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High Energy Physics Seminars History

ics Joint Nuclear/HEP seminar


Wednesday, July 24, 2019
3:30 PM
Physics Building, Room 204
Yuri Kovchegov [Host: Peter Arnold]
Ohio State
"Proton Spin at Small x"
ABSTRACT:

An integral part of the proton spin puzzle are the contributions to the proton spin coming from quarks and gluons having very small values of the Bjorken x variable. These contributions are mostly beyond the reach of current experiments and are very hard to calculate numerically on the lattice. It appears that better theoretical understanding of quark and gluon helicity distributions at small x is needed to assess the amount of proton spin coming from this region. In my talk I will describe the recent theoretical work aimed at finding the small-x asymptotics of the quark and gluon helicity distributions, along with their orbital angular momenta (OAM). I will derive small-x evolution equation for helicity and solve them to find the small-x asymptotics of the parton helicity distributions and OAM. The results of this work can be compared to the data to be collected at the upcoming Electron-Ion Collider (EIC) and can also be used to extrapolate the small-x helicity distributions to be measured at EIC to even smaller values of x, thus constraining the proton spin coming from small x.

ics High Energy
Wednesday, April 24, 2019
3:30 PM
Physics Building, Room 204
Pedro Cunha [Host: Kent Yagi]
University of Lisbon
"Light ring stability in ultra-compact objects"
ABSTRACT:

The following theorem is proven: axisymmetric, stationary solutions of the Einstein field equations formed from classical gravitational collapse of matter obeying the null energy condition, that are everywhere smooth and ultracompact (i.e., they have a  light ring, a.k.a. circular photon orbit) must have at least two light rings, and one of them is stable. It has been argued that stable light rings generally lead to nonlinear spacetime instabilities. Thus this result implies that smooth, physically and dynamically reasonable ultracompact objects are not viable as observational alternatives to black holes whenever these instabilities occur on astrophysically short time scales. The proof of the theorem has two parts: (i) We show that light rings always come in pairs, one being a saddle point and the other a local extremum of an effective potential. This result follows from a topological argument based on the Brouwer degree of a continuous map, with no assumptions on the spacetime dynamics, and hence it is applicable to any metric gravity theory where photons follow null geodesics. (ii) Assuming Einstein’s equations, we show that the extremum is a local minimum of the potential (i.e., a stable light ring) if the energy-momentum tensor satisfies the null energy condition.

ics High Energy
Wednesday, April 17, 2019
3:30 PM
Physics Building, Room 204
Alexander Saffer [Host: Kent Yagi]
Montana State University
"The Exterior Spacetime of Relativistic Stars in Quadratic Gravity"
ABSTRACT:

General Relativity (GR) has been the cornerstone of gravitational physics for a century. Over this time, numerous predictions and tests have strengthened the belief in GR as the foremost theory when discussing gravity. However, GR cannot in its present form be reconciled with either quantum mechanics, or many cosmological observations such as galactic rotation curves or the accelerated expansion of the universe. In an attempt to rectify these shortcomings, modified theories of gravity have been proposed. In this talk, I will present one of these theories and discuss my work in attempting to test its validity through the development of an exterior spacetime (metric) for a neutron star. From this, we expect to be able to develop a pulse profile which can be used, in conjunction with observations made of the x-ray flux of radiating neutron stars, to place constraints on the theory.

 

ics High Energy
Wednesday, April 10, 2019
3:30 PM
Physics Building, Room 204
Bertrand Echenard [Host: Craig Dukes]
Caltech
"Exploring light dark matter with the LDMX experiment"
ABSTRACT:

Understanding the nature of dark matter is a central objective of modern science, and recent theoretical developments have highlighted the importance of extending current searches over a wider range of masses. The Light Dark Matter eXperiment (LDMX) has been propose to search for light dark matter and sub-GeV New Physics in fixed-target electron-nucleus collisions with unprecedented sensitivity. The experiment is based on a missing momentum technique, in which dark matter is emitted by electrons scattering in a thin target, resulting in large missing momentum and energy in the detector. This talk will discuss the motivation for light dark matter and describe the LDMX concept and its expected performance.

ics Joint High Energy and Nuclear Seminar


Wednesday, April 3, 2019
3:30 PM
Physics Building, Room 204
Dr. Tongtong Cao [Host: Craig Group]
Hampton University
"Precise Measurement of the Ke2Kµ2 Branching Ratio and New Physics Search with a Stopped K+ Beam Experiment"
ABSTRACT:

