Particle Physics

If dark energy evolves in time its dynamical component could be dominated by a bath of dark radiation. Since dark energy was subdominant in the early universe, the dark energy radiation evades the usual stringent constraints on extra relativistic species from the cosmic microwave background, allowing for an O(1) fraction of the energy density today to be dark radiation. In this talk, I will discuss how dark energy radiation can emerge from a fundamental theory, its predictions for cosmological observables, as well as discovery potential and constraints with existing and future precision cosmological datasets including measurements of the cosmic microwave background, baryon acoustic oscillations, and supernova data. I’ll conclude with the prospects of measuring the particle content of the dark energy radiation in direct-detection experiments in the presence of interactions between the Standard Model and the dark radiation sector, focusing on neutrinos, axions and dark photons.

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Zoom link https://pitp.zoom.us/j/97180285756?pwd=aEtlYmFSRzFSZVBvY3lnMmtPYWc3Zz09

Higgs coupling deviations from Standard Model predictions contain information about two scales of Nature: that of new physics responsible for the deviation, and the scale where new bosons must appear. The two can coincide, but they do not have to. The scale of new bosons can be calculated by going beyond an effective field theory description of the coupling deviation. I will discuss model-independent upper bounds on the scale of new bosons for deviations in Higgs to WW and ZZ couplings, and explain how any measured deviation at present or future colliders requires the existence of new bosons within experimental reach. This has potentially interesting implications for naturalness.

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Zoom link https://pitp.zoom.us/j/97203814123?pwd=U3F3N2xxTmJSQmxIQ0Rib3ZwN3Fldz09

The QUEST-DMC experiment, aimed at detecting sub-GeV dark matter, utilizes a unique approach by employing superfluid Helium-3 (He-3) in conjunction with quantum sensors. Superfluid He-3 stands out as an ideal target medium for sub-GeV dark matter searches, especially in the context of spin-dependent interactions. This choice aligns seamlessly with a wide array of theoretically motivated dark matter models. The experiment's projected sensitivity to various dark matter models, as well as its potential to set upper limits on dark matter interactions, will be presented.

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Zoom link https://pitp.zoom.us/j/99386484623?pwd=dGVQdFJKbEpPMUcrRUNLbHdIR2p3Zz09

The rich EM phenomenology in the seconds, minutes, and hours just before, during, and after a compact object merger encodes the magnetization of the binary components, the nature of the post-merger remnant, the neutron star equation of state, the free neutron abundance, and a wide array of other compelling physics. Unfortunately, the requirement to search, find, and classify an electromagnetic counterpart within the large GW localization regions before targeted follow-up with sensitive instruments can begin, excludes access to these earliest times, even for the most well localized GW sources. The ability to promptly localize a GW source to within the field-of-view of a narrow-field sensitive facility, would enable extraordinary science. I will discuss the science cases that require extremely early time observations, and the coordination, instruments, and analyses necessary to achieve it. These include gamma-ray imaging, novel data analysis techniques, pre-merger GW detection, faster space telescopes, and new experiments.

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Zoom link https://pitp.zoom.us/j/96186614241?pwd=R0xpT0dDZVZzek5RT0x4Q1c3Z1RuUT09

The Callan Rubakov Effect describes the interaction between (massless) fermions and a smooth monopole in 4d gauge theory. In this scenario, the fermions can probe the UV physics inside the monopole core which leads to interesting effects such as proton decay in GUT models. However, the monopole-fermion scattering appears to lead to out-states that are not in the perturbative Hilbert space. In this talk, we will review this issue and propose a new physical mechanism that resolves this long-standing confusion.

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Zoom link: https://pitp.zoom.us/j/93551249905?pwd=REJvOUtTMlh6RU0vRjZnRVdZckgyZz09