Abstract
We consider a model of an expanding Universe in string theory that yields ‘environmental’ CPT violation for fermions, in the sense of different dispersion relations for fermions and antifermions. These are induced by a cosmological background with constant torsion provided by the Kalb–Ramond antisymmetric tensor field (axion) of the string gravitational multiplet. This effect induces different densities of neutrinos and antineutrinos while in chemical equilibrium, offering new scenarios for leptogenesis and baryogenesis even in the absence of CP violation.
Highlights
AND SUMMARYThe visible matter in the Universe is composed overwhelmingly of matter particles, with no detectable concentrations of anti-matter particles
According to the standard Big Bang theory in the absence of a primordial matter-antimatter asymmetry, matter and antimatter would have been present in equal amounts in the early radiation-dominated Universe
The observation of charge-parity (CP) violation in particle physics [1] prompted Andrei Sakharov [2] to conjecture that fundamental particle interactions could have generated a Baryon Asymmetry in the Universe (BAU), if the following conditions could all be met:
Summary
Mavromatos Theoretical Particle Physics and Cosmology Group, Department of Physics, King’s College London, Strand, London WC2R 2LS, UK. Sarben Sarkar Theoretical Particle Physics and Cosmology Group, Department of Physics, King’s College London, Strand, London WC2R 2LS, UK. We consider a model of an expanding Universe in string theory that yields ‘environmental’ CPT violation for fermions, in the sense of different dispersion relations for fermions and antifermions. These are induced by a cosmological background with constant torsion provided by the Kalb-Ramond antisymmetric tensor field (axion) of the string gravitational multiplet. This effect induces different densities of neutrinos and antineutrinos while in chemical equilibrium, offering new scenarios for leptogenesis and baryogenesis even in the absence of CP violation
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