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arXiv 2022年

作者： Scapin, Nicolò Demou, Andreas D. Brandt, Luca Stockholm Sweden Computation-based Science and Technology Research Center The Cyprus Institute Nicosia Cyprus Trondheim Norway

We propose an analytical model to estimate the interface temperature ΘΓ and the Nusselt number Nu for an evaporating two-layer Rayleigh-Bénard configuration in statistically stationary conditions. The model is based on three assumptions: (i) the Oberbeck-Boussinesq approximation can be applied to the liquid phase, while the gas thermophysical properties are generic functions of thermodynamic pressure, local temperature, and vapour composition, (ii) the Grossmann-Lohse theory for thermal convection can be applied to the liquid and gas layers separately, (iii) the vapour content in the gas can be taken as the mean value at the gas-liquid interface. We validate this setting using direct numerical simulations (DNS) in a parameter space composed of the Rayleigh number (106 6 Ra 6 108) and the temperature differential (0.05 6 Ε 6 0.20), which modulates the variation of state variables in the gas layer. To better disentangle the variable property effects on ΘΓ and Nu, simulations are performed in two conditions. First, we consider the case of uniform gas properties except for the gas density and gas-liquid diffusion coefficient. Second, we include the variation of specific heat capacity, dynamic viscosity, and thermal conductivity using realistic equations of state. Irrespective of the employed setting, the proposed model agrees very well with the numerical simulations over the entire range of Ra − Ε investigated. © 2022, CC BY.

关键词： Gases

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Towards the determination of the 3-dimensional structure of the proton using lattice QCD simulations

arXiv

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arXiv 2024年

作者： Alexandrou, Constantia Bacchio, Simone Department of Physics University of Cyprus PO Box 20537 Nicosia1678 Cyprus Computation-based Science and Technology Research Center The Cyprus Institute 20 Konstantinou Kavafi str. Aglantzia2121 Cyprus

State-of-the-art lattice QCD simulations enable the evaluation of nucleon form factors and Mellin moments with controlled systematics, yielding results with unprecedented accuracy. At the same time, new theoretical approaches are allowing the direct computation of nucleon generalized parton distributions. We review recent lattice QCD results on these quantities that are paving the way for extracting a wealth of information on the 3-dimensional structure of the nucleon. © 2024, CC BY.

关键词： Quantum theory

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Tackling critical slowing down using global correction steps with equivariant flows: the case of the Schwinger model

arXiv

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arXiv 2022年

作者： Finkenrath, Jacob Computation-Based Science and Technology Research Center The Cyprus Institute 20 Konstantinou Kavafi Str. Nicosia2121 Cyprus

We propose a new method for simulating lattice gauge theories in the presence of fermions. The method combines flow-based generative models for local gauge field updates and hierarchical updates of the factorized fermion determinant. The flow-based generative models are restricted to proposing updates to gauge-fields within subdomains, thus keeping training times moderate while increasing the global volume. We apply our method performs to the 2-dimensional (2D) Schwinger model with Nf = 2 Wilson Dirac fermions and show that no critical slowing down is observed in the sampling of topological sectors up to β = 8.45. Furthermore, we show that fluctuations can be suppressed exponentially with the distance between active subdomains, allowing us to achieve acceptance rates of up to 99% for the outer-most accept/reject step on lattices volumes of up to V = 128 × 128. © 2022, CC BY.

关键词： Topology

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Generalized form factors of the pion and kaon using twisted mass fermions 40

Generalized form factors of the pion and kaon using twisted ...

