BARYOGENESIS FROM WIMPS Y. Cui, L. Randall, and BS, arXiv:1112.2704 - - PowerPoint PPT Presentation

Probing the Electroweak Phase Transition with a Next-Generation pp Collider

BARYOGENESIS FROM WIMPS

Brian Shuve SLAC

19 September 2015

• Y. Cui, L. Randall, and BS, arXiv:1112.2704 (JHEP)
• Y. Cui and BS, arXiv:1409.6729 (PRD)

2

Cosmology at the Weak Scale

We have a new scale in particle physics Electroweak baryogenesis links the baryon asymmetry to this new scale (but need new dynamics!)

3

Cosmology at the Weak Scale

Coincidentally, we also see this scale imprinted in cosmology

DM DM SM SM

perturbative unitarity: MDM . 100 TeV

Griest, Kamionkowski 1990

What does this have to do with baryogenesis? Some hints....

1) Comparable energy densities of baryons and DM 2) Common features in DM/baryogenesis dynamics

see also Asymmetric Dark Matter models (recent renewal of interest: ex. Kaplan, Luty, Zurek 2009)

ΩDM ≈ 5 Ω∆B

• Out-of-equilibrium dynamics, CPV, self-conjugate particles

ΩDM ⇠ 1 hσ vDMi ⇠ 0.27 ✓ αW αDM ◆2 ✓MDM TeV ◆2

4

Baryogenesis-WIMP connections

I will briefly review two possible WIMP baryogenesis mechanisms, focusing on connections between cosmology and weak-scale probes Baryogenesis from WIMP Annihilation (“WIMPy Baryogenesis”):

DM DM SM SM

B − L > 0

B − L =

• Typically predict new gauge-charged states
• Collider and DM probes

Cui, Randall, BS 2011

Baryogenesis from Meta-Stable WIMP Decay: χ χ

SM SM

χ ui dk dj

• Colliders

(long-lived decays)

Cui, Sundrum 2012 Cui 2013 Cui, BS 2014

5

WIMPy Baryogenesis

DM DM SM SM

B − L > 0

B − L =

6

WIMPy Baryogenesis

• 1. Violation of B-L

DM DM SM SM

B − L > 0

B − L =

• If DM is a colour singlet, no B-L violation allowed

for pair of SM final states

• Need to couple to an exotic B/L charged state

X

exotic

• Equal and opposite asymmetries in regular baryons & exotic baryons
• Need asymmetries to be sequestered or for the exotic baryon to have additional

couplings to quarks that change its effective baryon number

DM DM SM baryons sterile antibaryons B conserving decay exotic antibaryon DM DM SM baryons B violating decay exotic antibaryon

Sakharov conditions:

7

WIMPy Baryogenesis

• 2. Violation of CP

DM DM SM SM

B − L > 0

B − L =

• Generally have phases in new couplings
• Might provide phenomenological handle!
• Physical CP violation comes from interference with on-shell states in loop:

X

exotic

new CP phases

X X ψ ¯ u λ∗2

3

¯ u ψ X X ψ ¯ u λ∗2

9

λ2

1

EFT diagrams from Bernal et al., 2012

✏ ≡ Γ(XX → ¯ u) − Γ(X†X† → †¯ u†) Γ(XX → ¯ u) + Γ(X†X† → †¯ u†)

8

WIMPy Baryogenesis

• 3. Departure from Thermal Equilibrium
• Opening the loop gives rise to washout processes
• We want these to be inactive at some point during DM annihilation

ψ ¯ u X X λ2

s1,s2,t

X ¯ u X† ψ† λ2

s1,s2,t

ψ ¯ u ψ† ¯ u† λ2

WO

Γwashout ⇠ hσ vψ¯

u→ψ† ¯ u†iYψYu + . . .

ΓDM ann. ⇠ hσ vXX→ψ¯

uiYX

• Annihilation, asymmetry production and washout depend on same couplings
• Generally, washout only freezes out before DM annihilation for

and ѱ in equilbrium

Can be somewhat relaxed in EFT (Bernal et al., 2012)

MX . Mψ . 2MX

9

WIMPy Baryogenesis: Asymmetry

Example simplified model:

• S is real scalar mediator
• n is a Majorana singlet (can be dark radiation), keeps ѱ in equilibrium
• Avoid ѱ-quark mixing due to some discrete (or global) symmetry
• Can have leptogenesis if ѱ instead couples to leptons

L ⊃ λi SiX2 + yi Siψ¯ u + 1 Λ2 (ψ n)(¯ u† ¯ d†) + h.c.

