tevatron for lhc

11Tracey BerryTracey Berry

Tevatron for LHC

& other & other

Tracey BerryRoyal Holloway

IOP, 31st January 2007


Why Exotics?

• Gauge hierarchy problem: why is the EW scale so small?• Dark matter problem: what is the nature most of the matter in the

Universe?• Unification hypothesis: do the forces unify at a high scale?

…..

Despite success of SM motivation for Exotics is strong …

E.g.

implies there is something new/exotic we haven’t yet found..


What new physics ?

• Supersymmetry• CHAMPs• Z’• Extra Dimensions• Black Holes

… in this talk, but many others………..

Aim: outline methods used at the Tevatron& plans for the LHC searches

• What new physics can we expect/hope (!) to see ? ….

–May be something totally unknown!


Supersymmetry

• SUSY gives rise to partners of SM states with opposite spin-statistics but otherwise same Quantum Numbers.

spin-1/2 matter particles (fermions) <=> spin-1 force carriers (bosons)

• Different mechanisms of SUSY breaking lead to different modelsMSSM, mSugra, GMSB, AMSB

• Expect SUSY partners to have same masses as SM states - Not observed

SUSY must be a broken symmetry

• Supersymmetry (SUSY) fundamental continuous symmetry connecting fermions and bosonsQ|F> = |B>, Q|B> = |F>

SUSY stabilises Higgs mass against loop corrections at EW scale Possible explanation of dark matter – Lightest Supersymmetric Particle

(LSP) SUSY modifies running of SM gauge couplings ‘just enough’ to give

Grand Unification at single scale.


SUSY Signatures

Q: What do we expect SUSY events @ hadron colliders to look like?

A: Typical decay chain:

• Strongly interacting sparticles (squarks, gluinos) dominate production.• Heavier than sleptons, gauginos etc. cascade decays to LSP.• Potentially long decay chains and large mass differences

– Many high pT objects observed (leptons, jets, b-jets).• If R-Parity conserved: LSP (lightest neutralino in mSUGRA) stable

