Tau04, Nara, September 2004

How to trigger on How to trigger on leptons: practical examples in CMS leptons: practical examples in CMS identificationidentification the importance of the importance of s in SUSY Higgsess in SUSY Higgses the use of the use of s in SUSY searches and measurementss in SUSY searches and measurements

Roberto Chierici 2

CMSCMSCALORIMETERS:

ECAL Scintillating PbWO4

Crystals HCAL Plastic scintillator

copper sandwich

Pixels and Silicon Microstrips

TRACKER(s)

MUON BARREL

Drift Tube Chambers (DT)

Resistive Plate Chambers (RPC)

Cathode Strip Chambers (CSC)Resistive Plate Chambers (RPC)

MUON ENDCAPS

<2.4<2.4<3<3

<5<5

SUPERCONDUCTING COIL (B=4 Tesla)

Total weight : 12,500 tOverall diameter : 15 mOverall length : 21.6 mMagnetic field : 4 Tesla

IRON YOKE

ee

Tau04, Nara, September 2004

Roberto Chierici 4

Triggering on Triggering on ss

22 R

Dedicated High Level Trigger (HLT) algorithms for Dedicated High Level Trigger (HLT) algorithms for identification are identification are essential to select events where essential to select events where s are produced in the final state, down to s are produced in the final state, down to relatively low Erelatively low ETT. . (benchmark channel: MSSM Higgs decays A/H(benchmark channel: MSSM Higgs decays A/H, H, H++))

Final state signatures involve either 1Final state signatures involve either 1 hadronic, 2 hadronic, 2s hadronic, 1s hadronic, 1 hadronic hadronic and 1 lepton.and 1 lepton.The trigger of The trigger of decays into lepton are part of the e and decays into lepton are part of the e and triggers. triggers.

Key features of Key features of detection and trigger: detection and trigger: s decay hadronically 65% of the time and in 77% of these there is only one s decay hadronically 65% of the time and in 77% of these there is only one charged hadron and a number of charged hadron and a number of 00s (one-prong decays)s (one-prong decays) jets at the LHC are slim, 90% of the energy is is contained in a ‘cone’ of jets at the LHC are slim, 90% of the energy is is contained in a ‘cone’ of radius radius R=0.2 around the jet direction for ER=0.2 around the jet direction for ETT>50 GeV >50 GeV

Designing a HLT scheme is tough:Designing a HLT scheme is tough: cuts must be tuned to reach the allowed rate for a certain channel: for cuts must be tuned to reach the allowed rate for a certain channel: for s s this is this is a few Hz from the initial 100KHza few Hz from the initial 100KHz selection must be fast enough to reach the wanted ratesselection must be fast enough to reach the wanted rates high luminosity conditions are the more demanding for setting up a : on high luminosity conditions are the more demanding for setting up a : on average 17.3 average 17.3 minimum bias events and contribution from 8 out of time bunch crossings minimum bias events and contribution from 8 out of time bunch crossings are are superimposed to every event. superimposed to every event.

Roberto Chierici 5

Level 1 and 2 Level 1 and 2 trigger with trigger with calorimetrycalorimetryA generic jet is first triggered with calorimetry as a 12x12 A generic jet is first triggered with calorimetry as a 12x12

group of towers whose central 4x4 Egroup of towers whose central 4x4 ETT is larger than the E is larger than the ETT in in all its neighbours.all its neighbours.A A jet is a generic jet in which in none of the nine 4x4 jet is a generic jet in which in none of the nine 4x4 regions regions there are more than 2 towers with Ethere are more than 2 towers with ETT>2,4GeV>2,4GeV

One must maintain the One must maintain the jet L1 trigger rate at a few KHz jet L1 trigger rate at a few KHz levellevel 1 1 jet with E jet with ETT>90 GeV or 2 >90 GeV or 2 jets with E jets with ETT>60 GeV>60 GeV

low lumilow lumi high lumihigh lumi

The level 2 calorimeter The level 2 calorimeter trigger is then based on a cut on the trigger is then based on a cut on the electromagnetic isolation parameter pelectromagnetic isolation parameter pisolisol = = EETT

em em (R<0.40)(R<0.40) – – EETTem em (R<0.13)(R<0.13)

