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Energy–momentum tensor of a causally disconnected region of the Universe and the possibility of model verification 宇宙因果分离区域的能量-动量张量及模型验证的可能性
IF 1.1 4区 物理与天体物理
Theoretical and Mathematical Physics Pub Date : 2026-05-26 DOI: 10.1134/S0040577926050107
V. I. Kochkin
{"title":"Energy–momentum tensor of a causally disconnected region of the Universe and the possibility of model verification","authors":"V. I. Kochkin","doi":"10.1134/S0040577926050107","DOIUrl":"10.1134/S0040577926050107","url":null,"abstract":"<p> We study the possibility of verifying a phenomenological model where dark energy, in the form of a cosmological constant, is identified with the average value of the energy–momentum tensor of a causally disconnected region. We show that the model under consideration does not contradict observational results. Furthermore, we propose an explanation for the significant difference between the coefficients of the square of the scalar curvature in the Starobinsky model and in the semiclassical gravity model that accounts for quantum corrections in the gravitational action. </p>","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"227 2","pages":"880 - 887"},"PeriodicalIF":1.1,"publicationDate":"2026-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148009759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 variance of measurable operators 关于可测算子的方差
IF 1.1 4区 物理与天体物理
Theoretical and Mathematical Physics Pub Date : 2026-05-26 DOI: 10.1134/S0040577926050120
A. M. Bikchentaev, V. Zh. Sakbaev
{"title":"On the variance of measurable operators","authors":"A. M. Bikchentaev,&nbsp;V. Zh. Sakbaev","doi":"10.1134/S0040577926050120","DOIUrl":"10.1134/S0040577926050120","url":null,"abstract":"<p> We study the block projection operator <span>(mathcal{P}_n)</span>, <span>(n geq 2)</span>, in the <span>(*)</span>-algebra <span>(S(mathcal{M}, tau))</span> of all <span>(tau)</span>-measurable operators, where <span>(tau)</span> is a faithful normal semi-finite trace on the von Neumann algebra <span>(mathcal{M})</span>. For a state <span>(tau)</span>, we study the variance <span>(mathbb D)</span> of an operator from <span>(L_2(mathcal{M},tau))</span>. These results are new, even for the <span>(*)</span>-algebra <span>(mathcal{M}=mathcal{B}(mathcal{H}))</span> of all bounded linear operators in <span>(mathcal{H})</span> equipped with canonical trace <span>(tau =mathrm{tr})</span>. For a random bounded linear operator <span>(mathbf{A})</span> in a Hilbert space <span>(mathcal{H})</span>, we consider the operator-valued random variance <span>(mathbf{D}(mathbf{A}))</span>, which is used to investigate the validity of the law of large numbers for the product of independent identically distributed semigroups of bounded linear operators. We present conditions on a bounded self-adjoint operator <span>(Xin mathcal{B}(mathcal{H}))</span> and on a random operator <span>(mathbf{A})</span>, whose variances are related as <span>(mathbb{D}(X)=tau (mathbf{D}(mathbf{A})))</span>. </p>","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"227 2","pages":"903 - 923"},"PeriodicalIF":1.1,"publicationDate":"2026-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148009764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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
The random rotation model with a nonlocal interaction potential. An optimal result on Anderson localization 具有非局部相互作用势的随机旋转模型。安德森定位的最优结果
IF 1.1 4区 物理与天体物理
Theoretical and Mathematical Physics Pub Date : 2026-05-26 DOI: 10.1134/S0040577926050041
V. A. Chulaevsky
{"title":"The random rotation model with a nonlocal interaction potential. An optimal result on Anderson localization","authors":"V. A. Chulaevsky","doi":"10.1134/S0040577926050041","DOIUrl":"10.1134/S0040577926050041","url":null,"abstract":"<p> We prove spectral and strong dynamical localization in a periodic lattice of arbitrary dimension, with the disorder generated solely by randomly rotated asymmetric site potentials of infinite range. These results are proved under the optimal assumption of summable power-law decay of the sign-indefinite site potentials. Earlier results usually assumed the disorder to be generated either by random amplitudes, or by random local displacements of the site potentials, and often required these potentials to be sign-definite. </p>","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"227 2","pages":"787 - 805"},"PeriodicalIF":1.1,"publicationDate":"2026-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148009767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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
Sum formula for the overlaps of Bethe vectors 贝特向量重叠的求和公式
IF 1.1 4区 物理与天体物理
Theoretical and Mathematical Physics Pub Date : 2026-05-26 DOI: 10.1134/S004057792605003X
