Signals of Warped Extra Dimensions at the LHC

We discuss the signatures of the spin-2 graviton excitations predicted by the Randall-Sundrum model with one warped extra dimension, in dilepton and diphoton production at LHC. By using a specific angular analysis, we assess the ranges in mass and coupling constant where such gravitons can be discriminated against competitor spin-1 and spin-0 objects, that potentially could manifest themselves in these processes with the same mass and rate of events. Depending on the value of the coupling constant to quarks and leptons, the numerical results indicate graviton identification mass ranges up to 1.1-2.4 TeV and 1.6-3.2 TeV for LHC nominal energy of 14 TeV and time-integrated luminosity of 10 and 100~${\rm fb}^{-1}$, respectively.Comment: 8 pages, Talk given at QCD@Work - International Workshop on QCD - Theory and Experiment, 20 - 23 June, 2010, Martina Franca Ital

CP violation in unpolarized e^+ e^- to charginos at one loop level

We study CP violation in e^+ e^- to \tilde\chi_i^+\tilde\chi_j^- in the framework of the MSSM. Though the cross section of this process is CP-even at the tree level even for polarized electron-positron beams, we show that it contains a CP-odd part at the one loop order and there are CP-odd observables that can in principle be measured even using unpolarized electron-positron beams. The relevant diagram calculations are briefly discussed and the results of selected (box) diagram computations are shown.Comment: similar to Phys. Rev. D version, but corrected figs. 4, 5, 6 (factor four

On the phenomenology of a Z' coupling only to third-family fermions

The phenomenology of an additional U(1) neutral gauge boson Z' coupled to the third family of fermions is discussed. One might expect such a particle to contribute to processes where taus, b and t quarks are produced. Precision data from LEP1 put severe constraints on the mixing and heavy-boson mass. We find that the effects of such a particle could not be observed at hadronic colliders, be it at the Tevatron or the LHC, because of the QCD background. At LEP2 and future e^+e^- linear colliders, one could instead hope to observe such effects, in particular for b\bar b final states.Comment: 36 pages, LaTeX, including 12 figure

A simple inert model solves the little hierarchy problem and provides a dark matter candidate

We discuss a minimal extension to the standard model in which two singlet scalar states that only interacts with the Higgs boson is added. Their masses and interaction strengths are fixed by the two requirements of canceling the one-loop quadratic corrections to the Higgs boson mass and providing a viable dark matter candidate. Direct detection of the lightest of these new states in nuclear scattering experiments is possible with a cross section within reach of future experiments.Comment: Finite corrections included. Model modified. Conclusion unchange

On-shell two-loop three-gluon vertex

The two-loop three-gluon vertex is calculated in an arbitrary covariant gauge, in the limit when two of the gluons are on the mass shell. The corresponding two-loop results for the ghost-gluon vertex are also obtained. It is shown that the results are consistent with the Ward-Slavnov-Taylor identities.Comment: 34 pages, LaTeX, including 5 figures, uses eps

Two-loop three-gluon vertex in zero-momentum limit

The two-loop three-gluon vertex is calculated in an arbitrary covariant gauge, in the limit when one of the external momenta vanishes. The differential Ward-Slavnov-Taylor (WST) identity related to this limit is discussed, and the relevant results for the ghost-gluon vertex and two-point functions are obtained. Together with the differential WST identity, they provide another independent way for calculating the three-gluon vertex. The renormalization of the results obtained is also presented.Comment: 22 pages, LaTeX, including 4 figures, uses eps

Three-gluon vertex in arbitrary gauge and dimension

One-loop off-shell contributions to the three-gluon vertex are calculated, in arbitrary covariant gauge and in arbitrary space-time dimension, including quark-loop contributions (with massless quarks). It is shown how one can get the results for all on-shell limits of interest directly from the general off-shell expression. The corresponding general expressions for the one-loop ghost-gluon vertex are also obtained. They allow for a check of consistency with the Ward--Slavnov--Taylor identity.Comment: 41 pages, LaTex, plus 3 figures in separate file. Misprints (signs) in eqs.(4.26), (C.2), (C.4), (C.5) are corrected. To appear in Phys. Rev.

Constraints on mixing angles of Majorana neutrinos

By combining the inputs from the neutrinoless double beta decay and the fits of cosmological models of dark matter with solar and atmospheric neutrino data, we obtain constraints on two of the mixing angles of Majorana neutrinos, which become stronger when coupled with the reactor neutrino data. These constraints are strong enough to rule out Majorana neutrinos if the small angle solution of solar neutrino puzzle is borne out.Comment: Some corrections and clarifications adde

Measurement of SUSY masses via cascade decays for SPS 1a

If R-parity conserving supersymmetry exists below the TeV-scale, new particles will be produced and decay in cascades at the LHC. The lightest supersymmetric particle will escape the detectors, thereby complicating the full reconstruction of the decay chains. In this paper we expand on existing methods for determining the masses of the particles in the cascade from endpoints of kinematical distributions. We perform scans in the mSUGRA parameter space to delimit the region where this method is applicable. From the examination of theoretical distributions for a wide selection of mass scenarios it is found that caution must be exerted when equating the theoretical endpoints with the experimentally obtainable ones. We provide analytic formulae for the masses in terms of the endpoints most readily available. Complications due to the composite nature of the endpoint expressions are discussed in relation to the detailed analysis of two points on the SPS 1a line. Finally we demonstrate how a Linear Collider measurement can improve dramatically on the precision of the masses obtained