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G. Felici

Publications and source records attributed to G. Felici.

At least 37 records · Page 2Linked to original sources
arXiv2026

Amplitude analysis and branching fraction measurement of the decay $D^0 \to K^0_Sπ^0π^0$

An amplitude analysis of the decay $D^0 \to K_S^0 π^0 π^0$ is performed to determine the relative magnitudes and phases of different intermediate processes. The analysis uses $e^+e^-$ collision data collected at the center-of-mass energy of 3.773 GeV by the BESIII detector corresponding to an integrated luminosity of 20.3 $\rm fb^{-1}$. The absolute branching fraction of $D^0 \to K^0_S π^0 π^0$ is measured to be $(1.026 \pm 0.008_{\rm{stat.}} \pm 0.009_{\rm{syst.}}) \%$. The dominant intermediate process is $D^0 \to \bar{K}^{*}(892)^{0}(\to K^0_S π^0) π^0$, with a branching fraction of $(4.10\pm0.10_{\rm{stat.}}\pm0.07_{\rm{syst.}})\times 10^{-3}$.

hep-ex↗
arXiv2026

Ultra-trace analysis of 40K in organic liquid scintillators

Rare-event searches require exceptionally low background levels, motivating the development of increasingly sophisticated screening methods to push sensitivity limits. Liquid scintillators are particularly attractive detector media due to their intrinsic radiopurity and the ability to scale to large target masses. In this work, we present a screening strategy capable of measuring ultra-trace concentrations of $^{40}\text{K}$ with sensitivities below $10^{-15}$g/g. The method combines neutron activation analysis with a dedicated radiochemical treatment, followed by low-background HPGe gamma spectroscopy. Using this approach, we achieved a minimum detectable concentration of $2.9\cdot10^{-16}$g/g for $^{40}\text{K}$, placing this technique among the most sensitive currently available.

physics.ins-det↗
arXiv2026

Search for an isoscalar partner of the $Z_c(3900)$ in $e^+e^-\toπ^+π^-ηJ/ψ$

Using a data sample corresponding to an integrated luminosity of 20.3 fb$^{-1}$ collected at center-of-mass energies from 4.18 to 4.95 GeV with the BESIII detector, we observe the process $e^+e^-\toπ^+π^-ηJ/ψ$ with a statistical significance of $6.0 σ$, including systematic uncertainties. The isoscalar partner of the $Z_c(3900)$, denoted $X(3900)$, is searched for in the $ηJ/ψ$ final state, and no significant signal is observed. The upper limits on the product of the Born cross section $σ^{\rm Born}[e^{+}e^{-}\toπ^{+}π^{-} X(3900)$] and the branching fraction $\mathcal{B}[X(3900)\toηJ/ψ]$ are given with various assumptions for the mass and width of the $X(3900)$.

hep-ex↗
arXiv2026

Observation of $Ξ(1530)^0$ Polarization and Determination of Its Electric and Magnetic Moments in $ψ(3686)\toΞ(1530)^0\barΞ(1530)^0$

Using the data sample of $2.7\times10^9$ $ψ(3686)$ events collected with the BESIII detector at the BEPCII collider, we present an observation of the $Ξ(1530)^0$ polarization in the decay $ψ(3686)\toΞ(1530)^0\barΞ(1530)^0$ with a significance larger than $20σ$ compared with all other tested hypotheses. The helicity amplitudes for the process $ψ(3686)\toΞ(1530)^0\barΞ(1530)^0$ and the moduli of form factors including electric charge, magnetic dipole, electric quadrupole, and magnetic octupole are measured for the first time by performing an angular distribution analysis. Additionally, the polarization correlations between $Ξ(1530)^0$ and $\barΞ(1530)^0$ are measured.

hep-ex↗
arXiv2026

Search for the charged lepton flavor violating decay $η\to e^{\pm}μ^{\mp}$

Based on $(10.087 \pm 0.044) \times 10^{9}~J/ψ$ events collected at the center-of-mass energy $\sqrt{s} = 3.097$~GeV with the BESIII detector, we search for the charged lepton flavor violating decay $η\to e^{\pm}μ^{\mp}$ through the process $J/ψ\to γη'$ with $η' \to π^{+} π^{-} η$. No signal is observed, and an upper limit on the branching fraction is determined to be $\mathcal{B}(η\to e^{\pm}μ^{\mp}) < 6.8 \times 10^{-7}$ at the 90\% confidence level. This result improves the previous best limit by one order of magnitude.

