Charged Scalar Bosons Research Articles

Charged scalar bosons in a Bonnor–Melvin-Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varLambda $$\\end{document} universe at conical approximation

The quantum dynamics of charged scalar bosons in a Bonnor–Melvin-Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varLambda $$\\end{document} universe is considered. In this study, the behavior of charged scalar bosons is explored within the framework of the Duffin–Kemmer–Petiau (DKP) formalism. Adopting a conical approximation (Λ≪1),\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\varLambda \\ll 1),$$\\end{document} we are considered two scenarios for the vector potential: a linear and quadratic vector potentials. In particular, the effects of this background in the equation of motion, phase shift, S-matrix, energy spectrum and DKP spinor are analyzed and discussed.

Bose–Einstein condensation of magnetized charged scalar bosons revisited

AbstractWe study the effects of a uniform and constant magnetic field on the Bose–Einstein condensation (BEC) of relativistic charged scalar bosons. The condensation of magnetized charged bosons is usually discussed in the weak or strong field regimes separately, and in each case, the properties predicted for the condensate are different. Here, we develop a low‐temperature analysis suitable for any field that allows us to observe how the gas behaves for intermediate values of the magnetic field. We find that BEC may occur at finite magnetic fields, despite the gas becoming effectively one‐dimensional due to Landau quantization of the momentum perpendicular to the magnetic axis.

Baryogenesis and gravitational waves in the Zee–Babu model

To explain the matter-antimatter asymmetry in the Zee–Babu (ZB) model, the sphaleron process in the baryogenesis scenario is calculated. It always satisfies the de-coupling condition and the strength of phase transition (S) is always greater than 1 in the presence of triggers other than that in the Standard Model, which are singly (h^{pm }) and doubly (k^{pm pm }) charged scalar bosons. Sphaleron energies are in the range of 5-10 TeV, in calculation with bubble profiles containing free parameters and assuming nuclear bubbles of h^{pm } and k^{pm pm } are very small. We tested the scaling law of sphaleron again with an average error of 10%. When the temperature is close to the critical one (T_c), the density of nuclear bubble is produced very large and decreases as the temperature decreases. The key parameter is alpha which results in the gravitational wave density parameter (Omega h^2) in the range of 10^{-14} to 10^{-12} when beta /H^*=22.5, this is not enough to detect gravitational waves from electroweak phase transition (EWPT) according to the present LISA data but may be detected in the future. As the larger strength of phase transition is, the more alpha increases (this increase is almost linear with S), the larger the gravitational wave density parameter is. Also in the context of considering the generation of gravitational waves, in the ZB model we calculated alpha sim text {a few} times 10^{-2}ll 1, so rigorously conclude that the EWPT is not strong even though S>1. We also suggest that, for a model with a lot of extra scalar particles and particles which play a role in mass generation, the stronger the EWPT process and the larger Omega h^2 can be.

NLO corrections to the B -hadron energy distribution of heavy charged Higgs boson decay in the general-mass-variable-flavor-number scheme

Since there is no fundamental charged scalar boson in the Standard Model (SM) of particle physics then the discovery of each charged scalar boson would clearly represent an instant evidence of physics beyond the SM. In this regard, searching for charged Higgs bosons is unique and have been the center of attention of colliders such as the CERN LHC. In the present work, we study a proposed channel to search for heavy charged Higgses at the current and future colliders. In this channel we study the scaled-energy distribution of bottom-flavored mesons ($B$) inclusively produced in heavy charged Higgs decay, i.e., ${H}^{+}\ensuremath{\rightarrow}t\overline{b}\ensuremath{\rightarrow}B+X$. This study is performed within the framework of two Higgs doublet model using the general-mass variable-flavor-number scheme where the $b$-quark mass is preserved from the beginning. Our results will be compared with the ones calculated in the zero-mass variable-flavor-number scheme where the zero mass approximation is adopted for the bottom quark. We find that most reliable predictions can be achieved through the massive scheme.

Electromagnetic quantum shifts in relativistic Bose-Einstein condensation

We compute deviations from ideal gas behavior of the pressure, density, and Bose-Einstein condensation temperature of a relativistic gas of charged scalar bosons caused by the current-current interaction induced by electromagnetic quantum fluctuations treated via scalar quantum electrodynamics. We obtain expressions for those quantities in the ultra-relativistic and nonrelativistic limits, and present numerical results for the relativistic case.

