Particle Physics

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

Seminar Series Events/Videos

Oct 4 2016 - 1:00pm
Room #: 400
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Oct 4 2016 - 1:00pm
Room #: 400
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Oct 25 2016 - 1:00pm
Room #: 400
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Nov 1 2016 - 1:00pm
Room #: 400
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TBA
Nov 1 2016 - 1:00pm
Room #: 400
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Nov 8 2016 - 1:00pm
Room #: 405
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TBA
Nov 22 2016 - 1:00pm
Room #: 400
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TBA
Dec 6 2016 - 1:00pm
Room #: 400
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Dec 6 2016 - 1:00pm
Room #: 400
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Tuesday Sep 27, 2016
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In this talk, I will present a framework in which Weinberg's anthropic explanation of the cosmological constant problem also solves the hierarchy problem. The weak scale is selected by chiral dynamics that controls the stabilization of an extra dimension. When the Higgs vacuum expectation value is close to a fermion mass scale, the radius of an extra dimension becomes large, and develops an enhanced number of vacua available to scan the cosmological constant down to its observed value.

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Tuesday Sep 20, 2016
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The fundamental constants of our universe may have been set to maximize the production of similar universes, through repeated parametric variation. In this context, I will advocate that by the time the maximum entropy producer in our universe has reached maximum complexity, the majority of its energy should be re-purposed towards the production of additional universes. This builds on elements of prior proposals, including cosmological natural selection, the nonsingular universe, and the causal entropic principle.

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Tuesday Jul 26, 2016
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With the discovery of a Higgs like boson at LHC in 2012, and the lack of any statistically significant evidence of physics beyond the Standard Model so far,

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Friday Jul 15, 2016
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In this talk I will propose a new mechanism for thermal dark matter freezeout, termed Co-Decaying Dark Matter. Multi-component dark sectors with degenerate particles and out-of-equilibrium decays can co-decay to obtain the observed relic density. The dark matter density is exponentially depleted through the decay of nearly degenerate particles, rather than from Boltzmann suppression. The relic abundance is set by the dark matter annihilation cross-section, which is predicted to be boosted, and the decay rate of the dark sector particles.

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Thursday Jun 02, 2016
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We discuss how to formulate a quantum field theory of dark energy interacting with dark matter. We show that the proposals based on the assumption that dark matter is made up of heavy particles with masses which are very sensitive to the value of dark energy are strongly constrained. Quintessence-generated long range forces and radiative stability of the quintessence potential require that such dark matter and dark energy are completely decoupled.

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Tuesday May 17, 2016
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Dark matter can be a thermal relic exponentially lighter than

the weak scale without being exponentially weakly coupled. I will present

three mechanisms to obtain light thermal dark matter with sizable

self-interactions and couplings to the Standard Model.

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Tuesday May 10, 2016
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An unbroken U(1)' is a minimal possibility for a dark matter self interaction, and may even be associated with dark matter stability. However, such an interaction faces incredibly strong constraints due to collective plasma effects, which dominate over 2-to-2 scattering by an order-of-magnitude of orders-of-magnitude. I will discuss the physics of these collective effects, and show preliminary results of simulation. The constraint of such a self interaction is estimated to be nearly as weak as gravity.

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Tuesday May 03, 2016
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Effective field theories (EFT) are everywhere in particle physics. Given an EFT, the first question we ask is “what are all the operators consistent with the symmetries and degrees of freedom at a particular expansion order? In this talk I will show how this question can be attacked, and often answered, using an object called a Hilbert series.

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Tuesday Apr 26, 2016
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Astrophysical observations spanning dwarf galaxies to galaxy clusters indicate that dark matter halos are less dense in their central regions compared to expectations from collisionless dark matter N-body simulations. Using detailed fits to dark matter halos of galaxies and clusters, we show that self-interacting dark matter may provide a consistent solution to the dark matter deficit problem across all scales, even though individual systems exhibit a wide diversity in halo properties.

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Tuesday Apr 19, 2016
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The High-Energy community is only now in the process of fully appreciating the opportunities the LHC provides by producing electroweak-scale resonances beyond threshold. On the one hand this is reflected by changing from the so-called 'kappa framework’ to effective operators and on the other hand by studying Higgs and gauge boson production in processes with large momentum transfer. Accessing more exclusive phase space regions will allow to either discover New Physics or improve Higgs-boson couplings measurements.

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