hep-ex↗
arXiv2026

Observation of an Altered $a_{0}(980)$ Line shape in $D^{+} \rightarrow π^{+}ηη$

Using $20.3~{\rm fb}^{-1}$ of $e^+e^-$ collision data collected with the BESIII detector at $\sqrt{s}=3.773~{\rm GeV}$, we perform the first amplitude analysis of the decay $D^+\toπ^+ηη$. The intermediate process $D^+\to a_0(980)^+η$, $a_0(980)^+\toπ^+η$, is observed as the only significant component in the amplitude analysis, and its branching fraction is measured to be $(3.67\pm0.12_{\rm stat}\pm0.06_{\rm syst})\times10^{-3}$. The $π^+η$ mass spectrum associated with $a_0(980)^+η$ production exhibits a line shape that differs substantially from those observed in $D_{(s)}\to a_0(980)π$ and $D^0\to a_0(980)^-e^+ν_e$ decays. We examine several conventional descriptions of the $a_0(980)$ amplitude, including Flatté, dispersively modified Flatté, $T$-matrix, and $K$-matrix parameterizations. With reference $a_0(980)$ parameters, neither these models nor their extensions including additional small resonant or non-resonant amplitudes reproduce the observed line shape satisfactorily. When the $a_0(980)$ parameters are allowed to float, satisfactory fits can be obtained, but the pole mass is driven well above the $K\bar K$ threshold, inconsistent with the near-threshold character of the $a_0(980)$. The results reveal a tension between fit quality and the physical pole position in conventional direct-production amplitude models.

hep-ex↗
arXiv2026

Study of the Magnetic Dipole Transition of $J/ψ\toγη_c$ via $η_c\to p\bar{p}$

Using $(10.087\pm0.044)\times10^9$ $J/ψ$ events collected with the BESIII detector at the $e^+e^-$ BEPCII collider, we present the first amplitude analysis of $J/ψ\toγp\bar{p}$ with the $p\bar p$ invariant mass in the $η_c$ mass region $[2.70,3.05]$~GeV/$c^2$. The product branching fraction $\mathcal{B}(J/ψ\toγη_c)\times\mathcal{B}(η_c\to p\bar{p})$ is precisely determined to be $(2.11\pm0.02_{\rm stat}\pm0.07_{\rm syst})\times10^{-5}$. Combining with the product branching fractions $\mathcal{B}(η_c\to p\bar{p})\times\mathcal{B}(η_c\to γγ)$ and $\mathcal{B}(J/ψ\toγη_c)\times\mathcal{B}(η_c\to γγ)$, the branching fractions of $\mathcal{B}(J/ψ\toγη_c)$ and $\mathcal{B}(η_c\toγγ)$ are calculated to be $(2.29\pm0.01_{\rm stat}\pm0.04_{\rm syst}\pm0.18_{\rm opbf})\%$ and $(2.28\pm0.01_{\rm stat}\pm0.04_{\rm syst}\pm0.18_{\rm opbf})\times10^{-4}$, respectively, which are consistent with the latest lattice quantum chromodynamics calculations. Here, opbf is the uncertainty from the other product branching fractions used in the calculation.

