Abstract: Using the Resonance Chiral Theory Lagrangian, we perform a calculation of the vector form factor of the pion at the next-to-leading order (NLO) in the 1/N-C expansion. Imposing the correct QCD short-distance constraints, one fixes the amplitude in terms of the pion decay constant F and resonance masses. Its low momentum expansion determines then the corresponding O(p(4)) and O(p(6)) low-energy chiral couplings at NLO, keeping control of their renormalization scale dependence. At mu(0) = 0.77 GeV, we obtain L-9(mu(0)) = (7.9 +/- 0.4).10(-3) and C-88(mu(0)) – C-90(mu(0)) = (-4.6 +/- 0.4).10(-5).

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.

Abstract: We study neutrino masses in the framework of the supersymmetric inverse seesaw model. Different from the non-supersymmetric version a minimal realization with just one pair of singlets is sufficient to explain all neutrino data. We compute the neutrino mass matrix up to 1-loop order and show how neutrino data can be described in terms of the model parameters. We then calculate rates for lepton flavour violating (LFV) processes, such as μ-> e gamma and chargino decays to singlet scalar neutrinos. The latter decays are potentially observable at the LHC and show a characteristic decay pattern dictated by the same parameters which generate the observed large neutrino angles.

Abstract: We illustrate how recently improved low-redshift cosmological measurements can tighten constraints on neutrino properties. In particular we examine the impact of the assumed cosmological model on the constraints. We first consider the new HST H-0 = 74.2 +/- 3.6 measurement by Riess et al. (2009) and the sigma(8)(Omega(m)/0.25)(0.41) = 0.832 +/- 0.033 constraint from Rozo et al. (2009) derived from the SDSS maxBCG Cluster Catalog. In a ACDM model and when combined with WMAP5 constraints, these low-redshift measurements constrain Sigma m(v) < 0.4 eV at the 95% confidence level. This bound does not relax when allowing for the running of the spectral index or for primordial tensor perturbations. When adding also Supernovae and BAO constraints, we obtain a 95% upper limit of Sigma m(v) < 0.3eV. We test the sensitivity of the neutrino mass constraint to the assumed expansion history by both allowing a dark energy equation of state parameter w not equal -1 and by studying a model with coupling between dark energy and dark matter, which allows for variation in w, Omega(k), and dark coupling strength xi. When combining CMB, H-0 and the SDSS LRG halo power spectrum from Reid et al. 2009, we find that in this very general model, Sigma m(v) < 0.51 eV with 95% confidence. If we allow the number of relativistic species N-rel to vary in a ACDM model with Sigma m(v) = 0, we find N-rel = 3.76(-0.68)(+0.63)(+1.38 -1.21) for the 68% and 95% confidence intervals. We also report prior-independent constraints, which are in excellent agreement with the Bayesian constraints.

Abstract: The Nd-150(3He,t) reaction at 140 MeV/u and Sm-150(t,He-3) reaction at 115 MeV/u were measured, populating excited states in Pm-150. The transitions studied populate intermediate states of importance for the (neutrinoless) beta beta decay of Nd-150 to Sm-150. Monopole and dipole contributions to the measured excitation-energy spectra were extracted by using multipole decomposition analyses. The experimental results were compared with theoretical calculations obtained within the framework of the quasiparticle random-phase approximation, which is one of the main methods employed for estimating the half-life of the neutrinoless beta beta decay (0 nu beta beta) of Nd-150. The present results thus provide useful information on the neutrino responses for evaluating the 0 nu beta beta and 2 nu beta beta matrix elements. The 2 nu beta beta matrix element calculated from the Gamow-Teller transitions through the lowest 1(+) state in the intermediate nucleus is maximally about half that deduced from the half-life measured in 2 nu beta beta direct counting experiments, and at least several transitions through 1+ intermediate states in Pm-150 are required to explain the 2 nu beta beta half-life. Because Gamow-Teller transitions in the Sm-150(t,3He) experiment are strongly Pauli blocked, the extraction of Gamow-Teller strengths was complicated by the excitation of the 2 (h) over bar omega, Lambda L = 0, Delta S = 1 isovector spin-flip giant monopole resonance (IVSGMR). However, the near absence of Gamow-Teller transition strength made it possible to cleanly identify this resonance, and the strength observed is consistent with the full exhaustion of the non-energy-weighted sum rule for the IVSGMR.