arXiv subjects

J. Yelton

Publications and source records attributed to J. Yelton.

At least 19 recordsLinked to original sources

arXiv2026

Averages of $b$-hadron, $c$-hadron, and $τ$-lepton properties as of 2023

This paper reports world averages of measurements of $b$-hadron, $c$-hadron, and $τ$-lepton properties obtained by the Heavy Flavour Averaging Group using results available before October 2023. In rare cases, significant results obtained several months later are also used. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, CP violation parameters, parameters of semileptonic decays, and Cabibbo-Kobayashi-Maskawa matrix elements.

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arXiv2025

HFLAV input to the 2026 update of the European Strategy for Particle Physics

Heavy-flavour physics is an essential component of the particle-physics programme, offering critical tests of the Standard Model and far-reaching sensitivity to physics beyond it. Experiments such as LHCb, Belle II, and BESIII drive progress in the field, along with contributions from ATLAS and CMS. The LHCb Upgrade II and upgraded Belle II experiments will provide unique and highly sensitive measurements for decades, playing a key role in the searches for new physics. Future facilities with significant heavy-flavour capabilities will further expand these opportunities. We advocate for a European Strategy that fully supports Upgrade II of LHCb and an upgrade of Belle II, along with their subsequent exploitation. Additionally, we support a long-term plan that fully integrates flavour physics in an $e^+e^-$ collider to run as a $Z$ factory.

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arXiv2023

First Observation of $Λπ^+$ and $Λπ^-$ Signals near the $\bar{K}N (I=1)$ Mass Threshold in $Λ_c^+\rightarrowΛπ^+π^+π^-$ Decay

Using the data sample of 980 fb$^{-1}$ collected with the Belle detector operating at the KEKB asymmetric-energy $e^+e^-$ collider, we present the results of an investigation of the $Λπ^+$ and $Λπ^-$ invariant mass distributions looking for substructure in the decay $Λ_c^+\rightarrowΛπ^+π^+π^-$. We find a significant signal in each mass dis\ tribution. When interpreted as resonances, we find for the $Λπ^+$ ($Λπ^-$) combination a mass of $1434.3 \pm 0.6 (\mathrm{stat}) \pm 0.9(\mathrm{syst})$ MeV/$c^2$ [$1438.5 \pm 0.9 (\mathrm{stat}) \pm 2.5(\mathrm{syst})$ MeV/$c^2$], an intrinsic width of $11.5 \pm 2.8 (\mathrm{stat}) \pm 5.3(\mathrm{syst})$ MeV/$c^2$ [$33.0 \pm 7.5 (\mathrm{stat}) \pm 23.6(\mathrm{syst})$ MeV/$c^2$] with a significance of 7.5$σ$ (6.2$σ$). As these two signals are very close to the $\bar{K}N$ threshold, we also investigate the possibility of a $\bar{K}N$ cusp, and find that \ we cannot discriminate between these two interpretations due to the limited size of the data sample.

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arXiv2023

Averages of $b$-hadron, $c$-hadron, and $τ$-lepton properties as of 2021

This paper reports world averages of measurements of $b$-hadron, $c$-hadron, and $τ$-lepton properties obtained by the Heavy Flavour Averaging Group using results available before April 2021. In rare cases, significant results obtained several months later are also used. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, CP violation parameters, parameters of semileptonic decays, and Cabibbo-Kobayashi-Maskawa matrix elements.

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arXiv2023

Measurement of the mass and width of the $Λ_c(2625)^+$ and the branching ratios of $Λ_c(2625)^+ \to Σ_c^{0}π^{+}$ and $Λ_c(2625)^+ \to Σ_c^{++}π^{-}$

