The Experts below are selected from a list of 17343 Experts worldwide ranked by ideXlab platform
Yu Holovatch - One of the best experts on this subject based on the ideXlab platform.
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possibility of a continuous phase transition in random anisotropy magnets with a generic random axis distribution
Physical Review B, 2020Co-Authors: D Shapoval, M Dudka, Andrei A Fedorenko, Yu HolovatchAbstract:We reconsider the problem of the critical behavior of a three-dimensional $O(m)$ symmetric magnetic system in the presence of random-anisotropy disorder with a generic trimodal random-axis distribution. By introducing $n$ replicas to average over disorder it can be coarse grained to a ${\ensuremath{\phi}}^{4}$ theory with an $m\ifmmode\times\else\texttimes\fi{}n$ component order parameter and five coupling constants taken in the limit of $n\ensuremath{\rightarrow}0$. Using a field theory approach we renormalize the model to two-loop order and calculate the $\ensuremath{\beta}$ functions within the $\ensuremath{\varepsilon}$ expansion and directly in three dimensions. We analyze the corresponding renormalization group flows with the help of the Pad\'e-Borel resummation technique. We show that there is no Stable Fixed Point accessible from physical initial conditions whose existence was argued in previous studies. This may indicate the absence of a long-range ordered phase in the presence of random-anisotropy disorder with a generic random-axis distribution.
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Possibility of a continuous phase transition in random-anisotropy magnets with a generic random-axis distribution
'American Physical Society (APS)', 2020Co-Authors: Shapoval D., Dudka M., Fedorenko A.a., Yu HolovatchAbstract:International audienceWe reconsider the problem of the critical behavior of a three-dimensional O(m) symmetric magnetic system in the presence of random-anisotropy disorder with a generic trimodal random-axis distribution. By introducing n replicas to average over disorder it can be coarse grained to a ϕ4 theory with an m×n component order parameter and five coupling constants taken in the limit of n→0. Using a field theory approach we renormalize the model to two-loop order and calculate the β functions within the ɛ expansion and directly in three dimensions. We analyze the corresponding renormalization group flows with the help of the Padé-Borel resummation technique. We show that there is no Stable Fixed Point accessible from physical initial conditions whose existence was argued in previous studies. This may indicate the absence of a long-range ordered phase in the presence of random-anisotropy disorder with a generic random-axis distribution
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on the possibility of a continuous phase transition in the random anisotropy magnets with a generic random axis distribution
arXiv: Disordered Systems and Neural Networks, 2019Co-Authors: D Shapoval, M Dudka, Andrei A Fedorenko, Yu HolovatchAbstract:We reconsider the problem of the critical behavior of a three-dimensional $O(m)$ symmetric magnetic system in the presence of random anisotropy disorder with a generic trimodal random axis distribution. By introducing $n$ replicas to average over disorder it can be coarse-grained to a $\phi^{4}$-theory with $m \times n$ component order parameter and five coupling constants taken in the limit of $n \to 0$. Using a field theory approach we renormalize the model to two-loop order and calculate the $\beta$-functions within the $\varepsilon$ expansion and directly in three dimensions. We analyze the corresponding renormalization group flows with the help of the Pade-Borel resummation technique. We show that there is no Stable Fixed Point accessible from physical initial conditions whose existence was argued in the previous studies. This indicates an absence of a long-range ordered phase in the presence of random anisotropy disorder with a generic random axis distribution.
Masao Ninomiya - One of the best experts on this subject based on the ideXlab platform.
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ultraviolet Stable Fixed Point and scaling relations in 2 ϵ dimensional quantum gravity
Nuclear Physics, 1993Co-Authors: Hikaru Kawai, Yoshihisa Kitazawa, Masao NinomiyaAbstract:Abstract We formulate a renormalizable quantum gravity in 2 + ϵ dimensions by generalizing the nonlinear sigma model approach to string theory. We find that the theory possesses the ultraviolet Stable Fixed Point if the central charge of the matter sector is in the range 0 c
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ultraviolet Stable Fixed Point and scaling relations in 2 epsilon dimensional quantum gravity
arXiv: High Energy Physics - Theory, 1993Co-Authors: Hikaru Kawai, Yoshihisa Kitazawa, Masao NinomiyaAbstract:We formulate a renormalizable quantum gravity in $2+\epsilon$ dimensions by generalizing the nonlinear sigma model approach to string theory. We find that the theory possesses the ultraviolet Stable Fixed Point if the central charge of the matter sector is in the range $0~<~c~<~25$. This may imply the existence of consistent quantum gravity theory in 3 and 4 dimensions. We compute the scaling dimensions of the relevant operators in the theory at the ultraviolet Fixed Point. We obtain a scaling relation between the cosmological constant and the gravitational constant, which is crucial for searching for the continuum limit in the constructive approach to quantum gravity.
