Improved effective action for light quarks beyond the chiral limit

Musakhanov, M.M.

doi:10.1007/s100520050528

Cited by 32 publications

(82 citation statements)

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“…The two-body interaction between quarks has a separable form, similar to that suggested by instanton liquid studies [22,23]. At LO the model has been shown to provide successful descriptions of mesons and baryons [19,21].…”

Section: Discussionmentioning

confidence: 54%

Mesonic fluctuations in a nonlocal Nambu–Jona-Lasinio model

Plant

Birse

2002

Nuclear Physics A

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The effects of meson fluctuations are studied in a nonlocal generalization of the Nambu-JonaLasinio model, by including terms of next-to-leading order (NLO) in 1/Nc. In the model with only scalar and pseudoscalar interactions NLO contributions to the quark condensate are found to be very small. This is a result of cancellation between virtual mesons and Fock terms, which occurs for the parameter sets of most interest. In the quark self-energy, similar cancellations arise in the tadpole diagrams, although not in other NLO pieces which contribute at the ∼ 25% level. The effects on pion properties are also found to be small. NLO contributions from real ππ intermediate states increase the sigma meson mass by ∼ 30%. In an extended model with vector and axial interactions, there are indications that NLO effects could be larger.

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Section: Discussionmentioning

confidence: 54%

Mesonic fluctuations in a nonlocal Nambu–Jona-Lasinio model

Plant

Birse

2002

Nuclear Physics A

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“…Independent averaging of the Det low over instanton collective coordinates ξ, justified in the dilute gas approximation and performed with the help of fermionization [19,20,21] gives the desired light quarks partition function Z N [v, a, s, p, m]:…”

Section: Light Quarks Partition Function In External Fieldsmentioning

confidence: 99%

“…After that, we average the quark determinant over instanton collective coordinates as it was described in [19,20,21], using smallness of packing parameter ( ρ R ) 4 ∼ 0.01. This leads to the partition function Z N [v, a, s, p, m], which is a generating functional of various quark correlators.…”

Section: Introductionmentioning

confidence: 99%

Low energy constants ofχPTfrom the instanton vacuum model

2007

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In the framework of the instanton vacuum model we make expansion over the current mass m and number of colors Nc and evaluate O(1/Nc, m, m/Nc, m ln m/Nc)-corrections to the dynamical quark mass M , the quark condensate qq , the pion mass Mπ and decay constant Fπ. There are several sources of these corrections: meson loops, finite size of the instanton distribution and the quark-quark "tensor" interaction terms. In contrast to the expectations, we found that numerically the 1/Nc-corrections to dynamical mass are large and mostly come from meson loops. As a consequence, we have large 1/Nc-corrections to all the other quantities. To provide the values of Fπ(m = 0), qq(m = 0) in agreement with χPT, we offer a new set of parameters ρ, R. Finally, we find the low-energy SU (2) f chiral lagrangian constantsl3,l4 in a rather good correspondence with the phenomenology.

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“…Diakonov&Petrov effective action (see recent papers [6]); 2. Improved Action [8] and presented here Modified Improved Action. They are essentially based on Lee& Bardeen result for the quark determinant in instanton vacuum background [4].…”

Section: Discussionmentioning

confidence: 99%

“…The further steps are the exponentiation and the bosonization of the integrand [6]. Finally, the corresponding partition function in terms of constituent quarks has a form [8]:…”

Section: Modification Of Improved Effective Actionmentioning

confidence: 99%