SUSY Searches at the LHC – Where do we stand? Smaragda Lola Dept. of Physics, University of Patras HEP 2018 Recent Developments on Particle Physics and Cosmology

SUSY GUTs have very attractive features (talk by Q. Shafi) Outline We know that we need to go beyond the SM, due to - Neutrino masses & mixing - Baryon asymmetry in the universe - Origin of dark matter - Large number of arbitrary SM parameters (mostly in mass sector) - Hierarchy problem , especially if further unification exists SUSY GUTs have very attractive features (talk by Q. Shafi) However: No signal found at the LHC Severe constraints on at least the simplest models (i.e. talks by V, Mitsou and N. Saoulidou) What lies beyond the simplest models? - Break unification conditions of minimal schemes &/or - add new particles and interactions (softer fitting constraints) W negative (more interesting…) need to simulate in the programme

Success of Unification electric planets magnetic apple Electromagnetism Quantum mechanics Gravity mechanics Special Relativity Quant. ElectroDynamics GR Weak force Th. of everything Electroweak Theory Grand Unification? Strong force

Combine GUTs, SUSY and Flavour Symmetries Different predictions in various GUTs SO(10), SU(4) x SU(2)L x SU(2)R [422] SU(5), Flipped SU(5) [non-universal sfermion masses] Can we distinguish different scenarios? What are the expected sparticle correlations in each scheme? Several constraints from DM + LHC considerations What can the LHC and DM tell us on the underlying symmetries? Will start by briefly reviewing aspects of GUTS, SUSY and flavour symmetries that are useful for our discussion, And will then proceed to discuss lepton flavour violation in various scenarios.

SUSY – new particles and interactions Minimal SUSY Lagrangian– very simple rule: all SM interactions + those where 2 particles are substituted by sparticles i.e. Look at Simplest SUSY models first: - Missing Energy Signature - LSP as Dark Matter (one of our basic requirements)

SUSY has to be broken Soft SUSY breaking terms

The simplest models are too restrictive! To search for/exclude SUSY unification need to first consider several alternative possibilities Problem: Vast number of models How to distinguish between them? Try to address at the same time the origin of mass, combining GUT and flavour symmetries

MINIMAL MODIFICATIOS TO SOFT TERM UNIVERSALITY: Fermion fields in the same 16 2 Higgs fields in different 10 representations

Ellis, Mustafaev, Olive, Velasco-Sevilla Fermions in different representations 2 Higgs fields in different 10 representations

Flipped SU(5) - versus SU(5) Different field assignment in representations – different predictions (i.e. more freedom with stop masses as compared to SO(10), SU(5))

4-2-2 Unification -Lepton number a 4th color – thus unifying quarks and leptons -L-R symmetry, but asymmetric 4-2-2 also possible Pati, Salam, Lazarides, Shafi, King Antoniadis, Leontaris Fermions embedded as follows:

Correlations between the non-universal soft scalar masses and DM in different SUSY GUTS – very rich structure (CMSSM fpr xu,d,5,R = 1 / too restrictive) SO(10) [and SU(5)]: stop mass tends to become very heavy Flipped SU(5)]: stop-coannihilations possible Cannoni, Ellis, Gomez, SL, Ruiz de Austri

New signals, including gluino coannihilations! 422: Gomez, SL, Ruiz de Austri, Shafi New signals, including gluino coannihilations!

(s)Fermion hierarchies from flavour symmetries EVEN MORE FREEDOM : complete 3x3 structure of Mass Matrices (s)Fermion hierarchies from flavour symmetries (i.e. Why the top quark mass so much larger?) Simplest: a LR family symmetry generates the observed hierarchies Charges such that only 3 generation masses allowed (0 flavour charges for 3rd generation) The rest of the terms appear once the symmetry is broken Frogatt-Nielsen mechanism W negative (more interesting…) need to simulate in the programme Similarly for other fermions, including neutrinos

After symmetry breaking, Mup

SL, Ross

Flavour symmetries may also determine soft SUSY terms break soft term universality even further! L-R symmetric SU(5) L: (1,0,0) R: (3,2,0)

SO FAR Can identify patterns of soft SUSY-breaking terms at the GUT scale, compatible with DM predictions and LHC spectra The models predict different spectra for the same LSP mass, connecting possible observations with the underlying unified theory. In particular, SO(10), SU(5), flipped SU(5) and 4-2-2 lead to very different predictions, and are distinguishable in future searches. Flipped SU(5) and 422 predict stop-LSP coannihilations that are absent in the other groups and can be explored in LHC searches. 422 also predicts light gluinos, and gluino coannihilations.

