528,258 research outputs found
Harmonic maps, SU (N) skyrme models and yang-mills theories
No full textThis thesis examines the construction of static solutions of (3+l)-dimensional SU{N) Skyrme models, usual and alternative, and pure massive SU(N) Yang-Mills theories. In particular, the application of harmonic maps from S(^2) into the subspace of fields configuration space M. Here, the harmonic maps are used as an ansatz to factoring out the angular dependence part of the solutions from the field equations. In this thesis, we consider the harmonic maps S(^2) → Gr(n, N), where Gr(n, N) is the Grassmann manifold of n-dimensional planes passing through the origin in C(^N). Using the harmonic map ansatz of S(^2) → Gr(2, N) to study the usual SU(N) Skyrme models, we have found that our approximate solutions have marginally higher energies in comparison to the corresponding results previously obtained using CP(^N-1) as target space M. For exact spherically symmetric solutions, we present arguments which suggest that the only solutions obtained this way are embeddings. For the alternative SU(N) Skyrme models, using the harmonic map ansatz of S(^2) → CP(^N-1), we have found that our results for the energies of the exact spherically symmetric solutions are higher than in the usual models. When considering the pure massive SU(N) Yang-Mills theories, we have shown that by choosing the gauge potential to be of almost pure gauge form, the theories reduce to the usual SU(N) Skyrme models. This observation has suggested to us to consider the harmonic map ansatz of S(^2) → CP(^N-1) previously applied to monopole theories. Using this ansatz, we have constructed some bounded spherically symmetric solutions of the theories having finite energies
Mean field analysis of SU(N) deconfining transitions in the presence of dynamical quarks
No full textGreen F, Karsch F. Mean field analysis of SU(N) deconfining transitions in the presence of dynamical quarks. Nuclear Physics, B. 1984;238(2):297-306
Two-loop coupling constant renormalization in lattice SU(N)×SU(N) 2 D chiral models
No full textFor the most general link action of lattice SU(N)×SU(N) two dimensional chiral models, the two loop coupling constant renormalization is discussed in the context of the background field method. A non-linear reparametrization of the fields, necessary to keep the invariance of the theory, introduces unpleasant extra-terms. However some of the non-universal contributions are unaffected by these extra-terms and can be easily calculated. This allows to compute the difference between the first non-universal coefficients of the Callan-Symanzik beta function for two actions having the same scale Λ. © 1986 Springer-Verlag
Non-perturbative thermodynamics of SU (N) gauge theories
No full textEngels J, Fingberg J, Karsch F, Miller D, Weber M. Non-perturbative thermodynamics of SU (N) gauge theories. Physics Letters, B. 1990;252(4):625-630.The pressure near the deconfinement transition as determined up to now in lattice gauge theories shows unphysical behaviour: it can become negative and may in SU (3) even have a gap at the transition. This has been attributed to the use of only perturbatively known derivatives of coupling constants. We propose a method to evaluate the pressure, which works without these derivatives, and is valid on large lattices. In SU (2) we study the finite-volume effects and show that for lattices with spatial extent N-sigma greater-than-or-similar-to 15 these effects are negligible. In SU (3) we then ontain a postive and continuous pressure. The influence of non-perturbative corrections to the beta-function on the energy density are investigated and found to be important, in particular for the latent heat
SU(N) gauge theory couplings on asymmetric lattices
No full textKarsch F. SU(N) gauge theory couplings on asymmetric lattices. Nuclear Physics, B. 1982;205(2):285-300
Su Ürünlerinin İnsanlara Olan Zararları
No full textSu ürünleri, insanlarýn besin gereksinimi karþýlamasý-nýn yanýnda birçok saðlýk sorununun çözümü için de yararlandýklarý önemli kaynaklar arasýndadýr. Ancak su ürünleri bu yararlarýnýn yanýnda, bazý türlerinin saldýrýcý ve yýrtýcý, bazýlarýnýn elektriki organlara sahip ve diðer birgrup ise fanerotoksik (açýk zehirli) ya da kriptotoksik (gizli zehirli) o l u þ u y l a i n s a n s a ð l ý ð ý n ý n bozulmasýna ve hatta hayatýnýn s o n l a n m a s ý n a n e d e n olabilmektedirler. Bu çalýþma da insanlar için tehlikeli oluþturabilen su ürünleri tanýtýlarak, insanlara olan etkileri üzerinde durulmaktadýr
Resolución CSPyGE N° 18/2021. Derogar la Resolución CSPyGE N° 97/2019 y su modificatoria, Resolución CSPyGE N° 02/2021. Aprobar el Régimen de Personal Docente.