and sparticles pair produced.– Large ET

miss signature

lqq

l

g~ q~ l~

~ ~

p p

e

H±H0

A

G

e

btscdu

gW±

Z

h

W±

Z~ ~ ~

g~

G~± 2~± 1

~

e

e

btscdu~ ~

~~

~ ~~ ~ ~

~~~

04

~03

~02

~01

~H-

d~H

+u

~H0d

~H0u

~


SUSY @ Tevatron

Cro

ss S

ecti

on

(p

b)

T. Plehn et al.

SUSY searches key goal of Tevatron experiments

• Hadron collider large cross-section for producing strongly interacting sparticles

– Jets + ETmiss searches

But small kinematic reach:

– Limited pT separation from SM hadronic backgrounds

– Short decay chains give limited signal multiplicity (jets, leptons)

• Alternative: lower backgrounds– Trilepton searches

• Alternative: rare decays

– Bs


Run II: Jets + ETmiss

• E.g. CDF Selection:

– 3 jets with ET>120 GeV, 70 GeV and 25 GeV

– Missing ET>90 GeV

– HT=∑ jet ET > 280 GeV

– Missing ET not along a jet direction:

• Background:– W/Z+jets with Wl or Z– Top– QCD multijets

• Mismeasured jet energies lead to missing ET

• No excess observed– Exclude regions of squark /

gluino mass plane (mSUGRA projection)

Observe 40

Expect 56 ± 3 ± 14

– Missing ET not along a jet direction:

• Avoid jet mismeasurements


ATLAS

5

5

• Inclusive searches with Jets + n leptons + ETmiss channel.

• Map statistical discovery reach in mSUGRA m0-m1/2 parameter space.

• Sensitivity only weakly dependent on A0, tan() and sign().

LHC: Jets + ETmissLHC: Jets + ETmiss

“Golden channel at the LHC”


Run II: Trileptons

Golden channel at TeVatron

Striking 3 isolated l signature Low background Easy to trigger

If Rp conserved

• Alternative approach at Tevatron: reduce hadronic background with multi-lepton requirement

• Sensitive to gaugino (chargino/neutralino) production• Analyses depend on SUSY model:

– Low tan:• 2e+e/ • 2+e/

– High tan (BR( ) enhanced):• 2e+isolated track (1-prong )

• Other requirements (typical):

– Large ETmiss

– mll>15 GeV, mll = mZ

– Njet < 2


Run II Trileptons

ee+l, e+l

+l, e+l

ee+track, +track

700-1000 pb-1

122 GeV/c^2, .Br = 0.42 pb.

162 < M1/2 230 GeV/c2.

tan=3, >0

MSSM with W/Z decays

162 < M1/2 240 GeV/c2., M0=70

Limit on mass of the chargino of 122 GeV/c^2, corresponding on sigma times Br of 0.42 pb.

129 GeV/c2,

.Br = 0.25 pb.

• CDF then combine the trilepton and dilepton SUSY search results: to obtain limits on m(chargino) & .Br in various SUSY models

enhanced BR of chargino & neutralino to e &

Predicted Central 0.44±0.06Plug 0.34±0.1Total Observed 0

Predicted 0.64±0.18Total Observed 1


CDF Like-sign Dileptons• Search for 2 high-momentum

same-sign leptons

Predicted 7.9 ± 1.0Observed 13

CDF observe an excess of events!

Predicted 33.7± 3.5 events Observe 44

Background:W, Diboson, ttbar, Drell-Yan, fakes

• Tighter sample: Z veto and MET>15 GeV requirement

This search is sensitive to New Physics with three or more leptons, such as SUSY trilepton signatures, or signals with Majorana particles, e.g gluino pair production signatures with decays into leptons.


• SM BR heavily suppressed:

• SUSY enhancements ~ tan6()/mA4

• Complementary to trilepton searches:

910)9.05.3()( sBBR

• Preselection (CDF):– Two muons with pT>1.5 GeV/c– Displaced dimuon vertex

• Search for excess in Bs (also Bd) mass window• Background estimated using a linear

extrapolation from the sidebands, and normalised to data BK

Results compatible with SM backgrounds:– 1(0) CMU(CMX) events observed, – 0.88± 0.30(0.39 ± 0.21) CMU(CMX) exp.

• Combined Limit:– BR(Bs->)<1.0 x 10-7 at 95%C.L.

• Future Run II limit ~2x10-8 (8 fb-1)

Trileptons: 2fb-1

Trileptons: 2fb-1

Trileptons

2, 10 ,30 fb-1 @Tevatron

Bs

Run II: Bs

important at high tan


LHC: Exclusive Studies LHC: Exclusive Studies • Prospects for kinematic measurements at LHC: measure weak scale SUSY parameters (masses etc.) using exclusive channels.• Different philosophy to TeV Run II (better S/B, longer decay chains) aim to use model-independent measures.

• Two neutral LSPs escape from each event – Impossible to measure mass of each sparticle using one channel alone

• Use kinematic end-points to measure combinations of masses.• Old technique used many times before ( mass from decay spectrum, W (transverse) mass in Wl).• Difference here is we don't know mass of neutral final state particles.

lqql

g~ q~ lR

~~

~p p


LHC: Dilepton EdgeLHC: Dilepton Edge

~~02

~01

l ll

e+e- + +-

~~

30 fb-1

atlfast

Physics TDR

Point 5

e+e- + +- - e+- - +e-

5 fb-1

SU3

ATLAS ATLAS

•m0 = 100 GeV•m1/2 = 300 GeV•A0 = -300 GeV•tan() = 6•sgn() = +1

• When kinematically accessible canundergo sequential two-body decay to via a right-slepton (e.g. LHC Point 5).

• Results in sharp OS SF dilepton invariant mass edge sensitive to combination of masses of sparticles.

• Can perform SM & SUSY background subtraction using OF distribution

e+e- + +- - e+- - +e-

• Position of edge measured with precision ~ 0.5% (30 fb-1).


LHC: Endpoint MeasurementsLHC: Endpoint Measurements• Dilepton edge starting point for reconstruction of decay chain.• Make invariant mass combinations of leptons and jets.• Gives multiple constraints on combinations of four masses. • Sensitivity to individual sparticle masses.

