Event Category: 4D Seminar

4D Seminar series:
Monday at 2:30 on campus

–

The first direct observations of gravitational waves (GWs) by ground-based interferometers have ushered in the era of GW astronomy. While the central focus of such experiments has been on the Hz − kHz frequency range, an exploration across a much wider spectrum is warranted. The Universe is expected to be populated by GWs over many decades in frequency, analogous to … Read More

–

Optically levitated dielectric spheres are quantum-limited impulse sensors. In this talk, I will discuss their potential to discover MeV-scale, invisible states emitted in nuclear decays, including sterile neutrinos, axions, or other nucleon-coupled scalars, as well as the possibility of carrying out precision tests of electroweak physics. I will also describe how manipulating the state of ingoing light can increase the … Read More

–

Abstract:I will discuss new ideas to directly search for light dark matter, such as the axion or the dark photon, by using quantum sensing techniques with nitrogen-vacancy (NV) centers in diamonds. Based on our previous work 2302.12756, I will demonstrate how the NV center magnetometry works, and how it can be applied to dark matter search. Also, based on some ongoing … Read More

–

abstract:The QCD axion may solve the strong CP problem and constitute the dark matter (DM) abundance in our Universe. I will discuss how the cosmology of string theory axions is fundamentally different from that of Peccei-Quinn (PQ) field theory axions. In particular, while field theory axions may form axion strings if the PQ phase transition occurs after inflation, string theory axions do not generically form strings. However, they may form … Read More

–

AbstractHiggs 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. … Read More

–

Abstract: Many motivated extensions of the standard model predict the existence of light and feably-coupled new physics. In this talk I’ll present two new searches for such particles: in the first part, I’ll outline a new search strategy for light physics coupled to muons utilizing the large flux of muons entering FASERnu, the forward component of FASER at the LHC. Next, I’ll … Read More

–

Abstract: The standard calculations of neutrino oscillation are predicated on the assumption that neutrinos’ wave packets maintain coherence throughout their propagation. Effects associated with neutrinos wave packet decoherence— specifically, damping of the oscillation probabilities—were considered unobservable in terrestrial experiments. However, recent claims suggest that if sterile neutrinos exist, we could observe decoherence effects in terrestrial experiments. To test these claims, … Read More

–

Abstract: Axion-like particles and Dark Photons are two well-motivated candidates of wave-like dark matter and are the subject of many ongoing experimental searches. Many of these rely on resonance phenomena, either directly in the lab or indirectly in astrophysical environments. We will discuss how the Earth’s well-studied ionosphere exhibits features of both of these effects. The weakly-ionised plasma allows for resonant … Read More

–

Abstract Thermal relic dark matter below ∼10 GeV is excluded by cosmic microwave background data if its annihilation to visible particles is unsuppressed near the epoch of recombination. Usual model-building measures to avoid this bound involve kinematically suppressing the annihilation rate in the low-velocity limit, thereby yielding dim prospects for indirect detection signatures at late times. In this work, we … Read More

–

Abstract: A light ( m ≲ MeV) dark fermion mixing with the Standard Model neutrinos can naturally equilibrate with the neutrinos via oscillations and scattering. In the presence of dark sector interactions, production of dark fermions is generically suppressed above BBN, but then enhanced at later times. Over much of the parameter space, we find that the dark sector equilibrates, even for … Read More