5,633 research outputs found
g_1 at low x and low Q^2 with Polarized ep Colliders
Measurements of g_1 at low x and low Q^2 are expected to provide a sensitive
probe of the transition from Regge to perturbative QCD dynamics, offering a new
testing ground for models of small x physics. We discuss the potential of
polarized ep colliders (Polarized HERA and eRHIC) to investigate this physics
--- varying Q^2 between 0.01 and 1 GeV^2 --- and to constrain the high-energy
part of the Drell-Hearn-Gerasimov sum-rule for polarized photoproduction.Comment: 18 pages, 2 figure
Transverse Momentum in Semi-Inclusive Polarized Deep Inelastic Scattering and the Spin-Flavor Structure of the Proton
The non-valence spin-flavor structure of the nucleon extracted from
semi-inclusive measurements of polarized deep inelastic scattering depends
strongly on the transverse momentum of the detected hadrons which are used to
determine the individual polarized sea distributions. This physics may explain
the recent HERMES observation of a positively polarized strange sea through
semi-inclusive scattering, in contrast to the negative strange sea polarization
deduced from inclusive polarized deep inelastic scattering.Comment: 4 pages, revtex style, 2 figure
Electron and Phonon Thermal Waves in Semiconductors: an Application to Photothermal Effects
The electron and phonon temperature distribution function are calculated in
semiconductors. We solved the coupled one-dimensional heat-diffussion equations
in the linear approximation in which the physical parameters on the sample are
independent of the temperature. We also consider the heat flux at the surface
of the semiconductor as a boundary condition for each electron and phonon
systems instead of using a fixed temperature. From this, we obtain an
expression for electron and phonon temperature respectively. The
characterization of the thermal waves properties is duscussed and some
practical procedures for this purpose provide us information about the electron
and phonon thermal parameters.Comment: 12 pages, amstex and amssymb macro package (LaTeX2e edition
The Drell-Hearn-Gerasimov Sum-Rule at Polarized HERA
We discuss the potential of polarized HERA to measure the spin dependent part
of the total photoproduction cross-section at large .Comment: 7 pages, LaTeX, 1 figure generated as fig1.tex. To appear in Proc.
Workshop on ``Physics with Polarized Protons at HERA'
The nucleon's octet axial-charge g_A^8 with chiral corrections
The value of the nucleon's flavour-singlet axial-charge extracted from
polarised deep inelastic scattering is sensitive to the value of the octet
axial-charge g_A^8 which is usually taken from an analysis of hyperon
beta-decays within the framework of SU(3) symmetry, namely 0.58 \pm 0.03. Using
the Cloudy Bag model we find that the value of g_A^8 is reduced by as much as
20% below the usual phenomenological value. This increases the value of the
flavour singlet axial charge (g_A^0|_inv) derived from deep inelastic data and
significantly reduces the difference between it and g_A^8.Comment: 12 page
Future physics with polarized ep-colliders
We discuss some of the physics opportunities at polarized ep-colliders.
Recent studies for polarized ep-colliders include HERA, EIC and THERA.Comment: 7 pages, 6 figures, Invited talk presented at the ``International
Workshop on the Spin Structure of the Proton and Polarized Collider
Physics'', ECT, Trento, Italy, July 23-28, 200
The Spin Structure of the Proton and Polarized Collider Physics
We summarise the present status of the proton spin problem and the physics
possibilities for future polarized ep and pp colliders. This summary is based
on the presentations and discussion sessions at the workshop ``The Spin
Structure of the Proton and Polarized Collider Physics'' (Trento, July 23-28,
2001).Comment: 27 pages, 22 figure
New Mechanism of Magnetoresistance in Bulk Semiconductors: Boundary Condition Effects
We consider the electronic transport in bounded semiconductors in the
presence of an external magnetic field. Taking into account appropriate
boundary conditions for the current density at the contacts, a change in the
magnetoresistance of bulk semiconductors is found as compared with the usual
theory of galvanomagnetic effects in boundless media. New mechanism in
magnetoresistance connected with the boundary conditions arises. In particular,
even when the relaxation time is independent of the electron energy,
magnetoresistance is not vanish.Comment: 7 pages, Elsart macro package (LaTeX2e edition
Spin structure function g_1 at low x: status and plans
A brief review of measurements and expectations concerning the spin structure
function g_1 of the nucleon at low values of the scaling variable x is given.Comment: 4 pages, 3 figures. Invited talk presented at the ``International
Workshop on the Spin Structure of the Proton and Polarized Collider
Physics'', ECT*, Trento, Italy, July 23-28, 200
Transverse Velocity Dependence of the Proton-Antiproton Ratio as a Signature of the QCD Critical Endpoint
The presence of a critical point in the QCD phase diagram can deform the
trajectories describing the evolution of the expanding fireball in the
phase diagram. If the average emission time of hadrons is a function
of transverse velocity, as microscopic simulations of the hadronic freeze-out
dynamics suggest, the deformation of the hydrodynamic trajectories will change
the transverse velocity () dependence of the proton-antiproton
ratio when the fireball passes in the vicinity of the critical point. An
unusual -dependence of the ratio in a narrow beam
energy window would thus signal the presence of the critical point.Comment: Final version accepted for publicatio
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