405 research outputs found

    Scattering with Baryon Number Violation -- The Case of Higgs Particle Production --

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    \noindent A formalism based on path-integral expression of time-evolution operator during tunneling at a finite energy proposed by the authors is applied to SU(2)SU(2) gauge-Higgs system to produce Higgs particles with ΔB=1\Delta B=1. Instead of starting from instanton tunneling at the zero energy, a classical bounce solution giving sphaleron (instanton) action at high (low) energies is used as the tunneling configuration. Fourier transform of the bounce configuration in coherent state expression at the entrance and exit of the tunneling plays an important role. Numerical results at various energies for MH/MW=1∌2M_H/M_W=1 \sim 2 are given. Though the cross section with ΔB=1\Delta B=1 results from a severe cancellation of several large quantities in the leading order as occured in the instanton calculus, it seems unlikely that the cross section grows as largely as to reach unitarity bound at energies E≀EsphE \leq E_{sph}. It is pointed out that the actual value g2=0.418g^2=0.418 of the SU(2)SU(2) gauge coupling constant may be too large to take the weak coupling limit.}Comment: modified PHYZZX(included), 4 Figures (not included), SAGA-HE-46 : KYUSHU-HET-

    Chiral Charge Flux and Electroweak Baryogenesis

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    By treating CP-violating interaction of the electroweak bubble wall as a perturbative term, chiral charge flux through the bubble wall is estimated. It is found that the absolute value of the flux FQF_Q has a sharp peak at m0∌a∌Tm_0 \sim a \sim T with FQ/(uT3)∌10−3 (QL−QR) ΔξF_Q/(u T^3) \sim 10^{-3}\, (Q_L-Q_R)\,\Delta \theta. Here m0m_0 is the fermion mass, 1/a1/a is the wall thickness, TT is the temperature at which the bubbles are growing, uu is the wall velocity, QL(R)Q_{L(R)} is the chiral charge of the relevant left(right)-handed fermion and Δξ\Delta\theta is the measure of CP violation.Comment: 10 pages, 4 figures ( not included, hard copies are available upon request ), plain TeX with phyzzx

    CP-violating profile of the electroweak bubble wall

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    In any scenario of the electroweak baryogenesis, the profile of the CP violating bubble wall, created at the first-order phase transition, plays an essential role. We attempt to determine it by solving the equations of motion for the scalars in the two-Higgs-doublet model at the transition temperature. According to the parameters in the potential, we found three solutions. Two of them smoothly connect the CP-violating broken phase and the symmetric phase, while the other connects CP-conserving vacua but violates CP in the intermediate region. We also estimate the chiral charge flux, which will be turned into the baryon density in the symmetric phase by the sphaleron process

    On the mutual effect of ion temperature gradient instabilities and impurity peaking in the reversed field pinch

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    The presence of impurities is considered in gyrokinetic calculations of ion temperature gradient (ITG) instabilities and turbulence in the reversed field pinch device RFX-mod. This device usually exhibits hollow Carbon/Oxygen profiles, peaked in the outer core region. We describe the role of the impurities in ITG mode destabilization, and analyze whether ITG turbulence is compatible with their experimental gradients.Comment: 19 pages, 9 figures, accepted for publication in Plasma Phys. Control. Fusio

    Solvability and PT-symmetry in a double-well model with point interactions

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    We show that and how point interactions offer one of the most suitable guides towards a quantitative analysis of properties of certain specific non-Hermitian (usually called PT-symmetric) quantum-mechanical systems. A double-well model is chosen, an easy solvability of which clarifies the mechanisms of the unavoided level crossing and of the spontaneous PT-symmetry breaking. The latter phenomenon takes place at a certain natural boundary of the domain of the "acceptable" parameters of the model. Within this domain the model mediates a nice and compact explicit illustration of the not entirely standard probabilistic interpretation of the physical bound states in the very recently developed (so called PT symmetric or, in an alternative terminology, pseudo-Hermitian) new, fairly exciting and very quickly developing branch of Quantum Mechanics.Comment: 24 p., written for the special journal issue "Singular Interactions in Quantum Mechanics: Solvable Models". Will be also presented to the int. conference "Pseudo-Hermitian Hamiltonians in Quantum Physics III" (Instanbul, Koc University, June 20 - 22, 2005) http://home.ku.edu.tr/~amostafazadeh/workshop/workshop.ht

    Baryogenesis and CP-Violating Domain Walls in the Background of a Magnetic Field

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    Within the domain wall-mediated electroweak baryogenesis, we study fermion scattering off a CP-violating wall in the background of an uniform magnetic field. In particular, we calculate the asymmetry between the reflection coefficients for right-handed and left-handed chiral fermions, \Delta R = R_{R \to L} - R_{L \to R}, which is of relevance to non local baryogenesis mechanisms.Comment: replaced with revised conclusion version, to be published in JCA

    Phase separation of an actin nucleator by junctional microtubules regulates epithelial function

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    Liquid-liquid phase separation (LLPS) is involved in various dynamic biological phenomena. In epithelial cells, dynamic regulation of junctional actin filaments tethered to the apical junctional complex (AJC) is critical for maintaining internal homeostasis against external perturbations; however, the role of LLPS in this process remains unknown. Here, after identifying a multifunctional actin nucleator, cordon bleu (Cobl), as an AJC-enriched microtubule-associated protein, we conducted comprehensive in vitro and in vivo analyses. We found that apical microtubules promoted LLPS of Cobl at the AJC, and Cobl actin assembly activity increased upon LLPS. Thus, microtubules spatiotemporally regulated junctional actin assembly for epithelial morphogenesis and paracellular barriers. Collectively, these findings established that LLPS of the actin nucleator Cobl mediated dynamic microtubule-actin cross-talk in junctions, which fine-tuned the epithelial barrier
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