Results from B-Physics (LHCb, BELLE)

Transcription

1 Prospects for Charged Higgs Uppsala, Sweden, September Results from B-Physics (LHCb, BELLE) Valery Pugatch Kiev Institute for Nuclear Research, NASU On behalf of the LHCb Collaboration 1

2 OUTLINE Introduction LHCb and BELLE: B - factories B - spectroscopy, decays, lifetimes CP symmetry Rare decays Search for NP (multi-quark systems, lepton number violation, charged Higgs boson, ) Summary and outlook V. Pugatch. Prospects for Charged Higgs 2

3 Introduction LHC : new events at up to еv energy in 35 /fb data (Run1). Precision measurements the way to search for New Physics. CERN. 4 th July The first Higgs boson! Charged Higgs bosons? New Physics (?) - super-partners in loops,? This talk: 1. LHCb ( BELLE ) precision measurements for the NP search : B - spectroscopy CP symmetry Rare decays 2. Search for NP: - multi-quark systems, lepton number violation, - charged Higgs boson search at B-factories 3. Future studies V. Pugatch. Prospects for Charged Higgs 3

4 New Physics & Higgs at B-factories. Study B-decays to predictable final states - for instance, with τ leptons, through tree-level processes evolving via b ->sq~q, b-> sγ, (with Higgs) Measure & compare with SM predictions: o Differential cross-sections o branching ratios o forward-backward asymmetries, o isospin asymmetries, -> to exclude uncertainties 4

5 New Physics & Higgs at B-factories. Requirements to the experimental setups. Beauty Identification at LHCb Flavor tagging B s identification Efficient trigger selecting B-hadrons decay products Excellent separation of secondary vertex allows to study B s oscillations with minimal time quantization of 40 fs. Background suppression: o due to high invariant mass-resolution (~14 MeV/c 2 ) o Perfect particles identification o Magnetic field flipping up-and-down (artificial asymmetries removal) 5

6 New Physics & Higgs at B-factories. Requirements to the experimental setups. Example: B -> τ ν & BELLE: Tracks, Vertices, ID, Momentum and Energy, Triggering, Event reconstruction efficiency, Background suppression etc., 6

7 The LHCb experiment The LHCb detector forward spectrometer with excellent characterisitics suitable for B- physics stuides: Acceptance 2 < η < 5 LHCb: The Large Hadron Collider Beauty Experiment for Precise Measurements of CP-Violation and Rare Decays RMS Momentum resolution about 0.5 % Track reconstruction efficiency > 96 % Impact parameter resolution: ~ 20 μm Decay time resolution: ~45 fs Invariant mass resolution: ~(10-20) MeV/c 2 Ring-Imaging Cherenkov Detectors and Muon system - particle identification (ID efficiency > 90%) p p Integrated luminosity 2010: 37 pb : TeV 2012: 2 8 TeV V. Pugatch. Prospects for Charged Higgs 7

8 LHCb. B-factory: proton-proton collisons protons per bunch collided at 7 and 8 TeV in 2011 and 2012 delivering luminosity at IP-8 (LHCb) (2-4) times cm -2 * s -1 In each p-p collision about 1500 charged particles are produced: Challenging radiation load on detectors Multi-level triggering for preselection of Beauty and Charm events in LHCb Integrated cross-sections B + ~39 µb B 0 ~38 µb B s ~10 µb Uncertainty ~ 10 % LHCb-Paper New Physics may modify measured features of CP-violation and Rare decays via its contribution in loop diagrams 8

9 BELLE. B-factory: electron-positron collisons KEKB. BELLE detector. (e + e - ) collisions at Y (4S) resonance. Clean samples of B-mesons. Data set fb -1 (total fb -1 ) ( ) Upgraded (2016) Belle II will run at 8.0 x cm -2 s -1 (40 times higher than at KEKB). 9

10 Spectroscopy - a perfect tool for searching NEW. LHCb Spectroscopy High energy of collisions at LHC: production rates by many orders of magnitude higher in comparison with lepton B-factories. All b-hadron species (but top-quark containing) were identified. V. Pugatch. Prospects for Charged Higgs 10

