GAMBIT results and prospects for EDM studies

Martin White

(EDMs for beyond-SM physics studies)

Martin White

Opening remarks•We strongly suspect that the SM of particle physics cannot

be the final answer•We discovered the last piece of the SM in 2012 (the Higgs

boson) at the LHC•We've been searching for beyond-SM physics for nearly a

decade now

Martin White

How to find BSM physics at the LHC● There are two main ways to uncover evidence for new physics

1) Search directly: look for new particles being produced

● Look for functions of four vectors that discriminate between SM and SUSY

● Cut away the SM background as much as possible without hurting the expected signal

● Or look for bumps over SM expectation

2) Measure SM processes very precisely

● New physics can enter via loop diagrams

● Measuring SM processes checks consistency but also reveals new physics at high scales

What have we found?

Martin White

No evidence for BSM physics• There is no current evidence for BSM physics in ATLAS or CMS,

neither in SUSY-type searches, nor resonance searches• Anomalies come and go, and some are at the 3-4 sigma level•No SM measurement has generated sustained excitement so far• Except precision flavour measurements at LHCb which show

significant anomalies (seen also at flavour factories)

Martin White

Stupid conclusion 1

•Wrong, surely. It can't explain gravity, dark matter, flavour, the matter-antimatter asymmetry, dark energy, inflation, the low Higgs mass (unstable under radiative corrections), etc, etc

Martin White

Stupid conclusion 2

•Wrong. See later GAMBIT results for proof, but plenty of natural SUSY models would have slipped under the radar of current searches

Martin White

Stupid conclusion 3

•Wrong. GAMBIT results show that plenty of models with light particles are slipping under the radar of current searches.

Martin White

What we should be doing• Surprises are still likely at the LHC•We should be looking to combine insights from the LHC with

every other experiment that can test BSM physics• If the new physics really is at high energy scales, we should be

pursuing other experimental programs, but the results still need to be compared with LHC and other results

Martin White

Martin White

Isn't this an EDM workshop?• EDM measurements could be crucial in discovering the next

theory of particle physics•GAMBIT studies that include a detailed treatment of EDM

constraints would be amazing• It is only for certain sorts of models that combined studies

make sense however

Martin White

Outline of the rest of the talk• I will present promising avenues for GAMBIT EDM projects•What does GAMBIT currently say about those models?•How do collider constraints work in GAMBIT?•What work needs to be done to do interesting EDM+X studies

with GAMBIT?

Martin White

Disclaimer•Much of this material is new to me, and I've only had time to

do a quick dump based on the literature• This is a “let's think about X talk”, not a “we have already

thought about X” talk!

Martin White

EDMs and BSM physics models•CPT theorem says that the SM is invariant under the

combined C, P and T transformation•CP is violated in flavour-changing weak interactions, given by

complex phases in the CKM matrix (constrained by studies of K and B meson properties)•With symmetric initial conditions, the observed matter-

antimatter asymmetry requires extra sources of CP violation• EDM searches provide powerful probes of these extra sources

Martin White

arXiv:1303.2371

One approach to BSM EDMs•Write a general effective field theory (EFT) that extends the

SM with extra CP-violating dimension-six operators

• This is matched onto low-energy hadronic and atomic parameters relating to the EDMs• The EFT provides a bridge between atomic, nuclear and

hadronic matrix elements, and the fundamental CP-violating terms; any given BSM scenario will map to the EFT.

Martin White

arXiv:1407.1064

EDMs and supersymmetry (SUSY)• SUSY: A hypothesised

symmetry that connects fermions and bosons• Lack of knowledge of

SUSY breaking → 105 a priori unconstrained parameters in the simplest theory

Lots of room for extra CP violation!

Option (3): Supersymmetry

EDMs and SUSY• In the MSSM, low fine-tuning plus Higgs mass of 125 GeV →

significant stop mixing• This tends to enhance possible EDMs• “Natural SUSY” models assume that only the stops and/or

electroweakinos are within reach of the LHC• These are a nice scenario to analyse, otherwise things get

very complicated indeed

Martin White

arXiv:1612.08090

Typical diagrams for fermion EDMs

Martin White

arXiv:1612.08090

EDM measurements → constraints on stop sector!

Martin White

arXiv:1612.08090

Also get constraints on EWino sector

Martin White

arXiv:1612.08090

GAMBIT SUSY results

Example GAMBIT results (MSSM7)

● Global fit of MSSM7 with lots of data (LHC+LEP Higgs, LHC+LEP sparticle searches, Planck relic density, Fermi-LAT Pass 8, IceCube 79 string data, direct DM searches (LUX, Panda-X, PICO, Xenon100, SuperCDMS, Simple), g-2, 59 results from Belle, BaBar and LHCb, strong coupling, top mass, nuclear matrix elements, local DM density

arXiv:1705.07917

Martin White + GAMBIT collaboration + Rose Kudzman-Blais + Matthias Danniger

arXiv: 1809.02097

Included constraints

Source: Anders Kvellestad

ColliderBit

•Handles LHC and LEP limits• LEP: complete recast of sparticle xsec limits• SUSY & Exotic LHC search limits from real-time MC simulation• LHC Higgs-like resonance search limits from

HiggsBounds+HiggsSignals• Future: new resonance limits

Model independent LHC limits

•Custom parallelised Pythia MC + custom detector sim•Can generate 20,000 events on 12 cores in < 5 s• Then apply Poisson likelihood with nuisance parameters for

systematics•Combine analyses using best expected exclusion• The best you can do without extra public info from the

experiments. CMS are getting better at this: https://cds.cern.ch/record/2242860/files/NOTE2017_001.pdf

LHC EWino results

● In a test of exclusion power, we find no general constraint on the MSSM EW sector from the LHC!

arXiv:1809.02097

Scalar leptoquark models• Leptoquarks are hypothetical particles that can transform

leptons into quarks (and vice versa)• Leptoquark models come with new CP-violating couplings•Recent work has derived the connection between scalar

leptoquark models and the dimension-6 EFT described earlier (I think!)• Leptoquark theories can simultaneously provide EDMs and

explain flavour anomalies!Martin White

arXiv:1809.09114

GAMBIT leptoquark plans• Progress been made on a GAMBIT leptoquark study•We would need to extend ColliderBit to include leptoquark

limits from ATLAS and CMS (probably via digitised exclusion curves)

Martin White

Existing GAMBIT EDM study• J. Cornell, D. Skodras, E.

Stamou, J. Brod are looking into global fits of CP-violating Yukawa couplings with EDM constraints•Constraint shown results

from only varying the u coupling

Martin White

Summary• Suggestion 1: We should implement literature results on EDMs

in EWino-only scenarios and update our current results• Suggestion 2: Add stop sector and do a new study with EDM

plus other constraints• Suggestion 3: we should implement EDM constraints on

leptoquarks for the leptoquark study• Suggestion 4: if we do this via the dim6 SM-EFT, perhaps we

should do a dim6 SM-EFT fit for a bonus paper?Martin White

Summary

Martin White