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Sep 23, 2013
09/13

by
K. Rummukainen

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In this talk I present a multicanonical hybrid-like two-step algorithm, which consists of a microcanonical spin system update with demons, and a multicanonical demon refresh. The demons act as a buffer between the multicanonical heat bath and the spin system, allowing for a large variety of update schemes. In this work the cluster algorithm is demonstrated with the 2-dimensional 7-state Potts model, using volumes up to $128^2$.

Source: http://arxiv.org/abs/hep-lat/9211049v1

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Sep 22, 2013
09/13

by
K. Rummukainen

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I present a hybrid-like two-step algorithm, which combines a microcanonical update of a spin system using demons, with a multicanonical demon refresh. The algorithm is free from the supercritical slowing down that burdens the canonical methods: the exponential increase of the tunnelling time between the metastable states in the first-order phase transitions, when the volume of the system is increased. The demons act as a buffer between the multicanonical heat bath and the spin system, allowing...

Source: http://arxiv.org/abs/hep-lat/9209024v1

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Sep 23, 2013
09/13

by
K. Rummukainen

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This talk reviews recent lattice results on the high $T$ electroweak phase transition. A remarkably accurate picture emerges: a) the transition is of first order for $m_H \lsim 80$GeV and vanishes for larger $m_H$; b) transition temperature, latent heat and interface tension are known, as well as c) the properties of the broken and symmetric phases. New developments in the sphaleron rate calculations are discussed.

Source: http://arxiv.org/abs/hep-lat/9608079v1

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Sep 22, 2013
09/13

by
K. Rummukainen

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We study the phase diagram of the 3-dimensional SU(2) + adjoint Higgs theory, and investigate to what extent it can be used as an effective theory of the 4-dimensional high-T SU(2) QCD. The relation between the parameters in 4 and 3 dimensions is obtained through dimensional reduction. The high-T (deconfined) QCD phase corresponds to the symmetric phase of the 3-D Higgs theory. In the relevant parameter region the symmetric phase is not stable, but the metastability is strong enough to make...

Source: http://arxiv.org/abs/hep-lat/9707034v1

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Jul 20, 2013
07/13

by
K. Rummukainen

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External (hyper)magnetic field can modify the phase structure in U(1) gauge+Higgs (Landau-Ginzburg) and SU(2)xU(1) gauge+Higgs (Standard Model) theories. In this talk I discuss how the magnetic field can be implemented on the lattice, and summarize the effects on symmetry breaking phase transitions.

Source: http://arxiv.org/abs/hep-lat/9906011v1

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Sep 18, 2013
09/13

by
M. Laine; K. Rummukainen

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We review the status of non-perturbative lattice studies of the electroweak phase transition. In the Standard Model, the complete phase diagram has been reliably determined, and the conclusion is that there is no phase transition at all for the experimentally allowed Higgs masses. In the Minimal Supersymmetric Standard Model (MSSM), in contrast, there can be a strong first order transition allowing for baryogenesis. Finally, we point out possibilities for future simulations, such as the problem...

Source: http://arxiv.org/abs/hep-lat/9809045v2

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Sep 22, 2013
09/13

by
K. Rummukainen; Steven Gottlieb

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Many low energy hadrons, such as the rho, can be observed as resonances in scattering experiments. A proposal by L\"uscher enables one to determine infinite volume elastic scattering phases from the two-particle energy spectrum measured from finite periodic lattices. In this work, we generalize the formalism to the case where the total momentum of the particles is non-zero; i.e. the lattice frame is not the center-of-mass frame of the scattering particles. There are several advantages to...

Source: http://arxiv.org/abs/hep-lat/9503028v1

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Jul 20, 2013
07/13

by
Leo Karkkainen; K. Rummukainen

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Expansions of the Wilson determinant in lattice QCD with quarks produce gauge action terms which shift the coupling constant of the fundamental representation plaquette action and induce an adjoint representation plaquette action. We study the magnitude of these induced couplings with two flavors of Wilson fermions. We utilize a microcanonical demon method, which allows us to measure the induced couplings directly from gauge configurations generated by full fermionic simulations.

