Measurement of charged pion double spin asymmetries at midrapidity in longitudinally polarized p+p collisions at s=510  GeV

U Acharya,J Murata,B Kurgyis,B Bannier,Y Ikeda,V Papavassiliou,T Murakami,A Durum,N Novitzky,H Ge,D Roach,M Grosse Perdekamp,A Dion,J Sziklai,Y Berdnikov,Y Aramaki,D Isenhower,A Berdnikov,V Canoa Roman,B Meredith,A Hodges,R Lacey,S Nelson,K Tanida,B Fadem,M Stepanov,H Nakagomi,G Mitsuka,T Sumita,T Koblesky,A Sexton,K Deblasio,T Hachiya,I Shein,A Pun,S Esumi,R Nishitani,E Kistenev,S Mizuno,M Mccumber,T Todoroki,D Ivanishchev,C Gal,A Denisov,Y Watanabe,C Pinkenburg,K Nakano,V Bumazhnov,C Mckinney,A Lebedev,D Jouan,A Taketani,S Tarafdar,M Patel,A Iordanova,T Hoshino,I Ravinovich,A Mwai,M Tomášek,B Azmoun,A Adare,M Virius,G David,S Sawada,F Wei,N Ramasubramanian,K Boyle,N Grau,S Bathe,V Babintsev,J Runchey,J Hanks,K Kihara,S Nagamiya,M Mendoza,Iu Mitrankov,R Petti,L Xue,L Zou,K Dehmelt,A Franz,A Enokizono,S Beckman,K Imai,M Sarsour,M Nihashi,N Feege,Y Goto,J Koster,A Taranenko,M Leitgab,T Niida,I Nakagawa,J Bryslawskyj,W Peng,A Yanovich,E Joo,Y Ueda,M Slunečka,E Vznuzdaev,N Riveli,D Richford,Y Imazu,M Towell,R Seto,T Moon,D Kotov,A Drees,S Zharko,K Sedgwick,L Patel,M Potekhin,M Jezghani,A Deshpande,J Klatsky,T Majoros,D Kleinjan,M Beaumier,R Belmont,J Seele,A Manion,M Wysocki,A Bazilevsky,A Meles,B Xia,M Rosati,A Timilsina,R Pinson,Y Riabov,Z Rowan,D Kawall,D Lynch,R Seidl,P Montuenga,I Tserruya,M Chiu,K Kurita,Y Zhai,I Younus,D Kincses,R Pak,B Mulilo,Y Akiba,S Wolin,Sanghoon Lim ,A Glenn,T Gunji,D H Kim ,S Park,M Alfred,D V Perepelitsa ,P Sett,J G Lajoie ,V Khachatryan,P K Netrakanti ,A Datta,L Ding,K K Hill ,M X Liu ,B K Singh ,J Rubin ,R A Soltz ,M Vargyas,A Khatiwada,V Vrba,N A Lewis ,М Фингер ,J S Haggerty ,J.-C Peng,J T Mitchell ,M Inaba,X Jiang,B Hong,I Yoon,R S Hollis ,B Jacak ,T Novák,P L Mcgaughey ,H Buesching,N Saito,K I Hahn ,M I Nagy ,K Shigaki,C P Wong ,M L Brooks ,M Kurosawa,C Nattrass,A Takahara,A Milov,X Sun,J A Key ,K S Joo ,A J Miller ,J E Frantz ,S Lökòs ,Jeongsu Bok ,M Daugherity ,J Sun,T K Hemmick ,Y H Leung ,T W Danley ,J L Nagle ,T A Shibata ,D Yu Peressounko ,Y I Makdisi ,S Fokin ,Z Wang,R Nouicer,B M Johnson ,R S Towell ,Qingyang Xu ,Y Yamaguchi ,J D Osborn ,C L Silva ,H Guragain,S Miyasaka,Shoichi Hasegawa ,D S Fitzgerald ,J H Kang ,T Csörgõ ,C A Aidala ,D Sharma,S F Pate ,D Mcglinchey,K Homma,X R Wang ,S I Morrow ,V Pantuev,R Tieulent,I J Choi ,M J Tannenbaum ,Z Sun,V K Singh ,C A Ogilvie ,R Esha,B K Schmoll ,Kenneth Francis Read ,P V Radzevich ,C Y ,A Öskarsson ,X Li,E Mannel,J Velkovska,C P Singh ,D P Morrison ,V Riabov,W J Metzger ,Y K Kim ,D Mishra ,W A Zajc ,H Hamagaki,D Silvermyr,J M Durham ,A V Kazantsev ,J C Hill ,I E Yushmanov ,Sihyun Jeon ,Timothy Thomas Rinn ,T V Moukhanova ,M Kim,P Gallus,V Manko ,J Choi ,H Asano,Z H Citron ,W Fan,A Khanzadeev,C E Perezlara ,H Yu,M J Leitch ,J D Orjuela Koop ,G D N Perera ,M Kofarago,P Shukla,S Greene ,A M Sickles ,J Jia,J Rak,T Chujo,P Kline,H Torii,S Huang,Z Ji,T Sakaguchi,S Campbell,S P Stoll ,A Sen,J Huang,A D Frawley ,V Samsonov,S Yalcin,Daisuke Watanabe ,R P Pisani ,E O’Brien,А Суханов ,K Ozawa,M Connors,M Makek,E J Kim ,C Kim,N S Bandara ,D S Jumper ,D J Kim ,A S Nyanin ,Susumu Sato ,H Sako,W E Sondheim ,I V Sourikova ,H J Kim ,K A Drees ,H W Van Hecke ,T Sugitate,C L Woody ,S Suzuki,S Whitaker,Y Wu,J Perry,H En’Yo,D Reynolds,C H Chen ,M Shimomura,N Apadula,Deirdre Black ,S Y Han ,M L Purschke ,X He,N N Ajitanand ,Y Gu,P Garg,E J Desmond ,J S Kang ,P W Stankus ,S Sörensen ,T O S Haseler ,K Smith ,T C Awes ,D E Fields ,C Scarlett ,S H Lee ,Y Miake,K N Barish ,F Giordano,B Schaefer,S Ishimaru,J Yoo ,A C Mignerey ,J H ,A Zelenski,K Nagashima,E A Gamez ,E T Atomssa ,Y Kwon,S D Rolnick ,Mei Bai ,B Ujvári ,M Csanád,K B Lee ,R Akimoto

