The propagator of a gauge boson, like the massless photon or the massive vector bosons $W^\pm$ and $Z$ of the electroweak theory, can be derived in two different ways, namely via Green's functions (semi-classical approach) or via the vacuum expectation value of the time-ordered product of the field operators (field theoretical approach). Comparing the semi-classical with the field theoretical approach, the central tensorial object can be defined as the gauge boson projector, directly related to the completeness relation for the complete set of polarisation four-vectors. In this paper we explain the relation for this projector to different cases of the $R_ξ$ gauge and explain why the unitary gauge is the default gauge for massive gauge bosons.
The quantisation of gauge invariant systems usually proceeds through some gauge fixing procedure of one type or another. Typically for most cases, such gauge fixings are plagued by Gribov ambiguities, while it is only for an admissible gauge fixing that the correct dynamical description of the system is represented, especially with regards to non perturbative phenomena. However, any gauge fixing procedure whatsoever may be avoided altogether, by using rather a recently proposed new approach based on the projection operator onto physical gauge invariant states only, which is necessarily free on…
The recently proposed physical projector approach to the quantisation of gauge invariant systems is applied to the U(1) Chern-Simons theory in 2+1 dimensions as one of the simplest examples of a topological quantum field theory. The physical projector is explicitely demonstrated to be capable of effecting the required projection from the initially infinite number of degrees of freedom to the finite set of gauge invariant physical states whose properties are determined by the topology of the underlying manifold.
We discuss the specificity of the interactions of the electroweak gauge boson excitations in models with warped extra dimensions. In particular, we show that the couplings of the gauge boson excitations $W^{\prime}$, $Z^{\prime}$, and $γ^\prime$ to the SM gauge bosons treated as the zero modes of the 5D gauge fields are either exactly equal to zero or very much suppressed. In the former case, the three-particle and four-particle interaction Lagrangians of the SM gauge bosons and their lowest excitations are found explicitly. Meanwhile, the couplings of $W^{\prime}$, $Z^{\prime}$, and $γ^\prime…
A simple, anomaly-free chiral gauge theory can be perturbatively quantised and renormalised in such a way as to generate fermion and gauge boson masses. This development exploits certain freedoms inherent in choosing the unperturbed Lagrangian and in the renormalisation procedure. Apart from its intrinsic interest, such a mechanism might be employed in electroweak gauge theory to generate fermion and gauge boson masses without a Higgs sector.
In the dynamical gauge-Higgs unification, it is shown that the mass of the Higgs boson (4D scalar field) in U(1) gauge theory in $M^4 \times T^n$ ($n=1,2,3,...$) is finite to all order in perturbation theory as a consequence of the large gauge invariance. It is conjectured that the Higgs boson mass is finite in non-Abelian gauge theory in $M^4 \times S^1$, $M^4 \times (S^1/Z_2)$ and the Randall-Sundrum warped spacetime to all order in the rearranged perturbation theory where the large gauge invariance is maintained.
In this work we adopt the point of view that the equations of motion satisfied by a field are just a consequence of the representation space which the field belongs to, and the discrete symmetries we impose on it. We illustrate this view point by rederiving Dirac and Proca equations as projectors over the subspaces with well defined parity of (1/2,0)+(0,1/2) and (1/2,0)X(0,1/2) representations respectively. We formulate the equation of motion corresponding to the identification of elementary systems with states in the invariant subspaces of the squared Pauli-Lubanski operator and couple minima…
We calculated the leading-order cross section for the helicity two tensor gauge bosons production in fermion pair annihilation process. We compare this cross section with a similar annihilation processes in QED with two photons in the final state and with two gluons in QCD.
A gauge field model, which simultaneously has strict local gauge symmetry and massive gauge bosons, is discussed in this paper. The model has SU(N) gauge symmetry. In the limit $α\longrightarrow 0$, the gauge field model discussed in this paper will return to Yang-Mills gauge field model. The important meaning of this model is that, without Higgs mechanism, gauge bosons can also obtain masses. This theory can also explain some other unknown phenomenum.
