<p>We present a quantitative assessment of the anticipated impact of future Electron-Ion Collider (EIC) measurements on the extraction of parton-to-pion fragmentation functions (FFs). Our analysis combines simulated semi-inclusive deep-inelastic scattering (SIDIS) pseudo-data at EIC energies of 45 GeV and 140 GeV with existing single-inclusive electron-positron annihilation (SIA) and SIDIS experimental data. The pion fragmentation functions are determined at next-to-leading-order (NLO) accuracy using a perturbative quantum chromodynamics framework and a neural network parametrization. Uncertainties are rigorously estimated through Monte Carlo sampling, accounting for both experimental errors and variations in input parton distribution functions. Our results demonstrate that incorporating EIC pseudo-data reduces their uncertainties, especially at medium- to-large momentum fractions (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>z</mi></math>). This improvement is particularly pronounced for the gluon and selected quark FFs, highlighting the substantial role that EIC measurements will play in achieving high-precision extractions of FFs and informing future experimental and theoretical developments in collider physics.</p>

Iran

United Arab Emirates

Maryam Soleymaninia

Poland

Hamzeh Khanpour

Majid Azizi

Italy

Hadi Hashamipour

Improved constraints on pion fragmentation functions from simulated electron-ion collider data

<p>We present new parton distribution functions (PDFs) at next-to-leading order and next-to-next-to-leading order in perturbative QCD, derived from a comprehensive QCD analysis of high-precision datasets from combined HERA deep-inelastic scattering, the Tevatron, and the LHC. To improve constraints on quark flavor separation, we incorporate Drell-Yan pair production data, which provides critical sensitivity to the quark distributions. In addition, we include the latest <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> boson production data from the CDF, D0, ATLAS, and CMS collaborations, further refining both quark and gluon distributions. Our nominal QCD fit integrates these datasets and examines the resulting impact on the PDFs and their associated uncertainties. Uncertainties in the PDFs are quantified using the Hessian method, ensuring robust error estimates. Furthermore, we explore the sensitivity of the strong coupling constant, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi>s</mi></msub><mo stretchy="false">(</mo><msubsup><mi>M</mi><mi>Z</mi><mn>2</mn></msubsup><mo stretchy="false">)</mo></math>, and proton PDFs in light of the projected measurements from the Electron-Ion Collider, where improvements in precision are expected. The analysis also investigates the effects of inclusive jet and dijet production data, which provide enhanced constraints on the gluon PDF and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi>s</mi></msub><mo stretchy="false">(</mo><msubsup><mi>M</mi><mi>Z</mi><mn>2</mn></msubsup><mo stretchy="false">)</mo></math>.</p>

Germany

Maral Salajegheh

China

Ulf-G. Meißner

Revisiting constraints on proton PDFs from HERA DIS, Drell-Yan, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> boson production, and projected EIC measurements

In this study, we revisit the extraction of parton-to-<math><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup></math> hadron fragmentation functions, named FF24-<math><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup></math>, focusing on both next-to-leading-order and next-to-next-to-leading-order accuracy in perturbative QCD. Our approach involves the analysis of single inclusive electron-positron annihilation (SIA) data. The two key improvements are, on the one hand, the incorporation of the latest experimental data from the BESIII experiment and, on the other hand, the adoption of neural networks in the fitting procedure. To address experimental uncertainties, the Monte Carlo method is employed. Our investigation also explores the impact of hadron mass corrections on the description of SIA data, spanning a broad kinematic regime with a particular emphasis on the range of small <math><mi>z</mi></math> values. The theory prediction for <math><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup></math> production at both NLO and NNLO accuracy exhibits good agreement with experimental data within their respective uncertainties.

Hubert Spiesberger

Georgia

Determination of <math><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup></math> fragmentation functions including BESIII measurements and using neural networks

