arXiv subjects

R. Kirschner

Publications and source records attributed to R. Kirschner.

At least 19 recordsLinked to original sources

arXiv2025

Intertwiners of Yangian representations

We construct type $g\ell(n)$ Yangian algebra evaluations of order $N$ embedded in Heisenberg algebras and consider their representations having a highest weight. These Yangian algebra presentations depend on $nN$ parameters. We construct explicitly intertwiners, which exist if the parameter arrays are related by permutations. The intertwiners are products of elementary adjacent parameter permutation operators derived from $R$ operators obeying Yang-Baxter relations. Permutation coefficients appear in the action on representations. Their dependence on the parameters allows to distinguish the types of representations.

math.QA↗

arXiv2025

Quantum Internet Use Case Analysis for the Automotive Industry

A future quantum internet brings promising applications related to security, privacy and enabling distributed quantum computing. Integration of these concepts into the future trends of the automotive sector is of considerable interest, as it enables both the development of practical quantum internet use cases and the adoption of innovative technologies in the automotive sector. In this work we analyze cross-platform megatrends in both the quantum internet and the automotive industry, identifying mutually beneficial regions of interest. In the short-term ($<10$ years) hardware miniaturization and automation of quantum internet technology provides a synergy interface between the two domains. For the long-term ($\geq10$ years) we develop a comprehensive list of use cases for the quantum internet within the automotive sector. We find considerable relevancy of augmenting autonomous driving, vehicle ad hoc networks and sensor fusion with blind quantum computing, anonymous transmission and quantum cryptographic tools. These results can be used to target future research, engineering and venture developments for both domains. Furthermore, our approach can be applied to other industries, enabling a structured methodology for identifying and developing feasible use cases for the quantum internet in diverse domains.

quant-ph↗

arXiv2023

Yangian symmetry applied to Quantum chromodynamics

We review applications of Yangain symmetry to high-energy QCD phenomenology. Some basic facts about high-energy QCD are recalled, in particular the spinor-helicity form of scattering amplitudes, the scale evolution equations of deep-inelastic scattering structure functions and the high-energy asymptotics of scattering. As the working tool the Yangian symmetric correlators are introduced and constructed in the framework of the Yangian algebra of $g\ell(n)$ type. We present the application to the tree scattering amplitudes and their iterative relation, to the parton splitting amplitudes and the kernels of the scale evolution equations of structure functions and to the equations describing the high-energy asymptotics of scattering.

hep-th↗

arXiv2020

Representations of orthogonal and symplectic Yangians

Exteded Yangian algebras of orthogonal and symplectic types are defined by the Yang-Baxter RLL relation involving the fundamental R-matrix with $so(n)$ or $sp(2m)$ symmetry. We study representations of highest weight characterized by weight function ratios. We consider the algebra relations for the linear and the quadratic evaluations and the resulting conditions imposed on the representation weights. We present expressions of L-operators constructed on underlying Clifford and Heisenberg algebras and characterize their representations.

math-ph↗

arXiv2020

Yang-Baxter R-operators for osp superalgebras

We study Yang-Baxter equations with orthosymplectic supersymmetry. We extend a new approach of the construction of the spinor and metaplectic $\hat{\cal R}$-operators with orthogonal and symplectic symmetries to the supersymmetric case of orthosymplectic symmetry. In this approach the orthosymplectic $\hat{\cal R}$-operator is given by the ratio of two operator valued Euler Gamma-functions. We illustrate this approach by calculating such $\hat{\cal R}$ operators in explicit form for special cases of the $osp(n|2m)$ algebra, in particular for a few low-rank cases. We also propose a novel, simpler and more elegant, derivation of the Shankar-Witten type formula for the $osp$ invariant $\hat{\cal R}$-operator and demonstrate the equivalence of the previous approach to the new one in the general case of the $\hat{\cal R}$-operator invariant under the action of the $osp(n|2m)$ algebra.

math-ph↗

arXiv2019

Spinorial R operator and Algebraic Bethe Ansatz

We propose a new approach to the spinor-spinor R-matrix with orthogonal and symplectic symmetry. Based on this approach and the fusion method we relate the spinor-vector and vector-vector monodromy matrices for quantum spin chains. We consider the explicit spinor R matrices of low rank orthogonal algebras and the corresponding RTT algebras. Coincidences with fundamental R matrices allow to relate the Algebraic Bethe Ansatz for spinor and vector monodromy matrices.

math-ph↗

arXiv2018

QCD at high energies and Yangian symmetry

Yangian symmetric correlators provide a tool to investigate integrability features of QCD at high energies. We discuss the kernel of the equation of perturbative Regge asymptotics, the kernels of the evolution equation of parton distributions, Born scattering amplitudes and coupling renormalization.

hep-th↗

arXiv2017

Orthogonal and symplectic Yangians - linear and quadratic evaluations

Orthogonal or symplectic Yangians are defined by the Yang-Baxter $RLL$ relation involving the fundamental $R$ matrix with $so(n)$ or $sp(2m)$ symmetry. Simple $L$ operators with linear or quadratic dependence on the spectral parameter exist under restrictive conditions. These conditions are investigated in general form.

math-ph↗

arXiv2016

Yangians and Yang-Baxter R-operators for ortho-symplectic superalgebras

Yang-Baxter relations symmetric with respect to the ortho-symplectic superalgebras are studied. We start from the formulation of graded algebras and the linear superspace carrying the vector (fundamental) representation of the ortho-symplectic supergroup. On this basis we study the analogy of the Yang-Baxter operators considered earlier for the cases of orthogonal and symplectic symmetries: the vector (fundamental) R matrix, the L operator defining the Yangian algebra and its first and second order evaluations. We investigate the condition for L(u) in the case of the truncated expansion in inverse powers of u and give examples of Lie algebra representations obeying these conditions. We construct the R operator intertwining two super-spinor representations and study the fusion of L operators involving the tensor product of such representations.

