411 research outputs found
Supersymmetric Standard Model, Branes and Del Pezzo Surfaces
No full textThe Standard Model of particle physics is one of the most important successful results of the work of the last century physicists. In this new book, the authors present topical research in the study of new developments in the Standard Model. Topics discussed include non-equilibrium theory, fractional dynamics and the physics of the terascale sector; unexplored regions in QFT and the conceptual foundations of the Standard Model; supersymmetric Standard Model, Branes and Del Pezzo surfaces; fermion condensate as Higgs substitute and Lepton flavor violation shedding light on CP-violation.
Even though the Standard Model of particles has been confirme by several experiments, many questions require improvements. Beyond the problem of Grand Unification the mass gap problem, the question of hierarchies, low boson masses and dynamical soft supersymmetry breaking, there is the really hard difficult in including gravity in a full quantum paradigm of the Standard Model. The most famous scheme elaborated in order to solve the last and, possibly, all this points is String Theory.
Dualities, mirror symmetry, M-theory and AdS/CFT are some of the powerful tools
which permit to perform several progresses in all the mentioned directions, at least in principle. However, interactions of String Theory with phenomenology are really recent results. A way to get a contact between theory and phenomenology is the so called bottom-up approach. We will present here a possible String Theory approach to the (Minimal Supersymmetric) Standard Model based on the geometric engineering construction firs proposed in [H. Verlinde and M. Wijnholt, JHEP 0701, 106]. We will study the relevant geometry along the lines of [S.L. Cacciatori and M. Compagnoni, JHEP 1005:078,2010], and the related physics. We will study the singular orbifold C3/27, with 27 a suitable non abelian group, its geometry and show how it can be desingularized. To render technical computations as simple as possible we will work also with a simplifie toric version, studing its main properties at K-theory level, and we will discuss how such calculations should be extended to the non abelian case. The associated relevant physics will be discussed
Experimental quantum cosmology in time-dependent optical media
No full textIt is possible to construct artificial spacetime geometries for light by using intense laser pulses that modify the spatiotemporal properties of an optical medium. Here we theoretically investigate experimental possibilities for studying spacetime metrics of the form . By tailoring the laser pulse shape and medium properties, it is possible to create a refractive index variation that can be identified with . Starting from a perturbative solution to a generalized Hopfield model for the medium described by an , we provide estimates for the number of photons generated by the time-dependent spacetime. The simplest example is that of a uniformly varying that therefore describes the Robertson–Walker metric, i.e. a cosmological expansion. The number of photon pairs generated in experimentally feasible conditions appears to be extremely small. However, large photon production can be obtained by periodically modulating the medium and thus resorting to a resonant enhancement similar to that observed in the dynamical Casimir effect. Curiously, the spacetime metric in this case closely resembles that of a gravitational wave. Motivated by this analogy, we show that a periodic gravitational wave can indeed act as an amplifier for photons. The emission for an actual gravitational wave will be very weak but should be readily observable in the laboratory analogue
D-branes on C^3_6. Part I: prepotential and GW-invariants
No full textThis is the first of a set of papers having the aim to provide a detailed description of brane configurations on a family of noncompact threedimensional Calabi-Yau manifolds. The starting point is the singular manifold C^3/Z_6, which admits five distinct crepant resolutions. Here we apply local mirror symmetry to partially determine the prepotential encoding the GW-invariants of the resolved varieties. It results that such prepotential provides all numbers but the ones corresponding to curves having null intersection with the compact divisor. This is realized by means of a conjecture, due to S. Hosono, so that our results provide a check confirming at least in part the conjecture
Projective superspaces in practice
No full textThis paper is devoted to the study of supergeometry of complex projective superspaces Pn|m. First, we provide formulas for the cohomology of invertible sheaves of the form OPn|m(l), that are pullbacks of ordinary invertible sheaves on the reduced variety Pn. Next, by studying the even Picard group Pic0(Pn|m), classifying invertible sheaves of rank 1|0, we show that the sheaves OPn|m(l) are not the only invertible sheaves on Pn|m, but there are also new genuinely supersymmetric invertible sheaves that are unipotent elements in the even Picard group. We study the Π-Picard group PicΠ(Pn|m), classifying Π-invertible sheaves of rank 1|1, proving that there are also non-split Π-invertible sheaves on supercurves P1|m. Further, we investigate infinitesimal automorphisms and first order deformations of Pn|m, by studying the cohomology of the tangent sheaf using a supersymmetric generalisation of the Euler exact sequence. A special attention is paid to the meaningful case of supercurves P1|mand of Calabi–Yau's Pn|n+1. Last, with an eye to applications to physics, we show in full detail how to endow P1|2with the structure of N=2 super Riemann surface and we obtain its SUSY-preserving infinitesimal automorphisms from first principles, that prove to be the Lie superalgebra osp(2|2). A particular effort has been devoted to keep the exposition as concrete and explicit as possible
