19014973
Evaluation of a Class of Two-Scale Three-Loop Vacuum Diagrams
As a generalization of a previous work [Phys. Rev. D. {\bf 59}, 105014 (1999)], we compute analytically a class of three-loop vacuum diagrams with two {\em arbitrarily} different mass scales. We use a decomposition algorithm in which the integrand of the final integral for the third momentum vector, say, $k$, becomes independent of the angles of $k$-vector in spherical polar coordinates. This algorithm proves to be very efficient in obtaining exclusively all $\e$-pole terms of the given diagram.
115777668
Self-dual solitons in dual-transformed abelian gauge theories in curved space
14139170
Calculation of a class of three loop vacuum diagrams with two different mass values
Using the method of Chetyrkin, Misiak, and M{umlt u}nz we calculate analytically a class of three-loop vacuum diagrams with two different mass values, one of which is one-third as large as the other. In particular, this specific mass ratio is of great interest in relation to the three-loop effective potential of the O(N) {phi}{sup 4} theory. All pole terms in {epsilon}=4{minus}D (D being the space-time dimensions in a dimensional regularization scheme) plus finite terms containing the logarithm of mass are kept in our calculation of each diagram. It is shown that a three-loop effective potential calculated using the three-loop integrals obtained in this paper agrees, in the large-N limit, with the overlap part of the leading-order (in the large-N limit) calculation of Coleman, Jackiw, and Politzer [Phys. Rev. D {bold 10}, 2491 (1974)]. {copyright} {ital 1999} {ital The American Physical Society}
16230113
Reduction of a Class of Three-Loop Vacuum Diagrams to Tetrahedron Topologies
We obtain finite parts (as well as $\epsilon$-pole parts) of massive three-loop vacuum diagrams with three-point and/or four-point interaction vertices by reducing them to tetrahedron diagrams with both massive and massless lines, whose finite parts were given analytically in a recent paper by Broadhurst. In the procedure of reduction, the method of integration-by-parts recurrence relations is employed. We use our result to compute the $\bar{\rm MS}$ effective potential of the massive $\phi^4$ theory.
2968872
RADIATIVELY-INDUCED LORENTZ AND CPT VIOLATING CHERN-SIMONS TERM IN QED
Abstract We calculate the induced Lorentz- and CPT-violating Chern–Simons term arising from the Lorentz- and CPT-violating sector of quantum electrodynamics with a b μ ψ γ μ γ 5 ψ term. The result to all orders in b coincides with the previous linear-in- b calulation by Chung and Oh [hep-th/9812132] as well as Jackiw and Kostelecký [Phys. Rev. Lett. 82 (1999) 3572], since all higher order terms vanish.
125318951
Selfdual vortices in curved space
30363280
NGC 3801 caught in the act: a post-merger star-forming early-type galaxy with AGN–jet feedback
In the current models of galaxy formation and evolution, AGN feedback is crucial to reproduce galaxy luminosity function, colour-magnitude relation and M• � relation. However, if AGN-feedback can indeed expel and heat up significant amount of cool molecular gas and consequently quench star formation, is yet to be demonstrated observationally. Only in four cases so far (Cen A, NGC 3801, NGC 6764 and Mrk 6), Xray observations have found evidences of jet-driven shocks heating the ISM. We chose the least-explored galaxy, NGC 3801, and present the first ultraviolet imaging and stellar population analysisis of this galaxy from GALEX data. We find this mergerremnant early-type galaxy to have an intriguing spiral-wisp of young star forming regions (age ranging from 100–500 Myr). Taking clues from dust/PAH, Hi and CO emission images we interpret NGC 3801 to have a kinamatically decoupled core or an extremely warped gas disk. From the HST data we also show evidence of ionised gas outflow similar to that observed in Hi and molecular gas (CO) data, which may have caused the decline of star formation leading to the red optical colour of the galaxy. However, from these panchromatic data we interpret that the expanding shock shells from the young (�2.4 million years) radio jets are yet to reach the outer gaseous regions of the galaxy. It seems, we observe this galaxy at a rare stage of its evolutionary sequence where post-merger star formation has already declined and new powerful jet feedback is about to affect the gaseous star forming outer disk within the next 10 Myr, to further transform it into a red-and-dead early-type galaxy.