Screening of light mesons and charmonia at high temperature

We present lattice QCD results for the screening masses of light mesons and charmonia. The lattice computations were performed with 2 + 1 flavors of improved staggered quarks using quark masses which correspond to realistic pion and kaon masses at zero temperature. For the light quark sector we have found that the screening masses in the pseudo-scalar and the isovector scalar channels do not become degenerate at the chiral crossover temperature indicating an effective non-restoration of the axial symmetry. Also the splitting between the vector and the pseudo-scalar screening masses persists even in the limit of zero lattice spacing and at a moderately high temperature around 420 MeV. In the charmonium sector our investigation shows that the screening masses of the pseudo-scalar and the vector charmonia are almost (within a few percent) equal to their zero temperature masses for temperatures less than 300 MeV. We also present results for the charmonium screening masses using periodic boundary conditions along the temporal direction and discuss their implications.     

Derivative expansion for the effective action of chiral gauge fermions. The normal parity component

Explicit exact formulas are presented, up to fourth order in a strict chiral covariant derivative expansion, for the normal parity component of the Euclidean effective action of even-dimensional Dirac fermions. The bosonic background fields considered are scalar, pseudo-scalar, vector and axial vector. No assumptions are made on the internal symmetry group and, in particular, the scalar and pseudo-scalar fields need not be on the chiral circle. Received: 31 January 2001 / Published online: 12 April 2001     

Derivative expansion for the effective action of chiral gauge fermions. The abnormal parity component

Explicit exact formulas are presented, for the leading order term in a strict chiral covariant derivative expansion, for the abnormal parity component of the effective action of two- and four-dimensional Dirac fermions in the presence of scalar, pseudo-scalar, vector and axial vector background fields. The formulas hold for completely general internal symmetry groups and general configurations. In particular, the scalar and pseudo-scalar fields need not be on the chiral circle. Received: 31 January 2001 / Published online: 12 April 2001     

Mass without scalars

We attempt to show that fundamental scalar fields can be eliminated from the theory of weak and electromagnetic interactions. We do this by constructing an explicit example in which the scalar field sectors are replaced by strongly interacting gauge systems. Unlike previous examples, our present work gives a natural explanation for fermion masses. The cost is a significant expansion of the size of the gauge group.     

Inertial Mass and Vacuum Fluctuations in Quantum Field Theory

Motivated by recent works on the origin of inertial mass, we revisit the relationship between the mass of charged particles and zero-point electromagnetic fields. To this end we first introduce a simple model comprising a scalar field coupled to stochastic or thermal electromagnetic fields. Then we check if it is possible to start from a zero bare mass in the renormalization process and express the finite physical mass in terms of a cut-off. In scalar QED this is indeed possible, except for the problem that all conceivable cut-offs correspond to very large masses. For spin-1/2 particles (QED with fermions) the relation between bare mass and renormalized mass is compatible with the observed electron mass and with a finite cut-off, but only if the bare mass is not zero; for any value of the cut-off the radiative correction is very small.     

Generalized spin and pseudo-spin symmetry: Relativistic extension of supersymmetric quantum mechanics

We consider the Dirac equation in 1+1$1+1$ space–time dimension with vector, scalar and pseudo-scalar coupling. In the traditional spin (or pseudo-spin) symmetry, the difference between (or sum of) the scalar and vector potentials is a constant. Here, however, we introduce an alternative symmetry where the scalar or pseudo-scalar potential is proportional to the vector potential. This leads to a model with significant extensions to supersymmetric quantum mechanics. We present a formal solution of the problem but give explicit analytic results for specific examples.     

Topological Aharonov-Bohm Effect of Neutral Scalar Particle on Noncommutative Space

We study the interactions between a neutral scalar particle and electromagnetic fields on noncommutative space. Because of the noncommutativity of space, neutral particle can couple to electromagnetic fields at the tree level, and the interaction strength is represented by a new coupling constant. We find that on noncommtuative space the topological Aharonov-Bohm effect is nontrivial even for neutral scalar particle.     

