arXiv subjects

T. Chen

Publications and source records attributed to T. Chen.

At least 307 records · Page 17Linked to original sources

arXiv2024

Study of $e^+e^-\toωX(3872)$ and $γX(3872)$ from 4.66 to 4.95 GeV

Using data samples with an integrated luminosity of $4.5~\text{fb}^{-1}$ collected by the BESIII detector at center-of-mass energies ranging from 4.66 to 4.95 GeV, we study the processes of $e^+e^-\toωX(3872)$ and $e^+e^-\toγX(3872)$. With the $e^+e^-\toωX(3872)$ process, the branching fraction ratio $R\equiv\frac{\mathcal{B}(X(3872)\toγJ/ψ)}{\mathcal{B}(X(3872)\toπ^+π^- J/ψ)}$ is measured to be $0.38\pm0.20_\text{stat.}\pm0.01_\text{syst.}$ ($R< 0.83$ at 90\% confidence level). In addition, we measure the ratio of the average cross section of $e^+e^-\toωX(3872)$ to $e^+e^-\toωχ_{c1}(ωχ_{c2})$ to be $σ_{ωX(3872)}/σ_{ωχ_{c1}}~(σ_{ωX(3872)}/σ_{ωχ_{c2}})=5.2\pm1.0_\text{stat.}\pm1.9_\text{syst.}~ (5.5\pm1.1_\text{stat.}\pm2.4_\text{syst.})$. Finally, we search for the process of $e^+e^-\toγX(3872)$, and no obvious signal is observed. The upper limit on the ratio of the average cross section of $e^+e^-\toγX(3872)$ to $e^+e^-\toωX(3872)$ is set as $σ_{γX(3872)}/σ_{ωX(3872)}<0.23$ at 90\% confidence level.

hep-ex↗

arXiv2024

Study of the decay and production properties of $D_{s1}(2536)$ and $D_{s2}^*(2573)$

The $e^+e^-\rightarrow D_s^+D_{s1}(2536)^-$ and $e^+e^-\rightarrow D_s^+D^*_{s2}(2573)^-$ processes are studied using data samples collected with the BESIII detector at center-of-mass energies from 4.530 to 4.946~GeV. The absolute branching fractions of $D_{s1}(2536)^- \rightarrow \bar{D}^{*0}K^-$ and $D_{s2}^*(2573)^- \rightarrow \bar{D}^0K^-$ are measured for the first time to be $(35.9\pm 4.8\pm 3.5)\%$ and $(37.4\pm 3.1\pm 4.6)\%$, respectively. The measurements are in tension with predictions based on the assumption that the $D_{s1}(2536)$ and $D_{s2}^*(2573)$ are dominated by a bare $c\bar{s}$ component. The $e^+e^-\rightarrow D_s^+D_{s1}(2536)^-$ and $e^+e^-\rightarrow D_s^+D^*_{s2}(2573)^-$ cross sections are measured, and a resonant structure at around 4.6~GeV with a width of 50~MeV is observed for the first time with a statistical significance of $15σ$ in the $e^+e^-\rightarrow D_s^+D^*_{s2}(2573)^-$ process. It could be the $Y(4626)$ found by the Belle collaboration in the $D_s^+D_{s1}(2536)^{-}$ final state, since they have similar masses and widths. There is also evidence for a structure at around 4.75~GeV in both processes.

hep-ex↗

arXiv2024

Improved measurement of the semileptonic decay $D^+_{s}\to K^0 e^+ν_e$

Analyzing $e^+e^-$ collision data corresponding to an integrated luminosity of $7.33~\mathrm{fb}^{-1}$ collected at center-of-mass energies between 4.128 and 4.226~GeV with the BESIII detector, we measure the branching fraction of the semileptonic decay $D^+_{s}\to K^0 e^+ν_e$ to be $(2.98\pm0.23\pm0.12)\times10^{-3}$. The $D_s^+\to K^0$ hadronic form factor is determined from the differential decay rate of $D^+_s\to K^0 e^+ν_e$ to be $f^{K^0}_+(0)=0.636\pm0.049\pm0.013$. For both measurements, the first uncertainty is statistical and the second systematic. The branching fraction and form factor measurements are factors of 1.6 and 1.7 more precise than the previous world averages, respectively.