No full textFil: Consejo Superior de Programación y Gestión Estratégica (P). Universidad Nacional de Río Negro. Río Negro, ArgentinaResolución CSPyGE N° 18/2021. Derogar la Resolución CSPyGE N° 97/2019 y su modificatoria, Resolución CSPyGE N° 02/2021. Aprobar el Régimen de Personal Docente.tru
Gittersimulation einer zentrumssymmetrischen dreidimensionalen effektiven Theorie für SU(2) Yang-Mills
No full textWe present lattice simulations of a center symmetric dimensionally reduced effective field theory for SU(2) Yang Mills which employ thermal Wilson lines and three-dimensional magnetic fields as fundamental degrees of freedom. The action is composed of a gauge invariant kinetic term, spatial gauge fields and a potential for the Wilson line which includes a "fuzzy" bag term to generate non-perturbative fluctuations between Z(2) degenerate ground states. The model is studied in the limit where the gauge fields are set to zero as well as the full model with gauge fields. We confirm that, at moderately weak coupling, the "fuzzy" bag term leads to eigenvalue repulsion in a finite region above the deconfining phase transition which shrinks in the extreme weak-coupling limit. A non-trivial Z(N) symmetric vacuum arises in the confined phase. The effective potential for the Polyakov loop in the theory with gauge fields is extracted from the simulations including all modes of the loop as well as for cooled configurations where the hard modes have been averaged out. The former is found to exhibit a non-analytic contribution while the latter can be described by a mean-field like ansatz with quadratic and quartic terms, plus a Vandermonde potential which depends upon the location within the phase diagram. Other results include the exact location of the phase boundary in the plane spanned by the coupling parameters, correlation lengths of several operators in the magnetic and electric sectors and the spatial string tension. We also present results from simulations of the full 4D Yang-Mills theory and attempt to make a qualitative comparison to the 3D effective theory.Diese Arbeit präsentiert die Ergebnisse der Gittersimulation einer dreidimensionalen effektiven Theorie für eine SU(2) Eichtheorie bei endlichen Temperaturen. Die Theorie verwendet thermische Wilson Linien und den dreidimensionalen magnetischen Sektor als elementare Freiheitsgrade. Die Wirkung der effektiven Theorie respektiert alle Symmetrien der Eichtheorie in vier Dimensionen. Sie ist invariant unter lokalen SU(2) Eichtransformationen und zusätzlich invariant unter globalen Z(2) Transformationen, welche dem Abel'schem Zentrum der SU(2) Gruppe entsprechen. Sie enthält das Quadrat des dreidimensionalen Feldstärketensors, einen effektiven kinetischen Term der die Eichfelder an die Wilson Linien koppelt und das störungstheoretische Potential der Wilson Linien bis zur ersten Ordnung. Zusätzlich wird ein "fuzzy bag'' Term addiert, welcher einen Phasenübergang erzeugt und nicht-störungstheoretische Fluktuationen zwischen Z(2) symmetrischen Grundzuständen generiert. Wir untersuchen die Theorie sowohl im Grenzfall verschwindender Magnetfelder, als auch die volle Theorie in welcher dynamische Magnetfelder auftreten. Wir zeigen, dass die Theorie eine Phase mit spontan gebrochener Z(2) Symmetrie besitzt in welcher der Polyakov Loop einen nicht-verschwindenden Wert hat. In Analogie zur Quantenchromodynamik entspricht dies einer Aufhebung des Quark-Confinement. Wir bestimmen das Phasendiagramm der Theorie und ermitteln die Ordnung des Phasenübergangs an verschiedenen Stellen der Phasengrenze mittels Korrelationsfunktionen und des Skalenverhaltens der Suszeptibilität. Wir zeigen dass im Bereich mittel schwacher Kopplung nahe der Phasengrenze in der Symmetrie-gebrochenen Phase der "fuzzy