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.

Projected Wave Functions and High Temperature Superconductivity

Abstract: Strong correlations are essential to understand d-wave high temperature superconductivity in doped Mott insulators [1]. The no-double occupancy constraint arising from strong correlations has been treated within two complementary approaches. Within the gauge theory approach [2], which is valid at all temperatures, the constraint necessitates the inclusion of strong gauge fluctuations. Alternatively, the constraint can be implemented exactly at T = 0 using the variational Monte Carlo (VMC) method. Previous variational studies [3–6] have focussed primarily on the energetics of competing states. In this letter, we revisit projected wavefunctions of the form proposed by Anderson in 1987 [1]. We compute physically interesting correlations using VMC and show that projection leads to loss of coherence. We obtain information about low energy excitations from the singular behavior of moments of the occupied spectral function. Remarkably, our results for various observables are in semi-quantitative agreement with experiments on the cuprates. We also make qualitative predictions for the doping (x) dependence of correlation functions in projected states (for x ≪ 1) from general arguments which are largely independent of the detailed form of the wavefunction and the Hamiltonian. We use the Hubbard Hamiltonian H = K + Hint. The kinetic energy K = P k,σ ǫ(k)c †σ ckσ with ǫ(k) =

The Forward muon detector of L3

Abstract: The forward-backward muon detector of the L3 experiment is presented. Intended to be used for LEP 200 physics, it consists of 96 self-calibrating drift chambers of a new design enclosing the magnet pole pieces of the L3 solenoid. The pole pieces are toroidally magnetized to form two independent analyzing spectrometers. A novel trigger is provided by resistive plate counters attached to the drift chambers. Details about the design, construction and performance of the whole system are given together with results obtained during the 1995 running at LEP.

M–Au/TiO2 (M = Ag, Pd, and Pt) nanophotocatalyst for overall solar water splitting: role of interfaces

Abstract: M–Au/TiO2 (M = Ag, Pd, Pt) composites were prepared through a facile one-pot photodeposition synthesis and evaluated for solar water splitting (SWS) with and without a sacrificial agent. The M–Au combination exhibits a dominant role in augmenting the H2 generation activity by forming a bi-metallic system. Degussa P25 was used as a TiO2 substrate to photodeposit Au followed by Au + M (M = Ag/Pd/Pt). The SWS activity of the M–Au/TiO2 was determined through photocatalytic H2 production in the presence of methanol as a sacrificial agent under one sun conditions with an AM1.5 filter. The highest H2 yield was observed for Pt0.5–Au1/TiO2 and was around 1.3 ± 0.07 mmol h−1 g−1, with an apparent quantum yield (AQY) of 6.4%. Pt0.5–Au1/TiO2 also demonstrated the same activity for 25 cycles of five hours each for 125 h. Critically, the same Pt0.5–Au1/TiO2 catalyst was active in overall SWS (OSWS) without any sacrificial agent, with an AQY = 0.8%. The amount of Au and/or Pt was varied to obtain the optimum composition and it was found that the Pt0.5–Au1/TiO2 composition exhibits the best activity. Detailed characterization by physico-chemical, spectral and microscopy measurements was carried out to obtain an in-depth understanding of the origin of the photocatalytic activity of Pt0.5–Au1/TiO2. These in-depth studies show that gold interacts predominantly with oxygen vacancies present on titania surfaces, and Pt preferentially interacts with gold for an effective electron–hole pair separation at Pt–Au interfaces and electron storage in metal particles. The Pt in Pt0.5–Au1/TiO2 is electronically and catalytically different from the Pt in Pt/TiO2 and it is predicted that the former suppresses the oxygen reduction reaction.

Black Hole Interior in the Holographic Correspondence and the Information Paradox

Abstract: We show that, within the AdS/CFT correspondence, recent formulations of the information paradox can be reduced to a question about the existence of certain kinds of operators in the conformal field theory (CFT). We describe a remarkably simple construction of these operators on a given state of the CFT. Our construction leads to a smooth horizon, addresses the strong subadditivity paradox, while preserving locality within effective field theory, and reconciles the existence of the interior with the growth of states with energy in the CFT. We also extend our construction to nonequilibrium states.