Article

# Computing K and D meson masses with Nf=2+1+1 twisted mass lattice QCD

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Humboldt-Universität zu Berlin, Institut für Physik, Newtonstraße 15, D-12489 Berlin, Germany
(Impact Factor: 2.41). 02/2011; 182(2):299-316. DOI: 10.1016/j.cpc.2010.10.004
Source: arXiv

ABSTRACT We discuss the computation of the mass of the K and D mesons within the framework of Nf=2+1+1 twisted mass lattice QCD from a technical point of view. These quantities are essential, already at the level of generating gauge configurations, being obvious candidates to tune the strange and charm quark masses to their physical values. In particular, we address the problems related to the twisted mass flavor and parity symmetry breaking, which arise when considering a non-degenerate (c,s) doublet. We propose and verify the consistency of three methods to extract the K and D meson masses in this framework.

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Available from: Urs Wenger, Aug 24, 2015
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• "The quark mass parameters of the heavy flavour pair have been tuned so that in the unitary lattice setup the Kaon and D-meson masses, take approximately their experimental values. More information about the N f = 2 + 1 + 1 setup scheme and further simulation details can be found in ref. [22] [23]. For the results we will show here, we have employed two values of the lattice spacing determined using the nucleon mass in [2]. "
##### Article: First moment of the flavour octet nucleon parton distribution function using lattice QCD
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ABSTRACT: We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, $\la x\ra^{(8)} _{\mu^2 = 4~\gev^2 }$. In particular, we fully take the disconnected contributions into account in our analysis for which we use a generalization of the technique developed in \cite{Dinter:2012tt}. We investigate systematic effects with a particular emphasis on the excited states contamination. We find that in the renormalization free ratio $\frac{\la x \ra^{(3)}}{\la x \ra^{(8)}}$ (with $\la x \ra^{(3)}$ the non-singlet moment) the excited state contributions cancel to a large extend making this ratio a promising candidate for a comparison to phenomenological analyses. Our final result for this ratio is in agreement with the phenomenological value and we find, including systematic errors, $\frac{\la x \ra^{(3)}}{\la x \ra^{(8)}} = 0.39(1)(4)$.
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• "In this section we summarize the results of the chiral condensate, described in detail in Ref. [3], for N f = 2 + 1 + 1 dynamical fermions of maximally twisted mass fermions [13] [17] [18]. Again we perform a chiral extrapolation following the strategy presented in Ref. [2] for three different values of the lattice spacing a = 0.086, 0.078 and 0.061 fm respectively [18]. "
##### Article: Computation of the chiral condensate using $N_f=2$ and $N_f=2+1+1$ dynamical flavors of twisted mass fermions
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ABSTRACT: We apply the spectral projector method, recently introduced by Giusti and L\"uscher, to compute the chiral condensate using $N_f=2$ and $N_f=2+1+1$ dynamical flavors of maximally twisted mass fermions. We present our results for several quark masses at three different lattice spacings which allows us to perform the chiral and continuum extrapolations. In addition we report our analysis on the $O(a)$ improvement of the chiral condensate for twisted mass fermions. We also study the effect of the dynamical strange and charm quarks by comparing our results for $N_f=2$ and $N_f=2+1+1$ dynamical flavors.
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• "Refs. [7] [8] "
##### Article: Lattice investigation of the tetraquark candidates a0(980) and kappa
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ABSTRACT: It is a long discussed issue whether light scalar mesons have sizeable four-quark components. We present an exploratory study of this question using N_f=2+1+1 twisted mass lattice QCD. A mixed action approach ignoring disconnected contributions is used to calculate correlator matrices consisting of mesonic molecule, diquark-antidiquark and two-meson interpolating operators with quantum numbers of the scalar mesons a0(980) (1(0^++)) and kappa (1/2(0+)). The correlation matrices are analyzed by solving the generalized eigenvalue problem. The theoretically expected free two-particle scattering states are identified, while no additional low lying states are observed. We do not observe indications for bound four-quark states in the channels investigated.