The spin structure function gp1 of the proton and a test of the Bjorken sum rule

C. Adolph; R. Akhunzyanov; M. G. Alexeev; G. D. Alexeev; A. Amoroso; V. Andrieux; V. Anosov; A. Austregesilo; C. Azevedo; B. Badełek; F. Balestra; J. Barth; G. Baum; R. Beck; Y. Bedfer; J. Bernhard; K. Bicker; E. R. Bielert; R. Birsa; J. Bisplinghoff; M. Bodlak; M. Boer; P. Bordalo; F. Bradamante; C. Braun; A. Bressan; M. Büchele; E. Burtin; L. Capozza; W. C. Chang; M. Chiosso; I. Choi; S. U. Chung; A. Cicuttin; M. L. Crespo; Q. Curiel; S. Dalla Torre; S. S. Dasgupta; S. Dasgupta; O. Yu Denisov; L. Dhara; S. V. Donskov; N. Doshita; V. Duic; M. Dziewiecki; A. Efremov; P. D. Eversheim; W. Eyrich; A. Ferrero; M. Finger; M. Finger; H. Fischer; C. Franco; N. du Fresne von Hohenesche; J. M. Friedrich; V. Frolov; E. Fuchey; F. Gautheron; O. P. Gavrichtchouk; S. Gerassimov; F. Giordano; I. Gnesi; M. Gorzellik; S. Grabmüller; A. Grasso; M. Grosse-Perdekamp; B. Grube; T. Grussenmeyer; A. Guskov; F. Haas; D. Hahne; D. von Harrach; R. Hashimoto; F. H. Heinsius; F. Herrmann; F. Hinterberger; N. Horikawa; N. d'Hose; C. Yu Hsieh; S. Huber; S. Ishimoto; A. Ivanov; Yu Ivanshin; T. Iwata; R. Jahn; V. Jary; P. Jörg; R. Joosten; E. Kabuß; B. Ketzer; G. V. Khaustov; Yu A. Khokhlov; Yu Kisselev; F. Klein; K. Klimaszewski; J. H. Koivuniemi; V. N. Kolosov; K. Kondo; K. Königsmann; I. Konorov; V. F. Konstantinov; A. M. Kotzinian; O. Kouznetsov; M. Krämer; P. Kremser; F. Krinner; Z. V. Kroumchtein; N. Kuchinski; F. Kunne; K. Kurek; R. P. Kurjata; A. A. Lednev; A. Lehmann; M. Levillain; S. Levorato; J. Lichtenstadt; R. Longo; A. Maggiora; A. Magnon; N. Makins; N. Makke; G. K. Mallot; C. Marchand; A. Martin; J. Marzec; J. Matousek; H. Matsuda; T. Matsuda; G. Meshcheryakov; W. Meyer; T. Michigami; Yu V. Mikhailov; Y. Miyachi; A. Nagaytsev; T. Nagel; F. Nerling; D. Neyret; V. I. Nikolaenko; J. Novy; W. D. Nowak; A. S. Nunes; A. G. Olshevsky; I. Orlov; M. Ostrick; D. Panzieri; B. Parsamyan; S. Paul; J. C. Peng; F. Pereira; M. Pesek; D. V. Peshekhonov; S. Platchkov; J. Pochodzalla; V. A. Polyakov; J. Pretz; M. Quaresma; C. Quintans; S. Ramos; C. Regali; G. Reicherz; C. Riedl; E. Rocco; N. S. Rossiyskaya; D. I. Ryabchikov; A. Rychter; V. D. Samoylenko; A. Sandacz; C. Santos; S. Sarkar; I. A. Savin; G. Sbrizzai; P. Schiavon; K. Schmidt; H. Schmieden; K. Schönning; S. Schopferer; A. Selyunin; O. Yu Shevchenko; L. Silva; L. Sinha; S. Sirtl; M. Slunecka; F. Sozzi; A. Srnka; M. Stolarski; M. Sulc; H. Suzuki; A. Szabelski; T. Szameitat; P. Sznajder; S. Takekawa; J. ter Wolbeek; S. Tessaro; F. Tessarotto; F. Thibaud; F. Tosello; V. Tskhay; S. Uhl; J. Veloso; M. Virius; T. Weisrock; M. Wilfert; R. Windmolders; K. Zaremba; M. Zavertyaev; E. Zemlyanichkina; M. Ziembicki; A. Zink

doi:10.1016/j.physletb.2015.11.064

The spin structure function g^p₁ of the proton and a test of the Bjorken sum rule

