Found 1170 results, showing the newest relevant preprints. Sort by relevancy only.Update me on new preprints

Hadamard renormalization for a charged **scalar** **field**

These results will have applications in the computation of renormalized expectation values for a charged quantum

**scalar****field**on a charged black hole space-time, and hence in addressing issues such as the quantum stability of the inner horizon. Expand abstract. The Hadamard representation of the Green's function of a quantum

**field**on a curved space-time is a powerful tool for computations of renormalized expectation values. We study the Hadamard form of the Feynman Green's function for a massive charged complex**scalar****field**in an arbitrary number of space-time dimensions. Explicit expressions for the coefficients in the Hadamard parametrix are given for two, three and four space-time dimensions. We then develop the formalism for the Hadamard renormalization of the expectation values of the**scalar****field**condensate, current and stress-energy tensor. These results will have applications in the computation of renormalized expectation values for a charged quantum**scalar****field**on a charged black hole space-time, and hence in addressing issues such as the quantum stability of the inner horizon.6 days ago

10/10 relevant

arXiv

10/10 relevant

arXiv

Running Vacuum from Dynamical Spacetime Cosmology

The Running Vacuum Model (RVM) has been a candidate to solve the tension between the Hubble constant from the early and the late universe data fit. Expand abstract.

The Running Vacuum Model (RVM) has been a candidate to solve the tension between the Hubble constant from the early and the late universe data fit. However the model does consider a Lagrangian formulation directly. In this paper we formulate an action principle that approaches the RMV from the second type, with a

**scalar****field**model for the whole dark components. The dynamical space time vector**field**$\chi_\mu$ is used as a Lagrange multiplier that forces the kinetic term of the**scalar****field**to evaluates as the modified dark matter component from the RMV model. When we replace the vector**field**to a derivative of a scalar, the model predicts diffusion interactions between the dark components and the cosmological solution have a different correspondence to the RMV. All of these new solutions yield new cosmological scenarios that should be studied in detail in the future.6 days ago

4/10 relevant

arXiv

4/10 relevant

arXiv

Resonant frequencies of a massless **scalar** **field** in the canonical
acoustic black hole

In this letter we consider the exact solution of the Klein-Gordon equation describing a massless

**scalar****field**in the spacetime of a four dimensional canonical acoustic black hole, which is given in terms of the general Heun function, to discuss the interesting phenomena related to the resonant frequencies. Expand abstract. In this letter we consider the exact solution of the Klein-Gordon equation describing a massless

**scalar****field**in the spacetime of a four dimensional canonical acoustic black hole, which is given in terms of the general Heun function, to discuss the interesting phenomena related to the resonant frequencies.7 days ago

10/10 relevant

arXiv

10/10 relevant

arXiv

Strong cosmic censorship in de Sitter space: As strong as ever

We have performed the full non-linear evolution of the massless charged

**scalar****field**minimally coupled to the Einstein-Maxwell system in de Sitter space, and found that the non-linear effect can restore the strong cosmic censorship, making it as strong as ever. Expand abstract. The strong cosmic censorship has recently been put into question for the charged black holes in de Sitter space. We have performed the full non-linear evolution of the massless charged

**scalar****field**minimally coupled to the Einstein-Maxwell system in de Sitter space, and found that the non-linear effect can restore the strong cosmic censorship, making it as strong as ever.11 days ago

4/10 relevant

arXiv

4/10 relevant

arXiv

Deformed general relativity

I firstly find the minimally-deformed model for a

**scal**ar-tensor theory, thereby establishing a classical reference point, and investigate the cosmological effects of a non-minimal coupled**scalar****field**. Expand abstract. In this thesis, I investigate how to construct a self-consistent model of deformed general relativity using canonical methods and metric variables. The specific deformation of general covariance is predicted by some studies into loop quantum cosmology. I firstly find the minimally-deformed model for a

**scalar**-tensor theory, thereby establishing a classical reference point, and investigate the cosmological effects of a non-minimal coupled**scalar****field**. By treating the deformation perturbatively, I derive the deformed gravitational action which includes the nearest order of curvature corrections. Then working more generally, I derive the deformed**scalar**-tensor constraint to all orders and I find that the momenta and spatial derivatives from gravity and matter must combine in a very specific form. It suggests that the deformation should be equally affected by matter**field**derivatives as it is by gravitational curvature. Finally, I derive the deformed gravitational action to all orders, and find how intrinsic and extrinsic curvatures differently affect the deformation. The deformation seems to be required to satisfy a non-linear equation usually found in fluid mechanics.11 days ago

4/10 relevant

arXiv

4/10 relevant

arXiv

Quantum aspects of Yukawa model with **scalar** and axial **scal**ar **fields** in
curved spacetime

We study the Yukawa model with one scalar and one axial scalar fields, coupled to $N$ copies of Dirac fermions, in curved spacetime background. Expand abstract.

