There’s Something About SUSY m. spiropulu EFI/UofC oct 3 2002

about SUSY Something Heavy Supersymmetry is the most plausible solution of the hierarchy (issue)  Something Light low energy Supersymmetry is required  Something Dark might provide the missing matter of the universe if the lightest neutralino is stable Something Beautiful the symmetry between fermions and bosons Something Cool they couple with known and sizable strengths Something Exotic a component of string theory Something Urgent testable at high enough energies (now)

SUSY is not a (super)model SUSY is a spontaneously broken spacetime symmetry

bosons-fermions I Bosons: Commuting fields Integer spin particles Bose statistics Fermions: Anticommuting fields Half-integer spin particles Fermi statistics [anticommutativity ab=-ba and aa=-aa=a2=0 If a is the operator that creates an electron into a given state, a2 creates two electrons into the same state.] A superspace has extra anticommuting coordinates q anticommutativity ab=-ba and aa=-aa=a2=0 If a is the operator that creates an electron into a given state, a2 creates two electrons into the same state. C’est pa possible: This operator vanishes and the probability to have two electrons in the same state also vanishes. There is no (nonzero) state with two fermions in the same state (Pauli).

bosons-fermions II If we Taylor expand an electron (anticommuting field) in the extra coordinates electron field in superspace = selectron(boson) + electron(fermion) For each boson of spin J there is a fermion of spin J±½ of equal mass  This picture is not telling the whole story:SUSY is broken  The masses of the superparticles are not equal with their corresponding particles (or we would have seen them already).  So we start SUSY with a few new parameters and introduce a bunch more of what are called “soft breaking terms”: the masses of all the superparticles. Photon W,Z gluon Squark slepton Photino Wino,Zino gluino quark lepton quark quark gluino gluon squark quark equal couplings

general MSSM:370 parameters

particle content M1 M2 M3

supersymmetry in colliders  Tevatron mass reach: 400 – 600 GeV for gluinos, 150 – 250 GeV for charginos and neutralinos 200 – 300 GeV for stops and sbottoms  LHC reach: 1 – 3 TeV for almost all sparticles If SUSY has anything to do with generating the electroweak scale, we will discover sparticles soon. ( no experimental direct evidence for SUSY today)

strong, weak, electromagnetic forces have comparable strengths hierarchy of scales 10-17 cm Electroweak scale range of weak force mass is generated (W,Z) strong, weak, electromagnetic forces have comparable strengths 10-33 cm Planck scale GN ~lPl2 =1/(MPl)2 1028 cm Hubble scale size of universe lu 16 orders of magnitude puzzle What kind of physics generates and stabilizes the 16 orders of magnitude difference between these two scales 1027 eV 1011 eV 10-33 eV

bosons-fermions III Bose-Fermi Cancellation SUSY SM and the solution to the higgs naturalness problem (the radiative corrections to the higgs mass can not be 32 orders of magnitude larger than the higgs mass)

unification of couplings The gauge couplings of the Standard Model converge to an almost common value at very high energy. what’s up with that?

unification of couplings SUSY changes the slopes of the coupling constants For MSUSY=1 TeV, unification appears at 3x1016 GeV

Proton’s (don’t) decay (fast) In generic SUSies the proton could decay We have measurements to the contrary effect Satisfy this by conserving R-parity R=(-1)3(B-L)+2S

With R-parity conservation 370107 (soft breaking) parameters The end of the decay chain of all SUSY particles is the lightest supersymmetric particle (LSP) The properties of the LSP, generally determine the signature of SUSY LSP is stable – great dark matter candidate; In many SUSY models it also weakly interacting.

example of mSUGRA SUSY tanb m A squarks/sleptons gauginos higgses

example collider signatures

example backgrounds

more SUSY models Gauge mediated SUSY (LSP is the gravitino) photon-lepton signatures. M1:M2:M3=1:2:7 Anomaly mediated SUSY (LSPs are the Winos) disappearing tracks. M1:M2:M3=3:1:-8 String inspired models

SUSY mass clues Mass (GeV/c2) 220 190 170 97 45 Upper bound (stau coanihilation) TeVII reach Red : most natural mass* D0 220 CDF TeVII reach 190 D0 TeVII reach Mass (GeV/c2) 170 CDF D0 GMSB CDF LEP2 97 LEP2 CDF LEP2 D0 LEP2 LEP2 GMSB LEP2 LEP2 LEP2 45 LEP2 DM LEP2 LEP2 * Anderson/Castano

the dark side of SUSY Cosmology needs sources of non-baryonic dark matter  SUSies provide weakly interacting massive particles to account for the universe’s missing mass neutralinos sneutrinos gravitinos  We are closing in fast on either discovery or exclusion! There is a good complementarity between direct, indirect, and collider searches  

0.1 < Wc < 0.3 0.025 < Wc < 1 Tevatron reach already excluded CDMS, CRESST, GENIUS Tevatron reach LHC does the rest GLAST 0.1 < Wc < 0.3 0.025 < Wc < 1 J. Feng, K. Matchev, F. Wilczek

 How do we detect neutralino DM at colliders? look at missing energy (LSP) signatures: QCD jets + missing energy like-sign dileptons + missing energy trileptons + missing energy leptons + photons + missing energy b quarks + missing energy etc. 

