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Discovery of Higgs Boson

u. c. d. t. γ. s. ν. b. e. ν. W. μ. e. ν. τ. μ. Z. τ. g. Discovery of Higgs Boson. H. 28 July 2012 at Matsumoto University Physics Department and ICEPP, The University of Tokyo Sachio Komamiya. Until Last month, we say we are at

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Discovery of Higgs Boson

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  1. u c d t γ s ν b e ν W μ e ν τ μ Z τ g Discovery of Higgs Boson H 28 July 2012 at Matsumoto University Physics Department and ICEPP, The University of Tokyo Sachio Komamiya

  2. Until Last month, we say we are at the Dawn of the Revolution in Particle Physics ⇒ Discovery of “Higgs Boson” （The July Revolution） ⇒ This is just a start of an enormous revolutionary era

  3. TheHiggspendence Day （The 4th July 、CERN） Press release“Something like Higgs Boson is discovered” Assoc. Prof. Jun-ichi Tanaka ICEPP U. Tokyo, ATLAS Higgs Group

  4. Hierarchy in sizes of building blocks of material MoleculesAtomsNucleiNucleonsElementary Particles Proton Oxygen Atom Oxygen Nucleus u-quark Neutron ｄ-quark Ｈ２Ｏ　　　 Water molecule electron Hydrogen atom 10-10 m10-15 m <10-18 m 0.1 nm 1 fm <1 am

  5. Discovery of the first elementary particle electron 1897J.J. Thomson measured relative charge (Q/m) by the instrument below ⇒found Q/m is huge i.e. electrons are very light ⇒　　　　　　　　　　　　　　　Study of atomic structure

  6. Models of atomic structure Atomic model １　　　　　　　　　　　Atomic model ２ electrons ＋charged uniform material Heavy and hard ＋charged nucleus electron Raisin bread modelSun-planets model 　Ｊ．Ｊ．ThomsonRutherford HantaroNagaoka

  7. Discovery of nucleus by Rutherford 1911Experiment by Geiger and Marsden α-source α-ray（He nucleus） Detector　　　　　（Scintillator） Thin gold leaf Almost all the α-particles penetrate a few of them scatters in large angles ⇒　　　　　　　THIS MODEL IS VALID Prototype of particle physics experiments

  8. Elementary Particles in the Standard Model （１） Matter Fermions　（Ｊ＝1/2）　　QuarksLeptons u c tνeνμντ dsbe μτ ＋Anti-Particles　　　　　　　　　　　　　　　　　＋Anti-Particles （２） Gauge Bosons　（Ｊ＝１） Electro-Magnetic Int.γ　　　　　　　　　　（Photon） Weak Interaction W+ W- Z0　　　　（Weak Bosons） Strong Interactiong　（８ species）　　（Gluons） （３） Origin of Masses　（Ｊ＝0）H0 （Higgs Boson）

  9. V V φ₀ φ φ Vacuum Vacuum Higgs Boson and Vacuum The shape of the Higgs potential changed when the universe cooled downAnalogous to the phase transition from water to ice. YoichiroNambu Peter Higgs cool down of the universe Early universe Now Vacuum= the lowest energy state The Higgs field obtained φ0 at the vacuum and the symmetry breaks down.

  10. Mass = Immobility/Inertia Since Higgs does not interact with a photon, photon is massless. Top quark mass/Electron mass= 350,000 Why they are so different ? Neutrinos may have different mechanism for obtaining the small masses. γ e x x x x x x x W x x t x x x x Particles with the same energy

  11. CERN Annual budget ： approx1,200MCHF(1,000 oku-yen) Number of staff ： approx. 2,500 Member states ： 20European countries Observer states ； Japan、USA、Russiaet al. Annual number of CERNusers ： approx.10,000 （Established 1954） 11

  12. Higgs Bosons are produced at LHC Large Hadron Collider at CERN 7TeV proton 7TeV proton ・ Constructed in the LEP tunnel （construction decision 1994） ・ 8.3T Supercond. Magnets ・ Complete constr. in 2008、… ・ Start operation with 3.5+3.5TeV energies （World highest energy） in 2010 TeV = Tera-electronvolt= 1012 eV

  13. Detect Higgs Boson with ・直径 22m、長さ 44m、重さ 7000t ・世界最大の超伝導トロイド磁石 ・粒子検出器のセンサー数は全部で約1億チャンネル ・38ヵ国からの約3000名の研究者による国際共同実験 ・日本グループ（15の大学・研究所、110名）はミューオン 　トリガー検出器、内部飛跡検出器、ソレノイド超伝導磁石 　などに貢献 ATLAS exp. (AToroidal LHC Apparatus)

