Searches for new vacua II: A new higgstory at the cosmological - PowerPoint PPT Presentation

Searches for new vacua II: A new higgstory at the cosmological collider Junwu Huang Perimeter Institute Aug, 2019 1904.00020 , 1907.10624 , 1908.00019 Anson Hook, Junwu Huang, Davide Racco

Leaving no stones unturned! • EW hierarchy problem & CC problem • Symmetry + Naturalness • Landscape/Multiverse + Anthropics (Credit: Giovanni Villadoro)

Multiverse • “…knowing that it could be out there is itself very important information” (Nima or Savas) • Weinberg CC One step further: • String Axiverse see a new minimum! 0905.4720 • Split Supersymmetry hep-ph/0406088, hep-ph/0409232,1210.0555 • How can we directly look for a minimum? • Local bubbles • High scale higgs minimum

Multiverse • “…knowing that it could be out there is itself very important information” (Nima or Savas) • Weinberg CC • String Axiverse • Split Supersymmetry • How can we directly look for a minimum? • Go far away: Local bubbles Anson Hook, JH , arXiv:1904.00020 • Go back into the past: High scale higgs minimum

Outline • The higgstory • The tale of SM fermions • Result and remarks • A lower risk lower reward signal Anson Hook, JH , Davide Racco arXiv:1908.00019

A new Higgstory

Higgs instability (Brief) V ( h ) • Higgs instability 1505.04825 λ h < 0@ v λ =0 ∼ 10 11 GeV v ew v uv • Higgs quartic h v λ =0 • The EW minimum v EW is meta-stable T = 0 H ≲ 6 × 10 13 GeV • During inflation ( ), Higgs could leave EW minimum. • What does Higgs instability + High scale inflation imply? • New physics at low energy scales? • New coupling of Higgs to Hubble/Inflaton? • Can we be in a high scale Higgs minimum all along?

Higgs instability (Implications) V ( h ) • Higgs instability 1505.04825 λ h < 0@ v λ =0 ∼ 10 11 GeV v ew v uv • Higgs quartic h v λ =0 • The EW minimum v EW is meta-stable T = 0 H ≲ 6 × 10 13 GeV • During inflation ( ), Higgs could leave EW minimum. • What does Higgs instability + High scale inflation imply? • New physics at low energy scales? • New coupling of Higgs to Hubble/Inflaton? • Can we be in a high scale Higgs minimum all along?

A new Higgstory V ( h ) • During inflation • Higgs fluctuate over and roll to the UV minimum. v λ =0 v ew v uv h v λ =0 • Stay there the whole time when v UV > H T = 0 H • Require : Stringy/GUT contribution stabilize runaway direction V ( h ) • After inflation: T = T max • Thermal contribution lift the UV minimum v ew v uv h v λ =0 • The Higgs rolls back and decays through scattering with background SM radiation T = 0 • Require : Reheat to temperatures T max > v UV

A new Higgstory V ( h ) • During inflation • Higgs fluctuate over and roll to the UV minimum. v λ =0 v ew v uv h v λ =0 • Stay there the whole time when v UV > H T = 0 H • Require : Stringy/GUT contribution stabilize runaway direction V ( h ) • After inflation: T = T max • Thermal contribution lift the UV minimum v ew v uv h v λ =0 • The Higgs rolls back and decays through scattering with background SM radiation T = 0 • Require : Reheat to temperatures T max > v UV

Summary: parameter space 10 15 10 14 Bound on r • White: The higgstory of 10 13 No instability at + 2 � in m t In all of the No instability at 0 � in m t this talk. 10 12 white region, • Green: See our story 10 11 Anson Hook, would apply. 10 10 JH , Davide V � + V h < 0 T RH < v UV Racco 10 9 1908.00019 10 8 10 7 10 9 10 10 10 11 10 12 10 13 10 14 10 15 10 16

Summary: parameter space • White: Focus of this talk. • Green: Anson Hook, JH , Davide Racco 1908.00019 • Blue: update to account for fluctuations of the Higgs

Cosmological collider of SM fermions

Non-Gaussianity (Brief) • Non-gaussianity: τ = 0 k 2 k 1 k 3 ⌧ k 1 0 k 2 • Cosmological collider ( δφ ) 3 1503.08043 • Cosmological collider physics concerns the case where there are intermediate massive particles • Massive particle redshifts differently • and lead to oscillating shapes in the squeezed limit ( k 3 < k 2 ∼ k 1 )

