Leptogenesis without violation of B-L

We study the possibility of generating the observed baryon asymmetry via leptogenesis in the decay of heavy Standard Model singlet fermions which carry lepton number, in a framework without Majorana masses above the electroweak scale. Such scenario does not contain any source of total lepton number violation besides the Standard Model sphalerons, and the baryon asymmetry is generated by the interplay of lepton flavour effects and the sphaleron decoupling in the decay epoch.Comment: V2 (published version): 21 pages, 4 figures. Some explanations have been adde

Study on TIME Efficiency of Tuna (Thunnus SP) Catches Landing Toward Mooring TIME of the Long Liner at Fishing Port of Bungus, West Sumatera Province

A series survey activity was conducted on April-Mei 2013 at the fishing port Bungus,Padang city West Sumatera province. Purpose of this study is to know efficiency level of longliner fishing catches, which has been landed in fishing port and its factor influenced. The resultshow that the efficiency level of fishing catches landing time was 56.98-72.73%, with uploadingefficiency time was 64,65% in average. There is seven free variable influence on the timeefficiency of fishing landing, with the value r=0,836 and R2=83,6%. So the diversity ofindependent variable gives the contribution to the diversity assess of time efficiency as 83,6%

Minimal Lepton Flavour Violation and Leptogenesis with exclusively low-energy CP Violation

We study the implications of a successful leptogenesis within the framework of Minimal Lepton Flavour Violation combined with radiative resonant leptogenesis and the PMNS matrix being the only source of CP violation, which can be obtained provided flavour effects are taken into account. We find that the right amount of the baryon asymmetry of the universe can be generated under the conditions of a normal hierarchy of the light neutrino masses, a non-vanishing Majorana phase, sin(theta_{13})>0.13 and m_{nu,lightest}<0.04 eV. If this is fulfilled, we find strong correlations among ratios of charged LFV processes.Comment: published in JHEP, small change

Full Boltzmann equations for leptogenesis including scattering

We study the evolution of a cosmological baryon asymmetry produced via leptogenesis by means of the full classical Boltzmann equations, without the assumption of kinetic equilibrium and including all quantum statistical factors. Beginning with the full mode equations we derive the usual equations of motion for the right-handed neutrino number density and integrated lepton asymmetry, and show explicitly the impact of each assumption on these quantities. For the first time, we investigate also the effects of scattering of the right-handed neutrino with the top quark to leading order in the Yukawa couplings by means of the full Boltzmann equations. We find that in our full Boltzmann treatment the final lepton asymmetry can be suppressed by as much as a factor of 1.5 in the weak wash-out regime (K<1), compared to the usual integrated approach which assumes kinetic equilibrium and neglects quantum statistics. This suppression is in contrast with the enhancement seen in some previous studies that considered only decay and inverse decay of the right-handed neutrino. However, this suppression quickly decreases as we increase K. In the strong wash-out regime (K>1), the full Boltzmann treatment and the integrated approach give nearly identical final lepton asymmetries (within 10 % of each other at K>3). Finally, we show that the opposing effects of quantum statistics on decays/inverse decays and the scattering processes tend to reduce the net importance of scattering on leptogenesis in the full treatment compared to the integrated approach.Comment: 39 pages, 8 figures, typos corrected, replaced to match published versio

Delay performance in random-access grid networks

We examine the impact of torpid mixing and meta-stability issues on the delay performance in wireless random-access networks. Focusing on regular meshes as prototypical scenarios, we show that the mean delays in an $L\times L$ toric grid with normalized load $\rho$ are of the order $(\frac{1}{1-\rho})^L$. This superlinear delay scaling is to be contrasted with the usual linear growth of the order $\frac{1}{1-\rho}$ in conventional queueing networks. The intuitive explanation for the poor delay characteristics is that (i) high load requires a high activity factor, (ii) a high activity factor implies extremely slow transitions between dominant activity states, and (iii) slow transitions cause starvation and hence excessively long queues and delays. Our proof method combines both renewal and conductance arguments. A critical ingredient in quantifying the long transition times is the derivation of the communication height of the uniformized Markov chain associated with the activity process. We also discuss connections with Glauber dynamics, conductance and mixing times. Our proof framework can be applied to other topologies as well, and is also relevant for the hard-core model in statistical physics and the sampling from independent sets using single-site update Markov chains

