QCDLAT
Strong interactions in the Standard Model and beyond and lattice field theory
The main objective of this project is to search for new fundamental phenomena in Nature by advancing the theoretical knowledge on strongly interacting theories in the Standard Model (SM) and beyond.
- QCD at high temperature and finite density: study of the phase diagram in the temperature - chemical potential plane, precise determination of the Equation of State (EoS) and light screening masses of QCD at chemical potential μ=0 up to temperatures of O(100) GeV, temperature dependence of the axion potential.
QCDLAT
Strong interactions in the Standard Model and beyond and lattice field theory
Research
Standard Model (SM) predictions are in impressive agreement with experimental results from many electroweak and strong interaction processes. However, astrophysical evidence and theoretical arguments suggest that the SM cannot be the ultimate theory.
The main objective of this project is to obtain more stringent theoretical predictions on selected electroweak and strong interaction processes by advancing the theoretical understanding of strongly interacting theories in the SM and beyond. We intend to overcome the current limits in the state of the art with new non-conventional theoretical approaches and novel computational strategies.
The comparison with precision measurements at low energy may give access to information at higher energy scales than direct particle production, thus leading to discoveries of new fundamental phenomena in Nature.
We conduct our research within the lattice field theory regularization, where the dynamics of strongly interacting theories can be studied non-perturbatively from first principles. We aim at computing quantities with a precision at the level of percent or less, which is the accuracy required for the interpretation and the analysis of the wealth of experimental results expected both for sub-nuclear matter and for matter at non-vanishing values of temperature and/or chemical potential.
The results that will be obtained in this project will enable us not only to link experimental findings to the fundamental theory, but also to move beyond what can be measured in experiments and address theoretical questions which may unveil deeper theoretical implications.
The project is organized along the following thematical groups of objectives:
Theme 1: QCD and flavour physics (Milano Bicocca, Parma, Roma Tor Vergata)
The aim is to find new fundamental phenomena in Nature by putting more stringent limits on selected electroweak and strong interaction processes, as well as to improve the precision of the free SM parameters in the quark sector. The goals are the following: (a) a determination of the hadronic contribution to the muon anomalous magnetic moment αμ at a few permille level; (b) a precise calculation of the weak matrix elements of four-fermion operators which enter the ΔS = 2 effective weak Hamiltonian in the SM and beyond; (c) extraction of the matrix elements of the first two rows of the CKM matrix from leptonic and semi-leptonic meson decays, through precise computations of weak matrix elements; (d) a computation of the nucleon mass and several nucleon matrix elements of quark bilinears close or at the physical point, i.e. gA and those necessary for the neutron EDM in the SM and beyond.
Theme 2: QCD at high temperature and finite density (Milano Bicocca, Parma)
The long-term goal is to determine the properties of QCD at finite temperature and baryon chemical potential, and to compute the parameters characterizing the QCD phase diagram in the temperature - chemical potential (T, μ) plane. The goals are: a) to probe the QCD phase diagram by Taylor expansions, gathering information at μ=0, at imaginary μ (where the sign problem is absent) and possibly at real values of μ (on the dominant Lefschetz thimble),aiming at locating the critical end point; b) a percent-level determination of the equation of state of QCD with 2+1 flavours at μ=0 up to temperatures of O(100) GeV, which were never explored so far; c) to determine to a few permille precision the lightest screening masses of QCD with 2+1 flavours at μ=0 up to temperatures of O(100) GeV; d) to carry out an exploratory computation of the topological susceptibility in thermal QCD to determine the T-dependence of the axion potential, an information needed to quantify the hypothetical relic abundance of axions today in the post-inflation scenario.
Theme 3: Theoretical developments (Milano Bicocca, Parma, Roma Tor Vergata)
The development of non-perturbative improvement, renormalization and running will be key contributions to this theme. We will continue our studies on the Lefschetz thimble approach for regularizing gauge theories at finite density, and on the realization of chiral symmetry breaking in QCD. In particular we plan to: a) determine non-perturbatively the renormalization and RG-running of the ΔF = 2 four-fermion operators relevant for studying neutral Kaon oscillations in the SM and beyond by using the chirally-rotated Schroedinger-functional scheme; b) implement our recently proposed procedure, based on shifted boundary conditions in the presence of an imaginary chemical potential, to renormalize non-perturbatively the energy-momentum tensor in QCD; c) compute the flavour-singlet renormalisation constants for the three flavour theory; d) study Yang-Mills theories in 2 dimensions, where an analytic solution is known and can be cast into a sum over critical points, as a laboratory to shed light on a possible Thimble regularisation of gauge theories; e) compute the η' mass in QCD at the percent level.
