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B. Basu

Publications and source records attributed to B. Basu.

At least 37 records · Page 2Linked to original sources
arXiv2010

Mutated Hilltop Inflation : A Natural Choice for Early Universe

We propose a model of inflation with a suitable potential for a single scalar field which falls in the wide class of hilltop inflation. We derive the analytical expressions for most of the physical quantities related to inflation and show that all of them represent the true behavior as required from a model of inflation. We further subject the results to observational verification by formulating the theory of perturbations based on our model followed by an estimation for the values of those observable parameters. Our model is found to be in excellent agreement with observational data. Thus, the features related to the model leads us to infer that this type of hilltop inflation may be a natural choice for explaining the early universe.

hep-th↗
arXiv2010

The Morphology of Urban Agglomerations for Developing Countries: A Case Study with China

In this article, the relationship between two well-accepted empirical propositions regarding the distribution of population in cities, namely, Gibrat's law and Zipf's law, are rigorously examined using the Chinese census data. Our findings are quite in contrast with the most of the previous studies performed exclusively for developed countries. This motivates us to build a general environment to explain the morphology of urban agglomerations both in developed and developing countries. A dynamic process of job creation generates a particular distribution for the urban agglomerations and introduction of Special Economic Zones (SEZ) in this abstract environment shows that the empirical observations are in good agreement with the proposed model.

physics.soc-ph↗
arXiv2010

City Size Distributions For India and China

This paper studies the size distributions of urban agglomerations for India and China. We have estimated the scaling exponent for the Zipf's law with the Indian census data for the years of 1981-2001 and the Chinese census data for 1990 and 2000. Along with the biased linear fit estimate, the maximum likelihood estimate for the Pareto and Tsallis q-exponential distribution has been computed. For India, the scaling exponent is in the range of [1.88, 2.06] and for China, it is in the interval [1.82, 2.29]. The goodness-of-fit tests of the estimated distributions are performed using the Kolmogorov-Smirnov statistic.

physics.soc-ph↗
arXiv2008

Multi-pronged events from Coulomb fission of nuclei at very low energies

Multi-pronged tracks have been recorded in the polyethylene terephthalate (C$_{10}$H$_8$O$_4$)$_n$ solid state nuclear track detector by exposure to a $^{252}$Cf fission source. After chemical etching, two-prong to six-pronged tracks along with single tracks have been observed under the optical microscope. We carried out a systematic study to understand the origin of the prongs. The track detectors were coated with metals (Cu, Ag and Pb) and were exposed to $^{252}$Cf source. After chemical etching two-prong to four pronged tracks were observed in each plate. We believe that at this very low energy of the order of 1 MeV/A, Coulomb fission is the only plausible explanation for the origin of such multi-pronged tracks.

nucl-ex↗
arXiv2008

Spin-Orbit gauge and quantum spin Hall effect

We have shown that the non-Abelian spin-orbit gauge field strength of the Rashba and Dresselhaus interactions, when split into two Abelian field strengths, the Hamiltonian of the system can be re-expressed as a Landau level problem with a particular relation between the two coupling parameters. The quantum levels are created with up and down spins with opposite chirality and leads to the quantum spin Hall effect.

cond-mat.mes-hall↗
arXiv2008

On atomic analogue of Landau quantization

We have studied the physics of atoms with permanent electric dipole moment and non vanishing magnetic moment interacting with an electric field and inhomogeneous magnetic field. This system can be demonstrated as the atomic analogue of Landau quantization of charged particles in a uniform magnetic field. This Landau-like atomic problem is also studied with space-space noncommutative coordinates.

cond-mat.mes-hall↗
arXiv2007

Spin Entanglement of Two delocalised Fermions and Berry Phase

We have studied the entanglement of identical fermions in two spatial regions in terms of the Berry phase acquired by their spins. The analysis is done from the viewpoint of the geometrical interpretation of entanglement, where a fermion is visualized as a scalar particle attached with a magnetic flux quantum. The quantification of spin entanglement in terms of their Berry phases is novel and generalises the relationship between the entanglement of distinguishable spins and that of delocalised fermions.

quant-ph↗
arXiv2007

Spin Hall Effect For Anyons

We explain the intrinsic spin Hall effect from generic anyon dynamics in the presence of external electromagnetic field. The free anyon is represented as a spinning particle with an underlying non-commutative configuration space. The Berry curvature plays a major role in the analysis.

cond-mat.mes-hall↗
arXiv2007

A Geometrical Approach towards Entanglement

We have studied the concurrence of two-site entanglement and have shown that it is related to the geometric phase accumulated due to a complete rotation of the entangled state. The geometric phase and hence the concurrence is evaluated for transverse Ising model and antiferromagnetic chain which is found to be in good agreement with that obtained by other methods.

