435 Search Results

The ATLAS experiment at the Large Hadron Collider explores the use of modern neural networks for a multi-dimensional calibration of its calorimeter signal defined by clusters of topologically connected cells (topo-clusters). The Bayesian neural network (BNN) approach not only yields a continuous and smooth calibration function that improves performance relative to the standard calibration but also provides uncertainties on the calibrated energies for each topo-cluster. The results obtained by using a trained BNN are compared to the standard local hadronic calibration and to a calibration provided by training a deep neural network. The uncertainties predicted by the BNN are interpretedmore » in the context of a fractional contribution to the systematic uncertainties of the trained calibration. They are also compared to uncertainty predictions obtained from an alternative estimator employing repulsive ensembles.« less

Using $(2712.4\pm 14.3)\times {10}^6$ $\psi \left(3686\right)$ events collected with the BESIII detector at BEPCII, a partial wave analysis of the decay $\psi \left(3686\right)\to \varphi \eta {\eta }^{\prime }$ is performed with the covariant tensor approach. In addition to the established states $h_1(1900$ ) and $\varphi \left(2170\right)$ , an axial-vector state with a mass near $more »$ 2.3     GeV / c 2 is observed for the first time. Its mass and width are measured to be $2316\pm 9_{\mathrm{stat}}\pm 30_{\mathrm{syst}}\mathrm{MeV}/c^2$ and $89\pm 15_{\mathrm{stat}}\pm 26_{\mathrm{syst}}\mathrm{MeV}$ , respectively. The product branching fractions of $\mathcal{B}\left[\psi \right(3686)\to X(2300\left){\eta }^{\prime }\right]\mathcal{B}\left[X\right(2300)\to \varphi \eta ]$ and $\mathcal{B}\left[\psi \right(3686)\to X(2300\left)\eta \right]\mathcal{B}\left[X\right(2300)\to \varphi {\eta }^{\prime }]$ are determined to be $(4.8\pm {1.3}_{\mathrm{stat}}\pm {0.7}_{\mathrm{syst}})\times {10}^{-6}$ and $(2.2\pm {0.7}_{\mathrm{stat}}\pm {0.7}_{\mathrm{syst}})\times {10}^{-6}$ , respectively. The branching fraction $\mathcal{B}\left[\psi \right(3686)\to \varphi \eta {\eta }^{\prime }]$ is measured for the first time to be ( $3.14\pm 0.17_{\mathrm{stat}}\pm 0.24_{\mathrm{syst}})\times {10}^{-5}$ . The first uncertainties are statistical and the second are systematic. Published by the American Physical Society 2025« less

Based on $(2712.4\pm 14.1)\times {10}^6$ $\psi \left(3686\right)$ decays collected with the BESIII detector, we have observed, for the first time, the hadronic decays of S- and P-wave charmonium states into $2\left({\pi }^{+}{\pi }^{-}\right)\eta$ via radiative transitions from $\psi \left(3686\right)$ . The branching fraction of the decay ${\eta }_c\left(1S\right)\to 2({\pi }^{+}{\pi }^{more »}$ − ) η has a significant dependence on the interference pattern between ${\eta }_c\left(1S\right)$ and non- ${\eta }_c\left(1S\right)$ processes. We measure it in both the destructive and constructive interference scenarios for the first time. The mass and width of the ${\eta }_c\left(1S\right)$ are measured to be $M=(2984.14\pm 0.13\pm 0.38)\mathrm{MeV}/c^2$ and $\mathrm{\Gamma }=(28.82\pm 0.11\pm 0.82)\mathrm{MeV}$ , respectively. Clear signals for the decays of the ${\chi }_{cJ}(J=0,1,2)$ and the ${\eta }_c\left(2S\right)$ to $2\left({\pi }^{+}{\pi }^{-}\right)\eta$ are also observed for the first time, and the corresponding branching fractions are measured. The ratio of the branching fractions between the ${\eta }_c\left(2S\right)$ and ${\eta }_c\left(1S\right)$ decays is significantly lower than the theoretical prediction, which might suggest different dynamics in their decays. Published by the American Physical Society 2025« less

