120999991
rho-meson properties in a nonpolynomial Lagrangian theory
Two possible explanations of the existence and the properties of the p meson are analyzed within the framework of the nonpolynomial Lagrangian. It is found that the p meson bootstrapping reciprocally with the B meson in the static Yrcu scattering provides a qualitatively satisfactory description of the p-meson properties. On the other hand, the forces in the 7t. 7). scattering are far too weak to generate the p meson. The calculations are performed within the framework of the N//D method, and are free of a cutoff parameter.
121285502
Nonpolynomial anharmonic oscillator
122881667
Wave functions for weakly coupled bound states
It has been observed' that a short-range attractive potential always produces a bound state in one or two dimensions. This property has been investigated in the weak-coupling limit, with the intention of obtaining perturbative expressions for the bound-state wave functions and energies. In particular, Hausmann has analyzed the bound states in one-dimensional, short-range potentials by using the homogeneous Lippmann-Schwinger equation for the bound-state wave functions. He showed that for the one-dimensional Hamiltonian V(x)~ —ax as x~+ ao, —2
120196663
Dispersion relations for stark energy shifts in hydrogen atom
Abstract On the basis of an approximate but nonperturbative expression for the energy shift δE in the ground state of the hydrogen atom in the presence of an electric field of strength E , we deduce that δE has a branch point at E = 0, and an asymptotic behavior δE → −1 2 E ln E as E → ∞. These properties lead to a twice-subtracted dispersion relation for δE as a function of E . The dispersion relations in conjunction with the WKB approximation and the perturbation series allow us to (i) deduce the large-n behavior of the coefficient of E n in the perturbation series for δE( E ) including 1 n corrections and (ii) obtain the energy shift and the level width of the ground state for a large range of values of E . The agreement with the earlier numerical calculations is very satisfactory.
119717796
A non-polynomial Lee-like model without ghosts
Abstract A Lee-like non-polynomial Lagrangian is discussed. The fourth order calculations in the major coupling, for the propagator function are finite but dominate over the second order terms, asymptotically. This implies that for using non-polynomial Lagrangians at high energy, one must include the higheer order terms in the major coupling. It is shown that the model has no ghosts, but does not satisfy the theorem of Lehmann, Symanzik and Zimmermann.
123365175
A renormalizable theory of weak interactions with a single massive spin-zero charged boson and neutral pseudoscalar hadrons as intermediate bosons
Abstract A renormalizable theory of weak interactions with a single spin-zero charged massive intermediate boson W ± and two charged massive leptons, L e ± , L μ ± is presented. The neutral intermediate boson is taken to be a combination of the usual pseudoscalar hadrons π O , η O and X O . The charged boson couples with unequal strengths to the leptons and octet hadron currents. An universality criterion is presented which enables us to understand this in a natural fashion. It is shown that such a theory is consistent with all the present data if the mass of W ± lies between few GeV and 20 GeV. Finally, some tests of the theory are suggested.
119039401
Exponential Inflation With $\rho = +p$
We introduce in this paper a new framework for obtaining a period of exponential inflation that is entirely driven by the quadratic kinetic energy of a scalar field. In contrast to recent attempts to realize scalar field inflation without potentials (such as k-inflation or ghost inflation), we find that it is possible to obtain exponential inflation, without invoking any higher derivative actions, or modifying gravity, and that unlike all previous approaches, we do not require a $\rho = -p$ phase in order to realize inflation. The inflaton in our proposed framework is a scalar field with a quadratic kinetic energy term, but with the `wrong sign'. We take the perspective that this is due to some temporary instability in our system at high energies, and provide physical examples of situations where a modulus field might temprorarily exhibit such behaviour. The deflation of extra dimensions is a neccesary feature of our framework. However, unlike in previous attempts at Kaluza-Klein inflation, it is possible to obtain exponential (as opposed to power law or pole) inflation. We provide several indications of how one can gracefully exit from this type of inflation.
