Nonsinglet kaon fragmentation function frome+e−kaon production

Abstract

We perform fits to the available charged and neutral kaon production data in e + + e − → K + X,, and determine the non-singlet combination of kaon fragmentation functions Din a model independent way and without any correlations to the other fragmentation functions. Only nuclear isospin invariance is assumed. Working with non-singlets allows us to include the data at very low momentum fractions, which have so far been excluded in global fits, and to perform a first NNLO fit to fragmentation functions. We find that the kaon non-singlet fragmentation function at large z is larger than that obtained by the other collaborations from global fit analysis and differs significantly at low z.

Study of Vector Meson Fragmentation Using a Broken Su(3) Model

“…In particular, an understanding of η and φ meson fragmentation in p p processes is important as a baseline for the study of the production of these mesons in nucleus-nucleus collisions as a signal of quark-gluon plasma (QGP) [3]. While there exist many phenomenological studies on π and K meson [4][5][6][7][8][9][10] and η fragmentation [5,11], as well as many comprehensive reviews [6][7][8]17] of these, the issue of vector meson hadro-production has not been addressed so far. In this paper we focus attention for the first time on light (u,d, s valence quarks only) vector meson fragmentation using a model that has earlier been applied to a study of light pseudo-scalar meson [4,5] and octet baryon [4] fragmentation.…”

“…In contrast, other studies [6][7][8][9][10][11] in, say, the pseudo-scalar meson sector, fit individual data on different mesons with no attempt made to combine the data in any way whatsoever. This is in fact one possible reason why the vector meson sparse data set may have not been studied so far.…”

On model independent extraction of the Kaon Fragmentation Functions

“…Unfortunately, the data around the Z-pole, where the most abundant and precise data exist, almost does not contribute. Our analysis would be easy if we had data on K ± and K 0 s production at the same z and s. However, as this is not the case, we proceed in three steps [7]: 1) we combine the measurements into 7 energy intervals: √ s = 12-14.8; 21.5-22; 29-35; 42.6-44; 58; 91.2; 183-189 GeV, 2) in each interval we fit K 0 s data purely phenomenologically and 3) we parametrize…”

Towards a model independent approach to fragmentation functions

“…where ê2 q (s) are the quark electro-weak charges. Using (18) we determine [6] (D u − D d ) K + +K − from the available data on K ± and K 0 s production in e + e − → (γ, Z) → K + X, K = K ± , K 0 s and compare it to those obtained in global fit analysis. Our analysis has several advantages: it allows for the first time to extract (D u − D d ) K + +K − without any assumptions about the FFs (commonly used in global fit analysis) and without any correlations to other FFs (and especially to D K ± g ), it allows to use data at much lower values of z than in global fit analysis (being a NS the combination σ K e + e − does not contain the unresummed soft gluon logarithms), etc.…”