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arXiv · 1009.6224

Cross section and double helicity asymmetry for eta mesons and their comparison to neutral pion production in p+p collisions at sqrt(s)=200 GeV

A. Adare·S. Afanasiev·C. Aidala·N. N. Ajitanand·Y. Akiba·H. Al-Bataineh·J. Alexander·K. Aoki·L. Aphecetche·R. Armendariz·S. H. Aronson·J. Asai·E. T. Atomssa·R. Averbeck·T. C. Awes·B. Azmoun·V. Babintsev·M. Bai·G. Baksay·L. Baksay·A. Baldisseri·K. N. Barish·P. D. Barnes·B. Bassalleck·A. T. Basye·S. Bathe·S. Batsouli·V. Baublis·C. Baumann·A. Bazilevsky·S. Belikov·R. Bennett·A. Berdnikov·Y. Berdnikov·A. A. Bickley·J. G. Boissevain·H. Borel·K. Boyle·M. L. Brooks·H. Buesching·V. Bumazhnov·G. Bunce·S. Butsyk·C. M. Camacho·S. Campbell·B. S. Chang·W. C. Chang·J. -L. Charvet·S. Chernichenko·J. Chiba·C. Y. Chi·M. Chiu·I. J. Choi·R. K. Choudhury·T. Chujo·P. Chung·A. Churyn·V. Cianciolo·Z. Citron·C. R. Cleven·B. A. Cole·M. P. Comets·P. Constantin·M. Csanád·T. Csörg\Hø·T. Dahms·S. Dairaku·K. Das·G. David·M. B. Deaton·K. Dehmelt·H. Delagrange·A. Denisov·D. d'Enterria·A. Deshpande·E. J. Desmond·O. Dietzsch·A. Dion·M. Donadelli·O. Drapier·A. Drees·K. A. Drees·A. K. Dubey·A. Durum·D. Dutta·V. Dzhordzhadze·Y. V. Efremenko·J. Egdemir·F. Ellinghaus·W. S. Emam·T. Engelmore·A. Enokizono·H. En'yo·S. Esumi·K. O. Eyser·B. Fadem·D. E. Fields·M. Finger, Jr.·M. Finger·F. Fleuret
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Abstract

Measurements of double-helicity asymmetries for inclusive hadron production in polarized p+p collisions are sensitive to helicity--dependent parton distribution functions, in particular to the gluon helicity distribution, Delta(g). This study focuses on the extraction of the double-helicity asymmetry in eta production: polarized p+p --> eta + X, the eta cross section, and the eta/pi^0 cross section ratio. The cross section and ratio measurements provide essential input for the extraction of fragmentation functions that are needed to access the helicity-dependent parton distribution functions.

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A. Adare, S. Afanasiev, C. Aidala, N. N. Ajitanand, Y. Akiba, H. Al-Bataineh, J. Alexander, K. Aoki, L. Aphecetche, R. Armendariz, S. H. Aronson, J. Asai, E. T. Atomssa, R. Averbeck, T. C. Awes, B. Azmoun, V. Babintsev, M. Bai, G. Baksay, L. Baksay, A. Baldisseri, K. N. Barish, P. D. Barnes, B. Bassalleck, A. T. Basye, S. Bathe, S. Batsouli, V. Baublis, C. Baumann, A. Bazilevsky, S. Belikov, R. Bennett, A. Berdnikov, Y. Berdnikov, A. A. Bickley, J. G. Boissevain, H. Borel, K. Boyle, M. L. Brooks, H. Buesching, V. Bumazhnov, G. Bunce, S. Butsyk, C. M. Camacho, S. Campbell, B. S. Chang, W. C. Chang, J. -L. Charvet, S. Chernichenko, J. Chiba, C. Y. Chi, M. Chiu, I. J. Choi, R. K. Choudhury, T. Chujo, P. Chung, A. Churyn, V. Cianciolo, Z. Citron, C. R. Cleven, B. A. Cole, M. P. Comets, P. Constantin, M. Csanád, T. Csörg\Hø, T. Dahms, S. Dairaku, K. Das, G. David, M. B. Deaton, K. Dehmelt, H. Delagrange, A. Denisov, D. d'Enterria, A. Deshpande, E. J. Desmond, O. Dietzsch, A. Dion, M. Donadelli, O. Drapier, A. Drees, K. A. Drees, A. K. Dubey, A. Durum, D. Dutta, V. Dzhordzhadze, Y. V. Efremenko, J. Egdemir, F. Ellinghaus, W. S. Emam, T. Engelmore, A. Enokizono, H. En'yo, S. Esumi, K. O. Eyser, B. Fadem, D. E. Fields, M. Finger, Jr., M. Finger, F. Fleuret. 2010-09-30. Cross section and double helicity asymmetry for eta mesons and their comparison to neutral pion production in p+p collisions at sqrt(s)=200 GeV. https://doi.org/10.1103/physrevd.83.032001

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