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Martin zur Nedden, HU Berlin 1 WS 2007/08: Physik am LHC Kap 4: Heavy Quarks Physics Introduction and overview Measurement of heavy quarks Production of.

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Presentation on theme: "Martin zur Nedden, HU Berlin 1 WS 2007/08: Physik am LHC Kap 4: Heavy Quarks Physics Introduction and overview Measurement of heavy quarks Production of."— Presentation transcript:

1 Martin zur Nedden, HU Berlin 1 WS 2007/08: Physik am LHC Kap 4: Heavy Quarks Physics Introduction and overview Measurement of heavy quarks Production of Heavy Quarks at TEVATRON: –b-selection methods –Cross section measuremtens Top search and mass measurement at TEVATRON Heavy quarks at LHC –BSM searches with rare B-decays –Top physics at LHC

2 Martin zur Nedden, HU Berlin 2 WS 2007/08: Physik am LHC Motivation Exploring the Big Band – Quark-Gluon-Plasma (LHC: ALICE) Test of symmetry of forces – CP-violation Kosmology – dark Matter Structure of strong and weak interaction – Strong coupling constant – Quark-Mixing-Matrix Search for new Physic (Beyond Standard Model) – Precission measurements Heavy Quarks are improtant tools for:

3 Martin zur Nedden, HU Berlin 3 WS 2007/08: Physik am LHC Quarks and Leptons Masses in MeV 0 +2/3 -1/3 CHARGE the top-Quark mass Is huge (175 GeV) …

4 Martin zur Nedden, HU Berlin 4 WS 2007/08: Physik am LHC Hidden Flavours: States wiht Quarks and corresponding Antiquarks Analogy to Positronium Spectroskopy of strong Interaction c-Quarks: and excited states (Ψ, χ c, etc.) b-Quarks: and excited states (Y, Y, etc.) Open Flavours: States with other (light) Quarks/Antiquarks c-Quarks: b-Quarks: no bound states wiht top-Quarks Decay channels J/Ψ, Υ e + e -, μ + μ - : easy to reconstruct B 0 J/Ψ + X : well measurable decay length b c + μ + υ μ : well measurable impact parameter Particles with heavy Quarks

5 Martin zur Nedden, HU Berlin 5 WS 2007/08: Physik am LHC Decays of heavy Quarks hadronic decay semi-leptonic decay decay into a CP-Eigen state: without B 0 - Oscillation with B 0 - Oscillation

6 Martin zur Nedden, HU Berlin 6 WS 2007/08: Physik am LHC Methods of b-tagging momentum of myons relativ to Jet-Axix: p t rel based on Jet (calorimeter) and MYON information: b-Jet Decay length of B-hadrons: track- und vertex-information necessary: pp bb X J/ψ XY XY measurement of secundary vertices semi leptonic b quark decay pp B + B - XY

7 Martin zur Nedden, HU Berlin 7 WS 2007/08: Physik am LHC Reconstruction of decay vertices experiment D0 (Tevatron): Z bb

8 Martin zur Nedden, HU Berlin 8 WS 2007/08: Physik am LHC Production of heavy Flavours Production in hadronic interaction Parton-Density FuctionsPartonic cross section Hadronization: formation of hadrons with heavy quarks faktorisation

9 Martin zur Nedden, HU Berlin 9 WS 2007/08: Physik am LHC Reconstruction of the Decay Length decay length in the lab-system: L = c t ß γ

10 Martin zur Nedden, HU Berlin 10 WS 2007/08: Physik am LHC Impact-Parameter in b-flavourd Jets

11 Martin zur Nedden, HU Berlin 11 WS 2007/08: Physik am LHC ATLAS Inner Detector (ID) The Inner Detector (ID) is organized into four sub-systems: Pixels ( channels) Silicon Tracker (SCT) ( channels) Transition Radiation Tracker (TRT) ( channels) Common ID items

