Oxford Group LHCb and CLEO-c Report

1. Oxford Group LHCb and CLEO-c Report Why flavour physics matters Status of LHC, LHCb and Oxford group RICH activities Physics activities (including CLEO-c) Summary and Outlook Guy Wilkinson, Project Review, 1/10/07

2. Importance of Flavour Physics Flavour physics has been an essential tool in construction of SM: • GIM mechanism → charm • CP Violation → 3 generations • B mixing → heavy top All surprises that predated ‘direct’ discovery! We may assume same story will continue. Precise measurements of low energy observables, eg. B-decays, a priori expected to reveal presence and nature of new physics at TeV scale and beyond. In B physics goal is to look for new sources of CP violation, or deviations from SM in very rare CP conserving processes, eg. BR(Bs→μμ) ‘Flavour facilities’, eg. LHCb, can make similar studies in D decays and search for LFV τ decays – very wide physics programme.

3. A topical example: D mixing Most interesting result in HEP in 2007 was first observation by BaBar and Belle of D mixing (characterised by x=Δm/Γ and y=ΔΓ/2Γ) BaBar Wrong Sign Kπ analysis Combined BaBar/Belle allowed x-y contours Immediate consequences for SUSY, eg. “it the first 2 generations of squark doublets are within reach of LHC, they must be quasi degenerate” Nir, arXiv:0708.1872v1

4. LHC Status Last dipole lowered April 26th this year ! (First was in March 2005) Last official schedule (August ’07) had beam commissioning beginning in May ’08, with then 2 months estimated before first 14 TeV collisions Since then, there have been problems, eg. with shielding bellows in cold interconnects Warm up of sector 7-8 So knock-on delays not unexpected…

5. Interaction point LHCb Status A very full IP8 - installation is very nearly complete & commissioning is underway Interaction point RICH 1 Schematic of what we are looking at (but note the parity transformation) RICH 2

6. Group Status • Faculty: N. Harnew & G. Wilkinson • Dept. Lecturer: J. Libby • Royal Soc Fellow: Malcolm John • Postdocs: R. Muresan & P. Spradlin • Students: A. Powell, S. Brisbane, L. Martin, F. Xing, Philip Hunt and Chris Thomas (joint with RAL) • Electronics, Systems and Software Engineers: I. McArthur, P. Sullivan, S. Topp-Jorgensen • RICH 1 Mechanics : T. Handford, B. Ottewell, R. Senanayake • Grid programmers: A. Soroko

7. Oxford LHCb RICH Activities Oxford group leading player in LHCb RICH since the beginning. Current responsibilities: RICH Project Leader (Neville Harnew) RICH software coordinator (Guy Wilkinson) and activites: • RICH Level-0 Electronics • RICH-1 Mechanics • RICH calibration strategy (with real data)

8. Status of the L0 electronics Oxford’s responsibility is the front-end electronics for the RICH detectors Hybrid Photo-Detectors (HPDs) detect the Cherenkov radiation by detecting photoelectrons on a 32×32pixel detector encapsulated within the detector Schematic of a HPD section silicon detector readout pixel chip 72 mm

9. Level-0 Production & DAQ status 300 boards have been produced and tested in Oxford 242 boards required to equip both RICHes Project finished successfully [on time and within budget] Commissioning is in progress – all RICH2 photon detectors have been successfully read out under HV Final Level-0 experimental control system (ECS) is very well advanced at CERN Sean Brisbane Neville Harnew Jim Libby Phil Sullivan Stig Topp Jorgensen PIXEL anodes Kaptons Level-0 board

10. 6 L0 Readout in Action Testbeam evaluation of 48 HPDs in 60 GeV/c beam with C4F10 radiator. (Beam single particles with composition 80% p, 10% e, 7% K, 3% p)

11. HPD column mounting at CERN RICH 2 Sean Brisbane Andrew Powell Phil Sullivan L0 boards RICH 1 All RICH-1 and RICH-2 ladders are now fully equipped with HPDs and Level-0 boards HPDs

12. RICH1 mechanics Oxford has extensive involvement in RICH1 mechanics project, vital to the collaboration for delivering on time-critical items. Work in collaboration with ICSTM. • Oxford produced final design and supervised construction of the RICH1 gas enclosure. This is now installed in LHCb pit. • Designed mechanical support and lifting rig for gas enclosure. • Designed and constructed mirror installation & storage boxes • Designed and supervised fabrication of upper HPD mounting and rail system. Still underway (until Nov). • Responsible for design and construction of the lower HPD mounting system. Still underway (until Dec). Matthew Brock, Charlie Evans Wing Lau, Brian Ottewell Tony Handford, Rohan Senanayake, Mike Tacon and the workshop team There will be pressure on Drawing Office and Mechanical Workshop time until the end of the year.