Probing doubly charged scalar bosons from the doublet at future high-energy colliders

The isospin doublet scalar field with hypercharge 3/2 is introduced in some new physics models such as tiny neutrino masses. Detecting the doubly charged scalar bosons from the doublet field can be a good probe of such models. However, their collider phenomenology has not been examined sufficiently. We investigate collider signatures of the doubly and singly charged scalar bosons at the LHC for the high-luminosity upgraded option (HL-LHC) by looking at transverse mass distributions etc. With the appropriate kinematical cuts we demonstrate the background reduction in the minimal model in the following two cases depending on the mass of the scalar bosons. (1) The main decay mode of the singly charged scalar bosons is the tau lepton and missing (as well as charm and strange quarks). (2) That is into a top bottom pair. In the both cases, we assume that the doubly charged scalar boson is heavier than the singly charged ones. We conclude that the scalar doublet field with $Y = 3/2$ is expected to be detectable at the HL-LHC unless the mass is too large.

One-loop Kubo estimations of the shear and bulk viscous coefficients for hot and magnetized bosonic and fermionic systems

The expressions of the shear viscosity and the bulk viscosity components in the presence of an arbitrary external magnetic field for a system of hot charged scalar bosons (spin 0) as well as for a system of hot charged Dirac fermions (spin $\frac{1}{2}$) have been derived by employing the one-loop Kubo formalism. This is done by explicitly evaluating the thermomagnetic spectral functions of the energy-momentum tensors using the real time formalism of finite temperature field theory and the Schwinger proper time formalism. In the present work, a rich quantum field theoretical structure in the expressions of the viscous coefficients in nonzero magnetic field are found, which are different from their respective expressions obtained earlier via kinetic-theory-based calculations; though, in the absence of a magnetic field, the one-loop Kubo and the kinetic-theory-based expressions for the viscosities are known to be identical. We have identified that Kubo and kinetic-theory-based results of viscosity components follow a similar kind of temperature and magnetic field dependency. The relaxation time and the synchrotron frequency in the kinetic theory formalism are realized to be connected, respectively, with the thermal width of propagator and the transitions among the Landau levels of the charged particles in the Kubo formalism. We believe that the connection of the latter quantities is quite new and probably the present work is the first time addressing this interpretation along with the new expressions of viscosity components, not seen in existing works.

Analysing the charged scalar boson contribution to the charged-current B meson anomalies

Experimental measurements collected by the BABAR, Belle, and LHCb experiments on different observables associated with the semileptonic transition , indicate the existence of disagreement respect with the Standard Model predictions. We analyze the charged scalar boson contributions to these charged-current B meson anomalies within the framework of two Higgs doublet model (2HDM) with the most general Yukawa couplings to quarks and leptons from the third generation, involving left-handed and right-handed (sterile) neutrinos. We perform a phenomenological study of the Yukawa couplings parameter space that accommodates these anomalies. We consider the most recent data from HFLAV world-average and Belle combination, and the upper limits and 10%. In addition, we include in our study the prospect measurements on R(D (*)) that the Belle II experiment could achieve and explore, for the first time, the future implications for the corresponding charged scalar Yukawa couplings. This analysis updates the existing literature and includes new important observables. Our results show that current experimental data and Belle II projection favor the interpretation of a charged scalar boson interacting with right-handed neutrinos. Furthermore, as a side analysis regarding the charged scalar boson interpretation, we revisit the relation between R(D*) and by investigating whether the claim that pseudoscalar new physics interpretations of R(D*) are implausible due to the B c lifetime is still valid, to the light of the recent data and Belle II prospects on R(D*). Lastly, we reexamine addressing the R(D (*)) anomalies in the context of the 2HDM of type II. We show that with the current Belle combined data is possible to obtain an available parameter space on the plane for a simultaneous explanation of the anomalies, in consistency with and bounds from inclusive radiative B decays. Moreover, projections at the Belle II experiment suggest that the 2HDM of type II would be no longer disfavored.

Bopp–Podolsky scalar electrodynamics propagators and energy-momentum tensor in covariant and light-front coordinates

We consider the interaction between a charged scalar boson and the Bopp–Podolsky gauge fields. The Bopp–Podolsky (BP) electrodynamics possesses both massive and massless propagation modes for the photon, while preserving gauge invariance. We obtain the propagator of all fields present in the model for the higher-order generalizations of the linear covariant, light-front and doubly transverse light-front gauges. Although BP’s original model is described by a higher-order derivatives Lagrangian, it is possible to work with an equivalent reduced-order version by means of the introduction of an auxiliary vector field. We compute the gauge-invariant improved energy-momentum tensor for the full reduced-order interacting BP model. Besides the more traditional front-form view, we also discuss the light-front perspective in both versions of the model. Within a Lagrangian framework approach, we maintain explicit covariance at all steps and show that the field propagators, as well as the energy-momentum tensor, can be cast into a light-front closed form using specific properties of general coordinate transformations.

