supersymmetry searches at colliders

Zuoz Summer school 16-20/08/04

Luc Pape, CERN 1

CERNCERN

Supersymmetry searches at colliders

L. Pape (CERN) Broad Outline

Some basics, models, sparticle spectra(Low energy experiments)Present and future accelerators

Higgs searchesSparticle decays

Existing limits on sparticlesFuture searches


Luc Pape, CERN 2

CERNCERN

Some basic phenomenology Contents:

MSSM sparticle contents Gauge interactions Yukawa couplings (Unbroken MSSM Lagrangian) SUSY breaking models Sparticle spectroscopy

See lectures by H.Haber


Luc Pape, CERN 3

CERNCERN

MSSM Particle content SUSY transforms fermions to bosons and vice versa:

Q|F> = |B> , Q|B> = |F>Symmetry supermultiplets with same number of

fermionic and bosonic degrees of freedomSM fermion (2 dof) complex scalarSM gauge boson (2 dof) SUSY fermion (gaugino)

Gauge multiplet Chiral multiplet

J = 1 J = 1/2 J = 1/2 J = 0

g~

0~,~

WW

MSSM = minimal extension of SM:

Supermultiplet components:-Same gauge quantum numbers- Differ only by ½ unit of spin g

0,WW

0~B0B

CL

CLL DUQ~,

~,

~CL

CLL DUQ ,,

CLL EL~,

~

ud HH~,

~

CLL EL ,

ud HH ,


Luc Pape, CERN 4

CERNCERN

Quantum Numbers Chiral supermultiplet:

e.g. 1st family

Charge is SU(3),SU(2),U(1)Q = I3 + Y/2

Gauge supermultiplet:After EW symmetry breakingMixing

charginosMixing

neutralinos

Charge Scalar

Q (3,2,+1/3)

Uc (3,1,-4/3)

Dc (3,1,+2/3)

L (1,2,-1)

Ec (1,1,+2)

Hd (1,2,-1)

Hu (1,2,+1)

)~,~( LL duQ cL

c uU ~cL

c dD~

)~,~( LL eL

cL

c eE ~),( 0 ddd HHH),( 0

uuu HHH

Fermion VB Charge

(gluino) g (8,1,0) (Wino) W (1,3,0) (Bino) B0 (1,1,0)

g~

W~

0~B

21

~,

~ HW

041

0000 ~,

~,

~,

~ ud HHBW


Luc Pape, CERN 5

CERNCERNFrom SM to MSSM interactions

SM multiplets → MSSM supermultiplets By including superpartners differing by ½ unit in spin Supermultiplets: Chiral = (), Gauge = (A,)

Same supermultiplet same couplings in interactions But: amplitudes must be scalars in spin space To go from SM to MSSM interaction:

Will not produce all MSSM interactions,But it provides a useful mnemonic

Replace pair of SM particles by their superpartners


Luc Pape, CERN 6

CERNCERNGauge interactions (trilinear)

Trilinear interactions as they control production and decay:

SM: (A) (A) ()

SM: (AAA)

(A)

More formally: derived from covariant derivatives

Strength: i=gi

2/4

g1=e/cosW , g2=e/sinW,=e2/4

1~1/100, 2~1/30, 3~0.12


Luc Pape, CERN 7

CERNCERN

Yukawa interactions

cos.,

sin. v

mh

v

mh d

du

u

du vv /tan

GeVg

Mvvv Wdu 1752

2

22

Strength: Y=h2/4, (for tan=1-35):Yt=0.17-0.08, Yb=1.10-4-6.10-2,

Y=2.10-5-1.10-2Y=6.10-8-5.10-5, Ye=1.10-12-

1.10-9

Top Yukawa can never be neglectedBottom and Tau Yukawas for large

tan

= dimensionful parameter

More formally: derived from Superpotential


Luc Pape, CERN 12

CERNCERN

SUPERSYMMETRY BREAKING Unbroken MSSM

Unbroken SUSY introduces new interactions but no new parameters

All particles are massless Superpartners must be heavier than SM particles SUSY broken

Soft SUSY breaking (soft = no quadratic divergences)

m0,i scalar masses (matrix in generation space) m1/2,a gaugino masses

Effective Lagrangian to derive phenomenology

..~~~~~~

..||

0,0,0,0

,2/12

,02

,~,~ ,

chHHBHUhQAHDhQAHEhLA

chmmV

udju

cLU

iLu

jd

cLD

iLd

jd

cLL

iLe

aaaiiHlq ud

Parametrization of our ignorance of SUSY breaking mechanism


Luc Pape, CERN 13

CERNCERN

Gauge coupling unification Renormalization Group Equations (RGE):

Connect gauge couplings at some scale q0 to a scale q

ba are constants related to the charges under groups U(1), SU(2), SU(3) summed over all particles entering the loops, e.g.

