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L. K. Li

Publications and source records attributed to L. K. Li.

96 records · Page 6Linked to original sources
arXiv2018

Search for $CP$ violation in the $D^{+}\toπ^{+}π^{0}$ decay at Belle

We search for $CP$ violation in the charged charm meson decay $D^{+}\toπ^{+}π^{0}$, based on a data sample corresponding to an integrated luminosity of $\rm 921~fb^{-1}$ collected by the Belle experiment at the KEKB $e^{+}e^{-}$ asymmetric-energy collider. The measured $CP$ violating asymmetry is $[+2.31\pm1.24({\rm stat})\pm0.23({\rm syst})]\%$, which is consistent with the standard model prediction and has a significantly improved precision compared to previous results.

hep-ex↗
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 $Ω_c(3090)$.

hep-ex↗
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 $Ω_c^0\toΣ^+K^-K^-π^+$.

hep-ex↗
arXiv2018

Measurement of the $τ$ lepton polarization and $R(D^*)$ in the decay $\bar{B} \rightarrow D^* τ^- \barν_τ$ with one-prong hadronic $τ$ decays at Belle

With the full data sample of $772 \times 10^6$ $B{\bar B}$ pairs recorded by the Belle detector at the KEKB electron-positron collider, the decay $\bar{B} \rightarrow D^* τ^- \barν_τ$ is studied with the hadronic $τ$ decays $τ^- \rightarrow π^- ν_τ$ and $τ^- \rightarrow ρ^- ν_τ$. The $τ$ polarization $P_τ(D^*)$ in two-body hadronic $τ$ decays is measured, as well as the ratio of the branching fractions $R(D^{*}) = \mathcal{B}(\bar {B} \rightarrow D^* τ^- \barν_τ) / \mathcal{B}(\bar{B} \rightarrow D^* \ell^- \barν_\ell)$, where $\ell^-$ denotes an electron or a muon. Our results, $P_τ(D^*) = -0.38 \pm 0.51 {\rm (stat)} ^{+0.21}_{-0.16} {\rm (syst)}$ and $R(D^*) = 0.270 \pm 0.035{\rm (stat)} ^{+0.028}_{-0.025}{\rm (syst)}$, are consistent with the theoretical predictions of the Standard Model. The polarization values of $P_τ(D^*) > +0.5$ are excluded at the 90\% confidence level.

hep-ex↗
arXiv2017

Study of $K^0_S$ pair production in single-tag two-photon collisions

We report a measurement of the cross section for $K^0_S$ pair production in single-tag two-photon collisions, $γ^* γ\to K^0_S K^0_S$, for $Q^2$ up to 30 GeV$^2$, where $Q^2$ is the negative of the invariant mass squared of the tagged photon. The measurement covers the kinematic range 1.0 GeV < W < 2.6 GeV and $|\cos θ^*| < 1.0$ for the total energy and kaon scattering angle, respectively, in the $γ^* γ$ center-of-mass system. These results are based on a data sample of 759 fb$^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. For the first time, the transition form factor of the $f_2'(1525)$ meson is measured separately for the helicity-0, -1, and -2 components and also compared with theoretical calculations. Finally, the partial decay widths of the $χ_{c0}$ and $χ_{c2}$ mesons are measured as a function of $Q^2$.

hep-ex↗
arXiv2017

Search for light tetraquark states in $Υ(1S)$ and $Υ(2S)$ decays

We search for the $J^{PC}=0^{--}$ and $1^{+-}$ light tetraquark states with masses up to 2.46~GeV/$c^2$ in $Υ(1S)$ and $Υ(2S)$ decays with data samples of $(102\pm 2)$ million and $(158\pm 4)$ million events, respectively, collected with the Belle detector. No significant signals are observed in any of the studied production modes, and 90\% credibility level (C.L.) upper limits on their branching fractions in $Υ(1S)$ and $Υ(2S)$ decays are obtained. The inclusive branching fractions of the $Υ(1S)$ and $Υ(2S)$ decays into final states with $f_1(1285)$ are measured to be ${\cal B}(Υ(1S)\to f_1(1285)+anything)=(46\pm28({\rm stat.})\pm13({\rm syst.}))\times 10^{-4}$ and ${\cal B}(Υ(2S)\to f_1(1285)+anything)=(22\pm15({\rm stat.})\pm6.3({\rm syst.}))\times 10^{-4}$. The measured $χ_{b2} \to J/ψ+ anything$ branching fraction is measured to be $(1.50\pm0.34({\rm stat.})\pm0.22({\rm syst.}))\times 10^{-3}$, and 90\% C.L. upper limits for the $χ_{b0,b1} \to J/ψ+ anything$ branching fractions are found to be $2.3\times 10^{-3}$ and $1.1\times 10^{-3}$, respectively. For ${\cal B}(χ_{b1} \to ω+ anything)$, the branching fraction is measured to be $(4.9\pm1.3({\rm stat.})\pm0.6({\rm syst.}))\times 10^{-2}$. %($<3.68\times 10^{-2}$ at 90\% C.L.). All results reported here are the first measurements for these modes.

hep-ex↗