Using the entire data sample of $980\,\textrm{fb}^{-1}$ collected with the Belle detector operating at the KEKB asymmetric-energy collider, we report the measurement of the mass, width, and the relative branching ratios of the $Λ_c(2625)^+$ charmed baryon. The mass difference between $Λ_c(2625)^+$ and $Λ_c^+$ is measured to be $M(Λ_c(2625)^{+}) - M(Λ_c^{+}) = 341.518 \pm 0.006 \pm 0.049\ \mathrm{MeV}/\mathit{c}^2$. The upper limit on the width is measured to be $Γ(Λ_c(2625)^+) < 0.52\,\mathrm{MeV}/\textit{c}^2$ at 90\% credibility level. Based on a full Dalitz plot fit, branching ratios with respect to the mode $Λ_c(2625)^+ \to Λ_c^+ π^+ π^-$ are measured to be $\frac{\mathcal{B}(Λ_c(2625)^+ \to Σ_c^{0} π^{+})} {\mathcal{B}(Λ_c(2625)^+ \to Λ_c^+ π^{+} π^{-})} = (5.19 \pm 0.23 \pm 0.40) \%$ and $\frac{\mathcal{B}(Λ_c(2625)^+ \to Σ_c^{++} π^{-})} {\mathcal{B}(Λ_c(2625)^+ \to Λ_c^+ π^{+} π^{-})} = (5.13 \pm 0.26 \pm 0.32) \%$. These measurements can be used to further constrain the parameters of the underlying theoretical models.

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arXiv2022

Belle II Executive Summary

Belle II is a Super $B$ Factory experiment, expected to record 50 ab$^{-1}$ of $e^+e^-$ collisions at the SuperKEKB accelerator until 2035. The large samples of $B$ mesons, charm hadrons, and tau leptons produced in the clean experimental environment of $e^+e^-$ collisions will provide the basis of a broad and unique flavor-physics program. Belle II will pursue physics beyond the Standard Model in many ways, for example: improving the precision of weak interaction parameters, particularly Cabibbo-Kobayashi-Maskawa (CKM) matrix elements and phases, and thus more rigorously test the CKM paradigm, measuring lepton-flavor-violating parameters, and performing unique searches for missing-mass dark matter events. Many key measurements will be made with world-leading precision.

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arXiv2021

Measurement of the Masses and Widths of the $Σ_c(2455)^+$ and $Σ_c(2520)^+$ Baryons

Using 980 ${\rm fb}^{-1}$ of data {collected} with the Belle detector operating at the KEKB asymmetric-energy $e^+e^-$ collider, we report the measurements of the masses, and the first measurements of the instrinsic widths, of the $Σ_c(2455)^+$ and $Σ_c(2520)^+$ charmed baryons. We find $M(Σ_c(2455)^+)-M(Λ_c^+) = 166.17\pm 0.05^{+0.16}_{-0.07}\ {\rm MeV}/c^2$, $Γ(Σ_c(2455)^+) = 2.3 \pm 0.3 \pm 0.3\ {\rm MeV/c^2}$, $M(Σ_c(2520)^+)-M(Λ_c^+) = 230.9 \pm 0.5 ^{+0.5}_{-0.1}\ {\rm MeV}/c^2$, and $Γ(Σ_c(2520)^+) = 17.2^{+2.3\ +3.1}_{-2.1\ -0.7}\ {\rm MeV}/c^2$, where the uncertainties are statistical and systematic, respectively. These measurements can be used to test models of the underlying quark structure of the $Σ_c$ states.

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arXiv2021

Averages of $b$-hadron, $c$-hadron, and $τ$-lepton properties as of 2018

This paper reports world averages of measurements of $b$-hadron, $c$-hadron, and $τ$-lepton properties obtained by the Heavy Flavor Averaging Group using results available through September 2018. In rare cases, significant results obtained several months later are also used. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, CP violation parameters, parameters of semileptonic decays, and Cabibbo-Kobayashi-Maskawa matrix elements.

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arXiv2021

Measurement of the Resonant and Non-Resonant Branching Ratios in $Ξ_{c}^{0} \rightarrow Ξ^{0} K^+ K^-$

Using the entire data sample of $980$ $fb^{-1}$ integrated luminosity collected with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider, we present an amplitude analysis measuring the branching fractions of the Cabibbo-allowed, $W$-exchange resonant decay $Ξ_{c}^{0} \rightarrow Ξ^{0} ϕ(\to K^+ K^-)$ with a polarized $ϕ$ and the non-resonant decay via a direct process $Ξ_{c}^{0} \rightarrow Ξ^{0} K^+ K^-$. We present these measurements, relative to the normalization mode $Ξ^{-}π^{+}$, and find branching ratios $\frac{\mathcal{B}(Ξ_{c}^{0} \rightarrow Ξ^{0} ϕ(\rightarrow K^{+}K^{-}))}{\mathcal{B}(Ξ_{c}^{0} \rightarrow Ξ^{-} π^{+})} = 0.036 \pm 0.004 (stat.) \pm 0.002 (syst.)$ and $\frac{\mathcal{B}(Ξ_{c}^{0} \rightarrow Ξ^{0} K^{+} K^{-})}{\mathcal{B}(Ξ_{c}^{0} \rightarrow Ξ^{-} π^{+})} = 0.039 \pm 0.004 (stat.) \pm 0.002 (syst.)$ which suggest that only minor cusping peaks occur in the combinatorial background of $Ω^{*-} \to Ξ^{0}K^{-}$ due to these $Ξ_{c}^{0}$ decays.

