Implications of 98 GeV and 125 GeV Higgs scenario in non-decoupling...

Implications of 98 GeV and 125 GeV Higgs scenario innon-decoupling SUSY

Dilip Kumar Ghosh

Department of Theoretical PhysicsIndian Association for the Cultivation of Science

Kolkata, India

Collaborators:B. Bhattacherjee, M. Chakraborti, A. Chakraborty, U. Chattopadhyay, D. Das

Ref: [Phys. Rev. D 88 (2013) 035011]

Dilip Kumar Ghosh (IACS) 98 GeV and 125 GeV Higgs scenario IPMU, Tokyo (Japan), 19.03.2014 1 / 47

Plan of the talk

Introduction

Inclusive LEP-LHC Higgs (ILLH) scenario

ILLH @MSSM and NMSSM

Collider analysis and results

Updated analysis (in progress)

Summary


Introduction

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A Standard Model like Higgs particle has been found by the ATLAS & CMScollaboration of the LHC experiment with mh ' 125 GeV.Evidence of this particle in multiple channels.The observed rates of this particle are compatible with the SM prediction.


Higgs couplings are not yet measured very precisely

With future LHC run and possibly at ILC the couplings will be measured moreprecisely =⇒ constrain several scenarios beyond the SM / or give a possibledirection to new physics.

)µSignal strength ( -1 0 +1

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-1Ldt = 4.7 fb∫ = 7 TeV: s-1Ldt = 13 fb∫ = 8 TeV: s

= 125.5 GeVHm

0.20± = 1.30 µ

ATLAS Preliminary

SMσ/σBest fit 0 0.5 1 1.5 2 2.5

0.28± = 0.92 µ ZZ→H

0.20± = 0.68 µ WW→H

0.27± = 0.77 µ γγ →H

0.41± = 1.10 µ ττ →H

0.62± = 1.15 µ bb→H

0.14± = 0.80 µ Combined

-1 19.6 fb≤ = 8 TeV, L s -1 5.1 fb≤ = 7 TeV, L s

CMS Preliminary = 0.65

SMp

= 125.7 GeVH m


Can MSSM accommodate 125 GeV Higgs boson ?


125 GeV Higgs and MSSM

It seems that the observed 125 GeV Higgs like particle agrees well with predictionof MSSM.

In MSSM, the large quadratic divergence in m2h due to top quark loop is cancelledby the scalar partner of top quarks (called stop t̃i , with i = 1, 2).

Stop sector plays a crucial role in determining the Higgs mass =⇒ theexperimental determination of the stop properties is crucial to understand thenature of SUSY protecting the Higgs mass at EW scale.

So far LHC has not seen any evidence of SUSY particles, only lower bounds havebeen put on different SUSY particles.

Limits on gluino (g̃) and squarks (q̃) currently stands at about 1.5 TeV for mg̃ ' mq̃and about 1.2 TeV for mg̃ � mq̃.


CMS SUSY exclusion

Mass scales [GeV]0 200 400 600 800 1000 1200 1400

0χ∼ l → l

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0χ∼

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0χ∼

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~0

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0χ∼ b → b

~

H G)→ 0χ∼(0χ∼ t b → t~)0χ∼ W → ±χ∼ b (→ t~)0χ∼ W→ +χ∼ b(→ t~0χ∼ t → t~0χ∼ t → t~

0χ∼ q → q~0χ∼ q → q~

))0

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b(→ g~)

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2

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)0

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χ∼γ→2

0χ∼ qq(→ g~

)0χ∼ W→±χ∼ qq(→ g~)

0χ∼ Z →

2

0χ∼ qq (→ g~

)0χ∼ ν± l→ ±χ∼ qq(→ g~)0χ∼ t→ t~ t(→ g~)0χ∼ |0χ∼ W→±χ∼ qq(→ g~)

0χ∼ |

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2

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l+

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Summary of CMS SUSY Results* in SMS framework

CMS Preliminary

m(mother)-m(LSP)=200 GeV m(LSP)=0 GeVSUSY 2013

= 7 TeVs

= 8 TeVs

lspm⋅-(1-x)

motherm⋅ = xintermediatem

For decays with intermediate mass,

Only a selection of available mass limits*Observed limits, theory uncertainties not included

Probe *up to* the quoted mass limit


ATLAS SUSY exclusion

Model e, µ, τ, γ Jets EmissT

∫L dt[fb−1] Mass limit Reference

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MSUGRA/CMSSM 0 2-6 jets Yes 20.3 m(q̃)=m(g̃ ) ATLAS-CONF-2013-0471.7 TeVq̃, g̃

