We present a LO evaluation of helicity densities of valence, Delta u(v) + Delta d(v), non-strange sea, Delta(u) over bar + Delta(d) over bar, and strange quarks, Delta s (assumed to be equal to Delta(s) over bar). They have been obtained from the inclusive asymmetry A(1,d) and the semi-inclusive asymmetries A(1,d)(pi+), A(1,d)(pi-), A(1,d)(K+), A(1,d)(K-) measured in polarised deep inelastic muon-deuteron scattering. The full deuteron statistics of COMPASS (years 2002-2004 and 2006) has been used. The data cover the range Q(2) > 1 (GeV/c)(2) and 0.004 < x < 0.3. Both non-strange densities are found to be in a good agreement with previous measurements. The distribution of Delta s(x) is compatible with zero in the whole measured range, in contrast to the shape of the strange quark helicity distribution obtained in most LO and NLO QCD fits. The sensitivity of the values of Delta s(x) upon the choice of fragmentation functions used in the derivation is discussed. (C) 2009 Elsevier B.V. All rights reserved.

Flavour separation of helicity distributions from deep inelastic muon-deuteron scattering

ALEXEEV, Maxim;AMOROSO, Antonio;BALESTRA, Ferruccio;BUSSA, Maria Pia;CHIOSSO, Michela;GRASSO, Antonino;KOTZINIAN, Aram;MAGGIORA, MARCO;PIRAGINO, Guido;ROCCO, Elena;SOSIO, Stefano;
2009-01-01

Abstract

We present a LO evaluation of helicity densities of valence, Delta u(v) + Delta d(v), non-strange sea, Delta(u) over bar + Delta(d) over bar, and strange quarks, Delta s (assumed to be equal to Delta(s) over bar). They have been obtained from the inclusive asymmetry A(1,d) and the semi-inclusive asymmetries A(1,d)(pi+), A(1,d)(pi-), A(1,d)(K+), A(1,d)(K-) measured in polarised deep inelastic muon-deuteron scattering. The full deuteron statistics of COMPASS (years 2002-2004 and 2006) has been used. The data cover the range Q(2) > 1 (GeV/c)(2) and 0.004 < x < 0.3. Both non-strange densities are found to be in a good agreement with previous measurements. The distribution of Delta s(x) is compatible with zero in the whole measured range, in contrast to the shape of the strange quark helicity distribution obtained in most LO and NLO QCD fits. The sensitivity of the values of Delta s(x) upon the choice of fragmentation functions used in the derivation is discussed. (C) 2009 Elsevier B.V. All rights reserved.
2009
680
217
224
VALENCE QUARK DISTRIBUTION; PARTON DISTRIBUTIONS; POLARIZED TARGET; NUCLEON; PROTON; DIS
Alekseev M; Alexakhin VY; Alexandrov Y; Alexeev GD; Amoroso A; Austregesilo A; Badelek B; Balestra F; Ball J; Barth J; Baum G; Bedfer Y; Bernhard J; Bertini R; Bettinelli M; Birsa R; Bisplinghoff J; Bordalo P; Bradamante F; Bravar A; Bressan A; Brona G; Burtin E; Bussa MP; Chapiro A; Chiosso M; Chung SU; Cicuttin A; Colantoni M; Crespo ML; Torre SD; Dafni T; Das S; Dasgupta SS; Denisov OY; Dhara L; Diaz V; Dinkelbach AM; Donskov SV; Doshita N; Duic V; Dunnweber W; Efremov A; El Alaoui A; Eversheim PD; Eyrich W; Faessler M; Ferrero A; Finger M; Finger M; Fischer H; Franco C; Friedrich JM; Garfagnini R; Gautheron F; Gavrichtchouk OP; Gazda R; Gerassimov S; Geyer R; Giorgi M; Gobbo B; Goertz S; Grabmuller S; Grajek OA; Grasso A; Grube B; Gushterski R; Guskov A; Haas F; Hagemann R; von Harrach D; Hasegawa T; Heckmann J; Heinsius FH; Hermann R; Herrmann F; Hess C; Hinterberger F; Horikawa N; Hoppner C; d'Hose N; Ilgner C; Ishimoto S; Ivanov O; Ivanshin Y; Iwata T; Jahn R; Jasinski P; Jegou G; Joosten R; Kabuss E; Kafer W; Kang D; Ketzer B; Khaustov GV; Khokhlov YA; Kiefer J; Kisselev Y; Klein F; Klimaszewski K; Koblitz S; Koivuniemi JH; Kolosov VN; Komissarov EV; Kondo K; Konigsmann K; Konopka R; Konorov I; Konstantinov VF; Korzenev A; Kotzinian AM; Kouznetsov O; Kowalik K; Kramer M; Kral A; Kroumchtein ZV; Kuhn R; Kunne F; Kurek K; Le Goff JM; Lednev AA; Lehmann A; Levorato S; Lichtenstadt J; Liska T; Maggiora A; Maggiora M; Magnon A; Mallot GK; Mann A; Marchand C; Marroncle J; Martin A; Marzec J; Massmann F; Matsuda T; Maximov AN; Meyer W; Michigami T; Mikhailov YV; Moinester MA; Mutter A; Nagaytsev A; Nagel T; Nassalski J; Negrini S; Nerling F; Neubert S; Neyret D; Nikolaenko VI; Olshevsky AG; Ostrick M; Padee A; Panknin R; Panzieri D; Parsamyan B; Paul S; Pawlukiewicz-Kaminska B; Perevalova E; Pesaro G; Peshekhonov DV; Piragino G; Platchkov S; Pochodzalla J; Polak J; Polyakov VA; Pontecorvo G; Pretz J; Quintans C; Rajotte JF; Ramos S; Rapatsky V; Reicherz G; Reggiani D; Richter A; Robinet F; Rocco E; Rondio E; Ryabchikov DI; Samoylenko VD; Sandacz A; Santos H; Sapozhnikov MG; Sarkar S; Savin IA; Sbrizzai G; Schiavon P; Schill C; Schmitt L; Schroder W; Shevchenko OY; Siebert HW; Silva L; Sinha L; Sissakian AN; Slunecka M; Smirnov GI; Sosio S; Sozzi F; Srnka A; Stolarski M; Sulc M; Sulej R; Takekawa S; Tessaro S; Tessarotto F; Teufel A; Tkatchev LG; Venugopal G; Virius M; Viassov NV; Vossen A; Weitzel Q; Wenzl K; Windmolders R; Wislicki W; Wollny H; Zaremba K; Zavertyaev M; Zemlyanichkina E; Ziembicki M; Zhao J; Zhuravlev N; Zvyagin A
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/77763
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