March 2000The First Data from BELLE1 First Data from BELLE HEP Seminar University of Chicago Daniel Marlow Princeton University March 13, 2000

March 2000The First Data from BELLE2 Physics Motivation Direct CP violation is perhaps the simplest case. Consider the CP mirror processes: The CP asymmetry is defined as The decay amplitudes are Note that the weak phase changes sign.

March 2000The First Data from BELLE3 Direct CP Violation Note that Yielding We need some sort of interference, two amplitudes, for example

March 2000The First Data from BELLE4 Direct CP Violation Despite its conceptual and experimental simplicity, there are two problems with direct CP violation: Cases where there are two comparable amplitudes that are large are (probably) rare. The strong phases are poorly understood, making it difficult to extract the weak (KM) phases that are of greatest interest. This leads one in the direction of asymmetric B factories aimed at the study of indirect CP violation.

March 2000The First Data from BELLE5 Indirect CP Violation In this approach we provide the interference using state mixing, i.e.,

March 2000The First Data from BELLE6 Indirect CP Violation Thus for a decay where is a CP eigenstate, we have two “indistinguishable” decay paths Working through the algebra, yields a time- dependent CP asymmetry Where and are the weak phases for the mixing and decay diagrams, respectively and

March 2000The First Data from BELLE7 The Kobayashi-Maskawa Mixing Scheme Where the second matrix is the Wolfenstein parameterization. Quark mixing is described via The “d b” unitarity relation yields

March 2000The First Data from BELLE8 CP Phases in the Gold-Plated Mode Decay Mixing The KM phase comes from the mixing.

March 2000The First Data from BELLE9 The Unitarity Triangle The gold-plated mode determines the angle which is also called.

March 2000The First Data from BELLE10 Existing Constraints Existing measurements of mixing and limit the allowed region in the plane. F. Parodi et al.

March 2000The First Data from BELLE11 The Measurement tag CP Need to: Measure momenta ID leptons & K’s Measure vertices

March 2000The First Data from BELLE12 The Measurement The time-dependent asymmetry appears mainly as a mean shift in the distribution between events tagged as decays and events tagged as decays.

March 2000The First Data from BELLE13 The KEK-B Asymmetric Collider KEK-B is similar to PEP- II in many ways, although there is a (potentially) important difference in the way in which the beams are brought into collision.

March 2000The First Data from BELLE14 Beam Crossing Schemes By colliding the beams at an angle, the KEK-B design achieves a simplified interaction region. Moreover, every RF bucket (2 ns spacing) can be filled to achieve maximum luminosity. However, this approach risks destabilizing couplings between transverse and longitudinal modes of the machines. A crab-crossing cavity is under development in case this proves to be a problem.

March 2000The First Data from BELLE15 Linac Parameters

March 2000The First Data from BELLE16 Ring Parameters

March 2000The First Data from BELLE17 The Storage Rings RF Cavity Stations

March 2000The First Data from BELLE18 Recent Run Snapshot

March 2000The First Data from BELLE19 The Magnet

March 2000The First Data from BELLE20 About 10 Countries, 50 Institutes, & 200 People The BELLE Collaboration

March 2000The First Data from BELLE21 Key Belle Milestones Early 1990’s - Japanese groups begin working. January Collaboration forms. April TDR Submitted. …lots of work by lots of people in lots of places... Dec 18, Belle detector completed (including SVD) Jan 26, First cosmic ray with full detector. May 1, Belle rolled into place. June 1, First hadronic event!!!!! June 1999/July 1999 first serious running

March 2000The First Data from BELLE22 June 1, 1999: Our First Hadronic Event

March 2000The First Data from BELLE23 More Fun: SVD Included

March 2000The First Data from BELLE24 First J/  Candidate J/  ee – M(ee) = 3.1 GeV

March 2000The First Data from BELLE25 Luminosity vs Time Profile The KEK-B team has recovered at least part of the one-year schedule lag that they once had with respect to PEP-II.

March 2000The First Data from BELLE26 The Silicon Vertex Detector

March 2000The First Data from BELLE27 SVD Performance

March 2000The First Data from BELLE28 SVD Performance Bhabha miss distance

March 2000The First Data from BELLE29 SVD Performance

March 2000The First Data from BELLE30 SVD Tomography X-Z distribution of primary vertices for all triggers, including beam gas. The IP, the beam crossing angle, and various flanges etc in the IR are clearly evident.

March 2000The First Data from BELLE31 CDC Performance

March 2000The First Data from BELLE32 CDC Performance (Cosmic Rays)

March 2000The First Data from BELLE33 Particle ID (dE/dx, ToF, & Aerogel)

March 2000The First Data from BELLE34 Particle ID (dE/dx, ToF, & Aerogel)

March 2000The First Data from BELLE35 CsI EM Calorimeter Performance

March 2000The First Data from BELLE36 More CsI

March 2000The First Data from BELLE37 Electron ID

March 2000The First Data from BELLE38 K_L Muon Detector The muon detectors, which are the largest, are made from standard soda-lime float glass (window glass). An endcap module is installed.

March 2000The First Data from BELLE39 Muon Detection Note that there are no missing hits in the layers of the muon system, except at the locations.

March 2000The First Data from BELLE40 Detection First ~1000 hadronic events.

March 2000The First Data from BELLE41 Energy Scan

March 2000The First Data from BELLE42 Unstable Particles

March 2000The First Data from BELLE43 Unstable Particles Impossible without PID

March 2000The First Data from BELLE44 A “Typical” Dimuon event J/  – M(  ) = 3.1 GeV –both muons tracks clearly evident in magnet return yoke This event is consistent with although there were no hits in the RPCs

March 2000The First Data from BELLE45 Lepton-pair Spectra

March 2000The First Data from BELLE46 candidate

March 2000The First Data from BELLE47 candidate

March 2000The First Data from BELLE48 Charm Lifetimes

March 2000The First Data from BELLE49 Charm Lifetimes

March 2000The First Data from BELLE50 Lifetimes

March 2000The First Data from BELLE51 Lifetimes

March 2000The First Data from BELLE52 D Mass Plots 0 w/o D cut * with D cut *

March 2000The First Data from BELLE53 D Lifetimes 0

March 2000The First Data from BELLE54 Charmed Baryon

March 2000The First Data from BELLE55 Combined Di-lepton Spectrum

March 2000The First Data from BELLE56 Exclusive Mode Reconstruction

March 2000The First Data from BELLE57 Exclusive Mode Reconstruction

March 2000The First Data from BELLE58 Neutral B Mixing

March 2000The First Data from BELLE59 Conclusions & Outlook We have acquired about 600/pb of data, a tiny fraction of the 100/fb that is our Phase-I goal, but a good start nonetheless. The KEK-B accelerator is working with luminosity of almost The entire Belle detector, including the DAQ and offline reconstruction software, is working well. We continue in a constant struggle to increase the luminosity while fighting background.

March 2000The First Data from BELLE60