|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2013). Search for a low-mass scalar Higgs boson decaying to a tau pair in single-photon decays of Y(1S). Phys. Rev. D, 88(7), 071102–8pp.
Abstract: We search for a low-mass scalar CP-odd Higgs boson, A(0), produced in the radiative decay of the upsilon resonance and decaying into a tau(+)tau(-) pair: Y(1S) -> gamma A(0). The production of Y(1S) mesons is tagged by Y(2S) -> pi(+)pi(-) Y(1S) transitions, using a sample of (98.3 +/- 0.9) x 10(6) Y(2S) mesons collected by the BABAR detector. We find no evidence for a Higgs boson in the mass range 3: 5 <= m(A)0 <= 9: 2 GeV, and combine these results with our previous search for the tau decays of the light Higgs in radiative Y(3S) decays, setting limits on the coupling of A(0) to the b (b) over bar quarks in the range 0.09-1.9. Our measurements improve the constraints on the parameters of the next-to-minimal-supersymmetric Standard Model and similar theories with low-mass scalar degrees of freedom.
|
|
|
Vijande, J., Valcarce, A., & Richard, J. M. (2013). Adiabaticity and color mixing in tetraquark spectroscopy. Phys. Rev. D, 87(3), 034040–5pp.
Abstract: We revisit the role of color mixing in the quark model calculation of tetraquark states, and compare simple pairwise potentials to more elaborate string models with three-and four-body forces. We attempt to disentangle the improved dynamics of confinement from the approximations made in the treatment of the internal color degrees of freedom.
|
|
|
Garcia-Recio, C., Geng, L. S., Nieves, J., Salcedo, L. L., Wang, E., & Xie, J. J. (2013). Low-lying even parity meson resonances and spin-flavor symmetry revisited. Phys. Rev. D, 87(9), 096006–18pp.
Abstract: We review and extend the model derived in Garcia-Recio et al. [Phys. Rev. D 83, 016007 (2011)] to address the dynamics of the low-lying even-parity meson resonances. This model is based on a coupled-channels spin-flavor extension of the chiralWeinberg-Tomozawa Lagrangian. This interaction is then used to study the S-wave meson-meson scattering involving members not only of the pi octet, but also of the rho nonet. In this work, we study in detail the structure of the SU(6)-symmetry-breaking contact terms that respect (or softly break) chiral symmetry. We derive the most general local (without involving derivatives) terms consistent with the chiral-symmetry-breaking pattern of QCD. After introducing sensible simplifications to reduce the large number of possible operators, we carry out a phenomenological discussion of the effects of these terms. We show how the inclusion of these pieces leads to an improvement of the description of the J(P) = 2(+) sector, without spoiling the main features of the predictions obtained in the original model in the JP = 0(+) and J(P) = 1(+) sectors. In particular, we find a significantly better description of the I-G(J(PC)) =0(+)(2(++)), 1(-)(2(++)) and the I(JP)=1/2(2(+)) sectors, which correspond to the f(2)(1270), a(2)(1320), and K-2(*)(1430) quantum numbers, respectively.
|
|
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2013). Observation of direct CP violation in the measurement of the Cabibbo-Kobayashi-Maskawa angle gamma with B-+/- -> Dd(()*()) K-(*()+/-) decays. Phys. Rev. D, 87(5), 052015–12pp.
Abstract: We report the determination of the Cabibbo-Kobayashi-Maskawa CP-violating angle gamma through the combination of various measurements involving B-+/- -> DK +/-, B-+/- -> D*K-+/-, and B-+/- -> DK*(+/-) decays performed by the BABAR experiment at the PEP-II e(+)e(-) collider at SLAC National Accelerator Laboratory. Using up to 474 million B (B) over bar pairs, we obtain gamma = (69(-16)(+17))degrees modulo 180 degrees. The total uncertainty is dominated by the statistical component, with the experimental and amplitude-model systematic uncertainties amounting to +/- 4 degrees. The corresponding two-standard-deviation region is 41 degrees < gamma < 102 degrees. This result is inconsistent with gamma = 0 with a significance of 5.9 standard deviations.
|
|
|
Campanario, F., Kerner, M., Ninh, L. D., & Zeppenfeld, D. (2013). WZ production in association with two jets at next-to-leading order in QCD. Phys. Rev. Lett., 111(5), 052003–4pp.
Abstract: We report on the calculation of W-+/- Zjj production with leptonic decays at hadron-hadron colliders at next-to-leading order in QCD. These processes are important both to test the quartic gauge couplings of the standard model and because they constitute relevant backgrounds to beyond standard model physics searches. Our results show that the next-to-leading order corrections reduce significantly the scale uncertainties and have a nontrivial phase space dependence.
|
|