Theory Seminar (High Energy/Cosmology)

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Events During the Week of April 3rd through April 10th, 2016

Monday, April 4th, 2016

No events scheduled

Tuesday, April 5th, 2016

Lepton Jets from Radiating Dark Matter
Time: 3:30 pm
Place: 5280
Speaker: Malte Buschmann, Fermilab
Abstract: The idea that dark matter forms part of a larger dark sector is very intriguing, given the high degree of complexity of the visible sector. We discuss lepton jets as a promising signature of an extended dark sector. As a simple toy model, we consider an O(GeV) DM fermion coupled to a new U(1)' gauge boson (dark photon) with a mass of order GeV and kinetically mixed with the Standard Model photon. Dark matter production at the LHC in this model is typically accompanied by collinear radiation of dark photons whose decay products can form lepton jets. We analyze the dynamics of collinear dark photon emission both analytically and numerically. In particular, we derive the dark photon energy spectrum using recursive analytic expressions, using Monte Carlo simulations in Pythia, and using an inverse Mellin transform to obtain the spectrum from its moments. In the second part, we simulate the expected lepton jet signatures from radiating dark matter at the LHC, carefully taking into account the various dark photon decay modes and allowing for both prompt and displaced decays. Using these simulations, we recast two existing ATLAS lepton jet searches to significantly restrict the parameter space of extended dark sector models, and we compute the expected sensitivity of future LHC searches.
Host: Yang Bai
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Wednesday, April 6th, 2016

No events scheduled

Thursday, April 7th, 2016

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Friday, April 8th, 2016

Fermion masses and mixings in F-theory GUTs
Time: 2:00 pm
Place: 5280 Chamberlin Hall
Speaker: Gianluca Zoccarato, Instituto de Fisica Teorica, Madrid
Abstract: In this talk I will discuss the structure of Yukawa couplings in local SU(5) F-theory models with E7 and E8 enhancement. In these models the whole flavour structure for the MSSM charged fermions is encoded in a small region of the entire compactification space. While only one generation of quarks and leptons acquires mass after taking into account non-perturbative effects the other two families acquire a mass which is hierarchically smaller compared to the mass of the first generation.
I will show that there is a unique model embeddable both in E7 and in E8 with a good hierarchical structure for the fermion masses. Finally I will discuss the structure of the CKM matrix for this particular model.
Host: Pablo Soler
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