Showing papers by "Sergio Grancagnolo published in 2003"

Observation of a Narrow Meson State Decaying to Ds+π0 at a Mass of 2.32 GeV/c2

Abstract: We have observed a narrow state near 2.32 GeV/c(2) in the inclusive D(+)(s)pi(0) invariant mass distribution from e(+)e(-) annihilation data at energies near 10.6 GeV. The observed width is consistent with the experimental resolution. The small intrinsic width and the quantum numbers of the final state indicate that the decay violates isospin conservation. The state has natural spin-parity and the low mass suggests a J(P)=0(+) assignment. The data sample corresponds to an integrated luminosity of 91 fb(-1) recorded by the BABAR detector at the SLAC PEP-II asymmetric-energy e(+)e(-) storage ring.

Rates, Polarizations, and Asymmetries in Charmless Vector-Vector B Meson Decays

Abstract: With a sample of approximately 89 million B{bar B} pairs collected with the BABAR detector, they measure branching fractions, determine the degree of longitudinal polarization, and search for direct CP violation in the decays B{sup 0} {yields} {psi}K*{sup 0} and B{sup +} {yields} {psi}K*{sup +}. They perform a search for other charmless vector-vector B decays involving {rho} and K*(892) resonances and observe the decays B{sup +} {yields} {rho}{sup 0} K*{sup +} and B{sup +} {yields} {rho}{sup 0}{rho}{sup +}. The branching fractions are measured to be {Beta}({phi}K*{sup 0}) = (11.1 {sub -1.2}{sup +1.3} {+-} 1.1) x 10{sup -6}, {Beta}({phi}K*{sup +}) = (12.1 {sub -1.9}{sup +2.1} {+-} 1.5) x 10{sup -6}, {Beta}({rho}{sup 0} K*{sup +}) = (7.7{sub -2.0}{sup +2.1} {+-} 1.4) x 10{sup -6}, and {Beta}({rho}{sup 0} {rho}{sup +}) = 0.65 {+-} 0.07 {+-} 0.04 and {Lambda}{sub L}/{Lambda}({phi}K*{sup +}) = 0.46 {+-} 0.12 {+-} 0.05. They measure the charge asymmetries: {Alpha}{sub CP}({phi}K*{sup 0}) = +0.04 {+-} 0.12 {+-} 0.02 and {Alpha}{sub CP}({phi}K*{sup +}) = +0.16 {+-} 0.17 {+-} 0.04.

Evidence for the rare decay B → K*ℓ+ℓ- and measurement of the B → Kℓ+ℓ- branching fraction

Abstract: We present evidence for the flavor-changing neutral current decay B-->K-*.(+).(-) and a measurement of the branching fraction for the related process B-->K.(+).(-), where .(+).(-) is either an e(+)e(-) or a mu(+)mu(-) pair. These decays are highly suppressed in the standard model, and they are sensitive to contributions from new particles in the intermediate state. The data sample comprises 123x10(6) Y(4S)-->B (B) over bar decays collected with the BABAR detector at the SLAC PEP-II e(+)e(-) storage ring. Averaging over K-(*) isospin and lepton flavor, we obtain the branching fractions B(B-->Kl(+)l(-))=(0.65(-0.13)(+0.14)+/-0.04)x10(-6) and B(B-->K(*)l(+)l(-))=(0.88(-0.29)(+0.33)+/-0.10)x10(-6), where the uncertainties are statistical and systematic, respectively. The significance of the B-->Kl(+)l(-) signal is over 8sigma, while for B-->K(*)l(+)l(-) it is 3.3sigma.

Measurements of CP-violating asymmetries and branching fractions in B meson decays to η' K

Abstract: We present measurements of the branching fractions of the decays B+-->eta'K+ and B0-->eta'K0. For B0-->eta(')K(0)(S) we also measure the time-dependent CP-violation parameters S eta'(K(0)(S)) and C eta'(K(0)(S)), and for B+-->eta'K+ the time-integrated charge asymmetry A(ch). The data sample corresponds to 88.9 x 10(6) BB pairs produced by e(+)e(-) annihilation at the Upsilon(4S). The results are B(B+-->eta'K+)=(76.9+/-3.5+/-4.4) x 10(-6), B(B0-->eta'K0)=(60.6+/-5.6+/-4.6) x 10(-6), S eta'(K(0)(S))=0.02+/-0.34+/-0.03, C eta'(K(0)(S))=0.10+/-0.22+/-0.04, and A(ch)=0.037+/-0.045+/-0.011.