A pA pisolisol cut of about 5 cut of about 5 GeV provides a factor GeV provides a factor 3 in 3 in the trigger rate the trigger rate reductionreduction

A,HA,HjetjetjetjetX vs QCDX vs QCD

ppisolisol<1 <1 GeVGeV

ppisolisol<10 <10 GeVGeV

Roberto Chierici 6

Level 2 Level 2 trigger using tracking trigger using tracking

RRmm,, RRss,, ppTTmm andand ppTT

ii are optimized for one are optimized for one and three-prong and three-prong decays in A/H decays in A/H

Reconstruct tracks with pReconstruct tracks with pTT>1GeV using >1GeV using only pixelsonly pixels Find primary verticesFind primary vertices The highest pThe highest pTT track (tr1) with good track (tr1) with good L2L2 jet matching:jet matching: --R(j-tr1)< R(j-tr1)< RRmm (~0.1) and p (~0.1) and pTT(tr1)> (tr1)> ppTT

m m (~3 GeV) (~3 GeV)

defines the primary vertexdefines the primary vertex count the tracks from the primary vertex in the count the tracks from the primary vertex in the isolation coneisolation cone and in the and in the signal conesignal cone - N- Nii: tracks with : tracks with R(j-track)< R(j-track)< RRii (~0.3) (~0.3) - N- Nss: tracks with : tracks with R(tr1-track)< R(tr1-track)< RRss (~0.05) (~0.05)

- p- pTT(track)> (track)> ppTTi i (~1 GeV) (~1 GeV)

accept as accept as candidates only if tracks are found in the candidates only if tracks are found in the signal cone (Nsignal cone (Nss=N=Nii))

ID with full tracker : the same “isolation” idea , but ID with full tracker : the same “isolation” idea , but using tracks found via a regional search with the silicon using tracks found via a regional search with the silicon tracker tracker

Roberto Chierici 7

A/HA/H jet jet jetjet TriggerTrigger

HLT path efficiency

CPU, ms

Calo+Pxl 0.41 59

Calo+Trk 0.45 130

Calo+Pxl vs Calo+Trk Path: Calo+Pxl vs Calo+Trk Path: efficiency for a Higgs boson of mass 200 GeV/c2 and CPU for background suppression 103 at L = 2 x 1033cm-

2s-1

low lumilow lumi high lumihigh lumi

Higgs efficiency vs QCD rejection with varying RRi i (0.2-0.5)(0.2-0.5)

With the same background rejection the Calo+Trk is more robust and efficient, but more time consuming…

Calo+Pxl for the Calo+Pxl for the leading leading jet. jet.

Pxl for the second jetPxl for the second jet

No strong dependence No strong dependence on the Higgs masson the Higgs mass

Roberto Chierici 8

Other examplesOther examples

Further criteria to the single Further criteria to the single trigger must be added to lower trigger must be added to lower the global rate.the global rate. Requirements on the pRequirements on the pTT of of the leading trackthe leading track Track trigger is the most Track trigger is the most appropriateappropriate

Single Single jetjet trigger trigger

Mixed eMixed ejetjet, , jetjet triggers triggers

example: Hexample: H++jetjet

example: A/Hexample: A/H l l jetjet Adding mixed triggers significantly increases Adding mixed triggers significantly increases the efficiency w.r.t. single lepton triggersthe efficiency w.r.t. single lepton triggers

relative 5-10% increase can be easily relative 5-10% increase can be easily obtainedobtained

