Committee: Jesse Thaler, Chair ~ Daniel Harlow ~ Kerstin Perez ~ Philip Harris
hosted by: Phil Harris
Verena Martinez Outshoorn, UMass Amherst
Unlocking the Higgs Portal With Exotic Higgs Decays
Abstract: Following the discovery of the Higgs boson at the Large Hadron Collider (LHC), a major goal is to characterize the properties of this new particle. The Higgs itself is a potential portal to new physics, providing connections between the Standard Model of particle physics and new phenomena, such as signatures of dark matter. Searches for new decays of the Higgs boson will be described using data collected by the ATLAS experiment and future prospects will be discussed. The development of new electronics upgrades to allow for effective triggering and recording of Higgs bosons for the high luminosity upgrade of the LHC will also be presented.
time: 4:00 p.m.
place: Kolker Room (26-414)
(refreshments at 3:30 p.m.)
PRESIDENT'S DAY - No Talk this Week
hosted by: Jesse Thaler
Clifford Cheung, Caltech
Unification from Scattering Amplitudes
Abstract: Scattering amplitudes are fundamental observables that encode the dynamics of interacting particles. In this talk, I describe how to systematically construct these objects without reference to a Lagrangian or an underlying spacetime. The physics of real-world particles like gravitons, gluons, and pions are thus derived from the properties of amplitudes rather than vice versa. Remarkably, the expressions gleaned from this line of attack are marvelously simple, revealing new structures long hidden in plain sight. As an example, I describe how gravitons are in a very precise way equivalent to products of gluons---a fact with far-reaching theoretical and phenomenological applications. Lastly, I show how gravity serves as the "mother of all theories" whose amplitudes secretly unify, among others, all gluon and pion amplitudes.
time: 4:00 p.m.
place: Kolker Room (26-414)
(refreshments at 3:30 p.m.)
hosted by: Kerstin Perez
Marcelle Soares-Santos, Brandeis
Discovering the Optical Counterparts of Gravitational Wave Emitting Neutron Star Mergers for Cosmology
Abstract: Motivated by the exciting prospect of a new wealth of information arising from the first observations of gravitational and electromagnetic radiation from the same astrophysical phenomena, the Dark Energy Survey (DES) has established a search and discovery program for the optical transients associated with LIGO/Virgo events using the Dark Energy Camera (DECam). This talk presents the discovery of the optical transient associated with the neutron star merger GW170817 using DECam and discusses its implications for the emerging field of multi-messenger cosmology with gravitational waves and optical data.
time: 4:00 p.m.
place: Kolker Room (26-414)
(refreshments at 3:30 p.m.)
hosted by: Daniel Harlow
Kurt Hinterbichler, Case Western University
The Status of Long Range Modifications of Gravity
Abstract: We will review the problem of explaining the current acceleration of the universe, some of the various classes of proposals for addressing it with new long-range degrees of freedom, and the constraints imposed from recent observations of gravitational waves.
time: 4:00 p.m.
place: Kolker Room (26-414)
(refreshments at 3:30 p.m.)
hosted by: Phil Harris
Marta Verweij, Vanderbilt
The Inner Workings of the Quark-Gluon Plasma Studied with Highly Energetic Jets
Abstract: In collisions between relativistically accelerated lead ions a dense medium is formed: the quark-gluon plasma (QGP). These type of collisions are used to study matter in phases where quarks and gluons are no more confined into hadrons and where chiral symmetry is restored. Hard scattered partons are used to map out the properties of the QGP. As a parton passes through the QCD medium, induced energy loss from elastic and radiative interactions leads to a modification of the parton shower; this modification is used to deduce medium properties.
In this colloquium, jet measurements in heavy-ion collisions at the Large Hadron Collider are discussed. In particular the use of jet substructures to study specific properties of hot QCD matter will be presented.
time: 4:00 p.m.
place: Kolker Room (26-414)
(refreshments at 3:30 p.m.)
SPRING BREAK- No Talk this Week
hosted by: Kerstin Perez
Zaven Arzoumanian, NASA GSFC
A NICER View: Physics, Astrophysics, and Exploration from the International Space Station
Abstract: Neutron stars are extraordinary in every way. They are made of the densest stuff in the universe, their gravity is immense, and they are the most powerful magnets known. Some, known as "pulsars," sweep narrow beams of radiation through space as they spin, often as fast as blender blades, appearing to flash with unrivaled regularity like cosmic timepieces. Launched in June 2017, NASA's dual-purpose Neutron star Interior Composition Explorer (NICER) mission aims to answer longstanding questions about the physics and astrophysics of neutron stars, with a telescope on the International Space Station (ISS) designed to precisely time their pulsations and investigate their X-ray emissions. The mission's second purpose is a first-ever demonstration of autonomous spacecraft navigation using pulsars as beacons in a "Galactic Positioning System." This presentation provides an overview of the NICER mission, its SEXTANT navigation demonstration, and the insights that NICER is delivering about the physics of neutron stars, black holes, and the high-energy processes that they drive.
time: 4:00 p.m.
place: Kolker Room (26-414)
(refreshments at 3:30 p.m.)
hosted by: Douglas Hasell
Rikutaro Yoshida, Jefferson Lab
The Electron-Ion Collider and the New Scientific Frontier
Abstract: The understanding of the structure of matter at the level of atoms and molecules is a cornerstone of the technical achievements of the modern civilization; everything from modern medicine to communication infrastructure depends on this knowledge. The current understanding of the internal structure of protons, neutrons and nuclei, however, are at a comparatively primitive state.
