1. Hadron Physics Lecture Week
The LHCb Experiment
Grzegorz Kalicy1) & Christoph Rosenbaum2)
1) GSI, Darmstadt & Goethe Universität Frankfurt
2) Justus Liebig University Giessen
Hadron Physics Lecture Week
July 7-12, 2013

2. Outline Motivation LHCb Detector LHCb Results Conclusion2
Motivation
Flavor Physics - probe for New Physics
LHCb Physics Program
LHCb Detector
Basic Design
Sub Systems
LHCb Tracking System
LHCb Results
Rare decays
CP violation
b-hadron production
Conclusion
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

3. Flavor Physics 3
CP violation (Charge Parity) The antimatter behaves differently then the matter does C - charge conjugation symmetry P - mirror at origin
The 2008 Nobel Prize in Physics awarded to Kobayashi and Maskawa: Predicting three generations of quarks and the broken
Symmetries.
Independent observation by BaBar and Belle in : Measurements consistent with predictions.
LHCb designed to study heavy flavor physics at the LHC: Primary goal is to look for evidence of New Physics in CP violation and rare decays of beauty and charm hadrons.
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

4. Flavor Physics 4
Unitary triangles constructed in according to restrictions coming from different measurements:
CP violation (Charge Parity) The antimatter behaves differently then the matter does C - charge conjugation symmetry P - mirror at origin
The 2008 Nobel Prize in Physics awarded to Kobayashi and Maskawa: Predicting three generations of quarks and the broken
Symmetries.
Independent observation by BaBar and Belle in : Measurements consistent with predictions.
LHCb designed to study heavy flavor physics at the LHC: Primary goal is to look for evidence of New Physics in CP violation and rare decays of beauty and charm hadrons. η ρ η ρ
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

5. The LHCb Physics Program5 b θ1
Search for New Physics (NP):
CP violation: Used to explain matter over antimatter dominance in universe. Current CP-violation data insufficient to explain matter abundance.
Rare decays: Decays that were not studied in BaBar and Bell
due to low statistics can be studied by LHCb with large number of B mesons.
Additional: b and c production studies, spectroscopy, forward electro-weak physics, exotica, etc...
The CP parameters and rare decays are sensitive to physics beyond the Standard Model.
B forward peaked production → LHCb is forward spectrometer. z θ2 b
θ2[rad]
θ1[rad] η2
LHCb
ATLAS
& CMS η1
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

6. The LHCb Detector 6
The main aim of the LHCb detector: Record the decay of B mesons (particles containing b and anti-b quarks).
B mesons and the particles they decay into stay close to the beam line Design of the detector with sub-detectors stacked behind each other like books on a shelf, different from “onion like” design of other LHC experiments.
Beam
Beam
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

7. The LHCb Detector Requirements7
Resolve fast Bs oscillation:
excellent vertex resolution
Background reduction:
Very good impact parameter resolution
Good mass resolution
Good Particle Identification (PID)
Collect high statistics: Efficient trigger for hadronic and leptonic final states.
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

8. The LHCb Detector Sub-systems8
VELO (VErtex LOcator)
Pick out B mesons from the multitude of other particles produced.
RICH (Ring Imaging Cherenkov) Identification of particles like pi, K, p.
Magnet Curvature of charged particle → Momentum measurement.
Tracking system Detection of charged particle trajectories.
Calorimeters PID of particles without electrical charge (γ and n).
Muon system Detection muons – important for many B meson decays.
VErtex LOcator
RICH
Calorimeters
Tracking system
Muon system
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

9. VELO's modules during construction
The LHCb Detector VELO 9
VELO (VErtex LOcator)
Pick out B mesons from the multitude of other particles produced.
42 silicon detector elements Precisely positioned at a distance of just five millimeters from collision point.
Movable silicon elements placed in vacuum Prevents damage from the proton beam during injection and stabilization.
Indirect measurements of B particles Measures the distance between the point where protons collide (and B particles are created) and the point where the B particles decay.
Spatial resolution around 10 μm, up to 4 μm Depends on pitch and projected track angle.
VELO's modules during construction
VErtex LOcator
RICH
Calorimeters
Tracking system
Muon system
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

10. The LHCb Detector Trackers10
Trackers: Detection of charged particle trajectories.
System :
1 tracking station before magnet:
- Trigger Tracker 4 layers of Si-Strips sensors
3 stations after magnet, 4 layers each split into:
- Inner Tracker (Si-sensors)
- Outer Tracker (straw tube)
Silicon technology offers fine spacial resolution: 270,000 readout electrodes can measure the position of a particle to better than 0.05 mm..
Straw Tube technology with raw resolution: 72 separate modules with 256 straw tubes each provides sufficient 0.2 mm resolution for covering large areas with lower particle densities.
Measuring the drift time of the ionization: Used to improve Outer Tracker resolution.
Outer Tracker
Silicon
Tracker
VErtex LOcator
RICH
Calorimeters
Tracking system
Muon system
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

