Gonzalez-Alonso, M., Pich, A., & Prades, J. (2010). Violation of quark-hadron duality and spectral chiral moments in QCD. Phys. Rev. D, 81(7), 074007–10pp.
Abstract: We analyze the spectral moments of the V – A two-point correlation function. Using all known short-distance constraints and the most recent experimental data from tau decays, we determine the lowest spectral moments, trying to assess the uncertainties associated with the so-called violations of quark-hadron duality. We have generated a large number of acceptable spectral functions, satisfying all conditions, and have used them to extract the wanted hadronic parameters through a careful statistical analysis. We obtain accurate values for the chi PT couplings L-10 and C-87, and a realistic determination of the dimension six and eight contributions in the operator product expansion, O-6 = (-5.4(-1.6)(+3.6)) . 10(-3) GeV6 and O-8 = d(-8.9-(12.6)(7.4+)) 10(-3) GeV8, showing that the duality-violation effects have been underestimated in previous literature.
|
Fernandez-Martinez, E., Li, T., Pascoli, S., & Mena, O. (2010). Improvement of the low energy neutrino factory. Phys. Rev. D, 81(7), 073010–13pp.
Abstract: The low energy neutrino factory has been proposed as a very sensitive setup for future searches for CP violation and matter effects. Here we study how its performance is affected when the experimental specifications of the setup are varied. Most notably, we have considered the addition of the “platinum'' nu(mu) -> nu(e) channel. We find that, while theoretically the extra channel provides very useful complementary information and helps to lift degeneracies, its practical usefulness is lost when considering realistic background levels. Conversely, an increase in statistics in the ”golden'' nu(mu) -> nu(e) channel and, to some extent, an improvement in the energy resolution, lead to an important increase in the performance of the facility, given the rich energy dependence of the "golden'' channel at these energies. We show that a low energy neutrino factory with a baseline of 1300 km, muon energy of 4.5 GeV, and either a 20 kton totally active scintillating detector or 100 kton liquid argon detector, can have outstanding sensitivity to the neutrino oscillation parameters theta(13), delta, and the mass hierarchy. For our estimated exposure of 2: 8 x 10(23) kton x decays per muon polarity, the low energy neutrino factory has sensitivity to theta(13) and delta for sin(2)(2 theta(13)) > 10(-4) and to the mass hierarchy for sin(2)(2 theta(13)) > 10(-3)
|
Roszkowski, L., Ruiz de Austri, R., & Trotta, R. (2010). Efficient reconstruction of constrained MSSM parameters from LHC data: A case study. Phys. Rev. D, 82(5), 055003–12pp.
Abstract: We present an efficient method of reconstructing the parameters of the constrained MSSM from assumed future LHC data, applied both on their own right and in combination with the cosmological determination of the relic dark matter abundance. Focusing on the ATLAS SU3 benchmark point, we demonstrate that our simple Gaussian approximation can recover the values of its parameters remarkably well. We examine two popular noninformative priors and obtain very similar results, although when we use an informative, naturalness-motivated prior, we find some sizeable differences. We show that a further strong improvement in reconstructing the SU3 parameters can by achieved by applying additional information about the relic abundance at the level of WMAP accuracy, although the expected data from Planck will have only a very limited additional impact. Further external data may be required to break some remaining degeneracies. We argue that the method presented here is applicable to a wide class of low-energy effective supersymmetric models, as it does not require one to deal with purely experimental issues, e.g., detector performance, and has the additional advantages of computational efficiency. Furthermore, our approach allows one to distinguish the effect of the model's internal structure and of the external data on the final parameters constraints.
|
BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Exclusive production of Ds+Ds-,D-s*D-+(s)-, and D-s*D-+(s)*(-) via e(+)e(-) annihilation with initial-state radiation. Phys. Rev. D, 82(5), 052004–10pp.
Abstract: We perform a study of exclusive production of Ds+Ds-,D-s*(+),D-s(-), and D-s*D-+(s)*- final states in initial-state radiation events from e(+)e(-) annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium 1(--) states. The data sample corresponds to an integrated luminosity of 525 fb(-1) and was recorded by the BABAR experiment at the PEP-II storage ring. Ds+Ds-,D-s*(+),D-s(-) and ,D-s*(+),D-s*(-) mass spectra show evidence of the known psi resonances. Limits are extracted for the branching ratios of the decays X(4260) -> D-s(()*()+) D-s(()*()-)
|
BABAR Collaboration(Aubert, B. et al), Azzolini, V., Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Observation of the decay (B)over-bar(0) -> Lambda(+)(c)(p)over-bar pi(0). Phys. Rev. D, 82(3), 031102–8pp.
