the three standard models - g2pc1.bu.edug2pc1.bu.edu/leptonmom/talks/wilczek.pdf · 03/01/2003...

The Good, the Bad, and the Ugly

The Three Standard Models

The Good: The Gauge Sector

03/01/2003 Frank Wilczek, MIT 3

03/01/2003 Frank Wilczek, MIT 4

Self-Transcendence

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03/01/2003 Frank Wilczek, MIT 7

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• Economy in quantum numbers and coupling strengths

• Stability of the electroweak scale

• Appearance of a large mass scale:

Advantages of Unification and (Low E) Supersymmetry

neutrinos,gravity, things that don’t happen!

• Small Radiative Corrections

• Light Higgs Mass

• Dark Matter Candidate

More Advantages of Susy

03/01/2003 Frank Wilczek, MIT 11

03/01/2003 Frank Wilczek, MIT 12

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The Bad: Gravity

• General relativity + minimal coupling: economical, algorithmic - and works!

• No practical problems (GPS, astrophysics)

• No “immediate” conflict with quantum theory

What’s so Bad?

• Ultraviolet catastrophe

• Singularities: black hole, big bang

• Isolation (vs. unification scale, inflation)

• The Cosmological Term

Refusals of Service

An Opening?

Non-minimal gravitational couplings play a crucial role in supersymmetry models.

The Ugly: Masses and Mixings

• Why three families?

• No deep principles in this sector; many independent parameters

• More accurately, no new deep principles - QM, QFT + renormalizability still rule

Problems

03/01/2003 Frank Wilczek, MIT 20

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• More stuff to determine: CKM matrix, neutrino mass matrix, mu-md

• Higgs particle(s) and couplings

• Axions in themselves: strong P,T; dark matter

• Axions as a clue: symmetry, dynamic “parameters”, ultralight particles

Deuglification: Insights and Opportunities

• Proton decay

• Other rare decays, b›s channels

• xyHiggs2 quartic couplings, hhfsf

• Precision dipole moments

More Opportunities

... which bring us to

The Sublime

The World as Concept, Algorithm, and Number

Hadron Mass Spectrumfrom Quarks and Gluons

Hadrons are the constituents of atomic nuclei. Thecomputation of their mass spectrum from thedynamics of more fundamental quarks and gluonshas been a principal subject of interest in particlephysics.In this figure, the results from the CP-PACS andfrom a previous computation are compared withexperiment. Experimental results are reproduced towithin about 5–10%. With the precise data from theCP-PACS, we further clarify a limitation of thewidely adopted "quenched" approximation,answering a long-standing question since 1981.

N = (u,d,d)L = (u,d,s)K = (d,s)

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

f

K

K* N

LS

X

D

S*X*

W

CP-PACS (1998)GF11 (1993)experiment

quenched QCD

mhad[GeV]