EETT(e) thresholds(e) thresholds

high lumihigh lumi

Roberto Chierici 9

3D flightpath in mm Background efficiency

Sig

nal effi

cie

ncy

Offline Offline jet identificationjet identification After HLT there are different ways studied and under study to improve the After HLT there are different ways studied and under study to improve the -jet selection-jet selection cuts on the jet propertiescuts on the jet properties: : low multiplicity low multiplicity (1 or 3 charged tracks in a small cone (1 or 3 charged tracks in a small cone around the jet axis defined with calorimetry)around the jet axis defined with calorimetry) isolation isolation (no other tracks with p(no other tracks with pTT>1GeV/c in a broader >1GeV/c in a broader

cone around the jet axis)cone around the jet axis) momentum of the leading track momentum of the leading track (typically p(typically pTT

leadingleading>40GeV/c)>40GeV/c)

cuts on the reconstructed cuts on the reconstructed impact parameter impact parameter:: In case of two In case of two s the combined IP significance can be s the combined IP significance can be used as a discriminant variableused as a discriminant variable cuts on the cuts on the decay vertex decay vertex:: a measure of the flight path cana measure of the flight path cangreatly help in QCD rejectiongreatly help in QCD rejection

cuts on the vertex masscuts on the vertex mass::work is ongoing on the mass work is ongoing on the mass reconstruction…reconstruction…

)()( 22

2112 IPIP

arb

itra

ry u

nit

s

Tau04, Nara, September 2004

Roberto Chierici 11

SUSY heavy Higgs sector and SUSY heavy Higgs sector and The SM(-like) Higgs discovery potential has already been discussed in the The SM(-like) Higgs discovery potential has already been discussed in the previous talk.previous talk.

The MSSM Higgs to The MSSM Higgs to couplings are enhanced with tan( couplings are enhanced with tan() (like for b quarks)) (like for b quarks) for medium-high tan(for medium-high tan() the dominant production ) the dominant production mechanism for the neutral Higgs is in association mechanism for the neutral Higgs is in association with b production (90% for tan(with b production (90% for tan()=10))=10)

Charged Higgses are produced via g-b fusion Charged Higgses are produced via g-b fusion gbgbHH++t or via g-g fusion ggt or via g-g fusion ggHH++tb.tb. This is particularly convenientThis is particularly convenient for the high mass region.for the high mass region. The most promising decayThe most promising decay channel is given by Hchannel is given by H++,,especially for high tan(especially for high tan() values.) values.

Most important backgrounds involve W+jets or Z+jets with Most important backgrounds involve W+jets or Z+jets with decays of the decays of the bosons.bosons.QCD is most important when looking at hadronic QCD is most important when looking at hadronic decays, bb especially decays, bb especially important if leptonic important if leptonic decays are investigated. decays are investigated.

Essential tools: IP reconstruction, b tagging, pEssential tools: IP reconstruction, b tagging, pTTmissmiss resolution resolution

Roberto Chierici 12

MSSM ggMSSM ggbbA/HbbA/Hbbbb

m(m() with l+j and two jet modes after selections) with l+j and two jet modes after selections

The Higgs mass can be reconstructed assuming The Higgs mass can be reconstructed assuming that the that the s are emitted along the measured s are emitted along the measured decay productsdecay products project pproject pTT

missmiss onto the directions of the two onto the directions of the two jets jets )cos1)()((2 212211 jjjjH EEEEm

)sin(/ 21 jjmissTH pm

MSSM HMSSM H studied in all its decay chain: studied in all its decay chain:BR(HBR(HeX) eX) 6.3% 6.3% BR(HBR(HeeX+eeX+X) X) 12.5% 12.5%BR(HBR(HjetX+ejetX) jetX+ejetX) 45.6% 45.6% BR(HBR(Hjetjet) jetjet) 41.5% 41.5%

Main backgrounds:Main backgrounds:

Z,Z,**,,ℓℓℓℓtttttWtWbbbb

W+jetW+jetQCDQCD

cuts after HLT:cuts after HLT:

lepton isolationlepton isolationstricter stricter tagging tagging

b-taggingb-taggingjet vetojet veto

positive Epositive E solution solution

Roberto Chierici 13

Discovery potential for neutral H Discovery potential for neutral H into into

essential agreement between ATLAS and CMS essential agreement between ATLAS and CMS reaches reaches

MSSM A/HMSSM A/H: : discovery reach in mdiscovery reach in mAA – tan( – tan() plane for m) plane for mHHmaxmax scenario scenario

Complementary to hComplementary to h (in the low value region of m (in the low value region of mAA). The overall discovery ). The overall discovery potential potential heavily depends on this channel. heavily depends on this channel. Most of the contribution to the 5Most of the contribution to the 5 contours comes from the hadronic contours comes from the hadronic contribution. The contribution. The lepton channels suffer from more background.lepton channels suffer from more background.

