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« The incredible progresses of particle physics and cosmology ». Does our knowledge of the laws of microscopic physics help us to understand the universe at large?. P. Binétruy AstroParticule et Cosmologie, Paris. XII International Workshop on « Neutrino Telescopes » - PowerPoint PPT Presentation
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« The incredible progresses of particle physics and cosmology »
P. Binétruy
AstroParticule et Cosmologie, Paris
XII International Workshop on « Neutrino Telescopes » Venezia, Palzzo Franchetti, 9 March 2007
Does our knowledge of the laws of microscopic physics help us to understand the universe at large?
A microscopic world almost fully explored (in as much as it is known)
All ingredients of the Standard Model as we know it have been understood and confirmed except for the Higgs
All observations on quark mixing are consistent with a single CP-violating phase
€
ν e
ν μ
ν τ
≅
cosθ12 sinθ12 0
−sinθ12 cosθ12 0
0 0 1
×
cosθ13 0 sinθ13
0 1 0
sinθ13 0 cosθ13
×
1 0 0
0 1 0
0 0 e−iδ
1 0 0
0 cosθ23 sinθ23
0 −sinθ23 cosθ23
×
ν 1
ν 2
ν 3
Atmos. neutrinosSolar neutrinos
€
θ13 ? ; δCP ???
Neutrinos : most of the MNSP mixing matrix is known
Remaining unexplained :
• mass hierarchies, i.e. a theory of Yukawa couplings
• strong CP-violating phase i.e. θ < 10-9
Horizontal symmetries?
A universe at large which remains largely unexplained in the context of the Standard Model :
• dark matter• acceleration of the universe• matter-antimatter antisymmetry
Dark matter
Galaxy rotation curves
Lensing
h2 ~109 GeV-1 xf
g*1/2 MP < ann v >
25
Number of deg. of freedom at time of decoupling
mass ~ MEW < ann v > ~ EW/MEW 2 h2 ~ 1
to be compared with dark h2 = 0.112 0.009
New particles may be valuable candidates
Weakly Interacting Massive Particles (absent in SM)
Supernovae (Sn Ia) :
astro-ph/0402512
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Hubble plot : magnitude vs redshift
Recent acceleration of the Universe
Matter-antimatter asymmetry
No working astrophysical model
From the point of view of fundamental physics, 3 necessary ingredients (Sakharov) :
• CP violation • B violation • out of equilibrium first order phase transition mHiggs > 72 GeV
Will the theories of the microscopic world allow us to understandbetter the Universe at large?
NO : the vacuum energy (cosmological constant) problem
Classically, the vacuum energy is not measurable. Only differencesof energy are (e.g. Casimir effect).
Einstein equations: Rν - R gν/2 = 8G Tν
Hence geometry may provide a way to measure absolute energies e.g. vacuum energy:
geometry energy
-1/2 ~ MW -1
~ 10 -18 m electroweak scale
or -1/2 ~ mP-1 ~ 10 -34 m Planck scale
Rν - R gν/2 = 8G Tν + g ν
~ 0.7 ~ 1 -1/2 ~ H0 -1 =10 26 m
size of the presently visible universe
A very natural value for an astrophysicist !
A high energy theorist would compute the vacuum energy and find
Related questions : why now? why is our Universe so large, so old?
YES : the example of dark matter
Will the theories of the microscopic world allow us to understandbetter the Universe at large?
Connecting the naturalness of the electroweak scale with the existence of WIMPs
naturalness
mh2 = t
2 - g2 - h
23mt
2
22v2
6MW2 + 3MZ
2
8 2v2
3mh2
8 2v2
Naturalness condition : |mh2 | < mh
2
v = 250 GeV
Introduce new physics at t (supersymmetry, extra dimensions,…) or raise mh to 400 GeV range
stable particles in the MEW mass range
E
New local symmetry
Standard Modelfermions
New fields
stable particles in the MEW mass range
E
New local symmetry
New discrete symmetry
Standard Modelfermions
New fields
Lightest odd-parityparticle is stable
Example : low energy SUSY
E
R symmetry
R parity
Standard Modelfermions
Supersymmetricpartners
Stable LSP
Bullet proof
Dark matterGravitational lensing
Ordinary matterX-rays (Chandra)
astro-ph/0611496
Clowe, Randall, Markevitch
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Going beyond : what might the infinitely small tell us in the future about the infinitely large?
• discovery of scalar particles• discovery of WIMPs• (discovery of extra dimensions)
Fundamental scalar fields
The discovery of the Higgs would provide the first fundamental scalar particle.
Scalars are the best remedy to cure cosmological problems:
Inflation, dark energy, compactification radius stabilization…
Scalars tend to resist gravitational clustering and thus may provide a diffuse background
Speed of sound cs2 = p/ ~ c2
Can we hope to test the dark energy idea at colliders?
Most popular models based on scalar fields (quintessence) :
V
has to be very light : m ~ H0
~ 10-33 eV
exchange would provide a long range force : has to be extremely weakly coupled to matter
HOPELESS FOR COLLIDERS
Dark matter: search of WIMPs at LHC
missing energy signal
Produced in pair : difficult to reconstruct, in the absence of a specific model
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search through direct detection
e.g. minimal sugra model
Going beyond : what might the infinitely large tell us in the future about the infinitely small?