M Dudka - One of the best experts on this subject based on the ideXlab platform.
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possibility of a continuous phase transition in random anisotropy magnets with a generic random axis distribution
Physical Review B, 2020Co-Authors: D Shapoval, M Dudka, Andrei A Fedorenko, Yu HolovatchAbstract:We reconsider the problem of the critical behavior of a three-dimensional $O(m)$ symmetric magnetic system in the presence of random-anisotropy disorder with a generic trimodal random-axis distribution. By introducing $n$ replicas to average over disorder it can be coarse grained to a ${\ensuremath{\phi}}^{4}$ theory with an $m\ifmmode\times\else\texttimes\fi{}n$ component order parameter and five coupling constants taken in the limit of $n\ensuremath{\rightarrow}0$. Using a field theory approach we renormalize the model to two-loop order and calculate the $\ensuremath{\beta}$ functions within the $\ensuremath{\varepsilon}$ expansion and directly in three dimensions. We analyze the corresponding renormalization group flows with the help of the Pad\'e-Borel resummation technique. We show that there is no Stable Fixed Point accessible from physical initial conditions whose existence was argued in previous studies. This may indicate the absence of a long-range ordered phase in the presence of random-anisotropy disorder with a generic random-axis distribution.
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on the possibility of a continuous phase transition in the random anisotropy magnets with a generic random axis distribution
arXiv: Disordered Systems and Neural Networks, 2019Co-Authors: D Shapoval, M Dudka, Andrei A Fedorenko, Yu HolovatchAbstract:We reconsider the problem of the critical behavior of a three-dimensional $O(m)$ symmetric magnetic system in the presence of random anisotropy disorder with a generic trimodal random axis distribution. By introducing $n$ replicas to average over disorder it can be coarse-grained to a $\phi^{4}$-theory with $m \times n$ component order parameter and five coupling constants taken in the limit of $n \to 0$. Using a field theory approach we renormalize the model to two-loop order and calculate the $\beta$-functions within the $\varepsilon$ expansion and directly in three dimensions. We analyze the corresponding renormalization group flows with the help of the Pade-Borel resummation technique. We show that there is no Stable Fixed Point accessible from physical initial conditions whose existence was argued in the previous studies. This indicates an absence of a long-range ordered phase in the presence of random anisotropy disorder with a generic random axis distribution.
D Shapoval - One of the best experts on this subject based on the ideXlab platform.
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possibility of a continuous phase transition in random anisotropy magnets with a generic random axis distribution
Physical Review B, 2020Co-Authors: D Shapoval, M Dudka, Andrei A Fedorenko, Yu HolovatchAbstract:We reconsider the problem of the critical behavior of a three-dimensional $O(m)$ symmetric magnetic system in the presence of random-anisotropy disorder with a generic trimodal random-axis distribution. By introducing $n$ replicas to average over disorder it can be coarse grained to a ${\ensuremath{\phi}}^{4}$ theory with an $m\ifmmode\times\else\texttimes\fi{}n$ component order parameter and five coupling constants taken in the limit of $n\ensuremath{\rightarrow}0$. Using a field theory approach we renormalize the model to two-loop order and calculate the $\ensuremath{\beta}$ functions within the $\ensuremath{\varepsilon}$ expansion and directly in three dimensions. We analyze the corresponding renormalization group flows with the help of the Pad\'e-Borel resummation technique. We show that there is no Stable Fixed Point accessible from physical initial conditions whose existence was argued in previous studies. This may indicate the absence of a long-range ordered phase in the presence of random-anisotropy disorder with a generic random-axis distribution.
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on the possibility of a continuous phase transition in the random anisotropy magnets with a generic random axis distribution
arXiv: Disordered Systems and Neural Networks, 2019Co-Authors: D Shapoval, M Dudka, Andrei A Fedorenko, Yu HolovatchAbstract:We reconsider the problem of the critical behavior of a three-dimensional $O(m)$ symmetric magnetic system in the presence of random anisotropy disorder with a generic trimodal random axis distribution. By introducing $n$ replicas to average over disorder it can be coarse-grained to a $\phi^{4}$-theory with $m \times n$ component order parameter and five coupling constants taken in the limit of $n \to 0$. Using a field theory approach we renormalize the model to two-loop order and calculate the $\beta$-functions within the $\varepsilon$ expansion and directly in three dimensions. We analyze the corresponding renormalization group flows with the help of the Pade-Borel resummation technique. We show that there is no Stable Fixed Point accessible from physical initial conditions whose existence was argued in the previous studies. This indicates an absence of a long-range ordered phase in the presence of random anisotropy disorder with a generic random axis distribution.
Toby Wiseman - One of the best experts on this subject based on the ideXlab platform.
