High Energy Physics Seminars next week - Parameswaran and Loladze - venue: Euler LH

[HECAP - Margherita Di Giovannantonio]

*_HIGH ENERGY PHYSICS SEMINARS_*
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*Tuesday, 21 April *2026, at *16:00* - *_Euler Lecture 
Hall_***-*https://indico.ictp.it/event/11322/*

Ajith Parameswaran (ICTS, TIFR - Bangalore)


*“Lensing of Gravitational Waves: A New Tool for Cosmology"*
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_Abstract_

Next-generation gravitational-wave (GW) detectors are expected to detect 
millions of binary black hole mergers during their operation period. A 
small fraction (∼0.1–1%) of them will be strongly lensed by intervening 
galaxies and clusters, producing multiple copies of the GW signals. The 
expected number of lensed events and the distribution of the time delay 
between lensed images will depend on the cosmological parameters and the 
large scale structure in the universe. Thus, future observations of 
strongly lensed GWs will provide a new way of probing cosmology, 
including new measurements of cosmological parameters, the distribution 
of dark matter halos and the nature of dark matter. This talk will 
introduce the exciting prospects of GW lensing.

To attend via _*Zoom*_, please *_register_* here:
https://zoom.us/meeting/register/MsiZmY6-Q3SdaZbepRgYQQ


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*Thursday, 23 April *2026, at *16:00* - *_Euler Lecture 
Hall_***-*https://indico.ictp.it/event/11302/*

Vazha Loladze (University of Oxford)


*“Dynamics of the Fermion-Rotor System"*
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_Abstract_

In this talk, I will examine the dynamics of the fermion–rotor system, 
originally introduced by Polchinski as a toy model for monopole–fermion 
scattering. Despite its simplicity, the system is surprisingly subtle, 
with ingoing and outgoing fermion fields carrying different quantum 
numbers. I will show that the rotor acts as a twist operator in the 
low-energy theory, changing the quantum numbers of excitations that have 
previously passed through the origin to ensure scattering consistent 
with all symmetries, thereby resolving the long-standing Unitarity puzzle.
I will then discuss generalizations of this setup with multiple rotors 
and unequal charges, and demonstrate how the system can be viewed as a 
UV-completion of boundary states for chiral theories, establishing a 
connection to the boundary conformal field theory based proposal for 
resolving the puzzle.

To attend via _*Zoom*_, please *_register_* here:
https://zoom.us/meeting/register/k_jOSKXvTQKq0SGVCmf1iQ