Particle Physics

I will discuss a set of calculations of dark matter interactions with low threshold semi-conductor detectors such as SENSEI and superCDMS. As a warm-up, I'll show how to rephrase traditional DM-electron scattering calculations in terms of the energy loss function of the material. We will then apply this framework to compute the rate for the Migdal effect in semi-conductor targets. This is needed because the traditional calculations of the Migdal effect do not apply in low threshold semi-conductor detectors, as the delocalized nature of the valence electrons is not taken into account.

 

Several anomalies have been recently reported by different laboratory experiments: the flavor anomalies involving B meson semileptonic and leptonic decays by the LHCb and B-factories, as well as the anomalous muon (g-2) by the Fermilab (g-2) collaboration. These deviations, if not coming from underestimated experimental or theoretical uncertainties, are pointing to new degrees of freedom around the few TeV scale. Enlarging the field content of the Standard Model may lead to baryon number violation, whose aggressive experimental constraints can rule out a wide range of attractive candidates. Motivated by its safeness under unacceptable baryon number violation and the possibility for having TeV scale physics, I will introduce the simplest theory for matter (leptons-quarks) unification based on the Pati-Salam symmetry and show how this theory can address both the flavor anomalies and the muon (g-2) with the scalar leptoquarks that it predicts.

Zoom Link: https://pitp.zoom.us/j/95090784229?pwd=Q21oQUVkeXFiSmt5S3hKcGJ3SlEyZz09

A new class of particle physics models of inflation is presented which is based on the phase transition associated with the spontaneous breaking of family symmetry responsible for the generation of the effective quark and lepton Yukawa couplings. We show

Moduli stabilization, SUSY breaking and flavor structure are discussed in 5D gauged supergravity models with two vector-multiplet moduli fields. One modulus field makes the fermion mass hierarchy while the other is relevant to the SUSY breaking mediation. We analyse the potential for the moduli from the viewpoint of the 4D effective theory to obtain the stabilized values of the moduli and their F-terms.

Parametric resonance, also known as preheating, is a plausible mechanism for bringing about the transition between the inflationary phase and a hot, radiation dominated universe. This epoch results in the rapid production of heavy particles far from thermal equilibrium and has the potential to source a significant stochastic background of gravitational radiation. Here, I present a numerical algorithm for computing the contemporary power spectrum of gravity waves generated in this post-inflationary phase transition for a large class of scalar-field driven inflationary models. I will present the results of this calculation for a number of inflationary models and discuss the (potential) observability of these models

A high energy muon collider complex can provide new and complementary discovery potential to the LHC or future hadron colliders. New spin-1 bosons are a motivated class of exotic new physics models. In particular leptoquarks, dark photons, and Lμ — Lτ models have distinct production channels at hadron and lepton machines. We study a vector leptoquark model at a muon collider with √ s = 3, 14 TeV within a set of both UV and phenomenologically motivated flavor scenarios. We compute which production mechanism has the greatest reach for various values of the leptoquark mass and the coupling between leptoquark and Standard Model fermions. We find that we can probe leptoquark masses up to an order of magnitude beyond √ s with perturbative couplings. Additionally, we can also probe regions of parameter space unavailable to flavor experiments. In particular, all of the parameter space of interest to explain recent low-energy anomalies in B meson decays would be covered even by a √ s = 3 TeV collider. We also consider other applications of a muon collider complex in the hunt for new physics.

Zoom link:  https://pitp.zoom.us/j/97081554839?pwd=bFBmdUExV0VSdm4vcm5iMTVtaTFrUT09

Cosmic strings arise as remnants of phase transitions in the early Universe, often related to theories of grand unification (GUTs). If such a phase transitions occurs at high energies, the resulting cosmic string network generates a sizable amount of gravitational waves. Most work so far has focused on the gravitational wave signal from topologically stable cosmic strings. In this talk I will introduce metastable cosmic strings, which are a generic consequence of many GUTs. I will discuss how this idea can be probed in various ongoing and upcoming gravitational wave experiments, from pulsar timing arrays to space- and ground-based interferometers. In the final part of my talk I will discuss a recent proposal on using the radio telescopes to probe this and other sources of ultra high frequency gravitational waves.

Abstract: TBD

Zoom Link: https://pitp.zoom.us/j/96516977019?pwd=WVlpZG5WTTUwbFJVZ2wvcXdNWUR5Zz09

Detecting ultralight axion dark matter has recently become one of the benchmark goals of future direct detection experiments. I will discuss a new idea to detect such particles whose mass is well below the micro-eV scale, corresponding to Compton wavelengths much greater than the typical size of tabletop experiments. The approach involves detecting axion-induced transitions between two quasi-degenerate resonant modes of a superconducting accelerator cavity. Compared to more traditional setups, the sensitivity is parametrically enhanced for ultralight axions, allowing for the exploration of vast new areas of parameter space relevant to the QCD axion and astrophysically long-ranged fuzzy dark matter.

Recently, an intriguing connection between the exceptional Jordan algebra h_3(O) and the standard model of particle physics was noticed by Dubois-Violette and Todorov (with further interpretation by Baez). How do the standard model fermions fit into this story? I will explain how they may be neatly incorporated by complexifying h_3(O) or, relatedly, by passing from RxO to CxO in the so-called "magic square" of normed division algebras. This, in turn, suggests that the standard model, with gauge group SU(3)xSU(2)xU(1), is embedded in a left/right-symmetric theory, with gauge group SU(3)xSU(2)xSU(2)xU(1). This theory is not only experimentally viable, but offers some explanatory advantages over the standard model (including an elegant solution to the standard model's "strong CP problem"). Ramond's formulation of the magic square, based on triality, provides further insights, and possible hints about where to go next.