SM particles only: ba = (41/10,-19/6,-7)

Including MSSM particles: ba = (33/5,1,-3) RGEs allow extrapolation of couplings from weak scale,

linear in -1 (at 1 loop)

)ln( 2

20

q

qt

4

2a

a

g,

4)(1

a

a

bt

dt

d


Luc Pape, CERN 14

CERNCERN

Gauge coupling unification Do couplings unify at some scale? (GQW1974)

Precisely known since measurements at LEP (1991) Evolving with 2-loop RGEs:

- do not meet if SM only- meet if MSSM with sparticles around 1-10 TeV

Gives support to the GUT idea and to MSSMWith MGUT = 2 1016 GeV, GUT = 1/24

First experimental hint that there is something beyond SM

W.de Boer, 1998


Luc Pape, CERN 15

CERNCERN

Mass Universality, MSUGRA In general MSSM

Many new parameters MSSM124 Most parameters involve flavour mixing or CP violating

phases

Universal mass parameters Catastrophy is evaded by asuming Universality at GUT

scale: m0,I = m0, common scalar mass

m1/2,a = m1/2, common gaugino masses

A0,i = A0,

Remaining parameters:

Called MSUGRA

m0 , m1/2 , A0 , B0 ,


Luc Pape, CERN 16

CERNCERN

MSUGRA Spectroscopy(1)Parameters defined at the GUT scale

Sfermions: m0

-Squarks increase fast (S

-Sleptons increase slower

Gauginos: m1/2

-Gluino increases fast

-Bino/Wino masses decrease (mix with higgsinos)

2 charginos, 4 neutralinosUsually: lightest 0

1 is Lightest SUSY Particle (LSP) stable Emiss

Run down to EW scale by Renormalization Group Equations (RGE)

log10Q

W.de Boer, 1998


Luc Pape, CERN 17

CERNCERN

MSUGRA Spectroscopy(2)Higgs mass parameters Hu and Hd at the GUT scale: 22

0 m

log10Q

Large Yukawa coupling of Hu to t-quark

Drives mass2 parameter of Hu < 0

Triggers EW symmetry breaking

Radiative EWSB occurs naturally

in MSSM

Minimization of Higgs potential

reduces number of parameters

tan = vu / vd

m0 , m1/2 , A0 , tan , sgn(


Luc Pape, CERN 19

CERNCERN

Gaugino mass RGEs Universal gaugino masses: m1/2 at GUT scale

Renormalization Group Equations (RGE):

Weak scale values:

SU(3) unbroken: M3=physical gluino mass, up to QCD corrections

After SU(2)xU(1) breaking, Wino and Bino masses are mixed

Note: same relations apply to GMSB

3

3

2

2

1

1

MMM

2/1~3 7.2 mMM g

2/12 8.0 mM 22/11 5.04.0 MmM


Luc Pape, CERN 20

CERNCERN

Chargino/neutralino masses Gauginos mix with higgsinos

Off diagonal coupling Mass matrices:

Charginos (2x2) matrix: M2, , tan Neutralinos (4x4) matrix: M1, M2, , tan In limit where neglect terms in tan, simplify to

two extreme cases:

In MSUGRA (+GMSB): usually gaugino-like, 10=Bino,

20,1

±=Winos

)~~

(),,( 0 ddHHW

)(,)( 221 MMM

)()(,)(,)( 04

032

021

01 MMMMMM

2M2M

Lightest are “gaugino-like”Lightest are “higgsino-like”


Luc Pape, CERN 21

CERNCERNSquark and slepton masses(1)

First two families: start from m0 at GUT scale Yukawas are negligible Running dominated by m1/2 and is Splitting by D-term (sfermion)2(higgs)2 after SU(2)xU(1)

breaking At weak scale (approx. formulae)

222/1

20

2 2cos35.09.5)~( ZL Mmmum

222/1

20

2 2cos15.05.5)~( ZR Mmmum 22

2/120

2 2cos42.09.5)~( ZL Mmmdm

222/1

20

2 2cos07.04.5)~( ZR Mmmdm

222/1

20

2 2cos27.049.)~( ZL Mmmem 22

2/120

2 2cos50.049.)~( ZL Mmmm 22

2/120

2 2cos23.015.)~( ZR Mmmem

2cos22~

2~

2~

2~ Wude Mmmmm

LLLLD-term sum

rule:note that mgluino is at most ~1.2 msquark (for m0=0)


