BRANE-WORLD BRANE-WORLD COSMOLOGY COSMOLOGY Porto 2004 University of Portsmouth Roy Maartens Revent reviews: Brax, Davis, vd Bruck, hep-th/0404011 RM, gr-qc/0312059
Transcript
Slide 1
BRANE-WORLD COSMOLOGY Porto 2004University of Portsmouth Roy
Maartens Revent reviews: Brax, Davis, vd Bruck, hep-th/0404011 RM,
gr-qc/0312059
Slide 2
standard cosmology highly successful standard cosmology highly
successful concordance model = excellent fit but still a paradigm
seeking a fundamental theory but still a paradigm seeking a
fundamental theory deep puzzles - inflation, deep puzzles -
inflation, dark energy, dark energy, dark matter, dark matter, more
to come more to come
Slide 3
GR breaks down GR breaks down need quantum gravity in the early
universe high-precision cosmology is probing the limits of GR no QG
theory as yet no QG theory as yet but M theory is a promising
candidate M theory needs extra dimensions + branes M theory needs
extra dimensions + branes can also lower the Planck scale can also
lower the Planck scale explain weakness of gravity explain weakness
of gravity
Slide 4
why dont we see the extra dimensions? conventional Kaluza-Klein
idea: conventional Kaluza-Klein idea: internal extra dimension too
small to be seen internal extra dimension too small to be seen
discovery of D-brane discovery of D-brane matter fields restricted
matter fields restricted to lower dimensional brane to lower
dimensional brane external bulk felt only external bulk felt only
through gravity through gravity extra dimension bigger extra
dimension bigger 4D spacetime small extra dimension large extra
dimension gravity
Slide 5
small extra dimensions = moduli fields m A (t,x) large extra
dimension = radion R(t,x) visible brane shadow brane THE BIG IDEA:
M THEORY WILL SOLVE PUZZLES * dilaton/radion = natural source of
brane inflation? * more radical: no inflation - brane-brane
collision = brane-brane collision = big bang (cyclic)? big bang
(cyclic)? * moduli = varying constants? * shadow matter = dark
matter? dark matter? dark energy? dark energy? dilaton D(t,x)
Slide 6
GR phenomenology QG the harsh reality the harsh reality still
no string/ M theory cosmology still no string/ M theory cosmology
even inflation/ dark energy hard to get even inflation/ dark energy
hard to get 2 parallel approaches 2 parallel approaches * hunt for
string/ M theory cosmology * hunt for string/ M theory cosmology *
use braneworld phenomenology * use braneworld phenomenology
braneworld cosmology braneworld cosmology use M theory ideas in
cosmology use M theory ideas in cosmology use high-precision data
to test & constrain models use high-precision data to test
& constrain models
Slide 7
2 key features 2 key features braneworld gravity brings new
features braneworld gravity brings new features KK modes of the
graviton KK modes of the graviton new fields (moduli, dilaton,) new
fields (moduli, dilaton,) shadow matter shadow matter holography,
holography, precision data constrains extra-dimensional gravity
precision data constrains extra-dimensional gravity dynamics BBN,
SNe dynamics BBN, SNe perturbations CMB and LSS perturbations CMB
and LSS
Slide 8
start with simple models start with simple models similar to
inflation and dark energy models similar to inflation and dark
energy models simplest models with predictive power simplest models
with predictive power focus on one or two key aspects at a time
focus on one or two key aspects at a time KK modes of graviton KK
modes of graviton scalar fields radion, dilaton, moduli scalar
fields radion, dilaton, moduli . . Randall-Sundrum braneworlds 5D
models 5D models gravity itself is central gravity itself is
central warped extra dimension warped extra dimension