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1.
We develop a (classical) local field theory which contains as a special solution the (classical) dual string recently discussed by Goddard, Goldstone, Rebbi and Thorn. The basic field is a gauge field Fμν(x), and the Lagrangian is given by (?12α')√F2. We treat the case of closed strings (corresponding to the Shapiro-Virasoro model) where Fμν can be expressed in terms of potentials Aμ. Quantization of Fμν is briefly discussed, but a more thorough discussion is postponed.  相似文献   

2.
Spontaneously broken gauge theories in a constant external electromagnetic field are shown to exhibit a first-order phase transition to a restored symmetry phase when the external field exceeds a certain critical value. The effects of fields characterized by various values of the two Lorentz invariants F1 = 12(B2 ? E2) and F2 = E · B are discussed. In a simple SU(2) model the critical field strength is found to be gR2(F1)crit = 0.057 mw4, mw being the vector boson mass. A number of theoretical developments in the background field formalism are presented. A new gauge-fixing term, the background field R gauge, is introduced. The configuration space heat kernel method for evaluating functional determinants, extended to allow the use of dimensional regularization, is employed, and it is shown how to perform background field calculations in a gauge specified by an arbitrary parameter α. Further applications of these methods are discussed.  相似文献   

3.
An effective action for QCD at one-loop order, which is real, manifestly Lorentz and gauge invariant and which depends on an infinite family of gauge invariants (tr(F μν F μν), tr(F μν F μν F F ),...), is obtained. Moreover, anAnsatz for a vacuum configuration is made, whose corresponding vacuum energy density is lower than the one for the SavvidyAnsatz. Both the cases of pure QCD and of QCD with massless fermions are considered.  相似文献   

4.
It is argued that since in asymptotically free Yang-Mills theories the quantum ground state is not controlled by perturbation theory, there is no a priori reason to believe that individual orbits corresponding to minima of the classical action dominate the Euclidean functional integral. To examine and classify the vacua of the quantum gauge theory, we propose an effective action in which the gauge field coupling constant g is replaced by the effective coupling g(t), t = ln[Fμνa)2μ4]. The vacua of this model correspond to paramagnetism and perfect paramagnetism, for which the gauge field is Fμνa = 0, and ferromagnetism, for which (Fμνa)2 = λ2, i.e. spontaneous magnetization of the vacuum occurs. We show that there are no instanton solutions to the quantum effective action. The equations for a point classical source of color spin are solved, and we show that the field infrared energy becomes linearly divergent in the limit of spontaneous magnetization. This implies bag formation, and an electric Meissner effect confining the bag contents.  相似文献   

5.
Spin-12 fermions are coupled to external axial vector and rank-2 anti-symmetic tensor fields. The chiral U(1) Ward identity is shown to have anomalous structure given by FμνF?μν only with Fμν the axial vector field strength tensor. No Additional axial anomalied are introduced due to the presence of the anti-symmetric tensor fields.  相似文献   

6.
The role of antisymmetric tensor fields in the gauging of groups is related to theorems on cohomology theory, and Cartan integrable systems are discussed. Examples are given. Various possibilities to gauge d = 11 supergravity by decontracting its underlying group are considered. In particular the simple supergroups Osp (1 | 64) and SU(32 | 1) yield a negative result, but a certain non-semisimple supergroup containing Osp (1 | 32) is proposed as a viable candidate. The corresponding action would no longer contain the 3-index photon Aμν?, but instead a second spin 32 field ημ and boson fields Bμa1a2 and Bμa1…a5. A first order formalism for d = 11 is presented. It is to be used for an improved form of dimensional reduction.  相似文献   

7.
A vibrational and rotational analysis is presented for the D′ → A′ transition (2800–2950 Å) of Br2. The analysis includes 11 rotationally analyzed bands for 79Br2 and 3 for 81Br2, plus bandheads for 70 additional v′-v″ bands of 79Br2, 81Br2, and 79Br81Br. The latter include some violet-degraded and spikelike features at the long-wavelength end of the spectrum, which are interpreted and assigned with the aid of band profile simulations. The assigned features are fitted directly to 14 vibrational and rotational expansion parameters for the two electronic states, from which the following spectroscopic constants are obtained: ΔTe = 35706 cm?1, ωe = 150.86 cm?1, ωe = 165.2 cm?1, Be = 0.042515 cm?1, Be = 0.05944 cm?1, R′e = 3.170 A?, R″e = 2.681 A?. The spectroscopic parameters are used to calculate RKR potentials and Franck-Condon factors for the transition.  相似文献   

