James Wells (UM): Nuclear Reactors, Nuclear Weapons, Neutrinos and NonproliferationJames Wells (UM) | 9/8/2023
This talk has two goals. One is to introduce some of the technical issues associated with nuclear reactors and concerns of proliferation of fissile materials that can be used to construct a nuclear weapon. Examples are discussed, including reactor fuel issues and possible neutrino monitoring of nuclear reactors. The second goal, which is connected to the first, is to describe the current landscape in the dangerous resurgence of nuclear weapons, most especially in North Korea. Emphasis will be on science and technology's role in creating the threats and possibly mitigating them.
David Poland (Yale): Bootstrapping the CFT Landscape | 9/29/2023
From critical phenomena to quantum gravity, conformal field theories (CFTs) describe the universal scale-invariant structures that lie at the heart of theoretical physics. The conformal bootstrap is the powerful idea, dating back to the 70’s, that one can use fundamental consistency conditions to constrain, solve, and map out the space ofconformal field theories. In this talk I will describe recent progress in using the conformal bootstrap to perform precise calculations and chart the landscape of 3d CFTs involving interacting scalars, fermions, and gauge fields.
Rouven Essig (Stony Brook): Progress & Challenges for Direct-Detection of Sub-GeV Dark Matter | 10/06/2023
The search for dark matter with masses between meV-to-GeV has seen tremendous theoretical and experimental progress in the past few years. I will provide an overview of some of this progress. I will mention recent results from SENSEI, a Skipper-CCD-based experiment that is sensitive to (halo) dark matter scattering off electrons for masses larger than ~1 MeV. I will highlight how such detectors can, however, also probe sub-MeV dark matter masses by searching for the component of dark matter that is boosted to higher energies from scattering in the Sun. In particular, future detectors with larger exposures could probe the entire “freeze-in” benchmark model down to keV masses. I will also discuss some challenges for direct detection, in particular, novel low-energy backgrounds. I will introduce a new detector concept, the “dual-sided CCD”, which could help with distinguishing some of these backgrounds.
Anastasia Volovich (Brown): Recent developments in N=4 Yang-Mills Amplitudes | 10/20/2023
Please note this event has been CANCELLED
The most important experimental probes of fundamental physics involve the scattering of elementary particles. Over the years we have seen significant progress in understanding the properties of scattering amplitudes and in our ability to carry out new computations both for theoretical and phenomenological purposes. I will overview some recent developments in N=4 Yang-Mills amplitudes.
Jnan Maharana (Institute of Physics, Bhubaneswar): Analyticity properties of scatteing amplitude in a theory with a compactified spatial dimension | 10/26/2023
NN Khuri, in 1995, considered a potential model where one spatial dimension was compactified. He adopted Green function method, which has been used for case of noncompact potential model, to study analyticity property
of forward amplitude and showed it violates dispersion relation (in case of noncompact potential model dispersionrelation had been proved in 1950's). If Khuri's result were valid in relativistic QFT it will have serious consequences (for example proof of Frossart bound will not be valid). Andre Martin asked me to look at analyticity of amplitude for a theory with compactified spatial dimension. I studied analyticity for such a theory in the framework of general field theory without adopting any specific model. I have proved two results (i) Forward dispesion relation is valid in relativistic QFT for a massive scalar field theory with a compact spatial dimention. Thus Khiri's result for potential scattering does not hold good for relativistic QFT. (ii) I have gone further; I proved nonforward dispersion relation. Thus Ihave gone beyond Khuri.
Sameer Murthy (King's College London/IAS): New attractors for the black hole index | 10/27/2023
The count of black hole microstates is typically obtained from a supersymmetric index in weakly coupled string theory. I will discuss the index in the strongly coupled theory, as a functional integral in N=2 supergravity in asymptotically flat space. The saddle-points of this index are given by supersymmetric "finite-temperature" rotating geometries. I will discuss a new version of the attractor mechanism obeyed by these geometries: the scalar fields at the poles of the Euclidean horizon as well as the free energy of the black hole get attracted to values that depend only on the charges and are independent of the asymptotic moduli and temperature.
Nathaniel Craig (UCSB): The Geometry of Electroweak Symmetry Breaking | 11/10/2023
Effective field theories (EFTs) suffer from a vast redundancy of description, reminiscent of coordinate invariance, that lends itself to a geometric treatment. In this talk I’ll survey recently-developed geometric insights into EFTs of the Standard Model Higgs sector, including invariant distinctions between possible EFTs of the Higgs boson, a new understanding of the connection between EFT geometry and observables, and generalizations of Riemannian field space geometry that encode information about analyticity and unitarity of the EFT. These developments are relevant to ongoing searches at the LHC and sharpen an open question for future colliders: is electroweak symmetry linearly realized by the known particles of the Standard Model?
Ofer Aharony (Weizmann/IAS): Correlation functions in TT*-deformed conformal field theories | 11/17/2023
I will begin by reviewing the movitations for studying the TT* deformation of two dimensional field theories, the original formulation of this deformation, and its formulation in terms of Jackiw-Teitelboim gravity. Then I will discuss how to compute correlation functions of local operators using this formulation, in which the position of the operators is defined using the dynamical coordinates of the formalism. I will focus on the large-momentum behavior of the two-point function when the undeformed theory is a conformal field theory. The main result (based on 2304.14091) is that for momentum q it is given by |q|^{-q^2 t/\pi}, where t is the deformation parameter. Interestingly, the sign of the exponent is different than previous computations which resummed the small momentum expansion. The decay at large momentum manifests the non-locality of the theory, which also appears through the fact that operators with different momentum require a different multiplicative renormalization, and that the large-momentum behavior of the correlation function on the torus is different from the behavior mentioned above on the plane.
