~1 m

RICH1 RICH2

LHC-b Experiment RICH2 RICH1

Tree T Penguin P

Bd -> +

Bs -> DsK

Rutherford Appleton Laboratory

Unitarity Triangles

VELO

Particle Identificationwith RICH detectors

• Rate asymmetries measure angle

• Expect 2400 events in 1 year of data taking

• LHCb is a 2nd generation experiment that will determine CP violations in a variety of decays of Bd and Bs mesons to test consistency of Unitarity Triangles.

• It will follow on from Babar, BELLE that have already established CP violations for Bd mesons (in the decay Bd -> J/ K) and will constrain unitarity triangles to unprecedented accuracy.

• LHC is the most intense source of B mesons (Bd, Bu, Bs, Bc) with bb = 500 mb

• Luminosity <L>LHCb = 2 x1032 cm-2 s-1 1012 bb / 107 s

• Range of channels available in LHCb:

Parameter Channels Evts/year (1 year) LHCb feature

2(+) Bd 4900

|P/T| = 0 2-5 PID, hadron trigger

Bd ~1300 3-6 PID, hadron trigger

2+ Bd D 340000 > 11 PID, hadron trigger

BdJ/Ks 37000 0.6

-2 Bs DsK2400 6-14 PID, hadron trigger, t

Bd DK 400 10 PID, hadron trigger

Bs J/ 44000 0.6 t

Bs oscillations

xs Bs Ds120000 up to 75 hadron trigger, t

Rare Decays

BR Bs <210-9 t

Bd K 22400 PID

C4F10

C4F10

+CF4

CF4

Aerogel

-K separation

Number of silicon sensors: 100 Area of silicon: 0.32m2

Number of channels: 204,800

Number of silicon sensors: 100 Area of silicon: 0.32m2

Number of channels: 204,800

Vertex Locator (VELO)

UK Contributions to LHCb vital for LHCb physics:• RICH detectors• Vertex Locator (VELO)

Physics aims:

• sensitive to CKM angle

~ 20 - 50 in 1 year

–depends on |P/T| and strong phase

• Backgrounds also have

Expected physics results: