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2.0

Jun 30, 2018
06/18

by
Niladri Paul; Saikat Nil Chakrabarty; Kaushik Bhattacharya

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The present work analyzes the various conditions in which there can be a bouncing universe solution in f(R) gravity. In the article an interesting method, to analyze the bouncing FRW solutions in a spatially flat universe using f(R) gravity models using an effective Einstein frame description of the process, is presented. The analysis shows that a cosmological bounce in the f(R) theory need not be described by an equivalent bounce in the Einstein frame description of the process where actually...

Topics: High Energy Astrophysical Phenomena, Astrophysics, General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1405.0139

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5.0

Jun 30, 2018
06/18

by
Dipanjan Dey; Kaushik Bhattacharya; Tapobrata Sarkar

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We study Bertrand space-times (BSTs), which have been proposed as viable models of space-times seeded by galactic dark matter, in modified theories of gravity. We first critically examine the issue of galactic rotation curves in General Relativity, and establish the usefulness of BSTs to fit experimental data in this context. We then study BSTs in metric $f(R)$ gravity and in Brans-Dicke theories. For the former, the nature of the Newtonian potential is established, and we also compute the...

Topics: High Energy Physics - Theory, Astrophysics of Galaxies, Astrophysics, General Relativity and...

Source: http://arxiv.org/abs/1407.0319

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Sep 22, 2013
09/13

by
Prashant Kumar; Kaushik Bhattacharya

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Bertrand's theorem in classical mechanics of the central force fields attracts us because of its predictive power. It categorically proves that there can only be two types of forces which can produce stable, circular orbits. In the present article an attempt has been made to generalize Bertrand's theorem to the central force problem of relativistic systems. The stability criterion for potentials which can produce stable, circular orbits in the relativistic central force problem has been deduced...

Source: http://arxiv.org/abs/1103.3338v1

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4.0

Mar 25, 2020
03/20

by
Ares J. Rosakis, Edward M. Stolper, Franklin Dean Thomas, Kaushik Bhattacharya, Diane Wallach, Jim Hall

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2.0

Jun 29, 2018
06/18

by
Phani Motamarri; Vikram Gavini; Kaushik Bhattacharya; Michael Ortiz

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We present a spectrum-splitting approach to conduct all-electron Kohn-Sham density functional theory (DFT) calculations by employing Fermi-operator expansion of the Kohn-Sham Hamiltonian. The proposed approach splits the subspace containing the occupied eigenspace into a core-subspace, spanned by the core eigenfunctions, and its complement, the valence-subspace, and thereby enables an efficient computation of the Fermi-operator expansion by reducing the expansion to the valence-subspace...

Topics: Computational Physics, Physics

Source: http://arxiv.org/abs/1608.07865

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2.0

Jun 30, 2018
06/18

by
Srivatsan Hulikal; Kaushik Bhattacharya; Nadia Lapusta

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We propose a statistical model for static and sliding friction between rough surfaces. Approximating the contact between rough surfaces by the contact of an ensemble of one-dimensional viscoelastic elements with a rough rigid surface, we study the collective behavior of the elements. We find that collective response of the contacts can lead to macroscopic behavior very different from the microscopic behavior. Specifically, various observed features of friction emerge as collective phenomena,...

Topics: Physics, Soft Condensed Matter, Classical Physics, Condensed Matter

Source: http://arxiv.org/abs/1405.3643

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2.0

Mar 25, 2020
03/20

by
Ares J. Rosakis, Edward M. Stolper, Franklin Dean Thomas, Kaushik Bhattacharya, Diane Wallach, Jim Hall

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2.0

Jun 30, 2018
06/18

by
Lincoln Collins; Kaushik Bhattacharya

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Fuel cells, batteries, thermochemical and other energy conversion devices involve the transport of a number of (electro-)chemical species through distinct materials so that they can meet and react at specified multi-material interfaces. Therefore, morphology or arrangement of these different materials can be critical in the performance of an energy conversion device. In this paper, we study a model problem motivated by a solar-driven thermochemical conversion device that splits water into...