hep-ex↗

arXiv2024

Search for $X(1870)$ via the decay $J/ψ\to ωK^+ K^-η$

Using a sample of $(10087\pm 44)\times10^{6}$ $J/ψ$ events collected by the BESIII detector at the BEPCII collider, we search for the decay $X(1870)\to K^+ K^-η$ via the $J/ψ\to ωK^+ K^- η$ process for the first time. No significant $X(1870)$ signal is observed. The upper limit on the branching fraction of the decay $ J/ψ\to ωX(1870) \toωK^+ K^- η$ is determined to be $9.55\times 10^{-7}$ at the $90\%$ confidence level. In addition, the branching faction $B(J/ψ\toωK^+ K^- η)$ is measured to be $(3.33\pm0.02(\rm{stat.})\pm 0.12(\rm{syst.}))\times 10^{-4}$.

hep-ex↗

arXiv2024

Observation of $η_{c}$(1S, 2S) and $χ_{cJ}$ decays to 2$(π^{+}π^{-})η$ via $ψ$(3686) radiative transitions

Based on $2.7 \times 10^9~ψ(3686)$ decays collected with the BESIII detector, the radiative decay $ψ(3686)\to\gamma2(π^{+}π^{-})η$ is investigated to measure properties of S- and P-wave charmonium states. The branching fraction of the decay $η_{c}(1S) \to 2(π^{+}π^{-})η$, which is found to have a strong dependence on the interference pattern between $η_c(1S)$ and non-$η_c(1S)$ processes, is measured in both destructive and constructive interference scenarios for the first time. The mass and width of the $η_{c}(1S)$ are measured to be $M=(2984.14 \pm 0.13 \pm 0.38)$ MeV/$c^{2}$ and $Γ=(28.82 \pm 0.11 \pm 0.82)$ MeV, respectively. Clear signals for the decays of the $χ_{cJ}(J=0,1,2)$ and the $η_{c}(2S)$ to $2(π^{+}π^{-})η$ are also observed for the first time, and the corresponding branching fractions are measured. The ratio of the branching fractions between the $η_{c}(2S)$ and $η_{c}(1S)$ decays is significantly lower than the theoretical prediction, which might suggest different dynamics in their decays.

hep-ex↗

arXiv2024

Measurements of the branching fractions of the $P$-wave charmonium spin-singlet state $h_c(^1P_1) \to h^+ h^-π^0/η$

Based on $(2712.4\pm 14.3)\times10^{6}$ $ψ(3686)$ events, we investigate four hadronic decay modes of the $P$-wave charmonium spin-singlet state $h_c(^1P_1) \to h^+ h^- π^0/η$ ($h=π$ or $K$) via the process $ψ(3686) \to π^{0}h_c$ at BESIII. The $h_c \to π^+ π^- π^0$ decay is observed with a significance of 9.6$σ$ after taking into account systematic uncertainties. Evidences for $h_c \to K^+ K^- π^0$ and $h_c \to K^+ K^- η$ are found with significances of $3.5σ$ and $3.3σ$, respectively, after considering the systematic uncertainties. The branching fractions of these decays are measured to be $\mathcal{B}(h_c \to π^+ π^- π^0)=(1.36\pm0.16\pm0.14)\times10^{-3}$, $\mathcal{B}(h_c \to K^+ K^- π^0)=(3.26\pm0.84\pm0.36)\times10^{-4}$, and $\mathcal{B}(h_c \to K^+ K^- η)=(3.13\pm1.08\pm0.38)\times10^{-4}$, where the first uncertainties are statistical and the second are systematic. No significant signal of $h_c\toπ^+π^-η$ is found, and the upper limit of its decay branching fraction is determined to be $\mathcal{B}(h_c\toπ^+π^-η) < 4.0 \times 10^{-4}$ at 90% confidence level.

hep-ex↗

arXiv2024

Evidence of the Singly Cabibbo Suppressed decay $Λ_c^+\to pπ^0$

Evidence for the singly Cabibbo suppressed decay $Λ_c^+\to pπ^0$ is reported for the first time with a statistical significance of $3.7σ$ based on 6.0 $\mathrm{fb}^{-1}$ of $e^+e^-$ collision data collected at center-of-mass energies between 4.600 and 4.843 GeV with the BESIII detector at the BEPCII collider. The absolute branching fraction of $Λ_c^+\to pπ^0$ is measured to be $(1.56^{+0.72}_{-0.58}\pm0.20)\times 10^{-4}$. Combining with the branching fraction of $Λ_c^+\to nπ^+$, $(6.6\pm1.3)\times10^{-4}$, the ratio of the branching fractions of $Λ_c^+\to nπ^+$ and $Λ_c^+\to pπ^0$ is calculated to be $3.2^{+2.2}_{-1.2}$. As an important input for the theoretical models describing the decay mechanisms of charmed baryons, our result indicates that the non-factorizable contributions play an essential role and their interference with the factorizable contributions should not be significant. In addition, the absolute branching fraction of $Λ_c^+\to pη$ is measured to be $(1.63\pm0.31_{\rm stat}\pm0.11_{\rm syst}) \times10^{-3}$.

