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Chen, C.

Publications and source records attributed to Chen, C..

At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Search for hidden-charm tetraquark with strangeness in e + e - → $K$ + $D^{*}_{s}$ - $D$ *0 + c.c.*

We report a search for a heavier partner of the recently observed Z cs (3985) - state, denoted as $Z^{'-}_{cs}$, in the process e + e - → $K$ + $D^{*}_{s}$ - $D$ *0 + c.c., based on e + e - collision data collected at the center-of-mass energies of $\sqrt{s}$ = 4.661, 4.682 and 4.699 GeV with the BESIII detector. The $Z^{'-}_{cs}$ is of interest as it is expected to be a candidate for a hidden-charm and open-strange tetraquark. A partial-reconstruction technique is used to isolate K + recoil-mass spectra, which are probed for a potential contribution from $Z^{'-}_{cs}$ → $D^{*}_{s}$ - $D$ *0 + (c.c.). We find an excess of $Z^{'-}_{cs}$ → $D^{*}_{s}$ - $D$ *0 + (c.c.) candidates with a significance of 2.1σ, after considering systematic uncertainties, at a mass of 4123.5 ± 0.7 stat. ± 4.7 syst. ) MeV/c 2 . As the data set is limited in size, the upper limits are evaluated at the 90% confidence level on the product of the Born cross sections (σ BORN ) and the branching fraction ($\mathcal{B}$) of $Z^{'-}_{cs}$ → $D^{*}_{s}$ - $D$ *0 , under different assumptions of the $Z^{'-}_{cs}$ mass from 4.120 to 4.140 MeV and of the width from 10 to 50 MeV at the three center-of-mass energies. The upper limits of σ BORN ∙ $\mathcal{B}$ are found to be at the level of $\mathcal{O}$(1) pb at each energy. Larger data samples are needed to confirm the $Z^{'-}_{cs}$ state and clarify its nature in the coming years.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Partial wave analysis of the charmed baryon hadronic decay $ {\Lambda}_c^{+} $ → Λ π +π 0

Based on e + e - collision samples corresponding to an integrated luminosity of 4.4 fb -1 collected with the BESIII detector at center-of-mass energies between 4.6 GeV and 4.7 GeV, a partial wave analysis of the charmed baryon hadronic decay ${\Lambda}_c^{+}$ → Λπ + π 0 is performed, and the decays ${\Lambda}_c^{+}$ → Λρ(770) + and ${\Lambda}_c^{+}$ → Σ(1385)π are studied for the first time. Making use of the world-average branching fraction $\mathcal{B}$ (${\Lambda}_c^{+}$ → Λπ + π 0 ), their branching fractions are determined to be $\mathcal{B}$(${\Lambda}_c^{+}$ → Λρ(770) + ) = (4.06 ± 0.30 ± 0.35 ± 0.23) x 10 -2 , $\mathcal{B}$(${\Lambda}_c^{+}$ → Σ(1385) + )π 0 ) = (5.86 ± 0.49 ± 0.52 ± 0.35) x 10 -3 , $\mathcal{B}$(${\Lambda}_c^{+}$ → Σ(1385) 0 )π + ) = (6.47 ± 0.59 ± 0.66 ± 0.38) x 10 -3 , where the first uncertainties are statistical, the second are systematic, and the third are from the uncertainties of the branching fractions $\mathcal{B}$ ${\Lambda}_c^{+}$ → Λπ + π 0 and $\mathcal{B}$(Σ(1385) → Λπ). In addition, the decay asymmetry parameters are measured to be αΛρ(770)+ = - 0.763 ± 0.053 ± 0.045, $\alpha$ Σ(1385)+π 0 = -0.917 ± 0.069 ± 0.056, and $\alpha$ Σ(1385) 0 π + = -0.789 ± 0.098 ± 0.056.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Observation of the decay ψ (3686) → $ {\Sigma}^{-}{\overline{\Sigma}}^{+} $ and measurement of its angular distribution

Using (448.1 ± 2.9) × 10 6 ψ(3686) events collected with the BESIII detector at the BEPCII collider, the decay ψ(3686) → Σ - $\overline{Σ}$ + is observed for the first time with a branching fraction of (2.82 ± 0.04 stat. ± 0.08 syst. ) × 10 -4 , and the angular parameter α Σ- is measured to be 0.96 ± 0.09 stat. ± 0.03 syst. .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Proton spin structure and generalized polarizabilities in the strong quantum chromodynamics regime

The strong interaction is not well understood at low energies or for interactions with low momentum transfer. Chiral perturbation theory gives testable predictions for the nucleonic generalized polarizabilities, which are fundamental quantities describing the nucleon’s response to an external field. We report a measurement of the proton’s generalized spin polarizabilities extracted with a polarized electron beam and a polarized solid ammonia target in the region where chiral perturbation theory is expected to be valid. The investigated structure function g2 characterizes the internal spin structure of the proton. From its moments, we extract the longitudinal–transverse spin polarizability δLT and twist-3 matrix element and polarizability d2¯. Our results provide discriminating power between existing chiral perturbation theory calculations and will help provide a better understanding of this strong quantum chromodynamics regime.

