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This report describes the present status of the detector design for SuperB. It is one of four separate progress reports that, taken collectively, describe progress made on the SuperB Project since the publication of the SuperB Conceptual Design Report in 2007 and the Proceedings of SuperB Workshop VI in Valencia in 2008. The other three reports relate to Physics, Accelerator and Computing.
The physics objectives of SuperB, an asymmetric electron-positron collider with a luminosity above 10^36/cm^2/s are described, together with the conceptual design of a novel low emittance design that achieves this performance with wallplug power comparable to that of the current B Factories, and an upgraded detector capable of doing the physics in the SuperB environment.
We present a measurement of the average multiplicity of $\phi$ mesons in $B^0$, $\kern 0.18em\bar{\kern -0.18em B}{}^0$ and $B^\pm$ meson decays. Using $17.6 fb^{-1}$ of data taken at the $\Upsilon{(4S)}\xspace$ resonance by the {\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}} detector at the PEP-II $e^+e^-\xspace$ storage ring at the Stanford Linear Accelerator Center, we reconstruct $\phi$ mesons in the $K^+K^-$ decay mode and measure ${\cal{B}}(B\to \phi X) = (3.41\pm0.06\pm0.12)%$. This is significantly more precise than any previous measurement.
We present a study of the decay B- -> D*0 K*- based on a sample of 86 million Upsilon(4S) -> BBbar decays collected between 1999 and 2002 with the BaBar detector at the PEP-II asymmetric-energy B-Factory at SLAC. We measure the branching fraction B(B- -> D*0 K*-) = 8.3 +/- 1.1 (stat)} +/- 1.0 (syst) x 10e-4, and the fraction of longitudinal polarization in this decay to be GammaL/Gamma = 0.86 +/- 0.06 +/- (stat) +/- 0.03 (syst).
We present evidence for the flavor-changing neutral current decay $B\to K^*\ell^+\ell^-$ and a measurement of the branching fraction for the related process $B\to K\ell^+\ell^-$, where $\ell^+\ell^-$ is either an $e^+e^-$ or $\mu^+\mu^-$ 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 $123\times 10^6$ $\Upsilon(4S)\to B\bar{B}$ decays collected with the Babar detector at the PEP-II $e^+e^-$ storage ring. Averaging over $K^{(*)}$ isospin and lepton flavor, we obtain the branching fractions ${\mathcal B}(B\to K\ell^+\ell^-)=(0.65^{+0.14}_{-0.13}\pm 0.04)\times 10^{-6}$ and ${\mathcal B}(B\to K^*\ell^+\ell^-)=(0.88^{+0.33}_{-0.29}\pm 0.10)\times 10^{-6}$, where the uncertainties are statistical and systematic, re...
We have studied the B^+/- --> J/psi pi^+/- and B^+/- --> J/psi K^+/- decays using a 20.7 fb-1 data set collected with the BABAR detector. We observe a signal of 51+/-10 B^+/- --> J/psi pi^+/- events and determine the ratio BF(B^+/- --> J/psi pi^+/-)/BF(B^+/- --> J/psi K^+/-) to be [3.91 +/- 0.78 (stat.) +/- 0.19 (syst.)]%. The CP-violating charge asymmetries for the B^+/- --> J/psi pi^+/- and B^+/- --> J/psi K^+/- decays are determined to be A_pi = 0.01 +/- 0.22 (stat.) +/- 0.01 (syst.) and A_K = 0.003 +/- 0.030 (stat.) +/- 0.004 (syst.).
The B0 lifetime has been measured with a sample of 23 million BBbar pairs collected by the BaBar detector at the PEP-II e+e- storage ring during 1999 and 2000. Events from the semileptonic decay B0 --> D*- l+ nu have been selected with a partial reconstruction method in which only the charged lepton and the slow pion from the D*- --> D0bar pi- decay are reconstructed. The result is tau_B0 = 1.529+/-0.012 (stat) +/- 0.029 (syst) ps.
We report the results of a search for T and CP violation in B0-anti-B0 mixing using an inclusive dilepton sample collected by the BaBar experiment at the PEP-II B Factory. The asymmetry between (l+,l+) and (l-,l-) events allows us to compare the probabilities P(anti-B0 -> B0) and P(B0 -> anti-B0) oscillations and thus probe T and CP invariance. Using a sample of 23 million B-anti-B pairs, we measure a same-sign dilepton asymmetry of A_(T/CP)=(0.5 +- 1.2(stat) +- 1.4(syst))%. For the modulus of the ratio of complex mixing parameters p and q, we obtain |q/p| = 0.998 +- 0.006(stat) +- 0.007(syst).
We present results from a search for the flavor-changing neutral current decays $B\to K\ell^+\ell^-$ and $B\to K^*\ell^+\ell^-$, where $\ell^+\ell^-$ is either an $e^+e^-$ or $\mu^+\mu^-$ pair. The data sample comprises $22.7\times 10^6$ $\Upsilon(4S)\to B\bar B$ decays collected with the BABAR detector at the PEP-II $B$ Factory. We obtain the 90% C.L. upper limits ${\mathcal B}(B\to K\ell^+\ell^-)< 0.50\times 10^{-6}$ and ${\mathcal B}(B\to K^*\ell^+\ell^-)<2.9\times 10^{-6}$, close to Standard Model predictions for these branching fractions. We have also obtained limits on the lepton-family-violating decays $B\to Ke^{\pm}\mu^{\mp}$ and $B\to K^{*}e^{\pm}\mu^{\mp}$.
We report a measurement of the branching fraction of the decay B^0 --> D^{*+} D^{*-} and of the CP-odd component of its final state using the BaBar detector. With data corresponding to an integrated luminosity of 20.4 fb^{-1} collected at the Upsilon(4S) resonance during 1999-2000, we have reconstructed 38 candidate signal events in the mode B^0 --> D^{*+}D^{*-} with an estimated background of 6.2 \pm 0.5 events. From these events, we determine the branching fraction to be BR(B^0 --> D^{*+}D^{*-}) = (8.3 +/- 1.6(stat) +/- 1.2(syst)) x 10^{-4}. The measured CP-odd fraction of the final state is 0.22 +/- 0.18(stat) +/- 0.03(syst).
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