Charged Scalar Bosons Research Articles

Heavy mass expansion, light-by-light scattering through pointlike quanta, and the anomalous magnetic moment of the muon

Contributions from light-by-light scattering to (g_\mu-2)/2, the anomalous magnetic moment of the muon, are mediated by the exchange of charged fermions or scalar bosons. Assuming large masses M for the virtual particles and employing the technique of large mass expansion, analytical results are obtained for virtual fermions and scalars in the form of a series in (m_\mu /M)^2. This series is well convergent even for the case M=m_\mu. For virtual fermions, the expansion confirms published analytical formulae. For virtual scalars, the result can be used to evaluate the contribution from charged pions. In this case our result confirms already available numerical evaluations, however, it is significantly more precise.

Gauged dimension bubbles

Some of the peculiar electrodynamical effects associated with gauged ``dimension bubbles'' are presented. Such bubbles, which effectively enclose a region of 5D spacetime, can arise from a 5D theory with a compact extra dimension. Bubbles with thin domain walls can be stabilized against total collapse by the entrapment of light charged scalar bosons inside the bubble, extending the idea of a neutral dimension bubble to accommodate the case of a gauged U(1) symmetry. Using a dielectric approach to the 4D dilaton-Maxwell theory, it is seen that the bubble wall is almost totally opaque to photons, leading to a new stabilization mechanism due to trapped photons. Photon dominated bubbles very slowly shrink, resulting in a temperature increase inside the bubble. At some critical temperature, however, these bubbles explode, with a release of radiation.

Neutrinoless double beta decay with and without Majoron-like boson emission in a 3-3-1 model

We consider the contributions to the neutrinoless double beta decays in a $SU(3)_L\otimes U(1)_N$ electroweak model. We show that for a range of the parameters in the model there are diagrams involving vector-vector-scalar and trilinear scalar couplings which can be potentially as contributing as the light massive Majorana neutrino exchange one. We use these contributions to obtain constraints upon some mass scales of the model, like the masses of the new charged vector and scalar bosons. We also consider briefly the decay in which besides the two electrons a Majoron-like boson is emitted.

Zee model and phenomenology of lepton sector

The virtual effects of the Zee charged scalar boson on the lepton-family-number (LFN) violating processes are studied. We obtain the constraints on the individual Yukawa coupling constants of the Zee boson to leptons. Using these constraints, we predict the upper bounds on the muonium-antimuonium conversion probability, the branching fractions of the LFN violating decays such as $\tau \to e\gamma$, $\tau \to \mu\gamma$, $\tau^- \to \mu^+e^-e^-$ and $\tau \to e^+\mu^-\mu^-$. The contribution of the Zee boson to the muon anomalous magnetic moment is also considered

Signature of exotic particles in light by light scattering

We discuss the implications on light by light scattering of two kinds of exotic particles: doubly charged scalar bosons and doubly charged fermions; the virtual effects of a nonstandard singly charged gauge boson are also examined. These particles, if their masses lie in the range 0.1–1.0 TeV, will have a clear signature in the future linear colliders. The present analysis has the advantage that it depends only on electromagnetic symmetry, so it is applicable to any model which predicts this class of particles. In particular, our results have interesting consequences on left-right models and their supersymmetric extension.

Charged Higgs boson and stau phenomenology in the simplest R-parity breaking model

We consider the charged scalar boson phenomenology in the simplest effective low-energy R-parity breaking model characterized by a bilinear violation of R-parity in the superpotential. This induces a mixing between staus and the charged Higgs boson. We show that the charged Higgs boson mass can be lower than expected in the MSSM, even before including radiative corrections. We also study the charged scalar boson decay branching ratios and show that the R-parity-violating decay rates can be comparable or even bigger than the R-parity conserving ones. Moreover, if the stau is the LSP it will have only decays into standard model fermions. These features could have important implications for charged supersymmetric scalar boson searches at future accelerators.

Strong Energy Condition of Simple Gauge Field System

An investigation is carried out for the violation of the strong energy condition by a generic field system consisting of charged scalar boson condensate, fermions, and U (1) gauge field. The Bose-Einstein condensation of the system is also studied by the Hamiltonian formulation. It is found that the strong energy condition can be violated by this quantum field system at high densities.

