arXiv subjects

Fulvio Piccinini

Publications and source records attributed to Fulvio Piccinini.

At least 19 recordsLinked to original sources

arXiv2026

Next-to-leading order FsQED corrections to radiative pion pair production

We compute the next-to-leading order corrections to the radiative return process $e^+ e^- \to \pi^+ \pi^- \gamma$ within the FsQED approach to embed the pion form factor in the calculation of loop integrals. We compare our results with those of the factorised scalar QED approach, as well as with previous predictions obtained by us in the generalised vector meson dominance model. We show the numerical impact of the structure-dependent corrections on various observables of interest for radiative return experiments at flavour factories. Following recent input from the literature, we include in our calculation also leading corrections beyond FsQED and we provide a first estimate of such contributions. We also investigate additional mechanisms contributing to final-state radiation at center-of-mass energies around the $\phi$-meson resonance, such as radiative $\phi$ decays, presenting numerical results that are relevant for the KLOE experiment. These novel features are implemented in the Monte Carlo event generator BabaYaga@NLO, which can now be used to evaluate the impact of the modelling of pion-photon interaction in radiative return measurements.

hep-ph↗

arXiv2026

Structure-dependent radiative corrections to $e^+ e^- \to \pi^+ \pi^- \gamma$ in the GVMD approach

We compute the radiative corrections to the process of two-pion production in association with a hard photon in $e^+ e^-$ annihilation by taking into account the non-perturbative structure of the pion in the one-loop calculation. For this purpose, we adopt the generalised vector meson dominance model to insert the pion form factor in loop integrals for the treatment of final-state radiation and initial-final state interference at next-to-leading order. We compare our predictions with the results of the naive factorised scalar QED approach for experimentally relevant observables in the measurement of the $e^+ e^- \to \pi^+ \pi^- \gamma$ process. The computation extends previous results obtained for the energy scan process $e^+ e^- \to \pi^+ \pi^-$ and can be used to quantify the uncertainty due to the model describing the pion-photon interaction in radiative return experiments at flavour factories.

hep-ph↗

arXiv2026

Radiative return at NLOPS accuracy

The radiative return, together with the energy scan, is the method used at flavour factories to measure the pion form factor, which is a crucial input for the data-driven dispersive computation of the leading-order hadronic contribution to the muon anomalous magnetic moment. We consider the radiative hadronic and leptonic channels of main experimental interest, namely the processes $e^+e^-\to X^+X^-\gamma$, with $X = \{\pi \, , \mu \}$. For such processes, we compute the exact next-to-leading order (NLO) corrections matched to a Parton Shower (PS) to describe exclusive multiple photon emission. All sources of radiative corrections from initial-state and final-state radiation, as well as their interference, are considered according to QED for $e^+e^-\to\mu^+\mu^-\gamma$ and QED$\oplus$F$\times$sQED (Factorised scalar QED) for $e^+e^-\to\pi^+\pi^-\gamma$. We describe in detail the novel features of our PS approach to compute the fixed-order corrections in association with higher-order contributions to $2\to3$ processes, with a hard photon in the final state. We present validation tests and comparisons with NLO predictions available in the literature to cross-check various ingredients of our formulation. We also show numerical results at NLOPS accuracy according to realistic event selection criteria for precision measurements at flavour factories. Our calculation is implemented in an updated version of the Monte Carlo event generator BabaYaga@NLO, which can be used for fully exclusive simulations and data analysis in radiative return experiments.

hep-ph↗

arXiv2025

New Physics contamination to precision luminosity measurements at future $e^+e^-$ colliders

Several key observables of the high-precision physics program at future lepton colliders will critically depend on the knowledge of the absolute machine luminosity. The determination of the luminosity relies on the precise knowledge of some reference process, which is in principle not affected by unknown physics, so that its cross section can be computed within a well-established theory, like the Standard Model. Quantifying the uncertainties induced by possible New Physics effects on such processes is therefore crucial. We present an exploratory investigation of light and heavy New Physics contributions to the small-angle Bhabha process at future $e^+e^-$ colliders and we discuss possible strategies to remove potential uncertainties originating from such contaminations by relying on observables that are independent of the absolute luminosity.

hep-ph↗

arXiv2024

Radiative corrections and Monte Carlo tools for low-energy hadronic cross sections in $e^+ e^-$ collisions

