multiQCD · time-like observables from multi-level lattice QCD
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2019-11-01 → 2021-10-31
- EU contribution
- €191,149
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
time-like observables from multi-level lattice QCD
The Standard Model (SM) of particle physics is the most successful theory of high-energy physics (HEP). It encompasses three of the four fundamental forces of nature, the electromagnetic, weak and strong forces, under the same mathematical framework of a gauge quantum field theory. With the discovery of the Higgs boson at CERN in 2012, which is responsible for giving to the masses of the elementary particle, the SM is now complete. However, the SM does not explain all known phenomena in HEP. Among other things, it does not account for neutrino masses and oscillations, and it does not include dark matter, dark energy, and a quantum theory of gravitation. To be able to understand if any experimental signature is a further indication of physics beyond the SM, one needs to be able to make precise predictions within the SM. My research focuses specifically on Quantum Chromodynamics (QCD), the sector of the SM responsible for the strong force that binds quarks into nucleons and nucleons into atomic nuclei. Because of their very nature of being strong interactions, the best methods to make predictions in the regime in which nucleons and nuclei form require expensive numerical simulations of the theory discretized on a four-dimensional lattice. The ultimate goal of my research is to improve the understanding of these nuclear forces. Specifically, I am targeting the so-called time-like quantities that have so far eluded precise estimations due to the specific time-like kinematic regime, which renders them intrinsically hard and particularly expensive for standard numerical simulations of QCD on the lattice.
Data: CORDIS, © European Union
Project objective
Lattice Quantum Chromodynamics (LQCD) is the only known systematic framework to obtain ab-initio results in the non-perturbative regime of strong interactions. Its relevance to high-energy and nuclear physics has grown significantly in recent years due in part to a series of algorithmic advancements.This project aims to compute time-like observables using numerical simulations of LQCD. Specifically, I will study spectral functions including the R-ratio, that is linked to the hadronic vacuum polarization of the electromagnetic current, and the hadronic tensor, that contains information on deep-inelastic scattering.It is extremely challenging to compute observables intrinsically defined in Minkowski spacetime with lattice techniques, with the main issue being that the simulated quantum field theory is defined in Euclidean spacetime. While Euclidean correlators contain all the information needed to extract real-time physics, performing the analytic continuation with finite-precision data points from numerical simulations is an ill-posed problem. A second issue is that the the computational cost is driven by the loss of the signal of hadronic correlators with Euclidean-time separation, that happens at an exponential rate.I will address these issues and significantly reduce the computational effort needed thanks to algorithms advancements. I plan to solve the signal-to-noise ratio problem using and further developing multi-level Monte Carlo sampling methods, that I recently contributed to extend to theories with fermions. The resulting exponential gain in the quality of the signal is essential to be able to perform the analytic continuation, that I plan to control using state-of-the-art techniques based on the Backus-Gilbert algorithm that have recently been developed by the supervisor.
Original text from CORDIS.
Participants
- ORGANISATION EUROPEENNE POUR LA RECHERCHE NUCLEAIRE · GENEVE 23CoordinatorSwitzerland
Links
Data: CORDIS, © European Union