arXiv subjects

S. Han

Publications and source records attributed to S. Han.

At least 127 records · Page 7Linked to original sources

arXiv2019

Observation of $ψ(3686)\rightarrowΞ(1530)^{-}\barΞ(1530)^{+}$ and $Ξ(1530)^{-}\barΞ^{+}$

Using 448.1 $\times$ $10^{6}$ $ψ(3686)$ events collected with the BESIII detector at BEPCII, we employ a single-baryon tagging technique to make the first observation of $ψ(3686)\rightarrowΞ(1530)^{-}\barΞ(1530)^{+}$ and $Ξ(1530)^{-}\barΞ^{+}$ decays with a statistical significance of more than 10$σ$ and 5.0$σ$, respectively. The branching fractions are measured to be $\cal{B}$$[ψ(3686)\rightarrowΞ(1530)^{-}\barΞ(1530)^{+}] $ = (11.45 $\pm$ 0.40 $\pm$ 0.59) $\times$ $10^{-5}$ and $\cal{B}$$[ψ(3686)\rightarrowΞ(1530)^{-}\barΞ^{+}]$ = (0.70 $\pm$ 0.11 $\pm$ 0.04) $\times$ $10^{-5}$. The angular distribution parameter for $ψ(3686)\rightarrowΞ(1530)^{-}\barΞ(1530)^{+}$ is determined to be $α$ = 0.40 $\pm$ 0.24 $\pm$ 0.06, which agrees with the theoretical predictions within 1$σ$. The first uncertainties are statistical, and the second systematic.

hep-ex↗

arXiv2019

First observation of the decay $χ_{cJ}\to Σ^{+}\bar{p}K_{S}^{0}+c.c. ~(J = 0, 1, 2)$

Using E1 radiative transitions $ψ(3686) \to γχ_{cJ}$ from a sample of $(448.1 \pm 2.9)\times10^{6}$ $ψ(3686)$ events collected with the BESIII detector, the decays $χ_{cJ}\to Σ^{+}\bar{p}K_{S}^{0}+c.c.~(J = 0, 1, 2)$ are studied. The decay branching fractions are measured to be $\mathcal{B}(χ_{c0}\to Σ^{+}\bar{p}K_{S}^{0}+c.c.) = (3.52 \pm 0.19\pm 0.21)\times10^{-4}$, $\mathcal{B}(χ_{c1}\to Σ^{+}\bar{p}K_{S}^{0}+c.c.) = (1.53 \pm 0.10\pm 0.08)\times10^{-4}$, and $\mathcal{B}(χ_{c2}\to Σ^{+}\bar{p}K_{S}^{0}+c.c.) = (8.25 \pm 0.83 \pm 0.49)\times10^{-5}$, where the first and second uncertainties are the statistical and systematic ones, respectively. No evident intermediate resonances are observed in the studied processes.

hep-ex↗

arXiv2019

First measurement of near-threshold J/$ψ$ exclusive photoproduction off the proton

We report on the measurement of the $γp \rightarrow J/ψp$ cross section from $E_γ= 11.8$ GeV down to the threshold at $8.2$ GeV using a tagged photon beam with the GlueX experiment. We find the total cross section falls toward the threshold less steeply than expected from two-gluon exchange models. The differential cross section $dσ/dt$ has an exponential slope of $1.67 \pm 0.39$ GeV$^{-2}$ at $10.7$ GeV average energy. The LHCb pentaquark candidates $P_c^+$ can be produced in the $s$-channel of this reaction. We see no evidence for them and set model-dependent upper limits on their branching fractions $\mathcal{B}(P_c^+ \rightarrow J/ψp)$ and cross sections $σ(γp \to P_c^+)\times\mathcal{B}(P_c^+ \to J/ψp) $.

nucl-ex↗

arXiv2019

Search for the rare decay $η'\rightarrowπ^{0}π^{0}π^{0}π^{0}$ at BESIII

Based on a sample of 1.31 billion $J/ψ$ events collected with the BESIII detector, we perform a search for the rare decay $η'\rightarrow 4π^{0}$ via $J/ψ\rightarrowγη'$. No significant $η'$ signal is observed in the invariant mass spectrum of 4$π^{0}$. With a Bayesian approach, the upper limit on the branching fraction of $η'\rightarrow 4π^{0}$ is determined to be $\mathcal{B}(η'\rightarrow 4π^{0})$ $< 4.94\times10^{-5}$ at the 90\% confidence level, which is a factor of six smaller than the previous experimental limit.

