Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Improved Measurement of cal{B}(D^+ --> mu^+ nu) and the Pseudoscalar
  Decay Constant f_{D^+}   We extract a relatively precise value for the decay constant of the D+ meson
by measuring B(D+ -> mu+ nu)=(4.40 +/- 0.66 {+0.09}{-0.12}) x 10^{-4}, using
281 inverse-pb of data taken on the psi(3770) resonance with the CLEO-c
detector. We find fD+=(222.6 +/- 16.7 {+2.8}{-3.4}) MeV, and compare with
current theoretical calculations. We also set a 90% confidence upper limit on
B(D+ -> e+ nu)<2.4 x 10^{-5} which limits contributions from non-standard model
physics.

20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom