Large CP violation in $Λ^0_b \to pK^-π^+π^-$ and its U-spin partner decays
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| Format: | Preprint |
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2025
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| _version_ | 1866915233250934784 |
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| author | He, Xiao-Gang Liu, Chia-Wei Tandean, Jusak |
| author_facet | He, Xiao-Gang Liu, Chia-Wei Tandean, Jusak |
| contents | The LHCb Collaboration has recently found a large CP-violating rate asymmetry in the $b$-baryon decay $Λ^0_b \to pK^-π^+π^-$. This is the first observation of CP violation in baryon processes, opening a new window to test its standard model origin. Many more baryon decays are expected to exhibit observable signals of CP violation. We show that there also exists large CP violation in the U-spin partner decay mode, $Ξ^0_b \to Σ^+π^- K^+K^-$, with rate asymmetry $$A_{CP}(Ξ^0_b \to Σ^+π^- K^+ K^-) = - A_{CP}(Λ^0_b \to p K^- π^+ π^-)~ \frac{Br(Λ^0_b \to p K^- π^+ π^-)}{Br(Ξ^0_b \to Σ^+ π^- K^+ K^-)}~ \frac{τ^{Ξ_b}}{τ^{Λ_b}} $$ in the U-spin symmetry limit. By neglecting a subleading contribution in the amplitudes, we obtain $$A_{CP}(Λ^0_b \to p π^+ π^- π^-) = A_{CP}( Ξ^0_b \to Σ^+π^- K^+ K^-) = -(12 \pm 3 ) \%. $$ These predictions provide crucial tests for the standard model. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2503_24350 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Large CP violation in $Λ^0_b \to pK^-π^+π^-$ and its U-spin partner decays He, Xiao-Gang Liu, Chia-Wei Tandean, Jusak High Energy Physics - Phenomenology High Energy Physics - Experiment The LHCb Collaboration has recently found a large CP-violating rate asymmetry in the $b$-baryon decay $Λ^0_b \to pK^-π^+π^-$. This is the first observation of CP violation in baryon processes, opening a new window to test its standard model origin. Many more baryon decays are expected to exhibit observable signals of CP violation. We show that there also exists large CP violation in the U-spin partner decay mode, $Ξ^0_b \to Σ^+π^- K^+K^-$, with rate asymmetry $$A_{CP}(Ξ^0_b \to Σ^+π^- K^+ K^-) = - A_{CP}(Λ^0_b \to p K^- π^+ π^-)~ \frac{Br(Λ^0_b \to p K^- π^+ π^-)}{Br(Ξ^0_b \to Σ^+ π^- K^+ K^-)}~ \frac{τ^{Ξ_b}}{τ^{Λ_b}} $$ in the U-spin symmetry limit. By neglecting a subleading contribution in the amplitudes, we obtain $$A_{CP}(Λ^0_b \to p π^+ π^- π^-) = A_{CP}( Ξ^0_b \to Σ^+π^- K^+ K^-) = -(12 \pm 3 ) \%. $$ These predictions provide crucial tests for the standard model. |
| title | Large CP violation in $Λ^0_b \to pK^-π^+π^-$ and its U-spin partner decays |
| topic | High Energy Physics - Phenomenology High Energy Physics - Experiment |
| url | https://arxiv.org/abs/2503.24350 |