hep-ex↗

arXiv2019

Evidence for the decays of $Λ^+_{c}\toΣ^+η$ and $Σ^+η^\prime$

We study the hadronic decays of $Λ_{c}^{+}$ to the final states $Σ^{+}η$ and $Σ^+η^\prime$, using an $e^{+}e^{-}$ annihilation data sample of 567 pb$^{-1}$ taken at a center-of-mass energy of 4.6 GeV with the BESIII detector at the BEPCII collider. We find evidence for the decays $Λ_{c}^{+}\rightarrowΣ^{+}η$ and $Σ^+η^\prime$ with statistical significance of $2.5σ$ and $3.2σ$, respectively. Normalizing to the reference decays $Λ_c^+\toΣ^+π^0$ and $Σ^+ω$, we obtain the ratios of the branching fractions $\frac{{\mathcal B}(Λ_c^+\toΣ^+η)}{{\mathcal B}(Λ_c^+\toΣ^+π^0)}$ and $\frac{{\mathcal B}(Λ_c^+\toΣ^+η^\prime)}{{\mathcal B}(Λ_c^+\toΣ^+ω)}$ to be $0.35 \pm 0.16 \pm 0.03$ and $0.86 \pm 0.34 \pm 0.07$, respectively. The upper limits at the 90\% confidence level are set to be $\frac{{\mathcal B}(Λ_c^+\toΣ^+η)}{{\mathcal B}(Λ_c^+\toΣ^+π^0)}<0.58$ and $\frac{{\mathcal B}(Λ_c^+\toΣ^+η^\prime)}{{\mathcal B}(Λ_c^+\toΣ^+ω)}<1.2$. Using BESIII measurements of the branching fractions of the reference decays, we determine $\mathcal B({Λ_{c}^{+}\rightarrowΣ^{+}η})=(0.41\pm0.19\pm0.05)\%$ ($<0.68\%$) and $\mathcal B({Λ_{c}^{+}\rightarrowΣ^{+}η'})=(1.34\pm0.53\pm0.21)\%$ ($<1.9\%$). Here, the first uncertainties are statistical and the second systematic. The obtained branching fraction of $Λ_c^+\toΣ^+η$ is consistent with the previous measurement, and the branching fraction of $Λ_{c}^{+}\rightarrowΣ^{+}η^{\prime}$ is measured for the first time.

hep-ex↗

arXiv2019

Cross section measurements of $e^{+}e^{-} \to K^{+}K^{-}K^{+}K^{-} $ and $ ϕK^{+}K^{-}$ at center-of-mass energies from 2.10 to 3.08 GeV

We measure the Born cross sections of the process $e^{+}e^{-} \to K^{+}K^{-}K^{+}K^{-}$ at center-of-mass (c.m.) energies, $\sqrt{s}$, between 2.100 and 3.080 GeV. The data were collected using the BESIII detector at the BEPCII collider. An enhancement at $\sqrt{s}= 2.232$ GeV is observed, very close to the $e^{+}e^{-} \to Λ\overlineΛ$ production threshold. A similar enhancement at the same c.m. energy is observed in the $e^{+}e^{-} \to ϕK^{+}K^{-}$ cross section. The energy dependence of the $K^{+}K^{-}K^{+}K^{-}$ and $ϕK^{+}K^{-}$ cross sections differs significantly from that of $e^{+}e^{-} \to ϕπ^{+}π^{-}$.

hep-ex↗

arXiv2019

Search for the decay $η'\toγγη$

Using a data sample of $1.31\times10^{9} ~J/ψ$ events collected with the BESIII detector, a search for $η'\toγγη$ via $J/ψ\toγη'$ is performed for the first time. No significant $η'$ signal is observed in the $γγη$ invariant mass spectrum, and the %upper limit of the branching fraction of $η'\toγγη$ is determined to be less than $1.33 \times 10^{-4}$ at the 90$\%$ confidence level.

