scholarly journals Spillway preheating

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
JiJi Fan ◽  
Kaloian D. Lozanov ◽  
Qianshu Lu
Keyword(s):  
Energy Density ◽  
Particle Physics ◽  
Particle Production ◽  
Model Building ◽  
Resonance Production ◽  
Production Mechanism ◽  
Efficient Energy ◽  
Inverse Power Law ◽  
Dissipation Mechanism ◽  
Resonant Production

Abstract In traditional models only an order one fraction of energy is transferred from the inflaton to radiation through nonperturbative resonance production in preheating immediately after inflation, due to backreaction effects. We propose a particle production mechanism that could improve the depletion of the inflaton energy density by up to four orders of magnitude. The improvement comes from the fast perturbative decays of resonantly produced daughter particles. They act as a “spillway” to drain these daughter particles, reducing their backreaction on the inflaton and keeping the resonant production effective for a longer period. Thus we dub the scenario “spillway preheating”. We also show that the fraction of energy density remaining in the inflaton has a simple inverse power-law scaling in the scenario. In general, spillway preheating is a much more efficient energy dissipation mechanism, which may have other applications in model building for particle physics.

scholarly journals Heterotic line bundle models on generalized complete intersection Calabi Yau manifolds

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Magdalena Larfors ◽  
Davide Passaro ◽  
Robin Schneider
Keyword(s):  
Line Bundle ◽  
Complete Intersection ◽  
Particle Physics ◽  
Model Building ◽  
Wilson Line ◽  
Symmetry Groups ◽  
The Standard Model ◽  
Order Of Magnitude ◽  
Systematic Program ◽  
Calabi Yau Manifolds

Abstract The systematic program of heterotic line bundle model building has resulted in a wealth of standard-like models (SLM) for particle physics. In this paper, we continue this work in the setting of generalised Complete Intersection Calabi Yau (gCICY) manifolds. Using the gCICYs constructed in ref. [1], we identify two geometries that, when combined with line bundle sums, are directly suitable for heterotic GUT models. We then show that these gCICYs admit freely acting ℤ2 symmetry groups, and are thus amenable to Wilson line breaking of the GUT gauge group to that of the standard model. We proceed to a systematic scan over line bundle sums over these geometries, that result in 99 and 33 SLMs, respectively. For the first class of models, our results may be compared to line bundle models on homotopically equivalent Complete Intersection Calabi Yau manifolds. This shows that the number of realistic configurations is of the same order of magnitude.

No-scale supergravity inflation: A bridge between string theory and particle physics?

2016 ◽  
Vol 25 (14) ◽  
pp. 1630027 ◽  
Author(s):  
John Ellis
Keyword(s):  
Supergravity Models ◽  
String Theory ◽  
Effective Potential ◽  
Particle Physics ◽  
Model Building ◽  
Inflationary Model ◽  
New Wave ◽  
Microwave Background ◽  
Supergravity Theory ◽  
Text Model

The plethora of recent and forthcoming data on the cosmic microwave background (CMB) data are stimulating a new wave of inflationary model-building. Naturalness suggests that the appropriate framework for models of inflation is supersymmetry. This should be combined with gravity in a supergravity theory, whose specific no-scale version has much to commend it, e.g. its derivation from string theory and the flat directions in its effective potential. Simple no-scale supergravity models yield predictions similar to those of the Starobinsky [Formula: see text] model, though some string-motivated versions make alternative predictions. Data are beginning to provide interesting constraints on the rate of inflaton decay into Standard Model particles. In parallel, LHC and other data provide significant constraints on no-scale supergravity models, which suggest that some sparticles might have masses close to present experimental limits.

Recent developments of Co3O4-based materials as the catalysts for oxygen evolution reaction

2021 ◽  
Author(s):  
Zhenyu Hu ◽  
Liping Hao ◽  
Fan Quan ◽  
Rui Guo
Keyword(s):  
Energy Density ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Fossil Fuels ◽  
High Energy ◽  
High Energy Density ◽  
Environmental Concerns ◽  
Efficient Energy ◽  
Recent Developments

The demand for the development of clean and efficient energy is becoming more and more pressing due to depleting fossil fuels and environmental concerns. Hydrogen is a high energy density...

scholarly journals Geography of fields in extra dimensions: String theory lessons for particle physics

2015 ◽  
Vol 30 (10) ◽  
pp. 1530008 ◽  
Author(s):  
Hans Peter Nilles ◽  
Patrick K. S. Vaudrevange
Keyword(s):  
String Theory ◽  
Particle Physics ◽  
Extra Dimensions ◽  
Model Building ◽  
Unified Theory ◽  
Fundamental Interactions ◽  
Spatial Dimensions ◽  
Physics Model ◽  
String Theories

String theoretical ideas might be relevant for particle physics model building. Ideally one would hope to find a unified theory of all fundamental interactions. There are only a few consistent string theories in D = 10 or 11 spacetime dimensions, but a huge landscape in D = 4. We have to explore this landscape to identify models that describe the known phenomena of particle physics. Properties of compactified six spatial dimensions are crucial in that respect. We postulate some useful rules to investigate this landscape and construct realistic models. We identify common properties of the successful models and formulate lessons for further model building.

