共查询到20条相似文献,搜索用时 15 毫秒
1.
A.A. Anselm 《Physics letters. [Part B]》1979,87(4):371-374
A new mechanism for symmetry breaking is suggested which is connected with the negative contribution of quark loops to the vacuum energy and with the strong interactions of quarks with gluons diminishing this effect. The “gluon mechanism” of symmetry breaking makes it possible to estimate the mass of the heaviest quark (~ 60 GeV) and the mass of the Higgs boson (~ 7 GeV). 相似文献
2.
M.K Volkov 《Annals of Physics》1984,157(1):282-303
On the basis of a effective “superconductivity”-type four-quark interaction, phenomenological Lagrangians are obtained for interactions of scalar, pseudoscalar, vector, and axial vector meson nonets. The Lagrangians include mass terms breaking chiral and U(3) invariance and corresponding to the quark masses mu ≠ md ≠ ms. It is shown that upon introducing boson fields the masses of current quarks in the initial Lagrangian are replaced by the masses of constituent quarks in the phenomenological boson Lagrangians. Estimates of these masses are presented. Electromagnetic interactions are considered, and the vector dominance model is derived. The widths of various meson decays are calculated. 相似文献
3.
YANG Xin-E 《中国物理C(英文版)》1985,9(5):537-541
We propose a composite model of leptons and quarks containing two constituent fermions of spin 1/2 and a constituent scalar. The constituent fermions are massless and color singlets. Leptons, quarks and weak vector bosons are composites confined by SU(3)H local gauge interaction, where leptons are made of three constituent fermions and quarks are two-body composites of a scalar and a fermion. The number of the constituent particles is less in our model. There are less exotic leptons and quarks. Quark-lepton parallelism holds. Weak interactions appear only at the composite level as residual short-range interactions among hypercolor singlets. The violation of parity occurs by the mechanism of dynamical symmetry breaking. 相似文献
4.
Simon Dalley 《Annals of Physics》2006,321(2):402-420
We discuss the origin of chiral-symmetry breaking in the light-cone representation of QCD. In particular, we show how quark helicity symmetry is spontaneously broken in SU (N) gauge theory with massless quarks if that theory has a condensate of fermion light-cone zero modes. The symmetry breaking appears as induced interactions in an effective light-cone Hamiltonian equation based on a trivial vacuum. The induced interaction is crucial for generating a splitting between pseudoscalar and vector meson masses, which we illustrate with spectrum calculations in some 1 + 1-dimensional reduced models of gauge theory. 相似文献
5.
《Nuclear Physics B》1986,274(1):157-170
The standard model is extended to incorporate spontaneous CP breaking which is transmitted to quarks and leptons by scalar leptoquarks. This provides a simple solution to the strong CP problem. Such models are best tested by searches for μe conversion. However, they may induce rare K decays for which there are current experimental searches. 相似文献
6.
We explore in detail the hypothesis that quarks and leptons are the approximately massless quasi Goldstone fermions of a supersymmetric preon theory. In particular, we discuss the possible patterns of states emerging from the spontaneous breakdown of global symmetries in supersymmetric theories and construct the low-energy effective lagrangians describing the interaction of these states. In contrast to what happens in the Goldstone sector, the interactions of the quasi Goldstone fermions contain arbitrary parameters which directly reflect the preon dynamics. Various models are explored, including both models in which the weak interactions are residual and models where these interactions are fundamental. A variety of issues are addressed, from the universality and approximate SU(2)L nature of the weak interactions, for the former class of models, to the generation of states beyond the quarks and leptons and the nature of the dynamical breaking of SU(2)L×U(1), for the latter class of models. Open questions and speculations connected with the origin of families and the nature of fermion mass generation, including supersymmetry breaking, are also discussed. 相似文献
7.
Bernreuther W Bonciani R Gehrmann T Heinesch R Leineweber T Mastrolia P Remiddi E 《Physical review letters》2005,95(26):261802
Interactions of heavy quarks, in particular, of top quarks, with electroweak gauge bosons are expected to be very sensitive to new physics effects related to electroweak symmetry breaking. These interactions are described by the so-called static form factors, which include anomalous magnetic moments and the effective weak charges. We compute the second-order QCD corrections to these static form factors, which turn out to be sizable and need to be taken into account in searches for new anomalous coupling effects. 相似文献
8.
We investigate the hypothesis that the observed weak interactions are the residual interactions of quasi Goldstone fermions. Left-handed quarks and leptons arise from the spontaneous symmetry breaking U(6) → U(4) × SU(2) in a supersymmetric theory. The simplest preon model realizing this breakdown leads, in the complementary picture, to the supersymmetric extension of the standard model of electroweak interactions. Furthermore, 't Hooft's anomaly conditions are satisfied with respect to the unbroken subgroup of the U(6) flavour symmetry and R-invariance. The preon model predicts the existence of a ninth chiral supermultiplet, the novino. 相似文献
9.
A simple model of dynamical symmetry breaking is presented in which the mass matrices of the up and down quarks are related to a (ETC) vector-boson mass-matrix in the 10–100 TeV range. Realistic quark masses and Cabibbo angles can be obtained. The problem of flavour-changing neutral interactions in theories of dynamical symmetry breaking is discussed in the context of this model. 相似文献
10.