Luc Pape, CERN 22

CERNCERNSquark and slepton masses(2)

Third family: Yukawa couplings cannot be neglected At weak scale (tan = 10)

Yukawa couplings decrease mass Also L-R mixing: SUSY breaking and F-term

Similar for sbottom/stau replacing cot by tan

)~()

~( 222

RbR dmmbm

222/1

20

22 2cos15.07.333.)~( ZtR Mmmmtm

222/1

20

22 2cos35.00.569.)~( ZtL Mmmmtm 22

2/120

22 2cos42.00.569.)~( ZbL Mmmmbm

)~()cot(

)cot()~(2

2

Rtt

ttL

tmAm

Amtm

2222~

2~

2~

2~

2~ )cot(4)(

2

12,1

ttttttt AmmmmmmRLRL

Lightest squark:

)tan(~),tan(~ 11 highblowt


Luc Pape, CERN 23

CERNCERN

Example MSUGRA spectrum Stable neutralino LSP

Low m0 High m0 (Focus Point)


Luc Pape, CERN 24

CERNCERNGauge Mediated SUSY Breaking

Gauge mediation (GMSB): 3 sectors

Loops: , for msoft at EW scale

Gravitino is the LSP (m ~ eV) Parameters

M= messenger scale (amount of RGE evolution) mass splitting of scalar messengers (F= vev of

X) N= messenger index, where a 5 contributes with 1 and a 10

with 3 and B obtained from gauge boson mass and tan

F

hiddenmessenger

visible

X: vevgauge interactio

ns

llqq ,,, __

1010,55

, M, N, tan, sign()

F

Fmsoft 4

GeVF 54 1010


Luc Pape, CERN 25

CERNCERN

Gauginos:

Scalars (at messenger scale):

With C3=4/3 (=0 if singlet), C2=3/4 (=0 if singlet), C1=3/5.(Y/2)2

Note the different dependence on N

Nt

M aa

4

)(

222

42~

a

aCNm

22 /ln QMt


Luc Pape, CERN 26

CERNCERN

GMSB spectroscopy LSP=gravitino

Who is NLSP?Sparticles decay to NLSP Low N:0

1 is NLSP

High N:Stau is NLSP

Typical signature of GMSB: Emiss + or or long-lived particles

G~0

1

G~~

1

Guidice,Rattazi, hep-ph/9801271


Luc Pape, CERN 30

CERNCERN

R-parity violation SUSY permits to add terms to Superpotential

Yukawa couplings with i,j,k=generation indices Violate conservation of R-parity Rp=(-1)3B+L+2S

1st 2 terms L=1, last term B=1 New parameters:

: antisymmetric by SU(2) invariance: i<j, 9terms ’: 27 terms ’’:antisymmetric by SU(3)C invariance: j<k, 9 terms

45 new free parameters

ck

cj

ciijk

ckjiijk

ckjiijkRPV DDUDQLELLW

~~~''