11. Trigger Tracker layers
The LHCb Detector Trackers 11
Trigger Tracker layers
Trackers: Detection of charged particle trajectories.
System :
1 tracking station before magnet:
- Trigger Tracker 4 layers of Si-Strips sensors
3 stations after magnet, 4 layers each split into:
- Inner Tracker (Si-sensors)
- Outer Tracker (straw tube)
Silicon technology offers fine spacial resolution: 270,000 readout electrodes can measure the position of a particle to better than 0.05 mm..
Straw Tube technology with raw resolution: 72 separate modules with 256 straw tubes each provides sufficient 0.2 mm resolution for covering large areas with lower particle densities.
Measuring the drift time of the ionization: Used to improve Outer Tracker resolution.
VErtex LOcator
RICH
Calorimeters
Tracking system
Muon system
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

12. The LHCb Detector Trackers
1212
Trackers: Detection of charged particle trajectories.
System :
1 tracking station before magnet:
- Trigger Tracker 4 layers of Si-Strips sensors
3 stations after magnet, 4 layers each split into:
- Inner Tracker (Si-sensors)
- Outer Tracker (straw tube)
Silicon technology offers fine spacial resolution: 270,000 readout electrodes can measure the position of a particle to better than 0.05 mm..
Straw Tube technology with raw resolution: 72 separate modules with 256 straw tubes each provides sufficient 0.2 mm resolution for covering large areas with lower particle densities.
Measuring the drift time of the ionization: Used to improve Outer Tracker resolution.
Outer Tracker
Silicon
Tracker
VErtex LOcator
RICH
Calorimeters
Tracking system
Muon system
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

13. The LHCb Detector Trackers
Trackers: Detection of charged particle trajectories.
System :
1 tracking station before magnet:
- Trigger Tracker 4 layers of Si-Strips sensors
3 stations after magnet, 4 layers each split into:
- Inner Tracker (Si-sensors)
- Outer Tracker (straw tube)
Silicon technology offers fine spacial resolution: 270,000 readout electrodes can measure the position of a particle to better than 0.05 mm..
Straw Tube technology with raw resolution: 72 separate modules with 256 straw tubes each provides sufficient 0.2 mm resolution for covering large areas with lower particle densities.
Measuring the drift time of the ionization: Used to improve Outer Tracker resolution.
Inner Tracker boxes
VErtex LOcator
RICH
Calorimeters
Tracking system
Muon system
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

14. The LHCb Detector Trackers
1414
Trackers: Detection of charged particle trajectories.
System :
1 tracking station before magnet:
- Trigger Tracker 4 layers of Si-Strips sensors
3 stations after magnet, 4 layers each split into:
- Inner Tracker (Si-sensors)
- Outer Tracker (straw tube)
Silicon technology offers fine spacial resolution: 270,000 readout electrodes can measure the position of a particle to better than 0.05 mm..
Straw Tube technology with raw resolution: 72 separate modules with 256 straw tubes each provides sufficient 0.2 mm resolution for covering large areas with lower particle densities.
Measuring the drift time of the ionization: Used to improve Outer Tracker resolution.
Outer Tracker
Silicon
Tracker
VErtex LOcator
RICH
Calorimeters
Tracking system
Muon system
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

15. The LHCb Detector Trackers15
Outer Tracker modules
Trackers: Detection of charged particle trajectories.
System :
1 tracking station before magnet:
- Trigger Tracker 4 layers of Si-Strips sensors
3 stations after magnet, 4 layers each split into:
- Inner Tracker (Si-sensors)
- Outer Tracker (straw tube)
Silicon technology offers fine spacial resolution: 270,000 readout electrodes can measure the position of a particle to better than 0.05 mm..
Straw Tube technology with raw resolution: 72 separate modules with 256 straw tubes each provides sufficient 0.2 mm resolution for covering large areas with lower particle densities.
Measuring the drift time of the ionization: Used to improve Outer Tracker resolution.
VErtex LOcator
RICH
Calorimeters
Tracking system
Muon system
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

16. The LHCb Detector Tracking16
VELO tracks Useful for primary vertex reconstruction (good IP resolution)
Long tracks Highest quality for physics (good IP & p resolution).
Downstream tracks Needed for efficient Ks finding (good p resolution).
Upstream tracks Lower p, worse p resolution, but useful for RICH1 pattern recognition.
T tracks Useful for RICH2 pattern recognition
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

17. The LHCb Detector RICH 17
RICH (Ring Imaging Cherenkov): Identification of particles like pi, K, p.
Cherenkov effect: Analogy to the bow wave of a boat traveling over water or the sonic boom of an airplane traveling faster than the speed of sound.
Identifying particles: Using dependence of shape of the cone and velocity of the particle together with information from tracking system to determine it's mass and charge.
Two RICH detectors with different gas radiators: RICH-1 set up to detect low momentum particles.
RICH-2 used for the low angle region where there are mostly high momentum particles
484 novel Hybrid Photon Detector (HPDs): 32x32 pixels each measure positions of the emitted Cherenkov photons.
VErtex LOcator
RICH
Calorimeters
Tracking system
Muon system
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

