论文标题
$ b $衰减中的U-Spin难题
A U-spin Puzzle in $B$ Decays
论文作者
论文摘要
我们将U Spin Symmetry（$ SU（2）_ {\ rm USPIN} $）施加在$ B $衰减的Hamiltonian上。正如预期的那样，我们发现Exchange $ d \ leftrightarrow s $相关的幅度相等。我们还发现，$δs= 0 $ processes $ b^0 \toπ^+π^ - $，$ b_s^0 \toπ^+ k^ - $和$ b^0 \ to k^+ k^ - $形式的u-Spin三角形关系。 $ b_s^0 \ to k^+k^ - $，$ b^0 \toπ^ - k^+$和$ b_s^0 \toπ^+π^ - $ a $ a $ a $ a $形式的振幅= 1 $δS= 1 $ triangle关系。这两个三角形通过$ d \ leftrightarrow s $相互关联。我们对这六个衰变的可观察物进行拟合。如果假定完美的旋转，则拟合度非常差。如果添加了U-Spin破裂的贡献，我们发现许多可以解释数据的方案。但是，在所有情况下，都需要100 \％U型旋转破裂，比$ \ sim 20 \％$的天真期望大得多。这是U-Spin难题；这可能强烈暗示存在新物理学。
We impose U spin symmetry ($SU(2)_{\rm Uspin}$) on the Hamiltonian for $B$ decays. As expected, we find the equality of amplitudes related by the exchange $d \leftrightarrow s$. We also find that the amplitudes for the $ΔS=0$ processes $B^0 \to π^+π^-$, $B_s^0\toπ^+ K^-$ and $B^0\to K^+ K^-$ form a U-spin triangle relation. The amplitudes for $B_s^0\to K^+ K^-$, $B^0\toπ^- K^+$ and $B_s^0\toπ^+π^-$ form a similar $ΔS=1$ triangle relation. And these two triangles are related to one another by $d \leftrightarrow s$. We perform fits to the observables for these six decays. If perfect U spin is assumed, the fit is very poor. If U-spin-breaking contributions are added, we find many scenarios that can explain the data. However, in all cases, 100\% U-spin breaking is required, considerably larger than the naive expectation of $\sim 20\%$. This is the U-spin puzzle; it may be strongly hinting at the presence of new physics.
