arXiv subjects

M. H. Cai

Publications and source records attributed to M. H. Cai.

188 records · Page 11Linked to original sources

arXiv2025

Observation of the decay $ψ(3686)\rightarrow Σ^{0}\barΣ^{0}ω$

Using a dataset of $(27.12\pm 0.14)\times 10^{8}$ $ψ(3686)$ events collected by the BESIII detector operating at the BEPCII collider, we report the first observation of the decay $ψ(3686)\toΣ^{0}\barΣ^{0}ω$ with a statistical significance of 8.9$σ$. The measured branching fraction is $(1.24 \pm 0.16_{\textrm{stat}} \pm 0.11_{\textrm{sys}}) \times 10^{-5}$, where the first uncertainty is statistical and the second is systematic. Additionally, we investigate potential intermediate states in the invariant mass distributions of $Σ^{0}ω$, $\barΣ^{0}ω$ and $Σ^{0}\barΣ^{0}$. A hint of a resonance is observed in the invariant mass distribution of $M_{Σ^{0}(\barΣ^{0})ω}$, located around 2.06 GeV/$c^2$, with a significance of 2.5$σ$.

hep-ex↗

arXiv2025

Stringent test of $CP$ symmetry in $Σ^+$ hyperon decays

The non-leptonic two-body weak decays $Σ^{+} \to p π^{0}$ and $\barΣ^{-} \to \bar{p} π^{0}$ are investigated, utilizing $(1.0087\pm0.0044)\times10^{10}$ $J/ψ$ events and $(2.7124\pm0.0143)\times10^{9}$ $ψ(3686)$ events collected by BESIII experiment. The precision of the weak-decay parameters for the decays $Σ^{+} \to p π^{0}$ ($α_{0}$) and $\barΣ^{-} \to \bar{p} π^{0}$ ($\barα_{0}$) is improved by a factor of three compared to the previous world average. Furthermore, the quantum-entangled $Σ^{+}\barΣ^{-}$ system enables the most precise test of $CP$ symmetry for the decay $Σ^+\to pπ^0$, through the asymmetry observable $A_{CP}=(α_{0}+\barα_{0})/(α_{0}-\barα_{0})$ that is measured to be $-0.0118\pm0.0083_{\rm stat}\pm0.0028_{\rm syst}$. Assuming $CP$ conservation, the average decay parameter is determined to be ${\left< α_{\rm 0}\right>} = (α_0-\barα_0)/2=-0.9869\pm0.0011_{\rm stat}\pm0.0016_{\rm syst}$, which is the most precise measurement of the asymmetry decay parameters in baryon sectors. The angular dependence of the ratio of the polarization of the $Σ^+$ in both $J/ψ$ and $ψ(3686)$ decays is studied for the first time.

hep-ex↗

arXiv2025

Measurement of Born cross section of $e^+e^-\toΣ^0\barΣ^0$ at $\sqrt{s} = 3.50-4.95$ GeV

Using $e^+e^-$ collision data collected with the BESIII detector at the BEPCII collider at thirty-two center-of-mass energies from 3.50 to 4.95 GeV, corresponding to an integrated luminosity of 25 $\rm{fb^{-1}}$, we measure the Born cross section of the $e^+e^-\toΣ^0\barΣ^0$ reaction and the effective form factor. No significant charmonium(-like) state, i.e., $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, $ψ(4230)$, $ψ(4360)$, $ψ(4415)$, or $ψ(4660)$, decaying into the $Σ^0\barΣ^0$ final state is observed by fitting the $e^+e^- \to Σ^0\barΣ^0$ dressed cross section. The upper limits for the product of the branching fraction and the electronic partial width at the 90% confidence level are provided for each assumed charmonium(-like) state. In addition, the ratios of the Born cross section and the effective form factor between the $e^+e^-\toΣ^0\barΣ^0$ and the $e^+e^-\toΣ^+\barΣ^-$ reactions are provided, which can be used to validate the prediction of the vector meson dominance model.

hep-ex↗

arXiv2025

Measurement of the branching fractions of $D^+ \to K^+K^-π^+π^+π^-$, $ϕπ^+π^+π^-$, $K^0_SK^+π^+π^-π^0$, $K^0_SK^+η$, and $K^0_SK^+ω$ decays

