25 research outputs found

    Baryon asymmetry at the weak phase transition in presence of arbitrary CP violation

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    We consider interactions of fermions with the domain wall bubbles produced during a first order phase transition. A new exact solution of the Dirac equations is obtained for a wall profile incorporating a position dependent CP violating phase. The reflection coefficients are computed, a resonance effect is uncovered for rapidly varying phases. This resonance effect happens when the energy and mass of the incident particles are E/m=Δθ/2E/m=\Delta\theta/2. Where Δθ\Delta\theta is the phase variation across the wall width. We calculate the chiral charge flux through the wall surface and the corresponding baryon asymmetry of the Universe. It agrees in sign and magnitude with the observed baryonic excess ρB/s1010\rho_B/s\approx 10^{-10} for a large range of parameters and CP violation. As a function of Δθ\Delta\theta, the ratio ρb/s\rho_b/s reach a maximum for Δθ24π\Delta\theta\approx 2-4\pi and mmtopm\approx m_{top}. PACS: 11.27.+d, 03.65.-w, 02.30.Hq, 02.30.Gp, 11.30.Fs, 98.80.CqComment: 23 pages, 7 eps figures (epsfig macro neccesary) also avalaible at http://www-itp.unibe.ch/~torrent

    Hamevol1.0: a C++ code for differential equations based on Runge-Kutta algorithm. An application to matter enhanced neutrino oscillation

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    We present a C++ implementation of a fifth order semi-implicit Runge-Kutta algorithm for solving Ordinary Differential Equations. This algorithm can be used for studying many different problems and in particular it can be applied for computing the evolution of any system whose Hamiltonian is known. We consider in particular the problem of calculating the neutrino oscillation probabilities in presence of matter interactions. The time performance and the accuracy of this implementation is competitive with respect to the other analytical and numerical techniques used in literature. The algorithm design and the salient features of the code are presented and discussed and some explicit examples of code application are given.Comment: 18 pages, Late

    KamLAND Bounds on Solar Antineutrinos and neutrino transition magnetic moments

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    We investigate the possibility of detecting solar electron antineutrinos with the KamLAND experiment. These electron antineutrinos are predicted by spin-flavor oscillations at a significant rate even if this mechanism is not the leading solution to the SNP. KamLAND is sensitive to antineutrinos originated from solar 8{}^8B neutrinos. From KamLAND negative results after 145 days of data taking, we obtain model independent limits on the total flux of solar electron antineutrinos $\Phi({}^8 B)< 1.1-3.5\times 10^4 cm^{-2}\ s^{-1},morethanoneorderofmagnitudesmallerthanexistinglimits,andontheirappearanceprobability, more than one order of magnitude smaller than existing limits, and on their appearance probability P<0.15%(95antineutrinoproductionbyspinflavorprecession,thisupperboundimpliesanupperlimitontheproductoftheintrinsicneutrinomagneticmomentandthevalueofthesolarmagneticfield (95% CL). Assuming a concrete model for antineutrino production by spin-flavor precession, this upper bound implies an upper limit on the product of the intrinsic neutrino magnetic moment and the value of the solar magnetic field \mu B< 2.3\times 10^{-21}MeV95LMA MeV 95% CL (for LMA (\Delta m^2, \tan^2\theta)values).Limitsonneutrinotransitionmomentsarealsoobtained.Forrealisticvaluesofotherastrophysicalsolarparameterstheseupperlimitswouldimplythattheneutrinomagneticmomentisconstrainedtobe,inthemostconservativecase, values). Limits on neutrino transition moments are also obtained. For realistic values of other astrophysical solar parameters these upper limits would imply that the neutrino magnetic moment is constrained to be, in the most conservative case, \mu\lsim 3.9\times 10^{-12} \mu_B(95CL)forarelativelysmallfield (95% CL) for a relatively small field B= 50kG.Forhighervaluesofthemagneticfieldweobtain: kG. For higher values of the magnetic field we obtain: \mu\lsim 9.0\times 10^{-13} \mu_Bforfield for field B= 200kGand kG and \mu\lsim 2.0\times 10^{-13} \mu_Bforfield for field B= 1000$ kG at the same statistical significance.Comment: 13 pages, 2 figure

    A model for fermion masses and lepton mixing in SO(10) x A4

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    The discrete flavor symmetry A4 explains very well neutrino data at low energy, but it seems difficult to extend it to grand unified models since in general left-handed and right-handed fields belong to different A4 representations. Recently it has been proposed a model where all the fermions equally transform under A4. We study here a concrete SO(10) realization of such a model providing small neutrino masses through the seesaw mechanism. We fit at tree level the charged fermion masses run up to the unification scale. Some fermion masses properties come from the SO(10) symmetry while lepton mixing angles are consequence of the A4 properties. Moreover, our model predicts the absolute value of the neutrino masses, these ones are in the range mν0.0050.052eVm_\nu\simeq 0.005-0.052 eV.Comment: 15 pages. V2: Final version to appear in the journa

    Neutrino masses and tribimaximal mixing in the minimal renormalizable supersymmetric SU(5) grand unified model with A4 flavor symmetry

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    We analyze all possible extensions of the recently proposed minimal renormalizable SUSY SU(5) grand unified model with the inclusion of an additional A4 flavor symmetry. We find that there are five possible cases but only one of them is phenomenologically interesting. We develop in detail such case and we show how the fermion masses and mixing angles come out. As a prediction we obtain the neutrino masses of order of 0.1 eV with an inverted hierarchy.Comment: V1: 22 pages, V2: 16 pages, published version, results unchange

    On Universal Constants of AdS Black Holes from Hawking-Page Phase Transition

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    We investigate the thermodynamic properties of the Hawking-Page phase transition of AdS black holes. We present evidence for the existence of two universal critical constants associated with the Hawking-Page (HP) and minimum black hole thermodynamical transition points. These constants are defined by C_S =\frac{S_{HP}-S_{min}}{S_{min}} and C_T =\frac{T_{HP}-T_{min}}{T_{min}} where S_{min}(S_{HP}) and T_{min}(T_{HP}) are the minimal (HP phase transition) entropy and temperature, respectively, below which no black hole can exist. For a large class of four dimensional non-rotating black holes, we find C_S =2 and C_T = \frac{2-\sqrt{3}}{\sqrt{3}}. For the rotating case, however, such universal ratios are slightly affected without losing the expected values. Taking small values of the involved rotating parameter, we recover the same constants. Higher dimensional models, with other universal constants, are also discussed in some details.Comment: Latex, 16 pages, 2 figures. Accepted for publication in PLB(2020

    Slavnov-Taylor1.0: A Mathematica package for computation in BRST formalism

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    Slavnov-Taylor 1.0 is a Mathematica package which allows us to perform automatic symbolic computation in BRST formalism. This article serves as a self-contained guide to prospective users, and indicates the conventions and approximations used.Comment: 1+11 pages, 2 figures, LaTeX graphicx package used; accepted for publication in Computer Physics Communication
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