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Esteves, J. N., Romao, J. C., Hirsch, M., Staub, F., & Porod, W. (2011). Supersymmetric type-III seesaw mechanism: Lepton flavor violating decays and dark matter. Phys. Rev. D, 83(1), 013003–21pp.
Abstract: We study a supersymmetric version of the seesaw mechanism type III. The model consists of the minimal supersymmetric extension of the standard model particle content plus three copies of 24 superfields. The fermionic part of the SU(2) triplet contained in the 24 is responsible for the type-III seesaw, which is used to explain the observed neutrino masses and mixings. Complete copies of 24 are introduced to maintain gauge coupling unification. These additional states change the beta functions of the gauge couplings above the seesaw scale. Using minimal Supergravity boundary conditions, we calculate the resulting supersymmetric mass spectra at the electroweak scale using full 2-loop renormalization group equations. We show that the resulting spectrum can be quite different compared to the usual minimal Supergravity spectrum. We discuss how this might be used to obtain information on the seesaw scale from mass measurements. Constraints on the model space due to limits on lepton flavour violating decays are discussed. The main constraints come from the bounds on μ-> e gamma but there are also regions where the decay tau -> μgamma gives stronger constraints. We also calculate the regions allowed by the dark matter constraint. For the sake of completeness, we compare our results with those for the supersymmetric seesaw type II and, to some extent, with type I.
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Aguilar, A. C., & Papavassiliou, J. (2011). Chiral symmetry breaking with lattice propagators. Phys. Rev. D, 83(1), 014013–17pp.
Abstract: We study chiral symmetry breaking using the standard gap equation, supplemented with the infrared-finite gluon propagator and ghost dressing function obtained from large-volume lattice simulations. One of the most important ingredients of this analysis is the non-Abelian quark-gluon vertex, which controls the way the ghost sector enters into the gap equation. Specifically, this vertex introduces a numerically crucial dependence on the ghost dressing function and the quark-ghost scattering amplitude. This latter quantity satisfies its own, previously unexplored, dynamical equation, which may be decomposed into individual integral equations for its various form factors. In particular, the scalar form factor is obtained from an approximate version of the “one-loop dressed” integral equation, and its numerical impact turns out to be rather considerable. The detailed numerical analysis of the resulting gap equation reveals that the constituent quark mass obtained is about 300 MeV, while fermions in the adjoint representation acquire a mass in the range of (750-962) MeV.
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Garcia-Recio, C., Geng, L. S., Nieves, J., & Salcedo, L. L. (2011). Low-lying even-parity meson resonances and spin-flavor symmetry. Phys. Rev. D, 83(1), 016007–30pp.
Abstract: Based on a spin-flavor extension of chiral symmetry, a novel s-wave meson-meson interaction involving members of the rho nonet and of the pi octet is introduced, and its predictions are analyzed. The starting point is the SU(6) version of the SU(3)-flavor Weinberg-Tomozawa Lagrangian. SU(6) symmetry-breaking terms are then included to account for the physical meson masses and decay constants in a way that preserves (broken) chiral symmetry. Next, the T-matrix amplitudes are obtained by solving the Bethe-Salpeter equation in a coupled-channel scheme, and the poles are identified with their possible Particle Data Group counterparts. It is shown that most of the low-lying even-parity Particle Data Group meson resonances, especially in the J(P) = 0(+) and 1(+) sectors, can be classified according to multiplets of SU(6). The f(0)(1500), f(1)(1420), and some 0(+)(2(++)) resonances cannot be accommodated within this scheme, and thus they would be clear candidates to be glueballs or hybrids. Finally, we predict the existence of five exotic resonances (I >= 3/2 and/or vertical bar Y vertical bar = 2) with masses in the range of 1.4-1.6 GeV, which would complete the 27(1), 10(3), and 10(3)* multiplets of SU(3) circle times SU(2).
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Roszkowski, L., Ruiz de Austri, R., Trotta, R., Tsai, Y. L. S., & Varley, T. A. (2011). Global fits of the nonuniversal Higgs model. Phys. Rev. D, 83(1), 015014–19pp.
Abstract: We carry out global fits to the nonuniversal Higgs Model (NUHM), applying all relevant present-day constraints. We present global probability maps for the NUHM parameters and observables (including collider signatures, direct, and indirect detection quantities), both in terms of posterior probabilities and in terms of profile likelihood maps. We identify regions of the parameter space where the neutralino dark matter in the model is either binolike, or else higgsinolike with mass close to 1 TeV and a spin-independent scattering cross section similar to 10(-9)-10(-8) pb. We trace the occurrence of the higgsinolike region to be a consequence of a mild focusing effect in the running of one of the Higgs masses, the existence of which in the NUHM we identify in our analysis. Although the usual binolike neutralino is more prominent, higgsinolike dark matter cannot be excluded, however its significance strongly depends on the prior and statistics used to assess it. We note that, despite experimental constraints often favoring different regions of parameter space to the constrained minimal supersymmetric standard model, most observational consequences appear fairly similar, which will make it challenging to distinguish the two models experimentally.
