******** CTCD/NTHU HEP Seminar ********

Speaker ：Dr. Shaoping Li (Osaka U.)

Title ：Neff from the dilution-resistant effect

Time ：12:30-13:30, Thursday, 2025/5/15

Place ：R521, 5F, General Building II, Nat'l Tsing Hua Univ.

Host ： Prof. Po-Yen Tseng (NTHU)

Abstract:
The effective neutrino number is a key observable characterizing the
expansion of the early universe, which can be measured by big-bang
nucleosynthesis and cosmic microwave background physics. In this talk, I
will introduce this important parameter and discuss the
dilution-resistant effect caused by new physics coupling to neutrinos.
Constraints and detection of this dilution-resistant effect will be
shown. As an interesting consequence, I will show a cosmic sandwiched
window of the lepton-number breaking scale.