N. A. Slavnov
{"title":"Sum formula for the overlaps of Bethe vectors","authors":"N. A. Slavnov","doi":"10.1134/S004057792605003X","DOIUrl":"10.1134/S004057792605003X","url":null,"abstract":"<p> The <span>(XXZ)</span> Heisenberg spin chain is considered. We calculate the overlaps of the Bethe vectors corresponding to different anisotropy parameters. A sum formula for the overlap of off-shell Bethe vectors is obtained. We derive a recurrence relation for the highest coefficient. </p>","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"227 2","pages":"775 - 786"},"PeriodicalIF":1.1,"publicationDate":"2026-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148009806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 isomorphism between the Kozlov problem on ferromagnetic motion in a magnetic field and the Schottky problem on four-dimensional solid motion 磁场中铁磁运动的Kozlov问题与四维固体运动的Schottky问题的同构性
IF 1.1 4区 物理与天体物理
Theoretical and Mathematical Physics Pub Date : 2026-05-26 DOI: 10.1134/S0040577926050089
A. V. Tsiganov, E. O. Porubov
{"title":"On the isomorphism between the Kozlov problem on ferromagnetic motion in a magnetic field and the Schottky problem on four-dimensional solid motion","authors":"A. V. Tsiganov,&nbsp;E. O. Porubov","doi":"10.1134/S0040577926050089","DOIUrl":"10.1134/S0040577926050089","url":null,"abstract":"<p> The theory of tensor invariants for ordinary differential equations and Cartan classification of simple Lie algebras are used to establish an isomorphism between the Kozlov problem on ferromagnetic motion in a magnetic field and the Schottky problem on four-dimensional solid motion. We derived new polynomial and rational Poisson bivectors which are invariant either with respect to the pair of commuting phase flows or with respect to one of the pair of flows. </p>","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"227 2","pages":"845 - 862"},"PeriodicalIF":1.1,"publicationDate":"2026-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148009766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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
Hydromagnetic nanofluid flow over a shrinking sheet with nonlinear thermal radiation and dissipation effects 具有非线性热辐射和耗散效应的磁纳米流体在收缩片上的流动
IF 1.1 4区 物理与天体物理
Theoretical and Mathematical Physics Pub Date : 2026-05-26 DOI: 10.1134/S0040577926050090
S. Mekala, S. Sureshkumar, P. Suriyakumar, Ali J. Chamkha
{"title":"Hydromagnetic nanofluid flow over a shrinking sheet with nonlinear thermal radiation and dissipation effects","authors":"S. Mekala,&nbsp;S. Sureshkumar,&nbsp;P. Suriyakumar,&nbsp;Ali J. Chamkha","doi":"10.1134/S0040577926050090","DOIUrl":"10.1134/S0040577926050090","url":null,"abstract":"<p> This study presents a two-phase revised model for the magnetically enhanced nanofluid flow over a nonlinearly shrinking sheet, incorporating the effects of nonlinear thermal radiation and viscous dissipation. The analysis considers both the base fluid and nanoparticles as distinct phases, accounting for their interactions to enhance heat transfer characteristics. Using similarity transformations, the controlling PDEs are converted into a system of ODEs that are numerically solved. The impact of key physical parameters, including magnetic intensity, thermal radiation, and viscous dissipation on flow velocity and temperature distributions is thoroughly examined. Results indicate that increasing nonlinear thermal radiation enhances heat transfer, while viscous dissipation contributes to temperature rise, affecting the stability of the boundary layer. The findings offer valuable insights into industrial applications such as thermal coatings, cooling systems, and nanofluid-based energy transport. </p>","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"227 2","pages":"863 - 879"},"PeriodicalIF":1.1,"publicationDate":"2026-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148009828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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
Self-adjoint operators in the Smolyanov–Shamarov space Smolyanov-Shamarov空间中的自伴随算子
IF 1.1 4区 物理与天体物理
Theoretical and Mathematical Physics Pub Date : 2026-04-23 DOI: 10.1134/S0040577926040021
M. G. Shelakov
{"title":"Self-adjoint operators in the Smolyanov–Shamarov space","authors":"M. G. Shelakov","doi":"10.1134/S0040577926040021","DOIUrl":"10.1134/S0040577926040021","url":null,"abstract":"<p> We prove the essential self-adjointness of the Laplace–Volterra operator in the Smolyanov–Shamarov space, i.e., in the space of functions defined on a real infinite-dimensional separable Hilbert space and square-integrable with respect to a generalized Lebesgue–Feynman–Smolyanov–Shamarov measure. To prove this, we first prove the essential self-adjointness of the operator of multiplication by a quadratic function with a kernel operator. Then we apply the infinite-dimensional Fourier transform, mapping functions from an infinite-dimensional analogue of the Schwartz space to functions from the same space. Furthermore, a consequence of one of the proved theorems is the separability of the Smolyanov–Shamarov space. </p>","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"227 1","pages":"592 - 604"},"PeriodicalIF":1.1,"publicationDate":"2026-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147733134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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