Abstract: In a sample of 467 x 10(6) B (B) over bar pairs collected with the BABAR detector at the PEP- II collider at SLAC we have observed the decay (B) over bar (0) -> Lambda(+)(c)(p) over bar pi(0) and measured the branching fraction to be (1.94 +/- 0.17 +/- 0.14 +/- 0.50 x 10(-4), where the uncertainties are statistical, systematic, and the uncertainty on the Lambda(+)(c) -> pK(-)pi(+) branching fraction, respectively. We determine an upper limit of 1.5 x 10(-6) at 90% C.L. for the product branching fraction B((B) over bar (0) -> Sigma(+)(c) (2455)(p) over bar) x B(Lambda(+)(c) -> pK(-) pi(+)). Furthermore, we observe an enhancement at the threshold of the invariant mass of the baryon- antibaryon pair.
|
BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Evidence for the decay X(3872) -> J/psi omega. Phys. Rev. D, 82(1), 011101–8pp.
Abstract: We present a study of the decays B-0,B-+ -> J/psi pi(+)pi(-)pi K-0(0,+), using 467 x 106 B (B) over bar pairs recorded with the BABAR detector. We present evidence for the decay mode X(3872) -> J/psi omega, with product branching fractions B(B+ -> X(3872K(+)) x B(X(3872) -> J/psi omega) = [0.6 +/- 0.2(stat) +/- 0.1(syst)] x 10(-5), and B(B-0 -> X(3872)K-0) x B(X(3872) -> J/psi omega) = [0.6 +/- 0.3(stat) +/- 0.1(syst)] x 10(-5). A detailed study of the pi(+) pi(-) pi(0) mass distribution from X(3872) decay favors a negative-parity assignment.
|
BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Study of B -> X gamma decays and determination of vertical bar V-td/V-ts vertical bar. Phys. Rev. D, 82(5), 051101–8pp.
Abstract: Using a sample of 471 x 10(6) B (B) over bar events collected with the BABAR detector, we study the sum of seven exclusive final states B -> X-s(d)gamma, where X-s(d) is a strange (nonstrange) hadronic system with a mass of up to 2.0 GeV/c(2). After correcting for unobserved decay modes, we obtain a branching fraction for b -> d gamma of (9.2 +/- 2.0(stat) +/- 2.3(syst) x 10(-6) in this mass range, and a branching fraction for b -> s gamma of (23.0 +/- 0.8(stat) +/- 3.0(syst) x 3.0(syst) x 10(-5) in the same mass range. We find B(b -> d gamma)/B(b -> s gamma) = 0.040 +/- 0.009(stat) +/- 0.010(syst), from which we determine vertical bar Vtd/Vts vertical bar = 0.199 +/- 0.022(stat) +/- 0.024(syst) +/- 0.002(th).
|
BABAR Collaboration(del Amo Sanchez, P. et al), Azzolini, V., Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). B-meson decays to eta ' rho, eta ' f(0), and eta ' K*. Phys. Rev. D, 82(1), 011502–8pp.
Abstract: We present measurements of B-meson decays to the final states eta'rho, eta'f(0), and eta'K*, where K* stands for a vector, scalar, or tensor strange meson. We observe a significant signal or evidence for eta'rho(+) and all the eta'K* channels. We also measure, where applicable, the charge asymmetries, finding results consistent with no direct CP violation in all cases. The measurements are performed on a data sample consisting of 467 X 10(6) B (B) over bar pairs, collected with the BABAR detector at the PEP-II e(+)e(-) collider at the SLAC National Accelerator Laboratory. Our results favor the theoretical predictions from perturbative QCD and QCD factorization and we observe an enhancement of the tensor K-2*(1430) with respect to the vector K*(892) component.
|
BABAR Collaboration(Lees, J. P. et al), Azzolini, V., Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Limits on tau lepton-flavor violating decays into three charged leptons. Phys. Rev. D, 81(11), 111101–8pp.
Abstract: A search for the neutrinoless, lepton-flavor violating decay of the tau lepton into three charged leptons has been performed using an integrated luminosity of 468 fb(-1) collected with the BABAR detector at the PEP-II collider. In all six decay modes considered, the numbers of events found in data are compatible with the background expectations. Upper limits on the branching fractions are set in the range (1.8-3.3) x 10(-8) at 90% confidence level.
|
BABAR Collaboration(Aubert, B. et al), Azzolini, V., Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Search for B+ -> l(+)nu(l) recoiling against B- -> D(0)l(-)(nu)over-barX. Phys. Rev. D, 81(5), 051101–9pp.
Abstract: We present a search for the decay B+ -> l(+)nu(l) (l = tau, mu, or e) in (458.9 +/- 5.1) x 10(6) B (B) over bar pairs recorded with the BABAR detector at the PEP-II B-factory. We search for these B decays in a sample of B+B- events where one B- meson is reconstructed as B- -> D(0)l(-)(nu) over barX. Using the method of Feldman and Cousins, we obtain B(B+ -> tau(+)nu(tau)) = (1.7 +/- 0.8 +/- 0.2) x 10(-4), which excludes zero at 2.3 sigma. We interpret the central value in the context of the standard model and find the B meson decay constant to be f(B)(2) = (62 +/- 31) x 10(3) MeV2. We find no evidence for B+ -> e(+)nu(e) and B+ -> mu(+)nu(mu) and set upper limits at the 90% C. L. B(B+ -> e(+)nu(e)) < 0.8 x 10(-5) and B(B+ -> mu(+)nu(mu)) < 1.1 x 10(-5).
|
