arXiv subjects

T. Guo

Publications and source records attributed to T. Guo.

At least 37 records · Page 2Linked to original sources

arXiv2024

Constraints on the Blazar-Boosted Dark Matter from the CDEX-10 Experiment

We report new constraints on light dark matter (DM) boosted by blazars using the 205.4 kg day data from the CDEX-10 experiment located at the China Jinping Underground Laboratory. Two representative blazars, TXS 0506+56 and BL Lacertae are studied. The results derived from TXS 0506+56 exclude DM-nucleon elastic scattering cross sections from $4.6\times 10^{-33}\ \rm cm^2$ to $1\times10^{-26}\ \rm cm^2$ for DM masses between 10 keV and 1 GeV, and the results derived from BL Lacertae exclude DM-nucleon elastic scattering cross sections from $2.4\times 10^{-34}\ \rm cm^2$ to $1\times10^{-26}\ \rm cm^2$ for the same range of DM masses. The constraints correspond to the best sensitivities among solid-state detector experiments in the sub-MeV mass range.

hep-ex↗

arXiv2015

Observation of $η^{\prime}\toωe^{+} e^{-}$

Based on a sample of \etapr mesons produced in the radiative decay $J/ψ\toγη^{\prime}$ in $1.31\times 10^9$ $J/ψ$ events collected with the BESIII detector, the decay $η^{\prime}\toωe^{+} e^{-}$ is observed for the first time, with a statistical significance of $8σ$. The branching fraction is measured to be $\mathcal{B}(η^{\prime}\toωe^{+} e^{-})=(1.97\pm0.34(\text{stat})\pm0.17(\text{syst}))\times10^{-4}$, which is in agreement with theoretical predictions. The branching fraction of $η^{\prime}\toωγ$ is also measured to be $(2.55\pm0.03(\text{stat})\pm0.16(\text{syst}))\times10^{-2}$, which is the most precise measurement to date, and the relative branching fraction $\frac{\mathcal{B}(η^{\prime}\to ωe^{+}e^{-})}{\mathcal{B}(η^{\prime}\to ωγ)}$ is determined to be $(7.71\pm1.34(\text{stat})\pm0.54(\text{syst}))\times10^{-3}$.

hep-ex↗

arXiv2015

Measurement of $y_{CP}$ in $D^0-\overline{D}^0$ oscillation using quantum correlations in $e^+e^-\to D^0\overline{D}^0$ at $\sqrt{s}$ = 3.773\,GeV

We report a measurement of the parameter $y_{CP}$ in $\ensuremath{D^0}\xspace-\ensuremath{\overline{D}^{0}}\xspace$ oscillations performed by taking advantage of quantum coherence between pairs of $\ensuremath{D^0}\xspace \ensuremath{\overline{D}^{0}}\xspace$ mesons produced in $e^+e^-$ annihilations near threshold. In this work, doubly-tagged $\ensuremath{D^0}\xspace \ensuremath{\overline{D}^{0}}\xspace$ events, where one $D$ decays to a $CP$ eigenstate and the other $D$ decays in a semileptonic mode, are reconstructed using a data sample of 2.92\,fb$^{-1}$ collected with the BESIII detector at the center-of-mass energy of $\sqrt{s}$ = 3.773\,GeV. We obtain $y_{CP} = (-2.0\pm1.3\pm0.7)\%$, where the first uncertainty is statistical and the second is systematic. This result is compatible with the current world average.

hep-ex↗

arXiv2015

Observation of $e^+e^-\to π^0π^0 h_c$ and a neutral charmoniumlike structure $Z_c(4020)^0$

Using data collected with the BESIII detector operating at the Beijing Electron Positron Collider at center-of-mass energies of $\sqrt{s}=4.23$, 4.26, and 4.36~GeV, we observe $\EE\to \pphc$ for the first time. The Born cross sections are measured and found to be about half of those of $\EE\to π^+π^-h_c$ within less than 2$σ$. In the $π^0h_c$ mass spectrum, a structure at 4.02~GeV/$c^2$ is found. It is most likely to be the neutral isospin partner of the $\zcp^{\pm}$ observed in the process of $\EE\to π^+π^-h_c$ is found. A fit to the $π^0 h_c$ invariant mass spectrum, with the width of the $\zcpn$ fixed to that of its charged isospin partner and possible interferences with non-$\zcpn$ amplitudes neglected, gives a mass of ($4023.9\pm 2.2 \pm 3.8$)~MeV/$c^2$ for the $\zcpn$, where the first error is statistical and the second systematic.