Roberto Chierici 14

A tan(A tan() measurement) measurement

significance significance larger than 5larger than 5

tan(tan() can be measured by counting H events (assuming known A) can be measured by counting H events (assuming known A00, , , m, m1/21/2, , mmSUSYSUSY)) main systematic uncertainties come from theory uncertainties on the main systematic uncertainties come from theory uncertainties on the cross-sections cross-sections and branching ratios and on the luminosity and branching ratios and on the luminosityThe measurement is dominated by A/HThe measurement is dominated by A/H whereas H whereas H++ gives a factor 2-3 gives a factor 2-3 worse statistical error.worse statistical error.

theory errortheory errordominatesdominates

Roberto Chierici 15

MSSM gbMSSM gbHH++tttt

For high mFor high mHH++, high tan(, high tan() the BR(H) the BR(H++) is about 10%. For low m) is about 10%. For low mHH

++, H, H++ dominatesdominatesMain backgrounds are semileptonic tt decays, W+jets and Wt production where Main backgrounds are semileptonic tt decays, W+jets and Wt production where WW

are involvedare involved

polarization in Hpolarization in H++ decays is opposite to W decays is opposite to W++ decays:decays:

in in decays from H decays from H++ are preferentially emitted are preferentially emitted in thein the

direction opposite to the direction opposite to the flight in the flight in the rest rest frameframe

harder pions are expected in harder pions are expected in jets from H jets from H++

Fully reconstruction of the t hadronic Fully reconstruction of the t hadronic decay and b tagging greatly reduce the decay and b tagging greatly reduce the backgrounds. backgrounds.

A final cut on mA final cut on mTT(() completely separate ) completely separate the signal and allows a mass the signal and allows a mass reconstructionreconstruction

Low efficiency selection, but very high Low efficiency selection, but very high purities can be reached (>90%)purities can be reached (>90%)

(( included) included)

Roberto Chierici 16

s in SUSY eventss in SUSY events

If SUSY exists et the EW scale, gluinos and squarks will be copiously produced If SUSY exists et the EW scale, gluinos and squarks will be copiously produced at the LHCat the LHCIn the decay chain the final products are fermions and the undetected LSP (if In the decay chain the final products are fermions and the undetected LSP (if R-parity is conserved)R-parity is conserved)

production is important because:production is important because: Yukawa couplings are larger for the third Yukawa couplings are larger for the third generation and are also enhanced for high generation and are also enhanced for high values of tan(values of tan()) With large values of tan(With large values of tan() in mSUGRA the ) in mSUGRA the is predicted to be the lightest slepton is predicted to be the lightest slepton higher probability for producing higher probability for producing in the in the charginos and neutralinos decay chain.charginos and neutralinos decay chain.

For SUSY events triggering on For SUSY events triggering on s is less important than for Higgses because of s is less important than for Higgses because of the distinctive signature of the missing Ethe distinctive signature of the missing ETT from the undetected LSP. from the undetected LSP.

%04.0)( 01

02 BR

%4.16)~

( 01

02 BR

%2.83)~( 01

02 BR

0;0;10tan;250;100 02/10 AGeVmGeVm

For high values of tan(For high values of tan() decay into ) decay into s largely dominate (s largely dominate (100%)100%)

~~

100%100%

100%100% 30%30%

Roberto Chierici 17

Proliferation of Proliferation of ss

tau-jet tau-jet

tan= 35, > 0tan= 35, > 0

tan= 10, > 0tan= 10, > 0Within mSUGRA one can count the expected Within mSUGRA one can count the expected -jet-jetmultiplicity per event. The probability of having at multiplicity per event. The probability of having at least one least one -jet per event can go up to 0.8 in certain-jet per event can go up to 0.8 in certainregions of the parameter space ! regions of the parameter space !

