Right-handed States Research Articles

Existence of traveling waves in elastodynamics with variable viscosity and capillarity

Motivated by our earlier works, Thanh (2010) [3,4], we study the global existence of traveling waves associate with a Lax shock of a model of elastodynamics where the viscosity and capillarity are functions of the strain. The system is hyperbolic and may not be genuinely nonlinear. The left-hand and right-hand states of a Lax shock correspond to a stable node and a saddle point. By defining a Lyapunov-type function and using its level sets, we estimate the attraction domain of the stable node. Then we show that the saddle point lies on the boundary of the attraction domain of the stable node. Moreover, exactly one stable trajectory enters this attraction domain. This gives a stable-to-saddle connection for 1-shocks (a saddle-to-stable connection for 2-shocks), and therefore defines exactly one traveling wave connecting the two states of the Lax shock.

Baryogenesis via Sterile neutrino oscillation and neutrino parameters

We investigate baryogenesis in the ν MSM which is the Minimal Standard Model (MSM) extended by three right-handed neutrinos with Majorana masses being smaller than the weak scale. In this model three sterile neutrinos, which are almost right-handed states, play important roles in cosmology. The baryon asymmetry of the universe (BAU) is generated via mechanism through flavor oscillation between two sterile neutrinos N 2 and N 3 which are degenerate in masses. We consider the case when BAU is solely originated from the CP violating phases in the mixing matrix of active neutrinos, i.e., the Dirac phase δ and the Majorana phase η , and study how BAU depends on these CP violating phases.

Attractor and traveling waves of a fluid with nonlinear diffusion and dispersion

This work completes the description of the method of estimating attraction domain for traveling waves for several systems of conservation laws with viscosity and capillarity effects proposed in our earlier work Thanh (2010) [26]. Precisely, we establish the global existence of traveling waves for an isentropic fluid with nonlinear diffusion and dispersion coefficients. The shock wave can be classical or nonclassical. Interestingly, we in particular show the existence of a traveling wave for a given Lax shock but rather nonclassical when the straight line connecting the two left-hand and right-hand states crosses the graph of the pressure function two more times in the middle region. Furthermore, we also discuss all the possibilities of saddle–stable, saddle–saddle, or stable–stable connections.

On quantum effects in soft leptogenesis

It has been recently shown that quantum Boltzmann equations may be relevant forleptogenesis. Quantum effects, which lead to a time-dependent CP asymmetry,have been shown to be particularly important for resonant leptogenesis when theasymmetry is generated by the decay of two nearly degenerate states. In this work weinvestigate the impact of the use of quantum Boltzmann equations in the frameworkof ‘soft leptogenesis’ in which supersymmetry soft breaking terms give a smallmass splitting between the CP-even and CP-odd right-handed sneutrino states ofa single generation and provide the CP-violating phase to generate the leptonasymmetry.

Possible gravitoelectric dipole moment of neutrinos, atmospheric, and solar neutrino anomalies

We have carried out quantum-mechanical calculations of transition dynamics between the leftand right-handed helicity states νL ↔ νR of the atmospheric muon Dirac neutrino νμ , which has a gravitoelectric dipole moment (GEDM) interacting with the gravitational field of the Earth. It is shown that the asymmetry of the zenith-angle distribution of this neutrino can be explained by an interference of the two mutually perpendicular linearly polarized plane neutrino states with different phase velocities (difference in the respective refractive indices δn0 ≈ 0.7μ10) inside the Earth taking into consideration its gravitational field. The solar neutrino deficit can also be explained by the electron neutrino νe helicity flip transitions νL ↔ νR due to the interaction between GEDM of νe and the gravitational field of the Sun. The characteristic mass Mc ~ 10 GeV for the gravitational dipole of the neutral and charged leptons have been estimated. PACS number(s): 12.10.Kt, 13.15.+g, 14.60.St, 95.30.Sf

