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Alexander Belyaev 1
"Implications of the 4-muon signature in the NMSSM"”
Alexander Belyaev
Southampton University & Rutherford Appleton LAB
Implications of the 4-muon signature in the NMSSM
Dark Matter motivated SUSY collider signatures
NMSSM Workshop, November 16-17, 2009, LPT, d’Orsay
In collaboration with Jim Pivarski, Alexei Safonov and Sergey Senkin
Texas A&M University [work in progress]
Alexander Belyaev 2
"Implications of the 4-muon signature in the NMSSM"”
NMSSMNilles, Srednicki, Wyler, Frere, Jones Raby, Ellis, Gunion, Haber, Roszkowski, Zwirner, Drees,
Ellwanger, Rausch, Savoy, Elliott, King, White, Pandita, Ellwanger, Franke, Fraas, Kim
provides an elegant solution to -problem of MSSM
with
NMSSM solves little hierarchy problem of MSSM
“singlino” can play a role of successful DM candidate
rich collider phenomenology, rises no-loose problem/theorem
is replaced with
Alexander Belyaev 3
"Implications of the 4-muon signature in the NMSSM"”
Motivation for pp->h1->a
1a
1->4 signature search
ma1
< 2 mhas not been explored
previously studied: h1 -> a1a
1 -> 4 when 2m < m
a1 < 2m
b
[see Stefano Moretti’s talk]
pp->h1->a
1a
1->4provides with a clean signature of two pairs of
collimated muons
could be a near zero background early LHC search
lack of missing energy allows direct measurement of ma1
, mh1
two tightly-collimated + - pairs leading pT > 20 GeV: negligible background from J/
Alexander Belyaev 4
"Implications of the 4-muon signature in the NMSSM"”
Recent results from D0 on pp->h1->a
1a
1->4 search
Phys.Rev.Lett.103:061801,2009
gg->h1 was assumed to be SM like!
Alexander Belyaev 5
"Implications of the 4-muon signature in the NMSSM"”
TOOLS for production cross sectionNMSSMTOOLS: mass spectra, Br, reduced couplings for NMSSM Higgs
21 ))(()(
1
NMSSMbbh
SMNMSSM GHbbhbb →=→ σσ
( )SM
ggH
NMSSMgghSMNMSSM Hgghgg
→
→
ΓΓ
→=→ 1)(1 σσ
SMggH
NMSSMtotalhSM gghBr
Hgg→Γ
Γ→→= 1
)()( 1σ
SMggH
SMSM HbbHgg →Γ→→ ),(),( σσ
NMSSMbbh
NMSSMtotalh GgghBr
11,),( 1 Γ→
HIGLU, HDECAY: NLO cs, Br, partial width for SM Higgs
Production cross section can be expressed using information above
*
*
[Ulrich Ellwanger, Cyril Hugonie]
[Djouadi,Kalinowski,Spira]
Alexander Belyaev 6
"Implications of the 4-muon signature in the NMSSM"”
MC generators/ME generators
PYTHIA was used in this study with CMS detector parameters from CMS TDR
Recent CalcHEP development allows now to generate events for the whole chain (see talk by Sasha Pukhov)
NMSSM model is in CalcHEP
ggH and H effective vertices are added
User friendly GUI interfacebatch interface – production and decay are in one chain nowcan cross check results in two gaugesOne can implement further modifications of NMSSM using superpotential formalism thought the LanHEP package (one can also use Feynrules, see talks by Benjamin Fuks and by Felix Braam)
Alexander Belyaev 7
"Implications of the 4-muon signature in the NMSSM"”
NMSSM parameter space
superpotentialSoft-breaking
terms
Alexander Belyaev 8
"Implications of the 4-muon signature in the NMSSM"”
NMSSM parameter spacerates and Br are defined by singlet/non-singlet components of h
1 and a
1
a1 is essentially singlet over the entire space including the Peccei-Quinn (k->0) or
R-symmetry limit (A, A -> 0). For example, for A, A -> 0, non-singlet component
is defined by which is small
Alexander Belyaev 9
"Implications of the 4-muon signature in the NMSSM"”
h1 couplings to SM fermions and gauge bosons
also controls the singlet/non-singlet admixture of h1
and its couplings to fermions and gauge bosons
Alexander Belyaev 10
"Implications of the 4-muon signature in the NMSSM"”
Br(a1 -> 2
Alexander Belyaev 11
"Implications of the 4-muon signature in the NMSSM"”
gg->h1 / bb ->h
1 production cross section
Alexander Belyaev 12
"Implications of the 4-muon signature in the NMSSM"”
Parametrer space with constraints
Alexander Belyaev 13
"Implications of the 4-muon signature in the NMSSM"”
Parametrer space with constraints
Alexander Belyaev 14
"Implications of the 4-muon signature in the NMSSM"”
Parametrer space with constraints
is this physical region?
Alexander Belyaev 15
"Implications of the 4-muon signature in the NMSSM"”
pp->h1->a
1a
1->4 signal acceptance study at the LHC
CMS as a benchmarkFiner granularity in muon identication than D0: require 4 muons
highest pT > 20 GeV, all others > 5 GeV
< 2.4
minimize R(1, 2)2 + R(3, 4)2 to pair 1-2 and 3-4
simultaneously fit m12
, m34
, and m1234
spectra: background is mostly smooth function while signal has narrow 3D bump in (m12 , m34 , m1234)
simulated distributions with detector resolution (CMS TDR)
Alexander Belyaev 16
"Implications of the 4-muon signature in the NMSSM"”
Background processes
Electroweak pp->4l: CalcHEP: NegligibleQCD:
2->2 Pythia ● Leptons from heavy flavor,
including J/psi
Direct J/psi+X production (also Pythia): negligible
Fakes from QCD with misidentified muons
● Use 2->2 Pythia with 3 leptons+track smearing with decay probabilities
Alexander Belyaev 17
"Implications of the 4-muon signature in the NMSSM"”
Signal acceptance and cross section limits
Alexander Belyaev 18
"Implications of the 4-muon signature in the NMSSM"”
Tevatron versus LHC reach
Alexander Belyaev 19
"Implications of the 4-muon signature in the NMSSM"”
Tevatron versus LHC reach
Alexander Belyaev 20
"Implications of the 4-muon signature in the NMSSM"”
Tevatron versus LHC reach
Alexander Belyaev 21
"Implications of the 4-muon signature in the NMSSM"”
Conclusions
pp->h1->a
1a
1->4 is a sensitive discovery mode for ma < 2m
D0 search doesn't rule out the large parameter space, SM cs is assumed there, while the NMSSM production CS is suppressed
CMS muon spectrometer allows for identication of all four muons, providing clean signature and significant reach
a1 is essentially signlet, BBAR and CLEO do not exclude light
singlet a1, whose coupling to fermions and gauges bosons
highly suppressed
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