R-violating SUSY In addition to the Yukawa couplings generating fermion masses also - These violate baryon & lepton number - If simultaneously present, rapid (unacceptable) p decay

Choices: X R-parity (SM: +1 , SUSY: -1) Forbids all terms with ΔL, ΔB LSP: stable, dark matter (DM) candidate Main Signal: Missing Energy Other symmetries, allowing only ΔL, or only ΔB LSP: unstable / do we lose SUSY DM (?) Signals: Multilepton and/or multijet events Single sparticle productions possible For ΔL (LLE, LQD) we look for: - ΔLi, new final state topologies -isolated leptons within jets with small missing energy For ΔB (UUD) bigger difficulties, except for t,b

(i) Simplest SUSY models – missing energy SUSY στο LHC (i) Simplest SUSY models – missing energy (ii)ΔL,ΔΒ≠0, rare leptonic/hadronic events MSSM

bonus – small neutrino masses, [in agreement with data]

For very small RPV couplings

Large RPV: Single sparticle productions at the LHC (Dimopoulos, Hall, Dreiner, Ross)

Various channels studied at the LHC 45 couplings! (9+27+9) Various channels studied at the LHC under the assumption of a single coupling dominance Typical λ, λ’, λ’’ bounds for sparticle masses of 1 TeV [λ133, λ’133, λ’’112, λ’’113 smaller]

Without such assumptions, Simple Models LLE: MSSM pair sparticle productions Direct decay to 2 LSP Χ0 RPV decay of Χ0 Also presence of neutrinos, thus limited Missing Energy [C]MSSM + 1RPV + RGEs Single coupling dominance Without such assumptions, the parametric space has not yet been scanned

CMSSM + 1 RPV + simplified models Dercks et al.,hep-ph/1706.09418 CMSSM + 1 RPV + simplified models Such RPV bounds directly translated to limits on other SM extensions: ie scalar leptoquarks, contact interactions i.e. Altarelli, Ellis, Giudice, SL, Mangano - 1997

Are these assumption obvious? Not really… L-R flavour symmetries (i.e. within SO(10)): Similar LLE,LQD,UDD (only the generation matters) w: flavour independent contributions (Ellis, SL, Ross) Single coupling dominance not generically valid!

Predictions for R-violating operators in different GUTS: What type of processes favoured in different groups? (proceed similarly to discussion for fermion mass terms) L-R symmetric – SO(10): similar LLE,LQD,UDD (only generation matters) - Bounds on products of couplings, due to correlations, translated to individual bounds /very restrictive [Ellis, SL, Ross] -1 coupling dominance disfavoured - Single sparticle productions disfavoured over MSSM ones, with RPV decays SU(5) – with U(1) charges chosen to match lepton data Very different expected correlations Larger hierarchies and dominance of fewer couplings Single sparticle productions better accommodated W negative (more interesting…) need to simulate in the programme 30

We need some insight for RPV hierarchies What can we do: We need some insight for RPV hierarchies (in analogy with those for fermion Yukawa couplings) Many possible channels – which ones to chose? Neutralinos-charginos couple to all 45 operators Ideal channels to study simultneously all hierarchies [Bomark, Choudhury, Kvellestad, SL, Osland, Raklev]

Neutralino Decays Have studied RPV hierarchies as predicted by flavour symmetries Parametric spaces beyond CMSSM Bomark, Chourdury, SL, Osland

Are chargino RPV decays also relevant? Bomark, Kvellastad, Osland, SL, Raklev For Wino or Ηiggsino LSP, chargino direct RPV decays possible W negative (more interesting…) need to simulate in the programme Diagrams for LQD (similar for LLE, UUD)

LLĒ LQD [ Χ0 -> (llν) ] Energetic leptons, with explicit ΔLi SU(2): at least 2 different leptons LQD Similar to neutralino decays(ljj, vjj) – BUT differ for LQ3D -Neutralinos: neutrino + jets OR charged lepton + top + jet -Charginos: charged leptons + jets, neutrinos + top + jet

UDD Generically a problem due to huge QCD background HOWEVER: Very distinct for: U3DjDk -Neutralino decays always involve a t -Chargino decays involve 3 down-type quarks (1 always b) -Moreover: bbj, ttj (για U3D1,2 D3)

Gravitino DM compatible with broken Rp! Very slow decays: Gravitino interatcions (~1/Mp) Phase space (light gravit.) Loops (~ fermion masses) Neutrino-neutralino mixing [Takayama, Yamaguchi], [Chemtob, Moreau][Buchmuler, Covi, Hamaguchi, Ibarra, Yanagida] [SL, P. Osland, A. Raklev]

NEED TO EXTEND THE SM & SUSY looked nice in this respect! CONCLUSIONS NEED TO EXTEND THE SM & SUSY looked nice in this respect! No sign of SUSY so far. BUT: There is an abundance of viable models with or without RPV Only the simplest ones have been studied extensively We cannot yet exclude SUSY without properly investigating these additional opportunities W negative (more interesting…) need to simulate in the programme 37