~~~

l ll

qL

q

~

~~

bh

qL

q

~

b

llq edge1% error(100 fb-1)

lq edge1% error(100 fb-1)

llq threshold2% error(100 fb-1)

bbq edge

TDR,Point 5

TDR,Point 5

TDR,Point 5

TDR,Point 5

ATLAS ATLAS ATLAS ATLAS

1% error(100 fb-1)


LHC: Sparticle Masses

• Combine measurements from edges from different jet/lepton combinations to obtain ‘model-independent’ mass measurements.

01 lR

02 qL

Mass (GeV)Mass (GeV)

Mass (GeV)Mass (GeV)

~

~

~

~

ATLAS ATLAS

ATLAS ATLAS

Sparticle Expected precision (100 fb-1)

qL 3%

02 6%

lR 9%

01 12%

~

~

~

~

LHCCPoint 5

• Also measurements of spin (Barr)


Champs CHArged Massive stable Particles:

-electrically charged-massive speed<<c-lifetime long enough to decay

outside detectorEvent Selection:-2 muons Pt> 15 GeV, isolated-Speed significantly slower than c

Expected Observed

0.66±0.06 0

100 GeV Staus 100 GeV Higgsino-like

Chargino 100 GeV Gaugino-like

Chargino

~~

Limits in AMSB:

champ = ±

M(±1)>174 GeV/c2


Tevatron Resonance Searches

95% C.L. lower limits on the littlest Higgs Z' models

CDF: Search for a resonance in a particular channele.g. ee, or

ee, : 200pb-1: Higgs, Sneutrino (Spin-0); Z’ (Spin-1), Randall-Sundrum Graviton

(Spin-2) ee: 448 pb-1: Z’, Littlest Higgs Z, Contact Interactions,

AFB

ee: 819 pb-1: Z’, RS Graviton: 1 fb-1: RS Graviton

Combined channels later: e.g. ee+ for RS modelD0: Performed specific model dependent searches

Randall-Sundrum Graviton: ee+ 1 fb-1, ~250 pb-1

Tev-1 ED model search: ee: 200pb-1

Different techniques used by CDF and D0


Run II: Dielectron Resonances• Dielectron channel:

studied invar. mass and AFB

show no evidence of excess

• Limits on Z’ (peak) from 650 GeV (Zl) – 850 GeV (SM)

95% C.L. lower limits on the littlest Higgs Z' models

• Used same data (448 pb-1) to set limits on…


Extra Dimensional Models

GArkani-Hamed, Dimopoulos, Dvali, Phys Lett B429 (98)

Dienes, Dudas, Gherghetta, Nucl Phys B537 (99)

-1 sized EDs

Planck TeV braneRandall, Sundrum, Phys Rev Lett 83 (99)b

(Many) Large flat Extra-Dimensions (LED) could be as large as a few mIn which G can propagate, SM particles restricted to 3D brane

Small highly curved extra spatial dimension (RS1 – two branes) Gravity localised in the ED

Bosons could also propagate in the bulk Fermions are localized at the same (opposite) orbifold point: destructive (constructive) interference between SM gauge bosons and KK excitations

SM Gauge Bosons

W, Z, , g

SM chiral fermions

Original models were proposed as a solution to the hierarchy problem

Why is gravity weak compared to gauge fields?

MEW (1 TeV) << MPlanck (1019 GeV)?