!"#$%&'()$&(*+,-./ 01 $$!2 !"#$%*.3,45$&(*+,-./$ !2

'6

MS = 5 TeV, MX = 3 TeV

(Mψ = 2 TeV) (Mψ = 4 TeV)

Washout 2mX mΨ Viable parameters LHC gluino constraint too strong 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.5 1.0 1.5

mX mS mΨ mS mS 1.5 TeV

LHC EXCLUDED

10

WIMPy Baryogenesis: Pheno

Colliders are the best way of probing WIMPy baryogenesis! Direct Baryogenesis Leptogenesis

∆L = 1 Λ2 (ψn)(¯ u† ¯ d†)

(XX → ¯ uψ) (XX → Lψ)

∆L = LH∗n

ψ

ψ† ¯ u ¯ d

n

n†

¯ u†

¯ d†

gluino-like wino-like

W ±

ψ± ψ0

Recast from Cohen et al., 2013 (Snowmass)

8 TeV, 20/fb: 14 TeV, 3/ab: 100 TeV, 3/ab: 100 TeV, 3/ab: 14 TeV, 3/ab: 8 TeV, 20/fb:

Mψ bound

720 GeV 1 TeV 3.3 TeV 2.5 TeV 1.35 TeV

Mψ bound

Gori, Jung, Wang, Wells 2014

11.5 TeV

11

WIMPy Baryogenesis: Pheno

• Perturbative direct baryogenesis parameter space

largely covered @ 100 TeV, 3/ab

• Leptogenesis more challenging near perturbativity

limit

• In extended models, other signatures are possible

(ex: RPV-like decays of charged states)

2 YX

• 3

x 1 014 2Y

X

9.5 x 10

• 1

4

• bserved

2Yx 3 x 1013 1 2 3 4 5 1.0 10.0 5.0 2.0 3.0 1.5 7.0

ΛX ΛBΛX

MS = 5 TeV, MX = 4 TeV, Mψ = 7 TeV

Y∆B = Y obs

∆B

Y∆B = 2Y obs

∆B

Y∆B = 0.5 Y obs

∆B

Other possible constraints:

• 1. EDMs
• 2. Direct detection
• Naïve two-loop result cancels, giving suppressed EDMs in minimal model (may be

larger in extended models)

• Naïve one-loop result cancels, giving velocity-suppressed spin-independent rates
• 3. Indirect detection
• Subdominant to collider constraints (but more model-independent)

12

Baryogenesis from WIMP Decay

χ χ

SM SM

χ ui dk dj

13

Baryogenesis from WIMP Decay

• In WIMPy baryogenesis, baryogenesis comes from WIMP dynamics but the

asymmetry is not directly related to the WIMP abundance

• Alternatively, if DM is produced through the decay of a meta-stable WIMP,

the asymmetry is automatically proportional to a DM-like abundance ✏ = Γ( → B) − Γ( → ¯ B) Γ( → B) + Γ( → ¯ B)

Ω∆B ≈ ✏ Mnucleon Mχ Ωτχ→∞

χ

Γχ . H(Tf.o.)

• WIMP dynamics can give an overabundance of χ, compensating for the

suppression factors

• To inherit the freeze-out abundance,
• Earlier decay can generate some asymmetry, but it is diluted due to rapid χ scattering

Cui, Sundrum 2012

14

Baryogenesis from WIMP Decay

• How big was the universe around the weak scale?

H(100 GeV) ∼ 10−14 GeV ∼ (1.3 cm)−1

10 GeV → (1.3 m)−1

1 TeV → (0.13 mm)−1

• Recall zf.o. ~ 20
• For WIMP masses ~100 GeV-TeV, the particle is long-lived if we can make it at

a collider!

• Heavier particles are closer to B lifetime, but mass discrimination is better

see also Barry, Graham, Rajendran 2013

15

Baryogenesis from WIMP Decay

• The method of collider production is similar to DM: cross the diagram

p p

MET MET

ISR

χ χ

j/`/MET j/`/MET

p p

(cτχ & 1 mm)

χ

χBG

vs.