8.
A detailed vibrational analysis is given for the D′(2g) → A′(2u3Π) transition (3300–3460 Å) in I2. The assignments include ~ 150 v′-v″ bands in 127I2 and ~100 in 129I2, spanning v′ levels 0–15 and v″ levels 4–30. These bands are mainly red-degraded but include some violet-degraded and line-like features. The analysis is corroborated by Franck-Condon and band profile calculations. The least-squares fit yields the following constants (cm?1); ΔTc = 30 340.8, ωe = 103.95, ωeχe = 0.206, ωe = 106.1, ωeχe = 0.81. Anomalous behavior in the vibrational level structure above v″ = 23 makes the extrapolation to the A′ dissociation limit uncertain, so the absolute energies of both states remain ill-defined. However there is a possibility that the D′ state is the state labeled α by King et al. [Chem. Phys. 56, 145–156 (1981)], in which case the energies are known precisely. There is evidence of weak emission from at least two other electronic transitions in this spectral region, probably D(0+u) → X(1Σg+) (λ < 3300 A?) and βA(1u3Π) (λ > 3300 A?).  相似文献   

9.
We classify, according to the number of independent gauge fields, Poincaré gauge invariant theoretical frameworks of describing gravity into three categories. One of them may provide the dynamical definition of the spin tensor S and that of the energy-momentum tensor T, resulting in the response equation of matter to gravity with the gravitational field strengths, D′ and F, coupled to the former tensors
Tνμ;μ=D′μλνTμλ+FμλνρSρμλ
, where the right-hand side represents spin force densities. In the absence of spin the response reduces to the conventional one of general relativity, i.e., without the spin forces. For the electromagnetic field the phase-gauge invariance requires the same conclusion as for a scalar field. For a spin 12 particle there is torsion, which deflects its trajectory from geodesic; an explicit expression for torsion takes a simple form of the axial vector current ψγ5γkψ.  相似文献   

10.
A weak emission spectrum of I2 near 2770 Å is reanalyzed and found to to minate on the A(1u3Π) state. The assigned bands span v″ levels 5–19 and v′ levels 0–8. The new assignment is corroborated by isotope shifts, band profile simulations, and Franck-Condon calculations. The excited state is an ion-pair state, probably the 1g state which tends toward I?(1S) + I+(3P1). In combination with other results for the A state, the analysis yields the following spectroscopic constants: Te = 10 907 cm?1, De = 1640 cm?1, ωe = 95 cm?1, R″e = 3.06 A?; Te = 47 559.1 cm?1, ωe = 106.60 cm?1, R′e = 3.53 A?.  相似文献   

11.
Pb2, which occurs in lead vapor, was studied by the technique of laser-induced fluorescence using single-mode Ar-laser excitation. The fluorescence observed could be classified into the F-X system. Ten progressions involving vibrational quantum numbers v′ = 0?9 and v″ = 0?22 were analyzed. Including collision-induced lines, rotational quantum numbers from J = 25 to J = 300 were observed. The vibrational constants and the numbering of the states had to be reassigned. For the first time rotational constants were determined for the Pb2 molecule. The internuclear distances of 208Pb2 in the F and X state are r = 3.079 A? and re = 2.930 A?, respectively. Using the constants derived RKR potentials and Franck-Condon factors were calculated, which confirmed the vibrational assignments and constants.  相似文献   

