## Two talks: "Novel approach to neutron electric dipole moment search using weak measurement" and "Self-interacting neutrinos and the expansion rate of the universe H0"

#### by Teppei Kitahara / Martin Schmaltz

*Nagoya U. & Technion / Boston U.*

##### at Special seminar

Wed, 15 Jan 2020, 10:55

Barkan Hall (adjacent to the Student Center)

#### Abstract

10:55 Refreshments

11:10 Teppei Kitahara (Nagoya U. and Technion)

"Novel approach to neutron electric dipole moment search using weak measurement"

Abstract: Weak measurement is one of the special quantum measurements, and it has been confirmed by many experiments. In the weak measurement, although data loses the statistics, the signal is amplified. We propose a novel approach in a search for the neutron electric dipole moment (EDM) by taking advantage of signal amplification in the weak measurement. Considering an analogy to the weak measurement that can measure the spin magnetic moment interaction, we examine a setup for a polarized neutron beam through an electric field with spatial gradient, where the signal is sensitive to the EDM interaction. In this talk, I will show a dedicated analysis of effects from impurities in a pre- and post-selections, and numerically investigate the impurity dependence of the signal amplification for the first time. This talk is based on an on-going project.

12:10 Lunch

13:00 Martin Schmaltz (Boston U.)

"Self-interacting neutrinos and the expansion rate of the universe H0"

Abstract: I begin my talk by reviewing measurements of the expansion rate of the universe. Recent observations cluster around two different values for H0: a faster expansion rate obtained from supernovae, strong lensing, and megamasers, and a ~7% slower rate from CMB and BAO measurements. Intriguingly, CMB and BAO measurements both rely on the theoretical prediction of a cosmological scale, the sound horizon. Thus in any model in which the theoretical prediction of the sound horizon is 7% smaller than in LCDM the H0 problem is automatically solved. Unfortunately, models which significantly alter the prediction of the sound horizon are tightly constrained by the CMB temperature and polarization perturbation spectra. I report on work to construct a model in which additional energy density in neutrinos dNeff ~ 1 is responsible for the needed decrease in the sound horizon and in which strong neutrino self-interactions allow compatibility with the CMB and BBN constraints. The talk is aimed at particle phenomenologists with limited background in cosmology.

Created on 11-01-2020 by Kats, Yevgeny (katsye)

Updaded on 11-01-2020 by Kats, Yevgeny (katsye)