Since then, many new models have been introduced to solved other problems: Dark Matter, Dark Energy, SUSY Breaking, etc


Signature: Narrow, high-mass resonance states in dilepton/dijet/diboson channels

700 GeV KK Graviton at the Tevatron

k/MPl = 1,0.7,0.5,0.3,0.2,0.1 from

top to bottom

Mll (GeV)

Mll (GeV)

Davoudiasl, Hewett, Rizzo hep-ph0006041

1000 3000 5000

10.50.10.050.01

KK excitations can be excited individually on

resonance

1500 GeV GKK and subsequent tower states

K/MPl

LHC

Experimental Signature for Model

jetjet,,,eeGgg,qq KK

d/dM (pb/GeV)

10-2

10-4

10-6

10-8

10-10

400 600 800 1000

Model parameters:• Gravity Scale:

1st graviton excitation mass: m1

= m1Mpl/kx1, & mn=kxnekrc(J1(xn)=0) • Coupling constant: c= k/MPl

1 = m1 x12 (k/Mpl)2

width

positionResonance

= Mple-kRc

k = curvature, R = compactification radius

1 extra warped dimension


Tevatron RS Searches

D0 performed combined ee+ (diem search)

CDF performed ee & search, then combine

• Graviton decaying to ee or ()• Backgrounds:

– Drell-Yan ee, direct production– Jets: fake e, 0,

• Data consistent with background

• Limits on coupling (k/MPl ) vs m(1st KK- mode)

CDF implemented a special trigger:

“SUPER PHOTON_70” To keep high efficiency at high mass: Had/Em inefficient at high ET asEM E saturates, so is miscalculated. PHOTON 70 has no HAD/EM cut


LHC: RS Discovery Limits

• Search for gg(qq) G(1) e+e- ATLAS study using test model with k/MPl=0.01 (narrow resonance).

• Signal seen for mass in range [0.5,2.08] TeV for k/MPl=0.01.

• Measure spin (distinguish from Z’) using polar angle distribution of e+e-.

• Measure shape with likelihood technique.

• Can distinguish spin 2 vs. spin 1 at 90% CL for mass up to 1.72 TeV.

Experimental resolution

m1 = 1.5 TeV

100 fb-1 100 fb-1

ATLAS

ATLAS

m1 = 1.5 TeV 100 fb-1

ATLAS

• At ATLAS best channels to search in are G(1)e+e- and G(1)due to the energy and angular resolutions of the LHC detectors

• G(1)e+e- best chance of discovery due to relatively small bkdg, from Drell-Yan*

A resonance could be seen in many other channels: , , jj, bbbar, ttbar, WW, ZZ, hence allowing to check universality of its couplings.


CMS RS Discovery LimitsGG11

GG11μμ++μμ--

Theoretical Constraints

c>0.1 disfavoured as bulk curvature becomes to large (larger than the 5-dim Planck scale)

LHC completely covers the region of interest

• c>0.1 disfavoured as bulk curvature becomes to large (larger than the 5-dim Planck scale)

• Theoretically preferred <10TeV assures no new hierarchy appears between mEW and

Theoretical Constraints

Solid lines = 5 discoveryDashed = 1 uncert. on L

GG11eeee


TeV-1 Extra Dimension Model

ppZ1KK/1

KKe+e-

New ParametersR=MC

-1 : size of the compact dimension MC : corresponding compactification scale M0 : mass of the SM gauge boson

Mn = M0

I. Antoniadis, PLB246 377 (1990)

• Multi-dimensional space with orbifolding (5D in the simplest case, n=1)

• The fundamental scale is not planckian: MD ~ TeV

• Gauge bosons can travel in the bulk Search for KK excitations of Z,..

• Fundamental fermions (quarks/leptons) can be localized at the same (M1) or opposite (M2) points of orbifold destructive (M1) or constructive (M2) interference of the KK excitations with SM model gauge bosons

Characteristic Signature: KK excitations of the gauge bosons appearing as resonances with masses : Mn = √(M0

2+n2/R2) where (n=1,2,…) & also interference effects!

me+e- (GeV)

G. Azuelos, G. Polesello EPJ Direct 10.1140 (2004)

• Look for l+l- decays of and Z0 KK modes. Also in decays (mT) of W+/- KK modes. Or evidence of g* via dijet or bb, tt s


Tevatron/LHC: TeV-1 ED Searches

L = 200pb-1predicted background

TeV-1 ED signal c=5.0 TeV-2

SM Drell-Yan

D0 performed the first dedicated experimental search for TeV-1 ED at a collider

Lower limit on the compactification scale of the longitudinal ED: MC>1.12 TeV at 95% C.L. (M1 model)

With L=30/80 fb-1 CMS will be able to detect a peak in the e+e- invar. mass distribution if MC<5.5/6 TeV.

