Journal of Physics A: Mathematical and Theoretical最新文献_第10页

The Unruh–DeWitt model and its joint interacting Hilbert space 恩鲁-德威特模型及其联合作用希尔伯特空间

IF 2.1 3区物理与天体物理

Journal of Physics A: Mathematical and Theoretical Pub Date : 2024-07-23 DOI: 10.1088/1751-8121/ad6365

Erickson Tjoa and Finnian Gray

{"title":"The Unruh–DeWitt model and its joint interacting Hilbert space","authors":"Erickson Tjoa and Finnian Gray","doi":"10.1088/1751-8121/ad6365","DOIUrl":"https://doi.org/10.1088/1751-8121/ad6365","url":null,"abstract":"In this work we make the connection between the Unruh–DeWitt (UDW) particle detector model applied to quantum field theory in curved spacetimes and the rigorous construction of the spin-boson (SB) model. With some modifications, we show that existing results about the existence of a SB ground state can be adapted to the UDW model. In the most relevant scenario involving massless scalar fields in (3+1)-dimensional globally hyperbolic spacetimes, where the UDW model describes a simplified model of light–matter interaction, we argue that common choices of the spacetime smearing functions regulate the ultraviolet behaviour of the model but can still exhibit infrared (IR) divergences. In particular, this implies the well-known expectation that the joint interacting Hilbert space of the model cannot be described by the tensor product of a two-dimensional complex Hilbert space and the Fock space of the vacuum representation. We discuss the conditions under which this problem does not arise and the relevance of the operator-algebraic approach for better understanding of particle detector models and their applications.Our work clarifies the connection between obstructions due to Haag’s theorem and IR bosons in the SB models, and paves the way for more rigorous study of entanglement and communication in the UDW framework involving multiple detectors.","PeriodicalId":16763,"journal":{"name":"Journal of Physics A: Mathematical and Theoretical","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141777069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Multi-parameter quantum estimation of single- and two-mode pure Gaussian states 单模和双模纯高斯状态的多参数量子估算

IF 2.1 3区物理与天体物理

Journal of Physics A: Mathematical and Theoretical Pub Date : 2024-07-22 DOI: 10.1088/1751-8121/ad6364

Gabriele Bressanini, Marco G Genoni, M S Kim and Matteo G A Paris

引用次数: 0

Impact of ageing on structure of random sequentialadsorption packings of discorectangles 老化对圆盘状无序吸附填料结构的影响

IF 2 3区物理与天体物理

Journal of Physics A: Mathematical and Theoretical Pub Date : 2024-07-22 DOI: 10.1088/1751-8121/ad6652

N. Lebovka, L. A. Bulavin, V. I. Kovalchuk, Mykhaylo R Petryk, N. Vygornitskii

{"title":"Impact of ageing on structure of random sequentialadsorption packings of discorectangles","authors":"N. Lebovka, L. A. Bulavin, V. I. Kovalchuk, Mykhaylo R Petryk, N. Vygornitskii","doi":"10.1088/1751-8121/ad6652","DOIUrl":"https://doi.org/10.1088/1751-8121/ad6652","url":null,"abstract":"\u0000 The ageing processes in the systems of elongated particles (discorectangles) adsorbed on a plane was studied numerically. An off-lattice model with continuous positional and orientational degrees of freedom was tested. The initial jammed state was produced using the random sequential adsorption (RSA) model. The transition from the jammed to equilibrium states were performed via translational and rotational Brownian motions. An aspect ratio of the particles (length-to-width ratio) was varied within the range $varepsilon=1-12$. At $varepsilon < 10$ the relaxation into the isotropic state %with $S=0$ was always observed. In the intermediate range, $10 le varepsilon le 11$, the relaxation transition into the states with ordered domains was observed. Particularly, for $ varepsilon=10$ this transition was related with significant finite size scaling effects. For particles with $varepsilon=12$ formation of the large scale quasi-nematic domains and unlimited domain growth was observed. The impact of the relaxation on the domain structure, porosity, percolation connectivity and tracer particle diffusion in such barrier systems was also discussed.","PeriodicalId":16763,"journal":{"name":"Journal of Physics A: Mathematical and Theoretical","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141815359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Passive and active field theories for disease spreading 疾病传播的被动场和主动场理论

IF 2.1 3区物理与天体物理

Journal of Physics A: Mathematical and Theoretical Pub Date : 2024-07-21 DOI: 10.1088/1751-8121/ad4c31

