423 Search Results

Using $\left(2712\pm 14\right)\times {10}^6$ $\psi \left(2S\right)$ events collected with the BESIII detector at the BEPCII collider, we search for the decays ${\eta }_c\left(2S\right)\to \omega \omega$ and ${\eta }_c\left(2S\right)\to \omega \varphi$ via the process $\psi \left(2S\right)\to \gamma {\eta }_c\left(2S\right)$ . No statistically significant signals are observed. The upper limits of their product branching fractions at the 90% confidence level are determined to be $\mathcal{B}\left(\psi \right(2S)\to \gamma {\eta }_c(2S),{\eta }_c(2S)\to \omega \omega )<1.04\times {10}^{-6}$ and $\mathcal{B}\left(\psi \right(2S)\to \gamma {\eta }_c(2S),{\eta }_c(2S)\to \omega \varphi )<1.85\times {10}^{-7}$ , respectively. We also update the branching fractions of ${\chi }_{cJ}\to \omega \omega$ and ${\chi }_{cJ}\to \omega \varphi$ via the $\psi \left(2S\right)\to \gamma {\chi }_{cJ}$ transition. Their branching fractions are determined to be $\mathcal{B}({\chi }_{c0}\to \omega \omega )=(10.66\pm 0.11\pm 0.57)\times {10}^{-4}$ , $\mathcal{B}({\chi }_{c1}\to \omega \omega )=(6.43\pm 0.07\pm 0.31)\times {10}^{-4}$ , $\mathcal{B}({\chi }_{c2}\to \omega \omega )=(8.75\pm 0.08\pm 0.42)\times {10}^{-4}$ , $\mathcal{B}({\chi }_{c0}\to \omega \varphi )=(1.18\pm 0.03\pm 0.07)\times {10}^{-4}$ , $\mathcal{B}({\chi }_{c1}\to \omega \varphi )=(2.04\pm 0.15\pm 0.11)\times {10}^{-5}$ , and $\mathcal{B}({\chi }_{c2}\to \omega \varphi )=(9.58\pm 1.07\pm 0.76)\times {10}^{-6}$ , where the first uncertainties are statistical and the second are systematic. Published by the American Physical Society 2025

Utilizing a dataset of $6.7{\mathrm{fb}}^{-1}$ from electron-positron collisions recorded by the BESIII detector at the BEPCII storage ring, a search is conducted for the processes $e^{+}{e}^{-}\to \varphi {\chi }_{c0}$ and $\varphi {\eta }_{c2}\left(1D\right)$ across center-of-mass energies from 4.47 to 4.95 GeV. In the absence of any significant signals, upper limits are set. These include limits on the dressed cross sections for $e^{+}{e}^{-}\to \varphi {\chi }_{c0}$ , as well as the product of the dressed cross section for $e^{+}{e}^{-}\to \varphi {\eta }_{c2}\left(1D\right)$ and a sum of five branching fractions. Furthermore, the product of the electronic width of $Y\left(4660\right)$ and the branching fraction of the $Y\left(4660\right)\to \varphi {\chi }_{c0}$ , denoted as ${\mathrm{\Gamma }}_{e^{+}{e}^{-}}^{Y\left(4660\right)}{\mathcal{B}}_{Y\left(4660\right)\to \varphi {\chi }_{c0}}$ , is determined to be $<0.35\mathrm{eV}$ at the 90% confidence level. Published by the American Physical Society 2025

Studies are performed of the Cabibbo-favored decay ${\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }{K}_S^0{K}^{+}$ and the singly Cabibbo-suppressed decay ${\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }{K}_S^0{\pi }^{+}$ , based on a sample of $e^{+}{e}^{-}$ collision data, corresponding to an integrated luminosity of $4.5{\mathrm{fb}}^{-1}$ , accumulated at center-of-mass energies between 4599.53 MeV and 4698.82 MeV with the BESIII detector. The decay ${\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }{K}_S^0{\pi }^{+}$ is observed for the first time. The branching fractions of ${\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }{K}_S^0{K}^{+}$ and ${\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }{K}_S^0{\pi }^{+}$ are measured to be $(3.04\pm 0.30\pm 0.16)\times {10}^{-3}$ and $(1.73\pm 0.27\pm 0.10)\times {10}^{-3}$ , respectively, where the first uncertainties are statistical and the second are systematic. These results correspond to the most precise measurement of these quantities for both decays. Evidence of a $K^{*+}$ contribution in the ${\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }{K}_S^0{\pi }^{+}$ decay is found with a statistical significance of $4.71\sigma$ . The branching fraction of ${\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }{K}^{*+}$ is calculated under three possible interference scenarios, with the significance increasing to $5.03\sigma$ when interference is taken into account. Published by the American Physical Society 2025

