Nuclear Physics B Proceedings Supplement 00 (2014) 1–3
Nuclear Physics B Proceedings Supplement
Search for supersymmetry with Higgs bosons in the final state
Mario Masciovecchio, on behalf of the CMS Collaboration
Institute for Particle Physics ETH Z¨urich 8093 Z¨urich, Switzerland E-mail: [email protected]
Abstract
The recent observation of a Standard Model (SM) like Higgs boson offers the chance to exploit the measured proper- ties of this particle to perform beyond-the-SM searches. A number of searches for Standard Model like Higgs bosons produced in cascade decays of supersymmetric particles are presented, including both strong and weak production mechanisms. A data sample of pp collisions at a center-of-mass energy √
s=8 TeV corresponding to an integrated luminosity of about 19.5 fb−1, collected by the CMS experiment [1] at the LHC, is used. SM-like branching fractions are considered for the Higgs boson, with a massMh0'125 GeV.
Keywords: CMS, supersymmetry, Higgs boson
1. Wh0+Emiss
T
Searches for direct electroweak production of su- persymmetric charginos and neutralinos in final states with a Higgs boson are presented [2, 3]. A chargino- neutralino pair is produced, and decays to a W boson, a Higgs boson, and missing transverse energy from escap- ing lightest supersymmetric particles. Searches explore three channels, depending on the particles detected in the final state: single lepton, same sign dilepton, and multilepton channels. The search performed in the sin- gle lepton final state provides sensitivity to events with a Higgs boson decaying ash0 → bb. The search in¯ the same sign dilepton final state targets events with a Higgs boson decaying ash0 → W+W−, where one W boson decays semi-leptonically, and the other hadroni- cally. Finally, the search in the multilepton final states is targeting events where the Higgs boson decays as h0 → W+W−,h0 → ZZ, and h0 → τ+τ−. The data are consistent with the Standard Model backgrounds (Fig. 1). Results are used to set constraints on the mass of charginos and neutralinos up to 204 GeV (Fig. 2).
[GeV]
b Mb 0 50 100 150 200 250 300 350 400 450 500
Events / 50 GeV
0 5 10 15 20 25
Data 2l top-quark 1l top-quark b νb
→ l WZ
b W+b W+light jets Rare Total Uncertainty
) (200/1) 0 χ∼1 )(H 0 χ∼1
→ (W 0 χ∼2
± χ∼1 = 8 TeV L = 19.5 fb-1 s CMS
> 100 GeV miss ET
[GeV]
Mljj
0 100 200 300 400 500 600 700
Events / 20 GeV
0 2 4 6 8 10 12 14 16 18 20
Data Genuine SM SS Non-prompt lepton Charge misID Total uncertainty
(130/1) x 5 0) 1 χ∼
0)(H 1 χ∼
(W±
→ 0 2
±χ∼
1 χ∼
= 8 TeV L = 19.5 fb-1 s CMS
Figure 1: Results of searches for Wh0+EmissT final states.
[GeV]
0 2
=mχ∼
± χ∼1
m
150 200 250 300 350 400
[GeV]0 1χ∼m
0 20 40 60 80 100 120 140
95% CL upper limit on cross section (fb)
102 103 = 8 TeV L = 19.5 fb-1 s
CMS
95% CL CLs NLO Exclusions theory σ
±1 Observed
experiment σ
±1 Expected
= mH 0 1 - mχ∼
0 2 mχ∼
± 1 χ∼
0 2 χ∼
pp→ 0 1 H χ∼
→ 0 2 χ∼
0 1 W χ∼
±→ 1 χ∼
Figure 2: Interpretation of searches for Wh0+EmissT final states.