Topics: Materials Science, Optimization and Control, Condensed Matter, Analysis of PDEs, Mathematics

Source: http://arxiv.org/abs/1702.00024

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2.0

Jun 30, 2018
06/18

by
Kaushik Bhattacharya; Joydeep Chakrabortty; Suratna Das; Tanmoy Mondal

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If the recent detection of $B-$mode polarization of the Cosmic Microwave Background by BICEP2 observations, withstand the test of time after the release of recent PLANCK dust polarisation data, then it would surprisingly put the inflationary scale near Grand Unification scale if one considers single-field inflationary models. On the other hand, Large Hadron Collider has observed the elusive Higgs particle whose presently observed mass can lead to electroweak vacuum instability at high scale...

Topics: High Energy Physics - Phenomenology, Astrophysics, General Relativity and Quantum Cosmology,...

Source: http://arxiv.org/abs/1408.3966

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2.0

Dec 16, 2019
12/19

by
Ares Rosakis, Kaushik Bhattacharya, Jim Hall, Diane Wallach, Thomas Rosenbaum

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1.0

Mar 25, 2020
03/20

by
Ares J. Rosakis, Edward M. Stolper, Franklin Dean Thomas, Kaushik Bhattacharya, Diane Wallach, Jim Hall

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2.0

Jun 29, 2018
06/18

by
Srivatsan Hulikal; Kaushik Bhattacharya; Nadia Lapusta

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We study the relation between a threshold-force based model at the microscopic scale and mode I fracture at the macroscopic scale in a system of discrete interacting springs. Specifically, we idealize the contact between two surfaces as that between a rigid surface and a collection of springs with long-range interaction and a constant tensile threshold force. We show that a particular scaling similar to that of crack-tip stress in Linear Elastic Fracture Mechanics leads to a macroscopic limit...

Topics: Soft Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1606.03166

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Sep 17, 2013
09/13

by
Carl D. Modes; Kaushik Bhattacharya; Mark Warner

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Nematic solids respond strongly to changes in ambient heat or light, significantly differently parallel and perpendicular to the director. This phenomenon is well characterized for uniform director fields, but not for defect textures. We analyze the elastic ground states of a nematic glass in the membrane approximation as a function of temperature for some disclination defects with an eye towards reversibly inducing three-dimensional shapes from flat sheets of material, at the nano-scale all...

Source: http://arxiv.org/abs/0912.2207v2

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3.0

Jun 29, 2018
06/18

by
Paul Plucinsky; Kaushik Bhattacharya

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Nematic elastomers are rubbery solids which have liquid crystals incorporated into their polymer chains. These materials display many unusual mechanical properties, one such being the ability to form fine-scale microstructure. In this work, we explore the response of taut and appreciably stressed sheets made of nematic elastomer. Such sheets feature two potential instabilities -- the formation of fine-scale material microstructure and the formation of fine-scale wrinkles. We develop a...

Topics: Soft Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1611.08621

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4.0

Jun 29, 2018
06/18

by
Barnali Das; Kaushik Bhattacharya

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If one assumes a particular form of non-minimal coupling, called the conformal coupling, of a perfect fluid with gravity in the fluid-gravity Lagrangian then one gets modified Einstein field equation. In the modified Einstein equation, the effect of the non-minimal coupling does not vanish if one works with spacetimes for which the Ricci scalar vanishes. In the present work we use the Schwarzschild metric in the modified Einstein equation, in presence of non-minimal coupling with a fluid, and...