11 Spectroscopy - a perfect tool for searching NEW. Heavy flavour spectroscopy. Excited states of Λ b Excited states are known for the Λ and Λ c. Two excited states of Λ b (at and MeV/c 2 ) were observed for the first time in the Λ 0 b π + π - mass- spectrum. Uncertaintes are less than 1 MeV/ 2 c. Λ b reconstructed in the Λ c+ π - invariant mass spectrum. Phys.Rev.Lett.109(2012) Discrepancies with theories reach MeV/c 2 V. Pugatch. Prospects for Charged Higgs 11

12 ϒ (3S) ϒ(2S) ϒ(1S) Spectroscopy - a perfect tool in searching for NEW. Heavy flavour spectroscopy. χ b radiative decays LHCb-PAPER LHCb. ( 7 & 8 ) 3 fb -1. Reconstruction of χ b -> ϒ γ : (di-muon (ϒ) + photon ) candidates Signals: χ b1 green, χ b2 magenta The observation of the radiative transition of χ b (3P) meson to ϒ (3S) -> the most precise value of the mass χ b1 (3P) 12

13 Spectroscopy and products angular distributions. A perfect tool for searching NEW. Z (4430) four-quarks resonant state Z(3900) (BELLE, PRL 110 (2013) Z(4430) - First observed by BELLE (Phys.Rev. D88:074026) LHCb Confirmed (PRL, 112, (2014) The same decay studied: B 0 -> K + π - ψ (2S) J P = 1 + assigned 13

14 Measurement of Lifetime a tool to identify KNOWN and NEW Lifetime: B-meson and Λ b - baryon HQE- theory [NPB, 483, 339, 1997] : Heavy b-quark determines the lifetime: equal for two b-species. The role of the third particle might be essential! Nuclear Physics the Coulomb field of the 3d particle modifies the observed width of the two-body short-lived resonance. LHCb result: τ(λ b ) = 1.482±0.018±0.012 ps τ(λ b )/τ(b 0 ) = 0.976±0.012±0.006 Confirmation of the HQE theory. V. Pugatch. Prospects for Charged Higgs 14

15 Evolution of Events in Time signature for NEW B s oscillation frequency Tagged flavor evolution measurements with an accuracy of 45 fs. Results for the B s -mesons decays into D - sπ + and D + sπ -. The extracted frequency of oscillations Δm s = ± ± ps -1 V. Pugatch. Prospects for Charged Higgs 15

16 Evolution of Events in Time signature for NEW B 0 oscillations observed in D + π - and J/ψK *0 decays Combined for two decay channels Δm d = ± ± ps -1 The most precise measurement of the oscillation frequency for B 0 mesons. LHCb-PAPER arxiv PLB.719(2013)318 16

17 Evolution of Events in Time signature for NEW Neutral B s and B d mixing frequences measured using semileptonic decays LHCb measures flavor evolution (mixing) with an accuracy of 45 fs due to VELO displaced vertex reconstruction with an accuracy of few tens µm. Characteristic features of mixing: mass difference Δm (related to the frequency of mixing), width difference ΔГ, phase between the decay and mixing amplitudes Φ s. Phys. Lett. B 723 (2013)

18 Measuring asymmetries - restrict the systematic errors in search for NEW CP symmetry violation CP Violation (CPV) potential source of New Physics SM expectations are significantly lower than needed to explain baryon asymmetry in the Universe. Three ways for CP violation: Direct - in decay Indirect - in mixing Interference of the above two processes. B mesons mixing (oscillations) Mixing may proceed also via loop diagrams involving heavy particles New Physics. 18

19 Measuring asymmetries - restrict the systematic errors in search for NEW CP Violation in Beauty Direct Decays Asymmetries were derived from measured data for decays of neutral B d as well as B s mesons (to get rid out of systematic errors) A CP (B 0 K + π - ) = ± ± The most precise measurement. A CP (B 0 s K - π + ) = ± 0.04 ± 0.01 First observation of CP violation in the decays of B 0 s mesons Within SM expectations Phys. Rev. Lett. 110 (2013)

20 Measuring asymmetries - restrict the systematic errors in search for NEW CP Violation in B s Mixing Time dependent decay studies for measuring CP violating parameters in B s mixing: B s J/Ψ Κ + Κ and B s J/Ψ π + π - CP violating phase Φ s may include new physics Combined for two processes results are compatible with SM. (Phys.Lett. B736 (2014) 186) Update for 3 fb -1 Ф s = (70 +/- 68 +/- 8 ) mrad 20