CDF 300 GeV gluino candidate: gluino pair strongly produced, decays to quarks + neutralinos

detectors

machines Tevatron pp 14 TeV 1034 LHC (27 Km) ~2 x Tevatron (3.2 Km) Main Injector and Recycler p source Booster LHC (27 Km) ~2 x Tevatron (3.2 Km)

gluino decay path example

example cross sections L is the Luminosity e is the acceptance (trigger included) B is the Background s is the cross section (unit is area: the effective scattering size of a process) Total p/antip cross section is 7x10-30 m2 Unit of Barns (b) = 10-28m2 s(ppX)=70 mb Run I L ~ 1031 crossings/cm2/sec N/sec ~ sL = 7x105/sec >1 interactions per beam crossing! Cross Section for top production: s(pptt+X)=70 mb This is around 1/1010 of total N/sec ~ sL = 7x10-5/sec A couple were created/day but we only saw a small % ~100 events in 3 ys in two experiments

recording the physics: triggering

recording the physics: triggering

recording the physics: triggering

Calorimeter energy Central Tracker (Pt,f) Muon stubs Cal Energy-track match E/P, Silicon secondary vertex Multi object triggers Farm of PC’s running fast versions of Offline Code  more sophisticated selections

Missing ET + multijets (CDF) q f Missing Energy provides R-parity conserving SUSY signatures (R=(-1)3B+L+2S) and also appears in many other phenomenological paradigms MET + 3 jets (squarks,gluinos) MET + dileptons + jets (squarks gluinos) MET + c-tagged jets (scalar top) MET + b-tagged jets (scalar bottom,Higgs) MET + monojet (gravitino, graviton) MET + photons (gravitino)

Production/Decay Graphs

“Fake” MET QCD Use to define fiducial jets gap cosmic Main Ring  DETECTOR NOISE  COSMICS eliminated with a set of timing and good jet quality requirements Main Ring & QCD mismeasurements Use to define fiducial jets QCD gap

Standard Model Missing Energy +jets  Z/W +jets MC norm to Z data  QCD MC norm to jet data  top, dibosons MC norm using theory cross section

Analysis 0 >0 “blind analysis” approach HT=ET(2)+ET(3)+MET Number of High PT isolated tracks 0 >0 “blind analysis” approach where you expect your signal don’t look until you are ready

Optimization for SUSY

comparisons around the “box” Q C D Z(inv) W(m,e) top W(t)

“The BOX” The Box: SM Expected 76±13 Found in data 74

“The other BOXes” A/D SUSY boxes: SM Expected 33±7 Found in data 31

“The other BOXes” SUSY box C: SM Expected 10.6±1 Found in data 14

LIMITS

Candidate Event Knowledge from this analysis applied in monojet+MET analysis with RunI data that can search for associate gluino-neutralino production (also KK graviton etc).

There’s Something About the gluino mass (why we think we’ll see it sooner than later) The required cancellation is easier if the gluino mass is not “too large”. susy – electroweak connection favors lighter gluinos to avoid tuning (G. Kane et al) look at models with nonuniversal gaugino masses

chargino/neutralino trilepton signature If this signal is observed , the structure in the l+l- mass distribution will constrain the c01 and c02 masses (difficult). LHC will take it from there.

stop signatures Aided by improved CDF/D0 lepton coverage and heavy flavor tagging

colliders, SUSY and baryogenesis since colliders will thoroughly explore the electroweak scale, we ought to be able to reach definite conclusions about EW baryogenesis EW baryogenesis in SUSY appears very constrained, requiring a Higgs mass less than 120 GeV, and a stop lighter than the top quark Baryogenesis requires new sources of CP violation besides the CKM phase of the Standard Model (or, perhaps, CPT violation). B physics experiments look for new CP violation by over-constraining the unitarity triangle SUSY models are a promising source for extra phases

such a light stop will be seen at the Tevatron

SUSY@LHC LHC is a SUSY factory. If LHC does not find SUSY forget about (weak scale) SUSY. High rates for direct squark and gluino production. Model independent measurement OK- Model independent limit DIFFICULT.

SUSY@LHC Use consistent model in simulations to study different cases. Combinatorial SUSY is the dominant background to SUSY. Guess and scan over the most difficult points of the multi-parameter-multi-model SUSY space. Ultimately you want to measure all the parameters of the model.

SUSY@LHC INCLUSIVE ANALYSES Correlates well with

AN EVENT SUSY@LHC

- SUSY@LHC h bb -1 SM SUSY

- h bb SUSY@LHC Method works over a large region of the parameter space in the SUGRA model Contours show number of reconstructed Higgs tanb=10 sgn m=+

SUSY@LHC

SUSY@LHC

There’s Something more About SUSY The predicted value of sin2(qW(MZ)) ~0.2314-0.25(as(MZ)-0.118)+0.002 (e.g. Ross et. al) within 1% of measured value The predicted upper limit on the higgs mass ~130 GeV (e.g. Carena et. Al, Ellis et. al …) with 115 lower experimental limit things get urgent EWSB through radiative corrections the massiveness of the top quark

L. Alvarez-Gaume, J. Polchinski, M. Wise NPB221:495 (1983) also L. Ibanez, and J. Ellis, D. Nanopoulos, K. Tamvakis the same year Quote from the abstract: "We discuss the motivation for considering models of particle physics based on N=1 supergravity...renormalization effects drive spontaneous symmetry breaking of SU(2)xU(1) to U(1) for a top quark mass between 55-200 GeV."

The immediate future HEP hadron collider program Run IIa Run IIb BTeV physics LHC physics Year: 2002 03 04 05 06 07 08 09 10

Higgs

The wager A light Higgs stabilized by TeV scale SUSY is what will be found.

something about terminology Not everything super- has to do with supersymmetry. (superconductor, supermarket, superstition, supernatural etc…) However, SUPERMAN does