The J-PARC TREK/E36 experiment with a stopped K+ beam is designed to provide a more precise measurement of the branching ratio RK = Γ(K+ → e+ν)/Γ(K+ → µ+ν) than previous in-flight K+ decay experiments. RK is very precisely predicted by the Standard Model (SM) with an uncertainty of 4×10−4 and any deviation from this prediction would very clearly indicate the existence of new physics beyond the SM. Additionally, the experiment is searching for dark photons/light neutral bosons (A0), which could be associated with dark matter or explain the gµ-2 anomaly and the proton radius puzzle. In the experiment, a K+ beam was stopped by a scintillating fiber target, and charged decay products were momentum analyzed and tracked by a 12-sector superconducting toroidal magnetic spectrometer and multi-wire proportional chambers (MWPCs) combined with a photon calorimeter with a large solid angle (75% of 4π) and 3 different particle identification systems. In this talk, the status of the RK and A0 analyses is presented, and the MWPC calibration and tracking by a Kalman filter are reported. This work has been supported by awards DE-SC0003884 and DE-SC0013941 in U.S., NSERC in Canada, and Kaken-hi in Japan.
 

ics High Energy
Wednesday, March 20, 2019
3:30 PM
Physics Building, Room 204
Christopher White, Ph.D. [Host: Craig Dukes]
Illinois Institute of Technology
"Neutrino Physics from the PROSPECT Experiment"
ABSTRACT:

PROSPECT, the Precision Oscillation and Spectrum Experiment, is a reactor antineutrino experiment designed to search for eV-scale sterile neutrinos and measure the spectrum of antineutrinos from highly-enriched 235U at the High Flux Isotope Reactor (HFIR). PROSPECT uses a 4-ton, segmented 6Li-doped liquid scintillator detector to make a high-resolution measurement of the prompt energy spectrum from inverse beta decay on protons. An optical and radioactive source calibration system integrated into the active detector volume is used to characterize the optical and energy response of all detector segments. I will discuss the calibration and characterization of the PROSPECT detector and report on PROSPECT’s first measurement of the energy spectrum associated with reactor antineutrinos.

ics Special Joint Nuclear and High Energy Seminar


Thursday, February 28, 2019
2:00 PM
Physics Building, Room 204
Oleg Denisov [Host: Dustin Keller]
COMPASS experiment
"A New QCD Facility at the M2 beam line of the CERN SPS (COMPASS++/AMBER)"
ABSTRACT:

Possibility to use high intensity secondary beams at the SPS M2 beam
line in combination with the world’s largest polarized target, liquid hydrogen,
liquid deuterium and various nuclear targets create a unique opportunity
for universal experimental facility to study previously unexplored aspects
of meson and nucleon structure, QCD dynamics and hadron spectroscopy. 

High intensity hadron (pion dominated) beams already made COMPASS the
world leading facility for hadron spectroscopy and  hadron structure
study through Drell-Yan production of di-muon pairs. High intensity
muon beams, previously used for unique semi-inclusive and exclusive
hard scattering programs, make possible proton radius measurement in
muon-proton elastic scattering and further development of polarized
exclusive hard scattering program.
  
Upgrades of the M2 beam line resulting in high intensity RF-separated
anti-proton- and kaon-beams would greatly expand the horizon of experimental
possibilities at CERN: hadron spectroscopy with kaon beam, studies
of transverse momentum dependent quark structure for protons, pions and
kaons, precise studies of nuclear effects and for the first time measurements
of kaon quark—gluon substructure.

ics High Energy
Tuesday, January 15, 2019
4:00 PM
Physics Building, Room 204
Reserved
"TBA"
ABSTRACT:

TBA

ics High Energy
Wednesday, December 5, 2018
3:30 PM
Physics Building, Room 313
Brian Beckford [Host: Craig Dukes]
University of Michigan
"New results on the search for the elusive K_L→πνν ̅ with the KOTO detector "
ABSTRACT:

The KOTO experiment was designed to observe and study the KL→πνν decay. The Standard Model (SM) prediction for the mode is 2.4 x 10-11 with a small theoretical uncertainty [1]. An experimental upper limit of 2.6 x 10-8 was set by the KEK E391a collaboration [2]. The rare “golden” decay is ideal for probing for physics beyond the standard model. A comparison of experimentally obtained results with SM calculations permits a test of the quark flavor region and provides a means to search for new physics.

The signature of the decay is a pair of photons from the π0 decay and no other detected particles. For the measurement of the energies and positions of the photons, KOTO uses a Cesium Iodide (CSI) electromagnetic calorimeter as the main detector, and hermetic veto counters to guarantee that there are no other detected particles.

