13 APR 2021
14:00 - 15:00

Abstract:

Recent developments on black holes have shown that a unitarity-compatible Page curve can be obtained from an ensemble-averaged semi-classical approximation. In this talk, we emphasize (1) that this peculiar manifestation of unitarity is not specific to black holes, and (2) that it can emerge from a single realization of an underlying unitary theory. To make things explicit, we consider a hard sphere gas leaking slowly from a small box into a bigger box. This is a quantum chaotic system in which we expect to see the Page curve in the full unitary description, while semi-classically, eigenstates are expected to behave as though they live in Berry's ensemble. We reproduce the unitarity-compatible Page curve of this system, semi-classically. The computation has structural parallels to replica wormholes, relies crucially on ensemble averaging at each epoch, and reveals the interplay between the multiple time-scales in the problem. Working with the ensemble averaged state rather than the entanglement entropy, we can also engineer an information "paradox". Our system provides a concrete example in which the ensemble underlying the semi-classical Page curve is an ergodic proxy for a time average, and not an explicit average over many theories. The questions we address here are logically independent of the existence of horizons, so we expect that semi-classical gravity should also be viewed in a similar light.



Date: Tuesday, April 13th

2 p.m. - 3 p.m. (Tehran time)

Zoom. (click)

Meeting ID: 884 3079 2016

Passcode: 395721

14 APR 2021
16:30 - 17:30

The Eigenvalue Theorem is a basic result in computational algebraic geometry. It says that solving a zero-dimensional system of polynomial equations can be reduced to an eigenvalue problem in linear algebra. The name of Ludwig Stickelberger (1850-1936) is often attached to this theorem, yet papers that use his name never cite any of his papers. My lecture will explore the reasons for this. The answer involves a lovely trace formula in algebraic number theory and an algebra textbook published by Gunter Scheja and Uwe Storch in 1988.
To get more information about the colloquium, join to the following google group:
https://groups.google.com/g/ipm-math-colloquium

14 APR 2021
11:00 - 12:00

Abstract: We study the dynamics of electroweak phase transition in a simple extension of the Standard Model where the Higgs sector is extended by adding an $SU(2)_L$-mutiplet. By making random scans over the parameters of the model, we show that there are regions consistent with constraints from collider experiments and the requirement for a strong first-order electroweak phase transition which is needed for electroweak baryogenesis. Further, we also study the power spectrum of the gravitational waves which can be generated due to the first-order phase transitions. Observation of such gravitational waves, such as by future space-based gravitational wave detectors, could yield information that is complementary to collider and dark matter experiments.


Indico: https://indico.particles.ipm.ir/indico/event/408
https://meet.google.com/hkp-tout-qzi

14 APR 2021
13:30 - 15:00

Abstract:
Axions and Axion-like fields are popular in cosmology, both as the inflaton and as dark matter. Such fields can naturally condense into long-lived, spatially localized configurations (oscillons, axion stars etc). I will discuss conditions under which such solitons become effective antennas for electromagnetic radiation by converting axions to photons, which can lead to potential observational signatures. I will also discuss multimessenger signals: electromagnetic and gravitational wave emission from soliton collisions. Time permitting, I will digress to advertise a separate topic of CMB birefringence from a different type of soliton: string loops in ultralight-axions.
To join the seminar, please click on the following link

https://www.skyroom.online/ch/soa/weekly-seminar

Then click on the guest bottom to participate

15 APR 2021
11:00 - 13:00

Schubert Derivations are distinguished instances of Higher Order (or Hasse-Schmidt) derivations on exterior algebras [8], originally introduced to phrase Schubert Calculus for Grassmannians varieties, solely in terms of Leibniz rules and integration by parts. The purpose of the talk is showing their applications to find explicit vertex operators representations of Lie algebras of endomorphisms on exterior algebras and related spaces [1, 2, 3, 4], like the infinite wedge power (as in [9] and the bosonic Fock space (a polynomial ring in infinitely many indeterminates). This is related with some pioneering work done by Date, Jimbo, kashiwara and Miwa at the beginning of the Eighties [5]. The premises are the following two elementary observations: each vector space is a representation of the Lie algebra of its own endomorphisms and the r-th exterior power of a polynomial ring in one indeterminate is isomorphic to a polynomial ring in r indeterminates.
References
[1] O. Behzad, Hasse-Schmidt Derivations and Vertex Operators on Exterior Algebras. Ph.D. Thesis, IASBS, Zanjan, 2021;
[2] O. Behzad, A. Contiero, L. Gatto, R. Vidal Martins, Polynomial ring representation of endomorphisms of exterior powers. Collectanea Math., 2021 (to appear), ArXiv:2005.01154.pdf,
[3] O. Behzad, L. Gatto, Bosonic and Fermionic Representations of Endomorphisms of Exterior Algebras, Fundamenta Math. 2021 (to appear), ArXiv:2009.00479.pdf

Join Zoom Meeting
https://zoom.us/j/9299700405?pwd=VTM5OW53dWFkbjcxQXBBalhiNWc2dz09
Meeting ID: 929 970 0405
Passcode: 210406

15 APR 2021
11:00 - 12:05

Abstract: Very recently, the LHCb collaboration @ CERN and muon g-2 collaboration @ Fermilab have announced their results on the lepton flavor universality violation (LFUV) and muon magnetic dipole moment, which deviate from the SM theory predictions by 3.1 and 4.2 standard deviations, respectively. In this talk we address these results and talk about their meanings and possible scenarios to explain the observed deviations if they are confirmed.



http://meet.google.com/iys-ixfq-gwm

19 APR 2021
16:00 - 18:00

Theory of Conflictless Drama in Soviet Literature


https://www.skyroom.online/ch/ipmseminars/ipm-seminars-2021

User: biweeklyseminars
Pass: biweeklyseminars