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Y. Bai

Publications and source records attributed to Y. Bai.

At least 379 records · Page 21Linked to original sources
arXiv2023

Study of $e^+e^-\toηϕ$ at center-of-mass energies from 3.773 to 4.600 GeV

We present a study of the process $e^{+}e^{-}\toηϕ$ using data samples collected with the BESIII detector corresponding to an integrated luminosity of 15.03 fb$^{-1}$ at 23 center-of-mass energies from 3.773 to 4.600 GeV. The Born cross sections are measured at each energy and a coherent fit to cross-section lineshape is performed using a Breit-Wigner parametrization to search for charmonium-like vector states. No significant signals of the $Y(4230)$ and $Y(4360)$ resonances are observed.

hep-ex↗
arXiv2023

Study of the doubly Cabibbo-suppressed decays $D^+_s\to K^+K^+π^-$ and $D^+_s\to K^+K^+π^-π^0$

Based on 7.33 fb$^{-1}$ of $e^+e^-$ collision data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, the experimental studies of the doubly Cabibbo-suppressed decays $D^+_s\to K^+K^+π^-$ and $D^+_s\to K^+K^+π^-π^0$ are reported. We determine the absolute branching fraction of $D^+_s\to K^+K^+π^-$ to be (${1.23^{+0.28}_{-0.25}}({\rm stat})\pm0.06({\rm syst})$) $\times 10^{-4}$. No significant signal of $D^+_s\to K^+K^+π^-π^0$ is observed and the upper limit on its decay branching fraction at 90\% confidence level is set to be $1.7\times10^{-4}$.

hep-ex↗
arXiv2023

Observation of the $ψ(3686)$ decays into $Σ^{+}\barΣ^{-}ω$ and $Σ^{+}\barΣ^{-}{\mathcalϕ}$

Based on $(27.08\pm 0.14)\times10^{8}$ $ψ(3686)$ events collected with the BESIII detector operating at the BEPCII collider, the $ψ(3686)\toΣ^{+}\barΣ^{-}ω$ and $Σ^{+}\barΣ^{-}ϕ$ decays are observed for the first time with statistical significances of 13.8$σ$ and 7.6$σ$, respectively. The corresponding branching fractions are measured to be $\mathcal{B}(ψ(3686)\toΣ^{+}\barΣ^{-}ω)=(1.90 \pm 0.18 \pm 0.21) \times 10^{-5}$ and $\mathcal{B}(ψ(3686)\toΣ^{+}\barΣ^{-}ϕ)=(2.96 \pm 0.54 \pm 0.41) \times 10^{-6}$, where the first uncertainties are statistical and the second systematic.

hep-ex↗
arXiv2023

GWTC-3: Compact Binary Coalescences Observed by LIGO and Virgo During the Second Part of the Third Observing Run

The third Gravitational-Wave Transient Catalog (GWTC-3) describes signals detected with Advanced LIGO and Advanced Virgo up to the end of their third observing run. Updating the previous GWTC-2.1, we present candidate gravitational waves from compact binary coalescences during the second half of the third observing run (O3b) between 1 November 2019, 15:00 UTC and 27 March 2020, 17:00 UTC. There are 35 compact binary coalescence candidates identified by at least one of our search algorithms with a probability of astrophysical origin $p_\mathrm{astro} > 0.5$. Of these, 18 were previously reported as low-latency public alerts, and 17 are reported here for the first time. Based upon estimates for the component masses, our O3b candidates with $p_\mathrm{astro} > 0.5$ are consistent with gravitational-wave signals from binary black holes or neutron star-black hole binaries, and we identify none from binary neutron stars. However, from the gravitational-wave data alone, we are not able to measure matter effects that distinguish whether the binary components are neutron stars or black holes. The range of inferred component masses is similar to that found with previous catalogs, but the O3b candidates include the first confident observations of neutron star-black hole binaries. Including the 35 candidates from O3b in addition to those from GWTC-2.1, GWTC-3 contains 90 candidates found by our analysis with $p_\mathrm{astro} > 0.5$ across the first three observing runs. These observations of compact binary coalescences present an unprecedented view of the properties of black holes and neutron stars.