/Nuclear Physics B Proceedings Supplement 00 (2014) 1–3 2
2. h0h0+Emiss
T
A search for electroweak pair production of higgsi- nos, both of which decay to a Higgs boson and an al- most massless lightest supersymmetric particle is pre- sented [4, 5]. Each Higgs boson is reconstructed in its decay to abb¯ pair, and the escaping lightest super- symmetric particles lead to missing transverse energy in the event. Three mutually exclusive samples of events with tagged b jets are defined: 2b sample, 3b sample, and 4b sample. The sample most sensitive to signal events is the 4b sample. The 3b sample is added to improve signal efficiency, while the 2b sample is only used for background evaluation. The data are consistent with the Standard Model predictions within uncertain- ties (Fig. 3). For higgsino masses between about 270 and 350 GeV, the expected 95% confidence level up- per limits on the cross section reach the predicted pro- duction cross section. Because of a slight excess in the observed number of events, compared to the estimated background, no exclusion is obtained for any higgsino mass value (Fig. 4).
bin 1
SMET SMET bin 2 SMET bin 3 SMET bin 4
Events / S bin
0 5 10 15 20 25
3b sample 0 = 250 GeV 1 χ∼
Signal, m = 400 GeV 0 1 Signal, mχ∼
Data Background estimate
= 8 TeV s , CMS Preliminary, L = 19.3 fb-1
bin 1
SMET SMET bin 2 SMET bin 3 SMET bin 4
Events / S bin
0 2 4 6 8
104b sample 0 = 250 GeV 1 χ∼
Signal, m = 400 GeV 0 1 Signal, mχ∼
Data Background estimate
= 8 TeV s , CMS Preliminary, L = 19.3 fb-1
Figure 3: Results of search for h0h0+EmissT final states.
(GeV)
0 1
Higgsino mass mχ∼
150 200 250 300 350 400 450 500 550
refσ/σ95% CL upper limit on
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
σexp.
± 1 Expected
σexp.
± 2 Expected Observed
= 8 TeV s -1, CMS Preliminary, L = 19.3 fb
≈ 0 ; mLSP 0 χ∼1
≈ m
± χ∼1
≈ m 0 χ∼2 m
Figure 4: Interpretation of search for h0h0+EmissT final states.
3. MT2Higgs
A search designed for events that contain a Higgs bo- son in the decay chain of a heavy SUSY particle is de- scribed. Assuming Higgs bosons decay primarily to a bb¯ pair in accordance with the Standard Model branch- ing fraction, this category of events is investigated to seek an excess at 125 GeV in the invariant mass distribu- tion of the selected b-tagged jet pairs. Theh0boson can
be produced together with the lightest supersymmetric particle in the decays of neutralinos, such as ˜χ02→h0χ˜01. The final state chosen to be considered comprises at least two b jets, multiple hard jets, and significant MT2 caused by the production of ˜χ01. The data are found to agree with Standard Model prediction (Fig. 5), and re- sults are interpreted for the following model: gluino pair production, with one gluino decaying via ˜g → qq¯χ˜02, with ˜χ02 → h0χ˜01, and the other gluino decaying via
˜
g → qq0χ˜±1, with ˜χ±1 → W±χ˜01. The search excludes at the 95% confidence level gluinos with masses M( ˜g) up to about 825 GeV, and M( ˜χ01) up to about 410 GeV (Fig. 6).
[GeV]
Mbb 20 40 60 80 100 120 140 160 180 200
Events / 15 GeV
0 2 4 6 8 10 12 14 16 18 20
Lost lepton )+jets ν ν Z(
T5Wh - 750,350 Data low HT
= 8 TeV, L = 19.5 fb-1 s CMS Preliminary,
[GeV]
Mbb 20 40 60 80 100 120 140 160 180 200
Events / 15 GeV
0 2 4 6 8 10 12 14 16 18 20
22 Lost lepton
)+jets ν ν Z(
T5Wh - 750,350 Data high HT
= 8 TeV, L = 19.5 fb-1 s CMS Preliminary,
Figure 5: Results of search for fully hadronic final states with a Higgs boson, usingMT2.
(GeV)
gluino
m 400 500 600 700 800 900 1000 (GeV)LSPm
0 100 200 300 400 500 600 700 800 900 1000
10-1
1 = 8 TeV s -1, CMS Preliminary, 19.5 fb
1 χ0 h0 2→ χ0 2, χ0 q q 2→
g~ 1
χ0 W± 1→ χ± 1, χ± q q 1→ g~
NLO+NLL exclusion g2
~ g1
→~ pp
theory σ
± 1 Observed
σexp 1/2
± Expected
95% C.L. upper limit on cross section (pb)
Figure 6: Interpretation of search for fully hadronic final states with a Higgs boson, usingMT2.