12.
We consider the Born approximation scattering, by electrons, of neutrinos (and antineutrinos) of the muon and of the electron types; the general Lagrangian respecting lepton locality is used. Throughout, we study only differential cross sections as the experimental observables. Some tests previously proposed for “neutrino identity” or Lorentz structure of the neutral weak interaction are reexamined. We find that, in general, these relations cannot uniquely answer the question of Lorentz structure. Similarly, in general, one cannot estblish whether the final neutral lepton is completely identical with, or “partly identical” with, or completely different from, the initial neutrino; identity allows a difference in helicity. In several experimental situations, one can exclude the possibility of a complete non-identity. In one experimental situation, assuming μe universality, one can establish that the final and the initial neutrinos are completely identical, even in their helicity. “Does an interference between neutral currents and the (V ? A) charged current exist in
e- scattering?” Certain tests can answer this question completely if μe universality is assumed. Without μe universality, the answer is “destructive interference” if an observable (Ae) turns out to be less than 4; Ae = 4 would exclude a constructive interference. Assuming neutrino identity, time-reversal invariance for the helicity flipping types (S,P,T), and μe universality, certain simple combinations of observables were previously noted to determine the (V,A) neutral interaction couplings of the neutrino to the electron. With our general formalism, that determination is seen not to require the first two assumptions. Also, the couplings concerned are seen to be only the “diagonal” ones—which refer to that part of the final state in which the final neutrino is identical with the iniitial one. Keeping in view a recent experimental situation, the following question is answered: “When will the lack of enough events for νe? scattering (or, similarly, νe? scattering) become a threat to lepton locality?” Some additional consequences of μe universality are noted.  相似文献   

13.
A.H. Taub 《Annals of Physics》1981,134(2):326-372
If V is a space-time with metric tensor gμν admitting a null, geodesic shear free vector field lμ, then one may determine a function H so that the spacetime V? with metric gμν = gμν + 2Hlμlν satisfies the Einstein field equations for various material sources, and for no sources. When V is Minkowski space, V? is a Kerr-Schild space-time. In case V is a vacuum space-time, one may choose H so that the source is a null fluid with no pressure. In case V is a Robertson-Walker universe H may be chosen so that the source has a stress-energy tensor with one timelike proper vector and three spacelike ones. There are two equal proper values associated with the latter vectors and one which differs from these. The stress-energy tensor describing this source may be interpreted as representing a perfect fluid with anisotropic pressures or as one describing the sum of a perfect fluid with isotropic pressures and a presureless null fluid. Vaidya's Kerr metric in a cosmological background [Pramana8 (1977) 512–517] is discussed as is the metric representing an accelerating point mass in an expanding universe.  相似文献   

14.
The O+ glueball mass in the fundamental-adjoint SU(2) la ttice gauge theory is extracted from the Monte Carlo data on the correlation functions at time distances t = 1 and t = 2 on a 84 lattice. The ratio mgσ is constant in the βFA region explored giving more evidence in favour of the universality hypothesis.  相似文献   

15.
The renormalization of Abelian and non-Abelian local gauge theories is discussed. It is recalled that whereas Abelian gauge theories are invariant to local c-number gauge transformations δAμ(x) = ?μ,…, withΛ = 0, and to the operator gauge transformation δAμ(x) = ?μφ(x), …, δφ(x) = α?1?·A(x), with □φ = 0, non-Abelian gauge theories are invariant only to the operator gauge transformations δAμ(x) ~ μC(x), …, introduced by Becchi, Rouet and Stora, where
μ is the covariant derivative matrix and C is the vector of ghost fields. The renormalization of these gauge transformation is discussed in a formal way, assuming that a gauge-invariant regularization is present. The naive renormalized local non-Abelian c-number gauge transformation δAμ(x) = (Z1/Z3)gAμ(x) × Λ(x)+?μΛ(x), …, is never a symmetry transformation and is never finite in perturbation theory. Only for Λ(x) = (Z3/Z1)L with L finite constants or for Λ(x) = Ωz?3C(x) with Ω a finite constant does it become a finite symmetry transformation, where z?3 is the ghost field renormalization constant. The renormalized non-Abelian Ward-Takahashi (Slavnov-Taylor) identities are consequences of the invariance of the renormalized gauge theory to this formation. It is also shown how the symmetry generators are renormalized, how photons appear as Goldstone bosons, how the (non-multiplicatively renormalizable) composite operator Aμ × C is renormalized, and how an Abelian c-number gauge symmetry may be reinstated in the exact solution of many asymptotically fr ee non-Abelian gauge theories.  相似文献   