Type II seesaw models with modular A4 symmetry

We discuss type-II seesaw models adopting modular $A_4$ symmetry in supersymmetric framework. In our approach, the models are classified by the assignment of $A_4$ representations and modular weights for leptons and triplet Higgs fields. Then neutrino mass matrix is characterized by modulus $\tau$ and two free parameters. Carrying out numerical analysis, we find allowed parameter sets which can fit the neutrino oscillation data. For the allowed parameter sets, we obtain the predictions in neutrino sector such as CP violating phases and the lightest neutrino mass. Finally we also show the predictions for the branching ratios of doubly charged scalar boson focusing on the case where the doubly charged scalar boson dominantly decays into charged leptons.

Search for doubly charged scalar bosons decaying into same-sign W boson pairs with the ATLAS detector

A search for doubly charged scalar bosons decaying into W boson pairs is presented. It uses a data sample from proton–proton collisions corresponding to an integrated luminosity of 36.1 fb^mathrm {-1} collected by the ATLAS detector at the LHC at a centre-of-mass energy of 13 TeV in 2015 and 2016. This search is guided by a model that includes an extension of the Higgs sector through a scalar triplet, leading to a rich phenomenology that includes doubly charged scalar bosons H^{pm pm }. Those bosons are produced in pairs in proton–proton collisions and decay predominantly into electroweak gauge bosons H^{pm pm }rightarrow W^{pm } W^{pm }. Experimental signatures with several leptons, missing transverse energy and jets are explored. No significant deviations from the Standard Model predictions are found. The parameter space of the benchmark model is excluded at 95% confidence level for H^{pm pm } bosons with masses between 200 and 220 GeV.

Chromomagnetic and chromoelectric dipole moments of the top quark in the fourth-generation THDM

The chromomagnetic dipole moment (CMDM) and chromoelectric dipole moment (CEDM) of the top quark are calculated at the one-loop level in the framework of the two-Higgs doublet model with four fermion generations (4GTHDM), which is still consistent with experimental data and apart from new scalar bosons (${H}^{0}$, ${A}^{0}$, and ${H}^{\ifmmode\pm\else\textpm\fi{}}$) and quarks (${b}^{\ensuremath{'}}$ and ${t}^{\ensuremath{'}}$) predicts new sources of $CP$ violation via the extended $4\ifmmode\times\else\texttimes\fi{}4$ CKM matrix. Analytical expressions for the CMDM and CEDM of a quark are presented both in terms of Feynman parameter integrals, which are explicitly integrated, and Passarino-Veltman scalar functions, with the main contributions arising from loops carrying the scalar bosons accompanied by the third- and fourth-generation quarks. The current bounds on the parameter space of the 4GTHDM are discussed and a region still consistent with the LHC data on the 125 GeV Higgs boson and the oblique parameters is identified. It is found that the top quark CMDM, which is induced by all the scalar bosons, can reach values of the order of ${10}^{\ensuremath{-}2}--{10}^{\ensuremath{-}1}$. As for the top quark CEDM, it only receives contributions from the charged scalar boson and can reach values of the order of ${10}^{\ensuremath{-}20}--{10}^{\ensuremath{-}19}\text{ }\text{ }\mathrm{ecm}$ for relatively light ${m}_{{H}^{\ifmmode\pm\else\textpm\fi{}}}$ and heavy ${m}_{{b}^{\ensuremath{'}}}$, with the dominant contribution arising from the $b$ quark. The CEDM would be the most interesting prediction of this model as it can be larger than the value predicted by the usual THDMs by one order of magnitude.

Discriminating leptonic Yukawa interactions with doubly charged scalar at the ILC

We explore discrimination of two types of leptonic Yukawa interactions associated with Higgs triplet, L¯LcΔLL, and with SU(2) singlet doubly charged scalar, e¯Rck++eR. These interactions can be distinguished by measuring the effects of doubly charged scalar boson exchange in the e+e−→ℓ+ℓ− processes at polarized electron-positron colliders. We study a forward-backward asymmetry of scattering angular distribution to estimate the sensitivity for these effects at the ILC. In addition, we investigate prospects of upper bounds on the Yukawa couplings by combining the constraints of lepton flavor violation processes and the e+e−→ℓ+ℓ− processes at the LEP and the ILC.

