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arXiv · 1504.07451

Measurement of parity-violating spin asymmetries in W$^{\pm}$ production at midrapidity in longitudinally polarized $p$$+$$p$ collisions

A. Adare·C. Aidala·N. N. Ajitanand·Y. Akiba·R. Akimoto·J. Alexander·M. Alfred·K. Aoki·N. Apadula·Y. Aramaki·H. Asano·E. C. Aschenauer·E. T. Atomssa·T. C. Awes·B. Azmoun·V. Babintsev·M. Bai·X. Bai·N. S. Bandara·B. Bannier·K. N. Barish·B. Bassalleck·S. Bathe·V. Baublis·C. Baumann·S. Baumgart·A. Bazilevsky·M. Beaumier·S. Beckman·R. Belmont·A. Berdnikov·Y. Berdnikov·D. Black·D. S. Blau·J. S. Bok·K. Boyle·M. L. Brooks·J. Bryslawskyj·H. Buesching·V. Bumazhnov·S. Butsyk·S. Campbell·C. -H. Chen·C. Y. Chi·M. Chiu·I. J. Choi·J. B. Choi·S. Choi·R. K. Choudhury·P. Christiansen·T. Chujo·O. Chvala·V. Cianciolo·Z. Citron·B. A. Cole·M. Connors·N. Cronin·N. Crossette·M. Csanád·T. Csörgő·S. Dairaku·D. Danley·A. Datta·M. S. Daugherity·G. David·K. DeBlasio·K. Dehmelt·A. Denisov·A. Deshpande·E. J. Desmond·O. Dietzsch·L. Ding·A. Dion·P. B. Diss·J. H. Do·M. Donadelli·L. D'Orazio·O. Drapier·A. Drees·K. A. Drees·J. M. Durham·A. Durum·S. Edwards·Y. V. Efremenko·T. Engelmore·A. Enokizono·H. En'yo·S. Esumi·K. O. Eyser·B. Fadem·N. Feege·D. E. Fields·M. Finger·M. Finger Jr.·F. Fleuret·S. L. Fokin·J. E. Frantz·A. Franz·A. D. Frawley·Y. Fukao
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Abstract

We present measurements from the PHENIX experiment of large parity-violating single spin asymmetries of high transverse momentum electrons and positrons from $W^\pm/Z$ decays, produced in longitudinally polarized $p$$+$$p$ collisions at center of mass energies of $\sqrt{s}$=500 and 510~GeV. These asymmetries allow direct access to the anti-quark polarized parton distribution functions due to the parity-violating nature of the $W$-boson coupling to quarks and anti-quarks. The results presented are based on data collected in 2011, 2012, and 2013 with an integrated luminosity of 240 pb$^{-1}$, which exceeds previous PHENIX published results by a factor of more than 27. These high $Q^2$ data provide an important addition to our understanding of anti-quark parton helicity distribution functions.

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A. Adare, C. Aidala, N. N. Ajitanand, Y. Akiba, R. Akimoto, J. Alexander, M. Alfred, K. Aoki, N. Apadula, Y. Aramaki, H. Asano, E. C. Aschenauer, E. T. Atomssa, T. C. Awes, B. Azmoun, V. Babintsev, M. Bai, X. Bai, N. S. Bandara, B. Bannier, K. N. Barish, B. Bassalleck, S. Bathe, V. Baublis, C. Baumann, S. Baumgart, A. Bazilevsky, M. Beaumier, S. Beckman, R. Belmont, A. Berdnikov, Y. Berdnikov, D. Black, D. S. Blau, J. S. Bok, K. Boyle, M. L. Brooks, J. Bryslawskyj, H. Buesching, V. Bumazhnov, S. Butsyk, S. Campbell, C. -H. Chen, C. Y. Chi, M. Chiu, I. J. Choi, J. B. Choi, S. Choi, R. K. Choudhury, P. Christiansen, T. Chujo, O. Chvala, V. Cianciolo, Z. Citron, B. A. Cole, M. Connors, N. Cronin, N. Crossette, M. Csanád, T. Csörgő, S. Dairaku, D. Danley, A. Datta, M. S. Daugherity, G. David, K. DeBlasio, K. Dehmelt, A. Denisov, A. Deshpande, E. J. Desmond, O. Dietzsch, L. Ding, A. Dion, P. B. Diss, J. H. Do, M. Donadelli, L. D'Orazio, O. Drapier, A. Drees, K. A. Drees, J. M. Durham, A. Durum, S. Edwards, Y. V. Efremenko, T. Engelmore, A. Enokizono, H. En'yo, S. Esumi, K. O. Eyser, B. Fadem, N. Feege, D. E. Fields, M. Finger, M. Finger Jr., F. Fleuret, S. L. Fokin, J. E. Frantz, A. Franz, A. D. Frawley, Y. Fukao. 2015-04-28. Measurement of parity-violating spin asymmetries in W$^{\pm}$ production at midrapidity in longitudinally polarized $p$$+$$p$ collisions. https://doi.org/10.1103/physrevd.93.051103

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