Enhancing li→3ljl_i \to 3 l_j with the Z0Z^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.Comment: 5 pages; v2: minor corrections, final version to appear in PR

Structural vulnerability of Nepalese Pagoda temples

Nepal is located in one of the most severe earthquake prone areas of the world, lying between collisions of Indian to the Eurasian plate, moving continuously, resulting in frequent devastating earthquakes within this region. Moreover, different authors refer mention that the accumulated slip deficit (central seismic gap) is likely to produce large earthquakes in the future. Also, the analysis of the available information of previous earthquakes indicates the potential damage that can occurs in unreinforced traditional masonry structures in future earthquakes. Most of the Nepalese pagoda temples were erected following very simple rules and construction details to accomplish with seismic resistance requirement, or even without any consideration for seismic resistance, during the period of Malla dynasty (1200-1768). Presently, conservation and restoration of ancient monuments are one of the major concerns in order to preserve our built heritage, transferring it to the future generations. The present paper is devoted to outline particular structural fragility characteristics in the historic Nepalese pagoda temples which affect their seismic performance. Moreover, based on the parametric analysis identified structural weaknesses/fragilities of pagoda topology, the associated traditional building technology and constructional details

Numerical simulations of quiet Sun magnetic fields seeded by Biermann battery

The magnetic fields of the quiet Sun cover at any time more than 90\% of its surface and their magnetic energy budget is crucial to explain the thermal structure of the solar atmosphere. One of the possible origins of these fields is due to the action of local dynamo in the upper convection zone of the Sun. Existing simulations of the local solar dynamo require an initial seed field, and sufficiently high spatial resolution, in order to achieve the amplification of the seed field to the observed values in the quiet Sun. Here we report an alternative model of seeding based on the action of the Bierman battery effect. This effect generates a magnetic field due to the local imbalances in electron pressure in the partially ionized solar plasma. We show that the battery effect self-consistently creates from zero an initial seed field of a strength of the order of micro G, and together with dynamo amplification, allows the generation of quiet Sun magnetic fields of a similar strength to those from solar observations.Comment: To appear in Astronomy & Astrophysic

Double Pion Photoproduction in Nuclei

The inclusive A(gamma,pi+ pi-)X reaction is studied theoretically. A sizeable enhancement of the cross section is found, in comparison with the scaling of the deuteron cross section (sigma_deuteron * A/2). This enhancement is due to the modifications in the nuclear medium of the gamma N ----> pi pi N amplitude and the pion dispersion relation. The enhancement is found to be bigger than the one already observed in the (pi,pi pi) reaction in nuclei.Comment: 11 pages, 7 figures (figures available from authors); TeX, Version 3.141 [PD VMS 3.4/CERN 1.0

High frequency waves in the corona due to null points

This work aims to understand the behavior of non-linear waves in the vicinity of a coronal null point. In previous works we have showed that high frequency waves are generated in such magnetic configuration. This paper studies those waves in detail in order to provide a plausible explanation of their generation. We demonstrate that slow magneto-acoustic shock waves generated in the chromosphere propagate through the null point and produce a train of secondary shocks that escape along the field lines. A particular combination of the shock wave speeds generates waves at a frequency of 80 mHz. We speculate that this frequency may be sensitive to the atmospheric parameters in the corona and therefore can be used to probe the structure of this solar layer

Determining the Θ+\Theta^+ quantum numbers through a Kaon induced reaction

We study the $K^+p\to \pi^+KN$ reaction with kinematical condition suited to the production of the $\Theta^+$ resonance. It is shown that in this reaction with the polarization experiment, a combined consideration of the strength at the peak and the angular dependence of cross section can help determine the $\Theta^+$ quantum numbers.Comment: 4 pages, 3 figures, Talk given at International Workshop PENTAQUARK04 at SPring-8, Japan, July 20-23, 200

Lower bounds on concurrence and separability conditions

We obtain analytical lower bounds on the concurrence of bipartite quantum systems in arbitrary dimensions related to the violation of separability conditions based on local uncertainty relations and on the Bloch representation of density matrices. We also illustrate how these results complement and improve those recently derived [K. Chen, S. Albeverio, and S.-M. Fei, Phys. Rev. Lett. 95, 040504 (2005)] by considering the Peres-Horodecki and the computable cross norm or realignment criteria.Comment: 5 pages, 1 figure; minor changes, references added; final version: minor correction in proof of lemma 1, scope of theorem 2 clarified, to appear in PRA; mistake in proof of lemma 1 of published version corrected, results unchange