Unitarity bounds in the vector condensate model of electroweak interactions

We replace the standard model scalar doublet by a doublet of vector fields and generate masses by dynamical symmetry breaking. Oblique radiative corrections are small if the new vector bosons (B ⁺,B ⁰) are heavy. In this note it is shown that the model has a low momentum scale and above Λ?2 TeV it does not respect the perturbative unitarity. From tree-graph unitarity the allowed region ofB ⁺ (B ⁰) mass is estimated asm _B ⁺≥333 GeV (m _B ⁰≥373 GeV) at Λ=1 TeV.     

Masses of the t and the b quark and their mass ratio m b /m t as a consequence of a dynamical breakdown of SU L (2) symmetry

A model (of the type of the Nambu-Jona-Lasinio model) where the t and the b quark simultaneously acquire dynamical masses m _t and m _b is constructed to describe a dynamical breakdown of chiral and weak SU _L(2) symmetry. That the ratio x=m _b/m _t is small may imply that, at high energies, the energy scales of isoscalar vector exchange and isoscalar scalar exchange between the quarks are markedly different $(M_V \sim \sqrt x M_S )$ . The spectrum of composite scalar states of the model and the mechanism that causes the transformation of Goldstone bosons of the system under consideration into components of vector bosons of local SU _L(2) symmetry are investigated.     

Speculations on a strongly interacting Higgs sector

Using the 1/N expansion, we argue that the O_2N Higgs-Goldstone model may be a good indicator of the behavior of the standard SU₂ ? U₁ electroweak model in the non-perturbative limit of a strongly interacting Higgs sector. We emphasize that there remains a physical scalar particle or resonance σ (Higgs remnant), whose mass (and width) will be set by the weak scale. However, its coupling to vector bosons is expected to be much stronger than the standard model Higgs of comparable mass. This provides evidence that there is an upper limit to the Higgs mass in the hundreds of GeV, regardless of whether naturalness constraints are imposed on the parameters of the effective lagrangian. We conclude with some comments about the possible relevance of this particle to the radiative events observed at the CERN $\text{p}\text{p}$ collider.     

Non-standard gauge-boson self-interactions within a gauge invariant model

We examine dimension-six extensions of the standard electroweak Lagrangian which are invariant under localSU(2) _L ×U(1) _Y -transformations. The dimensionfour trilinear and quadrilinear effective interactions of the vector bosons with one another are found to coincide with the vector boson interactions previously derived from globalSU(2) weak isospin symmetry broken by electromagnetism. Supplementing the model by a well-known dimension-six single-parameter quadrupole interaction leads to the most general vector boson self-couplings that can be obtained by addition of dimension-six terms to the standard Lagrangian. We examine in some detail anotherSU(2) _L ×U(1) _Y -symmetric interaction which containsW ₃ B mixing and modifies both vector boson self-couplings and fermionic interactions. Independently of being strongly constrained by the LEP 1 data, the addition of this interaction to the above-mentioned non-standard ones does not change the form of the trilinear and quadrilinear non-standard self-couplings of the vector bosons. Therefore, while being interesting in itself with respect to LEP 1 physics, this term is irrelevant with respect to the phenomenology of the vector-boson self-interactions.     

A new state of hadronic matter at high density

We propose in this article that if the chemical potential exceeds a critical value in dense hadronic medium, a first-order phase transition to a new state of matter with Lorentz symmetry spontaneously broken (in addition to the explicit breaking) takes place. As a consequence, light vector mesons get excited as “almost” Goldstone bosons. Since the light vector mesons dominantly couple to photons, the presence of these new vector mesons could lead to an enhancement in the dilepton production from dense medium at an invariant mass lower than the free-space vectormeson mass. We provide a low-energy quark model which demonstrates that the above scenario is a generic case for quark theories with a strong interaction in the vector channel. We discuss possible relevance of this phase to the phenomenon of the enhanced dilepton production at low invariant masses in relativistic heavy-ion collisions.     

