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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Cata, O., & Kamenik, J. F. (2011). Electroweak precision observables at one loop in Higgsless models. Phys. Rev. D, 83(5), 053010–9pp.
Abstract: We study the viability of generic Higgsless models at low energies when compliance with electroweak precision observables and unitarity constraints up to the TeV scale are imposed. Our analysis shows that consistency with S and T can be achieved at the one-loop level even with a single light vector state, m(V) less than or similar to 500 GeV. However, this scenario turns out to be strongly disfavored when direct resonance searches at the Tevatron are also taken into account. We show that a fully consistent picture can be obtained if an axial state is introduced. Interestingly, mV is still predicted to be light (below 1 TeV) while typical values of m(A) span over the window 1.2m(V) <= m(A) <= 1.4m(V). Our results for the vector channel are rather robust and well within the reach of present-day colliders, while the axial channel is more loosely constrained.
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Bernardoni, F., Garron, N., Hernandez, P., Necco, S., & Pena, C. (2011). Probing the chiral regime of N-f=2 QCD with mixed actions. Phys. Rev. D, 83(5), 054503–17pp.
Abstract: We report on our first experiences with a mixed action setup with overlap valence quarks and nonperturbatively O(a) improved Wilson sea quarks. For the latter we employ CLS N-f = 2 configurations with light sea-quark masses at small lattice spacings. Exact chiral symmetry allows to consider very light valence quarks and explore the matching to (partially-quenched) Chiral Perturbation Theory (ChPT) in a mixed epsilon/p-regime. We compute the topological susceptibility and the low-lying spectrum of the massless Neuberger-Dirac operator for three values of the sea-quark mass, and compare the sea-quark mass dependence to NLO ChPT in the mixed regime. This provides two different determinations of the chiral condensate, as well as information about some NLOlow-energy couplings. Our results allow to test the consistency of the mixed-regime approach to ChPT, as well as of the mixed action framework.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Escobar, C., et al. (2011). Measurement of the inclusive isolated prompt photon cross section in pp collisions at sqrt(s)=7 TeV with the ATLAS detector. Phys. Rev. D, 83(5), 052005–31pp.
Abstract: A measurement of the cross section for the inclusive production of isolated prompt photons in pp collisions at a center-of-mass energy root s = 7 TeV is presented. The measurement covers the pseudorapidity ranges vertical bar eta(gamma)vertical bar < 1: 37 and 1: 52 <= vertical bar eta(gamma)vertical bar < 1: 81 in the transverse energy range 15 <= E-T(gamma) < 100 GeV. The results are based on an integrated luminosity of 880 nb(-1), collected with the ATLAS detector at the Large Hadron Collider. Photon candidates are identified by combining information from the calorimeters and from the inner tracker. Residual background in the selected sample is estimated from data based on the observed distribution of the transverse isolation energy in a narrow cone around the photon candidate. The results are compared to predictions from next-to-leading-order perturbative QCD calculations.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Measurements of branching fractions, polarizations, and direct CP-violation asymmetries in B+ -> rho K-0*(+) and B+ -> f(0)(980)K*(+) decays. Phys. Rev. D, 83(5), 051101–8pp.
Abstract: We present measurements of the branching fractions, longitudinal polarization, and direct CP-violation asymmetries for the decays B+ -> rho K-0*(+) and B+ -> f(0)(980)K*(+) with a sample of (467 +/- 5) x 10(6)B (B) over bar pairs collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at the SLAC National Accelerator Laboratory. We observe B+ -> rho K-0*(+) with a significance of 5: 3 sigma and measure the branching fraction B(B+ -> rho K-0*(+)) = (4.6 +/- 1.0 +/- 0.4) x 10(-6), the longitudinal polarization f(L) = 0.78 +/- 0.12 +/- 0.03, and the CP-violation asymmetry A(CP) = 0.31 +/- 0.13 +/- 0.03. We observe B+ -> f(0)(980)K*(+) and measure the branching fraction B(B+ -> f(0)(980)K*(+)) x B(f(0)(980) -> pi(+)pi(-)) = (4.2 +/- 0.6 +/- 0.3) x 10(-6) and the CP-violation asymmetry A(CP) = 0.15 +/- 0.12 +/- 0.03. The first uncertainty quoted is statistical and the second is systematic.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Escobar, C., et al. (2011). Study of jet shapes in inclusive jet production in pp collisions at sqrt(s)=7 TeV using the ATLAS detector. Phys. Rev. D, 83(5), 052003–29pp.
