118317908
CP asymmetry in the decays B ---> (X(s), X(d)) mu+ mu- with four generations
We estimate the CP asymmetry A CP (q 2 ) in the decays B → X s μ + μ - and B → X d μ + μ in the standard model (SM) with an additional fourth generation. We use a parametrization that allows us to explore the complete parameter space of the 4 X 4 quark mixing matrix, and constrain these parameters from the current data on B decays. We find that the enhancement in A CP (q 2 ) depends strongly on the mass of the t 1 , the up-type quark in the fourth generation. For m t 1 around 400 GeV, the CP asymmetry in the high-q 2 region (q 2 > 14.4 GeV 2 ) can be enhanced by more than an order of magnitude for B → X s μ + μ - and up to a factor of 6 for B → X d μ + μ - . There is no enhancement in the low-q 2 region (1 < q 2 < 6 GeV 2 ). With increasing m t 1 , A CP (q 2 ) in the high-q 2 (low-q 2 ) region first decreases (increases) and then saturates at a value a few times the SM prediction. In the high-q 2 region of B → X s μ + μ - , this saturation value may be up to 25 times the SM expectation.
119875035
New physics signals at long baseline experiments
We develop a formalism that gives analytically tractable expressions for flavor conversion probabilities at long baseline experiments, in the presence of any number of sterile neutrino species or with CPT violation. Using a perturbative expansion in the small parameters we show that, even in a completely general analysis, only certain specific combinations of the mixing parameters are relevant and hence can be probed in the experiments. We identify the long baseline experiments which will be able to probe those observable combinations in a clean manner and estimate their reach in measuring or constraining those observables.
35648525
2540 km: bimagic baseline for neutrino oscillation parameters.
We show that a source-to-detector distance of 2540 km, motivated recently [S. K. Raut, R. S. Singh, and S. U. Sankar, arXiv:0908.3741] for a narrow band superbeam, offers multiple advantages for a low energy neutrino factory with a detector that can identify muon charge. At this baseline, for any neutrino hierarchy, the wrong-sign muon signal is almost independent of CP violation and θ(13) in certain energy ranges. This allows the identification of the hierarchy in a clean way. In addition, part of the muon spectrum is also sensitive to the CP violating phase and θ(13), so that the same setup can be used to probe these parameters as well.
119180962
CPT violation in long baseline neutrino experiments: A three flavor analysis
We explore possible signals of CPT violation in neutrinos in the complete three-flavor framework. Employing a systematic expansion in small parameters, we analytically estimate the CPT violating contributions to the survival probabilities of ${\ensuremath{\nu}}_{\ensuremath{\mu}}$, ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$, ${\ensuremath{\nu}}_{e}$ and, ${\overline{\ensuremath{\nu}}}_{e}$. The results indicate that, in spite of the large number of CPT violating parameters, only a small number of combinations are relevant for oscillation experiments. We identify the combinations that can be constrained at the long baseline experiments, and show that their contribution to the neutrino Hamiltonian can be bounded to $\ensuremath{\lesssim}{10}^{\ensuremath{-}23}\text{ }\text{ }\mathrm{GeV}$, by considering the NOvA experiment for the muon sector, and neutrino factories for the electron sector. This formalism also allows us to translate the bounds on the parameters describing non-standard interactions of neutrinos into the bounds on CPT violating quantities.
118450272
Renormalization group evolution of neutrino masses and mixing in the Type-III seesaw mechanism
Abstract We consider the standard model extended by heavy right-handed fermions transforming as triplets under SU ( 2 ) L , which generate neutrino masses through the Type-III seesaw mechanism. At energies below their respective mass scales, the heavy fields get sequentially decoupled to give an effective dimension-5 operator. Above their mass thresholds, these fields also participate in the renormalization of the wavefunctions, masses and coupling constants. We compute the renormalization group evolution of the effective neutrino mass matrix in this model, with particular emphasis on the threshold effects. The evolution equations are obtained in a basis of neutrino parameters where all the quantities are well-defined everywhere, including at θ 13 = 0 . We also point out the important role of the threshold effects and Majorana phases in the evolution of mixing angles through illustrative examples.
