Energy evolution of T-odd gluon TMDs at small $x$

Abstract

We study the energy or TMD evolution of the three leading twist dipole type T-odd gluon TMDs inside a transversely polarized nucleon, all of which at small x dynamically originate from the spin dependent odderon. Their energy dependence presents a unique opportunity to study the polarization dependent TMD evolution in the small-x region, where the distributions are identical up to a normalization constant at tree level. We further propose to study their evolution via azimuthal asymmetries in virtual photon-jet production in polarized proton-proton collisions at RHIC. We present model predictions for the asymmetries as functions of the large jet or photon transverse momentum and Q 2 which set the hard scales in this process.

Dijet photoproduction at low x at next-to-leading order and its back-to-back limit

“…In kinematics with a hierarchy of scales s µ 2 µ 2 b Λ 2 QCD , the necessity arises to simultaneously treat large ln(s/µ 2 ) and ln(µ 2 /µ 2 b ) logarithms. Such a combined low-x and Sudakov resummation is the subject of intensive research, some of which very recent, either JHEP10(2022)184 based on the HEF approach [33][34][35][36][37][38][39][40][41][42][43], BFKL [44,45], BK [46], the CGC [47][48][49][50][51][52], and TMD factorization [53][54][55].…”

Transverse momentum dependent distribution functions in the threshold limit

“…the non-perturbative parametrization of TMD functions has been investigated extensively in [14][15][16][17][18][19][20][21][22][23][24][25]. In the context of the small-x limit, the naive TMD factorization formula at the leading-power might no longer apply, and numerous studies have addressed TMD functions with considerations for gluon saturation effects [26][27][28][29][30]. Conversely, as x approaches larger values, the underlying factorization theorem of leading-power TMD factorization remains robust; nonetheless, the associated resummation formula begins to incorporate non-negligible logarithmic contributions.…”

Subfemtometer scale color charge correlations in the proton

“…The relation of various Odderon amplitudes to Generalized Transverse Momentum Dependent parton distributions (GTMDs) has been elucidated in refs. [7][8][9][10][11][12].…”