1,194 research outputs found
Phenomenology of the Flavor-Asymmetry in the Light-Quark Sea of the Nucleon
A phenomenological ansatz for the flavor-asymmetry of the light sea
distributions of the nucleon, based on the Pauli exclusion principle, is
proposed. This ansatz is compatible with the measured flavor-asymmetry of the
unpolarized sea distributions, , of the nucleon. A prediction
for the corresponding polarized flavor-asymmetry is presented and shown to
agree with predictions of (chiral quark--soliton) models which successfully
reproduced the flavor-asymmetry of the unpolarized sea.Comment: 5 pages, LaTeX, 2 figures, uses epsfi
The Photon Structure Function at Small-x
It is shown that recent small-x measurements of the photon structure function
F_2^{\gamma}(x,Q^2) by the LEP-OPAL collaboration are consistent with
parameter-free QCD predictions at all presently accessible values of Q^2.Comment: 7 pages, LaTeX, 2 figure
Extraction of Polarized Gluon Distributions from Large-pt Light Hadron Pair Production
We propose a new formula for extracting the polarized gluon distribution from
the large- light hadron pair production for semi-inclusive processes in
polarized deep inelastic scattering. In general, a large- hadron pair is
produced via photon-gluon fusion(PGF) and QCD Compton at the lowest order of
QCD. The PGF gives us a direct information on in the nucleon, while
QCD Compton becomes background to the signal process for extracting .
We show that the contribution from this background, i.e. the QCD Compton
process, can be removed by using symmetry relation among fragmentation
functions and taking an appropriate combination of various light hadron pair
production processes, and thus the double spin asymmetry can be described in
terms of alone.Comment: 14 pages 3 EPS figures Late
Has the QCD RG-Improved Parton Content of Virtual Photons been Observed?
It is demonstrated that present and DIS ep data on the structure of
the virtual photon can be understood entirely in terms of the standard `naive'
quark--parton model box approach. Thus the QCD renormalization group (RG)
improved parton distributions of virtual photons, in particular their gluonic
component, have not yet been observed. The appropriate kinematical regions for
their future observation are pointed out as well as suitable measurements which
may demonstrate their relevance.Comment: 24 pages, LaTeX, 5 figure
New proton polarized structure functions in charged current processes at HERA
Estimates for longitudinal spin asymmetries which single out new polarized
nucleon structure functions in deeply inelastic charged current interactions at
HERA energies are given, exploiting their interpretation in terms of polarized
quark distributions. These asymmetries turn out to be large and allow a
measurement of the new polarized structure functions and ,
which would add valuable tests and information on the spin content of quarks
inside a polarized proton. We also show that single spin asymmetries in neutral
current interactions are very small.Comment: LaTeX, 8 pages, 6 figure
On dynamically generated parton distribution functions and their properties
The idea of ``dynamically'' generated parton distribution functions, based on
regular initial conditions at low momentum scale, is reanalyzed with particular
emphasize paid to its compatibility with the factorization mechanism. Basic
consequences of this approach are discussed and compared to those of the
conventional approach, employing singular initial distribution functions.Comment: 15 pages, Latex, 5 figures in PS format attache
Heavy Quark Initiated Contributions to Deep Inelastic Structure Functions
We present O(alpha_s^1) corrections to deep inelastic scattering amplitudes
on massive quarks obtained within the scheme of Aivazis, Collins, Olness and
Tung (ACOT). After identifying the correct subtraction term the convergence of
these contributions towards the analogous coefficient functions for massless
quarks, obtained within the modified minimal subtraction scheme (MSbar), is
demonstrated. Furthermore, the quantitative relevance of the contributions to
neutral current (NC) and charged current (CC) structure functions is
investigated for several choices of the factorization scale.Comment: 29 pages, 6 figures; uses epsfig.sty, amssymb.sty, axodraw.sty; minor
changes for publication in Phys. Rev.
Appearance of quark-hadron duality in the Rein-Sehgal model
Quark-hadron duality in neutrino-nucleon reactions is investigated under the
assumption that cross sections in the resonance region are given by the
Rein-Sehgal model. The quantitative analysis of the duality is done by means of
appropriate integrals of the structure functions in the Nachtmann variable. We
conclude that with the definition of the resonance region
GeV) the duality holds for neutrino-proton reaction structure function
for GeV and it is absent for neutrino-neutron reaction.Comment: 4 pages, 7 figures, presented at NuInt05 conference, Okayama, Sept.
26-29, 200
Spin Asymmetries in Squark and Gluino Production at Polarized Hadron Colliders
We study the production cross sections for squarks and gluinos in collision
of longitudinally polarized hadrons. The corresponding polarized partonic cross
sections are computed in leading order supersymmetric QCD. The resulting
asymmetries are evaluated for the polarized proton collider RHIC, as well as
for hypothetical polarized options of the Tevatron and the LHC. These
asymmetries turn out to be sizable over a wide range of supersymmetric particle
masses, thus potentially opening a window to detailed sparticle spectroscopy at
future polarized hadron colliders.Comment: 25 pages, LaTeX, typos correcte
Semi-inclusive Lambda_c^+ Leptoproductions and Polarized Gluon Distributions
In order to extract the behavior and magnitude of the spin-dependent gluon
distribution, we propose a semi-inclusive production using
unpolarized lepton beams and polarized proton targets. The correlation between
the target proton spin and the spin of produced in the target
fragmentation region might be very effective for testing various models of
polarized gluons.Comment: 9 pages + 4 Postscript figures(2 PS files), LaTe
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