Papers by HARVENDRA SINGH
In this paper we study K3 compactification of ten-dimensional massive type IIA theory with all po... more In this paper we study K3 compactification of ten-dimensional massive type IIA theory with all possible Ramond-Ramond background fluxes turned on. The resulting sixdimensional theory is a new massive (gauged) supergravity with an action that is manifestly invariant under an O(4, 20)/O(4) × O(20) duality symmetry. We discover that this six-dimensional theory interpolates between vacua of ten-dimensional massive IIA supergravity and vacua of massless IIA supergravity with appropriate background fluxes turned on. This in turn suggests a new 11-dimensional interpretation for the massive type IIA theory. 1
Fifth International Conference on Advances in Computing, Communication and Information Technology - CCIT 2017, 2017
International Journal of Modern Physics A, 2017
We study the effects of asymmetry in the entanglement thermodynamics of CFT subsystems. It is fou... more We study the effects of asymmetry in the entanglement thermodynamics of CFT subsystems. It is found that “boosted” Dp-brane backgrounds give rise to the first law of the entanglement thermodynamics where the CFT pressure asymmetry plays a decisive role in the entanglement. Two different strip like subsystems, one parallel to the boost and the other perpendicular, are studied in the perturbative regime [Formula: see text]. We mainly seek to quantify this entanglement asymmetry as a ratio of the first-order entanglement entropies of the excitations. We discuss the AdS-wave backgrounds at zero temperature having maximum asymmetry from where a bound on entanglement asymmetry is obtained. The entanglement asymmetry reduces as we switch on finite temperature in the CFT while it is maximum at zero temperature.
Physics Letters B, 2009
We construct a SU(N) membrane B ∧ F theory with dual pairs of scalar and tensor fields. The modul... more We construct a SU(N) membrane B ∧ F theory with dual pairs of scalar and tensor fields. The moduli space of the theory is precisely that of N M2-branes on the noncompact flat space. The theory possesses explicit SO(8) invariance and is an extension of the maximal SU(N) super-Yang-Mills theory.
We use the information metric to investigate the moduli space of a U(1) instanton on (anti)self-d... more We use the information metric to investigate the moduli space of a U(1) instanton on (anti)self-dual manifolds, finding an $AdS$ geometry similar to that for the moduli space of a Yang-Mills instanton on flat space. We discuss our results from the perspective of gauge/gravity duality.
Physics Letters B, 2002
We construct M5-branes with 3/8 supersymmetry and find that they preserve exactly half of the bac... more We construct M5-branes with 3/8 supersymmetry and find that they preserve exactly half of the background pp-wave supersymmetries. We explicitly write down the standard as well as supernumerary Killing spinors and find that their respective numbers are also half of those for the pp-wave background. This is in line with the recent work of Dabholkar et.al. which shows that half-supersymmetric D-branes can be constructed in pp-wave backgrounds.
Journal of High Energy Physics, 2006
We aim to study rolling tachyon cosmological solutions in de Sitter gravity. The solutions are ta... more We aim to study rolling tachyon cosmological solutions in de Sitter gravity. The solutions are taken to be flat FRW type and these are not time-reversal symmetric. We find that cosmological constant of our universe has to be fine-tuned at the level of the action itself, as in KKLT string compactification. The rolling tachyon can give rise to required inflation with suitable choice of the initial conditions which include nonvanishing Hubble constant. We also determine an upper bound on the volume of the compactification manifold.
Nuclear Physics B, 2001
We investigate how the four-dimensional noncommutative open string/Yang-Mills theory behaves unde... more We investigate how the four-dimensional noncommutative open string/Yang-Mills theory behaves under a general non-perturbative quantum SL(2, Z) symmetry transformation. We discuss this by considering D3 branes in a constant background of axion, dilaton, and electric and magnetic fields (including both E ⊥ B and E||B cases) in the respective decoupling limit. We find that the value of axion, whether rational or irrational, determines the nature of the resulting theory under SL(2, Z) as well as its properties such as the coupling constant and the number of noncommutative directions. In particular, a strongly coupled theory with an irrational value of axion can never be physically equivalent to a weakly coupled theory while this is usually true for a theory with a rational value of axion. A noncommutative Yang-Mills (NCYM) (resulting from D3 branes with pure magnetic flux) is physically equivalent to a noncommutative open string (NCOS) but if the value of axion is irrational, we also have noncommutative space-space directions in addition to the usual noncommutative space-time directions for NCOS. We also find in general that a NCOS cannot be physically equivalent to a NCYM but to another NCOS if the value of axion is irrational. We find another new decoupling limit for possible light-like NCYM whose SL(2, Z) duality is a light-like ordinary Yang-Mills if the value of the axion is rational. Various related questions are also discussed.
Journal of High Energy Physics, 2005
We consider de Sitter spacetime solutions and the corresponding de Sitter kind of plane-wave solu... more We consider de Sitter spacetime solutions and the corresponding de Sitter kind of plane-wave solution in M * theory which is a (2 + 9)-dimensional theory. We attempt to write down corresponding matrix model which is found to have explicit negative energy mass terms as well as ghost-like kinetic terms for the matrix valued fields.