~~~'

~~~


Luc Pape, CERN 31

CERNCERN

R-parity violation Constrained by proton lifetime

’ and ’’ non zero Several other low energy constraints

Review by H.Dreiner hep-ph/9707435

LSP Neutralino decays Via fermion-sfermion pair, followed

by RPV decay Missing energy signature is lost New signatures appear (additional

leptons and/or jets) LSP could be sfermion, decaying via

RPV Single production of sfermions

E.g. sneutrino at LEP or squark at HERA


Luc Pape, CERN 32

CERNCERN

SUSY Signatures

Supersymmetry, MSUGRASupersymmetry, MSUGRAET

miss, Inclusive searchesDileptons, Taus, Z0, h0Bottomsmass reconstruction

Gauge MediatedGauge MediatedPhoton events + ET

miss Multi-tau events + ET

miss

Long-lived sparticles

R-parity violationR-parity violationMulti-leptonsMulti-jets


Luc Pape, CERN 33

CERNCERN

Low Energy Measurements

Contents b s decay Other FCNC decays of b and s g – 2 saga Many others

Proton decay, K0-K0bar oscillations, lepton violating decays, CP violation, electric dipole moments, atomic parity violation, LEP/SLC precision measurements …

May bring first evidence for physics beyond the SM Keep eyes wide open!

See lectures of D.Wyler and W.Hollik


Luc Pape, CERN 34

CERNCERN

Accelerators

Contents Present accelerators Future funded accelerators Future proposed accelerators


Luc Pape, CERN 35

CERNCERN

Present accelerators √s, GeV pb-1/exp

LEP e+e- ADLO

LEP 1 1989-95

91 150

LEP 2 95-2000

130-208

700

Tevatron

p-p CDF,D0

Run 1 1800 110

Run 2 01-~08 2000 ? (3-20.103)

HERA e±p H1,Zeus

1993-97

300 50

98-~07 318 ?(1.103)


Luc Pape, CERN 36

CERNCERN

Future accelerators LHC (funded, at CERN)

Expected to start in ~Summer 2007, true data taking 2008

Ecm = 14 TeV, p+p Run ~3 years at luminosity=1033cm-2s-1 (~10 fb-1/year) Continue at 1034cm-2s-1 (~100 fb-1/year)

e+e- Collider 3 techniques proposed: TESLA, NLC, JLC

Start at 0.5, upgrade to ~1 TeVDecision on technique this yearDetailed TDR for 2007, site selection 2008(?)

CLIC up to 3-5 TeVFeasibility to be demonstrated for 2010Construction could start in 2013 (last 7 years)

Others: collider, VLHC


Luc Pape, CERN 37

CERNCERN

Sparticle production Two basically different approaches

e+e- colliderPure partonic interactionsfixed Ecm= partonic energy (kinematical constraints)

allows E scans (e.g. thresholds) to be made/polarization precision measurementsbut limited Ecms

Hadron collider (p-p or p-p)Variable partonic energy, e.g.

but machine reaches higher energy exploratory machine

)'().().(. sxxsxFxFdxdx gqqgggqqgqqg


Luc Pape, CERN 38

CERNCERN

SUSY Higgses

Contents Higgs mass in SM Higgs mass in MSSM Higgs mass radiative corrections Production in e+e- colliders Limits from LEP and Tevatron Future searches: Tevatron, LHC and LC


Luc Pape, CERN 39

CERNCERN

Higgs mass in SM (1) One Higgs field SU(2) doublet

Masses generated by Higgs v.e.v.V() = 2||2 + ||4, with 2<0 and >0

Higgs mass: MH2 = 2 v2 (v) for v = 175 GeV

Parameters and are free in SM Higss mass is undetermined in SM


Luc Pape, CERN 40

CERNCERN

Higgs mass in SM (2) Limits on Higgs mass can be derived from rad.corr.

RGE evolution of due to Higgs and top (ht=Yukawa) loops:

Perturbativity: ht << 2 dominates strong coupling Upper limit on MH

Vaccum stability: ht >> -ht

4 dominates (t) negative Potential unbounded from below Lower bound on MH

SM valid up to Planck scale:

)/ln(,4

3)( 4222

vthhdt

tdtt

130 < MH < 180 GeV

MH

, GeV

Ridolfi, hep-ph/0106300


Luc Pape, CERN 41

CERNCERN

Higgs in MSSM In MSSM: 2 Higgs fields 8 degrees of freedom

3 are used to make W± and Z0 massiveMSSM contains 5 physical Higgs states

2 charged scalars H±

Mixture of Hd- and Hu

+, fixed by tan 1 neutral CP-odd A0

Mixture of Im(Hd0) and Im(Hu

0), fixed by tan 2 neutral CP-even h0 and H0

Mixture of Re(Hd0) and Re(Hu

0), with mixing angle

d

dd

H

HH

0

0u

uu

H

HH


Luc Pape, CERN 42

CERNCERN

Higgs mass at tree level From scalar potential, tree level masses are:

Higgs masses depend on only 2 parameters: mA and tan tanmh=0, mH

2=MZ2+mA

2

tan∞:mh, mH0=min,max(MZ,mA)

Mass hierarchy at tree level: 0 ≤ mh ≤MZ|cos2| mh ≤ mA ≤mH

0

mH0 ≥ MZ

mH± ≥ MW

Expect light h0 (coupling of ||4 term of gauge strength) observable at LEP2

But radiative corrections are large, especially on mh

222AWH

mMm

2cos4)(2

1)(

2

1 222222222, ZAZAZAhH MmMmMmm


Luc Pape, CERN 43

CERNCERNHiggs mass radiative corrections

Top loop corrections: 1-loop leading log approximation

Introduces a dependence on top and stop masses More accurate calculation:also on stop mixing Xt=At-cot

In MSSM, mh0 has upper bound

Increases with tan Increases from min Xt/MSUSY=0

To max (Xt/MSUSY)2=6

(for MSUSY = 1 TeV, mt=175 GeV)

Lower than preferred SM range

2

~~

22

42 21ln

4

3)(

t

ttth m

mm

v

mm

tanb=15

tanb=1.6

mh ≤130 GeV

Carena et al., hep-ph/9504316


Luc Pape, CERN 44

CERNCERN

Higgs masses, summary


Luc Pape, CERN 45

CERNCERN

Higgs decays Light Higgs h0 <130 GeV:

B(bb)~80-85%, B() ~8%, B() ~2.10-4, B() ~1.5.10-3

For mh>120 GeV B(WW*) and B(ZZ*) increase

H0/A0 (>130 GeV): Large tan>10: B(bb) dominates, B() ~10%, Small tan: H0WW*, ZZ*, hh dominate

and A0Zh dominatesbut for m(H,A)>350 GeV B(tt)~90%

H±: m(H±)<mt: B()~100% For m(H±)>200 GeV: B(tb) dominates, B()~10%

All can decay to gauginos (depends on parameters)


Luc Pape, CERN 46

CERNCERNProduction in e+e- machines(1)

Higgsstrahlung Fusion (small) Associated production

)(sin, 20 Zhee )(cos, 20 Ahee

The processes are complementary

is mixing angle of h0 and H0


Luc Pape, CERN 47

CERNCERNProduction in e+e- machines(2)

)(sin, 20 Zhee

Large mA

:- = /2h0Z0 dominates, h0 is SM-

like

Large tan, mh~mA- =

h0A0 dominates, mh≤100 GeV

22

22

2cos2coshH

ZA

mm

Mm


Luc Pape, CERN 48

CERNCERN

Higgs search topologies h0 Z topologies:

B(h0→b-bbar)=86%, B(h0→bar)=8%

Also , (B.R.=5.4%) included in search For mh > 130 GeV WW* and ZZ* become important

h0 A topologies For mA<350 GeV:

For mA>350 GeV: may be important

bbh 0 llZ 0 0Z qqZ 0

bbh 0 bbh 0

B.R.=9.3%

B.R.=18% B.R.=64%

0h qqZ 0

4,, bbbbbbttA


Luc Pape, CERN 49

CERNCERN

Higgs mass limits from LEPLEP 95% C.L. exclusion from

ADLO:Maximal stop mixing (mh

max)No stop

mixing

Large mA:For mh

max:mh≥114.1

GeVmh≥91.0, mA≥91.9 GeV

tan ≥2.4


Luc Pape, CERN 50

CERNCERN

Non-conventional Higgses H→

Crucial channel for LHC, but small BR (2.10-3) So far, insufficient sensitivity at LEP and Tevatron

H invisible decays E.g. decay to neutralinos “Easy” at LEP, ADLO limit 114.4 GeV

Flavour-blind H search Usually search H→bb, but BR may be suppressed Look for decays into 2 jets or in HZ channel LEP (preliminary) limit is 112.5 GeV

Charged H Decays to cs or LEP (preliminary) limit about 80 GeV


Luc Pape, CERN 52

CERNCERNFuture searches: Tevatron(1)

Dominant cross-section: Gluon fusion (top/bottom

loop) Decay hopeless But with

leptonic decays for large mh

Also with , triggered

byleptonic decay of W or Z for mh < 140 GeV

bbh 0

*0 VVh

0* VhVqq bbh 0

mH

(p

b) Gluon fusion

Anastasiou, Melnikov, hep-ph/0207004

NNLO

NLO

LO

2 curves: =mH/2,2mH


Luc Pape, CERN 53

CERNCERNFuture searches: Tevatron(2)

Tevatron Run II After 2 fb-1:

Excl 120 GeV (95% CL) After 11 fb-1 for 2008

Excl 180 GeV (95% CL)3 < 130, 155-175 GeV5 < 110 GeV

Discovery up to 130 GeVwould require 30 fb-1

bbHh /

Carena et al., hep-ph/0010338

HhWqq /lW */ WWHh

Hgg

lW


Luc Pape, CERN 54

CERNCERN

Future searches: LHC(1) Dominant cross sections:

Gluon fusion Higgsstrahlung, e.g. Hb-

bbar at high tan Gauge boson fusion (Hqq)

low, especially at high tan)

Associated production with VB (strongly suppressed)

tan=1.5

tan=30

Spira,

Zerwas

pb

pb


Luc Pape, CERN 55

CERNCERN

Future searches: LHC(2) Low Higgs mass region:

H most powerfulAlready with 30 fb-1 get 5 up to 150 GeV

~60 fb-1: >60-100 fb-1: several modes

observable Higher masses > 130 GeV

HWW*,ZZ*Already with 10 fb-1

SM(-like) Higgs

