Bryan Travis Smith - Ph.D / MBA

Bryan Travis Smith - Ph.D / MBA

Irvine, California, United States
2K followers 500+ connections

About

Senior Data Scientist holding a Ph.D in High Energy Particle Physics and an M.S. in…

Activity

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Experience

  • Meta Graphic
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    Irvine, California, United States

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    San Francisco Bay Area

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    Menlo Park, California

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    Costa Mesa, Calfornia

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    San Francisco Bay Area

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    Sherman Oaks, Santa Monica, and La Jolla California

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    Irvine, Ca

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    Irvine, Ca

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    Orange County, California Area

Education

  • University of California, Davis - Graduate School of Management Graphic
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    Activities and Societies: UCI Triathlon Team, American Physics Society, Graduate Student Union

    I worked on research in High Energy Particle Physics focused on phenomenological signals for extensions to the standard model.

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    Activities and Societies: OMSCS

    Specializing in Machine Learning

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    Activities and Societies: American Physical Society

    Took classes in physics, math, and psychology

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Publications

  • Determining Spins of Metastable Sleptons at the Large Hadron Collider

    Phys.Rev.D76:115004,2007

    We investigate models in minimal supergravity parameter space which contain metastable sleptons. We find the luminosity required to determine the slepton spin in these scenarios, and apply our analysis to two benchmark models. We show that the spin of the slepton in one of the benchmark models can be determined with less than 30 fb$^{-1}$ of data, while the slepton spin in the other model can be determined with roughly 40 fb$^{-1}$ of data. We show how our analysis can be applied to other…

    We investigate models in minimal supergravity parameter space which contain metastable sleptons. We find the luminosity required to determine the slepton spin in these scenarios, and apply our analysis to two benchmark models. We show that the spin of the slepton in one of the benchmark models can be determined with less than 30 fb$^{-1}$ of data, while the slepton spin in the other model can be determined with roughly 40 fb$^{-1}$ of data. We show how our analysis can be applied to other models, and give an estimate of the luminosity needed for a spin determination as a function of slepton mass. This analysis can be used to distinguish supersymmetry and extra dimensions.

    Other authors
    • Arvind Rajaraman
    See publication
  • Discovering SUSY with $m_0^2 < 0$ in the First LHC Physics Run

    Phys.Rev.D75:115015,2007

    In minimal supergravity, the parameter space where the slepton is the LSP is usually neglected, because of strong constraints on charged dark matter. When the gravitino is the true LSP, this region avoids these constraints and offers spectacular collider signals. We investigate this scenario for the LHC and find that a large portion of the ignored mSugra parameter space can lead to discovery within the first physics run, with 1-4 $\text{fb}^{-1}$ of data. We find that there are regions where…

    In minimal supergravity, the parameter space where the slepton is the LSP is usually neglected, because of strong constraints on charged dark matter. When the gravitino is the true LSP, this region avoids these constraints and offers spectacular collider signals. We investigate this scenario for the LHC and find that a large portion of the ignored mSugra parameter space can lead to discovery within the first physics run, with 1-4 $\text{fb}^{-1}$ of data. We find that there are regions where discovery is feasible with only 1 day of running.

    See publication
  • Goldilocks Supersymmetry: Simultaneous Solution to the Dark Matter and Flavor Problems of Supersymmetry

    Phys.Rev.Lett.100:021302,2008

    Neutralino dark matter is well motivated, but also suffers from two shortcomings: it requires gravity-mediated supersymmetry breaking, which generically violates flavor constraints, and its thermal relic density \Omega is typically too large. We propose a simple solution to both problems: neutralinos freezeout with \Omega ~10-100, but then decay to ~1 GeV gravitinos, which are simultaneously light enough to satisfy flavor constraints and heavy enough to be all of dark matter. This scenario is…

    Neutralino dark matter is well motivated, but also suffers from two shortcomings: it requires gravity-mediated supersymmetry breaking, which generically violates flavor constraints, and its thermal relic density \Omega is typically too large. We propose a simple solution to both problems: neutralinos freezeout with \Omega ~10-100, but then decay to ~1 GeV gravitinos, which are simultaneously light enough to satisfy flavor constraints and heavy enough to be all of dark matter. This scenario is naturally realized in high-scale gauge-mediation models, ameliorates small scale structure problems, and implies that ``cosmologically excluded'' models may, in fact, be cosmologically preferred.

    See publication
  • Minimal Supergravity with m_0^2 < 0

    Phys.Rev. D74 (2006) 015013

    We extend the parameter space of minimal supergravity to negative values of m_0^2, the universal scalar mass parameter defined at the grand unified scale. After evolving to the weak scale, all scalars can be non-tachyonic with masses consistent with collider constraints. This region of parameter space is typically considered excluded by searches for charged dark matter, since the lightest standard model superpartner is a charged slepton. However, if the gravitino is the lightest supersymmetric…

    We extend the parameter space of minimal supergravity to negative values of m_0^2, the universal scalar mass parameter defined at the grand unified scale. After evolving to the weak scale, all scalars can be non-tachyonic with masses consistent with collider constraints. This region of parameter space is typically considered excluded by searches for charged dark matter, since the lightest standard model superpartner is a charged slepton. However, if the gravitino is the lightest supersymmetric particle, the charged slepton decays, and this region is allowed. This region provides qualitatively new possibilities for minimal supergravity, including spectra with light sleptons and very heavy squarks, and models in which the lightest slepton is the selectron. We show that the m_0^2 < 0 region is consistent with low energy precision data and discuss its implications for particle colliders. These models may provide signals of supersymmetry in even the first year of operation at the Large Hadron Collider.

    Other authors
    • Jonathan L. Feng
    • Arvind Rajaraman
    See publication
  • Slepton Trapping at the Large Hadron and International Linear Colliders

    Phys.Rev.D71:015004,2005

    We consider supergravity with a gravitino lightest supersymmetric particle. The next-to-lightest supersymmetric particle (NLSP) decays to the gravitino with lifetime naturally in the range 10^4 - 10^8 s. However, cosmological constraints exclude lifetimes at the upper end of this range and disfavor neutralinos as NLSPs, leaving charged sleptons with lifetimes below a year as the natural NLSP candidates. Decays to gravitinos may therefore be observed by trapping slepton NLSPs in water tanks…

    We consider supergravity with a gravitino lightest supersymmetric particle. The next-to-lightest supersymmetric particle (NLSP) decays to the gravitino with lifetime naturally in the range 10^4 - 10^8 s. However, cosmological constraints exclude lifetimes at the upper end of this range and disfavor neutralinos as NLSPs, leaving charged sleptons with lifetimes below a year as the natural NLSP candidates. Decays to gravitinos may therefore be observed by trapping slepton NLSPs in water tanks placed outside Large Hadron Collider (LHC) and International Linear Collider (ILC) detectors and draining these tanks periodically to underground reservoirs where slepton decays may be observed in quiet environments. We consider 0.1, 1, and 10 kton traps and optimize their shape and placement. We find that the LHC may trap tens to thousands of sleptons per year. At the ILC, these results may be improved by an order of magnitude in some cases by tuning the beam energy to produce slow sleptons. Precision studies of slepton decays are therefore possible and will provide direct observations of gravitational effects at colliders; percent level measurements of the gravitino mass and Newton's constant; precise determinations of the gravitino's contribution to dark matter and supersymmetry breaking's contribution to dark energy; quantitative tests of supergravity relations; and laboratory studies of Big Bang nucleosynthesis and cosmic microwave background phenomena.

    Other authors
    • Jonathan L. Feng
    See publication

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