Source: http://arxiv.org/abs/hep-lat/9411025v1

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Sep 18, 2013
09/13

by
Steven Gottlieb; K. Rummukainen

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Most hadronic particles are resonances: for example, the rho meson appears as a resonance in the elastic scattering of two pions. A method by Luescher enables one to measure the properties of the resonance particles from finite lattices. We present here a more general method which includes scattering processes where the total momentum of the particles is non-zero. The main advantage is that the resonance scattering can be observed in a considerably smaller spatial volume. We test the method...

Source: http://arxiv.org/abs/hep-lat/9509088v1

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Sep 23, 2013
09/13

by
M. Laine; K. Rummukainen

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At finite temperatures around the electroweak phase transition, the thermodynamics of the MSSM can be described by a three-dimensional two Higgs doublet effective theory. This effective theory has a phase where CP is spontaneously violated. We study spontaneous CP violation with non-perturbative lattice simulations, and analyse whether one could end up in this phase for any physical MSSM parameter values.

Source: http://arxiv.org/abs/hep-lat/9908045v1

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Jul 20, 2013
07/13

by
M. Laine; K. Rummukainen

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Using a three-dimensional (3d) effective field theory and non-perturbative lattice simulations, we study the MSSM electroweak phase transition with two dynamical Higgs doublets. We first carry out a general analysis of spontaneous CP violation in 3d two Higgs doublet models, finding that this part of the parameter space is well separated from that corresponding to the physical MSSM. We then choose physical parameter values with explicit CP violation and a light right-handed stop, and determine...

Source: http://arxiv.org/abs/hep-lat/0009025v2

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Sep 18, 2013
09/13

by
D. Bodeker; K. Rummukainen

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We numerically investigate gauge field instabilities in anisotropic SU(2) plasmas using weak field initial conditions. The growth of unstable modes is stopped by non-abelian effects for moderate anisotropy. If we increase the anisotropy the growth continues beyond the non-abelian saturation bound. We find strong indications that the continued growth is not due to over-saturation of infrared field modes, but instead due to very rapid growth of high momentum modes which are not unstable in the...

Source: http://arxiv.org/abs/0705.0180v1

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Sep 19, 2013
09/13

by
M. Laine; K. Rummukainen

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We study the MSSM finite temperature electroweak phase transition with lattice Monte Carlo simulations, for a large Higgs mass (m_H ~ 95 GeV) and light stop masses (m_tR ~ 150...160 GeV). We employ a 3d effective field theory approach, where the degrees of freedom appearing in the action are the SU(2) and SU(3) gauge fields, the weakly interacting Higgs doublet, and the strongly interacting stop triplet. We determine the phase diagram, the critical temperatures, the scalar field expectation...

Source: http://arxiv.org/abs/hep-lat/9804019v1

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Sep 19, 2013
09/13

by
M. Laine; K. Rummukainen

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Non-perturbative lattice simulations have shown that there is no electroweak phase transition in the Standard Model for the allowed Higgs masses, m_H \gsim 75 GeV. In the Minimal Supersymmetric Standard Model, in contrast, it has been proposed that the transition should exist and even be strong enough for baryogenesis up to m_H ~ 105 GeV, provided that the lightest stop mass is in the range 100...160 GeV. However, this prediction is based on perturbation theory, and suffers from a noticeable...

Source: http://arxiv.org/abs/hep-ph/9804255v1

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Sep 18, 2013
09/13

by
M. Laine; K. Rummukainen

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We consider explicit and spontaneous CP-violation related to the profile of the two Higgs doublets at the MSSM electroweak phase transition. We find, in accordance with previous results, that in principle spontaneous CP-violation could exist in the MSSM at finite temperatures, but when the constraints from experiment and the strength of the transition are taken into account, the relevant region of the parameter space is rather restricted. Nevertheless, we show that in this small region,...

Source: http://arxiv.org/abs/hep-ph/9811369v3

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Sep 19, 2013
09/13

by
A. Hietanen; K. Rummukainen

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We use three dimensional reduced effective field theory (EQCD) and lattice calculations to determine the quark number susceptibility of QCD at high temperature. We find our results to agree well with known perturbative expansion as well as with other lattice data.

