Common Behaviors of Spinor-Type Instantons in 2D Thirring and 4D Gursey Fermionic Models

We investigate two examples of conformal invariant pure spinor fermionic models, which admit particle-like solutions of the classical field equations. For different dimensions and quantum spinor numbers, the vector field visualizations of the models are constructed to provide a better understanding of the spinor-type instanton dynamics in phase space. The hierarchical cluster analysis method investigations of the models are also presented. Finally, the autocorrelation and power spectrum graphs of models are constructed and frequencies of motions are defined

FRW Cosmology with the Extended Chaplygin Gas

We propose extended Chaplygin gas equation of state for which it recovers barotropic fluid with quadratic equation of state. We use numerical method to investigate the behavior of some cosmological parameters such as scale factor, Hubble expansion parameter, energy density, and deceleration parameter. We also discuss the resulting effective equation of state parameter. Using density perturbations we investigate the stability of the theory

Testing a Dilaton Gravity Model Using Nucleosynthesis

Big bang nucleosynthesis (BBN) offers one of the most strict evidences for the <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi mathvariant="normal">Λ</mi></mrow></math> -CDM cosmology at present, as well as the cosmic microwave background (CMB) radiation. In this work, our main aim is to present the outcomes of our calculations related to primordial abundances of light elements, in the context of higher dimensional steady-state universe model in the dilaton gravity. Our results show that abundances of light elements (primordial D, 3He, 4He, T, and 7Li) are significantly different for some cases, and a comparison is given between a particular dilaton gravity model and <math id="M2" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi mathvariant="normal">Λ</mi></mrow></math> -CDM in the light of the astrophysical observations

Production and Decay of Up-Type and Down-Type New Heavy Quarks through Anomalous Interactions at the LHC

We study the process <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><mi>p</mi><mi>p</mi><mo>→</mo><mi>Q</mi><mi>V</mi><mo>+</mo><mi>X</mi></math> (where <math id="M2" xmlns="http://www.w3.org/1998/Math/MathML"><mi>Q</mi><mo>=</mo><mi>t</mi><mo>,</mo><mi>b</mi></math> and <math id="M3" xmlns="http://www.w3.org/1998/Math/MathML"><mi>V</mi><mo>=</mo><mi>g</mi><mo>,</mo><mi>γ</mi><mo>,</mo></math> and <math id="M4" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Z</mi></mrow></math> ) through the anomalous interactions of the new heavy quarks at the LHC. Considering the present limits on the masses and mixings, the signatures of the heavy quark anomalous interactions are discussed and analysed at the LHC for the center of mass energy of 13 TeV. An important sensitivity to anomalous couplings <math id="M5" xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mrow><mi>κ</mi></mrow><mrow><mi>g</mi></mrow><mrow><msup><mrow><mi>t</mi></mrow><mrow><mi mathvariant="normal">′</mi></mrow></msup></mrow></msubsup><mo>/</mo><mi mathvariant="normal">Λ</mi><mo>=</mo><mn>0.10</mn></math>  TeV−1, <math id="M6" xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mrow><mi>κ</mi></mrow><mrow><mi>γ</mi></mrow><mrow><msup><mrow><mi>t</mi></mrow><mrow><mi mathvariant="normal">′</mi></mrow></msup></mrow></msubsup><mo>/</mo><mi mathvariant="normal">Λ</mi><mo>=</mo><mn>0.14</mn></math>  TeV−1, <math id="M7" xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mrow><mi>κ</mi></mrow><mrow><mi>Z</mi></mrow><mrow><msup><mrow><mi>t</mi></mrow><mrow><mi mathvariant="normal">′</mi></mrow></msup></mrow></msubsup><mo>/</mo><mi mathvariant="normal">Λ</mi><mo>=</mo><mn>0.19</mn></math>  TeV−1 and <math id="M8" xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mrow><mi>κ</mi></mrow><mrow><mi>g</mi></mrow><mrow><msup><mrow><mi>b</mi></mrow><mrow><mi mathvariant="normal">′</mi></mrow></msup></mrow></msubsup><mo>/</mo><mi mathvariant="normal">Λ</mi><mo>=</mo><mn>0.15</mn></math>  TeV−1, <math id="M9" xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mrow><mi>κ</mi></mrow><mrow><mi>Z</mi></mrow><mrow><msup><mrow><mi>b</mi></mrow><mrow><mi mathvariant="normal">′</mi></mrow></msup></mrow></msubsup><mo>/</mo><mi mathvariant="normal">Λ</mi><mo>=</mo><mn>0.19</mn></math>  TeV−1, <math id="M10" xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mrow><mi>κ</mi></mrow><mrow><mi>γ</mi></mrow><mrow><msup><mrow><mi>b</mi></mrow><mrow><mi mathvariant="normal">′</mi></mrow></msup></mrow></msubsup><mo>/</mo><mi mathvariant="normal">Λ</mi><mo>=</mo><mn>0.30</mn></math>  TeV−1 for the mass of 750 GeV of the new heavy quarks <math id="M11" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mrow><mi>t</mi></mrow><mrow><mi mathvariant="normal">′</mi></mrow></msup></mrow></math> and <math id="M12" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mrow><mi>b</mi></mrow><mrow><mi mathvariant="normal">′</mi></mrow></msup></mrow></math> can be reached for an integrated luminosity of <math id="M13" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>L</mi></mrow><mrow><mtext>int</mtext></mrow></msub><mo>=</mo><mn>100</mn></math>  fb−1

