Publications by Luca Rottoli

Higgs Transverse Momentum with a Jet Veto: A Double-Differential Resummation.

Physical review letters 124 (2020) 252001-

PF Monni, L Rottoli, P Torrielli

We consider the simultaneous measurement of the Higgs (p_{t}^{H}) and the leading jet (p_{t}^{J}) transverse momentum in hadronic Higgs-boson production, and perform the resummation of the large logarithmic corrections that originate in the limit p_{t}^{H},p_{t}^{J}≪m_{H} up to next-to-next-to-leading-logarithmic order. This work constitutes the first simultaneous (double differential) resummation for two kinematic observables of which one involves a jet algorithm in hadronic collisions, and provides an important milestone in the theoretical understanding of joint resummations. As an application, we provide precise predictions for the Higgs transverse-momentum distribution with a veto p_{t}^{J}≤p_{t}^{J,v} on the accompanying jets, whose accurate description is relevant to the Higgs precision programme at the Large Hadron Collider.

The Zγ transverse-momentum spectrum at NNLO+N<sup>3</sup>LL

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 809 (2020)

M Wiesemann, L Rottoli, P Torrielli

© 2020 The Authors We consider the transverse-momentum (pT) distribution of Zγ pairs produced in hadronic collisions. Logarithmically enhanced contributions at small pT are resummed to all orders in QCD perturbation theory and combined with the fixed-order prediction. We achieve the most advanced prediction for the Zγ pT spectrum by matching next-to-next-to-next-to-leading logarithmic (N3LL) resummation to the integrated cross section at next-to-next-to-leading order (NNLO). By considering ℓ+ℓ−γ production at the fully differential level, including spin correlations, interferences and off-shell effects, arbitrary cuts can be applied to the leptons and the photon. We present results at the LHC in presence of fiducial cuts and find agreement with the 13 TeV ATLAS data at the few-percent level.

Parton distributions with theory uncertainties: general formalism and first phenomenological studies NNPDF Collaboration


RA Khalek, RD Ball, S Carrazza, S Forte, T Giani, Z Kassabov, RL Pearson, ER Nocera, J Rojo, L Rottoli, M Ubiali, C Voisey, M Wilson

Higgsstrahlung at NNLL ' plus NNLO matched to parton showers in GENEVA

PHYSICAL REVIEW D 100 (2019) ARTN 096016

S Alioli, A Broggio, S Kallweit, MA Lim, L Rottoli

A first determination of parton distributions with theoretical uncertainties


RA Khalek, RD Ball, S Carrazza, S Forte, T Giani, Z Kassabov, ER Nocera, RL Pearson, J Rojo, L Rottoli, M Ubiali, C Voisey, M Wilson

The transverse momentum spectrum of weak gauge bosons at N 3 LL + NNLO.

The European physical journal. C, Particles and fields 79 (2019) 868-

W Bizoń, A Gehrmann-De Ridder, T Gehrmann, N Glover, A Huss, PF Monni, E Re, L Rottoli, DM Walker

We present accurate QCD predictions for the transverse momentum ( p⊥ ) spectrum of electroweak gauge bosons at the LHC for 13TeV collisions, based on a consistent combination of a NNLO calculation at large p⊥ and N 3 LL resummation in the small p⊥ limit. The inclusion of higher order corrections leads to substantial changes in the shape of the differential distributions, and the residual perturbative uncertainties are reduced to the few percent level across the whole transverse momentum spectrum. We examine the ratio of p⊥ distributions in charged- and neutral-current Drell-Yan production, and study different prescriptions for the estimate of perturbative uncertainties that rely on different degrees of correlation between these processes. We observe an excellent stability of the ratios with respect to the perturbative order, indicating a strong correlation between the corresponding QCD corrections.

Constraints on the quartic Higgs self-coupling from double-Higgs production at future hadron colliders


W Bizon, U Haisch, L Rottoli

Towards small-x resummed parton distribution functions

Proceedings of Science 2017-April (2017)

L Rottoli, M Bonvini

© 2017 Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). We present preliminary results for fits of parton distribution functions (PDFs) which include the resummation of small-x logarithms at NLLx accuracy, performed in the NNPDF framework. We observe an improvement in the description of DIS data at small values of Bjorken x when resummation effects are included. The improvement is more marked when comparing NNLO+NLLx fits to NNLO ones, and is particularly noticeable for small-x and small-Q 2 HERA inclusive structure functions. The main effect of the resummation is an enhancement of the gluon and singlet PDFs at small-x, which persists at high scales.

Momentum-space resummation for transverse observables and the Higgs p perpendicular to at (NLL)-L-3+NNLO


W Bizon, PF Monni, E Re, L Rottoli, P Torrielli

Parton distributions with small-x resummation: evidence for BFKL dynamics in HERA data


RD Ball, V Bertone, M Bonvini, S Marzani, J Rojo, L Rottoli

Fiducial distributions in Higgs and Drell-Yan production at (NLL)-L-3+NNLO


W Bizon, X Chen, A Gehrmann-De Ridder, T Gehrmann, N Glover, A Huss, PF Monni, E Re, L Rottoli, P Torrielli

Charged hadron fragmentation functions from collider data: NNPDF Collaboration.