Lorentz violating extension of the standard model and theβ-decay endpoint

The standard model extension with additional Lorentz violating terms allows for redefining the equation of motion of a propagating left-handed fermionic particle. The obtained Dirac-type equation can be embedded in a generalized Lorentz-invariance-preserving algebra through the definition of Lorentz algebralike generators with a lightlike preferred axis. The resulting modification to the fermionic equation of motion introduces some novel ingredients to the phenomenological analysis of the cross section of the tritium $\ensuremath{\beta}$ decay. Assuming lepton number conservation, our formalism provides a natural explanation for the tritium $\ensuremath{\beta}$-decay end point via an effective neutrino mass term without the need of a sterile right-handed state.

Bistability of left- and right-handed π-twist states in a pixel-isolated dual-frequency nematic liquid crystal cell

The authors propose a bistable nematic liquid crystal cell which has two stable states of left- and right-handed π-twist. The switching between the two states is achieved by using a dual-frequency liquid crystal material and sequential waveform of low and high frequencies. Each state is stabilized by a multidimensional anchoring effect of a pixel-isolating polymer wall without any chiral additives. Therefore, the elastic free energies of left- and right-handed π-twist states are almost the same. As a result, the two states show superior retention time in spite of the topological equivalence.

Possibility of observing chiral-symmetry effects in ferromagnetic nanoparticles

The statistics of left-and right-handed vortical magnetization states in a system of submicron-sized ferromagnetic disks is studied experimentally. Lattices of elliptic cobalt particles with a planar size of 750 × 450 nm and a thickness of 25 nm were formed using high-resolution electronic lithography. To visualize the magnetization distributions in the disks, magnetic force microscopy was used. The experimental results indicate the conservation of magnetic chiral symmetry in cobalt ferromagnetic particles of the above size and shape.

Detection of heavy Majorana neutrinos and right-handed bosons

The SU c (3) ⊗ SU L (2) ⊗ SU R (2) ⊗ U(1) left-right (LR) symmetric model explains the origin of the parity violation in weak interactions and predicts the existence of additional gauge bosons W R and Z′. In addition, heavy right-handed Majorana neutrino states N arise naturally within the LR symmetric model. The states N could be partners of light neutrino states, related to their nonzero masses through the seesaw mechanism. This makes the searches for W R , Z′, and N interesting and important. In the framework of the minimal LR model, we study the possibility to observe signals from N and W R production in pp collisions after three years of running at low LHC luminosity. We show that their decay signals can be identified with a small background, especially in the case of same-sign leptons in the final state. For the integral LHC luminosity of L t = 30 fb−1, the 5σ discovery of W R boson and heavy Majorana neutrinos N e with masses \(M_{W_R } \) up to 4 TeV and \(M_{N_e } \) up to 2.4 TeV, respectively, is found to be possible.

NEUTRINO MASSES AND TeV SCALE RESONANT LEPTOGENESIS FROM SUPERSYMMETRY BREAKING

We review a class of supersymmetric models in which the light neutrino masses result from higher-dimensional supersymmetry-breaking terms in the MSSM super- and Kähler-potentials. The mechanism used in these models is closely related to the Giudice–Masiero mechanism for the MSSM μ parameter and leads to TeV-scale right-handed neutrino and sneutrino states. In these models, the dominant contribution to the light neutrino (Majorana) mass matrix is a one-loop term with a sub-dominant tree-level "seesaw" contribution. It is also shown that it is possible to construct a natural model of TeV-scale leptogenesis via the resonant behavior of the one-loop self-energy contribution to the right-handed neutrino (Ni) decay. This model addresses the primary problems of previous phenomenological studies of low-energy leptogenesis: a rational for TeV-scale right-handed neutrinos with small Yukawa couplings; the origin of the tiny, but non-zero mass splitting required between at least two Ni masses; and the necessary non-trivial breaking of flavor symmetries in the right-handed neutrino sector.

