arXiv subjects

J. Cheng

Publications and source records attributed to J. Cheng.

At least 91 records · Page 5Linked to original sources

arXiv2026

Measurement of the branching fractions of $χ_{cJ} \to π^{+}π^{-}π^{0}π^{0}$ via $ψ(3686) \to γχ_{cJ}$

Using $(2712.4\pm14.3)\times 10^6$ $ψ(3686)$ events collected with the BESIII detector operating at BEPCII, the branching fractions of $χ_{cJ}\toπ^+π^-π^0π^0$ ($J=0,~1,~2$) are measured via the radiative transition $ψ(3686)\toγχ_{cJ}$. The results are $\mathcal{B}(χ_{c0} \to π^{+}π^{-}π^{0}π^{0}) = (3.10 \pm 0.01 \pm 0.14) \times 10^{-2}$, $\mathcal{B}(χ_{c1} \to π^{+}π^{-}π^{0}π^{0}) = (1.16 \pm 0.01 \pm 0.05) \times 10^{-2}$, and $\mathcal{B}(χ_{c2} \to π^{+}π^{-}π^{0}π^{0}) = (1.92 \pm 0.01 \pm 0.08) \times 10^{-2}$, where the first uncertainties are statistical and the second systematic. The dominant intermediate states are found to be $χ_{cJ}\toρ^+ρ^-$. These results supersede the previous most precise measurements and provide significantly improved precision.

hep-ex↗

arXiv2026

First measurement of the absolute branching fractions of $Σ^+$ nonleptonic decays and test of the $ΔI = 1/2$ rule

Based on $(10087 \pm 44) \times 10^6$ $J/ψ$ events collected by the BESIII detector at the center-of-mass energy $\sqrt{s} = 3.097$ GeV, the first absolute measurement of the branching fractions for the decays $Σ^+ \to p π^0$ and $Σ^+ \to n π^+$ is performed. The branching fractions are determined to be $B_{Σ^+ \to p π^0} = (49.79 \pm 0.06 \pm 0.22)\%$ and $B_{Σ^+ \to n π^+} = (49.87 \pm 0.05 \pm 0.29)\%$, where the first uncertainties are statistical and the second systematic. These results show significant deviations from the PDG values for both decays, with differences of 4.4$σ$ for $Σ^+ \to p π^0$ and 3.4$σ$ for $Σ^+ \to n π^+$. Furthermore, the $ΔI = 1/2$ rule is tested in nonleptonic $Σ^\pm$ decays. The observed results deviate from zero by more than $5σ$, indicating the presence of the $ΔI = 3/2$ transition amplitude in the $Σ$ hyperon decays.

hep-ex↗

arXiv2026

Measurement of the CKM angle $γ$ in $B^{\pm} \rightarrow D(\rightarrow K^{0}_{\rm S} h^{\prime+}h^{\prime-})h^{\pm}$ decays with a novel approach

A measurement of the CKM angle $γ$ and related strong-phase parameters is performed using a novel, model-independent approach in ${B^{\pm}\rightarrow D(\rightarrow K^{0}_{\rm S} h^{\prime+}h^{\prime-}) h^{\pm}}$ decays, where $h^{(\prime)} \equiv π, K$. The analysis uses a joint data sample of electron-positron collisions collected by the BESIII experiment at the Beijing Electron-Positron Collider II during 2010--2011 and 2021--2022, corresponding to an integrated luminosity of 8 fb$^{-1}$, and proton-proton collisions collected by the LHCb experiment at the Large Hadron Collider during 2011--2018, corresponding to an integrated luminosity of 9 fb$^{-1}$. The two datasets are analyzed simultaneously by applying per-event weights based on the amplitude variation over the $D$-decay phase space to enhance the sensitivity to $C\!P$-violating observables. The CKM angle $γ$ is determined to be $γ= (71.3\pm 5.0)^{\circ}$, which constitutes the most precise single measurement to date.

