Phase diagram of the G(2) Higgs model

Wellegehausen, Bjšrn

doi:10.22323/1.139.0266

Cited by 5 publications

(6 citation statements)

References 19 publications

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“…If it can be controlled by the strength of the breaking, however, this could provide new insights, a possibility that certainly deserves further study in the future. For our simulations, which consumed roughly 2000 core-years, we employ an extension of the available local HMC algorithm for scalars [26], generalized from QCD simulations, for details see [21,27]. The introduction of temperature and chemical potential proceeds as in QCD.…”

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confidence: 99%

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Phase diagram of a gauge theory with fermionic baryons

et al. 2012

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The fermion-sign problem at finite density is a persisting challenge for Monte-Carlo simulations. Theories that do not have a sign problem can provide valuable guidance and insight for physically more relevant ones that do. Replacing the gauge group SU(3) of QCD by the exceptional group G2, for example, leads to such a theory. It has mesons as well as bosonic and fermionic baryons, and shares many features with QCD. This makes the G2 gauge theory ideally suited to study general properties of dense, strongly-interacting matter, including baryonic and nuclear Fermi pressure effects. Here we present the first-ever results from lattice simulations of G2 QCD with dynamical fermions, providing a first explorative look at the phase diagram of this QCD-like theory at finite temperature and baryon chemical potential.Finite fermion density continues to be a serious challenge for Monte-Carlo simulations due to the fermionsign problem [1,2]. The sign problem appears in many areas of physics, but is of notorious importance to dense quark systems, especially in nuclei, heavy-ion collisions, and compact stellar objects. An alternative are models and continuum methods which do not have this type of problem [3][4][5][6][7]. However, these usually require approximations, and cross checks through lattice simulations remain desirable to improve systematic reliability.To provide support from numerical simulations, two major strategies have been followed. One is to replace the baryon chemical potential by some quantity more amenable to simulations, e.g. imaginary [8][9][10] or isospin [11,12] chemical potential. The other is to replace the theory with one accessible through numerical simulations at finite density. However, such theories usually differ from the original one in more or less important aspects.One very well studied replacement of QCD for strongly interacting matter at finite density is two-color QCD [13][14][15][16][17]. In this case, the baryons are bosons instead of fermions, however. This leads to profound differences, such as Bose-Einstein condensation of a baryon superfluid with a BEC-BCS crossover at high densities instead of the usual liquid-gas transition of nuclear matter. While two-color QCD has many interesting aspects that deserve to be studied in their own right, the quantum effects due to the fermionic nature of baryons are expected to play a very significant role for nuclear matter and especially in the physics of compact stellar objects [18].Therefore, a more realistic replacement theory in this regard should contain fermionic baryons. One possibility is the strong-coupling limit [19]. In order to maintain * Electronic address: axelmaas@web.de † the connection with the continuum, however, we employ here a different theory without sign problem for Monte-Carlo simulations. It is obtained by replacing the SU(3) gauge group of QCD with the gauge group G 2 [20]. All color representations of this theory are equivalent to real ones. As a consequence the Dirac operator has an antiunitary symplectic symmetry which ...

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confidence: 99%

“…Our aim here is a first exploration of the phase diagram as a proof of principle. One obstacle is the presence of a bulk transition [24,26,28], which turns out to persist with dynamical fermions [21,27]. To avoid this we chose a lattice with at least N t = 5 time slices in finite temperature simulations.…”

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Phase diagram of a gauge theory with fermionic baryons

et al. 2012

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“…Up to a rather small region surrounding (β trip , κ trip ) we can show that the deconfinement transition is first order and the Higgs transition is second order. But in this small window in parameter space, around the would-be triple point, the deconfinement transition is either second order or absent [9].…”

Section: The G 2 Higgs Modelmentioning

confidence: 97%

Phase diagram of the G(2) Higgs model and G(2)-QCD

Wellegehausen

2011

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We investigate gauge theories based on the smallest exceptional simple lie group G 2 . Our first model considered here is G 2 Yang-Mills coupled to a fundamental Higgs field. In 4 spacetime dimensions we explore the phase diagram of the theory, showing that at larger Higgs masses the first order deconfinement phase transition turns into a crossover and therefore connects the low temperature confined phase with the high temperature deconfined phase. The second model investigated is G 2 Yang-Mills coupled to fundamental fermions. It shares many features with QCD, especially fermionic baryons, but due to the absence of the fermion sign problem we can investigate this theory with Monte Carlo techniques even at low temperature and high baryonic density. First results on small lattices are presented.

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“…The confined state, as in the case of SU(N ), is seen on the lattice [66,67] to have a very small value of the traced Polyakov loop in the fundamental representation, l(T − c ) 1, which we take to vanish identically. Note that, as opposed to the case of SU(N ), this order parameter does not necessarily vanish below the critical temperature, as center symmetry is absent 18 .…”

Section: G 2 and Fmentioning

confidence: 98%

Gravitational Waves from Dark Yang-Mills Sectors

Halverson,

Long,

Maiti

et al. 2020

Preprint

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Dark Yang-Mills sectors, which are ubiquitous in the string landscape, may be reheated above their critical temperature and subsequently go through a confining firstorder phase transition that produces stochastic gravitational waves in the early universe. Taking into account constraints from lattice and from Yang-Mills (center and Weyl) symmetries, we use a phenomenological model to construct an effective potential of the semi quark-gluon plasma phase, from which we compute the gravitational wave signal produced during confinement for numerous gauge groups. The signal is maximized when the dark sector dominates the energy density of the universe at the time of the phase transition. In that case, we find that it is within reach of the next-to-next generation of experiments (BBO, DECIGO) for a range of dark confinement scales near the weak scale.

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Phase diagram of the G(2) Higgs model

Cited by 5 publications

References 19 publications

Phase diagram of a gauge theory with fermionic baryons

Phase diagram of a gauge theory with fermionic baryons

Phase diagram of the G(2) Higgs model and G(2)-QCD

Gravitational Waves from Dark Yang-Mills Sectors

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