arXiv subjects

Giancarlo Ferrera

Publications and source records attributed to Giancarlo Ferrera.

At least 19 recordsLinked to original sources

arXiv2026

Transverse-momentum resummation effects on angular coefficients in Z and W boson hadroproduction

We present a comprehensive analysis of the angular coefficients of $Z$ and $W$ boson production at hadron colliders in different kinematical ranges, using data from the ATLAS, LHCb, and CMS Collaborations at the LHC, as well as CDF data at the Tevatron. We provide theoretical predictions obtained by consistently combining the resummation of logarithmically enhanced QCD corrections at small transverse momenta $q_T$ up to next-to-next-to-leading logarithmic accuracy (NNLL) with fixed-order calculations at next-to-leading order (NLO), valid at large $q_T$. We quantify the impact of transverse-momentum resummation on the angular coefficients. We find that the inclusion of resummation effects leads to a moderate and systematic improvement in the description of the data in the intermediate $q_T$ region, $q_T \sim 20-50$~GeV, for several angular coefficients, while in the remaining cases it does not degrade the agreement of fixed-order QCD predictions with experimental measurements.

hep-ph↗

arXiv2026

Factorization of the Energy-Energy Correlation in the two-jet limit in the massive case

We consider non-logarithmic heavy-quark mass effects in the factorization and resummation of the Energy-Energy-Correlation (EEC) function, in the two-jet limit. We define a new, "partial" event fraction, restricted to the two-jet region and excluding the forward region, whose calculation at first order requires to consider real emission diagrams only, in $D=4$ space-time dimensions (no need to consider virtual diagrams or take $D \ne 4$). In order to determine explicitly the next-to-leading order coefficient function and the remainder function (both entering the standard resummation formula), we evaluate numerically the EEC spectrum at first-order in $α_S$, finding good agreement with previous calculations. To have a smooth massless limit, a new, improved factorization scheme is proposed, in which the coefficient function also depends on the correlation angle $χ$.

hep-ph↗

arXiv2026

A global analysis of Energy-Energy Correlation data: determination of $α_S$ and non-perturbative QCD parameters

We present a comprehensive global analysis of Energy-Energy Correlation (EEC) data in electron-positron annihilation into hadrons, spanning a wide range of center-of-mass energies ($7.7\,\,\text{GeV}\!\leq\!\sqrt{s}\!\leq\! 91.2\,\,\text{GeV})$. In the back-to-back (two-jet) region, we resum to all orders the logarithmically-enhanced contributions up to next-to-next-to-next-to-leading logarithmic (N$^3$LL) accuracy. The resummed results are consistently matched to fixed-order calculations up to $\mathcal{O}(α_S^3)$. Our resummation formalism also incorporates dominant heavy-quark mass effects and models non-perturbative power corrections by means of an analytic dispersive approach. A simultaneous fit yields an excellent description of experimental data across all energies, enabling a precise determination of the strong coupling, $α_S(m_Z^2) = 0.119 \pm 0.002$, as well as the non-perturbative parameters, including those characterizing the Collins--Soper evolution kernel. Our analysis includes, for the first time in a global fit, datasets from the ALEPH and AMY collaborations.

hep-ph↗

arXiv2026

Drell--Yan lepton pair production at low invariant masses: transverse-momentum resummation and non-perturbative effects in QCD

We consider the transverse-momentum ($q_T$) distribution of Drell-Yan lepton pairs produced with invariant masses ($M$) from low values up to the $Z$-boson peak ($4\leq M \leq 116$~GeV). We present perturbative predictions obtained by consistently combining the resummation of logarithmically enhanced QCD corrections at small $q_T$ ($q_T \ll M$) up to next-to-next-to-next-to-next-to-leading logarithmic accuracy with the available fixed-order calculations at next-to-next-to-leading order (i.e. $\mathcal{O}(α_S^3)$) valid at large $q_T$. For very low $q_T$ ($q_T\sim Λ_{\mathrm{QCD}}$), non-perturbative (NP) QCD effects become dominant and have been included through a NP form factor with a small number of free-parameters. We compare our results with multiple experimental datasets from hadron colliders, finding excellent agreement between theory and data. By fitting the NP parameters, we achieve a precise extraction of the NP form factor and the so-called Collins-Soper kernel.

hep-ph↗

arXiv2026

Transverse-momentum resummation at mixed QCD$\otimes$QED NNLL accuracy for Z boson production at hadron colliders

We consider the transverse momentum ($q_T$) distribution of neutral charged bosons at hadron colliders. We perform the resummation of the logarithmically-enhanced effects due to simultaneous QCD and QED initial-state radiation, up to mixed next-to-next-to-leading logarithmic (NNLL) accuracy. We study the impact of such mixed QCD$\otimes$QED resummed contributions on top of pure QCD corrections, finding percent-level effects.

