Showing papers by "B. G. Fulsom published in 2019"

Measurement of the CKM matrix element vertical bar V-cb vertical bar from B-0 -˃ D*(-)l(+)nu(l) at Belle

Abstract: We present a new measurement of the Cabibbo-Kobayashi-Maskawa matrix element |Vcb| from B0→D*-l+νl decays, reconstructed with the full Belle data set of 711 fb−1 integrated luminosity. Two form factor parametrizations, originally conceived by the Caprini-Lellouch-Neubert (CLN) and the Boyd, Grinstein and Lebed (BGL) groups, are used to extract the product F(1)ηEW|Vcb| and the decay form factors, where F(1) is the normalization factor and ηEW is a small electroweak correction. In the CLN parametrization we find F(1)ηEW|Vcb|=(35.06±0.15±0.56)×10-3, ρ2=1.106±0.031±0.007, R1(1)=1.229±0.028±0.009, R2(1)=0.852±0.021±0.006. For the BGL parametrization we obtain F(1)ηEW|Vcb|=(34.93±0.23±0.59)×10-3, which is consistent with the world average when correcting for F(1)ηEW. The branching fraction of B0→D*-l+νl is measured to be B(B0→D*-l+νl)=(4.90±0.02±0.16)%. We also present a new test of lepton flavor universality violation in semileptonic B decays, B(B0→D*-e+ν)B(B0→D*-μ+ν)=1.01±0.01±0.03. The errors quoted correspond to the statistical and systematic uncertainties, respectively. This is the most precise measurement of F(1)ηEW|Vcb| and form factors to date and the first experimental study of the BGL form factor parametrization in an experimental measurement.

Test of lepton flavor universality and search for lepton flavor violation in $B \to K \ell\ell$ decays

Abstract: We present measurements of the branching fractions for the decays $B\to K \mu^{+}\mu^{-}$ and $B\to K e^{+}e^{-}$, and their ratio ($R_{K}$), using a data sample of 711 $fb^{-1}$ that contains $772 \times 10^{6}$ $B\bar{B}$ events. The data were collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The ratio $R_{K}$ is measured in five bins of dilepton invariant-mass-squared ($q^{2}$): $q^{2} \in (0.1, 4.0), (4.0, 8.12), (1.0, 6.0)$, $(10.2, 12.8)$ and ($>14.18) GeV^{2}/c^{4}$, along with the whole $q^2$ region. The $R_{K}$ value for $q^{2} \in (1.0, 6.0) GeV^{2}/c^{4}$ is $1.03^{+0.28}_{-0.24} \pm 0.01$. The first and second uncertainties listed are statistical and systematic, respectively. All results for $R_{K}$ are consistent with Standard Model predictions. We also measure $C\!P$-averaged isospin asymmetries in the same $q^{2}$ bins. The results are consistent with a null asymmetry, with the largest difference of 2.6 standard deviations occurring for the $q^{2}\in(1.0,6.0) GeV^{2}/c^{4}$ bin in the mode with muon final states. The measured differential branching fractions, ${d\cal B}/{dq^{2}}$, are consistent with theoretical predictions for charged $B$ decays, while the corresponding values are below the expectations for neutral $B$ decays. We have also searched for lepton-flavor-violating $B \rightarrow K\mu^{\pm}e^{\mp}$ decays and set $90\%$ confidence-level upper limits on the branching fraction in the range of $10^{-8}$ for $B^{+} \rightarrow K^{+}\mu^{\pm}e^{\mp}$, and $B^{0} \rightarrow K^{0}\mu^{\pm}e^{\mp}$ modes.