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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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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2011). Studies of tau(-) -> eta K- nu(tau) and tau(-) -> eta pi(-) nu(tau) at BABAR and a search for a second-class current. Phys. Rev. D, 83(3), 032002–10pp.
Abstract: We report on analyses of tau lepton decays tau(-) -> eta K- nu(tau) and tau(-) -> eta pi(-) nu(tau), with eta -> pi(+) pi(-) pi(0), using 470 fb(-1) of data from the BABAR experiment at PEP-II, collected at center-of-mass energies at and near the Y(4S) resonance. We measure the branching fraction for the tau(-) -> eta K- nu(tau) decay mode, B(tau(-) -> eta K- nu(tau)) = (1.42 +/- 0.11(stat) +/- 0.07(syst)) x 10(-4), and report a 95% confidence level upper limit for the second-class current process tau(-) -> eta pi(-) nu(tau), B(tau(-) -> eta pi(-) nu(tau)) < 9.9 x 10(-5).
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Bertolini, S., Di Luzio, L., & Malinsky, M. (2011). Minimal flipped SO(10) x U(1) supersymmetric Higgs model. Phys. Rev. D, 83(3), 035002–28pp.
Abstract: We investigate the conditions on the Higgs sector that allow supersymmetric SO(10) grand unified theories to break spontaneously to the standard electroweak model at the renormalizable level. If one considers Higgs representations of dimension up to the adjoint, a supersymmetric standard model vacuum requires, in most cases, the presence of nonrenormalizable operators. The active role of Planck-induced nonrenormalizable operators in the breaking of the gauge symmetry introduces a hierarchy in the mass spectrum at the grand unified theory scale that may be an issue for gauge unification and proton decay. We show that the minimal Higgs scenario that allows for a renormalizable breaking to the standard model is obtained by considering flipped SO(10) circle times U(1) with one adjoint (45(H)) and two pairs of 16(H) circle plus (16) over bar (H) Higgs representations. We consider a nonanomalous matter content and discuss the embedding of the model in an E-6 grand unified scenario just above the flipped SO(10) scale.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2011). Measurement of the B -> D(bar)(*) D(*) K branching fractions. Phys. Rev. D, 83(3), 032004–16pp.
Abstract: We present a measurement of the branching fractions of the 22 decay channels of the B-0 and B+ mesons to (D) over bar (()*()) D-(*()) K, where the D-(*()) and (D) over bar (()*()) mesons are fully reconstructed. Summing the 10 neutral modes and the 12 charged modes, the branching fractions are found to be B(B-0 -> (D) over bar (()*()) D-(*()) K) = (3.68 +/- 0.10 +/- 0.24)% and B(B+ -> (D) over bar (()*()) D-(*()) K) = (4.05 +/- 0.11 +/- 0.28)%, where the first uncertainties are statistical and the second systematic. The results are based on 429 fb(-1) of data containing 471 X 10(6)B (B) over bar pairs collected at the Y(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory.
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Das, S. P., & Drees, M. (2011). CP-violating supersymmetric Higgs boson at the Tevatron and LHC. Phys. Rev. D, 83(3), 035003–17pp.
Abstract: We analyze the prospect for observing the intermediate neutral Higgs boson (h(2))in its decay to two lighter Higgs bosons (h(1)) at the presently operating hadron colliders in the framework of the CP-violating minimal supersymmetric standard model using the PYTHIA event generator. We consider the lepton + 4-jets + E-T channel from associate Wh(2) production, with Wh(2) -> Wh(1)h(1) -> l -> l nu lb (b) over barb (b) over bar. We require two, three or four tagged b jets. We explicitly consider all relevant standard model backgrounds, treating c jets separately from light flavor and gluon jets and allowing for mistagging. We find that it is very hard to observe this signature at the Tevatron, even with 20 fb(-1) of data, in the LEP-allowed region of parameter space due to the small signal efficiency, even though the background is manageable. At the LHC, a priori huge standard model backgrounds can be suppressed by applying judiciously chosen kinematical selections. After all cuts, we are left with a signal cross section of around 0.5 fb, and a signal to background ratio between 1.2 and 2.9. According to our analysis this Higgs signal should be viable at the LHC in the vicinity of present LEP exclusion once 20 to 50 fb(-1) of data have been accumulated at root s = 14 TeV.
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