Leptogenic Supersymmetry Andrea De Simone Massachusetts Institute - - PowerPoint PPT Presentation
SUSY 09, Northeastern University June 7, 2009 Leptogenic Supersymmetry Andrea De Simone Massachusetts Institute of Technology Based on arXiv:0903.5305 with J. Fan, V. Sanz, W. Skiba Leptogenic Supersymmetry SUSY 09 OUTLINE What is
Massachusetts Institute of Technology
Based on arXiv:0903.5305 with J. Fan, V. Sanz, W. Skiba
June 7, 2009
Leptogenic Supersymmetry
Andrea De Simone (MIT) 1/18 SUSY 09
Yet another SUSY model? No... A particular ordering of the SUSY spectrum. Not interested in how the hierarchy of masses gets generated at high energies. Look at what LHC can access. Striking and unusual collider signatures.
Leptogenic Supersymmetry
Andrea De Simone (MIT) 2/18 SUSY 09
g, m˜ q > m˜ χ0, m˜ χ± > m˜ ℓL > mh, m˜ ℓR
Leptogenic spectrum: ˜ ℓR ˜ ℓL ˜ q ˜ g ˜ χ stable Energetic Jets Leptons Leptons Higgses charged Many leptons are produced in cascade decays
Leptogenic Supersymmetry
Andrea De Simone (MIT) 3/18 SUSY 09
˜ ℓR ˜ ℓL ˜ q ˜ g ˜ χ
stable charged
Jets Leptons Leptons Higgses
Gauginos heavier than scalars. All sleptons lie at the bottom. The decay chains pass through , and produce many leptons. NLSP : long-lived, collider stable. No significant missing energy! (SUSY models with neutralino LSP, give large ). Gravitino LSP, no role at colliders.
/ ET
Lepto-SUSY spectrum
Leptogenic Supersymmetry
Andrea De Simone (MIT) 4/18 SUSY 09
˜ ℓR ˜ ℓL ˜ q ˜ g ˜ χ
stable charged
Jets Leptons Leptons Higgses
Lepto-SUSY spectrum
Higgs is produced in slepton
Several classes of models give rise to a Lepto-SUSY spectrum (GMSB with large Nmess, Gaugino mediation at low-scale, AMSB ...) ...or just the MSSM in a region of its parameter space h → b¯ b
Leptogenic Supersymmetry
Andrea De Simone (MIT) 5/18 SUSY 09
600 800 1000 1200 1400 1600 1800 2000 mq
GeV
0.001 0.01 0.1 1 10 Σ pb
√s = 14 TeV
pp → ˜ q¯ ˜ q + ˜ q˜ q + ¯ ˜ q¯ ˜ q pp → ˜ q˜ g
Strong production cross- section. Squark-pair production is the dominant process.
Leptogenic Supersymmetry
Andrea De Simone (MIT) 6/18 SUSY 09
600 800 1000 1200 1400 1600 1800 2000 mq
GeV
0.001 0.01 0.1 1 10 Σ pb
√s = 14 TeV
Typical final state of squark cascade decays: 2 jets + (2,3,4) leptons + 2 stable charged tracks No significant missing energy.
˜ q ˜ q χ+ j χ0 j ˜ ℓL ν ℓ ˜ ℓR ℓ ℓ ˜ ℓR p p →
pp → ˜ q¯ ˜ q + ˜ q˜ q + ¯ ˜ q¯ ˜ q pp → ˜ q˜ g
Strong production cross- section. Squark-pair production is the dominant process.
Leptogenic Supersymmetry
Andrea De Simone (MIT) 6/18 SUSY 09
LS1: squark masses ~ 1 TeV LS2: squark masses ~ 520-700 GeV sleptons ~ 110 GeV Higgs ~ 115 GeV 10 TeV 14 TeV
LS1
680 2170
LS2
5040 13700 Lepto-SUSY is not in ATLAS/CMS benchmark points!
