« 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