Abstract: Jet shapes have been measured in inclusive jet production in proton-proton collisions at root s = 7 TeV using 3 pb(-1) of data recorded by the ATLAS experiment at the LHC. Jets are reconstructed using the anti-k(t) algorithm with transverse momentum 30 GeV < p(T) < 600 GeV and rapidity in the region vertical bar y vertical bar < 2.8. The data are corrected for detector effects and compared to several leading-order QCD matrix elements plus parton shower Monte Carlo predictions, including different sets of parameters tuned to model fragmentation processes and underlying event contributions in the final state. The measured jets become narrower with increasing jet transverse momentum and the jet shapes present a moderate jet rapidity dependence. Within QCD, the data test a variety of perturbative and nonperturbative effects. In particular, the data show sensitivity to the details of the parton shower, fragmentation, and underlying event models in the Monte Carlo generators. For an appropriate choice of the parameters used in these models, the data are well described.
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Li, X. Q., Su, F., & Yang, Y. D. (2011). Determination of the strong coupling gB*B pi from semileptonic B -> pi l nu decay. Phys. Rev. D, 83(5), 054019–8pp.
Abstract: According to heavy-meson chiral perturbation theory, the vector form factor f+(q(2)) of exclusive semileptonic decay B -> pi l nu is closely related, at least in the soft-pion region ( i.e., q(2) similar to (m(B) – m(pi))(2)), to the strong coupling g(B*B pi) or the normalized coupling (g)over-cap. Combining the precisely measured q2 spectrum of B -> pi l nu decay by the BABAR and Belle collaborations with several parametrizations of the form factor f +(q(2)), we can extract these couplings from the residue of the form factor at the B* pole, which relies on an extrapolation of the form factor from the semileptonic region to the unphysical point q(2) = m(B*)(2). Comparing the extracted values with the other experimental and theoretical estimates, we can test these various form-factor parametrizations, which differ from each other by the amount of physical information embedded in. It is found that the extracted values based on the Becirevic-Kaidalov, Ball-Zwicky and Bourrely-Caprini-Lellouch parametrizations are consistent with each other and roughly in agreement with the other theoretical and lattice estimates, while the Boyd-Grinstein-Lebed ansatz, featured by a spurious, unwanted pole at the threshold of the cut, gives a neatly larger value.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Dalitz plot analysis of D-s(+) -> K+ K- pi(+). Phys. Rev. D, 83(5), 052001–20pp.
Abstract: We perform a Dalitz plot analysis of about 100 000 D-s(+) decays to K+ K- pi(+) and measure the complex amplitudes of the intermediate resonances which contribute to this decay mode. We also measure the relative branching fractions of D-s(+) -> K+ K+ pi(-) and D-s(+) -> K+ K+ K-. For this analysis we use a 384 fb(-1) data sample, recorded by the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider running at center-of-mass energies near 10.58 GeV.
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SciBooNE Collaboration(Nakajima, Y. et al), Catala-Perez, J., Gomez-Cadenas, J. J., & Sorel, M. (2011). Measurement of inclusive charged current interactions on carbon in a few-GeV neutrino beam. Phys. Rev. D, 83(1), 012005–21pp.
Abstract: We report a measurement of inclusive charged current interactions of muon neutrinos on carbon with an average energy of 0.8 GeV using the Fermilab Booster Neutrino Beam. We compare our measurement with two neutrino interaction simulations: NEUT and NUANCE. The charged current interaction rates (product of flux and cross section) are extracted by fitting the muon kinematics, with a precision of 6%-15% for the energy dependent and 3% for the energy integrated analyses. We also extract charged current inclusive interaction cross sections from the observed rates, with a precision of 10%-30% for the energy dependent and 8% for the energy integrated analyses. This is the first measurement of the charged current inclusive cross section on carbon around 1 GeV. These results can be used to convert previous SciBooNE cross-section ratio measurements to absolute cross-section values.
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Calabrese, E., de Putter, R., Huterer, D., Linder, E. V., & Melchiorri, A. (2011). Future CMB constraints on early, cold, or stressed dark energy. Phys. Rev. D, 83(2), 023011–11pp.
Abstract: We investigate future constraints on early dark energy (EDE) achievable by the Planck and CMBPol experiments, including cosmic microwave background (CMB) lensing. For the dark energy, we include the possibility of clustering through a sound speed c(s)(2) < 1 (cold dark energy) and anisotropic stresses parametrized with a viscosity parameter c(vis)(2). We discuss the degeneracies between cosmological parameters and EDE parameters. In particular we show that the presence of anisotropic stresses in EDE models can substantially undermine the determination of the EDE sound speed parameter c(s)(2). The constraints on EDE primordial energy density are however unaffected. We also calculate the future CMB constraints on neutrino masses and find that they are weakened by a factor of 2 when allowing for the presence of EDE, and highly biased if it is incorrectly ignored.
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