366 research outputs found
Complex amplitude phase motion in Dalitz plot heavy meson three body decay
We propose a method to determine the phase motion of a complex amplitude in
three body heavy meson decays. We show that the phase variation of a complex
amplitude can be directly revealed through the interference observed in the
Dalitz Plot region where it crosses with a well established resonant state.
This method could be applied to the decays \d3pi and , to
determine whether the low mass states and , suggested by E791,
have phase motions compatible with resonances.Comment: To appear in Physics Letters
Lessons from CLEO and FOCUS Measurements of D0-anti-D0 Mixing Parameters
If the true values of the D0-anti-D0 mixing parameters lie within the one
sigma ranges of recent measurements, then there is strong evidence for a large
width difference, y > 0.01, and large SU(3) breaking effects in strong phases,
\delta > pi/4. These constraints are model independent, and would become
stronger if M_{12}/Gamma_{12} << 1 in the D0-anti-D0 system. The interesting
fact that the FOCUS result cannot be explained by a large mass difference is
not trivial and depends on the small D0-anti-D0 production asymmetry in FOCUS
and the bounds on CP violating effects from CLEO. The large value of \delta
might help explain why y ~ sin^2(theta_c).Comment: 15 pages, harvma
Light quark and charm interplay in the Dalitz-plot analysis of hadronic decays in FOCUS
The potentiality of interpreting the D-meson decay-dynamics has revealed
itself to be strongly dependent on our understanding of the light-meson sector.
The statistics collected by FOCUS is already at a level that manifests
parametrization problems for scalar particles. In this paper the first
application of the K-matrix approach in the charm sector is illustrated and
preliminary results on the D+ and Ds decays to three pions are shown.Comment: 9 pages, 7 figures, Invited talk at the Scalar Meson Worksho
On the scalar nonet lowest in mass
The hypothesis that there exists a nonet of scalars mainly composed of a
valence quark-antiquark pair and mixed according to near singlet-octet
separation : f_0 (980) singlet, a_0^{+,0,-} (980), K^{* +,0}_0 (1430), \bar
K^{* -,0}_0 (1430), f_0 (1500) octet, is put to further tests from the three
body decays D^{\pm}, D_{s}^{\pm} -> PS^{\pm} pi^+ pi^- with PS^{\pm} =
pi^{\pm}, K^{\pm}. The analysis of decay phases supports the singlet nature of
f_0 (980).Comment: Talk (by P.M.) given at the QCD 02 9th International High-Energy
Physics Conference in QuantumChromoDynamics (Montpellier 2-9th July 2002), 4
page
Dalitz plot analysis and branching fraction measurement of D+ and Ds+ -> pi+pi-pi+
Fermilab fixed target experiment E791 obtained a sample of
events of and 848 events of decays. We find respectively and . Using a
coherent amplitude analysis to fit the Dalitz plot of the decay, we find strong evidence for a scalar resonance of mass
MeV/ and width
MeV/, compatible with what is expected for the isoscalar meson
>. The fraction accounts for approximately half of all three-charged-pion
decays of the . From the Dalitz plot analysis of the decay events, we find significant contributions from the channels
, ,
, , and . We also present new
measurement of the masses and widths of the isoscalar resonances and
.Comment: 4 pages, 4 figures, talk presented in BEACH2000, Valencia, Spai
A chiral qbarqbarqq nonet?
We point out that meson spectrum indicates the existence of a degenerate
chiral nonet in the energy region around 1.4 GeV with a slightly inverted
spectrum with respect to a qq nonet. Based on this observation, the
approximately linear rising of the mass of a hadron with the number of
constituent quarks, and the existence of a cuasidegenerate pseudoscalar nonet,
we conjecture the existence of a tetraquark chiral nonet in this energy region
with chiral symmetry implemented directly. We realize this idea in a chiral
model and take into account the mixing of the tetraquark chiral nonet with a
conventional qq nonet. We find that the mass spectrum of mesons below 1.5 GeV
is consistent with this picture. In general, pseudoscalar states arise as
mainly qq states but scalar states turn out to be strong admixtures of qq and
tetraquark states.Comment: 8 pages, 3 figure
Theoretical Summary of the HADRON99 conference
The Constituent Quark Model has provided a remarkable description of the
experimentally observed hadron spectrum but still has no firm theoretical
basis. Attempts to provide a QCD justification discussed at Hadron99 include
QCD Sum Rules, instantons, relativistic potential models and the lattice.
Phenomenological analyses to clarify outstanding problems like the nature of
the scalar and pseudoscalar mesons and the low branching ratio for were presented. New experimental puzzles include the observation of
.Comment: 10 pages, espcrc1.st
Structure of Light Scalar Mesons from D_s and D^0 Non-Leptonic Decays
Non-leptonic D meson decays may provide a reliable testbed for the multiquark
interpretation of light scalar mesons. In this letter we consider D_s decay and
show that a 4-quark f_0(980) meson could induce a decay pattern, which is
forbidden for a q-qbar constituent structure. Experimental tests to probe such
possibilities are within reach in the near future.Comment: 11 pages, 3 figures, minor changes. To appear in Phys. Lett.
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