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Ignacio Borsa

Publications and source records attributed to Ignacio Borsa.

15 recordsLinked to original sources
arXiv2026

A POWHEG generator for di-jet production in polarized proton-proton collisions

We present a new Monte-Carlo generator for the simulation of di-jet production in polarized proton-proton collisions at the next-to-leading order in QCD matched to parton showers using the framework of the POWHEG BOX. With this program we compute a variety of observables of immediate relevance for the spin program of the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. While parton-shower effects are generally small, we find that in some search regions their inclusion improves agreement of predictions with data. Moreover, we provide a critical assessment of selection criteria applied in experiment in the light of perturbative stability.

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arXiv2024

NNLO Global Analysis of Polarized Parton Distribution Functions

We present a next-to-next-to-leading order (NNLO) global QCD analysis of the proton's helicity parton distribution functions (PDFs), the first of its kind. To obtain the distributions, we use data for longitudinal spin asymmetries in inclusive and semi-inclusive lepton-nucleon scattering as well as in weak-boson and hadron or jet production in proton-proton scattering. We analyze the data using QCD perturbation theory at NNLO accuracy, employing approximations provided by the threshold resummation formalism in cases where full NNLO results for partonic hard-scattering functions are not readily available. Our numerical results suggest a remarkable perturbative stability of the extracted helicity PDFs.

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arXiv2024

Parton-shower effects in polarized deep inelastic scattering

We present a Monte-Carlo program for the simulation of polarized deep inelastic scattering at next-to-leading order in QCD matched to parton shower programs building on an existing implementation of the unpolarized case in the POWHEG BOX package. We discuss extensions of the POWHEG BOX framework necessary to account for polarized initial states and validate the code by detailed comparisons to existing fixed-order results. We then use the new tool to make predictions for the upcoming Electron Ion Collider. We find that parton-shower effects do have an impact on experimentally accessible distributions and improve the agreement with the next-to-next-to-leading order results.

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arXiv2023

Charged Hadron Fragmentation Functions at High Energy Colliders

We update our extraction of parton-to-charged hadron fragmentation functions at next-to-leading order accuracy in QCD, focusing on the wealth of data collected at the Large Hadron Collider over the past decade. We obtain an accurate description of single-inclusive processes involving unidentified charged hadrons produced at different rapidities and transverse momenta in proton-proton collisions in a wide range of center-of-mass system energies between 0.9 and 13 TeV, along with measurements performed in proton-antiproton collisions at the Tevatron Collider in the past. NLO estimates of charged hadron production rates agree best with data when the theoretical factorization scales are selected similar to those optimized for identified pions, kaons, and protons in a recent global QCD analysis.

hep-ph↗
arXiv2023

Proton helicity structure function g_1^p from a holographic Pomeron

We present a detailed analysis of the polarized and the unpolarized deep inelastic scattering structure functions of the proton, g_1^p and F_2^p respectively, in the context of a holographic dual description based on type IIB superstring theory. We compare this description with experimental data and Quantum Chromodynamics estimates computed at leading, next-to-leading and next-to-next-to-leading order in perturbation. We confront the predictions of a holographic dual model and those of perturbative QCD for g_1^p at the kinematics that will be probed by the forthcoming Electron-Ion Collider. We find that the extrapolation of g_1^p to very small values the Bjorken variable computed with a Holographic Pomeron model based on actual data at higher momentum fractions is always positive and differs significantly with standard projections based on perturbative QCD.

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arXiv2022

NNLO jet production in neutral and charged current polarized deep inelastic scattering

We perform the calculation of the fully differential single-jet production in longitudinally polarized deep inelastic scattering (DIS) at the next-to-next-to-leading order (NNLO) accuracy, featuring both neutral current and charged current processes. The computation is done with the projection-to-Born method (P2B), using the next-to-leading order (NLO) dijet calculation and the NNLO DIS structure functions as its main ingredients. We also analyze its phenomenological consequences in the kinematics of the future Electron-Ion Collider (EIC).

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arXiv2022

The full set of Polarized Deep Inelastic Scattering Structure Functions at NNLO accuracy

We present the second order contributions to the coefficient functions for the parity violating polarized structure functions $g_L$ and $g_4$, thus completing the $\mathcal{O}(α_S^2)$ knowledge on DIS structure functions. We obtain the missing $\mathcal{O}(α_S^2)$ pieces from the known parity conserving unpolarized coefficient functions. We also present a phenomenological analysis for the phase space region the future Electron-Ion Collider is set to explore.

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arXiv2022

Towards a Global QCD Analysis of Fragmentation Functions at Next-To-Next-To-Leading Order Accuracy

We carry out a global QCD analysis of parton-to-pion fragmentation functions at next-to-next-to-leading order (NNLO) accuracy by performing a fit to the combined set of single-inclusive electron-positron annihilation and, for the first time, semi-inclusive deep-inelastic scattering (SIDIS) multiplicity data. For the latter, we utilize the approximate NNLO QCD corrections that were derived recently within the threshold resummation formalism. We explore the impact of the NNLO corrections on the description of the SIDIS data sets in various kinematic regimes and on the resulting pion fragmentation functions.

