Search

We have analysed the observable consequences of the interactions of spin-1 resonances coupled to the invariant fermionic currents that arise in an $SO(5)$ Composite Higgs set-up. The phenomenology entailed by such interactions is thoroughly analysed by studying heavy vector resonances production and decay modes in the viable resonance mass range. Additionally, the production of double and single-composite fermion final states has been scanned along the fermion mass scale. Such production is mediated by the SM gauge and Higgs interactions, and also by charged and neutral vector resonances. The coupling between the new fermions and vector resonances induces a sizeable effect in the production rates. We use the recent 13 TeV LHC searches for vector-like quarks to constrain our parameter space. Specifically, we explore the allowed regions by analysing the decays of a heavy vector-like quark in the $Wb$-channel. We conclude that generically the impact of the couplings between the spin-1 and spin-1/2 resonances will substantially reduce the permitted regions, leading us to test the sensitivity of the parametric dependence in the light of exotic matter interactions., Comment: 30 pages, 40 figures, references added and some sections shortened. arXiv admin note: text overlap with arXiv:1405.1617, arXiv:1211.5663 by other authors. References and footnotes added

Effects of Kaluza-Klein excited neutral vector bosons ($Z'$ bosons) in the gauge-Higgs unification on $e^+e^- \to \bar{q}q, \ell^+\ell^-$ cross sections are studied, particularly in future $e^+ e^-$ collider experiments with polarized beams. Significant deviations in the energy and polarization dependence in $\sigma(\mu^+\mu^-)$, the lepton forward-backward asymmetry, $R_b(\mu) \equiv \sigma(\bar{b}b)/\sigma(\mu^+\mu^-)$ and the left-right asymmetry from the standard model are predicted., Comment: 16 pages, 5 figures, 7 tables (v3) numerical evaluations renewed, comments and references added, 4 tables added

We calculate the complete O ( α 2 ) initial state radiation corrections to e + e − annihilation into a neutral vector boson in a direct analytic computation without any approximation. The corrections are represented in terms of iterated incomplete (elliptic) integrals over alphabets of square-root valued letters. Performing the limit s ≫ m e 2 , we find discrepancies with the earlier results of Ref. [1] and confirm results obtained in Ref. [2] where the effective method of massive operator matrix elements has been used, which works for all but the power corrections in m e 2 / s . In this way, we also confirm the validity of the factorization of massive partons in the Drell-Yan process to O ( α 2 ) . We add non–logarithmic terms at O ( α 2 ) which have not been considered in previous calculations. The final results in the limit s ≫ m e 2 can be given in terms of Nielsen integrals.

We have searched for neutrinoless τ lepton decays into lhh or l V0, where l stands for an electron or muon, h for a charged light hadron, π or K, and V0 for a neutral vector meson, ρ0, K* (892)0 and φ{symbol}, using a 158 fb-1 data sample collected with the Belle detector at the KEKB e+ e- collider. Since the number of events observed are consistent with the expected background, we set upper limits on the branching fractions in the range of (1.6 - 8.0) × 10-7 for various decay modes at the 90% confidence level. © 2006 Elsevier B.V. All rights reserved.

We assume the latest experimental determination of the weak charge of atomic cesium and analyze its implications for possible new physics. We notice that the data would imply positive upper and lower bounds on the new physics contribution to the weak charge, $\delta_NQ_W$. The required new physics should be of a type not severely constrained by the high energy precision data. A simplest possibility would be new neutral vector bosons almost un-mixed to the $Z$ and with sizeable couplings to fermions. The lower positive bound would however forbid zero or negative $\delta_NQ_W$ and exclude not only the standard model but also models with sequential $Z^\prime$, in particular simple-minded towers of $Z$-like excitations from extra-dimensions. The bound would also imply an upper limit on the $Z^\prime$ mass within the models allowed. Conclusions are also derived for models of four-fermion contact interactions., Comment: 11 pages, Latex, 1 PS figure, final version for Physics Letters

Strong solvability in Sobolev spaces W 2, p (Ω) is proved for the regular oblique derivative problem for second order uniformly elliptic operators with VMO-principal coefficients. The results are applied to the study of degenerate (tangential) oblique derivative problem in the case of neutral vector field on the boundary.

Beam polarization would allow the measurement of spin-dependent observable quantities at LHC and SSC. Within this context we complete some previous analysis on the identification of new neutral gauge bosons by extending to some ingenious but more exotic models recently discussed in the literature. Comparison with some alternative models of composite origin is also performed.

