Extremes of nuclear structure

With the advent of medium and large gamma detector arrays, it is now possible to look at nuclear structure at high rotational forces. The role of pairing correlations and their eventual breakdown, along with the shell effects have showed us the interesting physics for nuclei at high spins — superdeformation, shape co-existence, yrast traps, alignments and their dramatic effects on nuclear structure and so on. Nuclear structure studies have recently become even more exciting, due to efforts and possibilities to reach nuclei far off from the stability valley. Coupling of gamma ray arrays with ‘filters’, like neutron wall, charged particle detector array, gamma ray total energy and multiplicity castles, conversion electron spectrometers etc gives a great handle to study nuclei produced online with ‘low’ cross-sections. Recently we studied, nuclei in mass region 80 using an array of 8 germanium detectors in conjunction with the recoil mass analyser, HIRA at the Nuclear Science Centre and, most unexpectedly came across the phenomenon of identical bands, with two quasi-particle difference. The discovery of magnetic rotation is another highlight. Our study of light In nucleus, 107In brought us face to face with the ‘dipole’ bands. I plan to discuss some of these aspects. There is also an immensely important development — that of the ‘radioactive ion beams’. The availability of RIB, will probably very dramatically influence our ‘conventional’ concept of nuclear structure. The exotic shapes of these exotic nuclei and some of their expected properties will also be touched upon.     

Cosmology with cosmic microwave background anisotropy

Measurements of CMB anisotropy and, more recently, polarization have played a very important role in allowing precise determination of various parameters of the ‘standard’ cosmological model. The expectation of the paradigm of inflation and the generic prediction of the simplest realization of inflationary scenario in the early Universe have also been established — ‘acausally’ correlated initial perturbations in a flat, statistically isotropic Universe, adiabatic nature of primordial density perturbations. Direct evidence for gravitational instability mechanism for structure formation from primordial perturbations has been established. In the next decade, future experiments promise to strengthen these deductions and uncover the remaining crucial signature of inflation — the primordial gravitational wave background.     

Against ‘Realism’

We examine the prevalent use of the phrase “local realism” in the context of Bell’s Theorem and associated experiments, with a focus on the question: what exactly is the ‘realism’ in ‘local realism’ supposed to mean? Carefully surveying several possible meanings, we argue that all of them are flawed in one way or another as attempts to point out a second premise (in addition to locality) on which the Bell inequalities rest, and (hence) which might be rejected in the face of empirical data violating the inequalities. We thus suggest that the phrase ‘local realism’ should be banned from future discussions of these issues, and urge physicists to revisit the foundational questions behind Bell’s Theorem.     

Contextuality and Nonlocality in ‘No Signaling’ Theories

We define a family of ‘no signaling’ bipartite boxes with arbitrary inputs and binary outputs, and with a range of marginal probabilities. The defining correlations are motivated by the Klyachko version of the Kochen-Specker theorem, so we call these boxes Kochen-Specker-Klyachko boxes or, briefly, KS-boxes. The marginals cover a variety of cases, from those that can be simulated classically to the superquantum correlations that saturate the Clauser-Horne-Shimony-Holt inequality, when the KS-box is a generalized PR-box (hence a vertex of the ‘no signaling’ polytope). We show that for certain marginal probabilities a KS-box is classical with respect to nonlocality as measured by the Clauser-Horne-Shimony-Holt correlation, i.e., no better than shared randomness as a resource in simulating a PR-box, even though such KS-boxes cannot be perfectly simulated by classical or quantum resources for all inputs. We comment on the significance of these results for contextuality and nonlocality in ‘no signaling’ theories.     

Wigner distributions for finite dimensional quantum systems: An algebraic approach

We discuss questions pertaining to the definition of ‘momentum’, ‘momentum space’, ‘phase space’ and ‘Wigner distributions’; for finite dimensional quantum systems. For such systems, where traditional concepts of ‘momenta’ established for continuum situations offer little help, we propose a physically reasonable and mathematically tangible definition and use it for the purpose of setting up Wigner distributions in a purely algebraic manner. It is found that the point of view adopted here is limited to odd dimensional systems only. The mathematical reasons which force this situation are examined in detail     

What price the spin-statistics theorem?

We examine a number of recent proofs of the spin-statistics theorem. All, of course, get the target result of Bose-Einstein statistics for identical integral spin particles and Fermi-Dirac statistics for identical half-integral spin particles. It is pointed out that these proofs, distinguished by their purported simple and intuitive kinematic character, require assumptions that are outside the realm of standard quantum mechanics. We construct a counterexample to these non-dynamical kinematic ‘proofs’ to emphasize the necessity of a dynamical proof as distinct from a kinematic proof. Sudarshan’s simple non-relativistic dynamical proof is briefly described. Finally, we make clear the price paid for any kinematic ‘proof’.     

