Mass-derivative relations for leptogenesis

Abstract

In this work, a diagrammatic representation of thermal mass effects is derived from the S-matrix unitarity both in the classical and quantum Boltzmann equations. Within the example of the seesaw type-I leptogenesis, we discuss the connection of the Higgs thermal mass and the cancelations of infrared divergences in zero- and finite-temperature calculations of the right-handed neutrino decay and scattering processes.

Cutting rules on a cylinder and simplified diagrammatic approach to $CP$ violation in quantum kinetic theory

“…Including the complete list of contributions analogous to Eq. ( 12), we may observe that the sum of all 2 → 3 rates is finite as well and can be interpreted as a thermal mass effect in the 𝑁 𝑖 → 𝑙𝐻 decay [3].…”

“…Another nontrivial example of using the expansion in Eq. ( 4) in finite-temperature calculations is the diagrammatic representation of the thermal mass effects [3]. Including the top Yukawa interactions, one may, for example, consider a box diagram cut as (11) or [3]…”

“…[12][13][14] a nonrelativistic effective theory was used to include the standard model higher-order corrections. Our work [1][2][3] focuses on a newly introduced bottom-up approach, starting with the classical Boltzmann equation and using perturbative unitarity to include the quantum thermal effect and higher-order corrections.…”

Mass-derivative relations and unitarity constraints for CP asymmetries at finite temperature

“…with 𝑘 labelling the four-momentum of the 𝑡-channel Higgses. The derivative with respect to its zeroth component can be turned into the derivative with respect to the Higgs mass through [16] 𝜕 𝜕𝑘 0…”

“…Using an unconventional diagrammatic approach introduced in refs. [11,12], we formulate CP T and unitarity constraints for higher-order asymmetries, including thermal-mass effects in the leading-order asymmetry kinematics.…”