Search

In 2010, Λcc¯* states were predicted as the strange number S=−1 partners of Ncc¯*, which are well known now as the Pc states and observed experimentally by the LHCb Collaboration. We analyze the decay behaviors of Λcc¯ as S-wave hadronic molecules within the effective Lagrangian framework by a similar method, which has been applied on Pc states successfully. With partial widths of possible decay channels calculated, we find that Λcc¯(4213) and Λcc¯(4403), which are formed as pseudoscalar meson baryon molecules, mainly decay to the ηcΛ channel. For the two vector meson baryon molecule states, our results show that the total decay width with JP=12− is by one order of magnitude larger than that with JP=32−. The decay patterns and relative decay ratios are very different for Λcc¯(4370) being a Ds*−Λc+ or D¯*Ξc molecule state. The main decay channels of Λcc¯(4550) are D¯(*)Ξc(*,′) because of the pseudoscalar meson exchange mechanism. In addition, D¯*Ξc is the dominant decay channel of Λcc¯(4490), which is assumed as a D¯Ξc* bound state. These decay patterns of the Λcc¯* states would provide guidance for future experimental searches and help us to understand their internal structures.

Invoked by the recent CMS observation regarding candidates of the χb(3P) multiplet, we analyze the hyperfine and mass splittings among the 3P multiplet in our unquenched quark model studies. The mass difference of χb2 and χb1 in the 3P multiplet measured by the CMS Collaboration (10.6±0.64±0.17 MeV) is very close to our theoretical prediction (12 MeV). Our corresponding mass splitting of χb1 and χb0 enables us to predict more precisely the mass of χb0(3P) to be (10490±3) MeV. Moreover, we predict ratios of the radiative decays of χbJ(nP) candidates, both in the unquenched quark model and quark potential model. Our predicted relative branching fraction of χb0(3P)→ϒ(3S)γ is one order of magnitude smaller than χb2(3P); this naturally explains the nonobservation of χb0(3P) in the recent CMS search. We hope these results provide useful references for forthcoming experimental searches.

Up to now, all charge radius measurements of the proton and deuteron assumed uniform spheroidal charge distribution. We investigate the nuclear deformation effects on these charge radius measurements by assuming a uniform prolate charge distribution for the proton and deuteron. We solve the energy levels of the corresponding muonic and electric atoms with such deformed nucleus and present how the purely quadruple deformation of proton and deuteron affects their Lamb shifts. The numerical results suggest that the deformation of proton and deuteron leads to that the charge radius extracted from the electronic measurement should be smaller than the corresponding one in the muonic measurement which assumed uniform spheroidal charge distribution. If the central values of newest measurements for the proton are adopted, the proton would have a prolate structure with the 0.91 $\mathrm{fm}$ long axis and 0.73 $\mathrm{fm}$ short axis. Further improved precise charge radius measurements of the proton and deuteron will help us to pin down their shape deformation., Comment: 13pages, 4figures

Invoked by the recent CMS observation regarding candidates of the χb(3P) multiplet, we analyze the hyperfine and mass splittings among the 3P multiplet in our unquenched quark model studies. The mass difference of χb2 and χb1 in the 3P multiplet measured by the CMS Collaboration (10.6±0.64±0.17 MeV) is very close to our theoretical prediction (12 MeV). Our corresponding mass splitting of χb1 and χb0 enables us to predict more precisely the mass of χb0(3P) to be (10490±3) MeV. Moreover, we predict ratios of the radiative decays of χbJ(nP) candidates, both in the unquenched quark model and quark potential model. Our predicted relative branching fraction of χb0(3P)→Υ(3S)γ is one order of magnitude smaller than χb2(3P); this naturally explains the nonobservation of χb0(3P) in the recent CMS search. We hope these results provide useful references for forthcoming experimental searches.

