High Energy Physics Seminars

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Wednesday, December 8, 2021
4:00 PM
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"TBA"


Dr. Christine McClean , SUNY-Buffalo
[Host: Chris Neu]
ABSTRACT:

TBA

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Wednesday, November 3, 2021
4:00 PM
Physics Building, Room 204

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"TBA"


Prof. Tracy Larson , UVA Biology
[Host: Chris Neu]
ABSTRACT:

TBA

TBA


Wednesday, October 27, 2021
4:00 PM
Physics Building, Room 204

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"Status and Prospects for the NOvA Long-Baseline Neutrino Experiment"


Erika Catano-Mur , William and Mary
[Host: Craig Group]
ABSTRACT:

TBA

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Wednesday, October 6, 2021
4:00 PM
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"The Astrophysics Program of the NOvA Experiment"


Matthew Strait , University of Minnesota
[Host: Craig Dukes]
ABSTRACT:

NOvA is a long-baseline neutrino oscillation experiment with the primary goals of discovering CP violation in the neutrino sector, determining the neutrino mass hierarchy and constraining the mixing angle theta_23. The detectors have a highly active, finely segmented design that offers superb event identification capability. Besides oscillation measurements, NOvA also has a rich cosmic ray and astrophysics program. We have set competitive limits on the flux of magnetic monopoles and for supernova-like neutrinos associated with gravitational wave events. NOvA runs its own supernova trigger and plans to participate in SNEWS. Both the Near and Far detectors are being used to search for dark matter. We have observed new details of the seasonal variation of cosmic rays at two depths and have several other cosmic rays analyses underway.

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Wednesday, September 29, 2021
4:00 PM
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"High Energy Neutrino Astrophysics with Radio Techniques "


Professor Amy L. Connolly , Ohio State University
[Host: Craig Dukes]
ABSTRACT:

Multimessenger astronomy has entered an exciting new era with the recent discovery of both gravitational waves and cosmic neutrinos.  I will focus on extremely energetic neutrinos as particles that can uniquely probe the most extreme astrophysics sources at cosmic distances, as well as fundamental physics in an unexplored energy regime.  While the optical detection technique remains the most powerful for neutrino detection over a broad energy range, radio techniques have emerged in the last two decades as the most promising for a long-term program to push the neutrino frontier by over a factor of 1000 in energy.   I will present the latest results from the field of high energy neutrino astrophysics, with a focus on the balloon-borne ANITA experiment and the in-ice South Pole array ARA.  I will also give an overview of the many exciting projects in this field that are on the horizon, and their anticipated impact in terms of the astrophysics and particle physics questions that we seek to answer.

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Wednesday, September 22, 2021
4:00 PM
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ABSTRACT:

Abstract: The LHC is not only the highest energy, but also the highest intensity proton-proton collider ever constructed. In 2016, the LHC exceeded its initial designed luminosity of 10^34 cm-2s-1, and since then, it has further increased to a record setting 2.06E34 cm-2s-1. The increase in luminosity has created a higher occupancy, radiation, and pileup environment, which requires an increasingly robust detector. The first of such adaptations was the CMS phase-I pixel upgrade. This pixel upgrade improved the pixel detector's bandwidth, tracking efficiency, radiation tolerance, and material budget in order to ensure physics performance up to the HL-LHC era. The next proposed tracking upgrade is a complete replacement of the inner and outer tracker. The HL-LHC Outer Tracker Upgrade is a monumental change that increases the detector's granularity, hit coverage, readout speed, triggering capabilities, radiation hardness, and cooling capabilities. This seminar will cover the construction, installation, and performance of the CMS phase-I pixel upgrade and the design, progress, and expected physics performance of the HL-LHC outer tracker upgrade.

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Wednesday, September 15, 2021
4:00 PM
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"Unified framework for B-anomalies, muon g-2, and neutrino masses"


Anil Thapa , University of Virginia - Department of Physics
[Host: Julian Heeck]
ABSTRACT:

A model of radiative neutrino masses which also resolves anomalies reported in B-meson decays, RD(★) and RK(★), as well as in muon g −2 measurement, ∆aµ is presented. Neutrino masses arise in the model through loop diagrams involving TeV-scale leptoquark (LQ) scalars R2 and S3. Fits to neutrino oscillation parameters are obtained satisfying all flavorconstraints which also explain the anomalies in RD(★), RK(★) and ∆aµ within 1 σ. An isospin-3/2 Higgs quadruplet plays a crucial role in generating neutrino masses; we point out that the doubly-charged scalar contained therein can be produced in the decays of the S3 LQ, which enhances its reach to 1.1 (6.2) TeV at √s = 14 TeV high-luminosity LHC (√s = 100 TeV FCC-hh).

