Hadronic Spectral Moments in Semileptonic B Decays With a Lepton Energy Cut

We compute the first two moments of the final hadronic invariant mass in inclusive semileptonic B decay, in the presence of a cut on the charged lepton energy. These moments may be measured directly by experiments at the Upsilon(4S) using the neutrino reconstruction technique, which requires such a cut. Measurement of these moments will place constraints on the nonperturbative parameters \bar\Lambda and \lambda_1, which are relevant for extracting the quark masses m_b and m_c, as well as the CKM angle V_cb. We include terms of order \alpha_s^2\beta_0 and 1/m_b^3 in the operator product expansion, and use the latter to estimate the theoretical uncertainty in the extraction of \bar\Lambda and \lambda_1.Comment: 13 pages, 5 figures, REVTe

Implications of the B→XℓνˉℓB \to X \ell \bar\nu_\ell lepton spectrum for heavy quark physics

The shape of the lepton spectrum in inclusive semileptonic $B\to X\,\ell\,\bar\nu_\ell$ decay is sensitive to matrix elements of the heavy quark effective theory, $\bar\Lambda$ and $\lambda_1$. From CLEO data we extract $\bar\Lambda=0.39\pm0.11\,$GeV and $\lambda_1=-0.19\pm0.10\,{\rm GeV}^2$, where the uncertainty is the $1\sigma$ statistical error only. Systematic uncertainties are discussed. These values for $\bar\Lambda$ and $\lambda_1$ are used to determine $|V_{cb}|$ and the $\overline{\rm MS}$ bottom and charm quark masses. We discuss the theoretical uncertainties related to order $(\Lambda_{\rm QCD}/m_b)^3$ effects and higher orders in the perturbative expansion.Comment: 10 pages revtex + one figure. Corrections from secondary leptons included, that affect the numerical results. Thus the central values become $\bar\Lambda=0.39\pm0.11GeV$ and $\lambda_1=-0.19\pm0.10GeV^2

B decay and the Upsilon mass

Theoretical predictions for inclusive semileptonic B decay rates are rewritten in terms of the Upsilon(1S) meson mass instead of the b quark mass, using a modified perturbation expansion. This method gives theoretically consistent and phenomenologically useful results. Perturbation theory is well behaved, and the largest theoretical error in the predictions coming from the uncertainty in the quark mass is eliminated. The results are applied to the determination of $|V_{cb}|$, $|V_{ub}|$, and $\lambda_1$.Comment: 8 pages revte

Nonperturbative QCD Contributions to the Semileptonic Decay Width of the B Meson

Nonperturbative QCD contributions to the inclusive semileptonic decay of the B meson consist of the dynamic and kinematic components. We calculate the decay width in an approach based on the light-cone expansion and the heavy quark effective theory, which is able to include both components of nonperturbative QCD contributions. The kinematic component results in the phase-space extension and is shown to be quantitatively crucial, which could increase the decay width significantly. We find that the semileptonic decay width is enhanced by long-distance strong interactions by +(9\pm 6)%. This analysis is used to determine the CKM matrix element |V_{cb}| with a controlled theoretical error. Implications of the phase-space effects for the nonleptonic decay widths of b hadrons are briefly discussed. The experimental evidence for the phase-space effects is pointed out.Comment: 16 pages, Latex, 3 eps figures included, published version (discussion extended, references updated, the main result unchanged

Interlayer Coupling and p-wave Pairing in Strontium Ruthenate

On the basis of a three orbital model and an effective attractive interaction between electrons we investigate the possible superconducting states, with $p$ and $f$-wave internal symmetry, of Sr$_2$RuO$_4$. For an orbital dependent interaction which acts between in plane and out of plane nearest neighbour Ruthenium atoms we find a state for which the gap in the quasi-particle spectra has a line node on the $\alpha$ and $\beta$ sheets of the Fermi Surface, but it is complex with no nodes on the $\gamma$-sheet. We show that this state is consistent with all the available experimental data. In particular, we present the results of our calculations of the specific heat and penetration depth as functions of the temperature.Comment: 4 pages, 5 figure

Comprehension as social and intellectual practice: Rebuilding curriculum in low socioeconomic and cultural minority schools

This article reframes the concept of comprehension as a social and intellectual practice. It reviews current approaches to reading instruction for linguistically and culturally diverse and low socioeconomic students, noting an emphasis on comprehension as autonomous skills. The Four Resources model (Freebody & Luke, 1990) is used to make the case for the integration of comprehension instruction with an emphasis on student cultural and community knowledge, and substantive intellectual and sociocultural content in elementary school curricula. Illustrations are drawn from research underway on the teaching of literacy in primary schools in low SES communities

The Mass Definition in Hqet and a New Determination of Vcb_{\text{cb}}

Positive powers of the mass parameter in a physical quantity calculated with the help of heavy quark effective theory originate from a Wilson coefficient in the matching of QCD and HQET Green function. We show that this mass parameter enters the calculation as a well--defined running current mass. We further argue that the recently found ill--definition of the pole mass, which is the natural expansion parameter of HQET, does not affect a phenomenological analysis which uses truncated perturbative series. We reanalyse inclusive semileptonic decays of heavy mesons and obtain the $c$ quark mass $m_c^{\overline{\text{MS}}}(m_c) = (1.35\pm 0.20)\,\text{GeV}$ where the error is almost entirely due to scale--uncertainties. We also obtain $m_b^{\overline{\text{MS}}}(m_b) = (4.6\pm 0.3)\,\text{GeV}$ and $|V_{cb}|(\tau_B/1.49\,\text{ps})^{1/2} = 0.036\pm 0.005$ where the errors come from the uncertainty in the kinetic energy of the heavy quark inside the meson, in the experimental branching ratios, in QCD input parameters, and scale--uncertainties.Comment: 21 p., 5 figs, all style files incl., TUM-T31-56/R (Sec. 2 revised, phenomenological results unchanged

Hadron Spectra for Semileptonic Heavy Quark Decay

We calculate the leading perturbative and power corrections to the hadronic invariant mass and energy spectra in semileptonic heavy hadron decays. We apply our results to the $B$ system. Moments of the invariant mass spectrum, which vanish in the parton model, probe gluon bremsstrahlung and nonperturbative effects. Combining our results with recent data on $B$ meson branching ratios, we obtain a lower bound $\bar\Lambda>410\,{\rm MeV}$ and an upper bound $m_b^{\rm pole}<4.89\,$GeV. The Brodsky-Lepage-Mackenzie scale setting procedure suggests that higher order perturbative corrections are small for bottom decay, and even tractable for charm decay.Comment: 24 pages, uses REVTeX, 5 EPS figures embedded with epsf.sty, slightly modified version to appear in Phys. Rev.

Effect of Band Structure on the Symmetry of Superconducting States

Effects of the band structure on the symmetry of superconducting (SC) states are studied. For a square lattice system with a nearest-neighbor attractive interaction, SC states with various symmetries are found by changing the band structure, or, the shape of the Fermi surface. The spin-triplet ($(p_x + ip_y)$-wave) and spin-singlet ($d$- or s-wave) SC states, and states with their coexistence ($d + ip_y$, $s + ip_y$) can be stabilized within the same type of interaction. The stability of interlayer-pairing states with line nodes is also examined, and its relation to the SC state of Sr$_2$RuO$_4$ is discussed.Comment: 4 pages, 4 figure