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ERKOL, Güray

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Güray

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ERKOL
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Now showing 1 - 10 of 24
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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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    Theoretical determination of K(1)(1270,1400) mixing angle in QCD
    (IOP Publishing, 2012) Dağ, Hüseyin; Ozpineci, A.; Çağıl, A.; Erkol, Güray; Natural and Mathematical Sciences; ERKOL, Güray; DAĞ, Hüseyin
    In quark model, the strange axial vector mesons K1(1270) and K1(1400) are defined as the mixtures of orbital angular momentum states K1A and K1B. In this work, by using the orthogonality of the mass eigenstates, we have estimated the K1(1270, 1400) mixing angle θK1, where we have found that θK1 sime −(39 ± 4)°.
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    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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    Electromagnetic structure of charmed baryons - extended to spin-3/2
    (2015) Can, K. U.; Oka, M.; Erkol, Güray; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray
    The electromagnetic form factors of the spin-3/2 Ω baryons, namely the Ω, Ω∗c , Ω∗ cc and Ωccc, are calculated in full QCD on 323 x 64 PACS-CS lattices with a pION mass of 156(9) MeV. The electric charge radii and magnetic moments from the E0 and M1 multipole form factors are extracted. Results for the electric quadrupole form factor, E2, are also provided. Quark sector contributions are computed individually for each observable and then combined to obtain the baryon properties. Charm quark contributions are observed to be systematically smaller compared to the strange quark contributions in case of the charge radii and magnetic moments. E2 moments of the Ω∗ cc and Ωccc are estimated significantly enough to show that their electric charge distributions are deformed. Properties of the spin-1/2 counterparts of the Ω∗ cc and Ω∗ cc baryons are also computed and a comparison is presented.
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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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    A look inside charmed-strange baryons from lattice QCD
    (American Physical Society, 2015-12-01) Can, K. U.; Erkol, Güray; Oka, M.; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray
    The electromagnetic form factors of the spin-3/2 Ω baryons, namely Ω, Ω∗c, Ω∗cc and Ωccc, are calculated in full QCD on 323×64 PACS-CS lattices with a pion mass of 156(9) MeV. The electric charge radii and magnetic moments from the E0 and M1 multipole form factors are extracted. Results for the electric quadrupole form factors, E2, are also given. Quark sector contributions are computed individually for each observable and then combined to obtain the baryon properties. We find that the charm quark contributions are systematically smaller than the strange-quark contributions in the case of the charge radii and magnetic moments. E2 moments of the Ω∗cc and Ωccc provide a statistically significant data to conclude that their electric charge distributions are deformed to an oblate shape. Properties of the spin-1/2 Ωc and Ωcc baryons are also computed and a thorough comparison is given. This complete study gives valuable hints about the heavy-quark dynamics in charmed hadrons.
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    Structure and dynamics of charmed baryons in lattice QCD
    (AIP, 2017) Erkol, Güray; Natural and Mathematical Sciences; ERKOL, Güray
    I report on the transition from factors of Ωcγ → Ωc ∗ and the preliminary results for Ξcγ → Ξ' c transitions in lattice QCD, which give access to the only decay modes of Ωc∗ and Ξ' c. The decay rates of Ωc ∗ and Ξ' c as extracted from lattice QCD are also given.
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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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    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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    ΛcΣcπ coupling and Σc → Λcπ decay in lattice QCD
    (Elsevier, 2017-05-10) Can, K. U.; Erkol, Güray; Oka, M.; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray
    We evaluate the Lambda(c)Sigma(c)pi coupling constant (G(Lambda c)Sigma(c)pi) and the width of the strong decay Sigma(c) -> Lambda(c)pi in 2 + 1flavor lattice QCD on four different ensembles with pion masses ranging from 700MeV to 300 MeV. We find G(Lambda c)Sigma(c)pi= 18.332(1.476)(stat.)(2.171)(syst.) and the decay width Gamma (Sigma(c) -> Lambda(c)pi) = 1.65(28)(stat.)(30)(syst.) MeVon the physical quark-mass point, which is in agreement with the recent experimental determination.