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Preprint typeset in JHEP style- HYPER VERSION Ricci solitons, Ricci flow, and strongly coupled CFT in
2016Co-Authors: Pau Figueras, James Lucietti, Toby WisemanAbstract:The elliptic Einstein-DeTurck equation may be used to numerically find Einstein metrics on Riemannian manifolds. Static Lorentzian Einstein metrics are considered by analyti-cally continuing to Euclidean time. Ricci-DeTurck flow is a constructive algorithm to solve this equation, and is simple to implement when the solution is a Stable Fixed Point, the only complication being that Ricci solitons may exist which are not Einstein. Here we extend previous work to consider the Einstein-DeTurck equation for Riemannian mani-folds with boundaries, and those that continue to static Lorentzian spacetimes which are asymptotically flat, Kaluza-Klein, locally AdS or have extremal horizons. Using a maxi-mum principle we prove that Ricci solitons do not exist in these cases and so any solution is Einstein. We also argue that Ricci-DeTurck flow preserves these classes of manifolds. As an example we simulate Ricci-DeTurck flow for a manifold with asymptotics relevant for AdS5/CFT4. Our maximum principle dictates there are no soliton solutions, and we give strong numerical evidence that there exists a Stable Fixed Point of the flow which continues to a smooth static Lorentzian Einstein metric. Our asymptotics are such that this describes the classical gravity dual relevant for the CFT on a Schwarzschild background in either the Unruh or Boulware vacua. It determines the leading O(N2c) part of the CFT stress tensor, which interestingly is regular on both the future and past Schwarzschild horizons. ar X i
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ricci solitons ricci flow and strongly coupled cft in the schwarzschild unruh or boulware vacua
Classical and Quantum Gravity, 2011Co-Authors: Pau Figueras, James Lucietti, Toby WisemanAbstract:The elliptic Einstein–DeTurck equation may be used to numerically find Einstein metrics on Riemannian manifolds. Static Lorentzian Einstein metrics are considered by analytically continuing to Euclidean time. The Ricci–DeTurck flow is a constructive algorithm to solve this equation, and is simple to implement when the solution is a Stable Fixed Point, the only complication being that Ricci solitons may exist which are not Einstein. Here we extend previous work to consider the Einstein–DeTurck equation for Riemannian manifolds with boundaries, and those that continue to static Lorentzian spacetimes which are asymptotically flat, Kaluza–Klein, locally AdS or have extremal horizons. Using a maximum principle, we prove that Ricci solitons do not exist in these cases and so any solution is Einstein. We also argue that the Ricci–DeTurck flow preserves these classes of manifolds. As an example, we simulate the Ricci–DeTurck flow for a manifold with asymptotics relevant for AdS5/CFT4. Our maximum principle dictates that there are no soliton solutions, and we give strong numerical evidence that there exists a Stable Fixed Point of the flow which continues to a smooth static Lorentzian Einstein metric. Our asymptotics are such that this describes the classical gravity dual relevant for the CFT on a Schwarzschild background in either the Unruh or Boulware vacua. It determines the leading O(N2c) part of the CFT stress tensor, which interestingly is regular on both the future and past Schwarzschild horizons.
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ricci solitons ricci flow and strongly coupled cft in the schwarzschild unruh or boulware vacua
arXiv: High Energy Physics - Theory, 2011Co-Authors: Pau Figueras, James Lucietti, Toby WisemanAbstract:The elliptic Einstein-DeTurck equation may be used to numerically find Einstein metrics on Riemannian manifolds. Static Lorentzian Einstein metrics are considered by analytically continuing to Euclidean time. Ricci-DeTurck flow is a constructive algorithm to solve this equation, and is simple to implement when the solution is a Stable Fixed Point, the only complication being that Ricci solitons may exist which are not Einstein. Here we extend previous work to consider the Einstein-DeTurck equation for Riemannian manifolds with boundaries, and those that continue to static Lorentzian spacetimes which are asymptotically flat, Kaluza-Klein, locally AdS or have extremal horizons. Using a maximum principle we prove that Ricci solitons do not exist in these cases and so any solution is Einstein. We also argue that Ricci-DeTurck flow preserves these classes of manifolds. As an example we simulate Ricci-DeTurck flow for a manifold with asymptotics relevant for AdS_5/CFT_4. Our maximum principle dictates there are no soliton solutions, and we give strong numerical evidence that there exists a Stable Fixed Point of the flow which continues to a smooth static Lorentzian Einstein metric. Our asymptotics are such that this describes the classical gravity dual relevant for the CFT on a Schwarzschild background in either the Unruh or Boulware vacua. It determines the leading O(N^2) part of the CFT stress tensor, which interestingly is regular on both the future and past Schwarzschild horizons.
