Successful Baryogenesis Research Articles

μ Problem and hybrid inflation in supersymmetric SU(2)L×SU(2)R×U(1)B−L

Abstract We present a solution of the μ problem within a supersymmetric model based on the SU (2) L × SU (2) R × U (1) B − L gauge group. We show that this solution implies a built-in hybrid inflationary scenario, which may result in a successful baryogenesis via leptogenesis. Baryon number is essentially conserved as a result of an R-symmetry. Neutrinos with mass in the eV range can provide the `hot' dark matter component.

Effective theories of MSSM at high temperature

We construct effective 3d field theories for the Minimal Supersymmetric Standard Model, relevant for the thermodynamics of the cosmological electroweak phase transition. The effective theories include a 3d theory for the bosonic sector of the original 4d theory; a 3d two Higgs doublet model; and a 3d SU(2)+Higgs model. The integrations are made at 1-loop level. In integrals related to vacuum renormalization we take into account only quarks and squarks of the third generation. Using existing non-perturbative lattice results for the 3d SU(2)+Higgs model, we then derive infrared-safe upper bounds for the lightest Higgs boson mass required for successful baryogenesis at the electroweak scale. The Higgs mass bounds turn out to be close to those previously found with the effective potential, allowing baryogenesis if the right-handed stop mass parameter mU2 is small. Finally we discuss the effective theory relevant for mU2 very small, the most favourable case for baryogenesis.

Effective theories of MSSM at high temperature

We construct effective 3d field theories for the Minimal Supersymmetric Standard Model, relevant for the thermodynamics of the cosmological electroweak phase transition. The effective theories include a 3d theory for the bosonic sector of the original 4d theory; a 3d two Higgs doublet model; and a 3d SU(2)+Higgs model. The integrations are made at 1-loop level. In integrals related to vacuum renormalization we take into account only quarks and squarks of the third generation. Using existing non-perturbative lattice results for the 3d SU(2)+Higgs model, we then derive infrared-safe upper bounds for the lightest Higgs boson mass required for successful baryogenesis at the electroweak scale. The Higgs mass bounds turn out to be close to those previously found with the effective potential, allowing baryogenesis if the right-handed stop mass parameter m U 2 is small. Finally we discuss the effective theory relevant for m U 2 very small, the most favourable case for baryogenesis.

R-parity breaking phase transition in the SUSY singlet majoron model

We consider thermal properties of the SUSY singlet majoron model. We compute the critical temperature T c and the subsequent reheating temperature T RH for R-parity breaking. Successful baryogenesis constrains the parameter space via the requirements that T c and T RH are lower than the electroweak phase transition temperature. A further constraint is provided by requiring that the gauge singlet should be kinematically allowed to decay, in order not to have a matter dominated universe at the time of nucleosynthesis. We have made a detailed study of the parameter space and find an upper limit for the SUSY breaking scalar mass m 0 ≲ 750 (900) GeV if m gluino = 100 (1000) GeV, which is valid except for certain special values of the singlet sector parameters.

Solving the cosmological moduli problem with weak scale inflation

Many models of supersymmetry breaking, including those motivated by superstring theory, involve “flat” directions which lead to particles with weak scale mass and Planck scale suppressed couplings. Coherent production of such particles can dominate the energy density in the early universe and destroy the successful predictions of nucleosynthesis. We also point out that producing a baryon density in such a scenario generally leads to an overproduction of the lightest supersymmetric particle if R-parity is conserved. We show that these problems may be solved by reducing the coherent condensate of dangerous particles through a brief period of inflation with a Hubble constant of the order of the weak scale. Furthermore the inflaton potential for such an inflation arises naturally from the same assumptions which lead to the cosmological problems, namely the existence of “flat” directions. Successful baryogenesis and preservation of density fluctuations for large scale structure formation are also possible in this scenario.

Avoiding baryon washout in the extended standard model.

It has been shown recently, in a one-loop analysis, that adding a singlet to the standard model strengthens the first-order nature of the electroweak phase transition, and thus weakens the upper limit on the Higgs boson mass required for successful baryogenesis. We demonstrate that the inclusion of ring diagrams alters the argument for a light singlet, consequently weakening the Higgs boson mass bound only up to [similar to][ital m][sub [ital W]]. However, the addition of several light singlets, or a heavy singlet, can raise the bound still further.

Massive neutrinos and electroweak baryogenesis

We show that certain models for neutrino masses that lead to the MSW explanation of the solar neutrino data and/or the hot dark matter component in the universe can also naturally allow for the successful generation of the cosmological baryon asymmetry at the electroweak scale. This follows either because the experimental Higgs boson mass limit is weakened due to the smaller production rate and the presence of sizeable invisible decays involving majoron emission, or due to the effect of additional electrically charged scalar bosons which substantially modify the condition for successful baryogenesis.