We use a unitary coupled-channel model to study the interactions. In our calculation, SU(3) flavor symmetry is applied to determine the coupling constants. Several resonant and bound states with different spin and parity are dynamically generated in the mass range of the recently observed pentaquarks. The approach is also extended to the hidden beauty sector to study the interactions. As the b-quark mass is heavier than the c-quark mass, there are more resonances observed for the interactions and they are more tightly bound.

Up to now, the $N^*$ production from $e^+e^-$ annihilations has been studied only around charmonium region. Charmonium decays to $N^*$s are analogous to (time-like) EM form factors in that the charm quark annihilation provides a nearly pointlike (ggg) current. Complementary to other sources, such as $\pi N$, $eN$ and $\gamma N$ reactions, this new source for $N^*$ spectroscopy has a few advantages, such as an isospin filter and a low spin filter. The experimental results on $N^*$ from $e^+e^-$ annihilations and their phenomenological implications are reviewed. Possible new sources on $N^*$ production from $e^+e^-$ annihilations are discussed., Comment: 7 pages, 4 figures. Contribution to the proceedings of the 11th International Workshop on the Physics of Excited Nucleons, 20-23 August 2017, University of South Carolina, Columbia, SC, USA

Very recently, a new $��^{*}$ state was reported by the Belle Collaboration, with its mass of $2012.4 \pm 0.7\ \text{(stat)}\pm 0.6\ \text{(syst)}\ \mathrm{MeV}$, which locates just below the $K��^*$ threshold and hence hints to be a possible $K��^*$ hadronic molecule. Using the effective Lagrangian approach as the same as our previous works for other possible hadronic molecular states, we investigate the decay behavior of this new $��^*$ state within the hadronic molecular picture. The results show that the measured decay width can be reproduced well and its dominant decay channel is predicted to be the $K����$ three-body decay. This suggests that the newly observed $��^*$ may be ascribed as the $J^P={3/2}^-$ $K��^*$ hadronic molecular state and can be further checked through its $K����$ decay channel., 7pages, 6 figures

Invoked by the recent CMS observation regarding candidates of the $��_b(3P)$ multiplet, we analyze the ultrafine and mass splittings among $3P$ multiplet in our unquenched quark model (UQM) studies. The mass difference of $��_{b2}$ and $��_{b1}$ in $3P$ multiplet measured by CMS collaboration ($10.6 \pm 0.64 \pm 0.17$ MeV) is very close to our theoretical prediction ($12$ MeV). Our corresponding mass splitting of $��_{b1}$ and $��_{b0}$ enables us to predict more precisely the mass of $��_{b0}(3P)$ to be ($10490\pm 3$) MeV. Moreover, we predict ratios of the radiative decays of $��_{bJ}(nP)$ candidates, both in UQM and quark potential model. Our predicted relative branching fraction of $��_{b0}(3P)\to��(3S)��$ is one order of magnitude smaller than $��_{b2}(3P)$, this naturally explains the non-observation of $��_{b0}(3P)$ in recent CMS search. We hope these results might provide useful references for forthcoming experimental searches.

We study the dipion transitions Υ(4S)→Υ(nS)π+π−(n=1,2). In particular, we consider the effects of the two intermediate bottomoniumlike exotic states Zb(10610) and Zb(10650) as well as bottom meson loops. The strong pion-pion final-state interactions, especially including channel coupling to K¯K in the S wave, are taken into account model independently by using dispersion theory. Based on a nonrelativistic effective field theory we find that the contribution from the bottom meson loops is comparable to those from the chiral contact terms and the Zb-exchange terms. For the Υ(4S)→Υ(2S)π+π− decay, the result shows that including the effects of the Zb exchange and the bottom meson loops can naturally reproduce the two-hump behavior of the ππ mass spectra. Future angular distribution data are decisive for the identification of different production mechanisms. For the Υ(4S)→Υ(1S)π+π− decay, we show that there is a narrow dip around 1 GeV in the ππ invariant mass distribution, caused by the final-state interactions. The distribution is clearly different from that in similar transitions from lower Υ states, and needs to be verified by future data with high statistics. Also we predict the decay width and the dikaon mass distribution of the Υ(4S)→Υ(1S)K+K− process.

