Recent results on beyond the standard model Higgs boson searches from CMS

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by  Alexander A. Savin on behalf of the CMS Collaboration

Recent results on beyond the standard model Higgs boson searches from
CMS
AlexanderA.Savin,a onbehalfoftheCMSCollaboration
UniversityofWisconsin-Madison,1150UniversityAve.,MadisonWI53706-1390
2 Abstract. Twoextensionsofthestandardmodel,onethatincludestheseesawmechanismoftypeII,andthe
1 minimalsupersymmetric extentiontothestandardmodel,arestudiedusingupto1.6fb 1 ofdatacollectedin
−
0 proton-protoncollisionsat √s=7TeVwiththeCMSdetectorattheLHC.
2

n
a 1 Introduction Excluded by Tevatron or LEP
J CMS Preliminary CMS s=7 TeV (cid:242) L=0.98 fb-1

4 AnobservationofthedoublychargedcomponentΦ++(here
2 BR(F ++fi e+e+)=100%
andbelowchargeconjugatemodesareimplicitlyincluded)
BR(F ++fi e+m +)=100%
ofthetripletscalarfieldpredictedinthetheminimalsee-
]
x sawmodeloftypeII,wouldestablishsuchmechanismin BR(F ++fi m +m +)=100%
e the most promising framework giving mass to neutrinos. BR(F ++fi e+t+)=100%
p- This particle carries double electric charge and decays to BR(F ++fi m +t+)=100%
e the same charged lepton pairs ℓi+ℓ+j allowing also lepton BR(F ++fi t+t+)=100%
h flavorviolatingdecays.TheΦ++ Yukawacouplingmatrix
[ is proportional to the light neutrino mass matrix and al- BP1: normal hierarchy

