16 research outputs found
HERA results on the structure of the proton
A selection of results from the H1 and ZEUS experiments at HERA are reviewed, particularly in the area of deep inelastic scattering and diffraction. Quantum chromodynamics gives a good explanation of these data down to surprisingly low values of the four-momentum transfer, . Data at smaller can be described by Regge models as well as by dipole models including parton-saturation effects. The latter can also give a unified description of many features of diffractive data
Soft Photoproduction Physics
Several topics of interest in soft photoproduction physics are discussed.
These include jet universality issues (particle flavour composition), the
subdivision into event classes, the buildup of the total photoproduction cross
section and the effects of multiple interactions.Comment: 10 pages, LaTeX2e, no figures, to appear in the proceedings of the
Durham Workshop on HERA Physics, ``Proton, Photon and Pomeron Structure'',
17--23 September 1995, Durham, U.
Regge behaviour of distribution functions and t and x-evolutions of gluon distribution function at low-x
In this paper t and x-evolutions of gluon distribution function from
Dokshitzer-Gribov-Lipatov-Altarelli-Parisi(DGLAP) evolution equation in leading
order(LO) at low-x, assuming the Regge behaviour of quark and gluon at this
limit, are presented. We compare our results of gluon distribution function
with MRST 2001, MRST 2004 and GRV '98 parameterizations and show the
compatibility of Regge behaviour of quark and gluon distribution functions with
perturbative quantum chromodynamics(PQCD) at low-x. We also discuss the
limitations of Taylor series expansion method used earlier to solve DGLAP
evolution equations, in the Regge behaviour of distribution functions.Comment: 19 pages, 7 figure
Study of the Linked Dipole Chain Model in heavy quark production at the Tevatron
We present calculations of charm and beauty production at Tevatron within the
framework of kT-factorization, using the unintegrated gluon distributions as
obtained from the Linked Dipole Chain model. The analysis covers transverse
momentum and rapidity distributions and the azimuthal correlations between b
and bbar quarks (or rather muons from their decay) which are powerful tests for
the different unintegrated gluon distributions. We compare the theoretical
results with recent experimental data taken by D0 and CDF collaborations at the
Tevatron Run I and II.Comment: 16 page
Complete O(alpha_s^2) Corrections to (2+1) Jet Cross Sections in Deep Inelastic Scattering
Complete next-to leading order QCD predictions for (2+1) jet cross sections
and jet rates in deep inelastic scattering (DIS) based on a new parton level
Monte Carlo program are presented. All relevant helicity contributions to the
total cross section are included. Results on total jet cross sections as well
as differential distributions in the basic kinematical variables and
are shown for HERA energies and for the fixed target experiment E665 at
FERMILAB. We study the dependence on the choices of the renormalization scale
and the factorization scale and show that the NLO results are
much less sensitive to the variation of than the LO results.
The effect of an additional cut to our jet definition scheme is
investigated.Comment: 14 pages, LateX, MAD/PH/821, 15 figures (not included), figures are
available upon request. (some essential changes to the figures, minor changes
to the text). To appear in Z.Phys.
Unbiased determination of the proton structure function F_2^p with faithful uncertainty estimation
We construct a parametrization of the deep-inelastic structure function of the proton F_2 based on all available experimental information from charged lepton deep-inelastic scattering experiments. The parametrization effectively provides a bias-free determination of the probability measure in the space of structure functions, which retains information on experimental errors and correlations. The result is obtained in the form of a Monte Carlo sample of neural networks trained on an ensemble of replicas of the experimental data. We discuss in detail the techniques required for the construction of bias-free parameterizations of large amounts of structure function data, in view of future applications to the determination of parton distributions based on the same method.We construct a parametrization of the deep-inelastic structure function of the proton F_2 based on all available experimental information from charged lepton deep-inelastic scattering experiments. The parametrization effectively provides a bias-free determination of the probability measure in the space of structure functions, which retains information on experimental errors and correlations. The result is obtained in the form of a Monte Carlo sample of neural networks trained on an ensemble of replicas of the experimental data. We discuss in detail the techniques required for the construction of bias-free parameterizations of large amounts of structure function data, in view of future applications to the determination of parton distributions based on the same method
Working Group Report on the Structure of the Proton
We summarize the developments on the structure of the proton that were
studied at the Workshop on "HERA Physics" that was held in Durham in September
1995. We survey the latest structure function data; we overview the QCD
interpretations of the measurements of the structure functions and of final
state processes; we discuss charm production and the spin properties of the
proton.Comment: 45 pages, latex file using epsfig and ioplppt macros. Figures
included, but full resolution figure files and postscript file of the whole
paper are available via anonymous ftp at
ftp://cpt1.dur.ac.uk/pub/preprints/dtp96/dtp962
Recommended from our members
Proton and deuteron structure functions in muon scattering at 470 GeV
The proton and deuteron structure functions F{sub 2}{sup p} and F{sub 2}{sup d} measured in inelastic muon scattering with an average beam energy of 470 GeV. The data were taken at Fermilab experiment 665 during 1991-1992 using liquid hydrogen and deuterium targets. The F{sub 2} measurements are reported in the range 0.0008 < x < 0.6 and 0.2 < Q{sup 2} < 75 GeV{sup 2}. These are the first precise measurements of F{sub 2} in the low x and Q{sub 2} range of the data. The E665 data overlap in x with the HERA data, and there is a smooth connection in Q{sup 2} between the two data sets. At high Q{sup 2} the E665 measurements are consistent with QCD-evolved leading twist structure function models. The data are qualitatively described by structure function models incorporating the hadronic nature of the photon at low Q{sup 2}. The Q{sup 2} and the W dependence of the data measure the transition in the nature of the photon between a point-probe at high Q{sup 2} and a hadronic object at low Q{sup 2}
Shadowing in inelastic scattering of muons on carbon, calcium and lead at low x_B_j
Nuclear shadowing is observed in the per-nucleon cross-sections of positive muons on carbon, calcium and lead as compared to deuterium. The data were taken by Fermilab experiment E 665 using inelastically scattered muons of mean incident momentum 470 GeV/c. Cross-section ratios are presented in the kinematic region 0.0001 < x_B_j < 0.56 and 0.1 < Q"2 < 80 GeV"2. The data are consistent with no significant #nu# or Q"2 dependence at fixed x_B_j. As x_B_j decreases, the size of the shadowing effect, as well as its A dependence, are found to approach the corresponding measurements in photoproduction. (orig.)SIGLEAvailable from TIB Hannover: RR 2916(95-11) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
Density and correlation integrals in deep-inelastic muon-nucleon scattering at 490 GeV
Results on density integrals F_q(Q[2) and correlation integrals K_q(Q"2) are presented for the first time in muon-nucleon scattering at #approx# 490 GeV, using data from the E665 experiment at the Tevatron of Fermilab. A clear rise of the F_q integrals with decreasing size of the phase-space cells ('intermittency') is observed for pairs and triplets of negative hadrons whereas the effect is much weaker for mixed charge combinations. From these findings it is concluded that the observed intermittency signal is mainly caused by Bose-Einstein interference. Furthermore, no energy (W) dependence of F_2(Q"2) is observed within the W range of the E665 experiment. Finally, the third-order correlation integrals K_3(Q"2) are found to be significantly different from zero which implies the presence of genuine three-particle correlations in muon-nucleon interactions. (orig.)Available from TIB Hannover: RR 2916(94-12) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman