Particle Physics

Getting the strongest physics conclusions from collider particle physics experiments regarding the (in)consistency of the Standard Model with actual measurements requires Effective Field Theory techniques. This approach (known as the SMEFT) has been rapidly advanced in recent years, leading to new analyses of the data being executed by Atlas and CMS. The current state of the theoretical art is not precise enough as such EXP studies are continued into the future, as the measurements continue to become more precise. We need to be able to calculate more precisely in the SMEFT to keep up. After an intro to this area of research, I will discuss some recent calculations that have pushed things to the two loop level in precision for higgs production/decay in the SMEFT, and how thinking geometrically (in terms of field space connections and the resulting Higgs geometries) in EFT is the key to keep advancing the theoretical state of the art.

Zoom link:  https://pitp.zoom.us/j/99931154202?pwd=SUMzK2JIS0prNk5KaGZWakphckZhdz09

Despite first observing cosmic rays with energies above an EeV (10^18 eV) in the 1960s, the source of these particles remains an open question. Modern observatories, in particular the Pierre Auger Observatory and Telescope Array, have firmly established that the cosmic ray spectrum continues up to ~10^20.3 eV and have significantly advanced our understanding of these particles. However, limited statistics, uncertainties in particle physics, and significant deflections in the Galactic magnetic field have made progress towards discovering their astrophysical source extremely challenging. One key astrophysical input needed to understand ultrahigh energy cosmic ray data is the distribution of their sources, or the source evolution. In this talk, I will focus on multimessenger observations which have the potential to pin down the source evolution for the very first time.

Zoom Link:  https://pitp.zoom.us/j/94054513261?pwd=aHRNWE04VDI2cDA2RmRYQmtNRnd3dz09

Every time researchers have pushed the energy boundary in particle physics we have found something new about our Universe. Recently, IceCube has demonstrated that Neutrino Telescopes can use neutrinos from the cosmos as excellent tools to continue this exploration. The true potential of this field, however, remains to be realized due to limited observations of neutrinos at the highest energies. To unlock this potential, advanced detectors are needed that will push the forefront of the cosmic frontier, revealing new knowledge of extreme astrophysical phenomena, including through multi-messenger follow-up programs, and testing fundamental physics at scales well beyond those reachable by Earth-bound accelerators. The Pacific Ocean Neutrino Experiment (P-ONE) is a proposed initiative to construct one of the largest neutrino telescopes deep in the northern Pacific Ocean off the coast of British Columbia. To overcome the challenges of a deep-sea installation, we have deployed two pathfinder mooring lines STRAW and STRAW-b in 2018 and 2020. These provide continuous monitoring of optical water properties at a potential detector site in the Pacific. In this talk I will cover results from these pathfinders and discuss the status of P-ONE. 

Zoom Link:  https://pitp.zoom.us/j/91718716984?pwd=Wm00anU4UjFWd0tKYVZ0TVZ6aVMrZz09

The mixing angles of the quark sectors are constrained by unitarity in the standard model. However, recent data indicates a about 3 sigma deviation from unitarity in the mixing angle between the 1st and 2nd generation down-type quarks, known as the Cabibbo angle anomaly. The observations include the charged-current weak decays of neutrons, nuclei, kaons, and the hadronic decay of tau leptons. Although the issue appears to lie in the quark sector, modifying the neutrino sector may offer a solution. In this talk, we discuss recent findings that suggest a sterile neutrino of MeV mass mixing with the electron-type neutrino can resolve the Cabibbo angle anomaly. We also examine the current bounds and future prospects of this scenario.

Zoom Link:  https://pitp.zoom.us/j/98083942792?pwd=eHFRUmJUVGNJcVpTSHZXVXFKQm95QT09

I will discuss a novel search for axions using spectropolarimetric observations of magnetic white dwarfs (MWDs). Photons produced as thermal radiation at the MWD surface may convert into an axion as they traverse the magnetosphere, but only the component polarized parallel to the MWD magnetic field. Therefore the MWD radiation at Earth is linearly polarized perpendicular to the magnetic field direction. I detail the analysis of archival linear polarization spectra of a few nearby MWDs that excludes the axion interpretation of the TeV gamma-ray transparency anomalies. I briefly discuss the sensitivity of ongoing and future searches using dedicated data at the Lick Observatory.