HqqH ,bbHHtt ,


Luc Pape, CERN 56

CERNCERN

Future searches: LHC(3) Up to highest masses,

with < 30 fb-1 Using HWW,ZZ

SM(-like) Higgs


Luc Pape, CERN 57

CERNCERN

Future searches: LHC(4) h0only for mA>200 GeV

Importance of tth, hbb and qqh, h

Still mA<130 GeV not covered (mh<120 GeV, not SM-like) Hope to cover with

ggbbh, h (or sparticle decays)

Caveat: ggh0 from loops with t or b In SUSY also stop+sbottom

Stop-top negative interference

May preclude discovery by h0if

GeVtm 200)~( 1


Luc Pape, CERN 58

CERNCERN

Future searches: LHC(5) Heavy neutral Higgses

Based on H,A No sensitivity for large mA

and low/intermediate tan Charged Higgs

Based on H±, tb No sensitivity for large mA

and low/intermediate tan Overall conclusion for LHC

Should discover Higgs, but Still holes for m(h0)<120

GeV May miss H0/A0 if large mA

and low tan


Luc Pape, CERN 62

CERNCERN

Future searches: LC Light Higgs likely discovered

before LC start LC for precision

measurements 500 GeV LC measurements:

mass to 0.05% determine spin/parity

Branching ratio measurement for 500 fb-1 (~2 years)

May need multi-TeV machine for heavy Higgses

Battaglia et al., hep-ex/0201018


Luc Pape, CERN 63

CERNCERN

Future searches: MuCOL MuCOL may produce Higgs

in s-channel Expects ~1 fb-1 per year can have very small beam

energy spread Ideal for line shape

measurement could measure

Mass to ±0.1 MeV (at 110 GeV)

Width to ±0.5 MeV Cross-section to ±5%


Luc Pape, CERN 64

CERNCERN

Sparticle decays

Contents Chargino/neutralino Sleptons Squarks and gluinos


Luc Pape, CERN 65

CERNCERN

Chargino Neutralino

Loop decay

Chargino/neutralino decays

Hji0

012 H

000 Hji

lli

~,~

012 Z

Wji0

Wi 1

0

000 Zji

~,~0 lli

)(

)(),( AA )( A

Hi 1

0)(

)(

)(

)(

)(),( AA

)(

01

02

)(),( AA

Are couplings with gauge strength

Dominant one depends on spectrum and ±/ composition


Luc Pape, CERN 66

CERNCERN

Slepton decays Slepton decay:

sleptonL prefers a Wino (±1 or 0

2 in MSUGRA cascade)

sleptonR only decays to a Bino (01 in MSUGRA)

Stau decays may be more complicated: At large tan, Yukawa couplings contribute

can decay to higgsino e.g. But only is possible

and is forbidden, as higgsino requires helicity flip

ii ll ,

~ 0 )(

hhR

~,

~~ 0

0~~ hL

hL

~~


Luc Pape, CERN 67

CERNCERN

Squark/gluino decays Squark strong decay: for

Preferred if kinematically allowed Electroweak decay:

squarkL prefers a Wino (±1 or 0

2 in MSUGRA cascade)

squarkR only decays to a Bino (01 in MSUGRA)

Stop EW decay: For light stop (m < m(±

1)) above decays forbidden

Loop decay may dominate Gluino decay: for If lighter than squarks:

Caveat: only main decay modes Others in special regions of parameter space, e.g. For stop/sbottom Yukawa couplings may be relevant

',~ 0 qqq ii )(

qgq ~~

ct 011

~

)~()~( gmqm

qqg ~~ )~()~( gmqm

gqqqqg 00 ,,'~

Wtb 1~~


Luc Pape, CERN 68

CERNCERN

Existing Limits, stable 01

Contents From Tevatron and LEP direct searches LEP limits on LSP mass Constraints on MSUGRA parameter space Including CDM constraints

(Limits also exist for): GMSB, AMSB scenarios R-p violating couplings

(See http://lepsusy.web.cern.ch/lepsusy/Welcome.html)


Luc Pape, CERN 69

CERNCERN

Slepton limits from LEP Sneutrino, LEP1

Expect: “invisible” in Z0 decays

LEP1 limit: inv< 2 MeV Sneutrino width:

Limit on sneutrino mass (assuming 1 family):

Charged sleptons, LEP2 Based on

2/3

2

2~

0

0 41

2

1

)(

)~~(

Zm

m

Z

Z

01

~

GeVm 7.43)~(

ll 01

~


Luc Pape, CERN 70

CERNCERN

Squark/gluino limits Limits from LEP and Tevatron, examples:

01

~ ct 01

~ bb

Complementarity between LEP and Tevatron


Luc Pape, CERN 71

CERNCERNChargino/neutralino production

Charginos:

typically ~ pbnegative interference s- and t-

channelFor gaugino-like charginos negligible for small sneutrino

mass loss of sensitivity

Neutralinos:

typically ~ pbt-channel only gaugino-likeincreases for light selectronsome compensation for x-sect