Michael te Vrugt, Julian Jeggle and Raphael Wittkowski

{"title":"Passive and active field theories for disease spreading","authors":"Michael te Vrugt, Julian Jeggle and Raphael Wittkowski","doi":"10.1088/1751-8121/ad4c31","DOIUrl":"https://doi.org/10.1088/1751-8121/ad4c31","url":null,"abstract":"The worldwide COVID-19 pandemic has led to a significant growth of interest in the development of mathematical models that allow to describe effects such as social distancing measures, the development of vaccines, and mutations. Several of these models are based on concepts from soft matter theory. Considerably less well investigated is the reverse direction, i.e. how results from epidemiological research can be of interest for the physics of colloids and polymers. In this work, we consider the susceptible-infected-recovered (SIR)-dynamical density functional theory (DDFT) model, a combination of the SIR model from epidemiology with DDFT from nonequilibrium soft matter physics, which allows for an explicit modeling of social distancing. We extend the SIR-DDFT model both from an epidemiological perspective by incorporating vaccines, asymptomaticity, reinfections, and mutations, and from a soft matter perspective by incorporating noise and self-propulsion and by deriving a phase field crystal (PFC) model that allows for a simplified description. On this basis, we investigate via computer simulations how epidemiological models are affected by the presence of non-reciprocal interactions. This is done in a numerical study of a zombie outbreak.","PeriodicalId":16763,"journal":{"name":"Journal of Physics A: Mathematical and Theoretical","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141740040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Non-ultralocal classical r-matrix structure for 1+1 field analogue of elliptic Calogero–Moser model 椭圆卡洛吉罗-莫泽模型 1+1 场类似物的非超局域经典 r 矩阵结构

IF 2.1 3区物理与天体物理

Journal of Physics A: Mathematical and Theoretical Pub Date : 2024-07-21 DOI: 10.1088/1751-8121/ad5ee1

Andrei Zotov

引用次数: 0

Front stability of infinitely steep travelling waves in population biology 群体生物学中无限陡峭行波的前稳定性

IF 2.1 3区物理与天体物理

Journal of Physics A: Mathematical and Theoretical Pub Date : 2024-07-21 DOI: 10.1088/1751-8121/ad6223

Matthew J Simpson, Nizhum Rahman and Alexander K Y Tam

{"title":"Front stability of infinitely steep travelling waves in population biology","authors":"Matthew J Simpson, Nizhum Rahman and Alexander K Y Tam","doi":"10.1088/1751-8121/ad6223","DOIUrl":"https://doi.org/10.1088/1751-8121/ad6223","url":null,"abstract":"Reaction–diffusion models are often used to describe biological invasion, where populations of individuals that undergo random motility and proliferation lead to moving fronts. Many reaction–diffusion models of biological invasion are extensions of the well–known Fisher–Kolmogorov–Petrovskii–Piskunov model that describes the spatiotemporal evolution of a 1D population density, , as a result of linear diffusion with flux , and logistic growth source term, . In 2020 Fadai introduced a new reaction–diffusion model of biological invasion with a nonlinear degenerate diffusive flux, , and the model was formulated as a moving boundary problem on , with and at (Fadai and Simpson 2020 J. Phys. A: Math. Theor. 53 095601). Fadai’s model leads to travelling wave solutions with infinitely steep, well–defined fronts at the moving boundary, and the model has the mathematical advantage of being analytically tractable in certain parameter limits. In this work we consider the stability of the travelling wave solutions presented by Fadai. We provide general insight by first presenting two key extensions of Fadai’s model by considering: (i) generalised nonlinear degenerate diffusion with flux for some constant m > 0; and, (ii) solutions describing both biological invasion with , and biological recession with . After establishing the existence of travelling wave solutions for these two extensions, our main contribution is to consider stability of the travelling wave solutions by introducing a lateral perturbation of the travelling wavefront. Full 2D time–dependent level–set numerical solutions indicate that invasive travelling waves are stable to small amplitude lateral perturbations, whereas receding travelling waves are unstable. These preliminary numerical observations are corroborated through a linear stability analysis that gives more formal insight into short time growth/decay of wavefront perturbation amplitude. Julia–based software, including level–set algorithms, is available on Github to replicate all results in this study.","PeriodicalId":16763,"journal":{"name":"Journal of Physics A: Mathematical and Theoretical","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141740043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Helicity of magnetic fields associated with non-relativistic electron vortex beams 非相对论电子涡流束相关磁场的螺旋性

IF 2 3区物理与天体物理

Journal of Physics A: Mathematical and Theoretical Pub Date : 2024-07-19 DOI: 10.1088/1751-8121/ad65a2

N. Alsaawi, Vasileios E. Lembessis, A. Lyras, Mohamed Babiker, Jun Yuan

{"title":"Helicity of magnetic fields associated with non-relativistic electron vortex beams","authors":"N. Alsaawi, Vasileios E. Lembessis, A. Lyras, Mohamed Babiker, Jun Yuan","doi":"10.1088/1751-8121/ad65a2","DOIUrl":"https://doi.org/10.1088/1751-8121/ad65a2","url":null,"abstract":"\u0000 The helicities of the magnetic fields associated with non-relativistic electron vortex beams are considered for radially extended Bessel modes. Investigating the helicity density of this system lies in realizing the unique electric and magnetic properties of electron vortex beams that influence their interactions with matter. We have evaluated the vector potential components needed for the derivation of the magnetic helicity density and found that this has a non-zero distribution. This is attributed entirely to the cylindrically symmetric density flux of the electron beam, which scales with the winding number $ell$. It is also related to the magnetic moments of the electron oriented along the $z$-direction, giving rise to the $z$-component of the magnetic field. We obtain different helicity distributions for different signs of winding number $pmell$, which confirms the chiral character of the magnetic fields associated with the electron vortex beam. The physical consequences of taking the spin current density into consideration are also examined. This allows a comparison to be made between the evaluated total current helicities, one with and one without including the spin-polarization.","PeriodicalId":16763,"journal":{"name":"Journal of Physics A: Mathematical and Theoretical","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141823372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