A large tan(A large tan() makes the Yukawa couplings to b and) makes the Yukawa couplings to b and increase and at the same time increases the massincrease and at the same time increases the massmixing in the third family, making the mixing in the third family, making the lighter lighter

Multi-Multi- production also increases drastically with production also increases drastically with increasing tan(increasing tan())

The ridge function of mThe ridge function of m00, m, m1/21/2 corresponds to the corresponds to the allowed phase space points where decays of allowed phase space points where decays of 22

00 and and11

into sleptons are allowed into sleptons are allowed

The domains where The domains where and b are produced abundantly and b are produced abundantly are complementary and cover most of the parameterare complementary and cover most of the parameterspace. space. Excellent tracking is essential. Excellent tracking is essential.

~~

all gluino and squarks decayall gluino and squarks decaymodes accounted for modes accounted for

Roberto Chierici 18

reconstructionreconstruction~~

For high tan(For high tan() using ) using s is a s is a necessitynecessity, and , and the di-lepton edge mass reconstruction is the di-lepton edge mass reconstruction is spoiled because of the spoiled because of the decay. decay.Use Use hadronic decays (missing E hadronic decays (missing ETT comes also comes alsofrom the undetected LSP) and subtract same from the undetected LSP) and subtract same sign di-sign di- masses to greatly reduce the MSSM masses to greatly reduce the MSSM backgrounds. SM backgrounds are suppressed backgrounds. SM backgrounds are suppressed because of the missing Ebecause of the missing ETT cuts. cuts.Sensitivity to the edge position still possible Sensitivity to the edge position still possible with about 30/fb.with about 30/fb.

Apart from the SUSY discovery itself, it will be important to measure the properties of Apart from the SUSY discovery itself, it will be important to measure the properties of the supersymmetric particlesthe supersymmetric particles. . The di-lepton invariant mass in the decay chain has The di-lepton invariant mass in the decay chain has a sharp edge because of the two-body decay of a sharp edge because of the two-body decay of the the 22

00.. The mass of the two leptons gives informationThe mass of the two leptons gives information on the relation between the sparticles involvedon the relation between the sparticles involved in the decay.in the decay.

))((1 22

~2~

2

~

max01

02 mmmm

mm

Roberto Chierici 19

More Standard Search MethodsMore Standard Search Methods

The standard physics program with The standard physics program with s at the LHC is important (W and Z physics, s at the LHC is important (W and Z physics, properties), and new physics can be searched continuing to probe the SM:properties), and new physics can be searched continuing to probe the SM: gg/g/gee in W decays in W decays rare decays / rare decays / forbidden decays forbidden decays

Example: the neutrinoless Example: the neutrinoless decay decay ++++- -

sign of lepton flavour violation, explainable by massive neutrinos or particular mSUGRA sign of lepton flavour violation, explainable by massive neutrinos or particular mSUGRA modelsmodels

Signal sources are considered as Signal sources are considered as WW, Z, Z, meson, mesonXXThe main backgrounds are found to be bb The main backgrounds are found to be bb and cc production. and cc production. Resonances can be easily suppressed.Resonances can be easily suppressed.The best limit is obtained with W decays because The best limit is obtained with W decays because of the peculiar high missing Eof the peculiar high missing ETT. .

The resolution on m(The resolution on m() is about 15 MeV ) is about 15 MeV

CMS or ATLAS alone should be able to improve CMS or ATLAS alone should be able to improve the present experimental limit on the the present experimental limit on the 33 BR BR (1.9 10(1.9 10-6-6) by a factor 50 with 30/fb (3.8 10) by a factor 50 with 30/fb (3.8 10-8-8))

CMS, m(CMS, m(), 10/fb), 10/fb

signal BR = 1.9 10signal BR = 1.9 10-6-6

Roberto Chierici 20

Some other uses of Some other uses of s in new s in new physicsphysics

In gauge mediated SUSY breaking the G is the LSP.In gauge mediated SUSY breaking the G is the LSP.There are mainly two options as NLSP: There are mainly two options as NLSP: or or 11