Topics: High Energy Physics - Theory, General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1607.05637

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7.0

Jun 26, 2018
06/18

by
Pierluigi Cesana; Paul Plucinsky; Kaushik Bhattacharya

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We derive the effective energy density of thin membranes of liquid crystal elastomers as the Gamma-limit of a widely used bulk model. These membranes can display fine-scale features both due to wrinkling that one expects in thin elastic membranes and due to oscillations in the nematic director that one expects in liquid crystal elastomers. We provide an explicit characterization of the effective energy density of membranes and the effective state of stress as a function of the planar...

Topics: Mathematics, Analysis of PDEs

Source: http://arxiv.org/abs/1501.06859

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5.0

Jun 30, 2018
06/18

by
Kaushik Bhattacharya; Marta Lewicka; Mathias Schäffner

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We study the effective elastic behavior of incompatibly prestrained plates, where the prestrain is independent of thickness as well as uniform through the thickness. We model such plates as three-dimensional elastic bodies with a prescribed pointwise stress-free state characterized by a Riemannian metric $G$ with the above properties, and seek the limiting behavior as the thickness goes to zero. Our results extand the prior analysis in M. Lewicka, M. R. Pakzad ESAIM Control Optim. Calc. Var. 17...

Topics: Mathematics, Analysis of PDEs, Mathematical Physics

Source: http://arxiv.org/abs/1401.1609

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44

Sep 21, 2013
09/13

by
Kaushik Bhattacharya; Subhendra Mohanty; Raghavan Rangarajan

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If the initial state of the inflaton field is taken to have a thermal distribution instead of the conventional zero particle vacuum state then the curvature power spectrum gets modified by a temperature dependent factor such that the fluctuation spectrum of the microwave background radiation is enhanced at larger angles. We compare this modified cosmic microwave background spectrum with Wilkinson microwave anisotropy probe data to obtain an upper bound on the temperature of the inflaton at the...

Source: http://arxiv.org/abs/hep-ph/0508070v3

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Sep 22, 2013
09/13

by
Ashish Shukla; Kaushik Bhattacharya

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The Schr\"{o}dinger equation of a charged particle in a uniform electric field can be specified in either a time-independent or a time-dependent gauge. The wave-function solutions in these two gauges are related by a phase-factor reflecting the gauge symmetry of the problem. In this article we show that the effect of such a gauge transformation connecting the two wave-functions can be mimicked by the effect of two successive extended Galilean transformations connecting the two...

Source: http://arxiv.org/abs/0908.1276v1

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3.0

Jun 29, 2018
06/18

by
Paul Plucinsky; Marius Lemm; Kaushik Bhattacharya

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Nematic elastomers and glasses are solids that display spontaneous distortion under external stimuli. Recent advances in the synthesis of sheets with controlled heterogeneities have enabled their actuation into non-trivial shapes with unprecedented energy density. Thus, these have emerged as powerful candidates for soft actuators. To further this potential, we introduce the key metric constraint which governs shape changing actuation in these sheets. We then highlight the richness of shapes...

Topics: Soft Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1605.02681

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Sep 20, 2013
09/13

by
Dilip Angom; Kaushik Bhattacharya; Saurabh D. Rindani

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Yang's theorem states that an initial J=1 state cannot decay into two photons. Because of this result some reactions relating to elementary particles or atomic transitions can be ruled out. The theorem is not valid in the presence of background electric or magnetic fields. In this work we show that the decay of a J=1 particle into two photons is permitted by Bose symmetry and rotational invariance when the background of the decay process is not pure vacuum but contains an external classical...

Source: http://arxiv.org/abs/hep-ph/0601168v1

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Sep 18, 2013
09/13

by
Utpal Roy; Suranjana Ghosh; T. Shreecharan; Kaushik Bhattacharya

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In quantum mechanics textbooks the momentum operator is defined in the Cartesian coordinates and rarely the form of the momentum operator in spherical polar coordinates is discussed. Consequently one always generalizes the Cartesian prescription to other coordinates and falls in a trap. In this work we introduce the difficulties one faces when the question of the momentum operator in spherical polar coordinate comes. We have tried to point out most of the elementary quantum mechanical results,...

