[Theory-seminars] Seminars next week

[Carlota Andres Casas]

Dear all,

Here is a reminder for next week theory seminars:

Theory seminar:
Monday, March 25th, 1:00PM, Room L102

Alessandro Baroni (U of South Carolina), "Finite-volume formalism for two-hadron states with one current insertion."

BlueJeans connection: https://bluejeans.com/321085255<https://gcc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbluejeans.com%2F321085255&data=02%7C01%7C%7Cddc07927d5ae4438e2d108d6aef9fce1%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C0%7C636888786047364755&sdata=LWJG3uODsM96mHodX0ABnNKO8kZUENL8oy8AhCAzJic%3D&reserved=0>

Abstract:
In this talk, I will present a recently proposed finite-volume formalism that will allow to obtain structural information of resonances and bound states coupling to two-hadron scattering states. I will place emphasis on a new class of observables that are experimentally inaccessible but can be accessed via lattice QCD. In particular, after introducing the problem, I will sketch the derivation of the result that relates finite-volume two-body matrix elements with one current insertion to the corresponding infinite volume scattering amplitude.



Cake seminar:
Wednesday, March 27th, 1:00PM, Room F224-F225

Felipe Ortega (William and Mary), "Two-hadron form-factors: 2+J ⟶ 2  Finite Volume effects"

BlueJeans connection: https://bluejeans.com/195615763

Abstract:
To study the underlying structure of hadronic resonances non-perturbative tools, like Lattice QCD (LQCD), play an essential role given the nature of QCD at low energies. It has been shown that LQCD computational results are robust, in particular that the systematics associated with finite lattice spacing or lattice volume are under control, for various observables, for example the low-lying spectrum of the theory. Nonetheless, in order to study properties of the resonances, like electromagnetic or axial Form Factors (FF), analysis so far had been carried out at unphysical high quark masses such that the studied state is stable, and finite volume corrections become negligible. In this talk I will give a short review about the formalism developed in [arXiv:1509.08507] to constrain FF of resonances/bound states of two-body systems. After that, I will focus on the work done in [arXiv:1812.10504], which is a Lorentz covariant version of the previously proposed formalism. This formalism is an all orders perturbative mapping between the finite-volume matrix elements obtained in LQCD and the aforementioned amplitudes. Then, I will outline an efficient procedure for evaluating a new kind of finite-volume functions needed to implement the formalism. In order to have a rigorous constraint of the dynamical behavior of resonances, the precise analytic structure of this function must be known. I will discuss the origin and characteristics of the singularities featured in it. I will conclude with an outlook of further steps and calculations needed in order to extract resonant FF from the lattice.



Raza, Vincent, Carlota
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