00. So . So production will represent one of the production will represent one of themain possible signatures of the final state. main possible signatures of the final state. One important feature of GMSB is that the lifetime of the NLSP is directly related to the One important feature of GMSB is that the lifetime of the NLSP is directly related to the scale of SUSY breaking and is totally unconstrained.scale of SUSY breaking and is totally unconstrained.

cc » L » Ldetectordetector: : will appear as heavy muons will appear as heavy muons cc ~ L ~ Ldetectordetector: kinks in the detector and the NLSP lifetime can be measured: kinks in the detector and the NLSP lifetime can be measured cc « L « Ldetectordetector: increase of : increase of production cross-section production cross-section

GMSBGMSB

LFV in SUSYLFV in SUSY

~~

~~

~~

SUSY models can naturally accommodate lepton SUSY models can naturally accommodate lepton flavour violation, which is expected to be larger for flavour violation, which is expected to be larger for the third generation.the third generation.The best way to observe it in large regions of parameterThe best way to observe it in large regions of parameterspace (mspace (m00≤m≤m1/21/2) is in the decay channel ) is in the decay channel 22

001100

The signal is then determined from N(The signal is then determined from N()-N(e)-N(e))(yielding 12(yielding 12 for BR=10% and 10/fb) for BR=10% and 10/fb) more sensitivity than more sensitivity than or or in this region in this region of parameter space.of parameter space.

~~

jet

jet

jet SM

10%)(BR

jet

ATLAS, 10/fbATLAS, 10/fb

tan(tan()=10)=10mm00=100 GeV=100 GeVmm1/21/2=300 GeV=300 GeVAA00=300 GeV=300 GeV

Roberto Chierici 21

Conclusions on Conclusions on at the LHC at the LHC

An intense activity for the inclusion of the An intense activity for the inclusion of the hadronic decay into the hadronic decay into the triggering scheme at LHC has lead to very encouraging results.triggering scheme at LHC has lead to very encouraging results. use of tracking at the HLT leveluse of tracking at the HLT levelWork on Work on identification algorithms continues and refines. identification algorithms continues and refines.

This effort will be very helpful for all the searches of new physics at the This effort will be very helpful for all the searches of new physics at the LHCLHC

Aside standard physics (SM Higgs, Aside standard physics (SM Higgs, physics) the relevance of physics) the relevance of detection at detection at the LHC involves the discovery of supersymmetry on sizeable regions of the LHC involves the discovery of supersymmetry on sizeable regions of parameter space:parameter space:

Higgs boson (neutral and charged) productionHiggs boson (neutral and charged) production evidence for SUSY with high sensitivity in the high tan(evidence for SUSY with high sensitivity in the high tan() regime) regime search for lepton flavour violation signals search for lepton flavour violation signals GMSB and other models where staus are NLSPsGMSB and other models where staus are NLSPs

And the measurement of its properties, if it exists:And the measurement of its properties, if it exists: Higgs boson masses at high tan(Higgs boson masses at high tan()) determination of tan(determination of tan() ) sensitivity to the slepton masses sensitivity to the slepton masses

Tau04, Nara, September 2004

Roberto Chierici 23

Trigger CPU, rates and speedTrigger CPU, rates and speed

CPU per physics object at L1:CPU per physics object at L1:1 GHz Intel PIII CPU (=41 SpecInt95)1 GHz Intel PIII CPU (=41 SpecInt95)

4092 CPU seconds to cover the4092 CPU seconds to cover the full 15 KHz of L1 full 15 KHz of L1 on average ~300ms/eventon average ~300ms/event considering full 100KHz one considering full 100KHz one needs 30000 PIII needs 30000 PIII 1.2 101.2 1066 SI95 SI95

At the start of LHC At the start of LHC (50 KHz+a (50 KHz+a factor 8 from Moore’s law)factor 8 from Moore’s law) 2000 2000 CPUs should be enoughCPUs should be enough