Source: http://arxiv.org/abs/hep-lat/0610111v1

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Sep 18, 2013
09/13

by
T. Karavirta; K. Rummukainen; K. Tuominen

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Lattice simulations on SU(2) and SU(3) gauge theories with matter fields in the fundamental, adjoint and two index symmetric representations are needed to determine if these theories are near or within the conformal window as required for their applications in beyond standard model phenomenology. Simulations with Wilson fermion action are subject to artifacts linear in the lattice spacing $a$, and must be improved. We provide the necessary coefficients for perturbative improvement of the...

Source: http://arxiv.org/abs/1201.1883v1

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Sep 21, 2013
09/13

by
M. Hasenbusch; K. Rummukainen; K. Pinn

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We propose an effective transfer-matrix method that allows a measurement of tunnelling correlation lengths that are orders of magnitude larger than the lattice extension. Combining this method with a particularly efficient implementation of the multimagnetical algorithm we were able to determine the interface tension of the 3D Ising model close to criticality with a relative error of less than 1 per cent.

Source: http://arxiv.org/abs/hep-lat/9312078v1

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Sep 22, 2013
09/13

by
T. Neuhaus; A. Rajantie; K. Rummukainen

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The three-dimensional integer-valued lattice gauge theory, which is also known as a "frozen superconductor," can be obtained as a certain limit of the Ginzburg-Landau theory of superconductivity, and is believed to be in the same universality class. It is also exactly dual to the three-dimensional XY model. We use this duality to demonstrate the practicality of recently developed methods for studying topological defects, and investigate the critical behavior of the phase transition...

Source: http://arxiv.org/abs/cond-mat/0205523v2

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Sep 21, 2013
09/13

by
K. Kajantie; K. Rummukainen; M. Shaposhnikov

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We study the finite temperature electroweak phase transition with lattice perturbation theory and Monte Carlo techniques. Dimensional reduction is used to approximate the full four-dimensional SU(2) + a fundamental doublet Higgs theory by an effective three-dimensional SU(2) + adjoint Higgs + fundamental Higgs theory with coefficients depending on temperature via screening masses and mass counterterms. Fermions contribute to the effective theory only via the $N_F$ and $m_{\rm top}$ dependence...

Source: http://arxiv.org/abs/hep-ph/9305345v1

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Sep 18, 2013
09/13

by
M. Laine; G. Nardini; K. Rummukainen

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We carry out lattice simulations of a cosmological electroweak phase transition for a Higgs mass m_h ~ 126 GeV. The analysis is based on a dimensionally reduced effective theory for an MSSM-like scenario including a relatively light coloured SU(2)-singlet scalar, referred to as a right-handed stop. The non-perturbative transition is stronger than in 2-loop perturbation theory, and may offer a window for electroweak baryogenesis. The main remaining uncertainties concern the physical value of the...

Source: http://arxiv.org/abs/1211.7344v1

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Sep 21, 2013
09/13

by
M. Hasenbusch; K. Pinn; K. Rummukainen

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We study the use of effective transfer matrices for the numerical computation of masses (or correlation lengths) in lattice spin models. The effective transfer matrix has a strongly reduced number of components. Its definition is motivated by a renormalization group transformation of the full model onto a 1-dimensional spin model. The matrix elements of the effective transfer matrix can be determined by Monte Carlo simulation. We show that the mass gap can be recovered exactly from the spectrum...

Source: http://arxiv.org/abs/hep-lat/9304006v2

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Sep 21, 2013
09/13

by
K. Kajantie; Leo Karkkainen; K. Rummukainen

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We study the coefficients of the expansion $F(R) = 1/3 c_3 R^3 + 1/2 c_2 R^2 + c_1 R$ of the free energy of spherical bubbles at $T=T_c$ in pure glue QCD using lattice Monte Carlo techniques. The coefficient $c_3$ vanishes at $T=T_c$ and our results suggest that the sign and the order of magnitude of $c_1$ is in agreement with the value $c_1=\pm 32\pi T_c^2/9$ (- for hadronic bubbles in quark phase, + for quark bubbles in hadronic phase) computed by Mardor and Svetitsky from the MIT bag model....

