Prospects of Charged Higgs Boson Discovery @ Colliders
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Prospects of Charged Higgs Boson Discovery @ Colliders
D. P. Roy
Homi Bhabha Centre for Science Education
Tata Institute of Fundamental Research
Mumbai, India
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• Charged Higgs Boson in the MSSM
• H Lighter than top(t): t bH+
• H Heavier than top : gbtH- (NLO Cont.)
• H± beyond the MSSM : NMSSM & CPVMSSM
• SUSY QCD Correction to H± signature
Outline
0,, WhtbH
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8 States - 3 Goldstone = 5 Physical St : h0, H0, A0& H±
H± carries unambiguous hallmark of MSSM Higgs sectorAll the MSSM Higgs masses & couplings => MA & tan β
01
02
,..,
02
2
,..,1
01 /tan:
ctb
MSSM
222
01
02
012 sinImcosIm,sincos
WAH MMM
AH
RLc
RbLt
Wmscm
btmbtmH
M
gL
tancot
tancot
2
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RLc
RbLt
Wmscm
btmbtmH
M
gL
tancot
tancot
2
mt > MH± => large tbH+ BR at tan β 1 & tan β mt/mb
H± decay: tan β < 1 & tan β > 1
(MH± < 140 GeV) H± cs H± τν=> Deficit in t bW blν
(MH± > 140 GeV) H± t*bWbb => t bH+ bbbW=> b tag excessMoretti & Stirling; Djouadi, Kalinowski & Zerwas; Ma, Roy & Wudka
LL QCD Corr => mq mq(MH±) => mt =170, mb = 3, mc =1 GeV
Pert. Lim. of H±tb coupling => tan β > 1/3 & tan β < 3mt/mb 170
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MH= 140 GeV
tan β ~ 8 problematicUsing τ Pol can helpto enhance Hτν Sigover W Bg
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Production of Heavy H± ( MH > mt ) at LHC
LO
NLO QCD Correction => K 1.5 (Zhu; Plehn et al.)
(a)g
b
t
g
H¯
+
g
b
t
H¯
t
t
g
b
t
t
H¯
g => 0.8 (0.6)
(b) - overlapping cont. from LO => -0.3 (0)
for μF = μR = MH + mt , ( μF = (MH + mt)/5)
t
H¯
b
g
g
tb
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Main BRs of H± (MH>200)
H± tb dominant atall tanβLarge QCD BgSignals with 3 & 4 b-tags
H± Wh(A) main subdominant at small tanβ ~ 3 (BR 5%)Marginal in MSSM(NMSSM & CPV-MSSM)
H± τν main subdominantat large tanβ > 10 (BR~20%)Most promising Signal
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Heavy H± (MH>200GeV) Signal at LHC in hadronic τ decay channel
g
g
t Wbt
Wqqbt 'g
b
t
Wqqbt '
H
jet
h
Sig has much harder pTτ-jet > 100 GeV (Enhanced by τ pol effect).
Azimuthal angle between τ-jet and missing-pT is peaked in backwarddirection for signal ( forward direction for background).
Transverse mass of τ-jet and missing-pT —> MH for Sig (MW for Bg)
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τ-Polarization: 11
,
P
LR
P
RR WH
%)5.7(%),26(%),12( 1 a => 90% of 1-pr.hadronic decay
0,2/1
2/1
V
R
L
H
V = ρ,a1
2/111
2/1
LV
RH
H τ (Pτ =+1) gives hard τ-jet from π,ρL, a1L
W τ (Pτ = -1) gives hard τ-jet from ρT , a1T
Can be distinguishedfrom X = pπ± / pτ-jet
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Raychaudhuri & Roy
Hardness of π± reqd for τ-id=> X > 0.3 (low-X peaks of ρL , a1Linaccessible)
X > 0.8 cut will retain the high-X ρL & π conts ( Pτ = + Signal),while effectively suppressing the ρT ,a1T conts ( Pτ = – bg ).
It will also suppress the fake τ bg from QCD jets effectively.
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Guchait, Kinnunen & Royhep-ph/0608324
Hardness of π± reqd for τ-id => X > 0.3
X > 0.8 cut retains most ofthe remaining Signal, whileeffectively suppressing the Bg.
PYTHIA+TAUOLA+ CMSJET
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p
pR3
3-prong τ-jet without π0
R3 > 0.8 or < 0.4 retains most of the Signal, whilesuppressing the Bg.
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mT > 200 GeV cuteffectively suppresses the Bg withoutaffecting the Signal.Provides estimate ofH± mass.
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H± discovery limit at LHC with luminosity of 30 fb -1 (solid)and 100 fb -1 (dashed lines).
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Detection of H± tb Signal at LHC with 3 b-tags : Moretti & Roy
g
b
t
H¯
t qqbbl
tbttHgbSig
. 3
333 ,, bmistaggedtgtggtbtgbbbttggBG
pT (b3) > 80 GeV
BG large, but5σ Sig possibleat very large (small)tan β
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H± tb Signal at LHC with 4 b-tags: Miller, Moretti, Roy& Stirling
t
H¯tb3
b4
g
g
tb
434: bbttbtHggSigqqbbl
43*: bbttgttggBg
qqbbl
Eb3> 120 GeV
Mbb> 120 GeV
cos θbb < 0.75
pT (b4 )>20 GeV
Better Sig/Bg at the cost of a smaller Sig size compared to the 3 b-tags
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Assamagan, Coadou& Deandrea
..~&..~ HgHqcan fill up intermediate tanβ region for some favorableSUSY parametersDatta, Djouadi, Guchait& Mambrini
Viability of H± tb channel is not supported by the full simulation study:Lowette, D’Hondt &Vanlaer
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Extensions of MSSM (NMSSM & CPV-MSSM)
Low Tanβ ( < 5 ) region: A not observable at LEPMSSM: Mh > 110 GeV => MA > 160 GeV => MH±> 180 GeV
NMSSM: Allows MA1 < 60 GeV with a large doublet component & MH± = 140 - 160 GeV => H± A1W Drees,Guchait & Roy
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CPV-MSSM: hA mixing => light H1 with large A comp, MH1< 60 GeV & MH±= 130-150 GeV => H± H1W±
t bH± bH1W bbbW Ghosh, Godbole & Roy
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t bH± bH1W bbbW
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SUSY QCD Correction : Non-decoupling Hall et al., Carena et al., Coarasa et al.,Bartl et al.
H±
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1&).(
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)1
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mmnessNaturalm
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mmmAm
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Estimate of Δb at Snowmass points & slopes in mSUGRA, GMSB &AMSB => Δb 20% for tanβ 30 ( ΔKSM~ 20%) Plehn et al.