Source: http://arxiv.org/abs/0704.0373v1

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Sep 20, 2013
09/13

by
Kaushik Bhattacharya; Subhendra Mohanty; Akhilesh Nautiyal

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If inflation was preceded by a radiation era then at the time of inflation there will exist a decoupled thermal distribution of gravitons. Gravitational waves generated during inflation will be amplified by the process of stimulated emission into the existing thermal distribution of gravitons. Consequently the usual zero temperature scale invariant tensor spectrum is modified by a temperature dependent factor. This thermal correction factor amplify the $B$-mode polarization of the CMB by an...

Source: http://arxiv.org/abs/astro-ph/0607049v3

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Sep 20, 2013
09/13

by
Kaushik Bhattacharya; Narendra Sahu; Utpal Sarkar; Santosh K. Singh

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An attractive explanation for non-zero neutrino masses and small matter antimatter asymmetry of the present Universe lies in "leptogenesis". At present the {\it size} of the lepton asymmetry is precisely known, while the {\it sign} is not known yet. In this work we determine the sign of this asymmetry in the framework of two right handed neutrino models by relating the leptogenesis phase(s) with the low energy CP violating phases appearing in the leptonic mixing matrix. It is shown...

Source: http://arxiv.org/abs/hep-ph/0607272v2

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Sep 17, 2013
09/13

by
Alberto Bravo Garcia; Kaushik Bhattacharya; Sarira Sahu

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In this talk we present the calculation of the neutrino self-energy in presence of a magnetized medium. The magnetized medium consists of electrons, positrons, neutrinos and a uniform classical magnetic field. The background magnetic field is assumed to be weak compared to the $W$-Boson mass as a consequence of which only linear order corrections in the field are included in the $W$ boson propagator. The electron propagator consists all order corrections in the background field. Our calculation...

Source: http://arxiv.org/abs/0711.2046v2

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Sep 21, 2013
09/13

by
Kaushik Bhattacharya; Yi-Fu Cai; Suratna Das

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The present article discusses about the effect of a Lee-Wick partner infested radiation phase of the early universe. As Lee-Wick partners can contribute negative energy density so it is always possible that at some early phase of the universe when the Lee-Wick partners were thermalized the total energy density of the universe became very small making the effective Hubble radius very big. This possibility gives rise to the probability of a bouncing universe. As will be shown in the article that...

Source: http://arxiv.org/abs/1301.0661v2

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47

Sep 21, 2013
09/13

by
Kaushik Bhattacharya; Suratna Das

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It was pointed out some time ago that there can be two variations in which the divergences of a quantum field theory can be tamed using the ideas presented by Lee and Wick. In one variation the Lee-Wick partners of the normal fields live in an indefinite metric Hilbert space but have positive energy and in the other variation the Lee-Wick partners can live in a normal Hilbert space but carry negative energy. Quantum mechanically the two variations mainly differ in the way the fields are...

Source: http://arxiv.org/abs/1108.0483v2

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Sep 20, 2013
09/13

by
Kaushik Bhattacharya; C. R. Das; Bipin R. Desai; G. Rajasekaran; Utpal Sarkar

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In this work we study an SO(10) GUT model with minimum Higgs representations belonging only to the 210 and 16 dimensional representations of SO(10). We add a singlet fermion S in addition to the usual 16 dimensional representation containing quarks and leptons. There are no Higgs bi-doublets and so charged fermion masses come from one-loop corrections. Consequently all the fermion masses, Dirac and Majorana, are of the see-saw type. We minimize the Higgs potential and show how the left-right...

