Linearly stable and causal relativistic first-order spin hydrodynamics

We derive equations of motion for dissipative spin hydrodynamics from kinetic theory up to first order in a gradient expansion. Choosing a specific form of the matching conditions, relating the change in the spin potential to the spin diffusion and spin energy, we then show that the equations of motion, linearized around homogeneous global equilibrium, are causal and stable in any Lorentz frame, if certain sufficient conditions on the transport coefficients are fulfilled.Comment: 16 page

Spin tensor and pseudo-gauges: from nuclear collisions to gravitational physics

The relativistic treatment of spin is a fundamental subject which has an old history. In various physical contexts it is necessary to separate the relativistic total angular momentum into an orbital and spin contribution. However, such decomposition is affected by ambiguities since one can always redefine the orbital and spin part through the so-called pseudo-gauge transformations. We analyze this problem in detail by discussing the most common choices of energy-momentum and spin tensor with an emphasis on their physical implications, and study the spin vector which is a pseudo-gauge invariant operator. We review the angular momentum decomposition as a crucial ingredient for the formulation of relativistic spin hydrodynamics and quantum kinetic theory with a focus on relativistic nuclear collisions, where spin physics has recently attracted significant attention. Furthermore, we point out the connection between pseudo-gauge transformations and the different definitions of the relativistic center of mass. Finally, we consider the Einstein-Cartan theory, an extension of conventional general relativity, which allows for a natural definition of the spin tensor.Comment: 23 page

Beyond Borders : The Impact of the Coronavirus Pandemic on Nagoya University’s International Programs

This paper provides a brief overview of the international programs at Nagoya University and outlines the characteristics of the Japan-in-Asia Cultural Studies Program (JACS). Besides, the pandemic's impact on international admissions at Nagoya University is discussed. Further, within the context of JACS, an attempt is made to explore the immense challenges the Japanese government’s restrictions on international travel posed for both students and faculty. It reflects on the lessons learned while navigating the complexities of the program amid a global crisis

Maturity Effects On Students Perceptions Of How Accounting Scandals Impact The Accounting Profession

This study examines the impact of recent ethical scandals on business students’ perceptions of the accounting profession and related regulatory reforms, and whether such perceptions may be differentiated by maturity.  Student maturity is distinguished by age, class standing, and number of accounting classes taken so far.    The study results are based on a survey of student perceptions regarding their understanding of recent accounting scandals and related regulations, the adequacy of the response (from the profession as well as Congress) to these scandals, and the ensuing viability of the accounting profession.  Student maturity is found to be a significant determinant of differentiation in these perceptions.  Among the results presented, it is interesting to note that more mature students perceive the accounting profession as being more viable than less mature students; however, less mature students purport to have a better understanding of the ethical scandals.  The findings of this study have important implications for academicians in their efforts to engage students in meaningful dialog regarding ethical and professional issues

Quantum kinetic theory with interactions for massive vector bosons

We present a derivation of quantum kinetic theory for massive spin-1 particles from the Wigner-function formalism up to first order in an $\hbar$-expansion, including a general interaction term. Both local and nonlocal contributions are computed in a covariant fashion. It is shown that, up to first order in $\hbar$, the collision term takes the same form as in the case of spin-1/2 particles.Comment: 22 pages, no figure

Pseudo-gauges and relativistic spin hydrodynamics for interacting Dirac and Proca fields

We present the explicit expressions of different pseudo-gauge transformations for Dirac and Proca fields considering a general interaction term. The particular case of the interaction of Dirac and Proca fields with a background electromagnetic field is also studied. Starting from the quantum kinetic theory with collisions derived from the Wigner-function formalism for massive spin-1/2 and spin-1 particles, we establish a connection between different pseudo-gauges and relativistic spin hydrodynamics. The physical implications of the various decompositions of orbital and spin angular momentum are discussed.Comment: 21 pages, no figure

Relativistic dissipative spin hydrodynamics from kinetic theory with a nonlocal collision term

We derive relativistic dissipative spin hydrodynamics from kinetic theory featuring a nonlocal collision term using the method of moments. In this framework, the components of the spin tensor are dynamical variables which obey relaxation-type equations. We find that the corresponding relaxation times are determined by the local part of the collision term, while the nonlocal part contributes to the Navier-Stokes terms in these equations of motion. The spin relaxation time scales are comparable to those of the usual dissipative currents. Finally, the Navier-Stokes limit of the Pauli-Lubanski vector receives contributions proportional to the shear tensor of the fluid, which implies that the polarization of hadrons observed in heavy-ion collisions is influenced by dissipative effects.Comment: 7 pages, 1 figur

Active vibration control of a double-curved shell structure using the example of stuttgart smartshell

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