hep-ex↗
arXiv2026

Precise Measurement of Chromoelectric Dipole Moment of the Charm Quark

The combined symmetry of charge conjugation and parity ($C\!P$) is tested in the hadronic transition $ψ(3686)\toπ^+π^{-}J/ψ$, using a dataset of $(2712.4\pm14.3)\times10^6$ $ψ(3686)$ events collected by the BESIII detector at the BEPCII collider. The resulting asymmetry observable is $A_{cp} = (0.6\pm1.8\pm0.1)\times10^{-4}$, which is determined by combining the two channels $J/ψ\to e^+e^-$ and $J/ψ\toμ^+μ^-$. Additionally, by considering the relationship between the chromoelectric dipole moment (CEDM) and the $A_{cp}$ observable derived from the quantum chromodynamics multipole expansion theory based on the Chen-Kuang model and the Cornell potential model, we obtain the results of charm quark's CEDM with $d^{\prime}_{c} = (2.6\pm7.8\pm0.4\pm0.6)\times10^{-16}$ $e$cm, and $d^{\prime}_{c} = (3.5\pm10.5\pm0.6\pm0.5)\times10^{-16}$ $e$cm, respectively. The uncertainties are statistical, systematic, and theoretical, respectively. These results correspond to an upper limit of $|d^{\prime}_{c}|<2.1\times10^{-15}$ $e$ cm at 90\% confidence level, representing an order of magnitude improvement in sensitivity compared to the previous direct bound using the same decay process.

hep-ex↗
arXiv2026

Measurement of the branching fraction of $D_{s}^{*+}\to e^{+}e^{-}D_{s}^{+}$

The branching fraction of the electromagnetic Dalitz decay $D^{*+}_{s}\to e^{+}e^{-}D^{+}_{s}$ is measured with an $e^{+}e^{-}$ collision data sample collected by the BESIII experiment at center-of-mass energies between 4.128 and 4.226 $\mathrm{GeV}$, corresponding to a total integrated luminosity of 7.33 $\mathrm{fb}^{-1}$. The measurement yields the branching fraction ${\mathcal{B}(D^{*+}_{s}\to e^{+}e^{-}D^{+}_{s})=(7.28\pm0.61_{\mathrm{stat}}\pm0.31_{\mathrm{syst}})\times10^{-3}}$. The result is consistent with the previous one, with a 2.5-fold improvement in precision. This provides an important input for constraining the parameters of theoretical models and for determining the absolute branching fractions of $D^{*+}_{s}\to π^{0}D^{+}_{s}$ and $D^{*+}_{s}\to γD^{+}_{s}$, measured with a relative method.

hep-ex↗
arXiv2026

Search for the isospin-violating decays $\boldsymbol{χ_{cJ}\toΛ\barΣ^{0}+c.c.}$ and $\boldsymbol{η_{c}\toΛ\barΣ^{0}+c.c.}$

Using a sample of $(2712.4\pm14.3)\times10^{6}$~$ψ(3686)$ events collected with the BESIII detector, we perform a search for the isospin-violating decays $χ_{cJ}\toΛ\barΣ^{0}+c.c.~(J=0,1,2)$ and $η_{c}\toΛ\barΣ^{0}+c.c.$ No significant signal for $χ_{cJ}$ or $η_{c}$ is observed in the $Λ\barΣ^{0}$ invariant mass distribution. The upper limits on the branching fractions at the 90\% confidence level are set to be $\mathcal{B}$($χ_{c0}\toΛ\barΣ^{0}+c.c.$)$<1.5\times 10^{-6}$, $\mathcal{B}$($χ_{c1}\toΛ\barΣ^{0}+c.c.$)$<1.6\times 10^{-6}$, $\mathcal{B}$($χ_{c2}\toΛ\barΣ^{0}+c.c.$)$<1.7\times 10^{-6}$ and $\mathcal{B}$($η_{c}\toΛ\barΣ^{0}+c.c.$)$<6.2\times 10^{-5}$ for the first time.

hep-ex↗
arXiv2026

Precision Measurement of $D_{s}^{*+}$-$D_{s}^{+}$ Mass Difference

We measure the mass difference between $D_{s}^{*+}$ and $D_{s}^{+}$, $Δm_s$, using the decay chain $D_{s}^{*+} \to D_{s}^{+}(\to K^{+} K^{-} π^{+})π^{0}$, utilizing $e^+e^-$ annihilation data corresponding to an integrated luminosity of 3.19 fb$^{-1}$ collected at a center-of-mass energy of 4.178 GeV with the BESIII detector. The measured value of $Δm_s = [144\,201.9 \pm 44.2({\rm stat.}) \pm 29.9({\rm syst.}) \pm 15.0({\rm PDG})]$ keV/$c^2$ is about seven times more precise than the current Particle Data Group average, where the last uncertainty is from the Particle Data Group average of the $D^{*+} - D^{+}$ mass difference.

