A study of kinematical correlations between charmed particles produced in π-Cu interactions at √s = 26 GeV
TL;DR: In this article, a sample of 475 events, in which two charmed-particle decays are observed, is analyzed to determine distributions of twoparticle kinematic variables.
About: This article is published in Physics Letters B.The article was published on 1996-09-26 and is currently open access. It has received 9 citations till now. The article focuses on the topics: Quantum chromodynamics.
Summary (2 min read)
Jump to: [1 Introduction] – [2 Event selection] – [3 Momentum estimator] – [4 Background subtraction and acceptances] – [5 Results] and [6 Conclusions]
1 Introduction
- Hadroproduction of heavy quarks is an important testing ground for Quantum Chro- modynamics (QCD).
- The observed experimental correlations between charmed particles provide a test of the NLO QCD calculations.
- These variables are useful in subsequent comparisons with the predictions of charm production models.
- The DkD has analogue readout so that secondary interactions in the detector material may be identi ed by their large energy deposits.
- More details of the description and performance of the experimental apparatus can be found in Refs. [3, 4].
2 Event selection
- Events are selected in which one charmed particle is fully reconstructed, while recon- struction of the decay vertex is all that is required for the second.
- At this stage no cut is applied on the charmed candidate's invariant mass, except that 2-prong vertices compatible with K0 or 0 decays are rejected.
- From the events which satisfy the previous requirements, 690 (2251) in the 1992 (1993) data, the authors extract two samples: the signal sample if the mass of the fully reconstructed vertex in the hypothesis D !.
- The range and width of the side-bands has been chosen to allow the subtraction of a linear background distribution and at the same time to minimize the statistical error of this subtraction.
- They were found to be compatible, so only the combined results are presented.
3 Momentum estimator
- As previously noted, the momenta of the charmed particles is not needed for the measurement of ; however, it is required for the determination of the other correlation variables.
- Thus it is necessary to have an estimator for the momentum of the partially reconstructed vertex which takes into account the unseen decay products.
- The charm momentum can be deduced imposing the charm mass: pD = D DMD: A comparison between these two methods and the simulation indicates that both methods give useful and independent information; however the rst method systematically underestimates the momentum while the second method systematically overestimates it.
- The optimal weights are acceptance dependent; for their experimental setup equal weights give a good result.
- The resulting fractional errors on the correlation variables are well below 10% over most of the range of their measurements.
4 Background subtraction and acceptances
- The invariant mass distribution for the fully reconstructed vertex is shown in Fig. 2a.
- Fitting the data mass distributions with a Gaussian peak above a linear background, the authors nd that the background in the signal region is 15% for both the 1992 and 1993 data sets.
- Comparison of the data and Monte Carlo distributions shows that the charm events with reconstruction errors account for all the background in this mass interval.
- 3 and 4, therefore acceptance corrections were evaluated by dividing each distribution of reconstructed events by the corresponding distribution of generated events.
5 Results
- 3 and 4 show the distributions of the charm correlation variables after back- ground subtraction and acceptance correction.
- Table 1 reports the mean values found by the present analysis for all measured correlation variables.
- The asymmetry in these distributions is thought to result from asymmetry in quark contents of the beam and target particle.
- The and p2T distributions are plotted in Fig. 3 along with the results of a model based on a NLO QCD calculation [22] which includes non-perturbative e ects such as hadronization and initial transverse momentum of the incident partons [23].
- Within the context of this model, no meaningful prediction is available for comparison with the data.
6 Conclusions
- This paper presents correlations observed in the WA92 experiment between two charmed particles produced in {Cu interactions at p s = 26GeV, where one of the charmed particles, which is fully reconstructed, has positive xF .
- The distributions observed are similar in shape and statistics to the previous highest statistics experiment.
- A comparison has been made between the and p2T distributions observed and a model based on NLO QCD.
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Citations
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CERN1
TL;DR: In this paper, the authors review the hadro-production data presently available on open charm and beauty absolute production cross-sections, collected by experiments at CERN, DESY and Fermilab.
