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NPP Seminar by Chris Tunnell (Rice)

August 27th, 2021 by al72

Date: Tuesday Aug 31, 2021 at 4pm
Location: HBH 227

Title: The bizzare excess electronic recoil events in XENON1T
Speaker: Chris Tunnell (Rice)

Abstract

XENON1T is the most sensitive dark matter detector built to date, but its senstivity has opened up a range of other scientific searches and discoveries. I will tell the story of one such search and the evidence we have for solar axions, a neutrino magnetic moment, or tritium. This result gained substaintial interest in the field with nearly 300 citations in the last year. I will also explain why each explaination is slightly unsettling, where XENONnT (our upgrade) should help clarify this situation.



NPP Seminar by Isaac Upsal (BNL)

April 27th, 2021 by geurts

Date: Tuesday April  27, 2021 at 4pm
Location: online

Title: Exploring the Frontier of Vorticity in Heavy-ion Collisions
Speaker: Isaac Upsal (BNL)

Abstract

In accelerators like RHIC, heavy atomic nuclei are collided at high energies to study emergent properties of the strong-nuclear force. At high-enough energies with heavy-enough nuclei such collisions create a short-lived novel fluid of deconfined quarks and gluons called the “Quark Gluon Plasma”. Because the nuclei themselves are so large, the transverse size of the nuclear overlap is a variable of significance to the field. Collisions with large impact parameters (low degree of overlap) have large angular momentum (~1000 hbar). For a collision which takes a finite amount of time one would expect an excess of particles with spin along the direction of system angular momentum due to spin-orbit coupling.

In 2017 STAR reported the first non-trivial measurement of this alignment, called the global polarization, at the order of a few percent (https://doi.org/10.1038/nature23004). In a thermalized fluid this polarization would come about through a vorticity. Using such a framework it’s possible to extract a vorticity on the order of 10^22 s^-1, which is notably higher than any previously known fluid. This measurement renewed interest in this physics within the heavy-ion physics community and there have been a number of interesting new calculations as well as measurements from STAR, ALICE, and HADES. I plan on discussing this measurement, newer developments, and the future of similar measurements.



NPP Seminar by Taylor Faucett (UCI)

January 25th, 2021 by geurts

Date: Wednesday January  27, 2021 at 2pm
Location: online (YouTube)

Title: Physicists Learning from Machines Learning
Speaker: Taylor Faucett (UCI)

Abstract

Machine Learning methods are extremely powerful but often function as black-box problem solvers, providing improved performance at the expense of clarity. Our work describes a new machine learning approach which translates the strategy of a deep neural network into simple functions that are meaningful and intelligible to the physicist, without sacrificing performance improvements. We apply this approach to benchmark high-energy problems of fat-jet classification and electron identification. In each case, we find simple new observables which provide additional classification power and novel insights into the nature of the problem.



NPP Seminar by Aaron Higuera (UH)

January 19th, 2020 by geurts

Date: Thursday January  23, 2020 at 4pm
Location: 223 Herman Brown Hall, Rice University

Title: Neutrinos, looking for the next big thing
Speaker: Aaron Higuera (UH)

Abstract

In this seminar I will give an overview of neutrinos, its history and I will discuss how neutrinos lead us to new physics phenomena, neutrinos oscillations and its implications. In addition, given the current knowledge of neutrino physics, I will discuss what are the open questions in neutrino physics and how we are planing to address them with the next generation of neutrino experiments. In specific, I will mentioned the Deep Underground Neutrino Experiment, and how we plan to build such experiment, its technology and R&D efforts.



NPP Seminar by Zhen Liu (Univ. of Maryland)

December 2nd, 2019 by geurts

Date: Thursday December 5, 2019 at 4pm
Location: 223 Herman Brown Hall, Rice University

Title: LHC Opportunities in Long-Lived Signatures from Hidden Sectors
Speaker: Zhen Liu (Univ. of Maryland)

Abstract

The LHC bear great potential in seeking for hidden sector particles, such as a high-quality QCD axion, glueballs, and heavy neutrinos. In this talk, I will present my recent studies on how to probe these hidden sector particles through the novel but challenging long-lived particle searches.



NPP Seminar by Jelle Aalbers (Univ. Stockholm)

October 27th, 2019 by geurts

Date: Thursday October 31, 2019 at 4pm
Location: 223 Herman Brown Hall, Rice University

Title: Light Dark Matter Search with XENON1T
Speaker: Jelle Aalbers (Univ. Stockholm)

Abstract

This talk reports on recent light dark matter results from XENON1T (https://arxiv.org/abs/1907.11485). Using strong event selections, rather than requiring a scintillation signal, we obtain a thousand times lower background than in similar previous searches. This yields world-leading constraints on WIMPs, leptophillic dark matter, dark photons and axion-like particles.



