REMINDER - High Energy Physics Seminars this week (Uwabo and Raju)

[HECAP - Margherita Di Giovannantonio]

*_HIGH ENERGY PHYSICS SEMINARS_**__*


*Tuesday, 20 May* 2025, at *16:00* - *Luigi Stasi Seminar Room **- 
*https://indico.ictp.it/event/10984/
**

**

Michiru Uwabo (Ochanomizu University/IBS)


*“Formation of Defects Associated with both Spontaneous and Explicit 
Symmetry Breaking"*

_Abstract_
We discuss formation of cosmic strings associated with a spontaneously 
broken approximate U(1) symmetry by performing classical 
field-theoretical simulations. An original U(1) symmetry is explicitly 
broken down to its subgroup Z_N even before spontaneous breaking takes 
place. We estimate the ratio of explicit breaking to that of spontaneous 
breaking for which topological defects for N=1 and N=2 are formed. For 
N=1, a cosmic string attached to a single domain wall can be formed when 
the amount of the explicit breaking is 3 orders of magnitude smaller 
than that of the spontaneous breaking. For N=2, no matter how large the 
explicit breaking is, domain walls are inevitably formed as long as the 
temperature of the Universe is high enough to restore Z_2 symmetry. In 
that case, cosmic strings are also inevitably formed as long as the 
amount of the explicit breaking is smaller than that of the spontaneous 
breaking.


To join via Zoom:
https://zoom.us/j/92441776557

Meeting ID:  924 4177 6557

Passcode: 175124


*******


*/!!! Please note unusual venue !!!/*

*Thursday, 22 May *2025, at*16:00*  - *Euler Lecture Hall* - 
https://indico.ictp.it/event/11033/



Suvrat Raju (Tata Institute of Fundamental Research, ICTS)


* “Cosmological Correlators in Gravitationally-Constrained de Sitter 
States"*
_
__Abstract_
We study perturbative cosmological correlators in wavefunctionals which 
solve the Wheeler-DeWitt equation in asymptotically de Sitter spacetimes 
and were constructed in arxiv:2303.16315. Even in the G_N \rightarrow 0 
limit, it is necessary to impose the gravitational Gauss law, which 
forces states to be de Sitter invariant. We set up Feynman rules for 
computing cosmological correlators in such states. We enumerate some 
necessary (but not sufficient) conditions that must be imposed on states 
and observables to avoid group-volume divergences. We provide sample 
computations to show that such cosmological correlators can be 
nontrivial even when the Hartle-Hawking wavefunction is Gaussian. We 
show that, in the presence of a heavy background state, it is possible 
to construct a class of state-dependent relational observables that 
approximate correlators in the Hartle-Hawking state.



To join via Zoom (please note audio/video may have lower resolution than 
usual):
https://zoom.us/j/97510670835

Meeting ID  975 1067 0835

Passcode: 216259