5 discovery limit ofppZ1

KK/1KKe+e-

• 2 high pT isolated electrons • Bckg: irreducible: Drell-YanAlso ZZ/WW/ZW/ttbar

ppZ1KK/1

KKe+e-


TeV-1 ED Discovery Limits


1) Model independent search for the resonance peak– lower mass limit

2) 2 sided search window – search for the interference

3) Model dependent – fit to kinematics of signal

ATLAS have studied 3 methods to determine the discovery limits for this signature: model independent & dependent

(1)/Z(1)→e+e-/+-

x1PA

x2PB

Event kinematics* can be fully defined by the 3 variables

~8 TeV for L=100 fb-1 ~10.5 TeV for 300 fb-1

13.5 TeV with 300 fb-1

MC (R-1)<5.8 TeV :100 fb-

1

For (ee+) using this method, the reach is

2 leptons with Pt>20GeV in ||<2.5, mll>1TeV

ATLAS expectations for e and μ:2 leptons with Pt>20GeV in ||<2.5, mll>1TeVReducible backgrounds from tt, WW, WZ, ZZPYTHIA + Fast simu/paramaterized reco + Theor. uncert.


: pT measured in tracker

k/MPl=0.05k/MPl=0.05

ee+: EM energy determined using calorimeters

Symmetric windows width 6 x detector resolution

Asymmetric windows only lower mass bound used (due to long high-mass tail)

Search Region Selection Observable width is combination of intrinsic new physics & detector resolutionDetector resolutions influence the choice of search windows

6

ee+ channel channelSimilar issues at the LHC

RS Graviton Search

TeV-1 ED Search

ee channel: experimental resolution is smaller than the natural width of the Z(1)

channel: exp. momentum resol. dominates the width


ADD Collider Signatures

Jets + missing ET, γ + missing ET

llqq llgg

Signature: deviations in and asymmetries of SM processes e.g. qq l+l-, & new processes e.g. gg l+l-

Virtual Graviton exchange

g,qg,q jet,V

GSignature: jets + missing ET, V+missing ET

depends on the number of ED

Real Graviton emission in association with a vector-boson

Run I

CDF Run I =+1

Broad increase in due to closely spaced summed over KK towers

Mll

g,qg,q

f,Vf,V

G

Excess above di-lepton continuum


Present ADD Emission LimitsLEP and Tevatron results are complementary

+MET LEP limits bestFor n>4:

jet+MET

CDF limits best

q

q

g

Gkk Gkk_

g

g

g

n MD (TeV/c2)

K=1.3

R (mm)

2 > 1.33 <0.27

3 > 1.09 < 3.1x10-6

4 > 0.99 < 9.9 x 10-9

5 > 0.92 < 3.2 x 10-10

6 > 0.88 < 3.1 x 10-11

For n<4:


MPl(4+d)MAX(TeV

)=2 =3 =4

LL 30fb-1 7.7 6.2 5.2

HL 100fb-1 9.1 7.0 6.0

•Signature: jet + G jet with high transverse energy (ET>500 GeV)+ high missing ET (ET

miss>500 GeV), • vetos leptons: to reduce jet+W bkdg mainly• Bkgd.: irreducible jet+Z/W jet+ /jet+l jZ() dominant bkgd, can be calibrated using ee and decays of Z.

