arXiv subjects
Publications and source records attributed to Peter S. Cooper.
If the cosmological limits on the sum of the neutrino masses are taken seriously we have first measurements of the masses of the neutrinos. Using the Planck experiment's limit $\sum_{i=1}^3{m_i} < 230 ~meV$ and some simple assumptions on measurement uncertainties the mass of the heaviest neutrino is $63\pm11 ~meV$ and the lightest $40\pm18 ~meV$ for either hierarchy.
Charged lepton flavor violation (CLFV) is a clear signal of new physics; it directly addresses the physics of flavor and of generations. The search for CLFV has continued from the early 1940's, when the muon was identified as a separate particle, until today. Certainly in the LHC era the motivations for continued searches are clear and have been covered in many reviews. This review is focused on the experimental history with a view toward how these searches might progress. We examine of the status of searches for charged lepton flavor violation in the muon, tau, and other channels, and then examine the prospects for new efforts over the next decade. Finally, we examine what paths might be taken after the conclusion of upcoming experiments and what facilities might be required.
The Selex experiment measured several billion charged hadron tracks with a high precision magnetic momentum spectrometer and high precision RICH velocity spectrometer. We have analyzed these data to simultaneously measure the masses of all the long lived charged hadrons and anti-hadrons from the pi to the Omega using the same detector and technique. The statistical precision achievable with this data sample is more than adequate for 0.1% mass measurements We have used these measurements to develop and understand the systematic effects of a RICH as a precision velocity spectrometer with the goal of measuring 10 masses with precision ranging from 100 KeV for the lightest to 1000 KeV for the heaviest. This requires controlling the radius measurement of RICH rings to the ~10^{-4} level. Progress in the mass measurements and the required RICH analysis techniques developed are discussed.
Data from the power output of the radioisotope thermoelectric generators aboard the Cassini spacecraft are used to test the conjecture that small deviations observed in terrestrial measurements of the exponential radioactive decay law are correlated with the Earth-Sun distance. No significant deviations from exponential decay are observed over a range of 0.7 - 1.6 A.U. A 90% Cl upper limit of 0.84 x 10^-4 is set on a term in the decay rate of Pu-238 proportional to 1/R^2 and 0.99 x 10^-4 for a term proportional to 1/R.
We report the first observation of a charm-strange meson D_sJ(2632) at a mass of 2632.5+/-1.7 MeV/c^2 in data from SELEX, the charm hadro-production experiment E781 at Fermilab. This state is seen in two decay modes, D_s eta and D^0 K^+. In the D_s eta decay mode we observe a peak with 101 events over a combinatoric background of 54.9 events at a mass of 2635.4+/-3.3 MeV/c^2. There is a corresponding peak of 21 events over a background of 6.9 at 2631.5+/-2.0 MeV/c^2 in the decay mode D^0 K^+. The relative branching ratio Gamma(D^0 K^+)/Γ(D_s eta) is 0.14+/-0.06. The full version of this paper has been accepted for publication in PRL (hep-ex/0406045). Here I have reproduced only the mass difference signal plots for the D_s eta and D^0 K^+ decay modes.
This document is an abridgement of the commemorative book prepared on the occasion of the symposium "In Celebration of the Fixed Target Program with the Tevatron" held at Fermilab on June 2, 2000. The full text with graphics contains, in addition to the material here, a section for each experiment including a "plain text" description, lists of all physics publications, lists of all degree recipients and a photo from the archives. The full text is available on the web at: http://conferences.fnal.gov/tevft/book/
It is usually assumed that the production of baryons in $B$ meson decays is induced primarily by the quark level process $b\to c\bar ud$, where the charm quark hadronizes into a charmed baryon. With this assumption, the $Λ_c$ momentum spectrum would indicate that the transition $B\toΛ_c X$ is dominated by multi-body $B$ decays. However, a closer examination of the momentum spectrum reveals that the mass $m_X$ against which the $Λ_c$ is recoiling almost always satisfies $m_X\agt m_{Ξ_c}$. This fact leads us to examine the hypothesis that the production of charmed baryons in $B$ decays is in fact dominated by the underlying transition $b\to c\bar cs$, and is seen primarily in modes with two charmed baryons in the final state. We propose a number of tests of this hypothesis. If this mechanism is indeed important in baryon production, then there are interesting consequences and applications, including potentially important implications for the ``charm deficit'' in $B$ decays.