C. Adolph, R. Akhunzyanov, M. G. Alexeev, G. D. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, A. Austregesilo, C. Azevedo, B. Badełek, F. Balestra, J. Barth, G. Baum, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E. R. Bielert, R. Birsa, J. BisplinghoffM. Bodlak, M. Boer, P. Bordalo, F. Bradamante, C. Braun, A. Bressan^*, M. Büchele, E. Burtin, L. Capozza, W. C. Chang, M. Chiosso, I. Choi, S. U. Chung, A. Cicuttin, M. L. Crespo, Q. Curiel, S. Dalla Torre, S. S. Dasgupta, S. Dasgupta, O. Yu Denisov, L. Dhara, S. V. Donskov, N. Doshita, V. Duic, M. Dziewiecki, A. Efremov, P. D. Eversheim, W. Eyrich, A. Ferrero, M. Finger, M. Finger, H. Fischer, C. Franco, N. du Fresne von Hohenesche, J. M. Friedrich, V. Frolov, E. Fuchey, F. Gautheron, O. P. Gavrichtchouk, S. Gerassimov, F. Giordano, I. Gnesi, M. Gorzellik, S. Grabmüller, A. Grasso, M. Grosse-Perdekamp, B. Grube, T. Grussenmeyer, A. Guskov, F. Haas, D. Hahne, D. von Harrach, R. Hashimoto, F. H. Heinsius, F. Herrmann, F. Hinterberger, N. Horikawa, N. d'Hose, C. Yu Hsieh, S. Huber, S. Ishimoto, A. Ivanov, Yu Ivanshin, T. Iwata, R. Jahn, V. Jary, P. Jörg, R. Joosten, E. Kabuß, B. Ketzer, G. V. Khaustov, Yu A. Khokhlov, Yu Kisselev, F. Klein, K. Klimaszewski, J. H. Koivuniemi, V. N. Kolosov, K. Kondo, K. Königsmann, I. Konorov, V. F. Konstantinov, A. M. Kotzinian, O. Kouznetsov, M. Krämer, P. Kremser, F. Krinner, Z. V. Kroumchtein, N. Kuchinski, F. Kunne, K. Kurek, R. P. Kurjata, A. A. Lednev, A. Lehmann, M. Levillain, S. Levorato, J. Lichtenstadt, R. Longo, A. Maggiora, A. Magnon, N. Makins, N. Makke, G. K. Mallot, C. Marchand, A. Martin, J. Marzec, J. Matousek, H. Matsuda, T. Matsuda, G. Meshcheryakov, W. Meyer, T. Michigami, Yu V. Mikhailov, Y. Miyachi, A. Nagaytsev, T. Nagel, F. Nerling, D. Neyret, V. I. Nikolaenko, J. Novy, W. D. Nowak, A. S. Nunes, A. G. Olshevsky, I. Orlov, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, J. C. Peng, F. Pereira, M. Pesek, D. V. Peshekhonov, S. Platchkov, J. Pochodzalla, V. A. Polyakov, J. Pretz, M. Quaresma, C. Quintans, S. Ramos, C. Regali, G. Reicherz, C. Riedl, E. Rocco, N. S. Rossiyskaya, D. I. Ryabchikov, A. Rychter, V. D. Samoylenko, A. Sandacz, C. Santos, S. Sarkar, I. A. Savin, G. Sbrizzai, P. Schiavon, K. Schmidt, H. Schmieden, K. Schönning, S. Schopferer, A. Selyunin, O. Yu Shevchenko, L. Silva, L. Sinha, S. Sirtl, M. Slunecka, F. Sozzi, A. Srnka, M. Stolarski, M. Sulc, H. Suzuki, A. Szabelski, T. Szameitat, P. Sznajder, S. Takekawa, J. ter Wolbeek, S. Tessaro, F. Tessarotto, F. Thibaud, F. Tosello, V. Tskhay, S. Uhl, J. Veloso, M. Virius, T. Weisrock, M. Wilfert, R. Windmolders, K. Zaremba, M. Zavertyaev, E. Zemlyanichkina, M. Ziembicki, A. Zink

