Showing papers on "Gauge boson published in 1996"
TL;DR: This biennial Review summarizes much of particle physics, using data from previous editions.
12,798 citations
TL;DR: In this paper, the authors discuss non-trivial fixed points of the renormalization group with dual descriptions in N = 4 gauge theories in three dimensions and show that small E8 instantons in string theory are described by a local quantum field theory.
868 citations
TL;DR: The Coulomb branch of N = 2 supersymmetric gauge theories in four dimensions is described in general by an integrable Hamiltonian system in the holomorphic sense as mentioned in this paper.
795 citations
TL;DR: In this paper, Sen showed that the perturbations around the enhanced symmetry point were described by the mathematics of the solution of N = 2, d = 4 SU (2) gauge theory with four flavors.
336 citations
TL;DR: It is shown that a viable top quark mass can be achieved for the ratio of the VEVs of the bi–doublet tan β ≡ κ/κ ′ ≃ 1.3–4.3 T eV ; in this case one expects several intermediate and low–scale scalars in addition to the Standard Model Higgs boson.
Abstract: We study a left–right symmetric model which contains only elementary gauge boson and fermion fields and no scalars. The phenomenologically required symmetry breaking emerges dynamically leading to a composite Higgs sector with a renormalizable effective Lagrangian. We discuss the pattern of symmetry breaking and phenomenological consequences of this scenario. It is shown that a viable top quark mass can be achieved for the ratio of the VEVs of the bi–doublet tan β ≡ κ/κ ′ ≃ 1.3–4. For a theoretically plausible choice of the parameters the right–handed scale can be as low as ∼ 20 T eV ; in this case one expects several intermediate and low–scale scalars in addition to the Standard Model Higgs boson. These may lead to observable lepton flavour violation effects including � → eγ decay with the rate close to its present experimental upper bound.
255 citations
TL;DR: In this article, a supersymmetric SU(2) model with four doublet chiral superfields Qi and six singlet superfields Z ij = −Z is considered.
Abstract: We provide vector-like gauge theories which break supersymmetry dynamically. ⋆ JSPS Research Fellow. There is a piece of folklore which holds that vector-like gauge theories cannot break supersymmetry dynamically. In this letter, we point out remarkable exceptions to this piece of folklore. Let us consider a supersymmetric SU(2) gauge theory with four doublet chiral superfields Qi. We also introduce six singlet chiral superfields Z ij = −Z. Here i and j denote the flavor indices (i, j = 1, · · · , 4). The tree-level superpotential of our model is given by † Wtree = λ kl ijZ QkQl, (1) where λ ij denote generic coupling constants with λ kl ij = −λ kl ji = −λ lk ij . The pecuriarity of this superpotential resides in that it raises all the D-flat directions in the doublets Qi, which is a necessary condition for supersymmetry to break down. [1] Of course, supersymmetry remains unbroken perturbatively in this model. The exact effective superpotential of the model, which takes into account the full nonperturbative effects, may be written in terms of gauge-invariant low-energy degrees of freedom [2] Vij = −Vji ∼ QiQj (2) as follows: Weff = X(PfVij − Λ ) + λ ijZ Vkl, (3) where X is an additional chiral superfield, PfVij denotes the Pfaffian of the antisymmetric matrix Vij, and Λ is a dynamical scale of the SU(2) gauge interaction. [2,3] † This tree-level superpotential is natural since it possesses two global symmetries. One is an axial U(1) symmetry associated with a Qi phase transformation and the other is an anomaly-free R symmetry. 2 This is none other than a superpotential of the O’Raifeartaigh type. [4] Namely, this effective superpotential yields conditions for supersymmetric vacua PfVij = Λ , λ ijVkl = 0, (4) which cannot be satisfied simultaneously as far as Λ 6= 0. Therefore we conclude that supersymmetry is dynamically broken in our model. We note that this conclusion is not in contradiction with the index argument. [5] The doublets Qi cannot be decoupled by means of mass terms m QiQj since the apparent masses may be absorbed in the shifts of the singlets Z . It is straightforward to generalize the above model to an Sp(N) gauge theory [6] with 2(N +1) chiral superfields in the 2N representation. Here we adopt a notation Sp(1) = SU(2). These vector-like models might serve as a supersymmetry-breaking mechanism in the hidden [7] or visible sector.