hep-ex↗

arXiv2019

Observation and study of the decay $J/ψ\rightarrowϕηη'$

We report the observation and study of the decay $J/ψ\rightarrowϕηη'$ using $1.3\times{10^9}$ $J/ψ$ events collected with the BESIII detector. Its branching fraction, including all possible intermediate states, is measured to be $(2.32\pm0.06\pm0.16)\times{10^{-4}}$. We also report evidence for a structure, denoted as $X$, in the $ϕη'$ mass spectrum in the $2.0-2.1$ GeV/$c^2$ region. Using two decay modes of the $η'$ meson ($γπ^+π^-$ and $ηπ^+π^-$), a simultaneous fit to the $ϕη'$ mass spectra is performed. Assuming the quantum numbers of the $X$ to be $J^P = 1^-$, its significance is found to be 4.4$σ$, with a mass and width of $(2002.1 \pm 27.5 \pm 21.4)$ MeV/$c^2$ and $(129 \pm 17 \pm 9)$ MeV, respectively, and a product branching fraction $\mathcal{B}(J/ψ\rightarrowηX)\times{}\mathcal{B}(X\rightarrowϕη')=(9.8 \pm 1.2 \pm 1.7)\times10^{-5}$. Alternatively, assuming $J^P = 1^+$, the significance is 3.8$σ$, with a mass and width of $(2062.8 \pm 13.1 \pm 7.2)$ MeV/$c^2$ and $(177 \pm 36 \pm 35)$ MeV, respectively, and a product branching fraction $\mathcal{B}(J/ψ\rightarrowηX)\times{}\mathcal{B}(X\rightarrowϕη')=(9.6 \pm 1.4 \pm 2.0)\times10^{-5}$. The angular distribution of $J/ψ\rightarrowηX$ is studied and the two $J^P$ assumptions of the $X$ cannot be clearly distinguished due to the limited statistics. In all measurements the first uncertainties are statistical and the second systematic.

hep-ex↗

arXiv2019

Search for heavy Majorana neutrino in lepton number violating decays of D-> K pi e+ e+

Using the data sample of an integrated luminosity of 2.93 fb$^{-1}$ taken at the center-of-mass energy of 3.773 GeV, we search for the Majorana neutrino in the lepton number violating decays $D\to K πe^+ e^+$. No significant signal is observed, and the upper limits on the branching fraction at the 90\% confidence level are set to be $\mathcal{B}\,(D^0 \to K^- π^- e^+ e^+)<2.8\times10^{-6}$, $\mathcal{B}\,(D^+ \to K_S^0 π^- e^+ e^+)<3.3\times10^{-6}$ and $\mathcal{B}\,(D^+ \to K^- π^0 e^+ e^+)<8.5\times10^{-6}$. The Majorana neutrino is searched for with different mass assumptions ranging from 0.25 to 1.0 GeV/$c^2$ in the decays $D^0\to K^- e^+ ν_N(π^- e^+)$ and $D^+\to K_S^0 e^+ ν_N(π^- e^+)$, and the upper limits on the branching fraction at the 90\% confidence level are extracted to be at the level of $10^{-7} \sim 10^{-6}$, depending on the mass of Majorana neutrino. The constraints on the mixing matrix element $|V_{eN}|^2$ are also evaluated.

hep-ex↗

arXiv2019

Observation of $η_c\toωω$ in $J/ψ\toγωω$

Using a sample of $(1310.6\pm7.0)\times10^6$ $J/ψ$ events recorded with the BESIII detector at the symmetric electron positron collider BEPCII, we report the observation of the decay of the $(1^1 S_0)$ charmonium state $η_c$ into a pair of $ω$ mesons in the process $J/ψ\toγωω$. The branching fraction is measured for the first time to be $\mathcal{B}(η_c\toωω)= (2.88\pm0.10\pm0.46\pm0.68)\times10^{-3}$, where the first uncertainty is statistical, the second systematic and the third is from the uncertainty of $\mathcal{B}(J/ψ\toγη_c)$. The mass and width of the $η_c$ are determined as $M=(2985.9\pm0.7\pm2.1)\,$MeV/$c^2$ and $Γ=(33.8\pm1.6\pm4.1)\,$MeV.