hep-ex↗

arXiv2015

Search for the $Y(4140)$ via $e^{+} e^{-} \to γϕJ/ψ$ at $\sqrt{s}=$ 4.23, 4.26 and 4.36 GeV

Using data samples collected at center-of-mass energies $\sqrt{s} = 4.23$, 4.26, and 4.36 GeV with the BESIII detector operating at the BEPCII storage ring, we search for the production of the charmoniumlike state $Y(4140)$ through a radiative transition followed by its decay to $ϕJ/ψ$. No significant signal is observed and upper limits on $σ[e^{+} e^{-} \rightarrow γY(4140)] \cdot \mathcal{B}(Y(4140)\rightarrow ϕJ/ψ)$ at the $90\%$ confidence level are estimated as 0.35, 0.28, and 0.33 pb at $\sqrt{s} = 4.23$, 4.26, and 4.36 GeV, respectively.

hep-ex↗

arXiv2015

Search for the $η_c(2S)/h_c\to p\bar{p}$ decays and measurements of the $χ_{cJ}\to p\bar{p}$ branching fractions

Using a sample of $1.06\times10^{8}~ψ(3686)$ events collected with the BESIII detector at BEPCII, the decays $η_{c}(2S)\to p\bar{p}$ and $h_{c}\to p\bar{p}$ are searched for, where $η_c(2S)$ and $h_c$ are reconstructed in the decay chains $ψ(3686)\toγη_{c}(2S)$, $η_{c}(2S)\to p\bar{p}$ and $ψ(3686)\toπ^{0}h_{c}$, $h_{c}\to p\bar{p}$, respectively. No significant signals are observed. The upper limits of the product branching fractions are determined to be $\mathcal{B}(ψ(3686)\toγη_c(2S))\times\mathcal{B}(η_{c}(2S)\to p\bar{p})<1.4\times10^{-6}$ and $\mathcal{B}(ψ(3686)\toπ^0h_c)\times\mathcal{B}(h_{c}\to p\bar{p})<1.3\times10^{-7}$ at the 90% C.L.. The branching fractions for $χ_{cJ}\to p\bar{p}$ $(J=0,~1,~2)$ are also measured to be $(24.5\pm0.8\pm1.3,~8.6\pm0.5\pm0.5,~8.4\pm0.5\pm0.5)\times10^{-5}$, which are the world's most precise measurements.

hep-ex↗

arXiv2015

Precision measurement of the $D^{*0}$ decay branching fractions

Using 482 pb$^{-1}$ of data taken at $\sqrt{s}=4.009$ GeV, we measure the branching fractions of the decays of $D^{*0}$ into $D^0π^0$ and $D^0γ$ to be $\BR(D^{*0} \to D^0π^0)=(65.5\pm 0.8\pm 0.5)%$ and $\BR(D^{*0} \to D^0γ)=(34.5\pm 0.8\pm 0.5)%$ respectively, by assuming that the $D^{*0}$ decays only into these two modes. The ratio of the two branching fractions is $\BR(D^{*0} \to D^0π^0)/\BR(D^{*0} \to D^0γ) =1.90\pm 0.07\pm 0.05$, which is independent of the assumption made above. The first uncertainties are statistical and the second ones systematic. The precision is improved by a factor of three compared to the present world average values.

