arXiv subjects

M. Laurenza

Publications and source records attributed to M. Laurenza.

At least 19 recordsLinked to original sources

arXiv2026

Assessing VBz variations during CME propagation: a preparatory study for the HENON mission using EUHFORIA

Coronal mass ejections (CMEs) are among the main drivers of space weather hazards. In this context, HENON is a new space mission designed to carry out observations in the solar wind upstream of the Earth, aiming to provide timely alerts for hazardous perturbations propagating towards the Earth. HENON will orbit Earth on a distant retrograde orbit, approximately 0.082 AU upstream of the Earth when it is on the Sun-Earth line. The measurements taken by HENON will allow us to determine plasma and magnetic field parameters with a lead time of several hours with respect to the Lagrangian point L1. We assess the VB_z parameter variations (the product of solar wind speed V and southward magnetic field B_z) along the HENON orbit. Given its role as a primary driver of geomagnetic activity, we analyse how these measurements change with respect to Earth's position to evaluate HENON's forecasting potential. We used the FRi3D CME model of the EUHFORIA simulation code to characterize the initial properties of the CME. FRi3D allows us to set the CME magnetic field as a magnetic flux rope. From the simulation results, we evaluated the VB_z parameter at nine virtual spacecraft positions along the planned HENON orbit. The heliocentric longitudes of the virtual spacecraft range from about -6.9° to 6.9°, while the geocentric longitudes vary from -60° to +60° in steps of 15°. The initial direction of propagation of the CME central apex is either along the Sun-Earth line or at heliocentric longitudes of {\pm}30°. We find that with the proposed orbital parameters, the values of the VBz parameter along the HENON orbit are sufficiently similar to those measured in the vicinity of the Earth to be useful for space weather forecasts. HENON enables reliable VB_z estimates 2-8 hours in advance, improving space weather forecasting and protection of critical infrastructure and satellites.

astro-ph.SR↗

arXiv2025

Mission Analysis for the HENON CubeSat Mission to a Large Sun-Earth Distant Retrograde Orbit

The HEliospheric pioNeer for sOlar and interplanetary threats defeNce (HENON) mission is a CubeSat Space Weather mission, designed to operate in a Sun-Earth Distant Retrograde Orbit (DRO) at more than 10 million km from Earth. HENON will embark payloads tailored for Space Weather (SWE) observations: a high-resolution energetic particle radiation monitor, a Faraday cup, and a magnetometer, enabling quasi-real-time monitoring of interplanetary conditions in deep space. HENON has multiple objectives, such as demonstrating CubeSat capabilities in deep space, including long-duration electric propulsion with periodic telemetry and command, and robust attitude control for deep-space operations. It will pave the way for a future fleet of spacecraft on DROs, providing continuous near real-time measurements for SWE forecasting. This paper focuses on the mission analysis performed for phases A and B, with the main goal of defining a baseline transfer trajectory to a heliocentric DRO in co-orbital motion with Earth. The proposed transfer leverages a rideshare opportunity on a mission escaping Earth gravity field, most likely one headed toward the Sun-Earth L2 region, and relies exclusively on on-board electric propulsion to reach deep space, making it a pioneering demonstration of this approach and the technology. Under appropriate assumptions on the electric propulsion system performance, spacecraft mass, and propellant budget, it is shown that the HENON target DRO can be reached in about one year, accounting also for periodic interruptions of thrusting to allow for telemetry, tracking, and command.

astro-ph.EP↗

arXiv2025

Measurement of the Ratio of Partial Branching Fractions of Inclusive $\overline{B} \to X_u \ell \overlineν$ to $\overline{B} \to X_{c} \ell \overlineν$ and the Ratio of their Spectra with Hadronic Tagging

