2020 Fall Seminar List

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== Spring 2020 LeCosPA Cosmology and Particle Astrophysics Seminars ==

Location : Room 7S1, LeCosPA center, NTU
if participants more than 20, we will change the lecture room from 7S1 to Room 7W3


Time : 11:00 am - 12:00 am, Monday

Organizers : Naoki Watamura; TsungChe Liu


Date Name Title Affiliation File
Oct./19
PhD. Shubham Maheshwari
Stable, ghost-free solutions in UV non-local gravity
abstract
University of Groningen, Netherland
Nov.30
Prof. Benjamin L'Huillier
Constraining Cosmology with the Large-Scale Structures
abstract: Despite great predictive power and its successes in the last decades, the concordance LCDM cosmological model suffers from both observational (H0 tension, ....) and theoretical issues (nature of dark energy, dark matter, inflation,…). Therefore, it is important to further test the model and its underlying hypotheses. In this talk, I will discuss how the study of the large scale structures can help shed light on some fundamental questions such as the nature of dark energy, gravity, or the early Universe, in the context of a new generation of survey such as Euclid, DESI, or LSST. I will focus on two different aspects: (i) modeling the nonlinear regime of structure formation through N-body simulations, in particular beyond LCDM, and (ii) applying advanced statistics, in particular model-independent methods, to state-of-the-art cosmological data to test different aspects of the concordance such as the metric, gravity, or the nature of dark energy.
Yonsei University, Korea
Dec.7
Dr. Yen-Yung Chang
Quantum information science for next generation dark matter search
abstract: Dark matter (DM) is one of the few outstanding questions in fundamental physics that are well-defined without theoretical aesthetics. Unambiguous observations in direct detection experiments, or an efficient parameter space removal, are the keys to theoretical development as well as motivating future large-scale experiments. I will begin by discussing the rising interests in sub-GeV DM models, which are well motivated but relatively underexplored due to previous technological limitations. I will then use our latest results in SuperCDMS beyond-SNOLAB R&D to explain the foreseeable challenges to an ultimate experiment for probing the entire particle DM mass spectrum. Motivated by these challenges, as well as developments in cutting-edge quantum sensing techniques, I will introduce our work in applying superconducting micro-resonators (Kinetic Inductance Detector) as an promising approach for future large-scale ultra-low-threshold experiments. I will also share the ongoing R&D for quantum-noise-limited parametric amplifiers at JPL, cryogenic radiation control for quantum devices, and target materials beyond semiconductors. I will conclude the talk with the implications, future prospects, and our plan toward probing the complete particle DM parameter space with quantum sensing technology. 


Caltech/JPL File:201206 quantum sensing for DM.pdf
Dec.14
Prof. [speaker speaker]
title
abstract
Affiliation
Dec.21
Hsu-Wen Chiang
Modification to the Hawking temperature of a dynamical black hole by a flow-induced supertranslation, or could microsoft save the day?
One interesting proposal to solve the black hole information loss paradox without modifying either general relativity or quantum field theory, is the soft hair, a diffeomorphism charge that records the anisotropic radiation in the asymptotic region. This proposal, however, has been challenged, given that away from the source the soft hair behaves as a coordinate transformation that forms an Abelian group, thus unable to store any information. To maintain the spirit of the soft hair but circumvent these obstacles, we consider Hawking radiation as a probe sensitive to the entire history of the black hole evaporation, where the soft hairs on the horizon are induced by the absorption of a null anisotropic flow, generalizing the shock wave considered by Hawking, Perry and Strominger. To do so we introduce two different time-dependent extensions of the diffeomorphism associated with the soft hair, where one is the backreaction of the anisotropic null flow, and the other is a coordinate transformation that produces the Unruh effect and a Doppler shift to the Hawking spectrum. Together,they form an exact BMS charge generator on the entire manifold (a realization of the interpolation between the BMS group on the null asymptote to the BMS group on the horizon) that allows the nonperturbative analysis of the black hole horizon, whose surface gravity, i.e. the Hawking temperature, is found to be modified. The modification depends on an exponential average of the anisotropy of the null flow with a decay rate of 4M, suggesting the emergence of a new 2-D degree of freedom on the horizon, which could be a way out of the information loss paradox.
LeCosPA, NTU
Dec.28
Hsu-Wen Chiang
Modification to the Hawking temperature of a dynamical black hole by a flow-induced supertranslation, or could microsoft save the day? Part 2
One interesting proposal to solve the black hole information loss paradox without modifying either general relativity or quantum field theory, is the soft hair, a diffeomorphism charge that records the anisotropic radiation in the asymptotic region. This proposal, however, has been challenged, given that away from the source the soft hair behaves as a coordinate transformation that forms an Abelian group, thus unable to store any information. To maintain the spirit of the soft hair but circumvent these obstacles, we consider Hawking radiation as a probe sensitive to the entire history of the black hole evaporation, where the soft hairs on the horizon are induced by the absorption of a null anisotropic flow, generalizing the shock wave considered by Hawking, Perry and Strominger. To do so we introduce two different time-dependent extensions of the diffeomorphism associated with the soft hair, where one is the backreaction of the anisotropic null flow, and the other is a coordinate transformation that produces the Unruh effect and a Doppler shift to the Hawking spectrum. Together,they form an exact BMS charge generator on the entire manifold (a realization of the interpolation between the BMS group on the null asymptote to the BMS group on the horizon) that allows the nonperturbative analysis of the black hole horizon, whose surface gravity, i.e. the Hawking temperature, is found to be modified. The modification depends on an exponential average of the anisotropy of the null flow with a decay rate of 4M, suggesting the emergence of a new 2-D degree of freedom on the horizon, which could be a way out of the information loss paradox.
LeCosPA, NTU


Jan.11
Prof. Masahiro Hotta
Generalized partners in quantum field theory
Black hole evaporation causes the information loss problem. Nobody knows what carries initial quantum information after the last burst of black holes even if unitarity is preserved. After the evaporation, the density of Hawking radiation decreases in time. In the regime, quantum gravity and matter interaction may be neglected. If so, low-energy free quantum fields carry whole of the initial quantum information under the unitary evolution. In this perspective, it is quite cruicial to explore what kinds of information storage are possible in free quantum field theory. In this talk, it will be shown that new information storages like generalized partners and quantum information capsules are able to share complete quantum information. I will also provide application of the generalized partners to expanding universes and moving mirror models.
Tohoku University, Japan


Mar. 8
Prof. Daniel Baumann
TBA
TBA
University of Amsterdam, Nederland
Mar. 15
Prof. [speaker speaker]
title
abstract
Affiliation




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