1 lows to test the neutrino mass mechanism by measuring BP2: inverse hierachy
v thebranchingfractionsΦ++ ℓiℓj[1]. BP3: degenerate masses
→
3 Theminimalsupersymmetricextensiontothestandard BP4: equal branchings
8 model (MSSM) requires the presence of two Higgs dou- 100 150 200 250 300 350
9 blets.Thisleadstoamorecomplicatedscalarsector,with Lower limit on mass of F ++ [GeV]
4 Fig.1.ObservedΦ++ masslimitsat95%CLindifferentlepton
five massive Higgs bosons: a light neutral CP-even state
. finalstates.Thebranchingfractionsthatareassumedinthelimit
1 (h),twochargedstates(H ),aheavyneutralCP-evenstate
±
calculationareindicated.
0 (H)andaneutralCP-oddstate(A).
2 IfthechargedHiggsbosonmass,m ,issmallerthan
H+
1 thetopquarkmass,thetopquarkcandecayviat H+b
: → nearly degenerate, while that of the h remains near 130
v (anditschargeconjugate).Thelowerlimitonthecharged GeV/c2.Theprecisevalueofthecrossoverpointdepends
i Higgs boson mass is set to about 80 GeV/c2 by LEP ex-
X predominantlyonthenatureofthemassmixinginthetop-
periments.Forvaluesoftanβ,theratioofthevacuumex-
squarkstates.TheneutralMSSMHiggsbosonproduction
r pectation values of the two Higgs boson doublets, larger
a isstudiedinitsdecayintopairoftauleptons,H ττ,in
than20,thechargedHiggsbosonpreferentiallydecaysto →
threefinalstates, whenτdecayleptonically,oneto µand
τ lepton and neutrino, H+ τ+ν . The presence of the
τ othertoe,eµ,andwhenoneoftheτdecayshadronically,
t H+b, H+ τ+ν dec→ay modes alters the standard
τ µτ andeτ [3].
→ → h h
model (SM) prediction of the τ lepton yield in the decay
products of the tt¯ pairs. The current upper limit on the
branchingfraction BR(t H+b) 0.2issetbytheCDF
and D0 experiments at t→he Tevatr≃on for m between 80 2 Doubly charge Higgs boson production
H+
and155GeV/c2,assuming BR(H+ τ+ν)=1.Thedomi-
fnoarnettshoeurccheaorgfetdopHqiugagrskbsoastoLnHiCssiesapr→cph→edtft¯oprrionctehses,stuhbesree-- Both,thepairproductionprocesspp→Φ++Φ−− →ℓi+ℓ+jℓk−ℓl−,
aswellastheassociatedproductionprocesspp Φ++Φ
qanudenttt¯decaHypHrodbub¯cwtshoefnthHetodpecqauyasrkinptaoirτs:lettp¯t→onHan±dWn∓ebub¯- ℓi+ℓ+jℓk−νl are studied, assuming that the Φ++ a→nd Φ+ a−re→
± ∓ ±
→ degenerate in mass. A search is performed for an excess
trino[2].
ofeventsinallpossibleflavourcombinationsofthesame
The mass relations among the neutral MSSM Higgs
chargeleptonpairscomingfromthedecaysΦ++ ℓ+ℓ+
tbhoesopnarsaamreetseurcthanthβatthifemmAas.se1s3o0fGtheeVh/ca2n,datAlaarrgeenveaalrulyesdoef- without making assumptions on the Φ++ branchin→g friacj-
generate,whilethatoftheHisapproximately130GeV/c2. tions. Both the three and four charged lepton final states
If m & 130GeV/c2, thenthe massesof the A and H are areconsideredincludingatmostoneandtwoτleptons,re-
A spectively.The Φ++ W+W+ decaysare assumed to be
a e-mail:[email protected] suppressed. →
EPJWebofConferences
In addition to the model independentsearch, the type
II seesaw model is tested in four benchmark points (BP)
thatcharacterizedifferentcharacteristicneutrinomassma-
trixstructures.BP1describestheneutrinosectorwithnor-
malmasshierarchyanda massless lightestneutrino.BP2
describes the same, but with the inverse mass hierarchy.
BP3representsadegenerateneutrinomassspectrumwith
m = 0.2 eV. Those three benchmark points are the ex-
1
tremesallowedbyvaryingtheneutrinomassandhierarchy
in theallowedrangeswithoutconsiderationforθ orCP
13
phasesandcoveralargeregionoftheparameterspace.The
fourthbenchmarkpointBP4 representsthe case inwhich
allΦ++ branchingfractionsareequal.
Thepresentedresultsarebasedondatacorresponding
to an integrated luminosity of 0.98 fb 1. The final states
−
are required to have four or three leptonswith transverse
momenta, p , above 5 GeV/c for muons and above 15
T
GeV/c for electrons and τ . There should be at least two
h
leptons with p > 35 and 10 GeV/c in the event. The
T
τh arereconstructedusing“hadronplusstrip”(HPS)algo- Fig.2.UpperlimitonBR(t H+b)assumingBR(H+ τν)=1
rithm [4] that is designedto optimize the performanceof as afunction of mH+for the→combination of all final st→ates. The
τhidentificationandreconstructionbyconsideringspecific yellow bands show the one- and two-standard-deviation ranges
τhdecaymodes.Thealgorithmprovideshighτhidentifica- aroundtheexpectedlimit.
tionefficiency,approximately50%fortherangeofτ en-
h
ergiesrelevantforthisanalysis,whilekeepingthemisiden-
tificationrateforjetsatthelevelof 1%thatisfactorof
≈
threetofourtimeslowerthanforthealgorithmsusedinthe
CMSphysicstechnicaldesignreport.Detaileddescription
ofthealgorithmanditsperformancecanbefoundin[4].
ACLsmethodisusedfortheupperlimitcalculations.
Theresultsoftheexclusionlimitcalculationsarereported
in Fig. 1. As can be seen, new significantly higher limits
are set in comparison to the previous LEP and Tevatron
bounds.Thefirstlimitsonfourbenchmarkpointsprobea
largeregionoftheparameterspaceoftypeIIseesawmod-
els.
3 Study of minimal supersymmetric
extensionto the standardmodel
3.1 ChargedHiggsboson
Theanalysisisperformedinthreefinalstates,eµ,µτ and
τ τ , in presence of large missing transverse energyh and Fig.3.TheexclusionregionintheMSSM MH+-tanβparameter
h h spaceobtainedfromthecombinedanalysisfortheMSSMmmax
one b-tagged jet. Transverse momenta of all leptons are h
scenario.
requiredtoexceed20GeV/c,40GeV/cintheτ τ case.
h h
ACLsmethodisusedinordertoobtaintheupperlimit
