Classical Double Copy of Spinning Worldline Quantum Field Theory

We study the classical double copy of massive spinning objects in the worldline quantum field theories (WQFT) formalism. We couple the $\mathcal{N}=1$ supersymmetric model to a Yang-Mills background to describe the propagation of a spin-half particle interacting with gluons. At the classical level, this model captures physical effects up to linear order in spin. We propose a double copy relation to map the spin tensors to the gravitation side. Enforcing R-symmetry and supersymmetry (SUSY) on the double copy integrands, we find that the gravitational theory is the ${\cal N}=2$ particle coupled to dilaton-gravity (DG). We check the double copy prescription for the eikonal phase up to next-to-leading order and for radiation at leading order in coupling constants, finding that the Grassmann nature of the spin tensor in WQFT plays a crucial role in finding full agreement with direct calculation in the $\mathcal{N}=2$ model. We show how to deform the SUSY charges of the free theory to include DG. Since the constraints algebra is first class, the worldline model can be quantized, describing the propagation of a massive vector field coupled to DG, in agreement with the literature. In addition, we investigate the double copy without preserving SUSY and R-symmetry, finding that the B-field also couples to the~worldline.Comment: 41 pages, 4 figure

Path integral calculation of heat kernel traces with first order operator insertions

We study generalized heat kernel coefficients, which appear in the trace of the heat kernel with an insertion of a first-order differential operator, by using a path integral representation. These coefficients may be used to study gravitational anomalies, i.e. anomalies in the conservation of the stress tensor. We use the path integral method to compute the coefficients related to the gravitational anomalies of theories in a non-abelian gauge background and flat space of dimensions 2, 4, and 6. In 4 dimensions one does not expect to have genuine gravitational anomalies. However, they may be induced at intermediate stages by regularization schemes that fail to preserve the corresponding symmetry. A case of interest has recently appeared in the study of the trace anomalies of Weyl fermions.Comment: 24 pages, modified title, reference and comments added, matches published versio

Classical off-shell currents

We consider tree-level off-shell currents of two massive particles and $n$ massless bosons in the classical limit, which can be fused into the classical limit of $n+2$ scattering amplitudes. We show that dressing up the current with coherent wave-functions associated with the massive particles leads to the recently proposed Worldline Quantum Field Theory (WQFT) path integral. The currents thus constructed encode solutions of classical equations of motion so they can be applied to contexts where the classical limit is relevant, including hard thermal loops. We give several examples of these currents in scalar, gauge and gravitational theories.Comment: 28 pages, v2: clarifications in Sec.2, references added, typos fixed, matches published versio

Un crepuscolare "minore" Compendio delle esperienze letterarie di Tito Marrone

Si affronta la figura di Tito Marrone, un poeta solo apparentemente "minore" aderente al crepuscolarismo romano, rintracciando le sue relazioni con i maggiori autori coevi, da Corazzini a Pirandello, passando per Rosso di San Secondo. Quella di Marrone è una poetica singolare e originale che riesce a cogliere i cambiamenti di contenuti e stile del suo tempo, oltre a mostrare una particolare sensibilità nelle recensioni teatrali

"L’anno 3000" di Paolo Mantegazza. L’utopia scientifica al servizio del progresso coloniale

