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Biswas S.,Rishi Bankim Chandra College | Roy P.,Saha Institute of Nuclear Physics | Dutt-Mazumder A.K.,Saha Institute of Nuclear Physics
Indian Journal of Physics | Year: 2011

We construct the charge symmetry violating (CSV) nucleon-nucleon potential in nuclear matter induced by the p-ω mixing due to the neutron-proton mass difference driven by the NN loop. Analytical expression for for the two-body CSV potential is presented. © 2011 Indian Association for the Cultivation of Science.

Chakraborty T.K.,Rishi Bankim Chandra College | Chakraborty T.K.,P.A. College | Chaudhuri S.D.,P.A. College | Choudhury J.,P.A. College
Hacquetia | Year: 2012

The evolutionary history of Ophioglossaceae is enigmatic mainly because fossils of the family trace back only from the earliest Tertiary. Phylogenetic analyses indicate that Helminthostachys is sister to the broadly defined Botrychium. Generally the sporophore of Botrychium is a pinnately compound, whereas it is simple in Helminthostachys. Here examples of different Helminthoistachys are represented which show double or triple spikes with some variations. Plants showing variations in their spike morphology are also grown normally. Variations of Helminthostachys spike morphology indicate a tendency to form a compound sporophore structure and in that way have a strong relationship with Botrychium.

Basak S.,Jadavpur University | Sen S.,Jadavpur University | Sen S.,Rishi Bankim Chandra College | Roy P.,Jadavpur University | And 6 more authors.
Australian Journal of Chemistry | Year: 2010

Two new dinuclear bis(μ2-phenoxo)-bridged copper(ii) complexes [Cu(NCS)L1]2 (1) and [Cu(NCS)L2] 2 (2) have been synthesized using two tridentate NNO-donor Schiff-base ligands, L1H (Me2N(CH2) 3N=CHC6H3(OMe)(OH)) and L2H (Me 2N(CH2)3N=C(CH3)C6H 4(OH)), respectively. They have been characterized by elemental analyses, IR, UV-visible, and electron paramagnetic resonance (EPR) spectroscopy, cyclic voltammetry, and magnetic susceptibility measurements. X-Ray single-crystal structures reveal a central Cu2O2 core in each complex with an isothiocyanate ligand coordinated terminally to each metal centre. The coordination environments around the CuII ions in 1 and 2 are a distorted trigonal bipyramid and a quasi-regular square pyramid, respectively, with significant differences in the Cu-O-Cu bridging angles (100.22(5)° for 1 and 95.64(7)° for 2). Although both Cu II dimers present intradimer antiferromagnetic exchange interactions, the magnitudes of the coupling constants in 1 and 2 (J = -119(1) and 0.361(3) cm-1, respectively) are quite different as a result of the different coordination geometries and Cu-O-Cu bridging angles. Both complexes act as promising catalysts or catalyst precursors for the efficient peroxidative oxidation of cycloalkanes (cyclohexane and cycloheptane) to the corresponding cyclic alcohols and ketones, with maximum overall yields of 53% and 56% for 1 and 2, respectively. © 2010 CSIRO.

Adhya S.P.,Saha Institute of Nuclear Physics | Mandal M.,Saha Institute of Nuclear Physics | Biswas S.,Rishi Bankim Chandra College | Roy P.K.,Saha Institute of Nuclear Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

In this work, dispersion relations of π0 and π± have been studied in vacuum in the limit of a weak external magnetic field using a phenomenological pion-nucleon (πN) Lagrangian. For our purpose, we have calculated the results up to one loop order in self-energy diagrams with the pseudoscalar (PS) and pseudovector (PV) pion-nucleon interactions. By assuming a weak external magnetic field, it is seen that the effective mass of the pion gets explicit magnetic field dependence, and it is modified significantly for the case of PS coupling. However, for the PV coupling, only a modest increase in the effective mass is observed. These modified dispersion relations due to the presence of the external field can have substantial influence in the phenomenological aspect of the mesons, both in the context of neutron stars as well as in relativistic heavy ion collisions. © 2016 American Physical Society.

Biswas S.,Rishi Bankim Chandra College | Roy P.,Saha Institute of Nuclear Physics
Proceedings of the Indian National Science Academy | Year: 2015

We revisit the problem of charge symmetry violation (CSV) in nucleon-nucleon interactions due to π- η mixing driven by the neutron-proton mass difference. We construct the CSV potential and estimate the contribution to the difference between pp and nn scattering lengths. © Printed in India.

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