Source: http://arxiv.org/abs/hep-ph/0601170v3

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Jun 27, 2018
06/18

by
Debajyoti Sarkar; Niladri Paul; Kaushik Bhattacharya; Tarun Kanti Ghosh

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In this article we present an effective Hamiltonian approach for Discrete Time Quantum Random Walk. A form of the Hamiltonian for one dimensional quantum walk has been prescribed, utilizing the fact that Hamiltonians are the generators of time translations. Then an attempt has been made to generalize the techniques to higher dimensions. We find that the Hamiltonian can be written as the sum of a Weyl Hamiltonian and a Dirac comb potential. The time evolution operator obtained from this...

Topic: Quantum Physics

Source: http://arxiv.org/abs/1505.01435

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Sep 19, 2013
09/13

by
Kaushik Bhattacharya; Palash B. Pal

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We calculate the cross section of the inverse beta decay process, $\nu_e+n\to p+e$, in a magnetic field which is much smaller than $m_p^2/e$. Using exact solutions of the Dirac equation in a constant magnetic field, we find that the cross section depends on the direction of the incident neutrino even when the initial neutron is assumed to be at rest. We discuss the implication of this result for pulsar kicks.

Source: http://arxiv.org/abs/hep-ph/9911498v2

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51

Sep 22, 2013
09/13

by
Kaushik Bhattacharya; Sarira Sahu

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In this work we calculate the decay rate of the electron type neutrinos into $W$ bosons and electrons in presence of an external uniform magnetic field. The decay rate is calculated from the imaginary part of the $W$ exchange neutrino self-energy diagram but in the weak field limit and compare our result with the existing one.

Source: http://arxiv.org/abs/0811.1692v1

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Jul 20, 2013
07/13

by
Kaushik Bhattacharya; Suratna Das

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The present article is about the statistical mechanics of non-trivial field configurations. The non-trivial fields arise from the negative sign of the commutators and the anticommutators of the bosonic and fermionic field excitations. These kinds of fields were previously studied by Pauli and Lee and Wick. The thermal distribution function of the above mentioned fields are calculated in the article and using the thermal distribution functions the energy density, pressure and entropy density of...

Source: http://arxiv.org/abs/1007.1537v2

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Sep 18, 2013
09/13

by
Kaushik Bhattacharya

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In this work we discuss the properties of the solutions of the Dirac equation in presence of an uniform background magnetic field. In particular we focus on the nature of the solutions, their ortho-normality properties and how these solutions depend on the choice of the vector potential giving rise to the magnetic field. We explicitly calculate the spin-sum of the solutions and using it we calculate the propagator of the electron in presence of an uniform background magnetic field.

Source: http://arxiv.org/abs/0705.4275v2

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Sep 21, 2013
09/13

by
Pratim Roy; Tarun Kanti Ghosh; Kaushik Bhattacharya

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The present article discusses magnetic confinement of the Dirac excitations in graphene in presence of inhomogeneous magnetic fields. In the first case a magnetic field directed along the z axis whose magnitude is proportional to $1/r$ is chosen. In the next case we choose a more realistic magnetic field which does not blow up at the origin and gradually fades away from the origin. The magnetic fields chosen do not have any finite/infinite discontinuity for finite values of the radial...

Source: http://arxiv.org/abs/1108.1907v2

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Jul 20, 2013
07/13

by
Shuman Xia; Laurent Ponson; Guruswami Ravichandran; Kaushik Bhattacharya

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The effective adhesive properties of heterogeneous thin films are characterized through a combined experimental and theoretical investigation. By bridging scales, we show how variations of elastic or adhesive properties at the microscale can significantly affect the effective peeling behavior of the adhesive at the macroscale. Our study reveals three elementary mechanisms in heterogeneous systems involving front propagation: (i) patterning the elastic bending stiffness of the film produces...

Source: http://arxiv.org/abs/1203.3634v1

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Jul 20, 2013
07/13

by
Kaushik Bhattacharya; Avijit K. Ganguly; Sushan Konar

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Neutrino-photon processes, forbidden in vacuum, can take place in presence of a thermal medium or an external electro-magnetic field, mediated by the corresponding charged leptons (real or virtual). The effect of a medium or an electromagnetic field is two-fold - to induce an effective $\nu-\gamma$ vertex and to modify the dispersion relations of all the particles involved to render the processes kinematically viable. It has already been noted that in presence of a thermal medium such an...