226 citations
TL;DR: In this paper, the authors studied left-right symmetric models which contain only fermion and gauge boson fields and no elementary scalars, and showed that parity breaking at low energies is automatically broken regardless of the choice of the parameters of the model.
190 citations
TL;DR: In this paper, the three-loop gauge β-function for an abelian N = 1 supersymmetric gauge theory, using DRED, was derived for the non-abelian case.
132 citations
TL;DR: In this article, a simple proof of the relation AanF = &bl (Tr #2) for N = 2 super-symmetric QCD with massless quarks is given.
131 citations
TL;DR: In this paper, the energy density of the wall in strongly coupled Yang-Mills theories is shown to be exactly the same as in the strong coupling regime, and a general mechanism is suggested to lead to massless gauge bosons localized on the wall.
Abstract: Domain walls in strongly coupled gauge theories are discussed. A general mechanism is suggested automatically leading to massless gauge bosons localized on the wall. In one of the models considered, outside the wall the theory is in the non-Abelian confining phase, while inside the wall it is in the Abelian Coulomb phase. Confining property of the non-Abelian theories is a key ingredient of the mechanism which may be of practical use in the context of the dynamic compactification scenarios.
In supersymmetric (N=1) Yang-Mills theories the energy density of the wall can be exactly calculated in the strong coupling regime. This calculation presents a further example of non-trivial physical quantities that can be found exactly by exploiting specific properties of supersymmetry. A key observation is the fact that the wall in this theory is a BPS-saturated state.
129 citations
TL;DR: In this paper, the scattering of R-R gauge bosons off of Dirichlet p-branes is computed to leading order in the string coupling and the results are qualitatively similar to those found in scattering of massless NS-NS bosons, in particular the Regge behavior.
TL;DR: In this article, the problem of the choice of the gauge in which to represent the electromagnetic field in the nonperturbative time-dependent study of the interaction of atoms with intense laser fields is discussed.
Abstract: We discuss the problem of the choice of the gauge in which to represent the electromagnetic field in the non-perturbative time-dependent study of the interaction of atoms with intense laser fields. Even though quantum mechanics is gauge invariant, the velocity gauge is more adopted then the length gauge for dynamical reasons. This property is even more severe when the problem is solved by expanding the wavefunction in spherical harmonics. The point is illustrated through the calculation of the above-threshold ionization photoelectron energy spectrum produced by atomic hydrogen under an intense laser pulse.
TL;DR: In this paper, the mass ranges of new neutral gauge bosons and constraints on the accompanying exotic particles as predicted by a class of superstring models are addressed, and it is shown that breaking of an additional U(1)′ symmetry is radiative when the appropriate Yukawa couplings of exotic particles are of order one, analogous to the radiative breaking of the electroweak symmetry in the supersymmetric standard model due to the large top-quark Yukawa coupling.
Abstract: We address the mass ranges of new neutral gauge bosons and constraints on the accompanying exotic particles as predicted by a class of superstring models. Under certain assumptions about the supersymmetry breaking parameters we show that breaking of an additional U(1)′ symmetry is radiative when the appropriate Yukawa couplings of exotic particles are of order one, analogous to the radiative breaking of the electroweak symmetry in the supersymmetric standard model due to the large top-quark Yukawa coupling. Such large Yukawa couplings occur for a large class of string models. The Z′ and exotic masses are either of , or of a scale intermediate between the string and electroweak scales. In the former case, may be achieved without excessive fine-tuning, and is within future experimental reach.
TL;DR: In this article, a model in which the third generation fermions undergo a different SU (2) weak interaction from the first two generations was discussed, where a flavor changing neutral current interaction is expected at tree level.
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TL;DR: In this article, the results obtained by the "Triple Gauge Couplings" working group during the LEP2 Workshop (1994-1995) are presented. And the detection of new interactions in the bosonic sector via other production channels is discussed.
Abstract: We present the results obtained by the "Triple Gauge Couplings" working group during the LEP2 Workshop (1994-1995). The report concentrates on the measurement of $WW\gamma$ and $WWZ$ couplings in $e^-e^+\to W^-W^+$ or, more generally, four-fermion production at LEP2. In addition the detection of new interactions in the bosonic sector via other production channels is discussed.
TL;DR: In this article, an extended electroweak gauge group was considered, where the first and second generation of fermions couple to SU(2) 1 and the third generation couples to SU (2) 2.
TL;DR: In this article, the effects of super-and super-covariant derivative terms on the Wilson action and the 2PI action for the composite superfield were derived for the case of one and several condensing gauge groups.
