E6SSM vs MSSM gluino phenomenology

0.16 MB·English

by  Patrik Svantesson

E SSM vs MSSM gluino phenomenology
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PatrikSvantessonab,AlexanderBelyaev,JonathanP.Hall,andStephenF.King
UniversityofSouthampton
Abstract. TheE SSMisapromisingmodelbasedonthegroupE ,assumedtobebrokenattheGUTscale,
6 6
2 leadingtothegroupSU(3) SU(2) U(1) U(1) attheTeVscale.ItgivesasolutiontotheMSSMµ-problem
′
1 withoutintroducingmassles×saxions,×gauge×anomaliesorcosmologicaldomainwalls.Themodelcontainsthree
0 familiesofcomplete27sofE ,givingaricherphenomenologythantheMSSM.TheE SSMgenericallypredicts
6 6
2
gluinocascadedecaychainswhichareabout2stepslongerthantheMSSM’sduetothepresenceofseverallight

n neutralinostates.Thisimplieslessmissing(andmorevisible)transversemomentumincolliderexperimentsand
a kinematicaldistributionssuchasM aredifferent.ScansofparameterspaceandMCanalysissuggestthatcurrent
eff
J SUSYsearchstrategiesandexclusionlimitshavetobereconsidered.

4
2
1 Introduction – Inthe NMSSM a cubicterm S3 is addedto breakthe
]
global U(1) to a descrete Z symmetry. The breaking
h 3
p Supersymmetry(SUSY)isapopulartheoryofphysicsbe- ofthisZ3 couldhoweverleadtocosmologicaldomain
- yondthe StandardModel(SM) because by extendingthe wallswhichwouldoverclosetheuniverse.
p
– IntheUSSMtheU(1)isgaugedandamassiveZ bo-
e Lorentzsymmetryintheonlypossiblywayyoufind ′
sonappearinsteadbutthetheoryisnotanomalyfree.
h
[ – AsolutiontotheSMhierarchyproblem, – In the E6SSM the gauged U(1) is a remnant of the
– Adarkmatter(DM)candidate, breaking of a larger gauge group at the GUT scale -

1 – Anindicationofagrandunificationtheory(GUT) E . Anomaliesare cancellednaturallysince the parti-
6
v
– AsupportforStringTheory cleslieincomplete27sofE .
1 6
4 Thesimplest,moststudiedmodel,theconstrainedversion The E6 is broken down to the standard model with one
1 of the minimalsupersymmetricstandardmodel(MSSM), extrasurvivingU(1):
5
isalreadylargelyexcluded.Bothconstraintsfromexperi-
1. mentsandtheoreticalmotivations,e.g.theµ-problem,forces E6 SO(10) U(1)ψ
→ ×
0 us to look beyond the MSSM. To test more complicated SU(5) U(1)χ U(1)ψ
2 → × ×
SUSYmodelsthantheconstrainedMSSMorMSSMone SU(3) SU(2) U(1) U(1)
1 needs to change current search strategies to make them → C× W × Y × N
:
v flexibleenoughtobesensitivetoextensionsoftheMSSM. EachSMgenerationiscontainedina27anditisthesin-
i The study presented here investigates the differences of glet, S, and the two Higgs doublets, H and H , of the
X u d
gluinodecaysinMSSMandtheE inspiredsupersymmet- third 27 that are assumed to acquire VEVs. The particle
6
r
a ricstandardmodel(E6SSM)[1]. content is much bigger in the E6SSM than in the MSSM
or USSM because of these three 27s. Contained in these
2 E SSM 27sthere are, forexample,righthandedneutrinos,which
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areneutralundertheextraU(1)andcanthusbeheavyand
provideasee-sawmechanism.Furthermore,sixmore,nat-
IntheMSSMthereisabilinearHiggscoupling,µ,which
urallylight,neutralinostatesareintroducedinadditionto
needstobeoftheorder1TeVtogiveanacceptableelec-
thesixneutralinosoftheUSSM.Theseneutralinosprovide
troweaksymmetrybreaking.NothingpreventsthisSUSY
a new possible source of dark matter [2] and interesting
preservingcouplingtobeoftheorderofthePlanckscale.
Higgs[3]andgluinophenomenology[9].
