{"title":"在没有(|V_{cb}|\\)和(|V_{ub}|\\\\)不确定性的稀有(K\\)和\\(B\\)衰变中寻找新物理","authors":"A. Buras, E. Venturini","doi":"10.5506/aphyspolb.53.6-a1","DOIUrl":null,"url":null,"abstract":"We reemphasize the strong dependence of the branching ratios $B(K^+\\to\\pi^+\\nu\\bar\\nu)$ and $B(K_L\\to\\pi^0\\nu\\bar\\nu)$ on $|V_{cb}|$ that is stronger than in rare $B$ decays, in particular for $K_L\\to\\pi^0\\nu\\bar\\nu$. Thereby the persistent tension between inclusive and exclusive determinations of $|V_{cb}|$ weakens the power of these theoretically clean decays in the search for new physics (NP). We demonstrate how this uncertainty can be practically removed by considering within the SM suitable ratios of the two branching ratios between each other and with other observables like the branching ratios for $K_S\\to\\mu^+\\mu^-$, $B_{s,d}\\to\\mu^+\\mu^-$ and $B\\to K(K^*)\\nu\\bar\\nu$. We use as basic CKM parameters $V_{us}$, $|V_{cb}|$ and the angles $\\beta$ and $\\gamma$ in the unitarity triangle (UT). This avoids the use of the problematic $|V_{ub}|$. A ratio involving $B(K^+\\to\\pi^+\\nu\\bar\\nu)$ and $B(B_s\\to\\mu^+\\mu^-)$ while being $|V_{cb}|$-independent exhibits sizable dependence on the angle $\\gamma$. It should be of interest for several experimental groups in the coming years. We point out that the $|V_{cb}|$-independent ratio of $B(B^+\\to K^+\\nu\\bar\\nu)$ and $B(B_s\\to\\mu^+\\mu^-)$ from Belle II and LHCb signals a $1.8\\sigma$ tension with its SM value. As a complementary test of the Standard Model, we propose to extract $|V_{cb}|$ from different observables as a function of $\\beta$ and $\\gamma$. We illustrate this with $\\epsilon_K$, $\\Delta M_d$ and $\\Delta M_s$ finding tensions between these three determinations of $|V_{cb}|$ within the SM. From $\\Delta M_s$ and $S_{\\psi K_S}$ alone we find $|V_{cb}|=41.8(6)\\times 10^{-3}$ and $|V_{ub}|=3.65(12)\\times 10^{-3}$. We stress the importance of a precise measurement of $\\gamma$. We obtain most precise SM predictions for considered branching ratios of rare K and B decays to date.","PeriodicalId":7060,"journal":{"name":"Acta Physica Polonica B","volume":null,"pages":null},"PeriodicalIF":0.9000,"publicationDate":"2021-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"20","resultStr":"{\"title\":\"Searching for New Physics in Rare \\\\(K\\\\) and \\\\(B\\\\) Decays without \\\\(|V_{cb}|\\\\) and \\\\(|V_{ub}|\\\\) Uncertainties\",\"authors\":\"A. Buras, E. Venturini\",\"doi\":\"10.5506/aphyspolb.53.6-a1\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"We reemphasize the strong dependence of the branching ratios $B(K^+\\\\to\\\\pi^+\\\\nu\\\\bar\\\\nu)$ and $B(K_L\\\\to\\\\pi^0\\\\nu\\\\bar\\\\nu)$ on $|V_{cb}|$ that is stronger than in rare $B$ decays, in particular for $K_L\\\\to\\\\pi^0\\\\nu\\\\bar\\\\nu$. Thereby the persistent tension between inclusive and exclusive determinations of $|V_{cb}|$ weakens the power of these theoretically clean decays in the search for new physics (NP). We demonstrate how this uncertainty can be practically removed by considering within the SM suitable ratios of the two branching ratios between each other and with other observables like the branching ratios for $K_S\\\\to\\\\mu^+\\\\mu^-$, $B_{s,d}\\\\to\\\\mu^+\\\\mu^-$ and $B\\\\to K(K^*)\\\\nu\\\\bar\\\\nu$. We use as basic CKM parameters $V_{us}$, $|V_{cb}|$ and the angles $\\\\beta$ and $\\\\gamma$ in the unitarity triangle (UT). This avoids the use of the problematic $|V_{ub}|$. A ratio involving $B(K^+\\\\to\\\\pi^+\\\\nu\\\\bar\\\\nu)$ and $B(B_s\\\\to\\\\mu^+\\\\mu^-)$ while being $|V_{cb}|$-independent exhibits sizable dependence on the angle $\\\\gamma$. It should be of interest for several experimental