quant-ph↗
arXiv2007

The Berry phase in ferromagnetic spin systems and anomalous Hall Effect

We have shown that the study of topological aspects of the underlying geometry in a ferromagnetic spin system gives rise to an intrinsic Berry phase. This real space Berry phase arises due to the spin rotations of conducting electrons which can be manifested as a further contribution in anomalous Hall effect.

cond-mat.mes-hall↗
arXiv2006

Noncommutative Geometry and Geometric Phases

We have studied particle motion in generalized forms of noncommutative phase space, that simulate monopole and other forms of Berry curvature, that can be identified as effective internal magnetic fields, in coordinate and momentum space. The Ahranov-Bohm effect has been considered in this form of phase space, with operatorial structures of noncommutativity. Physical significance of our results are also discussed.

hep-th↗
arXiv2005

Charge and Statistics of Quasiparticles in Fractional Quantum Hall Effec

We have studied here the charge and statistics of quasiparticle excitations in FQH states on the basis of the Berry phase approach incorporating the fact that even number of flux quanta can be gauged away when the Berry phase is removed to the dynamical phase. It is observed that the charge $q$ and statistical parameter $θ$ of a quasiparticle at filling factor $ν=\frac{n}{2pn+1}$ are given by $q=(\frac{n}{2pn+1})e$ and $θ=\frac{n}{2pn+1}$, with the fact that the charge of the quasihole is opposite to that of the quasielectron. Using Laughlin wave function for quasiparticles, numerical studies have been done following the work of Kjønsberg and Myrheim \cite{KM} for FQH states at $ν=1/3$ and it is pointed out that as in case of quasiholes, the statistics parameter can be well defined for quasielectrons having the value $θ=1/3$.

cond-mat.mes-hall↗
arXiv2005

Quantum Hall Effect In Bilayer Systems And The Noncommutative Plane: A Toy Model Approach

We have presented a quantum mechanical toy model for the study of Coulomb interactions in Quantum Hall (QH) system. Inclusion of Coulomb interaction is essential for the study of {\it{bilayer}} QH system and our model can simulate it, in the compound state, in a perturbative framework. We also show that in the noncommutative plane, the Coulomb interaction is modified at a higher order in the noncommutativity parameter $θ$, and only if $θ$ varies from layer to layer in the QH system.

cond-mat.mes-hall↗
arXiv2004

Statistics of Quasiparticles in Fractional Quantum Hall States

We have considered here the statistics parameter for quasiparticles in FQH states from an analysis of these states in the framework of chiral anomaly and Berry phase. It is shown that we have a generalized relation such that the statistical phase of a quasiparticle for FQH states at $ν=p/q$ with $p(q)$ even or odd, is given by $e^{iπθ}$ with $θ=p/q $ and the charge is $-e \frac{p}{q}$. The statistics parameter for a quasihole is identical with that of a quasiparticle and the charge is of opposite sign.

cond-mat.mes-hall↗
arXiv2004

Fractional Quantum Hall Edge Electrons, Chiral Anomaly and the Berry Phase

It is shown that the deviation of fractional quantum Hall edge fluid from power law correlation functions with universal exponent $α=1/ν$ as observed in recent experiment may be explained when analyzed from the viewpoint of chiral anomaly and Berry phase. It is observed that at the edge anomaly vanishes and this induces a nonlocal effect in the construction of the electron creation operator in terms of the edge boson fields. This nonlocality is responsible for the deviation of the power law exponent from $α=1/ν$ of the edge fluid. There are gapless edge excitations described by chiral boson fields and the number of branches of chiral boson fields can be related to the polarization states of electrons in the bulk. We have noted that for fully polarized state at $ν=\frac{1}{2m \pm 1}$ we will have a single branch whereas for partially polarized state at $ν=\frac{n}{2mn \pm 1}$, with $n >1$ and odd, we will have $n$ branches. However for unpolarized state at $ν=\frac{n}{2mn \pm 1}$ with $n$ even we will have two branches.

cond-mat.mes-hall↗
arXiv2004

High $T_c$ Superconductivity, Skyrmions and the Berry Phase

It is here pointed out that the antiferromagnetic spin fluctuation may be associated with a gauge field which gives rise to the antiferromagnetic ground state chirality. This is associated with the chiral anomaly and Berry phase when we consider the two dimensional spin system on the surface of a 3D sphere with a monopole at the centre. This realizes the RVB state where spinons and holons can be understood as chargeless spins and spinless holes attached with magnetic flux. The attachment of the magnetic flux of the charge carrier suggest, that this may be viewed as a skyrmion. The interaction of a massless fermion representing a neutral spin with a gauge field along with the interaction of a spinless hole with the gauge field enhances the antiferromagnetic correlation along with the pseudogap at the underdoped region. As the doping increases the antiferromagnetic long range order disappears for the critical doping parameter $δ_{sc}$. In this framework, the superconducting pairing may be viewed as caused by skyrmion-skyrmion bound states.

cond-mat.supr-con↗