783 research outputs found

    Renormalized Wick expansion for a modified PQCD

    Full text link
    The renormalization scheme for the Wick expansion of a modified version of the perturbative QCD introduced in previous works is discussed. Massless QCD is considered, by implementing the usual multiplicative scaling of the gluon and quark wave functions and vertices. However, also massive quark and gluon counter-terms are allowed in this mass less theory since the condensates are expected to generate masses. A natural set of expansion parameters of the physical quantities is introduced: the coupling itself and to masses mqm_q and mgm_g associated to quarks and gluons respectively. This procedure allows to implement a dimensional transmutation effect through these new mass scales. A general expression for the new generating functional in terms of the mass parameters mqm_q and mgm_g is obtained in terms of integrals over arbitrary but constant gluon or quark fields in each case. Further, the one loop potential, is evaluated in more detail in the case when only the quark condensate is retained. This lowest order result again indicates the dynamical generation of quark condensates in the vacuum.Comment: 13 pages, one figur

    About the phase space of SL(3) Black Holes

    Get PDF
    In this note we address some issues of recent interest, related to the asymptotic symmetry algebra of higher spin black holes in sl(3,R)×sl(3,R)sl(3,\mathbb{R})\times sl(3,\mathbb{R}) Chern Simons (CS) formulation. We compute the fixed time Dirac bracket algebra that acts on two different phase spaces. Both of these spaces contain black holes as zero modes. The result for one of these phase spaces is explicitly shown to be isomorphic to W3(2)×W3(2)W^{(2)}_3\times W^{(2)}_3 in first order perturbations.Comment: improved presentatio

    Black Holes in the 3D Higher Spin Theory and Their Quasi Normal Modes

    Get PDF
    We present a class of 3D Black Holes based on flat connections which are polynomials in the BTZ hs(λ)×hs(λ)hs(\lambda) \times hs(\lambda)-valued connection. We solve analytically the fluctuation equations of matter in their background and find the spectrum of their Quasi Normal Modes. We analyze the bulk to boundary two-point functions. We also relate our results and those arising in other backgrounds discussed recently in the literature on the subject.Comment: v3: typo corrected in first line of Eq (4.2), improved presentatio

    Partition Function of N=2N=2 Gauge Theories on a Squashed S4S^4 with SU(2)×U(1)SU(2)\times U(1) Isometry

    Get PDF
    We study N=2N=2 supersymmetric gauge theories on a large family of squashed 4-spheres preserving SU(2)×U(1)SO(4)SU(2)\times U(1)\subset SO(4) isometry and determine the conditions under which this background is supersymmetric. We then compute the partition function of the theories by using localization technique. The results indicate that for N=2N=2 SUSY, including both vector-multiplets and hypermultiplets, the partition function is independent of the arbitrary squashing functions as well as of the other supergravity background fields.Comment: version to appear in Nuclear Physics

    Prospectiva. Què passarà en biblioteconomia i documentació durant el 2005-2006?

    Get PDF

    Coastal salina evaporites of the Triassic-Liassic boundary in the Iberian Peninsula : the Alacón borehole

