249 research outputs found
Dalitz plot analyses of B-0 -> (D-DK+)-K-0 and B+-> (D)over-bar(-)D(0)K(+) decays
No full text© 2015, APS Journal
Model-independent extraction of form factors and |Vcb | in B ̄ →d?- ν ̄ ? with hadronic tagging at BABAR
No full textUsing the entire BABAR ?(4S) dataset, the first two-dimensional unbinned angular analysis of the semileptonic decay B ̄→D?-ν ̄? is performed, employing hadronic reconstruction of the tag-side B meson from ?(4S)→BB ̄. Here, ? denotes the light charged leptons e and μ. A novel data-driven signal-background separation procedure with minimal dependence on simulation is developed. This procedure preserves all multidimensional correlations present in the data. The expected sin2θ? dependence of the differential decay rate in the Standard Model is demonstrated, where θ? is the lepton helicity angle. Including input from the latest lattice QCD calculations and previously available experimental data, the underlying form factors are extracted using both model-independent (BGL) and dependent (CLN) methods. Comparisons with lattice calculations show flavor SU(3) symmetry to be a good approximation in the B(s)→D(s) sector. Using the BGL results, the CKM matrix element |Vcb|=(41.09±1.16)×10-3 and the Standard Model prediction of the lepton-flavor universality violation variable R(D)=0.300±0.004, are extracted. The value of |Vcb| from B ̄→D?-ν ̄? tends to be higher than that extracted using B ̄→D∗?-ν ̄?. The Standard Model R(D) calculation is at a 1.97σ tension with the latest HFLAV experimental average
Model-independent extraction of form factors and |Vcb| in B ̄ → D l− νbarl with hadronic tagging at BABAR
No full textUsing the entire BABAR ?(4S) dataset, the first two-dimensional unbinned angular analysis of the semileptonic decay B ̄→D?-ν ̄? is performed, employing hadronic reconstruction of the tag-side B meson from ?(4S)→BB ̄. Here, ? denotes the light charged leptons e and μ. A novel data-driven signal-background separation procedure with minimal dependence on simulation is developed. This procedure preserves all multidimensional correlations present in the data. The expected sin2θ? dependence of the differential decay rate in the Standard Model is demonstrated, where θ? is the lepton helicity angle. Including input from the latest lattice QCD calculations and previously available experimental data, the underlying form factors are extracted using both model-independent (BGL) and dependent (CLN) methods. Comparisons with lattice calculations show flavor SU(3) symmetry to be a good approximation in the B(s)→D(s) sector. Using the BGL results, the CKM matrix element |Vcb|=(41.09±1.16)×10-3 and the Standard Model prediction of the lepton-flavor universality violation variable R(D)=0.300±0.004, are extracted. The value of |Vcb| from B ̄→D?-ν ̄? tends to be higher than that extracted using B ̄→D∗?-ν ̄?. The Standard Model R(D) calculation is at a 1.97σ tension with the latest HFLAV experimental average. (BaBar Collaboration
Measurement of an excess of [¯ over B] → D[superscript (*)]τ[superscript -]ν[¯ over v][subscript τ] decays and implications for charged Higgs bosons
No full textBased on the full BABAR data sample, we report improved measurements of the ratios R(D) = B([¯ over B] → D[subscript τ][superscript −][¯ over v][subscript τ])/B([¯ over B] → Dℓ[superscript −][¯ over v]ℓ) and R(D[superscript *]) = B([¯ over B] → D[superscript *]τ[superscript −][¯ over v][subscript τ])/B([¯ over B] → D[superscript *]ℓ[superscript −][¯ over v][subscript ℓ]), where ℓ refers to either an electron or muon. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D) = 0.440 ± 0.058 ± 0.042 and R(D[superscript *]) = 0.332 ± 0.024 ± 0.018, which exceed the standard model expectations by 2.0σ and 2.7σ, respectively. Taken together, the results disagree with these expectations at the 3.4σ level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. Kinematic distributions presented here exclude large portions of the more general type III two-Higgs-doublet model, but there are solutions within this model compatible with the results.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
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Measurement of the time-dependent CP asymmetry of partially reconstructed B[superscript 0]→D[superscript *+]D[superscript *-] decays
No full textWe present a new measurement of the time-dependent CP asymmetry of B[superscript 0]→D[superscript *+]D[superscript *-] decays using (471±5) million BB̅ pairs collected with the BABAR detector at the PEP-II B Factory at the SLAC National Accelerator Laboratory. Using the technique of partial reconstruction, we measure the time-dependent CP asymmetry parameters S=-0.34±0.12±0.05 and C=+0.15±0.09±0.04. Using the value for the CP-odd fraction R[subscript ⊥]=0.158±0.028±0.006, previously measured by BABAR with fully reconstructed B[superscript 0]→D[superscript *+]D[superscript *-] events, we extract the CP-even components S+=-0.49±0.18±0.07±0.04 and C+=+0.15±0.09±0.04. In each case, the first uncertainty is statistical and the second is systematic; the third uncertainty on S+ is the contribution from the uncertainty on R[subscript ⊥]. The measured value of the CP-even component S+ is consistent with the value of sin2β measured in b→(cc̅ )s transitions, and with the Standard Model expectation of small penguin contributions.United States. Dept. of EnergyNational Science Foundation (U.S.
