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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2012). Branching fraction of tau(-) -> pi(-KsKs0)-K-0(pi(0))nu(tau) decays. Phys. Rev. D, 86(9), 092013–9pp.
Abstract: We present a study of tau(-) -> pi(-KsKs0)-K-0(pi(0))nu(tau) and tau(-) -> (K-KsKs0)-K-0(pi(0))nu(tau) decays using a data set of 430 million tau lepton pairs, corresponding to an integrated luminosity of 468 fb(-1), collected with the BABAR detector at the PEP-II asymmetric energy e(+)e(-) storage rings. We measure branching fractions of (2.31 +/- 0.04 +/- 0.08) x 10(-4) and (1.60 +/- 0.20 +/- 0.22) x 10(-5) for the tau(-) -> pi(-KsKs0)-K-0 nu(tau) and tau(-) -> pi(-KsKs0)-K-0 pi(0)nu(tau) decays, respectively. We find no evidence for tau(-) -> (K-KsKs0)-K-0 nu(tau) and tau(-) -> (K-KsKs0)-K-0 pi(0)nu(tau) decays and place upper limits on the branching fractions of 6.3 x 10(-7) and 4.0 x 10(-7) at the 90% confidence level.
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Boubekeur, L., Dodelson, S., & Vives, O. (2012). Cold positrons from decaying dark matter. Phys. Rev. D, 86(10), 103520–14pp.
Abstract: Many models of dark matter contain more than one new particle beyond those in the Standard Model. Often, heavier particles decay into the lightest dark matter particle as the Universe evolves. Here, we explore the possibilities which arise if one of the products in a (heavy particle) -> (dark matter) decay is a positron, and the lifetime is shorter than the age of the Universe. The positrons cool down by scattering off the cosmic microwave background and eventually annihilate when they fall into Galactic potential wells. The resulting 511 keV flux not only places constraints on this class of models, but might even be consistent with that observed by the INTEGRAL satellite.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Study of the baryonic B decay B- -> Sigma(++)(c) (p)over-bar pi(-)pi(-). Phys. Rev. D, 86(9), 091102–8pp.
Abstract: We report the measurement of the baryonic B decay B- -> Sigma(++)(c)(p) over bar pi(-)pi(-). Using a data sample of 467 x 10(6) B (B) over bar pairs collected with the BABAR detector at the PEP-II storage ring at SLAC, the measured branching fraction is (2.98 +/- 0.16((stat)) +/- 0.15((syst)) +/- 0.77((Ac))) x 10(-4), where the last error is due to the uncertainty in B(A(c)(+) -> pK(-)pi(+)). The data suggest the existence of resonant subchannels B- -> A(c)(2595)(+) (p) over bar pi(-) and, possibly, B- -> Sigma(++)(c) (Delta) over bar (--)pi(-). We see unexplained structures in m(Sigma(++)(c)pi(-)pi(-)) at 3.25 GeV/c(2), 3.8 GeV/c(2), and 4.2 GeV/c(2).
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Aceti, F., Liang, W. H., Oset, E., Wu, J. J., & Zou, B. S. (2012). Isospin breaking and f(0)(980)-a(0)(980) mixing in the eta(1405) -> pi(0)f(0)(980) reaction. Phys. Rev. D, 86(11), 114007–11pp.
Abstract: We make a theoretical study of the eta(1405) -> pi(0)f(0)(980) and eta(1405) -> pi(0)a(0)(980) reactions with an aim to determine the isospin violation and the mixing of the f(0)(980) and a(0)(980) resonances. We make use of the chiral unitary approach where these two resonances appear as composite states of two mesons, dynamically generated by the meson-meson interaction provided by chiral Lagrangians. We obtain a very narrow shape for the f(0)(980) production in agreement with a BES experiment. As to the amount of isospin violation, or f(0)(980) and a(0)(980) mixing, assuming constant vertices for the primary eta(1405) -> pi K-0 (K) over bar and eta(1405) -> pi(0)pi(0)eta production, we find results which are much smaller than found in the recent experimental BES paper, but consistent with results found in two other related BES experiments. We have tried to understand this anomaly by assuming an I = 1 mixture in the eta(1405) wave function, but this leads to a much bigger width of the f(0)(980) mass distribution than observed experimentally. The problem is solved by using the primary production driven by eta' -> K*(K) over bar followed by K* -> K pi, which induces an extra singularity in the loop functions needed to produce the f(0)(980) and a(0)(980) resonances. Improving upon earlier work along the same lines, and using the chiral unitary approach, we can now predict absolute values for the ratio Gamma(pi(0), pi(+)pi(-))/Gamma(pi(0), pi(0)eta) which are in fair agreement with experiment. We also show that the same results hold if we had the eta(1475) resonance or a mixture of these two states, as seems to be the case in the BES experiment.
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Denner, A., Hosekova, L., & Kallweit, S. (2012). Next-to-leading order QCD corrections to W(+)W(+)jj production in vector-boson fusion at the LHC. Phys. Rev. D, 86(11), 114014–19pp.
Abstract: We present a next-to-leading order QCD calculation for e(+)nu(e)mu(+)nu(mu)jj production in vector-boson fusion, i.e., the scattering of two positively charged W bosons at the LHC. We include the complete set of electroweak leading order diagrams for the six-particle final state and quantitatively assess the size of the s-channel and interference contributions in vector-boson fusion kinematics. The calculation uses the complex-mass scheme to describe the W-boson resonances and is implemented into a flexible Monte Carlo generator. Using a dynamical scale based on the transverse momenta of the jets, the QCD corrections stay below about 10% for all considered observables, while the residual scale dependence is at the level of 1%.
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