247 research outputs found
Fast Electroweak Symmetry Breaking and Cold Electroweak Baryogenesis
We construct a model for delayed electroweak symmetry breaking that takes
place in a cold Universe with T<<100 GeV and which proceeds by a fast quench
rather than by a conventional, slow, phase transition. This is achieved by
coupling the Standard Model Higgs to an additional scalar field. We show that
the quench transition can be made fast enough for successful Cold Electroweak
Baryogenesis, while leaving known electroweak physics unchanged.Comment: 13 pages, 5 figures. Section and extra checks added, conclusions
unchanged. Published versio
Chern-Simons number asymmetry from CP-violation during tachyonic preheating
We consider the creation of non-zero Chern-Simons number in a model of the
early Universe, where the Higgs field experiences a fast quench at the end of
inflation. We perform numerical lattice simulations in the Abelian Higgs model
in 1+1 dimensions and in the SU(2)-Higgs model in 3+1 dimensions with an added
effective CP-violating term. We also comment on the appropriate choice of
vacuum initial conditions for classical simulations.Comment: 5 pages, 10 figures, to appear in the proceedings of SEWM2002.
Modified presentation of final result. Results unchange
W-Particle Distribution in ElectroWeak Tachyonic Pre-Heating
Results are presented of a numerical study of the distribution of W-bosons
generated in a tachyonic electroweak pre-heating transitionComment: Contribution to Strong and ElectroWeak Matter 2002, 5 page
Simulations of Cold Electroweak Baryogenesis: Finite time quenches
The electroweak symmetry breaking transition may supply the appropriate
out-of-equilibrium conditions for baryogenesis if it is triggered sufficiently
fast. This can happen at the end of low-scale inflation, prompting baryogenesis
to occur during tachyonic preheating of the Universe, when the potential energy
of the inflaton is transfered into Standard Model particles. With the proper
amount of CP-violation present, the observed baryon number asymmetry can be
reproduced. Within this framework of Cold Electroweak Baryogenesis, we study
the dependence of the generated baryon asymmetry on the speed of the quenching
transition. We find that there is a separation between ``fast'' and ``slow''
quenches, which can be used to put bounds on the allowed Higgs-inflaton
coupling. We also clarify the strong Higgs mass dependence of the asymmetry
reported in a companion paper (hep-ph/0604263).Comment: 18 pages, 20 figure
Quantum back-reaction of the superpartners in a large-N supersymmetric hybrid model
We study the supersymmetric hybrid model near and after the end of inflation.
As usual, we reduce the model to a purely scalar hybrid model on the level of
the classical fields. But on the level of quantum fluctuations and their
backreaction we take into account all superpartners of the waterfall field in a
large-N approximation. The evolution after slow roll displays two phases with a
different characteristic behaviour of the classical and fluctuation fields. We
find that the fluctuations of the pseudoscalar superpartner are of particular
importance in the late time phase. The motion of the waterfall field towards
its classical expectation value is found to be very slow and suggests a rather
flat potential and a stochastic force.Comment: 37 pages 19 figure
Thermal effects on slow-roll dynamics
A description of the transition from the inflationary epoch to radiation
domination requires the understanding of quantum fields out of thermal
equilibrium, particle creation and thermalisation. This can be studied from
first principles by solving a set of truncated real-time Schwinger-Dyson
equations, written in terms of the mean field (inflaton) and the field
propagators, derived from the two-particle irreducible effective action. We
investigate some aspects of this problem by considering the dynamics of a
slow-rolling mean field coupled to a second quantum field, using a \phi^2\chi^2
interaction. We focus on thermal effects. It is found that interactions lead to
an earlier end of slow-roll and that the evolution afterwards depends on
details of the heatbath.Comment: 25 pages, 11 eps figures. v2: paper reorganized, title changed,
conclusions unchanged, to appear in PR
Simulations of Cold Electroweak Baryogenesis: hypercharge U(1) and the creation of helical magnetic fields
We perform numerical simulations of Cold Electroweak Baryogenesis, including for the first time in the Bosonic sector the full electroweak gauge group SU(2)×U(1) and CP-violation. We find that the maximum generated baryon asymmetry is reduced by a factor of three relative to the SU(2)-only model, but that the quench time dependence is very similar. In addition, we compute the magnitude of the helical magnetic fields, and find that it is proportional to the strength of CP-violation and dependent on quench time, but is not proportional to the magnitude of the baryon asymmetry as proposed in the literature. Astrophysical signatures of primordial magnetic helicity can therefore not in general be used as evidence that electroweak baryogenesis has taken place
Non-perturbative construction of counterterms for 2PI-approximation
A concise method is presented for the non-perturbative computation of the
counterterms renormalising 2PI-actions. The procedure is presented for a real
scalar field up to lambda^2 order in the skeleton truncation of Gamma_2PI with
respect to the self-coupling, and in a constant symmetry breaking background.
The method is easily generalizable to field theories with arbitrary global
symmetry.Comment: 4 pages, poster presented at Strong and Electroweak Matter
(SEWM2008), Amsterdam,August 25-29 200
Cold electroweak baryogenesis with Standard Model CP violation
AbstractWe study a mechanism that generates the baryon asymmetry of the Universe during a tachyonic electroweak phase transition. We utilize as sole source of CP violation an operator that was recently obtained from the Standard Model by integrating out the quarks
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