We present a measurement of the ratio of partial branching fractions of the semi-leptonic inclusive decays, $\overline{B} \to X_{u} \ell \overlineν$ to $\overline{B} \to X_{c} \ell \overlineν$, where $\ell = (e, μ)$, using the full Belle sample of $772 \times 10^{6}$ $B \kern 0.18em\overline{\kern -0.18em B}$ pairs collected at the $Υ(4S)$ resonance. The ratio is measured via a two-dimensional fit to the squared four-momentum transfer to the lepton pair, and the charged lepton energy in the $B$ meson rest frame, where the latter must be larger than $1$ Ge\kern -0.1em V, covering approximately $86\%$ and $78\%$ of the $\overline{B} \to X_{u} \ell \overlineν$ and $\overline{B} \to X_{c} \ell \overlineν$ phase space, respectively. We find $Δ\mathcal{B}(\overline{B} \to X_{u} \ell \overlineν)/ Δ\mathcal{B}(\overline{B} \to X_{c} \ell \overlineν) = (1.99 \pm 0.17_{\rm stat} \pm 0.16_{\rm syst}) \times 10^{-2}$ where the uncertainties are statistical and systematic, respectively. In addition, we report the partial branching fractions separately for charged and neutral $B$ meson decays, and for electron and muon decay channels. We place a limit on isospin breaking in $\overline{B} \to X_{u} \ell \overlineν$ decays, and find no indication of lepton flavor universality violation in either the charmed or charmless mode. Furthermore, we unfold the $\overline{B} \to X_{u} \ell \overlineν$ and $\overline{B} \to X_{c} \ell \overlineν$ yields and report the differential ratio in lepton energy and four-momentum transfer squared.

hep-ex↗

arXiv2025

The high-energy protons of the ground level enhancement (GLE74) event on 11 May 2024

High energy solar protons were observed by particle detectors aboard spacecraft in near-Earth orbit on May 11, 2024 and produced the 74th ground level enhancement (GLE74) event registered by ground-based neutron monitors. This study involves a detailed reconstruction of the neutron monitor response, along with the identification of the solar eruption responsible for the emission of the primary particles, utilizing both in situ and remote-sensing. Observations spanning proton energies from a few MeV to around 1.64 GeV, collected from the Solar and Heliospheric Observatory (SOHO), the Geostationary Operational Environmental Satellite (GOES), the Solar Terrestrial Relations Observatory (STEREO-A), and neutron monitors, were integrated with records of the associated solar soft X-ray flare, coronal mass ejection, and radio bursts, to identify the solar origin of the GLE74. Additionally, a time-shift analysis was conducted to link the detected particles to their solar sources. Finally, a comparison of GLE74 to previous ones is carried out. GLE74 reached a maximum particle rigidity of at least 2.4 GV and was associated with a series of type III, type II, and type IV radio bursts. The release time of the primary solar energetic particles (SEPs) with an energy of 500 MeV was estimated to be around 01:21 UT. A significant SEP flux was observed from the anti-Sun direction with a relatively broad angular distribution, rather than a narrow, beam-like pattern, particularly during the main phase at the particle peak flux. Comparisons with previous GLEs suggest that GLE74 was a typical event in terms of solar eruption dynamics.

astro-ph.SR↗

arXiv2024

Search for a heavy neutral lepton that mixes predominantly with the tau neutrino

We report a search for a heavy neutral lepton (HNL) that mixes predominantly with $ν_τ$. The search utilizes data collected with the Belle detector at the KEKB asymmetric energy $e^+ e^-$ collider. The data sample was collected at and just below the center-of-mass energies of the $Υ(4S)$ and $Υ(5S)$ resonances and has an integrated luminosity of $915~\textrm{fb}^{-1}$, corresponding to $(836\pm 12)\times 10^6$ $e^+e^\toτ^+τ^-$ events. We search for production of the HNL (denoted $N$) in the decay $τ^-\to π^- N$ followed by its decay via $N \to μ^+μ^- ν_τ$. The search focuses on the parameter-space region in which the HNL is long lived, so that the $μ^+μ^-$ originate from a common vertex that is significantly displaced from the collision point of the KEKB beams. Consistent with the expected background yield, one event is observed in the data sample after application of all the event-selection criteria. We report limits on the mixing parameter of the HNL with the $τ$ neutrino as a function of the HNL mass.

hep-ex↗

arXiv2024

Search for a dark leptophilic scalar produced in association with $τ^+τ^-$ pair in $e^+e^-$ annihilation at center-of-mass energies near 10.58 GeV

A dark leptophilic scalar $(ϕ_L)$ is a hypothetical particle that couples only to leptons rather than quarks. We report on a search for $ϕ_L$ in the $e^+e^- \to τ^+ τ^- ϕ_L, ~ϕ_L \to \ell^+ \ell^- ~(\ell = e, μ)$ process using 626~\invfb of data collected by the Belle experiment near the \Y4S resonance. We validate the backgrounds with multiple control regions in data, using a novel multiclass multivariate event classifier. In absence of a signal, we quote upper limits at the 90\% confidence level on the coupling between $ϕ_L$ and leptons. Our bounds, obtained in a blinded approach, are 19\% more constraining than the previous limits, averaged over the mass range $0.04 \leq m_{ϕ_L} \leq 6.5~\gev$. We exclude the parameter space below 4~\gev favored by measurement of the anomalous magnetic moment of the muon.

