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Fedor Ignatov

Publications and source records attributed to Fedor Ignatov.

11 recordsLinked to original sources
arXiv2026

PrecisionSM: an annotated database for low-energy $e^+e^-$ hadronic cross sections

PrecisionSM is an annotated database that compiles the available data on low-energy cross sections of electron-positron collisions into hadronic channels. This database organizes and collects data samples from $e^+e^-$ experiments, which are used as input for the data-driven theoretical evaluation of the muon anomalous magnetic moment, $a_μ$, serving as a precise test of the Standard Model when compared to the experimental measurements of $a_μ$. The database is accessible through a custom website (https://precision-sm.github.io) which contains details about the data samples, such as the treatment of radiative corrections, as well as links to papers on INSPIRE-HEP and to tables on HEPData. The PrecisionSM database was developed within a Joint Research Initiative in the group application of the European hadron physics community, STRONG2020, and is now incorporated into the RadioMonteCarLow2 Working Group (RMCL2 WG) activities, which have the more general goal of improving the theoretical description of scattering processes at $e^+e^-$ colliders. The results of Phase I of the new RMCL2 WG have been published in Aliberti et al, arXiv:hep-ph/2410.22882. In this proceeding, we will report on the status of the PrecisionSM database, which currently contains a list of the dominant $2π$ channel as well as $3π$ and $π^0γ$, and on the ongoing work for the other channels and for responsive plots.

hep-ph↗
arXiv2026

Letter Of Intent for a future $μ^+ \to \mathrm{e}^+ γ$ experiment at the High Intensity Muon Beam facility at PSI

Searches for charged lepton flavor violation in the muon sector stand out among the most sensitive and clean probes for physics beyond the Standard Model. Currently, $μ^+ \to \mathrm{e}^+ γ$ experiments provide the best constraints in this field for a wide range of models while, in the coming years, new experiments investigating the processes of $μ^+ \to \mathrm{e}^+ \mathrm{e}^+ \mathrm{e}^-$ and $μ\to \mathrm{e}$ conversion in the nuclear field are anticipated to reach comparable or higher sensitivities. The High-Intensity Muon Beam (HIMB) facility at PSI, which is expected to deliver muon beam intensities up to two orders of magnitude higher than the existing beam lines, offers a unique opportunity to significantly enhance the sensitivity of $μ^+ \to \mathrm{e}^+ γ$ searches. The discovery potential could be substantially boosted and a sensitivity comparable to that of all the other projects could be reestablished, which is essential for discriminating among competing new-physics scenarios should an observation occur in any of the channels. In this document, we express our interest in developing a $μ^+ \to \mathrm{e}^+ γ$ experimental program at HIMB, with the goal of improving, within the next decade, the sensitivity of the $μ^+ \to \mathrm{e}^+ γ$ search by more than one order of magnitude relative to the expected final result of the current leading experiment, MEG II. This effort would ensure that PSI retains its leadership in this field.

hep-ex↗
arXiv2025

Transformer-Based Approach to Enhance Positron Tracking Performance in MEG II

We developed a Transformer-based pattern recognition method for positron track reconstruction in the MEG II experiment. The model acts as a classifier to remove pileup hits in the MEG II drift chamber, which operates under a high pileup occupancy of 35 - 50 %. The trained model significantly improved hit purity, leading to enhancements in tracking efficiency and resolution by 15 % and 5 %, respectively, at a muon stopping rate of $5\times 10^7 \mu$/sec. This improvement translates into an approximately 10 % increase in the sensitivity of the $\mu\to e\gamma$ branching ratio measurement.

hep-ex↗
arXiv2025

CANTON-$\mu$ Proposal: A Next-Generation Muon $g-2$ Measurement at Sub-0.1 ppm Precision

We propose a next-generation precision measurement of the muon anomalous magnetic moment (muon g-2) at the High Intensity Heavy-Ion Accelerator Facility (HIAF) in Huizhou, China. We refer to this proposed experimental programme as CANTON-$\mu$ (Coherent Anomalous magNetic momenT ObservatioN with muon). HIAF's intense, pulsed GeV-scale muon beams, particularly for negative muons, provide a promising basis for this programme. Building on two previously proposed storage-ring concepts, this work develops HIAF-specific experimental schemes that relax the conventional magic-momentum constraint and allow greater flexibility in the choice of beam momentum. We assess the expected muon intensity at HIAF and the corresponding statistical sensitivity. For each scheme, we identify its distinctive systematic effects, examine feasible control strategies, and propose quantitative systematic-uncertainty targets. Together, the statistical projections and systematic-uncertainty targets indicate prospective total precisions of 0.1 ppm in Phase-I, comparable to the current Fermilab precision, with the potential to reach the 0.05 ppm level in in Phase-II following the planned HIAF upgrade. At the ultimate projected precision, the measurement would provide a stringent test of the Standard Model and probe new physics at multi-TeV scales. A focus on negative-muon measurements would enable direct comparison with existing high-precision positive-muon results and strengthen tests of CPT symmetry in the muon sector within the Standard-Model Extension, with a projected sensitivity at the $10^{-24}$ GeV level, an order of magnitude beyond current limits.

