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Mallick R.,Institute of Physics, Bhubaneswar
Physical Review C - Nuclear Physics | Year: 2013

Recent observation of pulsar PSR J1614-2230 with a mass of about two solar masses poses a severe constraint on the equations of state (EOSs) of matter describing stars under extreme conditions. Neutron stars (NSs) can reach the mass limit set by PSR J1614-2230, but stars having hyperons or quark stars (QSs) having boson condensates, with softer EOSs, can barely reach such limit and are ruled out. QSs with pure strange matter cannot attain such high mass unless the effect of strong coupling constants or color superconductivity are considered. In this work I calculate the upper mass limit for a hybrid star (HS) having a quark-hadron mixed phase. The hadronic matter (having hyperons) EOS is described by relativistic mean field theory and the quark matter EOS is modeled according to the Massachusetts Institute of Technology bag model. The intermediate mixed phase is constructed using the Glendenning prescription. A HS with a mixed phase cannot reach the mass limit set by PSR J1614-2230 unless one assumes a density-dependent bag constant. However, for such case the mixed-phase region is small. The maximum mass of a mixed hybrid star obtained with such a mixed-phase region is 2.01M⊙. A stiffer hadronic EOS can raise the maximum mass of a mixed HS to 2.1 M⊙. © 2013 American Physical Society.

Pareek Y.,Indian Institute of Technology Bombay | Ravikanth M.,Indian Institute of Technology Bombay | Chandrashekar T.K.,Institute of Physics, Bhubaneswar
Accounts of Chemical Research | Year: 2012

Porphyrins are tetrapyrrolic 18 π electron conjugated macrocycles with wide applications that range from materials to medicine. Expanded porphyrins, synthetic analogues of porphyrins that contain more than 18 π electrons in the conjugated pathway, have an increased number of pyrroles or other heterocyles or multiple meso-carbon bridges. The expanded porphyrins have attracted tremendous attention because of unique features such as anion binding or transport that are not present in porphyrins. Expanded porphyrins exhibit wide applications that include their use in the coordination of large metal ions, as contrasting agents in magnetic resonance imaging (MRI), as sensitizers for photodynamic therapy (PDT) and as materials for nonlinear optical (NLO) studies. Pentaphyrin 1, sapphyrin 2, and smaragdyrin 3 are expanded porphyrins that include five pyrroles or heterocyclic rings. They differ from each other in the number of bridging carbons and direct bonds that connect the five heterocyclic rings. Sapphyrins were the first stable expanded porphyrins reported in the literature and remain one of the most extensively studied macrocycles. The strategies used to synthesize sapphyrins are well established, and these macrocycles are versatile anion binding agents. They possess rich porphyrin-like coordination chemistry and have been used in diverse applications.This Account reviews developments in smaragdyrin chemistry. Although smaragdyrins were discovered at the same time as sapphyrins, the chemistry of smaragdyrins remained underdeveloped because of synthetic difficulties and their comparative instability. Earlier efforts resulted in the isolation of stable β-substituted smaragdyrins and meso-aryl isosmaragdyrins. Recently, researchers have synthesized stable meso-aryl smaragdyrins by [3 + 2] oxidative coupling reactions. These results have stimulated renewed research interest in the exploration of these compounds for anion and cation binding, energy transfer, fluorescent sensors, and their NLO properties. Recently reported results on smaragdyrin macrocycles have set the stage for further synthetic studies to produce stable meso-aryl smaragdyrins with different inner cores to study their properties and potential for various applications. © 2012 American Chemical Society.

Maharana J.,Institute of Physics, Bhubaneswar
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We study duality and local symmetries of closed bosonic string from the perspectives of worldsheet approach in the phase space path integral formalism. It is shown that the Ward identities reflecting the local symmetries associated with massless excitations such as graviton and antisymmetric tensor can be cast in a duality covariant form. It is shown how the manifestly O(d,d) invariant Hamiltonian can be obtained in the Hassan-Sen toroidal compactification scheme, d being the number of compact dimensions. It is proposed that massive excited states possess a T-duality symmetry for constant (tensor) backgrounds. This conjecture is verified for the first massive level. © 2010 Elsevier B.V.

Maharana J.,Institute of Physics, Bhubaneswar
Nuclear Physics B | Year: 2011

We present evidence for the target space duality symmetry associated with massive excited states of closed bosonic string. The evolution of string is considered in D̂ spacetime dimensions; out of which d spacial dimensions are compactified on torus. The phase space Hamiltonian formulation is adopted to unveil the T-duality symmetry from the worldsheet perspective. The existence of this symmetry is verified for a few massive levels. A systematic procedure is presented to study T-duality symmetry of vertex operators for all massive levels of closed bosonic string. It is argued that all vertex operators corresponding to excited massive states can be cast in an O(d,d) invariant form where d is the number of compact dimensions. © 2010 Elsevier B.V.

Chakrabortty S.,Institute of Physics, Bhubaneswar
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

Within the finite temperature N=4 strongly coupled super-Yang-Mills, we compute the dissipative force on an external quark in the presence of evenly distributed heavy quark cloud. This is computed holographically by constructing the corresponding gravity dual. We study the behaviour of this force as a function of the cloud density. Along the way we also analyze the stability of the gravity dual for vector and tensor perturbations. © 2011 Elsevier B.V.