hep-ex↗
arXiv2026

Thin single-crystal perovskite detector for high-energy charged particles

The organometal halide perovskites (OMHP) semi-conductors have shown recently a strong potential as radiation detectors, beside the well-known success in photovoltaics and as photo-detectors. Many studies have been published on X-rays detection, and a few studies about detection of alpha, beta-particles and protons. Less literature is present for high energy charged particles. OMHP-based devices for tracking and real-time monitoring for high energy particles may offer many advantages. OMHPs can be directly grown on pixelated electronics, even on curved substrates, without the need of complex and expensive bump-bonding procedures. Moreover, OMHPs have shown self-healing features after radiation exposure, which makes them attractive for high-flux applications. In this paper we report a device based on a thin single OMHP crystal, about 150 mum thick, directly grown on a patterned substrate through dewetting technique, able to detect high-energy charged particles in a high dynamic range of incident fluxes. A dedicated electronics circuit has been developed to match the expected time characteristics of the OMHP crystals. This is the first demonstration of thin OMHP single crystals being able to detect high energy charged particles of hundreds of MeV.

physics.ins-det↗
arXiv2026

Biophoton Emission from Palm during Meditation: A Multi-Method Complexity Analysis

Biophotons are ultra-weak photon emissions in the visible spectrum produced by living organisms. While extensively studied in plants, germinating seeds, and cell cultures, no systematic multi-method complexity analysis of human ultraweak photon emission (UPE) under physiological modulation has been reported. We address this gap by applying a comprehensive analytical framework to UPE measurements from the right palm of a human subject. Three independent sessions were conducted on different days, each comprising four consecutive 15-minute phases: Dark reference, pre-meditation resting state (Pre), structured meditation based on the Sama Vritti box-breathing protocol, and post-meditation recovery (Post). Photon count series are analysed with four complementary methods: distributional statistics (Fano factor, skewness, tail Expected Shortfall); multiscale Fano factor and Allan deviation; stripe-filtered Diffusion Entropy Analysis (DEA); and Renyi entropy with a Time Reversal test. The methods show complementary sensitivities, converging on a coherent picture: a systematic reduction of emission intermittency during meditation, consistently detected across all three sessions. Stripe-filtered DEA places the emission in the non-ergodic renewal regime with a Pre-to-Meditation decrease of the scaling exponent. Renyi analysis reveals two effects: reduced marginal amplitude burstiness (Tdir) and increased sequential pattern structure (Tseq), interpreted as entrainment to the Sama Vritti rhythm. These findings are consistent with cardiac complexity transitions during meditation reported by Tuladhar et al. and with EEG reorganization during Sama Vritti breathing by Zaccaro et al., suggesting a coordinated multi-channel physiological response. The results establish a proof-of-concept framework for complexity analysis of human UPE under physiological modulation.

physics.bio-ph↗
arXiv2026

Study of the reactions $\bar{n} p \to 2π^{+}π^{-}$, $2π^{+}π^{-}π^{0}$, and $2π^{+}π^{-}2π^{0}$ using $J/ψ\to p π^{-}\bar{n}$

We report an experimental investigation of the reactions $\bar{n} p \to 2π^{+}π^{-}$, $\bar{n} p \to 2π^{+}π^{-}π^{0}$, and $\bar{n} p \to 2π^{+}π^{-}2π^{0}$ using $(10.087 \pm 0.044) \times 10^{9}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring. The antineutron ($\bar{n}$) is produced in the decay $J/ψ\to p π^{-} \bar{n}$ with studied momentum from 200~MeV/$c$ to 1174~MeV/$c$, while the target proton originates from the hydrogen nuclei in the cooling oil of the beam pipe. This novel method pioneers the study of $\bar{n}$-nucleon interactions at an $e^{+}e^{-}$ collider, providing the first experimental data for $\bar{n}$ momenta exceeding 800~MeV/$c$.

hep-ex↗
arXiv2026

Precise Measurement of Matter-Antimatter Asymmetry with Entangled Hyperon Antihyperon Pairs

