Supersymmetry and dark matter search: prospects and challenges
Biplob Bhattacherjee Kavli IPMU University of Tokyo
Wednesday, 27 November 13 1 Observation of a new boson with mass ~125-126 GeV
Properties: roughly consistent with Standard Model Higgs boson
Wednesday, 27 November 13 2 New physics search: Large Hadron Collider
No hint of new physics !!
Wednesday, 27 November 13 3 New physics search: dark matter FERMI-LAT
inconclusive results in the
-27 ] 10 2 10-28 CMS Preliminary CMS 2012 Vector dark matter sector XENON- 100 s = 8 TeV CMS 2011 Vector 10-30 CDF 2012 L dt = 19.5 fb-1 XENON100 2012 -32
CMS 10 " COUPP 2012 SIMPLE 2012 -34 10 CoGeNT 2011
-36 CDMSII 2011 10 CDMSII 2010
10-38 (!$ !)(q$µq) 10-40 µ #2 10-42
-Nucleon Cross Section [cm -44
! 10 Spin Independent 10-46 1 10 102 103 2 M! [GeV/c ] Wednesday, 27 November 13 4 Standard Model vs new physics
Standard Model should not be the ultimate theory
Experimental facts
1. Baryon Asymmetry of the Universe 2. Dark matter (and dark energy?) 3. Neutrino mass
Theoretical issues
1. Flavour structure 2. Hierarchy problem 3. Gauge coupling unification
Wednesday, 27 November 13 5 Observation of a new boson with mass ~125-126 GeV
Is it Standard Model Is it SM Higgs ? Higgs ?
What kind of new physics models are consistent with present LHC data ?
Wednesday, 27 November 13 6 Supersymmetry
Wednesday, 27 November 13 7 Supersymmetry (SUSY)
Standard Model Supersymmetric Particle Particle
Quark Squark (example: top (Example: Stop quark) squark)
Gauge boson gaugino (example: (example: gluon) gluino)
Wednesday, 27 November 13 8 Supersymmetry (SUSY)
SM Particle SUSY Particle
One of the most attractive new physics option (dark matter , gauge coupling unification, hierarchy problem may be explained)
Broken symmetry (otherwise electron mass= Selectron mass= 0.5 MeV.. excluded.. no such particle observed) many breaking mechanisms more than 100 parameters in the low energy description
Wednesday, 27 November 13 9 Supersymmetry Higgs self coupling is not a free parameter, λ determined by gauge couplings( tree level)
Tree level mass M M H ≤ Z
Wednesday, 27 November 13 10 Supersymmetry Higgs self coupling is not a free parameter, λ determined by gauge couplings( tree level)
Tree level mass M M H ≤ Z
Higher order correction
No quadratic divergence dominant contribution from Stop squarks (superpartner of top quark)
Wednesday, 27 November 13 11 Higgs boson and Supersymmetry
Is 125 GeV Higgs too heavy for SUSY ?
Wednesday, 27 November 13 12 Option 1 : Heavy stop squarks Higgs mass depends on stop masses : log sensitivity Assume all squarks are heavy
Wednesday, 27 November 13 13 Option 1 : Heavy stop squarks Higgs mass depends on stop masses : log sensitivity Assume all squarks are heavy Required stop mass ~ a few TeV to hundreds of TeV ! Impossible to observe at LHC Does it mean that other SUSY particles are also hundreds of TeV range ?
Fig: BB, B. Feldstein, M. Ibe, S. Matsumoto,T. Yanagida, PRD 2012
Wednesday, 27 November 13 14 Option 1 : Heavy stop squarks Higgs mass depends on stop masses : log sensitivity Assume all squarks are heavy Required stop mass ~ a few TeV to hundreds of TeV ! Impossible to observe at LHC Does it mean that other SUSY particles are also hundreds of TeV Verificationrange ? ?? very difficult No
Fig: BB, B. Feldstein, M. Ibe, S. Matsumoto,T. Yanagida, PRD 2012 Chance to observe sparticles other than stop squarks at the LHC
Wednesday, 27 November 13 15 Option II : Large stop squark mixing
Increase X t parameter
Very large X t value does not help √ Optimal value: Xt(OPT ) = 6Mt˜
X t appears in the off diagonal component of stop squark mixing matrix
Large X t large stop squark mixing Measurement of stop mixing matrix is very important
Shelton, Many works in this direction.. Perelstein, Krohn, BB, Mandal, Nojiri, Belenger et.al., ...... Wednesday, 27 November 13 16 Option II : Large stop squark mixing
Increase X t parameter
Very large X t value does not help √ Optimal value: Xt(OPT ) = 6Mt˜ Verification ?? X t appears in the off diagonal component of stop squark mixing matrix Not always possible
Large X t large stop squark mixing Measurement of stop mixing matrix is very important
Shelton, Many works in this direction.. Perelstein, Krohn, BB, Mandal, Nojiri, Belenger et.al., ...... Wednesday, 27 November 13 17 Option III: Add new particles/interactions
S= gauge singlet scalar Add λSHuHd
New contribution in tree level Higgs mass λv sin 2β
large contribution for Two additional scalars very small tan β complicated small loop correction from Higgs phenomenology stop is sufficient for 125 GeV Higgs
Observations of more than 2 neutral Higgs bosons are required for verification
Wednesday, 27 November 13 18 Option IV : Observed Higgs boson is not the lightest Supersymmetric Higgs boson
In MSSM 2 CP even Higgs bosons h1 and h2 Mh2 ~ 125-126 GeV and Mh1 < 125 GeV possible LEP experiment observed excess around 98 GeV
Drees, Is this h1 ?? Asano et.al. , Christensen et.al., Ellawanger et.al., Djouadi......