Cosmological collider (Brief) • Non-gaussianity: τ = 0 k 2 k 1 k 3 ⌧ k 1 0 k 2 • Cosmological collider ( δφ ) 3 1503.08043 • Cosmological collider physics τ = 0 concerns the case where there are k 2 intermediate massive particles k 1 • Massive particle redshifts differently k 3 ⌧ k 1 0 k 2 m/H • and lead to oscillating shapes in the squeezed limit ( k 3 < k 2 ∼ k 1 ) ( δφ ) 3

Using SM Fermions • Why fermions? • SM fermion masses scan many order of magnitude • Fermions have no hierarchy problem • Fermions enhance EW symmetry breaking Anson Hook, JH , Davide Racco, arXiv:1908.00019 • How to use SM fermions? τ = 0 δφ δφ k 2 k 1 • Couple them to inflaton (shift symmetric): τ 1 τ 2 f δφ k 3 ⌧ k 1 0 k 2 f f 1805.02656 τ 3

τ = 0 A fermion story δφ δφ k 2 k 1 τ 1 τ 2 f δφ k 3 ⌧ k 1 0 k 2 • Fermion dispersion relation (small Hubble) f f • Rolling inflaton ( ) breaks Lorentz Symmetry τ 3 • Fermion production ( ) ( ω ∼ m , k ∼ ± λ ) • Fermion mode: • Production rate: • Effective density: • Fermion redshift • Fermion annihilation

τ = 0 A fermion story δφ δφ k 2 k 1 τ 1 τ 2 f δφ k 3 ⌧ k 1 0 k 2 f f • Fermion dispersion relation τ 3 • Fermion production ( ) Non-adiabatic particle ( ω ∼ m , k ∼ ± λ ) • Fermion mode: production • Production rate: • Effective density: • Fermion redshift • Fermion annihilation

A fermion story • Fermion dispersion relation: τ = 0 • Fermion production δφ δφ k 2 k 1 τ 1 τ 2 f • Fermion redshift: δφ k 3 ⌧ k 1 0 k 2 f ( ω ∼ m , k ∼ λ ) ( ω ∼ λ , k ∼ 0 ) f • From to • sets oscillation frequency τ 3 ω ∼ λ • Fermion annihilation ( ω ∼ λ , k ∼ 0 ) • Fermions can only pair annihilate ( k 2 ∼ k 1 ∼ ω ( τ 1 ) ∼ λ )

Results & implications

Signal strength 0.1 0.2 0.3 0.4 0.5 10 7 • Signal from a fermion loop: • Shape: 10 6 10 5 • Amplitude: • 10 4 10 3 10 2 0 10 20 30 40

Signal strength • Signal from a fermion loop: 0.1 0.2 0.3 0.4 0.5 10 7 • Shape: 10 6 10 5 • Two limits { when when 10 4 10 3 10 2 0 10 20 30 40

Signal strength 0.1 0.2 0.3 0.4 0.5 10 7 10 6 Take home: 10 5 1. SM fermions scan Hubble 2. Multiple SM fermions can be observed together 10 4 10 3 10 2 0 10 20 30 40

Distinguishing the signal • How to distinguish the signal: • Amplitude (f NL ) and frequency -> Mass (m/H) & Coupling ( λ /H) 0.1 0.2 0.3 0.4 0.5 10 7 • Two/multiple fermions: 10 6 • Ratio of fermion masses: 10 5 • Implications: 10 4 10 3 • A new minimum! 10 2 0 10 20 30 40 • New probe of GUT, string theories… • No two Higgs doublet, no new coloured states…

Implications • How to distinguish the signal: • Amplitude (f NL ) and frequency -> Mass (m/H) & Coupling ( λ /H) • Two/multiple fermions: • Ratio of fermion masses: We can look for the • Implications: landscape, directly! • A new minimum! • UV: New probe of GUT, string theories… • IR: No two Higgs doublets, no many new coloured states…

Does one new minimum hint multiverse? Would a few of them convince you? 不识庐⼭真⾯⽬ 只缘⾝在此⼭中 — 苏轼 Why can’t I tell the true shape of Lu-shan? Because I myself am in the mountain. —Shi Su