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Research Interests
My current research interests broadly revolve around searches for beyond the Standard Model physics at the energy frontier. Many observations suggest that new physics is within the grasp of the LHC: the relative weakness of the gravitational force compared to the electroweak force, the cosmological abundance of dark matter, the slight imbalance of matter over antimatter in the Universe, etc. Nevertheless, no definitive signals of new physics have been found at the LHC to date. Resolving this puzzle is the thrust of my research efforts.
My research is funded by a grant from the National Science Foundation. I have also received funding through the LPC Distinguished Researcher program and the Alfred P. Sloan Foundation.
Below is a brief description of my past and present research program. Although it is not an exhaustive list, it should give a flavor for the kinds of topics that I like to investigate. In general, my research tends to be filed under the category of "exotica." From 2013–2014, I was co-convener of the Exotica Physics Group at CMS.
Physics with Photons
Since joining the CMS experiment in 2008, I have conducted a number of searches for extra dimensions by looking for a continuum excess of events in the high-mass diphoton tail [1, 2]. These searches set some of the strongest constraints on the possibility of large extra dimensions to date. Additionally, I performed the first inclusive search for dark matter at the LHC, using photons to recoil off of the dark matter particles and measure the resulting imbalance in transverse momentum [3]. I have also used photons to look for stealth supersymmetry, where the characteristic missing momentum signature is suppressed by a stealth sector and replaced with a high multiplicity of jets [4]. I am currently renewing the search for large extra dimensions in the diphoton final state, taking advantage of the newly upgraded LHC center of mass energy and using the most recent state-of-the-art calculations of the irreducible continuum background.
Physics with Jets
Dijet resonances are a powerful tool to search for new physics, since any generic s-channel resonance that is produced by quarks and gluons must decay back into them. I have made significant contributions to a number of these searches at CMS [5, 6, 7, 8] by developing the statistical inference and adding b-jet tagging as a further discriminant. I have also studied the tail of the inclusive jet transverse momentum distribution to look for jet extinction [9], a phenomena that could indicate the production of microscopic black holes at the LHC. My present work in jet physics centers around the pair-production of particles as light as 100 GeV decaying into four or more light quarks. This challenging topology is motivated by natural supersymmetry with hadronic R-parity violation and requires novel jet substructure techniques to resolve the particles.
Unconventional Signatures
One reason that may explain why new physics has been so elusive at the LHC is that the signatures are unconventional in some way and so are not being looked for. One current research avenue I am investigating is to look for light pseudoaxions, which result in striking signatures that look like a two-pronged tau lepton. Another possibility is that the new particles are long lived. Rather than being fanciful, long-lived particles are a natural solution to many quandries in particle physics today. I have recently proposed that a new dedicated detector for long-lived particles might be constructed for the high-luminosity LHC upgrade [10]. A prototype of the MATHUSLA detector concept is being constructed at CERN and will be housed at P1 above the ATLAS experiment.
Hadron Calorimetry
I have made a many contributions to the calibrations,reconstruction software, operations, and upgrade of the CMS hadron calorimeter (HCAL). Early in my career, I developed a number of algorithms to identify and reject spurious, high energy noise [11]. From 2015–2017, I was co-convener of the HCAL Detector Performance Group. Currently, I work on the interface between the HCAL and the High Level Trigger, studying noise rejection performance, and the calibration of the forward HCAL.
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Current and Former Group Members
Postdocs:
• Antonios Agapitos
• Dinko Ferencek (now research associate at Rudjer Boskovic Institute)
Graduate Students:
• Steffie Thayil (Ph.D. expected ~'21)
• Brandon Chiarito (Ph.D. expected ~'20)
• Elliot "Tote" Hughes (Ph.D. '18)
• Steven Kaplan (Ph.D. '17)
Undergraduate Students:
• Brandon Gomes ('21)
• Ali Garabaglu ('20)
• Luke Kasper ('18, now a GS a UPenn)
• Christopher Grud ('15, now a GS at UMichigan)
• Margaret Zientek ('13, now a GS at Cornell)
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