gr-qc↗
arXiv2023

Measurement of the branching fractions of the singly Cabibbo-suppressed decays $Λ_{c}^{+}\to pη$ and $Λ_{c}^{+}\to pω$

Based on 4.5 $\mbox{fb$^{-1}$}$ $e^{+}e^{-}$ collision data collected with BESIII detector at seven energy points between 4.600 and 4.699 GeV, the branching fractions for $Λ_{c}^{+}\to pη$ and $Λ_{c}^{+}\to pω$ were measured by means of single-tag method. The branching fractions of $Λ_{c}^{+}\to pη$ and $Λ_{c}^{+}\to pω$ are determined to be $(1.57\pm0.11_{\rm {stat}}\pm0.04_{\rm{syst}})\times10^{-3}$ and $(1.11\pm0.20_{\rm{stat}}\pm0.07_{\rm{syst}})\times10^{-3}$, with a statistical significance of greater than 10 $σ$ and 5.7 $σ$, respectively. These results are consistent with the previous measurements by BESIII, LHCb and Belle, and the result of $Λ_{c}^{+}\to pη$ is the most precise to date.

hep-ex↗
arXiv2023

Search for $J/ψ$ weak decays containing $D$ meson

Using a sample of about 10 billion $J/ψ$ events with the BESIII detector, we search for the weak decays of $J/ψ\to \bar{D}^0π^0 + c.c.$, $J/ψ\to \bar{D}^0η+ c.c.$, $J/ψ\to \bar{D}^0ρ^0 + c.c.$, $J/ψ\to D^-π^+ + c.c.$, and $J/ψ\to D^-ρ^+ + c.c.$. Since no significant signal is observed, we set the upper limits of the branching fractions of these decays to be $\mathcal{B}(J/ψ\to \bar{D}^0π^0 + c.c.) < 4.7 \times 10^{-7}$, $\mathcal{B}(J/ψ\to \bar{D}^0η+ c.c.) < 6.8 \times 10^{-7}$, $\mathcal{B}(J/ψ\to \bar{D}^0ρ^0 + c.c.) < 5.2 \times 10^{-7}$, $\mathcal{B}(J/ψ\to D^-π^+ + c.c.) < 7.0 \times 10^{-8}$, and $\mathcal{B}(J/ψ\to D^-ρ^+ + c.c.) < 6.0 \times 10^{-7}$ at the 90\% confidence level.

hep-ex↗
arXiv2023

STCF Conceptual Design Report: Volume 1 -- Physics & Detector

The Super $τ$-Charm facility (STCF) is an electron-positron collider proposed by the Chinese particle physics community. It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of $0.5\times 10^{35}{\rm cm}^{-2}{\rm s}^{-1}$ or higher. The STCF will produce a data sample about a factor of 100 larger than that by the present $τ$-Charm factory -- the BEPCII, providing a unique platform for exploring the asymmetry of matter-antimatter (charge-parity violation), in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions, as well as searching for exotic hadrons and physics beyond the Standard Model. The STCF project in China is under development with an extensive R\&D program. This document presents the physics opportunities at the STCF, describes conceptual designs of the STCF detector system, and discusses future plans for detector R\&D and physics case studies.

hep-ex↗
arXiv2023

Measurement of $e^{+}e^{-}\rightarrowηJ/ψ$ Cross Section from $\sqrt{s}=$ 3.808 GeV to 4.951 GeV

Using data samples with an integrated luminosity of 22.42 fb$^{-1}$ collected by the BESIII detector operating at the BEPCII storage ring, we measure the cross sections of the $e^{+}e^{-}\rightarrow\etaJ/ψ$ process at center-of-mass energies from 3.808 to 4.951 GeV. Three structures are observed in the line shape of the measured cross sections. A maximum-likelihood fit with $ψ(4040)$, two additional resonances, and a non-resonant component is performed. The mass and width of the first additional state are $(4219.7\pm2.5\pm4.5) \rm{MeV}/\rm{c}^2$ and $(80.7\pm4.4\pm1.4) \rm{MeV}$, respectively, consistent with the $ψ(4230)$. For the second state, the mass and width are $(4386\pm13\pm17) \rm{MeV}/\rm{c}^2$ and $(177\pm32\pm13) \rm{MeV}$, respectively, consistent with the $ψ(4360)$. The first uncertainties are statistical and the second ones are systematic. The statistical significance of $ψ(4040)$ is $8.0σ$ and those for $ψ(4230)$ and $ψ(4360)$ are more than $10.0σ$.

