Path Integrals, Density Matrices, and Information Flow with Closed Timelike Curves

Two formulations of quantum mechanics, inequivalent in the presence of closed timelike curves, are studied in the context of a soluable system. It illustrates how quantum field nonlinearities lead to a breakdown of unitarity, causality, and superposition using a path integral. Deutsch's density matrix approach is causal but typically destroys coherence. For each of these formulations I demonstrate that there are yet further alternatives in prescribing the handling of information flow (inequivalent to previous analyses) that have implications for any system in which unitarity or coherence are not preserved.Comment: 25 pages, phyzzx, CALT-68-188

ρ\rho Polarization and `Model Independent' Extraction of ∣Vub∣/∣Vcd∣|V_{ub}|/|V_{cd}| from D→ρℓνD\to\rho\ell\nu and B→ρℓνB\to\rho\ell\nu

We briefly discuss the predictions of the heavy quark effective theory for the semileptonic decays of a heavy pseudoscalar to a light one, or to a light vector meson. We point out that measurement of combinations of differential helicity decay rates at Cleo-c and the $B$ factories can provide a model independent means of extracting the ratio $|V_{ub}|/|V_{cd}|$. We briefly discuss the corrections to this prediction.Comment: 8 pages, LaTeX, 1 figur

Breakdown of scaling in neutrino and electron scattering

Observation of deviations from scaling in the structure functions for deep-inelastic inclusive lepton-hadron scattering may provide a test of the hypothesis that the strong interactions are described by an asymptotically free field theory. Tests not involving additional assumptions are obtained for the combinations of structure functions F2 (ep)-F2 (en), F2 (ν)-F2 (ν), and xF3(ν or ν). Neutrino and electron scattering experiments are compared as possible tests of asymptotic freedom

Arcus senilis corneae-its relationship to serum lipids in the South African bantu

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Can a strongly interacting Higgs boson rescue SU(5)?

Renormalization group analyses show that the three running gauge coupling constants of the Standard Model do not become equal at any energy scale. These analyses have not included any effects of the Higgs boson's self-interaction. In this paper, I examine whether these effects can modify this conclusion.Comment: 8 pages (plus 4 postscript figures

Urinary Calculi

The chemical composition of 256 urinary calculi on the Witwatersrand has been determined in 3 population groups. 'Calcium stones' comprised 53,1% of the total and most of the remainder were triple phosphate. The distribution of these stones in the different population groups was similar. Urinary calculi are rare in the Bantu.S. Afr. Med. J., 47, 128 (1973

Laryngeal features are phonetically abstract : mismatch negativity evidence from Arabic, English, and Russian

2016-2017 > Academic research: refereed > Publication in refereed journal201804_a bcmaVersion of RecordPublishe

QCD Factorization for B→ππB\to\pi\pi Decays: Strong Phases and CP Violation in the Heavy Quark Limit

We show that, in the heavy quark limit, the hadronic matrix elements that enter $B$ meson decays into two light mesons can be computed from first principles, including `non-factorizable' strong interaction corrections, and expressed in terms of form factors and meson light-cone distribution amplitudes. The conventional factorization result follows in the limit when both power corrections in $1/m_b$ and radiative corrections in $\alpha_s$ are neglected. We compute the order-$\alpha_s$ corrections to the decays $B_d\to\pi^+\pi^-$, $B_d\to\pi^0\pi^0$ and $B^+\to\pi^+\pi^0$ in the heavy quark limit and briefly discuss the phenomenological implications for the branching ratios, strong phases and CP violation.Comment: 6 pages, 1 figur

Multiplicative renormalizability and quark propagator

The renormalized Dyson-Schwinger equation for the quark propagator is studied, in Landau gauge, in a novel truncation which preserves multiplicative renormalizability. The renormalization constants are formally eliminated from the integral equations, and the running coupling explicitly enters the kernels of the new equations. To construct a truncation which preserves multiplicative renormalizability, and reproduces the correct leading order perturbative behavior, non-trivial cancellations involving the full quark-gluon vertex are assumed in the quark self-energy loop. A model for the running coupling is introduced, with infrared fixed point in agreement with previous Dyson-Schwinger studies of the gauge sector, and with correct logarithmic tail. Dynamical chiral symmetry breaking is investigated, and the generated quark mass is of the order of the extension of the infrared plateau of the coupling, and about three times larger than in the Abelian approximation, which violates multiplicative renormalizability. The generated scale is of the right size for hadronic phenomenology, without requiring an infrared enhancement of the running coupling.Comment: 17 pages; minor corrections, comparison to lattice results added; accepted for publication in Phys. Rev.