TL;DR: In this paper, the spectrum of dyons in N = 4 supersymmetric Yang-Mills theory with gauge group SU(3) spintaneously broken down to U(1) × u(1).
TL;DR: In this paper, the color octet of massive gauge bosons (''colorons'') was studied in the low-energy spectrum of the model's Higgs phase and the implications of recent Tevatron data and the prospective input from future experiments were also discussed.
Abstract: A flavor-universal extension of the strong interactions was recently proposed in response to the apparent excess of high-$E_T$ jets in the inclusive jet spectrum measured at the Tevatron. This paper studies the color octet of massive gauge bosons (`colorons') that is present in the low-energy spectrum of the model's Higgs phase. Constraints from searches for new particles decaying to dijets and from measurements of the weak-interaction $\rho$ parameter imply that the colorons must have masses greater than 870-1000 GeV. The implications of recent Tevatron data and the prospective input from future experiments are also discussed.
TL;DR: In this article, the R-R and NS-NS-NS scattering amplitudes agree in the limit of small momentum transfer with scattering off Dirichlet p-brane solutions found in the low energy supergravities.
Abstract: The scattering of R-R gauge bosons off of Dirichlet p-branes is computed to leading order in the string coupling. The results are qualitatively similar to those found in the scattering of massless NS-NS bosons: all p-branes with p >= 0 exhibit stringy properties, in particular the Regge behavior. Both the R-R and NS-NS scattering amplitudes agree in the limit of small momentum transfer with scattering off the extremal R-R charged p-brane solutions found in the low-energy supergravities. We interpret this as evidence that Dirichlet-branes are an exact world-sheet description of the extremal p-branes. The -1-brane (D-instanton) is a special object which, unlike all other Dirichlet-branes, exhibits point-like behavior. We find the R-R charged instanton solution to type IIB supergravity and confirm that the field theoretic scattering off of this solution miraculously reproduces the full stringy calculation. As an aside, we include a discussion of the entropy of non-extremal black holes in ten dimensions, produced by exciting the 0-brane. We show that, for large black holes, the entropy grows linearly with the black hole mass.
TL;DR: In this article, the one-loop corrections for the decay of an off-shell vector boson with vector couplings into two pairs of quarks of equal or unequal flavors keeping all orders in the number of colours were calculated.
Abstract: We calculate the one-loop QCD corrections for the decay of an off-shell vector boson with vector couplings into two pairs of quarks of equal or unequal flavours keeping all orders in the number of colours. These matrix elements are relevant for the calculation of the next-to-leading order ${\cal O}(\alpha_s^3)$ corrections to four jet production in electron-positron annihilation, the production of a gauge boson accompanied by two jets in hadron-hadron collisions and three jet production in deep inelastic scattering. We use standard techniques for computing the interference of one-loop and tree level Feynman diagrams, but organise the results in terms of combinations of scalar loop integrals that are finite in the limit of vanishing Gram determinants and are therefore numerically stable.
TL;DR: In this article, the authors studied the supersymmetric evolution of the gauge couplings from the scale of their unification to lower scales, and showed how the heavy mass thresholds can be properly taken into account to all orders.
Abstract: The invention of supersymmetry, almost exactly 25 years ago,1 changed the face of high energy physics. The idea that the observed low energy gauge groups appear due to the process of spontaneous breaking of a single unifying group G is also quite popular. The synthesis of these two elements results in supersymmetric grand unification. I present (perturbatively) exact results regarding the supersymmetric evolution of the gauge couplings from the scale of their unification to lower scales. In particular, it is shown how the heavy mass thresholds can be properly taken into account to all orders.
TL;DR: The regularization that is introduced also solves the problem of overlapping divergences in a way similar to geometric regularization and yields the standard values of the {beta} and {gamma} functions of the renormalization group equations.
