Extracting ∣Vbc∣|V_{bc}|, mcm_c and mbm_b from Inclusive DD and BB Decays

Using recent results for nonperturbative contributions to the $B$ and $D$ meson inclusive semileptonic widths, a model independent extraction of \vbc, $m_c$ and $m_b$ is made from the experimentally measured $B$ and $D$ lifetimes and semileptonic branching ratios. Constraining the parameters of the HQET at \CO(1/m_Q^2) by the $D$ semileptonic width, \vbc is found to lie in the range .040<\vbc< 0.057. The $c$ and $b$ quark masses are not well constrained due to uncertainty in the relevant scale of $\alpha_s$. These results assume the validity of perturbative QCD at the low scales relevant to semileptonic charm decay. Without making this assumption, somewhat less stringent bounds on $V_{bc}$ from $B$ decay alone may be obtained.Comment: (revised version - contains a more detailed discussion of the uncertainty in our results from the uncertainty in the scale of \alpha_s) 12 pages, 5 figures included, uses harvmac.tex and epsf.tex, UCSD/PTH 93-25, UTPT 93-21, CMU-HEP 93-1

Heavy Quark Fragmentation to Baryons Containing Two Heavy Quarks

We discuss the fragmentation of a heavy quark to a baryon containing two heavy quarks of mass $m_Q\gg\Lambda_{\rm QCD}$. In this limit the heavy quarks first combine perturbatively into a compact diquark with a radius small compared to $1/\Lambda_{\rm QCD}$, which interacts with the light hadronic degrees of freedom exactly as does a heavy antiquark. The subsequent evolution of this $QQ$ diquark to a $QQq$ baryon is identical to the fragmentation of a heavy antiquark to a meson. We apply this analysis to the production of baryons of the form $ccq$, $bbq$, and $bcq$.Comment: 9 pages, 1 figure included, uses harvmac.tex and epsf.tex, UCSD/PTH 93-11, CALT-68-1868, SLAC-PUB-622

Hadronic Event Shapes in BB Decay

We compute the differential momentum correlation function for hadrons produced in the decay of $B$-mesons. This measure of hadronic event shapes tests the free $b$-quark decay picture for nonleptonic and semileptonic decays of $B$-mesons. Our results can also be applied to $B_s$ and $\Lambda_b$ decay.Comment: 11 pages, 3 uuencoded figures included, uses harvmac and epsf, UTPT 93-28, CMU-HEP 93-24, CALT-68-190

Curiosity search for non-equilibrium behaviors in a dynamically learned order parameter space

Exploring the spectrum of novel behaviors a physical system can produce can be a labor-intensive task. Active learning is a collection of iterative sampling techniques developed in response to this challenge. However, these techniques often require a pre-defined metric, such as distance in a space of known order parameters, in order to guide the search for new behaviors. Order parameters are rarely known for non-equilibrium systems \textit{a priori}, especially when possible behaviors are also unknown, creating a chicken-and-egg problem. Here, we combine active and unsupervised learning for automated exploration of novel behaviors in non-equilibrium systems with unknown order parameters. We iteratively use active learning based on current order parameters to expand the library of known behaviors and then relearn order parameters based on this expanded library. We demonstrate the utility of this approach in Kuramoto models of coupled oscillators of increasing complexity. In addition to reproducing known phases, we also reveal previously unknown behavior and related order parameters

How to assess technological developments in basic research? Enabling formative interventions regarding sustainability, ethics, and consumer issues at an early stage

In an era of ever faster and more momentous technological development, both technology assessment and transdisciplinary interventions are in danger of structurally lagging behind the speed of innovation. This paper proposes a new tiered approach to technology assessment at low Technology Readiness Levels that enables a both rapid and concerted interdisciplinary science response to this Great Acceleration. Covering sustainability, ethics, and consumer issues, this approach encourages and enables the innovators themselves to conduct assessments embedded in the innovation process as early as possible. Suitable tools for early engagement that help facilitate development-integrated assessments are introduced and described. The design and use of these instruments in the field of basic research is illustrated using the Cluster of Excellence livMatS as an example.In einer Ära immer rascherer und folgenreicherer technologischer Entwicklungen laufen sowohl die Technologiebewertung als auch transdisziplinäre Interventionen Gefahr, strukturell hinter der Dynamik von Innovationen zurückzubleiben. In diesem Beitrag wird ein neuer gestufter Ansatz für die Technikfolgenabschätzung für niedrige Technology Readiness Levels vorgeschlagen, der eine schnelle und konzertierte interdisziplinäre Reaktion der Wissenschaft auf diese "große Beschleunigung" ermöglicht. Dieser Ansatz, der Nachhaltigkeits-, Ethik- und Verbraucherfragen abdeckt, ermutigt und befähigt die Innovatoren, in den Innovationsprozess eingebettete Bewertungen so früh wie möglich selbst durchzuführen. Geeignete Instrumente für entwicklungsintegrierte Bewertungen werden vorgestellt und beschrieben. Die Konzeption und Anwendung dieser Instrumente im Bereich der Grundlagenforschung wird am Beispiel des Exzellenzclusters livMatS veranschaulicht