A light neutral intermediate vector boson without large e+e−→ μ+μ− asymmetries

An effective SU(2)×U(1)×U(1)' electroweak theory is shown to permit the occurence of a pair of neutral intermediate vector bosons with masses 40 GeV?m_light?70 GeV, m^W.S._Z⁰<m_heavy?100 GeV. Neutrino neutral current interactions are shown to be the same as in the standard electroweak model, and e⁺e^?→μ⁺μ^? forward-backward asymmetries are within experimental bounds for m_light?40 GeV.     

Uncertainties in the proton lifetime

We discuss the masses of the leptoquark bosons m_x and the proton lifetime in grand unified theories based principally on SU(5). It is emphasized that estimates of m_x based on the QCD coupling and the fine structure constant are probably more reliable than those using the experimental value of sin²θ_w. Uncertainties in the QCD Λ parameter and the correct value of α are discussed. We estimate higher-order effects on the evolution of coupling constants in a momentum-space renormalization scheme. It is shown that increasing the number of generations of fermions beyond the minimal three increases m_x by almost a factor of 2 per generation. Additional uncertainties exist for each generation of technifermions that may exist. We discuss and discount the possibility that proton decay could be “Cabibbo rotated” away, and a speculation that Lorentz invariance may be violated in proton decay at a detectable level. We estimate that in the absence of any substantial new physics beyond that in the minimal SU(5) model the proton lifetime is 8 × 10^30±2 years.     

Higgs boson searches at the Tevatron

This article reviews the Higgs searches at the Tevatron, as presented over the summer of 2012; both standard model (SM) and beyond the standard model (BSM) results are discussed as detailed (arXiv: 1207.0449; Phys. Rev. Lett., 2012, 109: 071804; Phys. Rev. D, 2012, 85: 032005). We discuss the combination of searches by the CDF and D0 Collaborations for the standard model Higgs boson in the mass range 100–200 GeV/c ² produced in the the gg → H, WH, ZH, t{ie27-1}H, and vector boson fusion production modes, and decaying in the H → b{ie27-2}, H → W ⁺ W ^?, H → ZZ, H → τ ⁺ τ ^?, and H → γγ modes. The data, collected at the Fermilab Tevatron collider in p{ie27-3} collisions at {ie27-4} TeV, correspond to integrated luminosities of up to 10 fb^?1. In the absence of signal, we expect to exclude the regions 100<m _H < 120 GeV/c ² and 139<m _H < 184 GeV/c ². We exclude, at the 95% C.L., two regions: 100<m _H < 103 GeV/c ², and 147<m _H < 180 GeV/c ². We observe a significant excess of events in the mass range between 115 and 140 GeV/c ². The local significance corresponds to 3.0 standard deviations at m _H = 120 GeV/c ²; the global significance (incorporating the look-elsewhere effect) for such an excess anywhere in the full mass range investigated is approximately 2.5 standard deviations. Furthermore, we separately combine searches for H → b{ie27-5}, H → W+W ^? and H → γγ. We find that the excess is concentrated in the H → b{ie27-6} channel, appearing in the searches over a broad range of m _H ; the maximum local significance of 3.3 standard deviations corresponds to a global significance of approximately 3.1 standard deviations. The observed signal strengths in all channels are consistent with the expectation for a standard model Higgs boson at m _H = 125 GeV/c ². The production of neutral Higgs bosons in association with b-quarks can be significantly enhanced in various beyond the standard model scenarios, including Supersymmetry. The recent combination of such searches from the two collaborations is discussed.     