Dirac magnetic monopoles as goldstone and higgs bosons in the origin of mass

A dyonium model of quarks is incorporated into a theory of the strong QCD and electromagnetic interactions. Dirac magnetic monopoles are introduced as scalar bosons in a triplet of isovector fields within the framework of the QCD theory of colored quarks and gluons. Superheavy vector bosons are predicted to exist with masses of 328 OeV and 11.3 TeV.     

Search for a lighter Higgs boson in the Next-to-Minimal Supersymmetric Standard Model

Following the discovery of the Higgs boson with a mass of approximately 125 Ge V at the LHC, many studies have been performed from both the theoretical and experimental viewpoints to search for a new Higgs Boson that is lighter than 125 Ge V. We explore the possibility of constraining a lighter neutral scalar Higgs boson h_1 and a lighter pseudo-scalar Higgs boson a_1 in the Next-to-Minimal Supersymmetric Standard Model by restricting the next-to-lightest scalar Higgs boson h_2 to be the one observed at the LHC after applying the phenomenological constraints and those from experimental measurements. Such lighter particles are not yet completely excluded by the latest results of the search for a lighter Higgs boson in the diphoton decay channel from LHC data. Our results show that some new constraints on the Next-to-Minimal Supersymmetric Standard Model could be obtained for a lighter scalar Higgs boson at the LHC if such a search is performed by experimental collaborations and more data. The potentials of discovery for other interesting decay channels of such a lighter neutral scalar or pseudo-scalar particle are also discussed.     

Nonleptonic Interactions of Kaons in the Quark Confinement Model

Nonleptonic, electromagnetic decays of K-mesons and K°–K̄° transition are treated with the effective Hamiltonians with ΔS = 1, 2. Matrix elements of four-quark operators are calculated in the framework of Quark Confinement Model. The account of the intermediate scalar mesons turns out to allow to explain ΔI = 1/2 rule. The account of intermediate scalar and pseudo-scalar states leads to experimental value of mass difference of K_L°–K_S° mesons. The obtained values for nonleptonic and electromagnetic decay widths as well as mass difference Δm_LS are in good agreement with experimental data.     

Moments of heavy–light current correlators up to three loops

We consider moments of the non-diagonal vector, axial-vector, scalar and pseudo-scalar current correlators involving two different massive quark flavours up to three-loop accuracy. Expansions around the limits where one mass is zero and the equal-mass case are computed. These results are used to construct approximations valid for arbitrary mass values.     

STATIC SPHERICALLY SYMMETRIC SOLUTION OF EINSTEIN GRAVITY COUPLED TO ELECTRO-MAGNETIC AND SCALAR FIELDS

The static spherically symmetric solution of Einstein gravity coupled to electromagnetic and scalar fields is obtained under the consideration of the self-gravitational interaction of the electromagnetic and scalar fields, which is singularity-free and stable.     

Meson screening masses from lattice QCD with two light quarks and one strange quark

We present results for screening masses of mesons built from light and strange quarks in the temperature range of approximately between 140 MeV to 800 MeV. The lattice computations were performed with 2+1 dynamical light and strange flavors of improved (p4) staggered fermions along a line of constant physics defined by a pion mass of about 220 MeV and a kaon mass of 500 MeV. The lattices had temporal extents N _τ =4, 6 and 8 and aspect ratios of N _s /N _τ ≥4. At least up to a temperature of 140 MeV the pseudo-scalar screening mass remains almost equal to the corresponding zero temperature pseudo-scalar (pole) mass. At temperatures around 3T _c (T _c being the transition temperature) the continuum extrapolated pseudo-scalar screening mass approaches very close to the free continuum result of 2πT from below. On the other hand, at high temperatures the vector screening mass turns out to be larger than the free continuum value of 2πT. The pseudo-scalar and the vector screening masses do not become degenerate even for a temperature as high as 4T _c . Using these mesonic spatial correlation functions we have also investigated the restoration of chiral symmetry and the effective restoration of the axial symmetry. We have found that the vector and the axial-vector screening correlators become degenerate, indicating chiral symmetry restoration, at a temperature which is consistent with the QCD transition temperature obtained in previous studies. On the other hand, the pseudo-scalar and the scalar screening correlators become degenerate only at temperatures larger than 1.3T _c , indicating that the effective restoration of the axial symmetry takes place at a temperature larger than the QCD transition temperature.     