18. The LHCb Detector Calorimeters18
Calorimeters: PID of particles without electrical charge (γ and n).
Calorimeter system layers:
Scintillating Pad Detector (SPD) Determines if particle was charged or neutral.
Pre-Shower Detector (PS) Indicates the electromagnetic character of the particle.
Electromagnetic Calorimeter (ECAL): ‘‘Shashlik’’-type. Measuring the energy of lighter particles (e, γ, NEUTRAL pi).
Hadron Calorimeter (HCAL): Scintillating tiles interspaced with iron plates. Samples the energy of p, n and other particles containing quarks.
Three EMC modules
HCAL structure
VErtex LOcator
RICH
Calorimeters
Tracking system
Muon system
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

19. The LHCb Detector Calorimeters19
Calorimeters: PID of particles without electrical charge (γ and n).
Calorimeter system layers:
Scintillating Pad Detector (SPD) Determines if particle was charged or neutral.
Pre-Shower Detector (PS) Indicates the electromagnetic character of the particle.
Electromagnetic Calorimeter (ECAL): ‘‘Shashlik’’-type. Measuring the energy of lighter particles (e, γ, neutral pi).
Hadron Calorimeter (HCAL): Scintillating tiles interspaced with iron plates. Samples the energy of p, n and other particles containing quarks.
VErtex LOcator
RICH
Calorimeters
Tracking system
Muon system
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

20. The LHCb Detector Muon System20
Five muon stations
Muon system Detection muons – important for many B meson decays.
The system:
Composed of five stations (M1-M5) of rectangular shape.
Coverage: ±300 mrad horizontally ±250 mrad vertically
Optimization for speed: Information must be gathered within 20 ns.
Different readout methods employed 126,000 front-end readout channels provide space point measurements of the tracks, giving a binary (yes/no) information.
VErtex LOcator
RICH
Calorimeters
Tracking system
Muon system
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

21. Results
2121
Few examples:
July 2012 – Evidence for CP violation asymmetry in 3-body charmless B decay.
November 2012/March 2011 – Oscillating charm and beauty (how matter turns into antimatter and back).
November 2012 – First evidence for the B0S→ μμ decay.
April 2013 – First observation of CP violation in the decays of B0S mesons.
Integrated asymmetries over all kinematical
variables of particles in B mesons decays
ARAWCP= (NB- - NB+ )/(NB- + NB+ )
ACP(B±→K±π+π-) = ± ± ±
Significance of 2.8σ
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

22. Results
2222
Few examples:
July 2012 – Evidence for CP violation asymmetry in 3-body charmless B decay.
November 2012/March 2011 – Oscillating charm and beauty (how matter turns into antimatter and back).
November 2012 – First evidence for the B0S→ μμ decay.
April 2013 – First observation of CP violation in the decays of B0S mesons.
Oscillating/mixing charm and beauty – time
dependence exclusion of no mixing hypothesis
with 9.1 sigma.
Look for small changes in the flavour mixture of the
D0 mesons as a function of the decay time.
Mixing appears as a decay-time dependence of the ratio
R between the number reconstructed “wrong-sign”
(D0→K+π-) and “right-sign” (D0→K-π+).
Absence of mixing → R constant.
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

23. Results
2323
Few examples:
July 2012 – Evidence for CP violation asymmetry in 3-body charmless B decay.
November 2012/March 2011 – Oscillating charm and beauty (how matter turns into antimatter and back).
November 2012 – First evidence for the B0S→ μμ decay.
April 2013 – First observation of CP violation in the decays of B0S mesons.
First evidence for the B0s →μμ decay with σ significance of the measurement
Branching Ratio (BR) - The likelihood of particle decaying to a particular mode.
Standard Model prediction of BR = (3.54±0.30)x10- 9
Exp. result of BR: B0s →μμ = ( )x10-9
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

24. Results
2424
Few examples:
July 2012 – Evidence for CP violation asymmetry in 3-body charmless B decay.
November 2012/March 2011 – Oscillating charm and beauty (how matter turns into antimatter and back).
November 2012 – First evidence for the B0S→ μμ decay.
April 2013 – First observation of CP violation in the decays of B0S mesons.
CP violation in the decays of Strange Beauty particles, the B0s mesons in to K and n mesons
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

25. The LHCb Results 25 Many first and world’s best measurements:
First observation of direct CP violation in Bs mesons.
World’s most sensitive measurements of mixing and CPV in b and c hadron decays.
World’s most sensitive measurements of very rare b and c hadron decays.
High statistics allow precise spectroscopic measurements.
High mass EW measurements complement ATLAS & CMS.
B meson decays topology:
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013

26. The LHCb Conclusion 26
With smooth and efficient operation LHCb sustain luminosity higher than designed value.
LHCb detector achievements:
excellent vertex resolution
great tracking performances
robust particle identification
flexible and efficient trigger
Excellent performance of the LHCb detector in has led to several physics results. LHCb has become a “flavour factory” and produced many first and world’s best CP asymmetry measurements in different B decays.
Most of the results is still based on 2011 data. The 2012 data-set is under study.
Upgrade activities launched. (Physics reach will increase sensitivities by up to an order of magnitude)
G. Kalicy & C. Rosenbaum, Hadron Physics Lecture Week - LHCb, July 7-12, 2013