lossin gaugino-like charginos


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Chargino limits Charginos: large m0

Gaugino-like Depends on sneutrino

mass

Small M=M(1±)-M(1

0) Higgsino-like Stable, IP, 2nd Vx, ISR Is also a limit on LSP!


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Direct search limitsChannel M > (GeV) M

43.7 EW measts ADLO

99 10 GeV ADLO

95 10 GeV ADLO

85 10 GeV ADLO

95 20 GeV ADLO

96 20 GeV ALO

94 20 GeV ADLO

195 - CDF

103.5 Large m0 ADLO

92.4 Small M ADLO011 W

01

~

~

011 W

mTEjg ~

01

~ ee

01

~ bb

~~ blt

01

~ ct

01

~


Luc Pape, CERN 75

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Indirect limits on LSP(1) No full coverage from neutralinos only

no direct limits on 10 mass

Requires to combine results from: Chargino searches: weak if gaugino and low Neutralino searches: weak if not higgsino,

but improves if gaugino for low Slepton searches

-LEP2 limit on using sum rule:-LEP1 limit on

Scalar mass universality: Allows exclusion of low regions of M2 for fixed m0

Higgs searches: excludes low tan

)~(m

GeVm 43)~( )~(em

)~(em

2cos22~

2~ We Mmm

LL

2cos27.81. 222

20

2~ Ze MMmm


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Indirect limits on LSP(2) Example of interplay of

these constraints (MSUGRA): Yellow: no REWSB Light blue: inconsistent

with LEP1 measurements Green: excluded by

chargino Red: excluded by slepton Blue: excluded by hZ

Regions depend on tan


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Indirect limits on LSP(3) In MSSM In MSUGRA

M(01=LSP) > 45-50

GeV


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Constrained MSUGRA GUT universality of gaugino+scalar masses + REWSB

m0 , m1/2 , A0 , tan , sgn()

)()~( 011 mm

GeVhm 114)( 0

GeVm 103)( 1

sb

Weakens at large tan

Depends weakly on tan

Stronger at large tan


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Sparticle production at LHC

Contents Squark and gluino production Stop production Slepton production Direct chargino/neutralino production


Luc Pape, CERN 83

CERNCERNSquark and gluino production

Contributing LO processes:

ggqq ~~ gggg ~~

qqgg ~~

gqqg ~~

qqqq ~~qqqq ~~


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Squark/gluino cross sections NLO cross sections at LHC

NLO calculation is important:

NLO ~(1.1-1.9) LO

Remaining scale dependence~15% (uncertainty)

At 1 TeV, summed > 1 pb

1 fb at ~2.5 TeV

qq~~ qq~~

gg~~ gq~~

Beenakker et al., hep-ph/9610490


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Future Searches

Contents At LHC (discovery reach + mass reconstruction) At e+e- Linear Colliders (precision measurements) Extrapolation to the GUT scale


Luc Pape, CERN 89

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Sparticle production at LHC

qqqqg ~,~~)~()~( qmgm Region

1

Region 2, e.g.

bbbbgqgqL ~,

~~,~~

Region 3 )~()~( gmqm qqgqgq ~,~~


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LHC inclusive reach (1) Using ET

miss + jets signature:

~1 pb at 1 TeV After 1 year: ~10

fb-1/yearat “low luminosity” already significant reach

“High lumi” ~100 fb-1/year

With 300 fb-1,

squarks and gluinos up to ~ 2.5 TeV

CMSDiscovery at 5 s.d.


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LHC inclusive reach (2) Using ET

miss + leptons signature:

In large area,Several topologies aresimultaneously observable

ETmiss likely to be a first hint But does not uniquely

identify SUSY

CMS


Luc Pape, CERN 92

CERNCERNDecay signatures in (m0,m1/2)

To prove SUSY: (MSUGRA)Need more specific signatures

100%significant

01

002 h

01

002 Z

01

02 ll

ll ~0

2)(

)(

)( A

01

~ qqR 02

~ qqL

More general than strict MSUGRA


Luc Pape, CERN 93

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Decay chain to dileptons

g~ q~

q q

02 l

~

l

missTE01

l


Luc Pape, CERN 94

CERNCERNFinal states with dileptons (1)

M(ll): very sharp end point

M(llq) softer edge,Obtained by extrapolation

)1)(1(2~

2

2

