Precision calculations for future e+e– colliders: targets and tools

7 Jun 2022, 09:00 → 17 Jun 2022, 18:00 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

The main goal is to identify clear theoretical and computational targets for high-precision predictions of relevance to the programme of future e+e– colliders. The workshop will be divided into two parts, of one week each, as follows: 

• Week 1 (7th to 10th of June): select key physics questions and observables
• Week 2 (13th to 17th of June): current status and advancements in multi-loop calculations required to match the precision goals

During Week 1, we will involve both theorists and experimentalists to identify key physics objectives and a set of important observables, to provide clear reference targets for the theory community.

During Week 2, we will dive deeper into the technical aspects of such calculations, with an overview of the status of current computational techniques (with a focus on multi-loop calculations), and discussions on the required future steps.

The workshop will have a limited number of invited talks occupying only a small fraction of the days, with ample time for discussions and collaborative work. We aim at promoting the development of an active community and foster new collaborations that will target these important questions. 

The workshop will be held in a hybrid format. The onsite participation will be limited to 50 people due to current restrictions on conference room occupancy. On the other hand, Zoom participation is unrestricted.

We invite interested people to fill the application form at their earliest convenience. We expect to review applications for in-person participation at the latest by the 30th of April 2022. A block of rooms has been reserved at the CERN hotel for on-site participants.

Tuesday 7 June

12:45 → 13:00 Welcome

FCWorkshop_CERN.pdf

wednesday.pdf

13:00 → 17:00 Talks and discussions: key physics questions and observables

13:00 Possibilities and precision goals at the Z pole

The talk will review the physics potential of future lepton (e+e-) colliders at the Z pole, highlighting in particular the electroweak measurements that rely heavily on theory inputs, such as precision calculations. Primary examples are Z-pole measurements of EW parameters, as well as EW precision observables.

Speaker: Patrick Janot (CERN)

PrecisionGoalsZPole.pdf

14:00 Status of theory calculations for Z-pole observables

The talk will review the status of theory calculations for Z pole precision observables, and highlight the requirements to match the foreseen experimental precision. Moreover, it will compare the EW pseudo-observables and EFT-parameterisation approaches to carry out precision physics at the Z pole.

Speaker: Ayres Freitas

FCee_freitas.pdf

15:00 Coffee break

15:30 Possibilities and precision goals for QCD measurements

The talk will review the physics potential of future lepton (e+e-) colliders at the Z pole, highlighting in particular the QCD measurements that rely heavily on theory inputs, such as precision calculations. Primary examples are Z-pole measurements of the strong coupling constant, hadronic decay rates of W/Z/tau, as well as (mulit-)jet measurements.

Speaker: Stefan Kluth (Max Planck Society (DE))

precisionQCD.pdf

17:00 → 19:00 Reception

Wednesday 8 June

10:00 → 11:00 Coffee Break

13:00 → 17:50 Talks and discussions: key physics questions and observables

13:00 Initial state QED radiation aspects for future lepton colliders

The talk will discuss the latest progress in the description of QED corrections to the initial state, such as the application and limitations of collinear factorisation to beamstrahlung and YFS approaches. This talk highlights the necessary steps to achieve the precision demanded by future lepton collider experiments.

Speaker: Stefano Frixione (INFN)

eeisr.pdf

14:00 TH colloquium

https://indico.cern.ch/event/1124737/

15:00 Coffee break

15:30 Theory aspects in top-pair production

The talk will review the status of theory calculations for tt production at threshold energies and above at future lepton colliders, and highlight the requirements to match the foreseen experimental precision.

Speaker: Martin Beneke (Technische Universitaet Muenchen (DE))

cern.pdf

16:30 Experimental possibilities at and above the top-pair threshold

The talk will review the physics potential of future lepton (e+e-) colliders at the tt threshold and above, highlighting in particular the experimental targets and those measurements that rely heavily on theory inputs, such as precision calculations.

