Fragmentation functions

Exotic hadron search by fragmentation functions
M. Hirai, S. Kumano, M. Oka, K. Sudoh
hep-ph/0708.1816 (submitted for publication).

It is proposed that fragmentation functions should be used to identify exotic hadrons. As an example, fragmentation functions of the scalar meson f0(980) are investigated. It is pointed out that the second moments and functional forms of the u- and s-quark fragmentation functions can distinguish the tetraquark structure from q-qbar. By the global analysis of f0(980) production data in electron-positron annihilation, its fragmentation functions and their uncertainties are determined. It is found that the current available data are not sufficient to determine its internal structure, while precise data in future should be able to identify exotic quark configurations.

Determination of fragmentation functions and their uncertainties
M. Hirai, S. Kumano, T.-H. Nagai, K. Sudoh
Phys. Rev. D75 (2007) 094009 (hep-ph/0702250).

For getting the fragmentation-function library (hkns07fflib-v1_2.tar.gz : The above bug is fixed.), please click here.

From the enclosed FORTRAN program, one can obtain fragmentation functions for pi+, K+, p, pi-, K-, n, pi0, (K0+K0bar)/2, and (p+pbar)/2 at a given z and Q^2 point within the range, 0.01<=z<=1, 1<=Q^2<=10^8 GeV^2. Read the beginning of the program (hknsff07.f) for explanation of input values. A sample program (sample.f) is provided. The fragmentation functions for each hadron (K^0, K^0-bar, pbar, nbar) can be calculated by using the relations in Appendix of hep-ph/0702250. The details are explained in the paper.

A limited number of grid points are taken for the variables z and Q^2. The determined fragmentation functions are provided as grid data at these points. Then, they are interpolated for providing the values of the fragmentation functions at given z and Q^2 by a user.
(Note) Because of the interpolations across the charm and bottom thresholds, the library may not provide precise charm- and bottom-quark fragmentation functions at the Q^2 scales which are very close to the thresholds [(1.43)^2=2.0449 < Q^2 < 2.15 GeV^2 for charm, (4.3)^2=18.49 < Q^2 < 21.5 GeV^2 for bottom].