%0 Generic %1 Morningstar2013Extended %A Morningstar, C. %A Bulava, J. %A Fahy, B. %A Foley, J. %A Jhang, Y. C. %A Juge, K. J. %A Lenkner, D. %A Wong, C. H. %D 2013 %K glueball %T Extended hadron and two-hadron operators of definite momentum for spectrum calculations in lattice QCD %U http://arxiv.org/abs/1303.6816 %X Multi-hadron operators are crucial for reliably extracting the masses of excited states lying above multi-hadron thresholds in lattice QCD Monte Carlo calculations. The construction of multi-hadron operators with significant coupling to the lowest-lying states of interest involves combining single hadron operators of various momenta. The design and implementation of large sets of spatially-extended single-hadron operators of definite momentum and their combinations into two-hadron operators are described. The single hadron operators are all assemblages of gauge-covariantly-displaced, smeared quark fields. Group-theoretical projections onto the irreducible representations of the symmetry group of a cubic spatial lattice are used in all isospin channels. Tests of these operators on 24^3 x 128 and 32^3 x 256 anisotropic lattices using a stochastic method of treating the low-lying modes of quark propagation which exploits Laplacian Heaviside quark-field smearing are presented. The method provides reliable estimates of all needed correlations, even those that are particularly difficult to compute, such as eta eta -> eta eta in the scalar channel, which involves the subtraction of a large vacuum expectation value. A new glueball operator is introduced, and the evaluation of the mixing of this glueball operator with a quark-antiquark operator, pi-pi, and eta-eta operators is shown to be feasible.

@misc{Morningstar2013Extended, abstract = {{Multi-hadron operators are crucial for reliably extracting the masses of excited states lying above multi-hadron thresholds in lattice QCD Monte Carlo calculations. The construction of multi-hadron operators with significant coupling to the lowest-lying states of interest involves combining single hadron operators of various momenta. The design and implementation of large sets of spatially-extended single-hadron operators of definite momentum and their combinations into two-hadron operators are described. The single hadron operators are all assemblages of gauge-covariantly-displaced, smeared quark fields. Group-theoretical projections onto the irreducible representations of the symmetry group of a cubic spatial lattice are used in all isospin channels. Tests of these operators on 24^3 x 128 and 32^3 x 256 anisotropic lattices using a stochastic method of treating the low-lying modes of quark propagation which exploits Laplacian Heaviside quark-field smearing are presented. The method provides reliable estimates of all needed correlations, even those that are particularly difficult to compute, such as eta eta -\> eta eta in the scalar channel, which involves the subtraction of a large vacuum expectation value. A new glueball operator is introduced, and the evaluation of the mixing of this glueball operator with a quark-antiquark operator, pi-pi, and eta-eta operators is shown to be feasible.}}, added-at = {2019-02-23T22:09:48.000+0100}, archiveprefix = {arXiv}, author = {Morningstar, C. and Bulava, J. and Fahy, B. and Foley, J. and Jhang, Y. C. and Juge, K. J. and Lenkner, D. and Wong, C. H.}, biburl = {https://www.bibsonomy.org/bibtex/2ae364b5abce1507c3d73ed599564b5c9/cmcneile}, citeulike-article-id = {12217549}, citeulike-linkout-0 = {http://arxiv.org/abs/1303.6816}, citeulike-linkout-1 = {http://arxiv.org/pdf/1303.6816}, day = 27, eprint = {1303.6816}, interhash = {bdb9afb977c3cbc9411e50f7d2b38524}, intrahash = {ae364b5abce1507c3d73ed599564b5c9}, keywords = {glueball}, month = mar, posted-at = {2013-03-28 08:41:47}, priority = {2}, timestamp = {2019-02-23T22:15:27.000+0100}, title = {{Extended hadron and two-hadron operators of definite momentum for spectrum calculations in lattice QCD}}, url = {http://arxiv.org/abs/1303.6816}, year = 2013 }