Seminars take place Wednesdays 12:00-1:00pm in room #3481 Randall Laboratory
Organizer: Bibhushan Shakya, Uri Kol
Haipeng An (Caltech): "Searching for dark photon with dark matter detectors" | Jan 14
Dark matter detectors built primarily to probe elastic scattering of WIMPs on nuclei can also be used to search for very light (sub keV scale) and very weakly coupled particles like a massive vector boson in the dark sector (the dark photon) very weakly coupled to our sector through a kinetic mixing with the photon. In this talk, I will first review various constraints on the parameter space of the dark photon model from astrophysics and cosmology. Then I will show that dark matter detectors can be sensitive to both the dark photons emitted from the Sun and the cold dark photons as a cold dark matter candidate.
Brian Shuve (Perimeter): "Not-so-sterile Neutrinos and New Leptonic Interactions" | Jan 21
The Standard Model supplemented with three light sterile neutrinos is a well-motivated, minimal model that accounts for dark matter, baryogenesis, and neutrino masses. However, in such theories the sterile neutrinos turn out to be too sterile: their feeble interactions with the Standard Model generically result in an under-abundance of dark matter and baryons, and the theory is only consistent with cosmological observations with substantial tuning of model parameters. I show how new interactions coupled to Standard Model leptons greatly enhance the baryon and dark matter abundances, eliminating the need for tuning among parameters, and giving generic predictions for probing models of not-so-sterile neutrinos at the LHC and intensity frontier experiments.
Abhijit Gadde (IAS): "Exact Solutions of 2d Supersymmetric Gauge Theories" | Jan 28
We study dynamics of two-dimensional non-abelian gauge theories with N=(0,2) supersymmetry that include N=(0,2) supersymmetric QCD and its generalizations. For a range of parameters where supersymmetry is not dynamically broken at low energies, we give a complete description of the low-energy physics in terms of 2d N=(0,2) SCFTs using anomaly matching and modular invariance.
Michael Smolkin (Berkley): "RG flow of entanglement entropy" | Feb 4
Using the techniques of Entanglement Entropy, I will discuss recent progress in understanding of RG flows in QFT. A number of simple examples will be presented and analyzed. A special emphasis will be made on curved manifolds, the role of contact terms and open problems.
Tarek Anous (MIT): "Holographic glasses" | Feb 11
Multicentered black hole bound states have been known to exist in flat space. We show that they can also exist in spacetimes with AdS_4 asymptotics. We map out the thermodynamic stability of these black holes in a probe approximation and study their dynamics. We use this to argue that these multicentered black holes are dual to structural glass states of the dual CFT.
Joseph Bramante (Notre Dame): "Signals of asymmetric dark matter from galactic center pulsar implosions" | Feb 18
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.
Matthew Low (Chicago): "The Twin Higgs Mechanism and Composite Higgs" | Feb 25
The twin Higgs mechanism is a mechanism which removes the quadratic sensitivity of the Higgs mass to heavy states if they are symmetric under the twin symmetry. This requires the addition of a copy of the known particles which are neutral under the standard model symmetries. In typical models, like composite Higgs and supersymmetry, the new partners to cancel top loops are colored and are becoming more constrained at the LHC, putting tension on naturalness. In this talk I will discuss an implementation of the twin Higgs mechanism in composite Higgs and show that it can result in natural models without light top partners.
Madalena Lemos (Stony Brook): "Bootstrapping the 6d N=(2,0) theory" | Mar 11
The conformal bootstrap program has been very successful recently as a non-perturbative approach to study conformal field theories. In this talk I will describe the results of an upcoming paper where it is applied to six-dimensional N=(2,0) superconformal field theories. Consistency of the four-point function of the stress tensor multiplet yields numerical bounds on OPE coefficients and operator dimensions. In particular we obtain a central charge lower bound, which we believe to be saturated by an existing theory.
Daniele Alves (NYU / Princeton): "Goldstone Gauginos" | Mar 18
Dirac Gauginos are an attractive alternative to the MSSM. They have smaller radiative corrections to the Higgs soft masses, a suppression of certain colored production processes at the LHC, and ameliorated flavor constraints. Previous attempts to implement Dirac Gauginos however generically featured tachyons that could break the SM gauge symmetries. Removing those tachyons from the theory inevitably spoiled the positive properties of Dirac Gauginos. I will present a simple mechanism that realizes Dirac Gauginos and eliminates the tachyonic states. Finally, I will discuss a natural realization ofthis mechanism in SUSY QCD
Itamar Yaakov (Princeton): "Generalized indices for N=1 theories in four-dimensions" | Apr 1
I’ll describe how to define and compute Euclidean partition functions of 4d N=1 theories on spaces that look like a circle times a simple three manifold. These partition functions can be interpreted as supersymmetric indices: supertraces over the Hilbert space resulting from quantizing the theory on the three manifold, analogous to the Witten index. I’ll show how to calculate these indices using localization and describe some applications of the results.
Simon Knapen (Berkeley): "The Orbifold Higgs" | Apr 8
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.
Chiara Toldo (Columbia): "New goals for AdS black holes" | Apr 15
This talk deals with AdS black holes arising as solutions of four dimensional supergravity theories, admitting an embedding in M-theory.
I will first introduce the framework of abelian FI gauged N=2 supergravity and I will give a brief overview of the various black hole solutions found so far. Subsequently I will discuss the thermodynamics of the static thermal solutions. I will show that for a sufficiently small charge a phase transition arises between small, hairy black holes and large, less-hairy ones. A similar phase transition takes place for a newly found class of rotating AdS black holes with scalar field. I will then comment on the interpretation of this phase transition in the dual field theory by means of the AdS/CFT correspondence.
Time permitting, I will finally elaborate upon some ongoing work concerning the study of bound states of AdS black holes.