The inclusive cross sections of prompt $J/\psi$ and $\psi \left(3686\right)$ production are measured at center-of-mass energies from 3.808 to 4.951 GeV. The dataset used is $22{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected with the BESIII detector operating at the BEPCII storage ring. The results obtained are in agreement with the previous BESIII measurements of exclusive $J/\psi$ and $\psi \left(3686\right)$ production. The average values obtainedmore » for the cross sections measured in the center-of-mass energy ranges from 4.527 to 4.951 GeV for $J/\psi$ and from 4.843 to 4.951 GeV for $\psi \left(3686\right)$ , where the impact of known resonances is negligible, are $14.0\pm 1.7\pm 3.1\mathrm{pb}$ and $15.3\pm 3.0\mathrm{pb}$ , respectively. For $J/\psi$ , the first and the second uncertainties are statistical and systematic, respectively. For $\psi \left(3686\right)$ , the uncertainty is total. These values are useful for testing charmonium production models. Published by the American Physical Society 2025« less

We measure the Born cross section for the reaction 𝑒⁺⁢𝑒⁻→ 𝜂⁢ℎ_𝑐 from $$\sqrt{𝑠}$$ = 4.129 to 4.600 GeV using datasets collected by the BESIII detector running at the BEPCII collider. A resonant structure in the cross-section line shape near 4.200 GeV is observed with a statistical significance of 7⁢𝜎. The parameters of this resonance are measured to be 𝑀 = 4188.8 ± 4.7 ± 8.0 MeV/𝑐² and Γ = 49 ± 16 ± 19 MeV, where the first uncertainties are statistical and the second systematic.

Based on $(10.09\pm 0.04)\times {10}^{9}J/\psi$ events collected with the BESIII detector operating at the BEPCII collider, a partial wave analysis of the decay $J/\psi \to \varphi {\pi }^0\eta$ is performed. We observe for the first time two new structures on the $\varphi \eta$ invariant mass distribution, with significances exceeding $27\sigma$ and $13\sigma$ ; the first with $J^{\mathrm{PC}}=1^{more »}$ + − , mass $\mathrm{M}=(1908\pm 6(\mathrm{stat}\left){}_{-4}^{+8}\right(\mathrm{sys}\left)\right)\mathrm{MeV}/c^2$ , and width $\mathrm{\Gamma }=(175\pm 13(\mathrm{stat}\left){}_{-16}^{+7}\right(\mathrm{sys}\left)\right)\mathrm{MeV}$ , the second with $J^{\mathrm{PC}}=1^{--}$ , mass $\mathrm{M}=(1992\pm 12(\mathrm{stat}\left){}_{-6}^{+15}\right(\mathrm{sys}\left)\right)\mathrm{MeV}/c^2$ , and width $\mathrm{\Gamma }=(132\pm 22(\mathrm{stat}\left){}_{-4}^{+17}\right(\mathrm{sys}\left)\right)\mathrm{MeV}$ . These measurements provide important input for the strangeonium spectrum. In addition, the $f_0\left(980\right)-a_0(980{)}^0$ mixing signal in $J/\psi \to \varphi f_0\left(980\right)\to \varphi a_0(980{)}^0$ and the corresponding electromagnetic decay $J/\psi \to \varphi a_0(980{)}^0$ are measured with improved precision, providing crucial information to understand the nature of $a_0(980{)}^0$ and $f_0\left(980\right)$ . Published by the American Physical Society 2024« less