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Wednesday, September 1, 2021
4:00 PM
Physics Building, Room 204

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"Precision luminosity measurement at CMS with the Pixel Luminosity Telescope "


Dr. Andres Delannoy , University of Tennessee, Knoxville
[Host: Chris Neu]
ABSTRACT:

The Pixel Luminosity Telescope is a silicon pixel detector dedicated to luminosity measurement at the CMS experiment. It consists of 48 silicon sensor planes arranged into 16 "telescopes'' such that particles originating from the CMS interaction point will pass through all three planes in the telescope. It takes advantage of the "fast-or'' readout mode built into the CMS Phase-0 pixel readout chip, which can be processed at a frequency of 40 MHz, to determine the instantaneous luminosity from the rate of triple coincidences. The full pixel information, including hit position and charge, is read out at a lower rate of ~3 kHz and can be used for studies of systematic effects in the measurement. A full rebuild of the PLT was installed in early July 2021 in anticipation of Run 3 of the LHC, which incorporates a few silicon sensors developed for the CMS Phase-2 upgrade for the High-Luminosity LHC. Several detailed studies will be presented that illustrate the impact of radiation damage on the detector performance during Run 2. The lessons learned from Run 2 and the outlook for Run 3 will be underlined. In addition, a new search for heavy-neutrinos using the vector boson fusion signature in final states with a pair of leptons and four jets will be highlighted.

VIDEO:
Joint Nuclear/HEP seminar

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Wednesday, April 28, 2021
4:00 PM
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"First results from the Fermilab Muon g-2 experiment"


Manolis Kargiantoulakis , Fermilab
[Host: Craig Group and Dinko Pocanic]
ABSTRACT:

The Muon g − 2 Experiment at Fermilab has measured the anomalous magnetic moment of the muon to 460 parts-per-billion, based on data collected during the first physics run in 2018. The experiment determines the anomalous precession frequency of the muon spin inside the highly uniform and precisely measured magnetic field of our storage ring. Our result is in excellent consistency with (and slightly more precise than) the BNL measurement of the same quantity from two decades ago. The combination of the experimental measurements increases the tension with the Standard Model prediction, enhancing the significance of the discrepancy to 4.2σ. In this seminar we will present the challenging experimental measurement and discuss the status of the discrepancy. 

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Wednesday, April 21, 2021
4:00 PM
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"Is double gluon bremsstrahlung in a quark-gluon plasma accurately described by the Ncolor = ∞ approximation to QCD?"


Omar Elgedawy , University of Virginia - Department of Physics
[Host: Peter Arnold]
ABSTRACT:
QCD jets produced from colliding two heavy nuclei play an important role in understanding properties of the Quark Gluon Plasma produced in these energetic collisions. During their travel through the medium, high energy partons lose their energy due to interactions with the medium through elastic collisions and medium-induced splitting processes like bremsstrahlung and pair production. In the high energy limit, these splitting processes are coherent over large distances and can no longer be treated as quantum mechanically independent, leading to a suppression of the splitting rate known as the Landau-Pomeranchuk-Migdal effect. An important question that arises is whether consecutive splittings of the high energy particle overlap within the formation time of an individual splitting. This case has been analyzed in the Nc = ∞ limit within the thick medium approximation. To see if this result applies for real QCD with Nc = 3, we calculate the next to leading order correction (i.e. O(1/N2)) to the gluon double-splitting. We have already completed a subset of the diagrams known as sequential diagrams. In this talk, I will report first results on whether the Nc = ∞  approximation to the differential rate of overlapping double bremsstrahlung of gluons is reliable, and in particular whether the correction is large or small compared to the naive expectation of 1/N2c 10% for Nc = 3.
 
 
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Wednesday, March 31, 2021
4:00 PM
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"Probing modified gravitational-wave propagation through tidal measurements of binary neutron star mergers"


Nan Jiang , University of Virginia - Department of Physics
[Host: Kent Yagi]
ABSTRACT:

Gravitational-wave sources can serve as standard sirens to probe cosmology by measuring their luminosity distance and redshift.  Such standard sirens are also useful to probe theories beyond General Relativity with a modified gravitational-wave propagation.  Most previous studies on the latter assume multi-messenger observations so that the luminosity distance can be measured with gravitational waves while the redshift is obtained by identifying sources’ host galaxies from electromagnetic counterparts.  Given that gravitational-wave events of binary neutron star coalescences with associated electromagnetic counterpart detections are expected to be rather rare,  it is important to examine the possibility of using standard sirens to probe gravity with gravitational-wave measurements alone.  In this paper, we achieve this by extracting the redshift from the tidal measurement of binary neutron stars (that was originally proposed within the context of gravitational-wave cosmology).  We also improve previous work by considering multi-band gravitational-wave observations between ground-based (e.g.  Einstein Telescope) and space-based (e.g.  DECIGO) interferometers. We find that such multi-band observations with the tidal information can constrain a parametric non-Einsteinian deviation in the luminosity distance more stringently than the case with electromagnetic counterparts (due to a larger number of available events) by a factor of a few.  We also map the above-projected constraints on the parametric deviation to those on specific theories beyond General Relativity.

