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Davoud Kamani

Publications and source records attributed to Davoud Kamani.

At least 37 records · Page 2Linked to original sources
arXiv2020

Left-Right Entanglement Entropy for a Dp-brane with Dynamics and Background Fields

We investigate the left-right entanglement entropy of a boundary state, corresponding to a dynamical D$p$-brane with the internal and background fields. We assume that the brane has a tangential linear motion and a rotation, and is dressed with an internal $U(1)$ gauge potential and the Kalb-Ramond tensor field $B_{μν}$. We derive the entanglement entropy via the Rényi entropy by applying the replica trick. Our calculations will be in the context of the bosonic string theory.

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arXiv2019

Scattering of the Kalb-Ramond State from a Dynamical D$p$-brane with Background Fields

We apply the boundary state method and operator formalism to obtain tree-level scattering amplitude of the Kalb-Ramond state from a D$p$-brane. The brane has a tangential dynamics, and it has been dressed by the antisymmetric tensor field, a $U(1)$ internal gauge potential and an open string tachyon field. By using the scattering amplitudes we acquire two DBI-like actions corresponding to the target branes. Our calculations are in the framework of the bosonic string theory.

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arXiv2019

Effective Action of a Dynamical D$p$-brane with Background Fluxes

We shall construct the Dirac-Born-Infeld like and the Wess-Zumino like actions for a dynamical D$p$-brane with the $U(1)$ gauge potential and the Kalb-Ramond background field. The brane dynamics simultaneously has both tangential and transverse components. Our calculations will be in the context of the type II superstring theory, via the boundary state formalism.

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arXiv2018

Fractional Dp-Branes with Transverse and Tangential Dynamics in the Presence of Background Fluxes

We shall construct two boundary states which are corresponding to a dynamical fractional D$p$-brane in the presence of the fluxes of the Kalb-Ramond field and a $U(1)$ gauge potential, in the partially orbifold spacetime $\mathbb{R}^{1, 5}\times\mathbb{C}^{2}/\mathbb{Z}_{2}$. These states accurately describe the D$p$-brane in the twisted and untwisted sectors under the orbifold projection. We use them to compute the interaction of two parallel fractional D$p$-branes with the transverse velocities, tangential rotations and tangential linear motions. Various properties of the interaction, such as its long-range force, will be discussed.

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arXiv2017

Fractional-Wrapped Branes with Rotation, Linear Motion and Background Fields

We obtain two boundary states corresponding to the two folds of a fractional-wrapped D$p$-brane, i.e. the twisted version under the orbifold $\mathbb{C}^{2}/\mathbb{Z}_{2}$ and the untwisted version. The brane has rotation and linear motion, in the presence of the following background fields: the Kalb-Ramond tensor, a $U(1)$ internal gauge potential and a tachyon field. The rotation and linear motion are inside the volume of the brane. The brane lives in the $d$-dimensional spacetime, with the orbifold-toroidal structure $T^n \times \mathbb{R}^{1, d-n-5} \times\mathbb{C}^{2}/\mathbb{Z}_{2}$ in the twisted sector. Using these boundary states we calculate the interaction amplitude of two parallel fractional D$p$-branes with the foregoing setup. Various properties of this amplitude such as the long-range behavior will be analyzed.

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arXiv2017

Interaction of Dynamical Fractional Branes with Background Fields: Superstring Calculations

We compute the boundary state corresponding to a fractional D$p$-brane with transverse motion and internal background fields: Kalb-Ramond and a $U(1)$ gauge field. The spacetime has the orbifold structure $\mathbb{R}^{1,5} \times\mathbb{C}^{2}/\mathbb{Z}_{2}$. The calculations are in the superstring theory. Using this boundary state we shall obtain the interaction amplitude between two parallel moving fractional D$p$-branes. We shall extract behavior of the interaction amplitude for large distances of the branes.

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arXiv2017

Moving Fractional Branes with Background Fields: Interaction and Tachyon Condensation

We calculate the bosonic boundary state corresponding to a moving fractional D$p$-brane in a partially orbifoldized spacetime $\mathbb{R}^{1, d-5} \times\mathbb{C}^{2}/\mathbb{Z}_{2}$ in the presence of the Kalb-Ramond field, the $U(1)$ gauge potential and the tachyon field. Using this boundary state we obtain interaction amplitude of two parallel moving D$p$-branes with the above background fields. Various properties of the interaction will be investigated. Besides, we study effects of the tachyon condensation on a moving fractional D$p$-brane with the above background fields through the boundary state formalism.

