Leptogenesis without CP Violation at Low Energies

In this letter we give a class of examples where the decays of the heavy Majorana neutrinos may violate CP even if there is no CP violation at low energies, i.e., leptogenesis can take place without Majorana or Dirac type CP phases at low energies.Comment: 7 pages, no figures. One comment and references added. Version proof rea

Essentials for sustainable urban transport in Brazil's large metropolitan areas

Before financing major urban transport projects, decisionmakers should attempt to put in place the basic elements for long-term sustainability of the sector. Specifically, the author contends that each large metropolitan area in Brazil should incorporate into its urban transport strategy, and pursue vigorously, the following four-point agenda: 1) create a regional transport coordination commission in charge of coordinating policies among federal, state, and municipal governments, giving highest priority to major urban transport investments in the metropolitan region and promoting modal integration - all to the end of improving the sector's economic efficiency and long-term sustainability; 2) adopt an integrated land use, urban transport, and air quality strategy that provides a framework in which the community and decisionmakers can evaluate future urban transport investments and policies; 3) enact into law formal financing mechanisms that would ensure that long-run variable costs of urban transport systems are covered by operating and non-operating revenues from the systems and by appropriate user charges; and 4) promote private sector participation in the operation, maintenance, and construction of urban transport systems - through concessions or management contracts - as a way to lessen the financial burden on the government.Roads&Highways,Public Sector Economics&Finance,Banks&Banking Reform,Municipal Financial Management,Environmental Economics&Policies,Urban Transport,Banks&Banking Reform,Roads&Highways,Municipal Financial Management,Environmental Economics&Policies

Reforming the urban transport sector in the Rio de Janeiro metropolitan region - a case study in concessions

The author describes a bold effort by the state government to increase private sector participation in Rio de Janeiro's urban transport sector, reduce heavy operating subsidies, and establish a foundation for making the sector sustainable. This effort was undertaken with the help of three World Bank-financed loans: * The Rio de Janeiro Metropolitan Transport Loan, which provided assistance for the transfer of federally owned suburban railways to the state government. * The Rio de Janeiro State Reform and Privatization Loan, which helped the state privatize and grant concessions for a number of its enterprises. * The Rio de Janeiro Mass Transit Loan, which supported the reorganization of the sector and the concession of the Rio suburban railways (Flumitrens). Most of the reforms in the urban transport sector have been implemented. The lessons learned from implementation and the results obtained so far suggest that political decisiveness, transparency, and ingenuity in developing incentives are crucial to privatizing urban rail transport systems. But the state also learned that not having a credible staff redundancy program might seriously reduce the benefits expected from concessions.Banks&Banking Reform,Municipal Financial Management,Economic Adjustment and Lending,Roads&Highways,Decentralization,National Governance,Banks&Banking Reform,Municipal Financial Management,Urban Transport,Roads&Highways

A Simple Method to detect spontaneous CP Violation in multi-Higgs models

For models with several Higgs doublets we present an alternative method to the one proposed by Branco, Gerard and Grimus, in 1984, to check whether or not CP is spontaneously violated in the Higgs potential. The previous method is powerful and rigorous. It requires the identification of a matrix $U$ corresponding to a symmetry of the Lagrangian and verifying a simple relation involving the vacuum expectation values. The nonexistence of such a matrix signals spontaneous CP violation. However, as the number of Higgs doublets increases, finding such a matrix $U$ may not be straightforward and it may turn out to be easier to analyse the potential by going to the so-called Higgs basis. The transformation to the Higgs basis is straightforward once the vacuum expectation values are known. The method proposed in this work is also powerful and rigorous and can be particularly useful to analyse models with more than two Higgs doublets and with continuous symmetries.Comment: 9 pages, no figures. v2: minor changes, matching JHEP versio

Impact of Inter-Country Distances on International Tourism

Tourism is a worldwide practice with international tourism revenues increasing from US\$495 billion in 2000 to US\$1340 billion in 2017. Its relevance to the economy of many countries is obvious. Even though the World Airline Network (WAN) is global and has a peculiar construction, the International Tourism Network (ITN) is very similar to a random network and barely global in its reach. To understand the impact of global distances on local flows, we map the flow of tourists around the world onto a complex network and study its topological and dynamical balance. We find that although the WAN serves as infrastructural support for the ITN, the flow of tourism does not correlate strongly with the extent of flight connections worldwide. Instead, unidirectional flows appear locally forming communities that shed light on global travelling behaviour inasmuch as there is only a 15% probability of finding bidirectional tourism between a pair of countries. We conjecture that this is a consequence of one-way cyclic tourism by analyzing the triangles that are formed by the network of flows in the ITN. Finally, we find that most tourists travel to neighbouring countries and mainly cover larger distances when there is a direct flight, irrespective of the time it takes

Nondecoupling of Heavy Fermions and a Special Yukawa Texture

Talk based on work entitled ``Yukawa textures, new physics and nondecoupling,'' done in collaboration with G. C. Branco and J. I. Silva-Marcos, arXiv:hep-ph/0612252, to appear in Phys. Rev. D. In this work we pointed out that New Physics can play an important r\^ ole in rescuing some of the Yukawa texture zero ans\" atze which would otherwise be eliminated by the recent, more precise measurements of $V_{CKM}$. We have shown that the presence of an isosinglet vector-like quark which mixes with standard quarks, can render viable a particularly interesting four texture zero Yukawa ansatz. The crucial point is the nondecoupling of the effects of the isosinglet quark, even for arbitrary large values of its mass.Comment: Invited talk at CTP Symposium on Supersymmetry at LHC: Theoretical and Experimental Prospectives, Cairo, Egypt, 11-14 Mar 200