论文标题
$ {e^ + e^ - } $ {d^{*0} \ bar {d}^0 +γ} $ in $ {e^ + e^ - }中的Charm-Meson Triangle奇异性
Charm-meson Triangle Singularity in ${e^+e^-}$ Annihilation into ${ D^{*0} \bar{D}^0 + γ}$
论文作者
论文摘要
我们将$ e^ + e^ - $ nihilation计算为$ d^{*0} \ bar d^0 +γ$在$ d^{*0} \ bar d^{*0} $ thereshold附近，假设$ x（3872）$ bar d^{*0} \ bar d^{*0} $ threshold是$ x（3872）$ bungiped us bungiped。 Dalitz图具有$ \ bar d^{*0} $共振频段，中的$ \ bar d^0γ$中的不变质量$ t $。在$ d^{*0} $的衰减宽度为0时，达利兹图在平方不变的质量$ u $ of $ d^{*0} \ bar d^0 $中也有一个狭窄的频段，来自符号三角形的三角形奇异。在$ d^{*0} $宽度的物理价值上，狭窄的频带会减少到肩膀上。因此，无法直接观察到差异横截面中的峰值作为$ u $的函数。但是，可以间接将其视为当地最低限度的$ t $分布，对于$ u $以下的$ u $以下的奇异性。最低限度是由三角环图和树图之间的Schmid取消产生的。对此最小值的观察将支持$ x（3872）$作为弱绑定的符号梅森分子的识别。
We calculate the cross section for $e^+ e^-$ annihilation into $D^{*0} \bar D^0 +γ$ at center-of-mass energies near the $D^{*0} \bar D^{*0}$ threshold under the assumption that $X(3872)$ is a weakly bound charm meson molecule. The Dalitz plot has a $\bar D^{*0}$ resonance band in the squared invariant mass $t$ of $\bar D^0 γ$. In the limit as the decay width of the $D^{*0}$ goes to 0, the Dalitz plot also has a narrow band in the squared invariant mass $u$ of $D^{*0} \bar D^0$ from a charm-meson triangle singularity. At the physical value of the $D^{*0}$ width, the narrow band reduces to a shoulder. Thus the triangle singularity cannot be observed directly as a peak in a differential cross section as a function of $u$. It may however be observed indirectly as a local minimum in the $t$ distribution for events with $u$ below the triangle singularity. The minimum is produced by the Schmid cancellation between triangle loop diagrams and a tree diagram. The observation of this minimum would support the identification of $X(3872)$ as a weakly bound charm meson molecule.
