%% ECT* Workshop 2025 — "Few-Body Systems and Universality"
%% Combined proceedings: single document, collective author list, single bibliography.
%%
%% Compilation:
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%%   bibtex   ectWS_report_FBsys_combined
%%   pdflatex --shell-escape ectWS_report_FBsys_combined
%%   pdflatex --shell-escape ectWS_report_FBsys_combined
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%% Notes:
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%%   If Jackura's bibi.bib is unavailable, comment out that \bibliography entry.
%%   Van Kolck's inline bibliography must be converted to vanKolck/vankolck.bib
%%   (see NOTE below) before his references appear in the combined list.

%% Springer "Few-Body Systems" journal class (svjour3 + spphys.bst).
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%\usepackage{bbold}       % conflicts with amssymb on some systems; load if needed
\usepackage{dsfont}       % \mathds{1}
\usepackage{braket}       % Dirac notation
\usepackage{physics}      % \qty, \dd, \grad, etc.  (loaded after amsmath)
\usepackage{scalerel,stackengine}
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\usepackage{dcolumn}
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\usepackage{microtype}
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\usepackage{enumitem}

%% ---- Cross-references ----
\usepackage[numbers,sort&compress]{natbib}
\usepackage[hidelinks,
  pdftitle={ECT* Workshop 2025 -- Few-Body Systems and Universality},
  pdfauthor={Briceno, Blume, Kirscher (eds.)}]{hyperref}
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%% ---- Springer journal name (sets the running head box) ----
\journalname{Few-Body Systems}

%% -----------------------------------------------------------------------
\begin{document}

%% ===== Front matter (Springer svjour3) ==================================
\title{Few-Body Systems and Universality}
\subtitle{Proceedings of the ECT* Workshop ``Universality in
  strongly-interacting systems: from QCD to atoms'',
  Trento, Italy, July 2025}
\titlerunning{Few-Body Systems and Universality}
\authorrunning{Brice\~no, Blume, Kirscher (eds.)}

%% Collective author list of the contributors.  Per-contribution authors and
%% their affiliations are given in the individual sections ("by ...").
%% TODO (editors): add per-author affiliations via \at if a full
%% "Authors and Affiliations" block is required by the journal.
\author{%
  J.~Kirscher \and U.~van~Kolck \and S.D.~G{\l}azek \and
  A.~Kievsky \and M.~Gattobigio \and L.~Girlanda \and M.~Viviani \and
  Y.~Capitani \and A.~Deltuva \and L.~Madeira \and F.~Wu \and T.~Mitra \and
  S.M.~Dawid \and D.~Hoban \and N.~Chambers \and A.W.~Jackura \and M.~Mai \and
  C.~Kacir \and J.~Moscoso \and A.~Nicholson \and T.R.~Richardson \and C.~Rodgers}
\institute{Editors: Ra\'ul Brice\~no, Doerte Blume, Johannes Kirscher
  \at ECT*, Fondazione Bruno Kessler, Trento, Italy}
\date{Received: date / Accepted: date}

\maketitle

\begin{abstract}
An infinite correlation length is synonymous with a rescaling invariance which implies
behavior that is common, i.e., \emph{universal}, to all those degrees of freedom exhibiting this
infinite correlation length. The following articles report on such universal features from
the perspective of particle, nuclear, and atomic physics as they were discussed at the ECT* workshop ``Universality in strongly-interacting systems: from QCD to atoms''.
For this workshop, Efimov three-body physics has been a guiding theme through
its analytical tractability while universal four- and more-body phenomena were presented
as numerical analyses. Aside from few-body dynamics and its modern computational handling,
the meeting exposed the community to the insights provided by a quasi-analytical investigation of the
analytical structure of S-matrices. Furthermore, the few instances of universality
in many-body systems were discussed in form of hydrodynamic attractors and
quantum-field-theoretical analyses of statistical properties of many-fermion correlation
functions.
\keywords{Few-body systems \and Universality \and Effective field theory
  \and Efimov physics \and Unitarity \and S-matrix \and Hydrodynamic attractors}
\end{abstract}

%% ===== Table of Contents ================================================
\tableofcontents
\clearpage

%% ===== Contributions ====================================================

%% ----- 1. Kirscher ------
\sectionheader{Introduction}{Johannes Kirscher}
\input{kirscher_body}

%% ----- 2. van Kolck -----
\sectionheader{Universality with Effective Field Theory}{U.~van~Kolck}
\input{vankolck_body}

%% ----- 3. Glazek --------
\sectionheader{Universality of limit cycles in renormalization
  of quantum Hamiltonians}{Stanis\l{}aw D.~G\l{}azek}
\input{glazek_body}

%% ----- 4. Kievsky -------
\sectionheader{The three-body parameter}{A.~Kievsky, M.~Gattobigio,
  L.~Girlanda, M.~Viviani}
\input{kievsky_body}

%% ----- 5. Capitani ------
\sectionheader{Cluster EFT calculations of electromagnetic breakup
  reactions with the Lorentz Integral Transform method}{Ylenia Capitani}
\input{capitani_body}

%% ----- 6. Deltuva -------
\sectionheader{Four-boson universality}{Arnoldas Deltuva}
\input{deltuva_body}

%% ----- 7. Madeira -------
\sectionheader{Effective field theory for atomic $^4$He clusters}{Lucas Madeira}
\input{madeira_body}

%% ----- 8. Wu ------------
\sectionheader{Bosonic few-body systems expanded around the unitarity limit}{Feng Wu}
\input{wu_body}

%% ----- 9. Mitra ---------
\sectionheader{Hydrodynamic attractors --- Fluid dynamics beyond equilibrium}{Toshali Mitra}
\input{mitra_body}

%% ----- 10. Dawid --------
\sectionheader{Analyticity of three-body amplitudes and Efimov states}{Sebastian~M.~Dawid,
  Declan~Hoban, Nicholas~Chambers}
\input{dawid_body}

%% ----- 11. Jackura ------
\sectionheader{Three-Body Dynamics from Quantum Chromodynamics}{Andrew~W.~Jackura}
\input{jackura_body}

%% ----- 12. Mai ----------
\sectionheader{Universal Implications of $S$-matrix Unitarity}{Maxim Mai}
\input{mai_body}

%% ----- 13. Nicholson ----
\sectionheader{Determining universal spectra from probability
  distributions}{Charles~Kacir, Joseph~Moscoso, Amy~Nicholson,
  Thomas~R.~Richardson, Cade~Rodgers}
\input{nicholson_body}

%% ===== Combined bibliography ============================================
%%
%% NOTE on van Kolck: His contribution uses \begin{thebibliography}
%% inline.  To merge those references into this single bibliography,
%% create vanKolck/vankolck.bib from the \bibitem entries in
%% vanKolck/vankolck_ect25.tex and uncomment the entry below.
%%
%% NOTE on Jackura: bibi.bib extracted from jackura_ectstar.zip to
%% Jackura/bibi.bib.
%%
%% The 14 per-contribution .bib files define 239 keys more than once, which
%% BibTeX reports as 135 "Repeated entry" errors when reading them directly.
%% merge_bibs.py folds them into combined_refs.bib using BibTeX's own first-wins
%% rule, so the bibliography is unchanged and the errors disappear.  Edit the
%% per-contribution files and re-run `python3 merge_bibs.py`.
\bibliographystyle{spphys}
\bibliography{combined_refs}

\end{document}
