Cosmology at the Terascale

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Cosmology at the Terascale

• P. Binétruy
• APC, Paris

Origins, Sèvres, 15 October 2007
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At t 400 000 yrs, the Universe becomes
transparent photons no longer interact with
matter
Looking back to the primordial Universe
BIG BANG
Cosmological background T 3 K - 270 C
WMAP satellite
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And before?
Terascale
?
gravitons and neutrinos
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If gravitons were in thermal equilibrium in the
primordial universe
? ?-1 d?/dlogf
?
g
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When do graviton decouple?
T5
Interaction rate
? GN2 T5 ----
MPl4
T2
Expansion rate
H ----
(radiation dominated era)
MPl
T3
?
---- ----
H
MPl3
Gravitons decouple at the Planck era fossile
radiation
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The cosmological evolution of the Universe in
the  redshifted Hubble frequency  diagram
.
Inverse apparent horizon size at scale factor a
H a / a
redshift
.
Frequency observed today f aH a
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.
rad domin. a?t1/2 log a - log a
.
log f log a
Inflation a?eHt log a log a
.
matter dom. a?t2/3 log a - log a / 2
log a
cosmic time
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log (T/1 eV)
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14
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VIRGO/LIGO
BBO
MSP
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A short tutorial on LISA (1)
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LISA
VIRGO
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Gravitational wave detection
VIRGO
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The LISA interferometer

• 1 W emission 70 pW reception.
• Interference between the internal beam and the
  incident laser beam
• 12 laser beams
• 6 lasers between satellites
• 6 internal reference lasers

5 106 km
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original apparatus used by Michelson and Morley
1887

• Sensitivity ?l 600 pm

• LISA requirement 40 pm/vHz

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LISA position
Earth-LISA distance 50 million kms
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LISA sky
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Verification binaries
WD 0957-666 WD-WD (0.37Ms, 0.32Ms) 100 pc from
Earth RXJ1914245 (Am/CVn binary) WD- He star
(0.6Ms, 0.07Ms) 100 pc from Earth 4U1820-30
StarNS (lt1Ms) 100 pc from Earth
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Back to the Terascale
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d ?GW
1
?GW --- --------
, ?c 3H0/(8?GN)
?c
d logf
for ?1
Gravitons produced at the electroweak phase
transition would be observed in the LISA window.
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But are gravitons produced in sufficient numbers
at the electroweak phase transition?
If the transition is first order, nucleation of
true vacuum bubbles inside the false vacuum
Collision of bubbles and turbulence ? production
of gravitational waves
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Pros and cons for a 1st order phase transition
at the Terascale

• in the Standard Model, requires mh lt 72 GeV
  (ruled out)
• MSSM requires too light a stop but generic in
  NMSSM
• possible to recover a strong 1st order
  transition by including H6 terms
• in SM potential
• other symmetries than SU(2)xU(1) at the
  Terascale (? baryogenesis)

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Two basic parameters
Efalse vac

• time variation of
• bubble nucleation rate

? ---------
aT4
radiation energy at transition
?-1 gt 10-3 H-1
duration of phase transition
(? ?H/?)
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Two basic parameters
Efalse vac

• time variation of
• bubble nucleation rate

? ---------
aT4
radiation energy at transition
h02 ?GW
?-1 10-2 H-1
duration of phase transition
Nicolis gr-qc/0303084
f in mHz
turbulence
bubble collision
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LISA potential reach is even higher than LHC
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Vacuum fluctuations de Sitter phase
Inflation
h02 ?GW 10-13 (H/10-4MPl)2
h02 ?GW 10-13(feq/f) 2(H/10-4MPl)2
Fluctuations reenter horizon during matter era
radiation era
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Production of gravitational waves during the
reheating period after inflation where the
matter and radiation that we observe today is
produced

• chaotic inflation

Parametric resonance
population of highly occupied modes matter waves
preheating
collisions ? GW with f 107 to 109 Hz

• hybrid inflation lowers the reheating
  temperature

expect lower frequencies
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High scale hybrid inflation v 10-2MP , ? g2
0.05
Low scale hybrid inflation v 10-5MP , ? g2
10-14
H 100 GeV
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A short tutorial on LISA (2)
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LISA sky
COSMOLOGY with LISA
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Pretorius 2005
gij ?4 ?ij
Re ?4 r in z0 plane
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LISA and dark energy
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Black hole coalescence may provide a new type of
standard candles
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Inspiral phase
(m1 m2)3/5
Key parameter chirp mass M
(1z)
(z)
(m1 m2)1/5
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Inspiral phase
(m1 m2)3/5
Key parameter chirp mass M
(1z)
(z)
(m1 m2)1/5
Amplitude of the gravitational wave
frequency f(t) d?/2?dt
M(z)5/3 f(t)2/3
h(t) F
(angles) cos ?(t)
dL
Luminosity distance
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Inspiral phase
(m1 m2)3/5
Key parameter chirp mass M
(1z)
(z)
(m1 m2)1/5
Amplitude of the gravitational wave
M(z)5/3 f(t)2/3
h(t) F
(angles) cos ?(t)
dL
Luminosity distance
poorly known in the case of LISA
10 arcmin
1 Hz
??
SNR
fGW
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z 1 , m1 105 M?, m2 6.105 M?
3
?? (arcminutes)
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Holz Hughes
?dL/dL
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Using the electromagnetic counterpart
Allows both a measure of the direction and of the
redshift
0.5
Holz and Hughes
?dL/dL
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3000 supernovae
100 SMBH sources
Dalal et al. astro-ph/0603275
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Conclusion
From the point of view of cosmology, LISA may be
seen as the  cosmic counterpart  of the LHC.
If LHC finds physics beyond the SM, important to
check what might be observed by LISA.
If LHC does not find anything besides a light
Higgs, even more important to go and check!
LISA may be a complementary tool for the study of
dark energy
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Gravitational waves
..
hij GN Qij / c4 r
Quadrupole formula
A simple case two masses on a circular orbit
chirp mass
solar mass
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(M1 M2)3/5
chirp mass M
(M1 M2)1/5
.
.
Rr1r2 rr1-r2
?M
1
1
Binary system L -- M R2 -- ? r2 G ----
r
2
2

Defining r ?1/2 r, the relative motion depends
on the mass only through
M (?3 M2)1/5
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How to measure a stochastic background?
Cross correlate ground interferometers
Let LISA move around the Sun
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Cosmic strings
Many versions of string theory predict the
cosmological formation of cosmic superstrings
that form after inflation.
Polchinski 2005
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value of G?
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Cosmic strings
Presence of cusps enhances the production of
gravitational waves
Damour-Vilenkin
log h
LIGO
stochastic GW background
log 50 GN?
zlt1
zgt1 (MD)
zgt1 (RD)
Loops radiate at