4. Higgs boson from s-top decay
A search for direct top squarks pair production fol- lowed by decays to Higgs bosons is performed using events with one or two electrons or muons and several jets, with at least three jets identified as originating from a b quark [6, 7]. Events are classified according to the lepton multiplicity, and charge requirements on the lep- tons. Four event categories are considered. The first two include events with one lepton, or two opposite sign
/Nuclear Physics B Proceedings Supplement 00 (2014) 1–3 3
leptons, with at least three b jets. The other two cat- egories are events with exactly two same sign leptons, and events with three or more leptons, with at least one b jet. Signal regions are defined with requirements on the transverse massMT, or the invariantbb¯pair mass,Mbb¯, to be consistent with the Higgs boson mass of 125 GeV.
The observed yields in the signal regions agree with the predicted backgrounds within the assessed uncer- tainties (Fig. 7). The results are interpreted in the con- text of a simplified model with pair production of a top squarks ˜t2, decaying to a top squarks ˜t1via a Higgs bo- son. The search excludes at the 95% confidence level top squarkss with masses M(˜t2) up to about 530 GeV, andM(˜t1) up to about 350 GeV (Fig. 8).
2 OS ℓ analysis CMS √s= 8 TeV, ∫ℒdt = 19.5 fb−1
[GeV]
mbb
0 50 100 150 200
Events / 25 GeV
0 10 20
30 3b
[GeV]
mbb
0 50 100 150 200
Events / 50 GeV
0 10 20
30 Data
t Dileptonic t t Semileptonc t Rare SM SM +˜t2→H˜t1
≥ 4b
m(˜t2,˜t1) = (450, 200) GeV
Figure 7: Results of search for direct top squarks pair production fol- lowed by decays to Higgs bosons.
[GeV]
t2
m~
300 400 500 600 700
[GeV]1t
~ m
200 300 400 500
102 103
H = m t1
m~
− t2
m~
CMS √s= 8 TeV, ∫ℒdt = 19.5 fb−1
1 χ0 t∼ 1→
~t 1H,
~t 2→
~t
*, t2
~ t2
→~ pp
= 175 GeV
0 χ1
m∼
−
1
~t m NLO+NLL exclusion
theory 1 σ Observed ±
experiment σ 1
± Expected
95% CL upper limit on cross section [fb]
Figure 8: Interpretation of search for direct top squarks pair produc- tion followed by decays to Higgs bosons.
5. Higgs boson from s-top and Higgsino decay
A search for a natural supersymmetry scenario with gauge mediated symmetry breaking is presented [8].
Complete Gauge Mediated Supersymmetry Breaking (GMSB) models are considered, with a minimal num- ber of accessible supersymmetric partners to satisfy the naturalness requirements, namely the right-handed top squarks and the higgsino (i.e., the supersymmetric part- ner of the Higgs boson). The lightest chargino ( ˜χ±1)
and neutralinos ( ˜χ01,χ02) are almost pure higgsinos and almost mass-degenerate. Pairs of higgsinos are pro- duced either directly through electroweak production or through ˜tRpairs (strong production). The ˜χ±1 and ˜χ02hig- gsinos decay into a very off-shell W or Z boson and a χ˜01. The lightest neutralino always decays as ˜χ01 →h0G,˜ or ˜χ01 → ZG, where ˜˜ Gis the gravitino. Events are se- lected in which the Higgs boson decays to two photons, and there are at least two b jets. No evidence for signal is found and lower limits at the 95% confidence level are set, excluding the top squarks mass below 360 to 410 GeV, depending on the higgsino mass (Fig. 9).
(GeV) tR
m~
200 300 400 500
(GeV)0 1χ∼m
200 300 400 500
Observed 95% Cross Section Exclusion (pb)
0 0.5 1 1.5 2 2.5 3 3.5
+ 5 GeV + χ∼1 = m 0 χ∼2 5 GeV, m
− + χ∼1 = m 0 χ∼1 m
) = 1, Strong and EW Production G~
→ H 0 χ∼1 Br(
Natural GMSB Higgsino model
Observed 95% CLs Limits Theory uncertainty Expected 95% CLs Limits
experimental σ
±1 Expected
= 19.7 fb-1 t d
∫L = 8 TeV, s CMS,
Figure 9: Interpretation of search for GMSB scenarios with a Higgs boson in the final state.
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