Particle Physics

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

Seminar Series Events/Videos

 

 

Tuesday Oct 20, 2020
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I discuss a new approach to the Higgs naturalness problem, where the value of the Higgs mass is tied to cosmic stability and the possibility of a large observable Universe. The Higgs mixes with the dilaton of a CFT sector whose true ground state has a large negative vacuum energy. If the Higgs VEV is non-zero and below O(TeV), the CFT also admits a second metastable vacuum, where the expansion history of the Universe is conventional.

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Tuesday Oct 13, 2020

The potential for discovering new gauge fields of nature relies upon extending the collision energy of hadron colliding beams as far as possible beyond the present 14 TeV capability of LHC.  We must seek a balance of minimum cost/TeV for the ring of superconducting magnets, feasibility and cost of a tunnel to contain the ring, and balancing the luminosity against synchrotron radiation.  Balancing feasibility, technology, and cost is crucial if there is to be a high-energy frontier for discovery of new gauge fields. Three design cases exhibit the tricky balance among these parameters:

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Tuesday Oct 06, 2020
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Hoop conjecture suggests that microscopic black holes can be produced in collisions of high energy particles if the fundamental gravity scale is lowered to the electroweak scale in extra dimension models. This opens up the possibility of studying extra dimensions in collliders and neutrino telescopes. In this talk, I will introduce the unique signatures associated with black holes from cosmic neutrino-nucleon scattering in IceCube-Gen2. These signatures include new topologies, distinct energy distributions and unusual ratios of hadronic-to-electronic energy deposition.

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Tuesday Sep 15, 2020
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Abstract TBD

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Friday Sep 11, 2020
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The axion solution to the strong CP problem also provides a natural dark matter candidate. If the Peccei-Quinn symmetry has ever been restored after inflation, topological defects of the axion field would have formed and produced relic axions, whose abundance is in principle calculable. We study the contribution to the abundance produced by string defects during the so-called scaling regime. Clear evidence of scaling violations is found, the most conservative extrapolation of which strongly suggests a large number of axions from strings.

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Tuesday Aug 11, 2020
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We revisit the physics of neutrino magnetic moments, focusing in particular on the case where the right-handed, or sterile, neutrinos are heavier (up to several MeV) than the left-handed Standard Model neutrinos. The discussion is centered around the idea of detecting an upscattering event mediated by a transition magnetic moment in a neutrino or dark matter experiment.

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Tuesday Jul 14, 2020
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In the first part of the talk I will present how to compute anomalous dimensions of EFT operators using on-shell scattering amplitudes. The method is used to compute some two loop transitions, which are important to provide a complete characterisation of the dynamics affecting some low energy precision experiments. In the second part, I show how unitarity, analycity and locality impose stringent non-trivial constraints to the space of possible EFTs, invisible at the Lagrangian level by only considering the symmetries of the IR theory.

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Tuesday Jun 23, 2020
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Neutrinos are a key (although implicit) ingredient of the standard cosmological model, LambdaCDM. Firstly, neutrinos directly participate in neutron freeze out during BBN, and secondly, they represent 40% of the energy density of the Universe after electron positron annihilation up to almost matter radiation equality. The latter fact makes neutrinos a necessary element to understand CMB observations. 

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Tuesday Jun 16, 2020
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Tuesday Jun 09, 2020
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The inference of the present expansion rate from the Cosmic Microwave Background and other early-time probes (assuming standard

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