Wednesday, 27 November 13 19 98 GeV Higgs MSSM vs NMSSM This possibility is still allowed both in MSSM AND NMSSM
MSSM NMSSM BB, M. Chakraborti, A. Chakraborty, U. Chattopadhyay, D. Das, D. Ghosh, PRD 2013 Model independent discovery of 98 GeV Higgs is not possible at the LHC Proposed International Linear Collider can discover lighter Higgs boson easily
Wednesday, 27 November 13 20 Various Supersymmetric models are consistent with present Higgs data
Light SUSY particles are not disallowed by Higgs data
What is the status of supersymmetry direct search at the LHC ?
Wednesday, 27 November 13 21 Possibilities
Low scale SUSY is not realized in nature
Low energy theory Standard Model
SUSY particles are heavier than current limit
small production Observation in cross section near future Light SUSY particles are present and search channels are not very sensitive
large signal cs and Observation in background is also high near future
Wednesday, 27 November 13 22 Supersymmetry search R- parity conserved
Pair production of SUSY particles
Wednesday, 27 November 13 23 Supersymmetry search R- parity conserved
Lightest SUSY particle is stable (dark matter candidate) Missing transverse energy
Wednesday, 27 November 13 24 Supersymmetry search R- parity conserved
Final state
Jets + leptons + missing transverse energy
Wednesday, 27 November 13 25 Supersymmetry search R- parity conserved
A particular event
3 jets + 2 muons + 1 electron
Calculate missing transverse energy
Wednesday, 27 November 13 26 Search variables for Large Hadron Collider (LHC)
Missing transverse p/ = ( p )2 +( p )2 T − x − y momentum(MET) ! px,py x and y component of visible momentum Expectation : SM: neutrino is the only source of missing energy SUSY: Massive invisible particle High p/ T Effective mass meff = p/ T + pT + pT (MEFF): jets ! leptons! Expectation : It reflects the mass scale of the event SUSY particles are much heavier than SM SUSY Effective Mass distribution is much harder than SM
Wednesday, 27 November 13 27 MET and MEFF 1 Measurement of p_x,p_y,p_z, E of visible particle possible Invisible
Proton Proton(z axis)
PX = px1 + px2 + px3
PY = py1 + py2 + py3 3 2 p/ = ( P )2 +( P )2 T − X − Y m = p/ + p + p + p Invisible eff !T T1 T2 T3 2 2 pT = px + py "
Wednesday, 27 November 13 28 SUSY Searches (CMS and ATLAS)
SUSY Search heavily depends on meff and p/ T
ATLAS-CONF-2013-047 CMSSM , 8 TeV LHC mg˜ = mq˜ =1.7 TeV looks very Is low scale SUSY ruled out ? strong
Understand the assumptions behind this bound
R parity conservation Assumption 1: (missing energy) a particular mass hierarchy Assumption II: (wide mass gap between squark gluino and lightest neutralino)
Wednesday, 27 November 13 29 Effective Mass (Parton level)
gluino pair production and gluino decay to lightest neutralino
High effective mass for signal Effective mass peaks at low value for background (Separation of signal and background very easy) Mg˜ = 1 TeV M ˜0 = 100 GeV χ1
Wednesday, 27 November 13 30 Effective Mass (Parton level)
Mg˜ = 1 TeV M ˜0 = 900 GeV Mg˜ = 1 TeV M ˜0 = 100 GeV χ1 χ1
Wednesday, 27 November 13 31 Effective Mass (Parton level)
Effective mass depends on the mass difference , not the actual mass
Mg˜ = 1 TeV M ˜0 = 900 GeV Mg˜ = 1 TeV M ˜0 = 100 GeV χ1 χ1 For compressed Supersymmetry the bound is drastically reduced compared to normal case
Wednesday, 27 November 13 32 Effective Mass (Parton level)
Future reach at the LHC Gluino ~ 1 TeV Gluino ~ 2.5 TeV
LeCompte et.al., Dreiner et.al BB, K. Ghosh BB, Chaudhuri, Ghosh, Poddar Mg˜ = 1 TeV M ˜0 = 900 GeV Mg˜ = 1 TeV M ˜0 = 100 GeV χ1 χ1 For compressed Supersymmetry the bound is drastically reduced compared to normal case
