Quark mass effects in the soft-collinear effective theory and B -> X_s + photon in the endpoint region

We consider the effects of a light quark mass in the soft-collinear effective theory (SCET) and we apply them to B -> X_s gamma in the endpoint region. We find that the reparameterization invariance can be extended by including the collinear quark mass in the SCET Lagrangian. This symmetry constrains the theory with the quark mass terms, and we present explicit results at one loop. It also relates the Wilson coefficients of some mass operators to those of the leading operators, which are useful in organizing the subleading effects due to the quark mass in B -> X_s gamma. We present strange quark mass corrections to B -> X_s gamma in the endpoint region as an application. The forward scattering amplitude from the mass corrections is factorized, and it can be expressed as a convolution of the m_s^2/p_X^2-suppressed jet function and the leading-order shape function of the B meson. This contribution should be added to the existing subleading contributions from the B meson shape functions to obtain complete subleading corrections.Comment: 30 pages, 6 figures; some errors are corrected and numerical estimates are adde

Probing electroweak physics using B -> XM decays in the endpoint region

Using soft-collinear effective theory we describe at leading order in 1/m_b all the semi-inclusive hadronic B -> XM decays near the endpoint, where an energetic light meson M recoils against an inclusive jet X. We also include the decays involving eta, eta' mesons that receive additional contributions from gluonic operators. The predicted branching ratios and CP asymmetries depend on fewer hadronic parameters than the corresponding two-body B decays. This makes semi-inclusive hadronic B -> XM decays a powerful probe of the potential nonperturbative nature of charming penguins as well as a useful probe of new physics effects in electroweak flavor changing transitions. A comparison with B -> KX data from BaBar points to an enhanced charming penguin, albeit with large experimental errors.Comment: 27 pages, 6 figure

Localized transverse bursts in inclined layer convection

We investigate a novel bursting state in inclined layer thermal convection in which convection rolls exhibit intermittent, localized, transverse bursts. With increasing temperature difference, the bursts increase in duration and number while exhibiting a characteristic wavenumber, magnitude, and size. We propose a mechanism which describes the duration of the observed bursting intervals and compare our results to bursting processes in other systems.Comment: 4 pages, 8 figure

Multiparameter Moment Matching Model Reduction Approach for Generating Geometrically Parameterized Interconnect Performance Models

In this paper we describe an approach for generating geometrically-parameterized integrated-circuit interconnect models that are efficient enough for use in interconnect synthesis. The model generation approach presented is automatic, and is based on a multi-parameter model-reduction algorithm. The effectiveness of the technique is tested using a multi-line bus example, where both wire spacing and wire width are considered as geometric parameters. Experimental results demonstrate that the generated models accurately predict both delay and cross-talk effects over a wide range of spacing and width variation.Singapore-MIT Alliance (SMA

SCET sum rules for heavy-to-light form factors

We consider a sum rule for heavy-to-light form factors in soft-collinear effective theory (SCET). Using the correlation function given by the time-ordered product of a heavy-to-light current and its hermitian conjugate, the heavy-to-light soft form factor zeta_P can be related to the leading-order B meson shape function. Using the scaling behavior of the heavy-to-light form factor in Lambda_QCD/m_b, we put a constraint on the behavior of the $B$ meson shape function near the endpoint. We employ the sum rule to estimate the size of zeta_P with the model for the shape function and find that it ranges from 0.01 to 0.07.Comment: 11 pages, 5 figure

Inclusive Semileptonic Decays in QCD Including Lepton Mass Effects

Starting from an Operator Product Expansion in the Heavy Quark Effective Theory up to order 1/m_b^2 we calculate the inclusive semileptonic decays of unpolarized bottom hadrons including lepton mass effects. We calculate the differential decay spectra d\Gamma/(dE_\tau ), and the total decay rate for B meson decays to final states containing a \tau lepton.Comment: 16 pages + 4 figs. appended in uuencoded form, LaTeX, MZ-TH/93-3

Enhanced subleading structure functions in semileptonic B decay

The charged lepton spectrum in semileptonic $B\to X_u \ell\bar\nu$ decay near maximal lepton energy receives important corrections from subleading structure functions that are formally suppressed by powers of $\Lambda_{QCD}/m_b$ but are enhanced by numerical factors. We investigate the series of higher order terms which smear over a region of width $\Delta E_\ell \sim \Lambda_{QCD}$ near the endpoint the contributions proportional to $\delta(E_\ell - m_b/2)$ times (i) the matrix element of the chromomagnetic operator, and (ii) four-quark operators. These contribute to the total rate at the few percent level, but affect the endpoint region much more significantly. Implications for the determination of $|V_{ub}|$ are discussed.Comment: 12 page

Perturbative Corrections to a Sum Rule for the Heavy Quark Kinetic Energy

We calculate the perturbative corrections to order \alpha_s^2\beta_0 to the sum rule derived from the second moment of the time-ordered product of b \to c currents near zero recoil. This sum rule yields a bound on \lambda_1, the expectation value of the b quark kinetic energy operator inside the B meson. The perturbative corrections significantly weaken the bound relative to the tree level result, yielding \lambda_1 < -0.15 GeV^2.Comment: 10 pages revtex, uses FEYNMA