Open Questions for the New Physics Working Group! (Theory)

Transcription

1 Open Questions for the New Physics Working Group! (Theory) Les Houches Thursday 15th June, 2017 Matthew McCullough

2 Topics of Focus I am a model builder: Throughout I will illustrate the topics by considering specific models.

3 Topics of Focus Beyond MET: Do we have full coverage of signatures not involving missing energy?

4 Generic Expectations HP solutions typically involve a Top Partner : h tt + h h TP h If top partner is near the weak scale, Higgs mass corrections logarithmically sensitive to new physics scales, hence naturally light Higgs. For naturalness expect m2 TP log m TP. 400 GeV.

5 Supersymmetry Supersymmetry extends SM fields to superfields, thus requiring a top partner: Top Partner Stop Squark With interactions such as And t = t + p 2 t + 2 F t L t ht L t R + h.c. + L t c t 0 Top Quark 2 t 2 h2 t L 2 + t R 2 which enables decays.

6 Supersymmetry MET searches in third generation go right for the jugular of SUSY naturalness: ~ ~ pp tt, t t χ 0 1 ICHEP CMS Preliminary 13 TeV 800 miss -1 Expected SUS , 0-lep (H T ), 12.9 fb -1 Observed 700 SUS , 0-lep (M T2 ), 12.9 fb -1 SUS , 0-lep (α T ), 12.9 fb -1 SUS , 0-lep stop, 12.9 fb SUS , 0-lep (top tag), 12.9 fb -1 SUS , 1-lep stop, 12.9 fb Combination 0-lep and 1-lep stop, 12.9 fb [GeV] [GeV] 1 χ 0 m t m~ = m t + m 0 χ 1 m~ t Already considerable pressure on SUSY naturalness

7 Supersymmetry Are these plots misleading us? Is SUSY hiding in signatures Beyond MET? Well-developed field: RPV, Stealth, etc etc. Are we certain no stone is unturned? BSM searches in third generation go right for the jugular of SUSY naturalness: ~ ~ pp tt, t t χ 0 1 ICHEP CMS Preliminary 13 TeV 800 miss -1 Expected SUS , 0-lep (H T ), 12.9 fb -1 Observed 700 SUS , 0-lep (M T2 ), 12.9 fb -1 SUS , 0-lep (α T ), 12.9 fb -1 SUS , 0-lep stop, 12.9 fb SUS , 0-lep (top tag), 12.9 fb -1 SUS , 1-lep stop, 12.9 fb Combination 0-lep and 1-lep stop, 12.9 fb [GeV] [GeV] 1 χ 0 m t m~ = m t + m 0 χ 1 m~ t Already considerable pressure on SUSY naturalness

8 Topics of Focus Multiple Unknowns: Most searches for one new particle (or pair). Do we have coverage for multiple new particles?

9 Topics of Focus Multiple Unknowns: Most searches for one new particle (or pair). Do we have coverage for multiple new particles? Apology: Will illustrate with current work, but I think it gets the point across

10 A Clockwork Scalar Action given by L = 1 NX (@ µ j ) 2 m 2 f j=0 Spontaneous symmetry breaking pattern: U(1) N+1!; So expect Goldstones. N +1 NX 1 j=0 e i f (q j+1 j ) + h.c. Explicit symmetry breaking: U(1) N+1! U(1) So expect N pseudo-goldstones and one true Goldstone. Can identify true Goldstone direction from remaining shift symmetry j! j + apple/q j Interaction basis π Choi & Im, Kaplan & Rattazzi

11 A Clockwork Scalar Peculiar spectrum, reminiscent of Condensed Matter... 0 M 2 = m 2 Mass matrix 1 q 0 0 q 1+q 2 q 0 0 q 1+q q 2 q q q 2 Discrete Clockwork How might this be useful in practice? 1. C A Eigenvalues for Clockwork Gears m 2 a k = q 2 k +1 2q cos m 2 N +1 k =1,..,N Mass spectrum Band Gap Choi & Im, Kaplan & Rattazzi m 2m m 1 (q 1)m Very weakly coupled state.

12 A Clockwork Axion Imagine clockworking Peccei-Quinn at weak scale: h j i = p f 2 m H N An invisible axion and band of weak-scale gears : m aj m aj m H, L a j f e GG 2 QCD q N f, L a j q N f e GG See also Farina et al Clockwork gears could show up as a band of states at colliders. Cosmology / thermal history of invisible axion radically altered: stays in thermal equilibrium to late times.

13 A Clockwork Axion The phenomenology of the clockwork gears would be very exotic: pp jj, BR jj =1 Preliminary!! 13 TeV, 3 ab -1 Signal+BG Signal BG [ ] Preliminary!! [ ] Dijet spectrum likely too smeared, and background too large, to reveal anything here. Perhaps diphotons could reveal gears. pp,br = TeV, 3 ab -1 Signal+BG Signal BG

14 Linear Dilaton Model This theory shows up as the continuum limit of the clockwork models. Solves hierarchy problem as in extra dimensions. In this theory But the mass Planck scale is: r M 3 m M P 5 n k k ek R So if all other parameters at the weak scale, require: kr 11 This splitting is a key prediction of the theory. spectrum is given by: 1+ n2 2(kR) 2 Thus the first few states will always be split by % s, with the relative splitting decreasing for heavier modes.

