The story of cp violation has changed qualitatively in the past two years
This presentation is the property of its rightful owner.
Sponsored Links
1 / 28

The story of CP Violation has changed qualitatively in the past two years. PowerPoint PPT Presentation


  • 52 Views
  • Uploaded on
  • Presentation posted in: General

f CP. f CP. Time-Dependent Particle-Antiparticle Asymmetries in the Neutral B-Meson System Michael D. Sokoloff University of Cincinnati. The story of CP Violation has changed qualitatively in the past two years.

Download Presentation

The story of CP Violation has changed qualitatively in the past two years.

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


The story of cp violation has changed qualitatively in the past two years

fCP

fCP

Time-Dependent Particle-Antiparticle Asymmetries in the Neutral B-Meson SystemMichael D. SokoloffUniversity of Cincinnati

The story of CP Violation has changed qualitatively in the past two years.

Babar and BELLE have observed time-dependent CP violation in neutral B-mesons, in accord with the Standard Model.

The ensemble of these and other results appear to validate the Kobayashi-Maskawa mechanism as the source of CP violation in the electroweak sector.

New Physics may yet be manifest in CP violation measurements to come.

Michael D. Sokoloff


The nature of particle physics

The Nature of Particle Physics

  • Particle physicists study the fundamental constituents of matter and their interactions.

  • Our understanding of these issues is built upon certain fundmental principles

    • The laws of physics are the same everywhere

    • The laws of physics are the same at all times

    • The laws of physics are the same in all inertial reference systems (the special theory of relativity)

    • The laws of physics should describe how the wave function of a system evolves in time (quantum mechanics)

  • These principles do not tell us what types of fundamental particles exist, or how they interact, but they restrict the types of theories that are allowed by Nature.

  • In the past 30 years we have developed a Standard Model of particle phyiscs to describe the electromagnetic, weak nuclear, and strong nuclear interactions of constituents in terms of quantum field theories.

Michael D. Sokoloff


Special relativity

Special Relativity

  • Energy and Momentum

    • Energy and momentum form a four-vector (t,x,y,z). The Lorentz invariant quantity defined by energy and momentum is mass:

    • For the special case when an object is at rest so that its

      momentum is zero

  • When a particle decays in the laboratory, we can measure the energy and momenta of it decay products (its daughter particles), albeit imperfectly.

  • The energy of the parent is exactly the sum of the energies of its daughters. Similarly, each component of the parent’s momentum is the sum of the corresponding components of the daughters’ momenta.

From the reconstructed

energy and momentum of the

candidate parent, we can

calculate its invariant mass.

Michael D. Sokoloff


Classical field theory e m

Classical Field Theory (E&M)

Michael D. Sokoloff


Fields and quanta

Fields and Quanta

  • Electromagnetic fields transfer energy and momentum from one charged particle to another.

  • Electromagnetic energy/momentum is quantized:

    • E = hn ;p = hn/c

  • These quanta are called photons: g

  • In relativistic quantum field theory: Amg

  • To calculate cross-sections and decay rates we use perturbation theory based on Feynman Diagrams:

Michael D. Sokoloff


Strong nuclear interactions of quarks and gluons

The Nobel Prize in Physics 2004

Gross

Politzer

Wilczek

Strong Nuclear Interactions of Quarks and Gluons

Each quark carries one of three strong charges, and each antiquark carries an anticharge. For convenience, we call these colors:

Just as photons are the quanta of EM fields, gluons are the quanta of strong nuclear fields; however, while photons are electrically neutral, gluons carry color-anticolor quantum numbers.

Michael D. Sokoloff


Baryons and mesons

Baryons and Mesons

  • Quarks are never observed as free particles.

    • Baryons consist of three quarks, each with a different color (strong nuclear) charge

      proton =

      neutron =

    • Mesons consist of quark-antiquark pairs with canceling color-anticolor charges

  • Baryons and meson (collectively known as hadrons) have net color charge zero.

  • A Van der Waals-types of strong interaction creates an attractive force which extends a short distance (~ 1 fm) to bind nucleii together.

Michael D. Sokoloff


Weak charged current interactions

Weak Charged Current Interactions

charm decay

neutrino scattering

l

~

l

As a first approximation, the weak charged current interaction couples fermions of the same generation. The Standard Model explain couplings between quark generations in terms of the Cabibbo-Kobayashi-Maskawa (CKM) matirx.

Michael D. Sokoloff


Weak phases in the standard model

b = f1; a = f2; g = f3

Weak Phases in the Standard Model

Michael D. Sokoloff


Elements of macroscopic cp violation

fCP

Elements of Macroscopic CP Violation

Michael D. Sokoloff


Some relevant feynman diagrams

Some Relevant Feynman Diagrams

Michael D. Sokoloff


The pep ii storage ring at slac

The PEP-II Storage Ring at SLAC

Total: 244 fb-1 (Jul 31st 04)

  • PEP-II is SLAC’s e+e-B factory running at the (4S) c.m. energy

  • The (4S) resonance decays to charged and neutral B-anti-B pairs

Michael D. Sokoloff


Babar detector

BaBar Detector

All subsystems crucial for CP analysis

SVT:97% efficiency, 15 mm z hit resolution (inner layers, transverse tracks)

SVT+DCH: (pT)/pT = 0.13 %  pT+ 0.45 %

DIRC: K- separation 4.2  @ 3.0 GeV/c  2.5  @ 4.0 GeV/c

EMC:E/E = 2.3 %E-1/4  1.9 %


The story of cp violation has changed qualitatively in the past two years

Belle Detector

Aerogel Cherenkov cnt.

n=1.015~1.030

SC solenoid

1.5T

3.5GeV e+

CsI(Tl) 16X0

TOF counter

8GeV e-

Tracking + dE/dx

small cell + He/C2H5

m / KL detection

14/15 lyr. RPC+Fe

Si vtx. det.