MSUGRA/CMSSM 1 e,µ 3-6 jets Yes 20.3 any m(q̃) ATLAS-CONF-2013-0621.2 TeVg̃

MSUGRA/CMSSM 0 7-10 jets Yes 20.3 any m(q̃) 1308.18411.1 TeVg̃

q̃q̃, q̃→qχ̃01 0 2-6 jets Yes 20.3 m(χ̃01)=0 GeV ATLAS-CONF-2013-047740 GeVq̃g̃ g̃ , g̃→qq̄χ̃01 0 2-6 jets Yes 20.3 m(χ̃01)=0 GeV ATLAS-CONF-2013-0471.3 TeVg̃g̃ g̃ , g̃→qqχ̃±1→qqW ±χ̃01 1 e,µ 3-6 jets Yes 20.3 m(χ̃01)50 GeV 1209.07531.07 TeVg̃

GGM (wino NLSP) 1 e, µ + γ - Yes 4.8 m(χ̃01)>50 GeV ATLAS-CONF-2012-144619 GeVg̃GGM (higgsino-bino NLSP) γ 1 b Yes 4.8 m(χ̃01)>220 GeV 1211.1167900 GeVg̃GGM (higgsino NLSP) 2 e, µ (Z ) 0-3 jets Yes 5.8 m(H̃)>200 GeV ATLAS-CONF-2012-152690 GeVg̃

Gravitino LSP 0 mono-jet Yes 10.5 m(g̃ )>10−4 eV ATLAS-CONF-2012-147645 GeVF1/2 scale

g̃→bb̄χ̃01 0 3 b Yes 20.1 m(χ̃01)

125 GeV Higgs in SUSY

superparticles responsible for cancellation of quadratic divergence in Higgs massare the third generation squarks, can be comparatively light to cure the fine-tuningproblem of SM.

m2h ' m2Z cos2 2β +3

4π2m4tv2

(log

M2Sm2t

+X 2tM2S

(1− X2t

12M2S)

)MS =

√mt̃1 mt̃2

Xt ≡ At − µ cotβ

At : the trilinear Higgs-stop coupling.

mh =⇒ heavier for larger tanβ or MS .For a given MS , mh reaches maximum when Xt =

√6MS so-called mmaxh scenario.

Lighter stop/sbottom : large stop/sbottom tri-linear couplings.


[L.J.Hall et.al, JHEP 04, 131 (2012)]

Light third generation scenario has an extremely attractive prospect for both thetheorists and the experimentalists


Did LEP give us any hint about Higgs ?


Higgs@LEP ?

At LEP, Higgs boson is searched in e+e− → ZH channel.Combined analysis of four LEP experiments: Mh > 114.4 GeV @ 95% C.L.

e−

e+

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H

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Parameter: ζ ≡(

gBSMHZZgSMHZZ

)= sin(β − α)

( α: Higgs mixing angle, tanβ: ratio of VEVs)

A mild excess (∼ 2.3σ) of Higgs-like events e+e− → Zh with a mass near 98 GeV.


LEP, LHC and SUSY

Both LEP and LHC events can be explained simultaneously in MSSM, andNMSSM.

MSSM: Five Higgses : h0,H0,A0,H±.

At tree level, MA and tanβ controls the MSSM Higgs sector.

Higgs couplings to gauge bosons and fermions are functions of β and α.

W +W−H, HZZ , ZAh, W±H∓h, ZW±H∓h and γW±H∓h ∝ cos(β − α).W +W−h, hZZ , ZAH, W±H∓H, ZW±H∓H and γW±H∓H ∝ sin(β − α).

decoupling : MA ≥ 300 GeV and cos2(β − α)→ 0 =⇒ sin2(β − α)→ 1.In decoupling limit : One can interpret the newly observed state at 125 GeV as thelight CP even Higgs boson with SM like couplings.

non-decoupling : Mh ∼ MA ∼ MH ∼ MZ or sin2(β − α)→ 0 =⇒ cos2(β − α)→ 1.This would mean larger coupling strength of H with the SM gauge bosons.

We may explore the possibility of MH ∼ 125 GeV, instead of h as the discoverednew resonance.

H behaves like hSM and h has weaker couplings to W/Z .


MSSM parameter space scan

We generate approximately 70 million random points in the following combinedrange of parameters:

We consider mpolet = 173.3± 2.8 GeV.

