1,331 research outputs found
The decay of massive closed superstrings with maximum angular momentum
No full textWe study the decay of a very massive closed superstring (i.e. \alpha' M^2>> 1) in the unique state of maximum angular momentum. This is done in flat ten-dimensional spacetime and in the regime of weak string coupling, where the dominant decay channel is into two states of masses M_1, M_2. We find that the lifetime surprisingly grows with the first power of the mass M: T =c \alpha' M. We also compute the decay rate for each values of M_1, M_2. We find that, for large M, the dynamics selects only special channels of decay: modulo processes which are exponentially suppressed, for every decay into a state of given mass M_1, the mass M_2 of the other state is uniquely determined
Resurgent Analysis of Localizable Observables in Supersymmetric Gauge Theories
No full textLocalization methods have recently led to a plethora of new exact results in supersymmetric gauge theories, as certain observables may be computed in terms of matrix integrals. These can then be evaluated by making use of standard large N techniques, or else via perturbative expansions in the gauge coupling. Either approximation often leads to observables given in terms of asymptotic series, which need to be properly defined in order to obtain nonperturbative results. At the same time, resurgent analysis has recently been successfully applied to several problems, e.g., in quantum, field and string theories, precisely to overcome this issue and construct nonperturbative answers out of asymptotic perturbative expansions. The present work uses exact results from supersymmetric localization to address the resurgent structure of the free energy and partition function of Chern-Simons and ABJM gauge theories in three dimensions, and of N=2 supersymmetric Yang-Mills theories in four dimensions. For each case, the complete structure of Borel singularities is exactly determined, and the relation of these singularities with the large-order behavior of (multi-instanton) perturbative expansions is made fully precise.Localization methods have recently led to a plethora of new exact results in supersymmetric gauge theories, as certain observables may be computed in terms of matrix integrals. These can then be evaluated by making use of standard large N techniques, or else via perturbative expansions in the gauge coupling. Either approximation often leads to observables given in terms of asymptotic series, which need to be properly defined in order to obtain nonperturbative results. At the same time, resurgent analysis has recently been successfully applied to several problems, e.g., in quantum, field and string theories, precisely to overcome this issue and construct nonperturbative answers out of asymptotic perturbative expansions. The present work uses exact results from supersymmetric localization to address the resurgent structure of the free energy and partition function of Chern-Simons and ABJM gauge theories in three dimensions, and of supersymmetric Yang-Mills theories in four dimensions. For each case, the complete structure of Borel singularities is exactly determined, and the relation of these singularities with the large-order behavior of (multi-instanton) perturbative expansions is made fully precise.Localization methods have recently led to a plethora of new exact results in supersymmetric gauge theories, as certain observables may be computed in terms of matrix integrals. These can then be evaluated by making use of standard large N techniques, or else via perturbative expansions in the gauge coupling. Either approximation often leads to observables given in terms of asymptotic series, which need to be properly defined in order to obtain nonperturbative results. At the same time, resurgent analysis has recently been successfully applied to several problems, e.g., in quantum, field and string theories, precisely to overcome this issue and construct nonperturbative answers out of asymptotic perturbative expansions. The present work uses exact results from supersymmetric localization to address the resurgent structure of the free energy and partition function of Chern-Simons and ABJM gauge theories in three dimensions, and of N=2 supersymmetric Yang-Mills theories in four dimensions. For each case, the complete structure of Borel singularities is exactly determined, and the relation of these singularities with the large-order behavior of (multi-instanton) perturbative expansions is made fully precise
Papel del factor de transcripción Kruppel-like factor 2 en la disfunción endotelial hepática asociada a la hipertensión portal y al daño por isquemia y reperfusión
No full textEl endotelio disfuncional presenta, entre otras caracteristicas, alteración en los mecanismos de vasodilatación, complicaciones trombóticas, disminución de la resistencia al estrés oxidativo, aumento de la expresión de moléculas de adhesión y de la secreción de moléculas proinflamatorias. El factor de transcripción endotelial KLF2 juega un importante papel en la regulación del fenotipo protector endotelial y su expresión depende de las fuerza hemodinámicas generadas por el flujo sanguíneo y de la administración exógena de estatinas.
La hipertensión portal y el daño hepático por I/R son dos condiciones patológicas asociadas a disfunción endotelial. Los trastornos estructurales característicos de la cirrosis hepática, la mayor causa prevalente de hipertensión portal en nuestro entorno, se acompañan de variaciones en las fuerzas hemodinámicas que pueden modificar la expresión de KLF2 y su programa transcripcional vasoprotector. Asímismo, durante la isquemia asociada a la preservación de injertos hepáticos para transplante, la interrupción de las fuerzas hemodinámicas generadas por el flujo sanguíneo podría resultar en la reducción de los programas endoteliales vasoprotectores, que se debería en parte a la pérdida de expresión de KLF2.