Agrawal P.,Institute of Physics, Bhubaneswar | Shivaji A.,Harish Chandra Research Institute
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

We study the associated production of an electroweak vector boson and the Higgs boson with a jet via gluon-gluon fusion. At the leading order, these processes occur at one-loop level. The amplitudes of these one-loop processes are gauge invariant and finite. Therefore, their contributions towards the corresponding hadronic cross sections and kinematic distributions can be calculated separately. We present results for the Large Hadron Collider and its discussed upgrades. We find that the gluon-gluon one-loop process gives dominant contribution to the γHj production. We observe a destructive interference effect in the gg→. ZHj amplitude. We also find that in the high transverse momentum and central rapidity region, the ZHj production cross section via gluon-gluon fusion becomes comparable to the cross section contributions coming from quark-quark and quark-gluon channels. © 2014 The Authors.

Dash T.K.,Institute of Physics, Bhubaneswar | Konkimalla V.B.,Institute of Physics, Bhubaneswar
Journal of Controlled Release | Year: 2012

Biodegradable polymer based novel drug delivery systems have provided many avenues to improve therapeutic efficacy and pharmacokinetic parameters of medicinal entities. Among synthetic biodegradable polymer, poly-ε- caprolactone (PCL) is a polymer with very low glass transition temperature and melting point. Owing to its amicable nature and tailorable properties it has been trialed in almost all novel drug delivery systems and tissue engineering application in use/investigated so far. This review aims to provide an up to date of drugs incorporated in different PCL based formulations, their purpose and brief outcomes. Demonstrated PCL formulations with or without drugs, intended for drug delivery and/or tissue engineering application such as microsphere, nanoparticles, scaffolds, films, fibers, micelles etc. are categorized based on method of preparation. © 2011 Elsevier B.V. All rights reserved.

Maharana J.,Institute of Physics, Bhubaneswar
International Journal of Modern Physics A | Year: 2013

The purpose of this paper is to present a pedagogical review of T-duality in string theory. The evolution of the closed string is envisaged on the worldsheet in the presence of its massless excitations. The duality symmetry is studied when some of the spacial coordinates are compactified on d-dimensional torus, Td. The known results are reviewed to elucidate that equations of motion for the compact coordinates are O(d, d) covariant, d being the number of compact directions. Next, the vertex operators of excited massive levels are considered in a simple compactification scheme. It is shown that the vertex operators for each massive level can be cast in a T-duality invariant form in such a case. Subsequently, the duality properties of superstring is investigated in the NSR formulation for the massless backgrounds such as graviton and antisymmetric tensor. The worldsheet superfield formulation is found to be very suitable for our purpose. The Hassan-Sen compactification is adopted and it is shown that the worldsheet equations of motion for compact superfields are O(d, d) covariant when the backgrounds are independent of superfields along compact directions. The vertex operators for excited levels are presented in the NS-NS sector and it is shown that they can be cast in T-duality invariant form for the case of Hassan-Sen compactification scheme. An illustrative example is presented to realize our proposal. © 2013 World Scientific Publishing Company.

Agarwalla S.K.,Institute of Physics, Bhubaneswar
Advances in High Energy Physics | Year: 2014

The discovery of neutrino mixing and oscillations over the past decade provides firm evidence for new physics beyond the Standard Model. Recently, θ13 has been determined to be moderately large, quite close to its previous upper bound. This represents a significant milestone in establishing the three-flavor oscillation picture of neutrinos. It has opened up exciting prospects for current and future long-baseline neutrino oscillation experiments towards addressing the remaining fundamental questions, in particular the type of the neutrino mass hierarchy and the possible presence of a CP-violating phase. Another recent and crucial development is the indication of non-maximal 2-3 mixing angle, causing the octant ambiguity of θ 13. In this paper, I will review the phenomenology of long-baseline neutrino oscillations with a special emphasis on sub-leading three-flavor effects, which will play a crucial role in resolving these unknowns. First, I will give a brief description of neutrino oscillation phenomenon. Then, I will discuss our present global understanding of the neutrino mass-mixing parameters and will identify the major unknowns in this sector. After that, I will present the physics reach of current generation long-baseline experiments. Finally, I will conclude with a discussion on the physics capabilities of accelerator-driven possible future long-baseline precision oscillation facilities. © 2014 Sanjib Kumar Agarwalla.

Das S.,Institute of Physics, Bhubaneswar
EPJ Web of Conferences | Year: 2015

The STAR experiment at RHIC has completed its first phase of the Beam Energy Scan (BES-I) program to understand the phase structure of the quantum chromodynamics (QCD). The bulk properties of the system formed in Au+Au collisions at different center of mass energy sNN = 7.7, 11.5, 19.6, 27, and 39 GeV have been studied from the data collected in the year 2010 and 2011. The centrality and energy dependence of mid-rapidity (|y| < 0.1) particle yields, and ratios are presented here. The chemical freeze-out parameters are extracted using measured particle ratios within the framework of a statistical model. © Owned by the authors, published by EDP Sciences, 2015.

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