Production cross-section (fb)
Leptogenic Supersymmetry
Andrea De Simone (MIT) 7/18 SUSY 09
mass (GeV) gluino: m˜
g
1938 neutralinos: mχ0
1
271 mχ0
2
302 mχ0
3
353 mχ0
4
676 charginos: mχ±
1
291 mχ±
2
676 Higgs: mh0 115 mH0 379 mA 379 mH± 387 µ 294
119 sleptons: m˜
ℓR
108 m˜
ℓL
248 m˜
ν
236 m˜
τ1
106 m˜
τ2
249 squarks: m˜
uL
949 m˜
uR
920 m ˜
dL
952 m ˜
dR
919 m˜
t1
920 m˜
t2
962
100 200 300 400 500 600 700 800 900
˜ ℓR ˜ ℓL
χ0
1
χ0
2
χ0
3
χ0
4
χ±
1
χ±
2
˜ qR ˜ qL
GeV
Leptogenic Supersymmetry
Andrea De Simone (MIT) 8/18 SUSY 09
Fast sleptons (β > 0.9) misidentified as muons
slepton0.6 0.7 0.8 0.9 1 Number of Events 2000 4000 6000 8000 10000
β˜
ℓ
Many sleptons are very fast in the signal
0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1
0.6 0.7 0.8 0.9 1
ATLAS
Long-lived sleptons hits like muons with lower β
[ATLAS TDR 2008]
Leptogenic Supersymmetry
Andrea De Simone (MIT) 9/18 SUSY 09
Mass reconstruction of several sparticle states. Higgs can be discovered in the mode. Almost background-free. Statistically significant excesses of events already at low luminosity (≤ 1 fb-1). h → b¯ b Focus on channels with: 2 hard jets ≥ 4 lepton-like particles
(leptons or stable sleptons)
TLeading jet p 200 400 600 800 1000 1200 1400 Number of Events/20 GeV 10 20 30 40 50 60 70 80 90
L=1 fb
T Leptogenic Supersymmetry
Andrea De Simone (MIT) 10/18 SUSY 09
New channels for SUSY searches!
˜ q ˜ q χ0 j χ0 j ˜ ℓR ℓ ˜ ℓR ℓ p p →
10 TeV 14 TeV
220 690
Events at
0.2 fb-1
45 140 seen as muons Event selection: (including sleptons) with standard cuts
|ηjet| < 2.5 , |ηℓ| < 2.5 pjet
T > 15 GeV ,
p ℓ
T > 10 GeV
∆Rjj,ℓℓ,ℓj > 0.4
nℓ = 4
njet ≥ 2
Leptogenic Supersymmetry
Andrea De Simone (MIT) 11/18 SUSY 09
˜ q ˜ q χ0 j χ0 j ˜ ℓR ℓ ˜ ℓR ℓ p p →
It allows mass reconstruction. Channel with no MET. No MET cut imposed. χ0
1, χ0 3, ˜
q
mjℓ˜
ℓ
mℓ˜
ℓ
Hard cuts on the of the leading jet can be applied and suppress the BG efficiently. All SM BGs are below 1 fb.
pT
Leptogenic Supersymmetry
Andrea De Simone (MIT) 12/18 SUSY 09
OSL pairs selected according to minimal ΔR separation.
lepton-slepton mass(GeV) 200 220 240 260 280 300 320 340 360 380 400
Number of Events/5 GeV/1 fb 20 40 60 80 100 120
χ0
1
χ0
3
dilepton mass(GeV) 200 220 240 260 280 300 320 340 360 380 400
Number of Events/5 GeV/1 fb 10 20 30 40 50 60
χ0
1
χ0
3
sleptons identified
sleptons misidentified
jet+lepton+slepton mass (GeV) 800 850 900 950 1000 1050 1100
Number of Events/10 GeV/1 fb 5 10 15 20 25
˜ qR
Further pairing with the nearest jet
Leptogenic Supersymmetry
Andrea De Simone (MIT) 13/18 SUSY 09
Standard lore: No Higgs searches in b-bbar, due to large BG. In Lepto-SUSY: Higgs is copiously produced in slepton decays , and then decays to b-bbar. BG efficiently suppressed by lepton multiplicity.