Os discursos de licenciandos, professores universitários e secundários contribuindo para a reestruturação curricular de um curso de licenciatura em Física

Este estudo foca-se na reestruturação curricular de um curso de licenciatura em Física de uma universidade pública. No processo foram analisados, discursos de licenciandos, docentes universitários e professores em exercício procurando-se entender como as demandas desses grupos influenciaram na estrutura curricular resultante. Para interpretar os efeitos de sentidos presentes em documentos e discursos dos sujeitos envolvidos foram adotados referenciais teórico-metodológicos embasados em teorias críticas e na Análise de Discurso de linha francesa. A proposta final situou-se entre as exigências legais e a realidade acadêmica. A legislação consultada, os professores em exercício, os licenciandos e os formadores na Universidade, subsidiaram ou sinalizaram o que e como a estrutura curricular do Curso poderia ter ou ser alterada

Peningkatan Motivasi Belajar Matematika Melalui Pendekatan Contextual Teaching And Learning Bagi Siswa Kelas X Semester I SMA Islam Sudirman 2 Boyolali Tahun Ajaran 2011/2012

Penelitian ini bertujuan mengkaji dan mendiskripsikan peningkatan motivasi belajar matematika siswa melalui pendekatan pembelajaran kontekstual. Pendekatan penelitian adalah penelitian kualitatif dengan desain Penelitian Tindakan Kelas (PTK). Subyek penelitian yang dikenai tindakan adalah siswa kelas x Sma Islam Sudirman 2 Boyolali, yang berjumlah 27 siswa. Metode pengumpulan data, observasi, catatan lapangan, dan dokumentasi. Teknik analisis data secara deskriptif kualitatif dengan metode alur. Keabsahan data dilakukan dengan observasi secara terus menerus dan triangulasi data. Hasil penelitian ini menunjukkan adanya peningkatan motivasi belajar siswa yang dapat dilihat dari meningkatnya indikator banyaknya siswa yang antusias dalam: a) persiapan dalam mengikuti pembelajaran, sebelum tindakan 33,33%, putaran I 48,14%, putaran II 66,66%,dan pada putaran III 77,77% b) belajar kelompok sebelum tindakan 25,92%, putaran I 37,03%, putaran II 62,96% , dan pada putaran III 74,07%.c) menanggapi atau mengajukan pertanyaan, sebelum tindakan 7,40%, putaran I 14,81%, putaran II 33,33%, dan pada putaran III 48,14%. Kesimpulan penelitian ini adalah bahwa penerapan strategi pembelajaran kontekstual dapat meningkatkan motivasi belajar sisw

Dirac phase leptogenesis

I present here a concise summary of the preprint arXiv:0707.3024, written in collaboration with A. Anisimov and P. Di Bari. There we discuss leptogenesis when {\em CP} violation stems exlusively from the Dirac phase in the PMNS mixing matrix. Under this assumption it turns out that the situation is very constrained when a hierarchical heavy right-handed (RH) neutrino spectrum is considered: the allowed regions are small and the final asymmetry depends on the initial conditions. On the other hand, for a quasi-degenerate spectrum of RH neutrinos, the {\em CP} asymmetry can be enhanced and the situation becomes much more favorable, with no dependence on the initial conditions. Interestingly, in the extreme case of resonant leptogenesis, in order to match the observed baryon asymmetry of the Universe, we obtain a lower bound on \sin \q_{13} which depends on the lightest active neutrino mass m_1.Comment: 3 pages, 2 figures, contribution to the proceedings of the TAUP 07 conference, Sep. 11-15, Sendai, Japa

Shear Viscosity of Quark Matter

We consider the shear viscosity of a system of quarks and its ratio to the entropy density above the critical temperature for deconfinement. Both quantities are derived and computed for different modeling of the quark self-energy, also allowing for a temperature dependence of the effective mass and width. The behaviour of the viscosity and the entropy density is argued in terms of the strength of the coupling and of the main characteristics of the quark self-energy. A comparison with existing results is also discussed.Comment: 15 pages, 4 figure