First measurements of absolute branching fractions of the Xi(+)(c) baryon at Belle

Abstract: We present the first measurements of the absolute branching fractions of $\Xi_c^+$ decays into $\Xi^- \pi^+ \pi^+$ and $p K^- \pi^+$ final states. Our analysis is based on a data set of $(772\pm 11)\times 10^{6}$ $B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB $e^+e^-$ collider. We measure the absolute branching fraction of $\bar{B}^{0} \to \bar{\Lambda}_{c}^{-} \Xi_{c}^{+}$ with the $\Xi_c^+$ recoiling against $\bar{\Lambda}_c^-$ in $\bar{B}^0$ decays resulting in ${\cal B}(\bar{B}^{0} \to \bar{\Lambda}_{c}^{-} \Xi_{c}^{+}) = [1.16 \pm 0.42(\rm stat.) \pm 0.15(\rm syst.)] \times 10^{-3}$. We then measure the product branching fractions ${\cal B}(\bar{B}^{0} \to \bar{\Lambda}_c^- \Xi_c^+){\cal B}(\Xi_c^+ \to \Xi^- \pi^+ \pi^+)$ and ${\cal B}(\bar{B}^{0} \to \bar{\Lambda}_c^- \Xi_c^+){\cal B}(\Xi_c^+ \to p K^- \pi^+)$. Dividing these product branching fractions by $\bar{B}^{0} \to \bar{\Lambda}_{c}^{-} \Xi_{c}^{+}$ yields: ${\cal B}(\Xi_c^+ \to \Xi^- \pi^+ \pi^+) = [2.86 \pm 1.21(\rm stat.) \pm 0.38(\rm syst.)]\%$ and ${\cal B}(\Xi_c^+ \to p K^- \pi^+)=[0.45 \pm 0.21(\rm stat.) \pm 0.07(\rm syst.)]\%$. Our result for ${\cal B}(\Xi_c^+ \to \Xi^- \pi^+ \pi^+)$ can be combined with $\Xi_c^+$ branching fractions measured relative to $\Xi_c^+ \to \Xi^- \pi^+ \pi^+$ to set the absolute scale for many $\Xi_c^+$ branching fractions.

Observation of a new structure near 10.75 GeV in the energy dependence of the $e^+e^-\to\Upsilon(nS)\pi^+\pi^-$ ($n=1,2,3$) cross sections

Abstract: We report a new measurement of the $e^+e^-\to\Upsilon(nS)\pi^+\pi^-$ ($n=1,2,3$) cross sections at energies from 10.52 to 11.02 GeV using data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We observe a new structure in the energy dependence of the cross sections; if described by a Breit-Wigner function its mass and width are found to be $M=(10752.7\pm5.9\,^{+0.7}_{-1.1})\,$MeV/$c^2$ and $\Gamma=(35.5^{+17.6}_{-11.3}\,^{+3.9}_{-3.3})\,$MeV, where the first error is statistical and the second is systematic. The global significance of the new structure including systematic uncertainty is 5.2 standard deviations. We also find evidence for the $e^+e^-\to\Upsilon(1S)\pi^+\pi^-$ process at the energy 10.52 GeV, which is below the $B\bar{B}$ threshold.

Search for $\Omega(2012)\to K\Xi(1530) \to K\pi\Xi$ at Belle

Abstract: Using data samples of e+e- collisions collected at the ϒ(1S), ϒ(2S), and ϒ(3S) resonances with the Belle detector, we search for the three-body decay of the Ω(2012) baryon to KπΞ. This decay is predicted to dominate for models describing the Ω(2012) as a KΞ(1530) molecule. No significant Ω(2012) signals are observed in the studied channels, and 90% credibility level upper limits on the ratios of the branching fractions relative to KΞ decay modes are obtained.

Extraction of form Factors from a Four-Dimensional Angular Analysis of B →d∗-ν

Abstract: An angular analysis of the decay B[over ¯]→D^{*}l^{-}ν[over ¯]_{l}, l∈{e,μ}, is reported using the full e^{+}e^{-} collision data set collected by the BABAR experiment at the ϒ(4S) resonance. One B meson from the ϒ(4S)→BB[over ¯] decay is fully reconstructed in a hadronic decay mode, which constrains the kinematics and provides a determination of the neutrino momentum vector. The kinematics of the semileptonic decay is described by the dilepton mass squared, q^{2}, and three angles. The first unbinned fit to the full four-dimensional decay rate in the standard model is performed in the so-called Boyd-Grinstein-Lebed approach, which employs a generic q^{2} parametrization of the underlying form factors based on crossing symmetry, analyticity, and QCD dispersion relations for the amplitudes. A fit using the more model-dependent Caprini-Lellouch-Neubert (CLN) approach is performed as well. Our form factor shapes show deviations from previous fits based on the CLN parametrization. The latest form factors also provide an updated prediction for the branching fraction ratio R(D^{*})≡B(B[over ¯]→D^{*}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]→D^{*}l^{-}ν[over ¯]_{l})=0.253±0.005. Finally, using the well-measured branching fraction for the B[over ¯]→D^{*}l^{-}ν[over ¯]_{l} decay, a value of |V_{cb}|=(38.36±0.90)×10^{-3} is obtained that is consistent with the current world average for exclusive B[over ¯]→D^{(*)}l^{-}ν[over ¯]_{l} decays and remains in tension with the determination from inclusive semileptonic B decays to final states with charm.

