Dublin 2020 - EuroPLEx progress workshop

30 Nov 2020, 08:00 → 3 Dec 2020, 18:00 Europe/Dublin

Gert Aarts (Swansea University), Mike Peardon, Petros Dimopoulos (University of Parma), Stefan Sint (Trinity College Dublin (IE))

This online workshop is organized by the EU funded European network for Particle physics, Lattice field theory and Extreme computing (EuroPLEX  cf. http://europlex.unipr.it/).  Besides status reports by the EuroPLEX working groups, the programme will contain several topical talks, as well as both introductory and advanced talks on scale setting in QCD, the inclusion of electromagnetism, the QCD phase diagram and lattice determinations of the strong coupling. Originally planned as a physical meeting in Dublin, the event will now take place online via zoom. Access is given to registered participants only, registration is free of charge.

Confirmed speakers:

• Luigi Del Debbio (U. Edinburgh)
• Tomasz Korzec  (U. Wuppertal)
• Ernesto Lozano (Investigación y Ciencia)
• Agostino Patella (Humboldt U., Berlin)
• Alberto Ramos (IFIC Valencia)
• Claudia Ratti  (U. Houston)
• Phiala Shanahan (MIT)
• Nazario Tantalo (Rome 2)
• Davide Vadacchino (Trinity College Dublin)
• Lukas Varnhorst  (Marseille)
• Philipp Wein (U. Regensburg)

 

(Non-)Local organizing committee:

• Gert Aarts
• Nico Battelli
• Lucius Bushnaq
• Pietro Butti
• Leonardo Chimirri
• Alessandro Conigli
• Petros Dimopoulos
• Francesco Di Renzo
• Mike Peardon
• Stefan Sint
• Davide Vadacchino

 

 

Monday, 30 November

Status Summary I (access restricted to EuroPLEx members)

1 WP1 Indirect searches for New Physics

Speaker: Carlos Pena Ruano (Universidad Autonoma de Madrid (ES))

WP1_Pena

2 WP2 Direct searches for New Physics

Speaker: Claudio Pica (University of Southern Denmark)

WP2_Pica

3 WP3 QCD under extreme conditions

Speaker: Christian Schmidt (University of Bielefeld)

WP3_Schmidt

4 WP6 Algorithms

Speaker: Gunnar Bali (Universität Regensburg)

WP6_Bali

10:00 Break

5 Introduction to QCD+QED in finite volume

Lattice QCD simulations have entered the precision era. Thanks to the combined efforts of several lattice collaborations, the masses, leptonic and semileptonic decay rates of light pseudoscalar mesons are presently known, in QCD, with sub-percent relative errors. At this level of precision strong isospin breaking and QED radiative corrections cannot be neglected and have to be taken into account with the required non-perturbative accuracy. This can in principle be done by performing lattice simulations of QCD+QED. The inclusion of the electromagnetic interactions in finite volume lattice simulations, however, poses both theoretical and numerical problems.

In particular, as a consequence of Gauss law, electrically-charged states are absent in a finite volume with periodic boundary conditions. While this statement is fairly trivial al the classical level, I will discuss in some detail what it means at the quantum-mechanical level. We will see how C-parity boundary conditions can be used to circumvent this problem in a fully consistent way (and in fact it is the only way if one insists on gauge and translational invariance). A possible lattice discretization of QCD+QED will also be discussed.

Speaker: Agostino Patella

Dublin2020_Patella.pdf

12:00 Lunch Break

6 Machine learning for sampling in lattice field theory

In the context of lattice quantum field theory calculations in particle and nuclear physics, I will describe avenues to accelerate sampling from known probability distributions using machine learning. I will focus in particular on flow-based generative models, and describe how guarantees of exactness and the incorporation of complex symmetries (e.g., gauge symmetry) into model architectures can be achieved. I will show the results of proof-of-principle studies that demonstrate that sampling from generative models can be orders of magnitude more efficient than traditional Hamiltonian/hybrid Monte Carlo approaches in this context.

Speaker: Phiala Shanahan

Dublin2020_Shanahan.pdf

14:30 Break

7 Strong coupling constant from the lattice

The strong coupling constant is one of the crucial ingredients for precision predictions for the LHC.
We discuss lattice inputs for the determination of the strong coupling with a specific focus on the systematic errors.