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arXiv2021

Pion Fragmentation Functions at High Energy Colliders

We revisit the description of pion production in proton-proton collisions in the light of the very precise data taken at the Large Hadron Collider (LHC) over the past decade. First attempts to include LHC results in next-to-leading order global QCD analyses of parton-to-pion fragmentation functions insinuated some conflict between data sets at different center-of-mass system energies. We show that the data can be well described within their uncertainties by a consistent set of pion fragmentation functions once the theoretical scale dependence is taken into account in the global QCD analysis.

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arXiv2020

Inclusive-jet and Di-jet Production in Polarized Deep Inelastic Scattering

We present the calculation for single-inclusive jet production in (longitudinally) polarized deep-inelastic lepton-nucleon scattering at next-to-next-to leading order (NNLO) accuracy, based on the Projection-to-Born method. As a necessary ingredient to achieve the NNLO results, we also introduce the next-to-leading-order (NLO) calculation for the production of di-jets in polarized DIS. Our di-jet calculation is based on an extension of the dipole subtraction method to account for polarized initial-state partons. We analyze the phenomenological consequences of higher order QCD corrections for the Electron-Ion Collider kinematics.

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arXiv2020

Jet production in Polarized DIS at NNLO

We present the NNLO calculation for single-inclusive jet production in polarized DIS $\vec{e}\vec{p} \rightarrow {\rm jet} +X$. We perform the computation based on the Projection-to-Born method by combining our recent NLO result for di-jet production in polarized DIS along with the NNLO coefficients for the inclusive cross section. In this way, we achieve NNLO accuracy in a fully exclusive way for single-jet observables, the first time for a polarized cross section. We study the perturbative stability and phenomenological consequences of the QCD corrections for Electron Ion Collider kinematics.

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arXiv2020

Revisiting Helicity Parton Distributions at a Future Electron-Ion Collider

We studied the impact of future Electron Ion Collider inclusive and semi-inclusive polarized deep inelastic scattering data will have on the determination of the helicity parton distributions. Supplementing the Monte Carlo sampling variant of the DSSV14 analysis with pseudo-data on polarized inclusive and semi-inclusive electron-proton deep inelastic scattering with updated uncertainty estimates and for two different center-of-mass-system energies, $\sqrt{s}=44.7$ GeV and $\sqrt{s}=141.4$ GeV respectively, and on inclusive electron-helium collisions at $\sqrt{s}=115.2$ GeV, we find a remarkable improvement in the determination of the helicity distributions, specially at low parton momentum fraction $x$. While inclusive electron-proton data at the lowest energy configuration constrain significantly the gluon polarization down to $x \sim 10^{-4}$, the higher energy configuration strengthens the constraint and extends it one decade further. On the other hand, semi-inclusive data achieves the hitherto elusive flavor separation for sea quarks that can not be obtained from any other inclusive electromagnetic measurement. Collisions with helium complement inclusive proton measurements, pushing the constraints on the combined quark plus anti-quark $u, d$ and $s$ polarizations to an unprecedented level.

hep-ph↗
arXiv2019

Semi-inclusive Deep-Inelastic Scattering, Parton Distributions and Fragmentation Functions at a Future Electron-Ion Collider

We present a quantitative assessment of the impact a future Electron-Ion Collider would have in the determination of parton distribution functions in the proton and parton-to-hadron fragmentation functions through semi-inclusive deep-inelastic electron-proton scattering data. Specifically, we estimate the kinematic configurations for which the forthcoming data are expected to have the most significant impact in the precision of these distributions, computing the respective correlation and sensitivity coefficients. Implementing the reweighting technique over sets of simulated data with realistic uncertainties for two different center-of-mass energies, we analyse the resulting upgraded sets of PDFs and FFs, which have significantly reduced uncertainties.

hep-ph↗
arXiv2017

Probing the Sea Quark Content of the Proton with One-Particle-Inclusive Processes

We investigate the feasibility of constraining parton distribution functions in the proton through a comparison with data on semi-inclusive deep-inelastic lepton-nucleon scattering. Specifically, we reweight replicas of these distributions according to how well they reproduce recent, very precise charged kaon multiplicity measurements and analyze how this procedure optimizes the determination of the sea quark densities and improves their uncertainties. The results can help to shed new light on the long standing question on the size of the flavor and charge symmetry breaking among quarks of radiative origin. An iterative method is proposed and adopted to account for the inevitable correlation with what is assumed about the parton-to-hadron fragmentation functions in the reweighting procedure. It is shown how the fragmentation functions can be optimized simultaneously in each step of the iteration. As a first case study, we implement this method to analyze kaon production data.

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