hep-ex↗

arXiv2024

Study of the decays $χ_{cJ} \rightarrow Λ\barΛϕ$

Based on $(2712.4 \pm 14.3) \times 10^{6}$ $ e^{+}e^{-}\toψ(3686)$ events collected with the BESIII detector operating at the BEPCII collider, we report the first evidence of $χ_{c0}\to Λ\bar Λϕ$ decays and the first observation of $χ_{c1,2}\to Λ\bar Λϕ$ decays, with significances of $4.5σ$, $11.3σ$ and $13.0σ$, respectively. The decay branching fractions of $χ_{c0,1,2}\to Λ\bar Λϕ$ are measured to be $( 2.99\pm1.24\pm0.19) \times 10^{-5}$, $(6.01\pm0.90\pm0.40 )\times 10^{-5}$, and $(7.13\pm0.81\pm0.36) \times 10^{-5}$, where the first uncertainties are statistical and the second systematic. No obvious enhancement near the $Λ\barΛ$ production threshold or excited $Λ$ state is found in the $Λϕ$ (or $\barΛϕ$) system.

hep-ex↗

arXiv2024

Measurement of absolute branching fractions of $D_s^+$ hadronic decays

Using $e^+ e^-$ collision data collected at the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, corresponding to an integrated luminosity of $7.33~{\rm fb}^{-1}$, we determine the absolute branching fractions of fifteen hadronic $D_s^{+}$ decays with a double-tag technique. In particular, we make precise measurements of the branching fractions $\mathcal{B}(D_s^+ \to K^+ K^- π^+)=(5.49 \pm 0.04 \pm 0.07)\%$, $\mathcal{B}(D_s^+ \to K_S^0 K^+)=(1.50 \pm 0.01 \pm 0.01)\%$ and $\mathcal{B}(D_s^+ \to K^+ K^- π^+ π^0)=(5.50 \pm 0.05 \pm 0.11)\%$, where the first uncertainties are statistical and the second ones are systematic. The \emph{CP} asymmetries in these decays are also measured and all are found to be compatible with zero.

hep-ex↗

arXiv2024

Determination of the number of $ψ(3686)$ events taken at BESIII

The number of $ψ(3686)$ events collected by the BESIII detector during the 2021 run period is determined to be $(2259.3\pm 11.1)\times 10^6$ by counting inclusive $ψ(3686)$ hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of $ψ(3686)$ events collected during the 2009 and 2012 run periods are updated to be $(107.7\pm0.6)\times 10^6$ and $(345.4\pm 2.6)\times 10^6$, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of $ψ(3686)$ events in the three data samples is $(2712.4\pm14.3)\times10^6$.

hep-ex↗

arXiv2024

VBFNLO: A parton level Monte Carlo for processes with electroweak bosons -- Manual for Version 3.0

VBFNLO is a flexible parton level Monte Carlo program for the simulation of vector boson fusion (VBF), QCD-induced single and double vector boson production plus two jets, and double and triple vector boson production (plus jet) in hadronic collisions at next-to-leading order (NLO) in the strong coupling constant, as well as Higgs boson plus two jet production via gluon fusion at the one-loop level. For the new version -- Version 3.0 -- several major enhancements have been included. An interface according to the Binoth Les Houches Accord (BLHA) has been added for all VBF and di/tri-boson processes including fully leptonic decays. For all dimension-8 operators affecting vector boson scattering (VBS) processes, a modified T-matrix unitarization procedure has been implemented. Several new production processes have been added, namely the VBS $Zγjj$ and $γγjj$ processes at NLO, $γγjj $, $WWj$ and $ZZj$ production at NLO including the loop-induced gluon-fusion contributions and the gluon-fusion one-loop induced $Φjjj$ ($Φ$ is a CP-even or CP-odd scalar boson) process at LO, retaining the full top-mass dependence. Finally, the code has been parallelized using OpenMPI.