Using $7.9\mathrm{f}{\mathrm{b}}^{-1}$ of $e^{+}{e}^{-}$ collision data collected at $\sqrt{s}=3.773\mathrm{GeV}$ with the BESIII detector at the BEPCII collider, we search for the massless dark photon with the flavor-changing neutral current processes $D^0\to \omega {\gamma }^{\prime }$ and $D^0\to \gamma {\gamma }^{\prime }$ for the first time. No significant signals are observed, and the upper limits at the 90% confidence level on the massless dark photon branching fraction are set to be $1.1\times {10}^{-5}$ and $2.0\times {10}^{-6}$ for $D^0\to \omega {\gamma }^{\prime }$ and $D^0\to \gamma {\gamma }^{\prime }$ , respectively. These results provide the most stringent constraint on the new physics energy scale associated with $cu{\gamma }^{\prime }$ coupling in the world, with the new physics energy scale related parameter $|\mathbb{C}{|}^2+|{\mathbb{C}}_5{|}^2<8.2\times {10}^{-17}{\mathrm{GeV}}^{-2}$ at the 90% confidence level. Published by the American Physical Society 2025

The first study of $J/\psi \varphi$ production in diffractive processes in proton-proton collisions is presented. The study is based on an LHCb dataset recorded at center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $5{\mathrm{fb}}^{-1}$ . The data disfavor a nonresonant $J/\psi \varphi$ production but are consistent with a resonant model including several resonant states observed previously only in $B^{+}\to J/\psi \varphi K^{+}$ decays. The ${\chi }_{c0}\left(4500\right)$ state is observed with a significance over $6\sigma$ and the ${\chi }_{c1}\left(4274\right)$ is confirmed with a significance of more than $4\sigma$ . © 2025 CERN, for the LHCb Collaboration 2025 CERN

Using $(27.12\pm 0.14)\times {10}^8$ $\psi \left(2S\right)$ events collected by the BESIII detector operating at BEPCII, we search for the decay ${\eta }_c\left(2S\right)\to p\overline{p}$ via the process $\psi \left(2S\right)\to \gamma {\eta }_c\left(2S\right)$ and only find a signal with a significance of $1.7\sigma$ . The upper limit of the product branching fraction at the 90% confidence level is determined to be $\mathcal{B}\left(\psi \right(2S)\to \gamma {\eta }_c(2S\left)\right)\times \mathcal{B}\left({\eta }_c\right(2S)\to p\overline{p})<2.4\times {10}^{-7}$ . The branching fractions of ${\chi }_{cJ}\to p\overline{p}(J=0,1,2)$ are also measured to be $\mathcal{B}({\chi }_{c0}\to p\overline{p})=(2.51\pm 0.02\pm 0.08)\times {10}^{-4}$ , $\mathcal{B}({\chi }_{c1}\to p\overline{p})=(8.16\pm 0.09\pm 0.25)\times {10}^{-4}$ , and $\mathcal{B}({\chi }_{c2}\to p\overline{p})=(8.33\pm 0.09\pm 0.22)\times {10}^{-4}$ , where the first uncertainty is statistical and the second systematic. Published by the American Physical Society 2025

