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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