12 Martin zur Nedden, HU Berlin 12 WS 2007/08: Physik am LHC b-Reconstruktion from 2-Muon events

13 Martin zur Nedden, HU Berlin 13 WS 2007/08: Physik am LHC b production-cross section at TEVATRON

14 Martin zur Nedden, HU Berlin 14 WS 2007/08: Physik am LHC Pseudo-Proper time of the J/ψ

15 Martin zur Nedden, HU Berlin 15 WS 2007/08: Physik am LHC J/ψ for B-Hadron Identification at CDF

16 Martin zur Nedden, HU Berlin 16 WS 2007/08: Physik am LHC Search for Toponium…

17 Martin zur Nedden, HU Berlin 17 WS 2007/08: Physik am LHC Discovery of the top-Quark 1995 at TEVATRON in Proton-Antiproton interactions

18 Martin zur Nedden, HU Berlin 18 WS 2007/08: Physik am LHC Top-Decay Channels Top production at TEVATRON dominated by quark – antiquark processes, At LHC by gluon-gluon interactions, decay channels are the same….

19 Martin zur Nedden, HU Berlin 19 WS 2007/08: Physik am LHC Observation in the Muon-Channel Lepton + Jet channel: 1 L + 2 J + 2 b-J + 1 MET

20 Martin zur Nedden, HU Berlin 20 WS 2007/08: Physik am LHC Observation in the Electron-Channel 2 Lepton channel: 2 L + 2 b-J + 2 MET

21 Martin zur Nedden, HU Berlin 21 WS 2007/08: Physik am LHC Observation based on Jets Jet channel: 4 J + 2 b-J

22 Martin zur Nedden, HU Berlin 22 WS 2007/08: Physik am LHC Top-Event-Displays von D0 (Tevatron) 2 with Jets with 4 Jets

23 Martin zur Nedden, HU Berlin 23 WS 2007/08: Physik am LHC Top-Eventdisplays of D0 (Tevatron) e wiht 4 Jets e with Jets

24 Martin zur Nedden, HU Berlin 24 WS 2007/08: Physik am LHC Example of a 2-myon Event

25 Martin zur Nedden, HU Berlin 25 WS 2007/08: Physik am LHC Signal/Background in top/Anti-top production Top events are multi jet events

26 Martin zur Nedden, HU Berlin 26 WS 2007/08: Physik am LHC Top mass reconstruction

27 Martin zur Nedden, HU Berlin 27 WS 2007/08: Physik am LHC Mean Value of the Top-Mass (TEVATRON)

28 Martin zur Nedden, HU Berlin 28 WS 2007/08: Physik am LHC Cross Section Measurement

29 Martin zur Nedden, HU Berlin 29 WS 2007/08: Physik am LHC Mean Value of Top-Production Cross Section

30 Martin zur Nedden, HU Berlin 30 WS 2007/08: Physik am LHC big bb productions-XS: ~ 500 µb (~ 1 bb pairs per 100 p-p collisions) high tt production-XS: ~830 pb (~ tt pairs per year) –LHC is a top-factory –important tool for detector- calibration and trigger comissioning Luminosity phases: –2008: ~ 100 pb -1 –2009: more than 1 fb -1 at an available luminosity of cm -2 s -1 (~10 fb -1 per year) –design: High-Luminosität: cm -2 s -1 (~100 fb -1 per year) Heavy Quarks at LHC

31 Martin zur Nedden, HU Berlin 31 WS 2007/08: Physik am LHC General Strategy for B Physics at LHC General-purpose experiments for discoveries: main emphasis on high-pT physics beyond the Standard Model B-physics programme depending on stages of the LHC operation: Huge b-hadron production statistics allow precise measurements of their properties Theoretical descriptions of heavy flavoured hadrons need input from LHC Precision measurements already achievable after one year of data taking Inclusive production cross section measurement in the initial phase Measurements extending the discovery potential for BSM physics measurements of CP violation parameters that are predicted to be small in the SM (e.g in B s J/ ( ) ) measurements of rare B-decays (B d K*, B d K*, B s, B s, B s, B ) Focus on physics topics that will not be accessible for the B-factories mainly B s, baryon and double heavy flavour hadrons (B s D s, B s J/ ( ), b J/ 0, …)