hep-ex↗

arXiv2015

Study of $e^+e^-\toωχ_{cJ}$ at center-of-mass energies from 4.21 to 4.42 GeV

Based on data samples collected with the BESIII detector at the BEPCII collider at 9 center-of-mass energies from 4.21 to 4.42 GeV, we search for the production of $e^+e^-\to ωχ_{cJ}$ ($J$=0, 1, 2). The process $e^+e^-\to ωχ_{c0}$ is observed for the first time, and the Born cross sections at $\sqrt{s}$=4.23 and 4.26 GeV are measured to be $(55.4\pm 6.0\pm 5.9)$ and $(23.7\pm 5.3\pm 3.5)$ pb, respectively, where the first uncertainties are statistical and the second are systematic. The $ωχ_{c0}$ signals at the other 7 energies and $e^+e^-\to ωχ_{c1}$ and $ωχ_{c2}$ signals are not significant, and the upper limits on the cross sections are determined. By examining the $ωχ_{c0}$ cross section as a function of center-of-mass energy, we find that it is inconsistent with the line shape of the $Y(4260)$ observed in $e^+ e^-\toπ^+π^-J/ψ$. Assuming the $ωχ_{c0}$ signals come from a single resonance, we extract mass and width of the resonance to be $(4230\pm8\pm6)$ MeV/$c^2$ and $(38\pm12\pm2)$ MeV, respectively, and the statistical significance is more than $9σ$.

hep-ex↗

arXiv2015

Search for the weak decays $J/ψ\to D^{(*)}_{s}eν_{e}$

Using a sample of $2.25\times 10^8$ $J/ψ$ events collected with the BESIII detector at the BEPCII collider, we search for the $J/ψ$ semi-leptonic weak decay $J/ψ\to D^{-}_{s} e^{+}ν_{e}+c.c.$ with a much higher sensitivity than previous searches. We also perform the first search for $J/ψ\to D^{*-}_{s} e^{+}ν_{e}+c.c.$ No significant excess of a signal above background is observed in either channel. At the $90\%$ confidence level, the upper limits are determined to be $\mathcal{B}(J/ψ\to D^{-}_{s}e^{+}ν_{e}+c.c.)<1.3\times10^{-6}$ and $\mathcal{B}(J/ψ\to {D^{*}_{s}}^{-}e^{+}ν_{e}+c.c.)<1.8\times10^{-6}$, respectively. Both are consistent with Standard Model predictions.

hep-ex↗

arXiv2014

Study of J/psi->eta phi pi+pi- at BESIII

Based on a sample of $2.25\times 10^{8} J/ψ$ events taken with the BESIII detector at the BEPCII collider, we present the results of a study of the decay $J/ψ\to ηϕπ^{+}π^{-}$. The $Y(2175)$ resonance is observed in the invariant mass spectrum of $ϕf_{0}(980)$ with a statistical significance of greater than $10σ$. The corresponding mass and width are determined to be $M=2200\pm 6 \mathrm{(stat.)} \pm 5\mathrm{(syst.)} \mathrm{MeV}/c^{2}$ and $Γ=104\pm 15\mathrm{(stat.)}\pm 15\mathrm{(syst.)}$ MeV, respectively, and the product branching fraction is measured to be $\mathcal{B}(J/ψ\toηY(2175)$, $Y(2175)\to ϕf_{0}(980)$, $f_{0}(980)\to π^{+}π^{-})= (1.20\pm 0.14\mathrm{(stat.)}\pm 0.37 \mathrm{(syst.)})\times 10^{-4}$. The results are consistent within errors with those of previous experiments. We also measure the branching fraction of $J/ψ\to ϕf_1(1285)$ with $f_1(1285)\to ηπ^{+}π^{-}$ and set upper limits on the branching fractions for $J/ψ\to ϕη(1405)$/$ϕX(1835)$/$ϕX(1870)$ with $η(1405)$/$X(1835)$/$X(1870)\to ηπ^{+}π^{-}$ at the 90\% confidence level.

hep-ex↗

arXiv2014

Evidence for $e^+e^-\toγχ_{c1, 2}$ at center-of-mass energies from 4.009 to 4.360 GeV

