DZero experiment Recent results. Теватрон вышел на проектную светимость, и в настоящее время за 1 месяц работы набирается интегральная светимость больше. - презентация

1 DZero experiment Recent results

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7 Теватрон вышел на проектную светимость, и в настоящее время за 1 месяц работы набирается интегральная светимость больше чем во всём Run I. Сейчас интегральная светимость – ~ 5 fb -1, к концу 2009 г. – 6-7 fb -1, 2010 – 8-9 fb -1, 2011 ?

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13 micro strips, Δx= 50 – 70 μm

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18 PNPI Readout electronics for mini drift tubes Software for the data acquisition by our electronics Software for the electronics interface Determination of the D0-Tevatron luminosity Calibration of the D0 Calorimeter Calibration of the D0 ICD Reprogramming of the electronics Estimation of the D0 SM background for top quark and Higgs boson physics Publications ~ 20 in 2007 ~ 40 in 2008 ~ 100 in total during Run II Our contribution - 1 paper

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20 Top quark cross section production: σ = 6.8 +/- 0.6 pb

21 Assuming that production is governed by the SM, Top quark mass can be extracted comparing the measured cross section with theory

22 t - anti-t forward-backward asymmetry pp tt + X Events where the top quark is more forward with respect to the p-beam Events where the anti-top quark is more forward with respect to the p-beam The SM NLO QCD – A bf = 5-10% First measurement (D0): A bf = 12 +/- 8 % The measured A bf is consistent with the MC NLO SM predictions

23 M t & M W M H m t ~ gold atom It is the only bare quark. It decays so quickly that the strong force does not confine it.

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25 Single top quark production for the first time was observed at D0

26 D0 CDF 0.68 |V tb | 1.0 SM V tb 1.0 (6 quarks)

27 B – B mixing and oscillations |B 1 = ( |B + |B ) / 2 = |B H B H M H, Γ H |B 2 = ( |B - |B ) / 2 = |B L B L M L, Γ L If initially start with a B Prob[B](t) = [ exp(-Γ 1 t) + exp(-Γ 2 t) + 2 exp(-Γt) cos(Δmt)] Prob[B](t) = [ exp(-Γ 1 t) + exp(-Γ 2 t) - 2 exp(-Γt) cos(Δmt)] A={N[B](t) – N[B](t)}/{N[B](t) + N[B](t)} cos(Δmt) Asymmetry A Δm = M H – M L ΔΓ = Γ L - Γ H

28 B s 0 oscillations B s 0 – (bs) τ( B s ) 1.5 ps |V td |/|V ts |=0.21 +/ This result rules out some versions of the SUSY theory which predict faster rates of oscillations B s 0 μ + D s – X, D s – φπ –, φK + K – Δm s ~ |V tb V ts | 2, Δm d ~ |V tb V td | 2 SM: Δm s = ps -1 D0: 17 Δm s 21 ps -1 CDF: Δm s = – 0.2 ps -1

29 B s 0 mixing parameters B s 0 J/ψ φ J/ψ μ + μ – Φ K + K – SM Φ s = – / Time-dependent angular distributions of μ +, μ –, K +, K –

30 First direct observation of the strange b baryon Ξ b - The STANDARD MODELd u s c b t M d =6 MeV, M u =3 MeV, M s =100 MeV, M c =1.2 GeV, M b =4.4 GeV, M t =173 GeV Λ b (udb) was observed previously Ξ b (dsb) - ? – indirect evidence was obtained at the CERN LEP collider An excess of Ξ events was observed in jets. This excess was interpreted as due to Ξ b Ξ l X The lifetime of Ξ b was estimated to be 1.4 +/- 0.3 ps. The mass of Ξ b is expected to be 5.7 – 5.8 GeV DELPHI 1995, ALEPH 1996, DELPHI D0 – first direct observation of Ξ b -- Phys. Rev. Lett. 99, (2007)

