1. Final COMPASS results on the deuteron spin-dependent structure function $g_1^{\rm d}$ and the Bjorken sum rule
- Author
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Adolph, C., Aghasyan, M., Akhunzyanov, R., Alexeev, M.G., Alexeev, G.D., Amoroso, A., Andrieux, V., Anfimov, N.V., Anosov, V., Augsten, K., Augustyniak, W., Austregesilo, A., Azevedo, C.D.R., Badełek, B., Balestra, F., Ball, M., Barth, J., Beck, R., Bedfer, Y., Bernhard, J., Bicker, K., Bielert, E. R., Birsa, R., Bodlak, M., Bordalo, P., Bradamante, F., Braun, C., Bressan, A., Büchele, M., Chang, W.-C., Chatterjee, C., Chiosso, M., Choi, I., Chung, S.-U., Cicuttin, A., Crespo, M.L., Curiel, Q., Dalla Torre, S., Dasgupta, S.S., Dasgupta, S., Denisov, O.Yu., Dhara, L., Donskov, S.V., Doshita, N., Dreisbach, Ch., Duic, V., Dünnweber, W., Dziewiecki, M., Efremov, A., Eversheim, P.D., Eyrich, W., Faessler, M., Ferrero, A., Finger, M., Finger Jr., M., Fischer, H., Franco, C., du Fresne von Hohenesche, N., Friedrich, J.M., Frolov, V., Fuchey, E., Gautheron, F., Gavrichtchouk, O.P., Gerassimov, S., Giarra, J., Giordano, F., Gnesi, I., Gorzellik, M., Grabmüller, S., Grasso, A., Grosse Perdekamp, M., Grube, B., Grussenmeyer, T., Guskov, A., Haas, F., Hahne, D., Hamar, G., von Harrach, D., Heinsius, F.H., Heitz, R., Herrmann, F., Horikawa, N., d'Hose, N., Hsieh, C.-Y., Huber, S., Ishimoto, S., Ivanov, A., Ivanshin, Yu., Iwata, T., Jary, V., Joosten, R., Jörg, P., Kabuß, E., Kerbizi, A., Ketzer, B., Khaustov, G.V., Khokhlov, Yu.A., Kisselev, Yu., Klein, F., Klimaszewski, K., Koivuniemi, J.H., Kolosov, V.N., Kondo, K., Königsmann, K., Konorov, I., Konstantinov, V.F., Kotzinian, A.M., Kouznetsov, O.M., Krämer, M., Kremser, P., Krinner, F., Kroumchtein, Z.V., Kulinich, Y., Kunne, F., Kurek, K., Kurjata, R.P., Lednev, A.A., Lehmann, A., Levillain, M., Levorato, S., Lian, Y.-S., Lichtenstadt, J., Longo, R., Maggiora, A., Magnon, A., Makins, N., Makke, N., Mallot, G.K., Marianski, B., Martin, A., Marzec, J., Matoušek, J., Matsuda, H., Matsuda, T., Meshcheryakov, G.V., Meyer, M., Meyer, W., Mikhailov, Yu.V., Mikhasenko, M., Mitrofanov, E., Mitrofanov, N., Miyachi, Y., Nagaytsev, A., Nerling, F., Neyret, D., Nový, J., Nowak, W.-D., Nukazuka, G., Nunes, A.S., Olshevsky, A.G., Orlov, I., Ostrick, M., Panzieri, D., Parsamyan, B., Paul, S., Peng, J.-C., Pereira, F., Pešek, M., Peshekhonov, D.V., Pierre, N., Platchkov, S., Pochodzalla, J., Polyakov, V.A., Pretz, J., Quaresma, M., Quintans, C., Ramos, S., Regali, C., Reicherz, G., Riedl, C., Roskot, M., Rossiyskaya, N.S., Ryabchikov, D.I., Rybnikov, A., Rychter, A., Salac, R., Samoylenko, V.D., Sandacz, A., Santos, C., Sarkar, S., Savin, I.A., Sawada, T., Sbrizzai, G., Schiavon, P., Schmidt, K., Schmieden, H., Schönning, K., Seder, E., Selyunin, A., Silva, L., Sinha, L., Sirtl, S., Slunecka, M., Smolik, J., Srnka, A., Steffen, D., Stolarski, M., Subrt, O., Sulc, M., Suzuki, H., Szabelski, A., Szameitat, T., Sznajder, P., Takekawa, S., Tasevsky, M., Tessaro, S., Tessarotto, F., Thibaud, F., Thiel, A., Tosello, F., Tskhay, V., Uhl, S., Vauth, A., Veloso, J., Virius, M., Vondra, J., Wallner, S., Weisrock, T., Wilfert, M., Windmolders, R., Wolbeek, J. ter, Zaremba, K., Zavada, P., Zavertyaev, M., Zemlyanichkina, E., Zhuravlev, N., Ziembicki, M., Zink, A., Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, COMPASS, Institut de Recherches sur les lois Fondamentales de l'Univers ( IRFU ), and Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay
