A Quantum Field Theory Warm Inflation Model
A quantum field theory warm inflation model is presented that solves the cosmological horizon/flatness problems. An interpretation of the model is given from supersymmetry and superstring theory.
hep-ph↗
arXiv subjects
Arjun Berera
Publications and source records attributed to Arjun Berera.
GUT Cosmic Magnetic Fields in a Warm Inflationary Universe
Sources of magnetic fields from grand unified theories are studied in the warm inflation regime. A ferromagnetic Savvidy vacuum scenario is presented that yields observationally interesting large scale magnetic fields. As an intermediate step, a general analysis is made of defect production at the onset of warm inflation and monopole constraints are obtained. Many features of this Savvidy vacuum scenario are applicable within a supercooled inflation regime and these points are discussed.
hep-ph↗
Strong Dissipative Behavior in Quantum Field Theory
We study under which conditions an overdamped regime can be attained in the dynamic evolution of a quantum field configuration. Using a real-time formulation of finite temperature field theory, we compute the effective evolution equation of a scalar field configuration, quadratically interacting with a given set of other scalar fields. We then show that, in the overdamped regime, the dissipative kernel in the field equation of motion is closely related to the shear viscosity coefficient, as computed in scalar field theory at finite temperature. The effective dynamics is equivalent to a time-dependent Ginzburg-Landau description of the approach to equilibrium in phenomenological theories of phase transitions. Applications of our results, including a recently proposed inflationary scenario called ``warm inflation'', are discussed.
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Factorization and Non-factorization in Diffractive Hard Scattering
Factorization, in the sense defined for inclusive hard scattering, is discussed for diffractive hard scattering. A factorization theorem similar to its inclusive counterpart is presented for diffractive DIS. For hadron-hadron diffractive hard scattering, in contrast to its inclusive counterpart, the expected breakdown of factorization is discussed. Cross section estimates are given from a simple field theory model for non-factorizing double-pomeron-exchange (DPE) dijet production with and without account for Sudakov suppression.
hep-ph↗
$K_L \to π^o ν\barν$ in the Aspon Model
An attractive alternative to the standard model of CP violation is the aspon model. In this model, CP is spontaneously broken, automatically solving the strong CP problem. Recently, it has been shown that CP violation in the B system is much smaller in the aspon model than in the standard model. Here we provide a complementary study by considering $K_L\to π^oν\barν$, which is almost entirely CP violating and free of hadronic uncertainties, and show that the rate in the aspon model is many orders of magnitude below the standard model rate. Observation of $K_L\to π^oν\barν$ would rule out the aspon model.
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An Attempt to Determine the Largest Scale of Primordial Density Perturbations in the Universe
Inflationary cosmology predicts that the particle horizon should be generically much bigger than the present-day Hubble radius, $1/H_0$. This implies a special regime of super-Hubble scale energy density fluctuations imprinted on the cosmic microwave background radiation (CMBR), which from present theory could only be explained by inflation Causality constraints are used to determine models for the power spectrum that accommodate a suppression scale. A three parameter likelihood analysis is performed of the COBE-DMR 4-year data with respect to the amplitude, spectral index, and suppression scale. It is found that all suppression length scales larger than $1/H_0$ are consistent with the data, but that scales of order $1/H_0$ are slightly preferred, at roughly the one-sigma level. Many non-inflation models would be consistent with a small suppression length scale, whereas for standard inflation models, the duration of the inflation epoch would have to be bounded by a fairly small upper limit. Suppression scales smaller than $1/H_0$ are strongly excluded by the anisotrophy data.
astro-ph↗
Jet Production Cross Section with Double Pomeron Exchange
I will discuss hadron-hadron collisions where the final state is kinematically of the kind associated with double-pomeron-exchange (DPE) and has large transverse momentum jets. I will show that in addition to the conventional factorized (FDPE) contribution, there is a non-factorized (NDPE) contribution which has no pomeron beam jet. Results of calculations from a simple model of DPE for two-jet total and differential cross sections at Tevatron energy scales are presented. The NDPE contribution is dominant.
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Interpolating the Stage of Exponential Expansion in the Early Universe: a possible alternative with no reheating
In the standard picture, the inflationary universe is in a supercooled state which ends with a short time, large scale reheating period, after which the universe goes into a radiation dominated stage. An alternative is proposed here in which the radiation energy density smoothly decreases all during an inflation-like stage and with no discontinuity enters the subsequent radiation dominated stage. The scale factor is calculated from standard Friedmann cosmology in the presence of both radiation and vacuum energy density. A large class of solutions confirm the above identified regime of non-reheating inflation-like behavior for observationally consistent expansion factors and not too large a drop in the radiation energy density. One dynamical realization of such inflation without reheating is from warm inflation type scenarios. However the solutions found here are properties of the Einstein equations with generality beyond slow-roll inflation scenarios. The solutions also can be continuously interpolated from the non-reheating type behavior to the standard supercooled limit of exponential expansion, thus giving all intermediate inflation-like behavior between these two extremes. The temperature of the universe and the expansion factor are calculated for various cases. Implications for baryongenesis are discussed. This non-reheating, inflation-like regime also appears to have some natural features for a universe that is between nearly flat and open.