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40th International Symposium on Lattice Field Theory, LATTICE 2023

作者： Delmar, Joseph Alexandrou, Constantia Bacchio, Simone Cloët, Ian Constantinou, Martha Koutsou, Giannis Department of Physics Temple University 1925 N.12th Street PhiladelphiaPA19122-1801 United States Department of Physics University of Cyprus P.O.Box 20537 Nicosia1678 Cyprus Computation-based Science and Technology Research Center The Cyprus Institute 20 Kavafi Str. Nicosia2121 Cyprus Physics Division Argonne National Laboratory LemontIL60439 United States

We present an update on our lattice calculations of the Mellin moments of PDFs and GPDs for the pion and kaon, using momentum-boosted meson *** particular, we focus on the calculation of the scalar and tensor local operators, and the vector operator with up to three-covariant *** corresponding matrix elements allow us to extract the scalar and tensor charges, as well as 〈xn〉 with n = 1, 2, *** addition, we introduce momentum transfer between the initial and final meson state that leads to the scalar, vector, and tensor form factors, and the generalized form factors up to three covariant *** above results are obtained using two ensembles of maximally twisted mass fermions with clover improvement with two degenerate light, a strange, and a charm quark (N f = 2 + 1 + 1) at lattice spacings of 0.093 fm and 0.081 *** pion mass of the ensembles is about 260 *** study excited-states effects by analyzing four values of the source-sink time separation (1.12-1.67 fm).We also examine discretization and volume *** lattice data are renormalized non-perturbatively, and the results are presented in the MS scheme at a scale of 2 GeV. © Copyright owned by the author(s) under the terms of the Creative Commons.

关键词： Tensors

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Low-lying baryon masses using twisted mass fermions ensembles at the physical pion mass

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Physical Review D 2023年第9期108卷 094510-094510页

作者： Constantia Alexandrou Simone Bacchio Georgios Christou Jacob Finkenrath Department of Physics University of Cyprus P.O. Box 20537 1678 Nicosia Cyprus Computation-based Science and Technology Research Center The Cyprus Institute 2121 Nicosia Cyprus University of Wuppertal 42119 Wuppertal Germany

We investigate the low-lying baryon spectrum using three Nf=2+1+1 ensembles simulated with physical values of the quark masses and lattice spacings of 0.080, 0.069 and 0.057 fm. The ensembles are generated using twisted mass clover-improved fermions and the Iwasaki gauge action. The spatial length is kept approximately the same at about 5.1 fm to 5.5 fm fulfilling the condition mπL>3.6. We investigate isospin splitting within isospin multiples and verify that for most cases the isospin splitting for these lattice spacing is consistent with zero. In the couple of cases, for which there is a nonzero value, in the continuum limit, the mass splitting goes to zero. The baryon masses are extrapolated to the continuum limit using the three Nf=2+1+1 ensembles and are compared to other recent lattice QCD results. For the strange and charm quark masses we find, respectively, ms(2 GeV)=99.2(2.7) MeV and mc(3 GeV)=1.015(39) GeV. The values predicted for the masses of the doubly charmed Ξcc⋆, Ωcc and Ωcc⋆ baryons are 3.676(55) GeV, 3.703(51) GeV and 3.803(50) GeV, respectively, and for the triply charmed Ωccc baryon is 4.785(71) GeV.

关键词： Baryons Gauge theories Quarks

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Inclusive Hadronic Decay Rate of the τ Lepton from Lattice QCD: The u¯s Flavor Channel and the Cabibbo Angle

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Physical Review Letters 2024年第26期132卷 261901-261901页

作者： Constantia Alexandrou Simone Bacchio Alessandro De Santis Antonio Evangelista Jacob Finkenrath Roberto Frezzotti Giuseppe Gagliardi Marco Garofalo Bartosz Kostrzewa Vittorio Lubicz Simone Romiti Francesco Sanfilippo Silvano Simula Nazario Tantalo Carsten Urbach Urs Wenger Department of Physics Computation-based Science and Technology Research Center Dipartimento di Fisica and Gaustrae 20 42119 Wuppertal Germany Istituto Nazionale di Fisica Nucleare HISKP (Theory) High Performance Computing and Analytics Lab Dipartimento di Matematica e Fisica Institute for Theoretical Physics Albert Einstein Center for Fundamental Physics