Renormalons in Effective Field Theories

We investigate the high-order behavior of perturbative matching conditions in effective field theories. These series are typically badly divergent, and are not Borel summable due to infrared and ultraviolet renormalons which introduce ambiguities in defining the sum of the series. We argue that, when treated consistently, there is no physical significance to these ambiguities. Although nonperturbative matrix elements and matching conditions are in general ambiguous, the ambiguity in any physical observable is always higher order in $1/M$ than the theory has been defined. We discuss the implications for the recently noticed infrared renormalon in the pole mass of a heavy quark. We show that a ratio of form factors in exclusive $\Lambda_b$ decays (which is related to the pole mass) is free from renormalon ambiguities regardless of the mass used as the expansion parameter of HQET. The renormalon ambiguities also cancel in inclusive heavy hadron decays. Finally, we demonstrate the cancellation of renormalons in a four-Fermi effective theory obtained by integrating out a heavy colored scalar.Comment: Minor changes mad

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.

Semileptonic BcB_c Decay and Heavy Quark Spin Symmetry

Semileptonic decay of the $B_c$ meson is studied in the heavy quark limit. The six possible form factors for $B_c \rightarrow B_s (B^0),B_s^* (B^{*0})$ semileptonic decay are determined by two invariant functions. Only one of these functions contributes at zero recoil, where it is calculable to lowest order in an operator product expansion in terms of the meson decay constant $f_B$ and the $B_c$ wavefunction. A similar result is found for $B_c \rightarrow D^0,D^{*0}$ and for $B_c\rightarrow\eta_c,J/\psi$ semileptonic decay for a restricted kinematic region. Semileptonic $B_c$ decay provides a means for determining the KM mixing angle $|V_{ub}|$.Comment: (12 Pages, no figures

Perturbative Strong Interaction Corrections to the Heavy Quark Semileptonic Decay Rate

We calculate the part of the order $\alpha_s^2$ correction to the semileptonic heavy quark decay rate proportional to the number of light quark flavors, and use our result to set the scale for evaluating the strong coupling in the order $\alpha_s$ term according to the scheme of Brodsky, Lepage and Mackenzie. Expressing the decay rate in terms of the heavy quark pole mass $m_Q$, we find the scale for the $\overline{MS}$ strong coupling to be $0.07\, m_Q$. If the decay rate is expressed in terms of the $\overline{MS}$ heavy quark mass $\overline m_Q(m_Q)$ then the scale is $0.12\, m_Q$. We use these results along with the existing calculations for hadronic $\tau$ decay to calculate the BLM scale for the nonleptonic decay width and the semileptonic branching ratio. The implications for the value of $|V_{bc}|$ extracted from the inclusive semileptonic $B$ meson decay rate are discussed.Comment: 7 pages in Latex plus 1 uuencoded figure, uses epsf, UTPT-94-24, CMU-HEP 94-29, CALT-68-1950 (previous results unchanged; we add a short discussion of nonleptonic decays

Non-1/m_b^n Power Suppressed Contributions to Inclusive b->s l+ l- Decays

We compute non-perturbative contributions to b->s l+ l- that are not explicitly suppressed by powers of the b-quark mass. They are proportional to lambda_2 and arise from an interference between the free-quark amplitude and higher order terms in the matrix element of a four-quark operator. This correction is found to be small over most of the dalitz plot except near the charm threshold. Unfortunately, the perturbative computation we have performed is invalid near charm threshold and we do not except to see the structure found at lowest order reproduced in the data. We conclude that these non-perturbative contributions do not significantly modify the previous analysis of b->s l+ l-.Comment: 8 pages, 3 figures, late