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Register a new userDetermination of the charm quark mass in lattice QCD with $2+1$ flavours on fine lattices
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We present a determination of the charm quark mass in lattice QCD with three active quark flavours. The calculation is based on PCAC masses extracted from $N_mathrm{f}=2+1$ flavour gauge field ensembles at five different lattice spacings in a range from 0.087 fm down to 0.039 fm. The lattice action consists of the $mathrm{O}(a)$ improved Wilson-clover action and a tree-level improved Symanzik gauge action. Quark masses are non-perturbatively $mathrm{O}(a)$ improved employing the Symanzik-counterterms available for this discretisation of QCD. To relate the bare mass at a specified low-energy scale with the renormalisation group invariant mass in the continuum limit, we use the non-pertubatively known factors that account for the running of the quark masses as well as for their renormalisation at hadronic scales. We obtain the renormalisation group invariant charm quark mass at the physical point of the three-flavour theory to be $M_mathrm{c} = 1486(21),mathrm{MeV}$. Combining this result with five-loop perturbation theory and the corresponding decoupling relations in the $overline{mathrm{MS}}$ scheme, one arrives at a result for the renormalisation group invariant charm quark mass in the four-flavour theory of $M_mathrm{c}(N_mathrm{f}=4) = 1548(23),mathrm{MeV}$. In the $overline{mathrm{MS}}$ scheme, and at finite energy scales conventional in phenomenology, we quote $m^{overline{mathrm{MS}}}_{mathrm{c}}(m^{overline{mathrm{MS}}}_{mathrm{c}}; N_mathrm{f}=4)=1296(19),mathrm{MeV}$ and $m^{overline{mathrm{MS}}}_{mathrm{c}}(3,mathrm{GeV}; N_mathrm{f}=4)=1007(16),mathrm{MeV}$ for the renormalised charm quark mass
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We investigate the charm quark system on 2+1 flavor PACS-CS configurations. Calculations are performed at the lattice spacing $a^{-1}=2.194(10)$ GeV and the spatial extent $L=2.9$ fm with O(a)-improved Wilson fermions for the light quarks and the relativistic heavy fermion for the charm quark. Our dynamical $ud$ and strange quark masses and valence charm quark mass are set to their physical values. A comparison of the mass spectrum and decay constants with experiments is presented. Our results for the charm quark mass and CKM matrix elements are also reported.
We present a lattice QCD calculation of the up, down, strange and charm quark masses performed using the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2 + 1 + 1 dynamical quarks, which include in the sea, besides two light mass degenerate quarks, also the strange and charm quarks with masses close to their physical values. The simulations are based on a unitary setup for the two light quarks and on a mixed action approach for the strange and charm quarks. The analysis uses data at three values of the lattice spacing and pion masses in the range 210 - 450 MeV, allowing for accurate continuum limit and controlled chiral extrapolation. The quark mass renormalization is carried out non-perturbatively using the RI-MOM method. The results for the quark masses converted to the bar{MS} scheme are: mud(2 GeV) = 3.70(17) MeV, ms(2 GeV) = 99.6(4.3) MeV and mc(mc) = 1.348(46) GeV. We obtain also the quark mass ratios ms/mud = 26.66(32) and mc/ms = 11.62(16). By studying the mass splitting between the neutral and charged kaons and using available lattice results for the electromagnetic contributions, we evaluate mu/md = 0.470(56), leading to mu = 2.36(24) MeV and md = 5.03(26) MeV.
We investigate the masses and decay constants of eta and eta mesons using the Wilson twisted mass formulation with N_f=2+1+1 dynamical quark flavours based on gauge configurations of ETMC. We show how to efficiently subtract excited state contributions to the relevant correlation functions and estimate in particular the eta mass with improved precision. After investigating the strange quark mass dependence and the continuum and chiral extrapolations, we present our results for masses and mixing angle(s) at the physical point. Using chiral perturbation theory we also extract the decay constants f_l and f_s and use them to estimate the decay widths of eta,eta to gamma gamma and the transition form factor in the limit of large momentum transfer.
We present the current status of our lattice QCD determination of the charm quark mass using $N_mathrm{f}=2+1$ dynamical, non-perturbatively $mathrm{O}(a)$ improved Wilson fermions. A subset of CLS ensembles with five different lattice spacings along the $mathrm{Tr}[M_mathrm{q}]=text{const.}$ trajectory is used. For the computation of the correlation functions involving valence charm quark propagators, we employ distance preconditioning to gain the necessary precision. To stabilize the extrapolations to the physical point, we consider different definitions of the bare charm quark mass and corresponding renormalization procedures.
We investigate the charm quark system using the relativistic heavy quark action on 2+1 flavor PACS-CS configurations previously generated on $32^3 times 64$ lattice. The dynamical up-down and strange quark masses are set to the physical values by using the technique of reweighting to shift the quark hopping parameters from the values employed in the configuration generation. At the physical point, the lattice spacing equals $a^{-1}=2.194(10)$ GeV and the spatial extent $L=2.88(1)$ fm. The charm quark mass is determined by the spin-averaged mass of the 1S charmonium state, from which we obtain $m_{rm charm}^{msbar}(mu = m_{rm charm}^{msbar}) = 1.260(1)(6)(35)$ GeV, where the errors are due to our statistics, scale determination and renormalization factor. An additional systematic error from the heavy quark is of order $alpha_s^2 f(m_Q a)(a Lambda_{QCD})$, which is estimated to be a percent level if the factor $f(m_Q a)$ analytic in $m_Q a$ is of order unity. Our results for the charmed and charmed-strange meson decay constants are $f_D=226(6)(1)(5)$ MeV, $f_{D_s}=257(2)(1)(5)$ MeV, again up to the heavy quark errors of order $alpha_s^2 f(m_Q a)(a Lambda_{QCD})$. Combined with the CLEO values for the leptonic decay widths, these values yield $|V_{cd}| = 0.205(6)(1)(5)(9)$, $|V_{cs}| = 1.00(1)(1)(3)(3)$, where the last error is on account of the experimental uncertainty of the decay widths.
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