Singlet Assisted Electroweak Phase Transitions and Precision Higgs - - PowerPoint PPT Presentation

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Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies

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Probing EWPT with NextGen Colliders

Singlet Assisted Electroweak Phase Transitions and Precision Higgs Studies

Peter Winslow

PRD 91, 035018 (2015) (arXiv:1407.5342)

• S. Profumo, M. Ramsey-Musolf, C. Wainwright, P. Winslow

arXiv:1510.XXXX

Based on:

• A. Kotwal, J. M. No, M. Ramsey-Musolf, P. Winslow

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Probing EWPT with NextGen Colliders

Outline

Singlets: Collider Physics Cosmology The xSM: a Minimally Extended Scalar Sector 1st Order Phase Transitions: Electroweak Baryogenesis in the xSM NextGen Colliders: A motivation from Cosmology

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Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies

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Probing EWPT with NextGen Colliders

LHC has thrown open the door to the scalar sector of the SM! … but where’s all the NP?

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Probing EWPT with NextGen Colliders

tot

σ

• O) /

indirect

(O

• 3
• 2
• 1

1 2 3 )

2 Z

(M

(5) had

α ∆ )

2 Z

(M

s

α

t

m

b

R

c

R

0,b FB

A

0,c FB

A

b

A

c

A )

FB

(Q

lept eff

Θ

2

sin (SLD)

l

A (LEP)

l

A

0,l FB

A

lep

R

had

σ

Z

Γ

Z

M

W

Γ

W

M

H

M

Global EW fit Indirect determination Measurement

G fitter SM

Jul ’14

No obvious hints from CKM-ology or EWPO either…

Options:

à Heavy NP à Weakly coupled NP à Clever NP (compressed spectra, etc.) à Hidden Sectors / Singlets

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Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies

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Probing EWPT with NextGen Colliders

Singlets:

SM NP Higgs Portal

• Less constrained (possibly still weak scale)
• Typically still couple to SM via portals

à Interesting collider signatures

∆L ⊃ ONP |H|2

• Also motivated by real cosmological problems

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Probing EWPT with NextGen Colliders

Singlets:

• Higgs portals can modify character of EWPT

à Strongly 1st order EWPT à Highly motivated by EWBG

• Less constrained (possibly still weak scale)
• Typically still couple to SM via portals

à Interesting collider signatures

• Also motivated by real cosmological problems

à Matter/Antimatter Asymmetry Requirement of a SFOEWPT identifies a preferred parameter space à Cosmological motivation for collider searches

Electroweak Baryogenesis

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Probing EWPT with NextGen Colliders

The xSM: a useful toy model Higgs Mixing

• Set mh1 = 125 GeV
• h1 (h2) couplings to SM rescaled by cosθ (sinθ)

✓ h1 h2 ◆ = ✓ cos θ sin θ − sin θ cos θ ◆ ✓ h s ◆

• Singlet inherits SM couplings entirely from mixing

à searches for heavy scalars à EW precision observables

sin 2θ = (a1 + 2a2x0)v0 (m2

1 − m2 2)

VxSM(H, S) = VSM(H) + ⇣a1 2 S + a2 2 S2⌘ |H|2 | {z }

Higgs P ortal

+

Secluded Self−Interactions

z }| { b2 2 S2 + b3 3 S3 + b4 4 S4

H = ✓ G+

1 √ 2

• v0 + h + iG0

◆ , S = x0 + s

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Peter Winslow Singlet Assisted EWPTs and Precision Higgs Studies

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Probing EWPT with NextGen Colliders

Strong 1st order EWPTs in the xSM

Connecting to EWPT requires finite temperature effective potential Veff(φ, T) = V0(φ) + VCW (φ) + V T 6=0(φ, T) + V Ring-sum(φ, T)

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Probing EWPT with NextGen Colliders

Veff(φ, T) = V0(φ) + VCW (φ) + V T 6=0(φ, T) + V Ring-sum(φ, T) à Gauge dependent!! à Independence restored at high temperature

v(T)/ √ 2 = φ(T) cos α(T), x(T) = φ(T) sin α(T)

