The accurate identification of heavy-flavour jets — those which originate from bottom or charm quarks — is crucial for precision studies of the Standard Model and searches for new physics. However, assigning flavour to jets presents significant challenges, primarily due to issues with infrared and collinear (IRC) safety. This paper aims to address these challenges by evaluating recently-proposed jet algorithms designed to be IRC-safe and applicable in high-precision measurements. We compare these algorithms across benchmark heavy-flavour production processes and kinematic regimes that are relevant for LHC phenomenology. Exploiting both fixed-order calculations in QCD as well as parton shower simulations, we analyse the infrared sensitivity of these new algorithms at different stages of the event evolution and compare to flavour labelling strategies currently adopted by LHC collaborations. The results highlight that, while all algorithms lead to more robust flavour assignments compared to current techniques, they vary in performance depending on the observable and energy regime. The study lays groundwork for robust, flavour-aware jet analyses in current and future collider experiments to maximise the physics potential of experimental data by reducing discrepancies between theoretical and experimental methods.

Germany

Arnd Behring

Switzerland

Simone Caletti

Italy

Francesco Giuli

United Kingdom

Radosław Grabarczyk

Andreas Hinzmann

Alexander Huss

United States

Joey Huston

Ezra Lesser

Simone Marzani

Davide Napoletano

Poland

Rene Poncelet

Daniel Reichelt

Alberto Rescia

Gavin Salam

Australia

Ludovic Scyboz

Federico Sforza

Andrzej Siódmok

Giovanni Stagnitto

James Whitehead

Ruide Xu

Flavoured jet algorithms: a comparative study

<p> We determine the value of the strong coupling <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>α</mi></mrow><mrow><mi mathvariant="normal">s</mi></mrow></msub></mrow></math> and study its running over a wide range of scales as probed by the dijet production process at hadron colliders, based on a next-to-next-to-leading-order QCD analysis of LHC dijet data. From a large subset of these data a value of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><msub><mrow><mi>α</mi></mrow><mrow><mi mathvariant="normal">s</mi></mrow></msub><mo stretchy="false">(</mo><msub><mrow><mi>m</mi></mrow><mrow><mi mathvariant="normal">Z</mi></mrow></msub><mo stretchy="false">)</mo></mrow><mo>=</mo><mn>0.1178</mn><mo>±</mo><mn>0.0022</mn></mrow></math> is obtained for the strong coupling at the scale of the Z-boson mass <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi mathvariant="normal">Z</mi></msub></math>, using the invariant mass of the dijet system to select the scale where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi mathvariant="normal">s</mi></msub></math> is probed. The combination of different datasets enhances the reach and precision of the analysis in the multi-TeV range and allows for the first determination of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>α</mi></mrow><mrow><mi mathvariant="normal">s</mi></mrow></msub></mrow></math> up to scales of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>7</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></mrow></math>. Complementing the LHC data with dijet cross sections measured at the HERA electron–proton collider, the kinematic range is extended to test the running of the strong coupling toward smaller scales. Our results exhibit excellent agreement with predictions based on the renormalization group equation of QCD, and represent a comprehensive test of the asymptotic behavior of QCD, spanning more than three orders of magnitude in energy scale.</p>

Fazila Ahmadova

Daniel Britzger

China

Xuan Chen

Johannes Gäßler

Aude Gehrmann-De Ridder

Thomas Gehrmann

Nigel Glover

Claire Gwenlan

Gudrun Heinrich

CERN

Lucas Kunz

Portugal

João Pires

Klaus Rabbertz

Mark Sutton

Precise Determination of the Strong Coupling Constant from Dijet Cross Sections up to the Multi-TeV Range

<p>Photon pair production is an important benchmark process at the LHC, entering Higgs boson studies and new physics searches. It has been measured to high accuracy, allowing for detailed studies of event shapes in diphoton final states. To enable precision physics with diphoton event shapes, we compute the second-order QCD corrections, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msubsup><mi>α</mi><mi>s</mi><mn>3</mn></msubsup><mo stretchy="false">)</mo></math>, to them and study their phenomenological impact.</p>

Federico Buccioni

Wei-Jie Feng

Matteo Marcoli

Precise Predictions for Event Shapes in Diphoton Production at the LHC

Modern analyses of experimental data from hadron colliders rely on theory predictions at high orders in perturbation theory and a variety of input settings. Interpolation grids facilitate an almost instant re-evaluation of theory predictions for different input parton distributions functions (PDFs) or scale settings and are thus indispensable in the study of the parton content of the proton. While interpolation grids at next-to-next-to-leading order (NNLO) exist for some key processes relevant for PDF determinations, a notable exception is the Drell–Yan process that constitutes the production of electroweak gauge bosons at hadron colliders and provides important constraints on the quark content of the proton. To address this gap, we report on a new interface between the parton-level Monte Carlo generator and the interpolation grid library and demonstrate its use for the Drell–Yan process. Accompanying this note, we release Drell–Yan grids covering a wide range of measurements that commonly enter global determinations of PDFs. We use the grids to study accidental cancellation between partonic channels at NNLO and inspect the validity of a $\textit{K}$-factor approximation that was widely employed previously.