21 Measuring asymmetries - restrict the systematic errors in search for NEW CP Violation in B s Mixing CKM2014 Vienna, 8-12th September

22 Measuring asymmetries - restrict the systematic errors in search for NEW CP Violation in three-body charmless B decays. The first evidence of inclusive CP asymmetry in charmless three-body B ± decays. Phys. Rev. Lett. 111 (2013) B ± K ± K + K - B ± K ± π + π - A CP = ± ± ± 0.007, 4.3 σ LHCb-Paper : From 1 to 3 fb -1 asymmetries are confirmed. A CP = ± ± ± 0.007, 2.8 σ 22

23 CKM angles in the Unitarity Triangle. φ 3 (γ) from B± Dh± decays LHCB-PAPER PLB, 726, 151 (2013) The B ± DK and B ± Dπ decays were analyzed : D decays: KK, ππ, K 0 Sππ, K 0 SKK or Kπππ. Example: γ = ( ) for B ± DK decay (68% CL). LHCb (CKM2014, Vienna). LHCb-CONF Updated LHCb combined measurements γ = ( ) 0 23

24 CKM angles in the Unitarity Triangle. Angle φ 1 (β) BELLE 24

25 CKM angles in the Unitarity Triangle. Angle φ 2 (α). B 0 -> π + π _ Global fit: φ 2 (α), φ 2 (γ) 25

26 Rare decays B 0 s µ + µ - and B 0 µ + µ - Standard Model - FCNC and helicity suppressed processes with pure leptonic final states, PRL (2014) : Br (B 0 s µ + µ - ) = (3.65 ± 0.23) 10-9 Br (B 0 µ + µ - ) = (1.1 ± 0.10) > If in experiment different evidence for New Physics. Results: 1. B 0 s µ + µ - First observation LHCb (PRL 111, (2013)) Combined LHCb & CMS (2014) (preliminary) (2.9 +/- 0.7) x 10-9 CMS PAS BPH LHCb-CONF B 0 µ + µ - Results consistent with the SM New Physics - the next digit of data accuracy? V. Pugatch. Prospects for Charged Higgs 26

27 Rare decays. Angular Distributions B 0 K + π - μ + μ -. B 0 K + π - μ + μ - - FCNC process via loop diagram in SM. - Possibility of modification of angular distributions due to contribution of new particles. In total, P 1-8 parameters determining angular distribution of final state products have been measured. The P 5 ' observable is shown as a function of the μ + μ - invariant mass squared q 2. JHEP 08 (2013) σ deviation of data above the Standard Model prediction is observed at 4.3 < q 2 < 8.68 GeV 2 /c 4. 27

28 Higgs boson searches at B-factories. Some ways how it might proceed with Higgs-bosons to observable final states. 28

29 Higgs boson searches at B-factories. B -> τν (BELLE & BABAR) B-decays with heavy τ lepton in final state may evolve with additional decay modes not present with light leptons : NP contribution might occur through tree processes Branching ratios change Predicition: Minimal extension of the SM with two Higgs doublet 2HDM Br(B->τν) = (1.11 +/- 0.28) X 10-4 Experimental results : BELLE (PRL 110, (2013) BaBaR (arxiv: (2012) averaged over hadronic and semileptonic tagging: Br(B->τν) = (1.15 +/- 0.23) X 10-4 Consistent with Standard Model 29

30 Higgs boson searches at B-factories. B -> D * τν Ratios (R) are considered : R = Br(B->D * τν) /Br(D->D * lν) to exclude experimental and theoretical uncertainties R (D) = Br(B->Dτν) /Br(D->Dlν) = / R (D * ) = Br(B->D * τν) /Br(D*->Dlν) = / (BELLE KEK FF2013) Deviations from the SM theory: R (D) : 1.4 σ; R (D*) 3.0 σ (S. Feiter et al., PRD (2012) R- dependence on the SM parameters Y. Sakai, R. Watanabe, M. Tanaka. PRD 87, (2013) 30

