The Rise and Fall of Pentaquarks in Experiments

Schumacher, R. A.

doi:10.1063/1.2220285

Cited by 18 publications

(19 citation statements)

References 47 publications

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“…Multiple entries for a single event, which occur when more than one pion candidate passes the track selection criteria, were suppressed by limiting the angular separation of the B 0 s candidate and the charged track. 20 The resultant B 0 s π ± invariant mass spectrum, shown in Fig. 24a, has a narrow structure that is approximately 60 MeV above the m Bs + m π threshold.…”

Section: B Bottommentioning

confidence: 98%

Nonstandard heavy mesons and baryons: Experimental evidence

Olsen¹,

Skwarnicki²,

Ziemińska³

2018

Rev. Mod. Phys.

755

560

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Quantum Chromodynamics (QCD), the generally accepted theory for the strong interactions, describes the interactions between quarks and gluons. The strongly interacting particles that are seen in nature are hadrons, which are composites of quarks and gluons. Since QCD is a strongly coupled theory at distance scales that are characteristic of observable hadrons, there are no rigorous, first-principle methods to derive the spectrum and properties of the hadrons from the QCD Lagrangian, except for Lattice QCD simulations that are not yet able to cope with all aspects of complex and short-lived states. Instead, a variety of "QCD inspired" phenomenological models have been proposed. Common features of these models are predictions for the existence of hadrons with substructures that are more complex than the standard quark-antiquark mesons and the three quark baryons of the original quark model that provides a concise description of most of the low-mass hadrons. Recently, an assortment of candidates for non-standard multi-quark mesons, meson-gluon hybrids and pentaquark baryons that contain heavy (charm or bottom) quarks have been discovered. Here we review the experimental evidence for these states and make some general comparisons of their measured properties with standard quark-model expectations and predictions of various models for non-standard hadrons. We conclude that the spectroscopy of all but simplest hadrons is not yet understood.

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Section: B Bottommentioning

confidence: 98%

Nonstandard heavy mesons and baryons: Experimental evidence

Olsen¹,

Skwarnicki²,

Ziemińska³

2018

Rev. Mod. Phys.

755

560

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“…However, the Roper width is not the only problem posed for the pentaquark interpretation. There is also the problem that recent experimental results have not confirmed previous claims concerning the existence of pentaquark states [46]. A different analysis argues that the Roper width can be reproduced in a model where the Roper wave function has a 30% admixture of a qqqqq component [47].…”

Section: B Q 2 Dependence Of the Axial N → Form Factorsmentioning

confidence: 89%

AxialN→Δ(1232)andN→N(1440
Barquilla-Cano¹,
Buchmann
²
,
Hernández³
2007
Phys. Rev. C*
28
0
6
0
1
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We calculate the axial N → (1232) and N → N * (1440) transition form factors in a chiral constituent quark model. As required by the partial conservation of axial current (PCAC) condition, we include one-and two-body axial exchange currents. We compare the axial N → (1232) form factors with previous quark model calculations that use only one-body axial currents, and with experimental analyses. The paper provides the first calculation of all weak axial N → N * (1440) form factors. Our main result is that exchange currents are very important for certain axial transition form factors. In addition to improving our understanding of nucleon structure, the present results are relevant to the neutrino-nucleus scattering cross section predictions needed in the analysis of neutrino mixing experiments.

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“…A feature of interest is that the step in C S per unit strangeness for "decuplet", δ 10 = (N − 1)/[(N + 1)(N + 9)], is greater than that for "antidecuplet", δ 10 = N/[(N + 3)(N + 9)], although they coincide for N = 3, and we do not consider the case of N = 1 6 . It can be seen also from Tables 1,2 that the parameter for expansion C S = (α/N)[1 + β/N + ...] is ∼ 7/N, 9/N, 11/N, 13/N, ..., for the "octet", "decuplet", "{27}" and "{35}"-plets, so, it increases with increasing values of (p, q) defining the multiplet [8].…”

Section: Strangeness Contents Of Baryons For Arbitrary Number Of Colorsmentioning

confidence: 99%

“…in [5,6]. Consideration of baryon states in the present paper is relevant independently on particular values of masses, widths and other properties of exotic baryon states measured experimentally.…”

mentioning

confidence: 99%

Baryon spectrum in largeNcchiral soliton and in quark models

Kopeliovich

Shunderuk

2006

Phys. Rev. D

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In memory of Karen Avetovich Ter-Martirosyan, the Teacher. IntroductionDescription of hadrons structure in terms of their quark constituents is generally accepted, but the alternative description within e.g. topological soliton (Skyrme) model [1,2] and its modifications also is useful and has certain advantages in comparison with traditional approaches. The chiral (topological) soliton approach is based on general principles and few ingredients incorporated in the effective chiral lagrangian, this is the reason for apparent simplifications in comparison, for example, with attempts to solve relativistic many-body problem. To simplify the latter, some additional objects like diquarks and triquarks have been phenomenologically introduced and discussed especially intensively after recent observations of the so called pentaquarks [3,4] 1 . Concept of diquarks "as an organizing principle for hadron spectroscopy" is considered in details in [12], see also [13]. The concepts of diquarks, triquarks or other correlated quark clusters are certainly of useful heuristic value, although their properties have not been deduced rigorously from basic QCD lagrangian. It should be noted that diquarks present in different physical states, baryons or mesons, can have different properties like the effective mass and size, even for same quantum numbers. 2In the present paper we perform explicit calculation of the strangeness contents of exotic and nonexotic baryon states at arbitrary number of colors N c , and discuss connection of the chiral soliton approach (CSA) and simple quark (pentaquark) model for exotic baryon states, 1 A contradictive present situation with experimental observation of possible pentaquark states is discussed, e.g. in [5,6]. Consideration of baryon states in the present paper is relevant independently on particular values of masses, widths and other properties of exotic baryon states measured experimentally. A detailed discussion of theoretical predictions of these states can be found in [7,8,9,10,11] 2 Some analogy with nuclei can be noted: two-, three-, etc. nucleon clusters play an important role in the structure of heavy nuclei, however, it is not possible to evaluate their properties from those of deuteron, helium etc., only. See, e.g. [14] for discussion of the role of femtometer toroidal structures in nuclei.

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The Rise and Fall of Pentaquarks in Experiments

Cited by 18 publications

References 47 publications

Nonstandard heavy mesons and baryons: Experimental evidence

Nonstandard heavy mesons and baryons: Experimental evidence

AxialN→Δ(1232)andN→N(1440
Barquilla-Cano¹,
Buchmann
²
,
Hernández³
2007
Phys. Rev. C*
28
0
6
0
1
View full text Add to dashboard Cite

Baryon spectrum in largeNcchiral soliton and in quark models

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The Rise and Fall of Pentaquarks in Experiments

Cited by 18 publications

References 47 publications

Nonstandard heavy mesons and baryons: Experimental evidence

Nonstandard heavy mesons and baryons: Experimental evidence

AxialN→Δ(1232)andN→N*(1440Barquilla-Cano1, Buchmann2, Hernández3 2007Phys. Rev. C280601View full textAdd to dashboardCite

Baryon spectrum in largeNcchiral soliton and in quark models

Contact Info

Product

Resources

About

AxialN→Δ(1232)andN→N(1440
Barquilla-Cano¹,
Buchmann
²
,
Hernández³
2007
Phys. Rev. C*
28
0
6
0
1
View full text Add to dashboard Cite