Theme 4: Computational strategies (Milano Bicocca, Parma)
The conception and implementation of algorithms is one of the pillars on which the project rests. Numerical strategies will be developed to benefit from the progress in HPC systems, with an emphasis on efficient exploitation of multi/many-cores architectures. In particular we intend to: a) further develop the multi-boson domain-decomposed Hybrid Monte Carlo (MB-DD-HMC) by integrating it with master-field simulation techniques; b) further explore the possibility of computing Taylor expansions on Lefschetz thimbles so that regions where only the dominant thimble contribute to physical results can be bridged, and multiple thimbles computations can be avoided; c) develop a new multi-level computational strategy based on MB-DD-HMC for a precise study of the string breaking in QCD; d) apply multi-level integration for computing transport coefficients in the thermal theory; e) develop new NSPT computational strategies, aiming at effectively computing expansions around non-trivial vacua and at a reduction of noise in high order fermionic computations.
QCDLAT
Strong interactions in the Standard Model and beyond and lattice field theory
Publications
A list of selected publications by members of the three groups:
(INFN Milano Bicocca)
1. M. Dalla Brida, L. Giusti, T. Harris, D. Laudicina and M. Pepe,
"Non-perturbative thermal QCD at all temperatures: the case of mesonic screening masses",
JHEP 04 (2022), 034.
2. M.Cè, et al.
"Window observable for the hadronic vacuum polarization contribution to the muon g-2 from lattice QCD",
Phys. Rev. D 106 (2022) no.11, 114502.
3. M. Dalla Brida, L. Giusti, T. Harris and M. Pepe,
"Multi-level Monte Carlo computation of the hadronic vacuum polarization contribution to (g_\mu-2)",
Phys. Lett. B 816 (2021), 136191.
4. M. Bruno and M. T. Hansen,
"Variations on the Maiani-Testa approach and the inverse problem",
JHEP 06 (2021), 043.
5. M. Dalla Brida, L. Giusti and M. Pepe,
"Non-perturbative definition of the QCD energy-momentum tensor on the lattice",
JHEP 04 (2020), 043.
(INFN Parma)
6. P. Dimopoulos et al.,
"Contribution to understanding the phase structure of strong interaction matter: Lee-Yang edge singularities from lattice QCD",
Phys.Rev.D 105 (2022) no.3, 034513.
7. F. Di Renzo and K. Zambello,
"Solution of the Thirring model in thimble regularization",
Phys.Rev.D 105 (2022) no.5, 054501.
8. D. Bachtis, G. Aarts, F. Di Renzo and B. Lucini,
"Inverse Renormalization Group in Quantum Field Theory",
Phys.Rev.Lett. 128 (2022) no.8, 081603.
9. F. Di Renzo, S. Singh and K. Zambello,
"Taylor expansions on Lefschetz thimbles",
Phys.Rev.D 103 (2021) no.3, 034513.
10. L. Del Debbio, F. Di Renzo and G. Filaci,
"Large-order NSPT for lattice gauge theories with fermions: the plaquette in massless QCD",
Eur.Phys.J.C 78 (2018) no.11, 974.
(INFN Roma Tor Vergata)
11. I.C. Plasencia et al. [ALPHA],
"Nonperturbative running of the quark mass for Nf=3 QCD from the chirally rotated Schrödinger functional",
Phys. Rev. D 105 (2022) no.5, 054506.
12. J.Heitger, F.Joswig, P.L.J.Petrak and A.Vladikas,
"Ratio of flavour non-singlet and singlet scalar density renormalisation parameters in Nf=3 QCD with Wilson quarks",
Eur. Phys. J. C 81 (2021) no.7, 606 [erratum: Eur. Phys. J. C 82 (2022) no.2, 104].
13. J.Heitger et al. [ALPHA],
"Ward identity determination of ZS/ZP for Nf=3 lattice QCD in a Schrödinger functional setup",
Eur. Phys. J. C 80 (2020) no.8, 765.
14. M.Bruno et al. [ALPHA],
"Light quark masses in Nf=2+1 lattice QCD with Wilson fermions",
Eur. Phys. J. C 80 (2020) no.2, 169.
