arXiv subjects

Fermilab E791 Collaboration

Publications and source records attributed to Fermilab E791 Collaboration.

12 recordsLinked to original sources

arXiv2002

Differential cross sections, charge production asymmetry, and spin-density matrix elements for D*(2010) produced in 500 GeV/c pi^- nucleon interactions

We report differential cross sections for the production of D*(2010) produced in 500 GeV/c pi^- nucleon interactions from experiment E791 at Fermilab, as functions of Feynman-x (x_F) and transverse momentum squared (p_T^2). We also report the D* +/- charge asymmetry and spin-density matrix elements as functions of these variables. Investigation of the spin-density matrix elements shows no evidence of polarization. The average values of the spin alignment are η= 0.01 +- 0.02 and -0.01 +- 0.02 for leading and non-leading particles, respectively.

hep-ex↗

arXiv2001

Search for Rare and Forbidden Charm Meson Decays D0--> V l+ l- and h h l l

We report the results of a search for flavor-changing neutral current, lepton-flavor, and lepton-number violating decays of the 3 and 4-body decay modes of D0 (and its antiparticle) containing muons and electrons. Using data from Fermilab charm hadroproduction experiment E791, we examine modes with two leptons and either a Rho(0), Kstar, or Phi vector meson or a non-resonant Pi Pi, K Pi, or K K pair of pseudoscalar mesons. No evidence for any of these decays is found. Therefore, we present branching-fraction upper limits at 90% confidence level for the 27 decay modes examined (18 new).

hep-ex↗

arXiv2001

Study of the decay $D^0 \to K^- K^- K^+ π^+$

Using data from the E791 fixed-target hadroproduction experiment at Fermilab we have studied the Cabibbo-favored but phase-space suppressed decay, $D^0 \to K^- K^- K^+ π^+$. We find the decay rate for this mode to be $(0.54 \pm 0.16 \pm 0.08) \times 10^{-2}$ times that for the normalization mode $D^0 \to K^- π^- π^+ π^+$. We observe a clear signal for $D^0 \to ϕK^- π^+$ which is consistent with producing $0.7 \pm 0.3$ of the $D^0 \to K^- K^- K^+ π^+$ signal. In the context of simple models, we use our measurements to estimate the importance of decay amplitudes that produce extra quark-antiquark pairs from the vacuum relative to those that do not.

hep-ex↗

arXiv2000

Search for Rare 3 and 4-Body D0 Decays at FNAL E791

Limits at the 10**-4 level are reported for rare and forbidden decays of the D0 charm meson to a pair of leptons and either a vector meson or two pseudoscalar mesons. Of these searches, 18 are investigations of decays without previous published results; several others have significantly improved sensitivity over previous results.

hep-ex↗

arXiv2000

Search for Rare and Forbidden Charm Meson Decays at Fermilab E791

We report the results of a blind search for flavor-changing neutral current, lepton-flavor violating, and lepton-number violating decays of D+, D(s)+, and D0 mesons (and their antiparticles) into modes containing muons and electrons. Using data from Fermilab charm hadroproduction experiment E791, we examine the pi l l and K l l decay modes of D+ and D(s)+ and the l+ l- decay modes of D0. No evidence for any of these decays is found. Therefore, we present branching-fraction upper limits at 90% confidence level for the 24 decay modes examined. Eight of these modes have no previously reported limits, and fourteen are reported with significant improvements over previously published results.

hep-ex↗

arXiv2000

Charm Physics at Fermilab E791

Experiment 791 at Fermilab's Tagged Photon Laboratory has just accumulated a high statistics charm sample by recording 20 billion events on 24000 8mm tapes. A 500 GeV/c pi- beam was used with a fixed target and a magnetic spectrometer which now includes 23 silicon fixed target and a magnetic spectrometer which now includes 23 silicon microstrip planes for vertex reconstruction. A new data acquisition system read out 9000 events/sec during the part of the Tevatron cycle that delivered beam. Digitization and readout took 50 uS per event. Data was buffered in eight large FIFO memories to allow continuous event building and continuous tape writing to a wall of 42 Exabytes at 9.6 MB/sec. The 50 terabytes of data buffered to tape is now being filtered on RISC CPUs. Preliminary results show D0 --> K- pi+ and D+ --> K- pi+ pi+ decays. Rarer decays will be pursued.