Unusual charged Higgs boson signals at CERN LEP 2

We have made a detailed study of the signals produced at LEP-2 from charged scalar bosons whose dominant decay channels are into four fermions. The event rates as well as kinematics of the final states are discussed when such scalars are either pair-produced or are generated through a tree-level interaction involving a charged scalar, the W and the Z. The backgrounds in both cases are discussed. We also suggest the possibility of reconstructing the mass of such a scalar at LEP-2.

Possible resonances in μ+e− → μ−e+ collisions

We study the possibility of discovering resonances in μ + e − → μ − e + and e − e − → μ − μ − collisions. We begin with the closely related problem of muonium-antimuonium transitions, where the experimental limit has just been improved by one order of magnitude. We show that the new limit enters a rather interesting mass and Yukawa coupling domain for neutral scalar bosons. The stringent μ → eγ decay is evaded by invoking some multiplicative lepton number. Neutral and doubly charged scalar bosons give rise to distinguishable effects in muonium transitions. Alternatively, they could show up as spectacular resonance peaks in high energy μ + e − → μ − e + and e − e − → μ − μ − collisions, respectively. This could occur independent of whether, but especially when, muonium-antimuonium transitions are experimentally observed.

Condensation and magnetization of the relativistic Bose gas

We show that the relativistic charged scalar boson gas exhibits a genuine Meissner-Ochsenfeld effect of the Schafroth form at fixed supercritical density. As in the well-known non-relativistic case, this total expulsion of a magnetic field is caused by the condensation of the Bose gas at vanishing magnetic field. In the course of these considerations, we present alternative proofs of the absence of Bose-Einstein condensation of a relativistic scalar boson gas, in any finite local magnetic field in less than five dimensions. The results are discussed in the context of kaon condensation in neutron stars.

Thermal background corrections to the neutrino electromagnetic vertex in models with charged scalar bosons.

We calculate the correction to the neutrino electromagnetic vertex due to background of electrons in a large class of models, as the supersymmetric model with explicit breaking of R-parity, where charged scalar bosons couple to leptons and which are able to provide an astrophysically interesting value for the neutrino magnetic (electric) moment, $\mu_\nu\sim 10^{-12}\:\mu_B$. We show that the medium contribution to the chirality flipping magnetic (electric) dipole moment is not significant, however a new chirality flipping, but helicity conserving, term arises. It signals the presence of ${\cal CP}$ and ${\cal CPT}$ asymmetries in the medium and is associated to the longitudinal photon and therefore disappears in the vacuum. We estimate the contribution of this new term to the rate of the plasmon decay process $\gamma_{pl}\rightarrow \nu\nu$ in the core of degenerate stars, showing that it can be comparable with the contribution coming from the vacuum magnetic (dipole) moment. We also calculate the correction to the effective potential of a propagating neutrino in presence of a magnetic field due to a chirality preserving contribution to the diagonal magnetic moment from the medium. This contribution is identical for particles and antiparticles and so need not to vanish for Majorana neutrinos.

Charged weak scalar bosons

We assume that the weak W± bosons be composed of two massless spin-1/2 constituents. Then, weak charged scalars Φ± must exist. Analysing the effective low-energy electromagnetic couplings and the WΦ transition vertex, we obtain novel results. They are applied to the reaction γ→Φ+Φ-. Total cross-sections and angular distributions are displayed and compared with the results following from spin-0 electrodynamics. The Born approximations respect partial-wave unitarity at high energies. Decay processes are explored. The results give rise to the expectationm Φ≈m W.

Massive neutrinos and electroweak baryogenesis

We show that certain models for neutrino masses that lead to the MSW explanation of the solar neutrino data and/or the hot dark matter component in the universe can also naturally allow for the successful generation of the cosmological baryon asymmetry at the electroweak scale. This follows either because the experimental Higgs boson mass limit is weakened due to the smaller production rate and the presence of sizeable invisible decays involving majoron emission, or due to the effect of additional electrically charged scalar bosons which substantially modify the condition for successful baryogenesis.