To naturally get a µ of order 1 TeV one may extend the
MSSM with a scalar field S, which couples to the Higgs
fields through an interaction λSH H and then let S get 3 Parameterspaces
u d
a VEV, S s . This provides a µ-term with µ = λs.
h i ≡ √2 √2
A consequenceofthisisthata globalU(1)Peccei-Quinn The recent XENON100 experiment [4] puts a bound on
symmetry is introducedand broken. The breaking of this thedirectdetectioncrosssectionfortheLSPandWMAP
U(1)impliestheexistenceofamasslessaxion,whichhas [5]putsaboundonitsrelicdensity.Theseconstraintsex-
notbeenobserved.Therearevariousproposedsolutionsto cludes large portions of the parameter space for SUSY
avoidtheappearanceoftheaxion: models.WehaveusedCalcHEP[6]andMicrOMEGAs[7]
whenscanningtheparameterspacesofMSSMandE SSM
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a PresenteroftheprojectatHCP-2011 topickoutbenchmarkswhichsatisfytheseconstraintson
b e-mail:[email protected] the LSP as well as constraintsfrom colliderexperiments.
EPJWebofConferences
MSSM E6SSM MSSM E6SSM MSSME6SSM
parameter min max min max tanβ 39.2 1.77 χ˜0 149.9 151.2
M1
tanβ 2 60 1.4 2 λ - -0.462 χ˜0 302.8 303.7
M2
|λ| - - 0.3 0.7 s - 5418 χ˜0M3 1580 1766 [G
s - - 3.7 8 µ 1578 (-1770) [G χ˜0M4 1581 1771 eV
µ -2 2 - - [T A -566.1 476.2 eV χ˜±M1 302.8 300.9 ]
A -3 3 -3 3 eV MA 302.5 2074 ] χ˜±M2 1582 1771
MA 0.1 2 1 5 ] M1 150 150 χ˜0U1 - 1909 [G
M2 285 300 χ˜0U2 - 2062 eV
Table1:Tobeabletocomparethemodelsonacommonbasis M - 151 χ˜0 - 45.2 ]
thegauginomasseswerefixedsothatagluinomassof800GeV, m1′ 800.2 800.0 χ˜0E1 - 53.2
g˜ E2
awinomassaround300GeVandabinomassaround150GeV P(l=1) 0.188 <10−5 χ˜0E3 - 141.6
were provided. A common squark and slepton mass scale was P(l=2) 0.812 0.1723 χ˜0E4 - 187.4 [G
fixedtoMS =2TeV.FortheE6SSMalargenumberofYukawa P(l=3) 0 0.7986 χ˜0E5 - 227.8 eV
couplingswerescannedoverwhichisomittedfromthistable. P(l=4) 0 0.02915 χ˜0E6 - 265.6 ]
P(l=5) 0 0 χ˜±E1 - 122.7
χ˜ - 225.1
Ωh2 0.00816 0.0006937 ±E2
Tinhcelusdcianngnbinegncrhemgiaornkss,aarreepprleostetendteidnitnheTapbla.n1eaonfdthpeoLinStsP, σSI 0.38×10−8 16.35×10−8 [pb] t˜h1 111999.20 121064.23 [GeV]
relic density andthe directdetectioncross section in Fig.
Table2:Propertiesoftwochosenbenchmarks.Inthenotationfor
2.Thegluinodecaychainlength,l,relevanthereisdefined
neutralinoandcharginostatesthesubscriptMdenotesaMSSM-
asthenumberofstepsinthegluinodecaychainafterthe
likestate,UaUSSM-likestateandEanE SSM-likestate.This
firstsquarkandillustratedinFig.1. 6
distinctionisreasonablesincethesesectorsareveryweaklycou-
pled.Thefollowingnumberordersthestatesbymass.