3 < tanβ < 5.5, 0.085 < MA < 0.2 TeV, 0.3 TeV < µ < 12 TeV,

0.05 TeV < M1,M2 < 1.5 TeV, 0.9 TeV < M3 < 3 TeV,

−8 TeV < At < 8 TeV, −3 TeV < Ab, Aτ < 3 TeV, Au = Ad = Ae = 0,0.3 TeV < Mq̃3 < 5 TeV, where, q̃3 ≡ t̃L, t̃R , b̃L, b̃R

Mq̃i = 3 TeV, for i = 1, 2 and M ˜̀i = 3 TeV, for i = 1, 2, 3.

CMS has constrained tanβ −MA plane from H/A→ τ+τ− decay.ATLAS has constrained tanβ −MH± plane from H+ → τ+ντ in t t̄ events, whereone t → bH+.

[CMS-PAS-HIG-2012-050],[ATLAS Collaboration, JHEP 06 (2012),039]


CMS exclusion in tanβ −MA plane

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95% CL Excluded Regions

M

90 < MA < 250 GeV for tanβ > 5.5 is excluded.


ATLAS exclusion in tanβ −MH± plane

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Observed exclusion 95% CL

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Expected exclusion 2011

Observed exclusion 2011

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90 < MH± < 150 GeV for 2 < tanβ < 6 is excluded.


ILLH in MSSM

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The blue points satisfy following constraints:Lower limits on SUSY particles95 GeV < mh < 101 GeV; 122 GeV < mH < 128 GeV.0.1 < sin2(β − α) < 0.25 .RH2gg (γγ)min > 0.5, [ CMS : µ̂ = 0.78

+0.28−0.26 ].

2.77× 10−4 < Br(b → sγ) < 4.09× 10−4 at 3σ level.[Br(b → sγ)(exp) = (3.43± 0.22)× 10−4]. [arXiv:1207.1158].0.67× 10−9 < Br(Bs → µ+µ−) < 6.22× 10−9 at 2σ level.

The red circles (enclosing blue points) shows points satisfy the DM relic densityconstraint (only upper limit): 0.112 < Ωχ̃01 h

2 < 0.128.


ILLH in MSSM

90 100 110 120 130 140 150 160 170 180 190 200M

H+ (GeV)

3

3.5

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Effective Exclusion fromCMS (H/A-->τ+τ−)

I

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IIIIV

From our previous figure : 130 GeV< MA

Higgs decay observables

Anti-correlation behavior between primarysignal strength observables.Total Higgs decay width is primarilydetermined by h→ bb̄ decay width.QCD and SUSY QCD corrections to mb(∆b) play important roles in modifying thetotal decay width/ relevant branching ratios.A reduction (enhancement) of h,H → bb̄couplings decreases (increases) the totaldecay width of Higgs.Enhances (reduces) the branching ratios toh,H → γγ increasing (decreasing)Rhgg(γγ) or RHgg(γγ).

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RVHH(bb)

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RVHH(τ

+τ

−)


Sample benchmark point in MSSM parameter space

Mt MA tan β µ M1 M2 M3 At Ab173.6 167.5 5.0 5429.8 527.9 119.2 1416.6 5729.2 -217.1

Aτ Mq̃3LMt̃R

Mb̃RMh MH M(H

±) Mt̃1Mb̃1

-115.2 1712.6 1602.2 426.7 97.7 125.1 182.1 999.2 539.1

Mg̃ BR(Bs → µ+µ−) BR(b → sγ) Ωh2 ζσSI

(p−χ)1608.9 2.8×10−9 3.8×10−4 4.5×10−4 5.5×10−11

All masses are in GeV unit

cross-section is pb unit.

Main issues of our analysis in MSSM :

In MSSM one can have 98 GeV and 125 GeV Higgs bosons.

This restrict : 3 < tanβ < 5.5, 130 GeV < MA < 200 GeV and 150 GeV < MH± < 200 GeV


ILLH in NMSSM

0 50 100 150 200 250 300 350 400 450 500 550 6000

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)

λŜĤuĤd + κ3 Ŝ3.

3 (2) CP even (odd) neutral Higgses, Hi , i = 1, 2, 3 and Ai , i = 1, 2, and H±.

We vary λ, κ, Aλ, Aκ, A0, m0, m1/2, tanβ, µeff using NMSSMTools3.2.4.

In this parameter (figure) space of interest, MA2 ∼ MH3 ∼ MH± .Heavy mass scale (MA > 200 GeV) =⇒ can accommodate mh ∼ 98 GeV ( notpossible in MSSM with MA > 200 GeV.)

