lhcb activities edinburgh ppe meeting
DESCRIPTION
LHCb Activities Edinburgh PPE Meeting. M. Needham 12 th December 2012. Outline. Overview of LHCb Edinburgh activities. Introduction Hardware activities: HPDs Momentum scale calibration + mass studies ϕ s and Bd J/ ψ K*. Then Dean will talk about charmless decays…. LHCb Detector. - PowerPoint PPT PresentationTRANSCRIPT
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LHCb ActivitiesEdinburgh PPE Meeting
M. Needham 12th December 2012
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OutlineOverview of LHCb Edinburgh activities
Then Dean will talk about charmless decays…
• Introduction
• Hardware activities: HPDs
• Momentum scale calibration + mass studies
• ϕs and Bd J/ψ K*
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LHCb Detector
pp collision Point
Vertex Locator VELO
Tracking System
Muon System RICH Detectors
Calorimeters
~ 1 cm
B
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LHCb running
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LHCb running
More than 0.5 billion events with a triggeredJ/ψ signal candidate on tape
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HPD monitoringDean/Stephen
Edinburgh was responsible for testing and quality assurance of the LHCb RICH photodetectors. Now responsible for maintainance
Unfortunately, vacuum of tubes degrades and leads to ion feedback (tubes ‘glowing’)
Continous campaign of monitoring (which tubes need replacing during TS),replacing and repairing new tubes
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Photodetectors for the upgrade
For planned LHCb upgrade in 2018 photodetectors will be replaced
Candidate is Hammatsu R11265 MaPMT
Being characterized in Edinburgh:
• Single photoelectron spectra
• Gain variation
• Cross-talk
Haofei/Stephen
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QCD @ LHCb• LHCb is more than triangles !
• Great testing ground for QCD studies
• QCD is the physics of the LHC
• Quarkonia cross-sections, probes of DPS, mass measurements….
• Unique measurements due to forward coverage of LHCb
Today mention mass measurements
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Pre-warning to Atlas folks
The next slides contains images of precision tracking. Phd students on other experiments are required to be accompanied by a supervisor
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Momentum scale calibration
Resolution improved by several MeV !(~ 7 % relative)
Phase spaced dependent momentum scale using B+ J/ψ K+
LHCbNot official
Matthew Needham
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b-baryon mass measurementEarly 2011 paper: b-hadron masses: An unexpected journeySequel, coming soon b baryon masses: The desolation of D0
LHCbNot official
LHCbNot official
LHCbNot official
LHCbNot official
D0 did not see the Ωb
Matthew Needham
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D meson massThere and back again…
LHCbNot official
LHCbNot official
LHCbNot official
World best measurements…paper forwinter conferences
Matthew Needham
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Bs mixing
B
B
f
_
Flavour eigenstates mix to give physical states BH and BL
Observable phase s = -2s = M - 2 D
In the Standard Model expected to be small s = - 0.04 radian
Larger values possible in models of New Physics such as Supersymmetry and Little Higgs
-D
D
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Mixing Parameters
Measurement of ϕs in Bs J/
● High yield: (25 k signal events/1fb-1 at 7 TeV)
● Vector-Vector final state: Admixture of CP eigenstates
● Time dependent Angular analysis needed
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Transversity angles Ω = θ, ϕ, ψ
CP Odd
CP Even
Rob Currie, Pete Clarke, Dianne Ferguson
Measurement of ϕs in Bs J/
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Unbinned maximum likelihood fit to mass, time and angles
Angular acceptance for signalfrom simulation
Mass sidebands or sWeight technique to determine angular distribution of background
Mass distribution
Mistag rate measured using B+ J/ψK+ calibration channel
Resolution model from prompt J/ψ Peak. Resolution ~ 50 fs
Time acceptance due to cuts in the trigger + reconstruction effects
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ϕs in Bs J/
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Preliminary result presented on 2011 (1 fb-1) dataset for Moriond
Final results for 2011 data being prepared: add lifetime biased triggers, same-sign kaon tag,
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ϕs: Last Christmas ambiguity Resolution
),,,,( 000|| sss ),,,,( 00||0 sss
S wave
P wave
S - P wave
Choose the solution with a decreasing trend of δs- δP vs mKK in the ϕ(1020) mass region
K+K- P-wave:Phase of Breit-Wigner increases rapidly acrossϕ(1020) resonance
K+K- S-wave: Phase of Flatté amplitude for f0(980) relatively flat (similar for non-resonance)
[Y. Xie et al., JHEP 0909:074, 2009]
Similar to Babar measurement of sign of cos(2β), PRD 71, 032005 (2007)
Use few % S wave KK present in the sample
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ϕs: Ambiguity Resolution
Solution I displays the expected decreasing trend
Santa’s present last yearBackground subtracted m(KK)
Dataset used for the LP result (350 pb-1),open up m(KK) mass cut
Perform analysis in four bins of m(KK) and extract phase dependence
1 σ2 σ
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ϕs: Ambiguity Resolution
Data favour the Standard Model solution
Paper publishedin PRL
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ϕs in Bs J/
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Preliminary result presented on 2011 (1 fb-1) dataset for Moriond
Final results for 2011 data being prepared: add lifetime biased triggers, same-sign kaon tag,
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ϕs in Bs J/
21Go to paper (soon) !
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Bd J/K*
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Thesis: Ailsa Sparkes
Determination of polarization amplitudesCP asymmetries ..
Bd Bs
Key is understanding acceptance (slow pion from K*) + large sWave
Aim for paper in the spring….
LHCb not official
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Summary
• Wide range of activities in the group: not all covered today
• LHCb is not just triangles
• 5 published papers this year where LHCb-Edinburgh took a leading role
• Another 6 coming early next year…
Over to Dean….
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Backup