^*Corresponding author for this work

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

124 Scopus citations

Abstract

New results for the double spin asymmetry A^p₁ and the proton longitudinal spin structure function g1p are presented. They were obtained by the COMPASS Collaboration using polarised 200 GeV muons scattered off a longitudinally polarised NH₃ target. The data were collected in 2011 and complement those recorded in 2007 at 160 GeV, in particular at lower values of x. They improve the statistical precision of g^p₁(x) by about a factor of two in the region x ≲0.02. A next-to-leading order QCD fit to the g₁ world data is performed. It leads to a new determination of the quark spin contribution to the nucleon spin, δσ, ranging from 0.26 to 0.36, and to a re-evaluation of the first moment of g1p. The uncertainty of δσ is mostly due to the large uncertainty in the present determinations of the gluon helicity distribution. A new evaluation of the Bjorken sum rule based on the COMPASS results for the non-singlet structure function g^NS₁(x,Q²) yields as ratio of the axial and vector coupling constants |g_A/g_V|=1.22 ± 0.05 (stat.) ± 0.10 (syst.), which validates the sum rule to an accuracy of about 9%.

Original language	English
Pages (from-to)	18-28
Number of pages	11
Journal	Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume	753
DOIs	https://doi.org/10.1016/j.physletb.2015.11.064
State	Published - 10 Feb 2016

Funding

Funders	Funder number
European Commission
Seventh Framework Programme	283286
Japan Society for the Promotion of Science	26247032
Fundação para a Ciência e a Tecnologia	CERN/FP/123600/2011

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10.1016/j.physletb.2015.11.064

Cite this

Adolph, C., Akhunzyanov, R., Alexeev, M. G., Alexeev, G. D., Amoroso, A., Andrieux, V., Anosov, V., Austregesilo, A., Azevedo, C., Badełek, B., Balestra, F., Barth, J., Baum, G., Beck, R., Bedfer, Y., Bernhard, J., Bicker, K., Bielert, E. R., Birsa, R., ... Zink, A. (2016). The spin structure function g^p₁ of the proton and a test of the Bjorken sum rule. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 753, 18-28. https://doi.org/10.1016/j.physletb.2015.11.064

@article{6bc6c93e66794d57955035a2f69442e0,

title = "The spin structure function gp1 of the proton and a test of the Bjorken sum rule",

abstract = "New results for the double spin asymmetry Ap1 and the proton longitudinal spin structure function g1p are presented. They were obtained by the COMPASS Collaboration using polarised 200 GeV muons scattered off a longitudinally polarised NH3 target. The data were collected in 2011 and complement those recorded in 2007 at 160 GeV, in particular at lower values of x. They improve the statistical precision of gp1(x) by about a factor of two in the region x ≲0.02. A next-to-leading order QCD fit to the g1 world data is performed. It leads to a new determination of the quark spin contribution to the nucleon spin, δσ, ranging from 0.26 to 0.36, and to a re-evaluation of the first moment of g1p. The uncertainty of δσ is mostly due to the large uncertainty in the present determinations of the gluon helicity distribution. A new evaluation of the Bjorken sum rule based on the COMPASS results for the non-singlet structure function gNS1(x,Q2) yields as ratio of the axial and vector coupling constants |gA/gV|=1.22 ± 0.05 (stat.) ± 0.10 (syst.), which validates the sum rule to an accuracy of about 9\%.",