hep-ex↗

arXiv2023

Measurement of the $e^+e^- \to B_s^0 \bar{B}_s^0 X$ cross section in the energy range from $10.63$ to $11.02$ GeV using inclusive $D_s^{\pm}$ and $D^0$ production

We report the first measurement of the inclusive $e^+e^- \to b\bar{b} \to D_s^{\pm}X$ and $e^+e^- \to b\bar{b} \to D^0/\bar{D}^0X$ cross sections in the energy range from $10.63$ to $11.02$. Based on these results, we determine $σ(e^+ e^- \to B_s^0 \bar{B}_s^0 X)$ and $σ(e^+ e^- \to B\bar{B}X)$ in the same energy range. We measure the fraction of $B_s^0$ events at $Υ(10860)$ to be $f_{\rm s}=(22.0^{+2.0}_{-2.1})\%$. We determine also the ratio of the $B_s^0$ inclusive branching fractions $\mathcal{B}(B_s^0 \to D^0/\bar{D}^0X)/\mathcal{B}(B_s^0 \to D_s^{\pm} X)=0.416 \pm 0.018 \pm 0.092$. The results are obtained using the data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider.

hep-ex↗

arXiv2023

The 17 April 2021 widespread solar energetic particle event

Context. A solar eruption on 17 April 2021 produced a widespread Solar Energetic Particle (SEP) event that was observed by five longitudinally well-separated observers in the inner heliosphere at heliocentric distances of 0.42 to 1 au: BepiColombo, Parker Solar Probe, Solar Orbiter, STEREO A, and near-Earth spacecraft. The event produced relativistic electrons and protons. It was associated with a long-lasting solar hard X-ray flare and a medium fast Coronal Mass Ejection (CME) with a speed of 880 km/s driving a shock, an EUV wave as well as long-lasting radio burst activity showing four distinct type III burst. Methods. A multi-spacecraft analysis of remote-sensing and in-situ observations is applied to attribute the SEP observations at the different locations to the various potential source regions at the Sun. An ENLIL simulation is used to characterize the interplanetary state and its role for the energetic particle transport. The magnetic connection between each spacecraft and the Sun is determined. Based on a reconstruction of the coronal shock front we determine the times when the shock establishes magnetic connections with the different observers. Radio observations are used to characterize the directivity of the four main injection episodes, which are then employed in a 2D SEP transport simulation. Results. Timing analysis of the inferred SEP solar injection suggests different source processes being important for the electron and the proton event. Comparison among the characteristics and timing of the potential particle sources, such as the CME-driven shock or the flare, suggests a stronger shock contribution for the proton event and a more likely flare-related source of the electron event. Conclusions. We find that in this event an important ingredient for the wide SEP spread was the wide longitudinal range of about 110 degrees covered by distinct SEP injections.

astro-ph.SR↗

arXiv2023

Measurement of the $B^+/B^0$ production ratio in $e^+e^-$ collisions at the $Υ(4S)$ resonance using $B \rightarrow J/ψ(\ell\ell) K$ decays at Belle

We measure the ratio of branching fractions for the $Υ(4S)$ decays to $B^+B^-$ and $B^0\bar{B}{}^0$ using $B^+ \rightarrow J/ψ(\ell\ell) K^+$ and $B^0 \rightarrow J/ψ(\ell\ell) K^0$ samples, where $J/ψ(\ell\ell)$ stands for $J/ψ\to \ell^+\ell^-$ ($\ell = e$ or $μ$), with $711$ fb$^{-1}$ of data collected at the $Υ(4S)$ resonance with the Belle detector. We find the decay rate ratio of $Υ(4S) \rightarrow B^+B^-$ over $Υ(4S) \rightarrow B^0\bar{B}{}^0$ to be $1.065\pm0.012\pm 0.019 \pm 0.047$, which is the most precise measurement to date. The first and second uncertainties are statistical and systematic, respectively, and the third uncertainty is systematic due to the assumption of isospin symmetry in $B \to J/ψ(\ell\ell) K$.

hep-ex↗

arXiv2023

Search for rare decays $B^{+} \to D_{s}^{(\ast)+}η$, $D_{s}^{(\ast)+}\bar{K}^{0}$, $D^{+}η$, and $D^{+}K^{0}$