Using $20.3~\mathrm{fb}^{-1}$ of $e^+e^-$ collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector operating at the BEPCII collider, the branching fractions of three hadronic charm meson decays, $D^+\to ϕπ^+π^+π^-$, $D^+\to K^0_SK^+π^+π^-π^0$, and $D^+\to K^0_SK^+ω$, are measured for the first time to be $(0.54\pm0.19\pm0.02)\times 10^{-4}$, $(2.51\pm0.34\pm0.14)\times 10^{-4}$, and $(2.02\pm0.35\pm0.10)\times 10^{-4}$, respectively. Futhermore, the branching fractions of $D^+\to K^+K^-π^+π^+π^-$ and $D^+\to K^0_SK^+η$ are measured with improved precision, yielding values of $(0.66\pm0.11\pm0.03)\times 10^{-4}$ and $(2.27\pm0.22\pm0.05)\times 10^{-4}$, respectively.

hep-ex↗

arXiv2025

Precision measurement of the branching fraction for the decay $ψ(2S)\rightarrowτ^{+}τ^{-}$

Using $(2259.3 \pm 11.1)\times10^{6}$ $ψ(2S)$ events acquired with the BESIII detector, the branching fraction of $ψ(2S)\rightarrowτ^{+}τ^{-}$ is measured with improved precision to be $\mathcal{B}_{ψ(2S)\rightarrowτ^{+}τ^{-}}=(3.240~\pm~0.023~\pm~0.081)\times 10^{-3}$, where the first and second uncertainties are statistical and systematic, respectively, which is consistent with the world average value within one standard deviation. This value, along with those for the branching fractions of the $ψ(2S)$ decaying into $e^{+}e^{-}$ and $μ^{+}μ^{-}$, is in good agreement with the relation predicted by the sequential lepton hypothesis. Combining the branching fraction values with the leptonic width of the $ψ(2S)$, the total width of the $ψ(2S)$ is determined to be (287 $\pm$ 9) keV.

hep-ex↗

arXiv2025

Search for the Cabibbo-suppressed decays $Λ_c^{+}\toΣ^0K^{+}π^{0}$ and $Λ_c^{+}\toΣ^0K^{+}π^{+}π^{-}$

Utilizing 4.5 $fb^-$ of $e^+e^-$ annihilation data collected at center-of-mass energies ranging from 4599.53 MeV to 4698.82 MeV by the BESIII detector at the BEPCII collider, we search for the singly Cabibbo-suppressed hadronic decays $Λ_{c}^{+}\toΣ^{0} K^{+}π^{0}$ and $Λ_{c}^{+}\toΣ^{0}K^{+}π^+π^-$ with a single-tag method. No significant signals are observed for both decays. The upper limits on the branching fractions at the $90\%$ confidence level are determined to be $5.0\times 10^{-4}$ for $Λ_{c}^{+}\toΣ^{0} K^{+}π^{0}$ and $6.5\times 10^{-4}$ for $Λ_c^{+}\toΣ^0K^{+}π^{+}π^{-}$.

hep-ex↗

arXiv2025

Search for the FCNC charmonium decay $J/ψ\to D^0 μ^+ μ^- + \text{c.c.}$

Based on a data sample of $(10087 \pm 44) \times 10^6$ $J/ψ$ events taken with the BESIII detector, we search for the flavor-changing neutral current charmonium decay $J/ψ\to D^{0} μ^{+} μ^{-} + \text{c.c.}$. No significant signal above the background is observed, and the upper limit on its branching fraction is set to be $\mathcal{B}(J/ψ\to D^{0}μ^{+}μ^{-} + \text{c.c.} ) < 1.1 \times 10^{-7}$ at the 90% confidence level. This marks the first search for a flavor-changing neutral current charmonium decay involving muons in the final state.

hep-ex↗

arXiv2021

Sensitivity improvement of Rydberg atom-based microwave sensing via electromagnetically induced transparency

A highly excited Rydberg atom via electromagnetically induced transparency with two color cascading lasers has extreme sensitivity to electric fields of microwave ranging from 100 MHz to over 1 THz. It can be used as susceptible atom-based microwave communication antennas where the carrier wave usually works exactly resonant to the transition between a pair of adjacent Rydberg states with large electric dipole moment. A technique of superheterodyne with a strong on-resonant local microwave oscillator is employed to induce considerable Autler-Townes splitting where the antennas has a highest dynamic response to another weak target signal microwave carrier. To further improve the sensitivity of atomic antenna in communication, we detune the carrier microwave frequency off resonance forming an asymmetrically optical splitting and fix the coupling laser frequency at the shoulder of the stronger one, and optimize the local field strength simultaneously. It gives a sensitivity of 12.50(04) $\rm{nVcm^{-1}\cdot Hz^{-1/2}}$. Its enhancement mechanism of sensitivity is also proved by a theoretical simulation.

physics.atom-ph↗