Los trabajos de investigación de la presente tesis doctoral amplian el conocimiento de los mecanismos moleculares responsables de la disfunción endotelial hepática, demostrando:
1. Que KLF2 está muy expresado en los hígados cirróticos y que su expresión se induce en las fases tempranas de la progresión de la enfermedad, representando un mecanismo compensador para mejorar los desórdenes vasculares característicos de los hígados cirróticos.
2. Que los hígados preservados en condiciones de transplante muestran un descenso tiempo-dependiente de KLF2, acompañado de daño hepático y aumentada resistencia vascular.
Además, demostran que la modulación farmacologica de la expresión de KLF2 puede ser beneficiosa tanto en el tratamiento de la hipertensión portal como en la preservación de los injertos hepáticos para transplante
Exact partition function in U(2) × U(2) ABJM theory deformed by mass and Fayet-Iliopoulos terms
No full textAbstract: We exactly compute the partition function for U(2)k × U(2)− k ABJM theory on S3 deformed by mass m and Fayet-Iliopoulos parameter ζ. For k = 1, 2, the partition function has an infinite number of Lee-Yang zeros. For general k, in the decompactification limit the theory exhibits a quantum (first-order) phase transition at m = 2ζ.Fil: Russo, Jorge Guillermo. Universidad de Barcelona; España. Institució Catalana de Recerca i Estudis Avancats; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Silva, Guillermo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina. Abdus Salam International Centre for Theoretical Physics; Itali
La mente come unità-nella-molteplicità. Cusano e l'interpretazione neoplatonica di Tim. 35 a, in: G. Cuozzo-C. D'Amico-N. Russo (eds.), Nicolás de Cusa: Unidad en la Pluralidad. Homenaje a Jorge Mario Machetta Tomo I, Filo-Uba, Benos Aires 2021, pp. 189-220
No full textIl saggio esamina il ruolo che l'interpretazione neoplatonica del celebre passo di Timeo, 35 a, svolge nella concezione cusaniana della natura e della funzione della mente uman
Handbook on string decay
No full textWe explain simple semi-classical rules to estimate the lifetime of any given
highly-excited quantum state of the string spectrum in flat spacetime. We
discuss both the decays by splitting into two massive states and by massless
emission. As an application, we study a solution describing a rotating and
pulsating ellipse which becomes folded at an instant of time -- the ``squashing
ellipse''. This string interpolates between the folded string with maximum
angular momentum and the pulsating circular string. We explicitly compute the
quantum decay rate for the corresponding quantum state, and verify the basic
rules that we propose. Finally, we give a more general (4-parameter) family of
closed string solutions representing rotating and pulsating elliptical strings.Comment: 18 pages, 9 figures. Final version appeared in JHE
Classical String Dynamics in Curved Backgrounds
No full textTreballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Any: 2014, Tutor: Jorge G. RussoIn this bachelor thesis, we study a rotating classical string embedded in the 5-
dimensional Anti-de-Sitter spacetime (AdS5), through the analysis of the dynamics of the Polyakov
action. We compute its energy E and spin S and discuss the dependence E(S). The function E(S)
is explicitly derived in two limiting cases: the short string case (in which the length of the string is
considerably smaller than the characteristic length of AdS5) and the long string case (in which it is
considerably greater). In the former case, the dependence E(S) previously derived for a
at space
is recovered
La compromissione del legislatore italiano con le leggi razziali: codice civile e codice di procedura civile a confronto. II) Il Fascismo e le leggi: l’ideologia fascista nella codificazione civile.
No full textL’autore, esaminando le fonti storiche e i testi normativi, analizza il livello di compromissione dei giuristi e, soprattutto, dei conditores del codice civile e del codice di procedura civile col fascismo e le leggi razziali. Conclude che, mentre gli autori del codice civile si compromisero in modo aperto con entrambi, il legislatore processuale, pur cedendo in molti punti all’ideologia del regime, riuscì ad evitare ogni compromissione con le leggi razziali.The author, examining the historical sources and normative texts, analyzes the level of compromise of the jurists and, above all, of the conditores of the civil code and the code of civil procedure with fascism and the racial laws. He concludes that, while the authors of the civil code openly compromised with both, the procedural legislator, while giving in to the regime's ideology on many points, managed to avoid any compromise with the racial laws
- …