Speaker: Luigi Del Debbio

Dublin2020_DelDebbio.pdf

Tuesday, 1 December

Status Summary II (access restricted to EuroPLEx members)

8 WP4 Lattice for progress in Formal Field Theory

Speaker: Valentina Forini (Humboldt University Berlin)

WP4_Forini

9 WP5 New Tools for High Precision Lattice QCD

Speaker: Marina Krstic Marinkovic (LMU Munich)

WP5_Krstic_Marinkovic

10 WP7 Hardware-aware Progress in Software

Speaker: Dr Antonin Portelli (The University of Edinburgh)

WP7_Portelli

11 WP8 Advanced Statistics and Data Analysis

Speaker: Biagio Lucini (Swansea University)

WP8_Lucini

10:00 Break

12 A new strategy for the determination of alpha_s

Speaker: Alberto Ramos Martinez

Dublin2020_Ramos.pdf

12:00 Lunch Break

13 Introduction to Scale Setting in QCD

In this lecture I will explain, how a dimensionful scale
is introduced in lattice QCD simulations. All sources of systematic uncertainties are discussed before the whole procedure is demonstrated for the case of the 2+1 flavor simulations of the CLS consortium.

Speaker: Tomasz Korzec

Dublin2020_Korzec.pdf

16:00 Escape Room Team building

Wednesday, 2 December

14 High precision scale setting in lattice QCD

Speaker: Lukas Varnhorst

Dublin2020_Varnhorst.pdf

10:30 Break

15 Sp(2N) gauge theories for beyond the standard model physics

Speaker: Davide Vadacchino

Dublin2020_Vadacchino.pdf

12:00 Lunch Break

16 "Lies-to-Children" and Science Communication

Lies-to-children is a common concept in science education. It refers to the simplified versions of a subject that are usually taught to students in order to provide them with the mental structure needed to move beyond those same lies. One typical example is classical mechanics: a "wrong" picture of reality that is however extremely useful if one wants to understand quantum mechanics and relativity.

In this talk I will explain why lies-to-children is also a pivotal concept to understand science communication. Here it works differently because it is encoded in metaphors, not in the subjects of a curriculum, but the idea is the same. We'll also see how lies-to-children are unavoidable when communicating theoretical physics to a lay audience, and we'll learn how to be aware of their pros and cons in order to use them properly. Finally, through some motivating examples, I will encourage all EuroPLEx members to lie as much and as finely as possible about QCD in QuarkBits, the EuroPLEx collaborative blog.

Speaker: Ernesto Lozano Tellechea

Dublin2020_Lozano.pdf

14:30 Break

17 The QCD Phase diagram: introduction

I will review our current knowledge of the phase diagram of strongly interacting matter. In particular, I will focus on the chiral and deconfinement phase transitions, the corresponding order parameters and their behavior at finite temperature and density.

Speaker: Claudia Ratti

Dublin2020_Ratti_1.pdf

Thursday, 3 December

18 Nucleon axial structure from lattice QCD: Controlling pion pole enhanced excited states

We present a new analysis method that allows you to understand and model excited state contributions in observables that are dominated by a pion pole. We apply this method to extract axial and (induced) pseudoscalar nucleon isovector form factors, which satisfy the constraints due to the partial conservation of the axial current up to expected discretization effects. Effective field theory predicts that the leading contribution to the (induced) pseudoscalar form factor originates from an exchange of a virtual pion, and thus exhibits pion pole dominance. Using our new method, we can recover this behavior directly from lattice data.

(Work in collaboration with Gunnar Bali, Lorenzo Barca, Sara Collins, Michael Gruber, Marius Löffler, Andreas Schäfer, Wolfgang Söldner, Simon Weishäupl and Thomas Wurm.)

Speaker: Phlipp Wein

Dublin2020_Wein.pdf

10:00 Break

19 Estimating finite volume effects in QCD+QED simulations by using relativistic EFTs

Lattice QCD simulations have entered the precision era. Thanks to the combined efforts of several lattice collaborations, the masses, leptonic and semileptonic decay rates of light pseudoscalar mesons are presently known, in QCD, with sub-percent relative errors. At this level of precision strong isospin breaking and QED radiative corrections cannot be neglected and have to be taken into account with the required non-perturbative accuracy. This can in principle be done by performing lattice simulations of QCD+QED. The inclusion of the electromagnetic interactions in finite volume lattice simulations, however, poses both theoretical and numerical problems. A particularly important issue are the finite volume effects. In the case of the masses of stable hadrons these are power-law suppressed in QCD+QED while they vanish exponentially fast in QCD. The issue becomes much more delicate in the case of decay rates where one has to cope with the well known problem of the infrared divergences, i.e. with diverging finite volume effects, that might appear at intermediate stages of the calculations. In this lecture I will discuss how finite volume effects in QCD+QED can be understood and estimated by using relativistic effective field theories techniques. I will discuss in particular the cases of the finite volume effects on the masses of stable hadrons and of the infrared divergences appearing in the leptonic decay rates of pseudoscalar mesons.

Speaker: Nazario Tantalo

Dublin2020_Tantalo.pdf

12:00 Lunch Break

20 The QCD phase diagram: state of the art

I will present the state of the art results on the QCD transition line and constraints on the location of the critical point from lattice QCD simulations.

Speaker: Claudia Ratti

Dublin2020_Ratti_2.pdf

16:00 END