Measurement of the Cabibbo-Kobayashi-Maskawa AngleγinB∓→D(*)K∓

Abstract

We report on a measurement of the Cabibbo-Kobayashi-Maskawa CP-violating phase gamma through a Dalitz analysis of neutral D decays to K0(S)pi-pi+ in the processes B+/- -->D*K+/-, D*-->Dpi0, Dgamma. Using a sample of 227 x 10(6) BB pairs collected by the BABAR detector, we measure the amplitude ratios r(B)=0.12+/-0.03+/-0.04 and r*(B)=0.17+/-0.10+/-0.03+/-0.03, the relative strong phases delta(B)=(104+/-45(+17+16)(-21-24))degrees and delta*(B)=(-64+/-41(+14)(-12)+/-15) degrees between the amplitudes A(B- -->D*0K-) and A(B- -->D*0)K-), and gamma=(70+/-31(+12+14)(-10-11))degrees. The first error is statistical, the second is the experimental systematic uncertainty, and the third reflects the Dalitz model uncertainty. The results for the strong and weak phases have a twofold ambiguity.

Implications of LHCb measurements and future prospects

“…Due to the fact that r B is required to be positive, the direct extraction of r B , δ B and γ can be biased. To avoid these biases, the "Cartesian coordinates" have been introduced [324] x ± = Re r B e i(δ B ±γ ) ,…”

Measurement of CP violation and constraints on the CKM angle γ inB±→DK±withAaij1, Adeva2, Adinolfi3 et al. 2014Nuclear Physics BSelf Cite

“…Assuming that no direct CP violation exists in the D meson decay, the amplitudes A f and Ā f are related by Ā f (m 2 + , m 2 − ) = A f (m 2 − , m 2 + ). A direct determination of r B , δ B and γ can lead to bias [3], and hence the Cartesian CP violation observables, x ± = r B cos (δ B ± γ ) and y ± = r B sin (δ B ± γ ), are used, where the "+" and "-" indices correspond to B + and B − decays, respectively. This paper reports measurements of (x ± , y ± ) made using B ± → D(→ K 0 S π + π − )K ± decays selected from pp collision data, corresponding to an integrated luminosity of 1 fb −1 , recorded by LHCb at a centre-of-mass energy of 7 TeV in 2011.…”

“…The CKM phase γ (γ ≡ arg[−V ud V * ub /V cd V * cb ], also known as φ 3 ) is the angle of the CKM unitarity triangle that is least constrained by direct measurements. The precise determination of γ is an important aim of current flavour physics experiments.…”

“…The model-dependent approach, as used in Refs. [3][4][5][6][7][8], implements a model to describe the D decay amplitude over the phase space. This unbinned method allows for full exploitation of the statistical power of the data.…”

Model-independent measurement of the CKM angle γ using B0 → DK∗0 decays with D → K S 0 π + π − and K S 0 K+K−

“…(2.6) and (2.7) over the phase space of a Dalitz plot bin are proportional to the expected yield in that bin. The physics parameters of interest, r B 0 , δ B 0 , and γ, are translated into four Cartesian variables [29,30]. These are the measured observables and are defined as…”