Speaker: Frank Simon (Max-Planck-Institut fuer Physik)

TopPhysicsExperiment.pdf

Thursday 9 June

10:00 → 11:00 Coffee Break

13:00 → 18:30 Talks and discussions: key physics questions and observables

13:00 Experimental constraints on Higgs properties

The talk will review the physics potential of future lepton (e+e-) colliders for Higgs production, e.g. Higgs-strahlung (e e -> HZ) and VBF (e e -> H v v (W W -> H)), highlighting in particular the experimental targets and those measurements that rely heavily on theory inputs, such as precision calculations.

Speaker: Jenny List (Deutsches Elektronen-Synchrotron (DE))

jlist_eehiggs_220609.pdf

14:00 Theory precision for Higgs observables

The talk will review the status of theory calculations for H production, e.g. Higgs-strahlung (e e -> HZ) and VBF (e e -> H v v (W W -> H)), and Higgs decays at future lepton colliders, and highlight the requirements to match the foreseen experimental precision.

Speaker: Li Lin Yang

2022-06-09 FCC-ee.pdf

15:00 Coffee break

15:30 Non-perturbative aspects of QCD jet observables

The talk will review the current understanding of non-perturbative (linear) corrections to final state observables at lepton colliders, such as event shapes and jet rates. The prospects for new calculations needed at future e+e- machines should be highlighted in view of the accuracy required at these experiments.

Speaker: Paolo Nason (Max Planck Society (DE))

FCC-9-6-22.pdf

16:30 Prospects for precision QCD jet calculations

This talk will review calculations for multi-jet production in e+e- collisions; emphasizing the precision targets and prospects for new calculations needed at future colliders, and whether these can be achieved with state-of-the-art technology.

Speaker: Andrea Banfi (University of Sussex)

banfi_CERN_22.pdf

Friday 10 June

10:00 → 10:30 Coffee Break

10:30 → 11:30 QCD seminar: On phase-space integrals with Heaviside functions

indico: https://indico.cern.ch/event/1151481/

Speaker: Maximilian Delto

13:00 → 17:10 Talks and discussions: key physics questions and observables

13:00 Precision electroweak physics above the Z pole

The talk will review the physics potential of future lepton (e+e-) colliders for EW precision physics above the Z pole, highlighting in particular the experimental targets and those measurements that rely heavily on theory inputs, such as precision calculations.

Speaker: Graham Wilson

Wmass_GWW_CERN_V1.pdf

14:00 Coffee break

14:30 W properties at the pair-production threshold

This talk will review the physics potential of future lepton (e+e-) colliders for EW precision physics at the WW threshold, highlighting in particular the experimental targets for the measurement of the W-boson mass and width.

Speaker: Paolo Azzurri (Universita & INFN Pisa (IT))

azzurriCERNPrecision100622.pdf

15:30 Summary of week 1

Monday 13 June

12:40 → 13:00 Summary of week 1 & objectives for week 2

week-2.pdf

13:00 → 17:00 Talks and discussions: multi-loop computational techniques

13:00 Latest IBP reduction techniques

The talk will review the status and future prospects of IBP reduction techniques. The importance and impact of finite-field based calculations, analytic reconstruction, multivariate partial fractioning and syzygys should be discussed.

Speaker: Tiziano Peraro (University of Bologna and INFN)

Tiziano_Peraro.pdf

14:00 Modern calculation techniques for multi-scale loop amplitudes

The talk will review modern techniques to compute multi-leg/loop amplitudes, as well as future prospects for applications in e+e- collisions. Analytic and numerical techniques will be compared.

Speaker: Vasily Sotnikov (University of Zurich (UZH))

Sotnikov_CERN_ee_precision.pdf

15:00 Coffee break

15:30 OpenLoops @ 2 loops

The talk will discuss the status and future prospects for the numerical calculation of two-loop integrands and amplitudes with OpenLoops, focusing on applications to future e+e- colliders.

Speaker: Max Zoller (PSI)

Zoller_CERN_ee_2022.pdf

17:00 → 19:00 Reception

Tuesday 14 June

10:00 → 11:00 Coffee Break

13:00 → 17:00 Talks and discussions: multi-loop computational techniques

13:00 Local unitarity: perspectives for future lepton colliders

The talk will discuss the status and future prospects of the Loop-Tree Duality approach for the calculation of higher-order corrections to cross sections relevant for future e+e- colliders (both for QCD and EW corrections).