doi:10.1103/physrevd.102.032001

Measurement of charged pion double spin asymmetries at midrapidity in longitudinally polarized p+p collisions at s=510 GeV

U Acharya, J Murata + Show 356 more

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https://doi.org/10.1103/physrevd.102.032001

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Journal: Physical Review D	Publication Date: Aug 5, 2020
Citations: 14	License type: CC BY 4.0

Affiliation: University of Jyväskylä

Abstract

The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the longitudinal double spin asymmetries, $A_{LL}$, for charged pions at midrapidity ($|\eta|<0.35$) in longitudinally polarized $p$$+$$p$ collisions at $\sqrt{s}=510$ GeV. These measurements are sensitive to the gluon spin contribution to the total spin of the proton in the parton momentum fraction $x$ range between 0.04 and 0.09. One can infer the sign of the gluon polarization from the ordering of pion asymmetries with charge alone. The asymmetries are found to be consistent with global quantum-chromodynamics fits of deep-inelastic scattering and data at $\sqrt{s}=200$ GeV, which show a nonzero positive contribution of gluon spin to the proton spin.

Highlights

The spin of the proton is known to be ħ=2, yet its decomposition in terms of its constituents, quarks and gluons, is not very well known
The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the longitudinal double spin asymmeptrffiiffies, ALL, for charged pions at midrapidity in longitudinally polarized p þ p collisions at s 1⁄4 510 GeV. These measurements are sensitive to the gluon spin contribution to the total spin of the proton in the parton momentum fraction x range between 0.04 and 0.09
We report double spin asymmetries atthepcffishffi a1⁄4rg5ed10pGioenVlotnhgaittudwinerael extracted by the PHENIX experiment at midrapidity

Summary

Introduction

The spin of the proton is known to be ħ=2, yet its decomposition in terms of its constituents, quarks and gluons, is not very well known. The fixed-target deep-inelastic scattering (DIS) experiments measured the polarized structure function, g1ðx; Q2Þ, where x is the parton momentum fraction of the proton and Q2 is the momentum transfer squared, enabling the reconstruction of the quark spin contributions, ΔΣðx; Q2Þ, with the help of weak and hyperon decay constants. Measurements found this contribution to be substantially smaller than expected [1], leading to the so-called spin crisis.

Methods

Results

Conclusion