Showing papers in "Physics Letters B in 1991"

TL;DR: In this paper, the DELPHI Collaboration data was used to show that in the minimal non-supersymmetric standard model with one Higgs doublet a single unification point is excluded by more than 7 standard deviations.

TL;DR: In this article, a class of multicanonical Monte Carlo algorithms is presented which can reduce the slowing down to a quadratic power law ≈V2. But this algorithm is not suitable for the case of finite volumes.

TL;DR: In this paper, a new method of massive Feynman diagram calculation is presented, which provides a fairly simple procedure for obtaining the result without D -space integrals for dimensional regularization.

TL;DR: In this article, the lightest neutral Higgs boson in the minimal supersymmetric extension of the standard model has a tree-level mass less than that of the Z 0.

TL;DR: In this paper, the standard q-deformation of the Cartan-Weyl basis for o(3,2) ⋍ sp (4| R ) (real form of C2) is calculated.

TL;DR: In this article, the chiral logarithmic corrections to the axial current for semileptonic hyperon decay and for the analysis of the strangeness content of the proton are computed as examples.

TL;DR: In this paper, the QCD corrections to the fusion cross section in the Higgs mass range below the top-antitop threshold are presented, and the corrections are large, being of the order of 60%.

TL;DR: In this paper, a new clustering algorithm was proposed to predict the jet cross sections at small y cut for arbitrary n. This algorithm can be used to compute the leading and next-to-leading logarithm of y cut to all orders in QCD perturbation theory.

TL;DR: In this paper, the problem of the cosmological constraints on the axion mass is re-examined and it is argued that in the context of inflationary cosmology the constraint m a ≳10 −5 eV can be avoided even when the axions perturbations produced during inflation are taken into account.

TL;DR: In this article, the string-modified, Einstein-Friedman equations are shown to possess physically-inequivalent, duality-related solutions which generically describe the "decay" of an initial, perturbative, flat D =10 superstring vacuum towards a more intersting strong-coupling state through an appealing pre-big-bang cosmological scenario.

TL;DR: The determination of the σ-term from πN scattering is critically examined in this paper, where low-energy precision measurements are needed to clarify discrepancies in experimental data and to reduce the uncertainty in the strangeness content for which y ≅ 0.2.

TL;DR: In this article, the authors present analytic one-loop expressions for sin 2 θ w, the unification scale M x, and the coupling at the unification level α (M x ), in supersymmetric grand-unified models with arbitrary intermediate scales.

TL;DR: In this paper, the authors estimate the strength of the electromagnetic fields produced due to the electroweak phase transition in the early universe and show that the resulting electromagnetic fields can also produce magnetic fields of other unbroken gauge symmetries such as SU(3)c.

TL;DR: In this paper, the effects of new physics on vacuum polarization corrections to electroweak processes can in general be parametrized in terms of six real constants, in the limit of neglecting terms which vanish for Λ→∞.

TL;DR: In this paper, the one-loop radiative corrections to the mass of the neutral CP -odd Higgs boson (A) in the minimal supersymmetric extension of the standard model, as well as to the even Higgs (h, H) masses and mixing angles were presented.

TL;DR: In this article, exact solutions to the field equations of eleven-dimensional supergravity corresponding to stable multi-membrane configurations are given by the SO(8) subgroup of an enlarged tangent space group SO(1, 2)×SO(16), and hence one half of spacetime supersymmetries are broken.

TL;DR: In this article, the authors presented the results of the total analytical reevaluation of the massless next-next-to-leading αs3 QCD correction to R(s) = σtot(e+e−→γ→hadrons)/σ(e−e −→μ+μ−).

TL;DR: In this article, the authors extended the massive Feynman integral calculation method to N-point diagrams and obtained a simple algorithm which allows them to reduce the N-Point diagram to the (N - 1) point diagram.

TL;DR: In this paper, the weak phase γ was determined from the CP asymmetry in B±→D01(2)X±, where X± is any hadronic state with the flavor of a K±.

TL;DR: In this article, the mass of the lightest Higgs boson in the minimal supersymmetric standard model was calculated by solving one-loop renormalization-group equations.

TL;DR: In this paper, a color embedding, SU(3) c → SU( 3) 1 × SU (3) 2, was proposed to break electroweak symmetries through top quark condensation.

TL;DR: In this article, it was shown how the standard model can be extended so that both the lagrangian and the vacuum are invariant under appropriately defined space-and time-inversion transformations.

TL;DR: In this article, the coefficients of the identity operator are determined by the elements of the matrix S which implements modular transformations on the torus and the other coefficients are related to the matrix implementing duality transformation on the conformal blocks of the four-point functions on the sphere.

TL;DR: In this article, the authors remark about an amusing universality in the thermodynamic Bethe ansatz equations for ADE-related diagonal scattering theories and show that the universality of the Bethe- ansatz equation for diagonal scattering is also applicable to the ADE theory.

TL;DR: In this article, the authors computed the next-next-to-leading order QCD corrections to the Gross-Llewellyn Smith sum rule for deep inelastic neutrino-nucleon scattering and to the Bjorken sum rules for polarized electron nucleon scatter.

TL;DR: In this article, the time-dependent decay rates of the three processes B d 0 → D 0 K s, D 0 k s, and D 1 0 K S, where D10 is a neutral D meson CP-eigenstate, were derived from the unitarity triangle of the Cabibbo-Kobayashi-Maskawa matrix.

TL;DR: In this paper, the concept of discrete scale-factor-duality transformations is extended to a full, continuous O(d, d) group and the action of the group transforms cosmological solutions of the low-energy, string-modified Einstein equations (including non-trivial dilaton and antisymmetric tensor fields) into other solutions, thus representing the natural generalization of Narain's construction to time-dependent, notnecessarily compact manifolds.

TL;DR: In this paper, it was shown that any discrete gauge symmetry should also obey certain discrete anomaly cancellation conditions, which strongly constrains the fermion content of the theory and follow from the parent cancellation of the usual continuous gauge anomalies.

TL;DR: The significance of the interpretation of heavy-ion fusion cross sections in terms of a distribution of potential barriers is discussed in this article, where the smoothing due to the quantal barrier penetration is shown to replace a set of discrete barriers by an effective continuous distribution.

TL;DR: Chiral logarithmic corrections to the baryon axial vector currents in semileptonic hyperon decay are computed in this paper including intermediate octet and decuplet states.