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/c2^2 in 3π+3π−3\pi^+ 3\pi^- diffractive photoproduction

A narrow dip structure has been observed at 1.9 GeV/c$^2$ in a study of diffractive photoproduction of the $~3\pi^+3\pi^-$ 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 $23.2 \pm 6.0_{-0.9}^{+1.0}$ purely-leptonic decays of $D_s^+ -> \mu^+ \nu_\mu$ from a sample of muonic one prong decay events detected in the emulsion target of Fermilab experiment E653. Using the $D_s^+ -> \phi \mu^+ \nu_\mu$ yield measured previously in this experiment, we obtain $B(D_s^+ --> \mu^+ \nu_\mu) / B(D_s^+ --> \phi \mu^+ \nu_\mu) =0.16 \pm 0.06 \pm 0.03$. In addition, we extract the decay constant $f_{D_s}=194 \pm 35 \pm 20 \pm 14 MeV$.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

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+

Observation of an excited state of the Lambda(c)+ baryon

An observation of an excited Lambda(c)+* baryon decaying to Lambda(c)+pi+pi-, with Lambda(c)+\u2192pK-pi+, is presented. We reconstruct 39.7+-8.7 Lambda(c)+* baryons with a mass of 340.4+-0.6+-0.3 MeV/c2 above the Lambda(c)+ mass. The upper limit on the resonant branching ratio is B(Lambda(c)+*\u2192Sigma(c)pi\ub1)/B(Lambda(c)+*\u2192Lambda(c)+ pi+pi-)<36% at the 90% confidence level