Graduate School in Physics and Astrophysics
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ANNUAL REPORT
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name: Davide Vadacchino
email: vadacchi@to.infn.it
ciclo: XXVIII
year completed (1,2 or 3): 3
supervisor: Marco Billo'
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CONFERENCES, WORKSHOP
title: EnLarge Horizons
place: Madrid - Spain
webpage: https://workshops.ift.uam-csic.es/NLHIFT
days:18
talk or poster (Y/N):N
title: Physics on the Riviera 2015
place: Sestri Levante - Italy
webpage: https://agenda.infn.it/conferenceDisplay.py?confId=8823
days:3
talk or poster (Y/N):N
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VISITS AND STAGES
(only those done in the current year)
institution: Physics Department - Swansea University
place: Swansea
starting date: 4/01/2015
days: 90 days
Seminar: On the rigid string contribution to the interquark potential in the 3D U(1) lattice gauge theory.
Place: Physics Department - Swansea University
Date: 10/12/2014
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Research activity/Publications in the current year
I am working on two parallel projects.
The first deals with the effective string description of the confining flux tube in the U(1) lattice gauge theory (LGT) in 3 spacetime dimensions. The possibility of recasting its partition function as that of a spin model makes it a perfect laboratory to test the predictions of effective string theory (EFT) to high precision. The interest for this model, besides the fact that it is the only model for which confinement of electric charges has been proven analytically in a semiclassical approximation, lies in the presence, in the effective action, of a term proportional to the extrinsic curvature of the worldsheet. This should give measurable contributions not only to the intercharge potential, as shown in a preceding work, but also to the broadening of the flux tube. My efforts have been focused on the measurement of those effects on a wide range of couplings and charge separations.
The second with the calculation of thermodynamic potentials and interface free energies using the density of states (D0S) algorithm in the SU(2) lattice gauge theory in 4 spacetime dimensions. The DOS algorithm allows one to compute the density of states of systems with a continouus spectrum that would be intractable with the usual Wang&Landau approach. Its main advantage is the possibility of sidestepping problems as the critical slowing down in the proximity of a second order phase transition, or as the sign problem. In general, in this framework one can compute quantities that cannot be expressed as ordinary vacuum expectation values of some operator. In my work I adapted the standard algorithms used in the simulation of the SU(2) LGT in 4d in order to obtain its density of states function. The goal of this project is to perform a proof of concept of the feasibility of the calculation of the entropy and of the interface free energy, using, respectively, shifted and twisted boundary conditions.
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