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Published byGodfrey Joseph Modified over 8 years ago
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Common problem against B and L genesis and its possible resolution M. Yoshimura Introduction 3 conditions for B asymmetry generation Sources of B non-conservation at finite T GUT, electroweak ・ Scenario of original B-genesis ・ Thermal L-genesis and general remarks ・ Possible nightmare: gravitino problem ・ Way out Conclusion
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Why are we (as a form of matter) here ? Despite that the law of microphysics is almost matter-antimatter symmetric, and Despite that in the early universe antimatter production is energetically possible and equilibrium must have been established by the laws of gravity and thermodynamics, and Despite that matter-antimatter pair annihilation is very effective
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Mystery of our existence: Generation of B-asymmetry Key quantity Is imbalance for matter a hint on some symmetry violation ?
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Absence of antimatter and problem with symmetric cosmology Observational evidence against symmetric cosmology near earth No evidence of from Theoretical problem with B-symmetric cosmology much smaller than observed No working model of domain separation p/p Ratio
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How to produce the asymmetry : 3 conditions Necessary ingredients in the early universe
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Sources of B nonconservation GUT Electroweak at high T: leading to L to B conversion @ SUSY ( Affleck-Dine mechanism)
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Electroweak damping Electroweak baryon noncnoservation suppressed at T=0 by enhanced at finite T by barrier crossing Can destroy preexisting B and L while keeping B-L Gauge and Higgs Mechanism due to level crossing of fermions caused by nontrivial gauge and higgs configuration of sphaleron and alike Electroweak baryon nonconservation
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Baryogenesis in standard model unsuppressed at finite T KM phase Out of equilibrium: 1 st order phase transition via bubble formation
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Difficulties of EW B-genesis ・ Out of equilibrium condition requires a large radiative correction to the Higgs potential to obtain a strong 1 st order phase transition, but experimental Higgs mass bound > 115 GeV excludes this possibility Magnitude too small due to KM phase alone
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Electroweak redistribution of B and L For standard model of 3 generations B-L conserved and never washed out. Original B-generation does not survive, but redistributed Opens a new possibility of L-genesis
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GUT generation of B with B-L nonconservation e.g. and its conjugate SO(10) model is OK with constraint on neutrino masses SU(5) is excluded
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Out of equilibrium condition: case of heavy particle decay One way decay, no inverse decay Otherwise, Boltzmann suppression by Typically leading to Need for high unification scale Reheating after inflation
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In GUT view, We are here, because matter that makes up us is ultimately unstable ! But, lifetime of proton typically
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L genesis and B conversion L-genesis of amount first and electroweak conversion into B, via For standard model of 3 generations Interesting in view of possible connection to observed neutrino masses
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Neutrino physics Neutrino oscillation Evidence of neutrino mass! Cosmic rays Neutrinos UpwardDownward
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Likely mechanism of small neutrino mass generation Seesaw mechanism Heavy Majorana type of masses of neutrino partner, independent of standard theory of particle physics, generates a tiny left- handed neutrino masses and mixing a la Necessarily violates lepton number conservation
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Thermal L genesis Fukugita-Yanagida Minimal extention of standard model with seesaw Right-handed Majorana decay CP asymmetry with neutrino mass matrix For 3 R-Majoranas = CP phase
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Great impacts on neutrino masses and thermal history of universe Connection to neutrino masses heaviest neutrino (WMAP 0.23eV) lightest R-neutrino Reheat temperature With hierarchy of masses, dependence on 3 parameters Giudice et al
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Delicacy of CP : Quantum interference Baryon excess from a pair of particle and antiparticle process, e.g. CP violation Rescattering phase Interference computed by Landau-Cutkovsky rule =
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Gravitino problem: a possible nightmare both for GUT B- and L-genesis Superpartner of graviton mass lifetime Usual estimate of gravitino abundance and constraint from nucleosynthesis, including hadronic decay Possible to produce heavy ?
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My favorite scenario for resolution Both baryon asymmetry and gravitino abundance was diluted before thermalization period after its violent, initial production stage during preheating
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Preheating: new understanding of entropy production before thermalization stage Non-perturbative effect of parametric resonance, leading to Complicated high energy phase of reheating, i.e. preheating 、 may be used for dilution of gravitino bundance Common to copious non-thermal production of R-Majorana neutrino for L-genesis
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Theory of particle production with chaotic potential Inflaton field oscillation given by (spatially homogeneous, periodic) Interaction by Producing a pair of particles For each momentum mode of massive particle
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Non-perturbative effect of parametric resonance, producing large mass particles ・ n-th band contribution like Large mass production possible if with large n Perturbative Born decay; from E-conservation
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Preheating stage and gravitino abundance e.g. B-generation during preheating and gravitino abundance lowed by perturbative estimate is possible
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Summary on B – L genesis (B-L) genesis is a great hint on physics beyond the standard model, linking the micro and the macro worlds B-genesis still alive, waiting for nucleon decay L-genesis interesting due to its possible connection to the neutrino sector and lepton flavor violation Watch out gravitino overproduction Some new idea necessary for relation to low energy CP violation in K and B systems
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