The use of charge conjugate reactions is implied throughout the paper.
This note constitutes a Letter of Interest to study the physics capabilities of, and to develop an implementation plan for, a neutrino physics program based on a Low-Energy Neutrino Factory at Fermilab providing a ν beam to a detector at the Deep Underground Science and Engineering Laboratory.It has been over ten years since the discovery of neutrino oscillations [1] established the existence of neutrino masses and leptonic mixing. Neutrino oscillations thus provide the first evidence of particle physics beyond the Standard Model. Most of the present neutrino oscillation data are well described by the 3ν mixing model. While a number of the parameters in this model have already been measured, there are several key parameters that are still unknown, namely, the absolute neutrino mass scale, the precise value of the mixing angles, the CP phase δ and hence the presence or absence of observable CP-violation in the neutrino sector. Future measurements of these parameters are crucial to advance our understanding of the origin of neutrino masses and of the nature of flavor in the lepton sector. The ultimate goal of a program to study neutrino oscillations goes beyond a first measurement of parameters, and includes a systematic search for clues about the underlying physics responsible for the tiny neutrino masses, and, hopefully, the origin of the observed flavor structure in the Standard Model, as well as the possible source of the observed matter-antimatter asymmetry in the Universe. To achieve this goal will almost certainly require precision measurements that go well beyond the presently foreseen program.
We present a preliminary measurement of CP-violating asymmetries in fully reconstructed B 0 →D (*)± π ∓ and B 0 →D ± ρ ∓ decays in approximately 110 million Υ (4S) → BB decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. From a maximum likelihood fit to the time-dependent decay distributions we obtain for the CP-violating parameters: a Dπ = −0.032 ± 0.031 (stat.) ± 0.020 (syst.), c Dπ lep = −0.059 ± 0.055 (stat.) ± 0.033 (syst.) on the B 0 →D ± π ∓ sample, a D * π = −0.049 ± 0.031 (stat.) ± 0.020 (syst.), c D * π lep = +0.044 ± 0.054 (stat.) ± 0.033 (syst.) on the B 0 →D * ± π ∓ sample, and a Dρ = −0.005 ± 0.044 (stat.) ± 0.021 (syst.), c Dρ lep = −0.147 ± 0.074 (stat.) ± 0.035 (syst.) on the B 0 →D ± ρ ∓ sample.
The BaBar high energy physics experiment will be in operation at the PEP-II asymmetric e + e − collider in Spring 1999. The primary purpose of the experiment is the investigation of CP violation in the neutral B meson system. The electromagnetic calorimeter forms a central part of the experiment and new techniques are employed in data acquisition and reconstruction software to maximise the capability of this device.The use of a matched digital filter in the feature extraction in the front end electronics is presented. The performance of the filter in the presence of the expected high levels of soft photon background from the machine is evaluated.The high luminosity of the PEP-II machine and the demands on the precision of the calorimeter require reliable software that allows for increased physics capability. BaBar has selected C++ as its primary programming language and object oriented analysis and design as its coding paradigm. The application of this technology to the reconstruction software for the calorimeter is presented. The design of the systems for clustering, cluster division, track matching, particle identification and global calibration is discussed with emphasis on the provisions in the design for increased physics capability as levels of understanding of the detector increase.The CP violating channel B o → J/ΨK o s has been studied in the two lepton, two π 0 final state. The contribution of this channel to the evaluation of the angle sin 2β of the unitarity triangle is compared to that from the charged pion final state. An error of 0.34 on this quantity is expected after 1 year of running at design luminosity.
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