We present a lattice determination of the inclusive decay rate of the process τ↦Xusντ in which the τ lepton decays into a generic hadronic state Xus with u¯s flavor quantum numbers. Our results have been obtained in nf=2+1+1 isosymmetric QCD with full nonperturbative accuracy, without any operator product expansion approximation and, except for the presently missing long-distance isospin-breaking corrections, include a solid estimate of all sources of theoretical uncertainties. This has been possible by using the Hansen-Lupo-Tantalo method [M. Hansen et al., Phys. Rev. D 99, 094508 (2019)] that we have already successfully applied [A. Evangelista et al., Phys. Rev. D 108, 074513 (2023)] to compute the inclusive decay rate of the process τ↦Xudντ in the u¯d flavor channel. By combining our first-principles theoretical results with the presently available experimental data, we extract the Cabibbo-Kobayashi-Maskawa matrix element |Vus|, the Cabibbo angle, with a 0.9% accuracy, dominated by the experimental error.

关键词： Cabibbo–Kobayashi–Maskawa matrix Hadronic decays Lattice field theory Lattice gauge theory Lepton-hadron interactions Non-Abelian gauge theories Nonperturbative effects in field theory Phenomenology Quantum chromodynamics Strong interaction Total cross sections

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Noether supercurrent operator mixing from lattice perturbation theory 39

Noether supercurrent operator mixing from lattice perturbati...

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39th International Symposium on Lattice Field Theory, LATTICE 2022

作者： Bergner, G. Costa, M. Panagopoulos, H. Soler, I. Spanoudes, G. University of Jena Institute for Theoretical Physics Max-Wien-Platz 1 JenaD-07743 Germany Department of Physics University of Cyprus 1 Panepistimiou Avenue Aglantzia Nicosia2109 Cyprus Department of Chemical Engineering Cyprus University of Technology 30 Archbishop Kyprianou Str. Limassol3036 Cyprus Computation-based Science and Technology Research Center The Cyprus Institute 20 Kavafi Str. Nicosia2121 Cyprus

In this work we present perturbative results for the renormalization of the supercurrent operator, Sµ, in N = 1 Supersymmetric Yang-Mills theory. At the quantum level, this operator mixes with both gauge invariant and noninvariant operators, which have the same global transformation properties. In total, there are 13 linearly independent mixing operators of the same and lower dimensionality. We determine, via lattice perturbation theory, the first two rows of the mixing matrix, which refer to the renormalization of Sµ, and of the gauge invariant mixing operator, Tµ. To extract these mixing coefficients in the MS renormalization scheme and at one-loop order, we compute the relevant two-point and three-point Green's functions of Sµ and Tµ in two regularizations: dimensional and lattice. On the lattice, we employ the plaquette gluonic action and for the gluinos we use the fermionic Wilson action with clover improvement. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).

关键词： Gages

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Shared-Space Autoencoders with Randomized Skip Connections for Building Footprint Detection with Missing Views 25th

Shared-Space Autoencoders with Randomized Skip Connections f...

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25th International Conference on Pattern Recognition Workshops, ICPR 2020

作者： Ashiotis, Giannis Oldfield, James Chrysostomou, Charalambos Christoudias, Theodoros Nicolaou, Mihalis A. Computation-Based Science and Technology Research Center The Cyprus Institute Lefkosia Cyprus Climate and Atmosphere Research Center The Cyprus Institute Lefkosia Cyprus School of Electronic Engineering and Computer Science Queen Mary University of London London United Kingdom

