Emergence of a new $SU(4)$ symmetry in the baryon spectrum

Denissenya, Mikhail; Glozman, L. Ya.; Pak, M.

doi:10.48550/arxiv.1508.01413

Cited by 6 publications

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“…Meanwhile emergence of SU (4) has been confirmed in the J = 2 meson sector [13] and in baryons [14].…”

Section: Introductionmentioning

confidence: 93%

SU(2N_F) hidden symmetry of QCD

Glozman

2015

Preprint

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Recently a global SU (4) ⊃ SU (2)L × SU (2)R × U (1)A symmetry of the confining Coulombic part of the QCD Hamiltonian has been discovered with NF = 2. This global symmetry includes both independent rotations of the left-and right-handed quarks in the isospin space as well as the chiralspin rotations that mix the left-and right-handed components of the quark fields. It has been suggested by lattice simulations, however, that a symmetry of mesons in the light quark sector upon the quasi-zero mode truncation from the quark propagators is actually higher than SU (4), because the states from a singlet and a 15-plet irreducible representations of SU (4) are also degenerate. Here we demonstrate that classically QCD, ignoring irrelevant exact zero mode contributions, has a SU (2NF ) symmetry. If effects of dynamical chiral symmetry breaking and of anomaly are encoded in the same near-zero modes, then truncation of these modes should restore a classical SU (2NF ) symmetry. Then we show in a Lorentz-and gauge-invariant manner emergence of a bilocal SU (4) × SU (4) symmetry in mesons that contains a global SU (4) as a subgroup upon truncation of the quasi-zero modes. We also demonstrate that the confining Coulombic part of the QCD Hamiltonian has this bilocal symmetry. It explains naturally a degeneracy of different irreducible representations of SU (4) observed in lattice simulations.

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“…Meanwhile emergence of SU (4) has been confirmed in the J = 2 meson sector [13] and in baryons [14].…”

Section: Introductionmentioning

confidence: 93%

SU(2N_F) hidden symmetry of QCD

Glozman

2015

Preprint

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“…Its effect on the hadron spectrum has been studied extensively in Refs. [10]- [13]. The Banks-Casher relation connects the low-lying modes of the Dirac operator to the quark condensate.…”

Section: Effect Of Low-mode Truncation On the Overlap Factorsmentioning

confidence: 99%

Angular momentum content of the $ρ(1450)$ from chiral lattice fermions

Rohrhofer,

Pak,

Glozman

2016

Preprint

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We identify the chiral and angular momentum content of the leading quark-antiquark Fock component for the ρ(770) and ρ(1450) mesons using a two-flavor lattice simulation with dynamical Overlap Dirac fermions. We extract this information from the overlap factors of two interpolating fields with different chiral structure and from the unitary transformation between chiral and angular momentum basis. For the chiral content of the mesons we find that the ρ(770) slightly favors the (1, 0) ⊕ (0, 1) chiral representation and the ρ(1450) slightly favors the (1/2, 1/2) b chiral representation. In the angular momentum basis the ρ( 770) is then a 3 S1 state, in accordance with the quark model. The ρ( 1450) is a 3 D1 state, showing that the quark model wrongly assumes the ρ(1450) to be a radial excitation of the ρ(770).

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“…one in which correlation functions of sources connected to each other by chiral transformations are identical. Moreover, for most channels a plateau in the effective mass plot continues to exist after the removal of these modes [1][2][3][4][5][6] which may be interpreted as suggesting that reasonably well defined hadronic resonances survive the truncation. However, what was found when the correlation functions were calculated was totally unexpected: a set of identical correlation functions that was much larger than could be explained by chiral symmetry alone.…”

Section: Introductionmentioning

confidence: 99%

“…Recent lattice gauge calculations [1][2][3][4][5][6][7] may have shed significant light on this relationship. These calculations are quite remarkable in that they suggest that in a regime where effects of chiral dynamics are turned off by hand (and thus confinement dynamics may be expected to dominate) a new symmetry emerges which is larger than any explicitly in the QCD lagrangian [1,2,[4][5][6][7]. The nature of this putative emergent symmetry is the subject of the present paper.…”

Section: Introductionmentioning

confidence: 99%

“…The proposal that a new symmetry emerges from QCD is quite radical. It was not introduced lightly [1,2,[4][5][6]. Rather, it was suggested to explain a totally unexpected phenomenon recently observed in lattice calculations of correlation functions with various sources including those with the quantum numbers of spin zero, spin one and spin two mesons and of baryons.…”

Section: Introductionmentioning

confidence: 99%

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On the nature of an emergent symmetry in QCD with low-lying Dirac modes removed

Cohen

2016

Phys. Rev. D

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Remarkable symmetry properties appear to arise in lattice calculations of correlation functions in which the lowest-lying eigenmodes of the Dirac operator in quark propagators are removed by hand. The Banks-Casher relation ties the chiral condensate to the density of low lying modes; thus, it is plausible that removal of such modes could lead to a regime where spontaneous chiral symmetry breaking does not occur. Surprising, a pattern of identical correlation functions was observed that is larger than can be explained by a restoration of chiral symmetry. This suggests that a larger symmetry-one that is not present in the QCD lagrangian-emerges when these modes are removed. Previously it was argued that this emergent symmetry was SU(4). However, when the low-lying modes are removed, the correlation functions of sources in the SU(4) 15-plet of spin-1 mesons appear to coincide with the correlation function of the SU(4) singlet. A natural explanation for this is an emergent symmetry larger than SU(4). In this work, it is shown that there exists no continuous symmetry whose generators in the field theory are spatial integrals of local operators that can account for the full pattern of identical correlation functions unless the apparent coincidence of the singlet channel with the 15-plet is accidental.

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Emergence of a new $SU(4)$ symmetry in the baryon spectrum

Cited by 6 publications

References 0 publications

SU(2N_F) hidden symmetry of QCD

SU(2N_F) hidden symmetry of QCD

Angular momentum content of the $ρ(1450)$ from chiral lattice fermions

On the nature of an emergent symmetry in QCD with low-lying Dirac modes removed

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