27 citations · 76 across the 5 of their papers we have counts for
5 papers
Exact solution of the infinite-U Hubbard problem and other models in one dimension
Brijesh Kumar
An interacting spin-fermion model is exactly solved on an open chain. In a certain representation, it is the nearest-neighbor Hubbard model in the limit of infinite (local inte…
Optical and near-IR photometric study of the open cluster NGC 637 and NGC 957
R. K. S. Yadav, Brijesh Kumar, A. Subramaniam +2
We present UBVRI CCD photometry in the region of the open clusters NGC 637 and NGC 957. The radii are found to be 4.2 arcmin and 4.3 arcmin. Their reddenings E(B-V) are 0.64+/-0.05…
Multi-wavelength study of a young open cluster NGC 7419
Himali Joshi, Brijesh Kumar, K. P. Singh +3
Using UBVRI Halpha CCD photometric observations and the archival NIR and X-ray data, we have carried out a multi-wavelength study of a young star cluster NGC 7419. An age of 22.5+/…
Chandra and XMM-Newton observations of the low-luminosity X-ray pulsators SAX J1324.4-6200 and SAX J1452.8-5949
Ramanpreet Kaur, Rudy Wijnands, Alessandro Patruno +5
We present results from our Chandra and XMM-Newton observations of two low-luminosity X-ray pulsators SAX J1324.4-6200 and SAX J1452.8-5949 which have spin-periods of 172 s and 437…
Fourfold degenerate columnar-dimer ground state in square lattice antiferromagnets
Rakesh Kumar, Brijesh Kumar
We construct and study two frustrated quantum spin-1/2 models on square lattice, which are like the antiferromagnetic - model with some additional four-spin exchange inte…