We study the production of massive gauge bosons during inflation from the axion-type coupling to the inflaton and the corresponding oscillatory features in the primordial non-Gaussianity. In a window in which both the gauge boson mass and the chemical potential are large, the signal is potentially reachable by near-future large scale structure probes. This scenario covers a new region in oscillation frequency which is not populated by previously known cosmological collider models. We also demonstrate how to properly include the exponential factor and discuss the subtleties in obtaining power d…
We analyze the potential of the CERN Large Hadron Collider (LHC) to study anomalous trilinear vector-boson interactions W^+ W^- γand W^+ W^- Z through the single production of electroweak gauge bosons via the weak boson fusion processes q q -> q q W (-> \ell^\pm ν) and q q -> q q Z(-> \ell^+ \ell^-) with \ell = e or μ. After a careful study of the standard model backgrounds, we show that the single production of electroweak bosons at the LHC can provide stringent tests on deviations of these vertices from the standard model prediction. In particular, we show that single gauge boson production …
There has been rapidly growing interest in the past decade in a new gauge boson which is considerably lighter than the standard model Z boson. A well-known example of this kind is the so-called dark photon, and it is actively searched for in various experiments nowadays. It would be puzzling to have a new gauge boson which is neither massless nor electroweak scale, but possesses a rather small yet nonzero mass. We present a mechanism that can provide a light gauge boson as a result of a mass matrix diagonalization.
If no light Higgs boson exist, the interaction among the gauge bosons becomes strong at high energies (~1TeV). The effects of strong electroweak symmetry breaking (SEWSB) could manifest themselves as anomalous couplings before they give rise to new physical states, thus measurement of all couplings and their possible deviation from Standard Model (SM) values could give valuable information for understanding the true nature of symmetry breaking sector. Here we present a detailed study of the measurement of quartic gauge couplings in weak boson scattering processes and a possibility for same mea…
It is proposed to replace the Higgs boson of the standard model by a Lorentz- and gauge-invariant combination of SU(2) gauge bosons. A pair of Higgs bosons is identified with pairs of gauge bosons by setting their mass Lagrangians equal to each other. That immediately determines the mass of the composite Higgs boson. It becomes simply half of the vacuum expectation value of the standard Higgs boson, which matches the observed mass with tree-level accuracy (2%). The two parameters of the standard Higgs potential are replaced by five one-loop self-interactions of the SU(2) gauge bosons, derived …
It is shown how the S-matrix pinch technique may be extended to the cases of external scalar and gauge boson fields. Using this extension, the universality of the pinch technique gauge-independent one-loop gauge boson self-energy in a general unbroken SU($N$) gauge theory is demonstrated explicitly.
We summarize the results of the New Gauge Boson Subgroup on the physics of extended gauge sectors at future colliders as presented at the 1996 Snowmass workshop. We discuss the direct and indirect search reaches for new gauge bosons at both hadron and lepton colliders as well as the ability of such machines to extract detailed information on the couplings of these particles to the fermions and gauge bosons of the Standard Model. [To appear in the Proceedings of the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics-Snowmass96, Snowmass, CO, 25 June-12 July, 1996.]
It is investigated whether observations of family gauge bosons by terrestrial experiments are possible or not. We propose an extended version of Sumino's family gauge boson model based on U(3) family symmetry. Then, we can expect the lowest family gauge boson $A_1^1$ with $M \sim 4.3$ TeV.
We consider a generic framework where the Standard Model (SM) coexists with a hidden sector endowed with some additional gauge symmetry. When this symmetry is broken by a scalar field charged under the hidden gauge group, the corresponding scalar boson generally mixes with the SM Higgs boson. In addition, massive hidden gauge bosons emerge and via the mixing, the observed Higgs-like mass eigenstate is the only known particle that couples to these hidden gauge bosons directly. We study the LHC monojet signatures of this scenario and the corresponding constraints on the gauge coupling of the hid…
The study of gauge bosons is interesting in two respects. The properties of gauge bosons are modified by higher order effects that are sensitive to mass scales not directly accessible to experiment. On the other hand interactions amongst gauge bosons are sensitive to the symmetry structure of the theory where especially the interactions involving longitudinally polarised bosons teach us about the mechanism of electroweak symmetry breaking. This article explains how far a linear collider can increase our knowledge about the properties of and the interactions amongst gauge bosons.
We derive analytic formulas for the radiatively corrected mass of the scalar Higgs boson in the framework of the minimal supersymmetric standard model (MSSM). Since the scalar-top-quark mass in our analysis include terms proportional to the gauge couplings in the 1-loop effective potential, the radiatively corrected mass of the scalar Higgs boson partially contains the gauge boson contributions. At the 1-loop level, the upper bound on the lighter scalar Higgs boson mass can be increased about 20 GeV in favor of the partial contributions of the gauge bosons. Thus the improved absolute upper bou…
We examine trilinear gauge boson couplings (TGCs) in the context of the $SU(3)_W\otimes U(1)'$ gauge-Higgs unification scenario. The TGCs play important roles in the probes of the physics beyond the standard model, since they are highly restricted by the experiments. We discuss mass spectrum of the neutral gauge boson with brane-localized mass terms carefully and find that the TGCs and $ρ$ parameter may deviate from standard model predictions. Finally we put a constraint from these observables and discuss the possible parameter space.