Ruth, D↗
DOE OSTI2022

Detection of astrophysical tau neutrino candidates in IceCube

High-energy tau neutrinos are rarely produced in atmospheric cosmic-ray showers or at cosmic particle accelerators, but are expected to emerge during neutrino propagation over cosmic distances due to flavor mixing. When high energy tau neutrinos interact inside the IceCube detector, two spatially separated energy depositions may be resolved, the first from the charged current interaction and the second from the tau lepton decay. We report a novel analysis of 7.5 years of IceCube data that identifies two candidate tau neutrinos among the 60 “High-Energy Starting Events” (HESE) collected during that period. The HESE sample offers high purity, all-sky sensitivity, and distinct observational signatures for each neutrino flavor, enabling a new measurement of the flavor composition. The measured astrophysical neutrino flavor composition is consistent with expectations, and an astrophysical tau neutrino flux is indicated at 2.8σ significance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Searches for Neutrinos from Gamma-Ray Bursts Using the IceCube Neutrino Observatory

Gamma-ray bursts (GRBs) are considered as promising sources of ultra-high-energy cosmic rays (UHECRs) due to their large power output. Observing a neutrino flux from GRBs would offer evidence that GRBs are hadronic accelerators of UHECRs. Previous IceCube analyses, which primarily focused on neutrinos arriving in temporal coincidence with the prompt gamma-rays, found no significant neutrino excess. The four analyses presented in this paper extend the region of interest to 14 days before and after the prompt phase, including generic extended time windows and targeted precursor searches. GRBs were selected between 2011 May and 2018 October to align with the data set of candidate muon-neutrino events observed by IceCube. No evidence of correlation between neutrino events and GRBs was found in these analyses. Limits are set to constrain the contribution of the cosmic GRB population to the diffuse astrophysical neutrino flux observed by IceCube. Prompt neutrino emission from GRBs is limited to ≲1% of the observed diffuse neutrino flux, and emission on timescales up to 10 4 s is constrained to 24% of the total diffuse flux.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Improved measurement of the strong-phase difference $\delta _D^{K\pi }$ in quantum-correlated $D{\overline{D}}$ decays

The decay D → K - π + is studied in a sample of quantum-correlated D$\overline{D}$ pairs, based on a data set corresponding to an integrated luminosity of 2.93 fb -1 collected at the ψ(3770) resonance by the BESIII experiment. The asymmetry between CP-odd and CP-even eigenstate decays into K - π + is determined to be A Kπ = 0.132 ± 0.011 ± 0.007, where the first uncertainty is statistical and the second is systematic. This measurement is an update of an earlier study exploiting additional tagging modes, including several decay modes involving a $K^{0}_{L}$ meson. The branching fractions of the $K^{0}_{L}$ modes are determined as input to the analysis in a manner that is independent of any strong phase uncertainty. Using the predominantly CP-even tag D → π + π - π 0 and the ensemble of CP-odd eigenstate tags, the observable $A^{πππ^0}_{Kπ}$ is measured to be 0.130 ± 0.012 ± 0.008. The two asymmetries are sensitive to $r^{Kπ}_{D}$ cos $δ^{Kπ}_{D}$ where $r^{Kπ}_{D}$ and $δ^{Kπ}_{D}$ are the ratio of amplitudes and phase difference, respectively, between the doubly Cabibbo-suppressed and Cabibbo-favoured decays. In addition, events containing D → K - π + tagged by D → $K^{0}_{S,L}$π + π - are studied in bins of phase space of the three-body decays. This analysis has sensitivity to both $r^{Kπ}_{D}$ cos $δ^{Kπ}_{D}$ and $r^{Kπ}_{D}$, sin $δ^{Kπ}_{D}$. A fit to A Kπ , $A^{πππ^0}_{Kπ}$ and the phase-space distribution of the D → $K^{0}_{S,L}$π + π - tags yields $δ^{Kπ}_{D}$ = ($187.6^{+8.9+5.4}_{-9.7-6.4}$)°, where external constraints are applied for $r^{Kπ}_{D}$ and other relevant parameters. This is the most precise measurement of $δ^{Kπ}_{D}$ in quantum-correlated D$\overline{D}$ decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