39 research outputs found
Search for CP violation in D0 and D+ decays
A high statistics sample of photoproduced charm particles from the FOCUS
(E831) experiment at Fermilab has been used to search for CP violation in the
Cabibbo suppressed decay modes D+ to K-K+pi+, D0 to K-K+ and D0 to pi-pi+. We
have measured the following CP asymmetry parameters: A_CP(K-K+pi+) = +0.006 +/-
0.011 +/- 0.005, A_CP(K-K+) = -0.001 +/- 0.022 +/- 0.015 and A_CP(pi-pi+) =
+0.048 +/- 0.039 +/- 0.025 where the first error is statistical and the second
error is systematic. These asymmetries are consistent with zero with smaller
errors than previous measurements.Comment: 12 pages, 4 figure
A measurement of lifetime differences in the neutral D-meson system
Using a high statistics sample of photoproduced charm particles from the
FOCUS experiment at Fermilab, we compare the lifetimes of neutral D mesons
decaying via D0 to K- pi+ and K- K+ to measure the lifetime differences between
CP even and CP odd final states. These measurements bear on the phenomenology
of D0 - D0bar mixing. If the D0 to K-pi+ is an equal mixture of CP even and CP
odd eigenstates, we measure yCP = 0.0342 \pm 0.0139 \pm 0.0074.Comment: 15 pages, 5 figure
Evidence for a narrow dip structure at 1.9 GeV/c in diffractive photoproduction
A narrow dip structure has been observed at 1.9 GeV/c in a study of
diffractive photoproduction of the final state performed by the
Fermilab experiment E687.Comment: The data of Figure 6 can be obtained by downloading the raw data file
e687_6pi.txt. v5 (2nov2018): added Fig. 7, the 6 pion energy distribution as
requested by a reade
Measurements of the Sigma_c^0 and Sigma_c^{++} Mass Splittings
Using a high statistics sample of photoproduced charmed particles from the
FOCUS experiment at Fermilab (FNAL-E831), we measure the mass splittings of the
charmed baryons Sigma_c^0 and Sigma_c^{++}. We find M(Sigma_c^0 - Lambda_c^+) =
167.38 +/- 0.21 +/- 0.13 MeV/c^2 and M(Sigma_c^++ - Lambda_c^+) = 167.35 +/-
0.19 +/- 0.12 MeV/c^2 with samples of 362 +/- 36 and 461 +/- 39 events,
respectively. We measure the isospin mass splitting M(Sigma_c^++ - Sigma_c^0)
to be -0.03 +/- 0.28 +/- 0.11 Mev/c^2. The first errors are statistical and the
second are systematic.Comment: 10 pages, 2 figure
Measurement of B(D_s+ -> mu+ nu_mu)/B(D_s+ -> phi mu+ nu_mu) and Determination of the Decay Constant f_{D_s}
We have observed purely-leptonic decays of
from a sample of muonic one prong decay events
detected in the emulsion target of Fermilab experiment E653. Using the yield measured previously in this experiment, we obtain
. In addition, we extract the decay constant .Comment: 15 pages including one figur
A High statistics study of states containing heavy quarks using the wide band photon beam and the E-687 multiparticle spectrometer.
The spectrometer used in Fermilab experiment 687 to study the photoproduction
and decay of charm particles will be upgraded to enable it to accumulate 10**6 fully reconstructed charm particles. The physics will involve high precision studies of the D semileptonic decays, QCD studies of double D events, a measurement of the absolute branching fraction for the D0, searches for the D0 mixing, CP violation, rare and forbidden decays, fully leptonic decays of the D+ and a systematic investigation of charm baryons and their lifetimes
Study of charged hadronic five-body decays of the D+ and Ds+ mesons
Charged hadronic five-body decays of D+ and Ds+ mesons have been studied in the E687 photoproduction experiment at Fermilab. We report the first compelling evidence of the decay mode D+, Ds+ \u2192 pi 12pi 12pi+pi+pi+ and the measurements of the decays D+ \u2192 K 12pi 12pi+pi+pi+, Ds+ \u2192 K 12K+pi 12pi+pi+ and Ds+ \u2192 phi pi 12pi+pi+. An analysis of the D+ \u2192 K 12pi 12pi+pi+pi+ resonance structure is also presente
Measurement of the form factors for the decay D(s)+ → phi mu+ nu
The fermilab high-energy photoproduction experiment E687 provides a sample of approximately 90 events of the decay mode D(s)+\u2192 phi mu+ nu. The ratios of the form factors governing the decay are measured to be Rv=1.8+-0.9+-0.2 and R2= 1.1+-0.8+-0.1, implying a polarization of G1/Gt=1.0+-0.5+-0.1 for the electron decay, consistent with our measurement of the form factor for the decay D+->anti(K0*) mu+ nu
Measurment of the masses and widths of L=1 charmed mesons
We report the measurement of masses and widths of the following L=1 charm mesons by the E687 Collaboration at Fermilab: a D(2)*0 state of mass (width) 2453+-3+-2 (25+-10+-5) MeV/c2 decaying to D+pi-, a D(2)*+ state of mass (width) 2453+-3+-2 (23+-9+-5) MeV/c2 decaying to D0pi+, a D(1)0 state of mass (width) 2422+-2+-2 (15+-8+-4) MeV/c2 decaying to D*+pi-, and a D(s1)+ state of mass 2535.0+-0.6+-1.0 MeV/c2 and width <3.2 MeV/c2 at 90% confidence level, decaying to D*+Ks0 and D(*0)K+