Indirect exclusion: A bit tough, particle masses relatively heavy, so less sensitiveat the LHC.

Exclusion is Model dependent.

Can we discover/exclude this at LHC in a model independent way ?


Prospect of observing 98 GeV Higgs @ Colliders


Can we find this 98 GeV Higgs @LHC ?

A combination of a 98 GeV & a 125 GeV Higgs boson in the nondecoupling limit ofMSSM and in NMSSM.

Nondecoupling limit of MSSM: =⇒ relatively light Higgs bosons =⇒ can beprobed at the early run of the LHC.

Non observation of such light Higgs bosons will indirectly exclude the possibility ofscenario with a 98 GeV Higgs boson.

Previous attempts :

At 8 TeV LHC, 5σ signal for pp → H±A0,H±h0 → τ±νbb̄ andpp → H+H− → τ+ντ−ν̄ can be observed with an integrated luminosity of7(11) fb−1 and 24(48) fb−1, respectively for MA = 95(130) GeV.

At the 14 TeV energy : 5σ signal can be observed with an integrated luminosity of4(7) fb−1 and 10(19) fb−1 respectively. [N.D.Christensen etal. 2012]

ATLAS search : 130 < MA < 200 GeV for tanβ ∼ 3− 5.5 ruled out the aboveanalysis and some others.

[M. Drees, PRD (2005) & (2012), N.D.Christensen etal. 2012, M. Asano etal. PRD (2012), S. Scopel etal. PRD (2013)].



Gluon fusion: g g→ H→ bb̄ for 98 GeV Higgs boson, large QCD jet background,difficult to prove.

Di-photon via Gluon fusion: Heavily suppressed BR(H→ γγ) for a 98 GeV Higgs,hard to distinguish from the continuous backgrounds.

VBF production: not so sensitive for a 98 GeV Higgs boson.

Higgs-strahlung process (VH): H is produced along with a gauge boson W/Z ,may have sufficient boost (large pT of Higgs)

p

p

W/Z

W/Z

H

gHWW/gHZZ


2.3σ excess in the LEP constrains the effective coupling :gBSMZZh /g

SMZZh ' 0.3− 0.5

⇒ controls the 98 GeV Higgs production cross-section in Vh at LHC⇒ A Model independent input parameter.

We follow ATLAS simulation considering 20% LEP excess and apply the JetSubstructure technique.

E/T > 30 GeV and pe/µT > 30 GeV [ hW ,W → µν, eν]

80 < m`` < 100 GeV, [ hZ ,Z → e+e−/µ+µ−]E/T > p

minT , with p

minT = 200 GeV [hZ ,Z → νν̄ and hW , W → `ν, ` is missing. ]

Process Significance ( S√B

) Combined`νbb̄ 1.7`+`−bb̄ 0.9 2.5E/T bb̄ 1.6

1 98 GeV Higgs at the 14 TeV LHC with 300 fb−1 luminosity is ∼ 2.5σ.2 This signal significance may be reduced further if systematic uncertainties in the

SM background estimations are considered.

[ATLAS Collaboration, Report No. ATL-PHYS-PUB-2009-008]


Associated production with top quarks

Associated production of 98 GeV Higgs boson with top quarks:

pp → t t̄h(h→ bb̄)

σ(pp → t t̄h) ∼ 1 pb for mh ∼ 100 GeV. at 14 TeV run of LHC. [CERN Yellow Report Page At 14TeV]Translated the results already performed by Tilman Plehn et. al. for ∼ 115 GeVStandard Model Higgs boson at 14 TeV LHC. [T. Plehn et.al. PRL 104, 111801 (2010)]

While translating the results of Tilman Plehn for our choice of Higgs mass, weexpect enhancements of 60% and 20% in Higgs production rate and backgroundestimation.

In our analysis, we scale the signal and background by 1.6 and 1.2, respectivelyfor h(mh = 98 GeV)→ bb̄).For an integrated luminosity of 300 fb−1 with two tagged b-jets the significance ∼3.1σ, while for three b-tag sample ∼ 2.6σ.Jet Substructure may marginally exclude the 98 GeV Higgs: experimentalcollaborations need to perform further detailed analysis.

In NMSSM A 98 GeV Higgs production from the decay of heavy Higgs bosons aswell as from the cascade decays of other sparticles may play an important role atthe LHC. [S.F. King et.al. NPB 870,323 (2013); Z.Kang et.al. PRD 88,015006 (2013)]


ILC

There has been a plan to build e+e− linear collider (ILC) with√

s ∼ 250 GeV -1000 GeV.

