Search results for "annihilation"
showing 10 items of 1016 documents
Test Measurements of Modernized Version of Two-Detector Doppler Spectrometer
1999
The quality of the annihilation quanta energy measurements (Doppler effect) has greatly increased when experimenters have begun to introduce Doppler apparatus modifications. In the basic version, the experimental set-up consisted of high energy resolution Ge(Li) detector, amplifier and multichannel analyser. A simple construction and short time of data acquisition were the main advantages of that version of the apparatus. Competitive, angular correlation of annihilation radiation (ACAR) method was better from the resolution point of view and not worse when considering the range of momentum distribution, but the ACAR method required high activity positron sources and data acquisition time wa…
Searches for the decaysB0→l±τ∓andB+→l+ν(l=e,μ) using hadronic tag reconstruction
2008
We present searches for the leptonic decays B{sup +} {yields} {ell}{sup +}{nu} and the lepton flavor violating decays B{sup 0} {yields} {ell}{sup {+-}}{tau}{sup {-+}}, where {ell} = e, {mu}, with data collected by the BABAR experiment at SLAC. This search demonstrates a novel technique in which we fully reconstruct the accompanying {bar B} in {Upsilon}(4S) {yields} B{bar B} events, and look for a monoenergetic lepton from the signal B decay. The signal yield is extracted from a fit to the signal lepton candidate momentum distribution in the signal B rest frame. Using a data sample of approximately 378 million B{bar B} pairs (342 fb{sup -1}), we find no evidence of signal in any of the decay…
Search for the decayB+→K¯*0(892)K+
2007
We report on a search for the process B+ -> (K) over bar*(0)(892)K+ using 232 X 10(6) Y(4S) -> B (B) over bar B decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. From a signal yield of 25 +/- 13[stat] +/- 7[syst] B+ -> (K) over bar*(0)(892)(-> K-pi(+))K+ events, we place an upper limit on the branching fraction B(B+ -> (K) over bar*(0)(892)K+) of 1.1 X 10(-6), at the 90% confidence level.
Measurement of branching fractions in radiativeBdecays toηKγand search forBdecays toη′Kγ
2006
We present measurements of the B ->eta K gamma branching fractions and upper limits for the B ->eta K-'gamma branching fractions. For B+->eta K+gamma we also measure the time-integrated charge asymmetry. The data sample, collected with the BABAR detector at the Stanford Linear Accelerator Center, represents 232x10(6) produced B (B) over bar pairs. The results for branching fractions and upper limits at 90% confidence level in units of 10(-6) are: B(B-0 ->eta K-0 gamma)=11.3(-2.6)(+2.8)+/- 0.6, B(B+->eta K+gamma)=10.0 +/- 1.3 +/- 0.5, B(B-0 ->eta K-'(0)gamma) eta K-'(+)gamma) eta K+gamma is A(ch)=-0.09 +/- 0.12 +/- 0.01. The first errors are statistical and the second systematic.
Measurements of the branching fractions of chargedBdecays toK±π∓π±final states
2004
We present results of searches for B-meson decays to K+ pi- pi+ with the BaBar detector. With a data sample of 61.6 million BBbar pairs, we measure the branching fractions and 90% confidence-level upper limits averaged over charge-conjugate states (the first error is statistical and the second is systematic): B+ --> K*0 pi+ = (15.5 +/- 1.8 +1.5 -4.0) x 10^-6, B+ --> f0 K+, f_0 --> pi+ pi- = (9.2 +/- 1.2 +2.1 -2.6) x 10^-6, B+ --> D0bar pi+, D0bar --> K+ pi- = (184.6 +/- 3.2 +/- 9.7) x 10^-6. B+ --> rho K+ K+ pi- pi+ non-resonant < 17 x 10^-6.