hep-ph↗

arXiv2024

HERMES: Gamma Ray Burst and Gravitational Wave counterpart hunter

Gamma Ray Bursts (GRBs) bridge relativistic astrophysics and multi-messenger astronomy. Space-based gamma/X-ray wide field detectors have proven essential to detect and localize the highly variable GRB prompt emission, which is also a counterpart of gravitational wave events. We study the capabilities to detect long and short GRBs by the High Energy Rapid Modular Ensemble of Satellites (HERMES) Pathfinder (HP) and SpIRIT, namely a swarm of six 3U CubeSats to be launched in early 2025, and a 6U CubeSat launched on December 1st 2023. We also study the capabilities of two advanced configurations of swarms of >8 satellites with improved detector performances (HERMES Constellations). The HERMES detectors, sensitive down to ~2-3 keV, will be able to detect faint/soft GRBs which comprise X-ray flashes and high redshift bursts. By combining state-of-the-art long and short GRB population models with a description of the single module performance, we estimate that HP will detect ~195^{+22}_{-21} long GRBs (3.4^{+0.3}_{-0.8} at redshift z>6) and ~19^{+5}_{-3} short GRBs per year. The larger HERMES Constellations under study can detect between ~1300 and ~3000 long GRBs per year and between ~160 and ~400 short GRBs per year, depending on the chosen configuration, with a rate of long GRBs above z>6 between 30 and 75 per year. Finally, we explore the capabilities of HERMES to detect short GRBs as electromagnetic counterparts of binary neutron star (BNS) mergers detected as gravitational signals by current and future ground-based interferometers. Under the assumption that the GRB jets are structured, we estimate that HP can provide up to 1 (14) yr^{-1} joint detections during the fifth LIGO-Virgo-KAGRA observing run (Einstein Telescope single triangle 10 km arm configuration). These numbers become 4 (100) yr^{-1}, respectively, for the HERMES Constellation configuration.

astro-ph.HE↗

arXiv2024

Study of the decays $χ_{cJ}\toΛ\barΛω$

Using $(27.12\pm 0.14)\times10^{8}$ $ψ(3686)$ events collected with the BESIII detector, we present the first observation of the decays $χ_{cJ}\toΛ\barΛω$, where $J=0, 1, 2$, with statistical significances of $11.7 σ, 11.2 σ$, and $11.8 σ$. The branching fractions of these decays are determined to be $\mathcal{B}(χ_{c0}\toΛ\barΛω)=({2.37 \pm 0.22 \pm 0.23}) \times 10^{-4}$, $\mathcal{B}(χ_{c1}\toΛ\barΛω)=({1.01 \pm 0.10 \pm 0.11}) \times 10^{-4}$, and $\mathcal{B}(χ_{c2}\toΛ\barΛω)=({1.40 \pm 0.13 \pm 0.17}) \times 10^{-4}$, where the first uncertainties are statistical and the second are systematic. We observe no clear intermediate structures.

hep-ex↗

arXiv2024

Precision measurement of the branching fraction of \boldmath $J/ψ\rightarrow K^+K^-$ via $ψ(2S)\rightarrow π^+π^-J/ψ$

Using a sample of $448.1 \times 10^6$ $ψ(2S)$ events collected with the BESIII detector, we perform a study of the decay $J/ψ\rightarrow K^+K^-$ via $ψ(2S)\rightarrow π^+π^-J/ψ$. The branching fraction of $J/ψ\rightarrow K^+K^-$ is determined to be $\mathcal{B}_{K^+K^-}=(3.072\pm 0.023({\rm stat.})\pm 0.050({\rm syst.}))\times 10^{-4}$, which is consistent with previous measurements but with significantly improved precision.

hep-ex↗

arXiv2024

First study of antihyperon-nucleon scattering $\barΛp\rightarrow\barΛp$ and measurement of $Λp\rightarrowΛp$ cross section

Using $(10.087\pm0.044)\times10^{9}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring, the processes $Λp\rightarrowΛp$ and $\barΛp\rightarrow\barΛp$ are studied, where the $Λ/\barΛ$ baryons are produced in the process $J/ψ\rightarrowΛ\barΛ$ and the protons are the hydrogen nuclei in the cooling oil of the beam pipe. Clear signals are observed for the two reactions. The cross sections in $-0.9\leq\rm{cos}θ_{Λ/\barΛ}\leq0.9$ are measured to be $σ(Λp\rightarrowΛp)=(12.2\pm1.6_{\rm{stat}}\pm1.1_{\rm{sys}})$ mb and $σ(\barΛ p\rightarrow\barΛ p)=(17.5\pm2.1_{\rm{stat}}\pm1.6_{\rm{sys}})$ mb at the $Λ/\barΛ$ momentum of $1.074$ GeV/$c$ within a range of $\pm0.017$ GeV/$c$, where the $θ_{Λ/\barΛ}$ are the scattering angles of the $Λ/\barΛ$ in the $Λp/\barΛp$ rest frames. Furthermore, the differential cross sections of the two reactions are also measured, where there is a slight tendency of forward scattering for $Λp\rightarrowΛp$, and a strong forward peak for $\barΛp\rightarrow\barΛp$. We present an approach to extract the total elastic cross sections by extrapolation. The study of $\barΛp\rightarrow\barΛp$ represents the first study of antihyperon-nucleon scattering, and these new measurements will serve as important inputs for the theoretical understanding of the (anti)hyperon-nucleon interaction.

