1,183 research outputs found
Deep inelastic scattering, diffraction, and all that
These lectures include an introduction to the partonic description of the
proton, the photon and the `colour singlet', as seen in inclusive and
semi-inclusive DIS, in collisions, and in diffractive processes,
respectively. Their formal treatment using structure, fragmentation, and
fracture functions is outlined giving an insight into the perturbative QCD
framework for these functions. Examples and comparisons with experimental data
from LEP, HERA, and Tevatron are also covered.Comment: 46 pages, 52 postscript figures, LaTeX, aipproc.sty. To be published
in the proceedings of VII Mexican Workshop on Particles and Field
Photoproduction of jets and the virtual structure of the photon
We compute the ratio between the direct and the resolved photon components of
single jet and dijet production in collisions for the kinematical range
covered by the most recent ZEUS data. We analyse the phenomenological
consequences of different models for the structure of virtual photons in these
observables and compare them with the available data. We also comment on the
correlation between the so called and the `true'
, that can be inferred from the data.Comment: epsfig, 5 figure
NLO Scale Dependence of Semi-Inclusive Processes
We discuss the order \alpha_s^2 gluon initiated QCD corrections to one
particle inclusive deep inelastic processes. We focus in the NLO evolution
kernels relevant for the non homogeneous QCD scale dependence of these cross
sections and factorization.Comment: Poster presentation at the XXIII Physics in Collision Conference
(PIC03), Zeuthen, Germany, June 2003, 3 pages, LaTeX, 4 eps figures, PSN
FRAP1
The role of heavy quarks in light hadron fragmentation
We investigate the role of heavy quarks in the production of light flavored
hadrons and in the determination of the corresponding non perturbative
hadronization probabilities. We define a general mass variable flavor number
scheme for fragmentation functions that accounts for heavy quark mass effects,
and perform a global QCD analysis to an up-to-date data set including very
precise Belle and BaBar results. We show that the mass dependent picture
provides a much more accurate and consistent description of data.Comment: 5 pages, 3 eps figure
Medium Effects in DIS from Polarized Nuclear Targets
The behavior of the nucleon structure functions in lepton nuclei deep
inelastic scattering, both polarized and unpolarized, due to nuclear structure
effects is reanalyzed. The study is performed in two schemes: an x-rescaling
approach, and one in which there is an increase of sea quark components in the
in medium nucleon, related to the low energy N-N interaction. In view of a
recent interesting experimental proposal to study the behavior of the proton
spin structure functions in nuclei we proceed to compare these approaches in an
effort to enlighten the possible phenomenological interest of such difficult
experiment.Comment: 11 pages and 5 figure
The Landau Distribution for Charged Particles Traversing Thin Films
The Landau distribution as well as its first and second momenta are well
suited for describing the energy loss of charged particles traversing a thin
layer of matter. At present, just rational approximations and asymptotic
expressions for these functions were obtained. In this paper we present a
direct calculation of the integral representation of these functions obtaining
perturbative and nonperturvative solutions expressed in terms of fast
convergent series. We also provide a simple numerical algorithm which allows to
control speed and precision of the results. The testing runs have provided, in
reasonable computing times, correct results up to 13-14 significant digits on
the density and distribution functions and 9-10 on the first and second
momenta. If necessary, this accuracy could be improved by adding more
coefficients to the algorithm.Comment: 29 pages, 4 Table
- …