arXiv subjects

The SELEX Collaboration

Publications and source records attributed to The SELEX Collaboration.

7 recordsLinked to original sources

arXiv2009

Nuclear Dependence of Charm Production

With data taken by SELEX, which accumulated data during the 1996-1997 fixed target run at Fermilab, we study the production of charmed hadrons on copper and carbon targets with Sigma-, p, pi-, and pi+ beams. Parameterizing the production cross section A^alpha, A being the atomic number, we determine alpha for D+, D0, Ds+, D+(2010), Lambda_c+, and their respective anti-particles, as a function of their transverse momentum pt and scaled longitudinal momentum xF. Within our statistics there is no dependence of alpha on xF for any charm species for the interval 0.1<xF<1.0. The average value of alpha for charm production by pion beams is alpha_{meson}=0.850+/-0.028. This is somewhat larger than the corresponding average alpha_{baryon}=0.755+/-0.016 for charm production by baryon beams (Sigma-, p).

hep-ex↗

arXiv2005

Confirmation of the Double Charm Baryon Xi_cc+ via its Decay to p D+ K-

We observes a signal for the double charm baryon Xi_cc+ in the charged decay mode Xi_cc+ -> p D+ K- to complement the previously reported decay Xi_cc+ -> Lambda_c K- pi+ in data from SELEX, the charm hadro-production experiment (E781) at Fermilab. In this new decay mode we observe an excess of 5.62 events over an expected background estimated by event mixing to be 1.38+/-0.13 events. The Poisson probability that a background fluctuation can produce the apparent signal is less than 6.4E-4. The observed mass of this state is (3518+/-3)MeV/c^2, consistent with the published result. Averaging the two results gives a mass of (3518.7+/-1.7)MeV/c^2. The observation of this new weak decay mode confirms the previous SELEX suggestion that this state is a double charm baryon. The relative branching ratio Gamma(Xi_cc+ -> pD+K-)/Gamma(Xi_cc+ -> Lambda_c K- pi+) = 0.36+/-0.21.

hep-ex↗

arXiv2004

First observation of a narrow charm-strange meson DsJ(2632) -> Ds eta and D0 K+

We report the first observation of a charm-strange meson DsJ(2632) at a mass of 2632.6+/-1.6 MeV/c^2 in data from SELEX, the charm hadro-production experiment E781 at Fermilab. This state is seen in two decay modes, Ds eta and D0 K+. In the Ds eta decay mode we observe an excess of 49.3 events with a significance of 7.2sigma at a mass of 2635.9+/-2.9 MeV/c^2. There is a corresponding peak of 14 events with a significance of 5.3sigma at 2631.5+/-1.9 MeV/c^2 in the decay mode D0 K+. The decay width of this state is <17 MeV/c^2 at 90% confidence level. The relative branching ratio Gamma(D0K+)/Gamma(Dseta) is 0.16+/-0.06. The mechanism which keeps this state narrow is unclear. Its decay pattern is also unusual, being dominated by the Ds eta decay mode.

hep-ex↗

arXiv2002

First Observation of the Doubly Charmed Baryon Xi_cc^+

We observe a signal for the doubly charmed baryon Xi_cc^+ in the charged decay mode Xi_cc^+ --> Lambda_c^+ K- pi+ in data from SELEX, the charm hadro-production experiment at Fermilab. We observe an excess of 15.9 events over an expected background of 6.1 +/- 0.5 events, a statistical significance of 6.3sigma. The observed mass of this state is (3519 +/- 1) MeV/c^2. The Gaussian mass width of this state is 3MeV/c^2, consistent with resolution; its lifetime is less than 33fsec at 90% confidence.

hep-ex↗

arXiv2000

Recent Results from SELEX

The SELEX experiment (E781) is 3-stage magnetic spectrometer for the study of charm hadroproduction at large xF using 600 Gev Sigma-, pi- and p beams. New precise measurements of the Lambda_c, D0, and Ds lifetimes are presented. We also report results on Lambda_c and Ds production by Sigma-, pi- and p beams at xF>0.2. The data agree with expectations from color-drag models to explain charm particle/antiparticle production asymmetries.

hep-ex↗

arXiv1999

Total Cross Section Measurements with pi-, Sigma- and Protons on Nuclei and Nucleons around 600 GeV/c

Total cross sections for Sigma- and pi- on beryllium, carbon, polyethylene and copper as well as total cross sections for protons on beryllium and carbon have been measured in a broad momentum range around 600GeV/c. These measurements were performed with a transmission technique adapted to the SELEX hyperon-beam experiment at Fermilab. We report on results obtained for hadron-nucleus cross sections and on results for sigma_tot(Sigma- N) and sigma_tot(pi- N), which were deduced from nuclear cross sections.

hep-ex↗

arXiv1999

Charm hadroproduction results from Selex

The SELEX experiment (E781) is 3-stage magnetic spectrometer for a high statistics study of hadroproduction of charm baryons out to large x_F using 650 Gev Sigma-, pi- and p beams. The main features of the spectrometer are: a high precision silicon vertex system, powerful particle identification provided by TRD and RICH, forward Lambda decay spectrometer and 3-stage lead glass photon detector. An experiment overview and spectrometer features are shown. Reconstructed charm states and results on Lambda_c, D+ particles and antiparticles produced by Sigma-, pi- and p beams at x_F>0.3 and asymmetry for Lambda_c are presented.

hep-ex↗