Inst High Energy Phys, Beijing 100039, Peoples R China
; CCAST, World Lab, Beijing 100080, Peoples R China
; Nanjing Normal Univ, Dept Phys, Nanjing 210097, Jiangsu, Peoples R China
In this paper, we study and try to find the constraint on the Cabibbo-Kobayashi-Maskawa (CKM) angle alpha from the experimental measurements of CP violation in B-d(0)-->pi(+)pi(-) decay, as reported very recently by the BaBar and Belle Collaborations. After considering the uncertainties of the data and the ratio r of the penguin to the tree amplitudes, we found that a strong constraint on both the CKM angle alpha and the strong phase delta can be obtained from the measured CP asymmetries S-pipi and A(pipi): (a) The ranges of 87degreesless than or equal toalphaless than or equal to131degrees and 36degreesless than or equal todeltaless than or equal to144degrees are allowed by 1sigma of the averaged data for r=0.31; (b) for the Belle result alone, the limits on alpha and delta are 104degreesless than or equal toalphaless than or equal to139degrees and 42degreesless than or equal todeltaless than or equal to138degrees for 0.32less than or equal torless than or equal to0.41; and (c) an angle alpha larger than 90degrees is preferred.