742 research outputs found
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 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
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