32 Martin zur Nedden, HU Berlin 32 WS 2007/08: Physik am LHC Trigger Strategies for B-Physics limited bandwidth for B-triggers: highly efficient and selective trigger needed. c- and b-events contain mostly low p T particles: challenge to trigger on those events many b-decays contain J/ψ : useful for calibration, optimization and understanding of detector, trigger as well as B-physics B-trigger is based on single- and di-muons in final state BR ~ 10 %, but clean signature at early level in trigger and give flavour tag lower lumi (< 2*10 33 cm -2 s -1 ) LVL1 single -trigger with additional LVL1 signature or a jet in calorimeter at LVL2 use LVL1 Regions of Interest (RoI) to seed LVL2 reconstruction: Jet RoI: for hadronic final states (e.g. B s D s ( π)π) EM RoI: for e/ final states (e.g. J/ψ ee, K*γ, γ) Muon RoI: to recover di-muon final-states in which second muon was missed at LVL1 LVL1 di-muon trigger high lumi (>2x10 33 cm -2 s -1 ) LVL1 di-μ trigger B J/ψ( ), rare decays (B, B K 0* μμ), double semi leptonic decays all single- all di- h (hadron) b (beauty) c (charm) J/ ATLAS rates for 14 TeV and cm -2 s -1

33 Martin zur Nedden, HU Berlin 33 WS 2007/08: Physik am LHC b d, s transitions (FCNC) are forbidden at the tree level in SM and occur at the lowest order through one-loop-diagrams penguin and box Main points to study: good test of SM and its possible extensions information of the long-distance QCD effects determination of the |V td | and |V ts | some of the rare decays as background to other rare decays (for example B d as bkg for B d,s + - ) Searches: Rare B-Decays B s μ + μ -

34 Martin zur Nedden, HU Berlin 34 WS 2007/08: Physik am LHC Example: ATLAS offline analysis for B s Cuts B 0 s signal BG (bb X) p T >6 GeV, ΔR <0.950 events 6.0×10 6 events M cut ( M μμ = M Bs MeV) ×10 -2 Isolation cut: no charged tracks with p T > 0.8 GeV in cone < 15 degrees ×10 -2 L xy / (L xy )>11, 2 <15 (transverse decay length) vertex fit with pointing to primary vertex constraint 0.4 < 0.7×10 -4 All cuts720±12 Expected signal v.s. inclusive bb μμX background Background:

35 Martin zur Nedden, HU Berlin 35 WS 2007/08: Physik am LHC Projected upper limits: B s extraction of upper limit on Br(B s μμ) (from 7 signal and (20±12) background events) ATLAS experiment expects to reach the sensitivity of SM prediction Still factor of 10 above The measurement of B s μμ is still feasible at nominal LHC luminosity cm -2 s -1. This would mean 100 fb -1 just in one year. Tevatron projection

36 Martin zur Nedden, HU Berlin 36 WS 2007/08: Physik am LHC Top-Decay channels charakteristic Signal: Lepton + missing energy only Jets in final state: dominant BG from QCD-multijet-events

37 Martin zur Nedden, HU Berlin 37 WS 2007/08: Physik am LHC Top – Physics at LHC/ATLAS measurement of the top-Quark mass – using m t = m jjb (m jj = m W ) pairproduction of top-Quarks – Tag via leptons and E T miss decay of top-Quarks – Branching ratios / coupplings – rare decays: t g/ /Z q (q=u,c: FCNC) Single top-Production ideal standard-candel – Detekctor calibration and trigger optimization

38 Martin zur Nedden, HU Berlin 38 WS 2007/08: Physik am LHC Single-Top Produktion direkte Bestimmung der Kopplungsstärke des t-W-b Vertex: W-Gluon-Fusion: sensitiv auf Modifikationen der Kopplungen des top-Quarks an andere SM-Teilchen Wt: sensitiv auf FCNC W*: sensitiv auf neue, schwere W-Bosonen wesentlich geringerer Anteil an der top-Produktion bei LHC W-Gluon-Fusion t-Kanal Direkte Produktion, Wt-Prozess W*-Prozess s-Kanal

39 Martin zur Nedden, HU Berlin 39 WS 2007/08: Physik am LHC Connection of W- and Top-Masse


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