Gravitational waves from deflagration bubbles in first-order phase transitions

The walls of bubbles in a first-order phase transition can propagate either as detonations, with a velocity larger than the speed of sound, or deflagrations, which are subsonic. We calculate the gravitational radiation that is produced by turbulence during a phase transition which develops via deflagration bubbles. We take into account the fact that a deflagration wall is preceded by a shock front which distributes the latent heat throughout space and influences other bubbles. We show that turbulence can induce peak values of $\Omega_{GW}$ as high as $\sim 10^{-9}$. We discuss the possibility of detecting at LISA gravitational waves produced in the electroweak phase transition with wall velocities $v_w\lesssim 10^{-1}$, which favor electroweak baryogenesis.Comment: 13 pages, 1 figure; calculations of section IV repeated using recent results for the GW spectrum from turbulence, comments added in all sections, references added, conclusions unchange

On the nucleation of hadronic domains in the quark-hadron transition

We present numerical results on bubble profiles, nucleation rates and time evolution for a weakly first-order quark-hadron phase transition in different expansion scenarios. We confirm the standard picture of a cosmological first-order phase transition, in which the phase transition is entirely dominated by nucleation. We also show that, even for expansion rates much lower than those expected in heavy-ion collisions nucleation is very unlikely, indicating that the main phase conversion mechanism is spinodal decomposition.Comment: 4 pages, 2 images. To be published in the proceedings of SEWM 200

Effective potential at finite temperature in a constant magnetic field I: Ring diagrams in a scalar theory

We study symmetry restoration at finite temperature in the theory of a charged scalar field interacting with a constant, external magnetic field. We compute the finite temperature effective potential including the contribution from ring diagrams. We show that in the weak field case, the presence of the field produces a stronger first order phase transition and that the temperature for the onset of the transition is lower, as compared to the case without magnetic field.Comment: Expanded comments, 4 figures added. Conclusions unchanged. Version to match published pape

Effective potential at finite temperature in a constant hypermagnetic field: Ring diagrams in the Standard Model

We study the symmetry breaking phenomenon in the standard model during the electroweak phase transition in the presence of a constant hypermagnetic field. We compute the finite temperature effective potential up to the contribution of ring diagrams in the weak field, high temperature limit and show that under these conditions, the phase transition becomes stronger first order.Comment: 15 pages, 8 Postscript figure

Electroweak Baryogenesis and New TeV Fermions

New fermions, strongly coupled to the Standard Model Higgs boson provide a well motivated extension of the Standard Model (SM). In this work we show that, once new physics at heavier scales is added to stabilize the Higgs potential, such an extension of the SM can strengthen the first order electroweak phase transition and make the electroweak baryogenesis mechanism feasible. We propose a SM extension with TeV Higgsinos, Winos and Binos that satisfy the following properties: a) The electroweak phase transition is strong enough to avoid sphaleron erasure in the broken phase for values of the Higgs mass mH < 300 GeV; b) It provides large CP-violating currents that lead to the observed baryon asymmetry of the Universe for natural values of the CP-violating phase; c) It also provides a natural Dark Matter candidate that can reproduce the observed dark matter density; d) It is consistent with electroweak precision measurements; e) It may arise from a softly broken supersymmetric theory with an extra (asymptotically free) gauge sector; e) It may be tested by electron electric dipole moment experiments in the near future.Comment: LateX, 40 pages, 12 embedded postscript figures. A discussion of the stability of the Higgs potential and its connection to a possible ultraviolet completion of the model has been adde

Comparison of preserved bimatoprost 0.01% with preservative-free tafluprost: A randomised, investigator-masked, 3-month crossover, multicentre trial, SPORT II