Zoom Link:  https://pitp.zoom.us/j/97657182582?pwd=ZlFYWWtoYXhQZUtnOUxsZFpqMUo1Zz09

We study the low-energy effective action for relativistic superfluids obtained by integrating out the heavy fields of a UV theory. A careful renormalization procedure is required if one is interested in deriving the EFT to all orders in the light fields (at a fixed order of derivatives per field). The result suggests a general relation between finite density and spontaneous symmetry breaking for QFTs of interacting scalars with an internal global symmetry. The ground state at finite chemical potential of these systems is usually associated with a superfluid phase, in which the global symmetry is spontaneously broken along with Lorentz boosts and time translations. We show that this expectation is always realized at one loop for complex scalar fields with arbitrary UV potential in d > 2 spacetime dimensions. The physically distinct phenomena of finite charge density and spontaneous symmetry breaking occur simultaneously. We quantify this result by deriving universal scaling relations for the symmetry breaking scale as a function of the charge density, at low and high density. Moreover, we show that the critical value of μ coincides with the pole mass. The same conclusions hold non-perturbatively for an O(N) theory with quartic interactions in d = 3, at leading order in the 1/N expansion. In order to do this we compute analytically the one-loop effective potential at finite μ and zero temperature. As an application we derive in closed form the one-loop EFT for superfluid phonons for arbitrary UV scalar potentials in d > 2. From this we obtain analytically the one-loop scaling dimension of the lightest charge n operator in the $\phi^6$ conformal superfluid in d=3, at leading order in 1/n, reproducing a numerical result of Badel et al. 

Zoom Link:  https://pitp.zoom.us/j/97727675289?pwd=TWJyNzRucEhkM0JNM0NWeEdMM0xTQT09

Precision measurements of primordial correlators in the CMB, Large Scale Structure, and 21-cm cosmology may contain “on-shell" imprints of extremely heavy particle physics, with masses comparable to the inflationary Hubble scale, via the remarkable inflationary mechanism known as “cosmological collider physics”. I will describe my research in (a) finding new robust mechanisms for extending the energy range and strength of such signals, (b) identifying motivated particle physics targets that may be discoverable, (c) showing how cosmological collider physics can probe the mechanism of inflation itself, and (d) demonstrating variants of the mechanism that may be observable in new cosmological “maps”, such as stochastic gravitational wave backgrounds with significant anisotropies. While this is an ambitious program of research, there are major challenges to bring it to fruition, on the experimental, phenomenological and theoretical fronts, which I will sketch. 

Zoom Link:  https://pitp.zoom.us/j/98923687484?pwd=cjgweEhoejVCeHAvc0RBSDEvVkZldz09

SNOLAB is a laboratory two kilometers underground in Sudbury, Ontario, Canada. This laboratory boasts the lowest muon flux on Earth. This low muon flux is utilized for a variety of research on Quantum computing and the nature of dark matter, which are some of the highest priority research topics in fundamental and applied physics. New sensors are required for light dark matter searches that extend current capabilities by three orders of magnitude in energy. The required energy scales overlap with the energy scale of environmental disturbances that limit the coherence time of many candidate qubit systems, like superconducting circuits. I will give a short overview of SNOLAB. I will then focus on the requirements and alignment of light dark matter searches and cutting-edge qubit performance. Finally, I will say a few words on how future experiments can leverage these maturing quantum computing technologies for fundamental physics searches.

Zoom Link:  https://pitp.zoom.us/j/95345167872?pwd=eDhYREd2Q04yV21DUC84NnVEcHRmUT09

Gravitational waves with frequencies below 1 nHz are notoriously difficult to detect. With periods exceeding current experimental lifetimes, they induce slow drifts in observables rather than periodic correlations. Observables with well-known intrinsic contributions provide a means to probe this regime. In this talk, I will demonstrate the viability of using observed pulsar timing parameters to discover such ultralow frequency gravitational waves, presenting two complementary observables for which the systematic shift induced by ultralow-frequency gravitational waves can be extracted. I will then show the results of searches for both continuous and stochastic signals from supermassive black hole binaries using existing data for these observables, and demonstrate that this technique has the power to probe astrophysically-interesting strains.

Zoom Link:  https://pitp.zoom.us/j/95734210379?pwd=Wnp1cHR2QW93bksxaGlCWEZVSjRsUT09

A dark energy-like component in the early universe, known as early dark energy (EDE), is a proposed solution to the Hubble tension. In this talk, I will describe how a frequentist profile likelihood yields important complementary information compared to a Bayesian MCMC analysis. While in an MCMC analysis, the EDE model is clearly disfavoured by Cosmic Microwave Background and large-scale structure data, a profile likelihood analysis prefers consistently larger amounts of EDE and with that a Hubble constant consistent with the SH0ES measurement for the same data sets. The difference between MCMC and profile likelihood can be explained by prior volume effects in the MCMC analysis. I will discuss how frequentist and Bayesian methods can give important complementary information in the context of beyond-LCDM models.

Zoom link:  https://pitp.zoom.us/j/97257428766?pwd=ckx4ajRsQVRQUnpXaGEvZEtEWW9ldz09