NUCLEAR Nuclear Physics B389 (1993) 445—510 P H Y S I CS B North-Holland ________________ The hadron spectrum in QCD with dynamical staggered fermions The MT~ Collaboration R. Altmeyer a,b K.D. Born a M. Göckeler a,c R. Horsley a,c E. Laermann cd and G. Schierholz b,c a Inst itut für Theoretische Physik, RWTHAachen, Sommerfeldstrasse, D-5100 Aachen, Germany b Deutsches Elektronen-Synchrotron DESY Notkestrasse 85, D-2000 Hamburg 52, Germany Gruppe Theorie der Elementarteilchen, Höchstleistungsrechenzentrum HLRZ, c / o Forschungszentrum Jülich, D-51 70 Jülich, Germany a Fakultât für Physik, Unit ersitàt Bielefeld, Postfach 8640, D-4800 Bielefeld 1, Germany Received 14 April 1992 (Revised 15 July 1992) Accepted for publication 4 August 1992 The hadron spectrum has been calculated in a large scale simulation of QCD with dynamical staggered fermions on a 16~ ~‘<24 lattice at m = 0.01 and /3 = 5.35 and 5.15. Special emphasis is placed on flavour symmetry restoration, for which we observe a substantial improvement between the two /3-values. The results at the lower /3-value provide a scale for the critical temperature on an eight time slice lattice. In addition to the spectrum we investigate chiral properties and calculate the chiral condensate and f,~ in the chiral limit. 1. Introduction As is well known, the only way to compute the low-energy properties of QCD from first principles is by means of the lattice regularization and numerical simulations. The drawback of this method is that it breaks almost all continuous symmetries, and only for small enough lattice constants can one hope that the broken symmetries will get restored dynamically. It is therefore important to compute, first of all, the known masses and matrix elements of the low-lying hadron states and to demonstrate the correctness of the lattice techniques. It is needless to say that the successful calculation of these quantities would also provide a major test of QCD. In this paper we describe a lattice QCD calculation of the hadron spectrum with four flavours of dynamical staggered fermions. The calculation is done on a 16~x 24 lattice using the exact hybrid Monte Carlo algorithm for 13 = 5.35 and 5.15. We differ from other recent large-scale hadron-mass calculations [1—4] either 055{)-3213/93/$06.00 © 1993 — Elsevier Science Publishers B.V. All rights reserved