- Subjects
cross section: ratio ,sum rule: Bjorken ,polarized target ,FOS: Physical sciences ,muon deuteron: deep inelastic scattering ,structure function: spin ,momentum transfer dependence ,COMPASS ,beam: energy ,High Energy Physics - Experiment ,x-dependence ,renormalization ,scaling: Bjorken ,p: spin ,High Energy Physics - Experiment (hep-ex) ,polarization: asymmetry ,Spin ,[ PHYS.HEXP ] Physics [physics]/High Energy Physics - Experiment [hep-ex] ,strong coupling ,[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex] ,quark: helicity ,quantum chromodynamics: perturbation theory ,Nuclear Experiment ,charge: axial ,Parton helicity distributions ,hep-ex ,High Energy Physics::Phenomenology ,coupling constant ,deuteron: structure function ,CERN SPS ,Structure function ,kinematics ,final state: hadronic ,nucleon: spin ,High Energy Physics::Experiment ,muon: polarized beam ,statistical ,Particle Physics - Experiment ,Deep inelastic scattering ,experimental results - Abstract
Final results are presented from the inclusive measurement of deep-inelastic polarised-muon scattering on longitudinally polarised deuterons using a $^6$LiD target. The data were taken at $160~{\rm GeV}$ beam energy and the results are shown for the kinematic range $1~({\rm GeV}/c)^2 < Q^2 < 100~({\rm GeV}/c)^2$ in photon virtuality, $0.004 4~{\rm GeV}/c^2$ in the mass of the hadronic final state. The deuteron double-spin asymmetry $A_1^{\rm d}$ and the deuteron longitudinal-spin structure function $g_1^{\rm d}$ are presented in bins of $x$ and $Q^2$. Towards lowest accessible values of $x$, $g_1^{\rm d}$ decreases and becomes consistent with zero within uncertainties. The presented final $g_1^{\rm d}$ values together with the recently published final $g_1^{\rm p}$ values of COMPASS are used to again evaluate the Bjorken sum rule and perform the QCD fit to the $g_1$ world data at next-to-leading order of the strong coupling constant. In both cases, changes in central values of the resulting numbers are well within statistical uncertainties. The flavour-singlet axial charge $a_0$, {which is identified in the $\overline{\rm MS}$ renormalisation scheme with the total contribution of quark helicities to the nucleon spin}, is extracted from only the COMPASS deuteron data with negligible extrapolation uncertainty: $a_0 (Q^2 = 3~({\rm GeV}/c)^2) = 0.32 \pm 0.02_{\rm stat} \pm0.04_{\rm syst} \pm 0.05_{\rm evol}$. Together with the recent results on the proton spin structure function $g_1^{\rm p}$, the results on $g_1^{\rm d}$ constitute the COMPASS legacy on the measurements of $g_1$ through inclusive spin-dependent deep inelastic scattering., Comment: 16 pages, 6 figures
- Published
- 2016
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