26054425
Dissipative dynamics of fission in the framework of asymptotic expansion of Fokker-Planck equation

Abstract: The dynamics of fission has been formulated by generalising the asymptotic expansion of the Fokker-Planck equation in terms of the strength of the fluctuations where the diffusion coefficients depend on the stochastic variables explicitly. The prescission neutron multiplicities and mean kinetic energies of the evaporated neutrons have been calculated and compared with the respective experimental data over a wide range of excitation energy and compound nuclear mass. The mean and the variance of the total kinetic energies of the fission fragments have been calculated and compared with the experimental values.
18344805
A Dynamical study of fission process and estimation of prescission neutron multiplicity
The dynamics of fission has been studied by solving Euler-Lagrange equation with dissipation generated through one and two body nuclear friction. The average kinetic energies of the fission fragments, prescission neutron multiplicities and the mean energies of the prescission neutrons have been calculated and compared with experimental values and they agree quite well. A single value of friction coefficient has been used to reproduce the experimental data for both symmetric and asymmetric splitting of the fissioning systems over a wide range of masses and excitation energies. It has been observed that a stronger friction is required in the saddle to scission region as compared to that in the ground state to saddle region.
123789901
Dark Matter Pions
We study the scenario where dark matter corresponds to a set of pseudoGoldstone bosons, that we call dark pions, generated by the spontaneous breaking of a symmetry in the dark sector. As a concrete example, we consider an SU(N)×SU(N) broken to the diagonal subgroup that remains an exact symmetry that ensures the stability of the dark pions, and allows a novel-interactions involving neutral gauge bosons and 3 dark pions. We study both experimental and theoretical constraints, and show that the model can accommodate all data in wide regions of parameter space.
119226937
Supersymmetry Signals at the LHC under the most favorable SUGRA scenario
Given that it will take quite some time for the Large Hadron Collider (LHC) to reach its desired luminosity, it is important to investigate the most favorable scenario in which supersymmetry (SUSY) may be discovered at the early runs at the LHC. Our aim in this work is to find such a scenario within the gravity mediated SUSY breaking (SUGRA) framework and select a class of final states that warrant a discovery at the very early runs of the LHC. It turns out that such a situation can be associated with a scenario where gluinos are sufficiently light and so are the third generation scalars while the first two family scalars are heavy. We find that this can be achieved from a high-scale set-up with scalar mass non-universality in the third family and gaugino mass non-universality with $M_3 < M_1, M_2$. We show that the final state channels which are most favorable in such a region of parameter space are $4b+{E_{T}}\!\!\!\!/$, $4b+\ell+{E_{T}}\!\!\!\!/$ and $2b+2\ell+{E_{T}}\!\!\!\!/$. We also justify our claim by comparing the results with a minimal supergravity (mSUGRA) scenario with similar gluino mass.
119189999
Signatures of supersymmetry with non-universal Higgs mass at the Large Hadron Collider
A bstractWe discuss large non-universality in the Higgs sector at high scale in supersymmetric theories, in the context of the Large Hadron Collider (LHC). In particular, we note that if $$ {{m}_{{{{H}_u}}}}^2 - {{m}_{{{{H}_d}}}}^2 $$ is large and negative $$ ( \simeq {1}{{0}^{{6}}}{\text{Ge}}{{\text{V}}^{{2}}}) $$ at high scale, the lighter slepton mass eigenstates at the electroweak scale are mostly left chiral, in contrast to a minimal supergravity (mSUGRA) scenario. We utilise this feature to explore different chiral structures of the lowest-lying sleptons, using two methods. First, we study final states with same-sign ditaus. We find that an asymmetry parameter reflecting the polarisation of the taus provides a notable distinction. In addition, we study a charge asymmetry in the jet-lepton invariant mass distribution, arising from decay chains of left-chiral squarks leading to leptons of the first two families.
119236612
Pionic dark matter
A bstractWe study a phenomenological model where the lightest dark matter (DM) particles are the pseudo-Goldstone excitations associated with a spontaneously broken symmetry, and transforming linearly with respect to an unbroken group $ {{\mathcal{H}}_{\mathrm{DM}}} $. For definiteness we take $ {{\mathcal{H}}_{\mathrm{DM}}} $ = SU(N) and assume the Goldstone particles are bosons; in parallel with QCD, we refer to these particles as dark-matter pions. This scenario is in contrast to the common assumption that DM fields transform linearly under the full symmetry of the model. We illustrate the formalism by treating in detail the case of $ {{\mathcal{H}}_{\mathrm{DM}}} $ = SU(2), in particular we calculate all the interactions relevant for the Boltzmann equations, which we solve numerically; we also derive approximate analytic solutions and show their consistency with the numerical results. We then compare the results with the constraints derived from the cold DM and direct detection experiments and derive the corresponding restrictions on the model parameters. We also briefly comment on constraints from indirect detection of DM.
119303787
Dark vector-gauge-boson model
A model based on $SU(3{)}_{C}\ifmmode\times\else\texttimes\fi{}SU(2{)}_{L}\ifmmode\times\else\texttimes\fi{}U(1{)}_{Y}\ifmmode\times\else\texttimes\fi{}SU(2{)}_{N}$ has recently been proposed, where the $SU(2{)}_{N}$ vector gauge bosons are neutral, so that a vector dark-matter candidate is possible and constrained by data to be less than about 1 TeV. We explore further implications of this model, including a detailed study of its Higgs sector. We improve on its dark-matter phenomenology, as well as its discovery reach at the Large Hadron Collider.