arXiv subjects

Francesco Garosi

Publications and source records attributed to Francesco Garosi.

9 recordsLinked to original sources

arXiv2026

NNLO+PS Higgs-pair production in MiNNLOPS

We consider Higgs-boson pair production in gluon fusion at hadron colliders and match next-to-next-to-leading-order (NNLO) QCD corrections to parton showers within the MiNNLO$_{PS}$ framework. Since the full top-quark mass dependence at this order is not available, finite top-quark mass effects are incorporated through approximations based on the exact NLO QCD result, using the available two-loop amplitude in the full theory. Specifically, the Born, single-virtual, single-real and double-real contributions are included exactly, while the real--virtual and double-virtual corrections are approximated. We consider different approximations for the latter to assess the associated uncertainties. We validate our predictions against fixed-order NNLO QCD results and compare with existing NNLO calculations matched to parton shower from GENEVA, where in some cases we find noticeable differences. Finally, we present phenomenological results for different Higgs-decay channels and variations of the trilinear Higgs coupling. Our MiNNLO$_{PS}$ generator for Higgs-boson pair production is available within the POWHEG-BOX-RES framework.

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arXiv2024

Testing the Neutrino Content of the Muon at Muon Colliders

Collinear emission of $W$ bosons off a high-energy muon induces a large muon-neutrino component among the Parton Distribution Functions (PDFs) of a muon. In this paper we study the phenomenology related to the $ν_μ$ PDF at future high-energy muon colliders. We examine total rates and differential distributions of the $e \barν_e$ and $W γ$ production processes, which receive a large, and often dominant, contribution from this PDF, allowing for a detailed experimental study. As a demonstration of the impact the $ν_μ$ PDF could have for searches of new physics, we study the charged-current pair production of a couple of heavy states, components of a ${\rm SU}(2)_L$ doublet. In both $e\barν_e$ production and charged-current pair production of heavy states, we compare results obtained using PDFs with those of a fixed-order simulation.

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arXiv2024

Indirect constraints on top quark operators from a global SMEFT analysis

We perform a model-independent analysis of top-philic New Physics scenarios, under the assumption that only effective operators involving top quarks are generated at tree level. Within the SMEFT framework, we derive indirect constraints on Wilson Coefficients by combining a large set of low-energy observables: B-meson and kaon decays, meson mixing observables, precision electroweak and Higgs measurements, anomalous magnetic moments, lepton flavour violating processes, lepton flavour universality tests, and measurements of the Cabibbo angle. We consider the renormalization group evolution of the operators and use the one-loop matching of the SMEFT onto the LEFT. The global analysis is then used to perform one-parameter, two-parameter, and global fits, as well as applications to explicit ultraviolet models. We find that the inclusion of measurements from different physics sectors reveals a strong interplay and complementarity among the observables. The resulting constraints are also compared to direct bounds provided by top quark productions at the LHC.

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arXiv2023

LePDF: Standard Model PDFs for High-Energy Lepton Colliders

The emission of collinear radiation off an elementary lepton can be factorised from the hard scattering process by introducing Parton Distribution Functions of a Lepton (LePDF), which, contrary to protons, can be derived from first principles. In case of multi-TeV lepton colliders, such as the muon colliders currently being proposed, the complete structure of Standard Model interactions must be taken into account. In this work we solve numerically the corresponding DGLAP equations at the double-log order and provide public files with LePDFs for both muons and electrons, including polarisation effects. We discuss several interesting aspects of the resulting PDFs and compare them with the Effective Vector Approximation, showing that the latter fails to describe well the vector bosons PDFs at small momentum fractions, unless it is extended to higher orders.

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arXiv2022

Localisation of Dirac eigenmodes and confinement in gauge theories: the Roberge-Weiss transition

Ample numerical evidence from lattice calculations shows a strong connection between the confining properties of gauge theories at finite temperature and the localisation properties of the low-lying Dirac eigenmodes. In this contribution we discuss recent progress on this topic, focussing on results for QCD at imaginary chemical potential $μ_I/T = π$ at temperatures above the Roberge-Weiss transition temperature. These confirm the general picture of low modes turning from delocalised to localised at the deconfinement transition, in a previously unexplored setup with a genuine, physical transition in the presence of dynamical fermions. This further supports the use of Dirac eigenmodes as a tool to investigate the mechanisms behind confinement and the deconfinement transition.

hep-lat↗

arXiv2022

New Physics in $b \to s μμ$: FCC-hh or a Muon Collider?

Rare flavour-changing neutral-current transitions $b \to s μ^+ μ^-$ probe higher energy scales than what is directly accessible at the LHC. Therefore, the presence of new physics in such transitions, as suggested by the present-day LHCb anomalies, would have a major impact on the motivation and planning of future high-energy colliders. The two most prominent options currently debated are a proton-proton collider at 100 TeV (FCC-hh) and a multi-TeV muon collider (MuC). In this work, we compare the discovery prospects at these colliders on benchmark new physics models indirectly detectable in $b \to s μ^+ μ^-$ decays but beyond the reach of the high-$p_T$ searches at the HL-LHC. We consider a comprehensive set of scenarios: semileptonic contact interactions, $Z^\prime$ from a gauged $U(1)_{B_3 - L_μ}$ and $U(1)_{L_μ- L_τ}$, the scalar leptoquark $S_3$, and the vector leptoquark $U_1$. We find that a 3 TeV MuC has a sensitivity reach comparable to the one of the FCC-hh. However, for a heavy enough mediator, the new physics effects at a 3 TeV MuC are only observed indirectly via deviations in the highest energy bin, while the FCC-hh has a greater potential for the discovery of a resonance. Finally, to completely cover the parameter space suggested by the $bsμμ$ anomalies, among the proposed future colliders, only a MuC of 10 TeV (or higher) can meet the challenge.

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arXiv2022

Muon Collider Physics Summary

The perspective of designing muon colliders with high energy and luminosity, which is being investigated by the International Muon Collider Collaboration, has triggered a growing interest in their physics reach. We present a concise summary of the muon colliders potential to explore new physics, leveraging on the unique possibility of combining high available energy with very precise measurements.

hep-ph↗

arXiv2022

The physics case of a 3 TeV muon collider stage

In the path towards a muon collider with center of mass energy of 10 TeV or more, a stage at 3 TeV emerges as an appealing option. Reviewing the physics potential of such muon collider is the main purpose of this document. In order to outline the progression of the physics performances across the stages, a few sensitivity projections for higher energy are also presented. There are many opportunities for probing new physics at a 3 TeV muon collider. Some of them are in common with the extensively documented physics case of the CLIC 3 TeV energy stage, and include measuring the Higgs trilinear coupling and testing the possible composite nature of the Higgs boson and of the top quark at the 20 TeV scale. Other opportunities are unique of a 3 TeV muon collider, and stem from the fact that muons are collided rather than electrons. This is exemplified by studying the potential to explore the microscopic origin of the current $g$-2 and $B$-physics anomalies, which are both related with muons.

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arXiv2021

Localization properties of Dirac modes at the Roberge-Weiss phase transition

We study the localization properties of the low-lying Dirac eigenmodes in QCD at imaginary chemical potential $\hatμ_I=π$ at temperatures above the Roberge-Weiss transition temperature $T_{\rm RW}$. We find that modes are localized up to a temperature-dependent "mobility edge" and delocalized above it, and that the mobility edge extrapolates to zero at a temperature compatible with $T_{\rm RW}$. This supports the existence of a strong connection between localization of the low Dirac modes and deconfinement, studied here for the first time in a model with a genuine deconfinement transition in the continuum limit in the presence of dynamical fermions.

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