˜ ℓL → h ˜ ℓR
h → b¯ b
Leptogenic Supersymmetry
Andrea De Simone (MIT) 14/18 SUSY 09
˜ q ˜ q χ0 j χ0 j ˜ µ1(˜ τ1) ℓ ℓ ˜ µ2(˜ τ2) h0 ˜ ℓR ¯ b b p p →
Analysis (simple-minded and conservative):
ask for and
assume 1st and 2nd jets are from squarks form invariant mass of 3rd and 4th jets
nℓ = 3, 4 njet ≥ 4
˜ q ˜ q χ0 j χ0 j ˜ µ1(˜ τ1) ℓ ℓ ˜ µ2(˜ τ2) h0 ˜ ℓR ¯ b b p p →
1 2 3, 4 µ µ τ, µ 10 TeV 14 TeV
100 320
Events at
0.2 fb-1
20 64
NB: No b-tagging. Not precisely known at early stages.
Leptogenic Supersymmetry
Andrea De Simone (MIT) 15/18 SUSY 09
(GeV)
dijetm 50 60 70 80 90 100 110 120 130 140 150 Events/10 GeV 20 40 60 80 100 120
>
T3P 100 GeV 200 GeV 300 GeV
, Etm < 40 GeV (LS2)
L= 1 fb
(GeV)
dijetm 60 70 80 90 100 110 120 130 Events/10 GeV 20 25 30 35 40 45
, Etm < 40 GeV (LS2)
L= 1 fb
(GeV)
dijetm 60 70 80 90 100 110 120 130 Events/10 GeV 6.5 7 7.5 8 8.5 9
, Etm < 40 GeV (LS1)
L= 1 fb
(GeV)
dijetm 50 60 70 80 90 100 110 120 130 140 150 Events/10 GeV 6 7 8 9 10 11 12 13 14 15 16
>
T3P 100 GeV 300 GeV
, Etm < 40 GeV (LS1)
L= 1 fb
14 TeV to 10 TeV is a factor of ~1/3
Combinatorial BG: more detailed analysis needed. Under study by ATLAS coll.
Z h0 h0 Z LS 1 LS 2
Leptogenic Supersymmetry
Andrea De Simone (MIT) 16/18 SUSY 09
The ease of multi-leptonic channels (~absence of BG) implies a tremendous discovery potential of LHC. The discovery of the stable slepton is possible with the very first data. Most of the sparticle spectrum can be reconstructed (at least 10 clean events) with Prospects of Higgs discovery in the channel may be good with ≤ 1 fb-1 at 14 TeV. Significance of this channel requires full simulation. h → b¯ b
(for TeV-squarks)
Leptogenic Supersymmetry
Andrea De Simone (MIT) 17/18 SUSY 09
Leptogenic SUSY spectra are characterized by many leptons in the final state of pp collisions. They arise in several well-motivated models. Extremely clean (almost BG-free) channels. One of the most “LHC-friendly” SUSY scenarios. Different from standard SUSY searches. Relevant for very early stage of LHC. It can be discovered/ruled out with ~ 0.2 fb-1 at 10 TeV.
Leptogenic Supersymmetry
Andrea De Simone (MIT) 18/18 SUSY 09
Leptogenic Supersymmetry
Andrea De Simone (MIT)
18/18
SUSY 09
Leptogenic SUSY spectra are characterized by many leptons in the final state of pp collisions. They arise in several well-motivated models. Extremely clean (almost BG-free) channels. One of the most “LHC-friendly” SUSY scenarios. Different from standard SUSY searches. Relevant for very early stage of LHC. It can be discovered/ruled out with ~ 0.2 fb-1 at 10 TeV.