  14. Production and decay of Higgs Boson @LHC p p p Space hadrons g t H g H→ｂｂ：　Decay fraction ＝65% hadrons p Time

  15. Higgs two photon decay H→γγ γ γ Decay fraction2/1000 H p Space hadrons γ g t H γ g hadrons p Time

  16. Higgs Boson Searches at LHC pp  H+ …  gg+ … LHCの陽子陽子衝突で ヒッグス粒子が生成され ２光子（ガンマ線）に崩壊 する事象の候補。 バックグランド事象も 多い。 16

  17. Candidate of H  ZZ(*)  4μ（m4μ= 125.1 GeV） 17

  18. ATLASRESULTS （July 4th） gg invariant mass 4lepton invariant mass

  19. Combined results:Discovery！ p0: Probability calculated from pure background Maximum excess observed at mH = 126.5 GeV Local significance (including energy-scale systematics) 5.0 σ Probability of background up-fluctuation 3 x 10-7 Expected from SM Higgs mH=126.5 4.6 σ

  20. The next step International Linear ColliderILC Electron-positron reactions are cleaner than pp collisions (LHC) ⇒Detectors are designed. Accelerator technology needs R&D ⇒end 2012 TDR Candidate sites in Japan Sefuri-mountains, Kitakami-mountains

  21. Precise measurement of Higgs Boson ⇒Deduce Principal Low in the Nature Higgs Boson 5 ILC is the Higgs Boson Factory O(10 ) such events will be collected and studied. Origin of mass Structure of the ‘vacuum`. - - - + + e e Z + H e e + b b

  22. ？ Unification of Forces Electricity Electro-magnetic Int. Maxwell Magnetism W/Z CERN Electro-Weak Int. Weinberg et al. Grand-Unification with SUSY β-decay Weak Interaction Fermi ＬＥＰ etc. Nuclei Strong Interaction QCD Super-string？ Rutherford Yukawa Gluon DESY ＬＨＣ/ＩＬＣ Terrestrial experiments Galileo Gravity General Relativity Quantum Gravity？ Newton Einstein Evolution of Planets Kepler

  23. Before going back to home please memorize these key words Higgs Boson LHC at CERN International Linear Collider = ILC

  24. Spare slides

  25. Supersymmetry (SUSY) FermionsBosons Supersymmetric partner of electron selectron spin = 0 Wave function of spin1/2 Fermion electron spin =1/2 ・SUSY is a space-time symmetry It plays a crucial role for the unification of forces with gravity Number of extra-dimensions in the string theory is determined ・ Every Elementary Particle has SUSY partner, some of masses　＜ TeV ⇒ The value of the SUSY discovery is that for the Anti-particle ・ The lightest SUSY particle is the best candidate of the Dark Matter ⇒ Understanding of the structure of the universe ～

  26. Ordinary particles SUSY partners Gauginos Ordinary particles Gauge bosons Gauge bosons Scalar Fermions Dark Matter Candidates Leptons and Quarks Leptons and Quarks Higgs bosons Higgs boson Higgsinos Higgs and SUSY are undiscovered Supersymmetry (SUSY) Stabilization of Higgs Boson Mass due to a cancellation ⇒Numbers of Fermion and Boson fields are identical ~ + f f _ h h h h

  27. pp-collision　ｖｓ　e+e- collision 例　ヒッグス粒子生成 陽子・陽子衝突 陽子は複合粒子　⇒　反応は複雑 　高放射線 　高事象頻度 ⇒ハイテクが必要 hadrons p g t - bb H g p hadrons 電子・陽電子衝突 μ＋μ- Ｚ 電子・陽電子は素粒子　素過程の直接観測 ⇒　実験は容易 - e Z - e + H bb

  28. Limit of High Energy Circular e+e- Colliders Reaction is simple, experiment is cleanbut… Electronand positrons loose energy due to synchrotron radiation Energy loss per trun ΔE is given by ΔE ∝ （E/m）４/Ｒ E：particle energy ｍ：particle massＲ：radius E,m ２Ｒ Defeat the energy loss and obtain higher collision enrgy （１）Use heavier particle (proton mass/electron mass＝1800）⇒LHC （２） Larger radius⇒　ＬＥＰ（２７ｋｍ）　⇒ILC

  29. 電子・陽電子リニアコライダー 放射光のエネルギー欠損を補ってより高いエネルギーを得たい Ｒを大きくする　⇒　Ｒ＝∞　にしてしまえ　！ 放射光の出ない線形加速器　（リニアコライダー） e- e+ 一方から電子、他方から陽電子を加速して正面衝突高加速勾配、ビームを小さく絞り込む技術が必要　　　　　　　　ＬＥＰ／ＬＨＣ加速器を伸ばしたくらいの長さ

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