KOTO’s initial data was collected in 2013 and achieved a similar sensitivity as E391a result [3]. Since then, we completed significant hardware upgrades and had additional physics runs in 2015 at beam powers of roughly 24-40 kW. This presentation will present new results from KOTO and its search of detecting KL→πνν.

ics High Energy
Wednesday, November 14, 2018
3:30 PM
Physics Building, Room 313
Andreas Jung [Host: Bob Hirosky]
Purdue
"Top quark physics at the precision frontier"
ABSTRACT:

The talk will highlight latest results on top quark physics at CMS employing pp collision data at a center-of-mass energy of 13 TeV. New results from other experiments and center of mass energies will also be discussed. With millions of top quarks already collected at the LHC top quark physics enters the precision era. Differential cross section measurements and top quark property measurements, in particular angular correlations, are challenging the Standard Model predictions. The intimate connection of the top quark to the Higgs Boson is scrutinized by highly precise direct measurements of the top quark mass, with alternative approaches entering the precision realm as well. The talk concludes with implications for the SM and an outlook towards the ultimate precision frontier at the high-luminosity phase of the LHC.

 

ics High Energy
Wednesday, October 10, 2018
3:30 PM
Physics Building, Room 313
Eliu Huerta [Host: Kent Yagi]
University of Illinois, Urbana-Champaign
"Frontiers in Multi-Messenger Astrophysics at the interface of Numerical Relativity and Deep Learning"
ABSTRACT:

Gravitational wave observations with the LIGO and Virgo detectors from a succession of mergers of black holes are a triumph of experimental and theoretical physics, and data science.  Similarly, the observation of two colliding neutron stars in gravitational waves and light heralds the era of Multi-Messenger Astrophysics. In this talk I outline a vision to drive innovation at the interface of gravitational wave astrophysics, large scale astronomical surveys, deep learning and large scale computing to address outstanding theoretical and data science challenges to realize the full potential of Multi-Messenger Astrophysics.

ics High Energy
Wednesday, September 26, 2018
3:30 PM
Physics Building, Room 313
Gavin Davies [Host: Craig Group]
Indiana University
"Recent Results from the NOvA Neutrino Experiment"
 
 Slideshow (PDF)
ABSTRACT:

Neutrinos are abundant fundamental particles throughout the universe; second-most only to the photon. They undergo a phenomenon called neutrino oscillation whereby they change flavor from one type to another as they travel. The NOvA experiment seeks to elucidate further understanding of this phenomenon utilizing Fermilab's NuMI neutrino beam and two detectors to observe neutrino interactions: a 300 ton near detector underground at Fermilab, IL and a 14 kton far detector in Ash River, MN.

The NOvA experiment has recently produced updated neutrino oscillation measurements as well as its first antineutrino oscillation results and these are presented herein.

SLIDESHOW:
ics High Energy
Monday, August 20, 2018
3:30 PM
Physics Building, Room 204
Triparno Bandyopadhyay [Host: P.Q. Hung]
University of Calcutta
"Another addition to the U(1) jungle"
ABSTRACT:

In a truly model independent approach we review the class of anomaly free U(1) extensions of the SM. Parametrising the extension in terms of three observable quantities, namely, MZ′, the Z-Z′ mixing angle (alphaZ) and the extra U(1) effective gauge coupling (g'), which absorb all model dependence, we proceed to draw exclusion contours in the parameter space. For the exclusion limits we use the latest LHC DY data, unitarity, and electron--muon-neutrino scattering data. The DY data turns out to be the most stringent, but the other two constraints have situational merits, as we discuss.

ics Special Q&A Session


Wednesday, April 18, 2018
3:30 PM
Physics Building, Room 204
Melissa Henriksen [Host: Nilanga Liyanage]
Applied Research Institute
"Introduction to Applied Research Institute (ARI)"
ics High Energy
Tuesday, March 20, 2018
3:30 PM
Physics Building, Room 204
Sebastian N. White [Host: Craig Dukes]
CERN
"A new Signal Processing Initiative to be Based at CERN"
ABSTRACT:

The case for measuring the time of arrival of physics objects in the major LHC Experiments (CMS, ATLAS and TOTEM so far) has been building since it was first proposed roughly 5 years ago [?] and the LHC committee has already approved (in March 2018) for CMS to proceed to the next stage- the technical design. Along with this process there have been separately intense activities in establishing the physics performance benefits (through simulations) of this enhanced capability as well as laboratory and particle beam work to establish candidate technologies for the required level of timing precision (roughly 20-30 picosecond time resolution). A significant base for this sensor  development work has been within the “PICOSEC” collaboration, which is not part of an LHC experiment but rather evolved within 2 CERN R&D groups following a “common fund proposal” by S. White and I. Giomataris in 2014. Over the past 3 years this project has accumulated a very carefully curated data set of high quality ( 2- 5 GHz BW and 20-40 GSa/s sampling) waveforms for the principal detector technologies (Silicon with internal Gain, MicroPattern Gas structures, Micro Channel Plate PMT) and achieved world records in timing precision for all of these sensor types. We propose to build from the productive collaboration with Wolfram Research during 2017 to use this large data set to guide the design of signal processing and digitizing electronics for fast timing, which is now capturing the attention of electronics groups in the US and Europe.
 

High Energy Physics Seminars
Craig Dukes (Chair)

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