Higgs Cosmology and dark matter. Ian Moss Newcastle University July 2018

Transcription

1 Higgs Cosmology and dark matter Ian Moss Newcastle University July 2018

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5 HIGGS AROUND GEV. Higgs Instability

6 Your theory is crazy, the question is whether it's crazy enough to be true. Bohr to Pauli

7 Contents Vacuum stability Present day Vacuum decay Early universe vacuum decay

8 Vacuum Stability Quantum contribution to the Higgs potential V vac = X b 1 2 ~! b X f 1 2 ~! f Frequencies depend on the particle mass! =(k 2 + M 2 2 /v 2 ) 1/2 v = 246GeV The effect on the Higgs potential can be summarised by an effective coupling. Krive & Linde Nucl. Phys. B117 (1976) 265, old review by Sher.

9 Higgs self-coupling V e = 1 4 e ( ) 4 Interaction strength λ eff m t =173.4 GeV H (GeV)

10 Stability regions* O(~ 2 ) The potential depends on the Higgs and Top mass V e = 1 4 e ( ) 4 where d e d ln = 4 e *Degrassi et al arxiv:

11 The metastable state can only decay by tunnelling 100 one-loop result for M t =172 GeV logarithmic fit V eff ( GeV ) φ (GeV) τ false vacuum O(4) symmetry Vacuum decay proceeds by the nucleation of bubbles Decay rate = Ae B B = S E [ b] S E [ fv] A = det0 S 00 E [ b] det S 00 E [ fv] 1/2 B Coleman, Phys Rev D

12 Bubble solution y φ(mp) x I = 1363

13 Seeded nucleation Most supercooled phase transitions are nucleated by impurities and imperfections. Hiscock, Phys Rev D ; Burda, Gregory, Moss, ,

14 Black hole seeds Primordial microscopic black holes: produced in the early universe? small ones evaporate, lose mass and eventually explode;

15 true vacuum seed remnant Philipp Burda, Ruth Gregory, IGM, , , Ongoing work with Kate Marshal and Leo Cuspinera

16 Static bubbles dominate. I is now the difference in action between the bubble and the false vacuum black hole. Amazingly simple result: I = 1 4G A 1 seed 4G A remnant S where A = 16 M 2 is the area of the event horizon. Tunnelling rate given by Einsteins formula e S

17 Comparison of vacuum decay rates and evaporation rates λ * = 0.02 λ * = λ * = 0.01 λ * = λ * = Γ D Γ H seed mass M + M p Seeded nucleation with V ( )= 1 4 { + b(ln( / ) 2 } 4

18 There is observational evidence that the false vacuum has not decayed by seeded nucleation. Standard model + microscopic black holes that can decay in the lifetime of the universe ruled out Even a single black hole of mass is not allowed g

19 Vacuum decay in the lab

20 Vacuum decay in the lab BEC, two atomic levels 1&2 with wave functions 1 = (1 + 2 )ei'/2 2 = (1 2 )e i'/ V V s relative phase ϕ Still just a proposal Fialko et al., , Braden et al

21 Seeded vacuum decay in the lab 2D system with vortices true vacuum vortex Tom Billam, Florent Michel, Ruth Gregory & IGM

22 Seeded vacuum decay in the lab Tunnelling Exponent without vortex with vortex Energy Difference ε 2 t t r r 0 phase

23 Vacuum decay in the early universe Standard Model General Relativity Inflaton

24 Higgs stability during inflation when the Higgs and the inflaton are distinct L = 1 2 M 2 p R 1 2 R (r )2 V (, ) 1. De Sitter vacuum fluctuations can destabilise the Higgs H 2. The curvature coupling can stabilise/ destabilise the Higgs during inflation. 3. The Higgs can seed large fluctuations

25 Higgs potential Curvature and inflation couplings: L e = 1 4 e ( ) e ( )R g e ( ) R is related to the expansion rate during inflation H Stability depends on e ( ), g e ( ), H Espinosa et al , Herranen et al , Bounakis & IGM

26 What exactly is the metric? Make a field redefinition to the Einstein frame g E = 1 2 /M 2 p g V E ( )= V ( ) (1 2 /M 2 p ) 2 This mixes up e ( ), g e ( ) The physics should be covariant under such field redefinitions Bounakis & IGM

27 Effects on vacuum decay = Ae B m t =173.4 GeV m t =173.0 GeV Higgs decay Higgs decay H (GeV) 10 9 H (GeV) ξ (170GeV) B = 10 B = 60 B = ξ (170GeV) B = 10 B = 60 B = 180

28 Higgs fluctuations Light field in de Sitter: can treat the quantum evolution through the barrier stochastically Subsequent evolution of the Higgs gives fluctuations h H2 (tk ) H2 (tk ) These can form primordial black holes with mass / g (dark matter candidates). Rather fine tuned Espinosa et al , , Rigopoulos & IGM

29 Summary Microscopic black holes seed very rapid vacuum decay in a metastable theory. Vacuum decay may be testable in the lab The Higgs may be an active spectator during inflation Philipp Burda and Ruth Gregory, , , Ongoing work with Kate Marshal, Leo Cuspinera and Michel Florent with Marios Bounakis

30 The End