hep-ex↗
arXiv2023

First measurement of $ΛN$ inelastic scattering with $Λ$ from $e^{+} e^{-} \rightarrow J/ψ\to Λ\barΛ$

Using an $e^+ e^-$ collision data sample of $(10087 \pm 44)\times10^6 ~J/ψ$ events taken at the center-of-mass energy of $3.097~\rm{GeV}$ by the BESIII detector at the BEPCII collider, the process $Λ+N \rightarrow Σ^+ + X$ is studied for the first time employing a novel method. The $Σ^{+}$ hyperons are produced by the collisions of $Λ$ hyperons from $J/ψ$ decays with nuclei in the material of the BESIII detector. The total cross section of $Λ+ ^{9}{\rm Be} \rightarrow Σ^+ + X$ is measured to be $σ= (37.3 \pm 4.7 \pm 3.5)~{\rm mb}$ at $Λ$ beam momenta within $[1.057, 1.091]~{\rm GeV}/c$, where the uncertainties are statistical and systematic, respectively. This analysis is the first study of $Λ$-nucleon interactions at an $e^+ e^-$ collider, providing information and constraints relevant for the strong-interaction potential, the origin of color confinement, the unified model for baryon-baryon interactions, and the internal structure of neutron stars.

nucl-ex↗
arXiv2023

Updated measurements of the M1 transition $ψ(3686) \to γη_{c}(2S)$ with $η_{c}(2S) \to K \bar{K} π$

Based on a data sample of $(27.08 \pm 0.14 ) \times 10^8~ψ(3686)$ events collected with the BESIII detector at the BEPCII collider, the M1 transition $ψ(3686) \to γη_{c}(2S)$ with $η_{c}(2S) \to K\bar{K}π$ is studied, where $K\bar{K}π$ is $K^{+} K^{-} π^{0}$ or $K_{S}^{0}K^{\pm}π^{\mp}$. The mass and width of the $η_{c}(2S)$ are measured to be $(3637.8 \pm 0.8 (\rm {stat}) \pm 0.2 (\rm {syst}))$ MeV/$c^{2}$ and $(10.5 \pm 1.7 (\rm {stat}) \pm 3.5 (\rm {syst}))$ MeV, respectively. The product branching fraction $\mathcal{B}\left(ψ(3686) \rightarrow γη_{c}(2 S)\right) \times \mathcal{B}(η_{c}(2 S) \rightarrow K \bar{K} π)$ is determined to be $(0.97 \pm 0.06 (\rm {stat}) \pm 0.09 (\rm {syst})) \times 10^{-5}$. Using $\mathcal{BR}(η_{c}(2S)\to K\bar{K}π)=(1.86^{+0.68}_{-0.49})\%$, we obtain the branching fraction of the radiative transition to be $\mathcal{BR}(ψ(3686) \to γη_{c}(2S)) = (5.2 \pm 0.3 (\rm {stat}) \pm 0.5 (\rm {syst}) ^{+1.9}_{-1.4} (extr)) \times 10^{-4}$, where the third uncertainty is due to the quoted $\mathcal{BR}(η_{c}(2S) \to K\bar{K}π)$.

hep-ex↗
arXiv2023

Observation of $J/ψ$ decays to $e^{+}e^{-}e^{+}e^{-}$ and $e^{+}e^{-}μ^{+}μ^{-}$

Using a data sample of $4.481\times 10^8 ψ^\prime$ events collected with the BESIII detector, we report the first observation of the four-lepton-decays $J/ψ\to e^+e^-e^+e^-$ and $J/ψ\to e^+e^-μ^+μ^-$ utilizing the process $ψ^\prime\to π^+π^- J/ψ$. The branching fractions are determined to be $[5.48\pm0.31~(\rm stat)\pm0.45~(\rm syst)]\times 10^{-5}$ and $[3.53~\pm0.22~(\rm stat)\pm0.13~(\rm syst)]\times 10^{-5}$, respectively. The results are consistent with theoretical predictions. No significant signal is observed for $J/ψ\to μ^+μ^-μ^+μ^-$, and an upper limit on the branching fraction is set at $1.6\times 10^{-6}$ at the 90$\%$ confidence level. A CP asymmetry observable is constructed for the first two channels, which is measured to be $(-0.012\pm0.054\pm0.010)$ and $(0.062\pm0.059\pm0.006)$, respectively. No evidence for CP violation is observed in this process.