Noncommutative geometry and the standard model vacuum

The space of Dirac operators for the Connes-Chamseddine spectral action for the standard model of particle physics coupled to gravity is studied. The model is extended by including right-handed neutrino states, and the S0-reality axiom is not assumed. The possibility of allowing more general fluctuations than the inner fluctuations of the vacuum is proposed. The maximal case of all possible fluctuations is studied by considering the equations of motion for the vacuum. While there are interesting nontrivial vacua with Majorana-type mass terms for the leptons, the conclusion is that the equations are too restrictive to allow solutions with the standard model mass matrix.

Neutrino helicity and chirality transitions in Schwarzschild space-time

We study the helicity and chirality transitions of a high-energy neutrino propagating in a Schwarzschild space-time background. Using both traditional Schwarzschild and isotropic spherical co-ordinates, we derive an ultrarelativistic approximation of the Dirac Hamiltonian to first-order in the neutrino's rest mass, via a generalization of the Cini-Touschek transformation that incorporates non-inertial frame effects due to the noncommutative nature of the momentum states in curvilinear co-ordinates. Under general conditions, we show that neutrino's helicity is not a constant of the motion in the massless limit due to space-time curvature, while the chirality transition rate still retains an overall dependence on mass. We show that the chirality transition rate generally depends on the zeroth-order component of the neutrino's helicity transition rate under the Cini-Touschek transformation. It is also shown that the chiral current for high-energy neutrinos is altered by corrections due to curvature and frame-dependent effects, but should have no significant bearing on the chiral anomaly in curved space-time. We determine the upper bound for helicity and chirality transitions near the event horizon of a black hole. The special case of a weak-field approximation is also considered, which includes the gravitational analogue of Berry's phase first proposed by Cai and Papini. Finally, we propose a method for estimating the absolute neutrino mass and the number of right-handed chiral states from the expectation values of the helicity and chirality transition rates in the weak-field limit.

Neutrino self-polarization effect in matter

We develop the quasi-classical theory of the spin light of neutrino (SLν) in background matter accounting for the neutrino polarization. The neutrino transition νL→νR and νR→νL rates in matter are calculated. As a result of the SLν in matter, the active left-handed neutrinos νL are converted to the sterile right-handed states νR (the neutrino self-polarization effect in matter).

A simple model of neutrino masses from supersymmetry breaking

We analyze a class of supersymmetric models first introduced by Arkani-Hamed et al. and Borzumati et al. in which the light neutrino masses result from higher-dimensional supersymmetry-breaking terms in the MSSM super-potentials and Kahler potentials. The mechanism is closely related to the Giudice–Masiero mechanism for the MSSM μ parameter, and leads to TeV-scale right-handed neutrino and sneutrino states, that are in principle accessible to direct experimental study. The dominant contribution to the light neutrino (Majorana) mass matrix is a one-loop term induced by a lepton-number violating B-term for the sneutrino states that is naturally present. We focus upon the simplification and analysis of the flavour structure of this general class of models, finding that simple and novel origins for the light neutrino mass matrix are possible. We find that a subdominant tree-level ‘see-saw’ contribution may lead to interesting perturbations of the leading one-loop-induced flavour structure, possibly generating the small ratio Δmsolar2/Δmatm2 dynamically.

A simple model of neutrino masses from supersymmetry breaking

We analyze a class of supersymmetric models first introduced by Arkani-Hamed et al. and Borzumati et al. in which the light neutrino masses result from higher-dimensional supersymmetry-breaking terms in the MSSM super-potentials and Kahler potentials. The mechanism is closely related to the Giudice–Masiero mechanism for the MSSM μ parameter, and leads to TeV-scale right-handed neutrino and sneutrino states, that are in principle accessible to direct experimental study. The dominant contribution to the light neutrino (Majorana) mass matrix is a one-loop term induced by a lepton-number violating B -term for the sneutrino states that is naturally present. We focus upon the simplification and analysis of the flavour structure of this general class of models, finding that simple and novel origins for the light neutrino mass matrix are possible. We find that a subdominant tree-level ‘see-saw’ contribution may lead to interesting perturbations of the leading one-loop-induced flavour structure, possibly generating the small ratio Δ m solar 2 /Δ m atm 2 dynamically.

