Winter 2015 Seminar Series
Unless otherwise noted, seminars are at 4pm on Tuesdays in 472 Willamette and are preceded by cookies at 3:45.
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January 6 Tuesday
First Measurement of Electroweak Vector Boson Scattering and Potential for New Physics Discovery at ATLAS
Brookhaven National Laboratory
472 Willamette Hall
The announcement of the Higgs discovery in July 2012 was a monumental achievement for High Energy Physics. Even if the recently discovered boson turns out to be the Higgs boson, its role in electroweak scattering of two vector bosons (V=W,Z) still needs to be experimentally established to confirm the Standard Model nature of electroweak symmetry breaking. The process was measured for the first time by ATLAS in the same (electric charge) sign WW (ssWW) channel. For future runs of the Large Hadron Collider (LHC) at CERN, this channel will also be a rich place to look for new physics via the anomalous quartic gauge couplings (aQGC) in an Effective Field Theory. The first measurement of electroweak VV scattering in the ssWW channel and the limits on aQGC with ?s = 8 TeV with the ATLAS Detector at the LHC will be presented, followed by a look at the potential prospects for discovering new physics in the ssWW channel for the planned High-Luminosity LHC.
January 16 Friday
Theory of non-equilibrium dynamics and the Higgs mode in condensed matter physics
110 Willamette Hall
Pump-probe laser spectroscopy, so far largely limited to the field of atomic and molecular physics, is gaining a surging interest in condensed matter physics. In this talk I will discuss two important achievements in a theoretical understanding of non-equilibrium dynamics that does not rest on any equilibrium assumptions. One of its potentials is as a method for probing the so-called electron-phonon coupling—the dynamics of interaction between electrons and quantum modes of collective vibrations of the atomic nuclei in a solid-state material, crucial to the understanding of, for example, superconductivity among many phenomena. But, how to make sense of the “movies” obtained in this way remains a fundamental challenge. In this talk, I will discuss a significant step in the development of a concrete and general understanding of pump-probe spectroscopy studies of electron-phonon coupling. I will specifically show that this mains a viable route to directly uncover the Higgs mode in a superconductor. While equilibrium band gap engineering has become a major theme since the first synthesis of monolayer graphene, it was only recently proposed that circularly polarized laser light could turn trivial equilibrium bands into topological non-equilibrium bands. I will discuss simulations that observe ultrafast band openings and closings accompanied by changes in Berry's curvature that can be tracked in real time. Since we are focused on the physics of chiral Dirac fermions, these results apply equally to all systems possessing Dirac points, such as surface states of topological insulators.
February 3 Tuesday
Dark Matter in Dilepton Production
University of Oregon
472 Willamette Hall
At the LHC a standard search channel for new physics is the production of a pair of leptons. New resonances or contact operators can be gleaned from peaks or broad deviations respectively in the invariant mass distribution of this channel. I'll demonstrate in this talk how hidden sectors can show up in dileptonic events through radiative corrections to the Standard Model process, giving rise to spectacular features in the invariant mass as well as in the angular distributions. One compelling possibility that can be probed is that of dark matter with scalar messengers coupling it to the quarks and leptons. I will present constraints from dilepton spectrum measurements at the LHC and dark matter experiments, and make predictions for sensitivities at the high luminosity 14 TeV LHC as well as a 100 TeV collider.
Last modified: Fr Aug 27 17:54:31 PDT 2010
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