Wednesday, 27 November 13 33 7/8 TeV results
BB, K. Ghosh hep-ph:1207.6289 7 TeV 8 TeV
LeCompte et.al., 7/8 TeV bound on gluino ~ 500-600 GeV Dreiner et.al BB, K. Ghosh
Wednesday, 27 November 13 34 14 TeV Cut flow
BB, Chaudhury, Ghosh, Poddar hep-ph: 1308:1526
Wednesday, 27 November 13 35 LHC reach
BB, Chaudhury, Ghosh, Poddar hep-ph: 1308:1526
Gluino mass discovery limit ~ 725 GeV Exclusion ~ 1.2 TeV
Wednesday, 27 November 13 36 SUSY search Two broad categories R- parity violated
A typical SUSY event
Wednesday, 27 November 13 37 SUSY search Two broad categories R- parity violated
Lightest SUSY particle is not stable
Small or no missing transverse energy
Relatively higher particle multiplicity
Wednesday, 27 November 13 38 SUSY search Two broad categories R- parity violated
1. hard jets / leptons and particleLightest multiplicity SUSY can particle be used for exclusion/discovery is not stable
2. Bound is comparable to the R-paritySmall or conserving no missing case if leptons are present in thetransverse decay energy
3. If the decay mode does not containRelatively leptons, higher bound may be weaker particle multiplicity
Wednesday, 27 November 13 39 LHC current bounds indicate that the new particles will possibly be heavy
Assumption: New particles will be produced at the 14 TeV LHC
The decay of new heavy particle to SM particles may give large Lorentz boost
Wednesday, 27 November 13 40 Top quark production t bW ~ 100 % decay → W lepton(e/µ/τ) + neutrino W quark + quark → → ~33% ~67%
Wednesday, 27 November 13 41 Top quark production t bW ~ 100 % decay → W lepton(e/µ/τ) + neutrino W quark + quark → → ~33% ~67% isolated electron/muon
Wednesday, 27 November 13 42 Technical Difficulty : Example :1 j1 j2
j3
j4
lepton
neutrino
Wednesday, 27 November 13 43 Technical Difficulty : Example :1 Invariant mass of j1 j2 j3 j1 gives top 1 j2
j3
Expectation j4
lepton
top quark 4 momentum neutrino measurement possible from missing transverse energy, lepton and jet
Wednesday, 27 November 13 44 Technical Difficulty : Example :1 j1 Jet merging Heavy Z’~ 2-3 TeV j2 very high pT top quarks j3
non isolated Text lepton
j4 Actual lepton j6
Wednesday, 27 November 13 45 Technical Difficulty : Example :1 j1 Jet merging Heavy Z’~ 2-3 TeV j2 very high pT top quarks j3
non isolated Text lepton
j4 lepton
Conventional method fails j6
Wednesday, 27 November 13 46 Technical Difficulty : Example :1 j1 Jet merging use t --> q q q mode instead of t -->q l nu j2 j3
Text
Jet merging j4 j5 j6
Wednesday, 27 November 13 47 Technical Difficulty : Example :1
Solution : increase the jet area Fat jet 1
Substructure inside the fat jet
Fat jet 2
Wednesday, 27 November 13 48 Technical Difficulty : Example :1
Solution : increase the jet area Fat jet 1
Fat jet 2
In reality, there are many technical challenges... multiple interaction, pile up, QCD mistagging... One of the most active field of research in collider physics Wednesday, 27 November 13 49 Technical Difficulty : Example :2
Identification of top,W,Z, Higgs are difficult
Long SUSY cascade
Wednesday, 27 November 13 50 Technical Difficulty : Example :2
Identification of top,W,Z, Higgs are difficult
Solution: For high boost of W/Z/Higgs we can identify top/W/Z/Higgs jet using jet-substructure technique
Many applications : Very important for LHC 14 TeV run
Wednesday, 27 November 13 51 Low mass supersymmetric particles are not excluded (True for other new physics options)
Chance to observe at 14 TeV Large Hadron Collider (New techniques may be required )
However, the current LHC bound may not be improved drastically
Wednesday, 27 November 13 52 Is there any direction where we can expect many orders of magnitude improvement in near future?
