Confronting fragmentation function universality with single hadron inclusive production at HERA ande+e−colliders

Abstract

Predictions for light charged hadron production data in the current fragmentation region of deeply inelastic scattering from the H1 and ZEUS experiments are calculated using perturbative Quantum Chromodynamics at next-to-leading order, and using fragmentation functions obtained by fitting to similar data from e + e − reactions. General good agreement is found when the magnitude Q 2 of the hard photon's virtuality is sufficiently large. The discrepancy at low Q and small scaled momentum x p is reduced by incorporating mass effects of the detected hadron. By performing quark tagging, the contributions to the overall fragmentation from the various quark flavours in the ep reactions are studied and compared to the contributions in e + e − reactions. The yields of the various hadron species are also calculated.

Hadron mass corrections in semi-inclusive deep-inelastic scattering

“…A full utilization of the new data will require that effects associated with kinematical constraints at finite energy are properly taken into account. Following earlier work which studied the dependence of unpolarized SIDIS cross sections on the masses of hadrons in the initial and final states [46][47][48], in this work we have presented a comprehensive analysis of hadron mass corrections to both spin-averaged and spin-dependent cross sections and asymmetries at finite values of Q 2 . Using the framework of collinear factorization, we have derived formulas for SIDIS cross sections in the presence of HMCs, which at leading order in α s result in a rescaling of the PDFs in terms of the modified Nachtmann variable ξ h and of the fragmentation functions in terms of the finite-Q 2 fragmentation variable ζ h .…”

Light Mesons and Strange Particle Production at HERA

“…The scaled momentum distributions were compared with next-to-leading order (NLO) QCD calculations and the leading-log parton-shower MC ARIADNE and LEPTO. Various fragmentation functions (FFs) obtained from fits to e + e − data [10,11], to e + e − and pp/pp data [12], or to e + e − , p/pp and ep data [13] were used in the NLO QCD calculations. Figure 4 shows the scaled momentum distributions, x p = 2P Breit /Q, as a function of Q 2 in different regions of x p for K 0 S and Λ particles.…”

Hadron multiplicities at the HERMES experiment

“…According to the factorization theorem [1] the cross section of a hadron production in semi-inclusive deep inelastic leptonnucleon scattering (SIDIS) process is described by parton distribution functions and fragmentation functions. On the other hand the universality for the fragmentation functions [2] gives a good chance to compare those with fragmentation functions extracted from different kind of precesses and consider them as a global input for the further studies. Understanding the hadronization process is an essential element of a complete picture of the interaction of quarks in Quantum ChromoDynamics (QCD), and is basic for the understanding of the dynamics of quark-quark, gluon-gluon, and quark-gluon interactions.…”