Search for X(3872) and X(3915) decay into chi(c1)pi(0) in B decays at Belle

Abstract: We report a search for X(3872) and X(3915) in B+→χc1π0K+ decays. We set an upper limit of B(B+→X(3872)K+)×B(X(3872)→χc1π0)<8.1×10-6 and B(B+→X(3915)K+)×B(X(3915)→χc1π0)<3.8×10-5 at 90% confidence level. We also measure B(X(3872)→χc1π0)/B(X(3872)→J/ψπ+π-)<0.97 at 90% confidence level. The results reported here are obtained from 772×106 BB¯ events collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

Measurement of the $D^{\ast-}$ polarization in the decay $B^0 \to D^{\ast -}\tau^+\nu_{\tau}$.

Abstract: We report the first measurement of the $D^{\ast -}$ meson polarization in the decay $B^0 \to D^{*-} \tau^+ u_{\tau}$ using the full data sample of 772$\times 10^6$ $B\bar{B}$ pairs recorded with the Belle detector at the KEKB electron-positron collider. Our result, $F_L^{D^\ast} = 0.60 \pm 0.08 ({\rm stat}) \pm 0.04 ({\rm sys})$, where $F_L^{D^\ast}$ denotes the $D^{\ast-}$ meson longitudinal polarization fraction, agrees within about $1.7$ standard deviations of the standard model prediction.

Azimuthal asymmetries of back-to-back π±- (π0, η, π±) pairs in e+e- annihilation

Abstract: This work reports the first observation of azimuthal asymmetries around the thrust axis in e+e- annihilation of pairs of back-to-back charged pions in one hemisphere, and π0 and η mesons in the opposite hemisphere. These results are complemented by a new analysis of pairs of back-to-back charged pions. The π0 and η asymmetries rise with the relative momentum z of the detected hadrons as well as with the transverse momentum with respect to the thrust axis. These asymmetries are sensitive to the Collins fragmentation function H1⊥ and provide complementary information to previous measurements with charged pions and kaons in the final state. In particular, the η final states will provide additional information on the flavor structure of H1⊥. This is the first measurement of the explicit transverse-momentum dependence of the Collins fragmentation function from Belle data. It uses a dataset of 980.4 fb-1 collected by the Belle experiment at or near a center-of-mass energy of 10.58 GeV.

Evidence for B+ -> h(c)K(+) and observation of eta(c()2S) -> p(p)over-bar pi(+)pi(-)

Abstract: A search for the decays B+→hcK+ and B0→hcKS0 is performed. Evidence for the decay B+→hcK+ is found; its significance is 4.8σ. No evidence is found for B0→hcKS0. The branching fraction for B+→hcK+ is measured to be (3.7-0.9+1.0 -0.8+0.8)×10-5; the upper limit for the B0→hcKS0 branching fraction is 1.4×10-5 at 90% C.L. In addition, a study of the pp¯π+π- invariant mass distribution in the channel B+→(pp¯π+π-)K+ results in the first observation of the decay ηc(2S)→pp¯π+π- with 12.1σ significance. The analysis is based on the 711 fb-1 data sample collected by the Belle detector at the asymmetric-energy e+e- collider KEKB at the ϒ(4S) resonance.

