Singlet Assisted Electroweak Phase Transitions and Precision Higgs Studies

Transcription

1 Singlet Assisted Electroweak Phase Transitions and Precision Higgs Studies Peter Winslow Based on: PRD 91, (2015) (arxiv: ) S. Profumo, M. Ramsey-Musolf, C. Wainwright, P. Winslow arxiv:1510.xxxx A. Kotwal, J. M. No, M. Ramsey-Musolf, P. Winslow Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 1/31

2 Outline Singlets: Collider Physics Cosmology The xsm: a Minimally Extended Scalar Sector 1 st Order Phase Transitions: Electroweak Baryogenesis in the xsm : A motivation from Cosmology Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 2/31

3 LHC has thrown open the door to the scalar sector of the SM! but where s all the NP? Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 3/31

4 No obvious hints from CKM-ology or EWPO either Global EW fit Indirect determination Measurement G fitter SM Jul 14 M H M W Γ W M Z Γ Z 0 σ had 0 Rlep 0,l A FB A l (LEP) A l (SLD) 2 lept sin Θ eff (Q ) FB A c Options: à Heavy NP à Weakly coupled NP à Clever NP (compressed spectra, etc.) à Hidden Sectors / Singlets 2 α s (M ) (5) α had A b 0,c A FB 0,b A FB 0 Rc 0 Rb m t Z 2 (M ) Z O) / (O indirect σ tot Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 4/31

5 Singlets: - Less constrained (possibly still weak scale) - Typically still couple to SM via portals à Interesting collider signatures - Also motivated by real cosmological problems SM Higgs Portal L O NP H 2 NP Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 5/31

6 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 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 6/31

7 The xsm: a useful toy model V xsm (H, S) =V SM (H)+ Higgs Mixing h1 h 2 = cos sin sin cos - Set m h1 = 125 GeV a1 2 S + a 2 2 S2 H 2 {z } h s Higgs Portal - h 1 (h 2 ) couplings to SM rescaled by cosθ (sinθ) - Singlet inherits SM couplings entirely from mixing à searches for heavy scalars à EW precision observables H = sin 2 = (a 1 +2a 2 x 0 )v 0 (m 2 1 m 2 2 ) Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 7/31 + Secluded Self Interactions z } { b 2 2 S2 + b 3 3 S3 + b 4 4 S4 p1 2 v 0 + h + ig 0 G +, S = x 0 + s

8 Strong 1 st order EWPTs in the xsm Connecting to EWPT requires finite temperature effective potential V eff (, T )=V 0 ( )+V CW ( )+V T 6=0 (, T )+V Ring-sum (, T ) Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 8/31

9 Strong 1 st order EWPTs in the xsm Connecting to EWPT requires finite temperature effective potential V eff (, T )=V 0 ( )+V CW ( )+V T 6=0 (, T )+V Ring-sum (, T ) à Gauge dependent!! JHEP 1107 (2011) 029 à Independence restored at high temperature V eff (,, T ) xsm High =) T D(T 2 T0 2 ) 2 + e v(t )/ p 2= (T ) cos (T ), x(t )= (T )sin (T ) 4 Condition for SFOEWPT (T c ) cos (T c ) & 1 T c e =) cos (T c ) 2T c & 1 SFOEWPT driven by tree-level parameters à Classical transition Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 9/31 e = a1 2 cos2 + b 3 3 sin2 sin = cos 4 + a 2 2 cos2 sin 2 + b 4 4 sin4

10 Strong 1 st order EWPTs in the xsm General requirements for SFOEWPT: - Large cos (T c ) - Large, negative a 1 à Raises barrier - linearly related to T C à correlated with T C Condition for SFOEWPT (T c ) cos (T c ) & 1 T c e =) cos (T c ) 2T c & 1 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 10/31 e = SFOEWPT driven by tree-level parameters à Classical transition a1 2 cos2 + b 3 3 sin2 sin = cos 4 + a 2 2 cos2 sin 2 + b 4 4 sin4

11 Strong 1 st order EWPTs in the xsm General requirements for SFOEWPT: - Large cos (T c ) - Large, negative a 1 à Raises barrier - linearly related to T C à correlated with T C True value is slightly higher in xsm PRD 90 (2014) 1, Condition for SFOEWPT (T c ) cos (T c ) & 1 T c e =) cos (T c ) 2T c & 1 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 11/31 e = SFOEWPT driven by tree-level parameters à Classical transition a1 2 cos2 + b 3 3 sin2 sin = cos 4 + a 2 2 cos2 sin 2 + b 4 4 sin4