hep-ph↗

arXiv2025

Saddle-point method for resummed form factors in QCD

We consider the form factor appearing in QCD resummation formalism for event shape distributions in the two-jet (or Sudakov) region. We present an analytic formula for the inverse transform of the form factor, namely from the conjugate moment space to the (physical) momentum space, based on the saddle-point method. The saddle-point itself is determined by means of an analytic recursion method as well as by standard numerical methods. The results we have found are in very good agreement with the exact (numerical) evaluation of the inverse transform, while they significantly differ from classical analytical formulations of resummation in momentum space. The latter are based on a Taylor expansion of the form factor around the free-theory saddle point.

hep-ph↗

arXiv2025

Thrust distribution in electron-positron annihilation at full NNNLL+NNLO (and beyond) in QCD

We consider the thrust ($T$) distribution in electron-positron ($e^+e^-$) annihilation into hadrons and we perform the all-order resummation of the large logarithms of $1-T$ up to next-to-next-to-next-to-next-to-leading logarithmic (N$^4$LL) accuracy in QCD. We consistently combine resummed predictions with the known fixed-order results up to next-to-next-to-leading order (NNLO). All perturbative terms up to order $α_S^3$ are included in our calculation which, thanks to a unitarity constraint, exactly reproduce after integration over the variable $T$ the next-to-next-to-next-to-leading order (N$^3$LO) result for the total cross section of $e^+e^-$ into hadrons. We resum the large logarithms in the Laplace-conjugated space and compare our results with those obtained with the analytic resummation formalism in the physical ($T$) space. We find that the differences in the spectra obtained with the two different formalisms are sizable. Non-perturbative corrections have been included through an analytic hadronization model depending on two free parameters. Finally, we present a comparison of our spectra with experimental data at the $Z$-boson mass ($m_Z$) energy, which enables us to extract the value of the QCD coupling $α_S(m_Z^2)=0.1181 \pm 0.0018$ fully consistent with the world average.

hep-ph↗

arXiv2024

Heavy quark mass effects in the Energy-Energy Correlation in the back-to-back region

We consider heavy quark mass ($m$) effects in the Energy-Energy Correlation function in $e^+e^- \to hadrons$ at high energy $Q$, in the back-to-back (two-jet) region. In the ultra-relativistic limit, $Q \gg m$, the QCD Sudakov form factor $S(b)$ in impact parameter ($b$-)space reads: \begin{eqnarray} \log S(b) &=& - \int_{m^2}^{Q^2} \frac{dk^2}{k^2} \left\{ \log\left(\frac{Q^2}{k^2}\right) A[α_S(k^2)] + B[α_S(k^2)]\right\} [1-J_0(b k)] \nonumber\\ && - \int_0^{m^2} \frac{dk^2}{k^2} \left\{ \log\left(\frac{Q^2}{m^2}\right) A[α_S(k^2)] + D[α_S(k^2)] \right\} [1-J_0(b k)]. \nonumber \end{eqnarray} The double-log function $A(α_S)$ describes the effects of soft gluons, quasi-collinear to the original quark-antiquark pair, while the single-log functions $B(α_S)$ and $D(α_S)$ describe hard collinear radiation and soft radiation not log-collinearly enhanced, respectively. The usual logarithmic expansion of the low transverse momenta contribution to the form factor ($k^2<m^2$) involves two new function series. An explicit evaluation of the heavy quark form factor at Next-to-Next-to-Leading Logarithmic accuracy is presented. The relation of our results with the well-known (classical) dead-cone effect in gauge theories is analyzed. At Next-to-Leading Logarithmic (NLL) accuracy, an improved formula for the dead cone is proposed; the soft term produces an increase of the dead-cone opening angle of a factor $\sqrt{e} \simeq 1.64872$. However, beyond NLL, a physical interpretation of this kind breaks down. The generalization of the above formula to the resummation of shape variables in $e^+e^-$ annihilation, or to the resummation of the transverse momentum distributions in hadron collisions, is also briefly discussed.