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arXiv2020

Study of Electromagnetic Decays of Orbitally Excited $Ξ_c$ Baryons

Using 980 $fb^-1$ of data collected with the Belle detector operating at the KEKB asymmetric-energy e^+e^- collider, we report a study of the electromagnetic decays of excited {charmed baryons} $Ξ_c(2790)$ and $Ξ_c(2815)$. A clear signal (8.6 standard deviations) is observed for $Ξ_c(2815)^0 \to Ξ_c^0γ$, and we measure: $B[Ξ_c(2815)^0 \to Ξ_c^0γ]/B[Ξ_c(2815)^0 \to Ξ_c(2645)^+π^- \to Ξ_c^0π^+π^-] = 0.41 \pm 0.05 \pm 0.03$. We also present evidence (3.8 standard deviations) for the similar decay of the $Ξ_c(2790)^0$ and measure: $B[Ξ_c(2790)^{0}\toΞ_c^{0}γ]/B[Ξ_c(2790)^0\toΞ_c^{\prime +}π^{-}\toΞ_c^{+}γπ^-] = 0.13 \pm 0.03 \pm 0.02$. The first quoted uncertainties are statistical and the second systematic. We find no hint of the analogous decays of the $Ξ_c(2815)^+$ and $Ξ_c(2790)^+$ baryons and set upper limits at the 90% confidence level of: $B[Ξ_c(2815)^{+}\toΞ_c^{+}γ]/B[Ξ_c(2815)^+\toΞ_c(2645)^0π^+\toΞ_c^+π^-π^+] < 0.09,$ and $B[Ξ_c(2790)^{+}\toΞ_c^{+}γ]/B[Ξ_c(2790)^+\toΞ_c^{\prime 0}π^{+}\toΞ_c^{0}γπ^+] < 0.06.$ Approximate values of the partial widths of the decays are extracted, which can be used to discriminate between models of the underlying quark structure of these excited states.

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arXiv2020

Snowmass 2021 Letter of Interest: Decays of Heavy Flavors Beauty, Charm, and Tau

The Heavy Flavor Averaging Group provides this Letter of Interest (LOI) as input to the Snowmass 2021 Particle Physics Community Planning Exercise organized by the Division of Particles and Fields of the American Physical Society. Research in heavy flavor physics is an essential component of particle physics, both within and beyond the Standard Model. To fully realize the potential of this field, we advocate strong support within the U.S. high energy physics program for ongoing and future experimental and theory research in heavy flavor physics.

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arXiv2018

HFLAV input to the update of the European Strategy for Particle Physics

The Heavy Flavor Averaging Group provides with this document input to the European Strategy for Particle Physics. Research in heavy-flavor physics is an essential component of the particle-physics program, both within and beyond the Standard Model. To fully realize the potential of the field, we believe the strategy should include strong support for the ongoing experimental and theoretical heavy-flavor research, future upgrades of existing facilities, and significant heavy-flavor capabilities at future colliders, including dedicated experiments.

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arXiv2018

Observation of an excited $Ω^-$ baryon

Using data recorded with the Belle detector, we observe a new excited hyperon, an $Ω^{*-}$ candidate decaying into $Ξ^0K^-$ and $Ξ^-K^0_S$ with a mass of $2012.4\pm0.7\ {\rm (stat)\pm\ 0.6\ (\rm syst)}\ {\rm MeV}/c^2$ and a width of $Γ=6.4^{+2.5}_{-2.0}\ {\rm(stat)}\pm1.6\ {\rm(syst)}\ {\rm MeV}$. The $Ω^{*-}$ is seen primarily in $Υ(1S), Υ(2S)$, and $Υ(3S)$ decays.

