A High-Precision Measurement of the Di-Electron Widths of the Upsilon(1S), Upsilon(2S), and Upsilon(3S) Mesons at CLEO-III

The di-electron width of an Upsilon meson is the decay rate of the Upsilon into an electron-positron pair, expressed in units of energy. We measure the di-electron width of the Upsilon(1S) meson to be 1.354 +- 0.004 +- 0.020 keV (the first uncertainty is statistical and the second is systematic), the di-electron width of the Upsilon(2S) to be 0.619 +- 0.004 +- 0.010 keV and that of the Upsilon(3S) to be 0.446 +- 0.004 +- 0.007 keV. We determine these values with better than 2% precision by integrating the Upsilon production cross-section from electron-positron collisions over their collision energy. Our incident electrons and positrons were accelerated and collided in the Cornell Electron Storage Ring, and the Upsilon decay products were observed by the CLEO-III detector. The di-electron widths probe the wavefunctions of the Strongly-interacting bottom quarks that constitute the three Upsilon mesons, information which is especially interesting to check high-precision Lattice QCD calculations of the nuclear Strong force.Comment: 160 pages, 73 figures, Ph.D. dissertation, also available through http://www.lepp.cornell.edu/public/THESIS/2006/ and http://hdl.handle.net/1813/2672, see hep-ex/0512056; corrected numerical values in abstrac

Potential of the Julia programming language for high energy physics computing

Research in high energy physics (HEP) requires huge amounts of computing and storage, putting strong constraints on the code speed and resource usage. To meet these requirements, a compiled high-performance language is typically used; while for physicists, who focus on the application when developing the code, better research productivity pleads for a high-level programming language. A popular approach consists of combining Python, used for the high-level interface, and C++, used for the computing intensive part of the code. A more convenient and efficient approach would be to use a language that provides both high-level programming and high-performance. The Julia programming language, developed at MIT especially to allow the use of a single language in research activities, has followed this path. In this paper the applicability of using the Julia language for HEP research is explored, covering the different aspects that are important for HEP code development: runtime performance, handling of large projects, interface with legacy code, distributed computing, training, and ease of programming. The study shows that the HEP community would benefit from a large scale adoption of this programming language. The HEP-specific foundation libraries that would need to be consolidated are identifiedComment: 32 pages, 5 figures, 4 table

Measurement of the Decay Constant fDS+f_D{_S^+} using $D_S^+ --> ell^+ nu

We measure the decay constant fDs using the Ds -> l+ nu channel, where the l+ designates either a mu+ or a tau+, when the tau+ -> pi+ nu. Using both measurements we find fDs = 274 +-13 +- 7 MeV. Combining with our previous determination of fD+, we compute the ratio fDs/fD+ = 1.23 +- 0.11 +- 0.04. We compare with theoretical estimates.Comment: 6 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2007

Measurement of Interfering K^*+K^- and K^*-K^+ Amplitudes in the Decay D^0 --> K^+K^-pi^0

We have studied the Cabibbo-suppressed decay mode D^0 into K^+ K^- pi^0 using a Dalitz plot technique and find the strong phase difference delta_D [defined as delta_(K*^- K^+) - delta_(K*^+ K^-)] = 332 degrees +- 8 degrees +- 11 degrees and relative amplitude r_D [defined as a_(K*^- K^+) / a_(K*^+ K^-)] = 0.52 +- 0.05 +- 0.04. This measurement indicates significant destructive interference between D^0 into K^+ (K^- pi^0)_K*^- and D^0 into K^- (K^+ pi^0)_K*^+ in the Dalitz plot region where these two modes overlap. This analysis uses 9.0 fb^(-1) of data collected at s^(1/2) of approximately 10.58 GeV with the CLEO III detector.Comment: 10 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2006/, Submitted to Phys. Rev. D (Rapid Communications

Confirmation of the Y(4260) Resonance Production in ISR

Using 13.3 fb^-1 of e+e- collision data taken in the Upsilon(1S-4S) region with the CLEO III detector at the CESR collider, a search has been made for the new resonance Y(4260) recently reported by the BaBar Collaboration. The production of Y(4260) in initial state radiation (ISR), and its decay into pi+pi-J/psi are confirmed. A good quality fit to our data is obtained with a single resonance. We determine M(Y(4260))=(4284+17-16(stat)+-4(syst)) MeV/c^2, Gamma(Y(4260))=(73+39-25(stat)+-5(syst)) MeV/c^2, and Gamma_ee(Y(4260))xBr(Y(4260)->pi+pi-J/psi)=(8.9+3.9-3.1(stat)+-1.9(syst)) eV/c^2.Comment: 8 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2006/, Submitted to PRD (Rapid Comm.

Absolute Branching Fraction Measurements for D^+ and D^0 Inclusive Semileptonic Decays

We present measurements of the inclusive branching fractions for the decays D^+ -> X e^+ nu_e and D^0 -> X e^+ nu_e, using 281 pb^-1 of data collected on the psi(3770) resonance with the CLEO-c detector. We find Br(D^0 ->Xe^+\nu_e) = (6.46 \pm 0.17 \pm 0.13)% and Br((D^+ -> Xe^+nu_e) = (16.13 \pm 0.20 \pm 0.33)%. Using the known D meson lifetimes, we obtain the ratio Gamma{D^+}^sl/Gamma_{D^0}^sl= 0.985\pm 0.028\pm 0.015, confirming isospin invariance at the level of 3%. The positron momentum spectra from D^+ and D^0 have consistent shapes.Comment: 6 pages postscript,also available through this http://www.lns.cornell.edu/public/CLNS/2006

Search for psi(2S)--> eta_c pi^+ pi^- pi^0

Using 5.63 pb^-1 of data accumulated at the psi(2S) resonance with the CLEO III and CLEO-c detectors corresponding to 3.08 million psi(2S) decays, a search is performed for the decay psi(2S) -> eta_c pi^+pi^-pi^0 to test a theoretical prediction based upon the assumption that the c \bar c pair in the psi(2S) does not annihilate directly into three gluons but rather survives before annihilating. No signal is observed, and a combined upper limit from six eta_c decay modes is determined to be B(psi(2S) -> eta_c pi^+pi^-pi^0) < 1.0 x 10^-3 at 90% C.L. This upper limit is about an order of magnitude below the theoretical expectation.Comment: 8 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2006