While we understand something of how quarks and gluons make up these objects, we have very little idea of how they are arranged and interact and how that leads to the macro-properties of nucleons and nuclei. This lack of understanding has not only been due to experimental limitations, but to the difficulty of the Quantum Chromodynamics (QCD) that govern quarks and gluons. Advances in the theoretical understanding of QCD in the past decades, however,have lead to a framework that enables the measurement and interpretation of the quark and gluon structure of nucleons and nuclei. With these developments in mind, a new facility called the Electron-Ion Collider (EIC) has been proposed to be built in the US in order to investigate the structure of nucleons and nuclei in unprecedented detail.
I will discuss the science of EIC as well as the status of the project.
time: 4:00 p.m.
place: Kolker Room (26-414)
(refreshments at 3:30 p.m.)
PATRIOT'S DAY- No Talk this Week
hosted by: Jesse Thaler
John Campbell, Fermilab
Precision Theory and LHC Searches for Dark Matter
Abstract:Ongoing experimental searches at the LHC seek to establish the existence of weakly-interacting particle dark matter. Many of these are based on monojet signatures that rely on precise theoretical predictions to maximize their sensitivity. In this talk I will discuss how the need for precision theory at the LHC arises and describe how this challenge has been met. I will conclude by demonstrating the role that the precision theory community is playing in collider searches for dark matter.
time: 4:00 p.m.
place: Kolker Room (26-414)
(refreshments at 3:30 p.m.
hosted by: Richard Milner
Areg Danagoulian, MIT NSE
Nuclear Disarmament Verification via Resonant Phenomena
Abstract: Nuclear disarmament 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. A team of scientists working at the department of Nuclear Science and Engineering (NSE) has developed two novel concepts which leverage isotope-specific nuclear resonance phenomena to authenticate a warhead's fissile components by comparing them to a previously authenticated template. Most actinides such as uranium and plutonium exhibit unique sets of resonances when interacting with MeV photons and eV neutrons. When measured, these resonances produce isotope-specific features in the spectral data, thus creating an isotopic "fingerprint" of an object. All information in these measurement has to be and is encrypted in the physical domain in a manner that amounts 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. These new methodologies can dramatically increase the reach and trustworthiness of future nuclear disarmament treaties. The talk will discuss the concepts and recent results.
time: 4:00 p.m.
place: Kolker Room (26-414)
(refreshments at 3:30 p.m.)
hosted by: Will Detmold
Daniel Kasen, UC Berkeley/LBNL
Physics from the Gravitational and Electromagnetic Waves of a Neutron Star Merger
Abstract: Last August, the discovery of the merger of two neutron stars heralded the first time we have detected both gravitational waves (GW) and light from the same event. Gamma-rays measured only seconds after the GW signal put strong constraints on the speed of gravity. Optical and infrared observations over the following days and weeks localized the GW source and revealed the radioactive glow of heavy elements that were freshly synthesized in the merger and its aftermath. I will review the physics of compact object mergers and their electromagnetic counterparts, and discuss how modeling their radioactive light has allowed us to probe dense matter physics and to identify (finally) an astrophysical site where the heavy elements were synthesized via rapid neutron capture. I'll look ahead to what future "multi-messenger" observations may tell us about the diversity of gravitational wave sources and the cosmic origin of the heavy elements.
time: 4:00 p.m.
place: Kolker Room (26-414)
(refreshments at 3:30 p.m.)
hosted by: Phil Harris
Kristian Hahn, Northwestern University
Real-Time Track Finding with the CMS Experiment
Abstract: The High Luminosity LHC (HL-LHC) will produce roughly 200 overlapping proton-proton collisions per bunch crossing on average. To mitigate the impact of these extreme conditions, the HL-LHC upgrade of the Compact Muon Solenoid (CMS) experiment will introduce tracking information in its hardware (L1) trigger. A new Track Finding system will reconstruct the trajectories of charged particles from each LHC beam crossing and transmit these tracks to the downstream trigger system. The technical requirements for L1 Track Finding are extraordinary; the system must cope with the enormous data rates generated from the Tracker detector while simultaneously obeying a stringent 4 microsecond latency limit for track reconstruction. The CMS experiment will confront these challenges using an FPGA-based architecture that implements spatial and time-multiplexed data processing. In this talk I will review on-going R&D for the CMS Track Finder, which includes the evaluation of multi-gigabit links and system-on-chip technologies, as well as the investigation of algorithmic optimizations that capitalize on the design of modern FPGAs.
time: 4:00 p.m.
place: Kolker Room (26-414)
(refreshments at 3:30 p.m.)
