String breaking in SU(2) gauge theory with scalar matter fields

Abstract

We investigate the static potential in the confinement phase of the SU(2) Higgs model on the lattice, where this model is expected to have properties similar to QCD. We observe that Wilson loops are inadequate to determine the potential at large distances, where the formation of two color-neutral mesons is expected. Introducing smeared fields and a suitable matrix correlation function, we are able to overcome this difficulty. We observe string breaking at a distance r b ≈ 1.8r 0 , where the length scale r 0 has a value r 0 ≈ 0.5 fm in QCD. The method presented here may lead the way towards a treatment of string breaking in QCD.

Vortices, Confinement and Higgs Fields

“…Güsken [23] suggested to do coupled channel calculations including the time evolution of single dynamical charges. This program was realized in Higgs models by [24] and for fermions by [25]. String breaking in the 3D Abelian Higgs model was discussed within the monopole mechanism for confinement by [26] and in 3D Z 2 gauge theory in [27].…”

Adjoint “quarks” on coarse anisotropic lattices: Implications for string breaking in full QCD

“…This is despite extensive large scale simulations in unquenched QCD by several collaborations [2][3][4][5][6]. This problem has come under renewed attack in the last few years with several new viewpoints emerging as to the underlying cause of the difficulty in observing string breaking, and suggestions as to the optimal approach for resolving this problem [7][8][9][10][11][12][13][14][15]. These ideas have stimulated new work on string breaking in simulations of full QCD [16][17][18], and on a number of models that may shed light on string breaking [19][20][21][22][23][24].…”

“…This has led to the consideration of other operators to study string breaking between static quarks, especially operators that explicitly generate light valence quarks at the positions of the heavy quarks [11,12]. We note that another distinguishing feature of the operators proposed in Refs.…”

“…The adjoint quark results in Refs. [20][21][22] were interpreted as providing support for the picture [3,7,10] that Wilson loops are not suitable for studies of string breaking, while suggesting that string breaking can readily be observed using operators that explicitly generate states containing light valence particles [11,12].…”

“…In particular we note that operators which explicitly generate light valence quarks, such as proposed in Refs. [11,12,[20][21][22], will automatically exhibit potentials that saturate, even in quenched QCD (here considering the theory with fundamental representation quarks). This is especially clear when the correlator has disconnected contributions.…”