Spectroscopy with heavy-quark symmetry

Isgur, Nathan; Wise, Mark B.

doi:10.1103/physrevlett.66.1130

Cited by 733 publications

(1,051 citation statements)

References 13 publications

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“…The calculation in ref. [8] was restricted to the decays allowed by the lowest order selection rules suggested by heavy quark symmetry [10]. In the case of the D 1 meson the excluded S−wave transition was found to be rather important here, a result already hinted at in ref.…”

Section: Introductionsupporting

confidence: 60%

Pion decay widths of mesons

et al. 2001

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The pionic decay rates of the excited L = 0, 1 D mesons are calculated with a Hamiltonian model within the framework of the covariant Blankenbecler-Sugar equation. The interaction between the light quark and charm antiquark is described by a linear scalar confining and a screened one-gluon exchange interaction. The decay widths of the D * mesons obtain a contribution from the exchange current that is associated with the linear scalar confining interaction. If this contribution is taken into account along with the single quark approximation, the calculated decay rates of the charged D * mesons are readily below the current empirical upper limits if the axial coupling constant of the light constituent quarks is taken to be g q A = 0.87, but reach the empirical upper limits if g q A = 1. With the conventional values for g q A , the calculated widths of the D1 and D * 2 mesons fall somewhat below the experimental lower limits, leaving room for other decay modes as well, such as ππ decay. The unrealistically large contribution from the axial charge operator to the calculated pion decay width of the D1 meson is suppressed by taking into account the exchange charge effects that are associated with the scalar linear confining and vector one-gluon exchange interactions. The predicted values for the pionic widths of the hitherto undiscovered L = 1 D * 1 and D * 0 mesons are found to be smaller than previous estimates. * koehenri@pcu.helsinki.fi † talahde@pcu.helsinki.fi ‡ nyfalt@pcu.helsinki.fi § riska@pcu.helsinki.fi

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Section: Introductionsupporting

confidence: 60%

Pion decay widths of mesons

et al. 2001

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“…Heavy Quark Symmetry (HQS) has proved to be a useful tool to understand the bottom and charm physics [13,14,15], and it has been extensively used to describe the dynamics of systems containing a heavy quark c or b. For instance, all lattice QCD simulations rely on HQS to describe bottom systems [16].…”

Section: Introductionmentioning

confidence: 99%

Charmed and bottom baryons: a variational approach based on heavy quark symmetry

et al. 2004

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The use of Heavy Quark Symmetry to study bottom and charmed baryons leads to important simplifications of the non-relativistic three body problem, which turns out to be easily solved by a simple variational ansatz. Our simple scheme reproduces previous results (baryon masses, charge and mass radii, · · ·) obtained by solving the Faddeev equations with simple non-relativistic quark-quark potentials, adjusted to the light and heavy-light meson spectra. Wave functions, parameterized in a simple manner, are also given and thus they can be easily used to compute further observables. Our method has been also used to find the predictions for strangeness-less baryons of the SU(2) chirally inspired quark-quark interactions. We find that the one pion exchange term of the chirally inspired interactions leads to relative changes of the Λ b and Λc binding energies as large as 90%.

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“…In the heavy quark limit the heavy quark spin-flavor decouples from the dynamics and hadronic spectrum exhibits an approximate heavy quark spin-flavor symmetry. Heavy quark effective theory (HQET) is a consistent framework to study the 1/m Q corrections to the heavy quark limit [1][2][3][4][5][6]. Another useful limit is the large N c limit where the number of colors N c of the QCD gauge group is taken to be large [7,8].…”

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Model-independent predictions for low energy isoscalar heavy baryon observables in the combined heavy quark and large Nc expansion

et al. 2001

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Model-independent predictions for excitation energies, semileptonic form factors and electromagnetic decay rates of isoscalar heavy baryons and their low energy excited states are discussed in terms of the combined heavy quark and large Nc expansion. At leading order, the observables are completely determined in terms of the known excitation energy of the first excited state of Λc. At next-to-leading order in the combined expansion all heavy baryon observables can be expressed in a model-independent way in terms of two experimentally measurable quantities. We list predictions at leading and next-to-leading order.A number of nonperturbative expansions have been used to study low-energy hadronic observables. The heavy quark expansion has been very successful in describing hadrons containing one heavy quark. In the heavy quark limit the heavy quark spin-flavor decouples from the dynamics and hadronic spectrum exhibits an approximate heavy quark spin-flavor symmetry. Heavy quark effective theory (HQET) is a consistent framework to study the 1/m Q corrections to the heavy quark limit [1][2][3][4][5][6]. Another useful limit is the large N c limit where the number of colors N c of the QCD gauge group is taken to be large [7,8]. In the large N c limit the baryon sector of QCD exhibits an approximate light quark spin-flavor symmetry; eg. as N c goes to infinity the nucleon and ∆ become degenerate [9-13]. For heavy baryons, i.e. baryons containing one (c or b) heavy quark it is useful to consider a double limit and a combined heavy quark and large N c expansion [14]. In Ref. [15][16][17] isoscalar heavy baryons have been considered near the combined limit.The combined heavy quark and large N c expansion is formulated in terms of the counting parameter λ ∼ Λ had /m Q , 1/N c with Λ had N c /m Q arbitrary (here Λ had is a typical hadronic scale). As λ approaches zero, the heavy baryon spectrum exhibits an approximate dynamical symmetry-a contracted O(8) symmetry-which connects orbitally excited states of the heavy baryons to the ground state [14,15]. An effective theory describing low-energy excitations of heavy baryons can be developed using the counting rules consistent with a contracted O(8) symmetry [16]. The purpose of the present paper is to use the formalism of Ref.[17] to derive model-independent relations among observables characterizing isoscalar heavy baryons and their decays. At present, experimental data is available only for the excitation energies of the doublet of the first excited state of Λ c . At leading order in the combined expansion this energy completely determines the excitation energy of the low-energy orbitally excited state of Λ b as well as the dominant semileptonic form factors and electromagnetic decay rates. Such predictions are necessarily rather crude as our expansion is in powers of λ 1/2 . At next-to-leading order an additional observable is required to make further model independent predictions. As data for more heavy baryon observables (such as the excitation energy of Λ b baryon, semil...

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Spectroscopy with heavy-quark symmetry

Cited by 733 publications

References 13 publications

Pion decay widths of mesons

Pion decay widths of mesons

Charmed and bottom baryons: a variational approach based on heavy quark symmetry

Model-independent predictions for low energy isoscalar heavy baryon observables in the combined heavy quark and large Nc expansion

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