• Direct link between cosmological condition and collider signature
• Look at representative models to see possible production modes, and then

use simplified models approach for collider study

• Large production + late decay consistent with approximate stability symmetry

16

SUSY Model

• An RPV-SUSY model illustrates the possible long-lived particles
• Many CP phases (ex. gaugino masses)
• B-L violation can come from udd, QdL, LLE-type superpotential terms or RPV terms

in Kähler potential

• Mini-split spectrum alleviates EDM constraints, makes LSP long-lived
• Bino typically gives overabundance, so it is a natural candidate for χ
• Asymmetry is largest when there is some other on-shell Majorana state that can run

in loop

˜ B di dj uk ˜ d∗

Tree-level RPV decay:

"

˜ B ˜ d di ¯ d ˜ g ˜ d∗ dj uk

Interference loop:

• split spectrum:

˜ B ˜ B H H∗ ˜ H

Thermal annihilation:

Tree-level Decay Loop-level Decay Freeze-out

• Can also have light gauge-charged states with same parametric lifetime

Cui 2013

Higgs portal:

singlet-like

χ χ

h

S sin α

λSχχ

17

WIMP decay baryogenesis: Pheno

• By analogy with DM, classify pair production modes, such as...

Majorana = gaugino-like (wino)

SM gauge interactions:

g/W/Z

χ χ

• Similar to EWBG, factorize CPV from equilibrium criterion

coupling fixed, can study mass reach fix χ mass @ 150 GeV, study coupling reach

• Model-independent constraints on

Higgs mixing relatively weak

0.85 0.90 0.95 1.00 100 150 200 250

LHC HL-LHC ILC-1 ILC-3 TLEP

cosq m2HGeVL

Profumo, Ramsey-Musolf, Wainwright, Winslow 2014 Cui, BS 2014

18

WIMP decay baryogenesis: Pheno

• Unlike DM, we also have to specify decay modes (also two examples):

Lepton number violating:

χ → LiQj ¯ dk

Baryon number violating:

χ → uidjdk

χ → QiQj(dc

k)†

CMS, arXiv:1411.6530 displaced jets (all-hadronic) displaced muon + hadrons ATLAS-CONF-2013-092

• We specifically looked at inner-detector decays (consistent with saturating

cosmological criteria), but decays in other components important too

• Very low SM backgrounds give good sensitivity even for small cross

sections

Later comprehensive analyses in RPV SUSY: Liu, Tweedie 2015; Csaki et al., 2015; Zwane 2015 In context of naturalness: Craig et al., 2015; Csaki et al., 2015;

19

Fully hadronic displaced vertices

8 TeV:

200 400 600 800 1000 0.5 1.0 5.0 10.0 50.0 100.0 Mc HGeVL scc95 % CL HfbL

wino Æ 3j, s = 8 TeV

scc HNLOL <Lxy> = 300 cm <Lxy> = 30 cm <Lxy> = 3 cm

wino singlet (Higgs portal)

no bound (singlet-like, Mχ = 150 GeV)

0.5 1.0 1.5 2.0 10 20 50 100 200 500 1000 2000 lScc sinH2aL luminosity Hfb-1L

Higgs portal c Æ 3j, 1DV vs. 2DV comparison s = 13 TeV

mc = 150 GeV 1 DV, 30% syst. 1 DV, 10% syst. 2 DV

Lxy = 3 cm

1000 1500 2000 2500 1 5 10 50 100 500 1000 Mc HGeVL luminosity Hfb-1L

wino Æ 3j, 2 DV, luminosity for 3 events, s = 13 TeV

1 DV, 30% syst. 1 DV, 10% syst. 2 DV

13 TeV:

20

Displaced muon + hadrons

500 1000 1500 2000 2500 0.001 0.01 0.1 1 10 100 1000 Mc HGeVL luminosity Hfb-1L

wino Æ m + tracks, 1 DV, luminosity for 3 events, s = 13 TeV

<Lxy> = 30 cm <Lxy> = 3 cm <Lxy> = 0.3 cm

13 TeV

0.0 0.5 1.0 1.5 2.0 5 10 50 100 500 1000 lScc sinH2aL luminosity Hfb-1L

Higgs portal c Æ m + tracks, 1DV, luminosity for 3 events, s = 13 TeV

mc = 150 GeV <Lxy> = 30 cm <Lxy> = 3 cm <Lxy> = 0.3 cm

wino

200 400 600 800 0.5 1.0 5.0 10.0 50.0 100.0 Mc HGeVL scc95 % CL HfbL

wino Æ m + tracks, s = 8 TeV

scc HNLOL <Lxy> = 30 cm <Lxy> = 3 cm <Lxy> = 0.3 cm

8 TeV singlet (Higgs portal)

no bound (singlet-like, Mχ = 150 GeV)

