arXiv subjects

Ehsan Hatefi

Publications and source records attributed to Ehsan Hatefi.

45 records · Page 3Linked to original sources

arXiv2013

Shedding light on new Wess-Zumino couplings with their corrections to all orders in alpha-prime

Motivated by arXiv:1203.5553, we continue to match super string amplitudes with their own effective field theory. We carry out within full details the computations of the complete form of the amplitude of one closed string Ramond-Ramond field and three SYM vertex operators, namely one gauge field and two scalar fields in type IIB(A) super string theories. Making use of the recent two gauge and two scalar couplings to all orders of $α'$, we produce all the infinite gauge poles for $p=n$ case (with $n$ as RR field strength's rank and $p$ as the dimension of a D$_p$-brane). Proceeding with direct and full S-Matrix calculations, we are able to produce even all the infinite gauge poles in u-channel for $p-2=n$ case in field theory as well. New couplings for $p-2=n$ case with their all order $α'$ corrections are discovered. In addition, we explain how to find out all the infinite scalar poles of this amplitude in $s,t$-channels and produce them for $p+2=n$ case. By comparing all of the contact terms of this amplitude, we obtain several new couplings with their higher derivative corrections for $p+2=n,p=n$ cases. These new couplings are neither inside Myers'terms nor within pull-back/Taylor expansions. Finally we comment on some related issues.

hep-th↗

arXiv2012

Universality in all-order $α'$ corrections to BPS/non-BPS brane world volume theories

Knowledge of all-$α'$ higher derivative corrections to leading order BPS and non-BPS brane actions would serve in future endeavor of determining the complete form of the non-abelian BPS and tachyonic effective actions. In this paper, we note that there is a universality in the all-$α'$ order corrections to BPS and non-BPS branes. We compute amplitudes between one Ramond-Ramond $C$-field vertex operator and several SYM gauge/scalar vertex operators. Specifically, we evaluate in closed form string correlators of two-point amplitudes $\cal A^{Cϕ}$, $\cal A^{CA}$, a three-point amplitude $\cal A^{Cϕϕ}$ and a four-point amplitude $\cal A^{Cϕϕϕ}$. We carry out pole and contact term analysis. In particular we reproduce some of the contact terms and the infinite massless poles of $\cal A^{Cϕϕϕ}$ by SYM vertices obtained through the universality.

hep-th↗

arXiv2012

More on closed string induced higher derivative interactions on D-branes

In our continued efforts of matching full string computations with the corresponding effective field theory computations, we evaluate string theory correlators in closed forms. In particular, we consider a correlator between three SYM vertex operators and one Ramond-Ramond $C$-field vertex operator: $ $. We show that the infinite number of massless poles of this amplitude can be reproduced by the Born-Infeld action, the Wess-Zumino terms, and their higher derivative corrections. More specifically we find, up to an on-shell ambiguity, two scalar field and two gauge field couplings to all orders in $α'$ such that the infinite number of massless poles of the field theory amplitude exactly match the infinite number of massless poles of S-matrix elements of $ $. We comment on close intertwinedness of an open string and a closed string that must be behind the matching.

hep-th↗

arXiv2011

Critical Collapse in the Axion-Dilaton System in Diverse Dimensions

We study the gravitational collapse of the axion-dilaton system suggested by type IIB string theory in dimensions ranging from four to ten. We extend previous analysis concerning the role played by the global SL(2,R) symmetry and we evaluate the Choptuik exponents in the elliptic case.

gr-qc↗

arXiv2011

Three Point Tree Level Amplitude in Superstring Theory

In order to check the definite amplitude and the exact zero result of the amplitude of three massless points $(CAA)$ in both string theory and field theory side for $p=n$ case and to find all gauge field couplings to R-R closed string, we investigate the disk level S-matrix element of one Ramond-Ramond field and two gauge field vertex operators in the world volume of BPS branes.

hep-th↗

arXiv2010

On effective actions of BPS branes and their higher derivative corrections

We calculate in detail the disk level S-matrix element of one Ramond-Ramond field and three gauge field vertex operators in the world volume of BPS branes, to find four gauge field couplings to all orders of $α'$ up to on-shell ambiguity. Then using these infinite couplings we find that the massless pole of the field theory amplitude is exactly equal to the massless pole S-matrix element of this amplitude for the $p=n$ case to all orders of $α'$. Finally we show that the infinite massless poles and the contact terms of this amplitude for the $p=n+2$ case can be reproduced by the Born-Infeld action and the Wess-Zumino actions and by their higher derivative corrections.

hep-th↗

arXiv2010

Extremal rotating solutions in Horava Gravity

Recently a new four-dimensional non relativistic renormalizable theory of gravity was proposed by Horava. In this paper we have found different near horizon geometries in Horava gravity. We find the rotating solutions in a special range of parameters of the theory. This range allows us to include up to six derivative terms in the equations of motion. We have found our solutions as perturbed solutions over spherical symmetric background with small rotating parameter.

hep-th↗

arXiv2009

More on WZ action of non-BPS branes

We calculate the disk level S-matrix element of one Ramond-Ramond, two gauge fields and one tachyon vertex operators in the world volume of non-BPS branes. We then find the momentum expansion of this amplitude and show that the infinite tachyon/massless poles and the contact terms of this amplitude can be reproduced by the tachyon DBI and the WZ actions, and by their higher derivative corrections.

hep-th↗

arXiv2007

On Wess-Zumino terms of Brane-Antibrane systems

We calculate the disk level S-matrix element of one closed string RR field, two open string tachyons and one gauge field in type II superstring theory. An expansion for the S-matrix element has been found that its four leading order terms are reproduced exactly by the symmetric trace tachyon DBI and the Wess-Zumino actions of D-brane-anti-D-brane systems. Using this consistency, we have also found the first higher derivative correction to the some of the WZ terms.

hep-th↗