On the geometry of C^3/\Delta_{27} and del Pezzo surfaces
No full textWe clarify some aspects of the geometry of a resolution of the orbifold X = C3/Δ27, the noncompact complex manifold underlying the brane quiver standard model recently proposed by Verlinde and Wijnholt. We explicitly realize a map between X and the total space of the canonical bundle over a degree 1 quasi del Pezzo surface, thus defining a desingularization of X. Our analysis relys essentially on the relationship existing between the normalizer group of Δ27 and the Hessian group and on the study of the behaviour of the Hesse pencil of plane cubic curves under the quotient
Equidistribution rates, closed string amplitudes, and the Riemann hypothesis
No full textWe study asymptotic relations connecting unipotent averages of Sp(2g,Z) automorphic forms to their integrals over the moduli space of principally polarized abelian varieties. We obtain reformulations of the Riemann hypothesis as a class of problems concerning the computation of the equidistribution convergence rate in those asymptotic relations. We discuss applications of our results to closed string amplitudes. Remarkably, the Riemann hypothesis can be rephrased in terms of ultraviolet relations occurring in perturbative closed string theory
Odd characteristic classes in entire cyclic homology and equivariant loop space homology
No full textGiven a compact manifoldM and a smooth map g:M → U.(l×l:C) from M to the Lie group of unitary l×l matrices with entries in C, we construct a Chern character Ch-(g) which lives in the odd part of the equivariant (entire) cyclic Chen-normalized cyclic complex Nε(ωT(M × T)) of M, and which is mapped to the odd Bismut-Chern character under the equivariant Chen integral map. It is also shown that the assignment g → Ch-(g) induces a well-defined group homomorphism from the K-1 theory of M to the odd homology group of Nε(ωT(M × T))
Le sculture di Benedetto Cacciatori nella chiesa parrocchiale di Gorgonzola (1819-1849) : precisazioni e documenti
No full textIl complesso monumentale di Gorgonzola – costituito dalla chiesa dei Santi Protaso e Gervaso, dal mausoleo della famiglia Serbelloni, dall’oratorio della SS. Trinità e dal campanile – fu voluto dal duca Gian Galeazzo Serbelloni, il quale incaricò del progetto l’architetto ticinese Simone Cantoni. Mentre la cappella sepolcrale fu edificata nel 1776, gran parte del complesso fu realizzata tra il 1806 e il 1881, in esecuzione del legato testamentario del duca, scomparso nel 1802. Al compimento del grandioso disegno neoclassico concorsero numerose personalità del panorama artistico del tempo: gli scultori Benedetto Cacciatori e Stefano Girola, il professore di Ornato Domenico Moglia, gli stuccatori Giovanni Porta e Carlo Cattori, i pittori Domenico Pozzi, Agostino Comerio e Filippo Bellati, l’architetto Giacomo Moraglia e suo figlio Pietro. Fra il 1819 e il 1849 lo scultore Benedetto Cacciatori (Carrara 1794-1871) realizzò per la parrocchiale di Gorgonzola due sculture in marmo bianco di Carrara, dieci figure monumentali in pietra calcarea, sedici bassorilievi in stucco e tre statue in gesso, più altre sei opere minori. L’occasione per il presente contributo, che vuole essere un significativo aggiornamento per il repertorio di uno dei maggiori scultori dell’Ottocento in area lombarda, è fornita dall’analisi dei due archivi dove ancora oggi si conserva gran parte della documentazione prodotta dal Legato Pio Serbelloni, l’ente giuridico che fu costituito per dare esecuzione alle ultime volontà del duca Gian Galeazzo riguardanti Gorgonzola. I nuovi dati ora a nostra disposizione confermano che l’attività di Cacciatori per la chiesa di Gorgonzola non terminò nel 1820, ma nemmeno entro la seconda metà di quel decennio: lo scultore fornì le prime opere già nel 1819 e l’ultimo documento nel quale compare il suo nome è datato 1849. Inoltre, sulla base delle fonti d’archivio, devono essere attribuite a Cacciatori anche sette sculture la cui paternità era precedentemente incerta
Eluding SUSY at every genus on stable closed string vacua.
No full textIn closed string vacua, ergodicity of unipotent ows provide a key for relat-ing vacuum stability to the UV behavior of spectra and interactions. Infrared finiteness at all genera in perturbation theory can be rephrased in terms of cancelations involving only tree-level closed strings scattering amplitudes. This provides quantitative results on the allowed deviations from supersymmetry on perturbative stable vacua. From a math-ematical perspective, diagrammatic relations involving closed string amplitudes suggest a relevance of unipotent ows dynamics for the Schottky problem and for the construction of the superstring measure
Ultraviolet behavior of conformally reduced quadratic gravity
No full textWe study the conformally reduced R+R2 theory of gravity and we show that the theory is asymptotically safe with an ultraviolet critical manifold of dimension three. In particular, we discuss the universality properties of the fixed point and its stability under the use of different regulators with the help of the proper-time flow equation. We find three relevant directions, corresponding to the g, gR, and gR2 operators, whose critical properties are very similar to the ones shared by the full theory. Our result shows that the basic mechanism at the core of the asymptotic safety program is still well described by the conformal sector also beyond the Einstein-Hilbert truncation. Possible consequences for the asymptotic safety program are discussed
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