Abstract
In this work we provide a detailed study of the CP violating phase transition (CPPT) which is a new mechanism proposed to produce a baryon asymmetry. This mechanism exploits the Weinberg operator whose coefficient is dynamically realised from the vacuum expectation values (VEVs) of new scalars. In the specific case of the first order phase transition, the scalar VEVs vary in the bubble wall which separates the two phases. This results in a spacetime varying coefficient for the Weinberg operator. The interference of two Weinberg operators at different spacetime points generates a CP asymmetry between lepton and anti-lepton production/annihilation processes, which eventually results in an asymmetry between baryon and anti-baryon number densities in the early Universe. We present the calculation of the lepton asymmetry, based on non-equilibrium quantum field theory methods, in full. We consider the influence of the bubble wall characteristics and the impact of thermal effects on the lepton asymmetry and draw a comparison between the CPPT mechanism and electroweak baryogenesis.
Highlights
Proposed by Fukugita and Yanagida [2], is one of the most widely studied explanations of the origin of the matter-antimatter asymmetry in the early universe
In this work we provide a detailed study of the CP violating phase transition (CPPT) which is a new mechanism proposed to produce a baryon asymmetry
In [76], we proposed a novel mechanism of leptogenesis which proceeds via a timevarying Weinberg operator which is present during a phase transition (PT)
Summary
In the Standard Model (SM), tiny neutrino masses may be explained by introducing higherdimensional operators. The simplest operator is the dimension-five Weinberg operator of eq (1.2) which violates lepton number and generates Majorana masses for neutrinos. In many New Physics models, the coefficient of the Weinberg operator λαβ in eq (1.2) is not a fundamental parameter; rather is dynamically realised after some scalars acquire VEVs. we will discuss how to achieve a varying Weinberg operator and introduce the mechanism of leptogenesis via the varying Weinberg operator
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