Singlet Assisted Electroweak Phase Transitions and Precision Higgs Studies Peter Winslow Based on: PRD 91 , 035018 (2015) (arXiv:1407.5342) S. Profumo, M. Ramsey-Musolf, C. Wainwright, P. Winslow arXiv:1510.XXXX A. Kotwal, J. M. No, M. Ramsey-Musolf, P. Winslow Probing EWPT with 1/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Outline Singlets : Collider Physics Cosmology The xSM : a Minimally Extended Scalar Sector 1 st Order Phase Transitions: Electroweak Baryogenesis in the xSM NextGen Colliders: A motivation from Cosmology Probing EWPT with 2/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
LHC has thrown open the door to the scalar sector of the SM! … but where’s all the NP? Probing EWPT with 3/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
No obvious hints from CKM-ology or EWPO either … Global EW fit Indirect determination G fitter SM Jul ’14 Measurement M H M W Γ W M Z Γ Z 0 σ had 0 R lep 0,l A FB A (LEP) l A (SLD) l lept 2 sin (Q ) Θ eff FB A c A b 0,c A Options : FB 0,b A FB 0 R à Heavy NP c 0 R b à Weakly coupled NP m t 2 α (M ) s Z à Clever NP (compressed (5) 2 ∆ α (M ) had Z spectra, etc.) -3 -2 -1 0 1 2 3 (O - O) / σ à Hidden Sectors / Singlets tot indirect Probing EWPT with 4/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Singlets: - Less constrained (possibly still weak scale) SM NP - Typically still couple to SM via portals à Interesting collider signatures Higgs Portal - Also motivated by real cosmological problems ∆ L ⊃ O NP | H | 2 Probing EWPT with 5/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Singlets: - Less constrained (possibly still weak scale) Electroweak Baryogenesis - Typically still couple to SM via portals à Interesting collider signatures - Also motivated by real cosmological problems à Matter/Antimatter Asymmetry - Higgs portals can modify character of EWPT à Strongly 1 st order EWPT à Highly motivated by EWBG Requirement of a SFOEWPT identifies a preferred parameter space à Cosmological motivation for collider searches Probing EWPT with 6/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
The xSM: a useful toy model Secluded Self − Interactions z }| { ⇣ a 1 2 S 2 ⌘ 2 S + a 2 b 2 2 S 2 + b 3 3 S 3 + b 4 | H | 2 4 S 4 V xSM ( H, S ) = V SM ( H ) + + | {z } Higgs P ortal G + ✓ ◆ H = , S = x 0 + s 1 � v 0 + h + iG 0 � √ 2 Higgs Mixing ✓ ◆ ✓ ◆ ✓ ◆ cos θ sin θ h 1 h = sin 2 θ = ( a 1 + 2 a 2 x 0 ) v 0 h 2 − sin θ cos θ s ( m 2 1 − m 2 2 ) - Set m h1 = 125 GeV - h 1 (h 2 ) couplings to SM rescaled by cos θ (sin θ ) - Singlet inherits SM couplings entirely from mixing à searches for heavy scalars à EW precision observables Probing EWPT with 7/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Strong 1 st order EWPTs in the xSM Connecting to EWPT requires finite temperature effective potential V eff ( φ , T ) = V 0 ( φ ) + V CW ( φ ) + V T 6 =0 ( φ , T ) + V Ring-sum ( φ , T ) Probing EWPT with 8/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Strong 1 st order EWPTs in the xSM Connecting to EWPT requires finite temperature effective potential V eff ( φ , T ) = V 0 ( φ ) + V CW ( φ ) + V T 6 =0 ( φ , T ) + V Ring-sum ( φ , T ) à Gauge dependent!! JHEP 1107 (2011) 029 à Independence restored at high temperature ¯ λ 0 ) φ 2 + e φ 3 + High T ¯ D ( T 2 − T 2 V eff ( φ , α , T ) xSM 4 φ 4 = ⇒ √ v ( T ) / 2 = φ ( T ) cos α ( T ) , x ( T ) = φ ( T ) sin α ( T ) SFOEWPT driven by tree-level parameters Condition for SFOEWPT à à Classical transition cos α ( T c ) ∆ φ ( T c ) ✓ a 1 ◆ 2 cos 2 α + b 3 & 1 3 sin 2 α e = sin α T c e λ = λ cos 4 α + a 2 2 cos 2 α sin 2 α + b 4 = ⇒ − cos α ( T c ) λ & 1 4 sin 4 α ¯ 2 T c ¯ Probing EWPT with 9/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Strong 1 st order EWPTs in the xSM General requirements for SFOEWPT: - Large cos α ( T c ) - Large, negative a 1 - linearly related to T C λ à Raises barrier à correlated with T C λ SFOEWPT driven by tree-level parameters Condition for SFOEWPT à à