First measurement of the CKM angle $\phi_3$ with $B^{\pm}\to D(K_{\rm S}^0\pi^+\pi^-\pi^0)K^{\pm}$ decays

Abstract: We present the first model-independent measurement of the CKM unitarity triangle angle $\phi_3$ using $B^{\pm}\to D(K_{\rm S}^0\pi^+\pi^-\pi^0)K^{\pm}$ decays, where $D$ indicates either a $D^{0}$ or $\overline{D}^{0}$ meson. Measurements of the strong-phase difference of the $D \to K_{\rm S}^0\pi^+\pi^-\pi^0$ amplitude obtained from CLEO-c data are used as input. This analysis is based on the full Belle data set of $772\times 10^{6}$ $B\overline{B}$ events collected at the $\Upsilon(4S)$ resonance. We obtain $\phi_3 = (5.7~^{+10.2}_{-8.8} \pm 3.5 \pm 5.7)^{\circ}$ and the suppressed amplitude ratio $r_{B} = 0.323 \pm 0.147 \pm 0.023 \pm 0.051$. Here the first uncertainty is statistical, the second is the experimental systematic, and the third is due to the precision of the strong-phase parameters measured from CLEO-c data. The 95% confidence interval on $\phi_3$ is $(-29.7,~109.5)^{\circ}$, which is consistent with the current world average.

Observation of the Decay D^{0}→K^{-}π^{+}e^{+}e^{-}.

Abstract: We report the observation of the rare charm decay D^{0}→K^{-}π^{+}e^{+}e^{-}, based on 468 fb^{-1} of e^{+}e^{-} annihilation data collected at or close to the center-of-mass energy of the ϒ(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. We find the branching fraction in the invariant mass range 0.675

Search for CP violation with kinematic asymmetries in the D0 →k+K-π+π- decay

Abstract: We search for CP violation in the singly-Cabibbo-suppressed decay D0→K+K-π+π- using data corresponding to an integrated luminosity of 988 fb-1 collected by the Belle detector at the KEKB e+e- collider. We measure a set of five kinematically dependent CP asymmetries, of which four asymmetries are measured for the first time. The set of asymmetry measurements can be sensitive to CP violation via interference between the different partial-wave contributions to the decay and performed on other pseudoscalar decays. We find no evidence of CP violation.

Evidence for the decay $B^0\to p\bar{p}\pi^0$

Abstract: We report a search for the charmless baryonic decay $B^0\to p\bar{p}\pi^0$ with a data sample corresponding to an integrated luminosity of 711~$\rm fb^{-1}$ containing $(772\pm 10)\times 10^6$ $B^0\bar{B}^0$ pairs. The data was collected by the Belle experiment running on the $\Upsilon(4S)$ resonance at the KEKB $e^+e^-$ collider. We measure a branching fraction $\mathcal{B}(B^0\to p\bar{p}\pi^0)= (5.0\pm1.8\pm0.6 )\times 10^{-7}$, where the first uncertainty is statistical and the second is systematic. The signal has a significance of 3.1 standard deviations and constitutes the first evidence for this decay mode. We also search for the intermediate two-body decays $B^{0}\to\Delta^+\bar{p}$ and $B^0\to\bar{\Delta}^-p$, and set an upper limit on the branching fraction: $\mathcal{B}(B^0\to \Delta^+\bar{p})+\mathcal{B}(B^0\to\bar{\Delta}^-p)<1.6\times10^{-6}$ at 90% confidence level.

Measurement of branching fraction and final-state asymmetry for the B¯0→KS0K∓π± decay

Abstract: We report a measurement of the branching fraction and final-state asymmetry for the $\bar{B}^{0}\to K^{0}_{S}K^{\mp}\pi^{\pm}$ decays. The analysis is based on a data sample of 711 $\rm{fb}^{-1}$ collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. We obtain a branching fraction of $(3.60\pm0.33\pm0.15)\times10^{-6}$ and a final-state asymmetry of $(-8.5\pm8.9\pm0.2)\%$, where the first uncertainties are statistical and the second are systematic. Hints of peaking structures are seen in the differential branching fractions measured as functions of Dalitz variables.

