hosted by: Janet Conrad
Joshua Spitz, University of Michigan
The Neutrino, Still Crazy (after all these years)
Abstract:
The MiniBooNE short-baseline neutrino experiment has recently reported a significant (4.5sigma) excess of electron-neutrino-like events in an originally muon-neutrino beam. This is arguably the most important existing hint of beyond standard model physics there is, and MiniBooNE is not alone in its anomalous observations of possible new neutrino mixing, as there may be indications from other experiments as well. This talk will discuss the recent MiniBooNE result, possible non-neutrino interpretations, and prospects for future accelerator-based measurements. In particular, Fermilab's Short-Baseline Neutrino (SBN) and the J-PARC Sterile Neutrino Search at the J-PARC Spallation Neutron Source (JSNS2) experiments will directly address these anomalies in the next few years.
Along with discussing the recent MiniBooNE results and introducing SBN and JSNS2, I will present the first measurement of the 236 MeV kaon decay-at-rest neutrino, recently performed with MiniBooNE, and prospects for follow-on high-precision measurements with JSNS2. The significance of this and future studies, in terms of elucidating both the neutrino-nucleus interaction and oscillations, will be emphasized.
If there is time, I will also describe a unique experiment based on "paleo-detectors" that could provide unprecedented sensitivity to changes in the cosmic ray flux over Gigayear-timescales, and therefore open a new window on the history of the Earth, the solar system, and even our galaxy. This idea, which relies on studying the imprints of atmospheric-neutrino-induced nuclear recoils in ancient minerals, could soon evolve into an actual experiment (since the technology exists).
hosted by: Bolek Wyslouch
Zhan Zhang, MIT
The Upgrade of the Alpha Magnetic Spectrometer (AMS) on the International Space Station
Abstract:
AMS is an LNS led high-energy particle physics experiment on the International Space Station (ISS) to study the origin of cosmic rays, the existence of dark matter and anti-matter. After nine years in space, AMS has collected over 160 billion cosmic rays and continues to provide unique insights into cosmic ray properties. The ISS lifetime has been extended to 2028 and beyond. I will present the recently completely upgrade of AMS to ensure its proper function for the lifetime of space station. This upgrade requires six astronauts engaged in four separate Extra-Vehicular Activities (EVA), and this were considered the most challenging space activities ever performed by NASA. I led the MIT effort for this upgrade and will summarize the four year effort.
hosted by: Philip Harris
Markus Klute, MIT
Recent Results from the LHC
Abstract:
Over the course of Run 2 of the LHC, from 2015 to 2018, the ATLAS and CMS experiments each collected 140 inverse femtobarn of proton-proton collision data for analysis. The data provides the basis for a stream of new results, from the exploration of the Higgs boson and searches for new physics to the study of heavy-ion collisions. In this talk, I will give an update on activities at CERN and the LHC and report on recent results. Emphasis will be given to showing new evidence for Higgs couplings to muons.
hosted by: Gunther Roland
Laura Fabbietti, Technical University of Munich and ALICE
Renaissance of Nuclear Physics at the LHC
Abstract:
hosted by: Daniel Harlow
Please Note: This is Tuesday at 4:00PM
David Tong, University of Cambridge
Chiral Fermions
Abstract:
Chiral quantum field theories have the property that left-handed and right-handed fermions experience different forces. The most prominent example is the Standard Model. These theories exhibit a number of interesting bugs and features. A feature is that the fermions seemingly cannot get a mass without breaking the gauge symmetry, a role played in the Standard Model by the Higgs. A closely related bug is that these theories have so far resisted attempts to formulate them on the lattice.
I'll describe a number of recent advances in understanding both bugs and features.
hosted by:
Abstract:
hosted by: Daniel Harlow
Alexander Zhiboedov, CERN
Event Shapes, the Light-Ray OPE and Superconvergence
Abstract:
I will describe recent progress in understanding event shapes in conformal field theories.
Familiar from the description of hadronic events at colliders, these observables are computed by matrix elements of the so-called light-ray operators. Characterizing the light-ray operators in a nonperturbative setting poses many theoretical challenges. I will describe some of the recently developed tools to perform computations of conformal event shapes and illustrate them using the conformal cousin of QCD, namely N=4 SYM. Finally, I will explain how via holography some of the basic properties of conformal event shapes lead to nontrivial sum rules obeyed by possible UV completions of general relativity.
hosted by: Or Hen/Richard Milner
Rolf Ent, JLab
The Quest to Understand the Fundamental Structure of Nuclear Matter – Outlook to an Electron-Ion Collider
Abstract:
Nuclear matter is made of quarks that are bound by gluons that also bind themselves. Unlike with the more familiar atomic and molecular matter, the interactions and structures in nuclear matter are inextricably mixed up, and observed properties of nucleons and nuclei, such as mass & spin, emerge out of this complex system. In order to understand how the properties and structure of nuclear matter emerge from the dynamics of QCD, it is essential to image the gluons and quarks and their interactions (nuclear femtography). This program is initiated at the 12-GeV Upgraded Jefferson Lab, concentrating on imaging the valence-quark region. A new US-based facility, EIC or Electron-Ion Collider, with a versatile range of beam energies, polarizations, and species, as well as high luminosity, is required to precisely image the quarks and gluons and their interactions, to explore the new QCD frontier of strong color fields in nuclei – to understand how matter at its most fundamental level is made. The nuclear femtography science foreseen at and the status of the EIC will be presented.
