« 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 » Venezia, Palzzo Franchetti, 9 March 2007

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 

Neutrinos : most of the MNSP mixing matrix is known Atmos. neutrinos Solar neutrinos

Remaining unexplained : mass hierarchies, i.e. a theory of Yukawa couplings Horizontal symmetries? strong CP-violating phase i.e.  < 10-9

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

New particles may be valuable candidates 25 109 GeV-1 xf  h2 ~ g*1/2 MP < ann v > 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 Weakly Interacting Massive Particles (absent in SM)

Recent acceleration of the Universe Supernovae (Sn Ia) : Hubble plot : magnitude vs redshift astro-ph/0402512

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 understand better the Universe at large?

NO : the vacuum energy (cosmological constant) problem Classically, the vacuum energy is not measurable. Only differences of energy are (e.g. Casimir effect). Einstein equations: R - R g/2 = 8G T geometry energy Hence geometry may provide a way to measure absolute energies e.g. vacuum energy:

R - R g/2 = 8G T +  g   ~ 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 -1/2 ~ MW -1 ~ 10 -18 m electroweak scale or -1/2 ~ mP-1 ~ 10 -34 m Planck scale Related questions : why now? why is our Universe so large, so old?

Will the theories of the microscopic world allow us to understand better the Universe at large? YES : the example of dark matter

Connecting the naturalness of the electroweak scale with the existence of WIMPs naturalness 3mt2 22v2 6MW2 + 3MZ2 8 2v2 3mh2 8 2v2 mh2 = t2 - g2 - h2 v = 250 GeV Naturalness condition : |mh2 | < mh2 Introduce new physics at t (supersymmetry, extra dimensions,…) or raise mh to 400 GeV range

stable particles in the MEW mass range New local symmetry Standard Model fermions New fields

stable particles in the MEW mass range New local symmetry Lightest odd-parity particle is stable New discrete symmetry Standard Model fermions New fields

Example : low energy SUSY R symmetry Stable LSP R parity Standard Model fermions Supersymmetric partners

Bullet proof Ordinary matter Dark matter X-rays (Chandra) Clowe, Randall, Markevitch Bullet proof astro-ph/0611496 Dark matter Gravitational lensing Ordinary matter X-rays (Chandra)

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) :  has to be very light : m  ~ H0 ~ 10-33 eV V  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

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 Cosmology  =m /(92.5eV) Baryon asymmetry Neutrino masses m = MEW2 / MF Flavor physics MF ~ 1010 GeV ? Flavour violations Colliders

baryonh2 darkh2  in dark  mi Data ∑mi (95%CL) N 1.8 eV - 1.3 eV astro-ph/0310723 baryonh2 darkh2 fraction of  in dark matter WMAP 3 yr: astro-ph/0603449  mi Data ∑mi (95%CL) N 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 SDSS WMAP

Electroweak phase transition and gravitational waves If the transition is first order, nucleation of true vacuum bubbles inside the false vacuum Collision of bubbles  production of gravitational waves

Pros and cons for a 1st order phase transition at the Terascale: 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)

Gravitons of frequency f produced at temperature T are observed . Gravitons of frequency f produced at temperature T are observed at a redshifted frequency 1/6 f = 1.65 10-7 Hz --- ( ----- ) ( ---- ) 1 T g  1GeV 100 At production  =  H-1 Wavelength Horizon length g is the number of degrees of freedom

Gravitational wave detection LF band 0.1 mHz - 1 Hz Gravitational wave amplitude VIRGO

LF band 0.1 mHz - 1 Hz Gravitational wave amplitude VIRGO T in GeV 10 3 10 6 10 9

Electroweak breaking scale LF band 0.1 mHz - 1 Hz VIRGO T in GeV 10 3 10 6 10 9

LISA launch > 2015 ESA/NASA mission Three satellites forming a triangle of 5 million km sides

High energy cosmic rays and extra dimensions Black holes Extra dimensions

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 compactified on a circle of radius R : mPl2 = MD2+n Rn MD fundamental scale of gravity in D dimensions

( ) If MD ~ 1 TeV, possible to produce black holes matter If MD ~ 1 TeV, possible to produce black holes gravity gauge inter. Relevant scale for a black hole of mass MH is Schwarzschild radius: 1/1+n 1 MBH rS ~ ----- -------- ( ) MD MD Thorne: a black hole forms in a 2-particle collision if the impact parameter is smaller than rS.  ~  rS2

( ) Hawking evaporation of the BH caracterized by the temperature n+1 4 rS 3+n/1+n MBH 1 ( ) dE / dt  TH4+n gives BH ~ ----- -------- MD MD 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

 ( N  BH) for n=1 to 7 and MD = 1 TeV  N  BH  MD-2(2+n)/(1+n) n=1 SM ( N  l X) Anchordoqui, Feng, Goldberg, Shapere hep-th/0307228

hep-ph/0206072

Includes inelasticity : MBH ≠ s n=6 Auger : bkgd of 2SM  + 10 hadronic evts xmin = MBHmin/MD MBHmin smallest BH mass for which we trust the semi-classical approximation. hep-ph/0311365

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 Higgs Cons : too orthodox This 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 Higgs Pros : minimal Cons : too standard, mass hierachies not addressed This might be the end of large colliders. Only way of doing high energy physics might be through neutrinos and astroparticles

The radical scenario : discovery of large extra dimensions Pros : new ways of breaking symmetries Cons : why large? Revolutionize our perspectives on the Universe. String theory probable quantum theory of gravity. BH production may overcome any future collider signatures. The favourite scenario: discovery of something unexpected

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 : gravitational waves give information on the bulk motion of matter in energetic processes (e.g. coalescence of black holes) high energy photons trace populations of accelerated particules, as well as dark matter annihilation protons provide information on the cosmic accelerators that have produced them neutrinos give information on the deepest zones, opaque to photons (e.g. on the origin --hadronic or electromagnetic-- of ). (*) Applies also to the primordial universe!