Search for $B \to π\ell^+\ell^-$ Decays at Belle

Wei, J. -T.; Chen, K. -F.

doi:10.48550/arxiv.0804.3656

Cited by 7 publications

(13 citation statements)

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“…LHCb [1] Belle [2] BaBar [3] B + → π + µ + µ − 2.3 ± 0.6 ± 0.1 < 6.9 < 5.5 B + → π + e + e − -< 8.0 < 12.5 B + → π + ℓ + ℓ − -< 4.9 < 6.6…”

Section: Modementioning

confidence: 99%

“…For better theoretical control, we limit our analysis in the 2 GeV 2 < q 2 < 6 GeV 2 region where the QCDF approach is expected to work, while the resonance contaminations would also be avoided. 2 The choice of q 2 range would be, however, rather subjective, given the lack of actual data and model-independent studies 3 on B → πℓ + ℓ − around the resonant regions. Indeed, choices of wider q 2 ranges can be found in literature, e.g., 1 GeV 2 < q 2 < 6 GeV 2 adopted in a study [15] of the closely related process B → ρℓ + ℓ − based on QCDF, or 1 GeV 2 < q 2 < 8 GeV 2 adopted as the low-q 2 region in a study [7] of B ± → π ± ℓ + ℓ − based on naive factorization with the heavy quark limit.…”

Section: Basic Formulas and Inputmentioning

confidence: 99%

“…at 5.2 σ significance. This is the first observation of a flavor changing neutral current (FCNC) b → dℓ + ℓ − transition, as the B factories were only able to set limits [2,3]. We summarize relevant data in Table I.…”

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confidence: 99%

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Rates and asymmetries ofB→πℓ+ℓ−decays

Hou

Kohda

2014

Phys. Rev. D

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The LHCb experiment observed B + → π + µ + µ − decay with 1.0 fb −1 data, which is the first measurement of a flavor changing neutral current b → dℓ + ℓ − decay (ℓ = e, µ). Based on QCD factorization, we give Standard Model predictions for the branching ratios, direct CP asymmetries, and isospin asymmetry for B → πℓ + ℓ − decays, in the kinematic region where the dilepton invariant mass is small. We find that the contribution from weak annihilation enhances the direct CP asymmetry for low ℓ + ℓ − pair mass. Anticipating improved measurements, we assess the utility offor determining CKM parameters in the future. PACS numbers: 12.15.Hh 11.30.Er 13.20.He 1 As for B → K ( * ) ℓ + ℓ − /ρℓ + ℓ − , isospin asymmetries were also are of great interest even within SM because V * ud V ub carries CPV phase. In contrast, such effects are suppressed by V * us V ub for b → sℓ + ℓ − processes. The B → πℓ + ℓ − modes may also be used to probe New Physics, such as two Higgs doublet model [4, 5], R-parity violating supersymmetry [6], and fourth generation [18].This paper is a followup of the last paper, where some results were used in conjunction with the study of B d → µ + µ − mode. In this paper we focus on SM expectations for B → πℓ + ℓ − . After presenting the basic formulas and input parameters in Sec. II, the SM predictions are given in Sec. III. We discuss prospects for constraining CKM parameters in Sec. IV, before giving our conclusion. Some details are placed in Appendices. studied [16] employing light-cone sum rule to calculate matrix elements for weak annihilation and O 8 [in Eq. (4)] [17].

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“…LHCb [1] Belle [2] BaBar [3] B + → π + µ + µ − 2.3 ± 0.6 ± 0.1 < 6.9 < 5.5 B + → π + e + e − -< 8.0 < 12.5 B + → π + ℓ + ℓ − -< 4.9 < 6.6…”

Section: Modementioning

confidence: 99%

Section: Basic Formulas and Inputmentioning

confidence: 99%

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Rates and asymmetries ofB→πℓ+ℓ−decays

Hou

Kohda

2014

Phys. Rev. D

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“…Quark flavor hierarchies in the SM predict b → d transitions to be suppressed with respect to b → s ones, in agreement with the observed values of ∆m d,s and the b → (s, d)γ rates. It is open to test this CKM-feature for semileptonic decays as well, where first data on B → πl + l − [20] have just become available. My favorite semi-near term questions for B decays with l + l − are: A FB (at low q 2 ), B(B s → µ + µ − ), R K,X s (improved), F l H , B(B d → µ + µ − )/B(B s → µ + µ − ), A i(T ) .…”

Section: Discussionmentioning

confidence: 99%

Theoretical Status of Rare B Decays with Muons

Hiller¹,

Bobeth²,

Piranishvili³

2010

Proceedings of 12th International Conference on B-Physics at Hadron Machines — PoS(BEAUTY 2009)

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“…Other than that, upper limits on exclusive decays include Belle constraint Br(B + → π + + − ) < 4.9 • 10 −8 (90% C.L.) [91] and BaBar result [92]:…”

Section: The Sm With Extra Vector-like Fermionsmentioning

confidence: 99%

Are the CKM anomalies induced by vector-like quarks? Limits from flavor changing and Standard Model precision tests

Belfatto,

Berezhiani

2021

Preprint

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Recent high precision determinations of V us and V ud indicate towards anomalies in the first row of the CKM matrix. Namely, determination of V ud from superallowed beta decays and of V us from kaon decays imply a violation of first row unitarity at about 4σ level. Moreover, there is tension between determinations of V us obtained from leptonic Kµ2 and semileptonic K 3 kaon decays. These discrepancies can be explained if there exist extra vector-like quarks at the TeV scale, which have large enough mixings with the lighter quarks. In particular, extra vector-like weak singlets quarks can be thought as a solution to the CKM unitarity problem and an extra vector-like weak doublet can in principle resolve all tensions. The implications of this kind of mixings are examined against the flavour changing phenomena and SM precision tests. We consider separately the effects of an extra down-type isosinglet, up-type isosinglet and an isodoublet containing extra quarks of both up and down type, and determine available parameter spaces for each case. We find that the experimental constraints on flavor changing phenomena become more stringent with larger masses, so that the extra species should have masses no more than few TeV. Moreover, only one type of extra multiplet cannot entirely explain all the discrepancies, and some their combination is required, e.g. two species of isodoublet, or one isodoublet and one (up or down type) isosinglet. We show that these scenarios are testable with future experiments. Namely, if extra vector-like quarks are responsible for CKM anomalies, then at least one of them should be found at scale of few TeV, and anomalous weak isospin violating Z-boson couplings with light quarks should be detected if the experimental precision on Z hadronic decay rate is improved by a factor of 2 or so.

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Search for $B \to π\ell^+\ell^-$ Decays at Belle

Cited by 7 publications

References 0 publications

Rates and asymmetries ofB→πℓ+ℓ−decays

Rates and asymmetries ofB→πℓ+ℓ−decays

Theoretical Status of Rare B Decays with Muons

Are the CKM anomalies induced by vector-like quarks? Limits from flavor changing and Standard Model precision tests

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