LHCb Discovery potential for New Physics

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1 Beam induced splash in LHCb Imperial College London LHCb Discovery potential for New Physics

2 Introduction Physics with LHCb Flavour physics can provide unique input on the type of New Physics If we express the low energy behaviour of New Physics as an effective theory cn ℒ eff =ℒ gauge ℒ Higgs d 4 O dn d 4 n O d : All possible operators with heavy d.o.f c n : Parameters arising from New Physics : Energy scale of New Physics If cn~1 flavour physics tells us Λ>100 TeV or if Λ~1 TeV then flavour physics put constraints on all cn which will provide model constraints on New Physics. Will here demonstrate how this works in practise 2/19

3 Introduction Which detector to do the physics There are 4 components to a successful flavour physics programme Vertexing for secondary vertex identification Trigger to enable high statistics data collection Mass resolution to reduce background Particle identification L=2 fb 1 per year at design luminosity of cm-2s-1 3/19

4 Physics Bs µ+µ- Any pseudoscalar Higgs can modify BR by large amount Can thus set severe constraints on NP x10-8 Excluded This very rare decay has a SM branching ratio of JHEP 0710:092,2007 Ellis et al 5x10-9 Limits in ma versus tan β within MSSM 4/19

5 Physics Bs µ+µ8 SM signal and 12 background events in 2fb-1 in most sensitive region CDF with 2 fb-1 with 8 fb-1? Normalisation from Bd J/ψ K+ decay With just 0.1 fb-1 of data it will be world leading measurement. LHCb -9 BR(x10 ) Background estimated from sidebands SM prediction Luminosity (fb ) 90% Confidence limit with no signal observed 5/19

6 Physics Bs J/ψ φ The box diagram for Bs oscillations is beginning to be understood Oscillation period well measured by Tevatron Phase 2βs is 2.2σ away from SM prediction SM prediction 0.04, central experimental value LHCb will be able to improve results dramatically σ(2βs) versus lifetime resolution Lifetime resolution of 39 fs Flavour tag efficiency of 6% In 2 fb-1 of data: 100k signal events 50k background events σ(2βs) = /19

7 Physics CP angle γ A direct test of CP violation contribution from New Physics Compare angle γ measured from interfering tree decays which should always take the value from the CKM matrix to angle measured from indirect constraint Any difference is a sign of New Physics With 10 fb-1 of data we get 2-3o precision from tree decays 7/19

8 Physics B K*0µ+µAFB(LHCb) = -AFB(BELLE) 7k signal events in 2 fb-1 BELLE preliminary, ICHEP 2008, 657M BB 1k background dominated by real muons Zero point accuracy of 0.8 GeV2 in just 0.5 fb-1 Other asymmetries possible from full angular analysis AFB First measurement will be of the forward-backward asymmetry An example 0.5fb 1 experiment 2 0 q All have very small theoretical errors. q2 (GeV2) 8/19

9 Scenarios The SM Higgs and nothing else Imagine CMS/ATLAS see a SM Higgs and nothing else. In LHCb we can expect Bs µ+µ- at discovered at SM level CP angle γ at value from combined fits Bd K*0µ+µ- zero point at SM value or much more exciting with squarks masses ~10 TeV Non-SM expectations in Bs box diagram from Bs J/ψ φ Bd K*0µ+µ- deviations in zero point of AFB. Both would be evidence of New Physics beyond limit for direct production. Scenario with no Higgs (and nothing else) is similar for LHCb. 9/19

10 Scenarios A SUSY spectra is discovered ATLAS and CMS might discover a host of new states but many different theory models are possible Bs µ+µ- will set very strict constraints on the Higgs sector of SUSY CP measurements investigate the flavour structure Can help to understand what kind of symmetry suppress the natural FCNC level? Bd K*0µ+µ- will investigate handedness of SUSY couplings 10/19

11 Scenarios Evidence of extra dimensions The Appelquist, Cheng and Dobrescu model gives new flavour couplings, but no new phases Strong effect on Bs µ+µ- from modified Z0 penguins Buras, Springer & Weiler; Nuclear Physics B 660 (2003) Bd K*0 µ+µ- is also sensitive in AFB zero point As no new phases, CP violation measurements will stay at SM values. hep-ph/ v1, Fazio h e SM p 1/R =200 GeV 11/19

12 Scenarios A 4th generation ATLAS/CMS will discover signals compatible with a set of heavier quarks. Satisfy b d: From G Hou b s Vts Vtb Vus Vub Vt svt b Cannot tell triangle from quadrangle Vud Vub Vcs Vcb Vtd Vtb Vcd Vcb b d Vt d Vt b Could show very large effects for CP violation in Bs box Verification of large 2βs hint from Tevatron Still consistent with Bd box Would expect significant effects in Bd K*0µ+µ- as well 12/19

13 Detector Event in vertex detector ~1 m August 24, /19

14 Detector Alignment Time alignment almost finalised for all sub detectors Space alignment in general better that specifications. Example from vertex detector In vertex detector accurate to 20 µm for sensors Expected BX 14/19

15 Detector Beam 450 GeV September 10, /19

16 Upgrade Physics with LHCb There is interesting physics for LHCb across a very wide range of integrated luminosities World best limit for Bs µ+µσ(2βs)=0.06 from Bs J/ψφ σ(afb) = from Bd K*µ+µσ(γ)=3o from tree diagrams σ(φ)=0.02 in Bs φφ Asymmetries in B K*µ+µ ? fb-1 Upgrade 16/19

17 Upgrade Why do we need an upgrade? For many observables 10 fb-1 will not make us reach theoretical limits Excellent opportunities to study the nature of New Physics discovered during first phase of LHC Theory error on SM SUSY models compatible with current data Comparison of CP violation in b s box and penguin processes Bs φφ possible with high precision (~0.01) with 100 fb-1 Experimental error with 100 fb-1 Compare with further studies of Bs J/ψ φ Angular observables in Bd K*0µ+µ 17/19

18 Upgrade Detector upgrade scenario Current detector will be limited by 1 MHz L0 trigger on transverse energy/momentum. Aim first to reach luminosity of 1033 cm-2 s-1 Factor 5 above design Solution is to read out full detector at 40 MHz and perform trigger in software. Mainly require changes to readout electronics and DAQ Possible to finish for 2014 run From physics simulations no fundamental limits discovered up to 1033 cm-2 s-1. To further increase luminosity will require upgrade to all detectors to cope with higher occupancy. 18/19

19 Conclusion Conclusion Flavour physics at the LHC will play a central role in the understanding of any new physics signals LHCb has a physics programme extending through the full range of integrated luminosity achievable Many channels available even if only subset shown here CP violation in Bs φγ, CP angle α, D0 mixing and CP violation, B meson and baryon spectroscopy, Bs φ µ+µ- An upgrade is essential to reach ultimate precision in channels with small theoretical errors Exclusive channels have much to offer in flavour physics 19/19

20 Backup 20/19

21 OT time alignment TDC range = 3 BX Drift time Trigger BX = n 2 BX = n 1 BX = n 45 ns BX = n /19

22 RICH time alignment 22/19

23 Detector Cosmic trigger with calorimeters Trigger on a MIP coincidence ECAL-HCAL Rate around 10 Hz Mostly almost vertical muons Provides time alignment and mapping of problematic cells. 23/19

24 Detector First beam Injection test dumped beam on TED and TDI Particles in the wrong direction for LHCb Not fully on axis In case of TDI intensities of up to 1000 particles per cm2 24/19

25 New Physics effects on flavour physics hep-ph/ /19