On the non-relativistic limit of charge conjugation in QED

Even if at the level of the non-relativistic limit of full QED, C is not a symmetry, the limit of this operation does exist for the particular case when the electromagnetic field is considered a classical external object coupled to the Dirac field. This result extends the one obtained when fermions are described by the Schroedinger-Pauli equation. We give the expressions for both the C matrix and the $\hat{C}$ operator for galilean electrons and positrons interacting with the external electromagnetic field. The result is relevant in relation to recent experiments with antihydrogen.Comment: 7 page

Partial Differential Equations in Applied Mathematics https://www.sciencedirect.com/journal/partial-differential-equations-in-applied- mathematics Analysis of unsteady thermo-solutal MoS2-EO Brinkman electro-conductive reactive nanofluid transport in a hybrid rotating Hall MHD generator

MHD rotating generators offer a plausible renewable energy mechanism. New designs are emerging in which nanotechnology is contributing. Such systems are increasingly deploying more complex functional fluid materials such as base fluids containing magnetic nanoparticles which constitute electromagnetic nanofluids and can be tuned to enhance efficiencies. Motivated by these developments, a mathematical model is presented for the combined effects of Hall current, heat source, chemical reaction and radiative flux on the unsteady rotating thermo-solutal magnetohydrodynamic transport of a Molybdenum disulphide (MoS2)-EO oil electroconductive Brinkman nanofluid to study the boundary layer characteristics in the vicinity of the side wall of an MHD generator system. The governing dimensional conservation equations are scaled using appropriate transformations into a system of dimensionless coupled partial differential equations. Under appropriate initial and boundary conditions, solutions are derived using the Laplace Transform Method (LTM) and complex variables. The physical impacts of the magnetic, nanoscale, thermal and species control parameters on primary and secondary velocity, temperature and concentration are visualized graphically. The judicious doping of the base fluid with MoS2 nanoparticles is shown to achieve superior thermal performance for MHD rotating energy generators

Physical mechanisms generating spontaneous symmetry breaking and a hierarchy of scales

We discuss the phase transition in 3+1 dimensional lambda Phi^4 theory from a very physical perspective. The particles of the symmetric phase (`phions') interact via a hard-core repulsion and an induced, long-range -1/r^3 attraction. If the phion mass is sufficiently small, the lowest-energy state is not the `empty' state with no phions, but is a state with a non-zero density of phions Bose-Einstein condensed in the zero-momentum mode. The condensate corresponds to the spontaneous-symmetry-breaking vacuum with neq 0 and its excitations ("phonons" in atomic-physics language) correspond to Higgs particles. The phase transition happens when the phion's physical mass m is still positive; it does not wait until m^2 passes through zero and becomes negative. However, at and near the phase transition, m is much, much less than the Higgs mass M_h. This interesting physics coexists with `triviality;' all scattering amplitudes vanish in the continuum limit, but the vacuum condensate becomes infinitely dense. The ratio m/M_h, which goes to zero in the continuum limit, can be viewed as a measure of non-locality in the regularized theory. An intricate hierarchy of length scales naturally arises. We speculate about the possible implications of these ideas for gravity and inflation.Comment: 27 pages plus 2 files of figure

Thirty Years of Precision Electroweak Physics

We discuss the development of the theory of electroweak radiative corrections and its role in testing the Standard Model, predicting the top quark mass, constraining the Higgs boson mass, and searching for deviations that may signal the presence of new physics.Comment: 19 pages, acknowledgments added, J.J.Sakurai Prize Talk, APS Meeting, Albuquerque, N.M., April 2002. To appear in a future issue of Journal of Physics

Metachronal propulsion of a magnetized particle-fluid suspension in a ciliated channel with heat and mass transfer

Biologically inspired pumping systems are of great interest in modern engineering since they achieve enhanced efficiency and circumvent the need for moving parts and maintenance. Industrial applications also often feature two-phase flows. In this article, motivated by these applications, the pumping of an electrically conducting particle-fluid suspension due to metachronal wave propulsion of beating cilia in a two-dimensional channel with heat and mass transfer under a transverse magnetic field is investigated theoretically. The governing equations for mass and momentum conservation for fluid- and particle-phases are formulated by ignoring the inertial forces and invoking the long wavelength approximation. The Jeffrey viscoelastic model is employed to simulate non-Newtonian characteristics. The normalized resulting differential equations are solved analytically. Symbolic software is employed to evaluate the results and simulate the influence of different parameters on flow characteristics. Results are visualized graphically with carefully selected and viable data

A Universal Action Formula

A universal formula for an action associated with a noncommutative geometry, defined by a spectal triple (\Ac ,\Hc ,D), is proposed. It is based on the spectrum of the Dirac operator and is a geometric invariant. The new symmetry principle is the automorphism of the algebra \Ac which combines both diffeomorphisms and internal symmetries. Applying this to the geometry defined by the spectrum of the standard model gives an action that unifies gravity with the standard model at a very high energy scale.Comment: This is a short non technical letter based on the longer version, hep-th/9606001. Tex file, 10 page

Dirac neutrino magnetic moment and a possible time evolution of the neutrino signal from a supernova

We analyze the influence of neutrino helicity conversion, $\nu_L \to \nu_R$, on the neutrino flux from a supernova caused by the interaction of the Dirac neutrino magnetic moment with a magnetic field. We show that if the neutrino has a magnetic moment in the interval $10^{-13} \, \mu_{\rm B} < \mu_\nu < 10^{-12} \, \mu_{\rm B}$ and provided that a magnetic field of $\sim 10^{13} - 10^{14}$ G exists in the supernova envelope, a peculiar kind of time evolution of the neutrino signal from the supernova caused by the resonance transition $\nu_L \to \nu_R$ in the magnetic field of the envelope can appear. If a magnetar with a poloidal magnetic field is formed in a supernova explosion, then the neutrino signal could have a pulsating behavior, i.e., a kind of a neutrino pulsar could be observed, when it rotates around an axis that does not coincide with its magnetic moment and when the orientation of its rotation axis is favourable for our observation.Comment: 9 pages, LaTeX, 2 EPS figures, based on the talk presented by A.V. Kuznetsov at the XVI International Seminar Quarks'2010, Kolomna, Moscow Region, June 6-12, 2010, to appear in the Proceeding

Large magnetic dipole moments for neutrinos with arbitrary masses

We show that there is a general sort of models in which it is possible to have large magnetic dipole moments for neutrinos while keeping their masses arbitrarily small. Some examples of these models are considered.Comment: REVTEX, 8 pages, 2 .eps figure

Experimental Characteristics of Dynamical Pseudo Goldstone Bosons

The hypothetical existence of new color interactions, which participate in the spontaneous breaking of the weak-interaction group, will in general lead to relatively light composite pseudo Goldstone bosons. Their production and decay characteristics are analyzed to be close to, yet actually distinguishable from, those of the elementary Higgs bosons of the Weinberg-Salam model