Beam-beam-induced orbit effects at LHC

For high bunch intensities the long-range beam-beam interactions are strong enough to provoke effects on the orbit. As a consequence the closed orbit changes. The closed orbit of an unperturbed machine with respect to a machine where the beam-beam force becomes more and more important has been studied and the results are presented in this paper.Comment: 5 pages, contribution to the ICFA Mini-Workshop on Beam-Beam Effects in Hadron Colliders, CERN, Geneva, Switzerland, 18-22 Mar 201

Beyond Standard Model Physics at the Large Hadron Collider at CERN

This conference report presents a compilation of some of the latest results on prospects for Extra Dimensions and Heavy Bosons Models with A Toroidal LHC ApparatuS (ATLAS) and the Compact Muon Solenoide (CMS). ATLAS and CMS are two general purpose detectors placed at two equidistant points in the Large Hadron Collider (LHC) at CERN. The results presented here correspond, in most of the cases, to full simulation and full reconstruction of the hadron interactions at sqrt(s) = 14 TeV and to low and/or high luminosity. In general, theoretical and systematic uncertainties are considered in the final results

Radiative two-pion decay of the tau lepton

We consider the bremsstrahlung and model-dependent contributions to the radiative decay $\tau^- \to \pi^-\pi^0\nu_{\tau}\gamma$ in the context of a meson dominance model. We focus on several observables related to this decay, including the branching ratio and the photon and di-pion spectra. Particular attention is paid to the sensitivity of different observables upon the effects of model-dependent contributions and of the magnetic dipole moment of the $\rho^-(770)$ vector meson. Important numerical differences are found with respect to results obtained in the framework of chiral perturbation theory.Comment: 14 pages, 8 figures, submitted for publicatio

Improved Determination of the Hadronic Contribution to the Muon (g-2) and to alpha(M_Z**2) Using new Data from Hadronic Tau Decays

We have reevaluated the hadronic contribution to the anomalous magnetic moment of the muon (g-2) and to the running of the QED fine structure constant alpha(s) at s=M_Z**2. We incorporated new data from hadronic tau decays, recently published by the ALEPH Collaboration. In addition, compared to previous analyses, we use more extensive e+e- annihilation data sets. The integration over the total hadronic cross section is performed using experimental data up to 40 GeV and results from perturbative QCD above 40 GeV. The improvement from tau data concerns mainly the pion form factor, where the uncertainty in the corresponding integral could be reduced by more than a factor of two. We obtain for the lowest order hadronic vacuum polarization graph a_mu(had) = (695.0 +/- 15.0) x 10^{-10} and delta(alpha(M_Z**2))(had) = (280.9 +/- 6.3) x 10^{-4} using e+e- data only. The corresponding results for combined e+e- and tau data are a_mu(had) = (701.1 +/- 9.4) x 10^{-10} and delta(alpha(M_Z**2))(had) = (281.7 +/- 6.2) x 10^{-4}, where the latter is calculated using the contribution from the five lightest quarks.Comment: 23 pages, LaTex, 6 figures, Paper submitted to Zeitschrift fuer Physik

Virtual effects of light gauginos and higgsinos: a precision electroweak analysis of split supersymmetry

We compute corrections to precision electroweak observables in supersymmetry in the limit that scalar superpartners are very massive and decoupled. This leaves charginos and neutralinos and a Standard Model-like Higgs boson as the only states with unknown mass substantially affecting the analysis. We give complete formulas for the chargino and neutralino contributions, derive simple analytic results for the pure gaugino and higgsino cases, and study the general case. We find that in all circumstances, the precision electroweak fit improves when the charginos and neutralinos are near the current direct limits. Larger higgsino and gaugino masses worsen the fit as the theory predictions asymptotically approach those of the Standard Model. Since the Standard Model is considered by most to be an adequate fit to the precision electroweak data, an important corollary to our analysis is that all regions of parameter space allowed by direct collider constraints are also allowed by precision electroweak constraints in split supersymmetry.Comment: 22 pages, 5 figures, v2: typos fixed and note adde

Deciphering solar turbulence from sunspots records

It is generally believed that sunspots are the emergent part of magnetic flux tubes in the solar interior. These tubes are created at the base of the convection zone and rise to the surface due to their magnetic buoyancy. The motion of plasma in the convection zone being highly turbulent, the surface manifestation of sunspots may retain the signature of this turbulence, including its intermittency. From direct observations of sunspots, and indirect observations of the concentration of cosmogenic isotopes $^{14}$C in tree rings or $^{10}$Be in polar ice, power spectral densities in frequency are plotted. Two different frequency scalings emerge, depending on whether the Sun is quiescent or active. %magnetic activity is maximum or minimum. From direct observations we can also calculate scaling exponents. These testify to a strong intermittency, comparable with that observed in the solar wind.Comment: 5 pages, 6 figures, accepted for publication in MNRAS Letter

A Sequencer for the LHC ERA

The Sequencer is a high level software application that helps operators and physicists to commission and control the LHC. It is an important operational tool for the LHC and a core part of the control system that interacts with all LHC sub-systems. This paper describes the architecture and design of the sequencer and illustrates some innovative parts of the implementation, based on modern Java technology