Post on 04-Jan-2016
description
Analysis of a D*+ Decay Path and Natural Line Width
Jeff Rodriguez
Mike Sokoloff Rolf Andreassen Carol Fabby
Jeff Rodriguez 204/20/23
Importance of particle physics and general physics research
Spin off technologies- Internet, Computers, Kings Island Answer some simple questions How did the universe come to be? Where is all the anti-matter? Why do objects have mass? What is dark matter and dark energy? Particles, Strings, and Dimensions? The scientist does not study nature because it is useful; he studies it
because he delights in it, and he delights in it because it is beautiful. If nature were not beautiful, it would not be worth knowing, and if nature were not worth knowing, life would not be worth living.- Henri Poincaré.
Jeff Rodriguez 304/20/23
;
advanced software for information-sharing (the World Wide Web), distributed grid-computing and radiation-exposure simulations for space and medical technologies.
accelerators for medical diagnosis, therapies, food-treatment, micro electronics production and energy-generation; radiofrequency power generation
high-field magnets for medical imaging; radiation and imaging detectors for use in pharmaceutical, biological and
materials sciences, medical and security equipment; Novel ‘bionic’ implants A new type of active pixel sensor developed for
the LHC has many applications but the most exciting are retinal implants which have the potential to restore partial sight to the blind.
Hilger Crystals in London had to mass-produce fast-response scintillator crystals for the BaBar experiment, which then allowed the company to supply its products at a price that was attractive to manufacturers of medical imaging equipment.
Importance of particle physics and general physics research
Jeff Rodriguez 404/20/23
BABAR Experiment The goal of the experiment is to study the
violation of charge and parity (CP) symmetry in the decays of B mesons. This violation manifests itself as different behaviour between particles and anti-particles and is the first step to explain the absence of anti-particles in everyday life.
B-factories confirm matter-antimatter asymmetry; leads to 2008 Nobel Prize in Physics
http://www-public.slac.stanford.edu/babar/Nobel2008.htm
Jeff Rodriguez 504/20/23
What is so important about this study?
CP violation? If CP symmetry holds, the decay rate of B mesons and their antiparticles
should be equal. Analysis of secondary particles produced in the BaBar detector showed this was not the case – in the summer of 2002, definitive results were published based on the analysis of 87 million B/B meson-pair events, clearly showing the decay rates were not equal. Consistent results were found by the Belle experiment at the KEK laboratory in Japan.
What about this study?
Jeff Rodriguez 604/20/23
Particle Data Group
D* (2010)+ , D0, and ∆m valuesD* (2010)+ 2008 +/- 3 MeV
D* (2010)+ Width 96 +/-4(stat) +/-22 (syst) keV
D0 1864.84 +/- .17 MeV∆m= m D*+(2010) = m D0 145.421 +/- .01 MeV
D* (2010)+ Decay ModesMode Fraction(Γi /Γ)D0 π + (67.7 +/- 0.5)%D+ π0 (30.7 +/- 0.5)%D+ γ (1.6 +/- 0.4)%
Jeff Rodriguez 704/20/23
Particle Data Group
D0 Decay ModesInclusive Modes Fraction(Γi /Γ) Scale factor
K- anything (54.7 +/- 2.8)% S=1.3
K0 anything +K0 anything (47 +/- 4)%
K+ anything (3.4 +/- 0.4)%
More…..
Why is fraction>100%?
The D0 and D0 bar are the mass eigenstates of the D0 meson( due to mixing). Need to determine proper description of decay mode
Jeff Rodriguez 804/20/23
CLEO Detector @Cornell (CESR)
Although CLEO ran mainly near the Υ(4S) to study B mesons, it was also competitive with experiments designed to study charm hadrons. CLEO was the first experiment to measure the doubly Cabibbo suppressed decay D0→ K+π-,[99] and CLEO performed Dalitz analyses of D0,+ in several decay modes.[100] [101] [102] [103] [104] [105]
CLEO studied the D*(2010)+, making the first measurement of its width and the most precise measurement of the D*-D0 mass difference.[106] CLEO-c made many of the most accurate measurements of D meson branching ratios in inclusive channels,[107][108] μ+νμ, [109] semileptonic decays,[110][111] and hadronic decays. [112][113][114]
These branching fractions are important inputs to B meson measurements at BaBar and Belle. CLEO first observed the purely leptonic decay Ds+→μ+ν,[115] which provided an experimental measure of the decay constant fDs.
