Search for four-quark and six-quark exotic states with charm and strange quarks

我们计划利用BaBar和贝儿组合的完整数据集研究e+e-连续统中窄的、可能奇异的强子态。这将代表光谱学中第一个组合的贝儿和BaBar分析。在B介子衰变过程中观测到了X（4140）和最近发现的更高的四夸克含量[ccbar sbar]的相似态，但目前的实验证据还存在争议。我们首次提出研究e+e-连续体，这在强子碰撞实验中是不可用的。DsJ（2317）是主要的奇异候选态之一，因为它的质量比夸克模型预测的低约160 MeV，否则可以非常准确地描述许多其他奇异介子的质量我们的建议包括：（1）在[DsDs ~*]不变质量系统中寻找X（4140）和类似态的信号。如果观察到信号，这将代表第二个衰变通道，从而将状态确定为共振，并将解释排除为运动学效应。如果没有BaBar和贝儿数据集的组合，由于DsJ衰变中中性π介子的重建效率低，这种分析将遭受统计不充分的问题。[J/Psi phi]不变质量系统也将被分析，尝试建立X（4140）作为参考信号。在第二步中，在[DsDsJ（2317）]不变质量系统中寻找更奇异的、尚未观测到的状态。假设DsJ（2317）可能具有4夸克性质，那么信号将是6夸克态的候选者。(2)在亚MeV区测量DsJ（2317）的总宽度。我们计划采用多维拟合与运动学过约束，以达到所需的灵敏度，这已经证明了贝儿是可能的宽度的Ds（2536）和X（3872）。为此，我们将使用衰变Bs -> DsDs（2317）pi 0。与B衰变相比，在Bs衰变中[s sbar]的产生增强了。这种精确分析需要初始状态的运动学变量，而这些变量仅在B（s）衰变中可用，而在连续体中不可用。π 0检测的重建效率比LHCb高约100-1000倍。

We plan the study of narrow, possibly exotic hadronic states in e+e- continuum with the combined, complete BaBar and Belle data sets. This would represent the first combined Belle and BaBar analysis in spectroscopy. The X(4140), and higher similar states discovered recently, of supposedly 4-quark content [c cbar s sbar] have been observed in B meson decays, yet the presently the experimental evidence is controversial. We propose to investigate for the first time the e+e- continuum, which is not available at experiments with hadron collisions.The DsJ(2317) is one of the prime exotic candidate states, as its mass is observed about 160 MeV lower than quark model predictions, which otherwise are very accurate to describe masses of many other charm-strange mesons Our proposal includes:(1) the search for a signal of the X(4140) and similar states in the [DsDs*] invariant mass systems. If a signal is observed, this would represent a second decay channel, and thus establish the states as resonances and exclude the intrepretation as kinematic effects(e.g. thresholds).Without the combination of the BaBar and Belle data sets, this analysis would suffer of insufficient statistics due to low reconstruction efficiency of neutral pions in the DsJ decay.The [J/Psi phi] invariant mass system will be analyzed as well, trying to establish the X(4140) as reference signal.In a second step, the search for even more exotic, yet unobserved states in the[DsDsJ(2317)] invariant mass system. Assuming possibly a 4-quark nature ofthe DsJ(2317), a signal would be a candidate for a 6-quark state.(2) Measurement of the total width of the DsJ(2317) in the sub-MeV regime. We plan to employ multi-dimensional fits with kinematical overconstraints to reach the required sensitivity, which has been already demonstrated by Belle to be possible for the widths of the Ds(2536) and the X(3872). For this purpose, we will use the decay Bs -> DsDs(2317)pi0. In Bs decays, production of [s sbar] is enhanced compared to B decays.This precision analysis requires kinematical variables of the initial state, which are only available in B(s) decays and not in the continuum. The reconstruction efficiency of pi0 detection is a factor ~100-1000 higher than at LHCb.