author = "C. Adolph and R. Akhunzyanov and Alexeev, \{M. G.\} and Alexeev, \{G. D.\} and A. Amoroso and V. Andrieux and V. Anosov and A. Austregesilo and C. Azevedo and B. Bade{\l}ek and F. Balestra and J. Barth and G. Baum and R. Beck and Y. Bedfer and J. Bernhard and K. Bicker and Bielert, \{E. R.\} and R. Birsa and J. Bisplinghoff and M. Bodlak and M. Boer and P. Bordalo and F. Bradamante and C. Braun and A. Bressan and M. B{\"u}chele and E. Burtin and L. Capozza and Chang, \{W. C.\} and M. Chiosso and I. Choi and Chung, \{S. U.\} and A. Cicuttin and Crespo, \{M. L.\} and Q. Curiel and \{Dalla Torre\}, S. and Dasgupta, \{S. S.\} and S. Dasgupta and Denisov, \{O. Yu\} and L. Dhara and Donskov, \{S. V.\} and N. Doshita and V. Duic and M. Dziewiecki and A. Efremov and Eversheim, \{P. D.\} and W. Eyrich and A. Ferrero and M. Finger and M. Finger and H. Fischer and C. Franco and \{du Fresne von Hohenesche\}, N. and Friedrich, \{J. M.\} and V. Frolov and E. Fuchey and F. Gautheron and Gavrichtchouk, \{O. P.\} and S. Gerassimov and F. Giordano and I. Gnesi and M. Gorzellik and S. Grabm{\"u}ller and A. Grasso and M. Grosse-Perdekamp and B. Grube and T. Grussenmeyer and A. Guskov and F. Haas and D. Hahne and \{von Harrach\}, D. and R. Hashimoto and Heinsius, \{F. H.\} and F. Herrmann and F. Hinterberger and N. Horikawa and N. d'Hose and Hsieh, \{C. Yu\} and S. Huber and S. Ishimoto and A. Ivanov and Yu Ivanshin and T. Iwata and R. Jahn and V. Jary and P. J{\"o}rg and R. Joosten and E. Kabu{\ss} and B. Ketzer and Khaustov, \{G. V.\} and Khokhlov, \{Yu A.\} and Yu Kisselev and F. Klein and K. Klimaszewski and Koivuniemi, \{J. H.\} and Kolosov, \{V. N.\} and K. Kondo and K. K{\"o}nigsmann and I. Konorov and Konstantinov, \{V. F.\} and Kotzinian, \{A. M.\} and O. Kouznetsov and M. Kr{\"a}mer and P. Kremser and F. Krinner and Kroumchtein, \{Z. V.\} and N. Kuchinski and F. Kunne and K. Kurek and Kurjata, \{R. P.\} and Lednev, \{A. A.\} and A. Lehmann and M. Levillain and S. Levorato and J. Lichtenstadt and R. Longo and A. Maggiora and A. Magnon and N. Makins and N. Makke and Mallot, \{G. K.\} and C. Marchand and A. Martin and J. Marzec and J. Matousek and H. Matsuda and T. Matsuda and G. Meshcheryakov and W. Meyer and T. Michigami and Mikhailov, \{Yu V.\} and Y. Miyachi and A. Nagaytsev and T. Nagel and F. Nerling and D. Neyret and Nikolaenko, \{V. I.\} and J. Novy and Nowak, \{W. D.\} and Nunes, \{A. S.\} and Olshevsky, \{A. G.\} and I. Orlov and M. Ostrick and D. Panzieri and B. Parsamyan and S. Paul and Peng, \{J. C.\} and F. Pereira and M. Pesek and Peshekhonov, \{D. V.\} and S. Platchkov and J. Pochodzalla and Polyakov, \{V. A.\} and J. Pretz and M. Quaresma and C. Quintans and S. Ramos and C. Regali and G. Reicherz and C. Riedl and E. Rocco and Rossiyskaya, \{N. S.\} and Ryabchikov, \{D. I.\} and A. Rychter and Samoylenko, \{V. D.\} and A. Sandacz and C. Santos and S. Sarkar and Savin, \{I. A.\} and G. Sbrizzai and P. Schiavon and K. Schmidt and H. Schmieden and K. Sch{\"o}nning and S. Schopferer and A. Selyunin and Shevchenko, \{O. Yu\} and L. Silva and L. Sinha and S. Sirtl and M. Slunecka and F. Sozzi and A. Srnka and M. Stolarski and M. Sulc and H. Suzuki and A. Szabelski and T. Szameitat and P. Sznajder and S. Takekawa and \{ter Wolbeek\}, J. and S. Tessaro and F. Tessarotto and F. Thibaud and F. Tosello and V. Tskhay and S. Uhl and J. Veloso and M. Virius and T. Weisrock and M. Wilfert and R. Windmolders and K. Zaremba and M. Zavertyaev and E. Zemlyanichkina and M. Ziembicki and A. Zink",