31 Ξ b J/ + Ξ J/ + - Ξ p J/ (cc) M=3.097 GeV Ξ (dss) M=1.315 GeV, = 290 ps. (uds) M=1.116 GeV, = 263 ps. (Ξ b ) = ~ mm (Ξ ) = ~ 5 cm (Λ) = ~ 5 cm

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33 Mass spectrum of Ξ –

34 Mass spectrum of Ξ b –

35 M(Ξ b )= / GeV 15 событий над фоном в 3 события. Significance

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37 First observation of the doubly strange b baryon Ω b -

38 M(Ω - ) = Gev/c 2 Mass spectrum of Ω –

39 M(Ω b - ), theory: 5.9 – 6.1 GeV/c 2 probability of background fluctuation - < 7*10 -8 Mass spectrum of Ω b –

40 Higgs search at DZero Higgs production rate excluded on the 95% C.L. Previous studies – M Higgs > 114 GeV Indirect evidence – M Higgs < 180 GeV

41 D0+CDF exclude a Higgs boson with a mass of ~170 GeV at the 95% confidential level. Combined D0 and CDF result

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43 First observation of double Z production pp ZZ ZZ 4e, 4μ, 2e2μ Observed 3 events, the background being 0.14 events. Theory: σ = 1.4 +/- 0.1 pb. The significance is 5.7 σ Experiment D0: σ = 1.6 +/- 0.6 pb, Experiment CDF: σ = 1.4 +/- 0.7 pb.

44 M[X(3872)] = (stat) (syst) MeV/c2; M[D 0 ] + M[D 0 *] = X(3872) – (cc), (ccqq), (D 0 D 0 *) ? X(3872) J/ψ ππ ψ(2S) J/ψ ππ X(3872) is not a 4 quark state

45 Inclusive jet production pQCD – perturbative QCD

46 Распределения по поперечному импульсу лидирующей струи для одно-, дважды-, трижды- и четырежды инклюзивным событиям: (a), (b), (c) и (d), соответственно. Гистограммы показывают результаты моделирования PYTHIA. Г. Обрант Данные свидетельствуют о большом (~50%) вкладе в сечение множественных партонных взаимодействий

47 b and c quarks in the proton Production rate for photons in association with a b quark (left) or a c quark (right) versus the photon transverse momentum pp γ + bpp γ + c

48 Димюонный спектр в области инвариантной массы B s 2µ Br(B s 2µ) = * % CL ? (SM - 3*10 -9 ) B s 2µ

49 Search for excited electrons Leptons and quarks consist of 3 fermions or a boson and a fermion ? The distribution of the e 2 γ invariant mass compared with the SM expectation and a possible e* signal for m e * = 100 GeV D0 no evidence of e* with m[e*] 800 GeV

50 Search for charged massive stable particles (tau sleptons, gaugino-like charginos, higgsino-like charginos, candidates for dark matter)

51 No evidence for such particles. σ < 0.3 – 0.04 pb for stau masses 60 – 300 GeV

52 Search for scalar or vector particles decaying into Zγ Z l + l - Experimental limits on the production cross section: M = 140 GeV – σ 3 pb, M = 600 GeV – σ 0.2 pb.

53 Search for large extra dimensions Kaluza-Klein graviton pp g + γ register a photon with p t > 90 GeV and E t _ miss > 70 GeV Lower limits on the fundamental mass scale M D

54 Поиск квантовой гравитации pp W(Z) + g W μ + ν g – Kaluza-Klein graviton Отбор: малая суммарная энергия в калориметре, большой поперечный импульс μ – мезона, большая недостающая поперечная энергия. pp W(Z) + g modernized generator has been included to Pythia 8.3

55 MET distribution of the data for p t (μ) > 15 GeV, Σ E t (calorimeter) < 15 GeV. In 2009, simulations of the MET spectrum for the signal, simulations of the background processes.

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