164 research outputs found
Measurement of the CP violating phase βs in B0s → J/ψφ decays
No full textThe CP violating phase βJ/ψφs is measured in decays of B0s → J/ψφ. This measurement uses 5.2 fb-1 of data collected in √—s = 1.96 TeV p̅p collisions at the Fermilab Tevatron with the CDF Run-II detector. CP violation in the B0s-̅B0sbar system is predicted to be very small in the Standard Model. However, several theories beyond the Standard Model allow enhancements to this quantity by heavier, New Physics particles entering second order weak mixing box diagrams. Previous measurements have hinted at a deviation from the Standard Model expectation value for βJ/ψφs with a significance of approximately 2σ. The measurement described in this thesis uses the highest statistics sample available to date in the B0s rightarrow; J/ψφ decay channel, where J/ψ → μ+ μ− and φ → K+K−. Furthermore, it contains several improvements over previous analyses, such as enhanced signal selection, fully calibrated particle ID and flavour tagging, and the inclusion of an additional decay component in the likelihood function. The added decay component considers S-wave states of KK pairs in the B0s → J/ψK+K− channel. The results are presented as 2-dimensional frequentist confidence regions for βJ/ψφs and ΔΓ (the width difference between the B0s mass eigenstates), and as a confidence interval for βJ/ψφs of [0.02,0.52] Ｕ [1.08, 1.55] at the 68 % confidence level. The measurement of the CP violating phase obtained in this thesis is complemented by the world's most precise measurement of the lifetime τs = 1.53 ± 0.025 (stat.) ± 0.012 (syst.) ps and decay width difference ΔΓ = 0.075 ± 0 .035 (stat.) ± 0.01 (syst.) ps−1 of the B0s meson, with the assumption of no CP violation
Lectures in relativistic quantum mechanics: an introductory course for postgraduates in particle physics
No full textThis book is based on a series of lectures taught by the author to all incoming first year Oxford University postgraduates in experimental particle physics. It begins by deriving the Dirac equation and incorporating the electro-magnetic interaction and calculating several bread and butter processes at tree level using the Feynman Stueckelberg approach: Mott scattering, electron-electron scattering, electron-positron scattering, Compton scattering, Bremsstrahlung and electron-positron to muon-anti-muon. The intention is for the student to become fluent in detail with all the steps leading to the calculation of these processes. Every step is motivated using the most basic arguments
Development of a novel Kalman filter and its application to neutrino interaction measurements in next-generation time projection chambers
No full textThe Deep Underground Neutrino Experiment (DUNE) is a next-generation neutrino oscillation experiment designed to achieve new levels of precision in the study of neutrino flavour oscillations. Its primary goals include measuring charge-parity violation in neutrinos and determining the neutrino mass hierarchy. To achieve these objectives, DUNE relies on a near detector complex to constrain systematic uncertainties, including those related to neutrino flux and interaction cross-sections. A key component of the near detector is a high-pressure gas time projection chamber called ND-GAr, whose novel application in neutrino physics enables low tracking thresholds and high precision, critical for addressing systematic uncertainties arising from nuclear effects. A novel momentum reconstruction algorithm, based on the Kalman filter technique, was developed for ND-GAr, facilitating the reconstruction of low energy tracks. This algorithm significantly improves the detector's performance in momentum reconstruction, eliminating bias and achieving a relative momentum resolution of approximately 2.6 % for muons and 5.3 % for protons. Its effectiveness was demonstrated through an evaluation of ND-GAr's performance in applying the transverse kinematic imbalance (TKI) technique. The double transverse kinematic imbalance, δpTT, can be used to isolate neutrino-hydrogen interactions, providing a sample free from nuclear effects. The novel Kalman filter enhances ND-GAr's ability to implement the TKI technique, achieving a δpTT resolution of (11.9 ± 0.7) MeV/c. These improvements will extend ND-GAr's capabilities in studying nuclear effects and will provide stronger support for DUNE's scientific goals
Measurement of the pion charge exchange differential cross section on Argon with the ProtoDUNE-SP detector
No full textThe Deep Underground Neutrino Experiment (DUNE) utilizes Liquid Argon Time Projection Chamber (LArTPC) technology in its pursuit of uncovering the origins of matter. As a crucial prototype for the DUNE far detector (FD) module, ProtoDUNE-SP at CERN Neutrino Platform Facility employs a hadron test beam with a momentum range of 0.3 to 7 GeV/c to study the detector response to particles that could be produced in the neutrino interactions at the DUNE FD. Furthermore, ProtoDUNE-SP is dedicated to testing event reconstruction and performing detector calibration under controlled conditions. Neutral pion reconstruction performance is an important benchmark of the calorimetric and tracking capability of LArTPC, and understanding neutral pion in LArTPC is crucial to characterize backgrounds to oscillation measurements and rare searches. To improve neutral pion reconstruction in LArTPC, a kinematic fitting algorithm is developed, achieving a 12% resolution in neutral pion energy in ProtoDUNE-SP. This enhancement enables the first measurements of the pion-argon charge exchange differential cross-section. By comparing these results with the current model, valuable constraints can be made to improve generator simulations in the future DUNE experiment
B, Lambda{sub b} and charm results from the Tevatron
