fragmentation function

Different scattering processes have been yet studied in the noncommutative standard model (SM) and different limits on the noncommutative scale have been determined. In the present work we, for the first time, study the hadron production process through pair annihilation, in the noncommutative standard model. In the experimental studies of hadron production through pair annihilation a wide range of collision energy spectrum () has been considered. In our study, we restrict ourselves to the ranges  so having available experimental data from Belle Collaboration for B-meson production in the process  we shall determine a lower limit  for the noncommutative scale. In fact, by studying the effect of noncommutativity on the differential cross section at the parton level () as well as the fragmentation function of meson and comparing the theoretical results and experimental data the lower limit will be determined. Having analytical results for the pair annihilation cross section in the noncommutative SM it would be possible to specify the production cross section of each meson or baryon for various values of noncommutative scale.

In this work, we determine the non-perturbative fragmentation function (FF) of B-mesons (meson including a bottom quark flavor), phenomenologically, at next-to-leading order QCD perturbation theory using data from electron-positron annihilation. In this regard, we apply all current experimental data from OPAL, ALEPH, SLD2002 and DELPHI collaborations. We also apply the Hessian method to calculate the error in determination of FFs. As an application, using our extracted results we shall make our predictions for energy distribution of B-mesons produced through top quark decay. Study of the B-meson energy spectrum can be considered as a convenient channel to search for the properties of top quarks at CERN.

Study of B meson (meson with the bottom quark flavor) in Large Hadron Collider (LHC) is of special importance so that the detector LHCb is devoted to investigate these types of mesons. For this reason, in this paper we will study the production process of this meson in a phenomenological approach using the experimental data from electron-positron annihilation. In this regards, we shall calculate the fragmentation function of B meson at next-to-leading order of perturbative QCD. We will impose the effect of B meson mass into the calculations for the first time. To perform our analysis, we will employ all available experimental data reported by the OPAL, ALEPH, SLD2002 and DELPHI collaborations. Our results show that the meson mass plays important roles in correction of fragmentation functions, specially, at low values of fragmentation parameter.

Studying the production or decay processes of heavy quarkonia (the bound state of heavy quark-antiquark) is a powerful tool to test our understanding of strong interaction dynamics and QCD theory. Fragmentation is the dominant production mechanism for heavy quarkonia with large transverse momentum. The fragmentation refers to the production process of a parton with high transverse momentum which subsequently decays into a heavy quarkonia. In all previous manuscript where the fragmentation functions of heavy mesons or baryons are calculated, authors have used the approximation of a Dirac delta function for the meson wave function. In the present paper by working in a perturbative QCD framework and by considering the effect of meson wave functions we calculate the fragmentation function of a gluon into a spin-triplet S-wave charmonium J/psi. To consider the real aspect of meson bound state we apply a mesonic wave function which is different of Dirac delta function and is a nonrelativistic limit of the Bethe-Salpeter equation. Finally, we present our numerical results and show that how the proposed wave function improves the previous results.

Nowadays، heavy mesons and baryons are produced and decayed at LHC in abundance. These processes are good sources to study the QCD theory، especially to study the hadron structures. Therefore، the phenomenology of heavy hadrons fragmentation function is a basic and important subject in the Particle Physics. In the present work، we replicate the calculation heavy meson fragmentation function in the quark model and we compare our results with the well known phenomenological results and we also، for the first time، incorporate the effect of hadron mass in the calculations. We show that the mass effect not only increases the fragmentation function for the special values of the scaling variable but also it creates a threshold to produce a heavy meson.