Tata Institute of Fundamental Research

About: Tata Institute of Fundamental Research is a education organization based out in Mumbai, Maharashtra, India. It is known for research contribution in the topics: Magnetization & Large Hadron Collider. The organization has 7786 authors who have published 21742 publications receiving 622368 citations. The organization is also known as: TIFR.

Upper limits on sparticle masses from g -- 2 and the possibility for discovery of supersymmetry at colliders and in dark matter searches.

Abstract: We analyze the implications of the new physics effect seen in the $g\ensuremath{-}2$ Brookhaven measurement and show that if the effect arises from supersymmetry, then the sign of the Higgs mixing parameter $\ensuremath{\mu}$ is determined to be positive in the standard sign convention. Further, analyses within the minimal supergravity model show that the Brookhaven result leads to upper limits on the universal gaugino and scalar masses of ${m}_{1/2}\ensuremath{\le}800\mathrm{GeV}$ and ${m}_{0}\ensuremath{\le}1.5\mathrm{TeV}$ for $\mathrm{tan}\ensuremath{\beta}\ensuremath{\le}55$. Our analysis strongly suggests that supersymmetry via production of sparticles must be found at the CERN Large Hadron Collider. Further, $\mathrm{sgn}(\ensuremath{\mu})$ positive is favorable for the discovery of supersymmetric cold dark matter.

Criteria for the unitarizability of some highest weight modules

Abstract: For a linear semisimple Lie group we obtain a necessary and sufficient condition for a highest weight module with non-singular infinitesimal character to be unitarizable.

Discovery of PSR J1227-4853: A transition from a low-mass X-ray binary to a redback millisecond pulsar

Abstract: XSS J12270-4859 is an X-ray binary associated with the Fermi LAT gamma-ray source 1FGL J1227.9-4852. In 2012 December, this source underwent a transition where the X-ray and optical luminosity dropped and the spectral signatures of an accretion disc disappeared. We report the discovery of a 1.69 millisecond pulsar (MSP), PSR J1227-4853, at a dispersion measure of 43.4 pc cm$^{-3}$ associated with this source, using the GMRT at 607 MHz. This demonstrates that, post-transition, the system hosts an active radio MSP. This is the third system after PSR J1023+0038 and PSR J1824-2452I showing evidence of state switching between radio MSP and low-mass X-ray binary (LMXB) states. We report timing observations of PSR J1227-4853 with the GMRT and Parkes, which give a precise determination of the rotational and orbital parameters of the system. The companion mass measurement of 0.17 to 0.46 M$_{sun}$ suggests that this is a redback system. PSR J1227-4853 is eclipsed for about 40% of its orbit at 607 MHz; with additional short-duration eclipses at all orbital phases. We also find that the pulsar is very energetic, with a spin-down luminosity of ~ 10$^{35}$ erg s$^{-1}$. We report simultaneous imaging and timing observations with the GMRT, which suggests that eclipses are caused by absorption, rather than dispersion smearing or scattering.

Unusual liquid state of hard-core bosons on the pyrochlore lattice.

Abstract: We study the physics of hard-core bosons with unfrustrated hopping (t) and nearest-neighbor repulsion (V) on the three dimensional pyrochlore lattice. At half-filling, we demonstrate that the small V/t superfluid state eventually becomes unstable at large enough V/t to an unusual insulating state which displays no broken lattice translation symmetry. Equal time and static density correlators in this insulator are well described by a mapping to electric field correlators in the Coulomb phase of a U(1) lattice gauge theory, allowing us to identify this insulator with a U(1) fractionalized Mott-insulating state. The possibility of observing this phase in suitably designed atom-trap experiments with ultracold atoms is also discussed, as are specific experimental signatures.