The Lie algebraic construction for the coupled Toda hierarchy 耦合Toda层次的李代数构造
IF 1.1 4区 物理与天体物理
Theoretical and Mathematical Physics Pub Date : 2026-04-23 DOI: 10.1134/S0040577926040057
Xiaojuan Duan, Jipeng Cheng
{"title":"The Lie algebraic construction for the coupled Toda hierarchy","authors":"Xiaojuan Duan,&nbsp;Jipeng Cheng","doi":"10.1134/S0040577926040057","DOIUrl":"10.1134/S0040577926040057","url":null,"abstract":"<p> By utilizing the vertex operator formulation of the polynomial Lie algebra <span>(gl_infty^{(n)})</span>, we develop a representation-theoretic framework for the coupled Toda hierarchy, which is a special matrix-type Toda hierarchy. This approach not only provides a deeper understanding of its algebraic structure but also allows us to derive the Hirota bilinear form for the coupled <span>(2)</span>-Toda hierarchy. Starting from the bilinear relation of the wave-function matrix, we construct the associated dressing operator matrix, which in turn enables us to define the Lax operator matrix and derive the corresponding Lax equation. </p>","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"227 1","pages":"630 - 644"},"PeriodicalIF":1.1,"publicationDate":"2026-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147733145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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
Direct sampling method for the inverse elastic wave scattering problem 弹性波反散射问题的直接抽样方法
IF 1.1 4区 物理与天体物理
Theoretical and Mathematical Physics Pub Date : 2026-04-23 DOI: 10.1134/S0040577926040045
Hong Guo, Jin Huang, Zhaoxing Li
{"title":"Direct sampling method for the inverse elastic wave scattering problem","authors":"Hong Guo,&nbsp;Jin Huang,&nbsp;Zhaoxing Li","doi":"10.1134/S0040577926040045","DOIUrl":"10.1134/S0040577926040045","url":null,"abstract":"<p> This paper solves the inverse elastic wave scattering problem using the direct sampling method. Based on the scattered field of the elastic wave, a new indicator function is introduced, and the theoretical analysis is carried out, which demonstrates the effectiveness of our method. In practice, the scattered data may contain noise, and a modified indicator function is developed; furthermore, the stability analysis is also implemented to confirm the robustness of the proposed approach. Numerical examples are provided to clarify the effectiveness and robustness of our method. </p>","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"227 1","pages":"617 - 629"},"PeriodicalIF":1.1,"publicationDate":"2026-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147733143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 geometry of compact statistical manifolds equipped with a concircular vector field 具有共圆矢量场的紧致统计流形的几何性质
IF 1.1 4区 物理与天体物理
Theoretical and Mathematical Physics Pub Date : 2026-04-23 DOI: 10.1134/S0040577926040033
F. Asali, M. B. Kazemi Balgeshir
{"title":"On the geometry of compact statistical manifolds equipped with a concircular vector field","authors":"F. Asali,&nbsp;M. B. Kazemi Balgeshir","doi":"10.1134/S0040577926040033","DOIUrl":"10.1134/S0040577926040033","url":null,"abstract":"<p> In this paper we introduce and study the properties of a statistical concircular vector field and the Laplacian of a smooth function on a statistical manifold endowed with the dual connection <span>(nabla^*)</span>. Focusing on the compact case, we obtain the fundamental integral formula for a statistical Ricci tensor <span>(mathcal Rc)</span> : </p><p> We prove that if a compact, connected statistical manifold <span>((W^m,nabla^*,h))</span> admits a nontrivial statistical concircular vector field <span>(nabla^*psi)</span> and its statistical Ricci curvature satisfies a specific lower bound condition on the first eigenvalue of the statistical Laplacian <span>(Delta^*)</span>, then the manifold must be isometric to a standard sphere <span>(S^m(a))</span>. </p>","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"227 1","pages":"605 - 616"},"PeriodicalIF":1.1,"publicationDate":"2026-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147733138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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
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