Measurement of Gamma-Rays from 11ΛB and 12ΛC

From the ^12 C（π^＋,K^＋）^12 AC reaction the γ -rays of 261.6±0.24 ke V（7/2^＋ →5/2^＋）and 1481.7±0.7 ke V（1/2^＋ →5/2^＋） of ^11 A B,and 2667.3±2.8 keV（1^- 2 → 2^- 1）of ^12 A C hypernuclei have been identified using a large germanium detector array Hyperball2 at K6 beam line of KEK. The observed energies of the transitions 1481.7keV and 261.6 keV are significantly different from the values predicted by the shell model using the △ and SN parameters determined from the ^7 △ Li data.     

Gravitational non-commutativity and Gödel-like spacetimes

We derive general conditions under which geodesics of stationary spacetimes resemble trajectories of charged particles in an electromagnetic field. For large curvatures (analogous to strong magnetic fields), the quantum mechanicical states of these particles are confined to gravitational analogs of lowest Landau levels. Furthermore, there is an effective non-commutativity between their spatial coordinates. We point out that the Som–Raychaudhuri and Gödel spacetime and its generalisations are precisely of the above type and compute the effective non-commutativities that they induce. We show that the non-commutativity for Gödel spacetime is identical to that on the fuzzy sphere. Finally, we show how the star product naturally emerges in Som–Raychaudhuri spacetimes.     

Quantum-invariant theory and the evolution of a Dirac field in Friedmann–Robertson–Walker flat space-times

On the basis of the generalized invariant formulation, the invariant-related unitary transformation method is used to study the evolution of a quantum Dirac field in Friedmann–Robertson–Walker spatially flat space-times. We first solve the functional Schr?dinger equation for a free Dirac field and obtain the exact solutions. We then investigate the way of extending the method to treat the case in which there is an interaction between the Dirac field and a scalar field. Received: 17 July 1999 / Published online: 6 March 2000     

Off-shell superpotentials and Ooguri-Vafa invariants of type Ⅱ/F theory compactification

In this paper, we calculate the off-shell superpotential of two Calabi-Yau manifolds with three parameters by integrating the period of the subsystem. We also obtain the Ooguri-Vafa invariants with open mirror symmetry.     

Conformally flat Stäckel spaces in the Brans–Dicke theory

A problem of classification of the conformally flat St?ckel spaces admitting complete separation of variables in the Hamilton–Jacobi equation is studied within the framework of the Brans–Dicke scalar-tensor gravitational theory. Solutions to the field equations of the theory are found for the conformally flat St?ckel spaces of type (1.1), and explicit forms of the metric and scalar field are presented. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 54–58, February, 2009.     

Jürgen Ehlers—and the fate of the black-hole spacetimes

This article—written in honour of Jürgen Ehlers—consists of two different, though interlocking parts: Sect. 1 describes my 54 years of perpetual experiences and exchanges with him, both science and episodes, whilst Sect. 2 describes the history of astrophysical black holes, which evolved during the same epoque though largely independently, with its activity centers in other places of the globe, and has by no means terminated.     

ΛN and ΣN Interactions from Lattice QCD

We present our recent study on ΛN and ΣN (isospin I = 3/2) interactions by measuring Nambu–Bethe–Salpeter wave functions on the Lattice QCD. The lattice QCD calculation is performed by using the N _f  = 2 + 1 gauge configurations generated by PACS-CS collaboration together with employing an improved method to obtain potentials in lattice QCD simulations. For the ¹ S ₀ channel, the central ΣN (I = 3/2) potential and the central ΛN (¹ S ₀) potential are found to be very similar. For the spin triplet (³ S ₁?³ D ₁) channels, the central ΛN(³ S ₁?³ D ₁) potential is attractive while the central ΣN(I = 3/2, ³ S ₁?³ D ₁) potentials is repulsive. Tensor potentials, on the other hand, are rather weak in both ΛN and ΣN(I = 3/2) systems.     

Thermodynamics of a class of non-asymptotically flat black holes in Einstein–Maxwell–Dilaton theory

We analyse in detail the thermodynamics in the canonical and grand canonical ensembles of a class of non-asymptotically flat black holes of the Einstein-(anti) Maxwell-(anti) Dilaton theory in 4D with spherical symmetry. We present the first law of thermodynamics, the thermodynamic analysis of the system through the geometrothermodynamics methods, Weinhold, Ruppeiner, Liu–Lu–Luo–Shao and the most common, that made by the specific heat. The geometric methods show a curvature scalar identically zero, which is incompatible with the results of the analysis made by the non null specific heat, which shows that the system is thermodynamically interacting, does not possess extreme case nor phase transition. We also analyse the local and global stability of the thermodynamic system, and obtain a local and global stability for the normal case for $0<\gamma <1$ and for other values of $\gamma $ , an unstable system. The solution where $\gamma =0$ separates the class of locally and globally stable solutions from the unstable ones.     