Observation of the decayB¯0→Λc+p¯π0
2010
In a sample of 467 x 10(6) B (B) over bar pairs collected with the BABAR detector at the PEP- II collider at SLAC we have observed the decay (B) over bar (0) -> Lambda(+)(c)(p) over bar pi(0) and measured the branching fraction to be (1.94 +/- 0.17 +/- 0.14 +/- 0.50 x 10(-4), where the uncertainties are statistical, systematic, and the uncertainty on the Lambda(+)(c) -> pK(-)pi(+) branching fraction, respectively. We determine an upper limit of 1.5 x 10(-6) at 90% C.L. for the product branching fraction B((B) over bar (0) -> Sigma(+)(c) (2455)(p) over bar) x B(Lambda(+)(c) -> pK(-) pi(+)). Furthermore, we observe an enhancement at the threshold of the invariant mass of the baryon- antibaryo…
Dalitz plot analysis of B−→D+π−π−
2009
We report on a Dalitz plot analysis of B- -> D+pi(-)pi(-) decays, based on a sample of about 383 x 10(6) Y(4S) -> B (B) over bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We find the total branching fraction of the three-body decay: B(B- -> D+ pi(-)pi(-)) = (1.08 +/- 0.03 +/- 0.05) x 10(-3). We observe the established D-2*(0) and confirm the existence of D-0*(0) in their decays to D+pi(-), where the D-2*(0) and D-0*(0) are the 2(+) and 0(+) c (u) over bar P-wave states, respectively. We measure the masses and widths of D-2*(0) and D-0*(0) to be: m(D2)*(0) = (2460.4 +/- 1.2 +/- 1.2 +/- 1.9) MeV/c(2), Gamma(D2*0) = (41.8 +/- 2.5 +/- 2.1 +/- 2.…
Search forB+→X(3872)K+,X(3872)→J/ψγ
2006
In a study of B+ --> J/psi gamma K+ decays, we find evidence for the radiative decay X(3872) --> J/psi gamma with a statistical significance of 3.4 sigma. We measure the product of branching fractions BF(B+ --> X(3872) K+).BF(X(3872) --> J/psi gamma) = (3.3 +/- 1.0 +/- 0.3) x 10^-6, where the uncertainties are statistical and systematic, respectively. We also measure the branching fraction BF(B+ --> chi_c1 K+) = (4.9 +/- 0.2 +/- 0.4) x 10^-4. These results are obtained from (287+/-3) million BBar decays collected at the Y(4S) resonance with the BaBar detector at the PEP-II B Factory at SLAC.
Measurement of theB0→D*−Ds*+andDs+→ϕπ+branching fractions
2005
The authors present measurements of the branching fractions {Beta}(B{sup 0} {yields} D*{sup -}D*{sub s}{sup +}) and {Beta}(D{sub s}{sup +} {yields} {phi}{pi}{sup +}), based on 123 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} B factory. A partial reconstruction technique is used to measure {Beta}(B{sup 0} {yields} D*{sup -}D*{sub s}{sup +}) and the decay chain is fully reconstructed to measure the branching fraction product {Beta}(B{sup 0} {yields} D*{sup -} D*{sub s}{sup +}) x {Beta}(D{sub s}{sup +} {yields} {phi}{pi}{sup +}). Comparing these two measurements provides a model-independent determination of …
Study of the decayB¯0→D*+ωπ−
2006
We report on a study of the decay B0bar -> D*+ omega pi- with the BABAR detector at the PEP-II B-factory at the Stanford Linear Accelerator Center. Based on a sample of 232 million BBbar decays, we measure the branching fraction BF(B0bar -> D*+ omega pi-) = (2.88 +/- 0.21(stat.) +/- 0.31(syst.)) \times 10^{-3}. We study the invariant mass spectrum of the omega pi- system in this decay. This spectrum is in good agreement with expectations based on factorization and the measured spectrum in tau- -> omega pi- nu_tau. We also measure the polarization of the D*+ as a function of the omega pi- mass. In the mass region 1.1 to 1.9 GeV we measure the fraction of longitudinal polarization of the D*+ …