论文标题
在$ b^0 \中搜索深色光子至a^{\ prime} a^{\ prime} $，$ a^{\ prime} \ to e^+ e^ - $，$μ^+μ^ - $，$π^+π^ - $π^+π^ - $ $ $ $ $ $ $ $ $
Search for the dark photon in $B^0 \to A^{\prime} A^{\prime}$, $A^{\prime} \to e^+ e^-$, $μ^+ μ^-$, and $π^+ π^-$ decays at Belle
论文作者
论文摘要
我们向$ b^0 \ in a^{\ prime} a^{\ prime} $衰减中的深色光子$ a^{\ prime} $进行搜索，其中$ a^{\ prime} $随后衰减到$ e^+ e^+ e^+ e^ - $，$，$，$，$，$，$μ^+μ^+μ^ - $ und $ fum和$ ful un和$ ful。搜索是通过分析$ 772 \ times 10^6 $ $ $ b \ overline {b} $事件在kekb $ e^+ e^ - $ $ quenth-qusymmetric collider上收集的$ 772 \ times 10^6 $ $ b \ overline {b} $事件。在深色光子质量范围内找不到信号$ 0.01〜 \ mathrm {gev}/c^2 \ le m_ {a^{a^{\ prime}} \ le 2.62〜 \ mathrm {gev}/c^2 $ 90 \％置信度。分支分数的产品，$ \ Mathcal {b}（b^0 \ to a^{\ prime} a^{\ prime}） a^{\ prime}）\ times \ times \ mathcal {b}（a^{\ prime} \toμ^+μ^ - ）^2 $，其订单的限制为$ 10^{ - 8} $，具体取决于$ a^{\ prime} $质量。此外，考虑到每对带电的粒子的$ a^{\ prime} $衰减率，$ \ Mathcal {b}的上限（b^0 \ to a^{\ prime} a^{\ prime}）$是$ 10^{ - 8} $ 10^$ 10^$ 10^{-5} $的顺序。从$ \ Mathcal {b}的上限（b^0 \到a^{\ prime} a^{\ prime}）$，我们获得了每个假定的深色光子和深色希格斯质量的higgs门户耦合。 higgs门户网站耦合的顺序为$ 10^{ - 2} $ - $ 10^{ - 1} $ at $ m_ { m_ {b^0} \ pm 3〜 \ mathrm {gev}/c^2 $。
We present a search for the dark photon $A^{\prime}$ in the $B^0 \to A^{\prime} A^{\prime}$ decays, where $A^{\prime}$ subsequently decays to $e^+ e^-$, $μ^+ μ^-$, and $π^+ π^-$. The search is performed by analyzing $772 \times 10^6$ $B\overline{B}$ events collected by the Belle detector at the KEKB $e^+ e^-$ energy-asymmetric collider at the $Υ(4S)$ resonance. No signal is found in the dark photon mass range $0.01~\mathrm{GeV}/c^2 \le m_{A^{\prime}} \le 2.62~\mathrm{GeV}/c^2$, and we set upper limits of the branching fraction of $B^0 \to A^{\prime} A^{\prime}$ at the 90\% confidence level. The products of branching fractions, $\mathcal{B}(B^0 \to A^{\prime} A^{\prime}) \times \mathcal{B}(A^{\prime} \to e^+ e^-)^2$ and $\mathcal{B}(B^0 \to A^{\prime} A^{\prime}) \times \mathcal{B}(A^{\prime} \to μ^+ μ^-)^2$, have limits of the order of $10^{-8}$ depending on the $A^{\prime}$ mass. Furthermore, considering $A^{\prime}$ decay rate to each pair of charged particles, the upper limits of $\mathcal{B}(B^0 \to A^{\prime} A^{\prime})$ are of the order of $10^{-8}$-$10^{-5}$. From the upper limits of $\mathcal{B}(B^0 \to A^{\prime} A^{\prime})$, we obtain the Higgs portal coupling for each assumed dark photon and dark Higgs mass. The Higgs portal couplings are of the order of $10^{-2}$-$10^{-1}$ at $m_{h'} \simeq m_{B^0} \pm 40~\mathrm{MeV}/c^2$ and $10^{-1}$-$1$ at $m_{h'} \simeq m_{B^0} \pm 3~\mathrm{GeV}/c^2$.