3 lyr. DSSD


Experimental technique at the 4s resonance

e+e-  (4S)  BB

m-

Flavor tag and vertex reconstruction

K-

Btag

m-

Brec

m+

B0

KS

B0

p+

Coherent L=1 state

p-

Start the Clock

Stop the Clock

Experimental Technique at the (4S) Resonance

Boost: bg= 0.55

(4S)

Exclusive B meson and vertex reconstruction

Michael D. Sokoloff


Identifying fully reconstructed b s

( )

Identifying Fully Reconstructed B’s

For fits, both Belle and Babar characterize signals and backgrounds with PDF’s which utilize Mbc, DE, tagging category, etc.

Michael D. Sokoloff


Tagging errors and finite d t resolution

typical

mistagging & finite time resolution

Tagging Errors and Finite Dt Resolution

perfect

tagging & time resolution

(f-)

(f+)

B0D(*)-p+/ r+/ a1+

Ntagged=23618

Purity=84%

Michael D. Sokoloff


Effective tagging efficiency q q e 1 2w 2

r = estimated tagging dilution

6

hep-ex/020825 v1

Effective Tagging Efficiency QQ=e(1-2w)2

Michael D. Sokoloff


Sin2 b golden sample cc k s and cc k l

sin2b Golden Sample: (cc)KS and (cc)KL

85 x 106 BB evts

2938 events used tomeasure sin2f1

Michael D. Sokoloff


Sin 2 b fit results

CP odd: sin 2f1 = 0.716  0.083

CP even: sin 2f1 = 0.78  0.17

sin(2b) Fit Results

|lf| = 0.948  0.051 (stat)  0.017 (sys) Scss = sin(2f1 ) = 0.759  0.074 (stat)  0.032 (sys)

sin(2f1 ) = 0.719  0.074 (stat)  0.035 (sys)asumming |lf| = 1 (hep-ex/020825, v1)

Summer 2002

Michael D. Sokoloff


Sin 2 b fit results1

|lf| = 0.948  0.051 (stat)  0.017 (syst) Sf = 0.759  0.074 (stat)  0.032 (syst)

}

hf =-1

sin(2b) Fit Results

hf =+1

hf =-1

sin2b = 0.755  0.074

sin2b = 0.723  0.158

sin2b = 0.741  0.067 (stat)  0.034 (sys) with

|lf| = 1

Summer 2002

Michael D. Sokoloff


Golden modes with a lepton tag

Golden modes with a lepton tag

The best of the best!

Ntagged = 220

Purity = 98%

Mistag fraction 3.3%

sDt 20% better than other tag categories

background

Consistent results across mode, data sample, tagging category

sin2b = 0.79  0.11

Michael D. Sokoloff


Standard model comparison

r = r (1-l2/2)

h = h (1-l2/2)

sin2b = 0.722  0.040 (stat)  0.023 (sys)

sin2b = 0.741  0.067 (stat)  0.034 (sys)

sin2f1= 0.728  0.056 (stat)  0.023 (sys)

sin2f1= 0.719  0.074 (stat)  0.035 (sys)

[email protected]: Im(lyK) = 0.725  0.037

Standard Model Comparison

One solution for b is in excellent agreement with measurements of unitarity triangle apex

Method as in Höcker et al,

Eur. Phys.J.C21:225-259,2001

[email protected]: Im(lyK) = 0.734  0.054

Michael D. Sokoloff


Sin2 b from the penguin decay b sss

sin2b from the Penguin Decay bsss

2.4 from s-penguin to sin2 (cc)

2.7 from s-penguin to sin2 (cc)

Michael D. Sokoloff


B pp to measure sin2 a eff

With Penguins (P):

B pp to Measure sin2aeff

No Penguins (Tree only):

mixing

decay

Michael D. Sokoloff


B pp cp asymmetry results

B ppCP Asymmetry Results

Michael D. Sokoloff


B pp cp asymmetry results1

B ppCP Asymmetry Results

PRL 93, 021601 (2004)152M BB pairs

Michael D. Sokoloff


Time dependent cp violation in b decays a summary

Time-Dependent CP Violation in B-DecaysA Summary

Babar and BELLE have observed time-dependent CP violation in neutral B-mesons, in accord with the Standard Model.

[email protected]: Im(lyK) = 0.725  0.037

The ensemble of these and other results appear to validate the Kobayashi-Maskawa mechanism as the source of CP violation in the electroweak sector.

New Physics may yet be manifest in CP violation measurements to come. Lots of experimental work is being done. Several “> 2.5s””” effects are stimulating theoretical work.

Michael D. Sokoloff


  • Login