g˜ MSSM: q q′ W±(h)
(Primary
Decaychainlength: 1 2 3 4 chain)
Fig.1:Thedefinitionofthegluinodecaychainlength,l. g˜ q˜ χ˜±M1(χ˜0M2) χ˜0M1
MSSM: q q¯
(Secondary
b102 chain)
p
-80 g˜ q˜ χ˜0M1
/1SI10 E6SSM: q q′ W±(h) Z
σ ΓZ→χχ(cid:1)0.0015 GeV (Primary
1 mh(cid:2)114.4 GeV chain)
0.5(cid:1) (cid:1)1.5
1.5(cid:1) (cid:1)2.5 g˜ q˜ χ˜±M1(χ˜0M2) χ˜0M1 χ˜0E1
10-1 2.5(cid:1) (cid:1)3.5
3.5(cid:1) (cid:1)4.5
-2 4.5(cid:1) (cid:1)5.5 Fig.3:Feynmandiagramsfortheleadinggluinodecaychainsfor
10
10-5 10-4 10-3 10-2 10-1 10-5 10-4 10-3 10-2 10-1 1 eachbenchmark.
Ω h2 Ω h2
χ χ
Fig. 2: The scanned regions of the parameter spaces projected
5 Event analysis
onto the plane spanned by the spin independent cross section,
σ , and the relic density, Ωh2. The area right of the solid line
SI
is excluded by XENON100 [4] and WMAP [5]. The colouring
representstheeffectivegluinodecaychainlengthl =P l P(l)
for each point, where P(l) is the probability for aeffchainlle·ngth SincetheE6SSMintroducesnewneutralinos,naturallylig-
ofl,asdefinedinFig.1.ThechosenbenchmarksofMSSMand hterthantheMSSMLSP,thegluinodecaychainswillbe
E SSMareencircled. longerthantheMSSM’singeneral.Thisisconfirmedand
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illustrated by the parameter scans in Fig. 2 and bench-
marks in Tab. 2. An effect of longer decay chains is that
4 Benchmarks therewillbelessmissingmomentaincolliderexperiments.
This affects the conventionalSUSY jets plus missing en-
ergysearches,e.g.[10]and[11],wheretheE SSMisdis-
6
ThebenchmarksconsideredforMCeventanalysisaresum- favouredcomparedtotheMSSM.ThiscanbeseeninTab.
marizedinTab.2,wheretheneutralinospectrumislisted, 3 and Figs. 6 and 7. Another important feature is the in-
andencircledinFig.2.Thesebenchmarksdonotprovidea creaseinleptonaswellasjetmultiplicity,asshowninFig.
sufficientamountofdarkmatterandanothersourceofdark 4. Effective variables for distinguishing models with dif-
matterisassumed.Otherscenarios,whereE6SSMgivethe ferentgluinodecaychainlengths,liketheMSSMandthe
rthigehstaammeoaunnatlyosfisda[9rk],mbuatttaerre[n8o],tphraevseenbteeednhceoren.sidered in Ew6hSeSreMth,earsem/paTllearn/pdT/paTn/dMlaeffr,gwerhMicehff oarfeEp6SloSttMedpiunshFitgh.es5e,
distributionstolowervalues.
HadronCollierPhysicsSymposium2011,Paris,France
-1-1-15 fb5 fb5 fb 10 EM6SSSSMM -1-1-15 fb5 fb5 fb 10 EM6SSSSMM -1-1-1-1-1-1-1-1-1-1-1-1bbbbbbbbbbbb 10
Events @ Events @ Events @ 101-1 Events @ Events @ Events @ 101-1 V @ 5 fV @ 5 fV @ 5 fV @ 5 fV @ 5 fV @ 5 fV @ 5 fV @ 5 fV @ 5 fV @ 5 fV @ 5 fV @ 5 f 1 ttttVVttttVWejVejW
10-2 10-2 GeGeGeGeGeGeGeGeGeGeGeGe WME6SWSSWSMMW
10-3 10-3 20 20 20 20 20 20 20 20 20 20 20 20
111111111111 -1
0 1 2 3 4 5 6 7 0 2 4 6 8 10 12 14 16 //////////// 10
NNNuuummmbbbeeerrr ooofff llleeeppptttooonnnsss NNNuuummmbbbeeerrr ooofff jjjeeetttsss ssssssssssss
tttttttttttt
nnnnnnnnnnnn
Fig.4:Leptonmultiplicity,requiringp >10GeVand η <2.5, eeeeeeeeeeee
T | | vvvvvvvvvvvv
andjetmultiplicity,requiring p >20GeVand η <4.5. EEEEEEEEEEEE
T | | 10-2
0 500 1000 1500 2000 2500 3000
-1-1-1-1vents/20 GeV @ 5 fbvents/20 GeV @ 5 fbvents/20 GeV @ 5 fbvents/20 GeV @ 5 fb 123456 EM6SSSSMM -1-1Events/0.02 @ 5 fbEvents/0.02 @ 5 fb 123456 EM6SSSSMM No01. FAigT.L7A:TS/phCeU>e1Tff3Se0cntolGiivmceeuVimtt ass00E..a01fffM09t.eSrS9FM10CMMMMMMMMMMMMr..aM08ceeeeeeeeeeee01.Sffffffffffffffffffffffffs((((((((((((tGGGGGGGGGGGGy00El..04eeeeeeeeeeeeeffE00c.VVVVVVVVVVVV6uS))))))))))))tSsFM10r..a06c00.