Veff(φ, α, T)xSM

High T

= ⇒ ¯ D(T 2 − T 2

0 )φ2 + eφ3 +

¯ λ 4 φ4 Condition for SFOEWPT SFOEWPT driven by tree-level parameters à à Classical transition Connecting to EWPT requires finite temperature effective potential

e = ✓a1 2 cos2 α + b3 3 sin2 α ◆ sin α ¯ λ = λ cos4 α + a2 2 cos2 α sin2 α + b4 4 sin4 α

cos α(Tc)∆φ(Tc) Tc & 1 = ⇒ − cos α(Tc) e 2Tc¯ λ & 1

JHEP 1107 (2011) 029

Strong 1st order EWPTs in the xSM

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Probing EWPT with NextGen Colliders

Condition for SFOEWPT

e = ✓a1 2 cos2 α + b3 3 sin2 α ◆ sin α ¯ λ = λ cos4 α + a2 2 cos2 α sin2 α + b4 4 sin4 α

cos α(Tc)∆φ(Tc) Tc & 1 = ⇒ − cos α(Tc) e 2Tc¯ λ & 1

Strong 1st order EWPTs in the xSM

General requirements for SFOEWPT:

• Large cos α(Tc)
• Large, negative a1

à Raises barrier

• linearly related to TC

à correlated with TC

λ λ

SFOEWPT driven by tree-level parameters à à Classical transition

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Probing EWPT with NextGen Colliders

Condition for SFOEWPT

e = ✓a1 2 cos2 α + b3 3 sin2 α ◆ sin α ¯ λ = λ cos4 α + a2 2 cos2 α sin2 α + b4 4 sin4 α

cos α(Tc)∆φ(Tc) Tc & 1 = ⇒ − cos α(Tc) e 2Tc¯ λ & 1 True value is slightly higher in xSM

PRD 90 (2014) 1, 015015

Strong 1st order EWPTs in the xSM

General requirements for SFOEWPT:

• Large cos α(Tc)
• Large, negative a1

à Raises barrier

• linearly related to TC

à correlated with TC

λ λ

SFOEWPT driven by tree-level parameters à à Classical transition

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Probing EWPT with NextGen Colliders

Possible collider signatures

Phenomenology depends largely on mass

m2 < 2 m1 à m2 > 2 m1 à m1/2 < m2 < 2 m1 à BSM Higgs-like decay modes Precision measurements Resonant di-Higgs(-like) production

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Possible collider signatures

Phenomenology depends largely on mass

Motivates precision measurements at future colliders

}

m2 < 2 m1 à m2 > 2 m1 à m1/2 < m2 < 2 m1 à BSM Higgs-like decay modes Precision measurements Resonant di-Higgs(-like) production

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Probing EWPT with NextGen Colliders

Possible collider signatures m2 < 2 m1 à m2 > 2 m1 à m1/2 < m2 < 2 m1 à What do we know from current LHC? What can we learn from future colliders? BSM Higgs-like decay modes Precision measurements Resonant di-Higgs(-like) production

In progress…

Phenomenology depends largely on mass

Motivates precision measurements at future colliders

}

Also, see Chien-Yi’s Talk!

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Probing EWPT with NextGen Colliders

Indirect Searches: Higgs-like coupling measurements

Fit to current data Sensitivity from projected uncertainties

0.85 0.90 0.95 1.00 100 150 200 250

• cosθ

m 2(GeV)

LHC: All 7-8 TeV data available HL-LHC: √s = 14 TeV, 3 ab-1

χ2(θ) = X

i

1 − cos2 θ ∆µproj

i

!2 χ2(θ) = X

i

✓µobs

i

− cos2 θ ∆µobs

i

◆2

ILC-1: √s = 250 GeV, 250 fb-1 ILC-3: √s = 1 TeV, 1 ab-1 TLEP: √s = 240 GeV, 1 ab-1

ATL-PHYS-PUB-2013-014, CMS-NOTE-13-002

ILC Higgs White Paper arXiv:1305.6498

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Indirect Searches: Oblique Parameters

∆O = cos2 θOSM(m1) + sin2 θOSM(m2) − OSM(m1) =

• 1 − cos2 θ

OSM(m2) − OSM(m1)

