1,304 research outputs found
Effective Average Action in N=1 Super-Yang-Mills Theory
For N=1 Super-Yang-Mills theory we generalize the effective average action
Gamma_k in a manifest supersymmetric way using the superspace formalism. The
exact evolution equation for Gamma_k is derived and, introducing as an
application a simple truncation, the standard one-loop beta-function of N=1 SYM
theory is obtained.Comment: 17 pages, LaTeX, some remarks added, misprints corrected, to appear
in Phys. Rev.
Orto Botanico di Siena: centro di biodiversitĂ per la comunitĂ
La storia del Museo Botanico attraverso gli anni conferma lâimpronta dellâistituzione universitaria: insegnare, ricercare/coltivare e passare la conoscenza a pubblico/studenti. Un Giardino dei Semplici nel 1684, poi un Orto Botanico dal 1856 e dagli anni 2000 un Centro di conservazione e studio della biodiversitĂ locale. Questa Ăš, nella cittĂ del palio, lâimmagine dellâOrto Botanico, che sta lavorando con pubblici diversi e vuole trovare una nuova dimensione allâinterno della comunitĂ cittadina, per svolgere la sua missione di centro culturale, di spazio verde nella cittĂ per svago e piacere, ma allo stesso tempo di luogo di comunicazione scientifica.The history of the Botanical Museum through the years confirms the imprint of the university institution: teaching, researching/cultivating and passing on knowledge to the public/students. A Giardino dei Semplici in 1684, then a Botanical Garden from 1856 and since the 2000s a Centre for the conservation and study of local biodiversity. This is the image of the Botanical Garden in the city of the Palio, which is working with different audiences and wants to find a new dimension within the city community, to carry out its mission as a cultural centre, a green space in the city for recreation and pleasure, but at the same time a place for scientific communication
Hard Non-commutative Loops Resummation
The non-commutative version of the euclidean theory is
considered. By using Wilsonian flow equations the ultraviolet renormalizability
can be proved to all orders in perturbation theory. On the other hand, the
infrared sector cannot be treated perturbatively and requires a resummation of
the leading divergencies in the two-point function. This is analogous to what
is done in the Hard Thermal Loops resummation of finite temperature field
theory. Next-to-leading order corrections to the self-energy are computed,
resulting in contributions in the massless case, and
in the massive one.Comment: 4 pages, 3 figures. The resummation procedure is now discussed also
at finite ultraviolet cut-off. Minor changes in abstract and references.
Final version to be published in Physical Review Letter
First record of Toxodontidae (Mammalia, Notoungulata) from the late Miocene - Early Pliocene of the southern central Andes, NW Argentina
A new species of toxodontid notoungulate, Xotodon maimarensis n. sp., is described from the MaimarĂĄ Formation (late Miocene - early Pliocene), Jujuy Province, northwestern Argentina. This is the first record of a toxodontid from the Eastern Cordillera. The specimen is housed at the Museo de GeologĂa, MineralogĂa y PaleontologĂa, Instituto de GeologĂa y MinerĂa de la Universidad Nacional de Jujuy. It consists of an incomplete mandible preserving the right mandibular ramus with part of the dental series, partially preserved symphysis with all the incisors, and a small portion of the left ramus without teeth. The following characters distinguish it as a new taxon: symphysis long and narrow with slight divergence of its lateral borders; strong procumbence of lower incisors and deeply implanted i3; chin angle lower than in X. major and X. cristatus and bulging labial keel limiting strong lateral concavities. Comparative analysis in the context of the recently revised Neogene Toxodontidae indicates that the MaimarĂĄ specimen shares mandibular features and dental characters with Xotodon and Mixotoxodon, differing from the latter by the more upraised symphysis. The phylogenetic position of Xotodon maimarensis n. sp. supports the taxonomic interpretation of the studied specimen as a new species of Xotodon. This new Toxodontidae increases the knowledge of the diversity and radiation of this group of notoungulates in northwest Argentina.Facultad de Ciencias Naturales y Muse
Contribution to the bryological knowledge of the Tuscan-Emilian Apennines (Northern Italy)
The inventory of the bryophytes collected during the annual excursion of the Working Group for Bryology of the Italian Botanical Society is reported. This excursion was held in 2018 on the northern slope of the Tuscan-Emilian Apennines National Park, in the Administrative Region of Emilia-Romagna. The field work led to the finding of 113 taxa (24 liverworts and 89 mosses), including eight new records and seven confirmations for this Region. The occurrence of rare taxa for Italy (Scapania uliginosa, Rhizomnium pseudopunctatum, Racomitrium fasciculare, Scorpidium cossonii, Grimmia lisae, Orthotrichum pulchellum) is highlighted
Two loop results from one loop computations and non perturbative solutions of exact evolution equations
A nonperturbative method is proposed for the approximative solution of the