hep-ex↗
arXiv2023

Measurements of the absolute branching fractions of $Ω^-$ decays and test of the $ΔI = 1/2$ rule

Based on a data set of $(27.12\pm0.10)\times 10^8$ $ψ(3686)$ events collected at the BESIII experiment, the absolute branching fractions of the three dominant $Ω^-$ decays are measured to be $\mathcal{B}_{Ω^- \to Ξ^0 π^-} = (25.03\pm0.44\pm0.53)\%$, $\mathcal{B}_{Ω^- \to Ξ^- π^0} = (8.43\pm0.52\pm0.28)\%$, and $\mathcal{B}_{Ω^- \to ΛK^-} = (66.3\pm0.8\pm2.0)\%$, where the first and second uncertainties are statistical and systematic, respectively. The ratio between $\mathcal{B}_{Ω^- \to Ξ^0 π^-}$ and $\mathcal{B}_{Ω^- \to Ξ^- π^0}$ is determined to be $2.97\pm0.19\pm0.11$, which is in good agreement with the PDG value of $2.74\pm0.15$, but greater by more than four standard deviations than the theoretical prediction of 2 obtained from the $ΔI = 1/2$ rule.

hep-ex↗
arXiv2023

Measurement of $e^{+}e^{-}\toϕη'$ cross sections at center-of-mass energies from 3.508 to 4.951 GeV and search for the decay $ψ(3770)\toϕη'$

The cross sections of the $e^{+}e^{-}\toϕη'$ process at center-of-mass energies from 3.508 to 4.951 GeV are measured with high precision using 26.1 fb$^{-1}$ data collected with the BESIII detector operating at the BEPCII storage ring. The cross sections are of the order of a few picobarn, and decrease as the center-of-mass energy increases as $s^{-n/2}$ with $n=4.35\pm 0.14$. This result is in agreement with the Nambu-Jona-Lasinio model prediction of $n=3.5\pm 0.9$. In addition, the charmless decay $ψ(3770)\toϕη'$ is searched for by fitting the measured cross sections, yet no significant signal is observed. The upper limit of ${\cal B}(ψ(3770)\toϕη')$ at the 90\% confidence level is determined to be $2.3\times 10^{-5}$.

hep-ex↗
arXiv2023

Search for the semileptonic decays $D^+_s \to K_1(1270)^0 e^+ν_e$ and $D^+_s \to b_1(1235)^0 e^+ν_e$

By analyzing 7.33\,fb$^{-1}$ of $e^+e^-$ collision data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, we search for the semileptonic decays $D^+_s \to K_1(1270)^0 e^+ν_e$ and $D^+_s \to b_1(1235)^0 e^+ν_e$ for the first time. No significant signals are observed for either decay mode. The upper limits on the (product) branching fractions are determined to be ${\mathcal B}[D^+_s \to K_1(1270)^0 e^+ν_e] < 4.1\times 10^{-4}$ and ${\mathcal B}[D^+_s \to b_1(1235)^0 e^+ν_e]\cdot {\mathcal B}[b_1(1235)^0\to ωπ^0] < 6.4\times 10^{-4}$ at 90\% confidence level.

hep-ex↗
arXiv2023

Novel method to extract the femtometer structure of strange baryons using the vacuum polarization effect