hep-ex↗

arXiv2026

Precise measurement of the CKM angle $γ$ with a novel approach

A measurement of the CKM angle $γ$ is performed by applying a novel, unbinned, model-independent approach to datasets of electron-positron collisions collected by the BESIII experiment and proton-proton collisions by the LHCb experiment, corresponding to integrated luminosities of 8 fb$^{-1}$ and 9 fb$^{-1}$, respectively. The $C\!P$-violating phase $γ$ is determined from ${B^{\pm}\rightarrow D(\rightarrow K_{\rm S}^{0} h^{\prime+}h^{\prime-}) h^{\pm}}$ decays in LHCb data, where $h^{(\prime)}$ is either a pion or kaon, while the corresponding strong-phase parameters are measured using doubly tagged ${D\rightarrow K_{\rm S/L}^0 h^{\prime+} h^{\prime-}}$ decays in the quantum-correlated $D\overline{D}$ system present in BESIII data. A joint fit to both datasets, which allows for a simultaneous determination of the associated $C\!P$-violating observables and strong-phase parameters, yields ${γ= (71.3\pm 5.0)^{\circ}}$. The result is the most precise to date and consistent with previous measurements and world averages.

hep-ex↗

arXiv2026

Emergent superconductivity at 16.3 K in an altermagnetic candidate Na$_{2-x}$V$_2$Se$_2$O with broken inversion symmetry

Altermagnets (AMs), characterized by zero net magnetization and momentum-dependent spin splitting, are anticipated to hold significant potential for generating multiple exotic and uncommon superconducting states. However, superconductivity has not yet been realized in AMs to date. Recently, two-dimensional (2D) V$_2$Ch$_2$O (Ch = Se, Te) monolayers, as well as AV$_2$Ch$_2$O (A = K, Rb, Cs) crystals containing [V$_2$Ch$_2$O]$^{δ-}$ building layers, have been predicted and/or demonstrated to be promising altermagnetic materials. Our preliminary attempts to explore superconductivity in these materials by applying pressure or chemical doping were unsuccessful. Here we report the discovery of superconductivity at a relatively high transition temperature of ~ 16.3 K in a newly synthesized layered compound, Na$_{2-x}$V$_2$Se$_2$O, a variant of AV$_2$Ch$_2$O. In this structure, the [V$_2$Ch$_2$O]$^{δ-}$ layers are interspersed with double layers of Na$^+$ instead of a single layer of A$^+$, with sodium sites being only half-filled. This new family of layered vanadium oxychalcogenides, lacking inversion symmetry, represents an intriguing platform for exploring altermagnetic superconductors, and holds the potential to reveal novel phenomena, such as topological states, van Hove singularities, and finite-momentum superconductivity. Furthermore, this material acts as a "bridge" between the cuprate/nickelate and iron-pnictide high temperature superconductors, providing new hope and opportunity to expand the category of layered superconductors with higher critical temperatures (T$_c$) and enhancing our understanding of the underlying mechanisms in these systems.

cond-mat.supr-con↗

arXiv2026

Amplitude analysis and branching fraction measurement of the decay $D^0 \to K^+K^-π^0π^0$

An amplitude analysis of the singly Cabibbo-suppressed decay $D^0 \to K^+ K^- π^0 π^0$ is performed, for the first time, to determine the relative magnitudes and phases of different intermediate processes. The analysis uses $e^+e^-$ collision data collected with the BESIII detector at the center-of-mass energy 3.773~GeV corresponding to an integrated luminosity of 20.3 $\rm fb^{-1}$. The absolute branching fraction of $D^0 \to K^+ K^- π^0 π^0$ is measured to be \BF. The dominant intermediate process is $D^0 \to K^{*}(892)^+K^{*}(892)^-$, with a branching fraction of $(2.79 \pm 0.13_{\rm{stat.}} \pm 0.11_{\rm{syst.}}) \times 10^{-3}$. Amplitude analysis reveals that the $D^0 \to K^{*}(892)^+K^{*}(892)^-$ decay is S-wave dominant. The longitudinal polarization fraction of $D^0 \to K^{*}(892)^+ K^{*}(892)^-$ is measured to be $0.468\pm0.046_{\rm{stat.}}\pm0.011_{\rm{syst.}}$.

hep-ex↗

arXiv2026

Measurements of branching fractions of $Λ_{c}^{+}\toΣ^{0}K_{S}^{0}π^{+}$ and $Λ_{c}^{+}\toΣ^{0}K_{S}^{0}K^{+}$

