What Are Fundamental Constants? Cosmic Accidents? Determined by Dynamics? Changing in Time? Given by...
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Transcript of What Are Fundamental Constants? Cosmic Accidents? Determined by Dynamics? Changing in Time? Given by...
What Are What Are Fundamental Fundamental Constants?Constants?
Cosmic Accidents?Cosmic Accidents?Determined by Dynamics?Determined by Dynamics?
Changing in Time?Changing in Time?Given by Self-Consistency?Given by Self-Consistency?
Calculable?Calculable?
Sommerfeld, 1916………Sommerfeld, 1916………
Pauli (1958): Nr 137, Pauli (1958): Nr 137, Zürich.............Zürich.............
L. Lederman, 137 Eola RoadL. Lederman, 137 Eola Road
Feynman: 137–how little we Feynman: 137–how little we
knowknow
137/1
/22
hce
QED: Most successful theory QED: Most successful theory in science. Merging of in science. Merging of electrody-namics, quantum electrody-namics, quantum mechanics and special mechanics and special relativity.relativity.Renormalizable theory, Renormalizable theory, tested up to 1:10 000 000tested up to 1:10 000 000(Lamb shift, hyperfine splitting, (Lamb shift, hyperfine splitting, magnetic moments)magnetic moments)
Not expected by the creators of Not expected by the creators of the theory: Dirac, Heisenberg, the theory: Dirac, Heisenberg, Pauli, …Pauli, …
Quantum Field Theory:Quantum Field Theory:
Finestructure constant becomes Finestructure constant becomes function of energy or scale due to function of energy or scale due to quantum fluctuations of electron-quantum fluctuations of electron-positron pairspositron pairs
=> partial screening of bare charge of => partial screening of bare charge of the electron at distances less than the electron at distances less than the compton wavelength of the the compton wavelength of the electronelectron
Renormalization GroupRenormalization GroupContribution of electron-Contribution of electron-
positron pairspositron pairs
3
2
( , ) ( )ln( / )
( ) ...12
r
de q e e
d q M
QED
ee
About 1.8 billion years ago, in Gabon, About 1.8 billion years ago, in Gabon,
Westafrika. Westafrika. Natural Reactor, which operated about Natural Reactor, which operated about
100 million years.100 million years. High concentration of uraniumHigh concentration of uranium 3.7% U 235 at that time (today 0.72 %)3.7% U 235 at that time (today 0.72 %) Moderator: water from river OkloModerator: water from river Oklo (off – on reactor, period about 30 min)(off – on reactor, period about 30 min)
Discovered in the 1970ties by frenchDiscovered in the 1970ties by french
nuclear physicistsnuclear physicists
It was found: It was found:
Uranium 235 had 0.717 %-Uranium 235 had 0.717 %-
Normally: 0.720 % Normally: 0.720 %
=> further investigation=> further investigation
Shlyakhter, Dyson and Damour (1996)Shlyakhter, Dyson and Damour (1996)Neutron CaptureNeutron Capture
Sm(149) + n =>Sm(150) + gammaSm(149) + n =>Sm(150) + gammaCalculation: cross section about 57 … 93 kbCalculation: cross section about 57 … 93 kb
very large cross section due to very large cross section due to nuclear resonance just above thresholdnuclear resonance just above threshold
E=0.0973 eVE=0.0973 eV
Resonance position cannot have changed muchResonance position cannot have changed much Change less than 0.1 eV =>Change less than 0.1 eV =>
alpha(Oklo)-alpha(now)/alphaalpha(Oklo)-alpha(now)/alpha
<1/10 000 000<1/10 000 000
Change of alpha per yearChange of alpha per year
must be less thanmust be less than
1/10 000 000 000 000 000 1/10 000 000 000 000 000
per yearper year
(if no other parameters (if no other parameters change)change)
=>constraint questionable=>constraint questionable
Thus far only one mechanism of mass Thus far only one mechanism of mass
generation established: generation established:
QCDQCDMass from „no-mass“Mass from „no-mass“
(dimensional transmutation)(dimensional transmutation)
„„Anti-screening“ of color – Anti-screening“ of color –
infrared slaveryinfrared slavery
Nucleon Mass in limit of Nucleon Mass in limit of vanishing quark masses:vanishing quark masses:
const. calculable, but large errors at const. calculable, but large errors at present.present.
Exp: 938.272 MeVExp: 938.272 MeV
cconstM .
