Skip to content
Free planNo credit card requiredStart writing
AI for Research home
AI for Research home
Dashboard
Sign inGet started

Search 250 million research papers

Read the abstract, see who wrote it and who cites it, and get the citation in APA, MLA, Chicago or Harvard.

About 10,000 papers for “Conserved current”

Conserved photon current

Margaret Hawton · Physical review. A/Physical review, A · 2024

A conserved photon current is derived from the commutation relations satisfied by the electromagnetic four-potential and field tensor operators. The density is found to be a sum over positive and negative frequency terms, both of which contribute a positive number density and propagate in a common direction. Discrete positive and negative frequency excitations are both identified as photons. The photon number, equal to the spatial integral of the photon density, is conserved in the absence of sources and sinks.

Cited by 1

Meson couplings from conserved vector current and partially conserved axial-vector current

W. Weihofen · Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields · 1974

By requiring only that conserved vector current (CVC) and partially conserved axial-vector current (PCAC) be expressed by the field equations, a matrix formalism is developed for the nonlinear meson Lagrangian density, incorporating both conditions in any group representation. The pseudoscalar-meson "mass term" is given explicitly. The concept of the chiral covariant derivative is employed to treat a general system of vector, axial-vector, and pseudoscalar mesons in an elegant manner. In the context of invariant pseudoscalar-meson coupling constant $f$ ($\ensuremath{\approx}0.7m_{\ensuremath{\pi}}^{}{}_{}{}^{\ensuremath{-}1}?$) and vector-meson coupling constant $g$ (\ensuremath{\cong}6) there follows immediately a relation between the (unrenormalized) axial-vector and vector-meson masses: $m_{A}^{}{}_{}{}^{2}=m_{V}^{}{}_{}{}^{2}+{(\frac{g}{2f})}^{2}$.

Cited by 1

Conserved current of nonconserved quantities

Cong Xiao, Qian Niu · Physical review. B./Physical review. B · 2021

We provide a unified semiclassical theory for the conserved current of nonconserved quantities, and manifest it in two physical contexts: the spin current of Bloch electrons and the charge current of mean-field Bogoliubov quasiparticles. We reveal that the previously overlooked torque quadrupole density and Berry phase correction to the torque dipole density are essential to assure a circulating spin current with null net flow at equilibrium. The band geometric origin of spin transport is ascertained to be the momentum space Berry curvature instead of the spin Berry curvature, paving the way for material related studies. In superconductors the attained conserved charge current corresponds to the quasiparticle charge current renormalized by the condensate backflow. Its circulation at equilibrium gives an orbital magnetization, which involves the characteristics of superconductivity, such as the Berry curvature arising from unconventional pairing and an orbital magnetic moment induced by the charge dipole of moving quasiparticles.

Cited by 1Open access

Partially Conserved Axial-Vector Current and Chiral Anomalies

Michael S. Chanowitz, Min-Shih Chen, Ling-Fong Li · Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields · 1973

We discuss means of testing the validity of the weak and strong partially conserved axial-vector current hypotheses when applied to the theory of chiral anomalies. A factorization property (abstracted from a model due to Drell) is proposed and applied to $\ensuremath{\eta}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$, $\ensuremath{\eta}\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}\ensuremath{\gamma}$, $\ensuremath{\gamma}\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}\ensuremath{\pi}$ and $\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}\ensuremath{\pi}$.

Cited by 9

Conserved vector current test using low energy beta beams

A. B. Balantekin, J. H. de Jesus, Rimantas Lazauskas et al. · Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology · 2006

We discuss the possibility of testing the weak currents and, in particular, the weak magnetism term through the measurement of the ${\overline{\ensuremath{\nu}}}_{e}+p\ensuremath{\rightarrow}{e}^{+}+n$ reaction at a low energy beta-beam facility. We analyze the sensitivity using both the total number of events and the angular distribution of the positrons emitted in a water \ifmmode \check{C}\else \v{C}\fi{}erenkov detector. We show that the weak magnetism form factor might be determined with better than several percent accuracy using the angular distribution. This offers a new way of testing the conserved vector current hypothesis.

Cited by 17Open access

Partially conserved axial-current, noncanonicality and the sigma commutator

M. K. Banerjee, Gerald A. Miller · OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 1980

The pion nucleon sigma commutator, sigma(..pi..N), is studied using the quark mass term as the mechanism for chiral symmetry breaking. The resulting expression for the divergence of the axial-vector current is not a canonical field as conjectured in the hypothesis of partially conserved axial-vector current. This produces a significant modification of the relationship between the soft pion limit of isoscalar pion nucleon scattering amplitude and sigma(..pi..N). Thus the analysis of ..pi..N scattering data yields not the true sigma commutator but what we call the apparent sigma commutator, sigma/sub A/. The latter is a sum of sigma(..pi..N) and a contribution from the noncanonicality of the divergence of the axial-vector current. A pionically amended quark bag model (the Cloudy Bag Model) is used to calculate sigma/sub A/. The Cloudy Bag Model with its bag radius of 0.82 fm can be sigma/sub A/ = 25 MeV, the result of one of the recent studies of the quantity, with 7.7 MeV as the mean mass of u and d quarks.

Cited by 0Open access

Possible Tests of Current Algebra and the Hypothesis of Partially Conserved Axial-Vector Current

Takeshi Ebata · Physical Review · 1967

It is shown that the current algebra and the hypothesis of partially conserved axial-vector current require the existence of a certain "contact-interaction" term in the usual pseudoscalar-pseudoscalar meson theory. Possible detection of such a contact term in the reactions ${\ensuremath{\pi}}^{+}+p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}+{N}^{*++}$ and $\ensuremath{\gamma}+p\ensuremath{\rightarrow}\ensuremath{\pi}+{N}^{*}$ is discussed.

Cited by 10

Spin Hall effect of a conserved current: Conditions for a nonzero spin Hall current

Naoyuki Sugimoto, Shigeki Onoda, Shuichi Murakami et al. · Physical Review B · 2006

We study the spin Hall effect taking into account the impurity scattering effect as general as possible with the focus on the definition of the spin current. The conserved bulk spin current (Zhang et al., cond-mat/0503505) satisfying the continuity equation of spin is considered in addition to the conventional one defined by the symmetric product of the spin and velocity operators. Conditions for nonzero spin Hall current are clarified. In particular, it is found that (i) the spin Hall current is nonzero in the Rashba model with a finite-range impurity potential, and (ii) the spin Hall current vanishes in the cubic Rashba model with a $\ensuremath{\delta}$-function impurity potential.

Cited by 76Open access

Pion photo- and electroproduction and the partially-conserved axial current

Haberzettl, Helmut · arXiv (Cornell University) · 2000

The relevance of the axial current for pion production processes off the nucleon with real or virtual photons is revisited. Employing the hypothesis of a partially conserved axial current (PCAC), it is shown that, when all of the relevant contributions are taken into account, PCAC does not provide any additional constraint for threshold production processes that goes beyond the Goldberger-Treiman relation. In particular, it is shown that pion electroproduction processes at threshold cannot be used to extract any information regarding the weak axial form factor. The relationships found in previous investigations are seen to be an accident of the approximations usually made in this context.

Cited by 0Open access