12 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 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 12/31

13 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 Motivates precision measurements at future }colliders m 2 > 2 m 1 à Resonant di-higgs(-like) production Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 13/31

14 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 Motivates precision 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? Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 14/31

15 Indirect Searches: Higgs-like coupling measurements Fit to current data 2 ( ) = X i µ obs i cos 2 µ obs i 2 Sensitivity from projected uncertainties 2 ( ) = X i 1 cos 2 µ proj i! 2 LHC: All 7-8 TeV data available HL-LHC: s = 14 TeV, 3 ab ATL-PHYS-PUB , CMS-NOTE ILC-1: s = 250 GeV, 250 fb -1 ILC-3: s = 1 TeV, 1 ab -1 ILC Higgs White Paper m 2(GeV) TLEP: s = 240 GeV, 1 ab -1 arxiv: cosθ Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 15/31

16 Indirect Searches: Oblique Parameters Effects are simple to calculate O = cos 2 O SM (m 1 )+sin 2 O SM (m 2 ) O SM (m 1 ) = 1 cos 2 O SM (m 2 ) O SM (m 1 ) O = S, T, U Perform full fit to current best-fit values from Gfitter = X i,j O i O 0 i 2 1 ij O j O 0 j Eur. Phys. J. C 72, 2205 (2012) m 2(GeV) cosθ Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 16/31

17 Direct searches: Null results from SM-like Higgs searches All h 2 -SM interactions rescaled by sinθ µ XX = (m 2 ) BR(m 2 ) SM (m 2 ) BR SM (m 2 ) =1 cos LEP Searches Phys. Lett. B 565, 61 (2003) m 2(GeV) cosθ Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 17/31

18 Direct searches: Null results from SM-like Higgs searches All h 2 -SM interactions rescaled by sinθ µ XX = (m 2 ) BR(m 2 ) SM (m 2 ) BR SM (m 2 ) =1 cos2 Higgs Discovery LEP Searches Phys. Lett. B 565, 61 (2003) LHC Searches à ATLAS-CMS Combination Phys. Lett. B 716, 1 (2012), Phys. Lett. B 716, 30 (2012) m 2(GeV) cosθ Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 18/31

19 Direct searches: Null results from SM-like Higgs searches All h 2 -SM interactions rescaled by sinθ µ XX = (m 2 ) BR(m 2 ) SM (m 2 ) BR SM (m 2 ) =1 cos2 LEP Searches Higgs Discovery Phys. Lett. B 565, 61 (2003) LHC Searches à ATLAS-CMS Combination Phys. Lett. B 716, 1 (2012), Phys. Lett. B 716, 30 (2012) Dedicated heavy SM-like Higgs search à CMS Eur. J. Phys. 73, 2469 (2013) m 2(GeV) Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 19/ cosθ - - -

20 SFOEWPT Lepton Colliders Deviations from SM Higgs tri-linear coupling Noble, Perelstein PRD (2008) Model-dependent p s>2 mh1 p s<2 mh1 Direct Indirect Direct Production Indirect Production PRD 90 (2014) 1, Hadron Colliders h 0 h 0 h 0 h 0 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 20/31

21 Projected sensitivity to Higgs-like tri-linear self-coupling TLEP & CEPC: Direct (Indirect) - % %- %- %- arxiv: , JHEP 1401, 164 (2014) HL-LHC: bb, with bbw + W,bb + PRD 90 (2014) 1, arxiv: λ h1 h 1 h 1 /λ SM h 1 h 1 h 1 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 21/31

22 Projected sensitivity to Higgs-like tri-linear self-coupling ILC: e + e with e + e 1 TeV with 2.5/ab! Zhh! hh - % %- %- %- VHE-LHC or SPPC (100 TeV pp collider) arxiv: , JHEP 1401, 164 (2014) 100 TeV with 3/ab ILC Higgs White Paper λ h1 h 1 h 1 /λ SM h 1 h 1 h 1 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 22/31