A new mechanism giving the massive gauge bosons in Yang-Mills theory is proposed in this letter. The masses of intermediate vector bosons can be automatically given without introducing Higgs scalar boson. Furthermore the relation between the masses of bosons and the fermion mass matrix is obtained. It is discussed that the theory should be renormalizable.
If the electroweak symmetry breaking sector contains colored particles weighing a few hundred GeV, then they will be copiously produced at a hadron supercollider. Colored technipions can rescatter into pairs of gauge bosons. As proposed by Bagger, Dawson, and Valencia, this leads to gauge boson pair rates far larger than in the standard model. In this note we reconsider this mechanism, and illustrate it in a model in which the rates can be reliably calculated. The observation of both an enhanced rate of gauge-boson-pair events and colored particles would be a signal that the colored particles …
The values of color and anticolor charges are proposed. The structure of gluons is predicted relative to their color and anticolor charges. It is shown that the gauge bosons of lower order theories can be used as it is for higher order theories. Various mass relations between the gauge bosons are also given.
We consider the scattering amplitudes of the form V_1 V_2 -> V_3 V_4, where V_i=γ, Z, W or g(=gluon) are the Standard Model gauge bosons, due to graviton exchange in Kaluza-Klein theories with large extra dimensions. This leads to a number of experimentally viable signatures at high energy leptonic and hadronic colliders. We discuss the observability or future limits on the scale of the gravitational interactions (m_D), that may be obtained at an e+e- Next Linear Collider (NLC) and at the LHC, by studying some of these type of gauge boson scattering processes. We find that the attainable limit…
Extra neutral gauge bosons and Higgs bosons in an effective low-energy $SU(2)_L \times SU(2)_I \times U(1)_Y \times U(1)_{Y^{\prime}}$ model, which is a subgroup of $E_6$, are studied. $SU(2)_I$ is a subgroup of $SU(3)_R$ and commutes with the electric charge operator, so the three corresponding gauge bosons are neutral. Electroweak precision experiments are used to put constraints on masses of the extra neutral gauge bosons and on the mixings between them and the ordinary Z boson, including constraints arising from a proposed measurment of the weak charge of the proton at Jefferson Lab. Bound…
Inspired by the Goldstone equivalence gauge, we study the thermal corrections to an originally massive vector boson by checking the poles and branch cuts. We find that part of the Goldstone boson is spewed out from the longitudinal polarization, becoming a branch cut which can be approximated by the "quasi-poles" in the thermal environment. In this case, physical Goldstone boson somehow partly recovers. We also show the Feynmann rules for the "external legs" of these vector boson as well as the recovered Goldstone boson, expecting to simplify the vector boson participated process calculations …
This work explores the possibility of obtaining a mass gap in Yang-Mills theories via the intrinsic gauge bosons, without invoking a separate Higgs boson or fermion-antifermion pairs. Instead, pairs of gauge bosons in the spin and isospin singlet state form a pair of composite Higgs bosons which can be viewed as the simplest possible glueball of Yang-Mills gauge theories. Quadratic and quartic gauge boson self-interactions form a potential that leads to a finite expectation value of the gauge boson amplitude. Transverse polarization ensures Lorentz invariance of the vacuum after averaging over…
We construct a toy model for weak interaction based on the assumption that gauge bosons form condensates. We then discuss the model predictions calculated from the effective Feynman rules which are derived through computing the effective action.
With the high energy and luminosity, the planned ILC has the considerable capability to probe the new heavy particles predicted by the new physics models. In this paper, we study the potential to discover the lightest new gauge boson $B_{H}$ of the littlest Higgs model via the processes $e^+e^- \to γ(Z)B_H$ at the ILC. The results show that the production rates of these two processes are large enough to detect $B_H$ in a wide range of the parameter space, specially for the process $e^+e^- \to γB_H$. Furthermore, there exist some decay modes for $B_H$ which can provide the typical signal and cl…
There is a growing interest for the search of new light gauge bosons. The small mass of a new boson can turn various kinds of low-energy experiments to a new discovery machine, depending on their couplings to the standard model particles. It is important to understand the properties of each type of gauge boson and their current constraints for a given mass. While the dark photon (which couples to the electric charges) and the $U(1)_{B-L}$ gauge boson have been well studied in an extensive mass range, the $U(1)_L$ gauge boson has not been fully investigated yet. We consider the gauge boson of t…
We calculate the electromagnetic fermion form-factors induced by the anomalous gauge boson interactions contained in the operators ODW and ODB. Other results regarding anomalous triple gauge boson interactions are briefly overviewed. We study the interplay between vertex corrections and gauge boson self-energies extended to the longitudinal degrees of freedom. The physical couplings to an external electromagnetic field are then derived.
