Recent results from HERMES in the hadron leptoproduction of nuclei are presented. The possible interpretations in terms of medium modifications of the parton fragmentation function and the implications on the parton e...
详细信息
Recent results from HERMES in the hadron leptoproduction of nuclei are presented. The possible interpretations in terms of medium modifications of the parton fragmentation function and the implications on the parton energy loss are discussed.
The difference between the structures of jets produced in heavy-ion and hadronic collisions can best be exhibited in the correlations between particles within those jets. We study the dihadron correlations in jets in ...
详细信息
The difference between the structures of jets produced in heavy-ion and hadronic collisions can best be exhibited in the correlations between particles within those jets. We study the dihadron correlations in jets in the framework of parton recombination. Two types of triggers, π+ and proton, are considered. It is shown that the recombination of thermal and shower partons makes the most important contribution to the spectra of the associated particles at intermediate pT. In pp collisions the only significant contribution arises from shower-shower recombination, which is negligible in heavy-ion collisions. Moments of the associated-particle distributions are calculated to provide a simple summary of the jet structures for easy comparison with experiments.
The hadron/pion ratio is calculated in 200 GeV AuAu collisions at midrapidity, applying pQCD and non-universal transverse-momentum broadening. Arguments are presented for such non-universality. and the idea is impleme...
详细信息
The hadron/pion ratio is calculated in 200 GeV AuAu collisions at midrapidity, applying pQCD and non-universal transverse-momentum broadening. Arguments are presented for such non-universality. and the idea is implemented in a model, which reproduces the main features of the, centrality dependence of the hadron/pion ratio in AuAu collisions. The model also reasonably describes the qualitative difference between the recently measured dAu nuclear enhancement factors for pions and charged hadrons.
We solve numerically the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations for the evolution of fragmentation functions using the Laguerre method. We extend this method to include supersymmetric evolution. ...
详细信息
We solve numerically the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations for the evolution of fragmentation functions using the Laguerre method. We extend this method to include supersymmetric evolution. The solution to the DGLAP equations is particularly interesting to calculate the expected spectra of Ultra High Energy Cosmic Rays in models where they are produced by the decay of a massive particle X, M-X > 10(12) GeV. (C) 2002 Elsevier Science B.V. All rights reserved.
We investigate the power-suppressed corrections to fragmentation functions in flavour-singlet deep-inelastic lepton scattering, to complement the previous results for the non-singlet contribution. Our method is a disp...
详细信息
We investigate the power-suppressed corrections to fragmentation functions in flavour-singlet deep-inelastic lepton scattering, to complement the previous results for the non-singlet contribution. Our method is a dispersive approach based on an analysis of Feynman graphs containing massive gluons. As in non-singlet deep-inelastic scattering we find that the leading corrections are proportional to 1/Q(2). (C) 1999 Elsevier Science B.V. All rights reserved.
This is the report of the QCD working group at WHEPP-6. Discussions and work on heavy ion collisions, polarized scattering, and collider phenomenology are reported.
This is the report of the QCD working group at WHEPP-6. Discussions and work on heavy ion collisions, polarized scattering, and collider phenomenology are reported.
We present the calculation of the order alpha(s)(2) corrections to the coefficient functions contributing to the longitudinal (F-L(x,Q(2))) and traverse fragmentation functions (F-T(x,Q(2))) measured in electron-posit...
详细信息
We present the calculation of the order alpha(s)(2) corrections to the coefficient functions contributing to the longitudinal (F-L(x,Q(2))) and traverse fragmentation functions (F-T(x,Q(2))) measured in electron-position annihilation. The effect of these higher order QCD corrections on the behaviour of the fragmentation functions and the corresponding longitudinal (d sigma(L)(x,Q(2))/dx) and transverse cross sections (d sigma(T)(x,Q(2))/dx) are studied. In particular we investigate the dependence of the above quantities on the mass factorization scale (M) and the various parameterizations chosen for the parton fragmentation densities D-p(H)(x,M(2)) (p = q,g;H = pi(+/-),K-+/-,P,(P) over bar). Our analysis reveals that the order alpha(s)(2) contributions to F-L(x,Q(2)) are large whereas these contributions to F-T(x,Q(2)) are small. From the above fragmentation functions one can also compute the integrated cross sections sigma(L) and sigma(T) in an independent way. The sum sigma(tot) = sigma(L) + sigma(T), corrected up to order alpha(s)(2), agrees with the well-known result in the literature providing us with an independent check on our calculations.
We present the calculation of the order alpha(s)(2) contributions to the coefficient functions (singlet and non-singlet) belonging to the longitudinal spin fragmentation function g(1)(x, Q(2)) measured in polarized el...
详细信息
We present the calculation of the order alpha(s)(2) contributions to the coefficient functions (singlet and non-singlet) belonging to the longitudinal spin fragmentation function g(1)(x, Q(2)) measured in polarized electron-positron annihilation. From this calculation we also obtain the two-loop contribution to the time-like spin splitting functions P-qq(S) and P-gq. These splitting functions are in agreement with recent results in the literature obtained using a different method. We show that in second order the renormalization constant needed for the HVBM prescription of the gamma(5)-matrix is process dependent. (C) 1998 Elsevier Science B.V.
We present the results of the tree-level calculation of inclusive two-hadron production in electron-positron annihilation via one photon up to subleading order in 1/Q. We consider the situation where the two hadrons b...
详细信息
We present the results of the tree-level calculation of inclusive two-hadron production in electron-positron annihilation via one photon up to subleading order in 1/Q. We consider the situation where the two hadrons belong to different, back-to-back jets. We include polarization of the produced hadrons and discuss azimuthal dependences of asymmetries. New asymmetries are found, in particular there is a leading cos(2 phi) asymmetry, which is even present when hadron polarization is absent, since it arises solely due to the intrinsic transverse momenta of the quarks. (C) 1997 Published by Elsevier Science B.V. PACS: 13.65.+i;13.88.+e.
暂无评论