We present a study of rare decay modes $B^{+} \to D_{s}^{+}h^{0}$, $B^{+} \to D_{s}^{\ast+}h^{0}$, and $B^{+} \to D^{+}h^{0}$, where $h^{0}$ denotes the neutral mesons $η$ or $K^{0}$, using a data sample of $(772 \pm 10 ) \times 10^{6}$ $B\bar{B}$ events produced at the $Υ(4S)$ resonance. The data were collected by the Belle detector operating at the asymmetric-energy KEKB collider. We observe no evidence for these decays, so we provide upper limits at the 90$\%$ confidence level on the branching fractions of $B^{+} \to D_{s}^{+}h^{0}$, $D_{s}^{\ast+}h^{0}$, and $D^{+}h^{0}$ decay modes. Along with rare decay modes, we report improved measurements of the color-suppressed decay branching fractions $\mathcal{B}(\bar{B}^{0} \to D^{0}η)$ = (26.6 $\pm$ 1.2 $\pm$ 2.1) $\times$ $10^{-5}$ and $\mathcal{B}(\bar{B}^{0} \to D^{0}\bar{K}^{0})$ = (5.6 $\pm$ 0.5 $\pm$ 0.2) $\times$ $10^{-5}$. The first and second uncertainties are statistical and systematic, respectively.

hep-ex↗

arXiv2022

Evidence for the singly Cabibbo-suppressed decay $Ω^0_c\toΞ^-π^+$ and search for $Ω^0_c\toΞ^-K^+$ and $Ω^-K^+$ decays at Belle

Using a data sample of 980 fb$^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider, we study for the first time the singly Cabibbo-suppressed decays $Ω^0_c\toΞ^{-}π^{+}$ and $Ω^-K^+$ and the doubly Cabibbo-suppressed decay $Ω^0_c\to Ξ^- K^{+}$. Evidence for an $Ω^0_c$ signal in the $Ω^0_c\toΞ^-π^+$ mode is reported with a significance of $4.5σ$ including systematic uncertainties. The ratio of branching fractions to the normalization mode $Ω_c^0\to Ω^-π^+$ is measured to be $${\cal B}(Ω_{c}^{0} \to Ξ^{-} π^{+} )/{\cal B}(Ω_c^0\to Ω^-π^+)=0.253\pm 0.053({\rm stat.})\pm 0.030({\rm syst.}).$$ No significant signals of $Ω^0_c\toΞ^-K^+$ and $Ω^-K^+$ modes are found. The upper limits at $90\%$ confidence level on ratios of branching fractions are determined to be $${\cal B}(Ω_{c}^{0} \to Ξ^{-} K ^{+})/{\cal B}(Ω_c^0\to Ω^-π^+) < 0.070$$ and $${\cal B}(Ω_{c}^{0} \to Ω^{-}K^{+})/{\cal B}(Ω_c^0\to Ω^-π^+) < 0.29.$$

hep-ex↗

arXiv2022

Search for the lepton flavour violating decays $B^{+} \to K^{+} τ^\pm \ell^\mp$ ($\ell = e, μ$) at Belle

We present a search for the lepton-flavour-violating decays $B^+ \to K^+ τ^\pm \ell^\mp$, with $\ell = (e, μ)$, using the full data sample of $772 \times 10^6$ $B\overline{B}$ pairs recorded by the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We use events in which one $B$ meson is fully reconstructed in a hadronic decay mode. We find no evidence for $B^\pm \to K^\pm τ\ell$ decays and set upper limits on their branching fractions at the 90% confidence level in the $(1$-$3) \times 10^{-5}$ range. The obtained limits are the world's best results.

hep-ex↗

arXiv2022

Measurements of the branching fractions $\mathcal{B} (\bar{B}{}^0 \to D^{+} π^-)$ and $\mathcal{B} (\bar{B}{}^0 \to D^{+} K^-)$ and tests of QCD factorization

