Past Events
| Event | Date | Summary |
| Don Scipione (ACMEX) | Tue. April 27th, 2021 11:30 am-12:30 pm |
Nuclear Levels as Analyzers of High Energy Interactions The theme of the talk is measurement, and how a clever experiment can eliminate the need for complex, model-dependent analysis. My thesis demonstrated the ability of using the excitation of Carbon to its first excited state as a target to select diffractive high energy interactions. In this talk, I will describe unpublished results from an experiment performed at Brookhaven National Laboratory where this technique was used to study properties of the A1 meson, a diffractively produced excited state of the pion. The results are in (three sigma) tension with the Particle Data Group’s estimate for the A1 mass. |
| Clara Murgui (Caltech) | Tue. April 20th, 2021 11:30 am-12:30 pm |
Flavour Anomalies: Lepton-Quark Unification at the TeV scale Deviations from the standard model predictions in the semileptonic decays of the B mesons have been reported by the LHCb and the B-factories over the last decade. Among them, strikingly, a deviation of 3.1 sigma in one of the cleanest observables, R(K), was recently announced by the LHCb. In this talk we review the status of these so-called flavour anomalies in the light of the data at face value and the upcoming experimental measurements. We present the simplest theory where one can understand the unification of matter (quarks and leptons) and show how these anomalies can be naturally accommodated in its context and discuss what are their implications regarding other predictions. |
| Alexis Plascencia (CWRU) | Tue. April 13th, 2021 10:30 am-11:30 am |
New Forces: Dark Matter, Electric Dipole Moments and the Baryon Asymmetry of the Universe Abstract: I will discuss minimal gauge extensions of the Standard Model where a new sector is predicted from the cancellation of gauge anomalies. As part of this new sector, there is a dark matter candidate and new sources of CP violation. I will discuss the dark matter phenomenology and the prediction of large electric dipole moments (EDMs) for the electron and the neutron. I will also discuss how to address the baryon asymmetry of the Universe.
Host: Pavel Fileviez Perez |
| Benjamin Grinstein (UCSD) | Tue. April 6th, 2021 12:30 pm-1:30 pm |
Special time 12:30 pm ET!! The Neutron Decay Anomaly: how it may be a window to new Physics In this talk I will first review a long-standing discrepancy between the neutron lifetime as measured in beam and in bottle experiments. If this discrepancy is not due to a systematic error, it may be due to novel mechanisms for neutron transmutation into new, as yet unknown elementary particles. These particles would be electrically neutral, or so-called “dark”. We will explain several scenarios for the possibility of neutron transmutation into dark particles. For example, |
| Delilah Gates (Harvard) | Tue. March 30th, 2021 11:30 am-12:30 pm |
Photon Emission from Circular Equatorial Orbiters around Kerr Black Holes We consider monochromatic and isotropic photon emission from circular equatorial Kerr orbiters. We calculate the critical curve delineating the region of photon escape from that of photon capture in each emitter’s sky, allowing us to derive analytic expressions for the photon escape probability and the redshift-dependent total flux collected on the celestial sphere as a function of emission radius and black hole parameters. This critical curve generalizes to finite orbital radius the usual Kerr critical curve and displays interesting features in the limit of high spin. |
| Hazel Mak (Brown University) | Tue. March 23rd, 2021 11:30 am-12:30 pm |
On 1D, N = 4 Supersymmetric Sachdev-Ye-Kitaev (SYK) Models Proposals are made to describe 1D, N = 4 supersymmetrical systems that extend S-Y-K models by compactifying from 4D, N = 1 supersymmetric Lagrangians involving chiral, vector, and tensor supermultiplets. The coupling constants in the superfield Lagrangians are arbitrary, and can be chosen to be Gaussian random. In that case, these 1D, N = 4 supersymmetric S-Y-K models would exhibit Wishart-Laguerre randomness, which share the same feature among 1D, N = 1 and N = 2 models in literature. One difference though, is our models contain dynamical bosons. |
| No Seminar | Tue. March 16th, 2021 11:30 am-12:30 pm |
No classes or seminars |
| Tim Tait (UC Irvine) | Tue. March 9th, 2021 11:30 am-12:30 pm |
An Early Period of QCD Confinement for Fun and Profit Abstract: I’ll discuss the possibility that QCD, the SU(3) encapsulating the strong nuclear force in the Standard Model, undergoes a period in the early history of the Universe in which it confines with a much larger confinement scale than is observed today. I’ll talk about the mechanics of how one can realize such a phenomenon, what the Universe would look like during this period and phenomenological implications, and potential applications to realize the observed baryon asymmetry or a modified picture for dark matter freeze out. For information about the speaker see this link Host: Pavel Fileviez Perez |
| Ozenc Gungor (CWRU) | Tue. March 2nd, 2021 11:30 am-12:30 pm |
A Classical, Non-Singular Bounce Bouncing cosmological models offer a viable alternative to Big-Bang cosmology and have gained recent attention. In a bouncing cosmology, the universe is initially contracting towards a minimum size before expanding. Such cosmological models are geodesically complete by construction and offer simple solutions to problems such as the Horizon problem. I will present a model that realizes such a cosmology and discuss its analytical and numerical properties. I will also discuss ongoing work on the stability of cosmological perturbations and possible future directions. Host: Glenn Starkman Zoom meeting ID: 999 3023 4812 |
| Erik Shirokoff (UChicago) | Tue. February 23rd, 2021 11:30 am-12:30 pm |
Line Intensity Mapping at millimeter wavelengths with on-chip spectrometers Recent advances in superconducting technology have enabled dramatic improvements in the sensitivity of millimeter and sub-millimeter wavelength instruments in the last decade and helped to usher in the era of precision cosmology. The next frontier is intensity mapping: using large arrays of spectrometers to build a 3D model of the emission from galaxies, with the ability to measure the star formation history throughout the epoch of reionization and to significantly constrain extensions to contemporary cosmology and inflation. The key to this technology are superconducting detectors and the microwave readout required to populate dense focal planes. |
| Shubham Maheshwari (Groningen) | Tue. February 16th, 2021 11:30 am-12:30 pm |
Stable, ghost-free solutions in UV non-local gravity I consider higher derivative, UV modifications to GR. In particular, I will focus on a specific kind of string theory-inspired higher derivative gravity where one includes derivatives to all orders in the action. First, I will discuss how such a non-local theory of gravity admits stable, non-singular bouncing solutions in the absence of matter. Moreover, around this bouncing background, there exists only one propagating (and ghost-free) scalar mode, and no vector or tensor modes. Next, I will discuss the general analysis of scalar-vector-tensor perturbations in non-local gravity – in particular, |
| Tanguy Grall (Cambridge) | Tue. February 9th, 2021 11:30 am-12:30 pm |
The Cosmological Phonon: Symmetries on Sub-Horizon Scales Curvature perturbations during inflation, which seed anisotropies in the CMB, can be described as phonons propagating on the inflationary background. Indeed the spacetime expansion breaks spontaneously time diffeomorphisms and Lorentz boost invariance generating such phonon-like behaviour. This representation is at the heart of the construction of the Effective Field Theory (EFT) of inflation. In this talk I will present an algebraic classification of the possible symmetries of a shift-symmetric scalar that is assumed to non-linearly realise Lorentz boosts. Such theories include for instance scalar modes in the EFT of inflation on sub-horizon scales, |