The five day long joint "21st International Workshop on Hadron Structure and Spectroscopy" and 6th workshop on the "QCD Structure of the Nucleon" (IWHSS-QCD-N'25) will be held in San Sebastián, Spain, from September 1 to 5, 2025.
The IWHSS comprises a series (21 editions) of annual workshops organized by COMPASS Collaboration on Hadron Structure and Spectroscopy, with most recent editions being the IWHSS-CPHI-2024 (Yerevan, Armenia), IWHSS-2023 (Prague, Czechia) and IWHSS-2022 (CERN, Switzerland).
This joint workshop will also mark the continuation of the series of QCD-N meetings previously held in Alcalá de Henares (2021), Getxo (2016), Bilbao(2012), Frascati (2006) and Ferrara (2002).
The joint workshop will be preceded by the COMPASS Collaboration meeting on September 1 (morning).
The main focus of the workshop will be on recent developments in the study of nucleon and hadron structure, hadron spectroscopy and related topics in quantum chromodynamics. In particular, the transverse and longitudinal spin structure of the nucleon and 3D imaging in both momentum space (transverse-momentum-dependent parton distributions) and in mixed momentum and position space (generalized parton distributions), including novel correltions between current and target remnants, have gained great attention and seen enormous progress during the last decade. This partially required new approaches from theory and from experiments to obtain correlated information. Semi-inclusive and hard exclusive deep-inelastic lepton-nucleon scattering are indispensable tools in this endeavor and so is proton-proton collision. Furthermore, electron-positron annihilation has become a vital tool to obtain precision information on hadronization, the later being used for probing nucleon structure. Progress has been achieved in the description of the nucleon structure in terms of integrated parton distributions as reflected in the PDF fits using both conventional but also neural-network approaches, all the way to global hybrid fits of parton distribution and fragmentation functions. Lattice gauge theory has been a complementary source of information on the structure of the nucleon, and lately also methods from quantum information more and more find their way to this field.
Experimental results on deep-inelastic scattering (inclusive, semi-inclusive, and exclusive), hadron-hadron collisions, and e+e- annihilation will be reviewed. The conference will emphasize the recent progress in the field from theory, lattice-QCD, and phenomenology. In this edition of the conference series, emphasis will be given to bridging the low-scale description of the nucleon structure and of hadronization and the high-scale observables from collider experiments and on the prospects of new – already planned or simply envisioned – facilities worldwide.
The joint workshop will be held as a single event with a unique timetable and schedule. The scientific programme of the joint workshop will cover the following topics:
- Spin and momentum structure of the nucleon
- Multi-dimensional maps of nucleons: TMDs, GPDs and GTMDs
- Fragmentation and fracture functions
- Meson structure and spectroscopy
- Search for exotics and baryon resonances
- Lattice QCD
- Confinement QCD and Fundamental symmetries
- Dark matter/dark photon searches
- Fixed-target and collider experiments
- Future measurements and experimental proposals
The conference will be organized in plenary sessions. Young physicists–post-docs and students–are especially encouraged to attend. The conference will be held at the Centro Carlos Santamaría in San Sebastián, Spain.
Further information and updates will be posted on the workshop web site.
