Impact of the recent results by the CMS and ATLAS Collaborations at the CERN Large Hadron Collider on an effective Minimal Supersymmetric extension of the Standard Model

We discuss the impact for light neutralinos in an effective Minimal Supersymmetric extension of the Standard Model of the recent results presented by the CMS and ATLAS Collaborations at the CERN Large Hadron Collider for a search of supersymmetry in proton-proton collisions at a center-of-mass energy of 7 TeV with an integrated luminosity of 35 inverse pb. We find that, in the specific case of light neutralinos, efficiencies for the specific signature searched by ATLAS (jets+missing transverse energy and an isolated lepton) imply a lower sensitivity compared to CMS (which searches for jets +missing transverse energy). Focusing on the CMS bound, if squark soft masses of the three families are assumed to be degenerate, the combination of the ensuing constraint on squark and gluino masses with the experimental limit on the b to s + gamma decay imply a lower bound on the neutralino mass that can reach the value of 11.9 GeV, depending on the gluino mass. On the other hand, when the universality condition among squark soft parameters is relaxed, the lower bound on the neutralino mass is not constrained by the CMS measurement and then remains at the value 7.5 GeV derived in previous papers.Comment: 6 pages, 6 figures, typeset with ReVTeX4. A version of the paper with full resolution figures can be found at http://www.to.infn.it/~scopel/cms_mssm2.pd

CP violation at one loop in the polarization-independent chargino production in e+e- collisions

Recently Osland and Vereshagin noticed, based on sample calculations of some box diagrams, that in unpolarised e+e- collisions CP-odd effects in the non-diagonal chargino-pair production process are generated at one-loop. Here we perform a full one-loop analysis of these effects and point out that in some cases the neglected vertex and self-energy contributions may play a dominant role. We also show that CP asymmetries in chargino production are sensitive not only to the phase of mu parameter in the chargino sector but also to the phase of stop trilinear coupling A_t.Comment: 14 pages, 5 figure

The effect of supersymmetric CP phases on Chargino-Pair Production via Drell-Yan Process at the LHC

We compute the rates for pp annihilation into chargino-pairs via Drell-Yan process taking into account the effects of supersymmetric soft phases, at proton-proton collider. In particular, the phase of the mu parameter gains direct accessibility via the production of dissimilar charginos. The phases of the trilinear soft masses do not have a significant effect on the cross sections.Comment: 24 pages, 7 figure

Anti-correlated time lags in the Z source GX 5-1: Possible evidence for a truncated accretion disk

We investigate the nature of the inner accretion disk in the neutron star source GX 5-1 by making a detailed study of time lags between X-rays of different energies. Using the cross-correlation analysis, we found anti-correlated hard and soft time lags of the order of a few tens to a few hundred seconds and the corresponding intensity states were mostly the horizontal branch (HB) and upper normal branch (NB). The model independent and dependent spectral analysis showed that during these time lags the structure of accretion disk significantly varied. Both eastern and western approaches were used to unfold the X-ray continuum and systematic changes were observed in soft and hard spectral components. These changes along with a systematic shift in the frequency of quasi-periodic oscillations (QPOs) made it substantially evident that the geometry of the accretion disk is truncated. Simultaneous energy spectral and power density spectral study shows that the production of the horizontal branch oscillations (HBOs) are closely related to the Comptonizing region rather than the disk component in the accretion disk. We found that as the HBO frequency decreases from the hard apex to upper HB, the disk temperature increases along with an increase in the coronal temperature which is in sharp contrast with the changes found in black hole binaries where the decrease in QPO frequency is accompanied by a decrease in the disk temperature and a simultaneous increase in the coronal temperature. We discuss the results in the context of re-condensation of coronal material in the inner region of the disk.Comment: 40 pages, 7 figures, accepted for publication in The Astrophysical Journal Supplement (ApJS

Determining Heavy Mass Parameters in Supersymmetric SO(10) Models

Extrapolations of soft scalar mass parameters in supersymmetric theories can be used to explore elements of the physics scenario near the grand unification scale. We investigate the potential of this method in the lepton sector of SO(10) which incorporates right-handed neutrino superfields. The method is exemplified in two models by exploring limits on the precision that can be expected from coherent LHC and e+e- collider analyses in the reconstruction of the fundamental scalar mass parameters at the unification scale and of the D-terms related to the breaking of grand unification symmetries. In addition, the mass of the third-generation right-handed neutrino can be estimated in seesaw scenarios. Even though the models are simplified and not intended to account for all aspects of a final comprehensive SO(10) theory, they provide nevertheless a valid base for identifying essential elements that can be inferred on the fundamental high-scale theory from high-energy experiments.Comment: 26 pp LaTeX; version published in Phys. Rev.

Comment about pion electro-production and the axial form factors

The claim by Haberzettl (Phys.Rev.Lett.85 (2000) 3576) that the axial form factor of the nucleon cannot be accessed through threshold pion electroproduction is unfounded

Determining SUSY Parameters in Chargino Pair-Production in e+e−e^+e^- Collisions

In most supersymmetric theories, charginos $\tilde{\chi}^\pm_{1,2}$, mixtures of charged color-neutral gauginos and higgsinos, belong to the class of the lightest supersymmetric particles. They are easy to observe at $e^+e^-$ colliders. By measuring the total cross sections and the left-right asymmetries with polarized electron beams in $e^+e^-\to\tilde{\chi}_i^-\tilde{\chi}_j^+ [i,j=1,2]$, the chargino masses and the gaugino-higgsino mixing angles can be determined. From these observables the fundamental SUSY parameters can be derived: the SU(2) gaugino mass $M_2$, the modulus $|\mu|$ and $\cos \Phi_\mu$ of the higgsino mass parameter, and $\tan\beta = v_2/v_1$, the ratio of the vacuum expectation values of the two neutral Higgs doublet fields. The solutions are unique; the CP-violating phase $\Phi_\mu$ can be determined uniquely by analyzing effects due to the normal polarization of the charginos.Comment: 20 pages, 4 figures, uses axodraw.st