Fmn SUSY like In SUSY Outline Standard Model

Fmn SUSY like In SUSY Outline Standard Model Woes Allowed Symmetry SUSY Fixes all? ? 1/4/2022 Broken SUSY Are we really better off? Todd Huffman University of Oxford

Introduction SM Required: Higgs 1/4/2022 H 0 0 110<m. H<250

Finishing off Higgs (production processes) Associate Production Direct Production tt-fusion (gg tt. H 0) WW(ZZ)-fusion (gg qq. H 0) q’ q W, Z H 0 B) W, Z q’’ t g D) H 0 g Higgs-Strahlung (qq W(Z 0)H 0) 0 H q’ W, Z 0 C) q W, Z 0 1/4/2022 q’’’ gg-fusion (gg H 0) A) g g x H 0

Higgs Production (production cross section, NLO) 1/4/2022 Compare this to stot(pp)=O(100 mb) or even s(tt)=O(1 nb) at LHC

Higgs Decay (Branching Ratios) ? 160 Ge. V 1/4/2022 Hint: m. W = 80. 2

Still Hunting for Higgs Peter Higgs Edinburgh U. CDF 2006 results! 1/4/2022

Standard Model Woes – Does not predict the masses of ANY particles. – Only predicts masses of W and Z if we know what the Higgs vacuum expectation value is – Running coupling constants to not unify – Why do the quarks and leptons form generations? • All Fermions Left-hand SU(2) doublets and Right hand singlets – (e, ne)L (e)R (n)R? ? – Why are there only 3 generations? – What makes up all the matter in the Universe? – There is no obvious method of including gravity in this picture. 1/4/2022

Show Grand Unification Failure transparency!! 1/4/2022

Standard Model Woes l Hierachy Problem – Suppose we have a fundamental scalar boson (like the higgs boson) – Renormalization has to deal with F h l l h ~ F 1/4/2022 Quadradically Divergent!! AARRGGHH

Standard Model Woes l Hierachy Problem l OK Lets assume a cut-off where we are sure there is other physics at the scale of m. F. – Renormalization Higgs mass we actually measure ~ 0. 10 Te. V Bare Higgs mass ~ 1016 Te. V Result of the divergent integral cutoff at m. F. ~ 1016 -0. 10 Te. V Would Nature tune the cut-off scale so precisely? ? 1/4/2022

Standard Model Woes l Higgs – Indirect from • Top Mass and • W mass – Direct Searches • q+qbar Higgs • H b+bbar Current lower limit about 100 Ge. V/c 2 Upper limit from global Electroweak fits to all existing measurements. 1/4/2022

Colman - Mandula Theorem – Q: What kind of symmetries can you impose on a field theory and still have non-zero scattering? – Coleman and Mandula say there are only 2 classes of conserved quantities: • External – Poincare’ symmetry (Lorentz invariance) • Energy-momentum conservation • Angular momentum conservation • Internal – Gauge symmetries • Electric charge conservation • Color Charge conservation l Paper Claimed: No More Symmetries Left! 1/4/2022

Colman - Mandula Theorem – Loop hole! – Theorem does not forbid conserved charges that anti-commute. – The one symmetry left open to us is: • Q|fermion> |boson> • Q|boson> |fermion> – If we assume that nature takes on this symmetry you generate the Super. Symmetric family of theories. • (nature has taken every other available symmetry why not this one? ) 1/4/2022

Super Symmetry Every Particle now has a Supersymmetric partner. All quantum numbers are the same except the spin. Particle Spin SUSY spin 1/2 0 1 ½ Why not spin 1? Not “Minimal”, too many DOF 1/4/2022

The MSSM Note: The Supersymmetry is at the field level, NOT the particle level 1/4/2022

The MSSM l Why do we need all these left and right-handed SUSY states? l Why not just copy direct from the observed particles? l Electroweak force at the field level actually only couples to SU(2)L a pair of left-handed doublets. – This is NOT the W and Z bosons we see. – Need to add-in the observed right-handed fermions from QCD in a sensible way. l Add them in as SU(2) right-handed singlets. 1/4/2022

