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A Quiz: You make science policy

Paul Grannis

Escolo Swieca, Campos do Jordao

Jan. 19 – 23, 2009

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Quiz

In a few years, you will be the leaders of particle physics with the best understanding of the physics coming from LHC, of new theoretical ideas, and the latest tools of the trade.

Lets postulate some scenarios of how things might look in 5-10 years time and ask ourselves how we would advise the leaders of world governments on where best to put limited resources for further study of particle physics.

Postulate that the LHC has run successfully and acquired about 100 fb of data (and its upgrade to sLHC at higher luminosities, still at 14 TeV, is starting).

Our job is to analyze what we then know, what further is needed for further progress, and to give the expert advice needed to our governments.

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Quiz

We start by only considering what we learn at the energy frontier at LHC. We suppose that any new facility will be expensive enough that it will be fully international and that only one new machine (if that) can be afforded. The candidates are:

ILC 500 → 1000 GeV, with phase 1 operation starting around 2022

CLIC 1 – 3 TeV, starting around 2030 … or

Muon collider 1 – 4 TeV, starting no sooner than 2035

VLHC (pp) at ~100 TeV, starting around 2040

(Don’t take these dates as more than examples – completing the R&D, reliable cost estimates, international agreements on siting, organization, cost sharing are impossible to predict.)

There are linkages. If for example, oscillations show is large enough, and there are hints of CP violation in the sector, then a Factory may be attractive. And a Factory is the precursor to a Muon Collider.

And there are competitors: What if LHC-b and super-B factory measurements show unambigous evidence for new physics in the b sector? What if Dark Energy measurements begin to point toward a new scalar field that can be effectively studied with new astrophysical facilities? etc.

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Scenario 1

The Tevatron/LHC discover a low mass Higgs at ≈120 GeV, and the LHC sees clear evidence for new particles at masses below 1 TeV, consistent with being squarks or gluinos. Moreover, the decays of these particles contain substantial numbers of leptons, indicating that, if it is Susy, either gauginos or sleptons exist at relatively low mass.

How nice!

What is our best next step? What are the questions we should aim to answer? Which accelerator facility will get us furthest?

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Scenario 2

The LHC observes a Higgs-like candidate at 120 GeV (or ≈200 GeV), but sees no evidence for new physics that looks like low mass Susy, and no direct evidence for extra dimensions with particle content below 5 TeV. WW scattering is at the level of the ‘low energy theorem’ implying no new strong coupling states at < 2 TeV.

but measurements at reactors, accelerators give significant sin2(2 ≈ 0.05.

AND/OR

b-physics measurements indicate significant non-SM effects

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Scenario 3

The LHC sees no Higgs candidate up to 1 TeV, and there is no evidence for Supersymmetry, new strongly coupled resonances or excited Z/W bosons. (It seems that everything we said about new physics at the TeV scale was wrong!)

Is there hope for particle physics? Is there a natural next energy frontier facility? Are there things we should do in other areas? Do we all become astroparticle physicists?

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Scenario 4

That last one was too depressing! How about this:

LHC sees a Higgs, finds evidence for some sort of Susy that looks like squark/gluino cascades through leptons to missing energy AND there is a new Z’ like state at 2 TeV (that might be evidence for extra dimensions or little Higgs or L-R models or …).

Not only that, but the neutrino program sees 13 just below the current limits, and loop effects are showing up in b-physics.

Now what?? (remember, only one new facility is affordable)

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Energy Frontier Lectures Summary

We believe that the SM is fundamentally incomplete & flawed, and that big new physics is lurking. Though we don’t yet understand the character of the new physics, but we do have good evidence that it should start to emerge at the TeV scale.

There are many theoretical suggestions for solving these questions: TeV scale supersymmetry Large extra dimensions Technicolor, strong coupling Little Higgs … and so on …

And we have the tools for exploring the new uncharted seas

There will be lots of fun to come in the next 10 years!

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This is an experimentalist’s dream! We have glimpsed a new and mysterious body of water, but have no idea about its dimensions, its islands and bays, its depths or its currents. GO THERE AND EXPLORE !