15. G.M.de Divitiis et al. [ALPHA],
"Non-perturbative determination of improvement coefficients bm and bA -bP normalisation factor Zm ZP/ZA with Nf=3 Wilson fermions",
Eur. Phys. J. C 79 (2019) no.9, 797.
QCDLAT
Strong interactions in the Standard Model and beyond and lattice field theory
National Coordinator: Michele Pepe (Milano Bicocca)
INFN Milano Bicocca
Matteo Bresciani (100%)
Mattia Bruno (100%)
Marco Cè (100%)
Claudio Destri (100%)
Leonardo Giusti (100%)
Mitsuaki Hirasawa (100%)
Davide Laudicina (100%)
Michele Pepe (100%)
Federico Rapuano (100%)
Pietro Rescigno (100%)
Matteo Saccardi (100%)
Manuele Tettamanti (100%)
Luca Virzì (100%)
INFN Parma
Paolo Baglioni (100%)
Francesco Di Renzo (100%)
Petros Dimopoulos (100%)
INFN Roma Tor Vergata
Giulia Maria de Divitiis (50%)
Augusto Mellini (100%)
Mauro Lucio Papinutto (50%)
Anastassios Vladikas (100%)
QCDLAT
Strong interactions in the Standard Model and beyond and lattice field theory
News
1+1 year Post-Doctoral position in theoretical particle physics at INFN (Gruppo Collegato) Parma (Italy)
Main research field: Lattice Gauge Theory
Details can be found at the URL
https://jobs.dsi.infn.it/index.php?tipo=Assegno%20di%20ricerca
(Bando N. 25864)
Deadline: November 10th, 2023
The announcement is part of a wider call, with positions offered at more then one place; applicants can select at most two sites. Applicants must hold a PhD in theoretical physics before taking up her/his appointment with INFN.
Applications (in electronic form) must be submitted not later than November 10th, 2023 (11:59 a.m. CET) through the website
https://reclutamento.dsi.infn.it/
Interested applicants must indicate Parma and select the research subject "Theoretical and numerical approaches to the study of the QCD phase diagram". For expression of interest and more information, they are invited to contact
Francesco Di Renzo (francesco.direnzo AT unipr.it)
The Parma group
The lattice group of Parma is active on several research topics and has been a pioneer of Numerical Stochastic Perturbation Theory and Thimbles regularization. Currently there are two experienced researchers (Francesco Di Renzo and Petros Dimopoulos) and a couple of PhD students; one master student is taking a thesis soon.
In recent years Parma has been coordinating the European research network EuroPLEx. The group is part of the Department of Mathematical, Physical and Computer Sciences; other theoretical physics research in Parma includes formal field/string theory, cosmology, gravitational waves, statistical mechanics/complex systems, foundations of quantum technologies.
During the last years the Parma lattice group has a most active collaboration with the the lattice group of the Bielefeld University (Dr. Christian Schmidt and several collaborators) on various aspects of the study of the QCD phase diagram.
List of research topics of the Parma group
- QCD phase diagram
- Numerical Stochastic Perturbation Theory
- Thimbles regularization
- Machine Learning
Application of Theoretical Physics Methods to the problem of the RNA folding.
List of recent publications
1. F. Di Renzo, P. Dimopoulos, L. Dini et al. "Contribution to understanding the phase structure of strong interaction matter: Lee-Yang edge singularities from lattice QCD", Phys. Rev. D 105 3, 034513 (2022) [arXiv: 2110.15933 [hep-lat]].
2. F. Di Renzo, K. Zambello, "Solution of the Thirring model in thimble regularization", Phys. Rev. D 105 5, 054501 (2022) [arXiv: 2109.02511 [hep-lat]].
3. D. Bachtis, G. Aarts, F. Di Renzo, B. Lucini, "Inverse Renormalization Group in Quantum Field Theory", Phys. Rev. Lett. 128 8, 081603 (2022), [arXiv: 2107.00466 [hep-lat]].
4. F. Di Renzo, S. Singh, K. Zambello, "Taylor expansions on Lefschetz thimbles", Phys. Rev. D 103 3, 034513 (2021) [arXiv: 2008.01622 [hep-lat]].
5. L. Del Debbio, F. Di Renzo, G, Filaci, "Large-order NSPT for lattice gauge theories with fermions: the plaquette in massless QCD", Eur. Phys. J. C 78 11, 974 (2018), [arXiv: 1807.09518 [hep-lat]].
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