Source: http://arxiv.org/abs/hep-lat/9204013v1

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Sep 23, 2013
09/13

by
D. Bodeker; G. D. Moore; K. Rummukainen

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We measure the sphaleron rate (topological susceptibility) of hot SU(2) gauge theory, using a lattice implementation of the hard thermal loop (HTL) effective action. The HTL degrees of freedom are implemented by an expansion in spherical harmonics and truncation. Our results for the sphaleron rate agree with the parametric prediction of Arnold, Son and Yaffe: Gamma ~ \alpha^5 T^4.

Source: http://arxiv.org/abs/hep-lat/9909054v1

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Sep 21, 2013
09/13

by
D. Bodeker; Guy D. Moore; K. Rummukainen

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We develop a discrete lattice implementation of the hard thermal loop effective action by the method of added auxiliary fields. We use the resulting model to measure the sphaleron rate (topological susceptibility) of Yang-Mills theory at weak coupling. Our results give parametric behavior in accord with the arguments of Arnold, Son, and Yaffe, and are in quantitative agreement with the results of Moore, Hu, and Muller.

Source: http://arxiv.org/abs/hep-ph/9907545v1

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Sep 18, 2013
09/13

by
K. Kajantie; M. Laine; K. Rummukainen; M. Shaposhnikov

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We study on the lattice the 3d SU(2)+Higgs model, which is an effective theory of a large class of 4d high temperature gauge theories. Using the exact constant physics curve, continuum ($V\to\infty, a\to 0$) results for the properties of the phase transition (critical temperature, latent heat, interface tension) are given. The 3-loop correction to the effective potential of the scalar field is determined. The masses of scalar and vector excitations are determined and found to be larger in the...

Source: http://arxiv.org/abs/hep-lat/9510020v1

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Sep 18, 2013
09/13

by
A. Freund; K. Rummukainen; H. Weigert; A. Schaefer

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In this note we report on geometric scaling in inclusive e A scattering data from the NMC and E665 experiments. We show that this scaling, as well as nuclear shadowing, is expected in the framework of nonlinear pQCD at small x based on a simple rescaling argument for e p scattering.

Source: http://arxiv.org/abs/hep-ph/0210139v1

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Sep 21, 2013
09/13

by
K. Farakos; K. Kajantie; K. Rummukainen; M. Shaposhnikov

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We develop a method for the construction of the effective potential at high temperatures based on the effective field theory approach and renormalization group. It allows one to sum up the leading logarithms in all orders of perturbation theory. The method reproduces the known one-loop and two-loop results in a very simple and economic way and clarifies the issue of the convergence of the perturbation theory. We also discuss the assumptions being made for the determination of the critical...

Source: http://arxiv.org/abs/hep-ph/9404201v1

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Sep 17, 2013
09/13

by
K. Kajantie; M. Laine; K. Rummukainen; Y. Schroder

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The strict coupling constant expansion for the free energy of hot QCD plasma shows bad convergence at all reasonable temperatures, and does not agree well with its 4d lattice determination. This has recently lead to various refined resummations, whereby the agreement with the lattice result should improve, at the cost of a loss of a formal agreement with the coupling constant expansion and particularly with its large infrared sensitive ``long-distance'' contributions. We show here how to resum...

Source: http://arxiv.org/abs/hep-ph/0007109v2

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Sep 22, 2013
09/13

by
K. Kajantie; M. Laine; K. Rummukainen; M. Shaposhnikov

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The continuum 3d SU(2)$\times$U(1)+Higgs theory is an effective theory for a large class of 4d high-temperature gauge theories, including the minimal standard model and some of its supersymmetric extensions. We study the effects of the U(1) subgroup using lattice Monte Carlo techniques. When $g'^2/g^2$ is increased from the zero corresponding to pure SU(2)+Higgs theory, the phase transition gets stronger. However, the increase in the strength is close to what is expected perturbatively, and the...