Based on a data sample corresponding to an integrated luminosity of 6.4~fb$^{-1}$ of $e^+e^-$ annihilation and collected with the BESIII detector at 13 center-of-mass energy points ranging between 4.600~GeV and 4.950~GeV, we report the first observation of the singly Cabibbo-suppressed decay $Λ_c^+ \to Σ^0 K_S^0 π^+$ with a statistical significance of 5.9$σ$. The branching fraction is determined to be $\mathcal{B}(Λ_c^+ \to Σ^0 K_S^0 π^+) = (0.58 \pm 0.14_{\rm stat.} \pm 0.04_{\rm syst.}) \times 10^{-3}$. In addition, the decay $Λ_c^+\toΣ^0K_{S}^{0} K^+$ has also been investigated, and the first evidence for this decay is obtained with a statistical significance of 3.7$σ$.

hep-ex↗

arXiv2026

Observation of $D_s^+ \to a_0(980)^+f_0(500)$ in the Amplitude Analysis of $D_s^+ \to π^+ π^0 π^0 η$

We report the first observation of the decay $D_s^+ \to π^+π^0π^0η$ in a data set corresponding to an integrated luminosity of 7.33 fb$^{-1}$, collected in $e^+e^-$ collisions by the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV. An unexpectedly large branching fraction $\mathcal{B}( D_s^+ \to a_0(980)^+ f_0(500), a_0(980)^+ \to π^+η, f_0(500)\to π^0π^0) = (0.98 \pm 0.16_{\rm{stat.}} \pm 0.22_{\rm{syst.}})\%$ is measured with a significance exceeding $10σ$, offering new constraints on the internal structure of light scalar mesons. The dominant intermediate process is $D_s^+ \to a_1(1260)^+η, a_1(1260)^+\to ρ(770)^+π^0$ with a branching fraction of $(1.77 \pm 0.21_{\rm stat.} \pm 0.12_{\rm syst.})\%$. The isospin symmetry has been validated to the decays of $a_1(1260)^+\to ρ(770)^0π^+$ and $a_1(1260)^+\to ρ(770)^+π^0$. Moreover, the measured $\mathcal{B}(D_s^+\to π^+π^0π^0η|_{\rm{non}-η^\prime})=(2.97 \pm 0.23_{\rm stat.} \pm 0.14_{\rm sys.})$ reduces the undetected $D_s^+ \to ηX$ decay branching fractions to (0.1 $\pm$ 3.1)\%.

hep-ex↗

arXiv2026

Search for a massless particle beyond the Standard Model in the $Ξ^0\toΛ+ \text{invisible}$ decay

A search for a massless beyond-standard-model particle is performed in the decay $Ξ^{0}\toΛ+\text{invisible}$ using $(1.0087 \pm 0.0044)\times 10^{10}$ $J/ψ$ events collected with the BESIII detector at the BEPCII collider. No significant signal is observed and the upper limit on the branching fraction $\mathcal{B}(Ξ^{0}\toΛ+\text{invisible})$ is set to be $2.3 \times 10^{-4}$ at the $90\%$ confidence level. This is the first search for a flavor-changing neutral current process with missing energy in $Ξ^0$ decays. Throughout this paper, charge-conjugate processes are always implied.

hep-ex↗

arXiv2026

Pulse shape simulation for the reduced charge collection layer in p-type high-purity germanium detectors

$P$-type high-purity germanium (HPGe) detectors are widely used across many scientific domains, and current data analysis methods have served well in many use cases. However, applications like low-background experiments that search for rare physics, such as dark matter, neutrinoless double-beta decay, and coherent elastic neutrino-nucleus scattering, could profit a lot from a more detailed understanding of the detector response close to the surface. The outer $n^+$ electrode of the $p$-type HPGe detector forms a layer with reduced charge collection, and events originating here can be a critical background source in such experiments. If the difference in detector pulse shape between detector surface and bulk events is known, it can be used to identify and veto these background events. However, a faithful simulation of the detector response in this surface region is difficult and has not been available as a standard method so far. We present a novel three-dimensional pulse shape simulation method for this reduced charge collection (RCC) layer. We have implemented this method as a new feature in the open-source simulation package \emph{SolidStateDetectors$.$jl} and show a validation of the numerical simulation results with analytical calculations. An experimental study using a $p$-type HPGe detector also validates our approach. The current implementation supports $p$-type HPGe detectors of fairly arbitrary geometry, but is easily adaptable to $n$-type detectors by adjusting the impurity density profile of the layer. It should also be adaptable to other semiconductor materials in a straightforward fashion.

