Nonperturbative transverse-momentum-dependent effects in dihadron and direct photon-hadron angular correlations in p+p collisions at s=200  GeV

C A Aidala ,J Runchey,N Feege,S Karthas,J Murata,S Zharko,H Ge,R Belmont,Y Ueda,A Deshpande,N Cronin,J Bryslawskyj,D Kincses,C Pinkenburg,V Canoa Roman,D Richford,A Dion,A Bazilevsky,J Sziklai,A Timilsina,D Kotov,R Cervantes,Y Akiba,V Babintsev,P Kline,Y Riabov,S Esumi,G Mitsuka,M Slunečka,N Apadula,R Seto,K Imai,M Sarsour,A Berdnikov,D Kawall,M Rosati,A Hodges,W Peng,P Montuenga,R Seidl,T Majoros,C Gal,K Kurita,M Tomášek,A Lebedev,K Dehmelt,A Drees,I Shein,D Kapukchyan,T Hoshino,N Hotvedt,M Virius,I Nakagawa,M Finger,L Zou,J Hanks,T Moon,Y Berdnikov,R Petti,E Kistenev,S Mizuno,T Niida,M Beaumier,K Sedgwick,N Vukman,A Durum,D Jouan,V Papavassiliou,A Enokizono,I Tserruya,D Ivanishchev,K Deblasio,D Lynch,K Tanida,T Sumita,Y Goto,M Jezghani,J Klatsky,G Tarnai,Y Fukuda,K Nakano,A Taranenko,T Koblesky,A Yanovich,N Grau,B Fadem,V Bumazhnov,B Azmoun,T Hachiya,C Mckinney,M Patel,S Bathe,T Murakami,D Isenhower,M Chiu,M Mendoza,A Iordanova,N Novitzky,M Grosse Perdekamp,T Todoroki,Z Rowan,G David,L Xue,A Franz,M Mccumber,B Kurgyis,A Sukhanov,A Sexton,V Andrieux,A Denisov,M Alfred,A Bagoly,A Zelenski,M Connors,J Velkovska,F Giordano,S Tarafdar,R Nouicer,Y Kwon,I Yoon,T Shioya,S Lee,J Sun,A Sen,M Makek,T Sakaguchi,H W Van Hecke ,T K Hemmick ,A S Nyanin ,J D Orjuela Koop ,K K Hill ,K N Barish ,K F Read ,M J Skoby ,S Sörensen ,B M Johnson ,Susumu Sato ,M L Brooks ,D Mishra ,M L Purschke ,J E Frantz ,C P Singh ,Y Yamaguchi ,M X Liu ,I V Sourikova ,R S Hollis ,C L Towell ,M W Phipps ,D Yu Peressounko ,N A Lewis ,D V Perepelitsa ,J M Durham ,G D N Perera ,C L Silva ,A D Frawley ,S H Lee ,C A Ogilvie ,R A Soltz ,M Boër ,C Y ,S Greene ,A Safonov ,T W Danley ,S Fokin ,R P Pisani ,A V Kazantsev ,P L Mcgaughey ,J H ,S F Pate ,D P Morrison ,K A Drees ,H F Hamilton ,B K Singh ,C L Woody ,M I Nagy ,D E Fields ,D S Jumper ,T A Shibata ,V K Singh ,Dhruv Utpalkumar Dixit ,B Ujvári ,C J Xu ,W A Zajc ,A Öskarsson ,R S Towell ,B Jacak ,W E Sondheim ,X R Wang ,K Lovász ,D Blau ,Y H Leung ,S I Morrow ,E J Desmond ,Hiroshi Yamamoto ,C E Perezlara ,T Csörgõ ,J T Mitchell ,S Y Han ,J G Lajoie ,N S Bandara ,Timothy Thomas Rinn ,Sanghoon Lim ,D E Mihalik ,I E Yushmanov ,Z H Citron ,M J Tannenbaum ,G J Ottino ,V Manko ,Jeongsu Bok ,J L Nagle ,J D Osborn ,I J Choi ,C P Wong ,Y I Makdisi ,K I Hahn ,M J Leitch ,P W Stankus ,A M Sickles ,S P Stoll ,B K Schmoll ,J S Haggerty ,M Daugherity ,J C Hill ,J Yoo ,Y Watanabe ,S D Rolnick ,Q H Xu ,J Choi ,A C Mignerey ,J S Park ,T O S Haseler ,S Lökòs ,P V Radzevich ,J H Kang ,M Inaba,H Guragain,K Shigaki,T Sugitate,H En’Yo,B Hong,V Pantuev,Z Ji,H Yu,M Snowball,E.-J Kim,K Ozawa,H Hamagaki,P Gallus,E Mannel,H Asano,A Khanzadeev,J Huang,X He,H Sako,W Fan,M Kim,E O’Brien,S Huang,K Nagai,D Sharma,B Schaefer,X Li,V Vrba,V.-R Loggins,Z Sun,K Homma,A Milov,S Kudo,P Garg,S Campbell,T Gunji,P Shukla,S Miyasaka,R Tieulent,M Csanád,D Mcglinchey,M Shimomura,C Kim,V Khachatryan,K Nagashima,V Samsonov,D Reynolds,C Nattrass,T Nagashima,T Novák,V Riabov,S Park,S Hasegawa,X Jiang,S Yalcin,J Perry,D Silvermyr

