Particle Physics

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

Seminar Series Events/Videos

Currently there are no upcoming talks in this series.

 

Tuesday Apr 21, 2015
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As an experimentalist involved in the search for physics beyond the Standard Model at the LHC, one must choose carefully which signatures to pursue. While theoretical guidance in identifying well motivated gaps in the coverage of “natural” BSM extensions is an important ingredient in this choice, unexplored territory is often unexplored for a reason, namely that there are likely non-trivial (“tricky”) experimental difficulties. One must thus consider the risk (time) vs. reward (discovery) in deciding what to pursue.

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Thursday Mar 26, 2015
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The presence of an instability in the Standard Model Higgs potential may have important implications for inflation and the viability of our Universe. In particular, if the Hubble scale during inflation is comparable to (or larger than) the instability scale of the potential, quantum fluctuations in the Higgs field will lead to the Higgs sampling the unstable part of the potential during inflation. However, to correctly study transitions to the unstable regime and determine the significance for the resulting universe requires addressing a number of subtleties.

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Tuesday Mar 17, 2015
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With the increase of the center-of-mass energy from 8 TeV
to 13 TeV for LHC Run 2, the probability for boosted topologies will
become even higher than in Run 1. This also comes with a large
increase in pileup from the increased luminosity. This talk
investigates the state of the art of boosted algorithms and grooming
techniques, addresses shortcomings and possible improvements, and
discusses hot-topic items that will be interesting early on in Run 2.

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Tuesday Mar 10, 2015
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I will talk about the physics of models in which dark matter consists of composite bound states carrying a large conserved dark “nucleon” number. The properties of sufficiently large dark nuclei may obey simple scaling laws, and this scaling can determine the number distribution of nuclei resulting from Big Bang Dark Nucleosynthesis. For plausible models of asymmetric dark matter, dark nuclei of large nucleon number, e.g. >~ 10^8, may be synthesised, with the number distribution taking one of two characteristic forms, which interestingly are broadly independent of initial conditions.

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Tuesday Mar 03, 2015
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It is not known how to explain the excess of matter over antimatter with the Standard Model.  This matter asymmetry can be accounted for in certain extensions of the Standard Model through the mechanism of electroweak baryogenesis (EWBG), in which the extra baryons are created in the early Universe during the electroweak phase transition.  In this talk I will review EWBG, connect it to theories of new physics beyond the Standard Model, and show that in many cases the new particles and interactions required for efficient EWBG can be discovered using existing and expected data from the LHC.

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Friday Feb 27, 2015
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I will describe a new collider object we have termed emerging jets.
These can arise when there is a confining dark sector connected to the
Standard Model by a TeV scale mediator, a scenario that is well
motivated by dark matter considerations. The signature of an emerging
jet is O(10) displaced vertices inside the jet each with different
impact parameter, and a small number of prompt tracks. I will describe
strategies that can be used to discover emerging jets even if they
have very small cross sections.

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Tuesday Feb 24, 2015
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We introduce and systematically study an expansive class of "orbifold Higgs" theories in which the weak scale is protected by accidental symmetries arising from the orbifold reduction of continuous symmetries. The protection mechanism eliminates quadratic sensitivity of the Higgs mass to higher scales at one loop (or more) and does not involve any new states charged under the Standard Model.

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Friday Feb 20, 2015
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The Higgs boson was discovered at the LHC more than two years ago.
So far, the LHC data is consistent with the Standard Model (SM)
predictions. Given its increased rate in the next run of the LHC
with a center-of-mass energy of 14 TeV, double Higgs production will
become an important channel in the search for deviations from the SM
due to new heavy particles. The study of double Higgs production is
also important for understanding the structure of the scalar potential.
In this talk, I will review the production mechanism of double Higgs

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Tuesday Feb 17, 2015
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The Higgs couplings to fermions are known parameters within the Standard Model. Deviations from these
expectations would be clear signals of new physics and are thus important target measurements for the LHC program. 
In this talk I shall discuss ways to extra information about the coupling of the Higgs boson to the charm quark with
emphasis on methods applicable with the available LHC data set. A novel method based on the current ATLAS and CMS
Hbb measurement will be presented and compared to our knowledge so far.  Future projections and the even more

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Tuesday Jan 20, 2015
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If dark matter is asymmetric, fermionic, and self-interacting, it may form black holes in pulsars at the galactic center. In this case, a measurable maximum attainable pulsar age would track the density of the dark matter halo, with the oldest pulsars being allowed in the least dense parts of the halo. This could explain a recent observation, that there are not as many pulsars in the galactic center as expected.

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