High Energy Physics Seminars next week - Zan and Porrati

[HECAP - Margherita Di Giovannantonio]

*_HIGH ENERGY PHYSICS SEMINARS_**__*

*/!!Please note unusual venue for both seminars!!/*
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*Tuesday, 14 April *2026, at *16:00* - *_Lagrange Lecture 
Hall_***-*https://indico.ictp.it/event/11264/*

Bernardo ZAN (University of Genova)


*“Phases of Some 2D Abelian Gauge Theories and Symmetric Mass Generation"*
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_Abstract_

I will discuss two-dimensional theories that are coupled in a chiral way 
to a U(1) global symmetry, meaning that we cannot deform the theory by 
adding a mass term. Does it mean that we’re bound to have gapless 
fermions in the IR? The answer is negative: despite mass terms not being 
allowed, non-perturbative effects can still gap out the fermions. This 
is the phenomenon of symmetric mass generation. I will discuss a way of 
obtaining symmetric mass generation in some models with two Dirac fermions.
As a warm up, I will also discuss a few non-chiral 2d abelian gauge 
theories. Then I will add some scalar fields to our theory of interest 
and gauge some U(1)’s to show how a symmetry preserving deformation will 
eventually gap out the theory, showing therefore a clean mechanism to 
obtain symmetric mass generation.


To attend via _*Zoom*_, please *_register_* here:
https://zoom.us/meeting/register/Bpit-7vSTwKQSC8W4Dz0PA


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*Thursday, 16 April *2026, at *16:00* - *_Euler Lecture 
Hall_***-*https://indico.ictp.it/event/11301/*

Massimo Porrati (New York University)


*“Supertranslations, Angular Momentum, and Covariance in 4D 
Asymptotically Flat Space"*
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_Abstract_

This talk reviews some aspects of the "angular momentum problem" in 
general relativity as well as of old and new results in the search for 
covariant and supertranslation-invariant formulas for the flux of 
angular momentum and other Lorentz charges in asymptotically flat 
spacetimes. It addresses in particular three problems with all existing 
solutions:
1) Supertranslation-invariance and covariance imply invariance under 
spacetime translations;
2) the flux depends on redundant auxiliary degrees of freedom that 
cannot be set to zero in all Lorentz frames without breaking Lorentz 
covariance;
3) supertranslation-invariant Lorentz charges do not generate the 
transformations of the Bondi mass aspect implied by the isometries of 
the asymptotic metric.
The resolution of these problems leads to new, covariant formulas for 
the fluxes that make explicit the choice of reference frame underpinning 
seemingly unambiguous results presented in the current literature. This 
choice will be described in some detail and an elementary method for 
measuring the rotational part of the angular momentum aspect will be 
presented.

To attend via _*Zoom*_, please *_register_* here:
https://zoom.us/meeting/register/saA-11bfRBupGr3Zz6MvRQ