Progetti di ricerca

QCD is the fundamental quantum field theory that describes the strong interactions between particles. It is one of the basic building blocks of the Standard Model of Particle Physics and it is responsible for the formation of nuclear matter. In particular,… Leggi tutto QCD at high temperature plays a crucial role in understanding a large number of physical processes spanning from the cosmological evolution of the early universe to the interpretation of the experimental results of heavy ions collisions. Due to asymptotic freedom, one could hope that a perturbative description of the dynamics of the theory becomes possible in the high temperature regime. However, the behaviour of the theory is strongly non- perturbative even at very high temperatures and the lattice is the only theoretical framework in which a first-principles, non-perturbative study is possible. So far, most of the numerical studies on the lattice are restricted to the low temperature regime (T<2 GeV) due to technical limitations. In the present project we overcome those limitations by using a recent strategy - proposed and developed by our group - based on using shifted boundary conditions along the temporal direction. Despite the novelty, that method has already given interesting results in the calculation of the Equation of State of SU(3) Yang-Mills theory and, more recently, in QCD for the calculation of the mesonic non-singlet screening masses projected onto zero Matsubara frequency. The purpose of the present application is to extend the above calculations studying, for the first time, the non-static sector of the mesonic screening masses and the baryonic one over a wide range of temperatures. These quantities are very interesting observables from the phenomenological point of view, since they encode fundamental properties of the plasma. Moreover, if the unreliability of the perturbative results obtained in the static sector of the mesonic screening masses were confirmed in those new sectors, this will make it clear that the dynamics of the plasma cannot be explained by the knowledge that we have from perturbation theory. We plan to investigate the above mentioned screening masses at 8 different values of temperature, approximately from 3 GeV, up to very high temperature, about 80 GeV. In order to perform the continuum limit extrapolation, we will take into account 4 different values of the lattice spacing. For this reason, we request computational resources for a total of 50 Mch.

The Standard Model of Particle Physics (SM) explains almost all results of all experiments conducted in laboratories on a huge variety of processes in the electroweak and strong interaction sectors. However, it is widely accepted that the SM cannot be the ultimate… Leggi tutto theory of fundamental interactions because it provides no explanation for several phenomena in Nature. The experimental measurement of the muon anomalous magnetic moment �µ currently shows a discrepancy of about 4 standard deviations from the theoretical expectations of the SM. The largest contribution to the theoretical uncertainty comes from the Hadron Vacuum Polarization (HVP) whose first principles, non-perturbative computation can be performed only by Monte Carlo simulations of lattice QCD. However, state of the art techniques have difficulty to further increase the numerical accuracy, which could only be achieved with unfeasibly large amounts of computer time. This project aims at measuring the HVP with an unprecedented precision, exploiting an innovative and very powerful multi-level algorithm. We expect that our method will become the standard for Monte Carlo studies of correlations functions in lattice QCD; the outcomes of this study will enable a lattice QCD determination of HVP to impact the SM prediction for �µ for the first time

Quantum Chromodynamics (QCD) is the fundamental quantum field theory that describes the strong interactions between particles. Its non- perturbative dynamics can be investigated from first principles only by numerical simulations on the lattice. The behaviour of the theory is unknown for temperatures… Leggi tutto above 1-2 GeV due to numerical challenges. This proposal continues a previous one (ID: 2018194651) where, using the theoretical framework based on the formulation of a thermal quantum theory in a moving frame, we are able to explore for the first time and with the accuracy of about 1-2% the thermal properties of QCD up to the Electro-Weak scale. In particular we focus on the Equation of State at zero chemical potential. The present project aims at calculating the renormalization constants of the energy-momentum tensor, concluding the computation started with 2018194651. The data we have collected show that our new method is, by far, more efficient than the state of the art and it will become the standard. The final result of the two parts of the project will be a milestone in the knowledge of the quark-gluon phase of QCD, and it will be of the utmost importance for studying and modeling the evolution of the Early Universe.