In this paper, we use the charged-current Higgs boson production process at future electron-proton colliders, <math><msup><mi>e</mi><mo>−</mo></msup><mi>p</mi><mo>→</mo><mi>H</mi><mi>j</mi><msub><mi>ν</mi><mi>e</mi></msub></math>, with the subsequent decay of the Higgs boson into a <math><mi>b</mi><mover><mi>b</mi><mo>¯</mo></mover></math> pair, to probe the Standard Model effective field theory with dimension-six operators involving the Higgs boson and the bottom quark. The study is performed for two proposed future high-energy electron-proton colliders, the Large Hadron Electron Collider (LHeC) and the Future Circular Collider (FCC-he) at the center-of-mass energies of 1.3 TeV and 3.46 TeV, respectively. Constraints on the <math><mi>C</mi><mi>P</mi></math>-even and <math><mi>C</mi><mi>P</mi></math>-odd <math><mi>H</mi><mi>b</mi><mover><mi>b</mi><mo>¯</mo></mover></math> couplings are derived by analyzing the simulated signal and background samples. A realistic detector simulation is performed and a multivariate technique using the gradient boosted decision trees algorithm is employed to discriminate the signal from background. Expected limits are obtained at 95% confidence level for the LHeC and FCC-he assuming the integrated luminosities of 1, 2 and <math><mrow><mn>10</mn><mtext> </mtext><mtext> </mtext><msup><mrow><mi>ab</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math>. We find that using <math><mrow><mn>1</mn><mtext> </mtext><mtext> </mtext><msup><mrow><mi>ab</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math> of data, the <math><mi>C</mi><mi>P</mi></math>-even and <math><mi>C</mi><mi>P</mi></math>-odd <math><mi>H</mi><mi>b</mi><mover><mi>b</mi><mo>¯</mo></mover></math> couplings can be constrained with accuracies of the order of <math><msup><mn>10</mn><mrow><mo>−</mo><mn>3</mn></mrow></msup></math> and <math><msup><mn>10</mn><mrow><mo>−</mo><mn>2</mn></mrow></msup></math>, respectively, and a significant region of the unprobed parameter space becomes accessible.

Gholamhossein Haghighat

Reza Jafari

Mojtaba Mohammadi Najafabadi

Exploring nonstandard <math><mi>H</mi><mi>b</mi><mover><mi>b</mi><mo>¯</mo></mover></math> interactions at future electron-proton colliders

In this study, we performed calculations and analyses of the structure functions of polarized nucleons and light nuclei, specifically <math><mmultiscripts><mi>He</mi><mprescripts></mprescripts><none></none><mn>3</mn></mmultiscripts></math> and <math><mmultiscripts><mi>H</mi><mprescripts></mprescripts><none></none><mn>3</mn></mmultiscripts></math>, using second-order Feynman diagrams. Our investigation focused on two main aspects: First, we examined the symmetry properties of polarized light sea quarks. Second, we conducted a detailed investigation into the impacts of symmetry breaking on the structure functions of both nucleons and nuclei. To achieve this, we utilized the existing polarized parton distribution functions (polarized PDFs) available in the literature. These PDFs were used to calculate and compare the polarized structure functions <math><msub><mi>g</mi><mn>1</mn></msub></math> and <math><msub><mi>g</mi><mn>2</mn></msub></math> of the nuclei. Additionally, we examined and analyzed the Bjorken and Efremov-Leader-Teryaev sum rules by utilizing the moments of the polarized structure functions. The Lorentz color force components, namely <math><msubsup><mi>F</mi><mi>E</mi><mrow><mi>y</mi><mo>,</mo><mi>n</mi></mrow></msubsup></math> and <math><msubsup><mi>F</mi><mi>B</mi><mrow><mi>y</mi><mo>,</mo><mi>n</mi></mrow></msubsup></math>, were determined using the twist-2, twist-3, and twist-4 matrix elements. When symmetry breaking is applied, it is observed that they have similar magnitudes but opposite signs. Our theoretical predictions for the polarized structure functions of nucleons and light nuclei, taking into account the symmetry breaking of light sea quarks, exhibit better agreement with experimental data.

Fatemeh Arbabifar

Shahin Atashbar Tehrani

Effect of symmetry breaking of polarized light sea quarks on the nucleon and nuclear structure functions, and sum rules

We present an updated set of SKMHS diffractive parton distribution functions (PDFs). In addition to the diffractive deep-inelastic scattering (diffractive DIS) datasets, the recent diffractive dijet cross-section measurement by the H1 experiment from the HERA collider are added to the data sample. The new set of diffractive PDFs, entitled SKMHS23 and SKMHS23-dijet, are presented at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) accuracy in perturbative QCD. Since the gluons directly contribute to jet production through the boson-gluon fusion process, the data on diffractive dijet production in inclusive DIS help constrain the gluon density, allowing for the determination of both the quark and gluon densities with better accuracy. The NLO and NNLO theory predictions calculated using both SKMHS23 and SKMHS23-dijet are compared to the analyzed data showing excellent agreement. The effect arising from the inclusion of diffractive dijet data and higher-order QCD corrections on the extracted diffractive PDFs and data/theory agreements are clearly examined and discussed.