physics.ins-det↗

arXiv2026

An improved measurement of $η^\prime\rightarrow e^{+}e^{-}ω$

Using a sample of $(10087 \pm 44) \times 10^{6}$ $J/ψ$ events collected with the BESIII detector, an improved measurement of the decay $η^{\prime}\rightarrow e^{+}e^{-}ω$, with $ω\rightarrowπ^{+}π^{-}π^{0}$ and $π^{0}\rightarrowγγ$ is performed. The branching fraction is determined to be $\mathcal{B}(η^{\prime}\rightarrow e^{+}e^{-}ω) = (1.79 \pm 0.09 \pm 0.12) \times 10^{-4}$, where the first uncertainty is statistical and the second is systematic. This result is consistent with the previous measurement and is obtained with significantly improved precision. Furthermore, the first measurement of the transition form factor cutoff parameter for this decay is reported, with $Λ^{-1} = (2.92 \pm 0.83 \pm 0.15)~\text{GeV}^{-1}$. These measurements provide valuable input for understanding the internal structure of the $η^{\prime}$ meson and testing theoretical models.

hep-ex↗

arXiv2026

Observation of charmonium sequential suppression in heavy-ion collisions at the Relativistic Heavy Ion Collider

We report measurements of charmonium sequential suppression in Ru+Ru and Zr+Zr collisions at $\sqrt{s_{\mathrm {NN}}}$ = 200 GeV with the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The inclusive yield ratio of $ψ$(2S) to J/$ψ$ as a function of transverse momentum is reported, along with the centrality dependence of the double ratio, defined as the $ψ$(2S) to J/$ψ$ ratio in heavy-ion collisions relative to that in $p$+$p$ collisions. In the 0-80% centrality class, the double ratio is found to be 0.41 $\pm$ 0.10 (stat) $\pm$ 0.03 (syst) $\pm$ 0.02 (ref), lower than unity with a significance of 5.6 standard deviations. This provides experimental evidence that $ψ$(2S) is significantly more suppressed than J/$ψ$ in heavy-ion collisions at RHIC. This sequential suppression pattern seems to increase from peripheral to central collisions, but with no significant dependence on the transverse momentum.

nucl-ex↗

arXiv2026

Measurement of Born Cross Sections for $e^+e^-\toΣ^-\barΣ^+$ at $\sqrt{s}=3.51-4.95$ GeV and Observation of $ψ(3770)\toΣ^-\barΣ^+$

Using $e^+e^-$ collision data corresponding to an integrated luminosity of 44 fb$^{-1}$ collected with the BESIII detector at the BEPCII collider, we report the first measurement of Born cross sections and effective form factors for $e^+e^-\toΣ^-\barΣ^+$ at centre-of-mass energies between 3.51 and 4.95 GeV. With a fit to the $\sqrt{s}$-dependent dressed cross sections, the decay $ψ(3770)\toΣ^-\barΣ^+$ is observed for the first time with a significance of 5.5$σ$, including systematic uncertainties. Upper limits at the 90\% confidence level on the product of the branching fraction and the electronic partial width are provided for other possible charmonium(-like) states. The ratios of Born cross sections for the $Σ$ isospin-triplet states are determined and can be used to test the vector-meson-dominance model.

hep-ex↗

arXiv2026

Measurement of the singly Cabibbo-suppressed decay $Λ_c^+\to pη'$ with Deep Learning

Using $4.5$ fb$^{-1}$ of $e^+e^-$ collision data collected with the BESIII detector at center-of-mass energies from 4.600 to 4.699 GeV, we report a measurement of the singly Cabibbo-suppressed decay $Λ_c^+ \to pη'$ with the single-tag method. To effectively distinguish the signal from the large backgrounds, we exploit a deep-learning classifier built on a Transformer-based neural network. Extensive validation and uncertainty quantification are carried out. The $Λ^+_c\to pη'$ signal is observed with a statistical significance of $3.4 σ$. The ratio of branching fractions of $\mathcal{B}{Λ^+_c\to pη'}/\mathcal{B}{Λ^+_c\to pω}$= $0.55\pm 0.22_{\rm{stat.}} \pm 0.05_{\rm{syst.}}$ is obtained, where the first uncertainty is statistical and the second systematic.

