Looking through the Higgs portal with exotic Higgs …...Looking through the Higgs portal with exotic Higgs decays Jessie Shelton University of Illinois, Urbana-Champaign Unlocking

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

Documents

Looking through the Higgs portal with exotic Higgs …...Looking through the Higgs portal with exotic Higgs decays Jessie Shelton University of Illinois, Urbana-Champaign Unlocking