hep-ex↗
arXiv2025

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↗
arXiv2023

An alternative evaluation of the leading-order hadronic contribution to the muon g-2 with MUonE

We propose an alternative method to extract the leading-order hadronic contribution to the muon g-2, $a_μ^\text{HLO}$, with the MUonE experiment. In contrast to the traditional method based on the integral of the hadronic contribution to the running of the effective fine-structure constant $Δα_{had}$ in the space-like region, our approach relies on the computation of the derivatives of $Δα_{had}(t)$ at zero squared momentum transfer $t$. We show that this approach allows to extract $\sim 99\%$ of the total value of $a_μ^\text{HLO}$ from the MUonE data, while the remaining $\sim 1\%$ can be computed combining perturbative QCD and data on $e^+e^-$ annihilation to hadrons. This leads to a competitive evaluation of $a_μ^\text{HLO}$ which is robust against the parameterization used to model $Δα_{had}(t)$ in the MUonE kinematic region, thanks to the analyticity properties of $Δα_{had}(t)$, which can be expanded as a polynomial at $t\sim 0$.

hep-ph↗
arXiv2022

Charge asymmetry in $e^+e^-\to π^+π^-$ process

We consider the charge asymmetry in the differential cross section of the process $e^+e^- \rightarrow π^+π^-$. Experimental data show large deviations from the results of the available theoretical calculations. Motivated by this fact, we revisit the contribution of the two photon exchange diagrams and find the origin of discrepancy in an oversimplified account of the pion internal structure in the theoretical calculations. We present a natural and simple approach that accounts for the pion structure in a more consistent way and find remarkable agreement with the experimental data.

hep-ph↗
arXiv2021

The Search for $μ^+\to e^+ γ$ with 10$^{-14}$ Sensitivity: the Upgrade of the MEG Experiment

The MEG experiment took data at the Paul Scherrer Institute in the years 2009--2013 to test the violation of the lepton flavour conservation law, which originates from an accidental symmetry that the Standard Model of elementary particle physics has, and published the most stringent limit on the charged lepton flavour violating decay $μ^+ \rightarrow {\rm e}^+ γ$: BR($μ^+ \rightarrow {\rm e}^+ γ$) $<4.2 \times 10^{-13}$ at 90% confidence level. The MEG detector has been upgraded in order to reach a sensitivity of $6\times10^{-14}$. The basic principle of MEG II is to achieve the highest possible sensitivity using the full muon beam intensity at the Paul Scherrer Institute ($7\times10^{7}$ muons/s) with an upgraded detector. The main improvements are better rate capability of all sub-detectors and improved resolutions while keeping the same detector concept. In this paper, we present the current status of the preparation, integration and commissioning of the MEG II detector in the recent engineering runs.

hep-ex↗
arXiv2013

Another Detector for the International Linear Collider

We describe another detectora designed for the International Linear Collider based on several tested instrumentation innovations in order to achieve the necessary experi- mental goal of a detecter that is 2-to-10 times better than the already excellent SLC and LEP detectors, in particular, (1) dual-readout calorimeter system based on the RD52/DREAM measurements at CERN, (2) a cluster-counting drift chamber based on the successful kloe chamber at Frascati, and (3) a second solenoid to return the magnetic flux without iron. A high-performance pixel vertex chamber is presently undefined. We discuss particle identification, momentum and energy resolutions, and the machine-detector interface that together offer the possibility of a very high-performance detector for $e^+e^-$physics up to $\sqrt{s} = 1$ TeV.

physics.ins-det↗
arXiv2013

The Case for a Muon Collider Higgs Factory

We propose the construction of a compact Muon Collider Higgs Factory. Such a machine can produce up to \sim 14,000 at 8\times 10^{31} cm^-2 sec^-1 clean Higgs events per year, enabling the most precise possible measurement of the mass, width and Higgs-Yukawa coupling constants.

hep-ph↗