figures, figure 9 is compressed from previous version,
typos fixe
Scattering from Singular Potentials in Quantum Mechanics
In non-relativistic quantum mechanics, singular potentials in problems with
spherical symmetry lead to a Schrodinger equation for stationary states with
non-Fuchsian singularities both as r tends to zero and as r tends to infinity.
In the sixties, an analytic approach was developed for the investigation of
scattering from such potentials, with emphasis on the polydromy of the wave
function in the r variable. The present paper extends those early results to an
arbitrary number of spatial dimensions. The Hill-type equation which leads, in
principle, to the evaluation of the polydromy parameter, is obtained from the
Hill equation for a two-dimensional problem by means of a simple change of
variables. The asymptotic forms of the wave function as r tends to zero and as
r tends to infinity are also derived. The Darboux technique of intertwining
operators is then applied to obtain an algorithm that makes it possible to
solve the Schrodinger equation with a singular potential containing many
negative powers of r, if the exact solution with even just one term is already
known.Comment: 19 pages, plain Tex. In this revised version, the analysis of Eq.
(5.29) has been amended, and an appendix has been added for completenes
The p(d,p)d and p(d,p)pn reactions as a tool for the study of the short range internal structure of the deuteron
In recent time the deuteron structure at short distances is often treated
from the point of view nonnucleonic degrees of freedom. In this paper the
measurements of T-odd polarization observables using tensor polarized deuteron
beam and polarized proton target or proton polarimeter are proposed to search
the quark configurations inside the deuteron.Comment: 12 pages, 8 Postscript figures, submitted in Phys.Atom.Nuc
Diffractive Phenomena and Shadowing in Deep-Inelastic Scattering
Shadowing effects in deep-inelastic lepton-nucleus scattering probe the mass
spectrum of diffractive leptoproduction from individual nucleons. We explore
this relationship using current experimental information on both processes. In
recent data from the NMC and E665 collaboration, taken at small x << 0.1 and
Q^2 < 1 GeV^2, shadowing is dominated by the diffractive excitation and
coherent interaction of low mass vector mesons. If shadowing is explored at
small x > 1 GeV^2 as discussed at HERA, the situation is
different. Here dominant contributions come from the coherent interaction of
diffractively produced heavy mass states. Furthermore we observe that the
energy dependence of shadowing is directly related to the mass dependence of
the diffractive production cross section for free nucleon targets.Comment: 12 pages Latex, 8 figure
Hard Parton Rescatterings and Minijets in Nuclear Collisions at LHC
The average number of minijets and the corresponding transverse energy
produced in heavy ion collisions are evaluated by including explicitly
semi-hard parton rescatterings in the dynamics of the interaction. At the LHC
semi-hard rescatterings have a sizable effect on global characteristics of the
typical inelastic event. An interesting feature is that the dependence on the
cutoff which separates soft and hard parton interactions becomes less critical
after taking rescatterings into account.Comment: 14 pages, 3 figures. Enlarged discussion in sect.1 and 4; 1 figure
added. To be published in Phys.Rev.
Color Transparency Effects in Electron Deuteron Interactions at Intermediate Q^2
High momentum transfer electrodisintegration of polarized and unpolarized
deuterium targets, is studied. We show that the importance of final
state interactions-FSI, occuring when a knocked out nucleon interacts with the
other nucleon, depends strongly on the momentum of the spectator nucleon. In
particular, these FSI occur when the essential contributions to the scattering
amplitude arise from internucleon distances . But the absorption
of the high momentum may produce a point like configuration, which
evolves with time. In this case, the final state interactions probe the point
like configuration at the early stage of its evolution. The result is that
significant color transparency effects, which can either enhance or suppress
computed cross sections, are predicted to occur for .Comment: 37 pages LaTex, 12 uuencoded PostScript Figures as separate file, to
be published in Z.Phys.
Multiparton interactions and production of minijets in high energy hadronic collisions
We discuss the inclusive cross section to produce two minijets with a large
separation in rapidity in high energy hadronic collisions. The contribution to
the inclusive cross section from the exchange of a BFKL Pomeron is compared
with the contribution from the exchange of two BFKL Pomerons, which is induced
by the unitarization of the semi-hard interaction. The effect of the multiple
exchange is studied both as a function of the azimuthal correlation and as a
function of the transverse momentum of the observed minijets.Comment: TeX file, 20 pages, 4 figures available on reques
Calculations of the Exclusive Processes 2H(e,e'p)n, 3He(e,e'p)2H and 3He(e,e'p)(pn) within a Generalized Glauber Approach
The exclusive processes 2H(e,e'p)n, 3He(e,e'p)2H and 3He(e,e'p)(pn), have
been analyzed using realistic few-body wave functions and treating the final
state interaction (FSI) within a Generalized Eikonal Approximation (GEA), based
upon the direct calculation of the Feynman diagrams describing the rescattering
of the struck nucleon with the nucleons of the A-1 system. The approach
represents an improvement of the conventional Glauber approach (GA), in that it
allows one to take into account the effects of the nuclear excitation of the
system on the rescattering of the struck nucleon. Using realistic
three-body wave functions corresponding to the AV18 interaction, the results of
our parameter free calculations are compared with available experimental data.
It is found that in some kinematical conditions FSI effects represent small
corrections, whereas in other kinematics conditions they are very large and
absolutely necessary to provide a satisfactory agreement between theoretical
calculations and experimental data. It is shown that in the kinematics of the
experimental data which have been considered, covering the region of missing
momentum and energy with p_m < 0.6 GeV/c and E_m < 100 MeV in the perpendicular
kinematics, the GA and GEA predictions differ only by less than 3-4 %.Comment: Typos detected and removed while Proof reading. Physical Review C. in
Pres
Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters in the Neutral Kaon System
We present a series of measurements based on K -> pi+pi- and K -> pi0pi0
decays collected in 1996-1997 by the KTeV experiment (E832) at Fermilab. We
compare these four K -> pipi decay rates to measure the direct CP violation
parameter Re(e'/e) = (20.7 +- 2.8) x 10^-4. We also test CPT symmetry by
measuring the relative phase between the CP violating and CP conserving decay
amplitudes for K->pi+pi- (phi+-) and for K -> pi0pi0 (phi00). We find the
difference between the relative phases to be Delta-phi = phi00 - phi+- = (+0.39
+- 0.50) degrees and the deviation of phi+- from the superweak phase to be
phi+- - phi_SW =(+0.61 +- 1.19) degrees; both results are consistent with CPT
symmetry. In addition, we present new measurements of the KL-KS mass difference
and KS lifetime: Delta-m = (5261 +- 15) x 10^6 hbar/s and tauS = (89.65 +-
0.07) x 10^-12 s.Comment: Submitted to Phys. Rev. D, August 6, 2002; 37 pages, 32 figure
Production of Secondaries in High Energy d+Au Collisions
In the framework of Quark-Gluon String Model we calculate the inclusive
spectra of secondaries produced in d+Au collisions at intermediate (CERN SPS)
and at much higher (RHIC) energies. The results of numerical calculations at
intermediate energies are in reasonable agreement with the data. At RHIC
energies numerically large inelastic screening corrections (percolation
effects) should be accounted for in calculations. We extract these effects from
the existing RHIC experimental data on minimum bias and central d+Au
collisions. The predictions for p+Au interactions at LHC energy are also given.Comment: 18 pages and 10 figure
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