23 Projected sensitivity to Higgs-like tri-linear self-coupling Revised to 100 TeV with 3/ab (30/ab): (~40%) ~10% JHEP 1502, 016 (2015) ILC: e + e with e + e 1 TeV with 2.5/ab! Zhh! hh - % %- %- %- VHE-LHC or SPPC (100 TeV pp collider) arxiv: , JHEP 1401, 164 (2014) 100 TeV with 3/ab ILC Higgs White Paper λ h1 h 1 h 1 /λ SM h 1 h 1 h 1 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 23/31

24 Perform MC scans over xsm space Phenomenological Implications a 1 /TeV,b 3 /TeV 2 [ 1, 1], x 0 /TeV 2 [0, 1], b 4, 2 [0, 1] Require: Current Collider Constraints SFOEWPT Sufficient Tunnelling CosmoTransitions SFOEWPT-viable space is biased towards small mixing and large mass splitting. Motivates: - High precision Higgs-like coupling measurements m 2(GeV) Searches for SM-like Higgs near di-higgs threshold cosθ Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 24/31

25 Phenomenological Implications Deviations for which of sphalerons! h 1 h 1 h 1 < SM h 1 h 1 h 1 correspond to strong quenching Precision measurements of tri-linear Higgs self-coupling will be powerful probes of SFOEWPT-viable space! TC % %- %- % λ h1 h 1 h 1 /λ SM h 1 h 1 h 1 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 25/31

26 For higher singlet-like masses, h 2 à h 1 h 1 opens up à Resonantly enhanced di-higgs production becomes possible What are discovery prospects for models which feature SFOEWPT? Assume in the resonance region à don t account for box graphs h 2 h 1 h =sin f(, x 0,a 1,b 3,b 4 ) Goal: Determine benchmark points, based on largest σ BR, which feature a SFOEWPT à Concentrate on ggf LO(pp(gg)! h 2 )=sin 2 ggf 0 m 2 2 dl dm 2 2 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 26/31

27 For higher singlet-like masses, h 2 à h 1 h 1 opens up à Resonantly enhanced di-higgs production becomes possible What are discovery prospects for models which feature SFOEWPT? Assume in the resonance region à don t account for box graphs h 2 h 1 h =sin f(, x 0,a 1,b 3,b 4 ) Goal: Determine benchmark points, based on largest σ BR, which feature a SFOEWPT à Concentrate on ggf LO(pp(gg)! h 2 )=sin 2 ggf 0 m 2 2 dl dm 2 2 Higgs XSWG at 100 TeV Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 27/31

28 For higher singlet-like masses, h 2 à h 1 h 1 opens up à Resonantly enhanced di-higgs production becomes possible What are discovery prospects for models which feature SFOEWPT? Assume in the resonance region à don t account for box graphs h 2 h 1 h =sin f(, x 0,a 1,b 3,b 4 ) Goal: Determine benchmark points, based on largest σ BR, which feature a SFOEWPT à Concentrate on ggf BR(h 2! h 1 h 1 )=@1+ 8 sin2 SM m 2 h1 (m 2 ) q A 1 Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 28/ m 2 1 m 2 2

29 Preliminary m 2(GeV) - Simulate events with MG5 + Pythia8 - Choose final states based on BG suppression à bbyy, 4τ, ττyy have smaller σ s but cleaner signatures à 100 TeV collider may yield substantial # of events - For each final state: - Combine distributions - Use BDT algorithm to separate signal from BG cosθ Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 29/31

30 Preliminary m 2(GeV) - Simulate events with MG5 + Pythia8 - Choose final states based on BG suppression à bbyy, 4τ, ττyy have smaller σ s but cleaner signatures à 100 TeV collider may yield substantial # of events - For each final state: - Combine distributions - Use BDT algorithm to separate signal from BG cosθ Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 30/31

31 Conclusions xsm: a simple framework linking EWPT dynamics to mixing phenomenology, allowing - EWPT-preferred parameter space to act as a guide for collider searches - Precision collider measurements to act as a powerful probe of the EWPT In both cases, SFOEWPT motivates next gen. colliders for the purposes of - High precision Higgs coupling measurements - Direct searches for singlet-like scalars Should future experiments find evidence for - Non-zero Higgs mixing - Existence of a singlet-like scalar - Deviations in SM h 1 h 1 h 1 our work will aid in narrowing down SFOEWPT-viable parameter space Thank you! Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 31/31

32 Backup Slides Orange Points: Satisfy Collider Bounds Black Points: Satisfy EWPT Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies 32/31