118698479
Supersymmetric SO(10)-inspired GUTs with sliding scales
This work has been supported in part by EU Network Grant No. UNILHC PITN-GA-2009-237920. M. H. also acknowledges support from the Spanish MICINN Grants No. FPA2011-22975, No. MULTIDARK CSD2009-00064 and by the Generalitat Valenciana Grant No. Prometeo/2009/091. The work of R. M. F has been supported by Fundacao para a Ciencia e a Tecnologia through the fellowship SFRH/BD/47795/2008. R. M. F. and J. C. R. also acknowledge the financial support from Grants No. CFTP-FCT UNIT 777, No. CERN/FP/123580/2011 and No. PTDC/FIS/102120/2008.
53865432
Hefty MSSM-like light Higgs in extended gauge models
A bstractIt is well known that in the MSSM the lightest neutral Higgs h0 must be, at the tree level, lighter than the Z boson and that the loop corrections shift this stringent upper bound up to about 130 GeV. Extending the MSSM gauge group in a suitable way, the new Higgs sector dynamics can push the tree-level mass of h0 well above the tree-level MSSM limit if it couples to the new gauge sector. This effect is further pronounced at the loop level and h0 masses in the 140GeV ballpark can be reached easily. We exemplify this for a sample setting with a low-scale U(1)R × U(1)B−L gauge symmetry in which neutrino masses can be implemented via the inverse seesaw mechanism.
35525710
Phenomenology of neutrinoless double beta decay
Neutrinoless double beta decay ( 0 ν β β ) violates lepton number by two units, a positive observation therefore necessarily implies physics beyond the standard model. Here, three possible contributions to 0 ν β β decay are briefly reviewed: (a) The mass mechanism and its connection to neutrino oscillations; (b) Left-right symmetric models and the lower limit on the right-handed W boson mass; and (c) R-parity violating supersymmetry. In addition, the recently published “extended black box” theorem is briefly discussed. Combined with data from oscillation experiments this theorem provides proof that the 0 ν β β decay amplitude must receive a non-zero contribution from the mass mechanism, if neutrinos are indeed Majorana particles.
53701384
Enhancing $l_i 3 l_j$ with the $Z^0$-penguin
Lepton flavor violation (LFV) has been observed in neutrino oscillations. For charged lepton FV decays only upper limits are known, but sizable branching ratios are expected in many neutrino mass models. High scale models, such as the classical supersymmetric seesaw, usually predict that decays $l_i \to 3 l_j$ are roughly a factor $\alpha$ maller than the corresponding decays $l_i \to l_j \gamma$. Here we demonstrate that the $Z^0$-penguin diagram can give an enhancement for decays $l_i \to 3 l_j$ in many extensions of the MSSM. We first discuss why the $Z^0$-penguin is not dominant in the MSSM with seesaw and show that much larger contributions from the $Z^0$-penguin are expected in general. We then demonstrate the effect numerically in two example models, namely, the supersymmetric inverse seesaw and R-parity violating supersymmetry.
119290526
Probing a supersymmetric model for neutrino masses at ultrahigh energy neutrino telescopes
Abstract A bilinear R-parity breaking SUSY model for neutrino mass and mixing predicts the lightest superparticle to decay mainly into a pair of tau leptons or b quarks along with a neutrino for relatively light SUSY spectra. This leads to a distinctive triple bang signature of SUSY events at ultrahigh energy neutrino telescopes like IceCube or Antares. While the expected signal size is only marginal at IceCube, it will be promising for a future multi-km 3 size neutrino telescope.
11803420
Majoron emission in muon and tau decays revisited
9 pages, 4 figures.-- ISI article identifier:000264762400078.-- ArXiv pre-print avaible at: http://arxiv.org/abs/0902.0525
118584751
Sérsic galaxy models in weak lensing shape measurement: model bias, noise bias and their interaction
Cosmic shear is a powerful probe of cosmological parameters, but its potential can be fully utilised only if galaxy shapes are measured with great accuracy. Two major effects have been identified which are likely to account for most of the bias for maximum likelihood methods in recent shear measurement challenges. Model bias occurs when the true galaxy shape is not well represented by the fitted model. Noise bias occurs due to the non-linear relationship between image pixels and galaxy shape. In this paper we investigate the potential interplay between these two effects when an imperfect model is used in the presence of high noise. We present analytical expressions for this bias, which depends on the residual difference between the model and real data. They can lead to biases not accounted for in previous calibration schemes. By measuring the model bias, noise bias and their interaction, we provide a complete statistical framework for measuring galaxy shapes with model fitting methods from GRavitational lEnsing Accuracy Testing (GREAT) like images. We demonstrate the noise and model interaction bias using a simple toy model, which indicates that this effect can potentially be significant. Using real galaxy images from the Cosmological Evolution Survey (COSMOS) we quantify the strength of the model bias, noise bias and their interaction. We find that the interaction term is often a similar size to the model bias term, and is smaller than the requirements of the current and shortly upcoming galaxy surveys.