New Results from CLEO-II on Hadronic Decays of the Tau Lepton

Results on semi-hadronic decays of the $\tau$ lepton are presented, from studies of $e^+e^-$ annihilation data obtained at the Cornell Electron Storage Ring with the CLEO-II detector. Branching fractions have been measured for decays to two, three and four hadrons, namely $\tau^-\!\!\rightarrow\! \nu_\tau h^-\pi^0$, $\tau^-\!\!\rightarrow\! \nu_\tau h^-h^+h^-$, and $\tau^-\!\!\rightarrow\! \nu_\tau h^-h^+h^-\pi^0$, where $h^\pm$ represents a charged pion or kaon. CLEO-II has also observed decays with charged and/or neutral kaons; preliminary results for branching ratios and structure arising from the decay dynamics are given. Connections are made with predictions derived from theoretical models, the Conserved Vector Current theorem, isospin constraints and sum rules.Comment: 9 pages, CALT-68-194

Observation of the Dsj(2463) and Confirmation of the Dsj*(2317)

Using 13.5 inverse-femtobarns of e+e- annihilation data in the CLEO II detector at CESR, we have observed a new narrow state decaying to Ds*+ pio, denoted the DsJ(2463). A possible interpretation holds that this is a J^P = 1+^ partner to the DsJ*(2317) state recently discovered by the BaBar Collaboration which is consistent with J^P = 0^+. We have also confirmed the existence of the DsJ*(2317) in its decay to Ds+ pio. We have measured the masses of both states, accounting for the cross-feed background that the two states represent for each other, and have searched for other decay channels for both states. No narrow resonances are seen in neutral or doubly charged Ds pi modes.Comment: Presented at MRST 2003 conference, "Joefest" Syracuse University, May 13-15, 2003; Conf. on the Intersections of Particle & Nuclear Phyiscs, New York, NY, May 19-24, 2003; Flavor Physics and CP Violation, Ecole Polytechnique, Paris, France, June 3-6, 2003; 7 pages 4 figure

Measurement of the B Semileptonic Branching Fraction with Lepton Tags

We have used the CLEO II detector and 2.06fb^(-1) of ϒ(4S) data to measure the B-meson semileptonic branching fraction. The B→Xeν momentum spectrum was obtained over nearly the full momentum range by using charge and kinematic correlations in events with a high-momentum lepton tag and an additional electron. We find B(B→Xeν) = (10.49±0.17±0.43)%, with overall systematic uncertainties less than those of untagged single-lepton measurements. We use this result to calculate the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element V_(cb) and to set an upper limit on the fraction of ϒ(4S) decays to final states other than BB̅

Two-Body B Meson Decays to η and η': Observation of B → η'K

In a sample of 6.6×10^6 produced B mesons we have observed decays B→η′K, with branching fractions B(B^+→η′K^+) = (6.5_(-1.4)^(+1.5)±0.9)×10^(-5) and B(B^0→η′K^0) = (4.7_(-2.0)^(+2.7)±0.9)×10^(-5). We have searched with comparable sensitivity for 17 related decays to final states containing an η or η′ meson accompanied by a single particle or low-lying resonance. Our upper limits for these constrain theoretical interpretations of the B→η′K signal

Measurement of B(D^0 → K^-π^+) Using Partial Reconstruction of B̅ → D^(*+)Xℓ^-ν̅

We present a measurement of the absolute branching fraction for D^0→K^-π^+ using the reconstruction of the decay chain B̅ →D^(*+)Xℓ^-ν̅ , D^(*+)→D^0π^+ where only the lepton and the low-momentum pion from the D^(*+) are detected. With data collected by the CLEO II detector at the Cornell Electron Storage Ring, we have determined B(D^0→K^-π^+) = [3.81±0.15(stat)±0.16(syst)]%

Search for color-suppressed B hadronic decay processes at the Υ(4S) resonance

Using 3.1fb^(-1) of data accumulated at the Υ(4S) by the CLEO-II detector, corresponding to 3.3×10^6 BB̅ pairs, we have searched for the color-suppressed B hadronic decay processes B^(0) → D^(0)(D^(*0))X^0, where X^0 is a light neutral meson π^0, ρ^0, η, η′ or ω. The D^(*0) mesons are reconstructed in D^(*0) → D^(0)π^(0) and the D^0 mesons in D^(0) → K^(-)π^(+), K^(-)π^(+)π^(0) and K^(-)π^(+)π^(+)π^(-) decay modes. No obvious signal is observed. We set 90% C.L. upper limits on these modes, varying from 1.2×10^(-4) for B^(0) → D^(0)π^(0) to 1.9×10^(-3) for B^(0) → D^(*0)η′

L2 Decay Of Certain Bilinear Oscillatory Integral Operators

In this thesis, we study bilinear oscillatory integral operators of the form $$I_\lambda(f_1, f_2) = \int_M e^{i\lambda \Phi(x)} f_1(x^1) f_2(x^2) a(x) d\sigma(x)$$ where $x^1:= (x_1, \dots, x_d)$, $x^2:= (x_{d+1}, \dots, x_{2d})$, and $\rho, \Phi, a$ are smooth functions on an open box $B_1$ with $a$ compactly supported, $\partial_i \rho$ nonvanishing on $B_1$ for each $i$, and $M := \{ x \in B_1 \,|\, \rho(x) = 0\}$. Under an additional determinant condition that has similarities to both a mixed Hessian condition on $\Phi$ and a Phong-Stein rotational curvature condition on $\rho$, we prove that this operator has optimal $L^2$ decay, namely that $$|I_\lambda(f_1, f_2)| \leq C|\lambda|^{-\frac{d-1}2} ||f_1||_{L^2(\mathbb{R}^d)} ||f_2||_{L^2(\mathbb{R}^d)}$$ The proof uses a frequency space decomposition which is a higher-dimensional analogue of one developed in earlier work with Gressman, and applies this to the functions $f_1$ and $f_2$ to generate a kernel which captures the oscillatory behavior of the phase and can be analyzed using stationary phase arguments, among others. The constant $C$ in the bound depends continuously on parameters based on $a, \Phi, \rho$, the dimension $d$, and the size of the support of the integrand, and so the result is stable under small perturbations of these objects. We then study two specific bilinear operators which have polynomial phase, and show how the results of the main theorem can be leveraged to prove decay even when the determinant condition in the hypothesis does not hold. We also use these examples to show that the decay of the operator is affected by the precise way in which the determinant condition fails

Measurement of the total cross section for e^+e^-→hadrons at √s=10.52 GeV

Using the CLEO detector at the Cornell Electron Storage Ring, we have made a measurement of R≡σ(e^+e^-→hadrons)/σ(e^+e^-→μ^+μ^-)=3.56±0.01±0.07 at √s=10.52 GeV. This implies a value for the strong coupling constant of α_s(10.52 GeV)=0.20±0.01±0.06, or α_s(MZ)=0.13±0.005±0.03

Search for the decay B→D_(s1)^+ (2536)X

We have searched for the decay B⃗D_(s1)^+(2536)X and measured an upper limit for the inclusive branching fraction of B(B⃗D_(s1)^+X)<0.96% at the 90% confidence level. This limit is small compared with the total expected B⃗D^((*))D^((*))KX rate. Assuming factorization, the D_(s1)^+ decay constant is constrained to be fD_(s1)^+<114 MeV at the 90% confidence level, at least 2.5 times smaller than that of D_s^+