Nucleon Mass in QCD:Nucleon Mass in QCD:
Nuleon mass: QCD mass and massNuleon mass: QCD mass and mass
contributions from the quark massescontributions from the quark masses
Example: QCD u d s+c Example: QCD u d s+c QED)QED)
n u u d d s s elmM c c m c m c m c
938.272 (861.532 20.138 19.253 35.362 1.987)pM MeV MeV
The Dark Corner of HEPThe Dark Corner of HEPFermion Masses: ArbitraryFermion Masses: Arbitrary
L
R
lbGeVMeVme301000.22460000021.0511.0
Quark Masses:Quark Masses:
Observed:Observed:
m(c) : m(t) = m(u):m(c) m(c) : m(t) = m(u):m(c) 1/185 1/1901/185 1/190
m(s):m(b) = m(d):m(s)m(s):m(b) = m(d):m(s) 1/24 1/231/24 1/23
Relations among constants?Relations among constants?
e.g. flavor mixinge.g. flavor mixing( slight reduction of nr. of parameters)( slight reduction of nr. of parameters)
/u u cm m
/d d sm m
Time Variation of fundamental Time Variation of fundamental constants:constants:
Dirac (~1930)Dirac (~1930)
1010
Fine structure of Fe, Ni, Mg, Sn, AFine structure of Fe, Ni, Mg, Sn, A
Quasars, back to 11 bn years in timeQuasars, back to 11 bn years in time
(challenged by Reimers, Chile, (challenged by Reimers, Chile, investigating only one quasar)investigating only one quasar)
5
15
/ ( 0.54 0.12)10
_ .: / : 1.2 10 _ _Linear App d dt per year
SU(3)xSU(2)xU(1) < SU(5)SU(3)xSU(2)xU(1) < SU(5)
(G, G: 1974)(G, G: 1974)
SU(3)xSU(2)xU(1) < SU(3)xSU(2)xU(1) < SO(10)SO(10)
(F-M, G : 1975)(F-M, G : 1975)
Electroweak theory:Electroweak theory:
SU(2) x SU(2) x U(1)SU(2) x SU(2) x U(1)
U(1): (B-L)U(1): (B-L)
Coupling Constants in SU(5) with Coupling Constants in SU(5) with SupersymmetrySupersymmetry
(similar in SO(10) – Theory)(similar in SO(10) – Theory)
If the scale of unification does If the scale of unification does not change, one finds:not change, one finds:
2 28 1/ : : ( .) _ / :
3 2s s Gut Gutd dt d const d dt
2 28/ : / :
3 s sd dt d dt
Calmet, F. - Langacker, Segre (2002)
Magnetic moments of atomic Magnetic moments of atomic nuclei would change nuclei would change accordingly, per yearaccordingly, per year
/ : 38,8 _ / :d dt d dt
143,9 10
If only the scale of unification If only the scale of unification changes, the sign changes:changes, the sign changes:
/ : 31_ / :d dt d dt
Time: measured by Cesium Time: measured by Cesium clocksclocks
Hyperfine transition, Hyperfine transition, involving the magnetic involving the magnetic moment of the cesium moment of the cesium nucleus.nucleus.
Would be affected by time Would be affected by time change of QCD scalechange of QCD scale
Comparison
Cs-
clockHydrogen
clock
Difference: 3 CS oscillations per day
Experiment at MPQ Munichand NIST Boulder
MPQ-ExperimentMPQ-Experiment
486 nm dye laser in hydrogen486 nm dye laser in hydrogenspectrometerspectrometer
Reference: cesium clock Pharao LPTFReference: cesium clock Pharao LPTFParisParis
Hydrogen: 1s-2s transitionHydrogen: 1s-2s transition2 466 061 413 187 127 (18) Hz2 466 061 413 187 127 (18) Hz
Expected in simple model:Expected in simple model:about 10 times moreabout 10 times more
Measurement:Measurement:15 1/ : (2.4 6.8) 10d dt yr
14/ : 2 10d dt
Simultaneous change of unif. coupling Simultaneous change of unif. coupling andand
unif. scaleunif. scalePartial Cancellation of effect? Partial Cancellation of effect?
(expected in superstring models)(expected in superstring models)
Indication for effect in the new exp. at Indication for effect in the new exp. at MPQ:MPQ: 15/ : (3 1) 10 /d dt year
2 28 1/ : / : ( .) _ / :
3 2s s Gut Gutd dt d dt const d dt
Very recently: Very recently: Reinhold et al. PRL 96 (2006)Reinhold et al. PRL 96 (2006)2 quasars, 12 bn. years away2 quasars, 12 bn. years away
Looking for time variation of ratio Looking for time variation of ratio proton mass / electron massproton mass / electron mass
One finds:One finds:
5/ (2 0.6) 10
SummarySummary
28 constants of nature, 24 of them mass 28 constants of nature, 24 of them mass parametersparameters
Grand unification relates elm., strong and weakGrand unification relates elm., strong and weakinteractions.interactions.
Time variation of alpha leads to time variation of theTime variation of alpha leads to time variation of theQCD scale and of the weak interactionsQCD scale and of the weak interactions
MPQ Experiment rules out simplest model, but effectMPQ Experiment rules out simplest model, but effectseems to be there, about a factor 10 less than naivelyseems to be there, about a factor 10 less than naivelyexpected, consistent mit observed variation of expected, consistent mit observed variation of electron-proton-massratio.electron-proton-massratio.
Necessary:Necessary:
Both unification scale Both unification scale
andand
unified couplingunified coupling
must change in time.must change in time.
(expected in superstring models)(expected in superstring models)