Dalitz plot analyses of B-0 -> (D-DK+)-K-0 and B+-> (D)over-bar(-)D(0)K(+) decays
No full textWe present Dalitz plot analyses for the decays of B mesons to (D-DK+)-K-0 and (D) over bar (DK+)-D-0-K-0. We report the observation of the D*(s1)(2700)(+) resonance in these two channels and obtain measurements of the mass M(D*(s1)(2700)(+)) = 2699(-7)(+14) MeV/c(2) and of the width Gamma(D*(s1)(2700)(+)) = 127(-19)(+24) MeV, including statistical and systematic uncertainties. In addition, we observe an enhancement in the (DK+)-K-0 invariant mass around 2350-2500 MeV/c(2) in both decays B-0 -> (D-DK+)-K-0 and B+ -> (D) over bar (DK+)-D-0-K-0, which we are not able to interpret. The results are based on 429 fb(-1) of data containing 471 x 10(6) B (B) over bar pairs collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory
Measurement of the mass of the D[superscript 0] meson
No full textWe report a measurement of the D[superscript 0] meson mass using the decay chain D[superscript *](2010)[superscript +] → D[superscript 0]π[superscript +] with D[superscript 0] → K[superscript −]K[superscript −]K[superscript +]π[superscript +]. The data were recorded with the BABAR detector at center-of-mass energies at and near the Υ(4S) resonance, and correspond to an integrated luminosity of approximately 477 fb[superscript −1]. We obtain m(D[superscript 0]) = (1864.841 ± 0.048 ± 0.063) MeV, where the quoted errors are statistical and systematic, respectively. The uncertainty of this measurement is half that of the best previous measurement.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
Evidence for an Excess of B[over ¯]→D^{(*)}τ^{-}ν[over ¯]_{τ} Decays
No full textBased on the full BABAR data sample, we report improved measurements of the ratios R(D(*))=B(B̅ →D(*)τ-ν̅ τ)/B(B̅ →D(*)ℓℓ-ν̅ ℓ), where ℓ is either e or μ. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D)=0.440±0.058±0.042 and R(D*)=0.332±0.024±0.018, which exceed the standard model expectations by 2.0σ and 2.7σ, respectively. Taken together, our results disagree with these expectations at the 3.4σ level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model
Search for the decay modes D-0 -> e(+) e(-), D-0 -> mu(+) mu(-), and D-0 -> e(+/-) mu -/+
No full textWe present searches for the rare decay modes D-0 -> e(+) e(-), D-0 -> mu(+) mu(-), and D-0 -> e(+/-) mu(-/+) in continuum e(+) e(-) -> c (c) over bar events recorded by the BABAR detector in a data sample that corresponds to an integrated luminosity of 468 fb(-1). These decays are highly Glashow-Iliopoulos-Maiani suppressed but may be enhanced in several extensions of the standard model. Our observed event yields are consistent with the expected backgrounds. An excess is seen in the D-0 -> mu(+) mu(-) channel, although the observed yield is consistent with an upward background fluctuation at the 5% level. Using the Feldman-Cousins method, we set the following 90% confidence level intervals on the branching fractions: B(D-0 -> e(+) e(-)) mu(+) mu(-)) within [0.6,8.1] x 10(-7), and B(D-0 -> e(+/-) mu(-/+)) < 3.3 x 10(-7)
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Search for b→u transitions in B^{±}→[K^{∓}π^{±}π^{0}]_{D}K^{±} decays
No full textWe present a study of the decays B±→DK± with D mesons reconstructed in the K+π−π0 or K−π+π0 final states, where D indicates a D0 or a D⎯⎯⎯0 meson. Using a sample of 474×106 BB⎯⎯⎯ pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e− collider at SLAC, we measure the ratios R±≡Γ(B±→[K∓π±π0]DK±)Γ(B±→[K±π∓π0]DK±). We obtain R+=(5+12−10(stat)+2−4(syst))×10−3 and R−=(12+12−10(stat)+3−5(syst))×10−3, from which we extract the upper limits at 90% probability: R+<23×10−3 and R−<29×10−3. Using these measurements, we obtain an upper limit for the ratio rB of the magnitudes of the b→u and b→c amplitudes rB<0.13 at 90% probability.PhysicsAccepted Manuscrip
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