Measurements of branching fractions and CP-violating asymmetries in B0 → ρ±h∓ decays

Abstract: Measurements of branching fractions and CP-violating asymmetries in B0→ρ±πplusmn; and ρ-K+ decays are presented. As such, no evidence is found for either mixing-induced CP violation in the time-dependent asymmetry of B0→ρ±π± decays, or direct CP violation in B0→ρ-K+. The measurement of direct CP violation is found to be consistent with zero within 2.0 standard deviations, when both statistical and systematic errors are taken into account.

Observation of the decay B± → π±π0, study of B± → K±π0, and search for B0 → π0 π0

Abstract: We present results for the branching fractions and charge asymmetries in B+/--->h(+/-)pi(0) (where h(+/-)=pi(+/-),K+/-) and a search for the decay B0-->pi(0)pi(0) using a sample of approximately 88 x 10(6) BBmacr; pairs collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We measure B(B+/--->pi(+/-)pi(0))=(5.5(+1.0)(-0.9)+/-0.6)x10(-6), where the first error is statistical and the second is systematic. The B+/--->pi(+/-)pi(0) signal has a significance of 7.7sigma including systematic uncertainties. We simultaneously measure the K+/-pi(0) branching fraction to be B(B+/--->K+/-pi(0))=(12.8(+1.2)(-1.1)+/-1.0)x10(-6). The charge asymmetries are Api(+/-)(pi(0))=-0.03(+0.18)(-0.17)+/-0.02 and AK+/-(pi(0))=-0.09+/-0.09+/-0.01. We place a 90% confidence-level upper limit on the branching fraction B(B0-->pi(0)pi(0)) of 3.6 x 10(-6).

Search for D0-D̄0 Mixing and a Measurement of the Doubly Cabibbo-Suppressed Decay Rate in D0 → Kπ Decays

Abstract: We present results of a search for D0-D(-)0 mixing and a measurement of R(D), the ratio of doubly Cabibbo-suppressed decays to Cabibbo-favored decays, using D0-->K+pi- decays from 57.1 fb(-1) of data collected near sqrt[s]=10.6 GeV with the BABAR detector at the PEP-II collider. At the 95% confidence level, allowing for CP violation, we find the mixing parameters x('2)<0.0022 and -0.056

Limits on D0-D̄0 Mixing and CP Violation from the Ratio of Lifetimes for Decay to K-π+, K -K+, and π-π+

Abstract: We present a measurement of D0-macro D0 mixing parameters using the ratios of lifetimes extracted from samples of D0 mesons decaying to K-pi(+), K-K+, and pi(-)pi(+). Using 91 fb(-1) of data collected by the BABAR detector at the PEP-II asymmetric-energy B Factory, we obtain a value Y=[0.8+/-0.4(stat.)(+0.5)(-0.4)(syst.)]%, which, in the limit of CP conservation, corresponds to the mixing parameter y=Delta Gamma/2 Gamma. Using the difference in lifetimes of D0 and macro D0 mesons, we obtain the CP-violation parameter Delta Y=[-0.8+/-0.6(stat.)+/-0.2(syst.)]%.

Observation of a significant excess of π0π0 events in B meson decays

Abstract: We present a study of the decay B0 -> p0p0 based on a sample of 124 * 106 B.hivin.B pairs recorded by the BABAR detector at the PEP-II asym.-energy B Factory at SLAC. We observe 46 +- 13 +- 3 events, where the first error is statistical and the second is systematic, corresponding to a significance of 4.2 std. deviations including systematic uncertainties. We measure the branching fraction B(B0 -> p0p0) = (2.1 +- 0.6 +- 0.3) * 10-6, averaged over B0 and .hivin.B0 decays. [on SciFinder (R)]

Measurement of the branching fractions for the exclusive decays of B(0) and B(+) to D over-bar(*) D(*) K

Abstract: We report the observation of 823+/-57 B^0 and 970+/-65 B^+ decays to doubly charmed final states Dbar^(*)D^(*)K, where Dbar^(*) and D^(*) are fully reconstructed and K is either a K+/- or a K^0. We use a sample of 82.3+/- 0.9 million BBbar events collected between 1999 and 2002 with the babar detector at the PEP-II storage ring at the Stanford Linear Accelerator Center. The 22 possible B decays to Dbar^(*)D^(*)K are reconstructed exclusively and the corresponding branching fractions or limits are determined. The branching fractions of the B^0 and of the B^+ to Dbar^(*)D^(*)K$ are found to be BR(B^0 --> Dbar^(*) D^(*) K) = (4.3 +/- 0.3 stat +/- 0.6 syst)%, BR(B^+ --> Dbar^(*) D^(*) K) = (3.5 +/- 0.3 stat +/- 0.5 syst)%. A search for decays to orbitally excited $D_s$ states, B --> Dbar^(*) D_{sJ}^{+} (D_{sJ}^{+} --> D^(*)0K^+) is also performed.