129 citations
TL;DR: In this article, the authors studied charmed meson production by 350 GeV/c π − particles incident on copper and tungsten targets at the CERN Ω′ spectrometer.
50 citations
TL;DR: In this article, the results of charmonium production were compared with results on open-charm production, relating to the same experimental conditions, and the ratio between the J / ψ cross-section and the charmed-meson crosssection was found to be σ 0 (J/ψ)/σ 0 (D D − ) = 1.13 ± 0.01.
11 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, University of Puerto Rico at Mayagüez12, University of South Carolina13, University of Tennessee14, Vanderbilt University15
TL;DR: In this article, a large sample of events containing fully and partially reconstructed pairs of charmed D mesons recorded by the Fermilab photoproduction experiment FOCUS (FNAL-E831) is presented.
9 citations
TL;DR: This paper measured the azimuthal correlation between beauty particles, and compared their result with predictions based on perturbative QCD, using a sample of 108 triggered events, produced in 350 GeV /c π− interactions in a copper target.
7 citations
References
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TL;DR: Recent deep-inelastic and prompt-photon data are used to put quantitative limits on {Lambda}{sub M{bar S}} and the gluon distribution and to esimate the theoretical error on a top-quark-mass measurement or lower limit at the same collider.
Abstract: Recent deep-inelastic and prompt-photon data are used to put quantitative limits on ${\ensuremath{\Lambda}}_{\stackrel{-}{\mathrm{MS}}}$ (where $\stackrel{-}{\mathrm{MS}}$ denotes the modified minimal-subtraction scheme) and the gluon distribution, taking fully into account the correlations between the two. The results are used (a) to assess the potential discriminating power of precision measurements of the large-transverse-momentum jet cross section at the Fermilab $p\overline{p}$ collider, and (b) to estimate the theoretical error on a top-quark-mass measurement or lower limit at the same collider. We estimate this latter error at approximately \ifmmode\pm\else\textpm\fi{}4 GeV at present, with the prospect of some slight improvement from an additional calibration from the jet cross section.
29 citations
Complutense University of Madrid1, University of Oxford2, RWTH Aachen University3, Collège de France4, University of Turin5, Pierre-and-Marie-Curie University6, CERN7, University of Tennessee8, University of Trieste9, University of Padua10, University of Genoa11, Rutgers University12, University of Liverpool13, Tata Institute of Fundamental Research14, Tokyo University of Agriculture and Technology15, Stockholm University16, Vrije Universiteit Brussel17
TL;DR: In this article, a sample of D D pairs produced in 360 GeV/c π−p interactions were compared with various models of charm production and the correlation properties were studied in detail for the first time.
25 citations
Aichi University of Education1, University of California, Davis2, Carnegie Mellon University3, Chonnam National University4, Fermilab5, Gifu University6, Gyeongsang National University7, Kindai University8, Kobe University9, Korea University10, Nagoya Institute of Technology11, Nagoya University12, Ohio State University13, Okayama University14, University of Oklahoma15, Osaka City University16, Toho University17, Utsunomiya University18, Wonkwang University19
TL;DR: In this paper, total and differential cross sections for charm mesons produced in 600 GeV/c π- emulsion interactions were presented. But the results were not compared to next-to-leading order QCD predictions.
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15 May 1993-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The Decay Detector as mentioned in this paper is a compact array of 10 μm pitch silicon microstrip detectors designed to give charged track data which is sufficient, both in quantity and in precision, to allow reconstruction of beauty particle decays.
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17 citations
Aichi University of Education1, University of California, Davis2, Carnegie Mellon University3, Chonnam National University4, Fermilab5, Gifu University6, Gyeongsang National University7, Kindai University8, Kobe University9, Korea University10, Nagoya Institute of Technology11, Nagoya University12, Ohio State University13, Okayama University14, University of Oklahoma15, Osaka City University16, Toho University17, Utsunomiya University18, Wonkwang University19
TL;DR: In this paper, the authors present results on charm pair correlations measured in proton-emulsion interactions at s =387 GeV and the predictions of leading order QCD for the distributions in invariant mass, rapidity gap, xF, and polar angle in the charm pair CMS are qualitatively consistent with their measurements.
17 citations