5431194
Transfer of metric fluctuations when extra dimensions bounce or stabilize
In this report, we study within the context of general relativity with one extra dimension compactified either on a circle or an orbifold, how radion fluctuations interact with metric fluctuations in the three noncompact directions. The background is nonsingular and can either describe an extra dimension on its way to stabilization, or immediately before and after a series of nonsingular bounces. We find that the metric fluctuations transfer undisturbed through the bounces or through the transients of the stabilization epoch. Our background is obtained by considering the effects of a gas of massless string modes in the context of a consistent ``massless background'' (or low energy effective theory) limit of string theory. We discuss applications to various approaches to early universe cosmology, including the ekpyrotic/cyclic universe scenario and string gas cosmology.
16353543
Degravitation, inflation and the cosmological constant as an afterglow
In this report, we adopt the phenomenological approach of taking the degravitation paradigm seriously as a consistent modification of gravity in the IR, and investigate its consequences for various cosmological situations. We motivate degravitation — where Netwon's constant is promoted to a scale dependent filter function — as arising from either a small (resonant) mass for the graviton, or as an effect in semi-classical gravity. After addressing how the Bianchi identities are to be satisfied in such a set up, we turn our attention towards the cosmological consequences of degravitation. By considering the example filter function corresponding to a resonantly massive graviton (with a filter scale larger than the present horizon scale), we show that slow roll inflation, hybrid inflation and old inflation remain quantitatively unchanged. We also find that the degravitation mechanism inherits a memory of past energy densities in the present epoch in such a way that is likely significant for present cosmological evolution. For example, if the universe underwent inflation in the past due to it having tunneled out of some false vacuum, we find that degravitation implies a remnant `afterglow' cosmological constant, whose scale immediately afterwards is parametrically suppressed by the filter scale (L) in Planck units Λ ~ l2pl/L2. We discuss circumstances through which this scenario reasonably yields the presently observed value for Λ ~ O(10−120). We also find that in a universe still currently trapped in some false vacuum state, resonance graviton models of degravitation only degravitate initially Planck or GUT scale energy densities down to the presently observed value over timescales comparable to the filter scale. We argue that different functional forms for the filter function will yield similar conclusions. In this way, we argue that although the degravitation models we study have the potential to explain why the cosmological constant is not large in addition to why it is not zero, it does not satisfactorily address the co-incidence problem without additional tuning.
119086649
Radion stabilization by stringy effects in general relativity
We consider the effects of a gas of closed strings (treated quantum mechanically) on a background where one dimension is compactified on a circle. After we address the effects of a time-dependent background on aspects of the string spectrum that concern us, we derive the energy-momentum tensor for a string gas and investigate the resulting space-time dynamics. We show that a variety of trajectories are possible for the radius of the compactified dimension, depending on the nature of the string gas, including a demonstration within the context of general relativity (i.e. without a dilaton) of a solution where the radius of the extra dimension oscillates about the self-dual radius, without invoking matter that violates the various energy conditions. In particular, we find that in the case where the string gas is in thermal equilibrium, the radius of the compactified dimension dynamically stabilizes at the self-dual radius, after which a period of usual Friedmann-Robertson-Walker cosmology of the three uncompactified dimensions can set in. We show that our radion stabilization mechanism requires a stringy realization of inflation as scalar field driven inflation invalidates our mechanism. We also show that our stabilization mechanism is consistent with observational bounds.
119076672
D0 Matrix Mechanics: Topological Dynamics of Fuzzy Spaces
We consider the physics of a matrix model describing D0-brane dynamics in the presence of an RR flux background. Non-commuting spaces arise as generic soltions to this matrix model, among which fuzzy spheres have been studied extensively as static solutions at finite N. The existence of topologicaly distinct static configurations suggests the possibility of D-brane topology change within this model, however a dynamical solution interpolating between topologies is still somewhat elusive. In this paper, we study this model in the limit of infinite dimensional matrices, where new solutions-- the fuzzy cylinder and the fuzzy plane among them-- appear. We argue that any dynamics which involves topology change will likely only occur in this limit, after which we study the decay of a fuzzy cylinder into an infinite collection of fuzzy spheres as both a classical and a quantum phenomenon. We conclude from this excercise that in certain limits, matrix models offer a viable framework in which to study topological dynamics, and could perhaps be a precursor to a viable theory of space-time topological dynamics.