Using the supersymmetry and R-breaking mechanism induced by N=1 supergravity, we develop the minimal flavon-chromon preonic model where and spin-0 components of four preonic chiral multiplets correspond to flavons and chromons, from which quarks and leptons are made as composites. The emergence of the concepts of flavour and colour, in this minimal model, is synonymous with R and supersymmetry breaking. This breaking also gives a heavy mass to the gaugino, which is necessary for the implementation of the model. 相似文献
11.
A new model for the substructure of leptons, quarks and weak bosons is investigated. The weak interactions are residual effects due to the substructure. No spontaneous symmetry breaking is needed to generate masses. The structure of the weak interactions at high energies is expected to deviate substantially from the one predicted by the standard SU(2) × U(1) theory. 相似文献
12.
A. Barducci R. Casalbuoni S. De Curtis D. Dominici R. Gatto 《Physics letters. [Part B]》1984,147(6):460-464
We calculate the effective two-loop potential of QCD with massive quarks in the CJT composite operator formalism. To perform the wave-function renormalization of composite operators we are lead to a condition which corresponds to the Adler-Dashen requirement in the limit of vanishing quark masses. The condition also assures absence of spontaneous breaking of parity. Pseudoscalar masses are calculated from the second derivatives of the effective potential, and a fit is obtained for quark masses mu = 3.6 MeV, md = 7 MeV, ms = 152 MeV. We also comment on consistuent quark masses and on the effect of heavy quarks. 相似文献
13.
14.
We extend the supersymmetric, confining theory of weak interactions to a left-right symmetric model. This model is based on the gauge group SU(M)SC×SU(2)R×SU(2)L×SU(3)c×U(1) and is more natural as far as supersymmetry breaking is concerned. Supersymmetry protects chiral symmetries from spontaneous breakdown and allows a solution to the strong CP problem. This model can accommodate at most three generations of quarks and leptons. 相似文献
15.
S. A. Selesnick 《International Journal of Theoretical Physics》2013,52(4):1088-1121
We consider symmetry breaking in the context of vector bundle theory, which arises quite naturally not only when attempting to “gauge” symmetry groups, but also as a means of localizing those global symmetry breaking effects known as spontaneous. We review such spontaneous symmetry breaking first for a simplified version of the Goldstone scenario for the case of global symmetries, and then in a localized form which is applied to a derivation of some of the phenomena associated with superconduction in both its forms, type I and type II. We then extend these procedures to effect the Higgs mechanism of electroweak theory, and finally we describe an extension to the flavor symmetries of the lightest quarks, including a brief discussion of CP-violation in the neutral kaon system. A largely self-contained primer of vector bundle theory is provided in Sect. 4, which supplies most of the results required thereafter. 相似文献
16.
《Nuclear Physics B》1988,306(4):809-848
We present arguments that QCD at low momenta is reduced to a simple theory given by a path integral over pion fields and quarks which obtain dynamical mass owing to chiral symmetry breaking. The dimensional quantities of this low-momenta theory are fixed through the ΛQCD parameter. The effective chiral lagrangian is given by a quark determinant in a background chiral field. Its properties are investigated both for slowly and rapidly varying pion fields. Though it satisfies requirements known from theory and phenomenology, it does not possess non-trivial soliton solutions. However we show that, at large Nc, nucleons correspond not to the local minimum of the effective chiral lagrangian but to a minimum of a more subtle quantity. In general, different functionals of the chiral field should be minimized, depending on the baryon charge of the system.We obtain a quantitative picture of nucleons as localized states of “constituent” quarks bound by a self-consistent pion field. Its properties, such as electromagnetic form factors, etc., are investigated in detail. We get very reasonable numerical values for the nucleon static properties. 相似文献
17.
We discuss the problem of constructing a model in which supersymmetry is unbroken down to low energies. It is suggested that the scalar partners of quarks and leptons may get their masses through radiative corrections and that the breaking of the weak interactions also occurs through radiative corrections. A toy model is constructed which illustrates these ideas. 相似文献
18.
We discuss the mixing of pseudoscalar mesons, in particular SU(3) breaking effects, based on ideas abstracted from QCD. The admixtures of η and η′ in ηc are calculated and utilized to estimate the M1 radiative decays ψ → ηγ, η′γ. A reasonably consistent picture emerges for these decays as well as others involving only the light quarks. 相似文献
19.
《Nuclear Physics B》1999,537(1-3):184-202
We study supersymmetry breaking due to the presence of branes on anti-de Sitter space and obtain conditions for brane orientations not to break too many supersymmetries. Using the conditions, we construct a brane configuration corresponding to a baryon in large N gauge theory, and it is shown that the baryon is a marginal bound state of quarks, as is expected from supersymmetry. 相似文献
20.
Spontaneous breaking of chiral symmetry is investigated in the Hamiltonian approach to QCD in Coulomb gauge. The quark wave functional is determined by the variational principle using an ansatz which goes beyond the commonly used BCS-type of wave functionals and includes the coupling of the quarks to the transversal spatial gluons. Using the lattice gluon propagator as input it is shown that the low energy chiral properties of the quarks, like the quark condensate and the constituent quark mass, are substantially increased by the coupling of the quarks to the spatial gluons. Our results compare favorably with the phenomenological values. 相似文献