The Experts below are selected from a list of 10470 Experts worldwide ranked by ideXlab platform
Zoltan Fodor - One of the best experts on this subject based on the ideXlab platform.
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the running coupling of the Minimal sextet composite higgs model
Journal of High Energy Physics, 2015Co-Authors: Zoltan Fodor, Kieran Holland, Julius Kuti, Santanu Mondal, Daniel Nogradi, Chik Him WongAbstract:We compute the renormalized running coupling of SU(3) gauge theory coupled to N f = 2 flavors of massless Dirac fermions in the 2-index-symmetric (sextet) representation. This model is of particular interest as a Minimal Realization of the strongly interacting composite Higgs scenario. A recently proposed finite volume gradient flow scheme is used. The calculations are performed at several lattice spacings with two different implementations of the gradient flow allowing for a controlled continuum extrapolation and particular attention is paid to estimating the systematic uncertainties. For small values of the renormalized coupling our results for the β-function agree with perturbation theory. For moderate couplings we observe a downward deviation relative to the 2-loop β-function but in the coupling range where the continuum extrapolation is fully under control we do not observe an infrared fixed point. The explored range includes the locations of the zero of the 3-loop and the 4-loop β-functions in the $$ \overline{\mathrm{MS}} $$ scheme. The absence of a non-trivial zero in the β-function in the explored range of the coupling is consistent with our earlier findings based on hadronic observables, the chiral condensate and the GMOR relation. The present work is the first to report continuum non-perturbative results for the sextet model.
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the running coupling of the Minimal sextet composite higgs model
arXiv: High Energy Physics - Lattice, 2015Co-Authors: Zoltan Fodor, Kieran Holland, Julius Kuti, Santanu Mondal, Daniel Nogradi, Chik Him WongAbstract:We compute the renormalized running coupling of SU(3) gauge theory coupled to N_f = 2 flavors of massless Dirac fermions in the 2-index-symmetric (sextet) representation. This model is of particular interest as a Minimal Realization of the strongly interacting composite Higgs scenario. A recently proposed finite volume gradient flow scheme is used. The calculations are performed at several lattice spacings with two different implementations of the gradient flow allowing for a controlled continuum extrapolation and particular attention is paid to estimating the systematic uncertainties. For small values of the renormalized coupling our results for the beta-function agree with perturbation theory. For moderate couplings we observe a downward deviation relative to the 2-loop beta-function but in the coupling range where the continuum extrapolation is fully under control we do not observe an infrared fixed point. The explored range includes the locations of the zero of the 3-loop and the 4-loop beta-functions in the MSbar scheme. The absence of a non-trivial zero in the beta-function in the explored range of the coupling is consistent with our earlier findings based on hadronic observables, the chiral condensate and the GMOR relation. The present work is the first to report continuum non-perturbative results for the sextet model.
Notker Rosch - One of the best experts on this subject based on the ideXlab platform.
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a strictly variational procedure for cluster embedding based on the extended subspace approach
Journal of Chemical Physics, 1998Co-Authors: Ulrich Gutdeutsch, U Birkenheuer, Notker RoschAbstract:Even if an isolated defect results only in a local perturbation of the electron density, the wave function and the first-order reduced density matrix may still exhibit a long-range response to the defect. We present an axiomatic approach to the construction of a general-purpose embedding scheme which is able to cope with this problem. We start from a list of requirements, which we consider pertinent to an accurate embedding technique, and we proceed to demonstrate that the extended subspace approach recently proposed by Head and Silva [J. Chem. Phys. 104, 3244 (1996)] is the Minimal Realization of such an embedding scheme. The variational principle, strict fulfillment of the Pauli exclusion principle, a finite dimensional parameter space, and the possibility to perform the minimization by a standard SCF (self-consistent field) procedure are the key requirements which lead to a constrained SCF procedure. Self-embedding consistency and local completeness of the Hilbert space can then be realized by a mathem...
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a strictly variational procedure for cluster embedding based on the extended subspace approach
Journal of Chemical Physics, 1998Co-Authors: Ulrich Gutdeutsch, U Birkenheuer, Notker RoschAbstract:Even if an isolated defect results only in a local perturbation of the electron density, the wave function and the first-order reduced density matrix may still exhibit a long-range response to the defect. We present an axiomatic approach to the construction of a general-purpose embedding scheme which is able to cope with this problem. We start from a list of requirements, which we consider pertinent to an accurate embedding technique, and we proceed to demonstrate that the extended subspace approach recently proposed by Head and Silva [J. Chem. Phys. 104, 3244 (1996)] is the Minimal Realization of such an embedding scheme. The variational principle, strict fulfillment of the Pauli exclusion principle, a finite dimensional parameter space, and the possibility to perform the minimization by a standard SCF (self-consistent field) procedure are the key requirements which lead to a constrained SCF procedure. Self-embedding consistency and local completeness of the Hilbert space can then be realized by a mathematically very simple construction principle for the active subspace which can be formulated independent of any basis set. We analyze the spatial structure of the resulting Minimal orbital space by means of tight-binding model Hamiltonians. For metal systems, we find active and frozen constrained SCF spaces to necessarily interlock in a strong and complicated fashion.
Matthias Troyer - One of the best experts on this subject based on the ideXlab platform.