Real graviton production

L.Vacavant, I.Hinchcliffe, ATLAS-PHYS 2000-016

ppjet+GKK

Discovery limits

gggG, qgqG & qqGg

Dominant subprocess

ADD Discovery Limit: G Emission

J. Phys., G 27 (2001) 1839-50

• G high-pT photon + high missing ET

• Main Bkgd: Z,

At low pT the bkgd, particularly irreducible is too large require pT>400 GeV

Also W e(), W e+jets, QCD, di-, Z0+jets

pp+GKKJ. Weng et al. CMS NOTE 2006/129

MMDD= = 1– 1.5 1– 1.5 TeV for 1 fbTeV for 1 fb-1-1

2 - 2.5 2 - 2.5 TeV for 10 TeV for 10 fbfb-1-1

3 - 3.5 3 - 3.5 TeV for 60 TeV for 60 fbfb-1-1

Rates for MD≥ 3.5TeV are very low – too low for 5 discovery


D0 ee+ ADD LED (cos*) spectrum to extract limitsD0 perform a combined fit of the invariant mass and angular information

low mass, high cos*

SM events expected to be distributed uniformly in cos*

Signal events are accumulated at low cos* & high mass

And to maximise reconstruction efficiency they perform combined ee+ (diEM) search: reduces inefficiencies from

• ID requires no track, but converts (ee)• e ID requires a track, but loose track due to imperfect track reconstruction/crack

0.96/0.93

0.85

0.900.971.071.271.091.07μμ246D0

Λ=+1/λ=-1

n=7n=6n=5n=4n=3n=2

1.17

0.879

1.74

-

1.48

1.10

1.76

1.31

1.33

0.999

1.32/1.21

1.241.48ee+γ

γ275D0

0.987/0.959

0.9291.10ee200CDF

Hewett[3]

HLZ[2]GRW[1]

Final state

L

(pb-

1)

RunI+RunII

most stringent collider limits on

LED to date!


Virtual graviton production

1 fb-1: 3.9-5.5 ТеV for n=6..310 fb-1: 4.8-7.2 ТеV for n=6..3100 fb-1: 5.7-8.3 ТеV for n=6..3300 fb-1: 5.9-8.8 ТеV for n=6..3

• Two opposite sign muons in the final state with M>1 TeV

•Irreducible background from Drell-Yan, also ZZ, WW, WW, tt (suppressed after selection cuts)• PYTHIA with ISR/FSR + CTEQ6L, LO + K=1.38

ppGKK

ADD Discovery Limit: G Exchange

Belotelov et al.,CMS NOTE 2006/076, CMS PTDR 2006

Fast MC

V. Kabachenko et al. ATL-PHYS-2001-012


LHC: Black Hole Signatures

• In large ED (ADD) scenario, when impact parameter smaller than Schwartzschild radius Black Hole produced with potentially large x-sec (~100 pb).

• Decays democratically through Black Body radiation of SM states – Boltzmann energy distribution.

Mp=1TeV, n=2, MBH = 6.1TeV

Dimopoulos and Landsberg PRL87 (2001) 161602

• Discovery potential (preliminary)

– Mp < ~4 TeV < ~ 1 day

– Mp < ~6 TeV < ~ 1 year

• Studies continue …

ATLAS w/o pile-up

w/o pile-up ATLAS


Strategy to Search for New Physics

• Aim in searches for New Physics is to find a deviation from the expected/ SM.

• To do this first need to know what the SM looks like in the new detector… i.e.– first it will be important to understand the detector:– Calibration….

• To quote Ian Hinchcliffe from 2005…We first need to study


Summary!

• Exotics searches well underway at Tevatron• Statistics increasing rapidly now

• New searches commencing soon at LHC• Many more exotics searches not covered here…

Leptoquarks, Technicolor, more SUSY and ED searches….• Good prospects for exciting discoveries

• Exciting times ahead!

• Exotics searches well underway at Tevatron• Statistics increasing rapidly now

• New searches commencing soon at LHC• Many more exotics searches not covered here…

Leptoquarks, Technicolor, more SUSY and ED searches….• Good prospects for exciting discoveries

• Exciting times ahead!


Distinguishing Z(1) from Z’, RS G• Spin 1 Z(1) signal can be distinguished from a spin-2 narrow graviton

resonance using the angular distribution of its decay products. • Z(1) can also be distinguished from a Z’ with SM-like couplings using

the distribution of the forward-backward asymmetry: due to contributions of the higher lying states, the interference terms and the additional √2 factor in its coupling to SM fermions.