• cosmological data and neutrino masses• gravitational waves and the electroweak phase transition• high energy cosmic rays and extra dimensions
Testing the scale of (lepton) flavour violations
Neutrino masses Baryon asymmetry
Flavour violations
Flavor physicsMF ~ 1010 GeV ?
Cosmology
Colliders
ν =mν /(92.5eV)
mν = MEW2 / MF
Data ∑mνi
(95%CL)
Nν
WMAP 1.8 eV -
WMAP+SDSS 1.3 eV 7.1+4.1
WMAP+2dFGRS 0.88 eV 2.7 1.4
CMB+LSS+SN 0.66 eV 3.3 1.7
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fraction of ν in dark matter
mνi
darkh2
baryonh2
WMAPSDSS
astro-ph/0310723
WMAP 3 yr: astro-ph/0603449
Electroweak phase transition and gravitational waves
If the transition is first order,nucleation of true vacuum bubblesinside the false vacuum
Collision of bubbles production of gravitational waves
• in the Standard Model, requires mh < 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)
Pros and cons for a 1st order phase transition at the Terascale:
.
Gravitons of frequency f produced at temperature T are observed at a redshifted frequency
f = 1.65 10-7 Hz --- ( ----- ) ( ---- )1 T
1GeV
g
100
1/6
At production = H-1
Horizon lengthWavelength
g is the number of degrees of freedom
LF band0.1 mHz - 1 Hz
VIRGO
Gravitational wave detection
Gravitational wave amplitude
LF band0.1 mHz - 1 Hz
VIRGO
T in GeV10 3 10 6 10 9
Gravitational wave amplitude
LF band0.1 mHz - 1 Hz
VIRGO
T in GeV10 3 10 6 10 9
Electroweak breaking scale
LISAlaunch > 2015
ESA/NASA mission
Three satellites forming a triangle of 5 million km sides
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High energy cosmic rays and extra dimensions
Extra dimensions
Black holes
More than 3 dimensions to our space?
Why ask?
Unification of gravity with the other interactions seems to require it :• unification electromagnetism-gravity (Kaluza 1921-Klein 1926)• unification of string theory (>1970)
For a theory in D=4+n dimensions with n dimensions compactifiedon a circle of radius R :
mPl2 = MD
2+n Rn
MD fundamental scale of gravity in D dimensions
If MD ~ 1 TeV, possible to produce black holes
Relevant scale for a black hole of mass MH is Schwarzschild radius:
rS ~ ----- --------1
MD
MBH
MD( )
1/1+n
Thorne: a black hole forms in a 2-particle collision if the impact parameteris smaller than rS.
~ rS2
gauge inter.gravity
matter
Hawking evaporation of the BH caracterized by the temperature
TH = _______n+1
4 rS
dE / dt TH4+n gives BH ~ ----- --------
MBH
)MD MD(3+n/1+n
1
BH decays visibly to SM particles:• large multiplicity N ~ MBH / (2TH)• large total transverse energy• characterisitic ratio of hadronic to leptonic activity of 5:1
Search for BH formation in high energy cosmic ray events
Look for BH production by neutrinos in order to overcome the QCD background:
horizontal showers
(ν N BH) for n=1 to 7 and MD = 1 TeV
SM (ν N l X)Anchordoqui, Feng, Goldberg, Shapere hep-th/0307228
n=1
ν N BH MD-2(2+n)/(1+n)
hep-ph/0206072
xmin = MBHmin/MD
MBHmin smallest BH mass for which we
trust the semi-classical approximation.
Includes inelasticity :
MBH ≠ s
hep-ph/0311365
Auger : bkgd of 2SM ν + 10 hadronic evts
n=6
Does our knowledge of the laws of microscopic physics help us to understand the universe at large?
Three and a half scenarios :
• The orthodox scenario : discovery of supersymmetry at LHC Pros : light HiggsCons : too orthodoxThis would confirm the general features of the « fundamental » universe as we understand it : role of scalars, nature of dark matter, string theory probable quantum theory of gravity…
• The standard scenario : discovery only of the HiggsPros : minimalCons : too standard, mass hierachies not addressedThis might be the end of large colliders. Only way of doing high energy physics might be through neutrinos and astroparticles
• The favourite scenario: discovery of something unexpected
• The radical scenario : discovery of large extra dimensionsPros : new ways of breaking symmetriesCons : why large? Revolutionize our perspectives on the Universe. String theory probable quantum theory of gravity. BH production may overcome any future collider signatures.
In any case, particles will provide a new way of studying the Universe
Ideally, one would like to study the same source (*) by detecting the gravitational waves, neutrinos, hadrons and photons emitted :
(*) Applies also to the primordial universe!
• gravitational waves give information on the bulk motion of matter in energetic processes (e.g. coalescence of black holes)
• neutrinos give information on the deepest zones, opaque to photons (e.g. on the origin --hadronic or electromagnetic-- of ).
• protons provide information on the cosmic accelerators that have produced them
• high energy photons trace populations of accelerated particules, as well as dark matter annihilation