English

Full energy fraction and angular dependence of medium-induced splittings in the large-$N_c$ limit

High Energy Physics - Phenomenology 2026-05-07 v2 Nuclear Theory

Abstract

Jets produced in relativistic heavy-ion collisions are modified by their interactions with the quark-gluon plasma (QGP), making jet substructure observables sensitive probes of QGP dynamics. A quantitative description of these modifications requires understanding how the medium affects elementary parton splittings with full dependence on both their energy fraction zz and splitting angle θ\theta, beyond the widely used soft emitted-gluon approximation. Here, we study medium-induced 121 \to 2 splittings double-differential in zz and θ\theta, with full resummation of multiple scatterings, and show that in the large-NcN_c limit and under the harmonic oscillator (HO) approximation, all path integrals can be evaluated analytically for any splitting channel, providing a computationally efficient semi-analytical result. We also revisit the semi-hard approximation (SHA), extending it to include leading corrections in inverse powers of the partons energies, which we denote the improved semi-hard approximation (ISHA), and assess its validity through a comparison with the large-NcN_c-HO results. Our analysis shows that while the SHA is found to be unreliable across most of phase space, even for high-energy emitters, the ISHA provides a robust approximation for splittings where all partons are sufficiently energetic.

Keywords

Cite

@article{arxiv.2603.27846,
  title  = {Full energy fraction and angular dependence of medium-induced splittings in the large-$N_c$ limit},
  author = {Carlota Andres and Fabio Dominguez},
  journal= {arXiv preprint arXiv:2603.27846},
  year   = {2026}
}

Comments

40 pages, 7 figures, plus two appendices with 7 additional figures. v2: typos corrected and two figures for evolving media added