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Title: On influence of experimental resolution on the statistical significance of a signal : implication for pentaquark searches.

Abstract

An empirical principle for the construction of a linear relationship between the total angular momentum and squared-mass of baryons is proposed. In order to examine linearity of the trajectories, a rigorous least-squares regression analysis was performed. Unlike the standard Regge-Chew-Frautschi approach, the constructed trajectories do not have nonlinear behavior. A similar regularity may exist for lowest-mass mesons. The linear baryonic trajectories are well described by a semiclassical picture based on a spinning relativistic string with tension. The obtained numerical solution of this model was used to extract the (di)quark masses.

Authors:
; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); Russian Foundation for Basic Research
OSTI Identifier:
960368
Report Number(s):
ANL-HEP-PR-07-47
Journal ID: ISSN 1550-7998; PRVDAQ; TRN: US0904385
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Phys. Rev. D; Journal Volume: 75; Journal Issue: 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANGULAR MOMENTUM; BARYONS; CONSTRUCTION; MESONS; NUMERICAL SOLUTION; REGRESSION ANALYSIS; RESOLUTION; TRAJECTORIES

Citation Formats

Chekanov, S., Levchenko, B. B., High Energy Physics, and Skobeltsyn Inst. of Nuclear Physics. On influence of experimental resolution on the statistical significance of a signal : implication for pentaquark searches.. United States: N. p., 2007. Web. doi:10.1103/PhysRevD.75.014007.
Chekanov, S., Levchenko, B. B., High Energy Physics, & Skobeltsyn Inst. of Nuclear Physics. On influence of experimental resolution on the statistical significance of a signal : implication for pentaquark searches.. United States. doi:10.1103/PhysRevD.75.014007.
Chekanov, S., Levchenko, B. B., High Energy Physics, and Skobeltsyn Inst. of Nuclear Physics. Mon . "On influence of experimental resolution on the statistical significance of a signal : implication for pentaquark searches.". United States. doi:10.1103/PhysRevD.75.014007.
@article{osti_960368,
title = {On influence of experimental resolution on the statistical significance of a signal : implication for pentaquark searches.},
author = {Chekanov, S. and Levchenko, B. B. and High Energy Physics and Skobeltsyn Inst. of Nuclear Physics},
abstractNote = {An empirical principle for the construction of a linear relationship between the total angular momentum and squared-mass of baryons is proposed. In order to examine linearity of the trajectories, a rigorous least-squares regression analysis was performed. Unlike the standard Regge-Chew-Frautschi approach, the constructed trajectories do not have nonlinear behavior. A similar regularity may exist for lowest-mass mesons. The linear baryonic trajectories are well described by a semiclassical picture based on a spinning relativistic string with tension. The obtained numerical solution of this model was used to extract the (di)quark masses.},
doi = {10.1103/PhysRevD.75.014007},
journal = {Phys. Rev. D},
number = 2007,
volume = 75,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • An analytical relationship between the statistical significance of an observed signal and the signal width in the case of a large background was obtained. It can help to explain why high-energy experiments may have different conclusions on the existence of new particles. We illustrate our approach using the experimental data on searches for the {theta}{sup +}(1530) pentaquark state. The obtained relationship is also useful for planning of future experiments designed to search for signals of new particles in invariant-mass distributions.
  • We examine cross sections for the processes {gamma} N {yields} NK{bar K} in the framework of a phenomenological Lagrangian. We include contributions from {Lambda} and {Sigma} resonances up to spin 3/2, as well as those from an exotic {Theta}{sup +}. We allow the {Theta}{sup +} to have spin 1/2 or 3/2, with either positive or negative parity in each case. We also allow the state to be either isovector or isoscalar. We find that the scenario that most closely matches observations at Jefferson Laboratory requires a very large coupling of the {Theta}{sup +} to NK*.
  • We examine cross sections for the processes {gamma}N{yields}NKK in the framework of a phenomenological Lagrangian. We include contributions from {lambda} and {sigma} resonances up to spin 3/2, as well as those from an exotic {theta}{sup +}. We allow the {theta}{sup +} to have spin 1/2 or 3/2, with either positive or negative parity in each case. We also allow the state to be either isovector or isoscalar. We find that the scenario that most closely matches observations at Jefferson Laboratory requires a moderately large coupling of the {theta}{sup +} to NK*.
  • Recent results on searches for baryonic resonances compatible with pentaquark states in deep-inelastic collisions at the HERA ep collider are reported. Searches and measurements of strange and charmed pentaquarks by the H1 and ZEUS experiments are presented. The analyses were performed in the central rapidity region of inclusive deep-inelastic scattering at an ep center-of-mass energy of 300-318 GeV using the full HERA I luminosity. Some conclusions and prospects for future measurements with HERA II are discussed.
  • An experimental search for exotic baryons was performed with the HERMES experiment at DESY in quasi-real photoproduction. Positive evidence is presented for a {theta}+ at a mass of 1528 {+-} 2.6(stat) {+-} 2.1 (sys) MeV. No evidence for possible {theta}++, {xi}--(1860) and {xi}0(1860) resonances was found, instead, upper limits for their production cross section are given. In addition, photoproduction crosssections for the {lambda}(1520) and {xi}0(1530) resonances are presented, because they have similar decay modes as the {theta}++ and {xi}-- (1860), respectively.