Elementary Particle Physics Seminar

semester, 2019


Wednesday, January 23rd 2019
There will be no seminar this week.

Wednesday, January 30th 2019
The seminar has been postponed until Friday afternoon.

Friday, February 1st 2019
Speaker: Christopher Palmer (Princeton University)
Subject: Observation of the Higgs boson decaying to bottom quarks at CMS
Note change of time and day for this seminar, this week only.

The Higgs boson decay to a bottom quark-antiquark pair has been sought
for decades by the high energy community (i.e. at LEP and Tevatron).
LHC experiments built analyses based on the experience of Tevatron
experiments' analysis techniques. With the observation of the Higgs
boson at LHC during Run 1, the search for this decay channel became
sharply focused. As the bottom quark pair channel is the most
probable decay of the Higgs boson (58%), its observation is both
important in terms of quantifying the Higgs boson and it represents an
important milestone in high energy physics. The results presented use
datasets from the LHC Run 1 and Run 2 (2016+2017) from CMS. This Run
2, 13 TeV dataset corresponds to an integrated luminosity of ~80
fb^-1. The analysis strategy, the background estimation techniques,
and significant analysis improvements from the 2017 data analysis in
CMS are shown. An outlook on the upcoming analysis of the full Run 2
dataset (and beyond) will be discussed.


Wednesday, February 6th 2019
Speaker: Andrew Furmanski (The University of Manchester)
Subject: Neutrinos at Short Baselines

Neutrino oscillations are being measured carefully across a broad range
of experiments, but there remain some anomalies that have not been fully
explained. Using three liquid argon TPCs on the same neutrino beam, the
short baseline neutrino program at Fermilab will set the worlds best
limits on eV-scale sterile neutrinos, whilst developing liquid argon
technology critical for DUNE and making precision measurements of
neutrino-argon interactions. MicroBooNE - the first operating TPC in
the SBN program - has been collecting data since late 2015. This talk
will describe the current status of the three-detector experiment, and
present the first physics results with MicroBooNE data.


Wednesday, February 13th 2019
Speaker: Yangyang Cheng (Cornell University)
Subject: A New Paradigm for Dark Matter Search at the LHC

The existence of dark matter (DM), through astrophysical and cosmological observations, presents some of the most striking evidence of physics beyond the Standard Model. Stringent limits have been placed on DM as a Weakly Interacting Massive Particle (WIMP) from direct and indirection detection as well as collider experiments. If instead of one type of DM particle, nature contains a complex dark sector, the new hidden particles can evade existing DM limits and most direct detection experiments, but may be produced at high-energy colliders like the LHC. Many dark sector models predict long-lived particles with striking collider signature, opening an exciting new paradigm for dark matter
search. This talk overviews the landscape for dark matter search, and
introduces the physics motivation for a complex dark sector with long-lived particles. It then describes two types of signature-driven dark sector searches at the CMS experiment, for a dark shower and for displaced lepton jets. Finally, the talk discusses prospects for dark sector searches at the High-Luminosity LHC with detector and trigger upgrades, in particular how the new forward detectors and enhanced timing capabilities can reach new phase spaces and sensitivities.


Monday, February 18th 2019
Speaker: David Caratelli (FNAL)
Subject: Neutrinos in High Definition

Thanks to advances in detector technology and the advent of powerful neutrino sources, neutrino physics in the past decade has rapidly moved to an era of precision measurements. With these new tools, we hope to shed light on their curious properties, and address fundamental questions on the fabric of our universe. In this seminar I will talk about how the MicroBooNE experiment is using a new detector technology to understand an anomaly in neutrino physics that has motivated many interesting phenomenological models. The talk will describe the MicroBooNE experiment, a short-baseline neutrino detector sitting in a ~1 GeV beam, and the status of the measurement of electron neutrino
interactions. I will focus on illustrating how the study of electromagnetic activity in LArTPC detectors enables MicroBooNE’s study of electron neutrino interactions as well as the broader neutrino oscillation physics program to be carried out at Femilab. Finally, I will describe how low-energy electromagnetic signatures can expand this detector technology’s physics reach to explore BSM physics and astrophysical signatures.


Wednesday, February 20th 2019
Speaker: Nadja Strobbe (FNAL)
Subject: Taking aim at New Physics

The Standard Model of Particle Physics has been immensely successful. However, many questions remain, such as the nature of dark matter, the origin of the matter-antimatter asymmetry, and the question of naturalness and the hierarchy problem. A variety of New Physics models have been proposed to address these questions. One class of such new physics models is supersymmetry (SUSY).

Many searches for SUSY have been performed with the LHC data, and so far, none has found any signs of physics beyond the Standard Model. A theme common to many of these searches is the reliance on the presence of substantial missing transverse momentum (MET) from undetected SUSY particles. It is therefore reasonable to wonder whether SUSY could take a form that instead produces low-MET final states, thereby evading detection in standard searches.

In this seminar I will first discuss the motivation and strategy behind some of the traditional SUSY searches, focusing in particular on searches for the top squark. Then, I will introduce SUSY models that lead to low-MET final states, including stealth SUSY and R-parity violating SUSY. I will describe a novel analysis that takes aim at the challenging final state with top quarks, many extra jets, and low MET. Finally, I will conclude with a look towards the future, including HL-LHC projections for SUSY searches.


Wednesday, March 6th 2019
Speaker: Jim Linnemann, Michigan State University
Subject: HAWC: Extreme Astronomy with Big Buckets of Water

Though we can see thousands of stars in a clear night sky, the number of known sources emitting TeV gamma rays is less than 200. This is both because there are few instruments capable of measuring such photons, and because the sources are restricted to particularly violent astrophysical processes which
produce photons of 100 TeV and beyond. The HAWC (High Energy Water Cherenkov) array is the only survey instrument in this energy range. Located on a plateau between two volcanos in Mexico at an altitude of 4100 m, HAWC is able to survey 60% of the sky, and observes 1/6 of the full sky at any moment, day or night. I will discuss the array, its construction and principles of operation, a selection of recent results spanning particle astrophysics to astronomy, and how we are pursuing multi-messenger astronomy to better understand the nature of TeV gamma ray sources.

Faculty Host: Roger Rusack

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