Bubble Wall Profiles With More Than One Scalar Field: A Numerical Approach

We present a general numerical approach to solve the equations for bubble wall profiles in models with more than one scalar field and CP violating phases. We discuss the algorithm as well as several problems associated with it and show some profiles for demonstration found with our method.Comment: 5 pages, 3 figures, minor changes: 3 references added, formula added, discussion clarified in several point

Defending Activists at Risk: Protecting Human Rights Defenders from Threats and Violence

This paper seeks to identify protection and security strategies that can be utilized to support human rights defenders. With the intention of making this paper useful to both human rights practitioners and grantmakers, we discuss important legislation, highlight case studies and conclude with a series of best practices drawn from our experience and the recommendations of experts in the field. We hope this work stimulates needed dialogue, enhancing the safety of human rights defenders and making them more effective in their tireless efforts on behalf of others

Spherical Domain Wall formed by Field Dynamics of Hawking Radiation and Spontaneous Charging-up of Black Hole

We investigate the Hawking radiation in the gauge-Higgs-Yukawa theory. The ballistic model is proposed as an effective description of the system. We find that a spherical domain wall around the black hole is formed by field dynamics rather than thermal phase-transition. The formation is a general property of the black hole whose Hawking temperature is equal to or greater than the energy scale of the theory. The formation of the electroweak wall and that of the GUT wall are shown. We also find a phenomenon of the spontaneous charging-up of the black hole by the wall. The Hawking radiation drives a mechanism of the charge-transportation into the black hole when C- and CP-violation are assumed. The mechanism can strongly transport the hyper-charge into a black hole of the electroweak scale.Comment: 24 pages, 6 figures, LaTeX2e with elsart-style and graphicx-macr

A New Source for Electroweak Baryogenesis in the MSSM

One of the most experimentally testable explanations for the origin of the baryon asymmetry of the universe is that it was created during the electroweak phase transition, in the minimal supersymmetric standard model. Previous efforts have focused on the current for the difference of the two Higgsino fields, $H_1-H_2$, as the source of biasing sphalerons to create the baryon asymmetry. We point out that the current for the orthogonal linear combination, $H_1+H_2$, is larger by several orders of magnitude. Although this increases the efficiency of electroweak baryogenesis, we nevertheless find that large CP-violating angles $\ge 0.15$ are required to get a large enough baryon asymmetry.Comment: 4 pages, 2 figures; numerical error corrected, which implies that large CP violation is needed to get observed baryon asymmetry. We improved solution of diffusion equations, and computed more accurate values for diffusion coefficient and damping rate

Transport equations for chiral fermions to order \hbar and electroweak baryogenesis: Part I

This is the first in a series of two papers. We use the Schwinger-Keldysh formalism to derive semiclassical Boltzmann transport equations for massive chiral fermions and scalar particles. Our considerations include complex mass terms and mixing fermion and scalar fields, such that CP-violation is naturally included, rendering the equations particularly suitable for studies of baryogenesis at a first order electroweak phase transition. In part II we discuss the collision terms.Comment: 58 pages, 5 figures; earlier version broken up into two parts, Part II is hep-ph/0406140; accepted for publication in Annals of Physic

Static Solutions for Brane Models with a Bulk Scalar Field

We present static solutions of the 5-dimensional Einstein equations in the brane-world scenario by using two different approaches for the stabilization of the extra dimension. Assuming a ``phenomenological'' stabilization mechanism, that creates a non-vanishing $\hat T^5_5$ in the bulk, we construct a two-brane model, which allows both branes to have positive self-energies. We then consider a candidate theory for the dynamical stabilization, through the introduction of a massless scalar field in the bulk, which interacts with the branes. We find exact static solutions for the metric and scalar field in the bulk and demonstrate that the inter-brane distance is determined by the parameters of scalar field-brane interactions. However, these solutions are always accompanied by a correlation between the bulk cosmological constant, the brane self-energies and the interaction terms of the scalar field with the branes and thus cannot be considered as candidates for the phenomenologically viable stabilized geometry. We find that the aforementioned correlation cannot be avoided even in the case of a single-brane solution with positive self-energy where the fifth dimension ends on a singularity.Comment: 16 pages, revised version, to appear in Phys. Lett.

Semiclassical force for electroweak baryogenesis: three-dimensional derivation

We derive a semiclassical transport equation for fermions propagating in the presence of a CP-violating planar bubble wall at a first order electroweak phase transition. Starting from the Kadanoff-Baym (KB) equation for the two-point (Wightman) function we perform an expansion in gradients, or equivalently in the Planck constant h-bar. We show that to first order in h-bar the KB equations have a spectral solution, which allows for an on-shell description of the plasma excitations. The CP-violating force acting on these excitations is found to be enhanced by a boost factor in comparison with the 1+1-dimensional case studied in a former paper. We find that an identical semiclassical force can be obtained by the WKB method. Applications to the MSSM are also mentioned.Comment: 19 page

Transient domain walls and lepton asymmetry in the Left-Right symmetric model

It is shown that the dynamics of domain walls in Left-Right symmetric models, separating respective regions of unbroken SU(2)_L and SU(2)_R in the early universe, can give rise to baryogenesis via leptogenesis. Neutrinos have a spatially varying complex mass matrix due to CP-violating scalar condensates in the domain wall. The motion of the wall through the plasma generates a flux of lepton number across the wall which is converted to a lepton asymmetry by helicity-flipping scatterings. Subsequent processing of the lepton excess by sphalerons results in the observed baryon asymmetry, for a range of parameters in Left-Right symmetric models.Comment: v2 version accepted for publication in Phys. Rev. D. Discussion in Introduction and Conclusion sharpened. Equation (12) corrected. 16 pages, 3 figure files, RevTeX4 styl

Electroweak baryogenesis and the Higgs and stop masses

In this talk we review the actual situation concerning electroweak phase transition and baryogenesis in the minimal supersymmetric extension of the Standard Model. A strong enough phase transition requires light Higgs and stop eigenstates. For a Higgs mass in the range 110--115 GeV, there is a stop window in the range 105--165 GeV. If the Higgs is heavier than 115 GeV, stronger constrains are imposed on the space of supersymmetric parameters. A baryon-to-entropy ratio is generated by the chargino sector provided that the $\mu$ parameter has a CP-violating phase larger than $\sim$ 0.04.Comment: 10 pages, 6 figures, uses espcrc2.sty. Contribution to the conferences: Strong Electroweak Matter, Centre de Physique Theorique, Universite de Marseille, Marseilles (France), June 14-17, 2000; and, Thirty years of supersymmetry, Theoretical Physics Institute, School of Physics and Astronomy, Minneapolis, Minnesota (USA), October 16-27, 200

Electroweak Baryogenesis: Concrete in a SUSY Model with a Gauge Singlet

SUSY models with a gauge singlet easily allow for a strong first order electroweak phase transition (EWPT) if the vevs of the singlet and Higgs fields are of comparable size. We discuss the profile of the stationary expanding bubble wall and CP-violation in the effective potential, in particular transitional CP-violation inside the bubble wall during the EWPT. The dispersion relations for charginos contain CP-violating terms in the WKB approximation. These enter as source terms in the Boltzmann equations for the (particle--antiparticle) chemical potentials and fuel the creation of a baryon asymmetry through the weak sphaleron in the hot phase. This is worked out for concrete parameters.Comment: 46 pages, LaTeX, 11 figures, discussion of source terms and transport equations modified, version to appear in Nucl. Phys.