Higher dimensional supersymmetric quantum mechanics and Dirac equation

We exhibit the supersymmetric quantum mechanical structure of the full 3+1 dimensional Dirac equation considering ‘mass’ as a function of coordinates. Its usefulness in solving potential problems is discussed with specific examples. We also discuss the ‘physical’ significance of the supersymmetric states in this formalism.     

Effect of the confined gluons in quark-quark interaction

On the basis of a successful phenomenological current confinement model for gluons we have obtained a closed analytical expression for the confined gluon propagator (CGP) for the specific small frequencies in the co-ordinate space using a translationally invariant ansatz. We have also derived compact expression for generalm-dimensional harmonic oscillator ‘propagator’ for specific energies. Using the CGP the complete expression for the one gluon exchange potential (COGEP) between the quarks has been derived using the Fermi-Breit formalism which will be useful in the study of hadron spectroscopy and hadron-hadron interactions. TheN - Δ splitting is calculated using the spin-spin part of the COGEP.     

An invitation to higher gauge theory

In this easy introduction to higher gauge theory, we describe parallel transport for particles and strings in terms of 2-connections on 2-bundles. Just as ordinary gauge theory involves a gauge group, this generalization involves a gauge ‘2-group’. We focus on 6 examples. First, every abelian Lie group gives a Lie 2-group; the case of U(1) yields the theory of U(1) gerbes, which play an important role in string theory and multisymplectic geometry. Second, every group representation gives a Lie 2-group; the representation of the Lorentz group on 4d Minkowski spacetime gives the Poincaré 2-group, which leads to a spin foam model for Minkowski spacetime. Third, taking the adjoint representation of any Lie group on its own Lie algebra gives a ‘tangent 2-group’, which serves as a gauge 2-group in 4d BF theory, which has topological gravity as a special case. Fourth, every Lie group has an ‘inner automorphism 2-group’, which serves as the gauge group in 4d BF theory with cosmological constant term. Fifth, every Lie group has an ‘automorphism 2-group’, which plays an important role in the theory of nonabelian gerbes. And sixth, every compact simple Lie group gives a ‘string 2-group’. We also touch upon higher structures such as the ‘gravity 3-group’, and the Lie 3-superalgebra that governs 11-dimensional supergravity.     

Reply to “quantum tunneling times: A crucial test for the causal program?”

Because Bohm’s Interpretation models particles with continuous trajectories, a natural property to attribute to a Bohmian particle is atunneling time, the time it takes for a particle to pass through a barrier. We also attribute a property-a different property-named ‘tunneling time’ to Copenhagen systems, systems that do not have particles with continuous trajectories. Cushing presents a discussion of the possibility of measuring Bohmian particle tunneling time; however, as becomes clear when considering the differences between properties named ‘tunneling time,’ he incorrectly argues that if such a measurement were possible, the measurement might constitute an empirical test between the Copenhagen interpretation and Bohm’s interpretation.     

How To Play Two-Player Restricted Quantum Games with 10 Cards

We show that it is possible to play ‘restricted’ two-player quantum games proposed originally by Marinatto and Weber (Phys. Lett. A 272:291–303, 2000) by purely macroscopic means, in the simplest case having as the only equipment a pack of 10 cards. Our example shows also that some apparently ‘genuine quantum’ results, even those that emerge as a consequence of dealing with entangled states, can be obtained by suitable application of Kolmogorovian probability calculus and secondary-school mathematics, without application of the ‘Hilbert space machinery’.     

Inseparability of Quantum Parameters

In this work, we show that ‘splitting of quantum information’ (Zhou, D., et al. in quant-ph/0503168) is an impossible task from three different but consistent principles namely unitarity of Quantum Mechanics, no-signaling condition and non-increase of entanglement under Local Operation and Classical Communication.     

The many faces of <Emphasis Type="Italic">nano</Emphasis> in newspaper reporting

The morpheme nano in languages such as Swedish and English is a constituent of many words. This article linguistically analyses the meaning potential of nano by focusing on word use in a Swedish newspaper corpus comprising 2,564 articles (1.6 million words) covering a 22-year period (1988–2010). Close to 400 word forms having nano as a constituent have been identified and analyzed. The results suggest that nano covers a broad and heterogeneous conceptual field: (i) as a prefix of the SI system; (ii) in relation to the scientific activities of nanoscience and nanotechnology, including their sub-processes and actors; and (iii) in relation to objects. The identified meanings of nano, besides the standard definition (i.e. ‘billionth part’ in relation to SI units), are ‘operating at the nanometre level’ in relation to activities and their actors and ‘nanometre sized’ and ‘nanotechnological’ in relation to objects; in addition, the less precise and non-technical meaning ‘very small’ is identified. We discuss the implications of the findings for a hypothesis about media influence on public understanding of technology, suggesting that repeated findings in Europe and the USA of little self-reported understanding and knowledge of nanotechnology or nanoscience among the public make sense in light of the polysemy of nano reflected in its broad variety of verbal forms and usages.     

