In this work, we seriously discuss whether X(3915) can be treated as a χ c0 (2P) state. Based on an unquenched quark model, we give the mass spectrum of the χ cJ (2P) states, where there are no free input parameters in our calculation. Our result shows that the mass gap between χ c0 (2P) and χ c2 (2P) can reach 13 MeV, which can reproduce the mass difference between Z(3930) and X(3915). Additionally, the calculated masses of χ c0 (2P) and χ c2 (2P) are consistent with experimental values of X(3915) and Z(3930), respectively. Besides, giving the mass spectrum analysis to support X(3915) as χ c0 (2P), we also calculate the width of χ c0 (2P) with the same framework, which is also consistent with the experimental data of X(3915). Thus, the possibility of charmoniumlike state X(3915) as χ c0 (2P) state is further enforced. ‡ Corresponding author * Electronic address: duanmx16@lzu.edu.cn † Electronic address: luosq15@lzu.edu.cn § Electronic address: xiangliu@lzu.edu.cn ¶ Electronic address: matsuki@tokyo-kasei.ac.jp η c (2S) 1986 h c (1P) 2003 X(3872) 2006 Z(3930) 2010 X(3915) 2013 X(3823) 2017 Y(4220) 2019 X(3842) Established charmonia XYZ states as the candidates of charmonium 17 years FIG. 1: The established charmonia and some XYZ states as possible candidates for charmonium.In 2009, focusing on 2P states, the Lanzhou group carried out the study of the mass spectrum and strong decay behav-arXiv:2002.03311v3 [hep-ph]

No abstract

No abstract

Un-doped Sr3Al2OCl2 material is synthesized by conventional solid state method in reducing atmosphere. It shows intense photostimulated luminescence and the emission band of spectrum covers in 420-800 nm under infrared laser (980 nm) stimulation. Both the emission centers and traps are related to oxygen-deficient defects. Moreover, thermoluminescence indicates that there are at least five types of traps levels in this material. The weak long lasting phosphorescence (30 s) implies the lack of the shallow traps. The deep traps are rich and their storage capacity can be influenced by the releasing progress of the shallow traps. When the shallow traps are completely emptied after 6 h, the stable storage capacity of deep traps is still as large as 51.5%. Also, this material show good photostimulated luminescence under irradiation by infrared laser. Therefore, the un-doped Sr3Al2O5Cl2 material synthesized in reducing atmosphere can be considered as a potential photostimulated material for optical storage. Accordingly, the influence mechanism of traps on photostimulated luminescence is proposed.

No abstract

We demonstrate that triangle singularity (TS) and box singularity (BS) mechanisms can produce unique narrow enhancements at the Λ c D and Λ c D * thresholds in the invariant mass spectra of J/ψp and J/ψpπ, respectively. Taking into account that such mechanisms only depend on the initial Σ ( * ) c D( * ) interactions near threshold within the TS or BS kinematic regimes, the Λ c D and Λ c D * threshold enhancements can be regarded as a feeddown phenomenon originated from both the heavier pentaquark decays and the Σ ( * ) c D( * ) scatterings from the continuum. A search for these structures in the J/ψp and J/ψpπ spectra in both exclusive and semi-inclusive processes will provide a smoking-gun evidence for the hadronic molecule nature of those observed pentaquarks and clarify the role played by the TS and BS in the near-threshold dynamics. c D( * ) channel, they were interpreted as hadronic molecules formed by the Σ ( * ) c D( * ) near-threshold interactions [13-23]. With the Run-2 data samples, the reanalysis of Λ 0 b → J/ψpK − exposes more detailed structures in the J/ψp invariant mass spectrum [24]. P c (4450) splits into two states, P c (4440) and P c (4457), which fit well the J P = 1/2 − and 3/2 − doublet formed by Σ c D * , and a new state P c (4312), which fits the Σ c D molecular state, is identified [25-35]. Meanwhile, signals for P c (4380), formerly assigned as the Σ *c D molecule in the Run-1 analysis, become obscure in the Run-2 analysis. It turns out to be broad and can be even absorbed by the background [24]. It should be noted that the quantum numbers determined by the Run-2 analysis are more consistent with the molecular scenario based on the relative S -wave interactions and also consistent with the early theoretical predictions [36][37][38][39].A key issue clarified by the Run-2 analysis is that these hidden charmonium pentaquark candidates couple to the nearby Σ c D( * ) in a relative S -wave. This makes the hadronic molecule scenario a natural interpretation for their internal structures and provide important insights into the threshold dynamics. Note that these observed P c states are correlated with the Σ ( * ) c D( * ) thresholds instead of Λ ( * ) c D( * ) . It is also interesting to observe that this feature seems to be consistent with the one boson exchange (OBE) dynamics between the charmed meson and baryon. Namely, it manifests to be attractive between Σ ( * ) c and D( * ) , but appears to be repulsive between Λ ( * ) c