math-ph↗

arXiv2016

Correlators with $s\ell_2$ Yangian symmetry

Correlators based on $s\ell_2$ Yangian symmetry and its quantum deformation are studied. Symmetric integral operators can be defined with such correlators as kernels. Yang-Baxter operators can be represented in this way. Particular Yangian symmetric correlators are related to the kernels of QCD parton evolution. The solution of the eigenvalue problem of Yangian symmetric operators is described.

hep-th↗

arXiv2015

Orthogonal and symplectic Yangians and Yang-Baxter R-operators

Yang-Baxter R operators symmetric with respect to the orthogonal and symplectic algebras are considered in an uniform way. Explicit forms for the spinorial and metaplectic R operators are obtained. L operators, obeying the RLL relation with the orthogonal or symplectic fundamental R matrix, are considered in the interesting cases, where their expansion in inverse powers of the spectral parameter is truncated. Unlike the case of special linear algebra symmetry the truncation results in additional conditions on the Lie algebra generators of which the L operators is built and which can be fulfilled in distinguished representations only. Further, generalised L operators, obeying the modified RLL relation with the fundamental R matrix replaced by the spinorial or metaplectic one, are considered in the particular case of linear dependence on the spectral parameter. It is shown how by fusion with respect to the spinorial or metaplectic representation these first order spinorial L operators reproduce the ordinary L operators with second order truncation.

math-ph↗

arXiv2014

Yang-Baxter operators and scattering amplitudes in $\mathcal{N} = 4$ super-Yang-Mills theory

Yangian symmetry of amplitudes in $\mathcal{N}=4$ super Yang-Mills theory is formulated in terms of eigenvalue relations for monodromy matrix operators. The Quantum Inverse Scattering Method provides the appropriate tools to treat the extended symmetry and to recover as its consequences many known features like cyclic and inversion symmetry, BCFW recursion, Inverse Soft Limit construction, Grassmannian integral representation, $\mathrm{R}$-invariants and on-shell diagram approach.

hep-th↗

arXiv2013

Yangian symmetric correlators

Similarity transformations and eigenvalue relations of monodromy operators composed of Jordan-Schwinger type L matrices are considered and used to define Yangian symmetric correlators of n-dimensional theories. Explicit expressions are obtained and relations are formulated. In this way basic notions of the Quantum inverse scattering method provide a convenient formulation for high symmetry and integrability not only in lower dimensions.

math-ph↗

arXiv2012

Baxter operators with deformed symmetry

Baxter operators are constructed for quantum spin chains with deformed $s\ell_2$ symmetry. The parallel treatment of Yang-Baxter operators for the cases of undeformed, trigonometrically and elliptically deformed symmetries presented earlier and relying on the factorization regarding parameter permutations is extended to the global chain operators following the scheme worked out recently in the undeformed case.

math-ph↗

arXiv2011

Baxter operators for arbitrary spin

We construct Baxter operators for the homogeneous closed $\mathrm{XXX}$ spin chain with the quantum space carrying infinite or finite dimensional $s\ell_2$ representations. All algebraic relations of Baxter operators and transfer matrices are deduced uniformly from Yang-Baxter relations of the local building blocks of these operators. This results in a systematic and very transparent approach where the cases of finite and infinite dimensional representations are treated in analogy. Simple relations between the Baxter operators of both cases are obtained. We represent the quantum spaces by polynomials and build the operators from elementary differentiation and multiplication operators. We present compact explicit formulae for the action of Baxter operators on polynomials.

hep-th↗

arXiv2011

Baxter operators for arbitrary spin II

This paper presents the second part of our study devoted to the construction of Baxter operators for the homogeneous closed XXX spin chain with the quantum space carrying infinite or finite-dimensional $s\ell_2$ representations. We consider the Baxter operators used in \cite{BLZ,Shortcut}, formulate their construction uniformly with the construction of our previous paper. The building blocks of all global chain operators are derived from the general Yang-Baxter operators and all operator relations are derived from general Yang-Baxter relations. This leads naturally to the comparison of both constructions and allows to connect closely the treatment of the cases of infinite-dimensional representation of generic spin and finite-dimensional representations of integer or half-integer spin. We proof not only the relations between the operators but present also their explicit forms and expressions for their action on polynomials representing the quantum states.

hep-th↗

arXiv2009

Small x resummation in collinear factorisation

The summation of the small x-corrections to hard-scattering QCD amplitudes by collinear factorisation method is reconsidered and the K-factor is derived in leading ln x approximation with a result differing from the corresponding expression by Catani and Hautmann (Nucl. Phys. B 427, 475, 1994). The significance of the difference is demonstrated in the examples of structure function F_L and of exclusive vector meson electroproduction. The formulation covers the channels of non-vanishing conformal spin n paving the way for new applications.

hep-ph↗

arXiv2009

Resummation of small x contributions to hard-scattering amplitudes

The summation of the small x corrections to hard scattering QCD amplitudes by collinear factorisation method is reconsidered and the K-factor is derived in leading log x approximation. The corresponding expression by Catani and Hautmann (1994) has to be corrected. The significance of the correction is demonstrated in the examples of structure function F_L and of exclusive electroproduction.

hep-ph↗