15 Irreducible prediction of clockwork gravity: Mass splitting: In this theory Planck scale is: r M 3 M P 5 So if all other [%] k ek R parameters at the weak scale, require: Linear Dilaton Model kr 11 But the mass spectrum is given by: m n k 1+ n2 2(kR) 2 Thus the first few states will always be split by % s, with the relative splitting decreasing for heavier modes. This splitting is thus a key prediction of the theory.

16 Linear Dilaton Model At colliders would look something like: pp, M 5 =5 TeV, k=500 GeV TeV. Schematic illustration! 13 TeV, 300 fb -1 BG Signal Signal+BG [ ] Most interestingly, due to splittings, signal appears to oscillate. Thus get extra sensitivity by doing spectral analysis The power spectrum of LHC data! Can search for continuum spectrum at high energies. BG modelling essential

17 Phenomenology The Fourier transform would then exhibit a peak:

18 Phenomenology What is the power spectrum of the LHC? LHC Diphoton Power Diphoton period

19 Phenomenology Multiple unknonwns: Clearly there are signatures worth pursuing involving multiple unknowns. This is only one example. What else are we not looking for? What is the power spectrum of the LHC? LHC Diphoton Power Diphoton period

20 Topics of Focus The lifetime frontier: How ubiquitous are Long- Lived Particles (LLPs)? Do we have/need the appropriate language to generalise search program?

21 LLPs in Naturalness Could there be a hidden Top Partner? Much attention now to alternative ideas: h tt +? h h h Folded SUSY Theory where EW-charged uncoloured scalars are top partners h h but they must be charged under new hidden QCD. hep-ph/ hep-ph/ Twin Higgs Theory where top partners are SM gauge neutral fermions t T Twin Tops but they must be charged under new hidden QCD. t F Folded Stops h h

22 LLPs in Naturalness Naturalness not hidden, just look in new places Twin Gluons New hidden sector introduces exotic Higgs decays: h t T Displaced Decays Twin Hadrons b b One striking signature these models motivate is displaced vertices, which may also be quite soft.

23 Exotic Higgs Exotic Higgs decays provide a signature standard candle h m =10, 25,40.GeV Assumes BG Assumes no BG As expected, reach scaling well with luminosity!

24 Neutrino Masses Certain classes of neutrino mass models have RHD neutrinos at weak scale. Signatures are relatively clean: same-sign leptons+jets. More generally, new neutral, weakly coupled, fields may show up in the lepton sector. Signatures rare, with low SM backgrounds. 300 fb -1 estimate

25 Displaced Dark Matter There are generic classes of unexplored scenarios. An example:l Int O SM (b) (a) 1 h h 1 bb 2 Numerous unexplored theories that take full advantage of the added integrated luminosity. 2 bb Exciting signatures: Paired displaced events! Soft displaced events. Missing energy Non-pointing displaced Clear detector goals: Triggering Tracking???

26 LLPs Long-lived particles come up in many models. Many exciting and creative ideas on the theoretical front Baryogenesis Neutrino Masses RPV Hidden Valleys Mini-Split Neutral Naturalness RHD Neutrinos LLPs LLPs are seemingly ubiquitous. They show up in: a) The Standard Model (Precedent) b) Pretty much any BSM scenario in some corner of parameter space. Are there other BSM scenarios where we may be overlooking signatures? Composite Higgs?

27 LLPs Long-lived particles come up in many models. Many exciting and creative ideas on the theoretical front Baryogenesis Neutrino Masses RPV Hidden Valleys Mini-Split Neutral Naturalness RHD Neutrinos LLPs Since they are ubiquitous, do we have an experimental program taking advantage of all the discovery opportunities? Do we need to generalise now to simplified models? Example for neutral LLPs: What about other scenarios?

28 Many exciting and creative ideas on the theoretical front LLPs There is already a concerted effort in this direction: LHC LLP Community. Recent workshop: What can we at Les Houches add to this effort? Tomorrow: Identify areas of opportunity and goals. Long-lived particles come up in many models. Baryogenesis Neutrino Masses RPV Hidden Valleys Mini-Split Neutral Naturalness RHD Neutrinos LLPs Since they are ubiquitous, do we have an experimental program taking advantage of all the discovery opportunities? Do we need to generalise now to simplified models? Example for neutral LLPs: What about other scenarios?

29 Topics of Focus Beyond ATLAS and CMS: What more can be done with LHCb?

30 Beyond ATLAS and CMS Last year demonstrated LHCb is a superb intensity-frontier machine. In this case dark photon searches. What else can we use it for?

31 Topics of Focus Colliders and multi-component dark matter: Are we taking relic abundance too seriously? Are we properly searching for sub-components? Are there collider signatures that are only possible with multi-component?

32 Dark Matters But there are some ideas Stolen from slides of Tim Tait.

33 Dark Matters But there are some ideas Do LH C sea rches prope theo r ry spa ly cover d ark ce? Stolen from slides of Tim Tait.

34 Topics of Focus New ideas? New features from old ideas?

35 Neutral Naturalness Personal perspective: These ideas are a decade old. Work since has been very valuable, but structurally not much has changed. Are there possibilities we haven t found yet? Are there signatures we are overlooking? Folded SUSY Theory where EW-charged uncoloured scalars are top partners h h but they must be charged under new hidden QCD. hep-ph/ hep-ph/ Twin Higgs Theory where top partners are SM gauge neutral fermions t T Twin Tops but they must be charged under new hidden QCD. t F Folded Stops h h

36 Topics of Focus Flavour? B-meson anomalies What else is left to study?

37 Summary A collider search is a question: Does there exist What questions are we not asking, and why not?