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fermionic quantum critical point of spinless fermions on a honeycomb lattice
New Journal of Physics, 2014Co-Authors: Lei Wang, Philippe Corboz, Matthias TroyerAbstract:Spinless fermions on a honeycomb lattice provide a Minimal Realization of lattice Dirac fermions. Repulsive interactions between nearest neighbors drive a quantum phase transition from a Dirac semimetal to a charge-density-wave state through a fermionic quantum critical point, where the coupling of the Ising order parameter to the Dirac fermions at low energy drastically affects the quantum critical behavior. Encouraged by a recent discovery (Huffman and Chandrasekharan 2014 Phys. Rev. B 89 111101) of the absence of the fermion sign problem in this model, we study the fermionic quantum critical point using the continuous-time quantum Monte Carlo method with a worm-sampling technique. We estimate the transition point with the critical exponents and . Compatible results for the transition point are also obtained with infinite projected entangled-pair states.
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fermionic quantum critical point of spinless fermions on a honeycomb lattice
arXiv: Strongly Correlated Electrons, 2014Co-Authors: Lei Wang, Philippe Corboz, Matthias TroyerAbstract:Spinless fermions on a honeycomb lattice provide a Minimal Realization of lattice Dirac fermions. Repulsive interactions between nearest neighbors drive a quantum phase transition from a Dirac semimetal to a charge-density-wave state through a fermionic quantum critical point, where the coupling of Ising order parameter to the Dirac fermions at low energy drastically affects the quantum critical behavior. Encouraged by a recently discovery of absence of the fermion sign problem in this model, we study the fermionic quantum critical point using the continuous time quantum Monte Carlo method with worm sampling technique. We estimate the transition point $V/t= 1.356(1)$ with the critical exponents $\nu =0.80(3)$ and $\eta =0.302(7)$. Compatible results for the transition point are also obtained with infinite projected entangled-pair states.
B De Moor - One of the best experts on this subject based on the ideXlab platform.
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on the boolean Minimal Realization problem in the max plus algebra
Systems & Control Letters, 1998Co-Authors: Bart De Schutter, Vincent D Blondel, Remco De Vries, B De MoorAbstract:One of the open problems in the max-plus-algebraic system theory for discrete event systems is the Minimal Realization problem. In this paper we present some results in connection with the Minimal Realization problem in the max-plus algebra. First we characterize the Minimal system order of a max-linear discrete event system. We also introduce a canonical representation of the impulse response of a max-linear discrete event system. Next we consider a simplified version of the general Minimal Realization problem: the boolean Minimal Realization problem, i.e., we consider models in which the entries of the system matrices are either equal to the max-plus-algebraic zero element or to the max-plus-algebraic identity element. We give a lower bound for the Minimal system order of a max-plus-algebraic boolean discrete event system. We show that the decision problem that corresponds to the boolean Realization problem (i.e., deciding whether or not a boolean Realization of a given order exists) is decidable, and that the boolean Minimal Realization problem can be solved in a number of elementary operations that is bounded from above by an exponential of the square of (any upper bound of) the Minimal system order. We also point out some open problems, the most important of which is whether or not the boolean Minimal Realization problem can be solved in polynomial time.
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Minimal state space Realization of mimo systems in the max algebra
European Control Conference, 1995Co-Authors: Bart De Schutter, B De MoorAbstract:The topic of this paper is the (partial) Minimal Realization problem in the max algebra, which is one of the modeling frameworks that can be used to model discrete event systems. We use the fact that a system of multivariate max-algebraic polynomial equalities can be transformed into an Extended Linear Complementarity Problem to find all equivalent Minimal state space Realizations of a multiple input multiple output (MIMO) max-linear discrete event system starting from its impulse response matrices. We also give a geometrical description of the set of all Minimal state space Realizations.
Philippe Corboz - One of the best experts on this subject based on the ideXlab platform.
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fermionic quantum critical point of spinless fermions on a honeycomb lattice
New Journal of Physics, 2014Co-Authors: Lei Wang, Philippe Corboz, Matthias TroyerAbstract:Spinless fermions on a honeycomb lattice provide a Minimal Realization of lattice Dirac fermions. Repulsive interactions between nearest neighbors drive a quantum phase transition from a Dirac semimetal to a charge-density-wave state through a fermionic quantum critical point, where the coupling of the Ising order parameter to the Dirac fermions at low energy drastically affects the quantum critical behavior. Encouraged by a recent discovery (Huffman and Chandrasekharan 2014 Phys. Rev. B 89 111101) of the absence of the fermion sign problem in this model, we study the fermionic quantum critical point using the continuous-time quantum Monte Carlo method with a worm-sampling technique. We estimate the transition point with the critical exponents and . Compatible results for the transition point are also obtained with infinite projected entangled-pair states.
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fermionic quantum critical point of spinless fermions on a honeycomb lattice
arXiv: Strongly Correlated Electrons, 2014Co-Authors: Lei Wang, Philippe Corboz, Matthias TroyerAbstract:Spinless fermions on a honeycomb lattice provide a Minimal Realization of lattice Dirac fermions. Repulsive interactions between nearest neighbors drive a quantum phase transition from a Dirac semimetal to a charge-density-wave state through a fermionic quantum critical point, where the coupling of Ising order parameter to the Dirac fermions at low energy drastically affects the quantum critical behavior. Encouraged by a recently discovery of absence of the fermion sign problem in this model, we study the fermionic quantum critical point using the continuous time quantum Monte Carlo method with worm sampling technique. We estimate the transition point $V/t= 1.356(1)$ with the critical exponents $\nu =0.80(3)$ and $\eta =0.302(7)$. Compatible results for the transition point are also obtained with infinite projected entangled-pair states.