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Ansar Fayyazuddin

Publications and source records attributed to Ansar Fayyazuddin.

At least 19 recordsLinked to original sources
arXiv2016

Massive 3d Abelian gauge theories and electric-magnetic duality

We study a model of massive photons with a parity invariant and non-local mass term. We identify a discrete symmetry of the classical equations of motion and show that this symmetry can be thought of as an electric-magnetic duality valid only in the presence of a non-zero photon mass. We explore this duality and discuss some features of the theory. We define notions of electric and magnetic charge that can be computed in any spatial domain as a volume integral of a density. These integrals can be transformed into integrals on the boundary. For instance, the electric charge is given by the sum of the electric flux through the boundary of the domain and a line integral of the dual gauge field along that same boundary. We show that electric and magnetic charge is quantized $q_mq_e = 2πn m_γ/e^2$, where $e$ is the coupling constant and $m_γ$ is the mass of the photon. Classical field configurations associated with external electric and magnetic charges as well as the classical forces between electric and magnetic charges are computed.

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arXiv2011

Non-local symmetries for Yang-Mills theories and their massive counterparts in two and three dimensions

We identify a non-local symmetry for Yang-Mills theories in 1+1 and 2+1 spacetime dimensions. The symmetry mixes a vector current with the gauge field. The current involved in the symmetry is required to satisfy certain constraints. The explicit solution for the current obeying these constraints, is obtained in two spacetime dimensions and in the abelian case in three dimensions. We conjecture that the current is generated from a non-local gauge and Lorentz invariant mass term in three dimensions and provide some evidence for it. We also posit a conserved current associated with the symmetry generators and derive some of its properties. In the Abelian case, we compute the symmetry algebra and show that additional symmetry generators have to be included for the algebra to close. The algebra contains an SO(2,1) subalgebra. We also comment on the implications of this symmetry for N=1 supersymmetry.

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arXiv2007

Calabi-Yau 3-folds from 2-folds

We consider type IIA string theory on a Calabi-Yau 2-fold with D6-branes wrapping 2-cycles in the 2-fold. We find a complete set of conditions on the supergravity solution for any given wrapped brane configuration in terms of SU(2) structures. We reduce the problem of finding a supergravity solution for the wrapped branes to finding a harmonic function on R$\times$CY$_2$. We then lift this solution to 11-dimensions as a product of R$^{(4.1)}$ and a Calabi-Yau 3-fold. We show how the metric on the 3-fold is determined in terms of the wrapped brane solution. We write down the distinguished (3,0) form and the K{ä}hler form of the 3-fold in terms of structures defined on the base 2-d complex manifold. We discuss the topology of the 3-fold in terms of the D6-branes and the underlying 2-fold. We show that in addition to the non-trivial cycles inherited from the underlying 2-fold there are $N-1$ new 2-cycles. We construct closed (1,1) forms corresponding to these new cycles. We also display some explicit examples. One of our examples is that of D6-branes wrapping the 2-cycle in an A$_1$ ALE space, the resulting 3-fold has $h^{(1,1)}=N$, where $N$ is the number of D6-branes.

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arXiv2006

$G_2$ holonomy metrics and wrapped D6-branes

We determine torsion class constraints for the supergravity background produced by D6-branes wrapping special Lagrangian cycles in a Calabi-Yau 3-fold. We employ a recently introduced method which involves probing the putative background by all possible supersymmetric brane configurations. We then lift this background to 11-dimensions to a product of 4-d Minkowski space and a 7-fold of G2-holonomy. The latter is a particular U(1) bundle over an almost complex manifold of SU(3) structure with specific torsion class constraints. We construct the closed 3- and 4-forms which calibrate the 3- and 4-cycles in the G2-holonomy manifold.

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arXiv2006

Ten and eleven dimensional perspectives on N=2 black holes

We give an 11 and 10 dimensional supergravity description of M5-branes wrapping 4-cylces in a Calabi-Yau manifold and carrying momentum along a transverse S$^1$. These wrapped branes descend to a class of N=2 black holes in 4 dimensions. Our description gives the conditions on the geometry interpolating between the asymptotic and near-horizon regions. We employ the ideas of geometric transitions to show that the near horizon geometry in ten dimensions is AdS$_2\times$S$^2\times CY_3$ while in 11 dimensions it is AdS$_3\times$S$^2\times CY_3$. We also show how to obtain the complete N=2 black hole supergravity solution in 4 dimensions for this class of black holes starting with our 11-dimensional description. Finally, we generalize our results on the 10 and 11 dimensional near horizon supergravity solution to the case of black holes carrying arbitrary charges (D0-D2-D4-D6 in the type IIA description). We argue that the near horizon geometry corresponding to wrapped D6 and D2 branes in 11 dimensions is AdS$_2\times$S$^3\times CY_3$.

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arXiv2005

Calibrations, Torsion Classes and Wrapped M-Branes

The present work has two goals. The first is to complete the classification of geometries in terms of torsion classes of M-branes wrapping cycles of a Calabi-Yau. The second goal is to give insight into the physical meaning of the torsion class constraints. We accomplish both tasks by defining new energy minimizing calibrations in M-brane backgrounds. When fluxes are turned on, it is these calibrations that are relevant, rather than those which had previously been defined in the context of purely geometric backgrounds.

