The Inclusive Semileptonic Decay Lepton Spectrum from B→Xeν‾B \to X e \overline{\nu}

In this talk, we review the QCD calculation of the lepton spectrum from inclusive semileptonic $B$ decay. We compare this prediction to that of the ACCMM model. This latter work was done in collaboration with Csaba Csaki.Comment: MIT-CTP-2333, uses LATEX. Invited Talk, Presented at WHEPP-3 Workshop in Madras,India, January, 199

More on Symmetries in Heavy Quark Effective Theory

We present a general classification of all normal and ``chiral" symmetries of heavy quark effective theories. Some peculiarities and conondrums associated with the ``chiral" symmetries are discussed.Comment: 15 pages, preprint UR-1320, ER40685-77

Spin Coherence During Optical Excitation of a Single NV Center in Diamond

We examine the quantum spin state of a single nitrogen-vacancy (NV) center in diamond at room temperature as it makes a transition from the orbital ground-state (GS) to the orbital excited-state (ES) during non-resonant optical excitation. While the fluorescence read-out of NV-center spins relies on conservation of the longitudinal spin projection during optical excitation, the question of quantum phase preservation has not been examined. Using Ramsey measurements and quantum process tomography, we establish limits on NV center spin decoherence induced during optical excitation. Treating the optical excitation and ES spin precession as a quantum process, we measure a process fidelity of F=0.87\pm0.03, which includes ES spin dephasing during measurement. Extrapolation to the moment of optical excitation yields F\approx0.95. This result demonstrates that ES spin interactions may be used as a resource for quantum control because the quantum spin state can survive incoherent orbital transitions.Comment: 12 pages, 3 figure

Higher Order 1/m1/m Corrections at Zero Recoil

The general structure of the $1/m$ corrections at zero recoil is studied. The relevant matrix elements are forward matrix elements of local higher dimensional operators and their time ordered products with higher order terms from the Lagrangian. These matrix elements may be classified in a simple way and the analysis at the non recoil point for the form factor of heavy quark currents simplifies drastically. The second order recoil corrections to the form factor $h_{A1}$ of the axial vector current, relevant for the $|V_{cb}|$ determination from $B \to D^*$ decays, are estimated to be $-5\% < h_{A1} - 1 < 0$.Comment: LaTeX, 25 pages, one figure, appended after \end{document} as uu-encoded and compressed eps file, uses epsf, CERN-TH.7162/9

Radiative Leptonic Decays of Heavy Mesons

We compute the photon spectrum and the rate for the decays $B(D)\to l\nu_l\gamma$ These photonic modes constitute a potentially large background for the purely leptonic decays which are used to extract the heavy meson decay constants. While the rate for D\to l\n\g is small, the radiative decay in the $B$ meson case could be of comparable magnitude or even larger than B\to\m\n. This would affect the determination of $f_B$ if the $\tau$ channel cannot be identified. We obtain theoretical estimates for the photonic rates and disscuss their possible experimental implications.Comment: 12 pages, RevTex, 3 uuencoded figures include

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

Critical points and resonance of hyperplane arrangements

If F is a master function corresponding to a hyperplane arrangement A and a collection of weights y, we investigate the relationship between the critical set of F, the variety defined by the vanishing of the one-form w = d log F, and the resonance of y. For arrangements satisfying certain conditions, we show that if y is resonant in dimension p, then the critical set of F has codimension at most p. These include all free arrangements and all rank 3 arrangements.Comment: revised version, Canadian Journal of Mathematics, to appea

CP violation for neutral charmed meson decays to CP eigenstates

CP asymmetries for neutral charmed meson decays to CP eigenstates are carefully studied. The formulas and numerical results are presented. The impact on experiments is briefly discussed.Comment: 7 pages, 1 figure, 1 table, Revte

Methods of Nature: Landscapes from the Gettysburg College Collection

Methods of Nature: Landscapes from the Gettysburg College Collection is the third annual exhibition curated by students enrolled in the Art History Methods course. The exhibition is an exciting academic endeavor and incredible opportunity for engaged learning, research, and curatorial experience. The five student curators are Molly Chason ’17, Leah Falk ’18, Shannon Gross ’17, Bailey Harper ’19 and Laura Waters ’19. The selection of artworks in this exhibition includes the depiction of landscape in the nineteenth- and twentieth-century French, American and East Asian cultural traditions in various art forms from traditional media of paintings and prints to utilitarian artifacts of porcelain and a paper folding fan. Landscape paintings in this exhibition are inspired by nature, specific locales and literature. Each object carries a distinctive characteristic, a mood, and an ambience. Collectively, they present a multifaceted view of the landscape in the heart and mind of the artists and intended viewers. [excerpt]https://cupola.gettysburg.edu/artcatalogs/1020/thumbnail.jp

Sum rules in the heavy quark limit of QCD

In the leading order of the heavy quark expansion, we propose a method within the OPE and the trace formalism, that allows to obtain, in a systematic way, Bjorken-like sum rules for the derivatives of the elastic Isgur-Wise function $\xi(w)$ in terms of corresponding Isgur-Wise functions of transitions to excited states. A key element is the consideration of the non-forward amplitude, as introduced by Uraltsev. A simplifying feature of our method is to consider currents aligned along the initial and final four-velocities. As an illustration, we give a very simple derivation of Bjorken and Uraltsev sum rules. On the other hand, we obtain a new class of sum rules that involve the products of IW functions at zero recoil and IW functions at any $w$. Special care is given to the needed derivation of the projector on the polarization tensors of particles of arbitrary integer spin. The new sum rules give further information on the slope $\rho^2 = - \xi '(1)$ and also on the curvature $\sigma^2 = \xi '' (1)$, and imply, modulo a very natural assumption, the inequality $\sigma^2 \geq {5\over 4} \rho^2$, and therefore the absolute bound $\sigma^2 \geq {15 \over 16}$.Comment: 64 pages, Late