We propose a new model to create a light meson in the heavy quarkonium transition, which is inspired by the Nambu$-$Jona-Lasinio (NJL) model. Hadronic transitions of $J^{PC}=1^{--}$ higher charmonia with the emission of an $\eta$ meson are studied in the framework of the proposed model. The model shows its potential to reproduce the observed decay widths and make predictions for the unobserved channels. We present our predictions for the decay width of $\Psi \to J/\psi \eta$ and $\Psi \to h_{c}(1P)\eta$, where $\Psi$ are higher $S$ and $D$ wave vector charmonia, which provide useful references to search for higher charmonia and determine their properties in forthcoming experiments. The predicted branching fraction $\mathcal B(\psi(4415)\to h_{c}(1P)\eta)=4.62\times 10^{-4}$ is one order of magnitude smaller than the $J/\psi \eta$ channel. Estimates of partial decay width $\Gamma(Y \to J/\psi \eta)$ are given for $Y(4360)$, $Y(4390)$ and $Y(4660)$ by assuming them as $c\bar{c}$ bound states with quantum numbers $3 ^3D_1$, $3 ^3D_1$ and $5 ^3S_1$, respectively. Our results are in favor of these assignments for $Y(4360)$ and $Y(4660)$. The corresponding experimental data for these $Y$ states has large statistical errors which do not provide any constraint on the mixing angle if we introduce $S-D$ mixing. To identify $Y(4390)$, precise measurements on its hadronic branching fraction are required which are eagerly awaited from BESIII., Comment: version published in Phys. Rev. D

We study the dipion transitions $\Upsilon(4S) \rightarrow \Upsilon(nS) \pi^+\pi^-$ $(n=1,2)$. In particular, we consider the effects of the two intermediate bottomoniumlike exotic states $Z_b(10610)$ and $Z_b(10650)$ as well as bottom meson loops. The strong pion-pion final-state interactions, especially including channel coupling to $K\bar{K}$ in the $S$-wave, are taken into account model-independently by using dispersion theory. Based on a nonrelativistic effective field theory we find that the contribution from the bottom meson loops is comparable to those from the chiral contact terms and the $Z_b$-exchange terms. For the $\Upsilon(4S) \rightarrow \Upsilon(2S) \pi^+\pi^-$ decay, the result shows that including the effects of the $Z_b$-exchange and the bottom meson loops can naturally reproduce the two-hump behavior of the $\pi\pi$ mass spectra. Future angular distribution data are decisive for the identification of different production mechanisms. For the $\Upsilon(4S) \rightarrow \Upsilon(1S) \pi^+\pi^-$ decay, we show that there is a narrow dip around 1 GeV in the $\pi\pi$ invariant mass distribution, caused by the final-state interactions. The distribution is clearly different from that in similar transitions from lower $\Upsilon$ states, and needs to be verified by future data with high statistics. Also we predict the decay width and the dikaon mass distribution of the $\Upsilon(4S) \rightarrow \Upsilon(1S) K^+ K^-$ process., Comment: 25 pages, 8 figures, predictions of the decay width and the dikaon mass distribution of the $\Upsilon(4S) \rightarrow \Upsilon(1S) K^+ K^-$ process added, more discussions added

Accelerator Driven Sub-critical System (ADS) is a technological integration of accelerator and nuclear reactor, and aims to cope with the increasing demand of radioactive nuclear waste disposal. In this paper we discuss the possibility to produce the fissile 233U with ADS and estimate the required performance of accelerator and the efficiency of 233U production. We propose that one should use Be as the moderator and breeder to control the neutron energy in the range of 1 keV-1 MeV in order to depress the production of 232U, and may further use heavy water as the moderator to improve the purity of 233U. The yield 233U could be burned in the thermal reactors after purification or used to be the initial loading of Thorium molten salt reactor so that the excellent properties of 233U in thermal neutron environment could be properly exploited. We show that it is probable to produce the 233U with ADS in view of the technological and economical aspects. Our results indicate that the fast reactor rather than slow reactor should be used if one of the main goals of ADS is to produce 233U. We suggest to further study the Thorium-based reactor, the technology of 233U purification and radiation-protection, etc.

