Abstract
Inclusive hadron production cross section in e+e- annihilation shed light on fundamental questions of hadronization and fragmentation processes. We present measurements of inclusive spectra of charged pions, kaons, and protons (antiprotons) produced in e+e- collisions at the center-of-mass energy of 10.54 GeV, and tests of QCD predictions and hadronization models. We also report the results on the measurement of the azimuthal modulation induced by the Collins effect in inclusive production of charged pion pairs e+e- → ππX, where the two pions are produced in opposite hemispheres. These data allows the determination of the polarized Collins fragmentation functions.
Highlights
Fragmentation functions describe the probability for a parton to fragment into a hadron carrying a certain fraction of the parton’s energy
The cleanest environment to measure fragmentation functions is in e+e− annihilation experiment, since no hadrons are present in the initial state
The first measurement of the Collins effect in e+e− annihilation experiments was performed by the Belle Collaboration,[16] which studied in detail the dependence of the asymmetry as a function of the pion fractional energies z and polar angles θ
Summary
Fragmentation functions describe the probability for a parton (quarks or gluons) to fragment into a hadron carrying a certain fraction of the parton’s energy. The first measurement of the Collins effect in e+e− annihilation experiments was performed by the Belle Collaboration,[16] which studied in detail the dependence of the asymmetry as a function of the pion fractional energies z and polar angles θ. In the first part of this report we present measurements of cross sections for inclusiv√e production of charged pions, kaons, and protons (antiprotons) at the c.m. energy s = 10.54 GeV, using a relatively small sample of data from the BaBar experiment at the PEP-II B factory at the SLAC National Accelerator Laboratory. Both statistical and systematic errors are included. Note that our results are very precise and extend up to xp 1, and that all the three models does not describe any spectrum in detail
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