15623742
Lorentz and CPT violating Chern-Simons term in the formulation of functional integral
We show that in the functional integral formalism the (finite) coefficient of the induced, Lorentz- and CPT-violating Chern-Simons term, arising from the Lorentz- and CPT-violating fermion sector, is undetermined.
1637505
Induced Lorentz and CPT violating Chern-Simons term in QED: Fock-Schwinger proper time method
Using the Fock-Schwinger proper time method, we calculate the induced Chern-Simons term arising from the Lorentz- and $\mathrm{CPT}$-violating sector of quantum electrodynamics with a ${b}_{\ensuremath{\mu}}\overline{\ensuremath{\psi}}{\ensuremath{\gamma}}^{\ensuremath{\mu}}{\ensuremath{\gamma}}_{5}\ensuremath{\psi}$ term. Our result to all orders in b coincides with a recent linear-in-$b$ calculation by M. Chaichian, W. F. Chen, and A. Gonz\'alez Felipe, hep-th/0010129v2. The coincidence was pointed out by J.-M. Chung, Phys. Lett. B 461, 138 (1999) and M. P\'erez-Victoria, Phys. Rev. Lett. 83, 2518 (1999), in the standard Feynman diagram calculation with the nonperturbative-in-$b$ propagator.
2607987
Renormalization group improvement of the effective potential in massive phi**4 theory: Next-next-next-to-leading logarithm resummation
The renormalization group method is applied to the three-loop effective potential of the massive φ4 theory in the MS scheme in order to obtain the next-next-next-to leading logarithm resummation. For this, we use already known four-loop renormalization group functions and calculate perturbatively evolutions of the parameters (λ, m2, φ and, Λ) along the running scale within the accuracy of the three-loop order. We also comment on the structure of five-loop effective potential using the renormalization group equation for the effective potential and the existing five-loop renormalization group functions. PACS number(s): 11.10.Hi Typeset using REVTEX ∗Electronic address: chung@ctpred.mit.edu †Electronic address: bkchung@nms.kyunghee.ac.kr
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.
115777668
Self-dual solitons in dual-transformed abelian gauge theories in curved space
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.
118550953
Enhanced Nitrogen in Morphologically Disturbed Blue Compact Galaxies at 0.20 < z < 0.35: Probing Galaxy Merging Features
We present a study of correlations between the elemental abundances and galaxy morphologies of 91 blue compact galaxies (BCGs) at z = 0.20-0.35 with Sloan Digital Sky Survey (SDSS) DR7 data. We classify the morphologies of the galaxies as either ''disturbed'' or ''undisturbed'' by visual inspection of the SDSS images, and using the Gini coefficient and M{sub 20}. We derive oxygen and nitrogen abundances using the T{sub e} method. We find that a substantial fraction of BCGs with disturbed morphologies, indicative of merger remnants, show relatively high N/O and low O/H abundance ratios. The majority of the disturbed BCGs exhibit higher N/O values at a given O/H value compared to the morphologically undisturbed galaxies, implying more efficient nitrogen enrichment in disturbed BCGs. We detect Wolf-Rayet (WR) features in only a handful of the disturbed BCGs, which appears to contradict the idea that WR stars are responsible for high nitrogen abundance. Combining these results with Galaxy Evolution Explorer GR6 ultraviolet (UV) data, we find that the majority of the disturbed BCGs show systematically lower values of the H{alpha} to near-UV star formation rate ratio. The equivalent width of the H{beta} emission line is also systematically lower in the disturbed BCGs. Basedmore » on these results, we infer that disturbed BCGs have undergone star formation over relatively longer timescales, resulting in a more continuous enrichment of nitrogen. We suggest that this correlation between morphology and chemical abundances in BCGs is due to a difference in their recent star formation histories.« less