Weak dipole moments of the tau lepton in models with an extended scalar sector

We consider renormalizable couplings of neutral $\phi$, singly $\phi^\pm$, and doubly charged $\phi^{\pm\pm}$ scalar bosons to leptons and the $Z$ gauge boson and calculate the one-loop contributions to the anomalous weak magnetic dipole moment (AWMDM) $a_\tau^W$ and the weak electric dipole moment (WEDM) $d_\tau^W$ of a charged lepton in a model independent way. The analytic expressions are presented in terms of both parametric integrals and Passarino-Veltman scalar functions. Among the new contributions, there are those arising from the vertices of the type $\phi^\pm W^\mp Z$ and $Z \phi_i\phi_j$ ($i\ne j$), along with contributions from doubly charged scalar bosons. Both $a_\tau$ and $d_\tau^W$ are evaluated in several scenarios , first in a model independent way and then within some popular models, such as two-Higgs doublet models (THDMs), multiple-Higgs doublet models and Higgs triplet models. As far as $a_\tau^W$ is concerned, its real part reaches values as high as $10^{-10}-10^{-9}$ for masses of the new scalar bosons in the 200 GeV range, whereas the imaginary part is one or two orders of magnitude below. On the other hand, the most promising scenario for a nonvanishing WEDM is offered by a $CP$-violating THDM in a scenario where the heavy neutral scalar bosons are a mixture of $CP$ eigenstates. It is found that the real part of $d_\tau^W$ is of the order of $10^{-24}$ ecm and its imaginary part can reach the $10^{-26}$ ecm level for masses of the new scalar bosons of the order of a few hundred of GeVs. Both the tau AWMDM and WEDM decrease dramatically as the scalar boson masses increase.

Magnetic field effect on charged scalar pair creation at finite temperature

In this work we explore the effects of a weak magnetic field and a thermal bath on the decay process of a neutral scalar boson into two charged scalar bosons. Our findings indicate that magnetic field inhibits while temperature enhances the pair production. The employed formalism allows us to isolate the contribution of magnetic fields in vacuum, leading to a separate analysis of the effects of different ingredients. This is essential since the analytical computation of the decay width necessarily needs of some approximation and the results that can be found in the literature are not always coincident. We perform the calculation in vacuum by two different weak field approximations. The particle pair production in vacuum was found to coincide with finite temperature behavior, which is opposite to results obtained by other authors in scenarios that involve neutral particles decaying into a pair of charged fermions. Among other differences between these scenarios, we traced that the analytical structure of the self-energy imposed by the spin of particles involved in the process is determinant in the behavior of the decay rate with the magnetic field.

Modified top quark condensation model with the extra heavy fermion, the 125 GeV pseudo-Goldstone boson, and the additional heavy scalar bosons

We discuss the modified top quark condensation model proposed in Ref. 54. This construction was inspired by the top-seesaw scenario, in which the extra heavy fermion [Formula: see text] that may be paired with the top quark is added. Besides, this model incorporates the ideas of the little Higgs scenario, in which the 125 GeV scalar particle appears as a pseudo-Goldstone boson. This model admits (in addition to the 125 GeV scalar boson [Formula: see text]) the heavier scalar excitation [Formula: see text]. We consider the region of parameters, where its mass is [Formula: see text], the width of [Formula: see text] is [Formula: see text], while the mass of the heavy fermion is [Formula: see text]. We find that in this model the value of the cross-section [Formula: see text] for [Formula: see text] is essentially smaller than the present experimental upper bound. Besides, we find that for the chosen values of parameters there should exist the CP-even scalar boson with mass [Formula: see text] and very small width. In addition, the model predicts the existence of the extra neutral CP-even scalar boson and the charged scalar boson with masses of the order of 1 TeV.

Searching for the heavy charged custodial fiveplet Higgs boson in the Georgi-Machacek model at the International Linear Collider

The Georgi-Machacek (GM) model is one of many Beyond Standard Model scenarios with an extended scalar sector which can group under the custodial $\rm SU(2)_C$ symmetry into a fiveplet, a triplet, and two singlets. The heavy charged custodial fiveplet Higgs $\rm H_5^{\pm}$ are typical particles in GM model which couple to the electroweak gauge bosons, therefore provide a good testing ground for the detection of the $\rm H^\pm W^\mp Z$ vertex. The neutral custodial fiveplet Higgs $\rm H_5^{0}$ in the GM model has the same mass with $\rm H_5^{\pm}$ and couples to the electroweak gauge bosons $\rm W^+ W^-$ and ZZ both. We study the discovery prospects of the exotic scalar bosons $\rm H_5^{\pm}$ and $\rm H_5^{0}$ at the International Linear Collider(ILC) via the vector boson associated production processes, and discuss two different decay modes for both charged and neutral scalars. The discovery potential is discussed. Testing the mass degeneracy of charged and neutral scalar bosons in the GM model is also considered.