A search for $CP$ violation with an entangled system of $Ξ^-\barΞ^+$ pairs is performed, using $(10,087\pm44)\times10^{6}$ $J/ψ$ events collected with the BESIII experiment. A nine-dimensional helicity amplitude is used to fit $e^+e^- \to J/ψ\toΞ^-\barΞ^+$ and its subsequent decays. The $Ξ^-$ and $Ξ^+$ decay parameters are determined with higher precision compared to the best results reported so far. Furthermore, the strong phase difference, $(δ_P-δ_S)=(0.3\pm1.2\pm0.2)\times10^{-2}~\text{rad}$, and the weak phase difference, $(ξ_P-ξ_S)=(-0.2\pm1.2\pm0.1)\times10^{-2}~\text{rad}$, are directly determined. These are the most precise measurements to date. The $CP$ asymmetry observables $A_{CP}^Ξ=(-7.8\pm4.8\pm0.8)\times10^{-3}$ and $Δϕ_{CP}^Ξ=(0.6\pm5.1\pm0.2)\times10^{-3}~\text{rad}$ are determined, which are consistent with $CP$ conservation. In addition, independent measurements of the $Λ$ decay parameter and $CP$ asymmetry $A^Λ_{CP}=(-2.9\pm4.3\pm0.7)\times10^{-3}$ are also obtained, which are in agreement with the previous measurements, but with much improved precision.

hep-ex↗
arXiv2026

Search for the charmonium semi-leptonic weak decay $J/ψ\rightarrow D_s^-e^+ν_e+c.c.$

Using a data sample of $(10087 \pm 44) \times 10^6$ $J/ψ$ events collected with the BESIII detector at a centre-of-mass energy of $\sqrt{s}=3.097\ \textrm{GeV}$, a dedicated search for the charmonium semileptonic weak decay $J/ψ\rightarrow D_s^-e^+ν_e + \text{c.c.}$ is performed. No significant signal is observed. An upper limit on the branching fraction is set at $\mathcal{B}(J/ψ\rightarrow D_s^- e^+ ν_e + \text{c.c.}) < 9.9 \times 10^{-8}$ at the 90\% confidence level. This result improves upon previous constraints by an order of magnitude, representing the most stringent experimental limit to date. It thus provides a critical test of Standard Model predictions and new physics scenarios in heavy-quark dynamics.

hep-ex↗
arXiv2026

Search for the charmonium weak decay $J/ψ\to\bar{D}^0\bar{K}^{*0}+{\rm c.c.}$

Based on a sample of $(10087\pm44)\times10^6$ $J/ψ$ events collected at the center-of-mass energy $\sqrt{s}$ = 3.0969 GeV with the BESIII detector, we search for the charmonium rare weak decay $J/ψ\to\bar{D}^0\bar{K}^{*0}+{\rm c.c.}$. No significant signal is observed, and the upper limit on its decay branching fraction at the 90% confidence level is set as $1.4\times10^{-7}$, improving the sensitivity of the previous best limit by an order of magnitude.

hep-ex↗
arXiv2026

Amplitude Analysis and Branching Fraction Measurement of $D^+ \to π^+π^0π^0$

We present the first amplitude analysis of the hadronic decay $D^+\toπ^+π^0π^0$, using $e^{+}e^{-}$ collision data collected with the BESIII detector at a center-of-mass energy of 3.773~GeV, corresponding to an integrated luminosity of 20.3~fb$^{-1}$. The fit fractions of the intermediate processes are measured, in which the $D^+ \to ρ(770)^+π^0$ component is found to be dominant with a branching fraction of $(3.08\kern0.15em\pm\kern0.15em0.10_{\rm stat.}\pm0.05_{\rm syst.})\times10^{-3}$. Based on the amplitude analysis, the branching fraction of $D^+ \to π^+π^0π^0$ is measured to be $(4.84\kern0.1em\pm\kern0.1em0.05_{\rm stat.}\kern0.1em\pm\kern0.1em0.05_{\rm syst.})\times10^{-3}$. In addition, the CP asymmetries, both for specific amplitudes and integrated over the entire phase space, are measured.

hep-ex↗