Andrea De Simone (MIT)
Andrea De Simone (MIT)
SM background in (3,4) leptons + 4 jets: +jets, W/Z+jets, WZ+jets, ZZ+jets, QCD jets. Rate for jets faking leptons ~ 10-4 (ATLAS TDR) b-decay producing isolated leptons ~ 5 10-3 Significant cross-section suppression: e.g. for QCD jets faking 4 leps: 108 pb x (10-4)4 = 10-5 fb Possibility to apply hard cuts on
without losing signal. Efficient BG suppression. t¯ t pT
TLeading jet p 200 400 600 800 1000 1200 1400 Number of Events/20 GeV 10 20 30 40 50 60 70 80 90
L=1 fb
T
Andrea De Simone (MIT)
SM BGs generated with ALPGEN and MG. All < 1 fb after the cuts: nℓ ≥ 3 nj ≥ 4 pj1
T
> 200 GeV pj4
T
> 25 GeV nµ ≥ 2 p(ℓ)
T
> 50 GeV ∆Rℓ ℓ,ℓ j,j j > 0.4
Andrea De Simone (MIT)
combinatorial BG
(GeV)
dijet
m 60 70 80 90 100 110 120 130 Events/5 GeV 4 5 6 7 8 9 10 11
CUTS
T,missE < 30 GeV
T,missE < 50 GeV
T,missE < 70 GeV
T,missE
L= 1 fb
Varying missing ET cuts
Andrea De Simone (MIT)
Only apply to slepton pair production (8 fb in our case). Not constrained by TeVatron
[Search for charged massive stable particles with D0 detector (2008)]
Mass [GeV] 50 100 150 200 250 300 Cross section [pb]
10
10
10
10
10 1 10 Mass [GeV] 50 100 150 200 250 300 Cross section [pb]
10
10
10
10
10 1 10
Observed Cross Section Limit Expected Cross Section Limit NLO Cross Section Prediction NLO Cross Section Uncertainty
DØ 1.1 fb (a)
Cross section [pb] Cross section [pb]
Andrea De Simone (MIT)
˜ q ˜ q χ+ j χ0 j ˜ ℓL ν ℓ ˜ ℓR ℓ ℓ ˜ ℓR p p → ˜ q ˜ q χ+ j χ0 j ˜ νL ℓ ℓ ˜ ℓR ℓ ν ˜ ℓR p p →
(GeV) R l ~ 2l M 100 200 300 400 500 600 700˜ ℓL
(GeV) T R l ~ l+ M 100 200 300 400 500 600 700˜ νL 10 TeV 14 TeV
137 426
Events at
0.2 fb-1
27 85
due to neutrino mass reconstr. also possible with transverse mass.
˜ χ± / ET
Andrea De Simone (MIT)
˜ q ˜ q χ0
3−4
j χ0
1−2−3
j ˜ ℓL ℓ ˜ ℓR ℓ ˜ ℓ′
R
ℓ ℓ′ p p →
10 TeV 14 TeV
70 225
Events at
0.2 fb-1
14 45
3 leptons + slepton mass(GeV) 200 300 400 500 600 700 800 900˜ χ0
3
˜ χ0
4
, other neutralinos and squarks can also be reconstructed but with lower statistics than in .
˜ ℓL 4 ℓ
Andrea De Simone (MIT)
Model-independent parametrization of soft masses: : dimensionless numbers. In the Higgs sector: Assuming gaugino mass unification, and A=0, 7 parameters:
˜ m2(R) =
3
C2(Ri)Ki
Ki = αi π m2
i n2 i
ni
δ ≡ −m2
Hd + m2 Hu = −α3λ2 t
4π3 m2
3n2 4
m3, ni (i = 1, 2, 3, 4), tan β, sign µ
Parameter Range n1 [2, 5] n2 [0.5, 6] n3 > 1.8 n4 > 1.75
Parameter space
Our benchmark point:
m3 2000 GeV n1 4.8 n2 3.9 n3 2.2 n4 6.7 tan β 10 sign µ +
Andrea De Simone (MIT)
Lepto-SUSY spectra are realized for . Examples: Gaugino mediation at low-scale: no large log contribution from RGE. Gauge mediation with large : Supersoft SUSY breaking: D-term SUSY breaking is communicated to the visible sector through higher dim operators. Scalar masses naturally suppressed wrt gaugino masses. Nm ni = O(1 − 10) ni ∝ 1 √Nm π αi