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arXiv2018

Observation of Excited $Ω_c$ Charmed Baryons in $e^+e^-$ Collisions

Using the entire Belle data sample of 980 ${\rm fb}^{-1}$ of $e^+e^-$ collisions, we present the results of a study of excited $Ω_c$ charmed baryons in the decay mode $Ξ_c^+K^-$. We show confirmation of four of the five narrow states reported by the LHCb Collaboration: the $Ω_c(3000)$ , $Ω_c(3050)$, $Ω_c(3066)$, and $Ω_c(3090)$.

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arXiv2018

Measurement of Branching Fractions of Hadronic Decays of the $Ω_c^0$ Baryon

Using a data sample of 980 ${\rm fb}^{-1}$ of $e^+e^-$ annihilation data taken with the Belle detector operating at the KEKB asymmetric-energy $e^+e^-$ collider, we report the results of a study of the decays of the $Ω_c^0$ charmed baryon into hadronic final states. We report the most precise measurements to date of the relative branching fractions of the $Ω_c^0$ into $Ω^-π^+π^0$, $Ω^-π^+π^-π^+$, $Ξ^-K^-π^+π^+$, and $Ξ^0K^-π^+$, as well as the first measurements of the branching fractions of the $Ω_c^0$ into $Ξ^-\bar{K}^0π^+$, $Ξ^0\bar{K}^0$, and $Λ\bar{K}^0\bar{K}^0$, all with respect to the $Ω^-π^+$ decay. In addition, we investigate the resonant substructure of these modes. Finally, we present a limit on the branching fraction for the decay $Ω_c^0\toΣ^+K^-K^-π^+$.

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arXiv2018

Averages of $b$-hadron, $c$-hadron, and $τ$-lepton properties as of summer 2016

This article reports world averages of measurements of $b$-hadron, $c$-hadron, and $τ$-lepton properties obtained by the Heavy Flavor Averaging Group using results available through summer 2016. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, \CP~violation parameters, parameters of semileptonic decays and CKM matrix elements.

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arXiv2016

Studies of the decays D^0 \rightarrow K_S^0K^-π^+ and D^0 \rightarrow K_S^0K^+π^-

The first measurements of the coherence factor R_{K_S^0Kπ} and the average strong--phase difference δ^{K_S^0Kπ} in D^0 \to K_S^0 K^\mpπ^\pm decays are reported. These parameters can be used to improve the determination of the unitary triangle angle γ in B^- \rightarrow $\widetilde{D}K^-$ decays, where $\widetilde{D}$ is either a D^0 or a D^0-bar meson decaying to the same final state, and also in studies of charm mixing. The measurements of the coherence factor and strong-phase difference are made using quantum-correlated, fully-reconstructed D^0D^0-bar pairs produced in e^+e^- collisions at the ψ(3770) resonance. The measured values are R_{K_S^0Kπ} = 0.70 \pm 0.08 and δ^{K_S^0Kπ} = (0.1 \pm 15.7)$^\circ$ for an unrestricted kinematic region and R_{K*K} = 0.94 \pm 0.12 and δ^{K*K} = (-16.6 \pm 18.4)$^\circ$ for a region where the combined K_S^0 π^\pm invariant mass is within 100 MeV/c^2 of the K^{*}(892)^\pm mass. These results indicate a significant level of coherence in the decay. In addition, isobar models are presented for the two decays, which show the dominance of the K^*(892)^\pm resonance. The branching ratio {B}(D^0 \rightarrow K_S^0K^+π^-)/{B}(D^0 \rightarrow K_S^0K^-π^+) is determined to be 0.592 \pm 0.044 (stat.) \pm 0.018 (syst.), which is more precise than previous measurements.

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arXiv2016

Study of Excited $Ξ_c$ States Decaying into $Ξ_c^0$ and $Ξ_c^+$ Baryons

Using a data sample of 980 ${\rm fb}^{-1}$ of $e^+e^-$ annihilation data taken with the Belle detector operating at the KEKB asymmetric-energy $e^+e^-$ collider, we report the results of a study of excited $Ξ_c$ states that decay, via the emission of photons and/or charged pions, into $Ξ_c^0$ or $Ξ_c^+$ ground state charmed-strange baryons. We present new measurements of the masses of all members of the $Ξ_c^{\prime}$, $Ξ_c(2645)$, $Ξ_c(2790)$, $Ξ_c(2815)$, and $Ξ_c(2980)$ isodoublets, measurements of the intrinsic widths of those that decay strongly, and evidence of previously unknown transitions.

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