SU(3)

We consider a gauge model based on $SU(3)\otimes U(1)$ symmetry in which the lepton number is violated explicitly by charged scalar and gauge bosons, including a vector field with double electric charge. Although there exist in the literature several models based on a $SU(3)\otimes U(1)$ gauge symmetry, our model has a different representation content and a quite different new physics at an, in principle, arbitrary mass scale. This is possibly the simplest way to enlarge the gauge group $SU_L(2)\otimes U_Y(1)$ in order to have doubly charged gauge bosons, without losing the natural features of the standard electroweak model. The price we must pay is the introduction of exotic quarks, with electric charge $5/3$ and $-4/3$. A previous version of the model was considered several months ago concerning the possibility that in this kind of models neutrinoless double beta decay proceeds even for massless neutrinos and with scalar exchange instead of vector exchange. Our work is in press in Physical Review D.

The production of charged scalar bosons at the HERA-collider

Using the minimal extension of the standardmodel which allows for charged scalar bosons in the model we compute the total cross section for the production of these charged scalar bosons at HERA. The production rates are found to be small.

Probing the WHZ vertex in E6 models at colliders.

We consider the production of charged Higgs scalar bosons at ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ and hadron colliders as a probe of the ${\mathrm{WHZ}}_{i}$ vertex which can be nonzero at the tree level in ${\mathrm{E}}_{6}$ models. Substantial cross sections at both kinds of colliders are possible but backgrounds are very substantial. These backgrounds can, in principle, be dealt with. ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilation with a light ${Z}_{2}$ may offer the best hope of probing this new interaction.

Left-right symmetry and finite one-loop Dirac neutrino mass

We present a modified version of the left-right symmetric model that includes a charged singlet scalar boson where the neutrino is massless at the tree level and acquires a smal and finite Dirac mass at the one-loop level. In the case if three families of fermions, it predicts m ve=0 and the other two neutrinos are massive with v τ lighter than v v . The model also predicts large magnetic moments and v μ → v e+ ψ decay rates. The new feature of the model is the inclusion of singlet charged heavy fermions which mix with the light quarks and leptons, leading to the existence of tree-level flavor-changing neutral currents, which can provide tests of the model.

Quantum mechanics of a charged scalar boson with respect to an observer’s past light cone

An observer whose instantaneous ‘‘here-now’’ has Minkowski coordinates zλ(λ=0,1,2,3) can only be aware of events within or on the past light cone with vertex at zλ. In conventional quantum mechanics his current quantum state would refer to some spacelike surface containing zλ, for example, x0=z0. This is, however, a region of space-time about which the observer can know nothing except the single event zλ, his current here-now. The aim of the present paper is to give a version of quantum mechanics in which the intrinsically unknowable ‘‘quantum state at the present time’’ is replaced by the ‘‘quantum state on the past light cone.’’ The theory is an extension and adaptation of Dirac’s point mechanics [Rev. Mod. Phys. 21, 392 (1949)].

Gauge equivalence of the electrodynamics of charged bosons

The quantum electrodynamics of charged scalar and vector bosons is formulated in the Lorentz gauge, and the effect of the charged particle–photon interaction on the subsidiary condition is explicitly taken into account. The results are extensions of earlier work on spinor quantum electrodynamics, but the presence of seagull vertices and anomalous current commutators in the case of the charged bosons make the extensions nontrivial. An operator gauge transformation that encompasses equations of motion as well as the commutator algebra of the field operators is developed; it is used to transform the theory from the Lorentz gauge to the Coulomb gauge.

Mass spectrum from four-boson contact interaction

Abstract Following the analysis of Nambu for four-fermion interactions, an attempt is made to explore the possibility of a mass spectrum for a self-coupled charged scalar or pseudoscalar boson (spin zero) field. It is found that there can be a bound state of zero mass only if the vertex function is momentum dependent. Assuming the existence of this particle, the strength of its coupling is determined. All couplings turn out to be ‘strong’, but finite. It is also noted that the two-meson scattering cross section exhibits a maximum. The possibility of existence of a bound vector meson is also discussed.