How to plan a L1 trigger:How to plan a L1 trigger:100(50) KHz100(50) KHz 33(15) KHz safety factor 333(15) KHz safety factor 3 8(4) KHz per physics 8(4) KHz per physics objectobject

XX ==

Roberto Chierici 24

A more complete viewA more complete view

Roberto Chierici 25

Latest LEP resultsLatest LEP results

SM: 10.8%028.0076.1

)BR(W

)BR(W

029.0070.1)BR(W

)BR(W

020.0994.0)BR(W

)BR(W

e

e

Fit individual channel cross-sections Fit individual channel cross-sections without assumptions on lepton without assumptions on lepton universalityuniversality BR(WBR(W) clearly higher than ) clearly higher than BR(WBR(Wee) ) and BR(Wand BR(W))

2*BR(W2*BR(W)- BR(W)- BR(Wee)- BR(W)- BR(W) ) differs from 0 by 3.0differs from 0 by 3.0 (correlations (correlations included)included)

• waswas 2.3 2.3 in summer 2003 in summer 2003• is is 2.62.6 if final results only are used if final results only are used

Common effect in all experimentsCommon effect in all experiments

Roberto Chierici 26

A bit of SUSYA bit of SUSY

Supersymmetry postulates the existence of partners of all SM particles differing by Supersymmetry postulates the existence of partners of all SM particles differing by those only because their spin is h/2 lower. This mechanism eliminates the radiative those only because their spin is h/2 lower. This mechanism eliminates the radiative corrections quadratic divergencies in the SM. Minimally two Higgs doublets must be corrections quadratic divergencies in the SM. Minimally two Higgs doublets must be introducedintroduced

The partners of SM particles are called squarks(q), sleptons(The partners of SM particles are called squarks(q), sleptons(ℓ,ℓ,), gluinos(g), photinos(), gluinos(g), photinos(). ). zinos(Z),zinos(Z),winos(W), Higgsinos(H), gravitino(G). Winos and charged Higgsinos mix to form two winos(W), Higgsinos(H), gravitino(G). Winos and charged Higgsinos mix to form two charginos(charginos(ii

),),photinos, zinos and neutral higgsinos mix to form four neutralinos(photinos, zinos and neutral higgsinos mix to form four neutralinos(ii

00) which are mass ) which are mass eigenstates.eigenstates.

SUSY must be broken: a hidden sector where this happens is introduced and the SUSY must be broken: a hidden sector where this happens is introduced and the mediator of the breaking can be gravity (SUGRA) or gauge forces (GMSB) in most mediator of the breaking can be gravity (SUGRA) or gauge forces (GMSB) in most popular scenarios.popular scenarios.

Minimal SUSY model = MSSM. The number of parameters of the model can be reduced Minimal SUSY model = MSSM. The number of parameters of the model can be reduced to five imposing gaugino and sfermion mass unification at the GUT scale, universal to five imposing gaugino and sfermion mass unification at the GUT scale, universal trilinear couplings and the correct EW symmetry scale (mSUGRA):trilinear couplings and the correct EW symmetry scale (mSUGRA):

tan(tan() is the ratio of the vacuum expectation values of the two Higgs doublets) is the ratio of the vacuum expectation values of the two Higgs doublets is the Higgs mass parameteris the Higgs mass parametermm1/21/2 are the unified gaugino masses are the unified gaugino massesmm00 are the unified sfermion masses are the unified sfermion massesmmAA is the pseudoscalar Higgs mass is the pseudoscalar Higgs mass

if R=(-1)if R=(-1)3B+L+2S3B+L+2S parity is conserved the LSP is stable (typically the parity is conserved the LSP is stable (typically the ii00) and SUSY particles ) and SUSY particles

can only be produced in pairs. Best signatures are represented by:can only be produced in pairs. Best signatures are represented by:

~~ ~~~~ ~~ ~~ ~~~~ ~~ ~~

ffi01

0

Roberto Chierici 27

Higgs discovery potentialHiggs discovery potential