hep-ph↗

arXiv2024

Energy-Energy Correlation in the back-to-back region at N$^3$LL+NNLO in QCD

We consider the Energy-Energy Correlation (EEC) function in high-energy electron-positron annihilation to hadrons. In the back-to-back (two-jet) region, we perform the all-order resummation of the logarithmically-enhanced contributions in QCD perturbation theory up to next-to-next-to-next-to-leading logarithmic (N$^3$LL) accuracy. Away from the back-to-back region, we consistently combine resummed predictions with the known fixed-order results up to next-to-next-to-leading order (NNLO) and we are able to obtain an accurate fit of the $\mathcal{O}(α_S^3)$ remainder function from the numerical QCD computation of the full spectrum. All perturbative terms up to order $α_S^3$ are included in our calculation and a non-trivial cross-check in the back-to-back region is obtained by comparing the SCET analytic calculation against the corresponding numerical QCD computation. In particular, the values of the $\mathcal{O}(α_S^3)$ resummation coefficients have been numerically verified. We regularize the Landau singularity of the QCD coupling within the so-called Minimal Prescription and we discuss the reduction of the perturbative scale dependence of distributions at higher orders, as a means to estimate the corresponding residual perturbative uncertainty. Finally, after introducing within a dispersive approach non-perturbative power corrections, we are able to obtain an accurate description of experimental data at LEP and SLC accelerators.

hep-ph↗

arXiv2024

Zero-bin subtraction and the $q_{\mathrm{T}}$ spectrum beyond leading power

In this paper, we present an algorithm to construct the qT distribution at NLO accuracy to arbitrary power precision, including the assembly of suitable zero-bin subtrahends, in a mathematically well-defined way for a generic choice of rapidity-divergence regularisation prescription. In its derivation, we divide the phase space into two sectors, the interior of the integration domain as well as the integration boundary, which we include here for the first time. To demonstrate the applicability and usefulness of our algorithm, we calculate the NNLP corrections for Higgs hadroproduction for the first time. We observe that our approximate NNLP-accurate qT spectra replicate the asymptotic behaviour of the full QCD calculation to a much better degree than the previously available results, both within the $q_{\mathrm{T}}\to 0$ limit and in the large-qT domain for all the involved partonic processes. While playing a minor role at larger transverse momenta, we show that the newly incorporated boundary contribution plays a vital role in the $q_{\mathrm{T}}\to 0$ limit, where any subleading power accuracy would be lost without them. In particular, our NNLP-accurate qT expansion can approximate the exact qT distribution up to $q_{\mathrm{T}}\sim30\,\text{GeV}$ at the percent level for rapidities $|Y_H|\lesssim 3$.

hep-ph↗

arXiv2024

Determination of the strong-coupling constant from the $Z$-boson transverse-momentum distribution

The strong-coupling constant is determined from the low-momentum region of the transverse-momentum distribution of $Z$ bosons produced through the Drell-Yan process, using predictions at third order in perturbative QCD. The analysis employs a measurement performed in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 1.96$ TeV with the CDF experiment. The determined value of the strong coupling at the reference scale corresponding to the $Z$-boson mass is $α_S(m_Z) = 0.1191^{+0.0013}_{-0.0016}$.

hep-ph↗

arXiv2024

Ad interim recommendations for the Higgs boson production cross sections at $\sqrt{s} = 13.6$ TeV

This note documents predictions for the inclusive production cross sections of the Standard Model Higgs boson at the Large Hadron Collider at a centre of mass energy of 13.6 TeV. The predictions here are based on simple extrapolations of previously documented predictions published in the CERN Yellow Report "Deciphering the Nature of the Higgs Sector". The predictions documented in this note should serve as a reference while a more complete and update-to-date derivation of cross section predictions is in progress.

hep-ph↗

arXiv2023

Drell-Yan lepton-pair production: $q_T$ resummation at approximate N$^4$LL+N$^4$LO accuracy

We consider Drell-Yan lepton pairs produced in hadronic collisions. We present high-accuracy QCD predictions for the transverse-momentum ($q_T$) distribution and fiducial cross sections in the small $q_T$ region. We resum to all perturbative orders the logarithmically enhanced contributions up to the next-to-next-to-next-to-next-to-leading logarithmic (N$^4$LL) accuracy and we include the hard-virtual coefficient at the next-to-next-to-next-to-leading order (N$^3$LO) (i.e. $\mathcal{O}(α_S^3)$) with an approximation of the N$^4$LO coefficients. The massive axial-vector and vector contributions up to three loops have also been consistently included. The resummed partonic cross section is convoluted with approximate N$^3$LO parton distribution functions. We show numerical results at LHC energies of resummed $q_T$ distributions for $Z/γ^*, W^\pm$ production and decay, including the $W^\pm$ and $Z/γ^*$ ratio, estimating the corresponding uncertainties from missing higher orders corrections and from incomplete or missing perturbative information coefficients at N$^4$LL and N$^4$LO. Our resummed calculation has been encoded in the public numerical program DYTurbo.

hep-ph↗

arXiv2023

Combining QED and QCD transverse-momentum resummation for W and Z boson production at hadron colliders