Using data samples collected at center-of-mass energies of $\sqrt{s}$ = 4.009, 4.230, 4.260, and 4.360 GeV with the BESIII detector operating at the BEPCII collider, we perform a search for the process $e^+e^-\toγχ_{cJ}$ $(J = 0, 1, 2)$ and find evidence for $e^+e^-\toγχ_{c1}$ and $e^+e^-\toγχ_{c2}$ with statistical significances of 3.0$σ$ and 3.4$σ$, respectively. The Born cross sections $σ^{B}(e^+e^-\toγχ_{cJ})$, as well as their upper limits at the 90% confidence level are determined at each center-of-mass energy.

hep-ex↗

arXiv2014

Search for C-parity violation in $J/ ψ\to γγ$ and $ γϕ$

Using $1.06\times10^8$ $ψ(3686)$ events recorded in $e^{+}e^{-}$ collisions at $\sqrt{s}=$ 3.686 GeV with the BESIII at the BEPCII collider, we present searches for C-parity violation in $J/ψ\to γγ$ and $ γϕ$ decays via $ψ(3686) \to J/ψπ^+π^-$. No significant signals are observed in either channel. Upper limits on the branching fractions are set to be $\mathcal{B}(J/ψ\to γγ) < 2.7 \times 10^{-7}$ and $\mathcal{B}(J/ψ\to γϕ) < 1.4 \times 10^{-6}$ at the 90\% confidence level. The former is one order of magnitude more stringent than the previous upper limit, and the latter represents the first limit on this decay channel.

hep-ex↗

arXiv2014

Observation of $J/ψ\rightarrow p\bar{p}a_{0}(980)$ at BESIII

Using $2.25\times10^{8}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage rings, we observe for the first time the process $J/ψ\rightarrow p\bar{p}a_{0}(980)$, $a_{0}(980)\rightarrow π^{0}η$ with a significance of $6.5σ$ ($3.2σ$ including systematic uncertainties). The product branching fraction of $J/ψ\rightarrow p\bar{p}a_{0}(980)\rightarrow p\bar{p}π^{0}η$ is measured to be $(6.8\pm1.2\pm1.3)\times 10^{-5}$, where the first error is statistical and the second is systematic. This measurement provides information on the $a_{0}$ production near threshold coupling to $p\bar{p}$ and improves the understanding of the dynamics of $J/ψ$ decays to four body processes.

hep-ex↗

arXiv2014

Study of e$^+$e$^-$ $\rightarrow \text{p} \overline{\text{p}}π^0$ in the Vicinity of the $ψ\text{(3770)}$

The process $e^+e^-\rightarrow p\overline{p}π^0$ has been studied by analyzing data collected at $\sqrt{s}=3.773$ GeV, at $\sqrt{s}=3.650$ GeV, and during a $ψ(3770)$ line shape scan with the BESIII detector at the BEPCII collider. The Born cross section of $p \overline{p} π^0$ in the vicinity of the $ψ(3770)$ is measured and the Born cross section of $ψ(3770)\rightarrow p \overline{p} π^0$ is extracted considering interference between resonant and continuum production amplitudes. Two solutions with the same probability and a significance of 1.5$σ$ are found, and the Born cross section of $ψ(3770)\rightarrow p \overline{p} π^0$ is determined to be less than 0.22 pb at 90% confidence level and $33.8\pm1.8\pm2.1$ pb, respectively. Using the estimated cross section and a constant decay amplitude approximation, the cross section $σ(p\overline{p} \rightarrow ψ(3770) π^0)$ is calculated for the kinematic situation of the planned $\overline{\text{P}}\text{ANDA}$ experiment. The maximum cross section corresponding to the two solutions is expected to be less than $0.79$ nb at 90% confidence level and $122\pm10$ nb at a center of mass energy of 5.26 GeV.