A new particle σ* with JP = 1/2− was predicted by unquenched quark models with its mass around the well established σ* (1385) with JP = 3/2+. Here we re-examine some old data of the K− p → Λπ−π+ reaction. Firstly we re-fit the data for kaon beam momenta in the range of 1.0–1.8 GeV. Secondly we study the reaction at the energies around Λ* (1520) peak. Both studies show evidence for the existence of σ* with JP = 1/2− around 1380 MeV. Higher statistic data on relevant reactions are needed to clarify the situation.

Abundant Ψ' events have been collected at the Beijing Electron Positron Collider- II (BEPCII) that could undoubtedly provide us with a great opportunity to study the more attractive charmonium decays. As has been noticed before, in the process of J/Ψ decaying to the baryonic final states, pK−, the evident Λ* and N* bands have been observed. Similarly, by using the product of χcJ from Ψ' radiative decay, we may confirm this or find some extra new resonances. χc0's data samples will be more than χc1,2, taking into account the larger branching ratio of Ψ' → γχc0. Here, we provide explicit partial wave analysis formulae for the very interesting channel Ψ' → γχc0 → γpK−.

We analyze the meson production in e+e− → ωπ0 as a probe for studying the isospin violation mechanisms. By clarifying the dynamic sources causing the isospin violation, we succeed in quantifying those mechanisms with the help of the recent KLOE data. Hence, the → ωπ0 branching ratio is extracted. We find that apart from the electromagnetic (EM) transitions, the strong transition via intermediate kaon loops plays an important role in understanding the cross section and its lineshape.

In this proceeding, we propose to directly measure the a00(980)-f0 (980) mixing in J/ψ → f0(980) → a00 (980) and χc1 → π0a00(980) → π0f0(980) with the upgraded Beijing Electron Positron Collider(BEPCII) with BESIII detector. We show that a narrow peak of about 8 MeV will be produced by the a00(980)-f0 (980) mixing, and the predominant feature makes it standing out from the background contributions. The predicted branching ratios for these two reactions are both expected to be about O(10−6), which is unambiguously accessible with 109 J/ψ and 3 × 108 χc1 at BESIII.

We study the dipion transitions $��(4S) \rightarrow ��(nS) ��^+��^-$ $(n=1,2)$. In particular, we consider the effects of the two intermediate bottomoniumlike exotic states $Z_b(10610)$ and $Z_b(10650)$ as well as bottom meson loops. The strong pion-pion final-state interactions, especially including channel coupling to $K\bar{K}$ in the $S$-wave, are taken into account model-independently by using dispersion theory. Based on a nonrelativistic effective field theory we find that the contribution from the bottom meson loops is comparable to those from the chiral contact terms and the $Z_b$-exchange terms. For the $��(4S) \rightarrow ��(2S) ��^+��^-$ decay, the result shows that including the effects of the $Z_b$-exchange and the bottom meson loops can naturally reproduce the two-hump behavior of the $����$ mass spectra. Future angular distribution data are decisive for the identification of different production mechanisms. For the $��(4S) \rightarrow ��(1S) ��^+��^-$ decay, we show that there is a narrow dip around 1 GeV in the $����$ invariant mass distribution, caused by the final-state interactions. The distribution is clearly different from that in similar transitions from lower $��$ states, and needs to be verified by future data with high statistics. Also we predict the decay width and the dikaon mass distribution of the $��(4S) \rightarrow ��(1S) K^+ K^-$ process., 25 pages, 8 figures, predictions of the decay width and the dikaon mass distribution of the $\Upsilon(4S) \rightarrow \Upsilon(1S) K^+ K^-$ process added, more discussions added

Within the framework of dispersion theory, we analyze the dipion transitions between the lightest Υ states, Υ(nS)→Υ(mS)ππ with m