• Effects are simple to calculate

0.85 0.90 0.95 1.00 100 150 200 250

• cosθ

m 2(GeV)

∆χ2 = X

i,j

• ∆Oi − ∆O0

i

• σ2−1

ij

• ∆Oj − ∆O0

j

• Perform full fit to current best-fit

values from Gfitter O = S, T, U

• Eur. Phys. J. C 72, 2205 (2012)

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Probing EWPT with NextGen Colliders

Direct searches: Null results from SM-like Higgs searches

µXX = σ(m2) · BR(m2) σSM(m2) · BRSM(m2) = 1 − cos2 θ LEP Searches

0.85 0.90 0.95 1.00 100 150 200 250

• cosθ

m 2(GeV)

All h2-SM interactions rescaled by sinθ

• Phys. Lett. B 565, 61 (2003)

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Probing EWPT with NextGen Colliders

0.85 0.90 0.95 1.00 100 150 200 250

• cosθ

m 2(GeV)

LHC Searches à ATLAS-CMS Combination LEP Searches Higgs Discovery µXX = σ(m2) · BR(m2) σSM(m2) · BRSM(m2) = 1 − cos2 θ All h2-SM interactions rescaled by sinθ

Direct searches: Null results from SM-like Higgs searches

• Phys. Lett. B 565, 61 (2003)
• Phys. Lett. B 716, 1 (2012), Phys. Lett. B 716, 30 (2012)

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Probing EWPT with NextGen Colliders

0.85 0.90 0.95 1.00 100 150 200 250

• cosθ

m 2(GeV)

Dedicated heavy SM-like Higgs search à CMS All h2-SM interactions rescaled by sinθ µXX = σ(m2) · BR(m2) σSM(m2) · BRSM(m2) = 1 − cos2 θ LHC Searches à ATLAS-CMS Combination LEP Searches Higgs Discovery

Direct searches: Null results from SM-like Higgs searches

• Phys. Lett. B 565, 61 (2003)
• Phys. Lett. B 716, 1 (2012), Phys. Lett. B 716, 30 (2012)
• Eur. J. Phys. 73, 2469 (2013)

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Probing EWPT with NextGen Colliders

SFOEWPT Deviations from SM Higgs tri-linear coupling

Noble, Perelstein PRD 78 063518 (2008)

Direct Indirect

√s < 2 mh1 √s > 2 mh1 Direct Production Indirect Production

PRD 90 (2014) 1, 015001

Lepton Colliders Hadron Colliders

h0 h0 h0 h0

Model-dependent…

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Probing EWPT with NextGen Colliders

0.0 0.5 1.0 1.5 2.0 λh1 h1 h1/λSM

h1 h1 h1

% - %- %- %-

Projected sensitivity to Higgs-like tri-linear self-coupling

TLEP & CEPC: Direct (Indirect) HL-LHC: bbγγ, with bbW +W −, bbτ +τ −

PRD 90 (2014) 1, 015001 arXiv:1305.6498 arXiv:1308.6302, JHEP 1401, 164 (2014)

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Probing EWPT with NextGen Colliders

0.0 0.5 1.0 1.5 2.0 λh1 h1 h1/λSM

h1 h1 h1

% - %- %- %-

VHE-LHC or SPPC (100 TeV pp collider) ILC: e+e− → Zhh with e+e− → ννhh

ILC Higgs White Paper arXiv:1308.6302, JHEP 1401, 164 (2014)

Projected sensitivity to Higgs-like tri-linear self-coupling

1 TeV with 2.5/ab

100 TeV with 3/ab

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Probing EWPT with NextGen Colliders

0.0 0.5 1.0 1.5 2.0 λh1 h1 h1/λSM

h1 h1 h1

% - %- %- %-

VHE-LHC or SPPC (100 TeV pp collider) ILC: e+e− → Zhh with e+e− → ννhh

ILC Higgs White Paper arXiv:1308.6302, JHEP 1401, 164 (2014)

Projected sensitivity to Higgs-like tri-linear self-coupling

1 TeV with 2.5/ab

100 TeV with 3/ab

Revised to 100 TeV with 3/ab (30/ab): (~40%) ~10%

JHEP 1502, 016 (2015)

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Probing EWPT with NextGen Colliders

SFOEWPT-viable space is biased towards small mixing and large mass splitting.