We report the precise measurements of the cross section of $e^{+}{e}^{-}\to \text{hadrons}$ at center-of-mass energies from 3.645 to 3.871 GeV. We thereby perform the most precise study of the cross sections and find a complex system composed of three resonances of $\mathcal{R}\left(3760\right)$ , $\mathcal{R}\left(3780\right)$ , and $\mathcal{R}\left(3810\right)$ . For the first time, we measure the $\mathcal{R}\left(3810\right)$ electronicmore » width to be $(19.4\pm 7.4\pm 12.1)\mathrm{eV}$ . For the $\mathcal{R}\left(3760\right)$ resonance, we measure the mass to be $(3751.9\pm 3.8\pm 2.8)\mathrm{MeV}/c^2$ , the total width to be $(32.8\pm 5.8\pm 8.7)\mathrm{MeV}$ , and the electronic width to be $(184\pm 75\pm 86)\mathrm{eV}$ . For the $\mathcal{R}\left(3780\right)$ resonance, we measure its mass to be $(3778.7\pm 0.5\pm 0.3)\mathrm{MeV}/c^2$ , total width to be $(20.3\pm 0.8\pm 1.7)\mathrm{MeV}$ , and electronic width to be $(265\pm 67\pm 83)\mathrm{eV}$ . Forty-seven years ago, the $\psi \left(3770\right)$ resonance was discovered, and was subsequently interpreted as the $1{}^3{D}_1$ -wave dominant state of charmonium. However, our analysis of the total-hadron cross sections indicates that the $\psi \left(3770\right)$ is not a single state, but a complex system composed of the $\mathcal{R}\left(3760\right)$ , $\mathcal{R}\left(3780\right)$ , and $\mathcal{R}\left(3810\right)$ resonances. Among these, we interpret the $\mathcal{R}\left(3780\right)$ is a resonance dominated by the $1{}^3{D}_1$ charmonium state. Published by the American Physical Society 2024« less

Geological CO₂ sequestration (GCS) can help mitigate global warming and enhance methane recovery from coal beds. However, few studies have linked the effects of CO₂ to surface chemistry changes controlling wetting behavior in deep coal beds. Contact angles (CAs) of CO₂/N₂-high volatile bituminous coal-water systems were measured under different temperatures and pressures. The surface chemistry and physical structure of coals were characterized to investigate changes in physicochemical properties and their relations with wettability after reactions. For N₂ treatment, the time-dependence of static and dynamic CAs were insignificant, ranging within 4°. For gaseous CO₂ treatment, the static CAs and the averagemore » advancing angles increased slightly. With supercritical (sc) CO₂, both the static and dynamic CAs increased significantly, and θ_adv changed to intermediate-wet (92°). Reactions with minerals exposed to scCO₂ resulted in greater surface roughness and heterogeneity, greater contact angle hysteresis and more surface sites occupied by scCO₂ rather than H₂O. Increases in hydrophobic functional groups and decreases in hydrophilicity were shown by FTIR spectra, reflecting the shedding of polar oxygen-containing functional groups, reduction of hydrogen bonds, and increasing percentage of hydrocarbons. XRD patterns obtained following scCO₂-treatment showed that crystallite growth and molecular polymerization were higher toward graphite-like. The calculated structural parameters of functional groups and crystallites both showed elevated coal rank. Changes in crystallite structure, notably higher carbon content and decreased negative surface charge, are unfavorable for water-wetting. Finally, this study contributes to understanding surface chemistry changes responsible for decreased wettability during CO₂-enhanced coal bed methane recovery and GCS in coal reservoirs.« less

Using $7.33{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data collected by the BESIII detector at center-of-mass energies in the range of $\sqrt{s}=4.128–4.226\mathrm{GeV}$ , we search for the rare decays $D_s^{+}\to h^{+}\left(h^0\right)e^{+}$ e − , where $h$ represents a kaon or pion. By requiring the $e^{+}{e}^{-}$ invariant mass to be consistent with a $\varphi \left(1020\right)$ , $0.98<M\left(e^{+}{e}^{-}\right)<1.04\mathrm{GeV}/c^2$ , the decay $D_s^{+}\to {\pi }^{+}\varphi$ , $\varphi \to e^{+}{e}^{-}$ is observed with a statistical significance of $7.8\sigma$ , and evidence for the decay $D_s^{+}\to {\rho }^{+}\varphi$ , $\varphi \to e^{+}{e}^{-}$ is found for the first time with a statistical significance of $4.4\sigma$ . The decay branching fractions are measured to be $\mathcal{B}(D_s^{+}\to {\pi }^{+}\varphi ,\varphi \to e^{+}{e}^{-})=(1.17_{-0.21}^{+0.23}\pm 0.03)\times {10}^{-5}$ , and $\mathcal{B}(D_s^{+}\to {\rho }^{+}\varphi ,\varphi \to e^{+}{e}^{-})=(2.44_{-0.62}^{+0.67}\pm 0.16)\times {10}^{-5}$ , where the first uncertainties are statistical and the second systematic. No significant signals for the three four-body decays of $D_s^{+}\to {\pi }^{+}{\pi }^0{e}^{+}{e}^{-}$ , $D_s^{+}\to K^{+}{\pi }^0{e}^{+}{e}^{-}$ , and $D_s^{+}\to K_S^0{\pi }^{+}{e}^{+}{e}^{-}$ are observed. For $D_s^{+}\to {\pi }^{+}{\pi }^0{e}^{+}{e}^{-}$ , the $\varphi$ mass region is vetoed to minimize the long-distance effects. The 90% confidence level upper limits set on the branching fractions of these decays are in the range of $\left(7.0–8.1\right)\times {10}^{-5}$ . Published by the American Physical Society 2024« less