We perform the first amplitude analysis of $D_s^{+}\to {\pi }^{+}{\pi }^{+}{\pi }^{-}{\pi }^0$ decays based on data samples of electron-positron collisions recorded with the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, corresponding to an integrated luminosity of $7.33{\mathrm{fb}}^{-1}$ . We report the observation of $D_s^{+}\to f_0\left(980\right)\rho (770{)}^{+}$ with a statistical significance greater than $10\sigma$ and determine the branching fractions $\mathcal{B}(D_s^{+}\to {\pi }^{+}{\pi }^{+}{\pi }^{-}{\pi }^0{|}_{\mathrm{non}-\eta })=(2.04\pm 0.08_{\mathrm{stat}}\pm 0.05_{\mathrm{syst}})\%$ and $\mathcal{B}(D_s^{+}\to \eta {\pi }^{+})=(1.56\pm 0.09_{\mathrm{stat}}\pm 0.04_{\mathrm{syst}})\%$ . Moreover, we measure the relative branching fraction between $\varphi \to {\pi }^{+}{\pi }^{-}{\pi }^0$ and $\varphi \to K^{+}{K}^{-}$ to be $\left[\mathcal{B}\right(\varphi \left(1020\right)\to {\pi }^{+}{\pi }^{-}{\pi }^0)/\mathcal{B}(\varphi \left(1020\right)\to K^{+}{K}^{-}\left)\right]=0.230\pm 0.014_{\mathrm{stat}}\pm 0.010_{\mathrm{syst}}$ ., which deviates from the world average value by more than $4\sigma$ . Published by the American Physical Society 2025

We present a study of the semileptonic decay $D^0\to {\pi }^{-}{\pi }^0{e}^{+}{\nu }_e$ using an $e^{+}{e}^{-}$ annihilation data sample of $7.93{\mathrm{fb}}^{-1}$ collected at the center-of-mass energy of 3.773 GeV with the BESIII detector. The branching fraction of $D^0\to \rho (770{)}^{-}{e}^{+}{\nu }_e$ is measured to be $(1.439\pm 0.033(\mathrm{stat})\pm 0.027(\mathrm{syst}\left)\right)\times {10}^{-3}$ , which is a factor 1.6 more precise than previous measurements. By performing an amplitude analysis, we measure the hadronic form-factor ratios of $D^0\to \rho (770{)}^{-}{e}^{+}{\nu }_e$ at $q^2=0$ assuming the single-pole-dominance parametrization: $r_V=V\left(0\right)/A_1\left(0\right)=1.548\pm 0.079\left(\mathrm{stat}\right)\pm 0.041\left(\mathrm{syst}\right)$ and $r_2=A_2\left(0\right)/A_1\left(0\right)=0.823\pm 0.056\left(\mathrm{stat}\right)\pm 0.026\left(\mathrm{syst}\right)$ . Published by the American Physical Society 2024

We report the first amplitude analyses of the decays $D^0\to {\pi }^{+}{\pi }^{-}\eta$ and $D^{+}\to {\pi }^{+}{\pi }^0\eta$ using a data sample taken with the BESIII detector at the center-of-mass energy of 3773 MeV, corresponding to an integrated luminosity of $7.9{\mathrm{fb}}^{-1}$ . The contribution from the process $D^{0(+)}\to a_0(980{)}^{+}{\pi }^{-\left(0\right)}$ is significantly larger than the $D^{0(+)}\to a_0(980{)}^{-\left(0\right)}{\pi }^{+}$ contribution. The ratios $\mathcal{B}(D^0\to a_0(980{)}^{+}{\pi }^{-})/\mathcal{B}(D^0\to a_0\left(980{)}^{-}{\pi }^{+}\right)$ and $\mathcal{B}(D^{+}\to a_0(980{)}^{+}{\pi }^0)/\mathcal{B}(D^{+}\to a_0\left(980{)}^0{\pi }^{+}\right)$ are measured to be ${7.5}_{-0.8\mathrm{stat}}^{+2.5}\pm {1.7}_{\mathrm{syst}}$ and $2.6\pm {0.6}_{\mathrm{stat}}\pm {0.3}_{\mathrm{syst}}$ , respectively. The measured $D^0$ ratio disagrees with the theoretical predictions by orders of magnitudes, thus implying a substantial contribution from final-state interactions. Published by the American Physical Society 2024

Using the $e^{+}{e}^{-}$ collision data collected with the BESIII detector operating at the BEPCII collider, at center-of-mass energies from the threshold to 4.95 GeV, we present precise measurements of the cross section for the process $e^{+}{e}^{-}\to D_s^{+}{D}_s^{-}$ using a single-tag method. The resulting cross section line shape exhibits several new structures, thereby offering an input for a future coupled-channel analysis and model tests, which are critical to understand vector charmonium-like states with masses between 4 and 5 GeV. Published by the American Physical Society 2024