Source: http://arxiv.org/abs/hep-lat/9612006v1

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Sep 22, 2013
09/13

by
K. Kajantie; M. Laine; K. Rummukainen; M. Shaposhnikov

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We study to what extent the three-dimensional SU(N)+adjoint Higgs theory can be used as an effective theory for finite temperature SU(N) gauge theory, with N=2,3. The parameters of the 3d theory are computed in 2-loop perturbation theory in terms of T/Lambda_MSbar,N,N_f. The perturbative effective potential of the 3d theory is computed to two loops for N=2. While the Z(N) symmetry probably driving the 4d confinement-deconfinement phase transition (for N_f=0) is not explicit in the effective...

Source: http://arxiv.org/abs/hep-ph/9704416v1

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Sep 18, 2013
09/13

by
K. Farakos; K. Kajantie; K. Rummukainen; M. Shaposhnikov

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We discuss a framework relying on both perturbative and non-perturbative lattice computations which will be able to reliably determine the parameters of the EW phase transition. A motivation for the use of 3d effective theory in the lattice simulations, rather than the complete 4d one, is provided. We introduce and compute on the 2-loop level a number of gauge-invariant order parameters -- condensates, which can be measured with high accuracy in MC simulations. The relation between MSbar and...

Source: http://arxiv.org/abs/hep-lat/9412091v1

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Sep 19, 2013
09/13

by
K. Kajantie; M. Laine; K. Rummukainen; Y. Schroder

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We discuss the logarithmic contributions to the vacuum energy density of the three-dimensional SU(3) + adjoint Higgs theory in its symmetric phase, and relate them to numerical Monte Carlo simulations. We also comment on the implications of these results for perturbative and non-perturbative determinations of the pressure of finite-temperature QCD.

Source: http://arxiv.org/abs/hep-lat/0209072v1

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Sep 18, 2013
09/13

by
K. Kajantie; M. Laine; K. Rummukainen; Y. Schroder

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For the pressure (or free energy) of QCD, four-dimensional (4d) lattice data is available at zero baryon density up to a few times the critical temperature $T_c$. Perturbation theory, on the other hand, has serious convergence problems even at very high temperatures. In a combined analytical and three-dimensional (3d) lattice method, we show that it is possible to compute the QCD pressure from about $2 T_c$ to infinity. The numerical accuracy is good enough to resolve in principle, e.g.,...

Source: http://arxiv.org/abs/hep-lat/0110122v1

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Sep 19, 2013
09/13

by
K. Farakos; K. Kajantie; K. Rummukainen; M. Shaposhnikov

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We study the finite temperature electroweak transition with non-perturbative lattice Monte Carlo simulations. We find that it is of first order, at least for Higgs masses up to 80 GeV. The critical temperature of the phase transition is found to be smaller than that determined by a 2-loop renormalization group improved effective potential. The jump of the order parameter at the critical temperature is considerably larger than the perturbative value. By comparing lattice data and perturbation...

Source: http://arxiv.org/abs/hep-ph/9405234v1

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Sep 21, 2013
09/13

by
K. Kajantie; M. Laine; K. Rummukainen; M. Shaposhnikov

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We formulate the rules for dimensional reduction of a generic finite temperature gauge theory to a simpler three-dimensional effective bosonic theory in terms of a matching of Green's functions in the full and the effective theory, and present a computation of a generic set of 1- and 2-loop graphs needed for the application of these rules. As a concrete application we determine the explicit mapping of the physical parameters of the standard electroweak theory to a three-dimensional SU(2)xU(1)...

Source: http://arxiv.org/abs/hep-ph/9508379v1

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Sep 18, 2013
09/13

by
K. Kajantie; M. Laine; K. Rummukainen; M. Shaposhnikov

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The effective super-renormalizable 3-dimensional Lagrangian, describing the high temperature limit of chiral gauge theories, has more symmetry than the original 4d Lagrangian: parity violation is absent. Parity violation appears in the 3d theory only through higher-dimensional operators. We compute the coefficients of dominant P-odd operators in the Standard Electroweak theory and discuss their implications. We also clarify the parametric accuracy obtained with dimensional reduction.