note = "Publisher Copyright: {\textcopyright} 2015 The Authors.",

year = "2016",

month = feb,

day = "10",

doi = "10.1016/j.physletb.2015.11.064",

language = "אנגלית",

volume = "753",

pages = "18--28",

journal = "Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics",

issn = "0370-2693",

publisher = "Elsevier B.V.",

}

Adolph, C, Akhunzyanov, R, Alexeev, MG, Alexeev, GD, Amoroso, A, Andrieux, V, Anosov, V, Austregesilo, A, Azevedo, C, Badełek, B, Balestra, F, Barth, J, Baum, G, Beck, R, Bedfer, Y, Bernhard, J, Bicker, K, Bielert, ER, Birsa, R, Bisplinghoff, J, Bodlak, M, Boer, M, Bordalo, P, Bradamante, F, Braun, C, Bressan, A, Büchele, M, Burtin, E, Capozza, L, Chang, WC, Chiosso, M, Choi, I, Chung, SU, Cicuttin, A, Crespo, ML, Curiel, Q, Dalla Torre, S, Dasgupta, SS, Dasgupta, S, Denisov, OY, Dhara, L, Donskov, SV, Doshita, N, Duic, V, Dziewiecki, M, Efremov, A, Eversheim, PD, Eyrich, W, Ferrero, A, Finger, M, Finger, M, Fischer, H, Franco, C, du Fresne von Hohenesche, N, Friedrich, JM, Frolov, V, Fuchey, E, Gautheron, F, Gavrichtchouk, OP, Gerassimov, S, Giordano, F, Gnesi, I, Gorzellik, M, Grabmüller, S, Grasso, A, Grosse-Perdekamp, M, Grube, B, Grussenmeyer, T, Guskov, A, Haas, F, Hahne, D, von Harrach, D, Hashimoto, R, Heinsius, FH, Herrmann, F, Hinterberger, F, Horikawa, N, d'Hose, N, Hsieh, CY, Huber, S, Ishimoto, S, Ivanov, A, Ivanshin, Y, Iwata, T, Jahn, R, Jary, V, Jörg, P, Joosten, R, Kabuß, E, Ketzer, B, Khaustov, GV, Khokhlov, YA, Kisselev, Y, Klein, F, Klimaszewski, K, Koivuniemi, JH, Kolosov, VN, Kondo, K, Königsmann, K, Konorov, I, Konstantinov, VF, Kotzinian, AM, Kouznetsov, O, Krämer, M, Kremser, P, Krinner, F, Kroumchtein, ZV, Kuchinski, N, Kunne, F, Kurek, K, Kurjata, RP, Lednev, AA, Lehmann, A, Levillain, M, Levorato, S, Lichtenstadt, J, Longo, R, Maggiora, A, Magnon, A, Makins, N, Makke, N, Mallot, GK, Marchand, C, Martin, A, Marzec, J, Matousek, J, Matsuda, H, Matsuda, T, Meshcheryakov, G, Meyer, W, Michigami, T, Mikhailov, YV, Miyachi, Y, Nagaytsev, A, Nagel, T, Nerling, F, Neyret, D, Nikolaenko, VI, Novy, J, Nowak, WD, Nunes, AS, Olshevsky, AG, Orlov, I, Ostrick, M, Panzieri, D, Parsamyan, B, Paul, S, Peng, JC, Pereira, F, Pesek, M, Peshekhonov, DV, Platchkov, S, Pochodzalla, J, Polyakov, VA, Pretz, J, Quaresma, M, Quintans, C, Ramos, S, Regali, C, Reicherz, G, Riedl, C, Rocco, E, Rossiyskaya, NS, Ryabchikov, DI, Rychter, A, Samoylenko, VD, Sandacz, A, Santos, C, Sarkar, S, Savin, IA, Sbrizzai, G, Schiavon, P, Schmidt, K, Schmieden, H, Schönning, K, Schopferer, S, Selyunin, A, Shevchenko, OY, Silva, L, Sinha, L, Sirtl, S, Slunecka, M, Sozzi, F, Srnka, A, Stolarski, M, Sulc, M, Suzuki, H, Szabelski, A, Szameitat, T, Sznajder, P, Takekawa, S, ter Wolbeek, J, Tessaro, S, Tessarotto, F, Thibaud, F, Tosello, F, Tskhay, V, Uhl, S, Veloso, J, Virius, M, Weisrock, T, Wilfert, M, Windmolders, R, Zaremba, K, Zavertyaev, M, Zemlyanichkina, E, Ziembicki, M & Zink, A 2016, 'The spin structure function g^p₁ of the proton and a test of the Bjorken sum rule', Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, vol. 753, pp. 18-28. https://doi.org/10.1016/j.physletb.2015.11.064

