Browsing by Author "Takahashi, T. T."

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Open Access
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.
Open Access
Charmed baryon spectrum from lattice QCD near the physical point
(American Physical Society, 2020-09-23) Bahtiyar, H.; Can, K. U.; Erkol, Güray; Gubler, P.; Oka, M.; Takahashi, T. T.; TRJQCD Collaboration; Natural and Mathematical Sciences; ERKOL, Güray
We calculate the low-lying spectrum of charmed baryons in lattice QCD on the 32(3) x 64, N-f = 2 +/- 1 PACS-CS gauge configurations at the almost physical pion mass of similar to 156 MeV/c(2). By employing a set of interpolating operators with different Dirac structures and quark-field smearings for the variational analysis, we extract the ground and first few excited states of the spin-1/2 and spin-3/2, singly, doubly, and triply charmed baryons. Additionally, we study the Xi(c)-Xi(c)' mixing and the operator dependence of the excited states in a variational approach. We identify several states that lie close to the experimentally observed excited states of the Sigma(c), Xi(c) and Omega(c) baryons, including some of the Xi(c) states recently reported by LHCb. Our results for the doubly and triply charmed baryons are suggestive for future experiments.
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Electromagnetic properties of doubly charmed baryons in Lattice QCD
(Elsevier, 2013-11-04) Can, K. Utku; Erkol, Güray; Işıldak, Bora; Oka, M.; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray; IŞILDAK, Bora; Can, K. Utku
We compute the electromagnetic properties of Ξcc baryons in (2+1)-flavor Lattice QCD. By measuring the electric charge and magnetic form factors of Ξcc baryons, we extract the magnetic moments, charge and magnetic radii as well as the ΞccΞccρ coupling constant, which provide important information to understand the size, shape and couplings of the doubly charmed baryons. We find that the two heavy charm quarks drive the charge radii and the magnetic moment of Ξcc to smaller values as compared to those of, e.g., the proton.
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Electromagnetic structure of charmed baryons
(Proceedings of Science, 2013) Can, K. U.; Oka, M.; Erkol, Güray; Işıldak, Bora; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray; IŞILDAK, Bora
We compute the electromagnetic form factors of charmed baryons (∑ c, (ξcc, ω c and ω cc) in 2+1 Lattice QCD and extract their electric and magnetic charge radii as well as their magnetic mo-ments. Such observables are important to understand the structure and the inner dynamics of the hadrons. We find that the existence of the heavy quarks drive the charge radii and magnetic moments to smaller values as compared to those of, e.g., proton.
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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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Electromagnetic structure of charmed baryons in Lattice QCD
(Springer Science+Business Media, 2014-05) Can, Kadir Utku; Erkol, Güray; Işıldak, Bora; Oka, M.; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray; IŞILDAK, Bora; Can, Kadir Utku
As a continuation of our recent work on the electromagnetic properties of the doubly charmed (sic)(cc) baryon, we compute the charge radii and the magnetic moments of the singly charmed Sigma(c), Omega(c) and the doubly charmed Omega(cc) baryons in 2+1 flavor Lattice QCD. In general, the charmed baryons are found to be compact as compared to the proton. The charm quark acts to decrease the size of the baryons to smaller values. We discuss the mechanism behind the dependence of the charge radii on the light valence- and sea-quark masses. The magnetic moments are found to be almost stable with respect to changing quark mass. We investigate the individual quark sector contributions to the charge radii and the magnetic moments. The magnetic moments of the singly charmed baryons are found to be dominantly determined by the light quark and the role of the charm quark is significantly enhanced for the doubly charmed baryons.
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Electromagnetic structure of charmed hadrons
(IOP Publishing, 2014) Erkol, Güray; Can, K. U.; Işıldak, Bora; Oka, M.; Ozpineci, A.; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray; IŞILDAK, Bora
We compute the electromagnetic structures of D and D* mesons, the singly charmed Σc, Ωc and the doubly charmed Ξcc, Ωcc baryons in 2+1 flavor Lattice QCD. We extract the charge radii and the magnetic moments of these hadrons. In general, charmed hadrons are found to be more compact as compared to light hadrons. The magnetic moments of the singly charmed baryons are found to be dominantly determined by the light quark and the role of the charm quark is significantly enhanced when it is doubly represented.