Neutral currents within beyond the standard model

We present new, model-independent analyses of the observables in low-energy neutral-current experiments in the neutrino-hadron, neutrino-electron, electron/muon-hadron and electron- muon/tau sectors. We combine them with the latest experimental measurements of the W and Z masses to make global fits in the context of the standard model and of superstring-inspired models. We find in the standard model that sin ²θ _w = 0.228 ± 0.004 if ϱ is fixed to be 1, whilst a two parameter fit yields sin ²θ _w = 0.229 ± 0.006 and ϱ = 1.001 ± 0.007. This new value of sin ²θ _w for ϱ = 1 lies uncomfortably outside the predicted region of the minimal SU(5) model, but is consistent with supersymmetric SU(5) models. In the minimal standard model with ϱ = 1 and equal Higgs and Z masses we find that m_t<168 GeV at the 90% confidence level. We establish lower bounds on the masses of additional neutral gauge bosons Z′ in three superstring-inspired models and upper limits on their mixing with the standard model Z ⁰. In particular, we find that m_Z′129 GeV at the 90% confidence level in a minimal rank-5 superstring-inspired model with canonical Higgs structure.     

Composite fermions,trios, and quartets in the Fermi-Bose mixture of neutral particles

We consider the model of a Fermi-Bose mixture with strong hard-core repulsion between particles of the same sort and attraction between particles of different sorts. In this case, in addition to the standard anomalous averages of the type 〈b〉, 〈bb〉, and 〈cc〉, pairing between fermions and bosons of the type 〈bc〉 is possible. This pairing corresponds to creation of composite fermions in the system. At low temperatures and equal densities of fermions and bosons, composite fermions are further paired into quartets. At higher temperatures, trios consisting of composite fermions and elementary bosons are also present in the system. Our investigations are important in connection with the recent observation of weakly bound dimers in magnetic and optical dipole traps at ultralow temperatures and with the observation of collapse of a Fermi gas in an attractive Fermi-Bose mixture of neutral particles.     

Can the superstring inspire the standard model?

We discuss general features of models in which the E₈ × E′₈ heterotic superstring is compactified on a specific Calabi-Yau manifold. The gauge group of rank-6 in four dimensions is supposed to be broken down at an intermediate scale m_I to the standard model group SU(3)_C × SU(2)_L × U(1)_Y, as a result of two neutral scalar fields acquiring large vacuum expectations (vev's) in one of many flat directions of the effective potential. We find that it is difficult to generate such an intermediate scale by radiative symmetry breaking, whilst such models have prima facie problems with baryon decay mediated by massive particles and with non-perturbative behaviour of the gauge couplings, unless m_I ≳ 10¹⁶ GeV. Rapid baryon decay mediated by light particles, large neutrino masses, other Δ L ≠ 0 processes and flavour-changing neutral currents are generic features of these models. We illustrate these observations with explicit calculations in a number of different models given by vev's in different flat directions.     

Induced fermionic interactions in theories with general nonlinearly realized SSB

We consider a model with nonlinear SSB, which can be considered as a limiting case of the electroweak SM whenM _H→∞. It possesses a chain of hidden local gauge symmetries yielding a series of heavy gauge boson triplets, which can be interpreted as effects of the strong self-interactions of the scalar sector and are able to infect via mixing low energy quantities. The theory is non-renormalizable and, therefore, new Lagrangian terms are induced at each loop order. We investigate these quantum-induced interactions (which are of non-standard type) of fermions and vector bosons, and show that they can be expressed in additional Lagrangian terms which obey the symmetry of the original theory.     

Study of charged and neutral minimal supersymmetric standard model Higgs boson decays and measurement of tan <Emphasis Type="Italic">β</Emphasis> at the compact linear collider

The minimal supersymmetric extension of the standard model (MSSM) predicts the existence of new charged and neutral Higgs bosons. The pair creation of these new particles at the multi-TeV e ⁺ e ⁻ compact linear collider (CLIC), followed by decays into standard model particles, were simulated along with the corresponding background. High-energy beam-beam effects such as ISR, beamstrahlung and hadronic background were included. We have investigated the possibility of using the ratio between the number of events found in various decay channels to determine the MSSM parameter tan β and we have derived the corresponding statistical error from the uncertainties on the measured cross-sections and Higgs boson masses.      