hep-ex↗

arXiv2014

Study of $e^+e^- \rightarrow p\bar{p}$ in the vicinity of $ψ(3770)$

Using 2917 $\rm{pb}^{-1}$ of data accumulated at 3.773~$\rm{GeV}$, 44.5~$\rm{pb}^{-1}$ of data accumulated at 3.65~$\rm{GeV}$ and data accumulated during a $ψ(3770)$ line-shape scan with the BESIII detector, the reaction $e^+e^-\rightarrow p\bar{p}$ is studied considering a possible interference between resonant and continuum amplitudes. The cross section of $e^+e^-\rightarrowψ(3770)\rightarrow p\bar{p}$, $σ(e^+e^-\rightarrowψ(3770)\rightarrow p\bar{p})$, is found to have two solutions, determined to be ($0.059\pm0.032\pm0.012$) pb with the phase angle $ϕ= (255.8\pm37.9\pm4.8)^\circ$ ($<$0.11 pb at the 90% confidence level), or $σ(e^+e^-\rightarrowψ(3770)\rightarrow p\bar{p}) = (2.57\pm0.12\pm0.12$) pb with $ϕ= (266.9\pm6.1\pm0.9)^\circ$ both of which agree with a destructive interference. Using the obtained cross section of $ψ(3770)\rightarrow p\bar{p}$, the cross section of $p\bar{p}\rightarrow ψ(3770)$, which is useful information for the future PANDA experiment, is estimated to be either ($9.8\pm5.7$) nb ($<17.2$ nb at 90% C.L.) or $(425.6\pm42.9)$ nb.

hep-ex↗

arXiv2014

Measurement of $χ_{cJ}$ decaying into $η^{\prime}K^+K^-$

Using $(106.41\pm 0.86) \times 10^{6}$ $ψ(3686)$ events collected with the BESIII detector at BEPCII, we study for the first time the decay $χ_{cJ}\toη'K^+K^-$, where $η'\toγρ^{0}$ and $η'\toηπ^+π^-$. A partial wave analysis in the covariant tensor amplitude formalism is performed for the decay $χ_{c1}\toη'K^+K^-$. Intermediate processes $χ_{c1}\toη' f_0(980)$, $χ_{c1}\toη' f_0(1710)$, $χ_{c1}\toη' f_2'(1525)$ and $χ_{c1}\to K^*_0(1430)^{\pm}K^{\mp}$ ($K^*_0(1430)^{\pm}\toη' K^{\pm}$) are observed with statistical significances larger than 5$σ$, and their branching fractions are measured.

hep-ex↗

arXiv2014

Precision Measurement of the Mass of the $τ$ Lepton

An energy scan near the $τ$ pair production threshold has been performed using the BESIII detector. About $24$ pb$^{-1}$ of data, distributed over four scan points, was collected. This analysis is based on $τ$ pair decays to $ee$, $eμ$, $eh$, $μμ$, $μh$, $hh$, $eρ$, $μρ$ and $πρ$ final states, where $h$ denotes a charged $π$ or $K$. The mass of the $τ$ lepton is measured from a maximum likelihood fit to the $τ$ pair production cross section data to be $m_τ = (1776.91\pm0.12 ^{+0.10}_{-0.13}$) MeV/$c^2$, which is currently the most precise value in a single measurement.

hep-ex↗

arXiv2014

Search for the radiative transitions $ψ(3770)\toγη_c$ and $γη_c(2S)$

By using a 2.92 fb$^{-1}$ data sample taken at $\sqrt{s} = 3.773$ GeV with the BESIII detector operating at the BEPCII collider, we search for the radiative transitions $ψ(3770)\toγη_c$ and $γη_c(2S)$ through the hadronic decays $η_c(η_c(2S))\to K^0_SK^\pmπ^\mp$. No significant excess of signal events above background is observed. We set upper limits at a 90% confidence level for the product branching fractions to be $\mathcal{B}(ψ(3770)\toγη_c)\times \mathcal{B}(η_c\to K^0_SK^\pmπ^\mp) < 1.6\times10^{-5}$ and $\mathcal{B}(ψ(3770)\toγη_c(2S))\times \mathcal{B}(η_c(2S)\to K^0_SK^\pmπ^\mp) < 5.6\times10^{-6}$. Combining our result with world-average values of $\mathcal{B}(η_c(η_c(2S))\to K^0_SK^\pmπ^\mp)$, we find the branching fractions $\mathcal{B}(ψ(3770)\toγη_c) < 6.8\times10^{-4}$ and $\mathcal{B}(ψ(3770)\toγη_c(2S)) < 2.0\times10^{-3}$ at a 90% confidence level.

hep-ex↗