Study of the decayD+→K¯0¯

Abstract

We have studied the exclusive semileptonic decay mode /)"*•-»• K^e^Ve in the Fermilab photoproduction experiment E691. We find the ratio BiD^-* K%^Ve)/B (D^-^ K~TT^Ji^) to be 0.66±0.09 ±0.14, corresponding to a Z)"*"-^ K^e^Ve branching ratio of (6.1 ±0.9± 1.6)%. Combining this result with our measurement of the Z> "^ lifetime, we find r(D"^-> ^^^^vj = (5.6±0.8 ± 1.5)x 10'^ s~'. We also find, using E691 averages, the ratio of decay rates r(Z)-* K*ev)/r (D-^ Kev) to be 0.55 ±0.14.PACS numbers: 13.20.Fc, 14.40JzThe exclusive semileptonic decays of mesons containing heavy quarks are particularly interesting because they are the simplest decays to interpret. The strong-interaction effects are completely contained in the form factors, which describe how the final-state quark from the weak decay combines with the spectator quark to produce a final-state meson, or mesons. Because of this simplicity, these decays are used to measure the Cabibbo-Kobayashi-Maskawa matrix elements, which parametrize the mixing between the quark mass eigenstates and the weak eigenstates. The form factors are interesting both because the precise measurement of the Kobayashi-Maskawa elements is important and because the form factors themselves represent a rare window on the structure of heavy mesons. There has been intense theoretical effort on calculating the form factors using both analytical models and lattice gauge techniques [1-9].The matrix element Vcs, which is relevant for Cabibbo-favored charm decays, is known to an error of ±0.001 assuming three-generation unitarity. It is therefore possible to measure the c-•^ form factors using semileptonic decays. There are arguments that these form factors are closely related to those in b-* u semileptonic decays, and will therefore be useful in extracting an accurate value of Vub when exclusive measurements of those decays are available [10].The two dominant semileptonic decays are expected to be D-^Kev and D->K*ev.The decay rates for /)"*" and D^ are equal, by isospin. We have already measured the decay rate r(Z)^^/if "^-^v^) =(9.1 ±0.7 ± 1.7) xlO'^s"' [11], which agrees well with various formfactor calculations. We have also measured the mode D'^-^ K~n^e'^Ve, and have found it to be dominated by the K*^ [12]. For the K* final state, there are three form factors, which we have extracted directly [13]. The resulting form factors do not agree very well with model predictions. In this paper we present a measurement of the decay rate for D^ -^ K^e'^Ve.(Charge-conjugate states are implicitly included throughout this paper.) This gives a second measurement of the Kev form factor with quite different systematic errors.We have used the data from the Fermilab charm photoproduction experiment E691 in this analysis. The apparatus, the Tagged Photon Spectrometer, is an open geometry, two-magnet spectrometer. Photons with energy between 80 and 240 GeV interacted in a 5-cm beryllium target. The charged particles were tracked using silicon microstrip detectors (SMDs) and drift chambers. As in the earlier ...

Effective model for charmed meson semileptonic decays

“…The O(E 0 ) coefficients, A and C, can be expressed in terms of the heavy meson pseudoscalar and vector decay constants f D and f D * , which are equal in the heavy quark limit [11], while no such relations exist between the coefficients B i,k (13) and D i,k (14). However, due to the relationÔ (3) µ u † = −Ô (2) µ u † , only the operatorsÔ (1) µ andÔ (2) µ are important at order O(E).…”

“…Our approach is different than in [7]- [8], where a pole dominance prescription for the q 2 dependence of the form factors was assumed, as in the data analysis of the semileptonic D 0 → K − [13], D + →K 0 [14] and D + →K * 0 [15], [16]. In contrast, we calculate the form factors directly from our Lagrangian.…”

“…The experimental data for the semileptonic decays D 0 → K − [13], D + → K 0 [14] and D + →K * 0 [15], [16] are unfortunately not good enough to clearly determine the q 2 dependence of the form factors. Experimentally what is known, apart from the branching ratios, are the form factors at one kinematical point, assuming a pole-type behaviour for all the form factors.…”

Semileptonic decays of heavy to light mesons from an MIT bag model

“…This parameter depends not only on the created light quark but also can be indirectly influenced by the spectator of the process as we shall show in a moment. Using formulae (25) -(27), (33) and the assumption of pole dependence (5), without any fitting, we obtain the results written in the Tables I, II. The results from Tables I, II agree well with the available data and are…”

Resonant and nonresonantD+→K−π+Bajc1, Fajfer2, Oakes3 et al. 1998Phys. Rev. D160270View full textAdd to dashboardCite

“…It is important to understand this result before making predictions for the other yet unmeasured D → P 1 P 2 lν l decay modes. Furthermore, this could also be helpful in understanding of the D → P lν l [2,3] and D → V lν l data [4,5]. Two main issues arise in the description of D meson semileptonic decays.…”