We study the Yukawa model with one

**scalar**and one axial**scalar**fields, coupled to $N$ copies of Dirac fermions, in curved spacetime background. The theory possesses a reach set of coupling constants, including the**scalar**terms with odd powers of**scalar****fields**in the potential, and constants of non-minimal coupling of the**scalar****fields**to gravity. Using the heat-kernel technique and dimensional regularization, we derive the one-loop divergences, describe the renormalization of the theory under consideration and calculate the full set of beta- and gamma-functions for all coupling constants and**fields**. As a next step, we construct the renormalized one-loop effective potential of the**scalar****fields**up to the terms linear in**scalar**curvature. This calculation includes only the contributions from quantum**scalar**fields, and is performed using covariant cut-off regularization and local momentum representation. Some difficulties of the renormalization group approach to the effective potential in the case under consideration are discussed.11 days ago

10/10 relevant

arXiv

10/10 relevant

arXiv

Quasinormal modes of magnetized black hole

We investigate charged, massive scalar field around static, spherically symmetric black hole immersed into an external asymptotically uniform magnetic field $B$. Expand abstract.

We investigate charged, massive

**scalar****field**around static, spherically symmetric black hole immersed into an external asymptotically uniform magnetic**field**$B$. It is shown that for given multipole number $\ell$ there are $2\ell+1$ numbers of modes due to the Zeeman effect appearing by an interaction of the external magnetic and charged**scalar****fields**introducing an effective mass of the**scalar****field**$\mu_{\rm eff}=\sqrt{\mu^2-mqB}$ where $m$ is the azimuthal number and $q$ is the charge coupling constant. We calculate threshold value of effective mass in which quasinormal modes are arbitrarily long lived and beyond that value quasinormal modes vanish. In the case of $m qB12 days ago

8/10 relevant

arXiv

8/10 relevant

arXiv

Locally contorted space-time invokes inflation, dark energy, and a non-singular Big Bang

The cosmological impact of the Covariant Canonical Gauge Theory of Gravity is investigated. Expand abstract.

The cosmological impact of the Covariant Canonical Gauge Theory of Gravity is investigated. We deduce that, in a metric compatible geometry, the requirement of covariant conservation of matter invokes torsion of space-time. In the Friedman model this leads to a

**scalar****field**built from contortion and the metric with the property of dark energy, which transforms the cosmological constant to a time-dependent function. Moreover, the quadratic Rieman-Cartan term in the CCGG**field**equations adds a geometrical curvature correction to the Friedman equations. Applying the standard $\Lambda$CDM parameter set, those equations give a unique solution for the cosmological**field**. With a relatively small "deformation" parameter of the theory that determines the strength of the quadratic term and thus the deviation from the Einstein-Hilbert theory, the resulting evolution of the universe starts from a finite extension, undergoes a violent, Big Bang-like, or a smooth and slow bounce process followed by an inflation phase, and exits gracefully to the current dark energy era. The calculations of the SNeIa Hubble diagram and of the most recent transition point from deceleration to acceleration compare well with astronomical observations. The theory also provides a new handle to resolving the cosmological constant problem.12 days ago

4/10 relevant

arXiv

4/10 relevant

arXiv

Adiabatic regularization and Green's function of massless **scalar** **field**
in general RW spacetimes

We study adiabatic regularization of a coupling massless

**scalar****field**in general spatially flat Robertson-Walker (RW) spacetimes. Expand abstract. We study adiabatic regularization of a coupling massless

**scalar****field**in general spatially flat Robertson-Walker (RW) spacetimes. For the conformally-coupling, the 2nd-order regularized power spectrum and 4th-order regularized stress tensor are zero, and no trace anomaly exists in general RW spacetimes. This is an extension of our previous result in de Sitter space. For the minimally-coupling, the regularized spectra are also zero in the radiation-dominant stage, the matter-dominant stage, and de Sitter space as well. The vanishing of these adiabatically regularized spectra are also confirmed by direct regularization of the Green's functions. For a general coupling and general RW spacetimes, the regularized spectra can be negative under the conventional prescription. By going to higher order of regularization, the spectra will generally become positive, but will also acquire IR divergence which is inevitable for a massless**field**. To avoid the IR divergence, the inside-horizon regularization is applied. By these procedures, one will eventually achieve nonnegative, UV- and IR-convergent power spectrum and spectral energy density.17 days ago

10/10 relevant

arXiv

10/10 relevant

arXiv

A duality of **scalar** **fields**: General results

A duality among

**scalar****fields**is revealed. If two**fields**are dual to each other, the solutions of their**field**equations are related by a duality transform. That is, once the solution of a**field**equation is known, the solution of the dual**field**can be obtained by the duality transform. A**scalar****field**has a series of dual fields, forming a duality family. Once the solution of a**field**in the duality family is solved, the solutions of all other**fields**in the family are given by the duality transform. That is, a series of exactly solvable model can be constructed from one exactly solvable model. The dual**field**of the sine-Gordon field, the sinh-Gordon field, the power-introduction field, etc., are considered as examples.19 days ago

9/10 relevant

arXiv

9/10 relevant

arXiv