The production of neutral vector bosons, Z0 and γ, in association with top-antitop pairs at LHC and SSC is studied. These reactions could provide direct information on the electroweak couplings of the top. Their relevance as a background for vector boson pair production is discussed.

Extensions of the standard model with extra neutral vector bosons predict additional fermions. In the minimal case, where the extended gauge group is contained in the unified group SO(10), one has one right-handed neutrino for each quark-lepton generation. For this theory we systematically study the effects of both, the mixing of neutral vector bosons and the neutrino mixing, on a variety of observables used for precision tests of the electroweak theory. In most quantities the effects of neutrino and vector boson mixing tend to compensate each other. In particular the shift in the invisible width of the Z boson may be positive or negative. The most stringent bounds follow from tests for universality of the charged current. A comparable sensitivity could be attained from a measurement of the left-right asymmetry and forward-backward asymmetries at the Z pole. We emphasize the importance of measuring τ decays with improved accuracy.

Extensions of the standard model with extra neutral vector bosons predict additional fermions whose allowed masses are constrained by the masses of the new vector bosons. For the minimal case with one extra Z′ boson and an extended gauge group contained in the unified group SO(10), we derive upper and lower bounds on the masses of heavy Majorana neutrinos. We also discuss implications for the standard model Higgs boson.

The neutral ϱ-meson propagator is computed at finite temperature using standard π-ρ dynamics. The vector dominance model states that the hadronic electromagnetic current operator is proportional to a linear combination of the neutral vector meson field operators. Neglecting the φ-ω complex, this should give a good account of the rate of lepton pair emission from a hot pion gas. The mass and width of both transverse and longitudinal ϱ-mesons increase with temperature, but temperature effects are still relatively small up to T = 150 MeV. If substantial shifts in these quantities were to be seen experimentally, it would seem to require other new physics like chiral symmetry restoration or deconfinement. The results obtained here may be viewed as generalizing the Gounaris-Sakurai formula to finite temperature.

We compute the decay widths of the radiative modes h0(H0, δL0r) → γγ, γZ and Z′→ γh0(H0, δL0r), where h0, H0and δL0r are the light neutral Higgs scalars of left-right symmetric (LR) models with a minimal Higgs potential. We use a nonlinear R-gauge to compute these one-loop induced decays. We find that only the decay modes which involve the scalar h0, the LR analogue of the standard model Higgs boson, are not suppressed by LR mixing angles.

Recent experimental data have significantly improved the overall consistency of ft values for superallowed 0+ → 0+ nuclear β-decays. All relevant data are collated in this paper and theoretical electromagnetic corrections applied. The resulting corrected F t values are constant to within two parts in 3000. This constitutes an exacting experimental confirmation of the CVC hypothesis. Statistical tests applied to the data gave no positive indication of any inadequacies in the theoretical corrections. These tests also set a new limit for the Fierz interference constant, bF ≦ 0.006, which is an order of magnitude smaller than previous determinations. The value of the vector coupling constant of nuclear β-decay, established from these data, is compared with muon and hyperon β-decays as a test of Cabibbo universality. It is shown that universality is achieved under specific conditions on the mass of the neutral vector boson.

Cross sections for Drell-Yan production of dimuons via Z0 and single muons via W± in pp , p p , π + p and π − p reactions are computed. Asymptotically a linear rise with log s is predicted. Should the order of magnitude of the estimates of the pion's quark distribution be confirmed, the π−p reaction may be of special interest in the experimental search for the neutral vector boson.

We discuss the possibility of observing weak neutral currents in the inclusive production of ordinary lepton pairs in high-energy proton-proton collisions. Our signatures of interest are the charge asymmetry 〈El+ − El−〉 and the polarization of the leptons. The weak interaction is considered to be mediated by a neutral vector boson and the calculations are done in the parton model. This model is also used to estimate the asymmetry background due to two-photon exchange. To obtain numerical results we use weak couplings suggested by the Weinberg theory.

Decays of a neutral Higgs scalar (H) into a neutral vector meson (V) and a photon ( γ ) are discussed. The width for H → V + γ is related to the leptonic width V → l + l − . The rate for H → V + V is also estimated using a Phenomenological quark interaction with vector mesons supplemented by form factors.