Some general properties of radiation processes as related to "secondary" cosmic rays

1968 ◽  
Vol 46 (10) ◽  
pp. S1003-S1005 ◽  
Author(s):  
Frank C. Jones
Keyword(s):  
Cosmic Rays ◽  
Electron Energy ◽  
Power Law ◽  
Particle Production ◽  
Inverse Power ◽  
Characteristic Energy ◽  
Inverse Compton Scattering ◽  
Inverse Power Law ◽  
Radiation Processes ◽  
The Individual

The individual processes of synchrotron radiation and inverse Compton scattering produce quite different photon spectra for electrons of a given energy. However, an inverse power-law spectrum of electrons, j(γ) = k′γ−m, will produce a photon spectrum N(α) = Kα−(m+1)/2 for either process. The explanation for this lies in the fact that both individual radiation processes produce spectra of the form N(α) = F(αc/αc)(αc)−n where the characteristic energy αc is proportional to some power of the electron energy and contains all of the dependence on the electron energy that the spectrum exhibits. This form of the spectrum coupled with an inverse power-law electron spectrum produces the desired result. An investigation reveals that other radiation and secondary particle production processes possess this form of spectrum. This gives a very general explanation for the well-known fact that secondary particles, even those several generations removed from the primary cosmic rays, exhibit inverse power-law spectra.

scholarly journals DISSIPATIVE HYDRODYNAMICS IN 2 + 1 DIMENSIONS

2007 ◽  
Vol 16 (07n08) ◽  
pp. 2325-2331
Author(s):  
A. K. CHAUDHURI
Keyword(s):  
Energy Density ◽  
Viscous Fluid ◽  
Shear Viscosity ◽  
Ideal Fluid ◽  
Particle Production ◽  
Elliptic Flow ◽  
Order Theory ◽  
First Order ◽  
First Order Theory ◽  
Hydrodynamic Evolution

In a first order theory of dissipative hydrodynamics, we have simulated hydrodynamic evolution of QGP fluid with dissipation due to shear viscosity only. Simulation confirms that compared to an ideal fluid, energy density or temperature of a viscous fluid evolve slowly. Transverse expansion is also more in viscous fluid. We also study the effect of viscosity on particle production. Particle production is enhanced, more at large pT. The elliptic flow on the otherhand decreases and shows a tendency to saturate at large pT.

scholarly journals A New Unified Electro-Gravity Theory for the Electron

2019 ◽  
Author(s):  
Nirod Das
Keyword(s):  
Energy Density ◽  
Electric Field ◽  
Particle Physics ◽  
Order Approximation ◽  
Structure Constant ◽  
Stable Solution ◽  
Fine Structure Constant ◽  
Mass Energy ◽  
Dimensionless Constant ◽  
Static Electron

A rigorous model for an electron is presented by generalizing the Coulomb's Law or Gauss's Law of electrostatics, using a unified theory of electricity and gravity. The permittivity of the free-space is allowed to be variable, dependent on the energy density associated with the electric field at a given location, employing generalized concepts of gravity and mass/energy density. The electric field becomes a non-linear function of the source charge, where concept of the energy density needs to be properly defined. Stable solutions are derived for a spherically symmetric, surface-charge distribution of an elementary charge. This is implemented by assuming that the gravitational field and its equivalent permittivity function is proportional to the energy density, as a simple first-order approximation, with the constant of proportionality referred to as the Unifield Electro-Gravity (UEG) constant. The stable solution with the lowest mass/energy is assumed to represent a ``static'' electron without any spin. Further, assuming that the mass/energy of a static electron is half of the total mass/energy of an electron including its spin contribution, the required UEG constant is estimated. More fundamentally, the lowest stable mass of a static elementary charged particle, its associated classical radius, and the UEG constant are related to each other by a dimensionless constant, independent of any specific value of the charge or mass of the particle. This dimensionless constant is numerologically suspected to be closely related to the the fine structure constant. This finding may carry greater fundamental significance, with scope of the UEG theory covering other elementary particles in the standard model of particle physics.

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