# Nuclear Theory Seminar

## "Medium Modification of Jet Substructure in the Opacity Expansion"

#### Presented by Matthew Sievert, Los Alamos

Friday, July 27, 2018, 11:00 am — Building 510, CFNS Seminar Room 2-38

The modification of jets and their substructure in the presence of quark-gluon matter, beyond solely the quenching of their production, is a cornerstone of jet tomography. Although the nature of different nuclear environments can vary widely, the manner in which an external potential leads to a modification of jets and their substructure is universal and applies to both hot and cold nuclear matter. An order-by-order calculation of the medium modifications is possible on the basis of the opacity expansion, a series which can be truncated at finite order if the average number of scatterings in the quark-gluon matter is not too large. Other methods exist which can resum the full opacity series into a path integral formalism that remains applicable at very high opacities. In this talk, I will present a new calculation in the opacity expansion approach which computes the gluon substructure of a quark jet with exact kinematics at second order in opacity. I will also derive a set of recursion relations which can be used to construct higher orders terms in the opacity expansion to any finite order. And finally, I will compare this approach to the resumed path integral formalism, discussing the strengths and weaknesses of both methods and opportunities to study their overlap.

Hosted by: Yacine Mehtar-Tani

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