Abstract: We report on a search for direct scalar bottom quark (sbottom) pair production in p (p) over bar collisions at root s = 1.96 TeV, in events with large missing transverse energy and two jets of hadrons in the final state, where at least one of the jets is required to be identified as originating from a b quark. The study uses a collider detector at Fermilab Run II data sample corresponding to 2.65 fb(-1) of integrated luminosity. The data are in agreement with the standard model. In an R-parity conserving minimal supersymmetric scenario, and assuming that the sbottom decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits on the sbottom pair production cross section of 0.1 pb are obtained. For neutralino masses below 70 GeV/c(2), sbottom masses up to 230 GeV/c(2) are excluded at 95% confidence level.

Abstract: We propose an A(4) flavor-symmetric SU(3) circle times SU(2) circle times U(1) seesaw model where lepton number is broken spontaneously. A consistent two-zero texture pattern of neutrino masses and mixing emerges from the interplay of type-I and type-II seesaw contributions, with important phenomenological predictions. We show that, if the Majoron becomes massive, such seesaw scenario provides a viable candidate for decaying dark matter, consistent with cosmic microwave background lifetime constraints that follow from current WMAP observations. We also calculate the subleading one-loop-induced decay into photons which leads to a monoenergetic emission line that may be observed in future x-ray missions such as Xenia.

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.

Abstract: We use a theoretical model of the gamma d --> K+K- np reaction adapted to the experiment done at LEPS where a peak was observed and associated with the Theta(+)(1540) pentaquark. The study shows that the method used in the experiment to assign momenta to the undetected proton and neutron, together with the chosen cuts, necessarily creates an artificial broad peak in the assumed K(+)n invariant mass in the region of the claimed Theta(+)(1540), such that the remaining strength seen for the experimental peak is compatible with a fluctuation of 2 sigma significance.

Abstract: We study the anomalous electromagnetic pion form factor F-pi 0 gamma*gamma* with a set of holographic models. By comparing with the measured value of the linear slope, some of these models can be ruled out. From the remaining models, we obtain predictions for the low-energy quadratic slope parameters of F-pi 0 gamma*gamma* , currently out of experimental reach but testable in the near future. We find it particularly useful to encode this low-energy information in a form factor able to satisfy also QCD short-distance constraints. We choose the form factor introduced by D'Ambrosio, Isidori, and Portoles in kaon decays, which has the right short distance for a particular value of the quadratic slope, which is later shown to be compatible with our holographic predictions. We then turn to a determination of the (dominant) pion exchange diagram in the hadronic light by light scattering contribution to the muon anomalous magnetic moment. We quantify the theoretical uncertainty in (g – 2)(mu) coming from the different input we use: QCD short distances, experimental input, and low-energy holographic predictions. We also test the pion-pole approximation. Our final result is a(mu)(pi 0) = 6: 54(25) x 10(-10), where the error is driven by the linear slope of F-pi 0 gamma*gamma* , soon to be measured with precision at KLOE-2. Our numerical analysis also indicates that large values of the magnetic susceptibility chi 0 are disfavored, therefore pointing at a mild effect from the pion off-shellness. However, in the absence of stronger bounds on chi 0, an additional (10-15)% systematic uncertainty on the previous value for a(mu)(pi 0) cannot be excluded.