IMPORTANCE: This study compares the efficacy and tolerability of a preservative-free prostaglandin analogue (tafluprost 15 mg/ml) to a prostaglandin analogue that uses 0.02% of benzalkonium chloride (bimatoprost 0.1 mg/ml). BACKGROUND: Different prostaglandin analogues have been commercially approved, with differences in tolerability. DESIGN: Prospective, randomised, investigator-masked, 3-month crossover, multicentre trial. PARTICIPANTS: Sixty-four patients with ocular hypertension or open-angle glaucoma were randomised to two groups, after a 4-week washout period from their current topical drop regimen. METHODS: Participants were randomised to tafluprost (Group 1; n = 33) or bimatoprost (Group 2; n = 31). At month 3, each group switched to the opposite treatment. IOP was evaluated at multiple timepoints. MAIN OUTCOME MEASURES: The primary outcome was difference in mean IOP between the two groups at the final visit. Secondary outcomes included change from baseline IOP at month 3 and month 6, difference in mean IOP at month 3 and difference in IOP at all timepoints. Safety outcomes included best-corrected visual acuity (BCVA), adverse events, ocular tolerability, optic nerve assessment and slit lamp biomicroscopy. RESULTS: Both medications significantly lowered IOP at month 6 compared to baseline: 5.4 mmHg (27%) for tafluprost and 6.8 mmHg (33%) for bimatoprost (p < 0.0001). No significant differences in any of the safety measures (including conjunctival hypearemia) were detected. CONCLUSIONS AND RELEVANCE: Bimatoprost produced a statistically significant greater IOP reduction compared to tafluprost with minimal to no difference in side effects. This should be borne in mind when weighing up the pros and cons of preserved versus preservative-free prostaglandin analogue therapy

Fermion scattering off electroweak phase transition kink walls with hypermagnetic fields

We study the scattering of fermions off a finite width kink wall during the electroweak phase transition in the presence of a background hypermagnetic field. We derive and solve the Dirac equation for such fermions and compute the reflection and transmission coefficients for the case when the fermions move from the symmetric to the broken symmetry phase. We show that the chiral nature of the fermion coupling with the background field in the symmetric phase generates an axial asymmetry in the scattering processes. We discuss possible implications of such axial charge segregation for baryon number generation.Comment: 9 pages, 3 Postscript figures, uses RevTeX4. Expanded discussion, published versio

Supercooling and phase coexistence in cosmological phase transitions

Cosmological phase transitions are predicted by Particle Physics models, and have a variety of important cosmological consequences, which depend strongly on the dynamics of the transition. In this work we investigate in detail the general features of the development of a first-order phase transition. We find thermodynamical constraints on some quantities that determine the dynamics, namely, the latent heat, the radiation energy density and the false-vacuum energy density. Using a simple model with a Higgs field, we study numerically the amount and duration of supercooling and the subsequent reheating and phase coexistence. We analyze the dependence of the dynamics on the different parameters of the model, namely, the energy scale, the number of degrees of freedom and the couplings of the scalar field with bosons and fermions. We also inspect the implications for the cosmological outcomes of the phase transition.Comment: 25 pages, 10 figures. References added and minor corrections. Version to appear in Phys. Rev.

Black hole mergers: the first light

The coalescence of supermassive black hole binaries occurs via the emission of gravitational waves, that can impart a substantial recoil to the merged black hole. We consider the energy dissipation, that results if the recoiling black hole is surrounded by a thin circumbinary disc. Our results differ significantly from those of previous investigations. We show analytically that the dominant source of energy is often potential energy, released as gas in the outer disc attempts to circularize at smaller radii. Thus, dimensional estimates, that include only the kinetic energy gained by the disc gas, underestimate the real energy loss. This underestimate can exceed an order of magnitude, if the recoil is directed close to the disc plane. We use three dimensional Smooth Particle Hydrodynamics (SPH) simulations and two dimensional finite difference simulations to verify our analytic estimates. We also compute the bolometric light curve, which is found to vary strongly depending upon the kick angle. A prompt emission signature due to this mechanism may be observable for low mass (10^6 Solar mass) black holes whose recoil velocities exceed about 1000 km/s. Emission at earlier times can mainly result from the response of the disc to the loss of mass, as the black holes merge. We derive analytically the condition for this to happen.Comment: 16 pages, accepted by MNRAS. Animations of the simulations are available at http://jilawww.colorado.edu/~pja/recoil.htm