arXiv subjects

Hamidreza Daniali

Publications and source records attributed to Hamidreza Daniali.

10 recordsLinked to original sources

arXiv2026

Dressed D-strings with Instability and Transverse Rotation: The Open String Pair Production

Motivated by the Schwinger effect in the QED, we investigate the open string pair creation for the dressed D1-branes, incorporating electric and tachyonic fields and also transverse rotation in the presence of the antisymmetric (Kalb-Ramond) background field. The background spacetime is partially compact on a torus. Our first observation is that the presence of the tachyonic field together with the transverse rotation prevents the open string production. Consequently, we shall quench the tachyonic field. Thus, we find that the pair creation arises only when the angular frequencies of the D-strings satisfy a rational relation. Besides, we observe that the compactification enhances the production rate of the open strings. Finally, we study various special cases of the system.

hep-th↗

arXiv2025

Relativistic Magnetohydrodynamic Wave Excitation by Laser Pulse in a Magnetized Plasma

In the study of plasma, particularly in applications involving strong laser-plasma interactions, the propagation of a strong electromagnetic wave induces relativistic velocities in the electron flow. Given such conditions, the wave propagating through the plasma experiences modulational instability. In this paper, we investigate this instability using magnetohydrodynamic (MHD) equations. In the relativistic limit, the motion of ions can be neglected due to their significant inertia, allowing us to treat the ions as a background fluid. This simplification enables us to apply perturbation techniques to the electron fluid equations, leading to the derivation of the nonlinear wave equation in the form of the Nonlinear Schrödinger Equation (NLSE). We also explore the relationship between wave dispersion and the conditions for instability. We derive the maximum growth rate of the modulational instability and analyze its dependence on plasma parameters and wave intensity in the context of relativistic magnetized plasma, providing quantitative insights into the instability dynamics. Finally, we examine aspects of the perturbed NLSE using the Bogoliubov-Mitropolsky perturbation approach, treating real and imaginary coefficients separately, which explicitly incorporates both Nonlinear Landau Damping (NLLD) and growth-damping effects.

physics.plasm-ph↗

arXiv2024

LREE of a Dressed D$p$-brane with Transverse Motion in the Partially Compact Spacetime

In the context of the type IIA/IIB superstring theories, we derive the left-right entanglement entropy (LREE) of a BPS D$p$-brane with transverse motion in the presence of a $U(1)$ gauge potential and the Kalb-Ramond field in the partially compact spacetime $\mathbf{T}^n \otimes \mathbb R^{1,9-n}$. At first we employ the replica trick to compute the Rényi entropy and then we obtain the entanglement entropy. We examine the results for the special case, i.e. for the D6-brane. Besides, we investigate the thermodynamical entropy, associated with the LREE. This demonstrates that the LREE is precisely equivalent to its thermodynamic counterpart.

hep-th↗

arXiv2023

Thermodynamics and Tachyon Condensation of the Dressed-Dynamical Unstable D$p$-branes

Using the boundary state formalism and thermo field dynamics approach, we study a D$p$-brane at finite temperature in which the background Kalb-Ramond field, a $U(1)$ gauge potential, and tachyon field are turned on together with a general tangential dynamics. The thermal entropy of the brane will be studied. In addition, the behavior of the entropy after the tachyon condensation process will be investigated and some thermodynamic interpretations will be extracted.

hep-th↗

arXiv2023

Open String Pair Production from the Interacting Dressed-Angled D-Strings

We calculate the rate of the open string pair production from the interaction of two non-intersecting D-strings at angle. The D-strings have been equipped with the $U(1)$ gauge potentials in the presence of the Kalb-Ramond field. This rate will be discussed when the D-strings intersect each other. Our computations is in the framework of the bosonic string theory.

hep-th↗

arXiv2023

Closed String Radiation from the Interaction of the Moving D$p$-branes with Background Fields

At first, we derive a boundary state, associated with a moving D$p$-brane, in the presence of the Kalb-Ramond field and a $U(1)$ gauge potential. Then, from the interaction of such D$p$-branes, we obtain the radiation amplitude for a massless closed string. The behavior of the radiation amplitude for the large distance of the branes will be studied. Our calculations is in the framework of the bosonic string theory.

hep-th↗

arXiv2022

Radiation of a Massless Closed String from Interacting D$p$-branes with Background Fields in the Superstring Theory

In the context of the superstring theory, we calculate the radiation amplitude of a general massless closed string from the interaction of two parallel D$p$-branes. The background field is the constant antisymmetric tensor $B_{μν}$, and the branes have been equipped with the different $U(1)$ gauge fields. For the large distance of the branes, the Kalb-Ramond emission will be investigated.

hep-th↗

arXiv2022

Closed String Radiation from the Interacting Fractional-Dressed D$p$-Branes with the Transverse Motions

We determine the boundary states, associated with a fractional D$p$-brane in the presence of the Kalb-Ramond field and a $U(1)$ gauge potential. The background spacetime is the non-compact orbifold $ \mathbb{R}^{1, 21} \otimes \mathbb{R}^4/ \mathbb{Z}_2$. Besides, the brane has a transverse velocity. We compute the radiation amplitude of a massless closed string from the interaction of two fractional D$p$-branes with the previous background fields. The branes have been dressed by different fields and have transverse motions. The total radiation amplitude will be investigated for large inter-brane separation. Finally, the graviton, Kalb-Ramond (axion) and dilaton emissions will be distinctly studied. Our calculations are in the context of the bosonic string theory.

hep-th↗

arXiv2022

Gravitational and Dilatonic Radiations from the Parallel Dressed-Dynamical Unstable Dp-Branes

In the context of the bosonic string theory, we shall extract the general radiation amplitude of a massless closed string from the interaction of two parallel unstable D$p$-branes. The branes are non-stationary and have been dressed by background fields. The foregoing amplitude will be rewritten for the massless state radiation from the branes with the large distance. Besides, we shall study the gravitational and dilatonic radiations from this configuration.

hep-th↗

arXiv2022

Radiation of Closed Strings between the Parallel Dynamical-Dressed Unstable Dp-Branes

We introduce a boundary state which is corresponding to a D$p$-brane with tangential dynamics in the presence of the Kalb-Ramond field, a tachyonic field and a $U(1)$ gauge potential in a special gauge. From the interaction of such branes radiation amplitude of a general massless closed string will be computed. The effects of the large distances of the branes on this radiation will be studied. In the large distances of the branes, the possibility of axion radiation will be investigated. Our calculations will be in the context of the bosonic string theory.

hep-th↗