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Precision Measurements after the Higgs Discovery

Precision Measurements after the Higgs Discovery. M.V. Chizhov Sofia University, Bulgaria and JINR, Russia. Why do we need the Higgs boson?. S = ½. S = 1. S = 0. Harmonic Oscillator (Analytical M echanics). Joseph-Louis Lagrange ( Giuseppe Lodovico Lagrangia) , 1788.

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Precision Measurements after the Higgs Discovery

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  1. Precision Measurements after the Higgs Discovery M.V. Chizhov Sofia University, Bulgaria and JINR, Russia

  2. Why do we need the Higgs boson? S = ½ S = 1 S = 0

  3. Harmonic Oscillator (Analytical Mechanics) Joseph-Louis Lagrange (Giuseppe Lodovico Lagrangia), 1788

  4. Harmonic Oscillator (Scalar Field) R < 0 R > 0

  5. Scalar Potential of Anharmonic Oscillator

  6. Discrete Z2Symmetryof the Scalar Potential

  7. Two Scalar Fields (or Complex ScalarField) Potential with Broken Symmetry

  8. Continuous U(1) Symmetry of • the Potential with Complex Scalar Field J. Goldstone, Nuovo Cim. 19 (1961) 154.

  9. Goldstone Particle (Theorem) “if there is continuous symmetry transformation under which the Lagrangian is invariant, then either the vacuum state is also invariant under the transformation, or there must exist spinless particles of zero mass.” Jeffrey Goldstone, Abdus Salam and Steven Weinberg, Phys. Rev. 127 (1962) 965

  10. Examples of Collective Goldstone Bosons • Spin waves in a ferromagnet • Phonons in a crystal lattice • Superfluidity (Bose condensate, Боголюбов,1947) • Superconductivity (Cooper pairs, 1956; Боголюбов,1958) • Pions in the chiral limit (Nambu, 1961)

  11. Massless Particles in Nature In Nature there is not a massless spinlesscolorless particle, which would have had an infinite radius of interaction! Only gravitational and electromagnetic forces have an infinite radius of interaction.

  12. Gauge Invariance and Massless Particles Am

  13. An Anecdote by C. N. Yang • As Yang relates: • Wolfgang Pauli (1900-1958) was spending • the year in Princeton, and was deeply • interested in symmetries and interactions.... Soon after my seminar began, when I had • written on the blackboard, • (∂m-iBm) • Pauli asked, "What is the mass of this field Bm?" I said we did not know. Then I resumed my presentation but soon Pauli asked the same question again. I said something to the effect that it was a very complicated problem, we had worked on it and had come to no definite conclusions. I still remember his repartee: "That is not sufficient excuse".

  14. Birth of the Standard Model of • Elementary Particles SU(2)LU(1)Y S. L. Glashow, Nucl. Phys. 22 (1961) 579. “Schwinger told me to think about unifying weak and EM. So I did it. For two years ‒ I thought about it.”

  15. Unitarity and Z boson

  16. Unitarity and Higgs boson Not yet tested experimentally… but see the following slide!

  17. Evidence of electroweak W±W±jj production ATLAS-CONF-2014-013 (March 25, 2014),arXiv:1405.6241 Inclusive mjj QCD+EW region Enriched VBS region: mjj>500 GeV, |Dyjj|>2.4

  18. Gauge Invariance and Massive Particles Schwingermodel (1962): two-dimentionalquantum electrodynamics, where the photon becomes massive. Non-relativisticdynamics of the plasma: PhilipW.Anderson (1963) – Yang  Mills fields acquire the mass due to longitudinal oscillations in plasma (Meissner  Ochsenfeld effect). “We conclude, then, that the Goldstone zero-mass difficulty is not a serious one, because we can probably cancel it off against an equal Yang-Mills zero-mass problem.” Am 2

  19. Englert-Brout-Higgs-Guralnik-Hagen-Kibble mechanism on one page • F. Englert and R. Brout, Phys. Rev. Lett. 13 (1964) 321(June 26, 1964) • P. W. Higgs, Phys. Rev. Lett. 13 (1964) 508(August31, 1964) • G. S. Guralnik, C. R. Hagen, and T. W. B. Kibble, • Phys. Rev. Lett. 13 (1964) 585 (Octomber12, 1964)

  20. Goldstone and HiggsParticles Peter W. Higgs Phys. Rev. Lett. 13 (1964) 508 “it is worth noting that an essential feature of this type of theory is the prediction of incomplete multipletsof scalar and vector bosons.” Jeffrey Goldstone Phys. Rev. 145 (1966) 1156 H → Z Z

  21. Omitted Opportunities “All of us, Brout, Englert and myself, had been going in the wrong direction, looking at hadron symmetries.”P.W. Higgs Glashow (1961) Salam & Ward (1964) Neither Salam and Ward, who worked at Imperial College in the same group with Guralnik, Hagen and Kibble, nor Glashow, who after Higgs seminar at Harvard on March 16, 1966 said: "that is a nice model, Peter" have realized that they could use this mechanism for generation of masses. Salam & Ward (Sept 24, 1964→ Nov 15, 1964) (On Monday, October 5, Peter Higgs gave a seminar about his mechanism at Imperial College?) GHK (Oct 12, 1964 → Nov 16,1964)

  22. Using of EBHGHK mechanism • S. Weinberg (1967) & A. Salam (1968) • → Nobel Prize 1979 • relation between the masses of intermediate • bosons MW=MZ cosWthrough the mechanism • of spontaneous symmetry breaking SU(2)L U(1)Y

  23. Lagrangian of the Standard Model

  24. Mathematical Foundation of the Standard Model (theory) • G. ’t Hooft& M. J. G. Veltman(1972) • → Nobel Prize 1999 • renormalizability of non-abelian gauge theories with broken symmetry is proven a drawing of their most important discovery

  25. Establishment of the Standard Model (experiment) • Discovery of the weak neutral interactions mediated byZ bosoninexperiment with bubble chamber Gargamelleat CERN (1973) sin2W ~ 0.3-0.5 MW=50-70GeV MZ =75-80GeV

  26. Hunt for the Higgs Boson John F. Gunion, Howard E. Haber, Gordon L. Kane, Sally Dawson, The Higgs Hunter's Guide, Upton, NY: Brookhaven Nat. Lab., 1989. - 404 p.

  27. TeVatron at FNAL began work on November 30, 1986 and stopped on September 30, 2011

  28. Tevatron Higgs Exclusion

  29. LargeElectron‒Positron (LEP) colliderat CERN started in August 1989 and ended in late 2000 L3 ALEPH OPAL DELPHI

  30. Direct LEP exclusion

  31. Indirect constraints on Higgs mass

  32. Large Hadron Collider (LHC) 2  1380 bunches 1.51011p 109interactions per second

  33. July 4, 2012

  34. Is it the Higgs, or isn’t Higgs?

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