A general procedure is presented for recasting a set of Feynman rules of vector field theories into another set by use of functional integration techniques. This procedure, when applied to the neutral vector meson coupled to a conserved current, allows us to recast conventional Feynman rules into the ones of arbitrary (even non-linear) gauges, and reveals the fact that this theory is manifestly renormalizable in any covariant (nonlinear) gauges. Likewise, the massive Yang-Mills theory can be converted into the one with a generalized Feynman gauge-like constraint, and it is then shown that the massive Yang-Mills field is not renormalizable.

An analytical approach is developed to the calculation of the hard bremsstrahlung corrections for the process e+e− → μ+μ− in the context of the standard SU(2) × U(1) model for unified weak and e.m. interactions. Numerical results are shown for different values of the c.m. energy and scattering angle. They are strongly dependent on the experimental setup and indicate that hard effects become extremely important in the region of the neutral vector boson peak. Total corrections to the process are also analyzed. Finally hard photon corrections are reexamined for pure QED giving agreement with previous numerical calculations.

As signals of phase transitions in ultra-relativistic nuclear collisions, observations of mass shifts of J/ Ψ , ν c 1 ν ′ and ν by lepton pair and photon pair are discussed.

We present the calculation of one-loop corrections to the decay width of the neutral vector boson into leptons, in the framework of the standard model of the electromagnetic and weak interactions.

We illustrate a strategy to identify the effect of a possible extra neutral vector boson of several different theoretical origins (extended gauge groups, composite models, models with a strongly interacting Higgs sector), assuming that only precision experiments without polarized e + e − beams were available. We show that it might be relatively easy to discover evidence of genuine New Physics (i.e., effects not depending on the value of the top mass, or on the existence of new families...) if a certain set of observables, including the final τ polarization in unpolarized e + e − annihilation, were measured. The region of possible confusion between different theoretical models would be, though, sensibly larger than in the case in which e + e − polarization were available.

We study the bremsstrahlung production of the ϱ meson in the reaction e+e− → e+e−ϱ (→ e+e−π+π−). This reaction gives a C = −1 background which complicates the study of C = +1 two-photon processes at the new colliding-beam facilities. The cross section for the reaction rises from approximately 0.3 nb to 0.7 nb as the beam energy increases from 2 GeV to 15 GeV. From a study of the distributions of the final leptons and pions, we find a suitable choice of cuts which will reduce the event rate down to a small fraction of R. It is not possible to attribute the three-prong events seen at DELCO and PLUTO to this particular production mechanism.

A study is made to determine if the results of the nonrelativistic quark model can be reproduced by a fully relativistic model of deeply bound spin - 1 2 quarks. It is found that the relativistic model does not reproduce the nonrelativistic results, even when the quarks have nonrelativistic momenta. However, the model is rather successful in accounting for the known properties of mesons. Numerical solutions to the Bethe-Salpeter equation are obtained for pseudoscalar and vector bound states of equal mass quark-antiquark pairs, with either a scalar, pseudoscalar, or neutral vector exchange interaction. The interaction function corresponds to single particle exchange, with the addition of either one or two regulating terms. It is found that the second regulator allows the internal quark momentum to be nonrelativistic, but that the spinor structure of the wave function remains highly relativistic. Only the scalar interaction can account for the observed spectrum of states. The pseudoscalar interaction yields a vector state of lower mass than the pseudoscalar state, and the vector interaction leads to a vector state which lies approximately one quark mass above the pseudoscalar state. The λ quark is taken as slightly heavier than the p and n, and the perturbation treatment of the mass difference leads to a quadratic mass formula. The decay amplitudes for π, K → μν are calculated, and it is found, independent of parameters, that ƒ π ≈ ƒ K for either a scalar or vector interaction, in agreement with experiment and in contrast with the nonrelativistic model. The amplitudes for ϱo, ω, φ → e+e−, μ+μ− are also calculated, but in this case the ratios (again parameter independent) are in minor discrepancy with experiment. The question of the additivity of quark amplitudes is examined by calculating (with significant restrictions) the magnetic moments of the vector mesons and the amplitudes for magnetic transitions such as ω → πoγ. The magnetic moments of the vector mesons have the same (trivial) ratios to each other as in the nonrelativistic model, but they are strongly enhanced over the sum of the quark magnetic moments. The amplitude for magnetic transitions, however, is related to the quark magnetic moments in approximately the same ratio as in the nonrelativistic model. The model is also used to obtain parameter dependent predictions for the masses and decay amplitudes. These predictions are not experimentally correct, but are generally well within an order of magnitude for a wide range of the parameters. The most significant defect discovered of the model is the presence of ghost states (the daughters of the vector mesons, with JPC = 0+−) with masses of about 2 BeV.

