The PANDA Experiment at FAIR - Subatomic Physics with Antiprotons

The non-perturbative nature of the strong interaction leads to spectacular phenomena, such as the formation of hadronic matter, color confinement, and the generation of the mass of visible matter. To get deeper insight into the underlying mechanisms remains one of the most challenging tasks within the field of subatomic physics. The antiProton ANnihilations at DArmstadt (PANDA) collaboration has the ambition to address key questions in this field by exploiting a cooled beam of antiprotons at the High Energy Storage Ring (HESR) at the future Facility for Antiproton and Ion Research (FAIR) combined with a state-of-the-art and versatile detector. This contribution will address some of the unique features of PANDA that give rise to a promising physics program together with state-of-the-art technological developments.Comment: 8 pages, 2 figures, proceedings of MENU201

Determination of spin and parity of D(s)⁎ mesons

The spin and parity of the charmed mesons Ds⁎+, D⁎0 and D⁎+ are determined for the first time to be JP=1− with significances greater than 10σ over other hypotheses of 2+ and 3−, using an e+e− collision data sample with an integrated luminosity of 3.19 fb−1 collected by the BESIII detector at a center-of-mass energy of 4.178 GeV. Different spin-parity hypotheses are tested via a helicity amplitude analysis of the processes e+e−→Ds⁎+Ds−, D⁎0D0 and D⁎+D−, with Ds⁎+→Ds+γ, D⁎0→D0π0, and D⁎+→D+π0. The results confirm the quark model predictions.</p

Observation of the decays χ cJ → nKS0Λ¯ + c.c.

By analyzing 4.48 × 108ψ(3686) events collected with the BESIII detector, we observe the decays χcJ → nKS0Λ¯ + c.c. (J = 0, 1, 2) for the first time, via the radiative transition ψ(3686) → γχcJ. The branching fractions are determined to be (6.65 ± 0.26stat ± 0.41syst) × 10−4, (1.66 ± 0.12stat ± 0.12syst) × 10−4, and (3.58 ± 0.16stat ± 0.23syst) × 10−4 for J = 0, 1, and 2, respectively. [Figure not available: see fulltext.]

Study of ψ (3686) → Λ Λ ¯ ω

Based on a data sample of (448.1±2.9)×106 ψ(3686) events collected with the BESIII detector at the BEPCII collider, the branching fraction of ψ(3686)→ΛΛ¯ω is measured to be (3.30±0.34(stat)±0.29(syst))×10-5 for the first time. In addition, the Λω (or Λ¯ω) invariant mass spectra is studied and the potential presence of excited Λ states has been investigated

Search for a CP-odd light Higgs boson in J/ψ →γA⁰

Using J/ψ radiative decays from 9.0 billion J/ψ events collected by the BESIII detector, we search for di-muon decays of a CP-odd light Higgs boson (A0), predicted by many new physics models beyond the Standard Model, including the next-to-minimal supersymmetric Standard Model. No evidence for the CP-odd light Higgs production is found, and we set 90% confidence level upper limits on the product branching fraction B(J/ψ→γA0)×B(A0→μ+μ-) in the range of (1.2-778.0)×10-9 for 0.212≤mA0≤3.0 GeV/c2. The new measurement is a 6-7 times improvement over our previous measurement, and is also slightly better than the BABAR measurement in the low-mass region for tanβ=1

Study of the decay D⁺ → K^∗(892)⁺K⁰_S in D⁺ → K⁺K⁰_Sπ⁰

Based on an e+e− collision data sample corresponding to an integrated luminosity of 2.93  fb−1 collected with the BESIII detector at √s=3.773  GeV, the first amplitude analysis of the singly Cabibbo-suppressed decay D+→K+K0Sπ0 is performed. From the amplitude analysis, the K∗(892)+K0S component is found to be dominant with a fraction of (57.1±2.6±4.2)%, where the first uncertainty is statistical and the second systematic. In combination with the absolute branching fraction B(D+→K+K0Sπ0) measured by BESIII, we obtain B(D+→K∗(892)+K0S)=(8.69±0.40±0.64±0.51)×10−3, where the third uncertainty is due to the branching fraction B(D+→K+K0Sπ0). The precision of this result is significantly improved compared to the previous measurement. This result also differs from most of theoretical predictions by about 4σ, which may help to improve the understanding of the dynamics behind

Partial wave analysis of ψ(3686) → K⁺K⁻η

Using a sample of (448.1±2.9)×106 ψ(3686) events collected with the BESIII detector, we perform the first partial wave analysis of ψ(3686)→K+K-η. In addition to the well established states, φ(1020), φ(1680), and K3∗(1780), contributions from X(1750), ρ(2150), ρ3(2250), and K2∗(1980) are also observed. The X(1750) state is determined to be a 1-resonance. The simultaneous observation of the φ(1680) and X(1750) indicates that the X(1750), with previous observations in photoproduction, is distinct from the φ(1680). The masses, widths, branching fractions of ψ(3686)→K+K-η, and the intermediate resonances are also measured