Quasi-invariants and generalized Killing vectors-II

We consider here the problem of the existence of a quasi-invariant which is linear in the momenta for Hamiltonians in three degrees of freedom. We show that such quasi-invariants are more constrained in their structure than in the two degrees of freedom case. We also show that some of these quasi-invariants have to be interpreted as ‘pseudo-translations’, i.e., as translations in a non-orthogonal system of coordinates.     

SPDM: light microscopy with single-molecule resolution at?the?nanoscale

Far-field fluorescence techniques based on the precise determination of object positions have the potential to circumvent the optical resolution limit of direct imaging given by diffraction theory. In order to use localization to obtain structural information far below the diffraction limit, the ‘point-like’ components of the structure have to be detected independently, even if their distance is lower than the conventional optical resolution limit. This goal can be achieved by exploiting various photo-physical properties of the fluorescence labeling (‘spectral signatures’). In first experiments, spectral precision distance microscopy/spectral position determination microscopy (SPDM) was limited to a relatively small number of components to be resolved within the observation volume. Recently, the introduction of photoconvertable molecules has dramatically increased the number of components which can be independently localized. Here, we present an extension of the SPDM concept, exploiting the novel spectral signature offered by reversible photobleaching of fluorescent proteins. In combination with spatially modulated illumination (SMI) microscopy, at the present stage, we have achieved an estimated effective optical resolution of approximately 20 nm in the lateral and 50 nm in the axial direction, or about 1/25th–1/10th of the exciting wavelength.     

All basic condensed matter physics phenomena and notions mirror in biology — A hypothesis,two examples and a novel prediction

A few billion years of evolutionary time and the complex process of ‘selection’ has given biology an opportunity to explore a variety of condensed matter phenomena and situations, some of which have been discovered by humans in the laboratory, that too only in extreme non-biological conditions such as low temperatures, high purity, high pressure etc., in the last centuries. Biology, at some level, is a complex and self-regulated condensed matter system compared to the ‘inanimate’ condensed matter systems such as liquid ⁴He, liquid water or a piece of graphite. In this article I propose a hypothesis that ‘all basic condensed matter physics phenomena and notions (already known and ones yet to be discovered) mirror in biology’. I explain this hypothesis by considering the idea of ‘Bose condensation’ or ‘momentum space order’ and discuss two known example of quantum magnetism encountered in biology. I also provide some new and rather speculative possibility, from light harvesting in biological photosynthesis, of mesoscopic excition condensation related phenomena at room temperature.     

The universe formation by space reduction cascades with random initial parameters

In this paper we discuss the creation of our universe using the idea of extra dimensions. The initial, multidimensional Lagrangian contains only metric tensor. We have found many sets of the numerical values of the Lagrangian parameters corresponding to the observed low-energy physics of our Universe. Different initial parameters can lead to the same values of fundamental constants by the appropriate choice of a dimensional reduction cascade. This result diminishes the significance of the search for the ‘unique’ initial Lagrangian. We also have obtained a large number of low-energy vacua, which is known as ‘landscape’ in the string theory.     

Satisfaction of deDonder and Trautman conditions by radiative solutions of the Einstein field equations

We show that when the Einstein field equations for the gravitational field are modified by imposing the deDonder coordinate conditions these equations can be ‘solved’ in terms of source functions using the retarded Green's function for the d'Alembertian in flat space. The ‘solution’, which becomes an actual solution in the fast-motion approximation, is shown to satisfy the deDonder conditions if and only if the stress-energy tensor of the sources of the gravitational field is covariantly conserved. It is also shown to satisfy the Trautman outgoing radiation condition.     

Mass spectrum of elementary particles in a temperature-dependent model

We show that the temperature-generalization of a popular model of quark-confinement seems to provide a rather interesting insight into the origin of mass of elementary particles: as the universe cooled, there was an era when particles did not have an identity since their masses were variable; the temperature at which the conversion of these ‘nomadic’ particles into ‘elementary’ particles took place seems to have been governed by the value of a dimension-less coupling constantC _c. ForC _c=0.001(0.1) this temperature is of the order of 10⁹ K (10¹¹ K), below which the particle masses do not change.     

Anti-Selfdual Connections on the Quantum Projective Plane: Monopoles

We present several results on the geometry of the quantum projective plane. They include: explicit generators for the K-theory and the K-homology; a real calculus with a Hodge star operator; anti-selfdual connections on line bundles with explicit computation of the corresponding ‘classical’ characteristic classes (via Fredholm modules); complete diagonalization of gauged Laplacians on these line bundles; ‘quantum’ characteristic classes via equivariant K-theory and q-indices.