Juan Cruz–Martinez

Christopher Schwan

Fast interpolation grids for the Drell–Yan process

Radiative corrections in pole approximation, which are based on the leading contribution in a systematic expansion of amplitudes about resonance poles, naturally decompose into factorizable corrections attributed to the production or decay of the resonance and non-factorizable corrections induced by soft photon (or gluon) exchange between those subprocesses. In this paper we complete an earlier calculation of mixed QCD × electroweak corrections of  $$\mathcal{O}\left({\alpha }_{{\text{s}}}\alpha \right)$$  to the neutral-current Drell-Yan cross section in pole approximation by including the previously neglected corrections that are solely related to the Z-boson production process. We present numerical results both for differential distributions and for the forward-backward asymmetry differential in the lepton-pair invariant mass, which is the key observable in the measurement of the effective weak mixing angle at the LHC. Carefully disentangling the various types of factorizable and non-factorizable corrections, we find (as expected in our earlier work) that the by far most important contribution at  $$\mathcal{O}\left({\alpha }_{{\text{s}}}\alpha \right)$$  originates from the interplay of initial-state QCD corrections and electroweak final-state corrections.

Stefan Dittmaier

Jan Schwarz

Mixed NNLO QCD × electroweak corrections to single-Z production in pole approximation: differential distributions and forward-backward asymmetry

Charged gauge boson production at hadron colliders is a fundamental benchmark for the extraction of electroweak parameters and the understanding of the proton structure. To enable precision phenomenology for this process, we compute the third-order (<math><msup><mrow><mtext>N</mtext></mrow><mrow><mn>3</mn></mrow></msup></math>LO) QCD corrections to the rapidity distribution and charge asymmetry in W boson production and to the transverse mass distribution of its decay products. Our results display substantial QCD corrections in kinematic regions relevant for Tevatron and LHC measurements. We compare the numerical magnitude of the <math><msup><mrow><mtext>N</mtext></mrow><mrow><mn>3</mn></mrow></msup></math>LO corrections with uncertainties from electroweak input parameters and illustrate their potential impact on the determination of the W boson mass.

Tong-Zhi Yang

Hua Xing Zhu

Transverse mass distribution and charge asymmetry in W boson production to third order in QCD

Identifying the flavor of reconstructed hadronic jets is critical for precision phenomenology and the search for new physics at collider experiments, as it allows one to pinpoint specific scattering processes and reject backgrounds. Jet measurements at the LHC are almost universally performed using the anti-<math><mrow><msub><mrow><mi>k</mi></mrow><mrow><mi>T</mi></mrow></msub></mrow></math> algorithm; however, no approach exists to define the jet flavor for this algorithm that is infrared and collinear safe. We propose a new approach, a flavor-dressing algorithm, that is infrared and collinear safe in perturbation theory and can be combined with any definition of a jet. We test the algorithm in an <math><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> environment and consider the <math><mrow><mi>p</mi><mi>p</mi><mo>→</mo><mi>Z</mi><mo>+</mo><mi>b</mi><mtext>−</mtext><mtext>jet</mtext></mrow></math> process as a practical application at hadron colliders.

Rhorry Gauld

Flavor Identification of Reconstructed Hadronic Jets

Defect characterizes the depth of factorization of terms in differential (cyclotomic) expansions of knot polynomials, i.e. of the non-perturbative Wilson averages in the Chern-Simons theory. We prove the conjecture that the defect can be alternatively described as the degree in  $$q^{\pm 2}$$  <math> <msup> <mi>q</mi> <mrow> <mo>±</mo> <mn>2</mn> </mrow> </msup> </math>   of the fundamental Alexander polynomial, which formally corresponds to the case of no colors. We also pose a question if these Alexander polynomials can be arbitrary integer polynomials of a given degree. A first attempt to answer the latter question is a preliminary analysis of antiparallel descendants of the 2-strand torus knots, which provide a nice set of examples for all values of the defect. The answer turns out to be positive in the case of defect zero knots, what can be observed already in the case of twist knots. This proved conjecture also allows us to provide a complete set of C-polynomials for the symmetrically colored Alexander polynomials for defect zero. In this case, we achieve a complete separation of representation and knot variables.

Russia

E. Lanina

A. Morozov

Defect and degree of the Alexander polynomial

The Drell-Yan process at hadron colliders is a fundamental benchmark for the study of strong interactions and the extraction of electroweak parameters. The outstanding precision of the LHC demands very accurate theoretical predictions with a full account of fiducial experimental cuts. In this Letter we present a state-of-the-art calculation of the fiducial cross section and of differential distributions for this process at third order in the strict fixed-order expansion in the strong coupling, as well as including the all-order resummation of logarithmic corrections. Together with these results, we present a detailed study of the subtraction technique used to carry out the calculation for different sets of experimental cuts, as well as of the sensitivity of the fiducial cross section to infrared physics. We find that residual theory uncertainties are reduced to the percent level and that the robustness of the predictions can be improved by a suitable adjustment of fiducial cuts.

Pier Francesco Monni

France

Emanuele Re

Luca Rottoli

Paolo Torrielli

Third-Order Fiducial Predictions for Drell-Yan Production at the LHC

We analyze the reliability of several techniques for computing jet and hadron spectra at different collision energies. This is relevant for discovering energy loss in the upcoming oxygen-oxygen (OO) run at the LHC, for which a reference <math><mi>p</mi><mi>p</mi></math> run is currently not planned. For hadrons and jets we compute the ratio of spectra between different <math><mi>p</mi><mi>p</mi></math> collision energies in perturbative QCD, which can be used to construct a reference spectrum. Alternatively, it can be interpolated from measured spectra at nearby energies. We estimate the precision of both strategies for the spectra ratio relevant to the oxygen run, and conclude that the central values agree to 4% accuracy for hadrons and 2% accuracy for jets. Finally we propose taking the ratio of OO and <math><mi>p</mi><mi>p</mi></math> spectra at different collision energies, which cleanly separates the experimental measurement and theoretical computation.

Jasmine Brewer

Aleksas Mazeliauskas

Wilke van der Schee

Ratios of jet and hadron spectra at LHC energies: Measuring high-<math><mrow><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></mrow></math> suppression without a <math><mrow><mi>p</mi><mi>p</mi></mrow></math> reference