One of the fundamental goals of particle physics is to gain microscopic understanding of the strong interaction. Electromagnetic form factors quantify the structure of hadrons in terms of charge and magnetization distributions. While the nucleon structure has been investigated extensively, data on hyperons is still scarce. It has recently been demonstrated that electron-positron annihilations into hyperon-antihyperon pairs provide a powerful tools to investigate their inner structure. We present a novel method useful for hyperon-antihyperon pairs of different types which exploits the cross section enhancement due to the vacuum polarization effect at the $J/ψ$ resonance. Using the 10 billion $J/ψ$ events collected with the BESIII detector, this allows a thorough determination of the hyperon structure . The result is essentially a precise snapshot of a $\barΛΣ^0$~($Λ\barΣ^0$) pair in the making, encoded in the form factor ratio and the phase. Their values are measured to be $R = 0.860\pm0.029({\rm stat.})\pm0.010({\rm syst.})$, $ΔΦ_1=(1.011\pm0.094({\rm stat.})\pm0.010({\rm syst.}))~\rm rad$ for $\barΛΣ^0$ and $ΔΦ_2=(2.128\pm0.094({\rm stat.})\pm0.010({\rm syst.}))~\rm rad$ for $Λ\barΣ^0$, respectively. Furthermore, charge-parity (CP) breaking is investigated for the first time in this reaction and found to be consistent with CP symmetry.

hep-ex↗
arXiv2023

Search for a scalar partner of the $X(3872)$ via $ψ(3770)$ decays into $γηη'$ and $γπ^{+}π^{-}J/ψ$

Using a data sample corresponding to an integrated luminosity of 2.93 fb$^{-1}$ collected at a center-of-mass energy of 3.773~GeV with the BESIII detector at the BEPCII collider, we search for a scalar partner of the $X(3872)$, denoted as $X(3700)$, via $ψ(3770)\to γηη'$ and $γπ^{+}π^{-}J/ψ$ processes. No significant signals are observed and the upper limits of the product branching fractions $ {\cal B}(ψ(3770)\toγX(3700))\cdot {\cal B}(X(3700)\to ηη')$ and ${\cal B}(ψ(3770)\toγX(3700))\cdot {\cal B}(X(3700)\toπ^{+}π^{-}J/ψ)$ are determined at the 90\% confidence level, for the narrow $X(3700)$ with a mass ranging from 3710 to 3740 MeV/$c^2$, which are from 0.8 to 1.8 $(\times 10^{-5})$ and 0.9 to 3.4 $(\times 10^{-5})$, respectively.

hep-ex↗
arXiv2023

A coupled-channel analysis of the $X(3872)$ lineshape with BESIII data

We perform a study of the $X(3872)$ lineshape using the data samples of $e^+e^-\toγX(3872)$, $X(3872)\to D^0\bar{D}^0 π^0$ and $π^+π^- J/ψ$ collected with the BESIII detector. The effects of the coupled-channels and the off-shell $D^{*0}$ are included in the parameterization of the lineshape. The lineshape mass parameter is obtained to be $M_{X}=(3871.63\pm 0.13^{+0.06}_{-0.05})$ MeV. Two poles are found on the first and second Riemann sheets corresponding to the $D^{*0}\bar{D}^0$ branch cut. The pole location on the first sheet is much closer to the $D^{*0}\bar{D}^0$ threshold than the other, and is determined to be $7.04\pm0.15^{+0.07}_{-0.08}$ MeV above the $D^0\bar{D}^0π^0$ threshold with an imaginary part $-0.19\pm0.08^{+0.14}_{-0.19}$ MeV.

hep-ex↗
arXiv2023

Observation of $χ_{cJ}\to Λ\bar Λη$

By analyzing $(448.1\pm2.9)\times10^6$ $ψ(3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decays of $χ_{cJ} \to Λ\bar Λη$ ($J=0$, 1 and 2) are observed for the first time with statistical significances of $13.9σ$, $6.7σ$, and $8.2σ$, respectively. The product branching fractions of $ψ(3686)\toγχ_{cJ}$ and $χ_{cJ}\to Λ\bar Λη$ are measured. Dividing by the world averages of the branching fractions of $ψ(3686)\toγχ_{cJ}$, the branching fractions of $χ_{cJ}\to Λ\bar Λη$ decays are determined to be $(2.31\pm0.30\pm0.21)\times10^{-4}$, $(5.86\pm1.38\pm0.68)\times10^{-5}$, and $(1.05\pm0.21\pm0.15)\times10^{-4}$ for $J=0$, 1 and 2, respectively, where the first uncertainties are statistical and the second systematic.

hep-ex↗