Two Large Examples in Orbifold Theory: Abelian Orbifolds and the Charge Conjugation Orbifold on su(n)

Recently the operator algebra and twisted vertex operator equations were given for each sector of all WZW orbifolds, and a set of twisted KZ equations for the WZW permutation orbifolds were worked out as a large example. In this companion paper we report two further large examples of this development. In the first example we solve the twisted vertex operator equations in an abelian limit to obtain the twisted vertex operators and correlators of a large class of abelian orbifolds. In the second example, the twisted vertex operator equations are applied to obtain a set of twisted KZ equations for the (outer-automorphic) charge conjugation orbifold on su(n \geq 3).Comment: 58 pages, v2: three minor typo

Ward Identities for Affine-Virasoro Correlators

Generalizing the Knizhnik-Zamolodchikov equations, we derive a hierarchy of non-linear Ward identities for affine-Virasoro correlators. The hierarchy follows from null states of the Knizhnik-Zamolodchikov type and the assumption of factorization, whose consistency we verify at an abstract level. Solution of the equations requires concrete factorization ans\"atze, which may vary over affine-Virasoro space. As a first example, we solve the non-linear equations for the coset constructions, using a matrix factorization. The resulting coset correlators satisfy first-order linear partial differential equations whose solutions are the coset blocks defined by Douglas.Comment: 53 pages, Latex, LBL-32619, UCB-PTH-92/24, BONN-HE-92/2

Semi-Classical Blocks and Correlators in Rational and Irrational Conformal Field Theory

The generalized Knizhnik-Zamolodchikov equations of irrational conformal field theory provide a uniform description of rational and irrational conformal field theory. Starting from the known high-level solution of these equations, we first construct the high-level conformal blocks and correlators of all the affine-Sugawara and coset constructions on simple g. Using intuition gained from these cases, we then identify a simple class of irrational processes whose high-level blocks and correlators we are also able to construct.Comment: 53 pages, Latex. Revised version with extended discussion of phases and secondarie

X-ray Observations and Infrared Identification of the Transient 7.8 s X-ray Binary Pulsar XTE J1829-098

XMM-Newton and Chandra observations of the transient 7.8 s pulsar XTE J1829-098 are used to characterize its pulse shape and spectrum, and to facilitate a search for an optical or infrared counterpart. In outburst, the absorbed, hard X-ray spectrum with Gamma = 0.76+/-0.13 and N_H = (6.0+/-0.6) x 10^{22} cm^{-2} is typical of X-ray binary pulsars. The precise Chandra localization in a faint state leads to the identification of a probable infrared counterpart at R.A. = 18h29m43.98s, decl. = -09o51'23.0" (J2000.0) with magnitudes K=12.7, H=13.9, I>21.9, and R>23.2. If this is a highly reddened O or B star, we estimate a distance of 10 kpc, at which the maximum observed X-ray luminosity is 2x10^{36} ergs s^{-1}, typical of Be X-ray transients or wind-fed systems. The minimum observed luminosity is 3x10^{32}(d/10 kpc)^2 ergs s^{-1}. We cannot rule out the possibility that the companion is a red giant. The two known X-ray outbursts of XTE J1829-098 are separated by ~1.3 yr, which may be the orbital period or a multiple of it, with the neutron star in an eccentric orbit. We also studied a late M-giant long-period variable that we found only 9" from the X-ray position. It has a pulsation period of ~1.5 yr, but is not the companion of the X-ray source.Comment: 6 pages, 7 figures. To appear in The Astrophysical Journa

Combining local- and large-scale models to predict the distributions of invasive plant species

Habitat-distribution models are increasingly used to predict the potential distributions of invasive species and to inform monitoring. However, these models assume that species are in equilibrium with the environment, which is clearly not true for most invasive species. Although this assumption is frequently acknowledged, solutions have not been adequately addressed. There are several potential methods for improving habitat-distribution models. Models that require only presence data may be more effective for invasive species, but this assumption has rarely been tested. In addition, combining modeling types to form ‘ensemble’ models may improve the accuracy of predictions. However, even with these improvements, models developed for recently invaded areas are greatly influenced by the current distributions of species and thus reflect near- rather than long-term potential for invasion. Larger scale models from species’ native and invaded ranges may better reflect long-term invasion potential, but they lack finer scale resolution. We compared logistic regression (which uses presence/absence data) and two presence-only methods for modeling the potential distributions of three invasive plant species on the Olympic Peninsula in Washington State, USA. We then combined the three methods to create ensemble models. We also developed climate-envelope models for the same species based on larger scale distributions and combined models from multiple scales to create an index of near- and long-term invasion risk to inform monitoring in Olympic National Park (ONP). Neither presence-only nor ensemble models were more accurate than logistic regression for any of the species. Larger scale models predicted much greater areas at risk of invasion. Our index of near- and long-term invasion risk indicates that \u3c4% of ONP is at high near-term risk of invasion while 67-99% of the Park is at moderate or high long-term risk of invasion. We demonstrate how modeling results can be used to guide the design of monitoring protocols and monitoring results can in turn be used to refine models. We propose that by using models from multiple scales to predict invasion risk and by explicitly linking model development to monitoring, it may be possible to overcome some of the limitations of habitat-distribution models

The Lie h-Invariant Conformal Field Theories and the Lie h-Invariant Graphs

We use the Virasoro master equation to study the space of Lie h-invariant conformal field theories, which includes the standard rational conformal field theories as a small subspace. In a detailed example, we apply the general theory to characterize and study the Lie h-invariant graphs, which classify the Lie h-invariant conformal field theories of the diagonal ansatz on SO(n). The Lie characterization of these graphs is another aspect of the recently observed Lie group-theoretic structure of graph theory.Comment: 38p

The heat of formation of CN radicals and radiative lifetimes of the A 1 Sigma - state of C2N2

Radiative lifetimes have been measured for the stable vibrational levels of the A 1 sigma - electronic state of C2N2. They range from 1.3 microsec for the 4(sub 0)(sup 1) level to 0.66 microsec for the 1(sub 0)(sup 1) 4(sub 0)(sup 1) level and in general decrease with increasing vibrational excitation. Self-quenching rate constants range from gas kinetic to ten times that. Foreign gas quenching rates are slower. Observation of emission from the 1(sub 0)(sup 1) 4(sub 0)(sup 1) level sets a lower limit for the heat of formation of CN of 439.11 kJ/mol