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).
(1) [2009-12-22] If you run the code by the g95 compiler,
wrong outputs are obtained although there is no problem by the g77, gfortran, and
intel fortran.
- In the supplied subroutine (hknsff07.f),
the the array PDFG should be saved.
- Solution: Please use
"SAVE IREAD, NPAR, BXG, CXG, DXG, PDFG"
in line 95 of hknsff07.f.
-
(Thank Dr. Stefano Melis for pointing out this issue.)
(2) [2008-03-28]
If you run the 2007 code, which was obtained
from our web site before March 27, 2008, it could lead to the error
"segmentation fault" for some fortran compilers.
- In the supplied subroutine (hknsff07.f),
the parameter number NPAR was not saved after setting NPAR
at a certain number when the subroutine is called for the first time.
Therefore, it could lead to the error
"segmentation fault" when the subroutine is called again.
[ As far as we tested various fortran compilers (g77, intel fortran, ...)
in linux, this problem does not occur.
- However, we have such an error
message if g77 is used in Macintosh. ]
- Solution: Please use
"SAVE IREAD, NPAR, BXG, CXG, DXG"
in line 95 of hknsff07.f.
-
(Thank Dr. Francois Arleo for pointing out this issue.)
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].