Accidental Degeneracy and Berry Phase of Resonant States

We study the complex geometric phase acquired by the resonant states of an open quantum system which evolves irreversibly in a slowly time dependent environment. In analogy with the case of bound states, the Berry phase factors of resonant states are holonomy group elements of a complex line bundle with structure group C*. In sharp contrast with bound states, accidental degeneracies of resonances produce a continuous closed line of singularities formally equivalent to a continuous distribution of "magnetic" charge on a "diabolical" circle, in consequence, we find different classes of topologically inequivalent non-trivial closed paths in parameter space.Comment: 23 pages, 2 Postscript figures, LaTex, to be published in: Group 21: Symposium on Semigroups and Quantum Irreversibility (Proc. of the XXI Int. Colloquium on Group Theoretical Methods in Physics

Constructing Doubly Self-Dual Chiral p-Form Actions in D=2(p+1) Spacetime Dimensions

A Siegel-type chiral p-form action is proposed in D=2(p+1) spacetime dimensions. The approach we adopt is to realize the symmetric second-rank Lagrange-multiplier field, introduced in Siegel's action, in terms of a normalized multiplication of two (q+1)-form fields with q indices of each field contracted in the even p case, or of two pairs of (q+1)-form fields with q indices of each pair of fields contracted in the odd p case, where the (q+1)-form fields are of external derivatives of one auxiliary q-form field for the former, or a pair of auxiliary q-form fields for the latter. Using this action, it is straightforward to deduce the recently constructed PST action for q equal to zero. It is found that the Siegel-type chiral p-form action with a fixed p (even or odd) is doubly self-dual in D=2(p+1) spacetime dimensions when the auxiliary field(s) is/are also chosen to be of p-form. This result includes PST's as a special case where only the chiral 0-form action is doubly self-dual in D=2 dimensions.Comment: 13 pages, no figure

Quaternion-Octonion Analyticity for Abelian and Non-Abelian Gauge Theories of Dyons

Einstein- Schroedinger (ES) non-symmetric theory has been extended to accommodate the Abelian and non-Abelian gauge theories of dyons in terms of the quaternion-octonion metric realization. Corresponding covariant derivatives for complex, quaternion and octonion spaces in internal gauge groups are shown to describe the consistent field equations and generalized Dirac equation of dyons. It is also shown that quaternion and octonion representations extend the so-called unified theory of gravitation and electromagnetism to the Yang-Mill's fields leading to two SU(2) gauge theories of internal spaces due to the presence of electric and magnetic charges on dyons

Solid-state nuclear magnetic resonance investigation of synthetic phlogopite and lepidolite samples

In the present work, our aim is to decipher the cationic ordering in the octahedral and tetrahedral sheets of two Al‐rich synthetic materials, namely, phlogopites of nominal composition K(Mg3‐xAlx)[Al1+xSi3‐xO10](OH)yF2‐y and lepidolites in the system trilithionite–polylithionite with composition K (LixAl3‐x)[Al4‐2xSi2xO10](OH)yF2‐y, by directly probing the aluminium distribution through 27Al and 17O magic‐angle spinning, multiple‐quantum magic‐angle spinning, and 27Al‐27Al double‐quantum single‐quantum nuclear magnetic resonance (NMR) experiments. Notably, 27Al‐27Al double‐quantum single‐quantum magic‐angle spinning NMR spectra, recorded at 9.34 and/or 20.00 T, show the spatial proximity or avoidance of the Al species inside or between the sheets. In both studied minerals, the ensemble of NMR data suggests a preference for [4]Al in the tetrahedral sheet to occupy position close to the [6]Al of the octahedral sheets

Finite homogeneous electric fields in the augmented plane wave formalism : applications to linear and nonlinear response

Computation of the effect of finite homogeneous electric fields in periodic systems is described in the context of the projector augmented wave formalism. Generalizing previous norm-conserving implementations, we compute the polarization using the approach of King-Smith and Vanderbilt [Phys. Rev. B 47 (1993) 1651] fully within the projector augmented wave framework, and then minimizing the electric field enthalpy. Applications to simple systems are provided, including both linear and nonlinear field effects, and photoelastic response

Medicare payment changes and nursing home quality: effects on long-stay residents

The Balanced Budget Act of 1997 dramatically changed the way that Medicare pays skilled nursing facilities, providing a natural experiment in nursing home behavior. Medicare payment policy (directed at short-stay residents) may have affected outcomes for long-stay, chronic-care residents if services for these residents were subsidized through cost-shifting prior to implementation of Medicare prospective payment for nursing homes. We link changes in both the form and level of Medicare payment at the facility level with changes in resident-level quality, as represented by pressure sores and urinary tract infections in Minimum Data Set (MDS) assessments. Results show that long-stay residents experienced increased adverse outcomes with the elimination of Medicare cost reimbursement. Copyright Springer Science+Business Media, LLC 2006Prospective payment, Nursing homes, Medicare, Quality of care, I11, I18, H51,