at95%CL onthe excess(lack)ofthe eventsin compari-
son with the expected contributionsfrom SM. The back- µ = 200 GeV/c2, M2 = 200 GeV/c2, mg˜ = 0.8 MSUSY,
·
ground and signal uncertainties are modeled with a log- X = 2 M (FD calculation), XM¯S = √6 M
t · SUSY t · SUSY
normal probability distribution function and their corre- (RG calculation), A = A. M denotes the common
b t SUSY
lations are taken into account. Assuming that the excess soft-SUSY-breaking squark mass of the third generation;
(lack) of events is due to the t bH+, H+ τ+ν de- X = A µ/tanβ the stop mixing parameter; A and A
t t t b
→ → −
cays,thelimitisobtainedforeachindividualanalysis,and thestopandsbottomtrilinearcouplings,respectively;µthe
also combinedfor all final states. Figure 2 shows the up- Higgsinomassparameter;m thegluinomass;andM the
g˜ 2
perlimitonBR(t H+b)assumingBR(H+ τν)=1asa SU(2)-gauginomass parameter. The value of M is fixed
1
→ →
functionofthehiggsmassforthecombinationofallfinal viatheGUTrelation M = (5/3)M sinθ /cosθ .Inde-
1 2 W W
states.Theupperlimitissetto4-5%fortheHiggsboson termining these bounds on tanβ, we have used the cen-
massinterval80<mH+ <160GeV/c2. tralvaluesoftheHiggsbosoncrosssectionsasafunction
Figure3showstheexclusionregionintheMSSMM - of tanβ reportedby the LHC HiggsCross Section Work-
H+
tanβ parameter space obtained from the combined anal- ing Group. The cross sections have been obtained from
ysis for the MSSM mmax scenario: M = 1 TeV/c2, the GGH@NNLO and HIGLU programs for the gluon-
h SUSY
HadronColliderPhysicssymposium,Paris2011
fusion process. For the bb¯ φ process, the 4-flavor cal-
→
culationandthe5-flavorcalculationasimplementedinthe
BBH@NNLOprogramhavebeencombinedusingtheSan-
tanderscheme.RescalingofthecorrespondingYukawacou-
plings by the MSSM factors calculated with FeynHiggs
hasbeenapplied.Wedonotquotelimitsabovetanβ=60
asthe theoreticalrelationbetweencrosssectionandtanβ
becomesunreliable.
3.2 NeutralHiggsboson
The MSSM neutralHiggsbosonanalysisis performedin
threefinalstateseµ,µτ ,andeτ with p > 15GeV/cfor
h h T
muons,and p > 20GeV/cforeandτ .Ineµfinalstates
T h
one of the lepton is requiredto have p > 20 GeV/c and
T
other p > 10 GeV/c. Each final state is subdivided into
T
two categories, one with no b-tagged jets with p > 20
T
GeV/candtheotherwithatleastoneb-taggedjet.
Fig.4.Theexpectedone-andtwo-standard-deviationrangesand
The largest source of events selected with these re-
observed 95%CLupper limitsonσ B asafunctionofm .
quirementscomes from the SM Z ττ production.The φ· ττ A
→ ThesignalacceptanceisbasedontheMSSMmodeldescribedin
contributionfromthisprocessisestimatedusingasample
thetext,assumingtanβ=30.
ofsimulatedevents,normalizedtothenumberofobserved
Z µµandZ eeeventsindata.Asignificantsourceof
→ →
backgroundarises from QCD multijet eventsand W+jets
eventsin which a jet is misidentified as τ , and thereis a
h
real or misidentified e or µ. The rates for these processes
areestimatedusingthenumberofobservedevents,where
both reconstructed leptons have the same charge, same-
sign combination. Other backgroundprocesses include tt¯
productionandZ ee/µµevents,particularlyinthe eτ
h
→
channel, due to the 2–3% probability for electrons to be
misidentifiedasτ [4].Thesmallfake-leptonbackground
h
fromW+jetsandQCDfortheeµchannelisestimatedus-
ingdata.
TheeventgeneratorPYTHIA,andPOWHEG,andMad-
GraphareusedtomodeltheHiggsbosonsignalandother
backgrounds.TheTAUOLApackageisusedfortaudecays
inallcases.
To distinguish the Higgs boson signal from the back-
Fig.5.Regionintheparameterspaceoftanβversusm excluded
ground, we reconstruct the visible mass, defined as the A
at95%CLinthecontextoftheMSSMmmax scenario,withthe
invariantmass of the visible tau decay products. The ob- h
effectof 1σtheoreticaluncertaintiesshown.Theothershaded
servedvisiblemassdistributionsarefitineachcasetothe ±
regions show the 95% CL excluded regions from the LEP and
sum of the SM backgroundsand the Higgs boson signal. Tevatronexperiments.
The visible mass spectra show no evidence for the pres-
ence of a Higgs boson signal, and are used to set a 95%
CL upperboundonthe productof the Higgsbosoncross
sectionandthetau-pairbranchingfraction,σφ Bττ. eter spaceatlargervaluesofmA. Figure5also showsthe
· regionexcludedbytheLEPexperiments.
Figure4showstheupperboundonσ B asafunction
φ ττ
·
of m , where we use as the signal acceptance model the
A
combinedvisiblemassspectrafromtheggandbb¯ produc-
tion processes for h, A, and H, and assuming tanβ = 30. References
The plot also shows the one- and two-standard-deviation
rangeofexpectedupperlimitsforvariouspotentialexper- 1. CMSCollaboration,CMS-PAS-HIG-11-007,2011,and
imentaloutcomes.Theobservedlimitsarewellwithinthe referencestherein
expectedrangeassumingnosignal. 2. CMSCollaboration,CMS-PAS-HIG-11-008,2011,and
One can interpret the upper limits on σ B in the referencestherein
φ ττ
MSSMparameterspaceoftanβversusm for·anexample 3. CMSCollaboration,CMS-PAS-HIG-11-020,2011,and
A
scenariointhesamewayitwasdoneaboveforthecharged referencestherein
Higgs.TheresultsareshowninFig.5.Theyexcludeare- 4. CMSCollaboration,CMS-PAS-TAU-11-001,2011,ac-
gion in tanβ down to values smaller than those excluded ceptedbyJINST
by the Tevatron experiments for m . 140 GeV/c2, and
A
significantlyextendtheexcludedregionofMSSMparam-