The Collins fragmentation function: a simple model calculation

The Collins fragmentation function: a simple model calculation

The Collins function belongs to the class of the so-called time-reversal odd fragmentation functions. Being chiral-odd as well, it can serve as an important tool to observe the nucleon’s transversity distribution in semi-inclusive DIS. Due to the possible presence of final state interactions, this function can be non-zero, though this has never been demonstrated in an explicit model calculation...

Transversity and Collins Fragmentation Functions: Towards a New Global Analysis

A new, preliminary global analysis of the experimental data on azimuthal asymmetries in SIDIS from HERMES and COMPASS collaborations, and in ee → h1h2X processes from the BELLE collaboration, is performed. The new data allow for a more precise determination of the Collins fragmentation function and of the transversity distribution function for u and d quarks, in comparison with the results of o...

Collins Fragmentation and the Single Transverse Spin Asymmetry

Competition and fragmentation: a simple model generating lognormal-like distributions

The current distribution of language size in terms of speaker population is generally described using a lognormal distribution. Analyzing the original real data we show how the double-Pareto lognormal distribution can give an alternative fit that indicates the existence of a power law tail. A simple model, based on competition and fragmentation, reproduces such behavior and is able to well appr...

A Fixed-Order Calculation of the Heavy-Quark Fragmentation Function in e+e− Collisions

We use a recently completed O(αs) fixed-order calculation of the heavyflavour production cross section in e+e− collisions to compute the heavy-quark fragmentation function. We fit the result of our calculation, convoluted with a Peterson fragmentation function, to available data for charm production, and thus obtain a value for the parameter ǫ in the Peterson function. We discuss the relevance ...