No full textRecent results on B{sub d}, B{sub u}{sup {+-}}, B{sub s}, {Lambda}{sub b} and Charm hadrons are reported from {approx} 75 pb{sup -1} and {approx} 40 pb{sup -1} of data accumulated at the upgraded CDF and D0 experiments at the Fermilab Tevatron {bar p}-p collider, during Run-II. These include lifetime and mass measurements of B and Charm hadrons, searches for rare decays in charm and B hadrons and CP-violation in Charm decays. Results relevant to CP-violation in B-decays are also reported
Measurement of the lifetime of the B(s)0 meson using the exclusive decay mode B(s)0 ---> J / psi phi
No full textProbing high energy Higgs bosons using H → bb̄ decays in √s = 13 TeV proton-proton collisions at the ATLAS experiment
No full textThis thesis presents a novel study of Higgs boson production using H → bb̄ decays produced with large transverse momentum boosts, with an additional high energy jet in the event, using √s = 13 TeV proton-proton collision data collected by the ATLAS experiment, corresponding to an integrated luminosity of 136 ifb. Higgs boson signal estimates were extracted from candidate jet mass spectra using binned likelihood fits. The Higgs boson signal estimate was probed inclusively using Higgs boson candidate jets with pTjet > 250 GeV. The inclusive Higgs boson production cross-sections were examined in a fiducial region defined by Higgs boson pTH > 450 GeV, and differential bins of pTH = [300, 450] GeV; [450, 650] GeV; [650, 1000] GeV; and > 1000 GeV inclusively. As sensitivity was not sufficient to make statistically significant measurements of the Higgs boson cross-section, in all cases 95% CLs limits were set, including a first-time limit set for Higgs bosons with pTH > 1 TeV, σH (pT > 1 TeV) < 74 fb. A differential Z boson signal measurement was also made under the same conditions and compared to theoretical predictions. All results were found to be consistent with Standard Model predictions. Particular emphasis is given to the development and validation of the analysis fit model
Measurement of the CP violating phase [beta]s in B_s^0 [rightarrow] J/[psi][phi] decays
No full textThe CP violating phase βJ/ψφs is measured in decays of B0s → J/ψφ. This measurement uses 5.2 fb-1 of data collected in √—s = 1.96 TeV p̅p collisions at the Fermilab Tevatron with the CDF Run-II detector. CP violation in the B0s-̅B0sbar system is predicted to be very small in the Standard Model. However, several theories beyond the Standard Model allow enhancements to this quantity by heavier, New Physics particles entering second order weak mixing box diagrams. Previous measurements have hinted at a deviation from the Standard Model expectation value for βJ/ψφs with a significance of approximately 2σ. The measurement described in this thesis uses the highest statistics sample available to date in the B0s rightarrow; J/ψφ decay channel, where J/ψ → μ+ μ− and φ → K+K−. Furthermore, it contains several improvements over previous analyses, such as enhanced signal selection, fully calibrated particle ID and flavour tagging, and the inclusion of an additional decay component in the likelihood function. The added decay component considers S-wave states of KK pairs in the B0s → J/ψK+K− channel. The results are presented as 2-dimensional frequentist confidence regions for βJ/ψφs and ΔΓ (the width difference between the B0s mass eigenstates), and as a confidence interval for βJ/ψφs of [0.02,0.52] Ｕ [1.08, 1.55] at the 68 % confidence level. The measurement of the CP violating phase obtained in this thesis is complemented by the world's most precise measurement of the lifetime τs = 1.53 ± 0.025 (stat.) ± 0.012 (syst.) ps and decay width difference ΔΓ = 0.075 ± 0 .035 (stat.) ± 0.01 (syst.) ps−1 of the B0s meson, with the assumption of no CP violation.This thesis is not currently available in OR
Lattice models with interactions on Caylay tree
No full textWe consider an Ising competitive model defined over a triangular Husimi tree where loops,
responsible for an explicit frustration, are even allowed. We first analyze the phase diagram of the model
with fixed couplings in which a “gas of noninteracting dimmers (or spin liquid) — ferro or
antiferromagnetic ordered state” zero temperature transition is recognized in the frustrated regions. Then
we introduce the disorder for studying the spin glass version of the model: the triangular ±J model. We
find out that, for any finite value of the averaged couplings, the model exhibits always a finite temperature
phase transition even in the frustrated regions, where the transition turns out to be a glassy transition. On
the other hand, In this investigation we studied one-dimensional countable state p-adic Potts model. We
prove the existence of generalized p-adic Gibbs measures for the given model. It is also shown that under
the condition there may occur a phase transition
ش- فرخ کا "آواگون " علامتی طرز کا منفرد سفر نامہ : ایک مطالعہ: A STUDY OF SHEEN FARRUKH'S "AAWAGON" A UNIQUE TRAVELOGUE OF SYMBOLIC STYLE
No full textSheen Farrukh is one of the famous and important Urdu Journalists, Novelist Autobiographers and Travelogues. She was born in Gujranwala in 1938. She obtained her master degree in Geography (1959) from University of the Panjab, (Lahore). After completion, she joined Journalism and worked with Akhbar-i-Khawateen, and urdu magazine for the period as a journalist and remaind with it till retirement. She was editor Inter Press Communication University of the Panjab, member Karachi press, Arts council of Pakistan, Women Action Forum. She was the author of many books, like a biographical noval on artist Ali Imran madaar and an autobiographical book Jeen ka Jurm two Travelogue “Nai dunya purani dunia and Secondly” Awagon. Sheen Farrukh passed away in Karachi on Thursday, 2021. She was 83.  
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