In this article, we consider the transverse momentum ($q_T$) distribution of $W$ and $Z$ bosons produced in hadronic collisions. We combine the $q_T$ resummation for QED and QCD radiation including the QED soft emissions from the $W$ boson in the final state. In particular, we perform the resummation of enhanced logarithmic contributions due to soft and collinear emissions at next-to-leading accuracy in QED, leading-order accuracy for mixed QED-QCD and next-to-next-to-leading accuracy in QCD. In the small-$q_T$ region we consistently include in our results the next-to-next-to-leading order (i.e.\ two loops) QCD corrections and the next-to-leading order (i.e.\ one loop) electroweak corrections. The matching with the fixed-order calculation at large $q_T$ has been performed at next-to-leading order in QCD (i.e.\ at $\mathcal{O}(α_S^2)$) and at leading order in QED. We show numerical results for $W$ and $Z$ production at the Tevatron and the LHC. Finally, we consider the effect of combined QCD and QED resummation for the ratio of $W$ and $Z$ $q_T$ distributions, and we study the impact of the QED corrections providing an estimate of the corresponding perturbative uncertainties.

hep-ph↗

arXiv2022

Higgs boson production at the LHC: fast and precise predictions in QCD at higher orders

We present a new numerical program, HTurbo, which provides fast and numerically precise predictions for Higgs boson production cross sections. The present version of the code implements the perturbative QCD expansion up to the next-to-next-to-leading order also combined with the resummation of the large logarithmic corrections at small transverse momenta up to next-to-next-to-leading logarithmic accuracy and it includes the Higgs boson production through gluon fusion and decay in two photons with the full dependence on the final-state kinematics. Arbitrary kinematical cuts can be applied to the final states in order to obtain fiducial cross sections and associated kinematical distributions. We present a benchmark comparison with the predictions obtained with the numerical programs HRes and HNNLO programs for which HTurbo represents an improved reimplementation.

hep-ph↗

arXiv2022

Drell-Yan lepton-pair production: $q_T$ resummation at N$^3$LL accuracy and fiducial cross sections at N$^3$LO

We present high-accuracy QCD predictions for the transverse-momentum ($q_T$) distribution and fiducial cross sections of Drell-Yan lepton pairs produced in hadronic collisions. At small value of $q_T$ we resum to all perturbative orders the logarithmically enhanced contributions up to next-to-next-to-next-to-leading logarithmic (N$^3$LL) accuracy, including all the next-to-next-to-next-to-leading order (N$^3$LO) (i.e. $\mathcal{O}(α_S^3)$) terms. Our resummed calculation has been implemented in the public numerical program DYTurbo, which produces fast and precise predictions with the full dependence on the final-state leptons kinematics. We consistently combine our resummed results with the known $\mathcal{O}(α_S^3)$ fixed-order predictions at large values of $q_T$ thus obtaining full N$^3$LO accuracy also for fiducial cross sections. We show numerical results at LHC energies discussing the reduction of the perturbative uncertainty with respect to lower-order calculations.

hep-ph↗

arXiv2021

Fiducial perturbative power corrections within the q$_{\bf T}$ subtraction formalism

We consider higher-order QCD corrections to the production of high-mass systems in hadron collisions within the transverse-momentum (q$_{\rm T}$) subtraction formalism. We present a method to consistently remove the linear power corrections in q$_{\rm T}$ which appears when fiducial kinematical cuts are applied on the final state system. We consider explicitly the case of fiducial cross sections for Drell-Yan lepton pair production at the Large Hadron Collider up to next-to-next-to-next-to-leading order (N$^3$LO) in QCD. We have implemented our method within the DYTurbo numerical program and we have obtained perturbative predictions which are in agreement at the per mille level with those obtained with local subtraction formalisms up to the next-to-next-to-leading order (NNLO). At the N3LO we are able to provide predictions for fiducial cross sections with numerical accuracy at the per mille level.

hep-ph↗

arXiv2020

DYTurbo: Fast predictions for Drell-Yan processes

Drell-Yan lepton pair production processes are extremely important for Standard Model (SM) precision tests and for beyond the SM searches at hadron colliders. Fast and accurate predictions are essential to enable the best use of the precision measurements of these processes; they are used for parton density fits, for the extraction of fundamental parameters of the SM, and for the estimation of background processes in searches. This paper describes a new numerical program, DYTurbo, for the calculation of the QCD transverse-momentum resummation of Drell-Yan cross sections up to next-to-next-to-leading logarithmic accuracy combined with the fixed-order results at next-to-next-to-leading order ($\mathcal{O}(α_{\mathrm{S}}^2)$), including the full kinematical dependence of the decaying lepton pair with the corresponding spin correlations and the finite-width effects. The DYTurbo program is an improved reimplementation of the DYqT, DYqT and DYNNLO programs, which provides fast and numerically precise predictions through the factorisation of the cross section into production and decay variables, and the usage of quadrature rules based on interpolating functions for the integration over kinematic variables.

hep-ph↗