UC Davis Particle Physics Seminars 2013

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Poincare Invariance and Charges in Shape Dynamics Dec 10, 2012

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Shape dynamics is a theory of gravity that is generically dynamically equivalent to general relativity and yet sheds refoliaiton invariance in favor of spatial Weyl invariance. The different invariance groups has caused some puzzlement regarding the theory. In this talk, we will show how shape dynamics reproduce Poincare symmetry for a Minkowski-like curve in phase space. The asymptotic algebra is the same, but the charges for this theory acquire a new contribution to the energy that makes it Weyl invariant. The boundary conditions that allow for Poincare symmetry do not allow for a remaining conformal symmetry.

Keeping Gd-Loaded Water Crystal Clear...Indefinitely! Dec 04, 2012

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Loading a water Cherenkov detector with a water soluble gadolinium compound makes possible the detection of thermal neutrons, dramatically improving such an enhanced detector's sensitivity to anti-neutrinos fluxes from both nuclear reactors and supernova explosions. But how can the Gd-loaded water be continuously repurified, maintaining its excellent optical properties, without also removing the dissolved gadolinium? A new technology - the molecular band-pass filter - has recently been developed and is currently being industrialized. The zen and the art of Gd-loaded water - including some of the more entertaining bumps encountered along the way to a viable system - will be discussed by the inventor of this technology.

Solitons and the microscopic entropy of hairy black holes in three dimensions Dec 03, 2012

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One of the strongest evidences of the AdS/CFT correspondence is provided by three-dimensional gravity with a negative cosmological constant, whose asymptotic symmetry group is the conformal one. As a further example, one can consider gravity coupled to self-interacting scalar field having a slow fall-off at infinity. In these cases, the metric describes an asymptotically AdS spacetime in a relaxed sense as compared with the one of Brown and Henneaux. Nevertheless, the asymptotic symmetry group remains to be the same as in pure gravity. In this talk we show a wide class of scalar hairy black holes, including spinning ones, which fit in these asymptotic conditions.

How to Unlock the Hidden Photon Collider in the LHC Nov 27, 2012

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The physics reach of the LHC can be extended by detecting events in which the beam protons interact via the gamma-gamma or gluon-gluon process and remain intact. Since there is no "underlying event" background from the breakup of the protons, which occurs in typical proton interactions, this central exclusive production (CEP) mode can be used as an experimentally clean way to observe many new physics channels, such as a low-mass SUSY lepton, the Higgs boson, and anomalous production of W and Z boson pairs and to study hard-diffractive QCD physics. I will describe the upgrade effort of the CMS detector at the LHC to detect the off-momentum protons produced by these exclusive events and the expected physics performance.

Resurgence, transseries, and towards a continuum definition of QFT Nov 26, 2012

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Resolving the problems with instantons and renormalons.

Searches for 0-nu-beta-beta Decay & WIMP Dark Matter Nov 20, 2012

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Xenon is increasingly popular for both direct WIMP and 0-nu-beta-beta decay searches. Although the current trend has exploited the liquid phase, gas phase xenon offers some remarkable performance advantages for energy resolution, topology visualization, and discrimination between electron and nuclear recoils. I will describe recent results with small prototypes, indicating that NEXT-100 can provide about 0.5% FWHM energy resolution at the decay Q-value, as well as topological rejection of gamma-rays.

Mini-Split Nov 19, 2012

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An update on mini-split supersymmetry.

Metaphor for Dark Energy Nov 16, 2012

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Thinking about dark energy using 3D gravity as a toy model.

Boosted Multijet Resonances and New Color-Flow Variables Nov 13, 2012

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We use modern jet-substructure techniques to propose LHC searches for multijet-resonance signals without leptons or missing energy. We focus on three-jet resonances produced by R-parity-violating decays of boosted gluinos, showing that shape analyses searching for a mass peak can probe such gluinos up to masses of 750 GeV (650 GeV) with 20/fb (5/fb) at the LHC at 8 TeV. This complements existing search strategies, which also include counting methods that are inherently more prone to systematic uncertainties. Since R-parity-violating gluinos lighter than all squarks hadronize before decaying, we introduce new color-flow variables, "radial pull" and "axis contraction", which are sensitive to the color structure of the R-hadron's decay. The former measures the inward pull of subjets in a fat jet, while the latter quantifies the inward drift of the N-subjettiness axes when changing the distance measure. We show that they can dramatically improve the discrimination of a boosted gluino signal.

Searching for Supersymmetry with Final State Photons at ATLAS Nov 06, 2012

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Bruce Schumm describes the ATLAS search for SUSY using photons.

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