A simple approach to describe hadron production rates in e+e− annihilation

Pei, Y. J.

doi:10.1007/s002880050221

Cited by 50 publications

(51 citation statements)

References 20 publications

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“…This is consistent with the result from the previous publication [1] and with the result from combined e + e − data [16,17]. It is smaller than the naive spin-counting prediction of 0.75 and also smaller than 2/3, the value predicted by the string-fragmentation approach [52]. The strangeness-suppression factor obtained is γ s = 0.214 ± 0.013(stat.)…”

Section: Jhep09(2013)058supporting

confidence: 82%

Measurement of charm fragmentation fractions in photoproduction at HERA

Abramowicz¹,

Abt²,

Adamczyk³

et al. 2013

J. High Energ. Phys.

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The production of D 0 , D * + , D + , D + s and Λ + c charm hadrons and their antiparticles in ep scattering at HERA has been studied with the ZEUS detector, using a total integrated luminosity of 372 pb −1 . The fractions of charm quarks hadronising into a particular charm hadron were derived. In addition, the ratio of neutral to charged D-meson production rates, the fraction of charged D mesons produced in a vector state, and the stangenesssuppression factor have been determined. The measurements have been performed in the photoproduction regime. The charm hadrons were reconstructed in the range of transverse momentum p T > 3.8 GeV and pseudorapidity |η| < 1.6. The charm fragmentation fractions are compared to previous results from HERA and from e + e − experiments. The data support the hypothesis that fragmentation is independent of the production process. 6 Charm-hadron production cross sections 11 The ZEUS collaboration 24 IntroductionThe fragmentation fractions of charm quarks into specific charm hadrons cannot be predicted by Quantum Chromodynamics (QCD) and have to be measured. It is usually assumed that they are universal, i.e. the same for charm quarks produced in e + e − annihilation, in ep collisions and also in pp or other hadronic collisions, even though the charm production mechanisms are not the same: in e + e − collisions, cc pairs are produced dominantly by QED pair production, whereas in ep collisions, the main production mechanism is the QCD boson-gluon fusion process γg → cc. The fragmentation universality can be tested by measuring the fragmentation fractions at HERA and comparing the results with those obtained with e + e − collisions. Additionally, the values of the fragmentation fractions are crucial parameters used in comparisons of perturbative QCD (pQCD) calculations with measurements of charm production at HERA and elsewhere.-1 - JHEP09(2013)058In this paper, measurements of the photoproduction of charm hadrons in ep collisions at HERA are presented. The relative production rates of the most copiously produced charm ground states, the D In addition, the ratio of neutral to charged D-meson production rates, the fraction of charged D mesons produced in a vector state, and the strangeness-suppression factor were determined.The analysis presented here is based on an independent data set with an integrated luminosity over 4.5 times larger than the previous ZEUS measurement [1]. The new measurement benefits also from the ZEUS microvertex detector (MVD), which made it possible to identify the secondary decay vertices of the charm ground states and thereby to suppress background significantly. The new results are compared to the previous ZEUS measurement [1] in photoproduction, other HERA results from H1 [2] and ZEUS [3,4] in deep inelastic scattering, and to results from experiments at the e + e − storage rings CLEO [5,6], ARGUS [7][8][9] and the LEP experiments [10][11][12][13][14][15]. A summary is given in [16], with an update to 2010 branching ratios [17].

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Section: Jhep09(2013)058supporting

confidence: 82%

Measurement of charm fragmentation fractions in photoproduction at HERA

Abramowicz¹,

Abt²,

Adamczyk³

et al. 2013

J. High Energ. Phys.

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“…They are in excellent agreement with a trend of the LEP data for x p → 1. They are also well consistent with the predictions of the JETSET [1] 4 and Pei [29] models for the promptly produced mesons at LEP also shown in Fig. 2a.…”

supporting

confidence: 79%

Comparing fragmentation of strange quark in Z0 decays and K+p reactions

Chliapnikov

2001

Physics Letters B

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The ratios of the production rates K * 0 (892)/K, φ/K, ρ 0 /π, ω/π, ∆ ++ ( The vector and pseudoscalar mesons, or decuplet and octet baryons, differ in the relative orientation of the quark spins. Therefore the ratios of their production rates, V /P and D/O, provide us with important information on spin dependence in fragmentation. Hadronization models predict V /P and D/O for promptly produced particles, not resulting from decays of other particles or resonances. Therefore apart from the models based on Monte-Carlo generators, such as the JETSET model [1], these predictions are difficult to test experimentally.In the nonrelativistic quark model, the mass difference of the vector and pseudoscalar mesons, decuplet and octet baryons is explained by the hyperfine mass splitting. The production rates exhibit a strong mass dependence. Therefore the vector-to-pseudoscalar and decuplet-to-octet suppressions could also be explained, at least qualitatively, by the hyperfine mass splitting [2,3] provided that the rates of promptly produced particles were reliably estimated.The simplest spin model of fragmentation, such as the model suggested in [4] and subsequently developed by Anisovich and his collaborators in many other papers, is a random combination of quark spin states giving V /P = 3 1 E-mail address: chliapnikov@mx.ihep.su (P.V. Chliapnikov)

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“…agrees with the prediction of the tunnelling model of 8.5% [52]. The predictions of both models are based on fits to the production rates of light-flavoured hadrons at LEP.…”

Section: Mass Width and Helicity Parameterssupporting

confidence: 66%