We present the results of Phase I of an ongoing review of Monte Carlo tools relevant for low-energy hadronic cross sections. This includes a detailed comparison of Monte Carlo codes for electron-positron scattering into a muon pair, pion pair, and electron pair, for scan and radiative-return experiments. After discussing the various approaches that are used and effects that are included, we show differential cross sections obtained with AfkQed, BabaYaga@NLO, KKMC, MCGPJ, McMule, Phokhara, and Sherpa, for scenarios that are inspired by experiments providing input for the dispersive evaluation of the hadronic vacuum polarisation.

hep-ph↗

arXiv2024

On electroweak corrections to neutral current Drell-Yan with the POWHEG BOX

Motivated by the requirement of a refined and flexible treatment of electroweak corrections to the neutral current Drell-Yan process, we report on recent developments on various input parameter/renormalization schemes for the calculation of fully differential cross sections, including both on-shell and MSbar schemes. The latter are particularly interesting for direct determinations of running couplings at the highest LHC energies. The calculations feature next-to-leading order precision with additional higher order contributions from universal corrections such as $\Delta \alpha$ and $\Delta \rho$. All the discussed input parameter/renormalization scheme options are implemented in the package of POWHEG-BOX-V2 dedicated to the neutral current Drell-Yan simulation, i.e. Z_ew-BMNNPV, which is used to obtain the presented numerical results. In particular, a comprehensive analysis on physical observables calculated with different input parameter/renormalization schemes is presented, addressing the Z peak invariant mass region as well as the high energy window. We take the opportunity of reporting also on additional improvements and options introduced in the package Z_ew-BMNNPV after svn revision 3376, such as different options for the treatment of the hadronic contribution to the running of the electromagnetic coupling and for the handling of the unstable Z resonance.

hep-ph↗

arXiv2024

Focus topics for the ECFA study on Higgs / Top / EW factories

In order to stimulate new engagement and trigger some concrete studies in areas where further work would be beneficial towards fully understanding the physics potential of an $e^+e^-$ Higgs / Top / Electroweak factory, we propose to define a set of focus topics. The general reasoning and the proposed topics are described in this document.

hep-ph↗

arXiv2023

Probing the weak mixing angle at high energy

The weak mixing angle is a probe of the vector-axial coupling structure of electroweak interactions. It has been measured precisely at the $Z$-pole by experiments at the LEP and SLD colliders, but its energy dependence above $M_Z$ remains unconstrained. In this contribution we propose to exploit measurements of Neutral-Current Drell Yan at large invariant dilepton masses at the Large Hadron Collider, to determine the scale dependence of the weak mixing angle in the $\overline{MS}$ renormalisation scheme, $\sin^2 θ_w^{\overline{MS}}(μ)$. Such a measurement can be used to test the Standard Model predictions for the $\overline{MS}$ running at TeV scales, and to set model-independent constraints on new states with electroweak quantum numbers. To this end, we present an implementation of $\sin^2 θ_w^{\overline{MS}}(μ)$ in the POWHEG-BOX Monte Carlo event generator, which we use to explore the potential of future analyses with the LHC Run~3 and High-Luminosity datasets. In particular, the impact of the higher order corrections and of the uncertainties due to the knowledge of parton distribution functions are studied.

hep-ph↗

arXiv2023

Probing the weak mixing angle at high energies at the LHC and HL-LHC

Measurements of neutral current Drell-Yan production at large invariant dilepton masses can be used to test the energy scale dependence (running) of the electroweak mixing angle. In this work, we make use of a novel implementation of the full next-to-leading order electroweak radiative corrections to the Drell-Yan process using the $\overline{\mathrm{MS}}$ renormalization scheme for the electroweak mixing angle. The potential of future analyses using proton-proton collisions at $\sqrt{s}=13.6~\mathrm{TeV}$ in the Run 3 and High-Luminosity phases of the LHC is explored. In this way, the Standard Model predictions for the $\overline{\mathrm{MS}}$ running at $\mathrm{TeV}$ scales can be probed.

hep-ph↗

arXiv2022

Probing the Weak Mixing Angle at high energies at the LHC

The electroweak mixing angle is a fundamental parameter of the theory of electroweak interactions. Its value has been measured precisely at the $\mathrm{Z}$-pole at colliders. In this contribution, we propose to exploit measurements of Neutral-Current Drell-Yan production at the Large Hadron Collider at large invariant dilepton masses to determine the energy scale dependence (running) of the electroweak mixing angle in the $\bar{\text{MS}}$ renormalisation scheme, $\sin^2θ_{W,\ell}^{\bar{\text{MS}}}(μ)$. Such a measurement can be used to confirm the Standard Model predictions for the $\bar{\text{MS}}$ running at $\text{TeV}$ scales, and to set model-independent constraints on new states with electroweak quantum numbers. To this end, we make use of a dedicated implementation of $\sin^2θ_{W,\ell}^{\bar{\text{MS}}}(μ)$ in the POWHEG-BOX-V2 Monte Carlo event generator, which we use to explore the potential of future analyses using the data of the LHC Run 3 and High-Luminosity.

