121137215
Novel perturbation expansion for the Langevin equation
We discuss the randomly driven systemdx/dt= -W(x) +f(t), wheref(t) is a Gaussian random function or stirring force with〈f(t)f(t′)〉=2δ(t−t′), andW(x) is of the formgx1+2δ. The parameterδ is a measure of the nonlinearity of the equation. We show how to obtain the correlation functions〈x(t)f(t′)〉···x(t(n))〉f as a power series inδ. We obtain three terms in theδ expansion and show how to use Padé approximants to analytically continue the answer in the variableδ. By using scaling relations, we show how to get a uniform approximation to the equal-time correlation functions valid for allg andδ.
122089562
SUPERSYMMETRIC APPROACH TO QUASINORMAL MODES
Supersymmetry (SUSY) in quantum mechanics is extended from square integrable states to those satisfying the outgoing wave boundary condition. Using this formalism we obtain new exactly solvable potentials admitting quasinormal modes (QNM) solutions of the Klein–Gordon equation.
14129154
A new class of PT-symmetric Hamiltonians with real spectra
Abstract We investigate complex PT-symmetric potentials, associated with quasi-exactly solvable non-Hermitian models involving polynomials and a class of rational functions. We also look for special solutions of intertwining relations of SUSY quantum mechanics providing a partnership between a real and a complex PT-symmetric potential of the kind mentioned above. We investigate conditions sufficient to ensure the reality of the full spectrum or, for the quasi-exactly solvable systems, the reality of the energy of the finite number of levels.
119751583
On supersymmetry and random sources
We evaluate the one loop effective potential for the supersymmetric Higgs model in the presence of a gaussian random source and examine supersymmetry breaking at the one loop level.
121026122
A Variational approach to the Liouville model
We perform a variational analysis of the Liouville model. In particular we evaluate the effective potential and examine the possibility of restoring translation invariance.
122355855
Comment on the ''Effect of a strong magnetic field and high temperature on broken gauge theories''
In a recent paper Chakrabarti has examined the effects of a strong magnetic field and high temperature on spontaneously broken gauge theories. We point out the invalidity of the approximation he has used to evaluate the one-loop effective potential. Using a rigorous and improved method, we obtain a result different from Chakrabarti's result. Further using this method we extend the results of the aforementioned paper by including fermions in the theory.
123132127
Bare current-quark masses, inelastic reactions, and light-cone algebra.
Abstract Relations connecting the effective bare current-quark masses with asymptotic meson-nucleon and lepton-nucleon scattering are derived by making use of the extended light-cone algebra which includes commutators of pseudoscalar densities. The commutators are relevant to meson-nucleon scattering amplitudes since the pseudoscalar densities act as fields of the (composite) mesons. Assuming pomeron-exchanged Regge behaviour, sufficient analyticity in the meson mass-squared variable is established to obtain finite-mass dispersion and superconvergence relations. Making additionally certain other reasonable assumptions, we are then able to show how these relations yield testable connections among the asymptotic πN and KN total cross sections, the structure functions of the deep inelastic lepton-nucleon scattering (for the scaling variable, ξ →0) and the bare current-quark masses μp, n, λ that appear essentially as parametrising the breaking of the chiral SU(3) ⊗ SU(3) symmetry. One interesting consequence of our results is at the Llewellyn-Smith inequality on the said structure functions should be experimentally satisfied as a near equality for ξ → 0, if chiral SU(2) ⊗ SU(2) turns out to be a rather good symmetry of nature. Moreover, taking the specific symmetry breaking model of Gell-Mann Oakes and Renner,we find that μp, n ≈ 35 MeV and μλ ≈ 800 MeV.
119615417
What neutral current experiments can tell us about left-right symmetry
Abstract Neutral current consequences of left-right symmetry for the gauge group SUL(2) × SUR(2) × U(1) are derived in the form of experimentally testable relations. Additional results follow from the hypothesis of no exotic charges. Some of these tests can distinguish such theories from the Weinberg-Salam model.
16313257
Oblique electroweak corrections and triple vector boson couplings
We relate all $C$-- and $P$--invariant anomalous triple vector--boson couplings to the oblique electroweak parameters. LEP constraints on the latter then yield the strongest and most general simultaneous bounds to date on the former. Even if the oblique parameters assume their Standard Model values precisely, these bounds would not shrink to zero---thus underscoring the need for direct experimental probes at future colliders.
121460845
Spinor-inverted solution to thirring model and its generalization to U(n) symmetry
Abstract Using the properties of massless free Fermi fields in (1-1) dimensions, it is shown that the spinor inverted form of Klaiber's operator solution to Thirring model is also a scale-invariant solution of the model. But unlike the former it admits a nonvanishing SU(n) current coupling in the generalization of the model to include U(n) symmetry. The value of this coupling constant is fixed and equals Dashen-Frishman number −4π (n + 1) . The general form of the 2m-point function is given and operates product expansions are exhibited in terms of composite local operators. Scale dimensions of all the bilinear and quadrilinear local operators with U(n) symmetry are computed and are found to depend on n. However, different parts of a composite local operator belonging to different irreducible U(n) representations have the same dimension.
18365464
Radiative electroweak parameters
The status of the present precision measurements of electroweak observables is reviewed with specific reference to the radiative parametersS, T, U or equivalently ε1,ε2, ε3. The significance of the obliqueness hypothesis is underlined and the importance of the “local fit” method of extracting these parameters from the data is emphasized. Possible new physics implications are briefly touched upon.