Theoretical treatment of multiple site reactivity in large molecules

The method of electrostatic potentials is generalized via a double perturbation theory to describe the simultaneous attack of a large molecule by two or more charged species. The interaction term is found to reproduce accurately the full “super-molecule” calculation. The scheme is illustrated by treating the diprotonation of adenine and N7-methyladenine. For adenine, the most stable diprotonated species is found to be the N1, N7 combination, while the N3, N9 couple is predicted for the N7 substituted derivative if N3 is the first protonation site.     

The zeros of the Artin l-series of a cubic field on the critical line

Denote by ψ(s) the Artin L-series of the non-abelian cubic field K. Let N₀(T) be the number of zeros of $\text{ψ(}\text{1}\text{2}\text{+ it)}$ for 0 < t ≤ T. Then for each ? > 0, there exists a positive constant T₀, such that for T > T₀:

$\text{N}{}_0\text{(T) > T}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(}\text{log}\text{2}\text{3}\text{T(}\text{loglog}\text{T)}{}^{\mathrm{<mtext>1</mtext><mtext>3</mtext><mtext>+?</mtext>}}\text{)}{}^{\mathrm{?1}}$

     

Study of the semileptonic charm decays D(0)-->pi(-)l(+)nu and D(0)-->K(-)l(+)nu

We investigate the decays D(0)-->pi(-)l(+)nu and D(0)-->K(-)l(+)nu, where l is e or mu, using approximately 7 fb(-1) of data collected with the CLEO III detector. We find R(0) identical with B(D(0)-->pi(-)e(+)nu)/B(D(0)-->K(-)e(+)nu)=0.082+/-0.006+/-0.005. Fits to the kinematic distributions of the data provide parameters describing the form factor of each mode. Combining the form factor results and R(0) gives |f(pi)(+)(0)|(2)|V(cd)|(2)/|f(K)(+)(0)|(2)|V(cs)|(2)=0.038(+0.006+0.005)(-0.007-0.003).     

Hydrostatic pressure dependence of negative-donor-ion singlet and singlet-like bound magnetoplasmon transitions in doped GaAs/AlGaAs quantum wells

Applied hydrostatic pressure modifies the Coulomb bound states of a quasi-two-dimensional electron gas in quantum wells by increasing the effective mass and by tuning the free electron density. Here, we explore these mechanisms by measuring the effects of pressure on the cyclotron resonance, the D⁰ 1s → 2p⁺ transition, and the D⁻-singlet and singlet-like transitions in low-and high-density, modulation-doped GaAs quantum wells. For low doping density, detailed calculations employing a pressure-dependent electron mass agree well with the observed magnetic field and pressure dependencies. For high doping density and low fields, the blue-shift of the D⁻-singlet-like transition at fields below 8 T decreases with applied pressure as anticipated, due to loss of free electrons via the Γ–X crossover. However, near 7.5 T, this singlet-like transition exhibits an anomalous branching for pressures above 4 kbar, which indicates the presence of a resonant level and obscures the blue-shift at high fields.     

Periodic nonlinear waves on a half-line

Nontrivial solutions of the equationu _tt=u _xx–g(u) which are 2-periodic int and which decay asx are shown to exist ifg(a)=0 andg(0)>1. Breather-like solutions, which also decay asx –, can be interpreted as homoclinic solutions in thex-dynamics; their existence is still in question for generalg.     

Nonlocality Without Nonlocality

Bell’s theorem is purported to demonstrate the impossibility of a local “hidden variable” theory underpinning quantum mechanics. It relies on the well-known assumption of ‘locality’, and also on a little-examined assumption called ‘statistical independence’ (SI). Violations of this assumption have variously been thought to suggest “backward causation”, a “conspiracy” on the part of nature, or the denial of “free will”. It will be shown here that these are spurious worries, and that denial of SI simply implies nonlocal correlation between spacelike degrees of freedom. Lorentz-invariant theories in which SI does not hold are easily constructed: two are exhibited here. It is conjectured, on this basis, that quantum-mechanical phenomena may be modeled by a local theory after all. This paper is dedicated to the memory of John A. Wheeler.     

Improved measurement of Vub with inclusive semileptonic B decays

We report a new measurement of the Cabibbo-Kobayashi-Maskawa parameter Vub made with a sample of 9.7 x 10(6) BB- events collected with the CLEO II detector. Using heavy quark theory, we combine the observed yield of leptons from semileptonic B decay in the end-point momentum interval 2.2-2.6 GeV/c with recent CLEO II data on B-->X(s)gamma to find Vub = (4.08+/-0.34+/-0.44+/-0.16+/-0.24)x10(-3), where the first two uncertainties are experimental and the last two are from theory.