looking through the higgs portal with exotic higgs …...looking through the higgs portal with...

Looking through the Higgs portal with exotic Higgs decays

Jessie SheltonUniversity of Illinois, Urbana-Champaign

Unlocking the Higgs Portal (U. Mass. Amherst)May 1, 2014

0.0

0.2

0.4

0.6

0.8

1.0

Br

h ! ff̄

h ! V V ⇤

h ! V V [GeV]HM100 200 300 1000

[GeV

]H

�

-210

-110

1

10

210

310

LHC

HIG

GS

XS W

G 2

010

500

�h(125 GeV) = 4.1 MeV

A light SM-like Higgs is narrow


• Presence of new light degrees of freedom can distort Higgs Brs by O(1) even for small couplings

Simple example: one new scalar

z = 0.001

z = 0.005

z = 0.01z =ms2 ëv2

0 10 20 30 40 50 60

10-4

0.001

0.01

0.1

1

ms HGeVL

BrHhÆ

ssLk

�L =⇣

2s2|H|2


Simple dim-5 interaction

• Exotic Higgs decay modes easily sensitive to new physics scales significantly above a TeV

M = 1 TeVM = 2.5 TeV

M = 5 TeV

M = 10 TeV

M = 20 TeV

0 10 20 30 40 50 600.0

0.2

0.4

0.6

0.8

1.0

mcqHGeVL

BrHhÆccLk

�L =1

M ̄ |H|2

Exotic Higgs Decays at the LHC

Higgs production in gluon fusion (8 TeV): 20 pb

Accumulated data at 8 TeV: 20 ifb

If: order one acceptance, good S/B:statistics for branching fractions ~10-4

~400,000 Higgs bosons served


BSMBR0.0 0.5 1.0

gκ

0.0

0.5

1.0

1.5

2.0

ln L

Δ-2

02468101214161820

CMS Preliminary -1 12.2 fb≤ = 8 TeV, L s -1 5.1 fb≤ = 7 TeV, L s

CMS indirect limits on BSM Higgs width


Unofficial combination of ATLAS and CMS (Giardino et al.);

(see also Ellis, You; Belanger et al.)

h

a

b

bb

b

a

Four soft b-jets:

pT . 30 GeV

A tough signal for a hadron machine like LHC:

...but also, many searches have not yet been done

[GeV] HM100 200 300 400 500 1000

H+X

) [pb

]

�(p

p �

-210

-110

1

10= 7 TeVs

LHC

HIG

GS

XS W

G 2

010

H (NNLO+NNLL QCD + NLO EW)

�pp

qqH (NNLO QCD + NLO EW)

�pp

WH (NNLO QCD + NLO EW)

�pp

ZH (NNLO QCD +NLO EW)

�pp

ttH (NLO QCD)

�pp


D. Curtin, R. Essig, S. Gori, P. Jaiswal, A. Katz, T. Liu, Z. Liu, D. McKeen, JS, M. Strassler, Z. Surujon, B. Tweedie, Y-M. Zhong

Immense landscape of possibilities

Exotic Decays of the 125 GeV Higgs Boson, arXiv:1312.4992

• Higgs portal couplings:

• Signatures depend on how HS states decay: to further HS states, back to SM

• May be: NMSSM-like, semi-invisible, high multiplicity, displaced, ...

Lint =X

i

1

⇤di�2i

|H|2O(di)i + . . .

Theories for Exotic Higgs Decays

• Long-standing body of work on

exotic Higgs decays, much driven by

precision EW preference for a Higgs

below the LEP bound

• Many examples fall out naturally from extended Higgs

sectors: NMSSM, EW baryogenesis, ...

• Others come from DM model building

• Genericity of Higgs portal: what are light degrees of

freedom?


1. Higgs decay to scalars

h

a

b

b

b

b

a

f

f

f

f

�L = V (a) +�

4a2|H|2

1 2 5 10 20 5010!4

0.001

0.01

0.1

1

ms!GeV"

BR

bbccss""##gg

$$

uudd

Singlet Br: SM Yukawas



h

a

b

b

b

b

a

f

f

f

f

�L = V (a) +�

4a2|H|2

Singlet pair Br: SM Yukawas

1 2 5 10 20 5010!4

0.001

0.01

0.1

1

ms!GeV"

BR#h"ss"XXYY$

4bbb##cc##4#

4ggg##bb$$4$##$$

gg$$



Singlet pseudoscalar Br: SM Yukawas

Extended Higgs sectors alter Yukawas:

consider 2HDM + complex singlet S

Type 1: SM

1 2 5 10 20 5010!4

0.001

0.01

0.1

1

ma!GeV"

BR

Type I

bbccss""##gg

uudd$$



Singlet pseudoscalar Br: Type II Yukawas



Type 1: SMType II: NMSSM-like

1 2 5 10 20 5010!4

0.001

0.01

0.1

1

ma!GeV"

BR

Tan "#5, TYPE II

bbccss$$%%gg

uudd&&



Singlet pseudoscalar Br: Type III Yukawas




Type III: lepton-specific 1 2 5 10 20 50

10!4

0.001

0.01

0.1

1

ma!GeV"

BR

Tan "#5, TYPE III

bbccss$$%%gg

uudd&&



Singlet pseudoscalar Br: Type IV Yukawas




Type III: lepton-specificType IV: flipped 1 2 5 10 20 50

10!4

0.001

0.01

0.1

1

ma!GeV"

