Parampreet Singh

Are loop quantum cosmos never singular? (2009)

We re-examine the issue of singularity resolution in homogeneous loop quantum cosmology from the perspective of geometrical entities such as expansion rate and the shear scalar. These quantities are...

Transcending Big Bang in Loop Quantum Cosmology: Recent Advances (2009)

A unified treatment of all known types of singularities for flat, isotropic and homogeneous spacetimes in the framework of loop quantum cosmology (LQC) is presented. These include bangs, crunches and...

Reply to `Comment on "Quantum Bounce and Cosmic Recall"' [arXiv:0811.2790] (2008)

We discuss the way non-perturbative quantization of cosmological spacetimes in loop quantum cosmology provides insights on the physics of Planck scale and the resolution of big bang singularity. In...

Covariant Effective Action for Loop Quantum Cosmology a la Palatini (2008)

A recent Comment [arXiv:0811.2790] on the Letter 'Quantum Bounce and Cosmic Recall' by the authors is shown to arise from an incorrect understanding of the issues at hand and of our analysis. The...

Olmo, Gonzalo J., Singh, Parampreet

In loop quantum cosmology, non-perturbative quantum gravity effects lead to the resolution of the big bang singularity by a quantum bounce without introducing any new degrees of freedom. Though...

Is loop quantization in cosmology unique? (2008)

Quantum bounce and cosmic recall (2007)

We re-examine the process of loop quantization for flat isotropic models in cosmology. In particular, we contrast different inequivalent `loop quantizations' of these simple models through their...

Robustness of key features of loop quantum cosmology (2007)

Loop quantum cosmology predicts that, in simple models, the big bang singularity of classical general relativity is replaced by a quantum bounce. Because of the extreme physical conditions near the...

Ashtekar, Abhay, Corichi, Alejandro, Singh, Parampreet

A small simplification based on well motivated approximations is shown to make loop quantum cosmology of the k=0 Friedman-Robertson-Walker (FRW) model (with a massless scalar field) exactly soluble....

Graceful exit via polymerization of pre-big bang cosmology (2007)

De Risi, Giuseppe, Maartens, Roy, Singh, Parampreet

We consider a phenomenological modification of the Pre Big Bang scenario using ideas from the resolution of curvature singularities in Loop Quantum Cosmology. We show that non-perturbative Loop...

Thermal fluctuations in loop cosmology (2007)

Magueijo, Joao, Singh, Parampreet

Quantum gravitational effects in loop quantum cosmology lead to a resolution of the initial singularity and have the potential to solve the horizon problem and generate a quasi scale-invariant...

Formation and Evolution of Structure in Loop Cosmology (2007)

Bojowald, Martin, Hernandez, Hector H., Kagan, Mikhail, Singh, Parampreet, Skirzewski, Aureliano

Inhomogeneous cosmological perturbation equations are derived in loop quantum gravity, taking into account corrections in particular in gravitational parts. This provides a framework for calculating...

Effective constraints of loop quantum gravity (2007)

Bojowald, Martin, Hernandez, Hector H., Kagan, Mikhail, Singh, Parampreet, Skirzewski, Aureliano

Within a perturbative cosmological regime of loop quantum gravity corrections to effective constraints are computed. This takes into account all inhomogeneous degrees of freedom relevant for scalar...

Loop quantum cosmology of k=1 FRW models (2006)

Ashtekar, Abhay, Pawlowski, Tomasz, Singh, Parampreet, Vandersloot, Kevin

The closed, k=1, FRW model coupled to a massless scalar field is investigated in the framework of loop quantum cosmology using analytical and numerical methods. As in the k=0 case, the scalar field...

Formation and Evolution of Structure in Loop Cosmology (2006)

Bojowald, Martin, Hernandez, Hector, Kagan, Mikhail, Singh, Parampreet, Skirzewski, Aureliano

Inhomogeneous cosmological perturbation equations are derived in loop quantum gravity, taking into account corrections in particular in gravitational parts. This provides a framework for calculating...