Source: http://arxiv.org/abs/hep-ph/9710538v2

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Sep 18, 2013
09/13

by
K. Kajantie; M. Laine; K. Rummukainen; M. Shaposhnikov

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We provide non-perturbative evidence for the fact that there is no hot electroweak phase transition at large Higgs masses, $m_H = 95$, 120 and 180 GeV. This means that the line of first order phase transitions separating the symmetric and broken phases at small $m_H$ has an end point $m_{H,c}$. In the minimal standard electroweak theory 70 GeV $

Source: http://arxiv.org/abs/hep-ph/9605288v1

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Sep 19, 2013
09/13

by
K. Kajantie; M. Laine; K. Rummukainen; Y. Schroder

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We compute the dimensionally regularised four-loop vacuum energy density of the SU(N_c) gauge + adjoint Higgs theory, in the disordered phase. ``Scalarisation'', or reduction to a small set of master integrals of the type appearing in scalar field theories, is carried out in d dimensions, employing general partial integration identities through an algorithm developed by Laporta, while the remaining scalar integrals are evaluated in d = 3 - 2\epsilon dimensions, by expanding in \epsilon <...

Source: http://arxiv.org/abs/hep-ph/0304048v1

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4.0

Jun 29, 2018
06/18

by
T. Lappi; A. Ramnath; K. Rummukainen; H. Weigert

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We study the effects of a parity-odd "odderon" correlation in JIMWLK renormalization group evolution at high energy. Firstly we show that in the eikonal picture where the scattering is described by Wilson lines, one obtains a strict mathematical upper limit for the magnitude of the odderon amplitude compared to the parity even pomeron one. This limit increases with N_c, approaching infinity in the infinite N_c limit. We use a systematic extension of the Gaussian approximation...

Topics: High Energy Physics - Phenomenology, Nuclear Theory

Source: http://arxiv.org/abs/1606.00551

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Sep 21, 2013
09/13

by
K. Farakos; K. Kajantie; K. Rummukainen; M. Shaposhnikov

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We study the finite temperature transition of SU(2)-Higgs model with lattice Monte Carlo techniques. We use dimensional reduction to transform the original 4-dimensional SU(2)-gauge + fundamental Higgs theory to an effective 3-dimensional SU(2) + adjoint Higgs + fundamental Higgs model. The simulations were performed with Higgs masses of 35 and 80 GeV; in both cases we observe a stronger first order transition than the perturbation theory predicts, indicating that the dynamics of the transition...

Source: http://arxiv.org/abs/hep-lat/9312023v1

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Sep 20, 2013
09/13

by
M. Laine; H. B. Meyer; K. Rummukainen; M. Shaposhnikov

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We study with lattice techniques the localisation of gauge fields on domain wall defects in 2+1 dimensions, following a scenario originally proposed by Dvali and Shifman for 3+1 dimensions, based on confining dynamics in the bulk. We find that a localised gauge zero-mode does exist, if the domain wall is wide enough compared with the confinement scale in the bulk. The range of applicability of the corresponding low-energy effective theory is determined by the mass gap to the higher modes. For a...

Source: http://arxiv.org/abs/hep-ph/0404058v2

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Sep 22, 2013
09/13

by
A. Hietanen; K. Kajantie; M. Laine; K. Rummukainen; Y. Schroder

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We update Monte Carlo simulations of the three-dimensional SU(3) + adjoint Higgs theory, by extrapolating carefully to the infinite volume and continuum limits, in order to estimate the contribution of the infrared modes to the pressure of hot QCD. The sum of infrared contributions beyond the known 4-loop order turns out to be a smooth function, of a reasonable magnitude and specific sign. Unfortunately, adding this function to the known 4-loop terms does not improve the match to...

Source: http://arxiv.org/abs/0811.4664v1

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Sep 18, 2013
09/13

by
K. Kajantie; M. Laine; J. Peisa; K. Rummukainen; M. Shaposhnikov

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We study the finite temperature electroweak phase transition in an external hypercharge U(1) magnetic field H_Y, using lattice Monte Carlo simulations. For sufficiently small fields, H_Y/T^2 < 0.3, the magnetic field makes the first order transition stronger, but it still turns into a crossover for Higgs masses m_H ~ 80 GeV. For larger fields, we observe a mixed phase analogous to a type I superconductor, where a single macroscopic tube of the symmetric phase, parallel to H_Y, penetrates...

