118957054
Einstein and the Quantum
We review here the main contributions of Einstein to the quantum theory. To put them in perspective we first give an account of Physics as it was before him. It is followed by a brief account of the problem of black body radiation which provided the context for Planck to introduce the idea of quantum. Einstein's revolutionary paper of 1905 on light-quantum hypothesis is then described as well as an application of this idea to the photoelectric effect. We next take up a discussion of Einstein's other contributions to old quantum theory. These include (i) his theory of specific heat of solids, which was the first application of quantum theory to matter, (ii) his discovery of wave-particle duality for light and (iii) Einstein's A and B coefficients relating to the probabilities of emission and absorption of light by atomic systems and his discovery of radiation stimulated emission of light which provides the basis for laser action. We then describe Einstein's contribution to quantum statistics viz Bose-Einstein Statistics and his prediction of Bose-Einstein condensation of a boson gas. Einstein played a pivotal role in the discovery of Quantum mechanics and this is briefly mentioned. After 1925 Einstein's contributed mainly to the foundations of Quantum Mechanics. We choose to discuss here (i) his Ensemble (or Statistical) Interpretation of Quantum Mechanics and (ii) the discovery of Einstein-Podolsky-Rosen (EPR) correlations and the EPR theorem on the conflict between Einstein-Locality and the completeness of the formalism of Quantum Mechanics. We end with some comments on later developments.
35249306
Quantum violation of stochastic noncontextual hidden-variable theories.
We formulate stochastic noncontextual hidden-variable theories. In such theories the hidden state λ specifies not definite values, but expectation values A − (λ), ... of observables A, ... and noncontextuality means that A − (λ) is independent of which other commuting observables commuting with A are measured together with A. We show via Bell inequalities that such theories conflict with quantum theory and propose a two-photon experimental test. We also show that for a single particle of spin (2 n −1)/2, quantum violation of classical noncontextuality grows exponentially with n.
123580858
Unitarity upper bound on the absorptive parts of elastic scattering amplitudes
We derive a unitarity upper bound on the absorptive part A(s, t) of the elastic-scattering amplitude in the physical region. In the diffraction peak region the bound on A(s, t)/A(s, 0) is a function only of the parameter σ tot 2 (−t)/4πσ el . Assuming the diffraction scattering to be purely absorptive and spin independent we find the pp, pp, and π ± p data to lie a little below the theoretical upper bound. Further the experimental curve of X(t)/X(0) vs −4tX(0)/σ el , where X(t)≡dσ/dt, seems "universal."
37383185
JOINT PROBABILITIES REPRODUCING THREE EPR EXPERIMENTS ON TWO QUBITS
An eight-parameter family of the most general non-negative quadruple probabilities is constructed for EPR–Bohm–Aharonov experiments when only three pairs of analyser settings are used. It is a simultaneous representation of three different Bohr-incompatible experimental configurations involving mutually noncommuting observables valid for arbitrary quantum states.
117295648
REGGE POLES AND ASYMPTOTIC BEHAVIOR IN THE ANALYTIC CONTINUATION OF THE PION-NUCLEON SCATTERING AMPLITUDE
120223172
psi particles, SU(4), and anomalous currents
We propose assignment of the new ψ particles in an SU(4) symmetry scheme, incorporating SU(3) and a new additive quantum number, paracharge Z. Anomalous currents are introduced to account for the production and decays of these particles. Two more rather broad resonances at around 4.3 and 5.0 (±0.2) GeV are expected in the e + e - annihilation, one of which has recently been reported (at 4.15 GeV).