BR

Tan "#5, TYPE IV

bbccss$$%%gg

uudd&&


2. Higgs decay to fermions

�L = ��HL �L =1

M�†�|H|2

Lepton number violation Nonrenormalizable

L = 0.5 TeV

L = 1 TeV

L = 2 TeV

0 10 20 30 40 50 6010-6

10-5

10-4

0.001

0.01

0.1

1

myHGeVL

BrHhÆyyLk

Chiral symmetry: can be effective dim-6


2. Higgs decay to fermions

Signatures depend on further fermion couplings: parameters largely independent of Higgs couplings

h

X

X

h hh

invisible: DM, SUSY

light bosonic dofs?

flavored 3-body decays


3. Higgs decay to vectors

h

�L = V (S) +

4S2|H|2

+✏Bµ⌫Vµ⌫

•Photon and Higgs portal

couplings with independent

strengths

•Higgs mixing: ,

•Kinetic mixing:

h ! VDVD

h ! VDZ

h ! aa


3. Higgs decay to vectors

!!

!"

#!#"

c c

b b

light hadrons

$$

10 20 30 40 50 600.0

0.1

0.2

0.3

0.4

0.5

mZD

Br

Relatively leptophilic!

Direct searches for exotic Higgs decays

• Each final state requires its own strategy.

• General observations:

• Leptonic resonances especially powerful

• Recast LHC8 analyses already place interesting limits on final states with multiple electroweak objects

• ...but results depend very sensitively on acceptance thresholds

• gluon fusion: powerful but limited

• A range of possibilities from spectacular to very hard


Example 1: .h ! VDVD ! 4`

h Resonant 4-lepton signal: spectacular ...just need to look for it!

• NMSSM-motivated 4-muon searches stop at 5 GeV

• Scrape data from Higgs searches, ZZ calibration regions



CMS data, SM background: ZZ*

mV = 20 GeVsmax = 7.3 fb

40 60 80 10010

20

30

40

50

60

m1 HGeVLm2HGe

VL

Exotic contribution



CMS data, SM background: ZZ* Exotic contribution

mV = 40 GeVsmax = 3.4 fb

40 60 80 10010

20

30

40

50

60

m1 HGeVLm2HGe

VL



10 20 30 40 50 600.0000

0.0002

0.0004

0.0006

0.0008

0.0010

mZDqHGeVL

Brk HhÆ

Z DZ DL

95% CL limits

ATLAS ZZ control region

CMS Higgs


Example 1A: .

95% CL limits

h ! ZVD ! 4`

CMS 20 ! 5 fb"1ATLAS 20 ! 5 fb"1

15 20 25 300

5

10

15

mX

Br!h#ZX"$Br!X#

!!"$104


Example 1A: .h ! ZVD ! 4`

10-3 10-2 10-1 1 10110-5

10-4

10-3

10-2

10-1

mZD @GeVD

e

U70

PROMPT

NON-PROMPT

E141

E774

EWPM

am, 5s

am,±2s favored

ae

BaBarKLOE

WASA

APEXêMAMI

Orsay

BrHhÆZZD L=10 -6

10 -510 -4

10 -3

CMS

Further possibilities:

h ! ss ! 4ZD

more complicated HS cascades...

h ! ZDZD ! exotic


Example 2: . h ! aa ! 4⌧, 2⌧2µ

Exclusions from multilepton searches


Example 2: . h ! aa ! 4⌧, 2⌧2µ

Gain from sharp resonance in muons, despite lower BR [Lisanti & Wacker]


Example 2A: METh ! �2�2 ! 4`+

Best existing limits from inclusive many-bin CMS multi-lepton searches:

Br(h ! �2�2) < 12%

(SUS-12-027, SUS-13-010) (includes Z Br and is highly spectrum-dependent)

•Most multi-lepton analyses specialized for high-pT signals

•Can further target analyses to Higgs kinematics

30 GeV

40 GeV50 GeV

60 GeV

20 GeV

0 10 20 30 40 50

0.02

0.05

0.10

0.20

0.50

1.00

mc1

Allo

wed

BR

Estimated 95% CL limits on allowed Br


Best limits: GMSB search (CMS SUS-12-018)

• 4 ifb, not optimized for Higgs signal

Example 2B: METh ! �2�2 ! 2�+

h

GMSB neutralinosextended DM sector with dipole

Estimated 95% CL reach


Example 3: .h ! ss ! 2b2µ

10 20 30 40 50 6010!4

10!3

10!2

10!1

1

ma !GeV"

Max.Br#h"aa"bb#$#!$

8 TeV LHC, L%25 fb!1

At least one b!tagTwo b!tagsNo b!tag

2m2µ

3m2b

= 4⇥ 10�4


LHC prospects for .h ! ss, aa

• The observed 125 GeV Higgs boson is highly sensitive to the potential existence of new light degrees of freedom

• Many interesting results/prospects at LHC8 already

• Light (pseudo-)scalars: still difficult

• Great statistical power from LHC 14: Higgs factory

• but reduced acceptance for low-pT objects may limit reach

• Important to remember for LHC 14: many physics opportunities at low pT

Summary and Conclusions

looking through the higgs portal with exotic higgs …...looking through the higgs portal with...

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