TY - JOUR

T1 - A lower bound on sin 2β from minimal flavour violation

AU - Buras, Andrzej J.

AU - Buras, Robert

N1 - Funding Information:
We would like to thank Martin Gorbahn for useful discussions and critical comments on the manuscript. This work has been supported in part by the German Bundesministerium für Bildung and Forschung under the contract 05HT9WOA0 and by the Deutsche Forschungsgemeinschaft under grant No. SFB 375.

PY - 2001/3/8

Y1 - 2001/3/8

N2 - We point out that there exists an absolute lower bound on sin 2β in all models with minimal flavour violation (MFV), that do not have any new operators beyond those present in the Standard Model and in which all flavour changing transitions are governed by the CKM matrix with no new phases beyond the KM phase. This bound depends only on |Vcb|, |Vub/Vcb| and the hadronic parameters B̂K, FBd √B̂d and ξ relevant for the CP violating parameter ε and the Bd,s0-B̄d,s0 mixings. Performing a simple scanning over the present ranges of these parameters we find sin 2β ≥ 0.34. We illustrate how this bound could become stronger when our knowledge of the parameters in question improves and when the upper bound on the Bs0-B̄s0 mixing ((ΔM)s) will be experimentally known. Provided the future accurate measurements of sin 2β through the CP asymmetry in Bd0(B̄d0) → ψ KS will confirm the low values recently reported by BaBar and Belle, there is a likely possibility that this class of models will be excluded. This would firmly imply the necessity of new CP violating phases and/or new effective operators in the weak effective Hamiltonians for K0-K̄0 and Bd,s0-B̄d,s0 mixings. We also point out that within the MFV models there exists also an absolute lower bound on the angle γ. We find sin γ ≥ 0.24. This lower bound could become stronger in the future.

AB - We point out that there exists an absolute lower bound on sin 2β in all models with minimal flavour violation (MFV), that do not have any new operators beyond those present in the Standard Model and in which all flavour changing transitions are governed by the CKM matrix with no new phases beyond the KM phase. This bound depends only on |Vcb|, |Vub/Vcb| and the hadronic parameters B̂K, FBd √B̂d and ξ relevant for the CP violating parameter ε and the Bd,s0-B̄d,s0 mixings. Performing a simple scanning over the present ranges of these parameters we find sin 2β ≥ 0.34. We illustrate how this bound could become stronger when our knowledge of the parameters in question improves and when the upper bound on the Bs0-B̄s0 mixing ((ΔM)s) will be experimentally known. Provided the future accurate measurements of sin 2β through the CP asymmetry in Bd0(B̄d0) → ψ KS will confirm the low values recently reported by BaBar and Belle, there is a likely possibility that this class of models will be excluded. This would firmly imply the necessity of new CP violating phases and/or new effective operators in the weak effective Hamiltonians for K0-K̄0 and Bd,s0-B̄d,s0 mixings. We also point out that within the MFV models there exists also an absolute lower bound on the angle γ. We find sin γ ≥ 0.24. This lower bound could become stronger in the future.

UR - http://www.scopus.com/inward/record.url?scp=0035826245&partnerID=8YFLogxK

U2 - 10.1016/S0370-2693(01)00124-1

DO - 10.1016/S0370-2693(01)00124-1

M3 - Article

AN - SCOPUS:0035826245

SN - 0370-2693

VL - 501

SP - 223

EP - 230

JO - Physics Letters B

JF - Physics Letters B

IS - 3-4

ER -