Electrical & Electronics Engineering

Permanent URI for this collectionhttps://hdl.handle.net/10679/44

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Browsing by Institution Author "ERKOL, Güray"

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    Axial charges of octet baryons in two-flavor lattice QCD
    (Elsevier, 2010-03-15) Erkol, Güray; Oka, M.; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray
    We evaluate the strangeness-conserving NN, ΣΣ, ΞΞ, ΛΣ and the strangeness-changing ΛN, ΣN, ΛΞ, ΣΞ axial charges in lattice QCD with two flavors of dynamical quarks and extend our previous work on pseudoscalar-meson–octet-baryon coupling constants so as to include πΞΞ, KΛΞ and KΣΞ coupling constants. We find that the axial charges have rather weak quark mass dependence and the breaking in SU(3)-flavor symmetry is small at each quark-mass point we consider.
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    Isovector axial-vector form factors of octet baryons in QCD
    (American Physical Society, 2011-06-01) Erkol, Güray; Ozpineci, A.; Natural and Mathematical Sciences; ERKOL, Güray
    We compute the diagonal isovector axial-vector as well as induced pseudoscalar form factors of nucleon, Σ, and ≡ baryons by employing the light-cone QCD sum rules to leading order in QCD and including distribution amplitudes up to twist 6. Extrapolating our sum-rules results to low-momentum transfers, we make a comparison with experimental and lattice-QCD results where we can achieve a nice qualitative and quantitative agreement.
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    Meson-baryon coupling constants in two-flavor lattice QCD
    (American Institute of Physics, 2010) Erkol, Güray; Oka, M.; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray
    We evaluate the pseudoscalar-meson coupling constants and the strangeness-conservingand the strangeness-changing axial charges of octet baryons in lattice QCD with two flavors ofdynamical quarks.We find that the coupling constants and the axial charges have rather weak quarkmassdependence and the breaking in SU(3)-flavor symmetry is small at each quark-mass point weconsider.
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    ArticlePublicationOpen Access
    Pseudoscalar-meson octet-baryon coupling constants from two-flavor lattice QCD
    (Elsevier, 2010-04-01) Takahashi, T. T.; Erkol, Güray; Oka, M.; Natural and Mathematical Sciences; ERKOL, Güray
    We evaluate the pseudoscalar-meson octet-baryon coupling constants and the corresponding axial charges in eight channels (πNN, πΣΣ, πΛΣ, KΛN, KΣN, πΞΞ, KΛΞ and KΣΞ) in lattice QCD with two flavors of dynamical quarks. The parameter α≡F/(F+D) representing the SU(3)-flavor symmetry is computed at each u,d-quark hopping parameter and at the flavor-SU(3) symmetric point where the three quark flavors are degenerate at the physical s-quark mass. In particular, we obtain α=0.395(6) at the SU(3) symmetric limit. The quark-mass dependences of the coupling constants are obtained by changing the u- and the d-quark masses and we find that the SU(3)-flavor symmetry is broken by only a few percent at each quark-mass we employ.
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    Pseudoscalar-meson-octet-baryon coupling constants in two-flavor lattice QCD
    (American Physical Society, 2009-04-01) Erkol, Güray; Oka, M.; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray
    We evaluate the πΝΝ, π∑∑, πΛ∑, KΛN and K∑N coupling constants and the corresponding monopole masses in lattice QCD with two flavors of dynamical quarks. The parameters representing the SU(3)-flavor symmetry are computed at the point where the three quark flavors are degenerate at the physical s-quark mass. In particular, we obtain α ≡ F/(F+D) = 0.395(6). The quark-mass dependences of the coupling constants are obtained by changing the u- and the d-quark masses. We find that the SU(3)-flavor parameters have weak quark-mass dependence and thus the SU(3)-flavor symmetry is brokenby only a few percent at each quark-mass point we consider.
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    QCD coupling constants and VDM
    (AIP, 2012) Erkol, Güray; Ozpineci, A.; Zamiralov, V. S.; Natural and Mathematical Sciences; ERKOL, Güray
    QCD sum rules for coupling constants of vector mesons with baryons are constructed.The corresponding QCD sum rules for electric charges and magnetic moments are also derived and with the use of vector-meson-dominance model related to the coupling constants. The vector-dominance model (VDM) role as the criterium of reciprocal validity of the sum rules is considered.
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    QCD sum rules for the coupling constants of vector mesons to octet baryons
    (Springer Science+Business Media, 2013-05) Zamiralov, V. S.; Ozpineci, A.; Erkol, Güray; Natural and Mathematical Sciences; ERKOL, Güray
    The QCD sum rules on the light cone proposed by Wang for the coupling constants of the ρ meson are generalized to the vector mesons ω and φ and all octet baryons, the Λ-hyperon included. A comparison with other results is given.
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    Spin content of Λ in QCD sum rules
    (American Physical Society, 2009-06-01) Erkol, Güray; Oka, M.; Natural and Mathematical Sciences; ERKOL, Güray
    We calculate the isoscalar axial-vector coupling constants of the Λ hyperon using the method of QCD sum rules. A determination of these coupling constants reveals the individual contributions of the u, d, and the s quarks to the spin content of Λ. Our results for the light-quark contributions are in agreement with those from experiment assuming flavor SU(3). We also find that the flavor-SU(3)-breaking effects are small and the contributions from the u and the d quarks to the Λ polarization are negatively polarized as in the flavor-SU(3) limit.
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    Tensor form factors of nucleon in QCD
    (Elsevier, 2011-10-25) Erkol, Güray; Ozpineci, A.; Natural and Mathematical Sciences; ERKOL, Güray
    We extract the isovector tensor nucleon form factors, which play an important role in understanding the transverse spin structure of the nucleon when related to the quark helicity-flip generalized parton distributions via their first moments. We employ the light-cone QCD sum rules to leading order in QCD and include distribution amplitudes up to twist 6 in order to calculate the three tensor form factors HT, ET and . Our results agree well with those from other approaches in the low and high momentum-transfer regions.