We present a determination of fragmentation functions (FFs) for the octet baryon Xi(-)/(Xi) over bar (+) from data for single inclusive electron-positron annihilation. Our parametrization in this QCD analysis is provi...
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We present a determination of fragmentation functions (FFs) for the octet baryon Xi(-)/(Xi) over bar (+) from data for single inclusive electron-positron annihilation. Our parametrization in this QCD analysis is provided in terms of a Neural Network (NN). We determine fragmentation functions for Xi(-)/(Xi) over bar (+) at next-to-leading order and for the first time at next-to-next-to-leading order in perturbative QCD. We discuss the improvement of higher-order QCD corrections, the quality of fit, and the comparison of our theoretical results with the fitted datasets. As an application of our new set of fragmentation functions, named SHKS22, we present predictions for Xi(-)/(Xi) over bar (+) baryon production in proton-proton collisions at the LHC experiments. (c) 2022 Published by Elsevier B.V.
Machine learning is rapidly making its path into the natural sciences, including high-energy physics. We present the first study that infers, directly from experimental data, a functional form of fragmentation functio...
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Machine learning is rapidly making its path into the natural sciences, including high-energy physics. We present the first study that infers, directly from experimental data, a functional form of fragmentation functions. The latter represent a key ingredient to describe physical observables measured in high-energy physics processes that involve hadron production, and predict their values at different energies. fragmentation functions cannot be calculated in theory and have to be determined instead from data. Traditional approaches rely on global fits of experimental data to learn the parameters of a pre-assumed functional form inspired from phenomenological models of hadron production. This novel approach uses an ML technique, namely symbolic regression (SR), to learn an analytical model from measured charged hadron multiplicities. The function studied by SR resembles the Lund string function and describes the data well, thus representing a potential candidate for use in global FFs fits.
We have measured the flavor dependence of multiplicities for pi(+ )and pi(-) production in semi-inclusive deep-inelastic scattering (SIDIS) on proton and deuteron to explore a possible charge symmetry violation in fra...
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We have measured the flavor dependence of multiplicities for pi(+ )and pi(-) production in semi-inclusive deep-inelastic scattering (SIDIS) on proton and deuteron to explore a possible charge symmetry violation in fragmentation functions. The experiment used an electron beam with energies of 10.2 and 10.6 GeV at Jefferson Lab and the Hall-C spectrometers. The electron kinematics spanned the range 0.3< x <0.6, 2< Q( 2)<5.5 GeV2, and 2.2< W <3.2 GeV. The pion fractional momentum range was 0.3< z <0.7, and the transverse momentum range was 0< p(T) <0.25 GeV/c. Assuming factorization and allowing for isospin breaking, the results can be described by two "favored" and two "unfavored" effective low p(T) fragmentation functions that are flavor-dependent. We find each pair converges to a common flavor-independent fragmentation function at the highest W, where factorization is most applicable.
Several groups have recently investigated the flow of information in high-energy collisions, from the entanglement entropy of the proton yielding classical Shannon entropy of its parton distribution functions (pdfs), ...
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Several groups have recently investigated the flow of information in high-energy collisions, from the entanglement entropy of the proton yielding classical Shannon entropy of its parton distribution functions (pdfs), through jet splitting generating entropy, to the entropy distribution in hadron *** in the literature is a discussion of the information entropy of fragmentation functions (FFs) in the instances where they can be considered as probability distributions, and we here provide it. We find that this entropy is a single, convenient number to characterize future progress in the extraction of fragmentation *** also deploy the related Kullback-Leibler divergence between two distributions to assess existing relations among FFs and parton distribution functions (pdfs) such as that of Barone, Drago and Ma. From a couple of current parametrizations of FFs, we do not find supporting empirical evidence for the relation, although it is possible that FFs and pdfs have similar power-laws near the x = 1 endpoint.(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons .org /licenses /by -nc -nd /4 .0/).
The goal of this study is to check which, if any, of the published versions of the pion and kaon fragmentation functions (FFs) is compatible with the STAR data on semi-inclusive pion and kaon production in proton-prot...
