The Games for Universe. Yun-Song Piao Interdisciplinary Center of Theoretical Studies Chinese Academy of Sciences. Some of Rceent Works Piao, hep-th/0407258, Can Universe Experience Many Cycles with Different Vacua ?
Interdisciplinary Center of Theoretical Studies
Chinese Academy of Sciences
Can Universe Experience Many Cycles with
Different Vacua ?
accepted in Phys.Rev.D (Rapid Communication)
Piao, Feng, Zhang, hep-th/0310206,
Suppressing CMB Quadrupole with a Bounce from
Contracting Phase to Inflation
Preheating and Dark Sector of Universe
1) For an expanding universe with dS minimum, it will arrive at a dS regime symptotically.
2) The universe with AdS minimum can not approach an AdS regime, and instead it will stop expanding and enter into a collapsing phase. During the collapsing process, its energy goes up rapidly. The singularity will become inevitable unless there is a mechanism responsible for the bounce.
3) When the universe is in the contracting phase, the field can be driven and roll up along its potential, and arrive at a large enough value for asuccessful inflation to occur in expanding phase for a feasible bounce.
When the field rolls down to the minima of its potential, the universe will collapse eventually. In the minima of potential
The anti-frictional term can be neglected.
The motion of equation becomes
whose solution is
more, the oscillations of field ends. The universe enters
into the regime dominated by kinetic energy.
In high energy regime, we take for the bounce
During a cycle, the change of field value is approximately
When the anti-frictional term can be not neglected any more
The connection between different vacua provides a
suppression of scalar perturbation spectrum on large scale
For kinetic dominated and potential dominated phase
after matching background
For kinetic dominated phase
For inflation phase
Considering a coupe to a massive field
When phi field crosses the oringin, the occupation number
of chi particles suddenly acquire the value
The density of dark energy is about the same as dark energy’s
at present requires
Making phi stay in a false vacumm up to today requires
produced particles is