J/ψPolarization at Hadron Colliders in Nonrelativistic QCD

Abstract

With nonrelativistic QCD factorization, we present a full next-to-leading order computation of the polarization observable for J/ψ production at hadron colliders including all important Fock states, i.e., 3S(1)([1,8]), 1S(0)([8]), and 3P(J)([8]). We find the 3P(J)([8]) channel contributes a positive longitudinal component and a negative transverse component, so the J/ψ polarization puzzle may be understood as the transverse components canceling between the 3S(1)([8]) and 3P(J)([8]) channels, which results in mainly the unpolarized (even slightly longitudinally polarized) J/ψ. This may give a possible solution to the long-standing J/ψ polarization puzzle. Predictions for J/ψ polarization at the LHC are also presented.

Probing quarkonium production mechanisms with jet substructure

“…The study in ref. [35] uses a NLO NRQCD calculation to fit the color-octet LDME to inclusive J/ψ production at high p ⊥ and finds values of the LDME that can produce negligible polarization in agreement with the data. However, these values of LDME are inconsistent with the results of fitting the world data in refs.…”

“…The fitted LDME are similar to those found in ref. [35] in the sense that O J/ψ ( 1 S (8) 0 ) is by far the largest matrix element and O J/ψ ( 3 P (8) 0 ) again has opposite sign as that extracted from fits to the world data. In ref.…”

“…[5,6] are considerably smaller than those in refs. [35,36]. However, the presence of nontrivial correlations between the uncertainties in [36] allows us to make a much sharper prediction for the gluon FJF than is naively suggested by the large individual error bars [37].…”

“…In addition to the extractions in refs. [5,6], we will consider values of the LDME extracted in two recent papers [35,36] that attempt to solve the polarization puzzle by focusing exclusively on high p ⊥ production of charmonia at collider experiments. The study in ref.…”

“…[5,6,36] and 1.16 GeV 3 in ref. [35]. We use the LDME extracted in the original fit and the error bands are the result of adding in quadrature the uncertainties for the LDME quoted in refs.…”