21

Prospects for HL/HE running

(Strassler, Zurek 2006)

• Main challenge is triggering on all-hadronic, low-mass new physics
• Hidden valleys
• Exotic Higgs decays
• Neutral naturalness

(review: Curtin et al., 2013) (Craig et al., 2015; Curtin, Verhaaren 2015)

• Other trigger options
• Associated objects
• “Volunteers”
• Trackless jets or other use of tracking information
• LHCb (better for high-multiplicity objects like emerging jets)

Schwaller, Stolarski, Weiler 2015

• Decays in other components: easy to trigger, harder to reconstruct
• Best sensitivity ~3 orders of magnitude worse than inner detector
• High-mass physics: should have sensitivity up to kinematic limit!

22

Implications of Phase Transition

• Phase transitions change masses of fields
• If fields get their mass from symmetry breaking, this can change particle

abundances and asymmetries, generate out-of-equilibrium abundances

• In neither scenario are there direct links to the EWPT
• Leptogenesis must occur prior to EWPT, so modifying the transition can

change the allowed parameter space

• Finally, let’s not forget low-scale leptogenesis, which can be tested by:
• SHiP
• Exotic Higgs sectors
• B-factories/LHCb
• LHC + 100 TeV collider
• ....

(BS, Yavin 2014) (Izaguirre, BS 2015; Batell, Pospelov, BS in progress) MANY , MANY REFERENCES!!

23

Conclusions

• WIMP-like dynamics can generate a baryon asymmetry in several ways,

definitively linked to the weak scale

• Colliders serve as excellent probes of this new physics
• 100 TeV collider would allow the comprehensive study of the most

favoured regions for WIMP-driven baryogenesis

24

Back-up slides

25

WIMPy Baryogenesis: Pheno

Other possible constraints:

• 1. EDMs
• In the minimal model, new physics only couples to one chirality of fermion
• Gives cancellation when summing over diagrams at two loops
• In the quark-coupled model, may have EDM at 10-31 e cm level
• CPV can be very large in extended models

eL eR eL L†

i

ψ†

i

Sα Sβ ψ†

1

γ eL eR eL Li ψi Sα Sβ ψ†

1

γ eL eR eL L†

i

ψ†

i

Sβ Sα ψ†

1

γ eL eR eL Li ψi Sβ Sα ψ†

1

γ

26

WIMPy Baryogenesis: Pheno

Other possible constraints:

• 2. Direct detection
• In the quark-coupled model, direct detection occurs naïvely at 1-loop
• However, there is a cancellation among diagrams to give a v-suppressed rate
• Again, this may be different beyond the minimal model

X ¯ u ¯ u X X ψ X ¯ u X ψ ¯ u X λ2

s

λ∗2

s

λ2

s

λ∗2

s

• 3. Indirect detection
• Comparable to regular WIMPs annihilating to hadrons, gauge bosons, subdominant

to collider constraints (but more model-independent)

• Other bounds (flavour, n-nbar oscillation) could be large, are model-dependent

27

LHC Search Possibilities

100 µm

1 mm

50 cm 1.5 m 4.5 m 10 m

Lxy

prompt analyses heavy flavour decays disappearing tracks vertices from displaced tracks non-pointing photons displaced lepton jets stopped gluinos decays in HCAL decays in muon system stable charged particles

18 5

missing energy searches

exotica & SUSY

28

Displaced Jet Bounds

0.0 0.5 1.0 1.5 2.0 10 20 50 100 200 500 1000 2000 H2aL Hfb L

TeV

eV yst. yst. DV

0.0 0.5 1.0 1.5 2.0 10 20 50 100 200 500 1000 2000 lScc sinH2aL luminosity Hfb-1L

Higgs portal c Æ 3j, 1DV vs. 2DV comparison, luminosity for 3 events, s = 13 TeV

mc = 150 GeV 1 DV, 10% syst. 2 DV

(b) hLxyi = 30 cm

29

Decays in Other Components

Can also have decays in calorimeters and muon system HCAL muon system (MS)

(ATLAS - arXiv:1501.0402) (ATLAS - arXiv:1504.03634) trigger on jets with no ECAL deposition trigger on large, isolated activity in MS 2 DV in tracker and/or MS 2 long-lived states each decaying in HCAL

• Common features
• Limited acceptance due to requiring decays in specific places
• Need stringent criteria + 2DV to suppress backgrounds
• Worse limits than tracker decays for high-mass objects, comparable for

low-mass

• Thresholds won’t go up significantly for future running