The antiparticle-over-particle multiplicity ratio is measured in deep-inelastic scattering for negatively and positively charged kaons and, for the first time, for antiprotons and protons. The data were obtained by the COMPASS Collaboration using a 160 GeV muon beam impinging on an isoscalar (LiD)-Li-6 target. The regime of deep-inelastic scattering is ensured by requiring Q(2) > 1 (GeV/c)(2) for the photon virtuality and W > 5 GeV/c(2) for the invariant mass of the produced hadronic system. Bjorken-x is restricted to the range 0.01 to 0.40. Protons and antiprotons are identified in the momentum range from 20 GeV/c to 60 GeV/c and required to carry a large fraction of the virtual-photon energy, z > 0.5. In the whole studied z-region, the P over p multiplicity ratio is found to be below the lower limit expected from calculations based on leading-order perturbative Quantum Chromodynamics (pQCD). Kaons were previously analysed in the momentum range 12 GeV/c to 40 GeV/c. In the present analysis this range is extended up to 55 GeV/c, whereby events with larger virtual-photon energies are included in the analysis and the observed K- over K+ ratio becomes closer to the expectation of next-to-leading order pQCD. The results of both analyses strengthen our earlier conclusion that at COMPASS energies the phase space available for single-hadron production in deep-inelastic scattering should be taken into account in the standard pQCD formalism. (C) 2020 Published by Elsevier B.V.

Antiproton over proton and K− over K+ multiplicity ratios at high z in DIS

M. G. Alexeev;A. Amoroso;M. Chiosso;V. Frolov;A. Grasso;A. M. Kotzinian;D. Panzieri;B. Parsamyan;
2020-01-01

Abstract

The antiparticle-over-particle multiplicity ratio is measured in deep-inelastic scattering for negatively and positively charged kaons and, for the first time, for antiprotons and protons. The data were obtained by the COMPASS Collaboration using a 160 GeV muon beam impinging on an isoscalar (LiD)-Li-6 target. The regime of deep-inelastic scattering is ensured by requiring Q(2) > 1 (GeV/c)(2) for the photon virtuality and W > 5 GeV/c(2) for the invariant mass of the produced hadronic system. Bjorken-x is restricted to the range 0.01 to 0.40. Protons and antiprotons are identified in the momentum range from 20 GeV/c to 60 GeV/c and required to carry a large fraction of the virtual-photon energy, z > 0.5. In the whole studied z-region, the P over p multiplicity ratio is found to be below the lower limit expected from calculations based on leading-order perturbative Quantum Chromodynamics (pQCD). Kaons were previously analysed in the momentum range 12 GeV/c to 40 GeV/c. In the present analysis this range is extended up to 55 GeV/c, whereby events with larger virtual-photon energies are included in the analysis and the observed K- over K+ ratio becomes closer to the expectation of next-to-leading order pQCD. The results of both analyses strengthen our earlier conclusion that at COMPASS energies the phase space available for single-hadron production in deep-inelastic scattering should be taken into account in the standard pQCD formalism. (C) 2020 Published by Elsevier B.V.
2020
807
1
10
Quantum chromodynamics; pQCD; Deep-inelastic scattering; Hadron multiplicities; COMPASS
G.D. Alexeev; M.G. Alexeev; A. Amoroso; V. Andrieux; V. Anosov; A. Antoshkin; K. Augsten; W. Augustyniak; C.D.R. Azevedo; B. Badełek; F. Balestra; M. Ball; J. Barth; R. Beck; Y. Bedfer; J. Berenguer Antequera; J. Bernhard; M. Bodlak; F. Bradamante; A. Bressan; M. Büchele; V.E. Burtsev; W.-C. Chang; C. Chatterjee; M. Chiosso; A.G. Chumakov; S.-U. Chung; A. Cicuttin; P.M.M. Correia; M.L. Crespo; D. D'Ago; S. Dalla Torre; S.S. Dasgupta; S. Dasgupta; I. Denisenko; O.Yu. Denisov; S.V. Donskov; N. Doshita; Ch. Dreisbach; W. Dünnweber; R.R. Dusaev; A. Efremov; P.D. Eversheim; P. Faccioli; M. Faessler; M. Finger; M. Finger; H. Fischer; C. Franco; J.M. Friedrich; V. Frolov; F. Gautheron; O.P. Gavrichtchouk; S. Gerassimov; J. Giarra; I. Gnesi; M. Gorzellik; A. Grasso; A. Gridin; M. Grosse Perdekamp; B. Grube; A. Guskov; D. von Harrach; R. Heitz; F. Herrmann; N. Horikawa; N. d'Hose; C.-Y. Hsieh; S. Huber; S. Ishimoto; A. Ivanov; T. Iwata; M. Jandek; V. Jary; R. Joosten; P. Jörg; E. Kabuß; F. Kaspar; A. Kerbizi; B. Ketzer; G.V. Khaustov; Yu.A. Khokhlov; Yu. Kisselev; F. Klein; J.H. Koivuniemi; V.N. Kolosov; K. Kondo Horikawa; I. Konorov; V.F. Konstantinov; A.M. Kotzinian; O.M. Kouznetsov; A. Koval; Z. Kral; F. Krinner; Y. Kulinich; F. Kunne; K. Kurek; R.P. Kurjata; A. Kveton; K. Lavičková; S. Levorato; Y.-S. Lian; J. Lichtenstadt; P.-J. Lin; R. Longo; V.E. Lyubovitskij; A. Maggiora; A. Magnon; N. Makins; N. Makke; G.K. Mallot; A. Maltsev; S.A. Mamon; B. Marianski; A. Martin; J. Marzec; J. Matoušek; T. Matsuda; G. Mattson; G.V. Meshcheryakov; M. Meyer; W. Meyer; Yu.V. Mikhailov; M. Mikhasenko; E. Mitrofanov; N. Mitrofanov; Y. Miyachi; A. Moretti; A. Nagaytsev; C. Naim; D. Neyret; J. Nový; W.-D. Nowak; G. Nukazuka; A.S. Nunes; A.G. Olshevsky; M. Ostrick; D. Panzieri; B. Parsamyan; S. Paul; H. Pekeler; J.-C. Peng; M. Pešek; D.V. Peshekhonov; M. Pešková; N. Pierre; S. Platchkov; J. Pochodzalla; V.A. Polyakov; J. Pretz; M. Quaresma; C. Quintans; G. Reicherz; C. Riedl; T. Rudnicki; D.I. Ryabchikov; A. Rybnikov; A. Rychter; V.D. Samoylenko; A. Sandacz; S. Sarkar; I.A. Savin; G. Sbrizzai; H. Schmieden; A. Selyunin; L. Sinha; M. Slunecka; J. Smolik; A. Srnka; D. Steffen; M. Stolarski; O. Subrt; M. Sulc; H. Suzuki; P. Sznajder; S. Tessaro; F. Tessarotto; A. Thiel; J. Tomsa; F. Tosello; A. Townsend; V. Tskhay; S. Uhl; B.I. Vasilishin; A. Vauth; B.M. Veit; J. Veloso; B. Ventura; A. Vidon; M. Virius; M. Wagner; S. Wallner; K. Zaremba; P. Zavada; M. Zavertyaev; M. Zemko; E. Zemlyanichkina; Y. Zhao; M. Ziembicki
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1893508
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