2~max

01

02

20

l

lll M

M

M

MMM

)1)(1(2~

2

2

2~max

01

02

20

l

lll M

M

M

MMM

M(ll)

M(llq)

ATLAS

%1.0/ MM

%1/ MM

)1)(1(2

2

2~

2

~max

02

01

02

M

M

M

MMM

qqllq


Luc Pape, CERN 95

CERNCERNFinal states with dileptons (2)

M(l1q):

M(l2q): leptons in sameconfiguration as for M(ll)max

Can distinguish M(l1q)max from M(l2q)max

4 unknown masses:4 endpoints: all masses can be determinedMore information available: constraints(other end points, gluino decay)

)1)(1(2~

2

2~

2

~max2

01

02

lqqql M

M

M

MMM

)1)(1(2

2~

2~

2

~max1

02

02

M

M

M

MMM l

qqql

01

02

,,, ~~ MMMM

lqmaxmaxmaxmax )(,)2(,)1(,)( llqMqlMqlMllM


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Decay chain to h0 or Z0

g~ q~

q q

02

missTE01

00 ,Zh


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Final states with h0 or Z0

Higgs can be reconstructed from b-bbar jetsCould be a h0 discovery channel

Z0 reconstructed from di-lepton decay

Decay chain is shorter than for di-leptons

1. Either need start from gluinoM(q1h0),M(q2h0),M(qq),M(qqh0)

to determine 4 masses2. Or start from squark and

combine with another channel

ATLAS

M(bb)


Luc Pape, CERN 99

CERNCERNMultiple end points in decays

Multiple decay modes

Multiple heavy 0i decays

D1 D2 D3 D4 ATLAS, Point SPS1A

(m0=100, m1/2=250, tan=10)

01

02 ,

~ llll

01

04

~ llllR01

04

~ llllL02

04

~ llllL

12~ lllL

CMS

ATLAS


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LHC summary LHC could discover SUSY quite early

With 10 fb-1 squarks/gluinos up to 1.5-2 TeV

Ultimate reach (300 fb-1) up to ~2.5 TeV LHC can also reconstruct sparticle masses

For all decay modes of 02, even in decays

Reasonable accuracy: (ATLAS, Gjelsten et al., ATL-PHYS-2004-007, SPS1A) M ~ 5 GeV for neutralinos and sleptons (2.5-5%) M ~ 10-15 GeV for gluino and squark (jet E-resolution)

(2-3%)

Futher work needed (cross-sections, spin correlations, “flavour”

identification, …)


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Comparison LHC/LC/CLIC Complementary reach LHC: h0, squarks, gluino eeCOL: sleptons,

gauginos Ecms limited

Not fully representative Precision is also

important May need >3 TeV to

unravel whole spectrum

M.Battaglia et al.,hep-ph/0306219


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Lepton Colliders More precise than LHC E.g. smuon pair production

2 edgesdetermines both masses Precision 2-3% at 1 TeV mass

Threshold scan improves precision further Precision 1-2% at 1 TeV mass Improves over LHC by 5-10 for neutralino

and slepton Can use beam polarization

Increase/decrease cross section selectivelyfor signal and background

But:

CLIC 3 TeV

2

2~

2~

2~minmax, 11)1(2

01

beamE

M

M

MME

Limited by beam energy

GeVMM 652,1145 01

~


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Extrapolation to GUT scaleLHC only LHC + LC

Blair, Porod, Zerwas, hep-ph/0011367


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Conclusion Today: completely in the dark (SM works too well) Something must exist beyond the SM But large number of candidate models Among them, SUSY is a respectable candidate Which SUSY? MSUGRA, GMSB, AMSB, RPV, NMSSM,

Hope to see something at LHC (light Higgs!) Then, will require another generation of

accelerators LC, CLIC, MUCOL, VLHC, …

It is time that we discover something!

Eagerly need experimental guidance


Luc Pape, CERN 106

CERNCERNFurther reading (biased sample)

Basic MSSM Perspectives on Supersymmetry, World Scientific,

Singapore 1998, ed. G.L.Kane S.P.Martin, A Supersymmetry Primer, hep-ph/9709356

v.3 H.Haber and M.Schmitt, Supersymmetry, PDG2004,

http://pdg.lbl.gov/

Higgs The Higgs Hunter’s Guide, Addison-Wesley 1990, ed.

J.F.Gunion, H.E.Haber, G.Kane, S.Dawson Perspectives on Higgs Physics, World Scientific,

Singapore 1993, ed. G.L.Kane M.Spira, P.M.Zerwas, Electroweak symmetry breaking

and Higgs physics, hep-ph/9803257

supersymmetry searches at colliders

Documents