Nonperturbative-transverse-momentum effects and evolution in dihadron and direct photon-hadron angular correlations in
collisions at
= 510 GeV
=510GeVでの陽子-陽子衝突におけるダイハドロン間および直接光子-ハドロン間の角度相関についての非摂動論的横運動量効果とその発展
Adare, A.*; 長谷川 勝一
; 今井 憲一; 永宮 正治; 佐甲 博之
; 佐藤 進
; 谷田 聖
; PHENIX Collaboration*; 他462名*
Adare, A.*; Hasegawa, Shoichi; Imai, Kenichi; Nagamiya, Shoji; Sako, Hiroyuki; Sato, Susumu; Tanida, Kiyoshi; PHENIX Collaboration*; 462 of others*
Dihadron and isolated direct photon-hadron angular correlations are measured in
collisions at
= 510 GeV. Correlations of charged hadrons of
GeV/
with
mesons of
GeV/
or isolated direct photons of
GeV/
are used to study nonperturbative effects generated by initial-state partonic transverse momentum and final-state transverse momentum from fragmentation. The nonperturbative behavior is characterized by measuring the out-of-plane transverse momentum component
perpendicular to the axis of the trigger particle, which is the high-
direct photon or
. Nonperturbative evolution effects are extracted from Gaussian fits to the away-side inclusive-charged-hadron yields for different trigger-particle transverse momenta (
). The Gaussian widths and root mean square of
are reported as a function of the interaction hard scale
to investigate possible transverse-momentum-dependent evolution differences between the
-
and direct photon-
correlations and factorization breaking effects. The widths are found to decrease with
, which indicates that the Collins-Soper-Sterman soft factor is not driving the evolution with the hard scale in nearly back-to-back dihadron and direct photon-hadron production in
collisions. This behavior is in contrast to Drell-Yan and semi-inclusive deep-inelastic scattering measurements.