TY - JOUR

T1 - The spin structure function gp1 of the proton and a test of the Bjorken sum rule

AU - Adolph, C.

AU - Akhunzyanov, R.

AU - Alexeev, M. G.

AU - Alexeev, G. D.

AU - Amoroso, A.

AU - Andrieux, V.

AU - Anosov, V.

AU - Austregesilo, A.

AU - Azevedo, C.

AU - Badełek, B.

AU - Balestra, F.

AU - Barth, J.

AU - Baum, G.

AU - Beck, R.

AU - Bedfer, Y.

AU - Bernhard, J.

AU - Bicker, K.

AU - Bielert, E. R.

AU - Birsa, R.

AU - Bisplinghoff, J.

AU - Bodlak, M.

AU - Boer, M.

AU - Bordalo, P.

AU - Bradamante, F.

AU - Braun, C.

AU - Bressan, A.

AU - Büchele, M.

AU - Burtin, E.

AU - Capozza, L.

AU - Chang, W. C.

AU - Chiosso, M.

AU - Choi, I.

AU - Chung, S. U.

AU - Cicuttin, A.

AU - Crespo, M. L.

AU - Curiel, Q.

AU - Dalla Torre, S.

AU - Dasgupta, S. S.

AU - Dasgupta, S.

AU - Denisov, O. Yu

AU - Dhara, L.

AU - Donskov, S. V.

AU - Doshita, N.

AU - Duic, V.

AU - Dziewiecki, M.

AU - Efremov, A.

AU - Eversheim, P. D.

AU - Eyrich, W.

AU - Ferrero, A.

AU - Finger, M.

AU - Fischer, H.

AU - Franco, C.

AU - du Fresne von Hohenesche, N.

AU - Friedrich, J. M.

AU - Frolov, V.

AU - Fuchey, E.

AU - Gautheron, F.

AU - Gavrichtchouk, O. P.

AU - Gerassimov, S.

AU - Giordano, F.

AU - Gnesi, I.

AU - Gorzellik, M.

AU - Grabmüller, S.

AU - Grasso, A.

AU - Grosse-Perdekamp, M.

AU - Grube, B.

AU - Grussenmeyer, T.

AU - Guskov, A.

AU - Haas, F.

AU - Hahne, D.

AU - von Harrach, D.

AU - Hashimoto, R.

AU - Heinsius, F. H.

AU - Herrmann, F.

AU - Hinterberger, F.

AU - Horikawa, N.

AU - d'Hose, N.

AU - Hsieh, C. Yu

AU - Huber, S.

AU - Ishimoto, S.

AU - Ivanov, A.

AU - Ivanshin, Yu

AU - Iwata, T.

AU - Jahn, R.

AU - Jary, V.

AU - Jörg, P.

AU - Joosten, R.

AU - Kabuß, E.

AU - Ketzer, B.

AU - Khaustov, G. V.

AU - Khokhlov, Yu A.

AU - Kisselev, Yu

AU - Klein, F.

AU - Klimaszewski, K.

AU - Koivuniemi, J. H.

AU - Kolosov, V. N.

AU - Kondo, K.

AU - Königsmann, K.

AU - Konorov, I.

AU - Konstantinov, V. F.

AU - Kotzinian, A. M.

AU - Kouznetsov, O.

AU - Krämer, M.

AU - Kremser, P.

AU - Krinner, F.

