7,464 research outputs found
Search for TeV Scale Physics in Heavy Flavour Decays
The subject of heavy flavour decays as probes for physics beyond the TeV
scale is covered from the experimental perspective. Emphasis is placed on the
more traditional Beyond the Standard Model topics that have potential for
impact in the short term, with the physics explained. We do unabashedly promote
our own phemonenology work.Comment: 10 pages, 9 figures (now fixed); Submitted for the SUSY07 proceeding
Direct CP Violation, Branching Ratios and Form Factors , in Decays
The and transitions involved in hadronic B decays are
investigated in a phenomenological way through the framework of QCD
factorization. By comparing our results with experimental branching ratios from
the BELLE, BABAR and CLEO Collaborations for all the B decays including either
a pion or a kaon, we propose boundaries for the transition form factors and depending on the CKM matrix element parameters and
. From this analysis, the form factors required to reproduce the
experimental data for branching ratios are and
. We calculate the direct CP violating asymmetry
parameter, , for and decays, in the case where mixing effects are taken into
account. Based on these results, we find that the direct CP asymmetry for
, ,
, and , reaches its maximum when the invariant mass is
in the vicinity of the meson mass. The inclusion of
mixing provides an opportunity to erase, without ambiguity, the phase
uncertainty mod in the determination of the CKM angles in case
of and in case of .Comment: 74 pages, 15 figures, 8 tables. A few misprints corrected, two
references adde
Study of D_(sJ) decays to D*K in inclusive e^+e^- interactions
We observe the decays D*_(s1)(2710)^+ → D*K and D*_(sJ)(2860)^+ → D*K and measure their branching fractions relative to the DK final state. We also observe, in the D*K mass spectrum, a new broad structure at a mass of (3044 ± 8_(stat)(^(+30)_(-5))_(syst)) MeV/c^2 having a width Γ =(239 ± 35_(stat)(^(+46)_(-42))_(syst)) MeV. To obtain this result we use 470 fb^(-1) of data recorded by the BABAR detector at the PEP-II asymmetric-energy e^+e^- storage rings at the Stanford Linear Accelerator Center running at center-of-mass energies near 10.6 GeV
Measurement of branching fractions of B decays to K_1(1270)π and K_1(1400)π and determination of the CKM angle α from B^0→a_1(1260)^±π^∓
We report measurements of the branching fractions of neutral and charged B meson decays to final states containing a K_1(1270) or K_1(1400) meson and a charged pion. The data, collected with the BABAR detector at the SLAC National Accelerator Laboratory, correspond to 454×10^6 BB̅ pairs produced in e^+e^- annihilation. We measure the branching fractions B(B^0→K_1(1270)^+π-+K_1(1400)^+π-)=3.1_(-0.7)^(+0.8)×10^(-5) and B(B^+→K_1(1270)^0π^++K_1(1400)^0π^+)=2.9_(-1.7)^(+2.9)×10^(-5) (<8.2×10^(-5) at 90% confidence level), where the errors are statistical and systematic combined. The B^0 decay mode is observed with a significance of 7.5σ, while a significance of 3.2σ is obtained for the B^+ decay mode. Based on these results, we estimate the weak phase α=(79±7±11)° from the time-dependent CP asymmetries in B^0→a1(1260)^±π^∓ decays
Measurements of the τ mass and the mass difference of the τ^+ and τ^- at BABAR
We present the result from a precision measurement of the mass of the τ lepton, M_τ, based on 423 fb^(-1) of data recorded at the Υ(4S) resonance with the BABAR detector. Using a pseudomass endpoint method, we determine the mass to be 1776.68±0.12(stat)±0.41(syst) MeV. We also measure the mass difference between the τ^+ and τ^-, and obtain (M_(τ+)-M_(τ-))/M_(AVG)^τ=(-3.4±1.3(stat)±0.3(syst))×10^(-4), where M^τ_(AVG) is the average value of M_(τ+) and M_(τ-)
Search for B^+→ℓ^+ν_ℓ recoiling against B^-→D^0ℓ^-ν̅ X
