Οι Υπερχορδές και η «δομική μουσική» του Σύμπαντος. Διονύσης Βαβουγυιός Πανεπιστήμιο Θεσσαλίας

Θεωρίες Χορδών ΤύποςΧωροχρονικ ές Διαστάσεις Λεπτομέρειες Μποζονική26 Μόνον μποζόνια, μόνον δυνάμεις, όχι φερμιόνια, όχι ύλη, με ανοικτές και κλειστές χορδές. Μέγιστο ελάττωμα : Σωματίδιο φανταστικής μάζας που λέγεται ταχυόνιο Ι10 Υπερσυμμετρία μεταξύ δυνάμεων και ύλης, με ανοικτές και κλειστές χορδές, όχι ταχυόνια. Συμμετρία Ομάδας : SO(32) ΙΙΑ10 Υπερσυμμετρία μεταξύ δυνάμεων και ύλης, με κλειστές χορδές μόνον, όχι ταχυόνια, φερμιόνια χωρίς μάζα (nonchiral). ΙΙΒ10 Υπερσυμμετρία μεταξύ δυνάμεων και ύλης, με κλειστές χορδές μόνον, όχι ταχυόνια, φερμιόνια χωρίς μάζα (chiral). ΗΟ10 Υπερσυμμετρία μεταξύ δυνάμεων και ύλης, με κλειστές χορδές μόνον, όχι ταχυόνια, ετεροτική (χορδές κινούμενες αριστερά και δεξιά διαφέρουν) Συμμετρία Ομάδας : SO(32) ΗΕ10 Υπερσυμμετρία μεταξύ δυνάμεων και ύλης, με κλειστές χορδές μόνον, όχι ταχυόνια, ετεροτική (χορδές κινούμενες αριστερά και δεξιά διαφέρουν) Συμμετρία Ομάδας : Ε 8 xE 8

A Timeline of Particle Discoveries 1895The electron is discovered, except electrons are called cathode rays by their discoverer. 1896X rays and other forms of radioactivity are observed 1899Alpha particles are discovered, and later shown to be helium nuclei consisting of two neutrons and two protons. 1911Nuclear model of atom with heavy nucleus in the middle and light electrons orbiting around it, is proposed, and becomes accepted. 1911Electron charge measured in an oil drop experiment indicates that all electrons carry the same electric charge. 1932The neutron directly observed in an experiment for first time. 1932The positron, predicted by a theorist in 1928, is discovered. 1934Radioactive nuclei produced in the laboratory.

1937The muon, a charged lepton like the electron only heavier and hence unstable, is discovered. 1947Two charged pi mesons, with positive and negative charge, are discovered. 1950The neutral pi meson is discovered. 1953The lambda baryon and K meson are discovered. 1956The electron neutrino, predicted by theory in 1930, is confirmed to exist. 1950s- 1960s Lots of baryons and mesons being discovered, and their properties occur in regular patterns that look as if baryons and mesons are made of smaller building blocks. Physicists exhibit a tendency to name new particles after letters in the Greek alphabet. 1961The muon neutrino is discovered and shown to be a different particle from the electron neutrino Quark theory postulates that protons are made of smaller particles that carry charges that come in thirds of the electron charge. The three flavours of quarks are given names: up, down and strange.

1970sDeep inelastic scattering and other experiments reveal more of the quark structure inside protons and other hadrons. 1974A fourth flavour of quark, named charm, is detected in a newly discovered meson called the J / . 1975The tau lepton is discovered, making a triplet of charged leptons with the electron and muon, leading to predictions of a tau neutrino to accompany the electron neutrino and the muon neutrino. 1979A fifth flavour of quark, named bottom, is detected in the newly discovered Upsilon meson. This pattern leads particle physicists to believe they will find a sixth and final flavour of quark some day. This predicted last flavour of quark is called top. 1983The massive gauge bosons that carry the weak nuclear force, called the W +, W - and Z 0, are discovered and the Standard Model of Particle Physics is confirmed.

1989The lifetime of the Z 0 weak nuclear gauge boson is measured, and agrees precisely with there being exactly three kinds of neutrinos, and no more. 1995The top quark is finally directly observed and measured, confirming the predictions of theorists that there are six flavours of quarks, as described in the Standard Model. FutureThe search goes on for the Higgs boson (the only particle predicted by the Standard Model that hasn't been seen yet), for supersymmetric particles predicted by string theory, for proton decay and for magnetic monopoles predicted by Grand Unified Theories, and new kinds of exotic unpredicted particles is ongoing. Perhaps in a few years there will be some more interesting entries for this page.

NameSpin Electric charge MassObserved? Graviton200Not yet Photon100Yes Gluon100Indirectly W+W GeVYes W-W- 180 GeVYes Z0Z GeVYes Higgs00> 78 GeVNot yet

NameSpin Electric charge MassObserved? Electron1/ GeVYes Muon1/2.10 GevYes Tau1/21.8 GevYes NameSpin Electric charge MassObserved? Electron neutrino1/200?Yes Muon neutrino1/20< GeVYes Tau neutrino1/20<.017 GeVYes

NameSpin Electric charge MassObserved? Up quark1/22/3.005 GeVIndirectly Charm quark1/22/31.4 GeVIndirectly Top quark1/22/3174 GeVIndirectly NameSpin Electric charge MassObserved? Down quark1/2-1/3.009 GeVIndirectly Strange quark1/2-1/3.17 GeVIndirectly Bottom quark1/2-1/34.4 GeVIndirectly

ForceSymbol Streng th Range Strong nuclear force ss 1/ m Weak nuclear force WW 1/ m Electromagnetic force  EM 7x10 -3 Infinity

Gauge bosonMass W+W+ 80 GeV W-W- Z0Z0 91 GeV

NameSpinSuperpartnerSpin Graviton2Gravitino3/2 Photon1Photino1/2 Gluon1Gluino1/2 W +,- 1Wino +,- 1/2 Z0Z0 1Zino1/2 Higgs0Higgsino1/2 NameSpinSuperpartnerSpin Electron1/2Selectron0 Muon1/2Smuon0 Tau1/2Stau0 Neutrino1/2Sneutrino0 Quark1/2Squark0

ScaleDefinition Planck scale Length scales of quantum fluctuations of spacetime geometry are important, about cm, or GeV. String scale Average size of string, once assumed to be Planck scale but now more complicated. Compactification scale Size of compact extra dimensions, also determines mass of massive oscillations in extra dimensions. Supersymmetry breaking scale Mass scale where supersymmetry is broken, could be anywhere between the Planck scale and the electroweak scale, depending on the model in question Grand Unification symmetry breaking scale Mass scale where unified gauge symmetry is broken and remaining symmetries split into three gauge groups of Standard Model, should be about GeV Electroweak scale Mass scale below which current particle physics experiments have agreed extremely well with predictions made by Standard Model of particle physics, this is about 100 GeV to 1TeV.

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