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Wednesday, March 24, 2021
4:00 PM
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"Search for Long-Lived Particles at CMS in Runs 2 and 3 and beyond"


Ang Li , University of Virginia - Department of Physics
[Host: Chris Neu]
ABSTRACT:

Many physics beyond standard model predicts the existence of long-lived particles, which will travel a relatively long distance in the detector after it’s generation and leave some special signals in the detector such as displaced vertices, displaced jets and delayed leptons etc.. This talk introduces the search for displaced vertex, including event selection, vertex reconstruction and data-driven background estimation method. In the meanwhile, the talk also includes the structure and mechanics study for MIP Timing Detector, which is capable to measure the time information precisely when a charged particle pass through it and will be installed in CMS for high luminosity LHC era.

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Wednesday, March 17, 2021
4:00 PM
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"Recent Results at the NOvA Neutrino Oscillation Experiment and Developments for Future Sensitivity Improvements"


Andrew Sutton , University of Virginia - Department of Physics
[Host: Craig Group]
ABSTRACT:

NOvA is a long-baseline accelerator neutrino experiment that can probe outstanding questions in neutrino oscillation physics. Among these are: the neutrino mass hierarchy, CP violation in the lepton sector, and the determination of the neutrino mixing angle θ23. NOvA has access to these parameters by observing electron neutrino appearance and muon neutrino disappearance over an 810 km baseline. For the high statistics muon neutrino measurements the shape of the energy spectra can be used to further constrain the oscillation parameters owing to the energy dependence of neutrino oscillations. Therefore, a high resolution measurement of the neutrino energy is necessary to make precision measurements of those parameters. Moreover, uncertainties on detector calibration and neutrino interaction models have a significant impact on measurement sensitivity. NOvA has an ongoing test beam effort to improve understanding of the detector response and reduce energy calibration uncertainties. Additionally, a Long Short-Term Memory (LSTM) neural network has been developed to estimate muon neutrino and provides improved energy resolution. Interaction model uncertainties can be further addressed by adversarial network training which can be employed with different interaction generators to increase the robustness and performance of the LSTM energy estimator against model variations. This talk will present the most recent NOvA oscillation results and show ongoing work to reduce systematic uncertainties and further improve measurement sensitivity.

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Wednesday, March 3, 2021
4:00 PM
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ABSTRACT:

The Mu2e experiment will measure the charged-lepton flavor violating (CLFV) neutrino-less conversion of a negative muon into an electron in the field of a nucleus. The conversion process results in a monochromatic electron with an energy slightly below the muon rest mass. Mu2e will improve the previous measurement by four orders of magnitude using a new technique, reaching a SES (single event sensitivity) of 3 x 10^{-17} on the conversion rate, and a discovery at 2 x 10^{-16}. The experiment will reach mass scales of nearly 10^4 TeV, far beyond the direct reach of colliders. The experiment is sensitive to a wide range of new physics, complementing and extending other CLFV searches. 

Mu2e is under design and construction at the Muon Campus of Fermilab with our first physics run in early 2025.

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Wednesday, February 3, 2021
4:00 PM
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"Reaching for the stars with CNO solar neutrinos"


Zara Bagdasarian , UC, Berkeley
[Host: Craig Dukes]
ABSTRACT:

The prime energy producer in the sun is the fusion of hydrogen to form helium. However, there is more than one way for this fusion to takeplace: for stars the size of the sun or smaller, the proton-proton (pp) chain reactions dominate (~99%), while in heavier stars, the carbon-nitrogen-oxygen (CNO) cycle is expected to play a more important role. Not only these fusion reactions would not have been possible without the emission of neutrinos, neutrinos are the only way to directly access the processes in the core of the sun.

Borexino experiment, located at the Laboratori Nazionali del Gran Sasso, was built with a primary goal of the Be7 solar neutrinos (part of pp chain) detection. In more than a decade of data taking, Borexino has not only demonstrated the unprecedentedly high sensitivity towards Be7 solar neutrinos (<3%) but performed a comprehensive study of low-energy neutrinos from the complete pp-chain. After a number of developments in both hardware and software, Borexino has presented the first experimental evidence of the up-to-now elusive CNO fusion cycle in the Sun. The absence of the CNO neutrinos signal is disfavoured by the Borexino experiment at 5σ.

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Wednesday, January 20, 2021
4:00 PM
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ABSTRACT:

Direct decays of proposed heavy force mediator particles to standard model leptons
have been largely excluded by past LHC searches, challenging theorists to explore more complex
decay chains. We begin our search with a framework model of a Leptophobic Z' cascading to a
pair anomalons, new Beyond the Standard Model fermions. These heavy intermediate particles decay in turn to neutral standard model bosons and a stable anomalon, which appears in the Compact Muon Solenoid (CMS) detector as missing transverse momentum (pT-miss). From a model independent point of view, this topology creates an interesting structure with a resonantly produced particle cascading to a final state with 2 missing particles, with each level of the cascade including new particles with unknown masses. To turn this into a bump hunt for the resonant particle, we employ Recursive Jigsaw Reconstruction (RJR), a rule-based methodology to systematically reduce degrees of freedom, allowing for the calculation of mass estimators at each level of our decay chain. RJR is an example of how analysis tools are evolving to be sensitive to the most well-hidden of new physics, and the detectors are doing the same. I will also give an overview of the Phase I upgrade to the CMS Hadronic Calorimeter.

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