SUSY Solution l Hierachy Problem – Exact SUSY adds 2 scalars (one for left and one for right handed) for every massive Fermion F h FL, R + h l 2 h l l F h =0 OK…So where all the selectrons? A: SUSY must be a broken symmetry like SU(2) (Electro-weak). 1/4/2022

SUSY Solution l Soft Breaking – Make the scalar partners heavier than the fermions: – Then we get a correction to Mh of If d < O(1 Te. V), There’s no fine tuning needed in mh! 1/4/2022

Broken SUSY l Supersymmetric Theories describe the breaking through parameter sets all have: – 2 Higgs doublets 8 degrees of Freedom • Need 3 of them to make the physical W± and Z bosons. – Left with 5 physical Higgs states: • h 0, H 0(CP+), A 0(CP-), H± – SUSY particles with identical quantum numbers will mix: • (u. L, u. R) u 1, 2 (analogous for d squarks and selectrons) • (B, W 3, H 01, H 02) 01, 2, 3, 4 , H ) ± • (W 1, 2 1/4/2022

Broken SUSY l Many Supersymmetric Theories Require a new quantum number called R - parity l Multiplicative quantum number – sparticles and (antisparticles) have R parity = -1 – particles (antiparticles) have R parity = +1 – If conserved then the lightest Supersymmetric sparticle would be stable. • Cannot have Electric or Colour charge • Would behave like a really massive neutrino in a detector. g 1/4/2022 Decay chain

Show Long Decay Chain! 1/4/2022

CDF Detector 1/4/2022

Latest CDF Results (Neutralino) Simple Search! Search for: Two high energy photons Large Missing Energy Harder to set limit because neutralino is likely to interact via the weak force. Even the chargino (EM force) is suppressed compared to QCD at Tevatron. 1/4/2022

Latest CDF Results (Gluino – QCD interactions) l Much better! – Gluino has the same quantum numbers as the gluon, but it is a fermion. – Expect much higher rate of production at the Tevatron. • It’s essentially a gluon collider anyway. l Note sbottom in final state! 1/4/2022

Latest CDF Results (Gluino – QCD interactions) l Combined Limit – Sbottom and gluino l Expect to gain factor of 3 by the end of data taking in 2009. l ~400 -500 Ge. V/c 2 for gluino and squark mass limits. 1/4/2022

ATLAS Unclothed! 1/4/2022

Show ATLAS SUSY projections!!! Not a real slide 1/4/2022

SUSY allows Unification l Unification of Strong, Weak, and Electromagnetic forces. – They now all come together! 60 Electromagnetic IF: There is SUSY. 1/a AND: Forces do unify Then: SUSY threshold lies at 103 ± 1 Ge. V 1/4/2022 50 40 Weak 30 20 Strong 10 105 1010 1015 1020

SUSY Model Success? – We solve the Hierarchy problem – We get a motivation for the Higgs sector • But it’s more complicated than SM Higgs. – The Minimal Supersymmetric model allows the 3 forces to Unify at the GUT scale. – Requires a higgs mass less than 130 Ge. V/c 2 (falsifiable!) – Possible candidates for Dark Matter. l MSSM is a Superset of all reasonable models of Supersymmetry breaking. l Nature will pick only one…in which case we can gain – Example SUGRA: • 5 parameters predicts masses of ALL the SUSY particles, including Vacuum Exp. Value of Higgs (and hence W and Z mass) • Also requires that the Top quark mass be much larger than the masses of all the other quarks…. . one mystery explained. l To Be Continued at a Large Hadron Collider near you!!! 1/4/2022

Problem with the Heirarchy problem? l. Higgs – Indirect from • Top Mass & • W mass Upper limit from global Electroweak fits to all existing measurements. Demands a light Higgs boson!!! 1/4/2022

SUSY – The Small Heirarchy Problem? Or: what happens when theorists get nervous l Tevatron data is showing no sign of gluino or squark. – Soon the limits on their masses will make cancelation in the propogation of the Higgs so imperfect that it will be inconsistent with a low-mass Higgs. – Thus inconsistent with indirect searches! l Does this problem really exist? ? ? l To Be Continued at a Large Hadron Collider near you!!! 1/4/2022