Large-N analysis of (2+1)-dimensional Thirring model

We analyze $(2+1)$-dimensional vector-vector type four-Fermi interaction (Thirring) model in the framework of the $1/N$ expansion. By solving the Dyson-Schwinger equation in the large-$N$ limit, we show that in the two-component formalism the fermions acquire parity-violating mass dynamically in the range of the dimensionless coupling $\alpha$, $0 \leq \alpha \leq \alpha_c \equiv {1\over16} {\rm exp} (- {N \pi^2 \over 16})$. The symmetry breaking pattern is, however, in a way to conserve the overall parity of the theory such that the Chern-Simons term is not induced at any orders in $1/N$. $\alpha_c$ turns out to be a non-perturbative UV-fixed point in $1/N$. The $\beta$ function is calculated to be $\beta (\alpha) = -2 (\alpha - \alpha_c)$ near the fixed point, and the UV-fixed point and the $\beta$ function are shown exact in the $1/N$ expansion.Comment: 14 pages Latex. (Revised version: some changes have been made and references added.) To appear in Phys. Rev. D, SNUTP 93-4

Remark on the effective potential of the gravitational perturbation in the black hole background projected on the brane

The polar perturbation is examined when the spacetime is expressed by a 4d metric induced from higher-dimensional Schwarzschild geometry. Since the spacetime background is not a vacuum solution of 4d Einstein equation, the various general principles are used to understand the behavior of the energy-momentum tensor under the perturbation. It is found that although the general principles fix many components, they cannot fix two components of the energy-momentum tensor. Choosing two components suitably, we derive the effective potential which has a correct 4d limit.Comment: 12 pages, no figure, CQG accepte

Professions, Organizations and Institutions: Tenure Systems in Colleges and Universities

A common strategy used by professions to support claims of workplace jurisdiction involves the institutionalization of professionally-endorsed formal structures, yet both theory and research suggest that ensuring the implementation of institutionalized structures after formal adoption can be problematic. This study investigates the influence of organizational characteristics on the implementation of one professionally-created institution in higher education organizations, tenure systems for faculty employment. Our results suggest that implementation of tenure systems is negatively affected by internal resource pressures, but positively affected by countervailing pressures from professionally-linked constituents. The results also suggest self-limiting aspects of the use of tenure systems

Regularization, Renormalization and Range: The Nucleon-Nucleon Interaction from Effective Field Theory

Regularization and renormalization is discussed in the context of low-energy effective field theory treatments of two or more heavy particles (such as nucleons). It is desirable to regulate the contact interactions from the outset by treating them as having a finite range. The low energy physical observables should be insensitive to this range provided that the range is of a similar or greater scale than that of the interaction. Alternative schemes, such as dimensional regularization, lead to paradoxical conclusions such as the impossibility of repulsive interactions for truly low energy effective theories where all of the exchange particles are integrated out. This difficulty arises because a nonrelativistic field theory with repulsive contact interactions is trivial in the sense that the $S$ matrix is unity and the renormalized coupling constant zero. Possible consequences of low energy attraction are also discussed. It is argued that in the case of large or small scattering lengths, the region of validity of effective field theory expansion is much larger if the contact interactions are given a finite range from the beginning.Comment: 7 page

ILR Impact Brief - Faculty Tenure and the Gap between Policy and Practice

Almost all four-year institutions of higher education have adopted the tenure system as a formal policy for faculty employment. The degree to which tenure systems are actually implemented, however, depends on resource flows and institutional pressures. Fewer resource constraints (i.e., greater per-student revenues and larger endowments) increase the proportion of professors employed on tenure-track lines; likewise, a stronger research orientation positively affects the share of faculty in tenure-track slots. Colleges and universities that rely more heavily on tuition for revenues and those with larger numbers of accreditations (from professional and occupational associations) generally employ fewer tenure-track professors. Other variables also matter: Tenure is more prevalent at public, older, and more complex universities and colleges and is less widespread among institutions that enroll larger numbers of students and among those that include a medical school. And finally, the share of tenure-track faculty declines on campuses with a larger pool of graduate students who are available to teach

Possible Suppression of Resonant Signals for Split-UED by Mixing at the LHC?

The mixing of the imaginary parts of the transition amplitudes of nearby resonances via the breakdown of the Breit-Wigner approximation has been shown to lead to potentially large modifications in the signal rates for new physics at colliders. In the case of suppression, this effect may be significant enough to lead to some new physics signatures being initially missed in searches at, e.g., the LHC. Here we explore the influence of this `width mixing' on the production of the nearly degenerate, level-2 Kaluza-Klein (KK) neutral gauge bosons present in Split-UED. We demonstrate that in this particular case large cross section modifications in the resonance region are necessarily absent and explain why this is so based on the group theoretical structure of the SM.Comment: 10 pages, 2 figures; discussion and references adde