Hamiltonian cosmological perturbation theory with loop quantum gravity corrections (2006)

Bojowald, Martin, Hernández, Hector H., Kagan, Mikhail, Singh, Parampreet, Skirzewski, Aureliano

Cosmological perturbation equations are derived systematically in a canonical scheme based on Ashtekar variables. A comparison with the covariant derivation and various subtleties in the calculation...

Quantum Nature of the Big Bang: Improved dynamics (2006)

Ashtekar, Abhay, Pawlowski, Tomasz, Singh, Parampreet

An improved Hamiltonian constraint operator is introduced in loop quantum cosmology. Quantum dynamics of the spatially flat, isotropic model with a massless scalar field is then studied in detail...

Non-Singular Bouncing Universes in Loop Quantum Cosmology (2006)

Singh, Parampreet, Vandersloot, Kevin, Vereshchagin, G. V.

Non-perturbative quantum geometric effects in Loop Quantum Cosmology predict a $\rho^2$ modification to the Friedmann equation at high energies. The quadratic term is negative definite and can lead...

Avoidance of future singularities in loop quantum cosmology (2006)

Sami, M., Singh, Parampreet, Tsujikawa, Shinji

We consider the fate of future singularities in the effective dynamics of loop quantum cosmology. Non-perturbative quantum geometric effects which lead to $\rho^2$ modification of the Friedmann...

Quantum Nature of the Big Bang: An Analytical and Numerical Investigation (2006)

Ashtekar, Abhay, Pawlowski, Tomasz, Singh, Parampreet

Analytical and numerical methods are developed to analyze the quantum nature of the big bang in the setting of loop quantum cosmology. They enable one to explore the effects of quantum geometry both...

Loop cosmological dynamics and dualities with Randall-Sundrum braneworlds (2006)

Quantum Nature of the Big Bang (2006)

The discrete quantum geometric effects play an important role in dynamical evolution in the loop quantum cosmology. These effects which are significant at the high energies lead to the quadratic...

Ashtekar, Abhay, Pawlowski, Tomasz, Singh, Parampreet

Some long standing issues concerning the quantum nature of the big bang are resolved in the context of homogeneous isotropic models with a scalar field. Specifically, the known results on the...

Hamiltonian cosmological perturbation theory with loop quantum gravity corrections (2006)

Bojowald, Martin, Hernandez, Hector H., Kagan, Mikhail, Singh, Parampreet, Skirzewski, Aureliano

Cosmological perturbation equations are derived systematically in a canonical scheme based on Ashtekar variables. A comparison with the covariant derivation and various subtleties in the calculation...

Semi-classical States, Effective Dynamics and Classical Emergence in Loop Quantum Cosmology (2005)

Singh, Parampreet, Vandersloot, Kevin

We construct physical semi-classical states annihilated by the Hamiltonian constraint operator in the framework of loop quantum cosmology as a method of systematically determining the regime and...

Quantum evaporation of a naked singularity (2005)

Goswami, Rituparno, Joshi, Pankaj S., Singh, Parampreet

We investigate here quantum effects in gravitational collapse of a scalar field model which classically leads to a naked singularity. We show that non-perturbative semi-classical modifications near...

A black hole mass threshold from non-singular quantum gravitational collapse (2005)

Bojowald, Martin, Goswami, Rituparno, Maartens, Roy, Singh, Parampreet

Quantum gravity is expected to remove the classical singularity that arises as the end-state of gravitational collapse. To investigate this, we work with a toy model of a collapsing homogeneous...

Effective State Metamorphosis in Semi-Classical Loop Quantum Cosmology (2005)

A black hole mass threshold from non-singular quantum gravitational collapse (2005)

Modification to the behavior of geometrical density at short scales is a key result of loop quantum cosmology, responsible for an interesting phenomenology in the very early universe. We demonstrate...

Bojowald,Martin, Goswami,Rituparno, Maartens,Roy, Singh,Parampreet

Quantum gravity is expected to remove the classical singularity that arises as the end-state of gravitational collapse. To investigate this, we work with a simple toy model of a collapsing...

