Search results for "fourth"

On the nature of the fourth generation neutrino and its implications

2012

We consider the neutrino sector of a Standard Model with four generations. While the three light neutrinos can obtain their masses from a variety of mechanisms with or without new neutral fermions, fourth-generation neutrinos need at least one new relatively light right-handed neutrino. If lepton number is not conserved this neutrino must have a Majorana mass term whose size depends on the underlying mechanism for lepton number violation. Majorana masses for the fourth generation neutrinos induce relative large two-loop contributions to the light neutrino masses which could be even larger than the cosmological bounds. This sets strong limits on the mass parameters and mixings of the fourth …

Anisotropy of flow and the order of phase transition in relativistic heavy ion collisions

2005

Using a hydrodynamical model we study how the order of phase transition in the equation of state of strongly interacting matter affects single particle spectra, elliptic flow and higher order anisotropies in Au+Au collisions at RHIC (sqrt{s_NN}=200 GeV energy). We find that the single particle spectra are independent of the order of phase transition and that the fourth harmonic v_4(p_T) shows only a weak dependence in the p_T region where hydrodynamics is expected to work. The differential elliptic flow, v_2(p_T), of baryons shows the strongest dependence on equation of state. Surprisingly the closest fit to data was obtained when the equation of state had a strong first order phase transit…

Study of thepd→pdηreaction

2007

A study of the pd{yields}pd{eta} reaction in the energy range where the recent data from Uppsala are available is done in the two-step model of {eta} production including the final state interaction. The {eta}-d final state interaction is incorporated through the solution of the Lippmann Schwinger equation using an elastic scattering matrix element, T{sub {eta}}{sub d{yields}}{sub {eta}}{sub d}, which is required to be half off-shell. It is written in a factorized form, with an off-shell form factor multiplying an on-shell part given by an effective range expansion up to the fourth power in momentum. The parameters of this expansion have been taken from an existing recent relativistic Fadde…

Fourth-order perturbation theory for the half-filled Hubbard model in infinite dimensions

2003

We calculate the zero-temperature self-energy to fourth-order perturbation theory in the Hubbard interaction $U$ for the half-filled Hubbard model in infinite dimensions. For the Bethe lattice with bare bandwidth $W$, we compare our perturbative results for the self-energy, the single-particle density of states, and the momentum distribution to those from approximate analytical and numerical studies of the model. Results for the density of states from perturbation theory at $U/W=0.4$ agree very well with those from the Dynamical Mean-Field Theory treated with the Fixed-Energy Exact Diagonalization and with the Dynamical Density-Matrix Renormalization Group. In contrast, our results reveal t…

Propagation of fourth sound in turbulent superfluids via extended thermodynamics

2011

The work deals with further developments of a study previously initiated, in which a macroscopic one-fluid model of inhomogeneous turbulent superfluids, based on extended thermodynamics, had been formulated. In this work the study is carried on. First the influence of the remnant vortices on the propagation of the first and second sound is studied. Then a boundary condition able to explain the reversible flow of superfluid flowing through a thin capillary is postulated and two vector fields, which have the dimensions of velocity and can be interpreted as the velocities of normal and superfluid components, are introduced. By using these new fields, a comparison between this model and the Hal…

Impact of the quenching of gA on the sensitivity of 0νββ experiments

2017

Detection of the neutrinoless $\ensuremath{\beta}\ensuremath{\beta}$ ($0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$) decay is of high priority in the particle- and neutrino-physics communities. The detectability of this decay mode is strongly influenced by the value of the weak axial-vector coupling constant ${g}_{A}$. The recent nuclear-model analyses of $\ensuremath{\beta}$ and $\ensuremath{\beta}\ensuremath{\beta}$ decays suggest that the value of ${g}_{A}$ could be dramatically quenched, reaching ratios of ${g}_{A}^{\mathrm{free}}/{g}_{A}\ensuremath{\approx}4$, where ${g}_{A}^{\mathrm{free}}=1.27$ is the free, neutron-decay, value of ${g}_{A}$. The effects of this quenching ap…

Active reduction of fluctuations in fourth-order modulation instability

2012

International audience; We experimentally study the fluctuation properties of a scalar fourth-order modulation instability process obtained by pumping a photonic crystal fiber in the normal dispersion region. We observe large wavelength-dependant pulse-to-pulse fluctuations which cannot be significantly reduced by stimulating the process with a single seed. Their reduction requires two seeds slightly detuned from the maximum gain frequency in order to also stimulate the second-order modulation instability process cascaded from the fourth-order one. This concept is validated by experiments and numerical simulations.

Usability of Programming Languages

2016

Programming languages form the interface between programmers (the users) and the computation that they desire the computer to execute. Although studies exist for some aspects of programming language design (such as conditionals), other aspects have received little or no human factors evaluations. Designers thus have little they can rely on if they want to make new languages highly usable, and users cannot easily chose a language based on usability criteria. This SIG will bring together researchers and practitioners interested in increasing the depth and breadth of studies on the usability of programming languages, and ultimately in improving the usability of future languages. nonPeerReviewed

Multiplicity results for fourth order two-point boundary value problems with asymmetric nonlinearities

1998

Some fourth order CY-type operators with non symplectically rigid monodromy

2012

We study tuples of matrices with rigidity index two in $\Sp_4(\mathbb{C})$, which are potentially induced by differential operators of Calabi-Yau type. The constructions of those monodromy tuples via algebraic operations and middle convolutions and the related constructions on the level differential operators lead to previously known and new examples.