Beyond SM phase transi(ons in the early Universe and gravita(onal wave detec(on Pierre Binétruy, APPIC mee(ng APC, 9 May 2014 If gravitons were in thermal equilibrium in the primordial universe Ω = ρ-­‐1 dρ/dlogf γ g When do gravitons decouple? Interac(on rate Expansion rate 5 T
Γ~ GN2 T5 ~ -­‐-­‐-­‐-­‐ MPl4 T2 H ~ -­‐-­‐-­‐-­‐ MPl (radia(on dominated era) Γ T3 -­‐-­‐-­‐-­‐ ~ -­‐-­‐-­‐-­‐ H MPl3 Gravitons decouple at the Planck era : fossile radia(on Gravitons of frequency f* produced at temperature T* provide a background observed at a redshi[ed frequency 1 f = 1.65 10-­‐7 Hz -­‐-­‐-­‐ ε ( ) ( )
T* -­‐-­‐-­‐-­‐-­‐ 1GeV g* -­‐-­‐-­‐-­‐ 100 1/6 At produc(on λ* = ε H*-­‐1 (or f* = H*/ ε) Wavelength Horizon length The frequency spectrum of gravita(onal waves 1 Mkm The electroweak phase transi(on g* 1/6 1 ( -­‐T-­‐-­‐-­‐-­‐ * f = 1.65 10-­‐7 Hz -­‐-­‐-­‐ ) ( -­‐-­‐-­‐-­‐ ) ε 1GeV 100 for ε=1 ΩGW = ρc-­‐1 dρGW/d logf Gravitons produced at the electroweak phase transi(on would be observed in the LISA window. But are gravitons produced in sufficient numbers at the electroweak phase transi(on? If the transi(on is first order, nuclea(on of true vacuum bubbles inside the false vacuum Collision of bubbles and (MHD) turbulence → produc(on of gravita(onal waves Pros and cons for a 1st order phase transi(on 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 transi(on by including H6 terms in SM poten(al • other symmetries than SU(2)xU(1) at the Terascale (→ baryogenesis) Two basic parameters : h02 ΩGW Efalse vac α = -­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐ aT*4 β = (me varia(on of bubble nuclea(on rate radia(on energy at transi(on β-­‐1 ~ 10-­‐2 H-­‐1 dura(on of phase transi(on f in mHz Nicolis gr-­‐qc/0303084 turbulence bubble collision eLISA sens. A. Bohé, P.B., C. Caprini, J.F. Dufaux 1201.0983 A. Bohé, P.B., C. Caprini, J.F. Dufaux 1201.0983 VIRGO aVIRGO The frequency spectrum of gravita(onal waves 1 Mkm Planck with no running of nS Planck with running of nS allowed Planck + BICEP2 But only one wavelength: is the es(mate of the polarisa(on coming from dust adequate? Planck will tell. If r=0.2, Planck will confirm as well. Are these primordial gravita(onal waves? Could be unexpected foreground. See e.g. Liu, Mertsch, Sarkar 1404.1899 If it is the trace of primordial gravita(onal waves, what does it tell us about fundamental physics? First both expected and not expected: • Most theore(cal models predicted values of r much lower P.B., E. Kiritsis, J. Mabillard, M. Pieroni, C. Rosset • The non-­‐observa(on of non-­‐gaussiani(es conflicts many « realis(c » theore(cal models • For the simplest toy models, a generic predic(on is N number of e-­‐foldings nS-­‐1 ∼ O(1/N) dnS
/dlnk ∼ O(1/N2) r ∼ O(1/N) or r ∼ O(1/N2) Is this an argument for grand unifica(on? In the simplest models H ∼ 1.23 (r/0.2)1/2 1014 GeV ρ1/4 ∼ 2.26 (r/0.2)1/4 1016 GeV But: • It remains to be seen whether the simplest modesl work (do they explain the missing power at low l ?). • Is there a corresponding phase transi(on at 1016 GeV? The case of dark energy is not encouraging. Can we expect direct detec(on at higher frequencies? Can we expect direct detec(on at higher frequencies? ? eLISA LIGO/Virgo Cosmological horizon Horizon scale today Horizon scale early Universe Future of CMB study: probe deeper into infla(on scenarios (not easy!) In order to check infla(on and reconstruct the infla(on poten(al, need to check the « consistency » rela(on r = -­‐8nT and look at the scale dependence dns/dlnk,… Need to delense J. Carlstrom, CMB Stage IV, Talk at P5 2nd mee(ng