Supersymmetry in the light of LHC experiments

Supersymmetry in the light of LHC

experiments

Free Meson7th April, 2011

Outline

Supersymmtery searches : Results from CMS and ATLAS

Discovery potential

Constraints on SUSY

Implications of those constraints on SUSY models

The Minimal Supersymmetric Standard model(MSSM)

Supersymmetry : particles + sparticles 2 Higgs doublets, coulping mu, ratio of vevs , tanbeta

SUSY is not an exact symmetry, has to be broken.

Presence of soft terms makes larger set of free parameters(100+)

Often assume universality, single m0, single m1/2, single A0, B0 universality assumes at the GUT scale. cMSSM/mSUGRa

NUHM1…

The MSSM: particle content

Couplings are parameter space dependent

SUSY: Signal and Backgrounds

Generic signal:

Tevatron LHCσSUSY increases 20000(!) for mgluino= 400 GeVS/B improves

6

Production Cross SectionsSUSY-discovery challenge

total event rate dominated by huge QCD cross section

reject SM by many orders of magnitude !understand SM events that survive SUSY

selectionProcess Events / s (L=1034cm-2s-1)

W e 150

Z ee 15

t-tbar 8

b-bbar 5x106

Squarks, gluinos (1~TeV) 0.03

Tevatron LHCσSUSY increases 20000 for mgluino=400 GeVS/B improves

SUSY searches at the LHC

Photons + jets +MET

Jets + MET : CMS

For Dijet system 0.5, very useful in suppressing the backgrounds. ̴

HT ≥ 350 GeV

Jets + MET: CMS For multijet system:

No. of jets ≥ 3

Jets + CMS

Jets + CMS

13 events are observed in the data consistent with SM prediction; also the Kinematic properties are consistent with the backgrounds

Jets + CMS

Squark Gluino mass ≥ 650 GeV excluded. ̴

Jets+MET: ATLAS ATLAS 1102.5290

Mass of gluino below 775 GeV are excluded ̴

Lepton + jets + MET: ATLAS

Electron or muons with pt>20 GeV and |eta|< 2.4 3 jets with pt>60,30,30 GeV

phi(jets,met)>0.2, and MT>100 GeV

MET >0.25 MEFF, with Meff > 500 GeV

Background events are estimated from data

ATLAS: 1102.2357

2.2(2.5) events are observed in the electron(muon) channel@95%C.L. 0.065 pb (0.073)pb in the elctron(muon channel

Lepton+jets+MET: ATLAS

Gluino mass >700 GeV excluded

Lepton+jets+MET:CMS and ATLAS

Dilepton(OS/SS) + jets +MET:CMS

Two leptons with at leat one lepton Pt>20 GeV and other lepton Pt>10 GeV

3 jets with PT>30 GeV, |eta|<2.4

MET>50 GeV and HT>100 Gev

Background estimation is from data.

More cleaning cuts

In the data with one event is observed.

Dilepton + jets +MET:CMS

Dilepton+jets+MET:CMSOS SS

Gluino mass > 600 GeV excluded

Dilepton + JETS + MET:ATLAS

Squark masses 450- 600 is ̴excluded

SUSY searches at LHC

2010 Data with L=35/pb

Discovery Potential at 7 TeV(L=1/fb)X. Tata et. al. 1004.3594

Gluino mass upto 1 TeV can be explored with L=1/fb ̴

Discovery Potential at 7 TeV(L=1/fb)MG, Dipan Sengupta. 1102.4785

Transeverse Thurst T<0.9 kills good fraction of QCD background

Discovery Potential at 7 TeV(L=1/fb)MG, Dipan Senputa. 1102.4785

RT < 0.85 suppress backgrounds significantly

Conservative estimates gluino mass 1.1 TeV can be probed for L=1/fb ̴

Backgrounds: top, QCD, W/Z+jets, tbW+jets ttw+jets, WW,WZ,ZZ+jets

Significance is signal rate limited

Constraints on SUSY

Effect of new B->tau+nu data

Bhattacharjee, Dighe,Ghosh,Raychaudhuri,1012,1052

Is large non-SM contribution to B->tau+nu supported by K->mu+nu data? M. Montonelli, et.al 1005.2323

Constraints and Model

Exclusions limits are parameter space sensitive, mainly the leptonic final states

P.Nath et. al. 1103.1197

ATLAS results on lepton and 0 lepton search are used. ObservedNe<2.2, Nmu < 2.5 events. Used same type cuts a la ATLAS.

A0 tanbeta 0 3 0 45 2 m0 45

1 lepton channel

Exclusion m0-m1/2

Largest number of single lepton channel arise at low mass scales, decrease for higher Values;

ATLAS constraints do not rule out any a low mass gluino 400 GeV, ̴ for heavy squark mass

Exclusion m0-m1/2

Flav + Collider elimininates 12% WMAP removes 96.5% alone

Exclusion m0-m1/2

Flav+Collider+WMAP Green region is still un explored.Confirms light gluino mass still alowed.

Confirms CMS and ATLAS limits are consistents

What if the LHC does not find SUSY at 7 TeV run?

K. Desch et .al 1102.4693

Rare decays of B and K mesons

anomalous magnetic moment of muon

EW precision observables LEP, SLC and Tevatron

Higgs boson mass limits(HiggsBounds)

Dark Matter ATLAS jets + MET + 0 lepton results

Used Fittino

Contd..

No LHC results + LHC resultsM0=75(+115-29), m1/2 = 329(+92-83) Tanbeta = 13(+10-7); A0 = 417(+715-725)

M0=270(+423-143), m1/2 = 655(+150-81) Tanbeta = 32(+18-21); A0 = 763(+1238-879)

Contd..

Mass spectrum for Best fit values

Glunio and squark masses are above TeV scale.

Contd..

Squark_R mass TeV ̴ Slepton_R mass 300-500 GeV ̴

NO SIGNAL from LHC at 1/fb will push the masses to higher scales.

Predictions from the LHCGlobal SUSY Fits

Precision EW data

Higgs mass limits(HiggsBounds)

Dark Matter

B decay(s+gamma, mu^+mu^-)

Muon anomalous magnetic moment

Analyze various variation of models.

Frequentist approach(MasterCode)

O.Buchmuller, Ellis et.al 1102.4585

Contd…

No significant reductions in fit probalities No significant tension or conflict

Contd..Fitted Gluino mass

Best fit values migrate to higher masses

CMSSM mSUGRA

Contd..

No Higgs limits used

CMS and ATLAS constraintsare consistent with LEP direct bounds.

Conclusion

CMS and ATLAS predict better bounds on gluinos and squarks masses, still, light gluino mass is allowed for heavy squark mass.

In CMSSM, the CMS and ATLAS has confirm the prediction from indirect constraints.

Global Fitted spectrum shows gluino and squark masses are of the TeV scale. Expect to see signal at 7 TeV LHC with 1/fb. ̴

If not?