Measurements of the branching fractions and bounds on the charge asymmetries of charmless three-body charged B decays.

Abstract: We present measurements of branching fractions and charge asymmetries for charmless B-meson decays to three-body final states of charged pions and kaons. The analysis uses 81.8 fb^-1 of data collected at the Upsilon(4S) resonance with the BaBar detector at the SLAC PEP-II asymmetric B Factory. We measure the branching fractions B(B+ -> pi+ pi- pi+) = (10.9 +/- 3.3 +/- 1.6) x 10^-6, B(B+ -> K+ pi- pi+) = (59.1 +/- 3.8 +/- 3.2) x 10^-6, and B(B+ -> K+ K- K+) = (29.6 +/- 2.1 +/- 1.6) x 10^-6, and provide 90% C.L. upper limits for other decays. We observe no charge asymmetries for these modes.

Evidence for B+ → J/ψpΛ̄ and search for B0 → J/ψpp̄

Abstract: We have performed a search for the decays ${B}^{+}\ensuremath{\rightarrow}J/\ensuremath{\psi}p\overline{\ensuremath{\Lambda}}$ and ${B}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}p\overline{p}$ in a data set of $(88.9\ifmmode\pm\else\textpm\fi{}1.0)\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $\ensuremath{\Upsilon}(4S)$ decays collected by the BABAR experiment at the PEP-II ${e}^{+}{e}^{\ensuremath{-}}$ storage ring at the Stanford Linear Accelerator Center. Four charged $B$ candidates have been observed with an expected background of $0.21\ifmmode\pm\else\textpm\fi{}0.14$ events. The corresponding branching fraction is $({12}_{\ensuremath{-}6}^{+9})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, where statistical and systematic uncertainties have been combined. The result can be interpreted as a 90% confidence level (C.L.) upper limit of $26\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. We also find one ${B}^{0}$ candidate, with an expected background of $0.64\ifmmode\pm\else\textpm\fi{}0.17$ events, implying a 90% C.L. upper limit of $1.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$.

Measurement of the branching fraction, and bounds on the CP-violating asymmetries, of neutral B decays to D*±D∓

Abstract: We present measurements of the branching fraction and CP-violating asymmetries for neutral B decays to D(*+/-)D-/+. The measurement uses a data sample of approximately 88x10(6) Upsilon(4S)-->BBmacr; decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy e(+)-e(-) collider. By fully reconstructing the D(*+/-)D-/+ decay products, we measure the branching fraction to be (8.8+/-1.0+/-1.3)x10(-4) and the time-integrated CP-violating asymmetry between the rates to D(*-)D+ and D(*+)D- to be A=-0.03+/-0.11+/-0.05. We also measure the time-dependent CP-violating asymmetry parameters to be S(-+)=-0.24+/-0.69+/-0.12, C(-+)=-0.22+/-0.37+/-0.10 for B-->D(*-)D+ and S(+-)=-0.82+/-0.75+/-0.14, C(+-)=-0.47+/-0.40+/-0.12 for B-->D(*+)D-. In each case, the first error is statistical and the second error is systematic.

Study of time-dependent CP asymmetry in neutral B decays to J/ψπ0

Abstract: We present the first study of the time-dependent CP-violating asymmetry in B0-->J/psi pi(0) decays using e(+)e(-) annihilation data collected with the BABAR detector at the Upsilon(4S) resonance during the years 1999-2002 at the PEP-II asymmetric-energy B Factory at SLAC. Using approximately 88 x 10(6) BB; pairs, our results for the coefficients of the cosine and sine terms of the CP asymmetry are C(J/psi pi(0))=0.38+/-0.41(stat)+/-0.09(syst) and S(J/psi pi(0))=0.05+/-0.49(stat)+/-0.16(syst).

Study of time-dependent CP asymmetries with partial reconstruction of B->D*pi

Abstract: The authors present a preliminary measurement of the time-dependent CP asymmetries in decays of neutral B mesons to the final states D*{sup {-+}}{pi}{sup {+-}}, using approximately 82 million B{bar B} events collected by the BABAR experiment at the PEP-II storage ring. Events containing these decays are selected with a partial reconstruction technique, in which only the high momentum {pi}{sup {+-}} and the low momentum pion from the D*{sup {-+}} decay are reconstructed. The flavor of the other B meson in the event is tagged using the information from kaon and lepton candidates. They measure the time-dependent CP asymmetry {Alpha} = -0.063 {+-} 0.024 (stat.) {+-} 0.017 (syst.). They interpret these results in terms of the angles of the unitarity triangle to set a bound on |sin(2{beta} + {gamma})|.