• High precision Higgs-like

coupling measurements

Phenomenological Implications

Perform MC scans over xSM space Motivates:

• Searches for SM-like Higgs’

near di-Higgs threshold Require: Current Collider Constraints SFOEWPT Sufficient Tunnelling

CosmoTransitions

a1/TeV, b3/TeV ∈ [−1, 1], x0/TeV ∈ [0, 1], b4, λ ∈ [0, 1]

0.85 0.90 0.95 1.00 100 150 200 250

• cosθ

m 2(GeV)

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Probing EWPT with NextGen Colliders

Precision measurements of tri-linear Higgs self-coupling will be powerful probes of SFOEWPT-viable space!

Phenomenological Implications

Deviations for which correspond to strong quenching

• f sphalerons!

λh1h1h1 < λSM

h1h1h1

0.0 0.5 1.0 1.5 2.0 50 100 150 200 λh1 h1 h1/λSM

h1 h1 h1

TC

% - %- %- %-

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Probing EWPT with NextGen Colliders

h2 h1 h1

For higher singlet-like masses, h2 à h1h1 opens up à Resonantly enhanced di-Higgs production becomes possible

Assume in the resonance region à don’t account for box graphs Goal: Determine benchmark points, based on largest σ BR, which feature a SFOEWPT à Concentrate on ggF

What are discovery prospects for models which feature SFOEWPT? σLO(pp(gg) → h2) = sin2 θ σggF m2

2

dL dm2

2

λ211 = sin θ f(λ, x0, a1, b3, b4)

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Probing EWPT with NextGen Colliders

Higgs XSWG at 100 TeV

h2 h1 h1

For higher singlet-like masses, h2 à h1h1 opens up à Resonantly enhanced di-Higgs production becomes possible

Assume in the resonance region à don’t account for box graphs Goal: Determine benchmark points, based on largest σ BR, which feature a SFOEWPT à Concentrate on ggF

What are discovery prospects for models which feature SFOEWPT? σLO(pp(gg) → h2) = sin2 θ σggF m2

2

dL dm2

2

λ211 = sin θ f(λ, x0, a1, b3, b4)

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Probing EWPT with NextGen Colliders

h2 h1 h1

For higher singlet-like masses, h2 à h1h1 opens up à Resonantly enhanced di-Higgs production becomes possible

Assume in the resonance region à don’t account for box graphs Goal: Determine benchmark points, based on largest σ BR, which feature a SFOEWPT à Concentrate on ggF

What are discovery prospects for models which feature SFOEWPT?

BR(h2 → h1h1) = @1 + 8π sin2 θ m2ΓSM

h1 (m2)

λ2

211

q 1 − 4m2

1

m2

2

1 A

−1

λ211 = sin θ f(λ, x0, a1, b3, b4)

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Probing EWPT with NextGen Colliders

0.94 0.95 0.96 0.97 0.98 0.99 1.00 300 400 500 600 700 800 900 1000

• cosθ

m 2(GeV)

Preliminary

• 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

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Probing EWPT with NextGen Colliders

0.94 0.95 0.96 0.97 0.98 0.99 1.00 300 400 500 600 700 800 900 1000

• cosθ

m 2(GeV)

Preliminary

• 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

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Probing EWPT with NextGen Colliders

Conclusions

xSM: a simple framework linking EWPT dynamics to mixing phenomenology, allowing In both cases, SFOEWPT motivates next gen. colliders for the purposes of Should future experiments find evidence for

• EWPT-preferred parameter space to act as a guide for collider searches
• Precision collider measurements to act as a powerful probe of the EWPT
• High precision Higgs coupling measurements
• Direct searches for singlet-like scalars
• Non-zero Higgs mixing
• Deviations in
• Existence of a singlet-like scalar
• ur work will aid in narrowing down SFOEWPT-viable parameter space

λSM

h1h1h1

Thank you!

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Probing EWPT with NextGen Colliders

Orange Points: Satisfy Collider Bounds Black Points: Satisfy EWPT Backup Slides