Classical transition cos α ( T c ) ∆ φ ( T c ) ✓ a 1 ◆ 2 cos 2 α + b 3 & 1 3 sin 2 α e = sin α T c e λ = λ cos 4 α + a 2 2 cos 2 α sin 2 α + b 4 = ⇒ − cos α ( T c ) λ & 1 4 sin 4 α ¯ 2 T c ¯ Probing EWPT with 10/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Strong 1 st order EWPTs in the xSM General requirements for SFOEWPT: - Large cos α ( T c ) - Large, negative a 1 - linearly related to T C λ à Raises barrier à correlated with T C λ True value is slightly higher in xSM PRD 90 (2014) 1, 015015 SFOEWPT driven by tree-level parameters Condition for SFOEWPT à à Classical transition cos α ( T c ) ∆ φ ( T c ) ✓ a 1 ◆ 2 cos 2 α + b 3 & 1 3 sin 2 α e = sin α T c e λ = λ cos 4 α + a 2 2 cos 2 α sin 2 α + b 4 = ⇒ − cos α ( T c ) λ & 1 4 sin 4 α ¯ 2 T c ¯ Probing EWPT with 11/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Phenomenology depends largely on mass Possible collider signatures m 2 < 2 m 1 à BSM Higgs-like decay modes m 1 /2 < m 2 < 2 m 1 à Precision measurements m 2 > 2 m 1 à Resonant di-Higgs(-like) production Probing EWPT with 12/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Phenomenology depends largely on mass Possible collider signatures } m 2 < 2 m 1 à BSM Higgs-like decay modes Motivates precision m 1 /2 < m 2 < 2 m 1 à Precision measurements measurements at future colliders m 2 > 2 m 1 à Resonant di-Higgs(-like) production Probing EWPT with 13/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Phenomenology depends largely on mass Possible collider signatures } m 2 < 2 m 1 à BSM Higgs-like decay modes Motivates precision m 1 /2 < m 2 < 2 m 1 à Precision measurements measurements at future colliders m 2 > 2 m 1 à Resonant di-Higgs(-like) production In progress … Also, see Chien-Yi’s Talk! What do we know from current LHC? What can we learn from future colliders? Probing EWPT with 14/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Indirect Searches: Higgs-like coupling measurements Fit to current data Sensitivity from projected uncertainties ! 2 1 − cos 2 θ − cos 2 θ ◆ 2 ✓ µ obs X X χ 2 ( θ ) = χ 2 ( θ ) = i ∆ µ proj ∆ µ obs i i i i �� - ��� LHC: ��� - � ��� - � ���� ��� All 7-8 TeV data available 250 HL-LHC: √ s = 14 TeV, 3 ab -1 ATL-PHYS-PUB-2013-014, CMS-NOTE-13-002 200 m 2 ( GeV ) ILC-1: √ s = 250 GeV, 250 fb -1 150 ILC-3: √ s = 1 TeV, 1 ab -1 100 ILC Higgs White Paper TLEP: 0.85 0.90 0.95 1.00 √ s = 240 GeV, 1 ab -1 cos θ arXiv:1305.6498 Probing EWPT with 15/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Indirect Searches: Oblique Parameters Effects are simple to calculate ∆ O = cos 2 θ O SM ( m 1 ) + sin 2 θ O SM ( m 2 ) − O SM ( m 1 ) O = S, T, U 1 − cos 2 θ O SM ( m 2 ) − O SM ( m 1 ) � � � � = �� - ��� ��� - � ��� - � ���� ��� 250 Perform full fit to current best-fit values from Gfitter 200 m 2 ( GeV ) σ 2 � − 1 X ∆ χ 2 = ∆ O i − ∆ O 0 ∆ O j − ∆ O 0 � �� � � i j ij 150 i,j Eur. Phys. J. C 72 , 2205 (2012) 100 0.85 0.90 0.95 1.00 cos θ Probing EWPT with 16/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Direct searches: Null results from SM-like Higgs searches All h 2 -SM interactions rescaled by sin θ σ ( m 2 ) · BR( m 2 ) = 1 − cos 2 θ µ XX = σ SM ( m 2 ) · BR SM ( m 2 ) �� - ��� ��� - � ��� - � ���� ��� 250 LEP Searches 200 Phys. Lett. B 565 , 61 (2003) m 2 ( GeV ) 150 100 0.85 0.90 0.95 1.00 cos θ Probing EWPT with 17/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
Direct searches: Null results from SM-like Higgs searches All h 2 -SM interactions rescaled by sin θ σ ( m 2 ) · BR( m 2 ) = 1 − cos 2 θ µ XX = σ SM ( m 2 ) · BR SM ( m 2 ) �� - ��� Higgs Discovery ��� - � ��� - � ���� ��� 250 LEP Searches 200 Phys. Lett. B 565 , 61 (2003) m 2 ( GeV ) LHC Searches 150 à ATLAS-CMS Combination Phys. Lett. B 716 , 1 (2012), Phys. Lett. B 716 , 30 (2012) 100 0.85 0.90 0.95 1.00 cos θ Probing EWPT with 18/31 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies NextGen Colliders
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