120323248
Supercoherent states for the t-J model
The Cartan structure of the dynamical superalgebra of the t-J model of strongly correlated electrons is found. This is used to define and explicitly construct the coherent states for this algebra and calculate the invariant measure for the completeness relation for the coherent states.
123114677
Mixing of operators in Wilson expansions
Abstract The tree-loop theorem of 't Hooft and Veltman is used in Fermi type gauges to show that gauge invariant operators in Wilson expansions mix in general with non-gauge invariant operators. Background field gauges are proposed in which this does not occur. Calculations of anomalous dimensions in these gauges are discussed.
115620347
The Schwinger mechanisms in non-abelian gauge theories
Abstract An alternative to the Higgs-Kibble mechanism for the formulation of spontaneously broken gauge theories has been recently proposed. It is shown how the new procedures can be generalised to the case when non-Abelian gauge groups are present.
120565281
Frustration and dynamics
Dynamical models incorporating frustration are discussed in general. In particular, it is shown how self-screening of Yang-Mills fields may lead to models of a generalized Ma-Rudnick genre for the spin-glass.
8253414
The omega effect for neutral mesons
The possible role of decoherence due to space-time foam is discussed within the context of two models, one based on string/brane theory. and the other based on properties of black hole horizons in general relativity. It is argued that the density matrix satisfies a dissipative master equation, primarily from the study of renormalization group flows in non-critical string theory. This interpretation of the zero mode of the Liouville field as time leads necessarily to the CPT operator being ill defined. One striking consequence is that the quantum mechanical correlations of pair states of neutral mesons produced in meson factories are changed from the usual EPR state. The magnitude of this departure from EPR correlations is characterised by a parameter ω. The predicted value of ω is very small or zero. However it is shown explicitly that the the non-vanishing of ω is only a feature of the model based on string/brane theory.
120412772
Renormalization-group approach to the lattice massive Schwinger model
Using Migdal-type recursion relations, the long-distance Coulomb force is found to be screened in the massive Schwinger model on a lattice. (AIP)
120645598
Spectroscopy of Nb 90 at high spin
Excited states of {sup 90}Nb were investigated via prompt and delayed {gamma} decays and the recoil-isomer tagging technique. The level scheme of {sup 90}Nb has been extended up to J=19({Dirac_h}/2{pi}) and E{sub x}=8.4 MeV. Half-lives of the 11{sup -} and 17/2{sup -} isomeric levels in {sup 90,91}Nb were measured to be 0.47{+-}0.01 and 3.3{+-}0.4 {mu}s, respectively. The results are compared with the predictions of large-basis shell model calculations. The effects of truncation of the valence model space on the calculated results are discussed.
107947607
RECENT DEVELOPMENTS IN THE TRIUMF CONTROL SYSTEM
The principle ideas and underlying architecture of the TRIUMF Central Control System have not changed since its commissioning in 1974. As described elsewhere 1,2,3 the system consists of a number of Data General minicomputers which communicate using a proprietary Data General parallel direct memory access interprocessor bus, and which share access to a common multiported memory containing a limited descriptive data base of device addresses and pointers to acquisition and conversion routines (Figure 1). The most important idea of the TRIUMF Control System design, and one which has in large measure determined the manner of its evolution, is the use of the executive crate, by means of which all central system computers share direct and immediate access to the entire seven parallel branch CAM.4C system, which in turn interfaces all accelerator devices and most of the main Control Room console devices. Expansion of the Control System to date has been realized on one hand by the addition of CAM.4C crates, and on the other by the addition of minicomputers to the executive crate interface. With the use of active extenders. the executive crate has been extended to three CAMAC crates. and could in principle clcctrically support as many as 1500 sources. In practice, this number is limited to a.bout 30 sources by bandwidth considerations, and to even fewer by the geographical requirement that sources be located physically within about 50 ft. (I/O bus length limitation) of the executive crate. This paper describes three recent developments in the TRIIJMF system whose designs have been influenced by its multisourced architecture. These are:
15573377
A Note on matrix model with IR cutoff and AdS/CFT
We study effective gauge theory at finite temperature on a three-sphere in the presence of an IR cutoff using AdS/CFT. Comparing with the thermodynamic behavior of its gravity dual, we analyze a phenomenological matrix model which describes the gauge theory in the strongly coupled regime. Subsequently, we study the behavior of the model as a function of the IR cutoff. We further argue that a similar matrix model represents the effective gauge theory on R3 with an IR-cutoff and analyze the model numerically.
118268033
Astrophysical implication of low E(21+) in neutron‐rich Sn isotopes
The observation and prediction of unusually depressed first excited 21+ states in even‐A neutron—rich isotopes of semi‐magic Sn above 132Sn provide motivations for reviewing the problems related to the nuclear astrophysics in general. In the present work, the β‐decay rates of the exotic even Sn isotopes (134,136Sn) above the 132Sn core have been calculated as a function of temperature (T). In order to get the necessary ft values, B(GT) values corresponding to allowed Gamow Teller (GT—) β‐decay have been theoretically calculated using shell model. The total decay rate shows decrease with increasing temperature as the ground state population is depleted and population of excited states with slower decay rates increases. The abundance at each Z value is inversely proportional to the decay constant of the waiting point nucleus for that particular Z. So the increase in half‐life of isotopes of Sn, like 136Sn, might have substantial impact on the r‐process nucleosynthesis.
199678166
Horizon entropy and higher curvature equations of state
The Clausius relation between entropy change and heat flux has previously been used to derive Einstein's field equations as an equation of state. We examine here whether a similar derivation can be given for extensions beyond Einstein gravity to include higher derivative and higher curvature terms.