In this comment we present an analysis of electroweak neutral triple gauge boson couplings projected out of the gauge sector of the extended non-commutative standard model. A brief overview of the current experimental situation is given.
Intersecting D-brane theories motivate the existence of exotic U(1) gauge bosons that only interact with the Standard Model through kinetic mixing with hypercharge. We analyze an effective field theory description of this effect and describe the implications of these exotic gauge bosons on precision electroweak, LHC and ILC observables.
We study the effects of a set of dimension six flavor changing effective operators on several processes of production of top quarks at the LHC. Namely, top anti-top production and associated production of a top and a gauge or Higgs boson. Analytical expressions for the cross sections of these processes are derived and presented.
We study the mass ratio of W and Z bosons in an SU(5) gauge-Higgs unification model with the left-right symmetry remaining locally for boundary conditions and with no scalar fields except for the extra-dimensional component of gauge bosons. We find that there are a variety of boundary conditions to yield distinct values of the mass ratio.
A review is given of the theoretical expectations of the self couplings of gauge bosons and of the present experimental information on the couplings. The possibilities for future measurements are also discussed.
We study anomalous gauge-boson couplings induced by a locally SU(2) x U(1) invariant effective Lagrangian containing ten operators of dimension six built from the boson fields of the Standard Model (SM) before spontaneous symmetry breaking (SSB). After SSB some operators lead to new three- and four-gauge-boson interactions, some contribute to the diagonal and off-diagonal kinetic terms of the gauge bosons and to the mass terms of the W and Z bosons. This requires a renormalisation of the gauge-boson fields, which, in turn, modifies the charged- and neutral-current interactions, although none o…
We explore the physics of a new neutral gauge boson, ($Z^\prime$), coupling to only third-generation particles with a mass near the electroweak gauge boson mass poles. A $Z^\prime$ boson produced by top quarks and decaying to tau leptons is considered. With a simple search strategy inspired by existing analyses of the standard model gauge boson production in association with top quarks, we show that the Large Hadron Collider has good exclusionary power over the model parameter space of the $Z^\prime$ boson even at the advent of the high-luminosity era. It is shown that the $t\bar{t}Z^\prime$ p…
We apply ideas motivated by string theory to improve the calculational efficiency of one-loop weak interaction processes with massive external gauge bosons. In certain cases ``supersymmetry'' relations between diagrams with a fermion loop and with a gauge boson loop hold. This is explicitly illustrated for a particular one-loop standard model process with four-external gauge bosons. The supersymmetry relations can be used to provide further significant improvements in calculational efficiency.
Spectroscopy of family gauge bosons is investigated based on a U(3) family gauge boson model proposed by Sumino. In his model, the family gauge bosons are in mass eigenstates in a diagonal basis of the charged lepton mass matrix. Therefore, the family numbers are defined by $(e_1,e_2, e_3)=(e, μ, τ)$, while the assignment for quark sector are free. For possible family-number assignments $(q_1, q_2, q_3)$, under a constraint from $K^0$-$\bar{K}^0$ mixing, we investigate possibilities of new physics, e.g. production of the lightest family gauge boson at the LHC, $μ^- N \rightarrow e^- N$, rare $…
The emission of W and Z gauge boson is included in a traditional QCD + QED shower. The unitarity of the shower algorithm links the real radiation of the weak gauge bosons to the negative weak virtual corrections. The shower evolution process leads to a competition between QCD, QED and weak radiation, and allows for W and Z boson production inside jets. Various effects on LHC physics are studied, both at low and high transverse momenta, and effects at higher-energy hadron colliders are outlined.
