Gauge theory renormalizations from the open bosonic string

We present a unified point of view on the different methods available in the literature to extract gauge theory renormalization constants from the low-energy limit of string theory. The Bern-Kosower method, based on an off-shell continuation of string theory amplitudes, and the construction of low-energy string theory effective actions for gauge particles, can both be understood in terms of strings interacting with background gauge fields, and thus reproduce, in the low-energy limit, the field theory results of the background field method. We present in particular a consistent off-shell continuation of the one-loop gluon amplitudes in the open bosonic string that reproduces exactly the results of the background field method in the Feynman gauge.Comment: 14 pages, latex, no figure

Prescriptions for Off-Shell Bosonic String Amplitudes

We give, in the framework of the bosonic string theory, simple prescriptions for computing, at tree and one-loop levels, off-shell string amplitudes for open and closed string massless states. In particular we obtain a tree amplitude for three open strings that in the field theory limit coincides with the three-gluon vertex in the usual covariant gauge and two-string one-loop amplitudes satisfying the property of transversality.Comment: 11 pages, LaTeX, to appear in the proceedings of the workshop "Quantum Aspects of Gauge Theories, Supersymmetry and Unification", Corfu (Greece), 20-26 September 1998. Eq. (12) and numerical factors in eqs. (13) and (16) corrected; some minor changes and references adde

Before and after the quarantine: An approximate study on the psychological impact of COVID-19 on the italian population during the lockdown period

COVID-19 (Corona-Virus Disease 2019) in Italy and the measures that were adopted to contain its diffusion had a strong impact on people’s quality of life and mental health. The objective of the study was to quantify the psychological impact of the lockdown period on the general Italian population during the two weeks when the COVID-19 emergency in Italy was at its peak. The study (1556 adults) was conducted from April 6th to April 12th, 2020. A survey was developed through Google Forms in order to assess different psychological measures (Self Efficacy, Locus of Control, Social Connectedness, Sense of Virtual Community, Flourishing, Positive and Negative Affect, Life Satisfaction, and Risk Propensity). The results were then compared to reference data. Thelockdown period increased arousal mainly for negative emotions, but also for positive emotions, and quality of life seemed to be reduced. From a psychosocial point of view, while social connectedness has decreased during lockdown, probably because of isolation and social distancing, the virtual social community seemed to increase in the same period. Interestingly, we revealed how self efficacy increased during the lockdown period, and, at the same time, the Locus of control appeared as externalized, and the risk propensity as reduced. The results are discussed considering previous literature, and a coherent theoretical framework is proposed in order to refine the forecasting model for the psychological impact of the lockdown

Topological order in Josephson junction ladders with Mobius boundary conditions

We propose a CFT description for a closed one-dimensional fully frustrated ladder of quantum Josephson junctions with Mobius boundary conditions, in particular we show how such a system can develop topological order. Such a property is crucial for its implementation as a "protected" solid state qubit.Comment: 14 pages, 3 figures, to appear in JSTA

Off-shell amplitudes for nonoriented closed strings

In the context of the bosonic closed string theory, by using the operatorial formalism, we give a simple expression of the off-shell amplitude with an arbitrary number of external massless states inserted on the Klein bottle

SURVEY OF HISTORICAL GARDENS: MULTI-CAMERA PHOTOGRAMMETRY VS MOBILE LASER SCANNING

This paper presents an investigation into the characterization of historical gardens by comparing two 3D survey methodologies. In this context, approaches employing terrestrial laser scanning are considered the most accurate, while Mobile Mapping Systems (MMSs) are considered promising due to their extreme productivity. Less common is the use of close-range photogrammetry. This paper compares two approaches based on the use of a wearable MMS and the use of an in-house built photogrammetric multi-camera prototype. The comparison aims to assess the applicability of the two techniques in this field, evaluating their advantages and disadvantages in surveying a historical garden and extracting information for tree inventory, such as the DBH (Diameter at Breast Height) and canopy footprint. We compared the practicality of surveying and processing operations; and the quality and characteristics of the point clouds obtained. Both systems produced a dense representation of the terrain. The multi-camera survey resulted to be more defined due to the lower noise of the point cloud but incomplete in the definition of tree canopies. DBH of tree trunks can be extracted with both systems, except for thinner and finer diameter trunks detected by the MMS approach but not always by the multi-camera. The MMS approach proved more effective thanks to a shorter survey time required to cover an equal area and the fact that the MMS survey alone is sufficient for the geometric description of trees. In contrast, the multi-camera approach cannot avoid integration with an aerial survey for canopy reconstructio

Exact Results for the Roughness of a Finite Size Random Walk

We consider the role of finite size effects on the value of the effective Hurst exponent H. This problem is motivated by the properties of the high frequency daily stock-prices. For a finite size random walk we derive some exact results based on Spitzer's identity. The conclusion is that finite size effects strongly enhance the value of H and the convergency to the asymptotic value (H=1/2) is rather slow. This result has a series of conceptual and practical implication which we discuss.Comment: 5 pages, 3 figure

A variational method from the variance of energy

A variational method is studied based on the minimum of energy variance. The method is tested on exactly soluble problems in quantum mechanics, and is shown to be a useful tool whenever the properties of states are more relevant than the eigenvalues. In quantum field theory the method provides a consistent second order extension of the gaussian effective potential.Comment: 5 ps figure

A general interpolation scheme for thermal fluctuations in superconductors

We present a general interpolation theory for the phenomenological effects of thermal fluctuations in superconductors. Fluctuations are described by a simple gauge invariant extension of the gaussian effective potential for the Ginzburg-Landau static model. The approach is shown to be a genuine variational method, and to be stationary for infinitesimal gauge variations around the Landau gauge. Correlation and penetration lengths are shown to depart from the mean field behaviour in a more or less wide range of temperature below the critical regime, depending on the class of material considered. The method is quite general and yields a very good interpolation of the experimental data for very different materials.Comment: some misprints have been corrected in Eq.(15),(19); more references and comments have been adde

10th September 2005: a bolide airblast in the Gulf of Naples (Southern Italy).

On 10th September 2005 at 17:11 local time (15:11 GMT) a loud boom was heard on the Ischia island. A clear seismic signal was also recorded by the seismic monitoring network of the Neapolitan volcanic areas (Ischia, Campi Flegrei and Mt. Vesuvius) and on a regional station (Mt. Massico). On the base of the seismic recordings and on acoustic phenomena reports, we relate this event to the airblast of a bolide at about 15 Km SW of Ischia at an elevation of about 11.5 Km. The location has been obtained through probabilistic non-linear traveltime inversion in a realistic atmospheric model including wind eff ect. We will show, using statistical estimators, how the traveltime pattern is due to both atmospheric winds and bolide trajectory. Using the same reasoning we discard a human origin (supersonic jet or sea-air missile). In addition, we propose also a new algorithm for a fast acoustic traveltime computation for a moving source