Low mass SUSY particles are not excluded
More study is required to exclude/discover Supersymmetry / New physics
However, the current LHC bound may not be improved drastically
Wednesday, 27 November 13 53 Dark matter
What we know 1. Many evidences 2. Weakly interacting
What we do not know
1. Mass ? 2. Charge ? 3. Interactions with SM particles? 4. Stable or unstable ? 5. Equal no of dark and anti dark matter ?
Wednesday, 27 November 13 54 Detection of DM (direct detection) DM DM
Exchange of SM/ new particle
SM SM
Wednesday, 27 November 13 55 Detection of DM (direct detection) DM DM
1. Recoil of detector nuclei (Energy measurement) Exchange of SM/ 2. Very effective for spin-independent interaction new particle 3. Future limit can be improved by a factor of ~ 1000
SM SM For very light dark matter , recoil energy is very small
Not very effective
Wednesday, 27 November 13 56 Detection of DM (Collider search)
DM Proton Exchange of SM/new particle
Proton DM
No missing transverse momentum : no trigger
Wednesday, 27 November 13 57 Detection of DM (Collider search)
DM Proton Exchange of SM/new particle
Proton DM Impossible to observe
No missing transverse momentum : no trigger
Wednesday, 27 November 13 58 Detection of DM (Collider search)
DM Proton
Proton DM Visible
Photon, jets, gauge bosons ......
Wednesday, 27 November 13 59 Detection of DM (Collider search)
DM Proton
Signature : Mono-jet , Mono photon plus missing transverse energy (ChanceProton to see dark matter DMat the LHC) Visible
radiation from internal leg
Photon, jets, gauge bosons ......
Wednesday, 27 November 13 60 Detection of DM (Collider search)
DM AdvantageProton : 1. This method also important for very low mass dark matter (unlike direct detection) 2. Equally good for spin-dependent and spin-independent interactionsProton DM Visible Disadvantage: Need interaction with quark/gluon Not muchradiation improvement from internal in future leg Interactions with top/bottom quark is Photon, jets, gauge bosons ...... difficult to probe even in future (BB, Choudhuri, Harigaya, Matsumoto, Nojiri, JHEP 13)
Wednesday, 27 November 13 61 Detection of DM (Indirect Detection) SM SM Gamma, DM neutrinos, or DM positron, DM anti- SM proton.. SM Advantage : It may cover wide energy range (GeV to Tens of TeV) Disadvantage : huge uncertainty in better Astrophysical background than LHC ? wino dark matter in High scale type of SUSY scenario future bound from gamma ray telescopes using dwarf spheroidal galaxy data may be better than LHC (BB, Ibe, Ichikawa, Matsumoto.. in preparation)
Wednesday, 27 November 13 62 Higgs dark matter portal
Coupling of dark and visible sectors is through Higgs
Scalar DM φDM† φDMH†H renormalizable
Fermionic DM χDMχDMH†H
Another Possibility: χDMχDMφ φ and mixes with Higgs
Wednesday, 27 November 13 63 Dark matter and Higgs boson
DM Higgs Invisible Higgs decay Possible ?
DM
Br(H -> DM DM) ~ 20 % is still allowed
International Linear Collider can probe Br(H -> DM DM) up to 0.6% ...... very effective
Wednesday, 27 November 13 64 Conclusion
• SUSY : many possibilities consistent with 125 GeV Higgs • It is too early to think that SUSY is excluded • Precise measurements of Higgs properties required (LHC, ILC ?) • Dark matter bounds may be improved by orders of magnitude within a decade.
Thank you.
Wednesday, 27 November 13 65 Extra Slides
Wednesday, 27 November 13 66 Possibilities B. Large stop mixing Xt
arXiv:0811.1024
arXiv:1112.2703
Wednesday, 27 November 13 67 Light fermionic Asymmetric dark matter
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−4 8./%96:; −4 10 ./%/0$$1%234%567% 10 "!"#$ 9:$:;<<$=$4>/$?12 "!"#$ !
−6 9<0((6="># −6 10 ,?$F?:?#G%?;%# 8./%8>>")":0("?> 10 Mixing Angle (sin ) Mixing Angle (sin ) −8 −8 10 10 0 1 2 3 0 1 2 3 Mediator Mass (GeV) Mediator Mass (GeV) BB, Matsumoto, Mukhopadhyay, Nojiri, JHEP 2013
Wednesday, 27 November 13 68 quark High Scale SUSY quark
gluino virtual wino squark
arXiv:1210.0555
Wednesday, 27 November 13 69 Wednesday, 27 November 13 70