doi:10.1103/physrevd.98.072004

Nonperturbative transverse-momentum-dependent effects in dihadron and direct photon-hadron angular correlations in p+p collisions at s=200 GeV

C A Aidala , J Runchey + Show 290 more

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https://doi.org/10.1103/physrevd.98.072004

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Abstract

Dihadron and isolated direct photon-hadron angular correlations are measured in $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV. The correlations are sensitive to nonperturbative initial-state and final-state transverse momentum $k_T$ and $j_T$ in the azimuthal nearly back-to-back region $\Delta\phi\sim\pi$. In this region, transverse-momentum-dependent evolution can be studied when several different hard scales are measured. To have sensitivity to small transverse momentum scales, nonperturbative momentum widths of $p_{\rm out}$, the out-of-plane transverse momentum component perpendicular to the trigger particle, are measured. These widths are used to investigate possible effects from transverse-momentum-dependent factorization breaking. When accounting for the longitudinal momentum fraction of the away-side hadron with respect to the near-side trigger particle, the widths are found to increase with the hard scale; this is qualitatively similar to the observed behavior in Drell-Yan and semi-inclusive deep-inelastic scattering interactions. The momentum widths are also studied as a function of center-of-mass energy by comparing to previous measurements at $\sqrt{s}=510$ GeV. The nonperturbative jet widths also appear to increase with $\sqrt{s}$ at a similar $x_T$, which is qualitatively consistent to similar measurements in Drell-Yan interactions. To quantify the magnitude of any transverse-momentum-dependent factorization breaking effects, calculations will need to be performed to compare to these measurements.

Highlights

QCD research has entered a period in which the focus of nucleon structure has shifted from a one-dimensional to a multidimensional picture
In leading-order perturbative QCD processes where a colored parton is exchanged in the hard interaction, and color is necessarily present in both the initial and final states, soft gluon exchanges can lead to new effects in a TMD framework to the predicted modified universality of certain TMD parton distribution functions (PDFs)
In processes where factorization is broken, the nonperturbative objects can no longer be factorized into a convolution of TMD PDFs and TMD fragmentation functions (FFs) due to the complex color flows that are possible throughout the hard scattering and remnants of the collision and connect the initial- and final-state hadrons

Summary

INTRODUCTION

QCD research has entered a period in which the focus of nucleon structure has shifted from a one-dimensional to a multidimensional picture. In leading-order perturbative QCD processes where a colored parton is exchanged in the hard interaction, and color is necessarily present in both the initial and final states, soft gluon exchanges can lead to new effects in a TMD framework to the predicted modified universality of certain TMD PDFs. In hadronic collisions where a final-state hadron is measured and the process is sensitive to a small transverse-momentum scale, factorization breaking has been predicted [19,20,21,22]. In processes where factorization is broken, the nonperturbative objects can no longer be factorized into a convolution of TMD PDFs and TMD FFs due to the complex color flows that are possible throughout the hard scattering and remnants of the collision and connect the initial- and final-state hadrons In both cases of factorization breaking and modified universality of certain TMD PDFs, gluon exchanges with the remnants cannot be eliminated via gauge transformations. A previous nonidentified charged hadron cross section from PHENIX can be found in e.g., Ref. [40]

ANALYSIS

Statistical subtraction of decay photons

Azimuthal correlations

CONCLUSIONS