On the breakdown of the curvature perturbation ζ during reheating

It is known that in single scalar field inflationary models the standard curvature perturbation ζ, which is supposedly conserved at superhorizon scales, diverges during reheating at times 0ϕ̇=, i.e. when the time derivative of the background inflaton field vanishes. This happens because the comoving gauge 0φ=, where φ denotes the inflaton perturbation, breaks down when 0ϕ̇=. The issue is usually bypassed by averaging out the inflaton oscillations but strictly speaking the evolution of ζ is ill posed mathematically. We solve this problem in the free theory by introducing a family of smooth gauges that still eliminates the inflaton fluctuation φ in the Hamiltonian formalism and gives a well behaved curvature perturbation ζ, which is now rigorously conserved at superhorizon scales. At the linearized level, this conserved variable can be used to unambiguously propagate the inflationary perturbations from the end of inflation to subsequent epochs. We discuss the implications of our results for the inflationary predictions

More on loops in reheating: non-gaussianities and tensor power spectrum

We consider the single field chaotic m2ϕ2 inflationary model with a period of preheating, where the inflaton decays to another scalar field χ in the parametric resonance regime. In a recent work, one of us has shown that the χ modes circulating in the loops during preheating notably modify the ⟨ζζ⟩ correlation function. We first rederive this result using a different gauge condition hence reconfirm that superhorizon ζ modes are affected by the loops in preheating. Further, we examine how χ loops give rise to non-gaussianity and affect the tensor perturbations. For that, all cubic and some higher order interactions involving two χ fields are determined and their contribution to the non-gaussianity parameter fNL and the tensor power spectrum are calculated at one loop. Our estimates for these corrections show that while a large amount of non-gaussianity can be produced during reheating, the tensor power spectrum receive moderate corrections. We observe that the loop quantum effects increase with more χ fields circulating in the loops indicating that the perturbation theory might be broken down. These findings demonstrate that the loop corrections during reheating are significant and they must be taken into account for precision inflationary cosmology

A semiclassical kinetic theory of Dirac particles and Thomas precession

Kinetic theory of Dirac fermions is studied within the matrix valued differential forms method. It is based on the symplectic form derived by employing the semiclassical wave packet build of the positive energy solutions of the Dirac equation. A satisfactory definition of the distribution matrix elements imposes to work in the basis where the helicity is diagonal which is also needed to attain the massless limit. We show that the kinematic Thomas precession correction can be studied straightforwardly within this approach. It contributes on an equal footing with the Berry gauge fields. In fact in equations of motion it eliminates the terms arising from the Berry gauge fields

Semileptonic Bs→Ds2∗(2573)ℓν¯ℓ transition in QCD

We analyze the semileptonic Bs→Ds2∗(2573)ℓν¯ℓ transition, where ℓ=τ,μ or e , within the standard model. We apply the QCD sum rule approach to calculate the transition form factors entering the low energy Hamiltonian defining this channel. The fit functions of the form factors are used to estimate the total decay widths and branching fractions in all lepton channels. The orders of the branching ratios indicate that this transition is accessible at LHCb in the near future

Superradiance and black hole bomb in five-dimensional minimal ungauged supergravity

We examine the black hole bomb model which consists of a rotating black hole of five-dimenensional minimal ungauged supergravity and a reflecting mirror around it. For low-frequency scalar perturbations, we find solutions to the Klein-Gordon equation in the near-horizon and far regions of the black hole spacetime. To avoid solutions with logarithmic terms, we assume that the orbital quantum number l takes on nearly, but not exactly, integer values and perform the matching of these solutions in an intermediate region. This allows us to calculate analytically the frequency spectrum of quasinormal modes, taking the limits as l approaches even or odd integers separately. We find that all l modes of scalar perturbations undergo negative damping in the regime of superradiance, resulting in exponential growth of their amplitudes. Thus, the model under consideration would exhibit the superradiant instability, eventually behaving as a black hole bomb in five dimensions

Analysis of the strong D2∗(2460)0→D+π- and Ds2∗(2573)+→D+K0 transitions via QCD sum rules

The strong D2∗(2460)0→D+π- and Ds2∗(2573)+→D+K0 transitions are analyzed via three-point QCD sum rules. First we calculate the corresponding strong coupling constants gD2∗Dπ and gDs2∗DK . Then we use them to calculate the corresponding decay widths and branching ratios. Making use of the existing experimental data on the ratio of the decay width in the pseudoscalar D channel to that of the vector D∗ channel, finally, we estimate the decay width and branching ratio of the strong D2∗(2460)0→D∗(2010)+π- transition