Fragmentation fractions of $$c$$ c and $$b$$ b quarks into charmed hadrons at LEP

Abstract

The c quark fragmentation fractions represent probabilities to hadronise as a given charmed hadron, while the b quark fragmentation fractions are defined as sums of probabilities to produce a particular charmed hadron or its antiparticle.

Measurement of D-meson production at mid-rapidity in pp collisions at $${\sqrt{s}=7}$$ s = 7 TeV

“…The measured ratios are compatible within uncertainties with the results at √ s = 2.76 TeV [15] and with the measurements of the LHCb collaboration at forward rapidity (2.0 < y < 4.5) at three different collision energies √ s = 5, 7 and 13 TeV [19-21]. The measured p T -integrated production ratios are also compatible with the charm-quark fragmentation fractions f (c → D) measured in e + e − collisions from the compilation in [51]. These results indicate that the fragmentation fractions of charm quarks into different D-meson species do not vary substantially with rapidity, collision energy and colliding system.…”

“…the fractions of charm quarks hadronising into each D-meson species, were taken from Ref. [51]. For the D + s mesons, only the comparisons to GM-VFNS and LO k T -factorisation predictions are shown, because a calculation of the D + s production cross section within the FONLL framework is not available.…”

“…In the data-to-theory ratios the 3.5% normalisation uncertainty due to the luminosity determination is not included in the systematic uncertainty on the data points complete cancellation of the uncertainties in the ratio. Note that in all these pQCD calculations, the relative abundances of the different D-meson species are not predicted by the theory, but the fragmentation fractions, f (c → D), are taken from the experimental measurements [7,9,[51][52][53][54]. In the FONLL and GM-VFNS frameworks, the p T dependence of the ratios of the D-meson production cross sections arises from the different fragmentation functions used to model the transfer of energy from the charm quark to a specific D-meson species [52,53,55], and from the different contribution from decays of higher excited states.…”

“…For the fragmentation fraction, the value f (c → D 0 ) = 0.542 ± 0.024 derived in Ref. [51] by averaging the measurements from e + e − collisions at LEP was used. As pointed out in Refs.…”

Combined analysis of charm-quark fragmentation-fraction measurements

“…However, a careful treatment of correlated uncertainties due to common usage of branching ratios and theory inputs is essential, as in many measurements these are one of the leading uncertainty sources. In the past several combinations of fragmentationfraction data were performed with fewer inputs: the summary of the charm fragmentation fractions in e + e − at the Z resonance [25], the combination of e + e − measurements [26,27] as well as the combination of e + e − and e ± p measurements [28]. Compared to those, the present analysis extends to a larger set of measurements, in particular the final measurement in PHP by the ZEUS experiment at HERA [15], the pp measurements from LHCb [19,20], ALICE [21][22][23], ATLAS [24] and the + c measurements from the BABAR experiment [8].…”