Like LEP, the Higgs boson will be produced in e+e− → Zh channel.ILC will be an ideal machine for the Higgs precision study.

In our analysis, we assume h→ bb̄ decay mode, while Z can decay leptonically orhadronically.

We use MadGraph5 to estimate the signal as well as SM backgroundcross-section for the 98 GeV Higgs boson.

For√

s = 250 GeV, σ(e+e− → Zh) = 350 fb, whereas σ(e+e− → ZZ ) ∼ 1.1 pb.We find that a 98 GeV Higgs boson can be easily discovered / excluded at the 250GeV ILC with a 100 fb−1 luminosity.

Discovery potential at the LHC is marginal.

ILC is an ideal machine to study this scenario.


Updated analysis (work in progress)

We relook the MSSM parameter space in the light of updated Higgs data:

ATLAS limits :

Rγγ : 1.55+0.33−0.28@[7 TeV(4.8) + 8 TeV(20.7)]

RZZ∗ : 1.43+0.40−0.35@[7 TeV(4.6) + 8 TeV(20.7)]

Rbb̄ : 0.2+0.7−0.6 @[7 TeV(4.7) + 8 TeV(20.3)]

Rτ+τ− : 1.4+0.5−0.4 @[8 TeV(20.3)]

CMS limits :

Rγγ : 0.78+0.28−0.26@[7 TeV(5.1) + 8 TeV(19.6)]

RZZ∗ : 0.93+0.29−0.25@[7 TeV(5.1) + 8 TeV(19.7)]

Rbb̄ : 1.0+0.5−0.5 @[7 TeV(5.1) + 8 TeV(18.9)]

Rτ+τ− : 0.87+0.29−0.29@[7 TeV(4.9) + 8 TeV(19.7)]


Updated analysis

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All points satisfy following constraints :95 GeV < mh < 101 GeV and 122 GeV < mH < 128 GeV0.1 < sin2(β − α) < 0.252.77× 10−4 < Br(b → sγ) < 4.09× 10−40.67× 10−9 < Br(Bs → µ+µ−) < 6.22× 10−9


Limits from the ATLAS and CMS Higgs search data

80 100 120 140 160 180 200

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(GeV)

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All points satisy previous constraints and Rγγ @2σ level .

ATLAS left figure and CMS right figure

Point to note : 130 GeV < MA < 200 GeV is allowed from CMS analysis ofH/A→ τ+τ−.


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(GeV)

3

3.5

4

4.5

5

5.5ta

nβ

80 100 120 140 160 180 200

MA

(GeV)

3

3.5

4

4.5

5

5.5

6

tanβ

Previous constraints plus Rτ+τ− @2σ level .


Conclusions

We studied the possibility that both the LEP excess in the bb̄ final state with a 98GeV Higgs boson and the LHC signal for a 125 GeV Higgs like object can besimultaneously explained in the most general MSSM framework.

This can happen in nondecoupling zone of MSSM Higgs sector, where,Mh ∼ MA ∼ MH ∼ MZ or sin2(β − α)→ 0 =⇒ cos2(β − α)→ 1.We have found a region of parameter space in MSSM allowed by heavy flavourphysics, CDM constraints, constraints from the XENON100 experiment on the DMdirect detection cross-section.

Both ATLAS & CMS searches on H/A→ τ+τ− and H± → τ+ντ from ATLAScollaboration severely constraint the parameter space : 130 GeV < MA < 200 GeVand 150 GeV < MH± < 200 GeV.

For these ranges of MA and MH± , tanβ ∼ 3− 5.5.We have shown that at the LHC it will be difficult to probe directly 98 GeV Higgsboson scenario, due low signal significance.


Work in progress..

The most recent data (at 2σ) on Higgs search still allow MSSM parameter spacewhere one can have simultaneously 98 GeV and 125 GeV Higgs boson.

More precise measurement on Higgs may be able to rule out this scenarioindirectly.

ILC is an ideal machine to explore this possibility.


Thank You!


References

1 B. Bhattacherjee et. al., arXiv:1305.4020 [hep-ph].2 R. Barate et al. [LEP Higgs WG], Phys. Lett. B 565, 61 (2003).3 T. Plehn et. al., Phys. Rev. Lett. 104, 111801 (2010).4 J. Butterworth et. al., Phys. Rev. Lett. 100, 242001 (2008).5 ATLAS Public NOTE: ATL-PHYS-PUB-2009-088


Backup slides


Dark matter direct detection

Exclude points with over-abundant relicdensities, include the possibility ofmulti-component dark matter.

