[Theory-seminars] Seminars next week

[Carlota Andres Casas]

Dear all,


Here is a reminder for next week theory seminars:

Theory seminar:
Monday, March 18th, 1:00PM, Room L102
Andrea Schindler (Michigan State University), "Nucleon Electric Dipole Moment results from lattice QCD using the Gradient Flow"

Abstract:
The electric dipole moments (EDMs) of the neutron and proton are very sensitive probes of CP-violating sources beyond those contained in the Standard Model (SM). In fact, the current bound on the neutron EDM strongly constrains many models of beyond-the-SM (BSM) physics. At current experimental accuracies, a nonzero nucleon EDM cannot be accounted for by the phase in the quark-mass matrix. This implies that such a signal is either caused by a nonzero QCD theta term, or by genuine BSM physics which, at low energies, can be parametrized in terms of higher- dimensional CP-violating quark-gluon operators. I will present recent results we have obtained from lattice QCD for the nucleon EDM induced by the theta term in QCD, by the quark-chromo and by the Weinberg operator. A key tool for our calculation is the use of the Gradient Flow. I will clarify the importance of the Gradient Flow in renormalizing the CP-violating operators and discuss the difficulties and pitfalls that an EDM lattice QCD calculation entails.


Theory seminar:
Wednesday, March 20th, 1:00PM, Room F326-F327
Felix Ringer (LBNL), "Factorization of jet cross sections in heavy-ion collisions"

Abstract:
At the LHC and RHIC highly energetic jets are used as probes of the created quark-gluon plasma (QGP). Medium properties are extracted relying on the assumption that the physics living at different energy scales can be consistently separated or factorized. However, QCD factorization is an approximation and even though it is well established in proton-proton collisions, the range of applicability could be very different in heavy-ion collisions. Therefore, we introduce a new phenomenological approach to establish QCD factorization in the heavy-ion environment. Starting from a factorization formalism in proton-proton collisions, we introduce medium modified jet functions that capture the interaction of jets with the hot and dense QCD medium. We perform a global analysis using a Monte Carlo sampling approach and find that it is indeed possible to describe the nuclear modification factor of inclusive jets within the new framework. Our work thus supports the notion of QCD factorization in heavy-ion collisions.

Theory seminar:
Friday, March 22th, 1:00PM, Room L102
Kimberley Cushman (Yale University) “Prony Methods for Extracting Excited States”

Abstract:
We hope to improve excited state extraction for our research in beyond the standard model composite Higgs dynamics. We propose an algebraic method of extracting excited states from lattice correlation functions which is also useful to lattice gauge theorists in general, as well as data analysts investigating exponentially decaying signals. Instead of fitting to a linear combination of exponentials, we adopt a variant of Prony’s method to obtain M energies (exponential decay rates) by finding the roots of an Mth order polynomial. I will describe the challenges faced in this approach and demonstrate our attempts to overcome them.

BlueJeans connection: https://bluejeans.com/321085255<https://gcc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbluejeans.com%2F321085255&data=02%7C01%7C%7C686aeba655c74eadccab08d6a97e9339%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C0%7C636882758430863257&sdata=WL5Eg28pa3wGozlwYeaBuTPImEzkPk6FCizLc6rh8bg%3D&reserved=0>

Raza, Vincent, Carlota


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