We examine two-body pp annihilition at high energy and angle in a model field theory of a fermion and massive neutral vector meson. In weak coupling approximation the amplitude eikonalises with “soft” photons dressing the hard nucleon exchange Born term, leading to an exponential fall off in ln2s.

A class of strong interaction models in which the interactions between fractionally charged colored quarks are mediated by massive neutral vector gluons is considered. All the vector gluons acquire masses via the usual Higgs mechanism. The effective coupling constants g (gauge coupling) and h (quartic self-coupling) are supposed to approach a limit cycle in the limit of large space-like momenta. The large Q 2 behavior of the moments of the deep inelastic lepton-hadron structure functions is analysed using this hypothesis. It is shown that Bjorken scaling is violated by power terms of Q 2 multiplied by an oscillating function of Q 2 .

Consider a massive neutral vector mesonUμ interacting with other spin zero or spin12 particle φ. If the interaction Lagrangian consists of two partsL1(φ, U) + L2(φ)whereL1(φ, U) is (together with kinetic energy terms) invariant for the gauge transformations φ = exp ( ι Q Λ ) φ ′ , U µ = A µ − 1 κ ∂ Λ ∂ x µ and L2 is not gauge-invariant, it shown that the conventionalS-matrix T expi(∫L1(φ, U) + + L2(φ)) identically equalsT expi(∫L1(φ, A)+L2(φ′)). Since allΛ-dependent effects are now contained and displayed explicitly inL2(φ′) it is possible to give a precise discussion of the renormalization problem for vector meson theories. This is because the suspected non-renormalizability of these theories arises from∂Λ/∂xμ terms in the conventionalS-matrix.

The (e + e − ) decay rates of vector mesons have been measured using spark chambers and Cerenkov gamma-spectrometers.

We show that in any theory in which weak leptonic processes are induced by an arbitrary number of massive charged and neutral vector intermediate bososns, with couplings satisfying μ-e symmetry, the cross-sections for the reactions ν e e →ν e e , ν e e → ν e e ,ν μ e →ν μ e and ν μ e → ν μ e , expressed in units of G 2 s 2π , satisfy the constraints (i) 1 3 ⩽ σ( ν e e )/σ(ν e e ), σ( ν μ e )/σ(ν μ e ) ⩽ 3 , (ii) σ( ν e e ) − σ( ν μ e )=( 1 3 [σ(ν e e ) − σ(ν μ e )] , (iii) [σ(ν e e ) − ( 1 3 )σ( ν e e )] 1 2 − [σ(ν μ e ) − ( 1 3 )σ( ν μ e )] 1 2 = 4 3 . These relations remain valid in gauge theories containing scalar bosons, as long as the coupling of such bosons to the leptons is proportional to the lepton mass.

We point out and discuss the possibility that the UA1 and UA2 collaborations at the p p collider at CERN have unearthed two distinct neutral vector bosons with masses of 91 GeV and 96 GeV.

We give predictions for the electronic widths of neutral vector mesons made from heavy quarks. Relying principally on dispersion relations and asymptotic freedom of QCD, these results are quite model-independent. Photonic and total hadronic widths of C -even mesons are also discussed.

An exact calculation of the lowest-order QED corrections to leptonic decay rates of the neutral vector boson is presented and the origin of a discrepancy between two recent results is explained.

The existence of at least one extra neutral vector boson provides a one-loop (SUSY) correction to the W± → l±νe decay which violates CP invariance. The existing bounds for the slepton masses allow the corresponding asymmetry to be as large as 10−3.

Assuming that a non-empty space is curved, at least in principle, it is suggested that a photon, in such a space, may be treated as a neutral vector meson.

We comment on apparent disagreements in calculations of the inelastic e − p structure functions in the neutral vector gluon model (also known as massive QED).

It has been shown in the first non-trivial approximation that the Langrangian field theory of spin 1/2 fermions and neutral vector mesons interacting through a conserved current has the apparently miraculous property that the "elementary" spinor particle lies on a Regge trajectory. We would like to point out here that this feature of the spinor-vector field theory, if it is in fact exactly true, also has interesting implications when phrased in terms of "S-matrix theory", in which it is assumed that there are no elementary objects and that all particles are created by a "bootstrap mechanism".

The possibility is considered of the production of a neutral vector meson pair via one virtual photon in electron-positron annihilation.