hep-ex↗

arXiv2019

Study of the Decays $D_{s}^{+} \rightarrow K_{S}^{0}K^{+}$ and $K_{L}^{0}K^{+}$

Using an $e^{+}e^{-}$ annihilation data sample corresponding to an integrated luminosity of $3.19~\mathrm{fb}^{-1}$ and collected at a center-of-mass energy $\sqrt{s} = 4.178~\mathrm{GeV}$ with the BESIII detector, we measure the absolute branching fractions $\mathcal{B}(D_{s}^{+} \rightarrow K_{S}^{0}K^{+}) = (1.425\pm0.038_{\rm stat.}\pm0.031_{\rm syst.})\%$ and $\mathcal{B}(D_{s}^{+} \rightarrow K_{L}^{0}K^{+}) =(1.485\pm0.039_{\rm stat.}\pm0.046_{\rm syst.})\%$. The branching fraction of $D_{s}^{+} \rightarrow K_{S}^{0}K^{+}$ is compatible with the world average and that of $D_{s}^{+} \rightarrow K_{L}^{0}K^{+}$ is measured for the first time. We present the first measurement of the $K_{S}^{0}$-$K_{L}^{0}$ asymmetry in the decays $D_{s}^{+} \rightarrow K_{S,L}^{0}K^{+}$, and $R(D_{s}^{+} \rightarrow K_{S,L}^{0}K^{+})=\frac{\mathcal{B}(D_{s}^{+} \rightarrow K_{S}^{0}K^{+}) -\mathcal{B}(D_{s}^{+} \rightarrow K_{L}^{0}K^{+})}{\mathcal{B}(D_{s}^{+} \rightarrow K_{S}^{0}K^{+}) +\mathcal{B}(D_{s}^{+} \rightarrow K_{L}^{0}K^{+})}= (-2.1\pm1.9_{\rm stat.}\pm1.6_{\rm syst.})\%$. In addition, we measure the direct $CP$ asymmetries $A_{\rm CP}(D_{s}^{\pm} \rightarrow K_{S}^{0}K^{\pm}) = (0.6\pm2.8_{\rm stat.}\pm0.6_{\rm syst.})\%$ and $A_{\rm CP}(D_{s}^{\pm} \rightarrow K_{L}^{0}K^{\pm}) = (-1.1\pm2.6_{\rm stat.}\pm0.6_{\rm syst.})\%$.

hep-ex↗

arXiv2019

Study of the process $e^+ e^- \to p \bar p$ via initial state radiation at BESIII

The Born cross section for the process $e^+ e^- \to p \bar p $ is measured using the initial state radiation technique with an undetected photon. This analysis is based on datasets corresponding to an integrated luminosity of 7.5 fb$^{-1}$, collected with the BESIII detector at the BEPCII collider at center of mass energies between 3.773 and 4.600 GeV. The Born cross section for the process $e^+ e^- \to p \bar p $ and the proton effective form factor are determined in the $p\bar p$ invariant mass range between 2.0 and 3.8 GeV/$c^2$ divided into 30 intervals. The proton form factor ratio ($|G_E|/|G_M|$) is measured in 3 intervals of the $p\bar p$ invariant mass between 2.0 and 3.0 GeV/$c^2$.

hep-ex↗

arXiv2019

Observation of Multiphoton Frequency Conversion in Superconducting Circuits

Multiphoton up/down conversion in a transmon circuit, driven by a pair of microwaves tuned near and far off the qubit resonance, has been observed. The experimental realization of these high order non-linear processes is accomplished in the three-photon regime, when the transmon is coupled to weak bichromatic microwave fields with the same Rabi frequencies. A many-mode Floquet formalism, with longitudinal coupling, is used to simulate the quantum interferences in the absorption spectrum that manifest the multiphoton pumping processes in the transmon qubit. An intuitive graph theoretic approach is used to introduce effective Hamiltonians that elucidate main features of the Floquet results. The analytical solutions also illustrate how controllability is achievable for desired single- or multiphoton pumping processes in a wide frequency range.

quant-ph↗

arXiv2019

First observations of $h_c \to$ hadrons

Based on $(4.48 \pm 0.03) \times 10^{8}$ $ψ(3686)$ events collected with the BESIII detector, five $h_c$ hadronic decays are searched for via process $ψ(3686) \to π^0 h_c$. Three of them, $h_c \to p \bar{p} π^+ π^-$, $π^+ π^- π^0$, and $2(π^+ π^-) π^0$ are observed for the first time, with statistical significances of 7.4$σ$, $4.9σ$, and 9.1$σ$, and branching fractions of $(2.89\pm0.32\pm0.55)\times10^{-3}$, $(1.60\pm0.40\pm0.32)\times10^{-3}$, and $(7.44\pm0.94\pm1.56)\times10^{-3}$, respectively, where the first uncertainties are statistical and the second systematic. No significant signal is observed for the other two decay modes, and the corresponding upper limits of the branching fractions are determined to be $B(h_c \to 3(π^+ π^-) π^0)<8.7\times10^{-3}$ and $B(h_c \to K^+ K^- π^+ π^-)<5.8\times10^{-4}$ at 90% confidence level.