    Get PDF
    The evaporite unit (the Lécera Formation), which was formed at the Triassic-Liassic boundary in the Aragonian Branch of the Iberian Chain, was studied at the 01 Alacón borehole (Alacón village, Teruel province), where it is mainly constituted by a thick (>300 m) succession of predominant sulphates (anhydrite, secondary gypsum and carbonate) overlain by brecciated carbonates. In the evaporite succession, a number of lithofacies were recognized, which can be grouped into an "ideal cycle", from base to top: (C1) massive to banded carbonate mudstone, (C2) alternation of carbonate and anhydrite laminae, (A1) alternation of anhydrite and carbonate bands, (A2) clastic intercalations in the alternation of anhydrite and carbonate bands, (A3) laminated to banded anhydrite, (A4) bedded pseudomorphs, (A5) interstitial pseudomorphs, and (A6) massive to nodular anhydrite. Fine-grained gypsum (anhydrite laminae and bands), bedded selenitic gypsum (bedded pseudomorphs), interstitial selenitic gypsum (interstitial pseudomorphs), and graded-nodular anhydrite (a particular fabric of nodular anhydrite) were the most outstanding depositional lithofacies. The evaporite succession exhibits a marked cyclicity: in the lower part the individual cycles are more similar to the ideal cycle and reflect deeper water settings, whereas in the upper part they correspond to shallower water settings. The evaporite sedimentation mainly occurred in a subsiding coastal basin of the salina or lagoon type. In this setting, the subaqueous precipitation of the carbonate and gypsum lithofacies was followed, in each cycle, by the interstitial growth of anhydrite in exposed conditions. As a whole, the evaporite succession reflects an infilling process. The conversion into anhydrite of the selenitic gypsum -probably also of the rest of depositional gypsum lithofaciesstarted under synsedimentary conditions and followed during shallow to moderate burial diagenesis

    Dilaton stabilization by massive fermion matter

    Full text link
    The study started in a former work about the Dilaton mean field stabilization thanks to the effective potential generated by the existence of massive fermions, is here extended. Three loop corrections are evaluated in addition to the previously calculated two loop terms. The results indicate that the Dilaton vacuum field tend to be fixed at a high value close to the Planck scale, in accordance with the need for predicting Einstein gravity from string theory. The mass of the Dilaton is evaluated to be also a high value close to the Planck mass, which implies the absence of Dilaton scalar signals in modern cosmological observations. These properties arise when the fermion mass is chosen to be either at a lower bound corresponding to the top quark mass, or alternatively, at a very much higher value assumed to be in the grand unification energy range. One of the three 3-loop terms is exactly evaluated in terms of Master integrals. The other two graphs are however evaluated in their leading logarithm correction in the perturbative expansion. The calculation of the non leading logarithmic contribution and the inclusion of higher loops terms could made more precise the numerical estimates of the vacuum field value and masses, but seemingly are expected not to change the qualitative behavior obtained. The validity of the here employed Yukawa model approximation is argued for small value of the fermion masses with respect to the Planck one. A correction to the two loop calculation done in the previous work is here underlined.Comment: 18 pages, 5 figures, the study was extended and corrections on the former calculations and redaction were done. The paper had been accepted for publication in "Astrophysics and Space Science

    Impacto del envejecimiento en el seguro

    Get PDF
    Màster de Direcció d'Entitats Asseguradores i Financeres, Universitat de Barcelona, Facultat d'Economia i Empresa, Curs: 2003-2004, Tutor: Juan Ignacio GuerreroEl Impacto del Envejecimiento en España actualmente es uno de los temas más cruciales desde el punto de vista Económico, Demográfico y Social. Donde el Sector Asegurador debe asumir un papel importante. Por ello, es necesario que nuestra generación adopte una serie de medidas y establezca las bases para garantizar un nivel de vida digno, para nuestros mayores

    Remark on charge conjugation in the non relativistic limit

    Full text link
    We study the non relativistic limit of the charge conjugation operation C\cal C in the context of the Dirac equation coupled to an electromagnetic field. The limit is well defined and, as in the relativistic case, C\cal C, P\cal P (parity) and T\cal T (time reversal) are the generators of a matrix group isomorphic to a semidirect sum of the dihedral group of eight elements and Z2\Z_2. The existence of the limit is supported by an argument based in quantum field theory. Also, and most important, the limit exists in the context of galilean relativity. Finally, if one complexifies the Lorentz group and therefore the galilean spacetime xμx_\mu, then the explicit form of the matrix for C\cal C allows to interpret it, in this context, as the complex conjugation of the spatial coordinates: xx\vec{x} \to \vec{x}^*. This result is natural in a fiber bundle description.Comment: 8 page
    corecore