13. RICH-1 schematic RICH-1 gas enclosure (installed with mirrors) RICH-1 upper HPD rail system RICH-1 lower HPD mounting system

14. Particle Identification Calibration Id / misid efficiency Using MC truth Using D* events Kaon momentum [GeV/c] Use high statistics D*→D0(Kπ)π sample selected through kinematics alone (RICH unbiased) to calibrate performance of PID Raluca Muresan

15. Oxford and LHCb Physics Im a   Re 1 Oxford has had leading involvement in physics studies of LHCb flag-ship measurements since start of collaboration, and this continues. • CP Working Group Convenor – Guy Wilkinson Involves not just running MC studies on established methods, but developing new strategies to extend ‘physics-reach’ of experiment. At present, tightly-focused and intensive programme in two key areas: 1) Precise measurement of the unitarity triangle γ (LHCb’s raison d’etre ?) [Libby, Harnew, Wilkinson, Powell, Brisbane, Martin] 2) Studies of charm mixing and search for CP violation in the D system. [Wilkinson, Spradlin, Xing, Muresan]

16. 2 → f + → f Oxford LHCb and the UT Angle γ γ is essentially the CP violating phase in b→u transitions. It is very badly known (σ~ 300) from B-factories. A precise measurement of γ is the next big challenge in flavour physics. Oxford LHCb is leading this work. Best way (statistically precise and theoretically clean) to measure γ is through ‘B→DK’ decays. γ Compare rates or kinematical distributions (eg. Dalitz plots) between B+ and B- for cases where f is a final state common to D and Dbar. Eg. KK ππ Ksππ Kπππ KKππ Kππ0 We estimate combined precision of 1-2o possible at LHCb ! Interference term picks out γ, but also CP conserving phase between the D and Dbar decay (or in 3 and 4 body case, phases associated with each intermediate resonance). If we know/can fit this (these), we get γ.

17. B→DK measurements: the fly in the ointment Dalitz plots for D→Ksππ Take B→D(Ksππ)K as example. For γ extraction we need to understand amplitudes and phases contributing to Ksππ decay. Can be modelled and fitted against decays of flavour eigenstates (available at BaBar/LHCb) but at expense of big systematic: σγ (model) ~ 12o (BaBar) No good for LHCb ! Work-around: look for orthogonal information to complement that which comes from flavour-tagged decays. Answer: decays of CP-eigenstates. But these not available at BaBar/LHCb…

18. Oxford LHCb and CLEO-c CLEO is the grand-daddy of flavour physics, with history of achievement dating back over 20 years. Cornell University, Ithaca NY, USA CLEO-c is latest incarnation. Dedicated programme of data-taking at and above the ccbar threshold, to perform studies needed for B physics. CESR Oxford LHCb physicists (with Bristol) have joined CLEO-c in order to measure quantities essential for our γ studies Oxford student (Andrew Powell) on LTA Recently had RRA bid approved by grants panel for postdoc and travel funding to execute our programme

19. CLEO-c: double tagged ψ(3770) events CLEO-c will collect >800 fb-1 at the ψ (3770) DDbar produced in quantum entangled state: Reconstruct one D in decay of interest for γ analysis (eg. Kπππ), & other in CP eigenstate (eg. KK, Ksπ0 …) then CP of other is fixed. Data: K3π vs Kπ Thus we accumulate a clean dataset of CP-tagged decays with which we can constrain amplitudes & phases in multibody D decays, and essentially eliminate limiting systematic error from LHCb γ analysis ! Note: very, very clean !

20. Oxford LHCb and charm physics Oxford first group in LHCb to identify potential and importance of charm physics measurements. (Recognised in RRA award in ‘round before last’) • Bottom line: SM predicts ~ zero CPV ; many NP models don’t. • It has certainly become very topical: observation of mixing this year • by B-factories at very top end of SM expectation. Opens many possibilities. Benchmark analysis: look for oscillatory component in ‘wrong sign’ D→Kπ decays. Oxford pioneering study: • In 1 yr will get >10x sample of both • B-factories integrated over all time • Methods developed for reconstructing • D0 proper time with necessary precision Conclusions: 1) LHCb can measure D mixing parameters (x and y) very precisely – interesting ; 2) LHCb has unprecedented sensitivity to CPV in charm decays and mixing – very interesting.

21. Summary and Outlook • Oxford efforts have been central to getting LHCb RICH • system built and ready for data-taking (continued lab support for • RICH 1 mechanics, DAQ and electronics necessary). • LHCb physics programme is of highest scientific importance. • All measurements will begin in earnest as soon as machine and • detector is commissioned. We do not need LHC ‘1034’ operation. • Oxford in poll position to steer several of most important analyses, • in particular γ measurement and charm studies. • Entry into CLEO-c has allowed us to tackle vital challenges in the • γ analysis prior to arrival of first LHC data. • Finally: discussions underway for LHCb upgrade. Oxford are well • placed to take place in electronics development for new RICH & trigger. We live in exciting times for flavour physics. Appointment of a new academic will ensure Oxford retains its current lead. Optimal timing would be as soon as possible, so to have maximum impact on LHC data analysis.