Abstract:We present new sets of fragmentation functions for charged pions and kaons, both at leading and next-to-leading order. They are fitted to data on inclusive charged-hadron production in e+eannihilation taken by the TPC Collaboration at SLAC PEP (fi = 29 GeV) and to similar data by ALEPH at CERN LEP, who discriminated between events with charm, bottom, and light-flavor fragmentation in their charged-hadron sample. In contrast with our previous analysis, where we only distinguished between valence-quark, sea-quar… Show more
“…The k tfactorization is much better but still some contribution is missing at large Feynman x F and at small transverse momenta. However, one should remember that other processes such as In Fig.4 we show our full result (diagrams A, B 1 and B 2 [13]) for different fragmentation functions [23,24,26]. In this calculation b 0 = 0.5 GeV −1 was used.…”
Section: From Partons To Hadronsmentioning
confidence: 99%
“…In the present application different fragmentation functions from the literature [23,24,26] will be used. All of them were obtained in global fits to the e + e − data.…”
We compare results of 2 → 1 k t -factorization approach with Kwieciński unintegrated parton distributions and the standard collinear factorization approach at RHIC and slightly smaller energies. Our approach contains only one free parameter responsible for internal parton motion in nucleons. In contrast to recent works in the literature our k t -factorization approach includes also quark degrees of freedom in addition to purely gluonic terms. Both mid and forward rapidity regions are considered. We discuss uncertainties due to fragmentation functions. In general, the k t -factorization approach gives a better description of the p t ∼ 1 -4 GeV region both at mid and forward rapidity regions. Our approach leads to asymmetry in the production of π + and π − , very similar to the one observed very recently by the BRAHMS collaboration.
“…The k tfactorization is much better but still some contribution is missing at large Feynman x F and at small transverse momenta. However, one should remember that other processes such as In Fig.4 we show our full result (diagrams A, B 1 and B 2 [13]) for different fragmentation functions [23,24,26]. In this calculation b 0 = 0.5 GeV −1 was used.…”
Section: From Partons To Hadronsmentioning
confidence: 99%
“…In the present application different fragmentation functions from the literature [23,24,26] will be used. All of them were obtained in global fits to the e + e − data.…”
We compare results of 2 → 1 k t -factorization approach with Kwieciński unintegrated parton distributions and the standard collinear factorization approach at RHIC and slightly smaller energies. Our approach contains only one free parameter responsible for internal parton motion in nucleons. In contrast to recent works in the literature our k t -factorization approach includes also quark degrees of freedom in addition to purely gluonic terms. Both mid and forward rapidity regions are considered. We discuss uncertainties due to fragmentation functions. In general, the k t -factorization approach gives a better description of the p t ∼ 1 -4 GeV region both at mid and forward rapidity regions. Our approach leads to asymmetry in the production of π + and π − , very similar to the one observed very recently by the BRAHMS collaboration.
“…and its inversion ∆k out 44) with U out uniform between 0 and 1. Note that the internal real radiative corrections are simulated in the event generation, but not in the full GEANT simulation of the detector.…”
Section: Internal Real Radiation Correctionsmentioning
confidence: 99%
“…Fragmentation functions are generally extracted from e + e − annihilation. Their parameterization frequently takes the form [43,44] 51) and they are normalized by 52) with N h the average multiplicity of the hadron h in inclusive process or in e + e − annihilation process.…”
Section: General Description Of Semi-inclusive Deep Inelastic Scattermentioning
“…For the proton's FF at present accelerator energies we use ref. [26]. We evolve the FFs in ordinary and in supersymmetric QCD to the energies of the SPs.…”
Abstract. We determine the probability that an ultrahigh energy (above 5 · 10 19 eV) proton created at a distance r with energy E arrives at earth above a threshold Ec. The clustering of ultrahigh energy cosmic rays suggests that they might be emitted by compact sources. We present a statistical analysis on the source density based on the multiplicities. The ultrahigh energy cosmic ray spectrum is consistent with the decay of GUT scale particles. By using a maximum likelihood analysis we determine the mass of these GUT scale particles. We consider the possibility that a large fraction of the ultrahigh energy cosmic rays are decay products of Z bosons which were produced in the scattering of ultrahigh energy cosmic neutrinos on cosmological relic neutrinos. Based on this scenario we determine the required mass of the heaviest relic neutrino as well as the necessary ultrahigh energy cosmic neutrino flux via a maximum likelihood analysis.
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