Speaker: Valentin Hirschi (CERN)

FCC_ee_workshop_LU.pdf

14:00 Integrand subtraction & numerical integration

The talk will discuss the status and future prospects of integrand-subtraction methods to construct locally finite two-loop amplitudes, focusing on applications to future e+e- colliders.

Speaker: Charalampos Anastasiou

HPFCee_Anastasiou.pdf

15:00 Coffee break

15:30 Analytic methods for multi-loop calculations

The talk will discuss the recent calculations of EW corrections to Drell-Yan and of the four-loop form factor, highlighting how these calculations and the technology adopted can be exploited for multiloop computations at future lepton colliders.

Speaker: Andreas von Manteuffel (Michigan State University)

manteuffel-ee-2020.pdf

Wednesday 15 June

10:00 → 11:00 Coffee Break

13:00 → 17:40 Talks and discussions: multi-loop computational techniques

13:00 Numerical evaluation of QCD virtual corrections with top quarks in e+e- collisions

The talk will discuss recent multi-loop calculations involving heavy quarks, highlighting how these calculations and the technology adopted can be exploited for multiloop computations at future e+e- colliders.

Speaker: Long Chen

Chen_FCCeeWorkshop.pdf

14:00 TH colloquium

https://indico.cern.ch/event/1155782/

15:00 Coffee break

15:30 Elliptic integrals

The talk will discuss the current understanding of elliptic integrals and future prospects in the context of multiloop calculations for future e+e- colliders. The talk will cover both the aspect of the analytic calculation of this class of integrals as well as their numerical evaluation.

Speaker: Stefan Weinzierl (Universität Mainz)

cern8.pdf

Thursday 16 June

10:00 → 11:00 Coffee Break

13:00 → 17:00 Talks and discussions: multi-loop computational techniques

13:00 Numerical calculations using pySecDec

The talk will discuss recent multi-loop calculations with PySecDec, highlighting how these calculations and the technology adopted can be exploited for multiloop computations at future e+e- colliders (e.g. EW corrections and reactions involving quark masses).

Speakers: Vitalii Ivanovych Maheria, Vitalii Maheria

magerya-futurecollider2022-pysecdec.pdf

14:00 Feynman parametrization and numerical integration

The talk will discuss the status of the calculation of electroweak pseudo-observables, as well as the methodology to evaluate Feynman-parameter integrals numerically, with a focus on the Mellin-Barnes method. The prospects for future applications at future e+e- machines will be highlighted.

Speakers: Janusz Gluza (University of Silesia (PL)), Janusz Gluza (U. Silesia)

CERN_TH_MB_2022.pdf

15:00 Coffee break

15:30 Mixed QCD-EW corrections to neutral-current Drell-Yan

The talk will discuss the recent calculations of QCD-EW corrections to Drell-Yan, highlighting how these calculations and the technology adopted can be exploited for multiloop computations at future lepton colliders.

Speaker: Narayan Rana (INFN Milan)

Rana_FCCee.pdf

Friday 17 June

10:00 → 11:00 Coffee Break

13:00 → 17:00 Talks and discussions: multi-loop computational techniques

13:00 DiffExp and Feynman parameter integration

The talk will discuss the status and applications of the generalized power-series solution of differential equations (e.g. DiffExp, CAESAR), highlighting how this technology can be exploited for multiloop computations at future lepton colliders.

Speaker: Martijn Hidding (Uppsala University)

Talk_FCCee.pdf

14:00 Coffee break

14:30 The AMFlow approach

The talk will discuss the status and applications of the AMFlow method to the calculation of IBP systems and the solution of differential equations for master integrals. The talk will highlight how this technology can be exploited for multiloop computations at future lepton colliders.

Speaker: Xiao Liu (University of Oxford)

XLiu20220617.pdf

15:30 Workshop wrap up