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The goal of this study is to check which, if any, of the published versions of the pion and kaon fragmentation functions (FFs) is compatible with the STAR data on semi-inclusive pion and kaon production in proton-proton collisions, and on the basis of this analysis to make reliable predictions for the p(T) spectra of the pions and kaons in inclusive pion and kaon production at the future NICA proton-proton collider. The calculations are carried out in next-to-leading order (NLO) of perturbative quantum chromodynamics (pQCD), using the well-tested CTEQ6 parton distributions. We consider the following pion and kaon FFs - DSEHS-14 [D. de Florian, R. Sassot, M. Epele, R. J. Hernandez-Pinto and M. Stratmann, Phys. Rev. D 91, 014035 (2015), 1410.6027], DSEHS-17 [D. de Florian, M. Epele, R. J. Hernandez-Pinto, R. Sassot and M. Stratmann, Phys. Rev. D 95, 094019 (2017), 1702.06353], LSS-15 [E. Leader, A. V. Sidorov and D. B. Stamenov, Phys. Rev. D 93, 074026 (2016), 1506.06381], HKNS-07 [M. Hirai, S. Kumano, T. H. Nagai and K. Sudoh, Phys. Rev. D 75, 094009 (2007), hep-ph/0702250] and AKK-08 [S. Albino, B. A. Kniehl and G. Kramer, Nucl. Phys. B 803, 42 (2008), 0803.2768]. Our analysis shows that within the experimental errors all tested sets of FFs provide a good fit to STAR data at the c.m. energy root S=200GeV, and the best ones are both LSS-15 and DSEHS-14 for pions and DSEHS-17 for kaons. From comparison of the LO and NLO results it is clear that the latter fit data much better, specially in the region of small p(T). The NLO cross-sections are also less scale-Q2 dependent, where pT/2 <= Q <= 2p(T), than the LO ones. In order to make predictions for NICA energies, we compare the NLO pQCD results with the existing experimental BES STAR data on semi-inclusive hadron production in the most peripheral Au+Au collisions where the nuclear effects can be neglected. The comparison for lower energy scales, like at NICA, shows that a purely pQCD approach is inadequate and suggests
We perform a simultaneous global analysis of hadron fragmentation functions (FFs) to various charged hadrons (π±, K±, and p/p¯) at next-to-leading order in QCD. The world data include results from elec...
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We perform a simultaneous global analysis of hadron fragmentation functions (FFs) to various charged hadrons (π±, K±, and p/p¯) at next-to-leading order in QCD. The world data include results from electron-positron single-inclusive annihilation, semi-inclusive deep inelastic scattering, as well as proton-proton collisions including jet fragmentation measurements for the first time, which lead to strong constraints on the gluon fragmentations. By carefully selecting hadron kinematics to ensure the validity of QCD factorization and the convergence of perturbative calculations, we achieve a satisfying best fit with χ2/d.o.f.=0.90. The total momentum of u, d quarks and gluon carried by light charged hadrons have been determined precisely, urging precision determinations of FFs to neutral hadrons for a test of fundamental sum rules in QCD fragmentation.
We present a new quantum field-theoretic definition of fully unintegrated dihadron fragmentation functions (DiFFs) as well as a generalized version for n-hadron fragmentation functions. We demonstrate that this defini...
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We present a new quantum field-theoretic definition of fully unintegrated dihadron fragmentation functions (DiFFs) as well as a generalized version for n-hadron fragmentation functions. We demonstrate that this definition allows certain sum rules to be satisfied, making it consistent with a number density interpretation. Moreover, we show how our corresponding so-called extended DiFFs that enter existing phenomenological studies are number densities and also derive their evolution equations. Within this new framework, DiFFs extracted from experimental measurements will have a clear physical meaning.
In this study, we revisit the extraction of parton-to-KS0 hadron fragmentation functions, named FF24-KS0, focusing on both next-to-leading-order and next-to-next-to-leading-order accuracy in perturbative QCD. Our appr...
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In this study, we revisit the extraction of parton-to-KS0 hadron fragmentation functions, named FF24-KS0, 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 z values. The theory prediction for KS0 production at both NLO and NNLO accuracy exhibits good agreement with experimental data within their respective uncertainties.
Recently the LHCb collaboration has measured both longitudinal and transverse momentum distribution of hadrons produced inside Z-tagged jets in proton-proton collisions at the Large Hadron Collider. These distribution...
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Recently the LHCb collaboration has measured both longitudinal and transverse momentum distribution of hadrons produced inside Z-tagged jets in proton-proton collisions at the Large Hadron Collider. These distributions are commonly referred to as jet fragmentation functions and are characterized by the longitudinal momentum fraction z(h) of the jet carried by the hadron and the transverse momentum j(perpendicular to) with respect to the jet direction. We derive a QCD formalism within Soft-Collinear Effective Theory to describe these distributions and find that the z(h)-dependence provides information on standard collinear fragmentation functions, while j(perpendicular to)-dependence probes transverse momentum dependent (TMD) fragmentation functions. We perform theoretical calculations and compare our results with the LHCb data. We find good agreement for the intermediate z(h) region. For j(perpendicular to)-dependence, we suggest binning in both z(h) and j(perpendicular to), which would lead to a more direct probing of TMD fragmentation functions. (C) 2019 The Author(s). Published by Elsevier B.V.
We review the status of extracting the strong-coupling constant alpha(s) from the scaling violations in fragmentation functions (FFs) by fitting the latter to experimental data of the inclusive production of single li...
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We review the status of extracting the strong-coupling constant alpha(s) from the scaling violations in fragmentation functions (FFs) by fitting the latter to experimental data of the inclusive production of single light hadrons in e(+)e(-) annihilation. We also discuss the analogous analysis based on the average hadron multiplicities in gluon and quark jets, which correspond to the first Mellin moments of the respective FFs. We then assess the prospects of such alpha(s) determinations at future high-luminosity e(+)e(-) colliders such alpha(s) the CERN Future Circular Collider operated in the e(+)e(-) annihilation mode (FCC-ee).
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