Energy Frontier Lectures Summary

???

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Thank you !

Paul Grannis

Escolo Swieca, Campos do Jordao

Jan. 19 – 23, 2009

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Some References I list here some references that I have found useful in preparing these lectures. They are by no means complete; primary references can be found in the listed reviews.General summaries of the physics, and experimental capabilities at

the energy frontier:

G1. ATLAS Technical Design Report, http://atlas.web.cern.ch/Atlas/TP/tp_ps.html (Detector) and http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/TDR/ access.html (Physics)

G2. CMS Technical Design Report, CERN-LHCC-2006-001 (Detector) and CERN-LHCC-2006-021 (Physics).

G3. ILC Reference Design Report (Vol 1 - Executive Summary; Vol 2 - Physics; Vol 3- Accelerator; Vol 4 - Detectors), http://www.linearcollider.org/cms/

G4. B.C. Allanach et al., Les Houches “Physics at TeV Colliders 2005; Beyond the Standard Model” , arXiv:hep-ph/0602198.

G5. G. Weiglein et al., ”Physics Interplay of the LHC and ILC”, arXiv:hep-ph/0410364.

G6. S. Dawson & M. Oreglia “Physics Opportunities with a TeV Linear Collider’, Ann. Rev. Nucl. Part. Sci., 54, 269 (2004).

G7. M. Peskin et al., Linear Collider Physics Resource Group for Snowmass 2001, http://www.slac.stanford.edu/grp/th/LCBook/

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References

Higgs:

H1. J. Gunion, H. Haber, G. Kane, S. Dawson, “The Higgs Hunter’s Guide”, Addison-Wesley, Reading (USA) (1990).

H2. M. Carena, J. Conway, H. Haber, J. Hobbs, “Report of the Tevatron Higgs Working Group”, arXiv:hep-ph/00100388.

H3. A. Djouadi, “The Anatomy of Electro-Weak Symmetry Breaking. II: The Higgs bosons in the Minimal Supersymmetric Model” , arXiv:hep-ph/0503173.

See also General Reference chapters on Higgs boson physics.

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References

Supersymmetry:

S1. H. Murayama, “Supersymmetry Phenomenology”, arXiv:\hep-ph/0002232.

S2. Nima Arkani-Hamed et al. “Supersymmetry and the LHC inverse problem”, arXiv hep-ph/0512190.

S3. C.F. Berger et al., “General Features of Supersymmetric Signals at the ILC: Solving the LHC Inverse Problem”, arXiv:/0712.2965 [hep-ph].

S4. C.F. Berger et al., “Supersymmetry without Prejudice”, arXiv:0812.0980.

S5. L. Pape and D. Treille, “Supersymmetry facing experiment: much ado (already) about nothing (yet)”, Rep. Prog. Phys. 69, 2843-3067 (2006).

S6. M. Schmitt, “Supersymmetry experiment”, in Particle Data Book, W.-M. Yao et al., J. Phys. G33, 1 (2006).

S7. P. Grannis, “A Run Scenario for the Linear Collider”, arXiv:hep-ex/0211002.

S8. H. U. Martyn, “Supersymmetry physics at the ILC”, arXiv:hep-ph/0302024.

See also General Reference chapters on Supersymmetry.

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References

Alternate models:

A1. J.L. Hewett, “Phenenology of Extra Dimensions”, SLAC-PUB-12188 (2005).

A2. Tao Han, “Physics with Extra Dimensions” , http://www.lns.cornell.edu/~maxim/snowmass/extrad-snow.pdf

A3. G. Azuelos, “Signals of Extra Dimensions at Atlas” , http://www.phys.ufl.edu/~kong/Notes/ued/extraD_Cambridge.pdf

A4. M. Schmaltz & D. Tucker-Smith, “Little Higgs Review”, arXiv.hep-ph/0502182.

A5. I. Hinchliffe et al., “Little Higgs Task Force” (Atlas), http://www.usatlas.bnl.gov/computing/Jackie/littleh.pdf

See also General Reference chapters on alternate models.