9,795 research outputs found

### Dependence of the leptonic decays of H^- on the neutrino mixing angles theta_{13} and theta_{23} in models with neutrinophilic charged scalars

In the Higgs Triplet Model and the neutrinophilic Two-Higgs-Doublet Model the
observed neutrinos obtain mass from a vacuum expectation value which is much
smaller than the vacuum expectation value of the Higgs boson in the Standard
Model. Both models contain a singly charged Higgs boson (H^-) whose Yukawa
coupling is directly related to the neutrino mass (i.e. a "neutrinophilic
charged Higgs"). The partial decay widths of H^- into a charged lepton and a
neutrino (H^- to l^- nu) depend identically on the neutrino masses and mixings
in the two models. We quantify the impact of the recent measurement of
sin^2(2theta_{13}), which plays a crucial role in determining the magnitude of
the branching ratio of H^- to e^- nu for the case of a normal neutrino mass
ordering if the lightest neutrino mass m_0 < 10^{-3} eV. We also discuss the
sizeable dependence of H^- to mu^- nu and H^- to tau^- nu on sin^2(theta_{23}),
which would enable information to be obtained on sin^2(theta_{23}) and the sign
of \Delta m^2_{31} if these decays are measured. Such information would help
neutrino oscillation experiments to determine the CP-violating phase \delta.Comment: 17 pages, 6 figure

### Probing Majorana Phases and Neutrino Mass Spectrum in the Higgs Triplet Model at the LHC

Doubly charged Higgs bosons (H^++) are a distinctive signature of the Higgs
Triplet Model of neutrino mass generation. If H^++ is relatively light
(m_{H^++} < 400GeV) it will be produced copiously at the LHC, which could
enable precise measurements of the branching ratios of the decay channels H^++
to l_i l_j. Such branching ratios are determined solely by the neutrino mass
matrix which allows the model to be tested at the LHC. We quantify the
dependence of the leptonic branching ratios on the absolute neutrino mass and
Majorana phases, and present the permitted values for the channels ee, emu and
mumu. It is shown that precise measurements of these three branching ratios are
sufficient to extract information on the neutrino mass spectrum and probe the
presence of CP violation from Majorana phases.Comment: 1+19 pages, 22 figures, typos corrected, references added, version to
appear in Phys. Rev.

### Lattice Boltzmann Simulations of Droplet formation in confined Channels with Thermocapillary flows

Based on mesoscale lattice Boltzmann simulations with the "Shan-Chen" model,
we explore the influence of thermocapillarity on the break-up properties of
fluid threads in a microfluidic T-junction, where a dispersed phase is injected
perpendicularly into a main channel containing a continuous phase, and the
latter induces periodic break-up of droplets due to the cross-flowing.
Temperature effects are investigated by switching on/off both positive/negative
temperature gradients along the main channel direction, thus promoting a
different thread dynamics with anticipated/delayed break-up. Numerical
simulations are performed at changing the flow-rates of both the continuous and
dispersed phases, as well as the relative importance of viscous forces, surface
tension forces and thermocapillary stresses. The range of parameters is broad
enough to characterize the effects of thermocapillarity on different mechanisms
of break-up in the confined T-junction, including the so-called "squeezing" and
"dripping" regimes, previously identified in the literature. Some simple
scaling arguments are proposed to rationalize the observed behaviour, and to
provide quantitative guidelines on how to predict the droplet size after
break-up.Comment: 18 pages, 9 figure

### Ground States for Diffusion Dominated Free Energies with Logarithmic Interaction

Replacing linear diffusion by a degenerate diffusion of porous medium type is
known to regularize the classical two-dimensional parabolic-elliptic
Keller-Segel model. The implications of nonlinear diffusion are that solutions
exist globally and are uniformly bounded in time. We analyse the stationary
case showing the existence of a unique, up to translation, global minimizer of
the associated free energy. Furthermore, we prove that this global minimizer is
a radially decreasing compactly supported continuous density function which is
smooth inside its support, and it is characterized as the unique compactly
supported stationary state of the evolution model. This unique profile is the
clear candidate to describe the long time asymptotics of the diffusion
dominated classical Keller-Segel model for general initial data.Comment: 30 pages, 2 figure

### Patchy He II reionization and the physical state of the IGM

We present a Monte-Carlo model of He II reionization by QSOs and its effect
on the thermal state of the clumpy intergalactic medium (IGM). The model
assumes that patchy reionization develops as a result of the discrete
distribution of QSOs. It includes various recipes for the propagation of the
ionizing photons, and treats photo-heating self-consistently. The model
provides the fraction of He III, the mean temperature in the IGM, and the He II
mean optical depth -- all as a function of redshift. It also predicts the
evolution of the local temperature versus density relation during reionization.
Our findings are as follows: The fraction of He III increases gradually until
it becomes close to unity at $z\sim 2.8-3.0$. The He II mean optical depth
decreases from $\tau\sim 10$ at $z\geq 3.5$ to $\tau\leq 0.5$ at $z\leq 2.5$.
The mean temperature rises gradually between $z\sim 4$ and $z\sim 3$ and
declines slowly at lower redshifts. The model predicts a flattening of the
temperature-density relation with significant increase in the scatter during
reionization at $z\sim 3$. Towards the end of reionization the scatter is
reduced and a tight relation is re-established. This scatter should be
incorporated in the analysis of the Ly$\alpha$ forest at $z\leq 3$. Comparison
with observational results of the optical depth and the mean temperature at
moderate redshifts constrains several key physical parameters.Comment: 18 pages, 9 figures; Changed content. Accepted for publication in
MNRA

### Production of doubly charged scalars from the decay of singly charged scalars in the Higgs Triplet Model

The existence of doubly charged Higgs bosons (H^{\pm\pm}) is a distinctive
feature of the Higgs Triplet Model (HTM), in which neutrinos obtain tree-level
masses from the vacuum expectation value of a neutral scalar in a triplet
representation of SU(2)_L. We point out that a large branching ratio for the
decay of a singly charged Higgs boson to a doubly charged Higgs boson via
H^\pm\to H^{\pm\pm}W^* is possible in a sizeable parameter space of the HTM.
From the production mechanism q'qbar\to W^* \to H^{\pm\pm}H^\mp the above decay
mode would give rise to pair production of H^{\pm\pm}, with a cross section
which can be comparable to that of the standard pair-production mechanism
qqbar\to \gamma^*,Z^* \to H^{++}H^{--}. We suggest that the presence of a
sizeable branching ratio for H^\pm\to H^{\pm\pm}W^* could significantly enhance
the detection prospects of H^{\pm\pm} in the four-lepton channel. Moreover, the
decays H^0\to H^\pm W^* and A^0\to H^\pm W^* from production of the neutral
triplet scalars H^0 and A^0 would also provide an additional source of H^\pm,
which can subsequently decay to H^{\pm\pm}.Comment: 13 pages, 3 figures, two figures added in v2, to appear in Physical
Review

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