bag'' Term Eigenwert Repulsion erzeugt, welche im Grenzfall extrem schwacher Kopplung verschwindet. Wir zeigen dass ein nicht-triviales Z(2) symmetrisches Vakuum existiert. Für die volle Theorie mit Eichfeldern untersuchen wir die räumliche String Spannung und zeigen dass magnetische Observablen vom elektrischen Sektor nur schwach beeinflusst werden. Desweiteren bestimmen wir das effektive Potential des Polyakov Loop, sowohl für den Fall dass alle Fourier Moden betrachtet werden, als auch für "gekühlte'' Konfigurationen ("Block Spins'') in welchen das Polyakov Loop Feld über kleine Volumina gemittelt wird, wodurch kurzreichweitige Fluktuationen unterdrückt werden. Qualitative Vergleiche mit der vierdimensionalen Eichtheorie zeigen dass das Verhalten des Block Spin Potentials in der dreidimensionalen Theorie mit der vierdimensionalen Theorie übereinstimmt
Scaling and asymptotic scaling in the SU(2) gauge theory
No full textFingberg J, Heller UM, Karsch F. Scaling and asymptotic scaling in the SU(2) gauge theory. Nuclear Physics, B. 1993;392(2):493-517.We determine the critical couplings for the deconfinement phase transition in SU(2) gauge theory on N(tau) x N(sigma)3 lattices with N(tau) = 8 and 16 and N(sigma) varying between 16 and 48. A comparison with string tension data shows scaling of the ratio T(c)/square-root sigma in the entire coupling regime beta = 2.30-2.75, while the individual quantities still exhibit large scaling violations. We find T(c)/square-root sigma = 0.69(2). We also discuss in detail the extrapolation of T(c)/LAMBDA(MSBAR) and square-root sigma/LAMBDA(MSBAR) to the continuum limit. Our result, which is consistent with the above ratio, is T(c)/LAMBDA(MSBAR) = 1.23(11) and square-root sigma/LAMBDA(MSBAR) = 1.79(12). We also comment upon corresponding results for SU(3) gauge theory and four-flavour QCD
N-Allylsecoboldine as a Novel Agent Prevents Acute Renal Failure during Endotoxemia
No full textBlockades of cytokine and oxygen radicals release are considered to be beneficial in reducing multiple organ injury and increasing the survival rate in sepsis/septic shock. Thus, we examined the protective efficacy of N- allylsecoboldine, a secoaporphine derivative with antioxidant and alpha 1-adrenoceptor blocking activities, in rats treated with endotoxin (E. coli lipopolysaccharide, LPS ). Pretreatment of LPS-treated rats with N- allylsecoboldine significantly attenuated the late-phase hypotension, hypoglycemia and incremental plasma tumor necrosis factor ( TNF)-alpha. Overproduction of plasma nitrate in endotoxemia was not changed but the continuous decrease of urinary nitrate appeared to be partially ameliorated by N- allylsecoboldine. However, N-allylsecoboldine inhibited the inducible nitric oxide synthase (iNOS) protein expression in the renal cortex of endotoxemic rats. N-allylsecoboldine also improved the endotoxemia-induced organ injury as demonstrated from the conspicuous recovery of marker enzymes in the LPS-treated rats. Endotoxemia was associated with renal dysfunctions as indicated by decreases in renal blood flow, urinary potassium excretion, and renal nitrate clearance. However, pretreatment with N-allylsecoboldine showed significant alleviation of these renal dysfunctions. In addition, a lower dose of N- allylsecoboldine ameliorated the mortality of LPS-treated mice. This study demonstrates N -allylsecoboldine's ability to avail against acute renal failure and increase survival rate during endotoxemia. These beneficial effects may be attributed to the inhibition of iNOS expression, TNF-alpha production, and free radical scavenging activities. However, the role of alpha1- adrenoceptor antagonism for N-allylsecoboldine in sepsis remains unclear
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