The Z(1) can be discriminated for masses up to about 5 TeV with L=300fb-1.


ATLAS

Z(1) or Z’ or RS Graviton? 4 TeV resonances


4 TeV resonances


SM

R-1=4 TeV

R-1=6 TeV

SM

W1 eFor L=100 fb-1 a peak in the lepton-neutrino transverse invariant mass (mT

l)

WKK decays

TeV-1 ED Discovery Limits

Isolated high-pT lepton >200 GeV + missing ET > 200 GeV Invmass (l,) (ml> 1 TeV, veto jets

Bckg: irreducible bkdg: We, Also pairs: WW, WZ, ZZ, ttbar

Sum over 2 lepton flavours

R-1=5 TeV

mTe (GeV)

G. Polesello, M. Patra EPJ Direct C 32 Sup.2 (2004) pp.55-67

G. Polesello, M. Patra EPJ Direct, ATLAS 2003-023

=√2peTp

T(1-cos)

Peak detected if the compactification scale (MC= R-1) is < 6 TeV

If no signal is observed with 100 fb-1 a limit of MC > 11.7 TeV can be obtained from studying the mT

e distribution below the peak:

- Can’t get such a limit with W since momentum spread - can’t do optimised fit which uses peak edge


SM

Can also Detect KK gluon excitations (g*) by reconstructing their hadronic decays (no leptonic decays).

This is more challenging than Z/W which have leptonic decay modesDetect g* by (1) deviation in dijet

(2) decays into heavy quarks

TeV-1 ED g* Discovery Limits

SM

M=1 TeV

M=1 TeV

M=1 TeV± 200 GeV

Gluon excitation decays

ttgqqbbgqq *,*

For ttbar one t is forced to decay leptonically

ttbar channel: R-1 = 3.3 TeV bbar channel: R-1 = 2.7 TeV

With 300 fb-1 Significance of 5 achieved for:*

M=2 TeV

* since there are large uncertainties in the calculations of the bkdgs: requires b-jet energy scale can be accurately computed.

M=2 TeV


CDF SS Dilepton Events

the two highest-E_T events, which are electron-electron, and of an e-μ event.

• This event has more than 100GeV Met. There are lots of piled-up interactions. the third electron does not come from the same interaction vertex.

Two electrons above 100 GeV each. In the same event we have a photon of 15GeV, Met of 25GeV and a third electron of 5GeV that does not pass the calorimeter isolation

e-mu


Run II Trileptons

SignalBackground

Expected

Observed Events


SUSY at the LHC• Ecm of 14 TeV available!!

• Between 1-2 fb-1 in the first year of data taking!

• In typical mSugra scenario, squarks and gluinos dominate => signatures with jets + MET

• Very quick discovery !

(all plots from Ian Hinchliffe, SUSY05)

~~• Direct production cross-sections small

– But could be the only way to observe SUSY if qg are heavy ! (“focus point”)

• In other regions trileptons signal enhanced from squark-gluino cascade


How fast can SUSY be found?

• Plot shows reach in SUSY model space

• Solid region is not allowed• Hatched region is already

ruled out by LEP• Contours label squark and

gluion masses and luminosity

• Example- 0.1 fb-1 discovers gluino mass 1 TeV

• This is 1 year at 1/1000 of the design luminosity!


Tevatron Experiments: CDF & D0

=1.0=0

=2.0

=3.0

Muon System

COT

Plug Calorimeter

Time-of-Flight

Central Calorimeters

Solenoid

Silicon Tracker

|| < 1

1<||<3

|| < 1.5

|| < 1

Hermitic calorimeter (central & plug)/muon coveragePrecision tracking and silicon vertex detectors Excellent particle ID


Else Lytken, Moriond QCD 2006 45

Indirect constraint: BS

• Look for excess of µµ events in Bs and Bd mass windows • Background estimation: linear extrapolation from sidebands• Results compatible with SM backgrounds Br(Bs)<1.0×10-7 @ 95%CL --- Closing in on SUSY! ---