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First lattice calculation of charmed hadrons' electromagnetic form factors
(IOP Publishing, 2014) Can, K. Utku; Erkol, Güray; Işıldak, Bora; Oka, M.; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray; IŞILDAK, Bora; Can, K. Utku
Electromagnetic form factors of D and D* mesons and Ξcc, Σc, Ωc and Ωcc baryons are calculated in 2+1 flavor lattice QCD. As a by product of this calculation electric/magnetic charge radii and magnetic moments are extracted. Compared to the PDG values of the light- sector, i.e. pion and proton, charmed hadron results are systematically smaller.
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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.
Open Access
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.
Open 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.
Open Access
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.
Open Access
Radiative transitions of doubly charmed baryons in lattice QCD
(American Physical Society, 2018-12-13) Bahtiyar, H.; Can, K. U.; Erkol, Güray; Oka, M.; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray
We evaluate the spin-3/2→spin-1/2 electromagnetic transitions of the doubly charmed baryons on 2+1 flavor, 323×64 PACS-CS lattices with a pion mass of 156(9) MeV/c2. A relativistic heavy quark action is employed to minimize the associated systematic errors on charm-quark observables. We extract the magnetic dipole, M1, and the electric quadrupole, E2, transition form factors. In order to make a reliable estimate of the M1 form factor, we carry out an analysis by including the effect of excited-state contributions. We find that the M1 transition is dominant and light degrees of freedom (u/d- or s-quark) play the leading role. E2 form factors, on the other hand, are found to be negligibly small, which in turn, have a minimal effect on the helicity and transition amplitudes. We predict the decay widths and lifetimes of Ξcc∗+,++ and Ωcc∗+ based on our results. Finite size effects on these ensembles are expected to be around 1%. Differences in kinematical and dynamical factors with respect to the Nγ→Δ transition are discussed and compared to nonlattice determinations while keeping possible systematic artifacts in mind. A comparison to Ωcγ→Ωc∗ transition and a discussion on systematic errors related to the choice of heavy quark action are also given. Results we present here are particularly suggestive for experimental facilities such as LHCb, PANDA, Belle II, and BESIII to search for further states.
Open Access
Vector and axial-vector couplings of D and D⁎ mesons in 2+1 flavor lattice QCD
(Elsevier, 2013-02-12) Can, Kadir Utku; Erkol, Güray; Oka, M.; Ozpineci, A.; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray; Can, Kadir Utku
Using the axial-vector coupling and the electromagnetic form factors of the D and D⁎ mesons in 2+1 flavor lattice QCD, we compute the D⁎Dπ , DDρ and D⁎D⁎ρ coupling constants, which play an important role in describing the charm hadron interactions in terms of meson-exchange models. We also extract the charge radii of D and D⁎ mesons and determine the contributions of the light and charm quarks separately.
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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.
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Ξcγ→Ξc ′ transition in lattice QCD
(Elsevier, 2017-09-10) Bahtiyar, H.; Can, K. U.; Erkol, Güray; Oka, M.; Takahashi, T. T.; Natural and Mathematical Sciences; ERKOL, Güray
We evaluate the electromagnetic Ξcγ→Ξc ′ transition on 2+1 flavor lattices corresponding to a pion mass of ∼156 MeV. We extract the magnetic Sachs and Pauli form factors which give the Ξc–Ξc ′ transition magnetic moment and the decay widths of Ξc ′ baryons. We did not find a signal for the magnetic form factor of the neutral transition Ξc 0γ→Ξc ′0, which is suppressed by the U-spin flavor symmetry. As a byproduct, we extract the magnetic form factors and the magnetic moments of Ξc and Ξc ′ baryons, which give an insight to the dynamics of u/d, s and c quarks having masses at different scales.