hep-ex↗

arXiv2026

First observation of the $η_{c}\toΞ^{0} \barΞ^{0}$ decay

Using $(10087\pm 44)\times 10^6$ $J/ψ$ events collected with the BESIII detector at the BEPCII collider, we report the first observation of the decay $η_{c} \to Ξ^{0} \barΞ^{0}$. The interference between $J/ψ\toγη_c\toγΞ^0\barΞ^0$ and $J/ψ\toγΞ^0\barΞ^0|_{\rm non-resonance}$ is considered in the $Ξ^0 \barΞ^0$ mass spectrum fits. The branching fractions are measured to be $B(η_c \to Ξ^0 \barΞ^0)=(1.33 \pm 0.03 \pm 0.18) \times 10^{-3}$ for the constructive interference and $B(η_c \to Ξ^0 \barΞ^0)=(1.63 \pm 0.04 \pm 0.21) \times 10^{-3}$ for the destructive interference, where the first uncertainties are statistical and the second are systematic.

hep-ex↗

arXiv2026

Study of $\barΛ$-$p$ Annihilation into Light Mesons

The annihilation of $\barΛ$-$p$ into light mesons is studied using $(10.087\pm0.044)\times10^{9}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring. The $\barΛ$ baryons are produced in the process $J/ψ\rightarrowΛ\barΛ$ and interact with the protons in the hydrogen nuclei in the cooling oil of the beam pipe. The reactions $\barΛp\rightarrow K^+π^+π^-$ and $K^+2π^+2π^-$ are observed for the first time, evidence for the reaction $\barΛp\rightarrow K^0_S2π^+π^-$ is found, and no significant signals are seen for the reactions $\barΛp\rightarrow K^0_Sπ^+$, $K^+3π^+3π^-$ and $2K^+K^-$. The cross sections of these reactions are also measured at $P_{\barΛ}\approx 1.074$ GeV/$c$. Furthermore, no significant structures are observed in the combinations of the final state particles for these reactions. The annihilation of $\barΛ$-$p$ into light mesons presents the similar behavior as $\bar{n}$-$p$ reactions in this energy region. These new measurements will serve as important inputs for the theoretical understanding of the antihyperon-nucleon interaction, and further contribute to understanding antibaryon-baryon interaction in a unified perspective.

hep-ex↗

arXiv2026

Search for $ψ_0(4360)\rightarrow ηψ(2S)$ through the process $e^+e^- \rightarrow ηηψ(2S)$

Using data samples corresponding to an integrated luminosity of 0.9~fb$^{-1}$ collected with the BESIII detector operating at the BEPCII storage ring at the center-of-mass energies of 4.84, 4.92, and 4.95~GeV, we search for the exotic charmonium-like state with quantum numbers $J^{PC}=0^{--}$, $ψ_0(4360)$, in the process $e^+e^-\rightarrowηψ_0(4360)$ with $ψ_0(4360)\rightarrowηψ(2S)$. No significant signal of the $ψ_0(4360)$ resonance state is observed. Upper limits on $σ(e^+e^-\rightarrowηψ_0(4360))\cdot {B}(ψ_0(4360)\rightarrowηψ(2S))$ and $σ(e^+e^-\rightarrowηηψ(2S))$ at the 90\% confidence level are determined for each energy point.

hep-ex↗

arXiv2026

Energy Independence of the Collins Asymmetry in $p^{\uparrow}p$ Collisions

The STAR experiment reports new, high-precision measurements of the transverse single-spin asymmetries for $π^{\pm}$ within jets, namely the Collins asymmetries, from transversely polarized ${p^{\uparrow}p}$ collisions at $\sqrt{s}$ = 510 GeV. The energy-scaled distribution of jet transverse momentum, $x_{\mathrm{T}} = 2p_{\mathrm{T,jet}}/\sqrt s$, shows a remarkable consistency for Collins asymmetries of $π^{\pm}$ in jets between $\sqrt{s}$ = 200 GeV and 510 GeV. This indicates that the Collins asymmetries are nearly energy independent with, at most, a very weak scale dependence in $p^{\uparrow}p$ collisions. These results extend to high-momentum scales ($Q^2 \leq 3400$ GeV$^2$) and enable unique tests of evolution and universality in the transverse-momentum-dependent formalism, thus providing important constraints for the Collins fragmentation functions.

hep-ex↗