hosted by: Philip Harris
Chris Tunnell, (Rice, Xenon)
XENON1T's Electronic-Recoil Excess, and how Fundamental Machine-Learning R&D May Help
Abstract:
Our XENON collaboration has been operating a series of ultra-radiopure experiments to probe tiny momentum transfers, which may arise from cosmogenic particles. Traditionally, we interpret our results in terms of WIMP dark matter, where our latest XENON1T experiment is the most sensitive such detector to date. However, the observable signal is a rate of either recoiling nuclei (e.g. WIMPs) or electrons, where such a model-agnostic approach means that any excess or discovery may have multiple interpretations if only using XENON data. Even though XENON is primarily designed for observing nuclear recoils, the unprecedentedly low-radioactivity gives sensitivity to any new physical phenomena that may present itself via electronic recoils. Using XENON1T data, we announced in June evidence (>3σ) of an electronic-recoil excess. Different interpretations of this excess were explored, ranging from new physics such as solar axions (3.5σ), a neutrino magnetic moment (3.2σ), or bosonic dark matter (3σ local, 4σ global), to detector effects such as tritium (3.2σ) or argon. This result cannot be interpreted in isolation as for some interpretations, for example, there is strong tension with stellar evaporation. Accordingly, these has been extensive interest in the literature (>126 papers) to find an explanation. I will review the field of dark-matter direct detection, present details on how XENON1T operated, provide details on this analysis, discuss interpretation attempts, and inform on how our new XENONnT experiment may provide the answers we crave.
As this was an excess in an energy spectrum and give the interest in "physics + ML" at MIT, depending on interest, I will also take time to describe the DIDACTS project that is an interdisciplinary team of researchers from physics, computer science, and electrical & computer engineering to rethink how we do reconstruction in particle experiments. Specifically, for difficult measurements that require a regression (i.e. predict an energy), what are the shortcomings of the state-of-the-art techniques? I will review how particle physics data is inherently graphical, and discuss how graphical convolutional neural networks can be used for regressions while opening up avenues to apply novel ML techniques such as graph learning to learn detector symmetries, or probabilistic graphical models for learning uncertainty. For a variety of data analysis challenges faced by most particle-physics experiments, I will draw connections to R&D in other fields that moves us closer to physics-constrained machine learning.
hosted by: Daniel Harlow
Monica Pate, Harvard University
Measuring Asymptotic Symmetries from Memory Effects at Particle Colliders
Abstract:
In recent years, the scattering problem in gauge and gravitational theories has been shown to admit a class of infinite-dimensional symmetries, known as asymptotic symmetries. The infinite number of constraints on scattering amplitudes implied by the symmetries are equivalent to quantum field theoretic soft theorems. As such, the pattern of soft radiation prescribed by soft theorems is a direct signature of the underlying asymptotic symmetries. An observable phenomenon that is sensitive to soft radiation is the memory effect, which characterizes the relative symmetry transformations of pairs of test charges induced by soft radiation. In short, the memory effect specifies how a configuration of soft radiation can be reconstructed from its distinct imprint on pairs of test charges. In this seminar, I will present a set of asymptotic symmetries that arise in classical non-Abelian gauge theory and their associated "color memory" effects. Then, I will discuss how these classical color memory effects are ubiquitous in high-energy processes that are modeled by the color glass condensate.
hosted by: Or Hen/Richard Milner
Areg Danagoulian, MIT
Arms Control Verification with Nuclear Resonances
Abstract:
Arms control treaties are not sufficient in and of themselves to neutralize the existential threat of the nuclear weapons. Technologies are necessary for verifying the authenticity of
the nuclear warheads undergoing dismantlement before counting them towards a treaty partner’s
obligation. We have developed two novel concepts which use observations of isotope specific nuclear
transitions to authenticate a warhead's fissile components. Most actinides such as uranium and plutonium exhibit
unique sets of nuclear resonances when interacting with eV neutrons. When measured, these resonances
produce isotope-specific features in the spectral data, thus creating an isotopic-geometric "fingerprint"
of an object. All information in these measurements is encrypted in the physical
domain in a manner that can amount to a physical zero-knowledge proof system. Using Monte Carlo
simulations and experimental proof-of-concept measurements these techniques are shown to reveal
no isotopic or geometric information about the weapon, while readily detecting hoaxing attempts.
The talk will discuss the policy context, the concept of the experimental techniques, along with results
from simulation and experimental measurements.