A black hole mass threshold from non-singular quantum gravitational collapse (2005)

Bojowald, Martin, Goswami, Rituparno, Maartens, Roy, Singh, Parampreet

Quantum gravity is expected to remove the classical singularity that arises as the end-state of gravitational collapse. To investigate this, we work with a simple toy model of a collapsing...

Semiclassical states, effective dynamics, and classical emergence in loop quantum cosmology (2005)

Singh, Parampreet, Vandersloot, Kevin

We construct physical semiclassical states annihilated by the Hamiltonian constraint operator in the framework of loop quantum cosmology as a method of systematically determining the regime and...

Coordinate time dependence in Quantum Gravity (2004)

Bojowald, Martin, Singh, Parampreet, Skirzewski, Aureliano

The intuitive classical space-time picture breaks down in quantum gravity, which makes a comparison and the development of semiclassical techniques quite complicated. Using ingredients of the group...

Loop Quantum Gravity and the Cyclic Universe (2004)

Bojowald, Martin, Maartens, Roy, Singh, Parampreet

Loop quantum gravity introduces strong non-perturbative modifications to the dynamical equations in the semi-classical regime, which are responsible for various novel effects, including resolution of...

Inflationary Cosmology and Quantization Ambiguities in Semi-Classical Loop Quantum Gravity (2004)

Bojowald, Martin, Lidsey, James E., Mulryne, David J., Singh, Parampreet, Tavakol, Reza

In loop quantum gravity, modifications to the geometrical density cause a self-interacting scalar field to accelerate away from a minimum of its potential. In principle, this mechanism can generate...

Inflationary Cosmology and Quantization Ambiguities in Semi-Classical Loop Quantum Gravity (2004)

Bojowald,Martin, Lidsey,James E., Mulryne,David J., Singh,Parampreet, Tavakol,Reza

In loop quantum gravity, modifications to the geometrical density cause a self-interacting scalar field to accelerate away from a minimum of its potential. In principle, this mechanism can generate...

Loop Quantum Gravity and the Cyclic Universe (2004)

Bojowald,Martin, Maartens,Roy, Singh,Parampreet

Loop quantum gravity introduces strong non-perturbative modifications to the dynamical equations in the semi-classical regime, which are responsible for various novel effects, including resolution of...

Time dependence in Quantum Gravity (2004)

Bojowald,Martin, Singh,Parampreet, Skirzewski,Aureliano

The intuitive classical space-time picture breaks down in quantum gravity, which makes a comparison and the development of semiclassical techniques quite complicated. By a variation of the group...

Inflationary Cosmology and Quantization Ambiguities in Semi-Classical Loop Quantum Gravity (2004)

Bojowald, Martin, Lidsey, James E., Mulryne, David J., Singh, Parampreet, Tavakol, Reza

In loop quantum gravity, modifications to the geometrical density cause a self-interacting scalar field to accelerate away from a minimum of its potential. In principle, this mechanism can generate...

Loop Quantum Gravity and the Cyclic Universe (2004)

Bojowald, Martin, Maartens, Roy, Singh, Parampreet

Loop quantum gravity introduces strong non-perturbative modifications to the dynamical equations in the semi-classical regime, which are responsible for various novel effects, including resolution of...

Time dependence in Quantum Gravity (2004)

Bojowald, Martin, Singh, Parampreet, Skirzewski, Aureliano

The intuitive classical space-time picture breaks down in quantum gravity, which makes a comparison and the development of semiclassical techniques quite complicated. By a variation of the group...

Coordinate time dependence in quantum gravity (2004)

Bojowald, Martin, Singh, Parampreet, Skirzewski, Aureliano

The intuitive classical space-time picture breaks down in quantum gravity, which makes a comparison and the development of semiclassical techniques quite complicated. Using ingredients of the group...

