Observation of a Resonance X(1835) in J/ψ→γπ+π−η′

Abstract

Using a data sample corresponding to an integrated luminosity of 2.93 fb −1 collected at a centerof-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider, we search for a scalar partner of the X(3872), denoted as X(3700), via ψ(3770) → γηη and γπ + π − J/ψ processes. No significant signals are observed and the upper limits of the product branching fractions B(ψ(3770) → γX(3700))•B(X(3700) → ηη ) and B(ψ(3770) → γX(3700))•B(X(3700) → π + π − J/ψ) are determined at the 90% confidence level, for the narrow X(3700) with a mass ranging from 3710 to 3740 MeV/c 2 , which are from 0.8 to 1.8 (×10 −5 ) and 0.9 to 3.4 (×10 −5 ), respectively.

Extraction of baryonia from the lightest anti-protonic atoms

“…Table IX gives R n/p , the ratio of basic pn capture rate to pp capture rate. It indicates consistency of Paris 09 potential with the R n/p results in 3 He and 4 He. The R n/p has been calculated in 2P atomic state that is likely to be the state of capture for 70% of all antiprotons that reach low level atomic states [27].…”

“…The separation, average recoil energies and the spread of recoil energies are given in Table III. These values and the separation energies indicate that three atoms 2 H, 3 He, 4 He cover disjoint energy regions from about -5 down to -40 MeV. Therefore, a model is required for the sub-threshold extrapolation.…”

“…This may be, but not necessarily is, a confirmation of a quasi-bound state. The valid proof requires a look into sub-threshold region and this also has been achieved by the BES Collaboration [3] in the mesonic decays of J/ψ into γπ + π − η ′ . A sub-threshold enhancement, the X(1835), was found in this way.…”

“…In this work we study the level shifts and widths due to pN interactions in the lightest atoms (levels): 2 H(2P ), 3 He(2P , 3D) and 4 He(2P , 3D). The number of states is limited to those characterized by very low atomic-nuclear overlaps.…”

Light unflavor vector meson spectroscopy around the mass range of $2.4\sim 3$ GeV and possible experimental evidence

“…Focusing on the study of light unflavor vector meson spectroscopy, we find big progress made by experiment in the past years [1][2][3]. A typical example is the observation of the Y(2175) [4] and the following measurement [5][6][7][8][9][10] around the Y(2175), which have stimulated extensive discussions of decoding the property of the Y(2175) [11][12][13][14][15][16].…”