Determination of diffractive PDFs from a global QCD analysis of inclusive diffractive DIS and dijet cross-section measurements at HERA

We present SKMHS22, a new set of diffractive parton distribution functions (PDFs) and their uncertainties at next-to-leading-order and next-to-next-to-leading-order accuracy in perturbative QCD within the xFitter framework. We describe all available diffractive DIS datasets from HERA and the most recent high-precision H1/ZEUS combined measurements considering three different scenarios. First, we extract the diffractive PDFs considering the standard twist-2 contribution. Then, we include the twist-4 correction from the longitudinal virtual photons. Finally, the contribution of subleading Reggeon exchange to the structure-function <math><msubsup><mi>F</mi><mn>2</mn><mi>D</mi></msubsup></math> is also examined. For the contribution of heavy flavors, we utilize the Thorne-Roberts general mass variable number scheme. We show that for those corrections, in particular, the twist-4 contribution allows us to include the high-<math><mi>β</mi></math> region and leads to a better description of the diffractive DIS datasets. We find that the inclusion of the subleading Reggeon exchange significantly improves the description of the diffractive DIS cross-section measurements. We then investigate the stability of the SKMHS22 QCD fit upon the inclusion of higher-order QCD corrections and show that it slightly improves the description of the data. The resulting sets are in good agreement with all diffractive DIS data analyzed, which cover a wider kinematical range than in previous fits. The SKMHS22 diffractive PDFs sets presented in this work are available via the LHAPDF interface. We also make suggestions for future research in this area.

Global QCD analysis of diffractive parton distribution function considering higher twist corrections within the xFitter framework

In this paper, we present a QCD analysis to extract the fragmentation functions (FFs) of unidentified light charged hadron entitled as SHK22.h from high-energy lepton-lepton annihilation and lepton-hadron scattering datasets. This analysis includes the data from all available single inclusive electron-positron annihilation processes and semi-inclusive deep-inelastic scattering (SIDIS) measurements for the unidentified light charged hadron productions. The SIDIS data that has been measured by the COMPASS experiment could allow the flavor dependence of the FFs to be well constrained. We exploit the analytic derivative of the neural network for fitting of FFs at next-to-leading-order (NLO) accuracy in the perturbative QCD. The Monte Carlo method is implied for all sources of experimental uncertainties and the parton distribution functions as well. Very good agreements are achieved between the SHK22.h FFs set and the most recent QCD fits available in literature, namely, JAM20 and NNFF1.1h. In addition, we discuss the impact arising from the inclusion of SIDIS data on the extracted light-charged hadron FFs. The global QCD resulting at NLO for charged hadron FFs provides valuable insights for applications in present and future high-energy measurement of charged hadron final state processes.

Ireland

Neural network QCD analysis of charged hadron fragmentation functions in the presence of SIDIS data

We present the first open-source analysis of fragmentation functions (FFs) of charged pions (entitled ipm-xfitter) performed at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) accuracy in perturbative QCD using the xfitter framework. This study incorporates a comprehensive and up-to-date set of pion production data from single-inclusive annihilation (SIA) processes, together with the most recent measurements of inclusive cross-sections of single pion by the BELLE collaboration. The determination of pion FFs along with their theoretical uncertainties is performed in the zero-mass variable-flavor number scheme (ZM-VFNS). We also present comparisons of our FFs set with recent fits from the literature. The resulting NLO and NNLO pion FFs provide valuable insights for applications in present and future high-energy analysis of pion final state processes.

Hamed Abdolmaleki

Simone Amoroso

Francesco Giuli

Alexander Glazov

Agnieszka Luszczak

United States

Fredrick Olness

CERN

Oleksandr Zenaiev

QCD analysis of pion fragmentation functions in the xFitter framework

In this paper, we study the triple top quark production at the future high-energy proton-proton colliders to probe the four-fermion interactions involving three top quarks. We employ the Standard Model Effective Field Theory (SMEFT) to find the upper limits at 95% CL on the Wilson coefficients of these kinds of four-fermion operators. We consider a detailed analysis with a unique signal signature of two same-sign leptons. A full simulation chain includes all the relevant backgrounds, realistic detector simulations, and a cut-based technique are taken into account. This study is presented for the HE-LHC working at the center of mass energy of 27 TeV with 15 ab$^{−1}$ and FCC-hh working at the center of mass energy of 100 TeV with 30 ab$^{−1}$. We show that the future high-energy proton-proton colliders could reach an impressive sensitivity to four-fermion contact interactions involving three top quarks.

Sara Khatibi

Probing four-fermion operators in the triple top production at future hadron colliders