Seminars - Winter 2010
January 8, 2010 (Friday) Eugene Lim,
Columbia University
February 5, 2010 (Friday) Christopher Lee,
UC, Berkeley
February 12, 2010 (Friday) Sergei Dubovsky,
Stanford CANCELLED
February 15, 2010 Mariangela Lisanti,
Stanford
March 1, 2010 (Monday) Johan Alwall, SLAC
March 5, 2010 (Friday) Spencer Chang
March 8, 2010 (Friday) Rouven Essig, Stanford
Eugene Lim, Columbia University
A New Mechanism for Cosmological Bubble Nucleation
4:00pm, 472 Willamette Hall
Refreshments served at 3:45
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Christopher Lee, UC, Berkeley
Jet Shapes as Probes of Jet Structure
(Technical Talk)
Jets of hadrons are produced both by decays of strongly-interacting new particles beyond the Standard Model and by ordinary Standard Model interactions in high-energy collisions. Discovering new physics at the Tevatron or LHC will require reliable identification of the underlying high-energy particles that produce different jets. Jet shapes are a measure of how a jet's constituents are distributed and encode information about what underlying energetic particle initiated the jet. Calculating shapes of jets defined with a jet algorithm to high precision is a challenging theoretical task in quantum chromodynamics. I describe our recent progress in applying effective field theory to the precision calculation of jet shapes, achieving a consistent factorization theorem for jet shape cross-sections and resumming perturbation series containing large logarithms of the jet shape in the limit of highly-collimated jets. As an initial demonstration of the utility of jet shapes, I illustrate how to distinguish quark-initiated and gluon-initiated jets in three-jet events in electron-positron collisions.
4:00pm, 472 Willamette Hall
Refreshments served at 3:45
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Sergei Dubovsky, Stanford
CANCELLED
Exploring String Axiverse with Precision Black Hole Physics
(Technical Talk)
4:00pm, 472 Willamette Hall
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Mariangela Lisanti, Stanford
Disentangling Dark Matter Dynamics
Joint HEP/ITS Seminar
4:00pm, 472 Willamette Hall
Refreshments served at 3:45
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Johan Alwall, SLAC
QCD Radiation and New Physics at the LHC
High-energy hadronic jets and missing transverse energy will be one of the
most important signatures for new physics at the LHC, indicating production
of heavy particles charged under QCD, with cascade decays to stable neutral
particles. Simulation and analysis of such signatures is complicated by the
presence of initial and final state QCD radiation, which can significantly
affect the expected signatures. I will present techniques to improve the
simulation of QCD radiation, and discuss the impact of QCD radiation on
signals for New physics production at hadron colliders.
4:00pm, 472 Willamette Hall
Refreshments served at 3:45
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Spencer Chang , UC, Davis
Displaced Dark Matter at the LHC
In the standard WIMP scenario for dark matter, the LHC is expected to
produce copious events where the dark matter properties can be studied. In
this talk, I discuss alternative scenarios where the dark matter is in a
hidden sector, whose density is generated by scattering processes of
particles of the visible sector. This same process at colliders can lead to
a decay of a heavy visible particle into dark matter. Interestingly,
consistent with cosmology, the decay lengths can range from prompt to
outside the detector, thus the vertices can appear in all parts of the LHC
detectors. I will demonstrate that new nontrivial analyses sensitive to
these decays are useful in many respects. In particular, observing the
position and/or timing of the displaced vertices enables reconstruction of
the spectra of supersymmetric models. In addition, the consistency of the
cosmological picture can be tested by measuring just three observables, the
mass of the dark matter and the mass and the lifetime of the particle which
decays into it. Therefore, dark matter provides a strong motivation for
improving sensitivity to displaced decays throughout the detector volume.
4:00pm, 472 Willamette Hall
Refreshments served at 3:45
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Rouven Essig, SLAC
Dark Forces
Joint HEP/ITS Seminar
4:00pm, 472 Willamette Hall
Refreshments served at 3:45
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