Search for CPT Violation with the FOCUS Experiment and Measurement of $Λ_b$ lifetime in the decay $Λ_b\to J/ψΛ$ with the DØ Experiment

1.6 MB·English

by  Abaz Kryemadhi

5 Search for CPT Violation with the FOCUS
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0 Experiment and Measurement of Λ lifetime in the
2 b
decay Λ J/ψΛ with the DØ Experiment
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Abaz Kryemadhi
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e
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e Submitted to the faculty of the Graduate School
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v: in partial fulfillment of the requirements
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X for the degree
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a Doctor of Philosophy
in the Department of Physics,
Indiana University
December, 2004
Accepted by the Graduate Faculty, Indiana University, in partial fulfillment
of the requirements of the degree of Doctor of Philosophy.
Doctoral Professor Rick Van Kooten
Committee (Chairman)
Professor Alan Kostelecky´
Professor Harold Ogren
December 7, 2004 Professor Steven Gottlieb
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Copyright c 2008
(cid:13)
Abaz Kryemadhi
ALL RIGHTS RESERVED
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To God: Who created so much beauty in the universe for us to study.
”The heavens declare the glory of God; the skies proclaim the work of his hands”.
Psalm 19:1
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Acknowledgments
First of all, my deepest gratitude goes to my advisors, Dr. Rick Van Kooten and Dr. Rob
Gardner. Throughout the years of my Ph.D. study, they were always willing to mentor,
encourage, and support me. Their expertise and enthusiasm in the field of high energy
physics, as well as their uniqueinsightfulway of approaching problems,are among the most
valuable resources for me.
I would like to thank Dr. Alan Kostelecky´ for his explanations of the CPT and Lorentz
Violation framework and also for his comments and suggestions during the process of pub-
lishing the CPT paper, which has been used in this thesis.
I would like to thank Dr. Fred Luehring for his suggestions when I have been at cross-
roads in my career and his help with some computer software. Along the same lines I would
like to thank Thom Sulanke for his help at solving a lot of technical questions.
I would like to thank people from the FOCUS Collaboration, in particular Jim Wiss,
Gianluigi Boca, Topher Cowfield, John Link, Eric Vaandering, Kevin Stenson and Harry
Cheung for their continual help with any question that I had, and also for their input on
making the first part of this thesis possible.
I would like to thank Indiana University DØ group, in particular Daria Zieminska and
AndrzejZieminskifortheusufuldisscussionsandsuggestions duringourIndianaUniversity
DØ group meetings.
I would like to thank people from the B-Physics group at DØ in particular Vivek Jain,
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Brad Abbott, Rick Jessik, Guenadi Borisov, Andrei Nomerotski, Sergey Burdin for their
continual help with any question that I had, and also for their input on making the second
part of this thesis possible.
IwouldliketothankfriendsinthePhysicsDepartment,MaciejSwat,PrabudhaChakraboty,
Jundong Huang and Chunhui Luo for the great physics discussions we have had and also
for their friendship.
Finally I would like to thank my beautiful fianc´ee Ilse Friberg and my parents Avni
and Fatmire Kryemadhi for their encouragement and support in the process of making this
thesis happen,they have beenhappyfor my achievements andpatient withmy frustrations.
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Abstract
This dissertation describes two different projects from two different experiments. We
have performed a search for CPT violation in neutral charm meson oscillations using data
from the FOCUS Experiment. While flavor mixing in the charm sector is predicted to
be small in the Standard Model, it is still possible to investigate CPT violation through
a study of the proper time dependence of a CPT asymmetry in right-sign decay rates
for D0 K−π+ and D¯0 K+π−. This asymmetry is related to the CPT violating
→ →
complex parameter ξ and the mixing parameters x and y: A Reξy Imξx. We
CPT
∝ −
determine a 95% confidence level limit of 0.0068 < Reξy Imξx < 0.0234. Within the
− −
framework of the Standard Model Extension incorporating general CPT violation, we also
find95% confidencelevel limitsfortheexpressionsinvolving coefficients ofLorentzviolation
of ( 2.8 < N(x,y,δ)(∆a + 0.6∆a ) < 4.8) 10−16 GeV, ( 7.0 < N(x,y,δ)∆a <
0 Z X
− × −
3.8) 10−16 GeV, and ( 7.0 < N(x,y,δ)∆a < 3.8) 10−16 GeV, where N(x,y,δ) is
Y
× − ×
a normalization factor that incorporates mixing parameters x, y and the doubly Cabibbo
suppressed to Cabibbo favored relative strong phase δ.
WealsopresentmeasurementsoftheΛ0lifetimeintheexclusivedecaychannelΛ0 J/ψΛ
b b →
with J/ψ µ+µ− and Λ pπ−, the B0 lifetime in the decay B0 J/ψK0 with J/ψ
→ → d → S →
µ+µ− and K0 π+π−, and the ratio of these lifetimes. The analysis is based on approxi-
S →
mately 225 pb−1 of data recorded with the DØ detector in pp¯collisions at √s = 1.96 TeV.
The Λ0 lifetime is determined to be τ(Λ0) = 1.36 0.30 (stat) 0.07(syst) ps, the B0
b b ± ±
lifetime τ(B ) = 1.43 0.12 (stat) 0.04 (syst) ps, and the ratio τ(Λb) = 0.95 0.22 0.05.
d ± ± τ(Bd) ± ±
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In contrast with previous measurements using semileptonic decays, this is the first deter-
mination of the Λ0 lifetime based on a fully reconstructed decay channel.
b
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Contents
Acknowledgments v
Abstract vii
1 The Standard Model of Particle Physics 1
1.1 The Fundamental Particles . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 The Fundamental Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Lagrangians . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 CPT Formalism 7
2.1 Mixing Formalism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Proper Time Asymmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3 Double Cabbibo Suppressed Interference . . . . . . . . . . . . . . . . . . . . 13
2.4 Lorentz Violating Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.5 Sidereal Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.6 Previous Searches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
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3 The E831/FOCUS Experiment at Fermilab 20
3.1 Physics Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.2 The Accelerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.3 The Photon Beam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.4 The Spectrometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.4.1 Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.4.2 Particle Identification . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.4.3 Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.5 Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4 Data Analysis 38
4.1 Analysis Aproach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.2 Analysis Cuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.3 Results for the Asymmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.4 Results for Coefficients of Lorentz Violation . . . . . . . . . . . . . . . . . . 45
4.5 Monte Carlo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.6 Systematic Uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
5 Conclusions 52
6 Introduction to Λ0 55
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7 Theory Predictions 59
7.1 Spectator Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
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