Abstract By analyzinge⁺e⁻annihilation data corresponding to an integrated luminosity of 2.93 fb⁻¹collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, the first observation of the semileptonic decays$$$$ {D}^0\to {K}_S^0{\pi}^{-}{\pi}^0{e}^{+}{\nu}_e $$$$ $D^0\to K_S^0{\pi }^{-}{\pi }^0{e}^{+}{\nu }_e$ and$$$$ {D}^{+}\to {K}_S^0{\pi}^{+}{\pi}^{-}{e}^{+}{\nu}_e $$$$ $D^{+}\to K_S^0{\pi }^{+}{\pi }^{-}{e}^{+}{\nu }_e$ is reported. In the hypothesis that all events correspond toK₁(1270) decays, the branching fractions are measured to be$$$$ \mathcal{B}\left({D}^0\to {K}_1{(1270)}^{-}\left(\to {K}_S^0{\pi}^{-}{\pi}^0\right){e}^{+}{\nu}_e\right)=\left({1.69}_{-0.46}^{+0.53}\pm 0.15\right)\times {10}^{-4} $$$$ $B\left(D^0\to K_1{\left(1270\right)}^{-}\left(\to K_S^{more »}\right)\right)$ 0 π− π0 e+ ν e = 1.69 − 0.46 + 0.53 ± 0.15 ×10 − 4 and$$$$ \mathcal{B}\left({D}^{+}\to {\overline{K}}_1{(1270)}^0\left(\to {K}_S^0{\pi}^{+}{\pi}^{-}\right){e}^{+}{\nu}^e\right)=\left({1.47}_{-0.40}^{+0.45}\pm 0.14\right)\times {10}^{-4} $$$$ $B\left(D^{+}\to {\overline{K}}_1{\left(1270\right)}^0\left(\to K_S^0{\pi }^{+}{\pi }^{-}\right)e^{+}{\nu }^e\right)=\left({1.47}_{-0.40}^{+0.45}\pm 0.14\right)\times {10}^{-4}$ with statistical significance of 5.4σand 5.6σ, respectively. When combined with measurements of theK₁(1270)→ K⁺π⁻πdecays, the absolute branching fractions are determined to be$$$$ \mathcal{B}\left({D}^0\to {K}_1{(1270)}^{-}{e}^{+}{\nu}_e\right)=\left({1.08}_{-0.13-0.10}^{+0.14+0.08}\pm 0.21\right)\times {10}^{-3} $$$$ $B\left(D^0\to K_1{\left(1270\right)}^{-}{e}^{+}{\nu }_e\right)=\left({1.08}_{-0.13-0.10}^{+0.14+0.08}\pm 0.21\right)\times {10}^{-3}$ and$$$$ \mathcal{B}\left({D}^{+}\to {\overline{K}}_1{(1270)}^0{e}^{+}{\nu}_e\right)=\left({1.70}_{-0.23}^{+0.26}\pm 0.13\pm 0.35\right)\times {10}^{-3} $$$$ $B\left(D^{+}\to {\overline{K}}_1{\left(1270\right)}^0{e}^{+}{\nu }_e\right)=\left({1.70}_{-0.23}^{+0.26}\pm 0.13\pm 0.35\right)\times {10}^{-3}$ . The first and second uncertainties are statistical and systematic, respectively, and the third uncertainties originate from the assumed branching fractions of theK₁(1270)→ Kππdecays.« less