EEEE T
2 pjet1 >130GeV 0.04 0.77 0.03 0.59
0 0 10020030040050060pppp0TTTT7mmmm00iiiissss8ssss00((((GGGG90eeee01VVVV00))))0 00.050.10.150.20.250.30pp.3TT5mm0.ii4ss0ss.//4MM50ee.ff5ff 3 pTTjet2 >40GeV 0.01 0.76 0.00 0.58
4 pjet3 >40GeV 0.11 0.68 0.04 0.56
T
Fig.5: Missingtransverse momentum anditsratiowiththeef- 5 pjet4 >40GeV 0.20 0.54 0.11 0.50
fectivemass,Meff,beforeselectioncuts. 6 ∆φ(/pT,Tjet)min>0.4 0.37 0.34 0.58 0.21
7 /p /M >0.25 0.49 0.17 0.68 0.07
T eff
111111111111 10 CMSCUTS MSSM E6SSM
------------bbbbbbbbbbbb No. limit Eff. Frac. Eff. Frac.
ffffffffffff tt
5 5 5 5 5 5 5 5 5 5 5 5 ttV 0 nocut 0.00 1.00 0.00 1.00
@ @ @ @ @ @ @ @ @ @ @ @ ttVttWejeW 1 H/T >200GeV 0.34 0.66 0.47 0.53
V V V V V V V V V V V V 1 VVj 2 pjet1 >50GeV 0.00 0.66 0.00 0.53
eeeeeeeeeeee WMSWSWMW 3 pTjet2 >50GeV 0.02 0.64 0.01 0.53
GGGGGGGGGGGG E6SSM T
4 pjet3 >50GeV 0.13 0.56 0.06 0.50
000000000000 T
121212121212121212121212 -1 5 ∆φ(/pT,jet1)>0.5 0.02 0.55 0.03 0.48
s/s/s/s/s/s/s/s/s/s/s/s/ 10 6 ∆φ(/pT,jet2)>0.5 0.08 0.50 0.12 0.42
ntntntntntntntntntntntnt 7 ∆φ(/pT,jet3)>0.3 0.07 0.47 0.10 0.38
eeeeeeeeeeee 8 ∆R(jet,lep) <0.3 0.24 0.36 0.36 0.25
vvvvvvvvvvvv min
EEEEEEEEEEEE 9 H >800GeV 0.49 0.18 0.38 0.15
-2 T
10
0 500 1000 1500 2000 2500 3000
MMMMMMMMMMMM ((((((((((((GGGGGGGGGGGGeeeeeeeeeeeeVVVVVVVVVVVV)))))))))))) Table 3: Efficiency of ATLAS and CMS cuts and the fraction
eeeeeeeeeeeeffffffffffffffffffffffff eventsleftaftersuccessiveapplicationsofcuts.
Fig.6:Theeffectivemassafter7ATLASstylecuts References
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Acknowledgements
9. A.Belyaev,J.P.Hall,S.F.KingandP.Svantesson,(In
We would like to thank Alexander Pukhov for necessary
preparation)
improvementsof CalcHEP and MicroMEGAs.PS thanks
10. ATLAS Collaboration, CERN-PH-EP-2011-145,
theNExTinstituteandSEPnetforsupport.ABthanksthe
[arXiv:1109.6572]
NExTInstituteandRoyalSocietyforpartialfinancialsup-
11. CMSCollaboration,[CMS-PAS-SUS-11-004]
port.