NPP Seminar by Fernanda Psihas (UT Austin)

August 26th, 2019 by geurts

Date: Thursday August 29, 2019 at 4pm
Location: 223 Herman Brown Hall, Rice University

Title: Deep Learning for Neutrino Physics: Successes and Lessons
Speaker: Fernanda Psihas (UT Austin)

Abstract

Among the particles of the Standard Model, neutrinos are the least understood. Experiments worldwide are engaged in studying their properties and behavior, which could be linked to the matter-antimatter asymmetry of the Universe. Over the past several years, particle physicists have adapted techniques from the field of computer vision, whose tasks translate naturally for detector data analysis and simulation. Particle physics datasets are also a rich playground for new algorithmic approaches to data analysis. Neutrino experiments often look for rare signals in large amounts of data. Deep Learning techniques have yielded substantial improvements to the physics reach of many experiments already, and have redefined the limit to what is attainable in the realm of data collection, analysis, and R&D. Not only is neutrino physics benefiting from these techniques, but we are also contributing in new ways to algorithm design and utilization. This talk will discuss the main successes and newest developments of deep learning applications in the field of neutrino physics. The particulars of neutrino experiment data and tasks will be discussed, as well as lessons learned and future applications of machine learning to the field of neutrino physics.



NPP Seminar by Sven Dildick (Texas A&M)

May 17th, 2019 by geurts

Date: Thursday May 23, 2019 at 10am
Location: 223 Herman Brown Hall, Rice University

Title: Searching for pair production of new light bosons decaying to muons with the CMS detector
Speaker: Sven Dildick (Texas A&M)

Abstract

Searches for new light bosons can offer insights into the nature of the Higgs boson and dark matter. These particles are introduced in many extensions of the standard model, such as supersymmetry and models with hidden sectors. In this seminar I present a search for pair production of new light bosons with the CMS detector at the LHC. The search is uniquely sensitive to signatures with multi-muon final states and is designed to be model independent. The results of the analysis using 13 TeV collision data set are interpreted in the context of two relevant benchmark models. I will also discuss the phase-2 upgrade of the CMS detector and how it can improve the sensitivity in these searches.



NPP Seminar by Peter Adshead (Univ. of Illinois at Urbana-Champaign)

April 11th, 2019 by geurts

Date: Thursday April 11, 2019 at 4pm
Location: 223 Herman Brown Hall, Rice University

Title: Gauge-field Inflation and the Origin of the Matter-antimatter Asymmetry
Speaker: Peter Adshead (Univ. of Illinois at Urbana-Champaign)

Abstract

The basic inflationary paradigm is in good shape. On the one hand, the observed density fluctuations are adiabatic, gaussian and are red-tilted—characteristics in general agreement with simple models built from scalar fields. On the other hand, B-mode polarization of the cosmic microwave background sourced by primordial gravitational waves, the so-called smoking-gun signature of inflation, remains elusive. Upcoming and planned experiments will make increasingly precise B-mode measurements, potentially putting the inflationary paradigm through a stringent test.

In this talk, I describe a new class of inflationary scenarios which utilize gauge fields to generate inflationary dynamics in the early universe. Beyond simply providing yet another model for inflation, these scenarios furnish unique observational imprints which distinguish them from standard scalar-field scenarios. In particular, these scenarios generically result in large-amplitude, chiral gravitational waves and provide counterexamples to the standard claim that an observable tensor-to-scalar ratio requires inflation at the grand unification scale, as well as super-Planckian excursions of the inflaton. In addition I discuss how these chiral gravitational waves may be responsible for the matter-antimatter asymmetry of the Universe.



NPP Seminar by Dongqing Huang (Brown University)

February 25th, 2019 by geurts

Date: Thursday Feb. 28, 2019 at 11am
Location: 223 Herman Brown Hall, Rice University

Title: LUX/LZ Dark Matter Experiment and Low Energy Calibrations of LUX Detector
Speaker: Dongqing Huang (Brown University)

Abstract

The LUX dark matter experiment is a 350 kg dual-phase time-projection chamber operating at the 4850 ft level of the Sanford Underground Research Facility in Lead, SD, USA from 2013 to 2016. The experiment searches for direct evidence of Weakly Interacting Massive Particles (WIMPs), a favored Dark Matter candidate. With a total exposure of 129 kg.year, LUX sets a 90% CL upper limit on the spin-independent (SI) WIMP-nucleon cross section of 1.1 × 10−46 cm2 at a WIMP mass of 50 GeV.c−2. The LUX experiment also carried out extensive calibrations for a better understanding of both electronic recoil (ER) and nuclear recoil (NR) responses in LXe. LUX achieved absolute energy calibrations of NR down to an energy of 0.7 keVnr using D-D neutron source and ER down to an energy of 186 eV using 127Xe electron capture in LXe. Both represent the lowest-energy ER and NR in situ measurements that have been explored in liquid xenon. The low energy calibrations allow an lower energy threshold for WIMP search and significantly improve LXe TPC sensitivities to low-mass WIMPs.

I will also present the LUX-ZEPLIN (LZ) detector, a LXe dark matter detector featuring more than 5 tons of target material in the fiducial region (from a total of 10 tons of xenon). It will be installed at the same facilities used by LUX. With a projected exposure of 1000 days (commissioning starts in 2020), LZ aims to exclude the WIMP-nucleon SI cross-sections down to 1.6×10−48 cm2 (90% CL, MWIMP = 40 GeV.c−2). This represents a factor of 10 improvement when compared to the expected sensitivities of currently running LXe dark matter experiments