CLEO-c made the most precise measurements of fD+[116] and fDs.[117] These decay constants are in turn a key input to the interpretation of other measurements, such as B mixing.[118]
Jeff Rodriguez 904/20/23
K-
e -
Signal Side
Tag Side
D*+
π+
D0
e +
π+
These particles
reach layers of the
detector
Decay being studied (for D*+ natural line width): D*+ D0 π+
D0 K- π+ π0
π0
Note-Decay image altered from Carol Fabby’s analysis
Jeff Rodriguez 1004/20/23
D0 mass vs ∆m
Jeff Rodriguez 1104/20/23
D0 mass distribution.1461>∆m>.1447
What happened to stat boxes?
Jeff Rodriguez 1204/20/23
D0 mass Region Selections
Central Signal Region 1.835-1.855 GeV/c2
Upper Signal Band 1.865-1.885 GeV/c2
Lower Signal Band 1.835-1.855 GeV/c2
Upper Side Band 1.940-1.960 GeV/c2
Lower Side Band 1.760-1.780 GeV/c2
Jeff Rodriguez 1304/20/23
D0 Mass Cuts on ∆m
Jeff Rodriguez 1404/20/23
Tag SVT and Drift Chamber selection
Make requirements on number of hits to have well measured tracks:
Pion SVT OKKaon SVT OKSlow Pion SVT OK
For high quality tracks, good track resolution and to remove background:
Kaon DCH Hits > 20Pion DCH Hits > 20
Jeff Rodriguez 1504/20/23
TagSVT and nDch Cuts
Jeff Rodriguez 1604/20/23
Cabibbo Favored vs. Doubly Cabibbo Suppressed“Right Sign vs. Wrong Sign”
99.7% favored 0.3% favored
Jeff Rodriguez 1704/20/23
Cabibbo Favored vs. Doubly Cabibbo Suppressed“Right Sign vs. Wrong Sign”
Jeff Rodriguez 1804/20/23
π CF(+/+) vs CDS(+/-)
Jeff Rodriguez 1904/20/23
Something here about how the calorimeter picks up 2 photons as a means of determining the detection of pi 0 and thus the probability that a particle detected is a pi 0
Also something about chi2 analysis
Jeff Rodriguez 2004/20/23
Plots of π0 Chi2 probability function
Jeff Rodriguez 2104/20/23
Probability of π0 Chi2 >0.2
Jeff Rodriguez 2204/20/23
Dalitz plot explanation
K- (m1
)
D0(M)
π+(m2
)
π 0 (m3
)
Jeff Rodriguez 2304/20/23
Dalitz plot explanation (cont.)
http://en.wikipedia.org/wiki/Dalitz_plot
http://pdg.lbl.gov/2009/reviews/rpp2009-rev-kinematics.pdf
Dalitz description pge4
Don’t forget invariant mass description
Jeff Rodriguez 2404/20/23
Dalitz Plots of Signal regionNeed extra code to clean up outsides of plot
Jeff Rodriguez 2504/20/23
Dalitz CutsNew code will be needed to determine regions of high cross product m2 rather than using ranges
Jeff Rodriguez 2604/20/23
Kinematic Limits 3-body decay
http://en.wikipedia.org/wiki/Particle_decay http://pdg.lbl.gov/2009/reviews/rpp2009-
rev-kinematics.pdf Put in equations here and description of 3
particle decay Try and calculate angle in lab vs cm and
compare?
Jeff Rodriguez 2704/20/23
P and Energy (lab and CM)
Jeff Rodriguez 2804/20/23
Center of Mass Momentum Cut
Jeff Rodriguez 2904/20/23
Effect of all cuts on ∆m
Jeff Rodriguez 3004/20/23
MC Truth Matching
• Not just verifying the decay mode exists
• Goal: find best match for D0 and check the mode
• “Top down” approach – Find the best match for the D*+, πs,
D0 (verify D*+ D0πs) – Find best match for the D0
daughters – From prev. step you know you have
the D0 – Make the separate categories for
signal mode and bkg
Real D0, Real πs
Real D0, Not πs
Not D0, Real πs
Not D0, Not πs
Zach Huard Presentation on Truth
Jeff Rodriguez 3104/20/23
Example Event - Event 0 /data/huard/05Jul10_MC_MWDstStudy/SP*.root"
Jeff Rodriguez 3204/20/23
Event info