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| Main Authors: | , , , , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2503.00351 |
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| _version_ | 1866912483865788416 |
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| author | Jwa, Seungyeob Kim, Jeehun Kim, Sunghee Lee, Sunkyu Lee, Weonjong Park, Sungwoo |
| author_facet | Jwa, Seungyeob Kim, Jeehun Kim, Sunghee Lee, Sunkyu Lee, Weonjong Park, Sungwoo |
| contents | We present theoretical results for the indirect CP violation parameter, $ |\varepsilon_K| $, evaluated directly within the Standard Model using lattice QCD inputs including $ B_K $, $ |V_{cb}| $, $ |V_{us}| $, $ |V_{ud}| $, $ ξ_0 $, $ ξ_2 $, $ F_K $, and the charm quark mass $ m_c $. Our analysis reveals a significant tension at the $ \sim 5σ$ level ($ 4.6σ$ to $ 5.2σ$) between the Standard Model prediction and the experimental value of $ |\varepsilon_K| $. The Standard Model prediction, informed by lattice QCD inputs, accounts for only approximately 65% of the experimental value, leaving a 35% discrepancy unexplained. Notably, this tension vanishes when using the inclusive determination of $ |V_{cb}| $, derived from heavy quark expansion. The discrepancy is therefore tied to the well-known tension between the exclusive and inclusive determinations of $ |V_{cb}| $. We further report results for $ |\varepsilon_K| $ obtained using the Brod--Gorbahn--Stamou (BGS) method based on $ u\text{--}t $ unitarity, which yields an even stronger discrepancy, in the range of $ 4.9σ$ to $ 5.5σ$, when combined with lattice QCD inputs. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_00351 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | 2025 update on $\varepsilon_K$ in the Standard Model with lattice QCD inputs Jwa, Seungyeob Kim, Jeehun Kim, Sunghee Lee, Sunkyu Lee, Weonjong Park, Sungwoo High Energy Physics - Lattice High Energy Physics - Phenomenology We present theoretical results for the indirect CP violation parameter, $ |\varepsilon_K| $, evaluated directly within the Standard Model using lattice QCD inputs including $ B_K $, $ |V_{cb}| $, $ |V_{us}| $, $ |V_{ud}| $, $ ξ_0 $, $ ξ_2 $, $ F_K $, and the charm quark mass $ m_c $. Our analysis reveals a significant tension at the $ \sim 5σ$ level ($ 4.6σ$ to $ 5.2σ$) between the Standard Model prediction and the experimental value of $ |\varepsilon_K| $. The Standard Model prediction, informed by lattice QCD inputs, accounts for only approximately 65% of the experimental value, leaving a 35% discrepancy unexplained. Notably, this tension vanishes when using the inclusive determination of $ |V_{cb}| $, derived from heavy quark expansion. The discrepancy is therefore tied to the well-known tension between the exclusive and inclusive determinations of $ |V_{cb}| $. We further report results for $ |\varepsilon_K| $ obtained using the Brod--Gorbahn--Stamou (BGS) method based on $ u\text{--}t $ unitarity, which yields an even stronger discrepancy, in the range of $ 4.9σ$ to $ 5.5σ$, when combined with lattice QCD inputs. |
| title | 2025 update on $\varepsilon_K$ in the Standard Model with lattice QCD inputs |
| topic | High Energy Physics - Lattice High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2503.00351 |