Search Talks

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.

Using holography, I will describe an approach for understanding the physics of a big bang singularity by translating the problem into the language of the dual quantum field theory. Certain two-point correlators in the dual field theory are sensitive to near-singularity physics in a dramatic way, and this provides an avenue for investigating how strong quantum gravity effects in string theory might modify the classical description of the big bang.

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. A possible consequence of these scenarios is alterations to direct detection signals, which may be coherently enhanced (relative to collider signals), and could be modified by new momentum-dependent form factors. Inelastic interactions between dark matter states might also be important in astrophysical settings.

The talk will be based on a work in progress with Stefano Kovacs
(Dublin IAS) and Yuki Sato (Wits University). In a previous work
(arxiv:1310.0016) we have shown that,
in the M-theory regime (large N with the Chern-Simon level k fixed)
of the duality between ABJM theory and M-theory on AdS4 x S7/Zk,
certain monopole operators with large R charges on the gauge theory side
correspond to spherical membranes
(which is in general in non-BPS excited states) in the pp-wave matrix
model on the dual side.

Having in mind application to
the study of three point functions of the monopole operators
from the dual side, we study the BPS instanton equation
of the pp-wave matrix model. The instanton equation describes, for example,
a process in which a single spherical membrane splits into
two spherical membranes. Under a certain
approximation which is valid when the matrix size is large,
the instanton equation can be recast
into a three dimensional Laplace equation;
a time snapshot of the membrane configuration corresponds
to an equipotential surface of the solution of the Laplace equation.
In order to study the above mentioned splitting process,
we found that one has to introduce a special boundary condition
of the Laplace equation: one prepares two copies of
three dimensional space which are connected in a manner analogous
to Riemann surfaces. We will discuss an exact solution
of the Laplace equation under this boundary condition, and 
the corresponding instanton solution, in which a membrane splits into two.

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.

In this talk I will describe recent work with Almheiri and Dong, where we proposed a connection between the emergence of bulk locality in AdS/CFT and the theory of quantum error correction. Bulk notions such as Bogoliubov transformations, location in the radial direction, and the holographic entropy bound all have natural CFT interpretations in the language of quantum error correction.  Time permitting, I will also discuss work in progress with Pastawski, Preskill, and Yoshida on a new class of stabilizer codes that explicitly realize many of the properties we argued the AdS/CFT error correcting code should have.  

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.