Martinez Torres, A., Garzon, E. J., Oset, E., & Dai, L. R. (2011). Limits to the fixed center approximation to Faddeev equations: The case of the phi(2170). Phys. Rev. D, 83(11), 116002–9pp.
Abstract: The fixed center approximation to the Faddeev equations has been used lately with success in the study of bound systems of three hadrons. It is also important to set the limits of the approach in those problems to prevent proliferation of inaccurate predictions. In this paper, we study the case of the phi(2170), which has been described by means of Faddeev equations as a resonant state of phi and K (K) over bar, and show the problems derived from the use of the fixed center approximation in its study. At the same time, we also expose the limitations of an alternative approach recently proposed.
|
Giusarma, E., Corsi, M., Archidiacono, M., de Putter, R., Melchiorri, A., Mena, O., et al. (2011). Constraints on massive sterile neutrino species from current and future cosmological data. Phys. Rev. D, 83(11), 115023–10pp.
Abstract: Sterile massive neutrinos are a natural extension of the standard model of elementary particles. The energy density of the extra sterile massive states affects cosmological measurements in an analogous way to that of active neutrino species. We perform here an analysis of current cosmological data and derive bounds on the masses of the active and the sterile neutrino states, as well as on the number of sterile states. The so-called (3 + 2) models, with three sub-eV active massive neutrinos plus two sub-eV massive sterile species, is well within the 95% CL allowed regions when considering cosmological data only. If the two extra sterile states have thermal abundances at decoupling, big bang nucleosynthesis bounds compromise the viability of (3 + 2) models. Forecasts from future cosmological data on the active and sterile neutrino parameters are also presented. Independent measurements of the neutrino mass from tritium beta-decay experiments and of the Hubble constant could shed light on sub-eV massive sterile neutrino scenarios.
|
Krauss, M. B., Ota, T., Porod, W., & Winter, W. (2011). Neutrino mass from higher than d=5 effective operators in supersymmetry, and its test at the LHC. Phys. Rev. D, 84(11). Retrieved June 13, 2024, from http://dx.doi.org/10.1103/PhysRevD.84.115023
Abstract: We discuss neutrino masses from higher than d = 5 effective operators in a supersymmetric framework, where we explicitly demonstrate which operators could be the leading contribution to neutrino mass in the minimal supersymmetric standard model and next to minimal supersymmetric standard model. As an example, we focus on the d = 7 operator LLH(u)H(u)H(d)H(u), for which we systematically derive all tree-level decompositions. We argue that many of these lead to a linear or inverse seesaw scenario with two extra neutral fermions, where the lepton number violating term is naturally suppressed by a heavy mass scale when the extra mediators are integrated out. We choose one example, for which we discuss possible implementations of the neutrino flavor structure. In addition, we show that the heavy mediators, in this case SU(2) doublet fermions, may indeed be observable at the LHC, since they can be produced by Drell-Yan processes and lead to displaced vertices when they decay. However, the direct observation of lepton number violating processes is on the edge at LHC.
|
Perez-Ramos, R., Mathieu, V., & Sanchis-Lozano, M. A. (2011). Three-particle correlations in QCD jets and beyond. J. Phys. G, 38(11), 115007–34pp.
Abstract: In this paper, we present a detailed study of three-particle correlations in quark and gluon jets. We give theoretical results for this observable in the double logarithmic approximation and the modified leading logarithmic approximation. In both resummation schemes, we use the formalism of the generating functional and solve the evolution equations analytically from the steepest descent evaluation of the one-particle distribution. In addition, in this paper we include predictions beyond the limiting spectrum approximation and study this observable near the hump of the single inclusive distribution. We thus provide a further test of the local parton hadron duality and make predictions for the LHC. The computation of higher rank correlators is presented in the double logarithmic approximation and shown to be rather cumbersome.
|
Kaneko, S., Saito, H., Sato, J., Shimomura, T., Vives, O., & Yamanaka, M. (2011). Correlation between flavor-violating decay of long-lived slepton and tau in the coannihilation scenario with the seesaw mechanism. Phys. Rev. D, 83(11), 115005–10pp.
Abstract: We investigate flavor violating decays of the long-lived lightest slepton and the tau lepton in the coannihilation region of the minimal supersymmetric standard model with a seesaw mechanism to generate neutrino masses. We consider a situation where the mass difference between the lightest neutralino, as the lightest supersymmetric particle, and the lightest slepton, as the next-to-lightest supersymmetric particle, is smaller than the mass of tau lepton. In this situation, the lifetime of the lightest slepton is very long and it is determined by lepton flavor violating (LFV) couplings because the slepton mainly consists of the lighter stau and the flavor conserving 2-body decay is kinematically forbidden. We show that the lifetime can change many orders of magnitude by varying the Yukawa couplings entering the seesaw mechanism. We also show that the branching ratios of LFV tau decays are strongly correlated with the lightest slepton lifetime. Therefore the branching ratios of LFV tau decays can be determined or constrained by measuring the slepton lifetime at the LHC experiment.
|