Picard–Vessiot theory and integrability

We survey some recent applications of the Differential Galois Theory of linear differential equations to the integrability (or solvability) of Dynamical Systems and Spectral Problems.     

Luis Santaló and classical field theory

Considered one of the founding fathers of integral geometry, Luis Santaló has contributed to various areas of mathematics. His work has applications in number theory, in the theory of differential equations, in stochastic geometry, in functional analysis, and also in theoretical physics. Between the 1950’s and the 1970’s, he wrote a series of papers on general relativity and on the attempts at generalizing Einstein’s theory to formulate a unified field theory. His main contribution in this subject was to provide a classification theorem for the plethora of tensors that were populating Einstein’s generalized theory. This paper revisits his work on theoretical physics.

     

K→ππγ and chiral perturbation theory

Weak radiative decaysK _L,S →π⁺π^?γ andK ⁺→π⁺π⁰γ are reexamined. The electromagnetic form factors and long-distance contributions to the direct photon emission are evaluated using the higher order effective chiral Lagrangian. We find that (1) the naive soft-pion theorem cannot be applied to the magnetic-type transition amplitude, (2) the shortdistance contribution toK _L →π⁺π^?γ is comparable to or even bigger than the long-distance one, (3) the ΔI=1/2 enhancement persists in the decayK ⁺→π⁺π⁰γ, (4) to the order of 1/Λ _χ ² (Λ _χ being the chiral-symmetry breaking scale) the direct photon emission amplitude does not receive a contribution from penguin operators, and (5) the 1/N _c expansion improves the discrepancy between theory and experiment.     

Chern–Simons theory and BCS superconductivity

We study the relationship between the holomorphic unitary connection of Chern–Simons theory with temporal Wilson lines and the Richardson's exact solution of the reduced BCS Hamiltonian. We derive the integrals of motion of the BCS model, their eigenvalues and eigenvectors as a limiting case of the Chern–Simons theory.     

Seiberg–Witten theory and matrix models

We derive a family of matrix models which encode solutions to the Seiberg–Witten theory in 4 and 5 dimensions. Partition functions of these matrix models are equal to the corresponding Nekrasov partition functions, and their spectral curves are the Seiberg–Witten curves of the corresponding theories. In consequence of the geometric engineering, the 5-dimensional case provides a novel matrix model formulation of the topological string theory on a wide class of non-compact toric Calabi–Yau manifolds. This approach also unifies and generalizes other matrix models, such as the Eguchi–Yang matrix model, matrix models for bundles over P¹${\mathbb{P}}^1$, and Chern–Simons matrix models for lens spaces, which arise as various limits of our general result.     

General theory and design of microperforated-panel absorbers

I.Introductionmicroperforated-panelsoundabsorber("microperforated-panelsoundabsorptionconstruc-tion"inearlierpapers,simplified)wasdevelopedinlaternineteensiXtiestoprovidearobustsoundabsorberforsevereenvironments,andtheorywaspresentedlateron[1].AperforatedpanelAsedbeforeasolidsurfaceconstitutestheabsorber,whoseperforationsbeingmadeinsubmillimeters,sothattheperforationsthemselvesprovideenoughacousticresistanceand,atthesametime,sufficientlylowacousticmassreactance,toformawide-bandresonancesoundab…     

Auditory place theory and frequency difference limen

It has been a barrier that the place code is far too coarse a mechanism to account for the finest frequency difference limen for place theory of hearing since it was proposed in 19th century. A place correlation model, which takes the energy distribution of a pure tone in neighboring bands of auditory filters into full account, was presented in this paper. The model based on the place theory and some experimental results of the psychophysical tuning curves of hearing can explain the finest difference limen for frequency (about 0.02 or 0.3% at 1000 Hz) easily. Using a standard 1/3 octave filter bank of which the relationship between the frequency of a input pure tone apart from the centre frequency of K-th filter band, Δf, and the output intensity difference between K-th and (K l)-th filters,ΔE, was established in order to show the fine frequency detection ability of the filter bank. This model can also be used to abstract the fundamental frequency of speech and to measure the frequency of pure tone precisely.     

Dynamics of wetting and Kramers’ theory

We investigate the potential link between Kramer’s treatment of rate processes and the molecular-kinetic theory of wetting. The results of recent large-scale simulations of dynamic wetting are used to illustrate and validate our analysis. We find that both theories predict that, for a given driving force, the velocity of the contact line is inversely proportional to the viscosity. They also predict that the velocity will depend with a negative exponent on the strength of solid-liquid interactions, which for simple systems can be represented to good approximation by the reversible work of adhesion Wa ⁰.