Search results for "Libraries"
showing 10 items of 255 documents
Gravitational footprints of massive neutrinos and lepton number breaking
2020
We investigate the production of primordial Gravitational Waves (GWs) arising from First Order Phase Transitions (FOPTs) associated to neutrino mass generation in the context of type-I and inverse seesaw schemes. We examine both "high-scale" as well as "low-scale" variants, with either explicit or spontaneously broken lepton number symmetry $U(1)_L$ in the neutrino sector. In the latter case, a pseudo-Goldstone majoron-like boson may provide a candidate for cosmological dark matter. We find that schemes with softly-broken $U(1)_L$ and with single Higgs-doublet scalar sector lead to either no FOPTs or too weak FOPTs, precluding the detectability of GWs in present or near future measurements.…
Sterile neutrinos and B–L symmetry
2017
We revisit the relation between the neutrino masses and the spontaneous breaking of the B-L gauge symmetry. We discuss the main scenarios for Dirac and Majorana neutrinos and point out two simple mechanisms for neutrino masses. In this context the neutrino masses can be generated either at tree level or at quantum level and one predicts the existence of very light sterile neutrinos with masses below the eV scale. The predictions for lepton number violating processes such as mu to e and mu to e gamma are discussed in detail. The impact from the cosmological constraints on the effective number of relativistic degree of freedom is investigated.
Subleading Regge limit from a soft anomalous dimension
2018
Wilson lines capture important features of scattering amplitudes, for example soft effects relevant for infrared divergences, and the Regge limit. Beyond the leading power approximation, corrections to the eikonal picture have to be taken into account. In this paper, we study such corrections in a model of massive scattering amplitudes in N = 4 super Yang-Mills, in the planar limit, where the mass is generated through a Higgs mechanism. Using known three-loop analytic expressions for the scattering amplitude, we find that the first power suppressed term has a very simple form, equal to a single power law. We propose that its exponent is governed by the anomalous dimension of a Wilson loop w…
Operator product expansion coefficients in the exact renormalization group formalism
2020
We study how to compute the operator product expansion coefficients in the exact renormalization group formalism. After discussing possible strategies, we consider some examples explicitly, within the $\epsilon$-expansions, for the Wilson-Fisher fixed points of the real scalar theory in $d=4-\epsilon$ dimensions and the Lee-Yang model in $d=6-\epsilon$ dimensions. Finally we discuss how our formalism may be extended beyond perturbation theory.
Integrands of loop amplitudes within loop-tree duality
2020
Using loop-tree duality, we relate a renormalised $n$-point $l$-loop amplitude in a quantum field theory to a phase-space integral of a regularised $l$-fold forward limit of a UV-subtracted $(n+2l)$-point tree-amplitude-like object. We show that up to three loops the latter object is easily computable from recurrence relations. This defines an integrand of the loop amplitude with a global definition of the loop momenta. Field and mass renormalisation are performed in the on-shell scheme.
Nonperturbative renormalization and O(a)-improvement of the nonsinglet vector current with Nf=2+1 Wilson fermions and tree-level Symanzik improved ga…
2019
In calculating hadronic contributions to precision observables for tests of the Standard Model in lattice QCD, the electromagnetic current plays a central role. Using a Wilson action with O(a) improvement in QCD with Nf flavors, a counterterm must be added to the vector current in order for its on-shell matrix elements to be O(a) improved. In addition, the local vector current, which has support on one lattice site, must be renormalized. At O(a), the breaking of the SU(Nf) symmetry by the quark mass matrix leads to a mixing between the local currents of different quark flavors. We present a nonperturbative calculation of all the required improvement and renormalization constants needed for …
Disegno geometrico e storia dell’arte nell’accademia di Pietro Selvatico (1849-1859)
2016
This book chapter investigates Pietro Selvatico Estense's position as director of the Venice Academy of Fine Arts (1849-1859). During this period art history classes and linear drawing have been strengthened within the academic curriculum.
Einstein's Washington Manuscript on Unified Field Theory
2020
In this note, we point attention to and briefly discuss a curious manuscript of Einstein, composed in 1938 and entitled "Unified Field Theory," the only such writing, published or unpublished, carrying this title without any further specification. Apparently never intended for publication, the manuscript sheds light both on Einstein's modus operandi as well as on the public role of Einstein's later work on a unified field theory of gravitation and electromagnetism.
Joan Roís de Corella, la seua vida i el seu entorn: noves dades per a la història de la cultura en la València del segle xv
2014
This article offers a full updating of the biographical records of the writer Joan Roís de Corella (1435-1497) and his family: his great-grandparents, grandparents, parents, siblings and children. All data are presented in a systematic way, generation by generation, and a new vision of the writer himself is offered. In its documentary section, 432 documents are transcribed or summarised, dating from 1373 to 1516. A broad range of new archival data is presented; other previously known data are corrected or improved. Some examples: Joan Roís de Corella had four children: Magdalena (born 1459), Maria, Joan and Estefania, the latter two by Isabel Martínez de Vera. Joan Roís de Corella was widel…
A multidisciplinary approach to the study of cultural heritage environments: Experience at the Palatina Library in Parma
2015
The aim of this paper is to describe a multidisciplinary approach including biological and particle monitoring, and microclimate analysis associated with the application of the Computational Fluid Dynamic (CFD). This approach was applied at the Palatina historical library in Parma. Monitoring was performed both in July and in December, in the absence of visitors and operators. Air microbial monitoring was performed with active and passive methods. Airborne particles with a diameter of ≥0.3, ≥0.5, ≥1 and ≥5 μm/m3, were counted by a laser particle counter. The surface contamination of shelves and manuscripts was assessed with nitrocellulose membranes. A spore trap sampler was used to identify…