Light-Cone Distribution Amplitudes of Hadrons in QCD and their Applications

13 Jan 2020, 08:00 → 24 Jan 2020, 18:00 Europe/Berlin

02.430 (Mainz Institute for Theoretical Physics, Johannes Gutenberg University)

To test the Standard Model of particle physics and to search for new phenomena beyond that theory, various processes are studied that are triggered through electroweak transitions of quarks. A large number of such flavour-changing processes are observed in a form of exclusive decays of hadrons. A complete description of these decays is not possible without knowledge of their hadronic matrix elements. Calculating these matrix elements on the basis of Quantum Chromodynamics (QCD) poses an ongoing challenge. ​Light-cone distribution amplitudes (LCDAs)​ are a central and universal set of inputs used to describe the long-distance components of hadronic matrix elements in QCD. The recent years were marked by significant progress in developing the theory of LCDAs. Their characteristics are currently being computed from first principles using lattice QCD simulations. Furthermore, knowledge of LCDAs is needed when calculating observables of multi-hadron matrix elements in frameworks based on various QCD-based factorization methods. We organize a dedicated scientific program that will bring together the experts from different subfields of QCD and flavour physics to exchange new results and to generate collaborative efforts concerning the theory, phenomenology and 
applications of LCDAs.

Executive Summary (PDF) Executive_Summary_lcda20.pdf

Participants (PDF) List of participants.pdf

Monday 13 January

09:55 → 10:00 Welcome

Speaker: Organizers

intro.pdf

10:00 → 11:00 Kaon electromagnetic form factor from lattice QCD

Speaker: Prof. Christine Davies

mainz-ff.pdf

11:00 → 11:30 Coffee break

15:00 → 15:30 Discussing the light-meson DAs

The light-cone distribution amplitudes of the pseudoscalar and scalar light mesons are (re)analyzed in the pure perturbative QCD approach to the meson transition form factors, as well as,
in the combined analysis of several hard exclusive processes.
The informations obtained from the confrontation with the experimental data, the open questions and the limitations of the approach will be discussed.

Speaker: Dr Kornelija Passek-Kumerički

LCDA2020-passek.pdf

16:00 → 16:30 Coffee break

Tuesday 14 January

10:00 → 11:00 Renormalization of B-meson light-cone distribition amplitudes

The B-meson light-cone distribution amplitudes (LCDAs) are matrix elements of operators involving one heavy-quark field sandwiched between the B-meson state and the vacuum. In this talk, I will present the recent developments regarding the evolution of higher-twist LCDAs as well as the renormalization of the leading-twist LCDA at the two-loop order. In particular, I will discuss how the renormalization group equations (RGEs) of higher-twist operators are completely integrable from spin chain models. I will also explain how to calculate the evolution kernel of the leading-twist LCDA using conformal symmetry.

Speaker: Dr Yao Ji

presentation.pdf

11:00 → 11:30 Coffee break

15:00 → 16:00 Discussion Session: Pion LCDA, status and open problems

Convener: Prof. Vladimir Braun

16:00 → 16:30 Coffee break

Wednesday 15 January

10:00 → 11:00 QED effects and B-meson LCDAs

Speaker: Dr Robert Szafron

MITP_LCDA_2020.pdf

11:00 → 11:30 Coffee break

15:00 → 15:30 Probing pion and kaon LCDAs with data on pion and kaon timelike form factors

Speaker: Dr Rusov Aleksey

15:30 → 16:00 LCDAs for mesons, baryons, and pentaquarks

Speaker: Edward Shuryak

shuryak_wave_function_talk.pdf

16:00 → 16:30 Coffee break

Thursday 16 January

10:00 → 11:00 B_{uds} -> gamma Form Factors in LCSRs @ NLO and 1/lambda_B

Speaker: Roman Zwicky

20_LCDA.pdf

11:00 → 11:30 Coffee break

15:00 → 16:00 Discussion Session: Modelling the B-meson LCDAs

Convener: Danny van Dyk (TU München)

