Gradient Flow for the Jet Transport Coefficient: A Quenched Lattice Benchmark
Abstract
We apply the gradient-flow framework to determine the nonperturbative medium contribution to the jet transport coefficient q̂ using quenched lattice QCD in the temperature range 0.76Tc ≤ T ≤ 2.25Tc. The calculation focuses on the leading-twist contribution at leading order for an asymptotically energetic quark propagating through a thermal pure-gluon plasma. In the infinite-energy limit, the operator-product expansion expresses q̂/T3 in pure gauge theory as the product of a perturbative short-distance coefficient and the entropy density s/T3. The latter is determined from the gradient-flow energy-momentum tensor at three lattice spacings for each temperature and the former is estimated perturbatively at one-loop order. We find that q̂/T3 is strongly suppressed below Tc, rises rapidly across the deconfinement transition, and remains approximately constant at q̂/T3≃1.1 throughout the deconfined temperature range studied. This is statistically consistent with the previous quenched lattice determination based on a different renormalization procedure, providing a nontrivial validation of the gradient-flow framework for the jet transport coefficient. The systematic treatment of operator renormalization and matching provided by gradient flow becomes particularly important in full QCD, because the need to renormalize quark operators and account for their mixing with the gluonic sector can likewise be addressed within the same framework.
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BibTeX
@misc{shu2026gradient,
title = {{Gradient Flow for the Jet Transport Coefficient: A Quenched Lattice Benchmark}},
author = {Hai-Tao Shu and Cheng Zhang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.25089},
eprint = {2609.25089},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.25089},
}
RIS
TY - UNPB
TI - Gradient Flow for the Jet Transport Coefficient: A Quenched Lattice Benchmark
AU - Hai-Tao Shu
AU - Cheng Zhang
PY - 2026
DA - 2026/09/19
PB - arXiv
DO - 10.48550/arxiv.2609.25089
UR - https://arxiv.org/abs/2609.25089
AB - We apply the gradient-flow framework to determine the nonperturbative medium contribution to the jet transport coefficient q̂ using quenched lattice QCD in the temperature range 0.76T_c ≤ T ≤ 2.25T_c. The calculation focuses on the leading-twist contribution at leading order for an asymptotically energetic quark propagating through a thermal pure-gluon plasma. In the infinite-energy limit, the operator-product expansion expresses q̂/T^3 in pure gauge theory as the product of a perturbative short-distance coefficient and the entropy density s/T^3. The latter is determined from the gradient-flow energy-momentum tensor at three lattice spacings for each temperature and the former is estimated perturbatively at one-loop order. We find that q̂/T^3 is strongly suppressed below T_c, rises rapidly across the deconfinement transition, and remains approximately constant at q̂/T^3≃1.1 throughout the deconfined temperature range studied. This is statistically consistent with the previous quenched lattice determination based on a different renormalization procedure, providing a nontrivial validation of the gradient-flow framework for the jet transport coefficient. The systematic treatment of operator renormalization and matching provided by gradient flow becomes particularly important in full QCD, because the need to renormalize quark operators and account for their mixing with the gluonic sector can likewise be addressed within the same framework.
ER -