Positive parity pentaquarks in a Goldstone boson exchange model

Stancu, Floarea

doi:10.1103/physrevd.58.111501

Cited by 53 publications

(48 citation statements)

References 22 publications

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“…3. The Θ c state lies much higher than the DN threshold in contradiction with several model predictions [18,19,20]. The chiral extrapolated value of the Θ c mass is 3.45(7) GeV, which is about 500 MeV above the DN threshold (M D =1.89(1) GeV) in our calculation.…”

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confidence: 95%

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Lattice Study of the ExoticS=+1Baryon

2004

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We propose S=+1 baryon interpolating operators, which are based on an exotic description of the antidecuplet baryon like diquark-diquark-antiquark. By using one of the new operators, the mass spectrum of the spin-1/2 pentaquark states is calculated in quenched lattice QCD at β = 6/g 2 = 6.2 on a 32 3 × 48 lattice. It is found that the J P assignment of the lowest Θ(uudds) state is most likely (1/2) − . We also calculate the mass of the charm analog of the Θ and find that the Θc(uuddc) state lies much higher than the DN threshold, in contrast to several model predictions.PACS numbers: 11.15. Ha, 12.38.Gc, 12.39.Mk, 14.20.Lq Recently, LEPS collaboration at Spring-8 has observed a very narrow resonance Θ + (1540) in the K − missingmass spectrum of the γn → nK. A remarkable observation is its strangeness is S=+1, which means that the observed resonance must contain a strange antiquark. Thus, the Θ + (1540) should be an exotic baryon state with the minimal quark content uudds. This discovery is subsequently confirmed in different reactions by several other collaborations [2]. It should be noted, however, that the experimental evidence for the Θ + (1540) is not very solid yet since there are a similar number of negative results to be reported [3].Theoretically the existence of such a state was predicted long time ago by the Skyrme model [4]. However, the prediction closest in mass and width with the experiments was made by Diakonov, Petrov and Polyakov using a chiral-soliton model [5]. They predicted that it should be a narrow resonance and stressed that it can be detected by experiment because of its narrow width. In a general group theoretical argument with flavor SU (3), S=+1 pentaquark state should be a member of antidecuplet or higher dimensional representation such as 27-plet or 35-plet. Both the Skyrme model and the chiral-soliton model predict that the lowest S=+1 state appears in the antidecuplet, I=0, and its spin and parity should be (1/2) + [4,5]. Experimentally, spin, parity and isospin of the Θ + (1540) are not determined yet. After the discovery of the Θ + (1540), many model studies for the pentaquark state are made with different spin, parity and isospin.Lattice QCD in principle can determine these quantum numbers of the Θ + (1540), independent of such arbitrary model assumptions or the experiments. We stress that there is substantial progress in lattice study of excited baryons recently [6]. Especially, the negative parity nucleon N * (1535), which lies close to the Θ + (1540), has become an established state in quenched lattice QCD [6,7]. Here we report that quenched lattice QCD is capable of studying the Θ + (1540) as well.Indeed, it is not so easy to deal with the qqqqq state rather than usual baryons (qqq) and mesons (qq) in lattice QCD. The qqqqq state can be decomposed into a pair of color singlet states as qqq and qq, in other words, it can decay into two-hadron states even in the quenched approximation. For instance, one can start a study with a simple minded local operator for the Θ + (154...

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confidence: 95%

“…Although more detailed lattice study would be desirable to clarify the significance of this observation, the present lattice study favors spin-parity (1/2) − for the Θ + (1540). We have also found that the lowest spin-1/2 Θ c state, which has the negative parity, lies much higher than the DN threshold, in contrast to several model predictions [18,19,20].…”

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confidence: 64%

Lattice Study of the ExoticS=+1Baryon

2004

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“…The approach is similar to that previously used in Ref. [23] for the positive parity uuddc and uudsc pentaquarks. That work preceded the H1 experiment [24] which has found evidence, so far not confirmed by other experiments, for a narrow baryon resonance in the D * ± p invariant mass, interpreted as a uuddc pentaquark.…”

Section: Introductionmentioning

confidence: 95%

Spectrum of the $$uudc \bar{c}$$ hidden charm pentaquark with an SU(4) flavor-spin hyperfine interaction

Stancu

2019

Eur. Phys. J. C

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We study a few of the lowest states of the pentaquark uudcc, of positive and negative parity, in a constituent quark model with an SU(4) flavor-spin hyperfine interaction. For positive parity we introduce space wave functions of appropriate permutation symmetry with one unit of orbital angular momentum in the internal motion of the four-quark subsystem or an orbital excitation between the antiquark and the four quark subsystem which remains in the ground state. We show that the lowest positive parity states 1/2 + , 3/2 + are provided by the first alternative and are located below the 1/2 − and the 1/2 + states with all quarks in the ground state. We compare our results with the LHCb three narrow pentaquark structures reported in 2019.

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“…This is a charm analogue of the pentaquark Â þ $ uudd" s [17,18]. So far the charmed pentaquarks have been discussed by many authors in various methods including quark models and hadron models [19][20][21][22][23][24][25][26][27][28][29][30][31]. To obtain a bound "…”

Section: Introductionmentioning

confidence: 99%

Exotic baryons from a heavy meson and a nucleon: Negative parity states

et al. 2011

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We study heavy baryons with an exotic flavor quantum number formed by a heavy meson and a nucleon ( " DN and BN) through a long range one pion exchange interaction. The bound state found previously in the ðI; J P Þ ¼ ð0; 1=2 À Þ channel survives when short range interaction is included. In addition, we find a resonant state with ðI; J P Þ ¼ ð0; 3=2 À Þ as a Feshbach resonance predominated by a heavy vector meson and a nucleon ( " D Ã N and B Ã N). We find that these exotic states exist for the charm and heavier flavor region.

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Positive parity pentaquarks in a Goldstone boson exchange model

Cited by 53 publications

References 22 publications

Lattice Study of the ExoticS=+1Baryon

Lattice Study of the ExoticS=+1Baryon

Spectrum of the $$uudc \bar{c}$$ hidden charm pentaquark with an SU(4) flavor-spin hyperfine interaction

Exotic baryons from a heavy meson and a nucleon: Negative parity states

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