Abstract
Large angle gluon radiations induced by multiple parton scatterings contribute to dijet production in deeply inelastic scattering off a large nucleus at the Electron-Ion Collider. Within the generalized high-twist approach to multiple parton scattering, such contributions at the leading order in perturbative QCD and large Bjorken momentum fraction $x_B$ can be expressed as a convolution of the multiple parton scattering amplitudes and the transverse momentum dependent (TMD) two-parton correlation matrix elements. We study this medium-induced dijet spectrum and its azimuthal angle correlation under the approximation of small longitudinal momentum transfer in the secondary scattering and the factorization of two-parton correlation matrix elements as a product of quark and gluon TMD parton distribution function (PDF). Using a simple model for gluon saturation based on the parametrized gluon TMD PDF, we can calculate the $x_B$ and $Q^2$ dependence of the saturation scale and parton transport coefficient $\hat q$. Contributions to dijet cross section from double scattering are power-suppressed and only become sizable for mini-jets at small transverse momentum. We find that the total dijet correlation for these mini-jets, which also includes the contribution from single scattering, is sensitive to the transverse momentum broadening in the quark TMD PDF at large $x$ and saturation in the gluon TMD PDF at small $x$ inside the nucleus. The correlation from double scattering is also found to increase with the dijet rapidity gap and have a quadratic nuclear-size dependence because of the Landau-Pomeranchuk-Migdal (LPM) interference in gluon emission induced by multiple scattering. Experimental measurements of such unique features in the dijet correlation can shed light on the LPM interference in strong interaction and gluon saturation in large nuclei.
Highlights
Jet quenching in high-energy heavy-ion collisions caused by energy loss of energetic partons due to multiple parton scattering and induced gluon radiation in a hot quark-gluon plasma (QGP) has been the subject of intense theoretical and experimental studies [1,2,3,4,5,6,7] over the last several decades
We find that the total dijet correlation for these minijets, which includes the contribution from single scattering, is sensitive to the transverse momentum broadening in the quark transverse momentum dependent (TMD) parton distribution function (PDF) at large x and saturation in the gluon TMD PDF at small x inside the nucleus
Since we focus on the nuclear modification of the dijet cross section in the leading order in this study, we assume that such factorization can be applied to the double hard scattering processes with the large transverse momentum imbalance
Summary
Jet quenching in high-energy heavy-ion collisions caused by energy loss of energetic partons due to multiple parton scattering and induced gluon radiation in a hot quark-gluon plasma (QGP) has been the subject of intense theoretical and experimental studies [1,2,3,4,5,6,7] over the last several decades. The extracted jet transport coefficient qin cold nuclear matter from experimental data on the suppression of leading hadrons in SIDIS [27,28] and transverse momentum broadening [29] is about 2 orders of magnitude smaller than that in the hot QGP in high-energy heavy-ion collisions. Within the generalized high-twist approach, one can study multiple parton scattering in the opposite limit of the collinear exchanged gluon approximation In this case, the initial transverse momentum from the medium gluon can be large and comparable to the transverse momentum of the final radiated gluon.
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