hep-ex↗

arXiv1998

Measurement of the form-factor ratios for D_s^+ -> phi ell^+ nu_ell

We have measured the form factor ratios r_V = V(0)/A_1(0) and r_2 = A_2(0)/A_1(0) for the decay D_s^+ -> phi ell^+ nu_ell, phi -> K^+ K^-, using data from charm hadroproduction experiment E791 at Fermilab. Results are based on 144 signal and 22 background events in the electron channel and 127 signal and 34 background events in the muon channel. We combine the measurements from both lepton channels to obtain r_V = 2.27 +- 0.35 +- 0.22 and r_2 = 1.57 +- 0.25 +- 0.19.

hep-ex↗

arXiv1998

Measurement of the Ds Lifetime

We report the results of a precise measurement of the Ds meson lifetime based on 1662 +/- 56 fully reconstructed Ds -> phi pi decays, from the charm hadroproduction experiment E791 at Fermilab. Using an unbinned maximum likelihood fit, we measure the Ds lifetime to be 0.518 +/- 0.014 +/- 0.007 ps. The ratio of the measured Ds lifetime to the world average D0 lifetime is 1.25 +/- 0.04. This result differs from unity by six standard deviations, indicating significantly different lifetimes for the Ds and the D0.

hep-ex↗

arXiv1997

Measurement of the form-factor ratios for D^+ -> \overline K^{*0}e^+ν_e

We present a measurement of the form-factor ratios r_V=V(0)/A_1(0) and r_2=A_2(0)/A_1(0) for the decay D^+ -> \overline K^{*0} e^+ ν_e. The measurement is based on a signal of approximately 3000 $D^+ -> \overline K^{*0} e^+ ν_e, \overline K^{*0} -> K^-π^+$ decays reconstructed in data from charm hadroproduction experiment E791 at Fermilab. The results are r_V = 1.84 +- 0.11 +- 0.08 and r_2 = 0.71 +- 0.08 +- 0.09.

hep-ph↗

arXiv1997

Search for CP Violation in Charged D Meson Decays

We report results of a search for CP violation in the singly Cabibbo-suppressed decays D+ -> K- K+ pi+, phi pi+, K*(892)0 K+, and pi- pi+ pi+ based on data from the charm hadroproduction experiment E791 at Fermilab. We search for a difference in the D+ and D- decay rates for each of the final states. No evidence for a difference is seen. The decay rate asymmetry parameters A(CP), defined as the difference in the D+ and D- decay rates divided by the sum of the decay rates, are measured to be: A(CP)(K K pi) = -0.014 +/- 0.029, A(CP)(phi pi) = -0.028 +/- 0.036, A(CP)(K*(892) K) = -0.010 +/- 0.050, and A(CP)(pi pi pi) = -0.017 +/- 0.042.

hep-ex↗

arXiv1996

Measurement of the Branching Ratio B(D+ --> rho^0 l nu)/B(D+ --> K*0 l nu)

We report a measurement of the branching ratio B(D+-->rho^0 l nu)/ B(D+-->K*0 l nu) from the Fermilab charm hadroproduction experiment E791. Based on signals of 49+-17 events in the D+--> rho^0 e nu mode and 54+-18 events in the D+--> rho^0 mu nu mode, we measure B(D+-->rho^0 e nu)/B(D+-->K*0 e nu) = 0.045+-0.014+-0.009, and B(D+-->rho^0 mu nu)/B(D+-->K*0 mu nu) = 0.051+-0.015+-0.009. Combining the results from both the electronic and muonic modes, we obtain B(D+-->rho^0 l nu)/B(D+-->K*0 l nu) = 0.047+-0.013. This result is compared to theoretical predictions.

hep-ex↗

arXiv1995

Search for the Flavor-Changing Neutral-Current Decays $D^+\to π^+ μ^+ μ^-$ and $D^+\to π^+ e^+ e^-$

We report the results of a search for the flavor-changing neutral-current decays $D^+\rightarrow π^+ μ^+ μ^-$ and $D^+\rightarrow π^+ e^+ e^-$ in data from Fermilab charm hadroproduction experiment E791. No signal above background is found, and we obtain upper limits on branching fractions, $B(D^+\rightarrow π^+ μ^+ μ^-) < 1.8 \times 10^{-5}$ and $B(D^+\rightarrow π^+ e^+ e^-) < 6.6 \times 10^{-5}$, at the 90\% confidence level.

hep-ex↗