Rates, polarizations, and asymmetries in charmless vector-vector B meson decays

With a sample of approximately 89 x 10(6) B(-)B pairs collected with the BABAR detector, we perform a search for B meson decays into pairs of charmless vector mesons (phi, rho, and K*). We measure the branching fractions, determine the degree of longitudinal polarization, and search for CP violation asymmetries in the processes B+-->phiK(*+), B0-->phiK(*0), B+-->rho(0)K(*+), and B+-->rho(0)rho(+). We also set an upper limit on the branching fraction for the decay B0-->rho(0)rho(0).     

Rare B decays into states containing a J/psi meson and a meson with s(-)s quark content

We report a study of the B meson decays, B+ --> J/psiphiK+, B0 --> J/psiphiK(0)(S), B0 --> J/psiphi, B0 --> J/psieta, and B0 --> J/psieta' using 56 x 10(6) B(-)B events collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II e(+)e(-) asymmetric-energy storage ring. We measure the branching fractions B(B+ --> J/psiphiK+)=(4.4+/-1.4(stat)+/-0.5(syst))x 10(-5) and B(B0 --> J/psiphiK(0)(S))=(5.1+/-1.9(stat)+/-0.5(syst))x 10(-5), and set upper limits at 90% confidence level for the branching fractions B(B0 --> J/psiphi)<9.2 x 10(-6), B(B0 --> J/psieta)<2.7 x 10(-5), and B(B0 --> J/psieta')<6.3 x 10(-5).     

Measurements of the branching fractions and bounds on the charge asymmetries of charmless three-body charged B decays

We present measurements of branching fractions and charge asymmetries for charmless B-meson decays to three-body final states of charged pions and kaons. The analysis uses 81.8 fb(-1) of data collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC PEP-II asymmetric B Factory. We measure the branching fractions B(B+-->pi(+)pi(-)pi(+))=(10.9+/-3.3+/-1.6)x10(-6), B(B+-->K+pi(-)pi(+))=(59.1+/-3.8+/-3.2)x10(-6), and B(B+-->K+K-K+)=(29.6+/-2.1+/-1.6)x10(-6) and provide 90% C.L. upper limits for other decays. We observe no charge asymmetries for these modes.     

Optimal labeling of point features in rectangular labeling models

 We investigate the NP–hard label number maximization problem (LNM): Given a set of rectangular labels Λ, each of which belongs to a point feature in the plane, the task is to find a labeling for a largest subset Λ _P of Λ. A labeling is a placement such that none of the labels overlap and each λΛ _P is placed according to a labeling model: In the discrete models, the label must be placed so that the labeled point coincides with an element of a predefined subset of corners of the rectangular label, in the continuous or slider models, the point must lie on a subset of boundaries of the label. Obviously, the slider models allow a continuous movement of a label around its point feature, leading to a significantly higher number of labels that can be placed. We present exact algorithms for this problem that are based on a pair of so-called constraint graphs that code horizontal and vertical positioning relations. The key idea is to link the two graphs by a set of additional constraints, thus characterizing all feasible solutions of LNM. This enables us to formulate a zero-one integer linear program whose solution leads to an optimal labeling. We can express LNM in both the discrete and the slider labeling models. To our knowledge, we present the first algorithm that computes provably optimal solutions in the slider models. We find it remarkable that our approach is independent of the labeling model and results in a discrete algorithm even if the problem is of continuous nature as in the slider models. Extensive experimental results on both real-world instances and point sets created by a widely used benchmark generator show that the new approach - although being an exponential time algorithm - is applicable in practice. Received: November 20, 2000 / Accepted: April 9, 2002 Published online: September 5, 2002 RID="★" ID="★" This work is partially supported by the German Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie (No. 03-MU7MP1-4). Key words. map labeling – point feature map labeling – constraint graphs – combinatorial optimization – integer programming     

Observation of CP violation in the B(0) meson system

We present an updated measurement of time-dependent CP-violating asymmetries in neutral B decays with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. This result uses an additional sample of Upsilon(4S) decays collected in 2001, bringing the data available to 32 x 10(6) BB macro pairs. We select events in which one neutral B meson is fully reconstructed in a final state containing charmonium and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the standard model is proportional to sin2 beta, is derived from the decay time distributions in such events. The result sin2 beta = 0.59+/-0.14(stat)+/-0.05(syst) establishes CP violation in the B(0) meson system. We also determine absolute value of lambda = 0.93+/-0.09(stat)+/-0.03(syst), consistent with no direct CP violation.     

Convergence of a Tuy-type algorithm for concave minimization subject to linear inequality constraints

A modification of Tuy's cone splitting algorithm for minimizing a concave function subject to linear inequality constraints is shown to be convergent by demonstrating that the limit of a sequence of constructed convex polytopes contains the feasible region. No geometric tolerance parameters are required.Research supported by National Science Foundation Grant ENG 76-12250     

Synthesis of 4-methylthio-1,2-dithiolane and 5-methylthio-1,2,3-trithiane. Two naturally occurring bioactive compounds

Syntheses of the title compounds are described. A method has been developed for the synthesis of 2-methylthio-1,3-propanedithiol, which on treatment with iodine or sulphurdichloride yields 4-methylthio-1,2-dithiolane and 5-methylthio-1,2,3-trithiane respectively.