31 Search for NP. Lepton Flavor Violation τ - -> µ - µ + µ - (LHCb) LHCb result (1 fb 7 TeV, 2 fb 8 TeV ) branching fraction of the τ - -> µ - µ + µ - : < 4.6 x 10-8 (90 % confidence level) consistent with the SM expectation LHCb-PAPER Dashed line SM; Solid line observed. Yellow - 68 % CL, Green 95 % CL BELLE: < 2.1 x 10-8 (90 % confidence level) PLB 687, 139 (2010) 31

32 Search for NP. Lepton Flavor Violation and Baryon Number Violation LHCb LHCb Search for Majorana neutrinos in B - -> π + μ - μ - BR < 4 x 10-9 (95 % CL) (LHCb data, 3 fb -1 ) PRL 112, (2014) 32

33 Search for NP. Asymmetries. Backward Forward asymmetry in Inclusive B -> X s l + l - (BELLE) Experimental data (BELLE) The Forward-Backward Asymmetry (A FB ) for the sum of 10 exclusive states (B 0, B + ) dependence on the momentum transferred q 2. SM calculation Red band A FB <0 excluded (2.3 σ) for the q 2 > 10.2 GeV/c 2 Deviation from the SM : 1.8 σ for the q 2 <4.3 GeV/c 2 arxiv:

34 Search for NP. Asymmetries. Isospin Asymmetries (A I ). arxiv LHCb (3 fb -1 ) B -> K (*) µ + µ - 34

35 Limits on the Higgs production. LHCb Cross-section for the production of Higgs like boson does not exceed % CL The specific model BV48: msugra with baryon number violation and parameters: 114 GeV/c 2 h 0, 48 Gev/c 2 anti-x 0, 10 ps - τ (X 0 ) Data analyzed: 35.8 pb -1 ( LHCb CONF ). Further studies continue. 35

36 Limits on Higgs ττ production. LHCb SM MSSM JHEP05(2013)132 > (1 s = 7 TeV) LHCb Limit on MSSM Higgs boson production 0.7 pb < σ x BF < 8.6 pb for 90<M H < 250 GeV, Values 32 < tan β < 70 for the 90 < m A0 < 150 GeV/c 2 are excluded at 95 % CL 36

37 Limits on Higgs production. LHCb W/Z (leptons) + H b anti-b (jets) -> LHCb acceptance for the 2 b s inside the detector 5% -> LHCb acceptance for single lepton inside the detector 5% Determine limits on H bb from the observed vs expected events - Tools developed: jets and B-jet tagging - Benchmark analysis made Measurement of the central forward bb asymmetry (LHCb- CONF ) Measurement of σ(bb) with inclusive final states (LHCb-CONF ) for 2.5<η<4 and pt>5 GeV: σ(bb) = (7.7 +/ /- 0.84) μb Data analysis in progress. 37

38 Conclusions and Outlook Beauty Physics studies have been successfully carried out at the leptonic and hadronic B-factories. Substantial data sets with B-matter samples were accumulated and analyzed at the LHCb and BELLE experiments. Measurements of physics observables (new range of energy for collisions up to 8 TeV at LHC) have been performed with unprecedented accuracy (CP violation, rare decays) or for the first time (B s ->µ + µ -, CPV in B 0 s, new resonances). Efforts to establish signals beyond Standard Model are being undertaken. Most of results obtained were in agreement with the Standard Model predictions. Some disagreements in the data space sensitive to New Physics are under studies (P 5 in B 0 K *0 μ + μ -, Lepton universality in B + -> K + l + l -, ). 38

39 Conclusions and Outlook LHCb will continue data taking in planning the upgrade for running in 2019 at luminosity up to 2 times cm -2 s -1. BELLE II after upgrade aims to accumulate fb -1 data set. New Physics must exist! It might require new tools and methods to be developed for its observation. New huge energy valley opened at LHC is certainly rich by new phenomena. There are observables which have to be discovered to study New Physics! 39

40 There are new directions for HEP studies. Energy: from еv (at LHC) to еv. Space: from m to m (Universe) Time: from s to s There... New Physics! THANK YOU FOR YOUR ATTENTION! New Physics?! It might require new tools and methods to be developed for its observation. New huge energy valley opened at LHC is certainly rich for new phenomena. There might be observables which have to be discovered to study New Physics! Distribution of Galaxies visible in cosmic rays with E >10 19 ev). Scale: m. The Earth diameter - ~10 7 m, The LHC diameter ~10 4 m V. Pugatch. Prospects for Charged Higgs 40