Source: http://arxiv.org/abs/hep-ph/0107259v2

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Sep 18, 2013
09/13

by
Kaushik Bhattacharya; Palash B. Pal

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Neutrinos have no electric charge, but a magnetic field can indirectly affect neutrino properties and interactions through its effect on charged particles. After a brief field-theoretic discussion of charged particles in magnetic fields, we discuss two broad kinds of magnetic field effects on neutrinos. First, effects which come through virtual charged particles and alter neutrino properties. Second, effects which alter neutrino interactions through charged particles in the initial or final...

Source: http://arxiv.org/abs/hep-ph/0212118v3

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Sep 21, 2013
09/13

by
Alberto Bravo Garcia; Kaushik Bhattacharya; Sarira Sahu

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In this work we calculate the neutrino self-energy in presence of a magnetized medium. The magnetized medium consists of electrons, positrons, neutrinos and a uniform classical magnetic field. The calculation is done assuming the background magnetic field is weak compared to the $W$-Boson mass squared, as a consequence of which only linear order corrections in the field are included in the $W$ boson propagator. The electron propagator consists all order corrections in the background field....

Source: http://arxiv.org/abs/0706.3921v3

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Sep 21, 2013
09/13

by
Kaushik Bhattacharya

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The article focuses on the issue of the two definitions of charge, mainly the gauge charge and the effective charge of fundamental particles. Most textbooks on classical electromagnetism and quantum field theory only works with the gauge charges while the concept of the induced charge remains unattended. In this article it has been shown that for intrinsically charged particles both of the charges remain the same but there can be situations where an electrically neutral particle picks up some...

Source: http://arxiv.org/abs/0905.4380v1

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Sep 19, 2013
09/13

by
Kaushik Bhattacharya; Palash B. Pal

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We calculate the cross section of the inverse beta decay process, $\nu_e+n\to p+e$, in a background magnetic field which is much smaller than $m_p^2/e$. Using exact solutions of the Dirac equation in a constant magnetic field, we find the cross section for arbitrary polarization of the initial neutrons. The cross section depends on the direction of the incident neutrino even when the initial neutron is assumed to be at rest and has no net polarization. Possible implications of the result are...

Source: http://arxiv.org/abs/hep-ph/0209053v2

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Sep 21, 2013
09/13

by
Utpal Roy; Suranjana Ghosh; Kaushik Bhattacharya

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In quantum mechanics textbooks the momentum operator is defined in the Cartesian coordinates and rarely the form of the momentum operator in spherical polar coordinates is discussed. Consequently one always generalizes the Cartesian prescription to other coordinates and falls in a trap. In this work we introduce the difficulties one faces when the question of the momentum operator in general curvilinear coordinates arises. We have tried to elucidate the points related to the definition of the...

Source: http://arxiv.org/abs/0706.0924v2

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Sep 21, 2013
09/13

by
Kaushik Bhattacharya

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The thesis deals with the effect of magnetic fields on elementary particle interactions, of which the neutrino is of prime concern. The initial part focuses on the quantum field theoretical description of scattering processes which involves charged particles, in presence of a background uniform magnetic field. A brief discussion on the charged particle propagators in an uniform background magnetic field using Schwinger's method is presented. A general analysis on neutrino self-energy in a...

Source: http://arxiv.org/abs/hep-ph/0407099v1

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Sep 23, 2013
09/13

by
Kaushik Bhattacharya

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Elementary particle scatterings and decays in presence of a background magnetic field are very common in physics, specially after the observation that the core of the neutron stars can sustain a magnetic field of the order of $10^{13} {\rm G}$. The important point about these calculations is that they are done in a background of a gauge field and as a result the calculations are prone to gauge arbitrariness. In this work we will investigate how this gauge arbitrariness is eradicated in...