The novel L’anno 3000 by Paolo Mantegazza (1897) was linked with an English text translated into Italy in 1890, Looking Backward: 2000-1887 by Edward Bellamy. It was a text that at the time had an incredible success, and which was soon translated into several languages. In Bellamy’s book the travel is exclusively temporal, with a great attention from the author to the verisimilitude, since the protagonist, asleep through hypnosis, awakens in his own city several decades later, showing the differences with respect to his “normal” life. The novel by Mantegazza is different and the pretext of time travel, compared to Bellamy, is less credible: a couple, to celebrate their “fruitful marriage” five years after the “marriage of love”, decides to take a trip through Europe and Asia to Andropolis, a giant megalopolis at the foot of the Himalayas. The trip is an opportunity to present to the reader the different aspects of the cities visited, according to a rigid and rather common scheme that sees in the classics of utopian literature the major antecedents, from Tommaso Campanella to Thomas More passing through Jonathan Swift, especially with regard to employment irony. Each crossed city is analyzed according to one or more utopian aspects, obviously following the scientific suggestions of the author. In opposition to the socialist utopia of Bellamy, inspired by the Marxist theories, Mantegazza proposes an operation sometimes parodistic where the optimism of the colleague is constantly challenged. The only element that, according to the author, could lead humanity to a real improvement of their living conditions is blind trust in progress and in science, through all its forms, in particular demographic control, pharmacology, and its applications to the conception and genetics.The novel L’anno 3000 by Paolo Mantegazza (1897) was linked with an English text translated into Italy in 1890, Looking Backward: 2000-1887 by Edward Bellamy. It was a text that at the time had an incredible success, and which was soon translated into several languages. In Bellamy’s book the travel is exclusively temporal, with a great attention from the author to the verisimilitude, since the protagonist, asleep through hypnosis, awakens in his own city several decades later, showing the differences with respect to his “normal” life. The novel by Mantegazza is different and the pretext of time travel, compared to Bellamy, is less credible: a couple, to celebrate their “fruitful marriage” five years after the “marriage of love”, decides to take a trip through Europe and Asia to Andropolis, a giant megalopolis at the foot of the Himalayas. The trip is an opportunity to present to the reader the different aspects of the cities visited, according to a rigid and rather common scheme that sees in the classics of utopian literature the major antecedents, from Tommaso Campanella to Thomas More passing through Jonathan Swift, especially with regard to employment irony. Each crossed city is analyzed according to one or more utopian aspects, obviously following the scientific suggestions of the author. In opposition to the socialist utopia of Bellamy, inspired by the Marxist theories, Mantegazza proposes an operation sometimes parodistic where the optimism of the colleague is constantly challenged. The only element that, according to the author, could lead humanity to a real improvement of their living conditions is blind trust in progress and in science, through all its forms, in particular demographic control, pharmacology, and its applications to the conception and genetics

Light bending from eikonal in worldline quantum field theory

open3noUsing the worldline quantum field theory (WQFT) formalism for classical scattering, we study the deflection of light by a heavy massive spinless/spinning object. WQFT requires the use of the worldline dressed propagator of a photon in a gravitational background, which we construct from first principles. The action required to set up the worldline path integral is constructed using auxiliary variables, which describe dynamically the spin degrees of freedom of the photon and take care of path ordering. We test the fully regulated path integral by recovering the photon-photon-graviton vertex. With the dressed propagator at hand, we follow the WQFT procedure by setting up the partition function and deriving the Feynman rules which can be used to evaluate it perturbatively. These rules depend on the auxiliary variables. The latter ultimately do not contribute in the geometric-optics regime, which realizes the equivalence between the scattering of a photon and a massive scalar with that of a massless and a massive scalar. Then, the calculation of the eikonal phase and the deflection angle simplifies considerably. Using the eikonal phase defined in terms of the partition function, we calculate explicitly the deflection angle at NLO in the spinless case, and at LO in the spinning case up to quadratic order in spin.openBastianelli F.; Comberiati F.; de la Cruz L.Bastianelli F.; Comberiati F.; de la Cruz L

La rivista Crocevia. Esperienze di una (breve) direzione

à partir de son expérience en tant que directeur de la revue Crocevia, publiée par l’éditeur Besa, l’auteur réfléchit sur l’évolution des études concernant la «littérature italienne de la migration» et surtout sur la notion de «littérature nationale». à l’heure actuelle, où les phénomènes migratoires demeurent un des éléments les plus importants du contexte contemporain, la coexistence, dans le même lieu, des personnes ayant des langues et cultures différentes devrait nous pousser à concevoir différemment l’idée de «littérature nationale» et à reconsidérer les liens entre langue et littérature.Taking off from his own experience as director of Crocevia, journal published by Besa, the author reflects upon the evolution of studies that bear on the «Italian literature of migrations», and especially on the notion of a «national literature». At present, when migrations are one of the most important factors in our contemporary contexts, the coexistence, in the same place and time, of people of different languages and cultures should incite us to take a different view of a «national literature» and to reconsider the links between language and literature