54620466
Measuring the level of nuclear activity in Seyfert galaxies and the unification scheme
Context. The unification scheme of Seyfert galaxies hypothesizes that Seyfert type 1s and type 2s are intrinsically similar and the observed differences between the two subtypes are solely due to the differing orientations of toroidal-shaped obscuring material around the AGN. In the framework of the unification scheme, both the Seyfert subtypes are expected to show similar intrinsic nuclear properties such as the absorption-corrected AGN X-ray luminosity, bolometric luminosity, accretion rate and the mass of the supermassive black hole. Aims. To test the predictions of the Seyfert unification scheme, we make statistical comparison of the distributions of: (i) the absorption-corrected 2.0‐10 keV X-ray luminosities; (ii) the bolometric luminosities; (iii) the black hole masses and; (iv) the Eddington ratios, of Seyfert type 1s and type 2s. Methods. We use an optically selected Seyfert sample in which type 1s and type 2s are matched in properties that are independent to the orientation of the obscuring torus, the AGN axis and the host galaxy. Results. The distributions of the absorption-corrected 2.0‐10 keV X-ray luminosities (L c.0−10 keV ), the bolometric luminosities (LBol), the black masses (MBH) and, the Eddington ratios (λ) are statistically similar for the two Seyfert subtypes, consistent with the orientation and obscuration based Seyfert unification scheme. The Eddington ratio distributions suggest that both the Seyfert subtypes are accreting at sub-Eddington level with wide span of Eddington ratios i.e., 10 −4 ‐10 −1 .
110461869
A multichannel avalanche photodiode phototube for calorimetry
New results from measurements of the performance of a multichannel Avalanche Photodiode Photomultiplier tube (APD-PMT) in a test beam at the CERN PS are presented. The APD-PMT was used to read out a shower maximum detector placed inside an electromagnetic calorimeter designed as a prototype for the SDC plug region. Electron beams with energies ranging between 3 and 10 GeV were used.
122336835
Validity of scaling relations between nucleon form factors
We prove, within the framework of analytic S-matrix theory and the physical mass spectrum, that the following scaling relations cannot be rigorously true for all t: (i) G M V (t)∝G E V (t), (ii) G M V (t)=R 1 (t)G E V (t)+R 2 (t), where R 1,2 (t) are rational functions of t, (iii) F Π (t)∝G E V (t), and (iv) F Π (t)∝G M V (t).
118486527
X-ray spectral properties of Seyfert galaxies and the unification scheme
Context. The unification scheme of Seyfert galaxies predicts that the observed differences between types 1 and 2 Seyfert galaxies are solely due to the differing orientations of the toroidal-shaped obscuring material around AGN. The observed X-ray spectra of Seyfert type 2s compared to type 1s are expected to be affected by higher absorbing column density owing to the edge-on view of the obscuring torus. Aims. We study the 0.5‐10 keV X-ray spectral properties of Seyfert type 1s and type 2s with the aim of testing the predictions of Seyfert unification scheme in the X-ray regime. Methods. We use an optically selected Seyfert sample in which type 1s and type 2s have matched distributions in parameters that are independent of the orientation of AGN and the host galaxy. Results. The 0.5‐10 keV XMM-Newton pn X-ray spectra of Seyfert galaxies are in general best fitted with a model that consists of (i) an absorbed powerlaw; (ii) a narrow Gaussian fitted to the Fe Kα emission line; and (iii) an often seen soft-excess component characterized by either a thermal plasma model with temperature kT ∼ 0.1‐1.0 keV or a steep powerlaw or both. The 2.0‐10 keV hard X-ray continuum emission in several Seyfert type 2s is dominated by reflection and suggests the Compton-thick obscuration. Results of the statistical comparison between the distributions of (i) the observed X-ray luminosities in the soft (0.5‐2.0 keV) and hard (2.0‐10.0 keV) bands; (ii) the X-ray absorbing column densities; (iii) the equivalent widths of Fe Kα line; and (iv) the flux ratios of hard X-ray to [OIII] λ5007 A, for the two Seyfert subtypes are consistent with the obscuration and orientation-based unification scheme.
119188201
Emission characteristics of the projectile fragments at relativistic energy
A projectile (84Kr36) having kinetic energy around 1 A GeV has been used to expose NIKFI BR-2 emulsion target at GSI, Darmstadt, Germany. A total of 700 inelastic events has been identified and used in the present studies on projectile fragments. The emission angle of the projectile fragments are strongly affected by charge of the other projectile fragments emitted at same time with different emission angle is observed. The angular distribution studies show symmetrical nature for lighter charge projectile fragments. The symmetrical nature decreased with the charge of projectile fragments. We have observed at ~4o of emission angle for double charge projectile fragments, the momentum transfer during interaction is similar for various target species of emulsion. We have also observed a small but significant amplitude peaks on both side of the big peak for almost all light charge projectile fragments having different delta angle values. It reflects that there are a few percent of projectile fragments that are coming from the decay of heavy projectile fragments or any other process.