Source: http://arxiv.org/abs/hep-ph/0510280v1

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Sep 19, 2013
09/13

by
Kaushik Bhattacharya; Avijit K. Ganguly

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In the presence of a thermal medium or an external electro-magnetic field, neutrinos can interact with photon, mediated by the corresponding charged leptons (real or virtual). The effect of a medium or an electromagnetic field is two-fold - to induce an effective $\nu \gamma$ vertex and to modify the dispersion relations of all the particles involved to render the processes kinematically viable. It has already been noted that in a medium neutrinos acquire an effective charge, which in the...

Source: http://arxiv.org/abs/hep-ph/0209236v1

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Sep 22, 2013
09/13

by
Kaushik Bhattacharya; Palash B. Pal

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We show that neutrino cross sections are direction dependent in a background magnetic field.

Source: http://arxiv.org/abs/hep-ph/0001077v1

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Jul 20, 2013
07/13

by
Kaushik Bhattacharya; Suratna Das

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In the present article the thermodynamic results of the Lee-Wick partner infested universe have been applied in a toy model where there is one Lee-Wick partner to each of the standard model particle and more over the longitudinal degrees of freedom of the massive partners of the standard massless gauge bosons are neglected at high temperatures. For practical purposes, the chiral fermionic sector of Lee-wick theories requires two Lee-Wick partners per fermion which opens up the possibility for a...

Source: http://arxiv.org/abs/1203.1109v2

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Sep 23, 2013
09/13

by
Biplab Dutta; Kaushik Bhattacharya

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Glashow and Cohen claim that many results of special theory of relativity (SR) like time dilation, relativistic velocity addition, etc, can be explained by using certain proper subgroups, of the Lorentz group, which collectively form the main body of Very special relativity (VSR). They did not mention about length contraction in VSR. Length contraction in VSR has not been studied at all. In this article we calculate how the length of a moving rod contracts in VSR, particularly in the HOM(2)...

Source: http://arxiv.org/abs/1105.4219v1

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Jun 28, 2018
06/18

by
Kaushik Bhattacharya; Saikat Chakrabarty

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In this paper we present the techniques for computing cosmological bounces in polynomial $f(R)$ theories, whose order is more than two, for spatially flat FLRW spacetime. In these cases the conformally connected Einstein frame shows up multiple scalar potentials predicting various possibilities of cosmological evolution in the Jordan frame where the $f(R)$ theory lives. We present a reasonable way in which one can associate the various possible potentials in the Einstein frame, for cubic $f(R)$...

Topics: General Relativity and Quantum Cosmology, Cosmology and Nongalactic Astrophysics, Astrophysics,...

Source: http://arxiv.org/abs/1509.01835

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62

Sep 22, 2013
09/13

by
Kaushik Bhattacharya; Avijit K. Ganguly

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To one loop the effective neutrino photon interaction takes place through the vector-vector type and the axialvector-vector type amplitude. In this work we explicitly write down the form of the axialvector-vector amplitude to all orders in the external magnetic field in a medium. We then infer upon its zero external momentum limit which contributes to the effective charge of the neutrinos inside a magnetized medium. We further show its gauge invariance properties.

Source: http://arxiv.org/abs/hep-ph/0308063v1

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Sep 23, 2013
09/13

by
Laurent Ponson; Kenneth Diest; Harry Atwater; Guruswami Ravichandran; Kaushik Bhattacharya

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We investigate the origin of undesirable transverse cracks often observed in thin films obtained by the layer transfer technique. During this process, two crystals bonded to each other containing a weak plan produced by ion implantation are heated to let a thin layer of one of the material on the other. The level of stress imposed on the film during the heating phase due to the mismatch of thermal expansion coefficients of the substrate and the film is shown to be the relevant parameter of the...

Source: http://arxiv.org/abs/0810.5053v1