On the integrability of three two-component bi-Hamiltonian systems 论三个双分量双哈密顿系统的可积分性

IF 2 3区物理与天体物理

Journal of Physics A: Mathematical and Theoretical Pub Date : 2024-07-19 DOI: 10.1088/1751-8121/ad65a1

L. Zang, Qian Zhang, Qingping Liu

引用次数: 0

Coagulation-flocculation process on a lattice: Monte Carlo simulations 晶格上的混凝-絮凝过程：蒙特卡罗模拟

IF 2.1 3区物理与天体物理

Journal of Physics A: Mathematical and Theoretical Pub Date : 2024-07-18 DOI: 10.1088/1751-8121/ad5e4d

Viktoria Blavatska, Jaroslav Ilnytskyi and Erkki Lähderanta

{"title":"Coagulation-flocculation process on a lattice: Monte Carlo simulations","authors":"Viktoria Blavatska, Jaroslav Ilnytskyi and Erkki Lähderanta","doi":"10.1088/1751-8121/ad5e4d","DOIUrl":"https://doi.org/10.1088/1751-8121/ad5e4d","url":null,"abstract":"Coagulation-flocculation, the physicochemical process widely used for purification a wastewater, is affected both by chemical details of involved polymers and by the statistics of their conformations on a large scale. The latter aspect is covered in this study by employing a coarse-grained modeling approach based on a combination of two paradigms of statistical mechanics. One is the self-avoiding walk (SAW) which generates a range of conformations for a linear polymer of NSAW monomers. Another one is a non-trivial diffusion limited aggregation (DLA) process of NDLA impurities (referred thereafter as ‘particles’) which describes their coagulation occurring with the probability (p = 1 recovers a standard DLA). DLA of diffusive particles is complemented by their irreversible adsorption on the SAW monomers occurring with the probability equal to one, both processes resulting in formation of the DLA-SAW agglomerates. The dynamics of formation of such agglomerates, as well as their fractal dimensions and internal structure are of practical interest. We consider a range of related characteristics, such as: (i) absolute Na and relative na adsorbing efficiencies of SAW; (ii) effective gyration radius of the DLA-SAW agglomerates; and (iii) the fractal dimension of these aggregates. These are studied within a wide range for each parameter from a set .","PeriodicalId":16763,"journal":{"name":"Journal of Physics A: Mathematical and Theoretical","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141740042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Lozenge tilings of a hexagon and q -Racah ensembles 六边形的菱形倾斜和 q -Racah 组合

IF 2 3区物理与天体物理

Journal of Physics A: Mathematical and Theoretical Pub Date : 2024-07-18 DOI: 10.1088/1751-8121/ad653d

M. Duits, Erik Duse, Wenkui Liu

{"title":"Lozenge tilings of a hexagon and \u0000 q\u0000 -Racah ensembles","authors":"M. Duits, Erik Duse, Wenkui Liu","doi":"10.1088/1751-8121/ad653d","DOIUrl":"https://doi.org/10.1088/1751-8121/ad653d","url":null,"abstract":"\u0000 We study the limiting behavior of random lozenge tilings of the hexagon with a $q$-Racah weight as the size of the hexagon grows large. Based on the asymptotic behavior of the recurrence coefficients of the $q$-Racah polynomials, we give a new proof for the fact that the height function for a random tiling concentrates near a deterministic limit shape and that the global fluctuations are described by the Gaussian Free Field. These results were recently proved using (dynamic) loop equation techniques. In this paper, we extend the recurrence coefficient approach that was developed for (dynamic) orthogonal polynomial ensembles to the setting of $q$-orthogonal polynomials. An interesting feature is that the complex structure is easily found from the limiting behavior of the (explicitly known) recurrence coefficients. A particular motivation for studying this model is that the variational characterization of the limiting height function has an inhomogeneous term. The study of the regularity properties of the minimizer for general variational problems with such inhomogeneous terms is a challenging open problem. In a general setup, we show that the variational problem gives rise to a natural complex structure associated with the same Beltrami equation as in the homogeneous situation. We also derive a relation between the complex structure and the complex slope. In the case of the $q$-Racah weighting of lozenge tilings of the hexagon, our representation of the limit shape and their fluctuations in terms of the recurrence coefficients allows us to verify this relation explicitly.","PeriodicalId":16763,"journal":{"name":"Journal of Physics A: Mathematical and Theoretical","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141826261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0