Statistical analysis of the azimuthal asymmetry in the J/𝜓 leptoproduction in unpolarized ep collisions

Abstract

In this paper, we study the azimuthal asymmetry in the J/ψ leptoproduction in unpolarized ep collisions. There are two independent azimuthal asymmetry modulations, namely cos(ψ) and cos(2ψ), where ψ is the azimuthal angle of the lepton scattering plane with respect to the hadron-interacting plane. We calculate the two modulations as functions of four kinematic variables, and find that they provide a very good laboratory to distinguish several models describing the heavy quarkonium production, including the color-singlet (CS) model, the nonrelativistic QCD (NRQCD). In addition, this process can be used to test the magnitude of the 1 S [8] 0 long-distance matrix element, which is extraordinarily large from various phenomenological extraction. In order to make definite conclusions, we restrict our calculation in a specific kinematic region, where the CS and CO mechanisms can be distinguished by scrutinizing the values of the cos(ψ) modulation, while the 1 S [8] 0 dominance picture can be tested by measuring the values of the cos(2ψ) modulation. Calculating their values and carrying out a meticulous statistical analysis, we find that at an integrated luminosity L = 1000pb −1 , the statistical uncertainties of the two quantities are small enough to tell the three models apart. When this experiment is implemented at the future ep colliders such as the EIC, crucial information for the J/ψ production mechanism might be discovered.

J/ψ polarization in semi-inclusive DIS at low and high transverse momentum

“…where we have denoted the quantum numbers of the cc pair by (L, L z ; S, S z ). At the order in v we are considering and by further exploiting the symmetries of NRQCD, it can be shown that the partonic structure functions can be written in a factorized form, in which the nonperturbative contributions, encoded in the same four LDMEs 0|O(n)|0 that describe unpolarized J/ψ production [14, [49][50][51][52], are multiplied by perturbative shortdistant coefficients K P(a)…”

The production of the doubly charmed baryon in deeply inelastic ep scattering at the Large Hadron Electron Collider

“…In addition to the hadro-and photoproductions, the productions in deeply inelastic scattering (DIS) is another interesting process for the studies of the doubly charmed baryon, like the J/ψ case [58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75]. Analyzing the productions in DIS at finite Q 2 has theoretical and experimental advantages compared to the inelastic photoproduction (Q 2 0).…”

$J/ψ$ polarization in large-$P_T$ semi-inclusive deep-inelastic scattering at the EIC

“…The values of the CO LDMEs extracted from different fits to data on J/ψ and Υ yields [7][8][9][10][11] are not compatible with each other, even within the large uncertainties [12][13][14]. Therefore, any new method to determine them with better precision is worth exploring [15][16][17]. In this paper we propose to look at the J/ψ polarization parameters in semi-inclusive deep-inelastic scattering (SIDIS), e p → e J/ψ X, in a kinematic region where the transverse momentum of the J/ψ meson P T is large, namely P T Λ QCD , and collinear factorization is expected to hold.…”