Rare decay, SM branching frac ~10-9

Loop diagrams with sparticles (or direct decay if RPV) enhance orders of magnitude

Important at high tan

Previous limit:

hep-ph/0507233


Else Lytken, Moriond QCD 2006 46

Look in the Bs and Bd Signal Window

LR > 0.99

CMU-CMU Channel: Expect Observed ProbBs 0.88±0.30 1 67%Bd 1.86±0.34 2 63%

CMU-CMX Channel: Expect Observed ProbBs 0.39±0.21 0 68%Bd 0.59±0.21 0 55%


Projection Z’->ee


Allenach et al, hep-ph0211205

Also the size (R) of the ED could also be estimated from mass and cross-section measurements.

RS1 Model Parameters

Allenach et al, JHEP 9 19 (2000), JHEP 0212 39 (2002)

A resonance could be seen in many other channels: , , jj, bbbar, ttbar, WW, ZZ, hence allowing to check universality of its couplings:

Relative precision achievable (in %) for measurements of .B in each channel for fixed points in the MG, plane. Points with errors above 100% are not shown.


Total weight 7000 tOverall diameter 25 mBarrel toroid length 26 mEnd-cap end-wall chamber span 46 mMagnetic field 2 Tesla

Total weight 12 500 tOverall diameter 15.00 mOverall length 21.6 mMagnetic field 4 Tesla

Total weight 12 500 tOverall diameter 15.00 mOverall length 21.6 mMagnetic field 4 Tesla

Large general-purpose particle physics detectors

Detector subsystems are designed to measure:energy and momentum of ,e, , jets, missing ET up to a few TeV

ATLASCMS

ATLAS and CMS Experiments


RS1 Model Determination

Allanach et al, hep-ph 0006114

Note: acceptance at large pseudo-rapidities is essential for spin discrimination (1.5<|eta|<2.5)

e+e-

LHC

MC = 1.5 TeV

MG=1.5 TeV 100 fb-1

Stacked histograms

How could a RS G resonance be distinguished from a Z’ resonance?Potentially using Spin information:G has spin 2: ppGee has 2 components: ggGee & qqGee: each with different angular distributions:

Spin-2 could be determined (spin-1 ruled out) with 90% C.L. up to MG = 1720 GeV with 100 fb-1


Run at two different √s e.g. 10 TeV and 14 TeV, need 50 fb-1

To characterise the model need to measure MD and

Measuring gives ambiguous results (ppjet+GKK)

Use variation of on √s at different √s almost independent of MD,varies with

Rates at 14 TeV of =2 MD=6 TeV very similar to =3 MD=5 TeV whereasRates at 10 TeV of (=2 MD=6 TeV) and (=3 MD=5 TeV) differ by ~

factor of 2

ADD Parameters: jet+G Emission

L.Vacavant, I.Hinchcliffe, ATLAS-PHYS 2000-016J. Phys., G 27 (2001) 1839-50


Energy FrontierEnergy Frontier


SUSY Spectrum

• Expect SUSY partners to have same masses as SM states– Not observed– SUSY must be a

broken symmetry

• SUSY gives rise to partners of SM states with opposite spin-statistics but otherwise same Quantum Numbers.

e

H±H0A

G

e

bt

sc

du

g

W±

Z

h

W±

Z~ ~ ~

g~

G~± 2~± 1

~

e

e

bt

sc

du~ ~

~

~

~ ~

~ ~ ~

~

~

~

04

~03

~02

~01

~H-

d

~H+

u

~H0

d

~H0

u

~

spin-1/2 matter particles (fermions) <=> spin-1 force carriers (bosons)

• R-Parity Rp = (-1)3B+2S+L

- Conservation of Rp causes LSP to be stable

- Naturally provides solution to dark matter problem

• R-Parity violating models still possible not covered here.

• Different mechanisms of SUSY breaking lead to different models

MSSM, mSugra, GMSB, AMSB

tevatron for lhc

Documents