[Theory-seminars] Addendum: farewell for Ishara Fernando next week

[Astrid Hiller Blin]

Dear all,

Unfortunately we had no chance for a farewell before Ishara left, but
luckily he can join us next Monday before the theory seminar (details
below).

Please join us at *12:40* on Monday, October 5, to thank him and wish him
good luck in his new position at Fermilab!

Best wishes,
Astrid, Christos, Filippo and Miguel


On Fri, Oct 2, 2020 at 2:23 PM Astrid Hiller Blin <ahblin at jlab.org> wrote:

> Dear all,
>
> Here is a reminder of next week's theory seminar:
>
> *Theory seminar*
> Monday October 5, 1:00 PM
>
> *Gustavo Guerrero Navarro* (University of Valencia) will talk about "Pion
> electro- and photoproduction on nucleons with explicit Delta(1232) in
> covariant Chiral Perturbation Theory".
>
> *Abstract:*
> Recent studies have been made on pion electro- and photoproduction off
> nucleons close to threshold with the explicit inclusion of the Delta(1232)
> in full relativistic Chiral Perturbation Theory at O(p^3). The relevant low
> energy constants (LECs) were fixed by fitting the available experimental
> data with the theoretical model.
> The Delta(1232) inclusion in the model improves the global agreement with
> data in the neutral and charged pion photoproduction. Furthermore, when we
> extend the fitting procedure to the electroproduction case, the model
> remains consistent with data, also allowing us to explore wider kinematical
> regions being important to better determine the LECs.
> Moreover, we have found a best conciliation near threshold with the LECs
> that were fixed by other processes, like pion-nucleon scattering, when we
> consider the isospin breaking at the one-loop amplitudes. We reproduce
> accordingly the angular distributions and the center of mass energy
> dependence up to ~60 MeV above the threshold for all the observables.
> Finally, I show a brief study for the uncertainties in the fitted LECs
> from three main sources of error: The systematical errors in the
> theoretical model, the statistical errors from data, and the error bars
> from the non-fitting low-energy-constants. These LECs could be incorporated
> in the study of other precision processes involving neutrino-nucleus
> interactions or pion photoproduction on nucleus.
>
> Bluejeans connection: https://bluejeans.com/801786278
> <https://urldefense.proofpoint.com/v2/url?u=https-3A__bluejeans.com_801786278&d=DwMFaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=AIMSQQ81YDyrZuJNGks2qw&m=aT_3J5jjiFmHtFXffqbfPqEY_A73NEWw2ebyFyL_eCA&s=YNm3qgT5e8sJgKfZ9vFA_w--imuXwmeAjg0C4AslLwg&e=>
>
> Best wishes,
> Astrid, Christos, Filippo, Miguel
>
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