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Roca, L., & Oset, E. (2010). Description of the f(2)(1270), rho(3)(1690), f(4)(2050), rho(5)(2350), f(6)(2510) resonances as multi-rho(770) states. Phys. Rev. D, 82(5), 054013–11pp.
Abstract: In a previous work regarding the interaction of two rho(770) resonances, the f(2)(1270) (J(PC) = 2(++)) resonance was obtained dynamically as a two-rho molecule with a very strong binding energy, 135 MeV per rho particle. In the present work we use the rho rho interaction in spin 2 and isospin 0 channel to show that the resonances rho(3)(1690) (3(--)), f(4)(2050) (4(++)), rho(5)(2350) (5(--)), and f(6)(2510) (6(++)) are basically molecules of increasing number of rho(770) particles. We use the fixed center approximation of the Faddeev equations to write the multibody interaction in terms of the two-body scattering amplitudes. We find the masses of the states very close to the experimental values and we get an increasing value of the binding energy per rho as the number of rho mesons is increased.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Measurement of the B-0 -> pi(-)l(+)nu and B+ -> eta(l)l(+)nu branching fractions, the B-0 -> pi(-)l(+)nu and B+ -> eta l(+)nu form- factor shapes, and determination of |Vub|. Phys. Rev. D, 83(5), 052011–16pp.
Abstract: We report the results of a study of the exclusive charmless semileptonic decays, B+ -> eta(l)l(+)nu and B-0 -> pi(-)l(+)nu undertaken with approximately 464 x 10(6) B (B) over bar pairs collected at the Y(4S) resonance with the BABAR detector. The analysis uses events in which the signal B decays are reconstructed with a loose neutrino reconstruction technique. We obtain partial branching fractions for B+ -> eta l(+)nu and B-0 -> pi(-)l(+)nu decays in three and 12 bins of q(2), respectively, from which we extract the f (+)(q(2)) form-factor shapes and the total branching fractions B(B+ -> eta l(+)nu)= (0.36 +/- 0.05(stat) +/- 0.04(syst)) x 10(-4) and B(B-0 -> pi(-)l(+)nu) = (1.42 +/- 0.05(stat) +/- 0.07(syst)) x 10(-4). We also measure B(B+ -> eta'l(+)nu) = (0.24 +/- 0.08(stat) +/- 0.03(syst)) x 10(-4). We obtain values for the magnitude of the CKM matrix element |V-ub| using three different QCD calculations.
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Martin Camalich, J., Geng, L. S., & Vicente Vacas, M. J. (2010). Lowest-lying baryon masses in covariant SU(3)-flavor chiral perturbation theory. Phys. Rev. D, 82(7), 074504–7pp.
Abstract: We present an analysis of the baryon-octet and -decuplet masses using covariant SU(3)-flavor chiral perturbation theory up to next-to-leading order. Besides the description of the physical masses we address the problem of the lattice QCD extrapolation. Using the PACS-CS Collaboration data we show that a good description of the lattice points can be achieved at next-to-leading order with the covariant loop amplitudes and phenomenologically determined values for the meson-baryon couplings. Moreover, the extrapolation to the physical point up to this order is found to be better than the linear one given at leading-order by the Gell-Mann-Okubo approach. The importance that a reliable combination of lattice QCD and chiral perturbation theory may have for hadron phenomenology is emphasized with the prediction of the pion-baryon and strange-baryon sigma terms.
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Escrihuela, F. J., Tortola, M., Valle, J. W. F., & Miranda, O. G. (2011). Global constraints on muon-neutrino nonstandard interactions. Phys. Rev. D, 83(9), 093002–8pp.
Abstract: The search for new interactions of neutrinos beyond those of the standard model may help to elucidate the mechanism responsible for neutrino masses. Here, we combine existing accelerator neutrino data with restrictions coming from a recent atmospheric neutrino data analysis in order to lift parameter degeneracies and improve limits on new interactions of muon neutrinos with quarks. In particular, we reconsider the results of the E-815 experiment at Fermilab (NuTeV) in view of a new evaluation of its systematic uncertainties. We find that, although constraints for muon neutrinos are better than those applicable to tau or electron neutrinos, they lie at the few X 10(-2) level, not as strong as previously believed. We briefly discuss prospects for further improvement.
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CDF Collaboration(Aaltonen, T. et al), Cabrera, S., & Cuenca Almenar, C. (2010). Measurement of the t(t)over-bar production cross section in p(p)over-bar collisions at root s=1.96 TeV using soft electron b-tagging. Phys. Rev. D, 81(9), 092002–18pp.
Abstract: We present a measurement of the top-quark pair-production cross section in p (p) over bar collisions at root s = 1.96 TeV using a data sample corresponding to 1.7 fb(-1) of integrated luminosity collected with the Collider Detector at Fermilab. We reconstruct t (t) over bar events in the lepton + jets channel, consisting of e nu + jets and μnu + jets final states. The dominant background is the production of W bosons in association with multiple jets. To suppress this background, we identify electrons from the semileptonic decay of heavy-flavor jets ("soft electron tags''). From a sample of 2196 candidate events, we obtain 120 tagged events with a background expectation of 51 +/- 3 events, corresponding to a cross section of sigma(t (t) over bar) = 7.8 +/- 2.4(stat) +/- 1.6(syst) +/- 0.5(lumi) pb. We assume a top-quark mass of 175 GeV/c(2). This is the first measurement of the t (t) over bar cross section with soft electron tags in run II of the Tevatron.
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