122331597
Some Anisotropic Homogeneous Cosmological Models in Self-creation Cosmology
The paper presents an exact solution of cylindrically symmetric cosmological models which are of Petrov type-I or Petov type-D in Barber’s second self-creation theory of gravitation. Some physical and geometrical properties of these models are also discussed.
120331693
Bianchi Type-I Cosmological Model Filled with Viscous Fluid in a Modified Brans-Dicke Cosmology
Adding the cosmological term, which is assumed to be variable in Brans-Dicke theory we have discussed about a Bianchi type-I cosmological model filled with viscous fluid with free gravitational field of Petrov type-D. The effect of viscousity on various kinematical parameters has been discussed. Finally, this model has been transformed to the original form (1961) of Brans-Dicke theory including a variable cosmological term.
121164064
The "Herbst Hamiltonian" and the mass of boson stars
Abstract We present new accurate lower bounds on the ground state of the Hamiltonian p 2 +m 2 − α r . From these, we obtain a lower bound on the maximum mass of a boson star in the semirelativistic framework, and we compare it to a variational upper bound. We get 0.846 ( Gm ) −1 M max Gm ) −1 , where G is Newton's constant and m the boson mass.
120734068
Conformally invariant field theories in two dimensions and corresponding statistical mechanical models
Belavin, Zamlodochikov and Polyakov have recently proposed a class of conformally invariant field theories in two dimension with exactly determined rational critical indices. We establish a tentative identification of a subset of these theories in terms of the O(n) model and theq-state Potts model in 2-dimensions for appropriaten andq.
119542670
Exact solution of a meiman problem with an application to the pionic contribution to the muon magnetic moment
An exact solution is obtained tp the follpwing problem: given a form factor F(t) analytic in the cut t plane, to find a lower bpund to a weighted ontegral over |F(t)|2 over the cut in the presence of space-like data and also time-like data on both the modulus and the phase of F(t). The solution is used to obtain a lower bound on the pionic contribution to the muon magnetic moment (aμ(ππ)). We obtain aμ(ππ) ≥ 41.8 × 10−9.
123264743
Rigorous sum rules and bounds on pion-pion scattering lengths
Abstract We deduce from axiomatic field theory rigorous sum rules, and upper and lower bounds on S-and P-wave ππ scattering lenghts in terms of physical region forward ππ amplitudes, and also absolute sum rule inequalities on those amplitudes involving pion mass alone.
120093834
Rigorous sum rules and bounds on pion-pion scattering amplitudes with positivity
We derive the complete set of crossing symmetric forward pion-pion amplitudes with non-negative absorptive parts obeying twice-subtracted dispersion relations. We give a method to eliminate subtraction constants for these amplitudes by making a simultaneous use of subtracted dispersion relations for the amplitude and its inverse, and unitarity. We thus deduce from axiomatic field theory (i) lower bounds on forward real parts in terms of physical forward amplitudes, (ii) lower bounds on S- and P-wave scattering lengths in terms of forward amplitudes in any part of the physical region, (iii) sum rules on scattering lengths in terms of physical forward amplitudes which provide a complete test of forward dispersion relations, (iv) upper bounds on scattering lengths in terms of total cross sections and (v) absolute sum rule inequalities on total and forward differential cross sections in terms of the pion mass alone which provide new tests of dispersion relations not involving scattering lengths.