Using $(771.6 \pm 10.6) \times 10^6$ $B\bar{B}$ meson pairs recorded by the Belle experiment at the KEKB $e^+ e^-$ collider, we report the branching fractions $\mathcal{B}(\bar{B}^0 \to D^{*+} π^-) = (2.62 \pm 0.02 \pm 0.09)\times 10^{-3}$ and $\mathcal{B}(\bar{B}^0 \to D^{*+} K^-) = (2.22 \pm 0.06 \pm 0.08)\times 10^{-4}$; the quoted uncertainties are statistical and systematic, respectively. A measurement of the ratio of these branching fractions is also presented, $\mathcal{R}_{K/π}=\mathcal{B}(\bar{B} \to D^{*+}K^-) /\mathcal{B}( \bar{B} \to D^{*+}π^-) = (8.41 \pm 0.24 \pm 0.13)\times 10^{-2}$, where systematic uncertainties due to the $D^{*+}$ meson reconstruction cancel out. Furthermore, we report a new QCD factorization test based on the measured ratios for $\bar{B} \to D^{*+}h^-$ and $\bar{B} \to D^{*+}\ell^-ν$ decays at squared momentum transfer values equivalent to the mass of the $h = π$ or $K$ hadron. The parameters $|a_1(h)|$ are measured to be $|a_1(π)|= 0.884 \pm 0.004 \pm 0.003 \pm 0.016$ and $|a_1(K)|=0.913 \pm 0.019 \pm 0.008 \pm 0.013$, where the last uncertainties account for all external inputs. These values are approximately $15\%$ lower than those expected from theoretical predictions. Subsequently, flavor $SU(3)$ symmetry is tested by measuring the ratios for pions and kaons, $|a_1(K)|^2/ |a_1(π)|^2=1.066 \pm 0.042 \pm 0.018 \pm 0.023$, as well as for different particle species. The ratio is consistent with unity and therefore no evidence for $SU(3)$ symmetry breaking effects is found at the $5\%$ precision level.

hep-ex↗

arXiv2022

First search for the weak radiative decays $Λ_c^+ \to Σ^+ γ$ and $Ξ_c^0 \to Ξ^0 γ$

We present the first search for the weak radiative decays $Λ_c^+ \to Σ^+ γ$ and $Ξ_c^0 \to Ξ^0 γ$ using a data sample of 980~fb$^{-1}$ collected by the Belle detector operating at the KEKB asymmetric-energy $e^+e^-$ collider. There are no evident $Λ_c^+ \to Σ^+ γ$ or $Ξ_c^0 \to Ξ^0 γ$ signals. Taking the decays $Λ_c^+ \to p K^- π^+$ and $Ξ_c^0 \to Ξ^- π^+$ as normalization channels, the upper limits at 90\% credibility level on the ratios of branching fractions ${\cal B}(Λ_c^+ \to Σ^+ γ)/{\cal B}(Λ_c^+ \to p K^{-} π^+) < 4.0 \times 10^{-3}$ and ${\cal B}(Ξ_c^0 \to Ξ^0 γ)/{\cal B}(Ξ_c^0 \to Ξ^- π^+) < 1.2 \times 10^{-2}$ are determined. We obtain the upper limits at 90\% credibility level on the absolute branching fractions ${\cal B}(Λ_c^+ \to Σ^+ γ) < 2.6 \times 10^{-4}$ and ${\cal B}(Ξ_c^0 \to Ξ^0 γ) < 1.8 \times 10^{-4}$.

hep-ex↗

arXiv2022

Evidence of a new excited charmed baryon decaying to $Σ_{c}(2455)^{0,++} π^{\pm}$

We present the study of $\bar{B}^{0} \to Σ_{c}(2455)^{0,++} π^{\pm} \bar{p}$ decays based on $772\times 10^{6}$ $B\bar{B}$ events collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The $Σ_{c}(2455)^{0,++} $ candidates are reconstructed via their decay to $Λ_{c}^{+} π^{\mp}$ and $Λ_{c}^{+}$ decays to $pK^{-}π^{+},~pK_{S}^{0},$ and $Λπ^{+}$ final states. The corresponding branching fractions are measured to be ${\cal B}(\bar{B}^{0} \to Σ_{c}(2455)^{0} π^{+} \bar{p}) = (1.09 \pm 0.06 \pm 0.07)\times10^{-4}$ and ${\cal B}(\bar{B}^{0} \to Σ_{c}(2455)^{++} π^{-} \bar{p}) = (1.84\pm 0.11 \pm 0.12)\times 10^{-4}$, which are consistent with the world average values with improved precision. A new structure is found in the $M_{Σ_{c}(2455)^{0,++}π^{\pm}}$ spectrum with a significance of $4.2σ$ including systematic uncertainty. The structure is possibly an excited $Λ_{c}^{+}$ and is tentatively named $Λ_{c}(2910)^{+}$. Its mass and width are measured to be $(2913.8 \pm 5.6 \pm 3.8)$ MeV/$c^{2}$ and $(51.8\pm20.0 \pm 18.8)$ MeV, respectively. The products of branching fractions for the $Λ_{c}(2910)^{+}$ are measured to be ${\cal B}(\bar{B}^{0} \to Λ_{c}(2910)^{+}\bar{p})\times{\cal B}(Λ_{c}(2910)^{+} \to Σ_{c}(2455)^{0}π^{+}) = (9.5 \pm 3.6 \pm 1.6)\times 10^{-6}$ and ${\cal B}(\bar{B}^{0} \to Λ_{c} (2910)^{+}\bar{p})\times {\cal B}(Λ_{c}(2910)^{+} \to Σ_{c}(2455)^{++}π^{-}) = (1.24 \pm 0.35 \pm 0.10)\times 10^{-5}$. Here, the first and second uncertainties are statistical and systematic, respectively.