Journal of High Energy Physics, 2013
Journal of High Energy Physics, 2007
Space-like branes or S-branes are certain class of time dependent solutions of M/string theories ... more Space-like branes or S-branes are certain class of time dependent solutions of M/string theories having isometries ISO(p + 1) × SO(d − p − 2, 1), where d = 11, 10 respectively and have singularities at t = 0. In [1], we found that the asymptotically flat S-branes have the structure of generalized Kasner geometry near t = 0. In this work we evaluate higher order α ′ corrections perturbatively to the heterotic string Kasner backgrounds to probe the singularity at t = 0. We generally find that the perturbative corrections do not permit us to reach the singular point, as the supergravity framework fails near t ∼ √ α ′ blurring the origin of space-like singularities. This is analogous to the concept of stretched horizons in the case of black holes.
Journal of High Energy Physics, 2012
We extend our earlier study of special double limits of 'boosted' AdS 5 black hole solutions to i... more We extend our earlier study of special double limits of 'boosted' AdS 5 black hole solutions to include all black Dp-branes of type II strings. We find that Lifshitz solutions can be obtained in generality, with varied dynamical exponents, by employing these limits. We then study such double limits for 'boosted' Dp-brane bubble solutions and find that the resulting non-relativistic solutions instead describe Schrödinger like spacetimes, having varied dynamical exponents. We get a simple map between these Lifshitz & Schrödinger solutions and a relationship between two types of dynamical exponents. We also discuss about the singularities of the Lifshitz solutions and an intriguing thermodynamic duality.
Journal of High Energy Physics, 2010
We study special vanishing horizon limit of 'boosted' black D3-branes having a compact light-cone... more We study special vanishing horizon limit of 'boosted' black D3-branes having a compact light-cone direction. The type IIB solution obtained by taking such a zero temperature limit is found to describe a nonrelativistic system with dynamical exponent 3. We discuss about such limits in M2-branes case also.
Quality Engineering, 2008
... Deployment: A Case Study on Indian Bikes T. Soota,1 H. Singh,2 R. Mishra3 1Department of Mech... more ... Deployment: A Case Study on Indian Bikes T. Soota,1 H. Singh,2 R. Mishra3 1Department of Mechanical Engineering, AIET, Lucknow, India 2Department of Mechanical Engineering, KNIT,Sultanpur, India 3Department of Mechanical Engineering, NIEC, Lucknow, India ...
Physics Letters B, 1998
In this paper we obtain supersymmetric brane-like configurations in the vacuum of N = 4 gauged SU... more In this paper we obtain supersymmetric brane-like configurations in the vacuum of N = 4 gauged SU(2)×SU(2) supergravity theory in four spacetime dimensions. Almost all of these vacuum solutions preserve either half or one quarter of the supersymmetry in the theory. We also study these solutions in presence of nontrivial axionic and gauge field backgrounds. In the case of pure gravity with axionic charge the geometry of the spacetime is AdS 3 × R 1 with N = 1 supersymmetry. An interesting observation is that the domain walls of this theory cannot be given an interpretation of a 2-brane in four dimensions. But it still exists as a stable vacuum. This feature is quite distinct from the domain-wall configuration in massive type IIA supergravity in ten dimensions.
Physics Letters B, 2004
In this note we aim to study plane-wave limits of the solutions of type II * superstring theories... more In this note we aim to study plane-wave limits of the solutions of type II * superstring theories. We consider Freund-Rubin type dS 5 × H 5 solutions of type IIB * theory and obtain a new kind of plane-wave solutions, we refer them as de Sitter plane-waves or Dpp-waves. Considering Hull's time-like T-duality we are able to map the Dpp wave solution to maximally supersymmetric Hpp-wave in IIB string theory and vice-versa.
Physics Letters B, 1998
In this report we obtain explicit string-like solutions of equations of motion of massive heterot... more In this report we obtain explicit string-like solutions of equations of motion of massive heterotic supergravity recently obtained by Bergshoeff, Roo and Eyras. We also find consistent string source which can be embedded in these backgrounds when space-time dimension is greater than or equal to six.
Physics Letters B, 1998
In this note we extend our work in a previous paper hep-th/9801038. We show here that various int... more In this note we extend our work in a previous paper hep-th/9801038. We show here that various intersecting brane-like configurations can be found in the vacuum of D = 4, N = 4 supergravity with gauged R-symmetry group SU(2)×SU(2). These include intersections of domain-walls, strings and pointlike objects. Some of these intersecting configurations preserve 1/2 and 1/4 of supersymmetry. We observe that the previously obtained AdS 3 × R 1 pure axionic vacuum or 'axio-vac' is an intersection of domain-wall with extended string with 1/2 supersymmetries. Also the solutions known as 'electro-vac' with geometry AdS 2 × R 2 can be simply interpreted as the intersection of domain-wall with point-like object.
Physics Letters B, 2000
We study Euclidean D = 4, N = 4 gauged SU(2) × SU(1, 1) supergravity theory which has been obtain... more We study Euclidean D = 4, N = 4 gauged SU(2) × SU(1, 1) supergravity theory which has been obtained from dimensional reduction of N = 1, D = 10 supergravity on S 3 × AdS 3. We obtain supersymmetric configurations like domain wall, electro-vac type of solutions with geometries E 2 × S 2 , E 2 × AdS 2 and axio-vac type E 1 × S 3 solution in this Euclidean Freedman-Schwarz (EFS) model. We also show that the Euclidean gravitational instantons with nontrivial (anti)self-dual U(1) gauge fields are stable vacua preserving one fourth of the original supersymmetry.
Uploads
Papers by HARVENDRA SINGH