ISBN: (纸本)9783030687861

Recently, a vast amount of satellite data has become available, going beyond standard optical (EO) data to other forms such as synthetic aperture radars (SAR). While more robust, SAR data are often more difficult to interpret, can be of lower resolution, and require intense pre-processing compared to EO data. On the other hand, while more interpretable, EO data often fail under unfavourable lighting, weather, or cloud-cover conditions. To leverage the advantages of both domains, we present a novel autoencoder-based architecture that is able to both (i) fuse multi-spectral optical and radar data in a common shared-space, and (ii) perform image segmentation for building footprint detection under the assumption that one of the data modalities is missing–resembling a situation often encountered under real-world settings. To do so, a novel randomized skip-connection architecture that utilizes autoencoder weight-sharing is designed. We compare the proposed method to baseline approaches relying on network fine-tuning, and established architectures such as UNet. Qualitative and quantitative results show the merits of the proposed method, that outperforms all compared techniques for the task-at-hand. © 2021, Springer Nature Switzerland AG.

关键词： Synthetic aperture radar

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Nucleon electromagnetic form factors using Nf=2+1+1 twisted mass fermion ensembles at the physical mass point 39

Nucleon electromagnetic form factors using Nf=2+1+1 twisted ...

引用

39th International Symposium on Lattice Field Theory, LATTICE 2022

作者： Alexandrou, C. Bacchio, S. Constantinou, M. Finkenrath, J. Hadjiyiannakou, K. Jansen, K. Koutsou, G. Spanoudes, G. Department of Physics University of Cyprus P.O. Box 20537 Nicosia1678 Cyprus Computation-based Science and Technology Research Center The Cyprus Institute 20 Konstantinou Kavafi Str. Nicosia2121 Cyprus Temple University 1801 N Broad Str. PhiladelphiaPA19122 United States DESY-Zeuthen 6 Platanenallee Str. Zeuthen15738 Germany

We present results for the nucleon electromagnetic form factors using N f =2+1+1 twisted mass lattice QCD with clover improvement and with quark masses tuned to their physical values. Our preliminary analysis includes three ensembles at similar physical volume and varying lattice spacing allowing us to take the continuum limit at the physical point. Both connected and disconnected contributions are evaluated, allowing us to take the isovector and isoscalar contributions as well as the individual proton and neutron form factors in the flavour isospin limit. For each ensemble we assess excited state effects using several sink-source time separations in the range 0.8 fm - 1.6 fm, exponentially increasing statistics with the separation. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).

关键词： Excited states

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Low-lying baryon masses using twisted mass fermions ensembles at the physical pion mass

arXiv

引用

arXiv 2023年

作者： Alexandrou, Constantia Bacchio, Simone Christou, Georgios Finkenrath, Jacob Department of Physics University of Cyprus P.O. Box 20537 Nicosia1678 Cyprus Computation-based Science and Technology Research Center The Cyprus Institute Nicosia Cyprus University of Wuppertal Wuppertal Germany

We investigate the low-lying baryon spectrum using three Nf = 2 + 1 + 1 ensembles simulated with physical values of the quark masses and lattice spacings of 0.080, 0.069 and 0.057 fm. The ensembles are generated using twisted mass clover-improved fermions and the Iwasaki gauge action. The spatial length is kept approximately the same at about 5.1 fm to 5.5 fm fulfilling the condition mπL > 3.6. We investigate isospin splitting within isospin multiples and verify that for most cases the isospin splitting for these lattice spacing is consistent with zero. In the couple of cases, for which there is a non-zero value, in the continuum limit, the mass splitting goes to zero. The baryon masses are extrapolated to the continuum limit using the three Nf = 2 + 1 + 1 ensembles and are compared to other recent lattice QCD results. For the strange and charm quark masses we find, respectively, ms(2 GeV) = 99.2(2.7) MeV and mc(3 GeV) = 1.015(39) GeV. The values predicted for the masses of the doubly charmed Ξ★cc, Ωcc and Ω★cc baryons are 3.676(55) GeV, 3.703(51) GeV and 3.803(50) GeV, respectively, and for the triply charmed Ωccc baryon is 4.785(71) GeV. © 2023, CC BY.

关键词： Germanium alloys

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