WWV ( V=γ , Z ) vertex in the Georgi-Machacek model

The $CP$-even static form factors $\mathrm{\ensuremath{\Delta}}{\ensuremath{\kappa}}_{V}^{\ensuremath{'}}$ and $\mathrm{\ensuremath{\Delta}}{Q}_{V}$ ($V=\ensuremath{\gamma}$, $Z$) associated with the $WWV$ vertex are studied in the context of the Georgi-Machacek model (GMM), which predicts nine new scalar bosons accommodated in a singlet, a triplet, and a fiveplet. General expressions for the one-loop contributions to $\mathrm{\ensuremath{\Delta}}{\ensuremath{\kappa}}_{V}^{\ensuremath{'}}$ and $\mathrm{\ensuremath{\Delta}}{Q}_{V}$ arising from neutral, singly, and doubly charged scalar bosons are obtained in terms of both parametric integrals and Passarino-Veltman scalar functions, which can be numerically evaluated. It is found that the GMM yields 15 (28) distinct contributions to $\mathrm{\ensuremath{\Delta}}{\ensuremath{\kappa}}_{\ensuremath{\gamma}}^{\ensuremath{'}}$ and $\mathrm{\ensuremath{\Delta}}{Q}_{\ensuremath{\gamma}}$ ($\mathrm{\ensuremath{\Delta}}{\ensuremath{\kappa}}_{Z}^{\ensuremath{'}}$ and $\mathrm{\ensuremath{\Delta}}{Q}_{Z}$), though several of them are naturally suppressed. A numerical analysis is done in the region of parameter space still consistent with current experimental data and it is found that the largest contributions to $\mathrm{\ensuremath{\Delta}}{\ensuremath{\kappa}}_{V}^{\ensuremath{'}}$ arise from Feynman diagrams with two nondegenerate scalar bosons in the loop, with values of the order of $a={g}^{2}/(96{\ensuremath{\pi}}^{2})$ reached when there is a large splitting between the masses of these scalar bosons. As for $\mathrm{\ensuremath{\Delta}}{Q}_{V}$, it reaches values as large as ${10}^{\ensuremath{-}2}a$ for the lightest allowed scalar bosons, but it decreases rapidly as one of the masses of the scalar bosons becomes large. Among the new contributions of the GMM to the $\mathrm{\ensuremath{\Delta}}{\ensuremath{\kappa}}_{V}^{\ensuremath{'}}$ and $\mathrm{\ensuremath{\Delta}}{Q}_{V}$ form factors are those induced by the ${H}_{5}^{\ifmmode\pm\else\textpm\fi{}}{W}^{\ensuremath{\mp}}Z$ vertex, which arises at the tree level and is a unique prediction of this model.

Δk’v and ΔQV (V =γ, Z) form factors in the Georgi-Machacek model

The CP-even static form factors Δk’v and ΔQV (V =γ, Z) associated with the WWV vertex are studied in the context of the Georgi-Machacek model (GMM), which predicts nine new scalar bosons accommodated in a singlet, a triplet and a fiveplet. General expressions for the one-loop contributions to Δk’v and ΔQV arising from neutral, singly and doubly charged scalar bosons are obtained in terms of both parametric integrals and Passarino- Veltman scalar functions, which can be numerically evaluated. It is found that the GMM yields 15 (28) distinct contributions to Δk’γ and ΔQγ (Δk'z and ΔQz), though several of them are naturally suppressed.

Three-loop neutrino mass model with doubly charged particles from isodoublets

We propose a new type of a three-loop induced neutrino mass model with dark matter candidates which are required for the neutrino mass generation. The smallness of neutrino masses can be naturally explained without introducing super heavy particles, namely, much heavier than a TeV scale and quite small couplings as compared to the gauge couplings. We find that as a bonus, the anomaly of the muon anomalous magnetic moment can simultaneously be explained by loop effects of new particles. In our model, there are doubly charged scalar bosons and leptons from isospin doublet fields which give characteristic collider signatures. In particular, the doubly charged scalar bosons can decay into the same-sign dilepton with its chirality of both right-handed or left- and right-handed. This can be a smoking gun signature to identify our model and be useful to distinguish other models with doubly charged scalar bosons at collider experiments.