Isospin-breaking effects on alpha extracted in B --> pi pi, rho rho, rho pi

Isospin-breaking in B --> pi pi caused by pi^0-eta-eta' mixing is studied in a model-independent way using flavor SU(3). Measured branching ratios for B^+ --> pi^+ pi^0, B^+ --> pi^+ eta^(') and B^0 --> pi^0 eta^(') imply an uncertainty in alpha smaller than 1.4 degree. We find a negligible effect of pi^0-eta-eta' mixing on alpha in B --> rho pi. Characterizing the effect of rho^0-omega mixing in B --> rho rho and in B --> rho pi by the two-pion invariant mass dependence, we point out a way of constraining this effect experimentally or eliminating it altogether. We show that a model-independent shift in alpha caused by electroweak penguin amplitudes in B --> pi pi and B --> rho rho, \Delta alpha_{EWP}=1.5+- 0.3 degree, may be slightly different in B --> rho pi. Other sources of isospin-breaking in these processes are briefly discussed.Comment: 21 pages, very slight changes, same version as in Physical Review

Semi-inclusive hadronic B decays as null tests of the Standard Model

We propose a new set of observables that can be used as experimental null tests of the Standard Model in charged and neutral B decays. The CP asymmetries in hadronic decays of charged B mesons into inclusive final states containing at least one of the following mesons: K_{S,L}, eta', c\bar c bound states or neutral K^* or D mesons, for all of which a U-spin rotation is equivalent to a CP conjugation, are CKM suppressed and furthermore vanish in the exact U-spin limit. We show how this reduces the theoretical error by using Soft Collinear Effective Theory to calculate the CP asymmetries for K_{S,L} X_{s+d}, K^* X_{s+d} and eta' X_{s+d} final states in the endpoint region. For these CP asymmetries only the flavor and not the charge of the decaying B meson needs to be tagged up to corrections of NLO in 1/m_b, making the measurements more accessible experimentally.Comment: 8 pages, significantly expanded after the observation that both neutral and charged B decays can be used, calculation for decays involving eta' adde

Regio and Stereospecific 2 + 2 Photoaddition of Cyclopentene to Pentafluoro-alkoxybenzene

2 + 2 photoaddition of cyclopentene to pentafluoro-alkoxybenzene in cyclohexane solution proceeds stereoselectively anti and regiospecifically to the 3,4 position

Electronic Structure of Hydrazinium (2 + ) Ion. A Semiempirical MO Treatment

A simple semiempjrical MO treatment of the electronic structure of hydrazinium (2 + ) ion was carried out on the basis of an extended Htickel method. The electronic population analysis for nitrogen and hydrogen atoms in this ion was calculated to b e (ls) 2 (2s)1 -121 (2px)1 ·3Go (2py)t·3Go (2p z)o .9BG and (ls)0o122, respectively

On measuring alpha in B(t)-> rho^\pm pi^\mp

Defining a most economical parametrization of time-dependent B-> rho^\pm pi^\mp decays, including a measurable phase alpha_{eff} which equals the weak phase alpha in the limit of vanishing penguin amplitudes, we propose two ways for determining alpha in this processes. We explain the limitation of one method, assuming only that two relevant tree amplitudes factorize and that their relative strong phase, delta_t, is negligible. The other method, based on broken flavor SU(3), permits a determination of alpha in B^0-> rho^\pm pi^\mp in an overconstrained system using also rate measurements of B^{0,+}-> K^* pi and B^{0,+}->rho K. Current data are shown to restrict two ratios of penguin and tree amplitudes, r_\pm, to a narrow range around 0.2, and to imply an upper bound |alpha_{eff} - alpha| < 15 degrees. Assuming that delta_t is much smaller than 90 degrees, we find alpha =(93\pm 16) degrees and (102 \pm 20) degrees using BABAR and BELLE results for B(t)-> rho^\pm pi^mp. Avoiding this assumption for completeness, we demonstrate the reduction of discrete ambiguities in alpha with increased statistics, and show that SU(3) breaking effects are effectively second order in r_\pm.Comment: 23 pages, 2 figures, data and references updated, to be published in Phys. Rev.