High Energy Physics Seminar next week - Romano

[HECAP - Margherita Di Giovannantonio]

*_HIGH ENERGY PHYSICS SEMINARS_*
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*Tuesday, 19 May *2026, at *16:00* - *_Euler Lecture 
Hall_***-*https://indico.ictp.it/event/11315/*


Marcello Romano (IPhT, Saclay)


*“Positivity With Long-Range Interactions"*
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_Abstract_

Long-range interactions, mediated for instance by photons and/or 
gravitons, force exclusive S-matrix elements to vanish in D=4 flat 
space-time, due to infrared divergences. This poses a challenge to 
programs, such as positivity and S-matrix bootstrap, that directly rely 
on the properties of 2-to-2 amplitudes. In this talk, I will introduce 
stripped amplitudes as IR-finite, analytic, crossing-symmetric, and 
Regge-behaved avatars of standard amplitudes, associated with a physical 
detector scale \Lambda. In the regime in which the latter is taken 
exponentially small than all other scales, they also satisfy a form of 
unitarity, allowing to derive IR-finite positivity bounds on EFTs, in 
presence of long-range interactions.

To attend via _*Zoom*_, please *_register_* here:
https://zoom.us/meeting/register/fdVkXNbzRmaMiR12z8F3sg