hep-ph↗

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.

hep-ph↗

arXiv2021

Multi Higgs production via photon fusion at future multi-TeV muon colliders

Multi-TeV muon colliders promise an unprecedented potential for exploring the particle-physics energy frontier, and, at the same time, can probe with fantastic accuracy the precise structure of the Standard Model, and in particular of the Higgs boson sector. Here we consider the possibility to measure the loop-suppressed single-, double-, triple-Higgs boson production mediated by the collinear-photon scattering in the channels $\mu^+\mu^-\to\mu^+\mu^-\gamma^\ast \gamma^\ast \to \mu^+\mu^- [H,HH,HHH]$. We study total rates and kinematical distributions in the Standard Model, and compare them with the corresponding vector-boson-fusion processes $V^\ast V^\ast\to H,HH,HHH$ at muon collisions center-of-mass energies in the range between 1.5 and 100 TeV. Possible strategies for enhancing the $\gamma\gamma\to H,HH,HHH$ signal over the dominant vector-boson-fusion production are proposed. The sensitivity of total rates to possible anomalies in the Higgs-boson self-couplings is also discussed.

hep-ph↗

arXiv2021

Directional detection of light dark matter from three-phonon events in superfluid $^4$He

We present the analysis of a new signature for light dark matter detection with superfluid $^4$He: the emission of three phonons. We show that, in a region of mass below the MeV, the kinematics of this process can offer a way to reconstruct the dark matter interaction vertex, while providing background rejection via coincidence requirements and directionality. We develop all the necessary technology to deal with such an observable, and compute the associated differential distributions.

hep-ph↗

arXiv2020

Measuring the quartic Higgs self-coupling at a multi-TeV muon collider

Measuring the shape of the Higgs boson potential is of paramount importance and will be a challenging task at current as well as future colliders. While the expectations for the measurement of the trilinear Higgs self-coupling are rather promising, an accurate measurement of the quartic self-coupling interaction is presently considered extremely challenging even at a future 100 TeV proton-proton collider. In this work we explore the sensitivity that a muon collider with a center of mass energy in the multi-TeV range, and luminosities of the order of 10^35cm^-2s^-1, as presently under discussion, might provide thanks to a rather large three Higgs-boson production and to a limited background. By performing a first and simple analysis, we find a clear indication that a muon collider could provide a determination of the quartic Higgs self-coupling that is significantly better than what is currently considered attainable at other future colliders.

hep-ph↗

arXiv2019

Estimating $γγ$ absorption for UHE photons with lepton and hadron production

Surprisingly, the contribution to the cosmic opacity to UHE ($E>10^{18} \, \rm eV$) $γ$-rays has been systematically computed so far for the $γγ\to e^+e^-$ and $γγ\to e^+ e^- e^+ e^-$ processes alone. We go a step further by systematically evaluating the additional opacity brought about by other leptons and hadrons. We find that the dominant channels are those leading to the production of $μ^{\pm}$ and hadrons (mainly $π^{\pm}$, $π^0$, $K^{\pm}$, $K^0$, $η$). For nearly the GZK radius, the photon survival probability becomes smaller by about a factor of two with respect to current estimates.

astro-ph.HE↗

arXiv2019

On the direct determination of $\sin^2 θ^\ell_{eff}$ at hadron colliders

We discuss the renormalization of the electroweak Standard Model at 1-loop using the leptonic effective weak mixing angle as one of the input parameters. We evaluate the impact of this choice in the prediction of the forward-backward asymmetry for the neutral current Drell-Yan process. The proposed input scheme is suitable for a direct determination of the effective leptonic weak mixing angle from the experimental data.

hep-ph↗

arXiv2019

Electroweak corrections to $e^+e^-\toγγ$ as a luminosity process at FCC-ee

We consider large-angle two photon production in $e^+ e^-$ annihilation as a possible process to monitor the luminosity of a future $e^+ e^-$ circular collider (FCC-ee). We review and assess the status of the theoretical accuracy by performing a detailed phenomenological study of next-to-leading order electroweak corrections and leading logarithmic QED contributions due to multiple photon radiation. We also estimate the impact of photonic and fermion-loop corrections at next-to-next-to-leading order and the uncertainty induced by the hadronic contribution to the vacuum polarization. Possible perspectives to address the target theoretical accuracy are briefly discussed.

hep-ph↗