16.
Although A′(3Π2) ← X(1Σ+) is forbidden in near case c molecules the A′ ← X transition can be efficiently accomplished by the three-step sequence A′(3Π2) ← D′(2) ← A(3Π1) ← X(1Σ+). Transitions to a range of levels of A′, vA = 2–38, have been recorded by this means, using J-selective polarization-labeling spectroscopy. Principal constants of the A′ state of I35Cl are Te = 12682.05, ωe = 224.57, ωeχe = 1.882, ωeye = ?0.0107, Be = 0.08653, and αe = 0.000675 cm?1. The A′ state is therefore similar in its physical characteristics to two other (relatively) deep states, A(3Π1) and B(3Π0+), of the 2431 configuration.  相似文献   

17.
The natural conservation of flavours to O(GF2) in neutral weak interactions severely constrains choices of gauge groups as well as their fermion representations. In the absence of exactly conserved quantum numbers other than charge, and of |ΔQ| ? 2 charged currents, essentially the only weak and electromagnetic gauge groups whose neutral interactions naturally conserve all flavours are SU(2)L ? U(1) and SU(2)L ? [U(1)]2. The plausible extensions of these gauge groups to grand unified models including the strong interactions are based on SU(5) and SO(10) respectively. Making the SU(5) model completely natural, including in the Higgs sector, gives the prediction md/me ? ms/mμ ? mb/mτ ? 2605 where τ is the probable new heavy lepton and b is the conjectured third flavour of charge ?13quark. The SO(10) model contains a potential SU(2)L ? SU(2)R ? U(1) weak and electromagnetic gauge group, and has a complicated Higgs structure which does not naturally conserve quark flavours.  相似文献   

18.
The radiative corrections of O(α) to the final electron spectrum and the total cross sections for the processes νμ + e → νμ + e, νμ + e → νe + e, νe + e → νe + e andνe + e are studied in the framework of the SU(2)L ? U(1) theory. The electroweak corrections to the fisrt two processes are presented in two equivalent schemes in terms of (Gμ, sin2θw) and (Gμ, sin2θ?w(mw)). As a byproduct, the relationship to O(α) between the basic parameters sin2θW ≡ 1 ? mW2/mZ2and sin2θ?W(mW) (defined by modified minimal subtraction) is explicitly given. The QED corrections are evaluated in the extreme relativistic (ER) regime of the final electron (Ee ? me) for the situation in which the bremsstrahlung photons are unobserved and unrestricted. The ER approximation allows us to obtain simple analytic expressions for the differential electron spectrum and the total cross sections. The relationship to O(GFα) between the spin-averaged differential cross sections for the above processes in the ER regime is derived.  相似文献   

19.
The microwave spectra of eight isotopic species of COCl2 have been observed, and the following rotational constants have been obtained: An analysis of the rotational constants has resulted in the rs and rm structures. The equilibrium structure, re, has been estimated by combining the rm parameters derived according to Watson's method and the re bond distances estimated in our recent electron-diffraction and spectroscopic studies to be re(CO) = 1.1756 ± 0.0023 A?, re(CCl) = 1.7381 ± 0.0019 A?, ∠eClCCl = 111.79 ± 0.24°.  相似文献   

20.
We present a unified gauge theory of weak and electromagnetic interactions in which parity is spontaneously broken together with gauge invariance, by the Higgs mechanism. The gauge group is SU(2) × U(1), and a heavy neutrino is associated with every charged lepton. After the breaking of the original parity-conserving theory, both a purely vector electromagnetic current and the usual V-A charged currents are obtained. Z is coupled to a vector electron current, and the model predicts equal νμe andνμe cross sections. Extension to hadrons is made by introducing three charmed quarks p′, n′ and λ′ of the same charges as p, n and λ. All the experimental results μe, νμe, νee, νμ and νμ hadron scatterings) are compatible with a value of sin2θW of order 0.4.  相似文献   

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