Source: http://arxiv.org/abs/hep-lat/9809004v3

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Sep 22, 2013
09/13

by
K. Rummukainen; M. Tsypin; K. Kajantie; M. Laine; M. Shaposhnikov

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We study the universality class and critical properties of the electroweak theory at finite temperature. Such critical behaviour is found near the endpoint m_H=m_{H,c} of the line of first order electroweak phase transitions in a wide class of theories, including the Standard Model (SM) and a part of the parameter space of the Minimal Sypersymmetric Standard Model (MSSM). We find that the location of the endpoint corresponds to the Higgs mass m_{H,c} = 72(2) GeV in the SM with sin^2 theta_W =...

Source: http://arxiv.org/abs/hep-lat/9805013v1

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41

Sep 24, 2013
09/13

by
A. Hietanen; K. Kajantie; M. Laine; K. Rummukainen; Y. Schroder

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In three dimensions, the gluon condensate of pure SU(3) gauge theory has ultraviolet divergences up to 4-loop level only. By subtracting the corresponding terms from lattice measurements of the plaquette expectation value and extrapolating to the continuum limit, we extract the finite part of the gluon condensate in lattice regularization. Through a change of regularization scheme to MSbar and (inverse) dimensional reduction, this result would determine the first non-perturbative coefficient in...

Source: http://arxiv.org/abs/hep-lat/0412008v1

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39

Sep 22, 2013
09/13

by
K. Kajantie; M. Laine; T. Neuhaus; A. Rajantie; K. Rummukainen

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We study with lattice Monte Carlo simulations the relation of global O(2) symmetry breaking in three dimensions to the properties of a geometrically defined vortex loop network. We find that different definitions of constructing a network lead to different results even in the thermodynamic limit, and that with typical definitions the percolation transition does not coincide with the thermodynamic phase transition. These results show that geometrically defined percolation observables need not...

Source: http://arxiv.org/abs/hep-lat/0003020v2

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29

Sep 21, 2013
09/13

by
P. H. Damgaard; U. M. Heller; R. Niclasen; K. Rummukainen

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Based on a large number of smearing steps, we classify SU(3) gauge field configurations in different topological sectors. For each sector we compare the exact analytical predictions for the microscopic Dirac operator spectrum of quenched staggered fermions. In all sectors we find perfect agreement with the predictions for the sector of topological charge zero, showing explicitly that the smallest Dirac operator eigenvalues of staggered fermions at presently realistic lattice couplings are...

Source: http://arxiv.org/abs/hep-lat/9907019v1

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75

Jul 20, 2013
07/13

by
K. Kajantie; M. Laine; T. Neuhaus; A. Rajantie; K. Rummukainen

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We study with lattice Monte Carlo simulations the interactions and macroscopic behaviour of a large number of vortices in the 3-dimensional U(1) gauge+Higgs field theory, in an external magnetic field. We determine non-perturbatively the (attractive or repelling) interaction energy between two or more vortices, as well as the critical field strength H_c, the thermodynamical discontinuities, and the surface tension related to the boundary between the Meissner phase and the Coulomb phase in the...

Source: http://arxiv.org/abs/hep-lat/9906028v2

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95

Sep 18, 2013
09/13

by
K. Farakos; K. Kajantie; M. Laine; K. Rummukainen; M. Shaposhnikov

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We study the phase transition in SU(2)-Higgs model on the lattice using the 3D dimensionally reduced formalism. The 3D formalism enables us to obtain highly accurate Monte Carlo results, which we extrapolate both to the infinite volume and to the continuum limit. Our formalism also provides for a well-determined and unique way to relate the results to the perturbation theory. We measure the critical temperature, latent heat and interface tension for Higgs masses up to 70 GeV.

Source: http://arxiv.org/abs/hep-lat/9509086v1