hep-ph↗
Diffractive Factorization - a Simple Field Theory Model for $F_2^{diff}(βx_{\pom}, Q^2; x_{\pom},t)$
Operator definitions of diffractive parton distribution functions are given. A distinction is made between the special case of ``Regge factorization'' to the general case of ``diffractive factorization'' with explicit expressions for $F_2^{diff}(βx_{\pom}, Q^2;x_{\pom},t)$ in both cases. A calculation from a simple field theory model is presented in the style of ``constituent counting rules'' for the behavior of the diffractive parton distribution functions when $β\rightarrow 1$, which corresponds to when the detected parton carries almost all of the longitudinal momentum transferred from the scattered hadron. A comment is made about the consistency of the model with the observed flattening of $n(β)$ as $β\rightarrow 1$, which recently was reported by the H1-collaboration from their preliminary 1994 data.
hep-ph↗
Thermal Properties of an Inflationary Universe
An energetic justification of a thermal component during inflation is given. The thermal component can act as a heat reservoir which induces thermal fluctuations on the inflaton field system. We showed previously that such thermal fluctuations could dominate quantum fluctuations in producing the initial seeds of density perturbations. A Langevin-like rate equation is derived from quantum field theory which describes the production of fluctuations in the inflaton field when acted upon by a simple modeled heat reservoir. In a certain limit this equation is shown to reduce to the standard Langevin equation, which we used to construct "Warm Inflation" scenarios in previous work. A particle physics interpretation of our system-reservoir model is offered.
hep-th↗
Double Pomeron Jet Cross Sections
We treat hadron-hadron collisions where the final state is kinematically of the kind associated with double-pomeron-exchange (DPE) and has large transverse momentum jets. We show that in addition to the conventional factorized (FDPE) contribution, there is a non-factorized (NDPE) contribution which has no pomeron beam jet. Within a simple model we compute DPE-two-jet total and differential cross sections at Tevatron energy scales, and show that the NDPE contribution is dominant.
hep-ph↗
Warm Inflation
Assuming a first order phase transition during inflation, a model scenario is described which does not require a tiny coupling constant. Thermal equilibrium is closely maintained as inflation commences. No large scale reheating is necessary. Solutions for $N> 70$ are found for any $δρ/ ρ$ in the range $10^{-5} - 10^{-3}$.
astro-ph↗
Behavior of Diffractive Parton Distribution Functions
Diffractive parton distribution functions give the probability to find a parton in a hadron if the hadron is diffractively scattered. We provide an operator definition of these functions and discuss their relation to diffractive deeply inelastic scattering and to photoproduction of jets at HERA. We perform a calculation in the style of ``constituent counting rules'' for the behavior of these functions when the detected parton carries almost all of the longitudinal momentum transferred from the scattered hadron.
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Thermally Induced Density Perturbations in the Inflation Era
The possibility of thermally induced initial density perturbations in inflationary cosmology is examined. The fluctuation dynamics of a scalar field plus thermal bath system during slow roll is described by a Langevin-like equation. Fluctuation-dissipation arguments show that for a wide parameter range within the standard inflation model, the thermal fluctuations of the scalar field can dominate its quantum fluctuations. The initial amplitude of density perturbations is found to lie in a range which is consistent with the recent observations of cosmic temperature fluctuations.
astro-ph↗
A Property of Recombination in Polarized Hadronic Targets
The triple gluon-ladder vertex is shown to project the outgoing gluon in either polarization state with equal probability up to the leading double-ln(x)ln($Q^2$) approximation. This implies that the $Q^2$-evolution of $ΔG (x, Q^2)$ is free from recombination effects to this level of approximation.
hep-ph↗
Wave Function Properties in a High Energy Process
A model example is given of how properties of the hadronic light-cone wave function are revealed in a particular high energy process. The meson wave function is derived in scalar quark QCD. We apply it to compute the form of the cross section for lossless diffractive jet-production, an upcoming possiblity at HERA.
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Second-Order Scaling in the Two-Flavor QCD Chiral Transition
Scaling behavior is analyzed for the two-flavor QCD lattice gauge theory chiral transition. Leading scaling behavior and correction to leading scaling from lattice spacing effects are examined for the quark condensate. Scaling predictions under the assumption of quark mass dominance are tested for the longitudinal correlation length. Second order scaling behavior is consistent with present data.
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