Observation of $B^{+} \rightarrow p\bar{\Lambda} K^+ K^-$ and $B^{+} \rightarrow \bar{p}\Lambda K^+ K^+$

Abstract: We report the study of B+→pΛ¯K+K- and B+→p¯ΛK+K+ decays using a 772×106 BB¯ pair data sample recorded on the ϒ(4S) resonance with the Belle detector at KEKB. The following branching fractions are measured: B(B+→pΛ¯K+K-)=(4.10-0.43+0.45±0.50)×10-6, B(B+→p¯ΛK+K+)=(3.70-0.37+0.39±0.44)×10-6, B(ηc→pΛ¯K-+c.c.)=(2.83-0.34+0.36±0.35)×10-3 and B(B+→pΛ¯ϕ)=( 7.95±2.09±0.77)×10-7, where c.c. denotes the corresponding charge-conjugation process. The intermediate resonance decays are excluded in the four-body decay measurements. We also find evidence for B(ηc→Λ(1520)Λ¯+c.c.)=(3.48±1.48±0.46)×10-3 and B(B+→Λ(1520)Λ¯K+)=( 2.23±0.63±0.25)×10-6. No significant signals are found for J/ψ→Λ(1520)Λ¯+c.c. and B+→Λ¯(1520)ΛK+; we set the 90% confidence level upper limits on their decay branching fractions as <1.80×10-3 and <2.08×10-6, respectively.

Measurements of branching fraction and direct $CP$ asymmetry in $B^{\pm}\to K^{0}_{S}K^{0}_{S}K^{\pm}$ and a search for $B^{\pm}\to K^{0}_{S}K^{0}_{S}\pi^{\pm}$

Abstract: We study charmless hadronic decays of charged B mesons to the final states KS0KS0K± and KS0KS0π± using a 711 fb-1 data sample that contains 772×106 BB¯ pairs and was collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. For B±→KS0KS0K±, the measured branching fraction and direct CP asymmetry are [10.42±0.43(stat)±0.22(syst)]×10-6 and [+1.6±3.9(stat)±0.9(syst)]%, respectively. In the absence of a statistically significant signal for B±→KS0KS0π±, we obtain a 90% confidence-level upper limit on its branching fraction as 8.7×10-7.

Search for B-→ Λ p ν ν with the B a B ar experiment SEARCH for B-→ Λ p ν ν ... LEES J. P. et al.

Abstract: A search for the rare flavor-changing neutral current process B-→Λp¯νν¯ using data from the BABAR experiment has been performed. A total of 424 fb-1 of e+e- collision data collected at the center-of-mass energy of the ϒ(4S) resonance is used in this study, corresponding to a sample of (471±3)×106 BB¯ pairs. Signal B-→Λp¯νν¯ candidates are identified by first fully reconstructing a B+ decay in one of many possible exclusive decays to hadronic final states, then examining detector activity that is not associated with this reconstructed B+ decay for evidence of a signal B-→Λp¯νν¯ decay. The data yield is found to be consistent with the expected background contribution under a null signal hypothesis, resulting in an upper limit of B(B-→Λp¯νν¯)<3.0×10-5 at the 90% confidence level.

Measurements of the Branching Fractions ${\cal B}(B^{-} \to \bar{\Lambda}_{c}^{-} \Xi_{c}^{'0})$, ${\cal B}(B^{-} \to \bar{\Lambda}_{c}^{-} \Xi_{c}(2645)^{0})$ and ${\cal B}(B^{-} \to \bar{\Lambda}_{c}^{-} \Xi_{c}(2790)^{0}) $

Abstract: Using the data sample of 711 fb-1 of ϒ(4S) on-resonance data taken by the Belle detector at the KEKB asymmetric-energy electron-positron collider, we present the first measurements of branching fractions of the decays B-→Λ¯c-Ξc′0, B-→Λ¯c-Ξc(2645)0, and B-→Λ¯c-Ξc(2790)0. The signal yields for these decays are extracted from the recoil mass spectrum of the system recoiling against Λ¯c- baryons in selected B- candidates. The branching fraction of B-→Λ¯c-Ξc(2790)0 is measured to be (1.1±0.4±0.2)×10-3, where the first uncertainty is statistical and the second is systematic. The 90% credibility level upper limits on B(B-→Λ¯c-Ξc′0) and B(B-→Λ¯c-Ξc(2645)0) are determined to be 6.5×10-4 and 7.9×10-4, respectively.