χ̃01-χ̃±1 coannihilation: χ̃

01 a pure bino & χ̃

±1

is pure wino.Heavy sleptons: no coannihilation withLSPs.spin-independent direct detection χ̃01 − p:Region above the solid (black) linediscarded via XENON100 dataScaled cross-section (ζσSI

pχ̃01):

under-abundant relic densities.ζ = min{1,Ωχ̃01

h2/(ΩCDM h2)min}, where

(ΩCDM h2)min = 0.112Possibility at future direct-detectionexperiment XENON-1T

0 100 200 300 400 500 600 700 800 900

mχ

1

(GeV)

10-11

10-10

10-9

10-8

10-7

σS

I (p

-χ) (p

b)

0~

XENON100

XENON1T

0 100 200 300 400 500 600 700 800 900

mχ

1

(GeV)

10-12

10-11

10-10

10-9

10-8

10-7

ζσ

SI (

p-χ

) (p

b)

XENON100

0~

XENON1T



No Boost vs Boost

H → bb̄ at rest =⇒ Two back to back jets

mH = 120 GeV, pT >∼ 200− 300 GeV =⇒large boost =⇒ ∆R ≈ 2mH/pT ≈ 1.2− 0.8∆R =

√(∆η)2 + (∆φ)2

G. Kribs talk @ Fermilab (2011)


Application : pp → VH, (V = W±,Z )

pp → VH, with V = W±,Z =⇒`νbb̄, ``bb̄, νν̄bb̄ final state

For Higgs to be boosted pT (H) > 200 GeV

Such a high pT (H) =⇒σboosted(WH/ZH) ∼ 5% of σtot(WH/ZH) @14 TeV

ATLAS simulation @14 TeV with 30fb−1luminosity : NS(mH ∼ 120 GeV) ∼ 13.5and NB ∼ 20.3 =⇒ S√B = 3

[J.Butterworth etal., PRL (2008)], ATL-PHYS-PUB-2009-088, G. Kribs talk @ Fermilab (2011)


Fat jets

Quantitatively, consider the following thumb rule for a two-body decay: To resolve

the two partons of a X→ q q̄ decay,choose a radius (or more generally a jet size)of R < 2MX /PTFor PT � Mh R → very small ( Overlap of Jet areas !)

These highly boosted jets are called ”Fat Jets”

Example: Consider a hadronically decaying W Boson..

Question : How do I see the inside of this fat jet ?


Jet Substructure

The basis of this technique involves an iterative jet clustering algorithm (e.g C/A),examining subjet kinematics step-by-step, and finally choosing the “best“ subjets toform the fat-jet mass.

**Ref: Phys. Rev. Lett. 100.242001, Butterworth, Davison, Rubin & Salam


Jet Decomposition 1


Jet Decomposition 2

Step 1: Break the jet j into two subjets( j1,j2) by undoing its last stage of clustering s.tmj1 > mj2 .


Jet Decomposition 3

Step 2: a) Significant mass drop (MD),

mj1 < µmj

b) Splitting is nearly Symmetric

y = [min(P2Tj1 ,P2Tj2

)/m2j ]∆R2j1,j2 > ycut

Two parameters µ and ycut are independent of Higgs mass and Higgs pt .

µ = 0.667

ycut = (0.3)2

⇒ Helps to reject/minimize QCD contamination.


Jet Decomposition 4

Step 3: If y> ycut , consider j as heavy particle neighborhood and exit the loop.

Otherwise

Redefine j to be j1 and go back to Step 1.

In practice, above procedure is not optimal for LHC, when the transverse momentumcan be around 250-300 GeV.Since,

mx ∼150 GeV ⇒ Rj1,j2 ∼ 1.0→ Large

⇒ Significant degradation due the Underlying Events (UE)

→ UE ∝ R4j1,j2


Filtering

To minimize UE contamination ⇒ Filter the subjets j1, j2 within a finer angularregion, Rfilt < Rj1,j2Consider 3 hardest pT subjets 2b & gluon

Most Effective result ( In the context of Higgs search)⇒Rfilt = min(Rj1,j2/2, 0.3)

(provided, both the subjets have tagged b’s)


Implications of 98 GeV and 125 GeV Higgs scenario in non-decoupling...

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