958 research outputs found
Strange quark suppression from a simultaneous Monte Carlo analysis of parton distributions and fragmentation functions
We perform the first simultaneous extraction of unpolarized parton
distributions and fragmentation functions from a Monte Carlo analysis of
inclusive and semi-inclusive deep-inelastic scattering, Drell-Yan lepton-pair
production, and single-inclusive annihilation data. We use data
resampling techniques to thoroughly explore the Bayesian posterior distribution
of the extracted functions, and use -means clustering on the parameter
samples to identify the configurations that give the best description across
all reactions. Inclusion of the semi-inclusive data reveals a strong
suppression of the strange quark distribution at parton momentum fractions , in contrast with the ATLAS observation of enhanced strangeness
in and production at the LHC. Our study reveals significant
correlations between the strange quark density and the strange kaon
fragmentation function needed to simultaneously describe semi-inclusive
production data from COMPASS and inclusive spectra in
annihilation from ALEPH and SLD, as well as between the strange and light
antiquark densities in the proton.Comment: 6 pages, 4 figures; version to appear in Phys. Rev.
Deep-inelastic and quasielastic electron scattering from nuclei
We perform a combined analysis of inclusive electron scattering data from
nuclei in the deep-inelastic and quasielastic scattering regions, using
Monte Carlo analysis methods and the nuclear weak binding approximation to
establish the range over which the data can be described within the same
theoretical framework. Comparison with quasielastic He cross sections from
SLAC and Jefferson Lab suggests that most features of the data
can be reasonably well described in the impulse approximation with finite-
nuclear smearing functions for momentum transfers GeV. For
the DIS region, we analyze the recent He to deuterium cross section ratio
from the Jefferson Lab E03-103 experiment to explore the possible isospin
dependence of the nuclear effects. We discuss the implications of this for the
MARATHON experiment at Jefferson Lab, and outline how a Bayesian analysis of
He, H and deuterium data can robustly determine the free neutron
structure function.Comment: 45 pages, 14 figure
Hadron mass corrections in semi-inclusive deep-inelastic scattering
The spin-dependent cross sections for semi-inclusive lepton-nucleon
scattering are derived in the framework of collinear factorization, including
the effects of masses of the target and produced hadron at finite momentum
transfer squared Q^2. At leading order the cross sections factorize into
products of parton distribution and fragmentation functions evaluated in terms
of new, mass-dependent scaling variables. The size of the hadron mass
corrections is estimated at kinematics relevant for future semi-inclusive
deep-inelastic scattering experiments.Comment: 28 pages, 12 figures, published versio
Self-Averaging Scaling Limits of Two-Frequency Wigner Distribution for Random Paraxial Waves
Two-frequency Wigner distribution is introduced to capture the asymptotic
behavior of the space-frequency correlation of paraxial waves in the radiative
transfer limits. The scaling limits give rises to deterministic transport-like
equations. Depending on the ratio of the wavelength to the correlation length
the limiting equation is either a Boltzmann-like integral equation or a
Fokker-Planck-like differential equation in the phase space. The solutions to
these equations have a probabilistic representation which can be simulated by
Monte Carlo method. When the medium fluctuates more rapidly in the longitudinal
direction, the corresponding Fokker-Planck-like equation can be solved exactly.Comment: typos correcte
First Monte Carlo analysis of fragmentation functions from single-inclusive e(+)e(-) annihilation
We perform the first iterative Monte Carlo (IMC) analysis of fragmentation functions constrained by all available data from single-inclusive e(+)e(-) annihilation into pions and kaons. The IMC method eliminates potential bias in traditional analyses based on single fits introduced by fixing parameters not well constrained by the data and provides a statistically rigorous determination of uncertainties. Our analysis reveals specific features of fragmentation functions using the new IMC methodology and those obtained from previous analyses, especially for light quarks and for strange quark fragmentation to kaons
- …