16:00 → 16:30 Coffee break

Friday 17 January

10:00 → 11:00 Gravitational form factors and light-cone distributions for pseudoscalar mesons

The gravitational form factors for a hadron, the form factors for the hadron matrix element of the QCD energy-momentum tensor, not only describe the coupling of the hadron with a graviton, but also serve as unique quantities for describing the shape inside the hadron reflecting dynamics of quarks and gluons, such as the internal shear forces acting on the quarks/gluons and their pressure distributions. The gravitational form factors are also relevant to understanding the origin of hadron mass. We consider the quark/gluon contributions to the gravitational form factors for a pseudoscalar meson, and also for the nucleon. We derive the relations satisfied by the gravitational form factors as direct consequences of the symmetries and the equations of motion in QCD, and connections to the generalized (off-forward) parton distributions. Our results show the connections between the gravitational form factors and the higher-twist quark-gluon correlation effects inside the hadrons. Furthermore, we are able to constrain the twist-four gravitational form factors by the trace anomalies in QCD, and derive the corresponding relations at three loop. We mention properties of the gravitational form factors for a heavy meson in the heavy quark limit, and also prospects to calculate the gravitational form factors using the LCSRs.

Speaker: Prof. Kazuhiro Tanaka

mitp20_1_17_tanaka.pdf

11:00 → 11:30 Coffee break

Monday 20 January

10:00 → 11:00 Moments of light-cone distribution amplitudes from lattice QCD

Speaker: Prof. Gunnar Bali

11:00 → 11:30 Coffee break

15:00 → 15:40 Quarkonium LCDAs from NRQCD

Speakers: Dr Hee Sok Chung, Wai Kin Lai

LCDA2020_HSC.pdf

LCDA_Mainz_WKLai.pdf

16:00 → 16:30 Coffee break

Tuesday 21 January

10:00 → 11:00 LCDAs from Euclidean correlation functions

Speaker: Dr Philipp Wein

LCDA2020_Philipp_Wein.pdf

11:00 → 11:30 Coffee break

14:00 → 15:00 Discussion Session: How to calculate B-meson LCDA using lattice QCD?

Convener: Christoph Lehner

14:00 P -> l nu gamma from Lattice QCD

Speaker: Davide Giusti

Giusti_reph_LCDA20.pdf

15:00 → 15:30 Coffee break

Wednesday 22 January

10:00 → 11:00 Chiral dynamics in hard exclusive reactions

Speaker: Prof. Maxim Polyakov

11:00 → 11:30 Coffee break

15:00 → 15:30 Pion form factor at large momentum transfers from lattice QCD

Speaker: Dr Sara Collins

15:30 → 16:00 Cold Case: Nucleon Form Factor, factor of 2

Calculation of electromagnetic nucleon form factor in perturbative QCD is an old and seamingly over-discussed story, but there is still a shadow hanging over that straightforward calculation. Namely, there is factor of 2 discrepancy among results obtained by different groups.
The usual suspects were normalizations of the nucleon wave function. Different explanations were offered but without conclusive answer and the final statement was that
there are simply two different normalizations which both are equally reasonable. Consequently, the problem appeared: two different physical results. The unpleasant situation was circumvented by taking ratio between various amplitudes and everyone was happy. But no one should be. Years passed, we stumbled upon the problem, decided to reopen the case and definitely solve the mystery. The outcome was surprising and, of course, the answer was where no one expected it.

Speaker: Dr Goran Duplančić

16:00 → 16:30 Coffee break

Thursday 23 January

10:00 → 11:00 tbd

Speaker: Nikolay Kivel

11:00 → 11:30 Coffee break

15:00 → 16:00 Discussion Session: Prospects for Dimeson LCDAs

Convener: Prof. Alexander Khodjamirian

15:00 Contributions

Speakers: Alexander Khodjamirian, K. Keri Vos

Mainz_Dimeson_DA_disc.pdf

16:00 → 16:30 Coffee break

Friday 24 January

10:00 → 11:00 LCSRs with B-meson LCDAs

Speaker: Prof. Yu-Ming Wang

11:00 → 11:30 Coffee break