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Particle Physics

This series consists of talks in the areas of Particle Physics, High Energy Physics & Quantum Field Theory.

Seminar Series Events/Videos

TBA
avr 29 2014 - 1:00pm
Room #: 400
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Mardi avr 15, 2014
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I'll present a proof-of-concept new technique for tagging boosted objects which decay into two colored particles based on the wavelet transform. It is able to moderately improve the sensitivity of searches for such particles by 6-7%. I will also discuss future directions of applicability.

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Mercredi mar 26, 2014
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Past studies have identified a spatially extended excess of ~1-3 GeV gamma rays from the Galactic Center and inner Galaxy, consistent with the emission expected from annihilating thermal relic dark matter. I will describe recent improvements in the characterization of this signal, which demonstrate that it is spherically symmetric, centered on the Galactic Center, and with a spatial profile consistent with annihilation from a cusped NFW profile.

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Mardi mar 25, 2014
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The weak gravity conjecture (WGC) asserts a powerful consistency condition on gauge theories coupled to quantum gravity: an Abelian, long-range force requires a state of charge q and mass m such that q > m/mPl. Failure of this condition implies the existence of stable black hole remnants and is in tension with no-hair theorems. In this paper, we argue that the WGC creates a non- perturbative obstruction to naturalness, which is the notion that dimensionless coefficients should take on O(1) values in the absence of enhanced symmetry.

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Mardi mar 18, 2014
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The simplest black hole solution in asymptotic AdS spacetime, the eternal 3-dimensional BTZ black hole, is studied from the viewpoint of AdS/CFT duality. We identify a class of non-local correlators on the CFT side that allow us to generalize the notion of quantum gravity "S-matrix" to scattering inside the horizon. Since the interior of the horizon is a cosmological spacetime with a big bang/crunch-like singularity, our construction can be interpreted as identifying generally coordinate invariant observables of quantum gravity in a simple cosmology.

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Mardi fév 25, 2014
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The production of gravitational waves from cosmic inflation > is normally bounded by the inflaton field excursion. This relation, > which is often referred to as the Lyth bound, claims that > observationally large gravitational waves are produced only if the > inflaton has a super-Planckian field range. In this talk I will point > out that this general belief is not necessarily true when there are > additional light fields producing density perturbations.

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Vendredi fév 21, 2014
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We propose a very simple reformulation of General Relativity, which completely sequesters from gravity {\it all} of the vacuum energy from a matter sector, including all loop corrections and renders all contributions from phase transitions automatically small. The idea is to make the dimensional parameters in the matter sector functionals of the 4-volume element of the universe. For them to be nonzero, the universe should be finite in spacetime.

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Jeudi jan 16, 2014
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Discovery of the Higgs boson and lack of discovery of superpartners in the first run at LHC are both predictions of split supersymmetry with thermal dark matter. We discuss what it would take to find gluinos at hadron supercolliders, including the LHC at 14 TeV center of mass energy, and future pp colliders at 100 TeV and 200 TeV. We generalize the discussion by re-expressing the search capacity in terms of gluino to lightest superpartner mass ratio, and apply results to other scenarios, such as gauge mediation and mirage mediation.

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Vendredi déc 06, 2013
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I will present recent and ongoing work in collaboration with Tsutomu Yanagida and Simeon Hellerman (arXiv:1309.0692 and 1312.xxxx) on a new way to obtain charge quantization, without a GUT or monopole solution. In the CP^1 model, SU(2)_G/U(1)_H, consistency conditions for a charged field and its transformation properties over the entire group manifold lead to a charge quantization condition. By gauging the U(1)_H and identifying it with hypercharge, we find charge quantization in the SM without a monopole or GUT, purely from the structure and dynamics of the nonlinear sigma model.

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Jeudi déc 05, 2013
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The discovery of a perturbatively-coupled, 125 GeV Higgs, together with the absence of LHC signals for supersymmetry, places the principle of naturalness under tension. In this talk I will discuss the possibility that the weak scale is unnatural, with its value determined environmentally in the landscape. In particular, this environmental selection may be driven by BBN: as the weak scale is increased, the abundance of Hydrogen in the early universe is rapidly depleted.

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Jeudi déc 05, 2013
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The discovery of the Higgs boson marks the first direct probe into the mechanism of electroweak symmetry breaking. All evidence currently points to the fact that electroweak symmetry is broken by at least one fundamental scalar, and naturalness remains the most compelling reason to expect additional degrees of freedom at the weak scale.

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