hep-ex↗

arXiv2019

Precision measurements of $σ_{B}(e^+e^- \to K_{S}^{0}K^{\pm}π^{\mp})$ at center-of-mass energies between 3.8 and 4.6 GeV

Using data samples collected by the BESIII detector operating at the BEPCII storage ring, we measure the $e^+e^- \to K_{S}^{0}K^{\pm}π^{\mp}$ Born cross sections at center-of-mass energies between 3.8 and 4.6\,GeV, corresponding to a luminosity of about 5.0~fb$^{-1}$. The results are compatible with the BABAR measurements, but with the precision significantly improved. A simple $1/s^n$ dependence for the continuum process can describe the measured cross sections, but a better fit is obtained by an additional resonance near 4.2\,GeV, which could be an excited charmonium or a charmonium-like state.

hep-ex↗

arXiv2019

Measurements of Weak Decay Asymmetries of $Λ_c^+\to pK_S^0$, $Λπ^+$, $Σ^+π^0$, and $Σ^0π^+$

Using $e^+e^-\toΛ_c^+\barΛ_c^-$ production from a 567 pb$^{-1}$ data sample collected by BESIII at 4.6 GeV, a full angular analysis is carried out simultaneously on the four decay modes of $Λ_c^+\to pK_S^0$, $Λπ^+$, $Σ^+π^0$, and $Σ^0π^+$. For the first time, the $Λ_c^+$ transverse polarization is studied in unpolarized $e^+e^-$ collisions, where a non-zero effect is observed with a statistical significance of 2.1$σ$. The decay asymmetry parameters of the $Λ_c^+$ weak hadronic decays into $pK_S^0$, $Λπ^+$, $Σ^+π^0$ and $Σ^0π^+$ are measured to be $0.18\pm0.43(\rm{stat})\pm0.14(\rm{syst})$, $-0.80\pm0.11(\rm{stat})\pm0.02(\rm{syst})$, $-0.57\pm0.10(\rm{stat})\pm0.07(\rm{syst})$, and $-0.73\pm0.17(\rm{stat})\pm0.07(\rm{syst})$, respectively. In comparison with previous results, the measurements for the $Λπ^+$ and $Σ^+π^0$ modes are consistent but with improved precision, while the parameters for the $pK_S^0$ and $Σ^0π^+$ modes are measured for the first time.

hep-ex↗

arXiv2019

Cross section measurements of $e^+ e^-\toωχ_{c0}$ from $\sqrt{s}=$4.178 to 4.278 GeV

The cross section of the process $e^+e^- \rightarrow ωχ_{c0}$ is measured at center-of-mass energies from $\sqrt{s} =$ 4.178 to 4.278 GeV using a data sample of 7 fb$^{-1}$ collected with the BESIII detector operating at the BEPCII storage ring. The dependence of the cross section on $\sqrt{s}$ shows a resonant structure with mass of $(4218.5\pm1.6(\text{stat.})\pm4.0(\text{syst.}))$ MeV/$c^2$ and width of $(28.2\pm3.9(\text{stat.})\pm1.6(\text{syst.}))$ MeV, respectively. This observation confirms and improves upon the result of a previous study. The angular distribution of the $e^+e^- \rightarrow ωχ_{c0}$ process is extracted for the first time.

hep-ex↗

arXiv2019

Search for the decay $D_s^+\rightarrow γe^+ν_e$

A search for the rare radiative leptonic decay $D_s^+\toγe^+ν_e$ is performed for the first time using electron-positron collision data corresponding to an integrated luminosity of 3.19 fb$^{-1}$, collected with the BESIII detector at a center-of-mass energy of 4.178 GeV. No evidence for the $D_s^+\toγe^+ν_e$ decay is seen and an upper limit of $\mathcal B(D_s^+\toγe^+ν_e)<1.3\times 10^{-4}$ is set on the partial branching fraction at a 90\% confidence level for radiative photon energies $E_γ^*>0.01$~GeV.

hep-ex↗