25 research outputs found

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

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 $E/m=\Delta\theta/2$. Where
$\Delta\theta$ 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 $\rho_B/s\approx 10^{-10}$ for a large range of parameters and
CP violation. As a function of $\Delta\theta$, the ratio $\rho_b/s$ reach a
maximum for $\Delta\theta\approx 2-4\pi$ and $m\approx m_{top}$. 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

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

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 ${}^8$B neutrinos. From KamLAND negative results after
145 days of data taking, we obtain model independent limits on the total flux
of solar electron antineutrinos $\Phi({}^8 B)< 1.1-3.5\times 10^4 cm^{-2}\
s^{-1}$, more than one order of magnitude smaller than existing limits, and on
their appearance probability$P<0.15%$(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$\mu B< 2.3\times 10^{-21}$MeV 95% CL (for
LMA$(\Delta m^2, \tan^2\theta)$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,$\mu\lsim 3.9\times 10^{-12} \mu_B$(95%
CL) for a relatively small field$B= 50$kG. For higher values of the magnetic
field we obtain:$\mu\lsim 9.0\times 10^{-13} \mu_B$for field$B= 200$kG and$\mu\lsim 2.0\times 10^{-13} \mu_B$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

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 $m_\nu\simeq
0.005-0.052 eV$.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

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

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

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