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arXiv2005

The geometry of wrapped M5-branes in Calabi-Yau 2-folds

We study the geometry of M5-branes wrapping a 2-cycle which is Special Lagrangian with respect to a specific complex structure in a Calabi-Yau two-fold. Using methods recently applied to the three-fold case, we are again able find a characterization of the geometry, in terms of a non-integrable almost complex structure and a (2,0) form. This time, however, due to the hyper-K{ä}hler nature of the underlying 2-fold we also have the freedom of choosing a different almost complex structure with respect to which the wrapped 2-cycle is holomorphic. We show that this latter almost complex structure is integrable. We then relate our geometry to previously found geometries of M5-branes wrapping holomophic cycles and go further to prove some previously unknown results for M5-branes on holomorphic cycles.

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arXiv2004

One dimensional M5-brane intersections

We study one dimensional intersections of M5 branes with M5 and M2 branes. On the worldvolume of the M5-brane, such an intersection appears as a string soliton. We study this worldvolume theory in two different regimes: 1) Where the worldvolume theory is formulated in flat space and 2) where the worldvolume theory is studied in the supergravity background produced by a stack of M5 (or M2) branes. In both cases, we study the corresponding string solitons, and find the most general BPS configuration consistent with the fraction of supersymmetries preserved. We argue that M5 and M2 brane intersections leave different imprints on the worldvolume theory of the intersecting probe brane, although geometrically they appear to be similar.

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arXiv2002

Supersymmetric webs of D3/D5-branes in supergravity

We study webs of D3- and D5-branes in type IIB supergravity. These webs preserve at least 8 supercharges. By solving the Killing spinor equations we determine the form of supergravity solutions for the system. We then turn to the sub-class of the intersecting D3/D5 brane system and elucidate some of its features.

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arXiv2002

Marginal perturbations of N=4 Yang-Mills as deformations of AdS$_5\times S^5$

We study constant dilaton supersymmetric solutions of type IIB Supergravity with 5-form and 3-form flux with isometry group U(1) $\times$$Z_3$. Some of these solutions correspond to marginal perturbations of N=4 Yang-Mills. We find one line of solutions in particular of AdS$_5$ fibred over an $S^5$. This line is described by a single complex parameter. AdS$_5\times$S$^5$ is obtained when this partameter is tuned to zero.

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arXiv2001

N=1 M5-brane geometries

We describe how to construct solutions to 11-dimensional supergravity corresponding to M5-branes wrapped on holomorphic 2-cycles embedded in C^3. These solutions preserve N=1 supersymmetry in four dimensions. In the near-horizon limit they are expected to be dual to N=1 large N gauge theories in four dimensions by Maldacena's duality.

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arXiv2000

Supergravity M5-branes wrapped on Riemann surfaces and their QFT duals

We find solutions of 11-dimensional supergravity for M5-branes wrapped on Riemann surfaces. These solutions preserve ${\cal N} = 2$ four-dimensional supersymmetry. They are dual to ${\cal N} = 2$ gauge theories, including non-conformal field theories. We work out the case of ${\cal N} = 2$ Yang-Mills in detail.

hep-th↗
arXiv2000

A note on bosonic open strings in constant B field

We sketch the main steps of old covariant quantization of bosonic open strings in a constant $B$ field background. We comment on its space-time symmetries and the induced effective metric. The low-energy spectrum is evaluated and the appearance of a new non-commutative gauge symmetry is addressed.

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arXiv1999

Localized intersections of M5-branes and four-dimensional superconformal field theories

We write supersymmetry preserving conditions for infinite M5-branes intersecting on a (3+1)-dimensional space. In contrast to previously known solutions, these intersections are completely localized. We solve the equations for a particular class of configurations which in the near-horizon decoupling limit are dual to N_f = 2N_c Seiberg-Witten superconformal field theories with gauge group SU(N) and generalisations to SU(N)^n. We also discuss the relationship to D3-branes in the presence of an A_k singularity.

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arXiv1998

The Large N Limit of ${\cal N} =2,1 $ Field Theories from Threebranes in F-theory

We consider field theories arising from a large number of D3-branes near singularities in F-theory. We study the theories at various conformal points, and compute, using their conjectured string theory duals, their large $N$ spectrum of chiral primary operators. This includes, as expected, operators of fractional conformal dimensions for the theory at Argyres-Douglas points. Additional operators, which are charged under the (sometimes exceptional) global symmetries of these theories, come from the 7-branes. In the case of a $D_4$ singularity we compare our results with field theory and find agreement for large $N$. Finally, we consider deformations away from the conformal points, which involve finding new supergravity solutions for the geometry produced by the 3-branes in the 7-brane background. We also discuss 3-branes in a general background.

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arXiv1997

The Seiberg-Witten Differential From M-Theory

The form of the Seiberg-Witten differential is derived from the M-theory approach to N=2 supersymmetric Yang-Mills theories by directly imposing the BPS condition for twobranes ending on fivebranes. The BPS condition also implies that the pullback of the Kahler form onto the space part of the twobrane world-volume vanishes.

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arXiv1997

A note on T^5/Z_2 compactification of the M-theory matrix model

We study the T^5/Z_2 orbifold compactification of the M-theory matrix model. This model was originally studied by Dasgupta, Mukhi, and Witten. It was found that one had to add 16 5-branes to the system to make the compactification consistent. We demonstrate how this is mimicked in the matrix model.

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