Soft leptogenesis

We study “soft leptogenesis”, a new mechanism of leptogenesis which does not require flavour mixing among the right-handed neutrinos. Supersymmetry soft-breaking terms give a small mass splitting between the CP-even and CP-odd right-handed sneutrino states of a single generation and provide a CP-violating phase sufficient to generate a lepton asymmetry. The mechanism is successful if the lepton-violating soft bilinear coupling is unconventionally (but not unnaturally) small. The values of the right-handed neutrino masses predicted by soft leptogenesis can be low enough to evade the cosmological gravitino problem.

Gluino pair production in high-energy photon collisions

We study the potential of high-energy photon colliders for the production of gluino pairs within the Minimal Supersymmetric Standard Model (MSSM). In this model, the process gamma gamma -> gluino gluino is mediated by quark/squark box diagrams with enhancements for up-type quarks/squarks from their larger charges and for third generation squarks from their large mass splittings, generated by the mixing of left- and right-handed states. Far above threshold and in scenarios with very heavy squarks, resolved photons can contribute significantly at tree level. Taking into account the laser photon backscattering spectrum, electron and laser beam polarization effects, and current mass exclusion limits, we find that gluino pair production in high-energy photon collisions should be visible over large regions of the MSSM parameter space, contrary to what has been found for e^+e^- annihilation. In addition, the cross section rises rather steeply, so that a gluino mass determination with a precision of a few GeV should be feasible for a wide range of post-LEP benchmark points.

Sterile neutrino in a minimal three-generation see-saw model

We investigate symmetries in Dirac and Majorana mass matrices of neutrinos in a three-generation scenario. We show that if we invokeLe +Lμ-LτxS2R symmetry, one combination of right-handed neutrino states remains massless which can be interpreted as a sterile neutrino. Next we consider a SU2Lx U(1)yx U(l)R gauge model and show how higher-dimensional operators can induce mixing between left- and right-handed states which explains solar, atmospheric and LSND experimental results.

Gluino pair production at lineare+e−colliders

We study the potential of high-energy linear $e^+e^-$ colliders for the production of gluino pairs within the Minimal Supersymmetric Standard Model (MSSM). In this model, the process $e^+e^-\to\tilde{g}\tilde{g}$ is mediated by quark/squark loops, dominantly of the third generation, where the mixing of left- and right-handed states can become large. Taking into account realistic beam polarization effects, photon and $Z^0$-boson exchange, and current mass exclusion limits, we scan the MSSM parameter space for various $e^+e^-$ center-of-mass energies to determine the regions, where gluino production should be visible.

Search for scalar top and scalar bottom quarks at LEP

Searches for a scalar top quark and a scalar bottom quark have been performed using a data sample of 438 pb−1 at centre-of-mass energies of s=192–209 GeV collected with the OPAL detector at LEP. No evidence for a signal was found. The 95% confidence level lower limit on the scalar top quark mass is 97.6 GeV if the mixing angle between the supersymmetric partners of the left- and right-handed states of the top quark is zero. When the scalar top quark decouples from the Z0 boson, the lower limit is 95.7 GeV. These limits were obtained assuming that the scalar top quark decays into a charm quark and the lightest neutralino, and that the mass difference between the scalar top quark and the lightest neutralino is larger than 10 GeV. The complementary decay mode of the scalar top quark decaying into a bottom quark, a charged lepton and a scalar neutrino has also been studied. The lower limit on the scalar top quark mass is 96.0 GeV for this decay mode, if the mass difference between the scalar top quark and the scalar neutrino is greater than 10 GeV and if the mixing angle of the scalar top quark is zero. From a search for the scalar bottom quark, a mass limit of 96.9 GeV was obtained if the mass difference between the scalar bottom quark and the lightest neutralino is larger than 10 GeV.