hep-ex↗

arXiv2022

$B$-flavor tagging at Belle II

We report on new flavor tagging algorithms developed to determine the quark-flavor content of bottom ($B$) mesons at Belle II. The algorithms provide essential inputs for measurements of quark-flavor mixing and charge-parity violation. We validate and evaluate the performance of the algorithms using hadronic $B$ decays with flavor-specific final states reconstructed in a data set corresponding to an integrated luminosity of $62.8$ fb$^{-1}$, collected at the $Υ$(4$S$) resonance with the Belle II detector at the SuperKEKB collider. We measure the total effective tagging efficiency to be $\varepsilon_{\rm eff} = \big(30.0 \pm 1.2(\text{stat}) \pm 0.4(\text{syst})\big)\%$ for a category-based algorithm and $\varepsilon_{\rm eff} = \big(28.8 \pm 1.2(\text{stat}) \pm 0.4(\text{syst})\big)\%$ for a deep-learning-based algorithm.

hep-ex↗

arXiv2022

Investigating Mercury's Environment with the Two-Spacecraft BepiColombo Mission

The ESA-JAXA BepiColombo mission will provide simultaneous measurements from two spacecraft, offering an unprecedented opportunity to investigate magnetospheric and exospheric dynamics at Mercury as well as their interactions with the solar wind, radiation, and interplanetary dust. Many scientific instruments onboard the two spacecraft will be completely, or partially devoted to study the near-space environment of Mercury as well as the complex processes that govern it. Many issues remain unsolved even after the MESSENGER mission that ended in 2015. The specific orbits of the two spacecraft, MPO and Mio, and the comprehensive scientific payload allow a wider range of scientific questions to be addressed than those that could be achieved by the individual instruments acting alone, or by previous missions. These joint observations are of key importance because many phenomena in Mercury's environment are highly temporally and spatially variable. Examples of possible coordinated observations are described in this article, analysing the required geometrical conditions, pointing, resolutions and operation timing of different BepiColombo instruments sensors.

astro-ph.EP↗

arXiv2022

First Measurement of the $Λ_c^+ \to p η'$ decay

We present the first measurement of the branching fraction of the singly Cabibbo-suppressed (SCS) decay $Λ_c^+ \to p η'$ with $η' \to ηπ^+π^-$, using a data sample corresponding to an integrated luminosity of 981 $\rm fb^{-1}$, collected by the Belle detector at the KEKB $e^{+}$$e^{-}$ asymmetric-energy collider. A significant $Λ_c^+$ signal is observed for the first time with a signal significance of 5.4$σ$. The relative branching fraction with respect to the normalization mode $Λ_c^+ \to pK^-π^+$ is measured to be \begin{equation*} \frac{{\cal B}(Λ_c^+ \to p η')}{{\cal B}(Λ_c^+ \to p K^-π^+)} = (7.54 \pm 1.32 \pm 0.75) \times 10^{-3}, \end{equation*} where the uncertainties are statistical and systematic, respectively. Using the world-average value of ${\cal B}(Λ_c^+ \to p K^-π^+) = (6.28\pm0.32)\times10^{-2}$, we obtain \begin{equation*} {\cal B}(Λ_c^+ \to p η') = (4.73 \pm 0.82 \pm 0.47 \pm 0.24)\times 10^{-4}, \end{equation*} where the uncertainties are statistical, systematic, and from ${\cal B}(Λ_c^+ \to pK^-π^+)$, respectively.

hep-ex↗