Electrodynamics of a Scalar Particle in a Plane Electromagnetic Wave Field

In the present paper, compact expressions are derived for the probability of photon emission by a scalar particle and for the probability of creating pairs of scalar particles in an arbitrary plane electromagnetic wave field. Based on these general expressions, the amplitude of elastic scattering of a scalar particle and the amplitude of elastic scattering of a photon are derived by the method of dispersion relations (in the first-order approximation for the fine-structure constant ₀ = e ²/4). The real components of these amplitudes determine the radiative corrections for particle masses in the examined fields. Some particular cases of the plane wave field are examined. In particular, the above-indicated amplitudes in the external electromagnetic field being a superposition of a constant crossed field and a plane elliptically polarized electromagnetic wave propagating along the direction orthogonal to the magnetic and electric components of the constant crossed field are investigated. The amplitude of elastic scattering of a scalar particle in an arbitrary plane electromagnetic wave field is also obtained by direct calculations of the corresponding mass operator of the scalar particle in this field.     

Electromagnetic waves in dielectrics with memory

We analyse electromagnetic wave propagation in a dielectric with memory of the Maxwell-Hopkinson type. We show that the components of the electric and magnetic fields satisfy two different scalar wave equations and we first look for their harmonic plane wave solutions. Then we prove that dielectrics with memory can also support approximate Courant-Hilbert waves. We discuss the equations to be solved to get all the components of the electromagnetic field from a scalar solution from each wave equation and TE, TM harmonic plane waves are explicitly given.     

Detecting dark energy in long baseline neutrino oscillations

In this paper, we discuss a possibility of studying properties of dark energy in long baseline neutrino oscillation experiments. We consider two types of models of neutrino dark energy. For one type of models the scalar field is taken to be quintessence-like and for the other phantom-like. In these models the scalar fields couple to the neutrinos to give rise to spatially varying neutrino masses. We will show that the two types of models predict different behaviors of the spatial variation of the neutrino masses inside the Earth and consequently result in different signals in long baseline neutrino oscillation experiments.     

The Scalar-photon Coupling with Mie Invariant Within the Scope of Bianchi Type-I Cosmological Model

We investigate the Bianchi type-I cosmological model with the scalar and electromagnetic fields possessing non-minimal couplings. They contain the Mie invariant that leads to the flat Friedman’s cosmological model. We found the lagrangian for interaction, which the isotropization process of the expansion takes place. Two cases are considered, when the Mie invariant is constat or time-dependent. We study the canonical scalar field and the phantom one.     

Torsion as Electromagnetism and Spin

We show that it is possible to formulate the classical Einstein-Maxwell-Dirac theory of spinors interacting with the gravitational and electromagnetic fields as the Einstein-Cartan-Kibble-Sciama theory with the Ricci scalar of the traceless torsion, describing gravity, and the torsion trace acting as the electromagnetic potential.     

Low- and high-energy expansion of heavy-quark correlators at next-to-next-to-leading order

We calculate three-loop corrections to correlation functions of heavy-quark currents in the low- and high-energy regions. We present 30 coefficients both in the low-energy and the high-energy expansion of the scalar and the vector correlator with non-diagonal flavour structure. In addition we compute 30 coefficients in the high-energy expansion of the diagonal vector, axial-vector, scalar and pseudo-scalar correlators. Possible applications of our new results are improvements of lattice-based quark-mass determinations and the approximate reconstruction of the full momentum dependence of the correlators.     

Time-dependent scalar Beltrami-Hertz potentials in free space

We have solved the Beltrami-Maxwell equations for free space in terms of time-dependent scalar functions, the so-called scalar Beltrami-Hertz potentials. The two Beltrami fields have been represented in terms of scalar Beltrami-Hertz potentials. While the method is formulated for general sources, it is at its most powerful when the impressed source current densities are unidirectional: each Beltrami field, a complex-valued vector, can then be derived from a single scalar Beltrami-Hertz potential. We have calculated the corresponding scalar Green function explicity and given closed-form solutions for dipolar sources. Finally, the connection between the Beltrami-Maxwell formalism and conventional electromagnetic theory has been re-affirmed.