Neutrino non-standard interactions meet precision measurements of Neff

• Published in: The journal of high energy physics Vol. 2021; no. 5
• Main Authors: Du, Yong, Yu, Jiang-Hao
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2021; Springer Nature B.V
• Subjects: Classical and Quantum Gravitation; Coherent scattering; Constraints; Decoupling; Dictionaries; Elementary Particles; Experiments; Field theory; High energy physics; Inelastic scattering; Integrals; Neutrinos; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Quarks; Regular Article - Theoretical Physics; Relativity Theory; String Theory; Theoretical physics; Cosmology of Theories beyond the SM; Neutrino Physics; Effective Field Theories; Beyond Standard Model
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP05(2021)058

A bstract The number of relativistic species, N eff , has been precisely calculated in the standard model, and would be measured to the percent level by CMB-S4 in future. Neutral-current non-standard interactions would affect neutrino decoupling in the early Universe, thus modifying N eff . We parameterize those operators up to dimension-7 in the effective field theory framework, and then provide a complete, generic and analytical dictionary for the collision term integrals. From precision measurements of N eff , the most stringent constraint is obtained for the dimension-6 vector-type neutrino-electron operator, whose scale is constrained to be above about 195 (331) GeV from Planck (CMB-S4). We find our results complementary to other experiments like neutrino coherent scattering, neutrino oscillation, collider, and neutrino deep inelastic scattering experiments.