Abstract: We show that regularization of gauge theories by higher covariant derivatives and gauge-invariant Pauli-Villars regulators is a consistent method if the Pauli-Villars vector fields are considered in a covariant {alpha} gauge with {alpha}{ne}0 and a given auxiliary preregularization is introduced in order to uniquely define the regularization. The limit {alpha}{r_arrow}0 in the regulating Pauli-Villars fields is pathological and the original Slavnov proposal in the covariant Landau gauge is not correct because of the appearance of massless modes in the regulators which do not decouple when the ultraviolet regulator is removed. In such a case the method does not correspond to the regularization of a pure gauge theory but that of a gauge theory in interaction with massless ghost fields. However, a minor modification of the Slavnov method provides a consistent regularization even for such a case. The regularization that we introduce also solves the problem of overlapping divergences in a way similar to geometric regularization and yields the standard values of the {beta} and {gamma} functions of the renormalization group equations. {copyright} {ital 1996 The American Physical Society.}
TL;DR: In this paper, a general method is presented that allows one to determine from the local gauge invariant observables of a quantum field theory the underlying particle and symmetry structures appearing at the lower (ultraviolet) end of the spatio-temporal scale.
TL;DR: This work presents a new gauge-independent approach to resonant transition amplitudes with nonconserved external currents, based on the pinch technique method, that shows the correct high-energy unitarity behavior, admits renormalization, and satisfies a number of other required properties, including the optical theorem.
Abstract: We present a new gauge-independent approach to resonant transition amplitudes with nonconserved external currents, based on the pinch technique method. In the context of 2{r_arrow}2 and 2{r_arrow}3 scattering processes we show explicitly that the analytic results derived respect U(1){sub e}{sub m} gauge symmetry and do not depend on the choice of the SU(2){sub {ital L}} gauge fixing. Our analytic approach treats, on equal footing, fermionic as well as bosonic contributions to the resummed gauge boson propagators, does not contain any residual spacelike threshold terms, shows the correct high-energy unitarity behavior, admits renormalization, and satisfies a number of other required properties, including the optical theorem. Even though our analysis has mainly focused on the standard model gauge bosons, our method can easily be extended to the top quark, and be directly applied to the study of unstable particles present in renormalizable models of new physics. {copyright} {ital 1996 The American Physical Society.}
TL;DR: The massless monopoles should be understood as the duals to the massless gauge bosons that appear as the mediators of the non-Abelian forces in the perturbative sector, argued in particular in a class of Sp(2{ital N}) examples.
Abstract: We use the multimonopole moduli space as a tool for studying the properties of BPS monopoles carrying non-Abelian magnetic charges. For configurations whose total magnetic charge is purely Abelian, the moduli space for non-Abelian breaking can be obtained as a smooth limit of that for a purely Abelian breaking. As the asymptotic Higgs field is varied toward one of the special values for which the unbroken symmetry is enlarged to a non-Abelian group, some of the fundamental monopoles of unit topological charge remain massive but acquire non-Abelian magnetic charges. The BPS mass formula indicates that others should become massless in this limit. We find that these do not correspond to distinct solitons but instead manifest themselves as {open_quote}{open_quote}non-Abelian clouds{close_quote}{close_quote} surrounding the massive monopoles. The moduli space coordinates describing the position and U(1) phase of these massless monopoles are transformed into an equal number of non-Abelian global gauge orientation and gauge-invariant structure parameters characterizing the non-Abelian cloud. We illustrate this explicitly in a class of Sp(2{ital N}) examples for which the full family of monopole solutions is known. We show in detail how the unbroken symmetries of the theory are manifested as isometries of the moduli space metric. We discuss themore » connection of these results to the Montonen-Olive duality conjecture, arguing in particular that the massless monopoles should be understood as the duals to the massless gauge bosons that appear as the mediators of the non-Abelian forces in the perturbative sector. {copyright} {ital 1996 The American Physical Society.}« less
TL;DR: A model of the electroweak interactions as a possible extension of the standard model to higher energies is considered and contains new fermions with ordinary lepton and quark electric charges.
Abstract: We consider an $\mathrm{SU}{(3)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{U}{(1)}_{X}$ model of the electroweak interactions as a possible extension of the standard model to higher energies. The model contains new fermions with ordinary lepton and quark electric charges. There are new gauge bosons with masses in the TeV region. There exists a version of the model with identical low energy predictions as those of the standard model.
TL;DR: In this article, a soluble gauge model is presented which can exhibit the typical characteristics of Gribov's gauge-equivalent copies that exist in the Coulomb gauge of QCD, and correct results can be obtained by including all such copies, both in the Hamiltonian approach using Schrodinger wave functions and in the pathintegration formalism using Feynman rules.
TL;DR: In this paper, the authors studied the symmetric and symmetry broken phases of the 3D, SU(2) gauge-Higgs model and found that W-boson screening mass drops in the symmetry broken phase when approaching the critical temperature.