Browsing by Author "Bahtiyar, H."

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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.
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.
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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.
Metadata only
Ωcγ → Ω∗ transition in lattice QCD
(Elsevier, 2015-07-30) Bahtiyar, H.; Can, K. U.; Erkol, Güray; Oka, M.; Natural and Mathematical Sciences; ERKOL, Güray
We study the electromagnetic View the MathML sourceΩcγ→Ωc⁎ transition in 2+12+1 flavor lattice QCD, which gives access to the dominant decay mode of View the MathML sourceΩc⁎ baryon. The magnetic dipole and the electric quadrupole transition form factors are computed. The magnetic dipole form factor is found to be mainly determined by the strange quark and the electric quadrupole form factor to be negligibly small, in consistency with the quark model. We also evaluate the helicity amplitudes and the decay rate.