exact evolution equation which describes the scale dependence of the effective
average action. It consists of a combination of exact evolution equations for
independent couplings with renormalization group improved one loop expressions
of secondary couplings. Our method is illustrated by an example: We compute the
beta-function of the quartic coupling lambda of an O(N) symmetric scalar field
theory to order lambda^3 as well as the anomalous dimension to order lambda^2
using only one loop expressions and find agreement with the two loop
perturbation theory. We also treat the case of very strong coupling and confirm
the existence of a "triviality bound".Comment: 32 pages, HD-THEP-94-3, replaced because: lines too long, blank line
Renormalization of the Hamiltonian and a geometric interpretation of asymptotic freedom
Using a novel approach to renormalization in the Hamiltonian formalism, we
study the connection between asymptotic freedom and the renormalization group
flow of the configuration space metric. It is argued that in asymptotically
free theories the effective distance between configuration decreases as high
momentum modes are integrated out.Comment: 22 pages, LaTeX, no figures; final version accepted in Phys.Rev.D;
added reference and appendix with comment on solution of eq. (9) in the tex
Updated data on Litopterna from the Huayquerian Stage/Age (Late Miocene-Early Pliocene) of central-east Argentina
Hitherto, only the Proterotheriidae Ameghino, 1887 litopterns from the Cerro Azul Formation (Chasicoan-Huayquerian Stages/Ages; Late Miocene-Early Pliocene) in La Pampa Province had been studied, recognizing Proterotheriidae indet. at Cerro La Bota, Diplasiotherium pampa Soria, 2001 at several localities, Eoauchenia primitiva Ameghino, 1887 at El Guanaco, and cf. Brachytherium cuspidatum Ameghino, 1883 at Salinas Grandes de Hidalgo, which added to Epecuenia thoatherioides Cabrera, 1939 from Laguna EpecuĂ©n in Buenos Aires Province; this locality also yielded the Macraucheniidae Gervais, 1855 Huayqueriana cristata (Rovereto, 1914). Now, we enlarge the study to both litoptern families and to the outcrops of the Cerro Azul Formation in Buenos Aires Province. Concerning Macraucheniidae, we recognize: Scalabrinitherium bravardi Ameghino, 1883 at Salinas Grandes de Hidalgo, TelĂ©n, and GuatrachĂ© (La Pampa), and Laguna EpecuĂ©n (Buenos Aires); Paranauchenia denticulata Ameghino, 1891, Promacrauchenia sp., and Cullinia sp. at Salinas Grandes de Hidalgo and Laguna ChillhuĂ© (La Pampa); cf. Oxyodontherium zeballosi Ameghino, 1883b at Laguna del Monte (Buenos Aires); and Promacrauchenia sp. at Cantera Relleno Sanitario (Buenos Aires). Referring to Proterotheriidae, new results reveal the first record of Diplasiotherium pampa in Buenos Aires (Arroyo El Venado) and Neobrachytherium sp. at Laguna EpecuĂ©n and Laguna La Paraguaya (Buenos Aires). The litoptern diversity is close to that from the Lower Member of the ItuzaingĂł Formation, Late Miocene, Entre RĂos Province. The litoptern record does not provide confident data to support or reject the established relative biostratigraphic succession of localities of the Cerro Azul Formation, which is mainly based on some rodent lineages.Fil: Schmidt, Gabriela Ines. Provincia de Entre RĂos. Centro de Investigaciones CientĂficas y Transferencia de TecnologĂa a la ProducciĂłn. Universidad AutĂłnoma de Entre RĂos. Centro de Investigaciones CientĂficas y Transferencia de TecnologĂa a la ProducciĂłn. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Centro de Investigaciones CientĂficas y Transferencia de TecnologĂa a la ProducciĂłn; ArgentinaFil: Montalvo, Claudia I.. Universidad Nacional de la Pampa. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Naturales; ArgentinaFil: Cerdeño Serrano, Maria Esperanza. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales; ArgentinaFil: Sostillo, Renata. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Tomassini, Rodrigo Leandro. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - BahĂa Blanca. Instituto GeolĂłgico del Sur. Universidad Nacional del Sur. Departamento de GeologĂa. Instituto GeolĂłgico del Sur; ArgentinaFil: Bonini, Ricardo Adolfo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Tandil. Investigaciones ArqueolĂłgicas y PaleontolĂłgicas del Cuaternario Pampeano. Universidad Nacional del Centro de la Provincia de Buenos Aires. Investigaciones ArqueolĂłgicas y PaleontolĂłgicas del Cuaternario Pampeano; Argentin
Nonperturbative Evolution Equation for Quantum Gravity
A scale--dependent effective action for gravity is introduced and an exact
nonperturbative evolution equation is derived which governs its renormalization
group flow. It is invariant under general coordinate transformations and
satisfies modified BRS Ward--Identities. The evolution equation is solved for a
simple truncation of the space of actions. In 2+epsilon dimensions,
nonperturbative corrections to the beta--function of Newton's constant are
derived and its dependence on the cosmological constant is investigated. In 4
dimensions, Einstein gravity is found to be ``antiscreening'', i.e., Newton's
constant increases at large distances.Comment: 35 pages, late
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