Heavy SUSY Higgs bosons at e + e − linear colliders

The production mechanisms and decay modes of the heavy neutral and charged Higgs bosons in the Minimal Supersymmetric Standard Model are investigated at future e ⁺ e ^? colliders in the TeV energy regime. We generate supersymmetric particle spectra by requiring the MSSM Higgs potential to produce correct radiative electroweak symmetry breaking, and we assume a common scalar mass m₀, gaugino mass m_1/2 and trilinear coupling A, as well as gauge and Yukawa coupling unification at the Grand Unification scale. Particular emphasis is put on the low tan β solution in this scenario where decays of the Higgs bosons to Standard Model particles compete with decays to supersymmetric charginos/neutralinos as well as sfermions. In the high tan β case, the supersymmetric spectrum is either too heavy or the supersymmetric decay modes are suppressed, since the Higgs bosons decay almost exclusively into b and τ pairs. The main production mechanisms for the heavy Higgs particles are the associated AH production and H ⁺H^? pair production with cross sections of the order of a few fb.     

Charged and neutral minimal supersymmetric standard model Higgs boson decays and measurement of tan <Emphasis Type="Italic">β</Emphasis> at the compact linear collider

The minimal supersymmetric extension of the standard model (MSSM) predicts the existence of new charged and neutral Higgs bosons. The pair creation of these new particles at the multi-TeV e ⁺ e ⁻ compact linear collider (CLIC), followed by decays into standard model particles, were simulated along with the corresponding background. High-energy beam-beam effects such as ISR, beamstrahlung and hadronic background were included. We have investigated the possibility of using the ratio between the number of events found in various decay channels to determine the MSSM parameter tan β and we have derived the corresponding statistical error from the uncertainties on the measured cross-sections and Higgs boson masses.      

Higgs bosons in supersymmetric models (III). Decays into neutralinos and charginos

We give explicit formulae for the decays of the Higgs bosons of the minimal supersymmetric model to neutralinos and charginos. The important features of these decays are illustrated and their phenomenological implications discussed. Particular attention is given to the decays of heavy Higgs bosons (with masses larger than m_Z) which can only be observed at a future supercollider. When phase-space allowed, Higgs decays into neutralinos and charginos are at least as important as, and often dominate, other types of Higgs decay modes, such as WW, ZZ, and heavy quark (or lepton) pairs.     

New resonance-polariton Bose-quasiparticles enhances optical transmission into nanoholes in metal films

We argue the existence of fundamental particles in nature, neutral Light-Particles with spin 1, and rest mass m=1.8⋅¹⁰−4me, in addition to electrons, neutrons and protons. We call these particles Light Bosons because they create the electromagnetic field which represents Planck's gas of massless photons together with a gas of Light-Particles in the condensate. In this respect, the condensed Light-Particles, having no magnetic field, represent the constant electric field. In this context, we predict an existence of polariton-plasmon Bose-quasiparticles with effective masses ml≈¹⁰−6me and mr=0.5me, which are induced by interaction of the plasmon field and the resonance Frölich-Schafroth charged bosons with electromagnetic wave in metal. Also, we prove that the enhancement optical transmission into nanoholes in metal films and Surface Enhanced Raman Spectroscopy are provided by a new resonance-polariton Bose-quasiparticles but not model of surface plasmon-polariton. In this Letter, the quantization Fresnel's equations is presented which confirms that Light-Particles in the condensate are concentrated near on the wall of grooves in metallic grating and, in turn, represent as the constant electric field which provides the launching of the surface Frölich-Schafroth bosons on the surface metal holes.     

Order αs corrections to intermediate boson masses

We present the order α_s corrections to the masses of the Z and W bosons in the standard model. For the low mass quarks u, d, c and s the corrections are small and positive. Due to the Coulomb singularity which appears in the vector boson self-energy graph with one gluon exchange, we find a negative contribution from the t, b doublets.