High Energy Physics

New scalar bosons that are uncharged under the Standard Model have many phenomenological applications, and in particular may serve as mediators between the dark and visible sectors. Such scalars are often taken to have Higgs-like couplings to Standard Model fermions, in order to evade constraints from bounds on flavor-changing neutral currents.
We describe an alternative approach, based on an effective field theory approach in which a new scalar preferentially couples to a single fermion mass eigenstate. In such theories, we show through a spurion analysis that small flavor changing couplings are still technically natural. Examples of our framework include a muon-philic scalar that can explain the observed anomalous magnetic moment of the muon and an up-specific scalar mediator to a dark sector, whose phenomenologies we discuss in detail.

Bulk coherent states produced by Euclidean CFT sources can be used to study how geometry arises from entanglement: when these states obey the Ryu-Takayanagi formula, the linearized Einstein equations hold in the bulk without assuming the complete AdS/CFT correspondence.  However, the Faulkner-Lewkowycz-Maldacena bulk entanglement term that corrects the RT formula does not play a role in these previous studies, since to leading order coherent states have the same entanglement entropy as the vacuum.  We study states CFT states created by Euclidean, bilocal, double trace sources, which produce bulk squeezed states.  We consider possible modifications to RT and study divergences in the perturbative expansion that occur for certain choices of source.  We work towards determining constraints on the bulk geometry and state that arise from requiring FLM, akin to the linearized Einstein equations that arose for coherent states.

In recent years the Standard Model Effective Field Theory (SMEFT) has emerged as a well defined and systematically improvable theory to study the constraints on physics beyond the Standard Model. This formalism explains old mysteries in interpreting LEP data and offers a field theory framework to combine such data with LHC measurements of the properties of the Higgs. We discuss the current status of these combined studies. The lack of evidence for new physics resonances at LHC has also encouraged new approaches to explaining the observed value of the electroweak scale, in the presence of physics beyond the Standard Model. One such approach is the Neutrino Option, that generates the electroweak scale from an underlying Majorana scale, when Neutrino masses come about due to a seesaw mechanism. We discuss how this approach is embedded into the SMEFT.

More than 99% of the visible matter in the universe is built from protons and neutrons and the nuclei that they form. This rich structure emerges dynamically from the complex interactions of quarks and gluons, the most elementary particles that have been discovered. Understanding how nuclear physics arises from the underlying quark and gluon dynamics is a computational challenge that pushes the capabilities of the world’s largest supercomputers.

In her lecture, Dr. Shanahan will introduce the audience to the subatomic realm and describe what supercomputer calculations of quarks and gluons can reveal about the origins of mass, the primordial nuclear reactions that power the sun, and the nature of the elusive dark matter that permeates the universe.

We review the color memory effect which is the non-abelian gauge theory analog of the gravitational memory effect, in which the passage of color radiation induces a net relative SU(3) color rotation of a pair of nearby quarks. Then, we show how the color memory effect arises in Regge limit scattering processes and propose that this effect can be measured in the Regge limit of deeply inelastic scattering at electron-ion colliders.

Repeated null-results at dark matter experiments targeted at WIMP masses, have resulted in the spotlight shifting to lighter dark matter and more exotic WIMP candidates. In this talk I shall present the rich level structure of molecules and nuclei as a tool to explore MeV scale dark matter and dark forces. I will also present a novel detector concept that supplies energy to dark matter, thus accessing inelastic dark matter parameter space.

In this talk I will consider the S-matrix bootstrap of four dimensional scattering amplitudes with O(3) symmetry and no bound states and apply the formalism to pion physics. I will discuss the remarkable location where QCD seems to lie in the multi-dimensional space of zeros, scattering length and resonance mass values, based on various experimental and theoretical expectations.

We consider implications of superrotations as an asymptotic symmetry of asymptotically flat spacetimes.  Beginning with a review of the rich structure of interconnections between soft theorems, asymptotic symmetries, and                 memory effects, we describe the superrotation iteration.  The subleading soft graviton theorem can be cast as a Ward identity for this asymptotic symmetry in 4D, and also as one for the stress tensor of a putative CFT2.  We detail the change of scattering basis motivated by this asymptotic symmetry and discuss recent progress.

Among the many candidates proposed to explain the nature of Dark Matter, WIMPs have been the most supported in the last decades, because of their success in a natural explanation of the current Dark Matter abundance and their ubiquitous presence in models addressing the hierarchy problem.
Other candidates that have been attracting some attention recently are Primordial Black Holes, which would have formed in the early history of the universe.
In my talk I will touch on both frameworks for the explanation of Dark Matter.
As for WIMP candidates, I will discuss the interplay between their experimental searches and theoretical frameworks. On the side of Effective Field Theories, I propose a method to use them consistently for the recast of collider searches. On the side of simplified models, in the presence of apparent gauge anomalies at low energies I highlight the enhanced reach of indirect searches.
In the last part I will illustrate a model for the generation of PBHs relying on a feature already present in the Standard Model, the metastability of the Higgs vacuum. Another signature of this remarkable property of the SM could be the generation of a background of gravitational waves.
The observation of either of these signatures would represent a spectacular confirmation of the metastability of the Higgs vacuum.

In gauge theories, there is an inherent tension between locality and gauge invariance.   This is precisely expressed by the failure to factorize the physical Hilbert space into local tensor products.   The extended Hilbert space offers a resolution to this problem by embedding physical states into a larger Hilbert space containing gauge variant degrees of freedom.  For two dimensional TQFT's, we show how this extension fits inside the framework of extended quantum field theory, as described by the Moore-Segal axioms.  These are sewing axioms that impose a sort of spacetime covariance for the extended Hilbert space.   For the case of two-dimensional Yang Mills and it's string theory dual, we show how this framework leads to exact calculations of multi-interval modular flow,  ,negativity, and entanglement entropy.  Moreover, we given an axiomatic formulation of the "entanglement brane", which nicely compliments the worldsheet description given in previous work.

We perform a full (3+1)-dimensional numerical simulation of the axion field around the QCD epoch. Our aim is to fully resolve large dynamical non-linear effects in the inhomogenous axion field. These effects are important as they lead to large overdensities in the field at late times. Those overdensities will eventually evolve into axion minicluster, which have various phenomenological implications like microlensing events. It is therefore important to have a reliable estimate of the number of overdensities and their mass relation.