When we try to consider family gauge bosons with a lower energy scale, a major obstacle is constraints from the observed $P^0$-$\bar{P}^0$ mixings ($P^0=K^0, D^0, B^0,B^0_s$). Against such a conventional view, we point out that, in a U(3) family gauge boson model, the bosons are harmless to any $P^0$-$\bar{P}^0$ mixings independently of explicit values of the family mixings, if masses $M_{ij}$ of the gauge bosons $A_i^{\ j}$ ($i,j$ are family indexes) satisfy a relation $2/M_{ij}^2=1/M_{ii}^2 +1/M_{jj}^2$. If such the case can be realized together with an inverted mass hierarchy $M_{33}^2 \ll …
We discuss the implications of the excesses in LHC Higgs boson searches on the gauge mediated supersymmetric standard model, for the mass range 120-140\,GeV. We find that a relatively heavy lightest Higgs boson mass in this range can be reconciled with light SUSY particles, $m_{\rm gluino}<2$\,TeV, if there are additional fields which couple directly to the Higgs boson. We also find that the mass of this extra matter can be predicted rather precisely in gauge mediation for a given Higgs boson and gluino mass.
We compare vector boson fusion and quark antiquark annihilation production of vector boson pairs at the LHC and include the effects of anomalous couplings. Results are given for confidence intervals for anomalous couplings at the LHC assuming that measurements will be in agreement with the standard model. We consider all couplings of the general triple vector boson vertex and their correlations. In addition we consider a gauge invariant dimension-six extension of the standard model. Analytical results for the cross sections for quark antiquark annihilation and vector boson fusion with anomalou…
We derive and solve the compositeness condition for the SU(N_c) gauge boson at the next-to-leading order in 1/N_f (N_f is the number of flavors) and the leading order in ln(Λ^2) (Λis the compositeness scale) to obtain an expression for the gauge coupling constant in terms of the compositeness scale. It turns out that the argument of gauge-boson compositeness (with a large Λ) is successful only when N_f/N_c>11/2, in which the asymptotic freedom fails.
We discuss the prospects for observing multiple weak gauge boson production at the SSC and LHC. We summarize conventional perturbative cross sections for processes involving 1-6 final state weak gauge bosons and compare them with more speculative scenarios including 1) a toy model of a strongly interacting Higgs sector patterned after hadronic multipion production and 2) the nonperturbative production of O(30) weak gauge bosons in a weakly coupled gauge sector.
We study the phenomenology of heavy gauge bosons at the LHC in a nonuniversal gauge interaction model with the separate electroweak SU(2) gauge group for the third generation. Considered are the Drell-Yan processes into the final states of dilepton, dijet, $τ^- τ^+$, and $t \bar{t}$ for $Z'$ boson and those of lepton-neutrino for $W'$ boson. We find that the present LHC data provides lower bounds on the masses of the heavy gauge bosons, $m_{Z'},~m_{W'} > 2$ TeV, more stringent than indirect bounds, when $\sin^2 ϕ> 0.15$ for the mixing angle of two SU(2) gauge groups.We also note that the study…
We study the phenomenology of the heavy charged gauge boson and obtain the lower bounds on its mass with the early LHC data at 7 TeV center-of-mass energy in the nonuniversal gauge interaction model, in which the electroweak SU(2) gauge group depends upon the fermion family. We found that the direct bound on the mass of the $W'$ boson is compatible to the indirect bound with only the early data of the LHC.
We generalize a previous construction of a fermiophobic model to the case of more than one extra $W$ and $Z$ gauge bosons. We focus in particular on the existence of screening configurations and their implication on the gauge boson mass spectrum. One of these configurations allows for the existence of a set of relatively light new gauge bosons, without violation of the quite restrictive bounds coming from the $ρ_{\rm NC}$ parameter. The links with Bess and degenerate Bess models are also discussed. Also the signal given here by this more traditional gauge extension of the SM could help to dise…
The relationship between MS and pole masses of the vector bosons Z and W is calculated at the two-loop level in the Standard Model. We only consider the purely bosonic contributions which represents a gauge invariant subclass of diagrams. All calculations were performed in the linear $R_ξ$ gauge with three arbitrary gauge parameters utilizing the method of asymptotic expansions. The results are presented in analytic form as series in the small parameters $\sin^2θ_W$ and mass ratio $m_Z^2/m_H^2$. As a byproduct we obtain the bosonic two-loop contributions to the renormalization of the weak mixi…
We have calculated the imaginary part of W and Z gauge boson's wave-function renormalization constants (wrc.) in the complex-pole mass renormalization scheme and made atonement for the paper hep-ph/0301090 where the imaginary part of gauge boson's wrc. has been ignored in the second renormalization scheme in section 4. But the conclusion of this section in hep-ph/0301090 doesn't change.