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arXiv2017

Interaction of the branes in the Presence of the Background Fields: the Dynamical Non-intersecting Perpendicular Wrapped-Fractional Configuration

We shall obtain the interaction of the D$p_1$- and D$p_2$-branes in the toroidal-orbifold spacetime $\mathit{T}^{n}\times\mathbb{R}^{1, d-n-5} \times\mathbb{C}^{2}/\mathbb{Z}_{2}$. The configuration of the branes is: non-intersecting, perpendicular, moving-rotating, wrapped-fractional with background fields. For this, we calculate the bosonic boundary state corresponding to a dynamical fractional-wrapped D$p$-brane in presence of the Kalb-Ramond field, a $U(1)$ gauge potential and an open string tachyon field. The long-range behavior of the interaction amplitude will be extracted.

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arXiv2015

Resistance of a Rotating-Moving Brane with Background Fields Against Collapse

Using the boundary state formalism we investigate the effect of tachyon condensation process on a rotating and moving D$p$-brane with various background fields in the bosonic string theory. The rotation and motion are inside the brane volume. We demonstrate that some specific rotations and/or motions can preserve the brane from instability and collapse.

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arXiv2014

Rotating-Moving D-Branes with Background Fields in the Superstring Theory

Using the boundary state formalism we study rotating and moving D$p$-branes in the presence of the following background fields: Kalb-Ramond, $U(1)$ gauge potential and the tachyon field. The rotation and motion are in the brane volumes. The interaction amplitude of two D$p$-branes will be studied, and specially contribution of the superstring massless modes will be segregated. Because of the tachyon fields, rotations and velocities of the branes, the behavior of the interaction amplitude reveals obvious differences from what is conventional.

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arXiv2014

Rotating and Moving D-Branes in the Presence of Various Background Fields

We calculate the bosonic boundary state associated with a rotating and moving D$p$-brane in the presence of the antisymmetric tensor field, a $U(1)$ gauge field and a tachyon field. Rotation and motion are in the brane volume. We reconstruct this boundary state via the group $PSL(2,R)$ to be applicable when the tachyon field is presented. This modified boundary state enables us to calculate the interaction amplitude between two parallel D$p$-branes with rotation and motion. The long-range force of this interaction will be obtained. The boundary state also enables us to investigate the tachyon condensation on a rotating and moving D$p$-brane.

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arXiv2013

Some $\mathbf{Z}_2$-invariant Variables: Constructed of the Scalars Dilaton and Axion

Using the dilaton scalar and axion pseudoscalar fields we construct a number of scalars and differential forms which are symmetric under the $\mathbf{Z}_2$-subgroup of the group $SL(2, \mathbf{R})$. These invariants enable us to establish various 10-dimensional invariant actions. Other invariants which are not independent from the previous ones will be detached.

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arXiv2013

Non-commutative Dp-Brane in General Background Fields

We investigate non-commutativity of open strings, attached to a D$p$-brane, in the presence of the linear dilaton, tachyon, U(1) gauge field as well as constant anti-symmetric $B$-field backgrounds. Non-commutativity parameter, open string metric and some special cases will be studied. Mode-dependent non-commutativity, inspired by the tachyon field, will be discussed in detail.

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arXiv2011

Interaction of Moving Branes with Background Massless and Tachyon Fields in Superstring Theory

Using the boundary state formalism we study a moving D$p$-brane in a partially compact spacetime in the presence of the background fields: Kalb-Ramond $B_{μν}$, a U(1) gauge field $A_α$ and the tachyon field. The boundary state enables us to obtain interaction amplitude of two branes with above background fields. The branes are parallel or perpendicular to each other. Presence of the background fields, compactification of some directions of the spacetime, motion of the branes and arbitrariness of the branes' dimensions give a general feature to the system. Due to the tachyon fields and velocities of the branes, the behavior of the interaction amplitude reveals obvious differences from what is conventional.

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arXiv2011

Moving Branes with Background Massless and Tachyon Fields in the Compact Spacetime

In this article we shall obtain the boundary state associated with a moving $Dp$-brane in the presence of the Kalb-Ramond field $B_{μν}$, an internal U(1) gauge field $A_α$ and a tachyon field, in the compact spacetime. According to this state, properties of the brane and a closed string, with mixed boundary conditions emitted from it, will be obtained. Using this boundary state we calculate the interaction amplitude of two moving $Dp_{1}$ and $Dp_{2}$-branes with above background fields in a partially compact spacetime. They are parallel or perpendicular to each other. Properties of the interaction amplitude will be analyzed and contribution of the massless states to the interaction will be extracted.

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arXiv2011

Moving Branes in Presence of the Background Tachyon Fields

We compute the boundary state associated with a moving D$p$-brane in the presence of the open string tachyon field as a background field. The effect of the tachyon condensation on the boundary state will be discussed. It leads to a boundary state associated with a lower dimensional moving D-brane or a stationary instantonic D-brane. The former originates from condensation along the spatial directions and the latter comes from the temporal direction of the D-brane's worldvolume. Using the boundary state we also study the interaction amplitude between two arbitrary D$p_1$ and D$p_2$-branes. The long range behavior of the amplitude is investigated which shows an obvious deviation from the conventional form, due to the presence of the background tachyon field.

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