High Energy Seminar
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Room: 285
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Don't forget to vote!
Description:
<p>Thanksgiving</p>
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High-Energy Seminars
Time:
5:30am - 6:30am
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Yes - 3 days 4 hour 0 minutes before start
Description:
Joint Theory Seminar
Speaker: Dorota Grabowska (UC Berkeley)
Title: Defining Chiral Gauge Theories Beyond Perturbation Theory
Host: Xiaochuan Lu
Room: 432
Abstract: I discuss a recent proposal for nonperturbatively regulating the high-energy divergences of chiral gauge theories, a long-standing problem in quantum field theory, and its possible raminfication on Standard Model physics. The proposal is a well-defined field theoretic framework in which ordinary fermions have conventional gauge coupling while their mirror partners have extremely soft form factors. This can be implemented on the lattice by coupling five-dimensional domain wall fermions to four-dimensional gauge fields that are extended into the extra dimension via gradient flow. In the limit of an infinite extra dimension, the effective fermion operator for this construction has the expected chiral properties, namely that it obeys the Ginsparg-Wilson equation. After explaining the details of this construction, I discuss open questions about the proposal, including questions about residual coupling between the mirror and ordinary fermions via topological effects and how this might affect our understanding of Standard Model physics.
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High-Energy Seminars
Time:
8:10am - 9:10am
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Yes - 1 day 4 hour 0 minutes before start
Description:
High Energy Seminar
Speaker: Charlie Young
Title: Circular Electron Positron Collider (CEPC) and Super p-p Collider (SppC)
Host: Robin Erbacher
Room: 285
Abstract:
The Circular Electron Positron Collider (CEPC) proposed by the Institute of High Energy Physics in Beijing has as its primary goal the precise measurements of Higgs boson properties, and it can be converted subsequently to the Super proton-proton Collider (SppC). These two phases are analogous to the Future Circular Collider (FCC) studies in Europe. This talk will discuss the physics program, project status, and some technical challenges.
Description:
<p>Thanksgiving</p>
Description:
Veterans Day
User:
High-Energy Seminars
Time:
5:30am - 6:30am
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Yes - 3 days 4 hour 0 minutes before start
Description:
Joint Theory Seminar
Speaker: Riccardo Rattazzi (EPFL)
Title: Semiclassics, Goldstone Bosons and CFT data
Host: Markus Luty
Room: 432
Abstract: Hellerman et al. (arXiv:1505.01537) have shown that in a generic CFT the spectrum of operators carrying a large U(1) charge can be analyzed semiclassically in an expansion in inverse powers of the charge. The key is the operator state correpondence by which such operators are associated with a finite density
superfluid phase for the theory quantized on the cylinder. The dynamics is dominated by the corresponding Goldstone hydrodynamic mode and the derivative expansion coincides with the inverse charge expansion. I illustrate and hopefully clarify this situation by considering simple quantum mechanical analoques. I then systematize the approach by employing the coset construction for non-linearly realized space-time symmetries. Focussing on CFT3 I illustrate the case of higher rank and non-abelian groups and the computation of higher point functions. Three point function coefficients turn out to satisfy universal scaling laws and correlations as the charge and spin are varied.
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High-Energy Seminars
Time:
8:10am - 9:10am
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Yes - 1 day 4 hour 0 minutes before start
Description:
High Energy Seminar
Speaker: Nirmal Raj (Notre Dame)
Title: New Physics Anticipations in Dilepton Angular Distributions
Host: Chris Verhaaren
Room: 285
Abstract:Searches for a new resonance in kinematic distributions is an important program at the LHC. Once its mass is discovered from the location of the peak, one typically relegates to angular distributions the role of profiling its spin and chiral couplings. This approach, however, is troublesome if new physics is non-resonant, where the lack of a bump feature gives no indication as to which spectrum to first anticipate signals in. Most likely, both kinematic and angular spectra information may be needed to extract all at once the mass, spin and coupling properties. A good testing ground for this possibility is the Drell-Yan process, due to its well-understood backgrounds and small uncertainties. In this talk, I will use LHC measurements of the dilepton forward-backward asymmetry (AFB) and invariant mass spectra to corner leptoquarks (LQs), which may mediate Drell-Yan in the t-channel and yield no resonant feature. These probes, exploiting the cleanness of dileptons, are often stronger than dedicated searches through direct LQ production. The couplings of first generation LQs are best probed today by low-energy atomic parity violation measurements, but the high luminosity runs of the LHC can deliver enough precision to overtake these experiments, with the dilepton angular spectra leading the way. I will conclude with suggestions on the use of certain angular observables that may provide an unambiguous interface between theory and experiment, and help facilitate prompt interpretations of new physics.
Description:
<p>Thanksgiving</p>
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High-Energy Seminars
Time:
5:30am - 6:30am
Send Reminder:
Yes - 3 days 4 hour 0 minutes before start
Description:
Joint Theory Seminar
Speaker: Tom Melia (UC Berkeley)
Title: A heavy ion flashlight for discovering axions
Host: Xiaochuan Lu
Room: 432
Abstract: I will show that ultra-peripheral, heavy-ion collisions at the LHC can be used to search for axion-like particles with mass below 100 GeV. The Z^4 enhanced photon-photon luminosity from the ions provides a large exclusive production rate, with a signature of a resonant pair of back-to-back photons and no other activity in the detector.
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High-Energy Seminars
Time:
9:10am - 10:10am
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Yes - 1 day 4 hour 0 minutes before start
Description:
High Energy Seminar
Speaker:
Title:
Host:
Room: 285
Abstract:
Description:
<p>Thanksgiving</p>
User:
High-Energy Seminars
Time:
5:30am - 6:30am
Send Reminder:
Yes - 3 days 4 hour 0 minutes before start
Description:
Joint Theory Seminar
Speaker: Xiaochuan Lu (UC Davis)
Title: Scale Anomalies in Conformal Field Theory
Host: Christopher Verhaaren
Room: 432
Abstract: We study scale anomalies in conformal field theories. We first use Euclidean position space to show that scale anomaly coefficients can be computed in terms of CFT data (dimensions and OPE coefficients). We give an explicit expression in the form of a sum over operators, and we show that the series is not positive-definite. We then use a different approach by coupling the CFT to a weakly-coupled probe quantum field in Minkowski space. The scattering amplitudes of the probe particles are sensitive to the scale anomaly, and the optical theorem then gives an expression for the scale anomaly coefficient in terms of a positive sum of states.
User:
High-Energy Seminars
Time:
9:10am - 10:10am
Send Reminder:
Yes - 1 day 4 hour 0 minutes before start
Description:
High Energy Seminar
Speaker:
Title:
Host:
Room: 285
Abstract:
