Search results for "decay"
showing 10 items of 2087 documents
Measurements of the branching fraction and time-dependentCPasymmetries ofB0→J/ψπ0decays
2006
We present measurements of the branching fraction and time-dependent CP asymmetries in B{sup 0} {yields} J/{psi}{pi}{sup 0} decays based on (231.8 {+-} 2.6) x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. We obtain a branching fraction {Beta}(B{sup 0} {yields} J/{psi}{pi}{sup 0}) = (1.94 {+-} 0.22 (stat) {+-} 0.17 (syst)) x 10{sup -5}. We also measure the CP asymmetry parameters C = -0.21 {+-} 0.26 (stat) {+-} 0.06 (syst) and S = -0.68 {+-} 0.30 (stat) {+-} 0.04 (syst).
Study ofB0→π0π0,B±→π±π0, andB±→K±π0decays, and isospin analysis ofB→ππdecays
2007
We present updated measurements of the branching fractions and CP asymmetries for B{sup 0}{yields}{pi}{sup 0}{pi}{sup 0}, B{sup {+-}}{yields}{pi}{sup {+-}}{pi}{sup 0}, and B{sup {+-}}{yields}K{sup {+-}}{pi}{sup 0}. Based on a sample of 383x10{sup 6} {upsilon}(4S){yields}BB decays collected by the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC, we measure B(B{sup 0}{yields}{pi}{sup 0}{pi}{sup 0})=(1.47{+-}0.25{+-}0.12)x10{sup -6}, B(B{sup {+-}}{yields}{pi}{sup {+-}}{pi}{sup 0})=(5.02{+-}0.46{+-}0.29)x10{sup -6}, and B(B{sup {+-}}{yields}K{sup {+-}}{pi}{sup 0})=(13.6{+-}0.6{+-}0.7)x10{sup -6}. We also measure the CP asymmetries C{sub {pi}{sup 0}}{sub {pi}{sup 0}}=-0.49{+-}0.…
Analysis of enhancedβeffects in minimal flavor violation GUT scenarios
2006
Long-range forces between macroscopic objects are mediated by light particles that interact with the electrons or nucleons, and include spin-dependent static components as well as spin- and velocity-dependent components. We parametrize the long-range potential between two fermions assuming rotational invariance, and find 16 different components. Applying this result to electrically neutral objects, we show that the macroscopic potential depends on 72 measurable parameters. We then derive the potential induced by the exchange of a new gauge boson or spinless particle, and compare the limits set by measurements of macroscopic forces to the astrophysical limits on the couplings of these partic…
Measurements ofΛc+branching fractions of Cabibbo-suppressed decay modes involvingΛandΣ0
2007
We measure the branching ratios of the Cabibbo-suppressed decays $\Lambda^+_c$ $\to$ $\Lambda$ $K^+$ and $\Lambda^+_c$ $\to$ $\Sigma^{0}$ $K^+$ %(measured with improved accuracy). relative to the Cabibbo-favored decay modes $\Lambda^+_c$ $\to$ $\Lambda$ $\pi^+$ and $\Lambda^+_c$ $\to$ $\Sigma^{0}$ $\pi^+$ to be $ 0.044 \pm 0.004 ~(\textnormal{stat.})~ \pm ~0.003 \~(\textnormal{syst.})$ and $ 0.039~ \pm ~0.005 ~(\textnormal{stat.})~ \pm \~0.003 ~(\textnormal{syst.})$, respectively. We set an upper limit on the branching ratio at 90 % confidence level for $\Lambda^+_c$ $\to$ $\Lambda$ $K^+ \pi^+ \pi^-$ to be $ 4.1 \times ~10^{-2}$ relative to $\Lambda^+_c$ $\to$ $\Lambda$ $\pi^+$ and for $\La…
Measurements of time-dependentCPasymmetries inB0→D(*)+D(*)−decays
2009
We present new measurements of time-dependent CP asymmetries for B{sup 0} {yields} D{sup (*)+}d{sup (*)-} decays using (467 {+-} 5) x 10{sup 6} B{bar B} pairs collected with the BABAR detector located at the PEP-II B Factory at the Stanford Linear Accelerator Center. We determine the CP-odd fraction of the B{sup 0} {yields} D*{sup +}D*{sup -} decays to be R{perpendicular} = 0.158 {+-} 0.028 {+-} 0.006 and find CP asymmetry parameters for the CP-even component of the decay S{sub +} = -0.76 {+-} 0.16 {+-} 0.04 and C{sub +} = 0.00 {+-} 0.12 {+-} 0.02. We measure S = -0.63{+-}0.36{+-}0.05 and C = -0.07{+-}0.23{+-}0.03 for B{sup 0} {yields} D{sup +}D{sup -}, S = -0.62{+-}0.21{+-}0.03 and C = 0.0…
Photoproduction ofZ(4430)through mesonic Regge trajectories exchange
2011
The recently discovered $Z(4430)$ mesonic resonance is believed to be a strong tetraquark candidate. The photoproduction in the channel $\ensuremath{\gamma}p\ensuremath{\rightarrow}{Z}^{+}(4430)n\ensuremath{\rightarrow}{\ensuremath{\psi}}^{'}{\ensuremath{\pi}}^{+}n$ has been proposed as the most effective way to confirm the $Z(4430)$ presence and to measure its quantum numbers. In this work we present a model for high-energy and forward-angle $Z(4430)$ photoproduction in a effective Lagrangian approach. This model is based on the use of Regge trajectories exchange, thus a Regge propagator replaces the usual Feynman propagator. The differential and total cross sections and the asymmetries ha…
Sensitivity to the Higgs sector of supersymmetric-seesaw models in the lepton flavor violatingτ→μf0(980)decay
2009
In this work we study the lepton flavor violating (LFV) semileptonic $\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}{f}_{0}(980)$ decay within the context of SUSY-Seesaw Models, where the MSSM spectrum is extended by three right-handed neutrinos and their SUSY partners, and where the seesaw mechanism is used to generate the neutrino masses. We estimate its decay rate when it proceeds via the Higgs-mediated channel $\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}{H}^{*}\ensuremath{\rightarrow}\ensuremath{\mu}{f}_{0}(980)$, where $H$ refers to the $CP$-even MSSM Higgs bosons ${h}^{0}$ and ${H}^{0}$, and the lepton flavor violating $\ensuremath{\tau}\ensuremath{\mu}H$ vert…
Reparametrization invariance ofBdecay amplitudes and implications for new physics searches inBdecays
2005
When studying $B$ decays within the standard model (SM), it is customary to use the unitarity of the CKM matrix in order to write the decay amplitudes in terms of only two of the three weak phases which appear in the various diagrams. Occasionally, it is mentioned that those two weak phases can be used in order to describe any decay amplitude, even beyond the standard model. Here we point out that, when describing a generic decay amplitude, the two weak phases can be chosen completely at will, and we study the behavior of the decay amplitudes under changes in the two weak phases chosen as a basis. Of course, physical observables cannot depend on such reparametrizations. This has an impact o…
Update analysis of : Theory and Experiment
2009
Within the resonance chiral theory (RχT), we have studied the process of a tau lepton decaying into a vector resonance plus a pseudo-Goldstone meson and a tau neutrino. Two kinds of processes are discussed: (a) τ − → ( ρ 0 π − , ω π − , ϕ π − , K ∗ 0 K − ) ν τ , belonging to Δ S = 0 processes and (b) Δ S = 1 processes, such as τ − → ( ρ 0 K − , ω K − , ϕ K − , K ¯ ∗ 0 π − ) ν τ . To fit the τ − → ω π − ν τ spectral function and the decay distribution of τ − → ω K − ν τ to get unknown resonance couplings, we then make a prediction for branching ratios of all channels.
Study of the K±→π±γγ decay by the NA62 experiment
2014
Abstract A study of the dynamics of the rare decay K ± → π ± γ γ has been performed on a sample of 232 decay candidates, with an estimated background of 17.4 ± 1.1 events, collected by the NA62 experiment at CERN in 2007. The results are combined with those from a measurement conducted by the NA48/2 Collaboration at CERN. The combined model-independent branching ratio in the kinematic range z = ( m γ γ / m K ) 2 > 0.2 is B MI ( z > 0.2 ) = ( 0.965 ± 0.063 ) × 10 − 6 , and the combined branching ratio in the full kinematic range assuming a Chiral Perturbation Theory description is B ( K π γ γ ) = ( 1.003 ± 0.056 ) × 10 − 6 . A detailed comparison of the results with the previous measurements…