The European physical journal. C, Particles and fields 78 (2018) 651-

V Bertone, NP Hartland, ER Nocera, J Rojo, L Rottoli

We present NNFF1.1h, a new determination of unidentified charged-hadron fragmentation functions (FFs) and their uncertainties. Experimental measurements of transverse-momentum distributions for charged-hadron production in proton-(anti)proton collisions at the Tevatron and at the LHC are used to constrain a set of FFs originally determined from electron-positron annihilation data. Our analysis is performed at next-to-leading order in perturbative quantum chromodynamics. We find that the hadron-collider data is consistent with the electron-positron data and that it significantly constrains the gluon FF. We verify the reliability of our results upon our choice of the kinematic cut in the hadron transverse momentum applied to the hadron-collider data and their consistency with NNFF1.0, our previous determination of the FFs of charged pions, kaons, and protons/antiprotons.

Parton distributions from high-precision collider data


RD Ball, V Bertone, S Carrazza, L Del Debbio, S Forte, P Groth-Merrild, A Guffanti, NP Hartland, Z Kassabov, JI Latorre, ER Nocera, J Rojo, L Rottoli, E Slade, M Ubiali, NNPDF Collaboration

Pseudo-scalar Higgs boson production at (NLOA)-L-3+(NLL)-L-3 '


T Ahmed, M Bonvini, MC Kumar, P Mathews, N Rana, V Ravindran, L Rottoli

On the Higgs cross section at (NLO)-L-3+(NLL)-L-3 and its uncertainty


M Bonvini, S Marzani, C Muselli, L Rottoli

The prompt atmospheric neutrino flux in the light of LHCb

JHEP Springer Berlin Heidelberg 02 (2016) 130-

R Gauld, J Rojo, L Rottoli, S Sarkar, J Talbert

The recent observation of very high energy cosmic neutrinos by IceCube heralds the beginning of neutrino astronomy. At these energies, the dominant background to the astrophysical signal is the flux of `prompt' neutrinos, arising from the decay of charmed mesons produced by cosmic ray collisions in the atmosphere. In this work we provide predictions for the prompt atmospheric neutrino flux in the framework of perturbative QCD, using state-of-the-art Monte Carlo event generators. Our calculation includes the constraints set by charm production measurements from the LHCb experiment at 7 TeV, and has been recently validated with the corresponding 13 TeV data. Our results for the prompt flux are a factor of about 2 below the previous benchmark calculation, in general agreement with two other recent estimates, and with an improved estimate of the uncertainty. This alleviates the existing tension between the theoretical prediction and IceCube limits, and suggests that a direct direction of the prompt flux is imminent.

Intrinsic charm in a matched general-mass scheme

Physics Letters B Elsevier 754 (2016) 49-58

RD Ball, V Bertone, M Bonvini, S Forte, P Groth Merrild, J Rojo, L Rottoli

The FONLL general-mass variable-flavour number scheme provides a framework for the matching of a calculation in which a heavy quark is treated as a massless parton to one in which the mass dependence is retained throughout. We describe how the usual formulation of FONLL can be extended in such a way that the heavy quark parton distribution functions are freely parameterized at some initial scale, rather than being generated entirely perturbatively. We specifically consider the case of deep-inelastic scattering, in view of applications to PDF determination, and the possible impact of a fitted charm quark distribution on is assessed.

A determination of the charm content of the proton


RD Ball, V Bertone, M Bonvini, S Carrazza, S Forte, A Guffanti, NP Hartland, J Rojo, L Rottoli

Fitting EMC structure functions with intrinsic charm

XXIV International Workshop on Deep-Inelastic Scattering and Related Subjects, 11-15 April, 2016 DESY Hamburg, Germany Scuola Internazionale Superiore di Studi Avanzati (S I S S A) (2016)

L Rottoli

A detailed study of the impact of the data collected by the European Muon Collaboration (EMC) on the parton distribution function (PDF) of the charm quark is presented. The analysis is performed in the NNPDF framework, and the charm PDF is freely parametrized on equal footing as light quark and gluon distributions. We find that variations in the treatment of EMC data do not modify the charm PDF and do not affect our previous conclusion on the presence of an intrinsic component in the charm PDF.

Towards parton distributions with fitted charm

Nuclear and Particle Physics Proceedings Elsevier 270-272 (2016) 23-26

RD Ball, V Bertone, S Carrazza, L Del Debbio, S Forte, A Guffanti, PN Hartland, Z Kassabov, IJ Latorre, J Rojo, M Ubiali, P Groth-Merrild, L Rottoli

Modern parton distribution function fits require an accurate treatment of heavy quark mass effects. In this contribution, we discuss how the FONLL general-mass variable flavour number scheme can be extended to allow for the possibility of a fitted charm PDF. We present a first estimate of the impact of a fitted charm contribution in the FONLL structure functions, and we discuss the development towards including a fitted charm PDF in the NNPDF framework.