Big Crunch Avoidance in k = 1 Semi-Classical Loop Quantum Cosmology (2003)

Singh, Parampreet, Toporensky, Alexey

It is well known that a closed universe with a minimally coupled massive scalar field always collapses to a singularity unless the initial conditions are extremely fine tuned. We show that the...

Loop quantum gravity effects on inflation and the CMB (2003)

Tsujikawa, Shinji, Singh, Parampreet, Maartens, Roy

In loop quantum cosmology, the universe avoids a big bang singularity and undergoes an early and short super-inflation phase. During super-inflation, non-perturbative quantum corrections to the...

Action based approach to the dynamics of extended bodies in General Relativity (2003)

Anandan, Jeeva, Dadhich, Naresh, Singh, Parampreet

We present, for the first time, an action principle that gives the equations of motion of an extended body possessing multipole moments in an external gravitational field, in the weak field limit....

Cosmological Dynamics of Phantom Field (2003)

Singh, Parampreet, Sami, M., Dadhich, Naresh

We study the general features of the dynamics of the phantom field in the cosmological context. In the case of inverse coshyperbolic potential, we demonstrate that the phantom field can successfully...

Matter-Antimatter Asymmetry Generated by Loop Quantum Gravity (2003)

Lambiase, Gaetano, Singh, Parampreet

We show that Loop Quantum Gravity provides new mechanisms through which observed matter-antimatter asymmetry in the Universe can naturally arise at temperatures less than GUT scale. This is enabled...

Neutrino-Antineutrino Asymmetry around Rotating Black Holes (2003)

Mukhopadhyay, Banibrata, Singh, Parampreet

Propagation of fermion in curved space-time generates gravitational interaction due to the coupling between spin of the fermion and space-time curvature. This gravitational interaction, which is an...

Black holes as a source of neutrino asymmetry in Universe (2003)

Mukhopadhyay, Banibrata, Singh, Parampreet

Propagation of fermions in curved space-time generates gravitational interaction due to coupling of its spin with space-time curvature connection. This gravitational interaction, which is an...

Action principle formulation for motion of extended bodies in General Relativity (2002)

Anandan, Jeeva, Dadhich, Naresh, Singh, Parampreet

We present an action principle formulation for the study of motion of an extended body in General Relativity in the limit of weak gravitational field. This gives the classical equations of motion for...

Can brane cosmology with a vanishing \Lambda explain the observations? (2002)

Vishwakarma, R. G., Singh, Parampreet

A plethora of models of the universe have been proposed in recent years claiming that the present universe is accelerating, being driven by some hypothetical source with negative pressure...

Localized gravity on FRW branes (2002)

Brane curvature and supernovae Ia observations (2002)

We study the system of Schwarzschild anti de Sitter (S-AdS) bulk and FRW brane for localization of gravity; i.e. zero mass gravitons having ground state on the brane, and thereby recovering the...

Singh, Parampreet, Vishwakarma, R. G., Dadhich, Naresh

It is well known that modifications to the Friedmann equation on a warped brane in an anti de Sitter bulk do not provide any low energy distinguishing feature from standard cosmology. However,...

Localization of gravity in brane world cosmologies (2002)

Semi-classical States in the Context of Constrained Systems (2001)

The most remarkable and interesting feature of brane world scenario is the use of bulk's curvature to localize gravity on the brane, albeit with fine tuning of the brane and bulk parameters. For FRW...

Date, G., Singh, Parampreet

Algebraic quantization scheme has been proposed as an extension of the Dirac quantization scheme for constrained systems. Semi-classical states for constrained systems is also an independent and...

Non-conformally flat bulk spacetime and the 3-brane world (2001)

Field Theories from the Relativistic Law of Motion (2001)

We show that for non-conformally flat bulk spacetime, there exist no bound modes for zero mass graviton on the 3-brane. The brane world model is therefore unstable for the bulk spacetime being...

The field equation from Newton's law of motion and absence of magnetic monopole (1999)

From the relativistic law of motion we attempt to deduce the field theories corresponding to the force law being linear and quadratic in 4-velocity of the particle. The linear law leads to the vector...