The non-linear evolution of a bus fare rise

Yesterday was an atypical day in Brazil. It all started on June 1st with a rise in the bus fare in almost all major cities. The fare rose about 7%, the inflation since the last fare rise.  On June 6 some people in São Paulo organized the first rally against the fare rise and called it PASSE LIVRE, free fare. Not many people showed up. They walked along  some main streets causing troubles for the local traffic. The police tried to repress the demonstration and they came into conflict resulting in violence from both sides. The next day some more people showed up and the same violence happened again. Other cities in Brazil started doing the same. On June 13 the fourth demonstration in São Paulo was too violent. The riot police was blamed and accused of violence, vandalism and intolerance. It was then agreed that the police would not interfere with the fifth demonstration which happened yesterday.

So in a plain Monday, a regular working day, it happened. More than 65.000 people were protesting not only against the rise in the bus fare, but also against the services provided by the state. Poor education system, bad health services, lack of security. Others were protesting against corruption, mainly governmental corruption which seems endless. And there were even people complaining about the expenses with the next FIFA World Cup and Olympics which will happen in a few years time in Brazil. The demonstration started at 5 pm and went on during the night luckily without any violence. But that is not all. Demonstrations happened in many other cities all over Brazil also asking for the same. Unfortunately some were much more violent than in São Paulo. In Rio de Janeiro the city assembly was attacked while in Brasília people got to the roof of the congress building. Altogether about A QUARTER OF A MILLION people were in the streets yesterday! Brazilians are awakening at last and asking for their rights!

If you google PASSE LIVRE or go to YouTube you can see what happened in several cities. But there is video which explains it all. It seems it was recorded before yesterday´s demonstration.

Porque supersimetria?

Depois do vídeo explicando o que é supersimetria temos agora outro vídeo explicando porque a supersimetria é necessária. Vale a pena conferir.

Tetraquarks?

Na natureza os quarks sempre aparecem em combinações de três quarks formando bárions (como o próton e o nêutron) ou num par quar-anti-quark formando mésons (como o píon). Em 2005 foi descoberta uma partícula exótica chamada de Y(4260) que parece ser composta de dois quarks e um glúon (a partícula responsável pela força forte). Para tentar compreender a estrutura dessa partícula dois grupos, BELLE (no Japão) e BESIII (na China), estudaram o decaimento do Y(4260) e descobriram uma nova partícula, denominada Zc(3900) e que parece ser ainda mais exótica que a Y(4260). A nova partícula possui carga elétrica e um quark charmoso e anti-quark charmoso e parece conter mais dois quarks, um quark up e um anti-quark down, uma partícula com quatro quarks! Anos atrás outros grupos experimentais encontraram evidências de tetra quarks mas este é o primeiro resultado experimental com resultados mais sólidos. Porém, outras interpretações não estão excluídas ainda. A Zc(3900) poderia ser um estado ligado de dois mésons formando uma molécula hadrônica, um proposta teórica que nunca foi detectada experimentalmente. Outra interpretação menos excitante é que poderia ser apenas um estado com dois mésons porém sem formar uma  molécula hadrônica. Mais dados são necessários para compreender essa partículas. Vamos aguardar. Os dois trabalhos foram publicados no Physical Review Letters desta semana.