118994296
Signatures of heavy sterile neutrinos at long baseline experiments
Sterile neutrinos with masses {approx}0.1 eV or higher, allowed with the current oscillation data, can potentially play an important role in astrophysics and cosmology. We explore possible signatures of such sterile neutrinos at long baseline experiments. We determine the neutrino conversion probabilities analytically in a 4-neutrino framework, including matter effects, treating the sterile mixing angles {theta}{sub 14}, {theta}{sub 24}, {theta}{sub 34}, the deviation of {theta}{sub 23} from maximality, as well as {theta}{sub 13} and the ratio {delta}m{sub {center_dot}}{sup 2}/{delta}m{sub atm}{sup 2} as small parameters for a perturbative expansion. This gives rise to analytically tractable expressions for flavor conversion probabilities from which effects of these parameters can be clearly understood. We numerically calculate the signals at a neutrino factory with near and far detectors that can identify the lepton charge, and point out observables that can discern the sterile mixing signals. We find that clean identification of sterile mixing would be possible for {theta}{sub 24}{theta}{sub 34} > or approx. 0.005 (3{sigma}) and {theta}{sub 14} > or approx. 0.06 rad (3{sigma}) with the current bound of {theta}{sub 13}<0.2 rad; a better {theta}{sub 13} bound would allow probing smaller values of sterile mixing. We also generalize the formalism for any number of sterilemore » neutrinos, and demonstrate that only certain combinations of sterile mixing parameters are relevant irrespective of the number of sterile neutrinos. This also leads to a stringent test of the scenario with multiple sterile neutrinos that currently is able to describe all the data from the short baseline experiments, including LSND and MiniBooNE.« less
7320135
Energy density in general relativity: a possible role for the cosmological constant
Abstract We consider a static spherically symmetric charged anisotropic fluid source of radius ∼10 −16 cm by introducing a variable Λ dependent on the radial coordinate r under general relativity. From the solution sets a possible role of the cosmological constant is investigated which indicates the dependency of energy density on it.
15882822
Entropy & viscosity bound of strange stars
At finite temperature (T) there is a link with general relativity and hydrodynamics that leads to a lower bound for the ratio of shear viscosity and entropy density (\eta/s). We find that the bound is saturated in the simple model for quark matter that we use for strange stars at T = 80 MeV, at the surface of a strange star. At this T we have the possibility of cosmic separation of phases. We find that, although strongly correlated, the quark matter at the surface of strange stars constitute the most perfect interacting fluid permitted by nature. At the centre of the star, however, the density is higher and conditions are more like the results found for perturbative QCD.
197508300
CMB power spectrum estimation with non-circular beam and incomplete sky coverage
14472580
Strange stars and superbursts at near-Eddington mass accretion rates
Careful assessment of four good superburst candidates for GX 17+2 reveals that superburst is possible at near Eddington mass accretion rates. For the other seven stars, where superburst is found, there is the standard model of burning accumulated carbon from normal type I bursts of the accreting stars. However, there is the need for carbon, nitrogen and oxygen mass fraction (Z_{CNO}) which must be larger than Z_{CNO,\odot}, where the latter refers to the standard value found in the sun. Also it is very difficult to incorporate GX 17+2 into the standard picture of superbursts. In case of superbursts from strange stars, arising from broken quark pairs going over to diquarks at the surface of the star, these problems do not arise. Furthermore there is a natural explanation for the large value of ~ 1000 for \alpha which is defined in the literature as the ratio of energy released between normal bursts to the energy released during the normal burst. In the scenario for superbursts in strange stars it may be argued that the relatively smaller value of \alpha of ~ 440 indicates frequent recurrence of superbursts which is reflected in 4U 1636-53.
583746
Compact strange stars with a medium dependence in gluons at finite temperature
Aims. The possible existence of strange stars in the universe will help in the understanding of various properties of quantum chromodynamics, like asymptotic freedom and chiral symmetry restoration, which is otherwise very difficult to prove in laboratory experiments. Methods. Strange star properties were calculated using large color approximation with built-in chiral symmetry restoration. A relativistic Hartree Fock calculation was performed using the Richardson potential as an interquark interaction. This potential has the asymptotic freedom and a confinement-deconfinement mechanism built into it and the present calculation employs an application of this potential with modified two scale parameters Λ and $\Lambda^{\prime}$, to find a new set of equations of state for strange quark matter. The linear confinement string tension from lattice calculations is 350 MeV and the Coulomb -like part has the parameter 100 MeV from deep inelastic scattering experiments. We also consider the effect of temperature, on gluon mass in a simple way, in addition to the usual density dependence, Results. We obtained a set of new equation of states for strange quark matter and also found that the transition temperature from hadronic matter to strange matter is at 80 MeV, close to the 100 MeV estimated in literature. Conclusions. Formation of strange stars may be the only signal for formation of quark-gluon plasma with asymptotic freedom and chiral symmetry restoration and this may be observable through many processes – such as for example through delayed γ ray afterglow.