AU - Kroumchtein, Z. V.

AU - Kuchinski, N.

AU - Kunne, F.

AU - Kurek, K.

AU - Kurjata, R. P.

AU - Lednev, A. A.

AU - Lehmann, A.

AU - Levillain, M.

AU - Levorato, S.

AU - Lichtenstadt, J.

AU - Longo, R.

AU - Maggiora, A.

AU - Magnon, A.

AU - Makins, N.

AU - Makke, N.

AU - Mallot, G. K.

AU - Marchand, C.

AU - Martin, A.

AU - Marzec, J.

AU - Matousek, J.

AU - Matsuda, H.

AU - Matsuda, T.

AU - Meshcheryakov, G.

AU - Meyer, W.

AU - Michigami, T.

AU - Mikhailov, Yu V.

AU - Miyachi, Y.

AU - Nagaytsev, A.

AU - Nagel, T.

AU - Nerling, F.

AU - Neyret, D.

AU - Nikolaenko, V. I.

AU - Novy, J.

AU - Nowak, W. D.

AU - Nunes, A. S.

AU - Olshevsky, A. G.

AU - Orlov, I.

AU - Ostrick, M.

AU - Panzieri, D.

AU - Parsamyan, B.

AU - Paul, S.

AU - Peng, J. C.

AU - Pereira, F.

AU - Pesek, M.

AU - Peshekhonov, D. V.

AU - Platchkov, S.

AU - Pochodzalla, J.

AU - Polyakov, V. A.

AU - Pretz, J.

AU - Quaresma, M.

AU - Quintans, C.

AU - Ramos, S.

AU - Regali, C.

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PY - 2016/2/10

Y1 - 2016/2/10

N2 - New results for the double spin asymmetry Ap1 and the proton longitudinal spin structure function g1p are presented. They were obtained by the COMPASS Collaboration using polarised 200 GeV muons scattered off a longitudinally polarised NH3 target. The data were collected in 2011 and complement those recorded in 2007 at 160 GeV, in particular at lower values of x. They improve the statistical precision of gp1(x) by about a factor of two in the region x ≲0.02. A next-to-leading order QCD fit to the g1 world data is performed. It leads to a new determination of the quark spin contribution to the nucleon spin, δσ, ranging from 0.26 to 0.36, and to a re-evaluation of the first moment of g1p. The uncertainty of δσ is mostly due to the large uncertainty in the present determinations of the gluon helicity distribution. A new evaluation of the Bjorken sum rule based on the COMPASS results for the non-singlet structure function gNS1(x,Q2) yields as ratio of the axial and vector coupling constants |gA/gV|=1.22 ± 0.05 (stat.) ± 0.10 (syst.), which validates the sum rule to an accuracy of about 9%.

AB - New results for the double spin asymmetry Ap1 and the proton longitudinal spin structure function g1p are presented. They were obtained by the COMPASS Collaboration using polarised 200 GeV muons scattered off a longitudinally polarised NH3 target. The data were collected in 2011 and complement those recorded in 2007 at 160 GeV, in particular at lower values of x. They improve the statistical precision of gp1(x) by about a factor of two in the region x ≲0.02. A next-to-leading order QCD fit to the g1 world data is performed. It leads to a new determination of the quark spin contribution to the nucleon spin, δσ, ranging from 0.26 to 0.36, and to a re-evaluation of the first moment of g1p. The uncertainty of δσ is mostly due to the large uncertainty in the present determinations of the gluon helicity distribution. A new evaluation of the Bjorken sum rule based on the COMPASS results for the non-singlet structure function gNS1(x,Q2) yields as ratio of the axial and vector coupling constants |gA/gV|=1.22 ± 0.05 (stat.) ± 0.10 (syst.), which validates the sum rule to an accuracy of about 9%.

UR - http://www.scopus.com/inward/record.url?scp=84949655686&partnerID=8YFLogxK

U2 - 10.1016/j.physletb.2015.11.064

DO - 10.1016/j.physletb.2015.11.064

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AN - SCOPUS:84949655686

SN - 0370-2693

VL - 753

SP - 18

EP - 28

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

ER -

The spin structure function g^p₁ of the proton and a test of the Bjorken sum rule

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