hep-ex↗

arXiv2024

Search for the leptonic decays $D^{+}\to e^+ν_e$ and $D^{+}\to μ^+ν_μ$

We present the first search for the leptonic decays $D^{*+}\to e^+ν_e$ and $D^{*+}\to μ^+ν_μ$ by analyzing a data sample of electron-positron collisions recorded with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, corresponding to an integrated luminosity of 6.32~fb$^{-1}$. No significant signal is observed. The upper limits on the branching fractions for $D^{*+}\to e^+ν_e$ and $D^{*+}\to μ^+ν_μ$ are set to be $1.1 \times 10^{-5}$ and $4.3 \times 10^{-6}$ at 90\% confidence level, respectively.

hep-ex↗

arXiv2024

Intertwined Charge and Spin Density Waves in a Topological Kagome Material

Using neutrons and x-rays we show the topological kagome antiferromagnet Mn$_3$Sn for $T<285$~K forms a homogeneous spin and charge ordered state comprising a longitudinally polarized spin density wave (SDW) with wavevector $\textbf{k}_β=k_β{\bf \hat{c}}$, a helical modulated version of the room temperature anti-chiral magnetic order with $\textbf{k}_χ=k_χ{\bf \hat{c}}$, and charge density waves with wave vectors $2\textbf{k}_β, 2\textbf{k}_χ$, and $\textbf{k}_β+\textbf{k}_χ$. Though $\textbf{k}_χ$ and $\textbf{k}_β$ coincide for $200~{\rm K}<T<230$~K, they exhibit distinct continuous $T-$dependencies before locking to commensurate values of $\textbf{k}_β = \frac{1}{12}\textbf{c}^{*}$ and $\textbf{k}_χ = \frac{5}{48}\textbf{c}^{*}$ at low$-T$. Density functional theory indicates this complex modulated state may be associated with the nesting of Fermi surfaces from correlated flat kagome bands, which host Weyl nodes that are annihilated as it forms.

cond-mat.str-el↗

arXiv2024

First Observation of a Three-Resonance Structure in $e^+e^-\rightarrow$Nonopen Charm Hadrons

We report the measurement of the inclusive cross sections for $e^+e^-$$\rightarrow$nOCH (where nOCH denotes non-open charm hadrons) with improved precision at center-of-mass (c.m.) energies from 3.645 to 3.871 GeV. We observe three resonances: $\mathcal R(3760)$, $\mathcal R(3780)$, and $\mathcal R(3810)$ with significances of $8.1σ$, $13.7σ$, and $8.8σ$, respectively. The $\mathcal R(3810)$ state is observed for the first time, while the $\mathcal R(3760)$ and $\mathcal R(3780)$ states are observed for the first time in the nOCH cross sections. Two sets of resonance parameters describe the energy-dependent line shape of the cross sections well. In set I [set II], the $\mathcal R(3810)$ state has mass $(3805.7 \pm 1.1 \pm 2.7)$ [$(3805.7 \pm 1.1 \pm 2.7)$] MeV/$c^2$, total width $(11.6 \pm 2.9 \pm 1.9)$ [$(11.5 \pm 2.8 \pm 1.9)$] MeV, and an electronic width multiplied by the nOCH decay branching fraction of $(10.9\pm 3.8\pm 2.5)$ [$(11.0\pm 3.4\pm 2.5)$] eV. In addition, we measure the branching fractions ${\mathcal B}[{\mathcal R}(3760)$$\rightarrow$nOCH$]=(25.2 \pm 16.1 \pm 30.4)\% [(6.4 \pm 4.8 \pm 7.7)\%]$ and ${\mathcal B}[\mathcal R(3780)$$\rightarrow$nOCH$]=(12.3 \pm 6.6 \pm 8.3)\% [(10.4 \pm 4.8 \pm 7.0)\%]$ for the first time. The $\mathcal R(3760)$ state can be interpreted as an open-charm (OC) molecular state, but containing a simple four-quark state component. The $\mathcal R(3810)$ state can be interpreted as a hadrocharmonium state.

hep-ex↗