groups in the coming years. We point out that the $|V_{cb}|$-independent ratio of $B(B^+\\\\to K^+\\\\nu\\\\bar\\\\nu)$ and $B(B_s\\\\to\\\\mu^+\\\\mu^-)$ from Belle II and LHCb signals a $1.8\\\\sigma$ tension with its SM value. As a complementary test of the Standard Model, we propose to extract $|V_{cb}|$ from different observables as a function of $\\\\beta$ and $\\\\gamma$. We illustrate this with $\\\\epsilon_K$, $\\\\Delta M_d$ and $\\\\Delta M_s$ finding tensions between these three determinations of $|V_{cb}|$ within the SM. From $\\\\Delta M_s$ and $S_{\\\\psi K_S}$ alone we find $|V_{cb}|=41.8(6)\\\\times 10^{-3}$ and $|V_{ub}|=3.65(12)\\\\times 10^{-3}$. We stress the importance of a precise measurement of $\\\\gamma$. We obtain most precise SM predictions for considered branching ratios of rare K and B decays to date.\",\"PeriodicalId\":7060,\"journal\":{\"name\":\"Acta Physica Polonica B\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.9000,\"publicationDate\":\"2021-09-22\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"20\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Acta Physica Polonica B\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://doi.org/10.5506/aphyspolb.53.6-a1\",\"RegionNum\":4,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"PHYSICS, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Physica Polonica B","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.5506/aphyspolb.53.6-a1","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"PHYSICS, MULTIDISCIPLINARY","Score":null,"Total":0}
Searching for New Physics in Rare \(K\) and \(B\) Decays without \(|V_{cb}|\) and \(|V_{ub}|\) Uncertainties
We reemphasize the strong dependence of the branching ratios $B(K^+\to\pi^+\nu\bar\nu)$ and $B(K_L\to\pi^0\nu\bar\nu)$ on $|V_{cb}|$ that is stronger than in rare $B$ decays, in particular for $K_L\to\pi^0\nu\bar\nu$. Thereby the persistent tension between inclusive and exclusive determinations of $|V_{cb}|$ weakens the power of these theoretically clean decays in the search for new physics (NP). We demonstrate how this uncertainty can be practically removed by considering within the SM suitable ratios of the two branching ratios between each other and with other observables like the branching ratios for $K_S\to\mu^+\mu^-$, $B_{s,d}\to\mu^+\mu^-$ and $B\to K(K^*)\nu\bar\nu$. We use as basic CKM parameters $V_{us}$, $|V_{cb}|$ and the angles $\beta$ and $\gamma$ in the unitarity triangle (UT). This avoids the use of the problematic $|V_{ub}|$. A ratio involving $B(K^+\to\pi^+\nu\bar\nu)$ and $B(B_s\to\mu^+\mu^-)$ while being $|V_{cb}|$-independent exhibits sizable dependence on the angle $\gamma$. It should be of interest for several experimental groups in the coming years. We point out that the $|V_{cb}|$-independent ratio of $B(B^+\to K^+\nu\bar\nu)$ and $B(B_s\to\mu^+\mu^-)$ from Belle II and LHCb signals a $1.8\sigma$ tension with its SM value. As a complementary test of the Standard Model, we propose to extract $|V_{cb}|$ from different observables as a function of $\beta$ and $\gamma$. We illustrate this with $\epsilon_K$, $\Delta M_d$ and $\Delta M_s$ finding tensions between these three determinations of $|V_{cb}|$ within the SM. From $\Delta M_s$ and $S_{\psi K_S}$ alone we find $|V_{cb}|=41.8(6)\times 10^{-3}$ and $|V_{ub}|=3.65(12)\times 10^{-3}$. We stress the importance of a precise measurement of $\gamma$. We obtain most precise SM predictions for considered branching ratios of rare K and B decays to date.
期刊介绍:
Acta Physica Polonica B covers the following areas of physics:
-General and Mathematical Physics-
Particle Physics and Field Theory-
Nuclear Physics-
Theory of Relativity and Astrophysics-
Statistical Physics