We present a search for the decay B^+→ℓ^+ν_ℓ(ℓ=τ, μ, or e) in (458.9±5.1)×10^6 BB̅ pairs recorded with the BABAR detector at the PEP-II B-factory. We search for these B decays in a sample of B^+B^- events where one B-meson is reconstructed as B^-→D^0ℓ^-ν̅ X. Using the method of Feldman and Cousins, we obtain B(B^+→τ^+ν_τ)=(1.7±0.8±0.2)×10^(-4), which excludes zero at 2.3σ. We interpret the central value in the context of the standard model and find the B meson decay constant to be f_B^2=(62±31)×10^3 MeV^2. We find no evidence for B^+→e^+ν_e and B^+→μ^+ν_μ and set upper limits at the 90% C.L. B(B^+→e^+ν_e)<0.8×10^(-5) and B(B^+→μ^+ν_μ)<1.1×10^(-5)
Observation of the χ_(c2)(2P) meson in the reaction γγ→DD at BABAR
A search for the Z(3930) resonance in γγ production of the DD system has been performed using a data sample corresponding to an integrated luminosity of 384 fb^(-1) recorded by the BABAR experiment at the PEP-II asymmetric-energy electron-positron collider. The DD invariant mass distribution shows clear evidence of the Z(3930) state with a significance of 5.8σ. We determine mass and width values of (3926.7±2.7±1.1) MeV/c^2 and (21.3±6.8±3.6) MeV, respectively. A decay angular analysis provides evidence that the Z(3930) is a tensor state with positive parity and C parity (J^(PC)=2^(++)); therefore we identify the Z(3930) state as the χ_(c2)(2P) meson. The value of the partial width Γ_(γγ)×B(Z(3930)→DD) is found to be (0.24±0.05±0.04) keV
Synthesis and photophysical characteristics of polyfluorene polyrotaxanes
Two alternating polyfluorene polyrotaxanes (3·TM-βCD and 3·TM-γCD) have been synthesized by the coupling of 2,7-dibromofluorene encapsulated into 2,3,6-tri-O-methyl-β- or γ-cyclodextrin (TM-βCD, TM-γCD) cavities with 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester. Their optical, electrochemical and morphological properties have been evaluated and compared to those of the non-rotaxane counterpart 3. The influence of TM-βCD or TM-γCD encapsulation on the thermal stability, solubility in common organic solvents, film forming ability was also investigated. Polyrotaxane 3·TM-βCD exhibits a hypsochromic shift, while 3·TM-γCD displays a bathochromic with respect to the non-rotaxane 3 counterpart. For the diluted CHCl3 solutions the fluorescence lifetimes of all compounds follow a mono-exponential decay with a time constant of ≈0.6 ns. At higher concentration the fluorescence decay remains mono-exponential for 3·TM-βCD and polymers 3, with a lifetime τ = 0.7 ns and 0.8 ns, whereas the 3·TM-γCD polyrotaxane shows a bi-exponential decay consisting of a main component (with a weight of 98% of the total luminescence) with a relatively short decay constant of τ1 = 0.7 ns and a minor component with a longer lifetime of τ2 = 5.4 ns (2%). The electrochemical band gap (ΔEg) of 3·TM-βCD polyrotaxane is smaller than that of 3·TM-γCD and 3, respectively. The lower ΔEg value for 3·TM-βCD suggests that the encapsulation has a greater effect on the reduction process, which affects the LUMO energy level value. Based on AFM analysis, 3·TM-βCD and 3·TM-γCD polyrotaxane compounds exhibit a granular morphology with lower dispersity and smaller roughness exponent of the film surfaces in comparison with those of the neat copolymer 3
Observation and polarization measurement of B^0 → a_1(1260)^(+)a_1(1260)^(-) decay
We present measurements of the branching fraction B and longitudinal polarization fraction f_L for B^0 → a_1(1260)^(+)a_1(1260)^(-) decays, with a_1(1260)^(±) → π^(-)π^(+)π^(±). The data sample, collected with the BABAR detector at the SLAC National Accelerator Laboratory, represents 465 × 10^6 produced BB(overbar) pairs. We measure B(B^0 → a_1(1260)^(+)a_1(1260)^-) × [B(a_1(1260)^+ → π^(-)π^(+)π^(+))]^2 = (11.8±2.6±1.6) ×10^(-6) and f_L = 0.31±0.22±0.10, where the first uncertainty is statistical and the second systematic. The decay mode is measured with a significance of 5.0 standard deviations including systematic uncertainties
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