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Register a new userInteraction of the magnetic quadrupole moment of a non-relativistic particle with an electric field in the background of screw dislocations with a rotating frame
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Bekir Can L\\\"utf\\\"uo\\u{g}lu
Publication date
2021
fields
Physics
and research's language is
English
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In this study, we considered a moving particle with a magnetic quadrupole moment in an elastic medium in the presence of a screw dislocation. We assumed a radial electric field in a rotating frame that leads a uniform effective magnetic field perpendicular to the plane of motion. We solved the Schrodinger equation to derive wave and energy eigenvalue functions by employing analytical methods for two interaction configurations: in the absence of potential and in the presence of a static scalar potential. Due to the topological defect in the medium, we observed a shift in the angular momentum quantum number which affects the energy eigenvalues and the wave function of the system.
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In this paper we define a non-dynamical phase for a spin-1/2 particle in a rotating magnetic field in the non-adiabatic non-cyclic case, and this phase can be considered as a generalized Berry phase. We show that this phase reduces to the geometric Berry phase, in the adiabatic limit, up to a factor independent of the parameters of the system. We could add an arbitrary phase to the eigenstates of the Hamiltonian due to the gauge freedom. Then, we fix this arbitrary phase by comparing our Berry phase in the adiabatic limit with the Berrys result for the same system. Also, in the extreme non-adiabatic limit our Berry phase vanishes, modulo $2pi$, as expected. Although, our Berry phase is in general complex, it becomes real in the expected cases: the adiabatic limit, the extreme non-adiabatic limit, and the points at which the state of the system returns to its initial form, up to a phase factor. Therefore, this phase can be considered as a generalization of the Berry phase. Moreover, we investigate the relation between the value of the generalized Berry phase, the period of the states and the period of the Hamiltonian.
We have studied numerically the shadows of a non-Kerr rotating compact object with quadrupole mass moment, which belongs to Manko-Novikov family. The non-integrable photon motion caused by quadrupole mass moment affects sharply the shadow of the compact object. As the deviation parameter related to quadrupole mass moment is negative, the shadow of compact object is prolate and there are two disconnected main shadows with eyebrows located symmetrically on both sides of the equatorial plane. As the deviation parameter is positive, the shadow becomes oblate and the main shadow is joined together in the equatorial plane. Moreover, in this positive cases, there is a disorder region in the left of shadow which increases with the quadrupole-deviation parameter. Interestingly, we also find that Einstein ring is broken as the deviation from Kerr metric is larger than a certain critical value. This critical value decreases with the rotation parameter of black hole. Especially, the observer on the direction of rotation axis will find some concentric bright rings in the black disc. Finally, supposing that the gravitational field of the supermassive central object of the galaxy described by this metric, we estimated the numerical values of the observables for the black hole shadow.
We investigate the system constituted by a polarizable atom near a nanosphere under the influence of an external electrostatic field, showing that the attractive dispersive force between them can be overcome by the electrostatic interaction. Therefore, in addition to the advantageous possibility of actively tuning the resultant force with an external agent without the requirement of physical contact, this force may also become repulsive. We analyze this situation in different physical regimes of distance and explore the interaction of different atoms with both metallic and dielectric spheres, discussing which cases are easier to control. Furthermore, our results reveal that these repulsive forces can be achieved with feasible field intensities in the laboratory.
The neutron, in addition to possibly having a permanent electric dipole moment as a consequence of violation of time-reversal invariance, develops an induced electric dipole moment in the presence of an external electric field. We present here a unified non-relativistic description of these two phenomena, in which the dipole moment operator, $vec{cal D}$, is not constrained to lie along the spin operator. Although the expectation value of $vec{cal D}$ in the neutron is less than $10^{-13}$ of the neutron radius, $r_n$, the expectation value of $vec {cal D},^2$ is of order $r_n^2$. We determine the spin motion in external electric and magnetic fields, as employed in past and future searches for a permanent dipole moment, and show that the neutron electric polarizability, although entering the neutron energy in an external electric field, does not affect the spin motion. In a simple non-relativistic model we show that the expectation value of the permanent dipole is, to lowest order, proportional to the product of the time reversal-violating coupling strength and the electric polarizability of the neutron.
We calculate the electric conductivity $sigma$ in deconfined QCD matter using a holographic QCD model, i.e., the Sakai-Sugimoto Model with varying magnetic field $B$ and chiral anomaly strength. After confirming that our estimated $sigma$ for $B=0$ is consistent with the lattice-QCD results, we study the case with $B eq 0$ in which the coefficient $alpha$ in the Chern-Simons term controls the chiral anomaly strength. Our results imply that the transverse conductivity, $sigma_perp$, is suppressed to be $lesssim 70%$ at $Bsim 1,mathrm{GeV}^2$ as compared to the $B=0$ case when the temperature is fixed as $T= 0.2,mathrm{GeV}$. Since the Sakai-Sugimoto Model has massless fermions, the longitudinal conductivity, $sigma_parallel$, with $B eq 0$ should diverge due to production of the matter chirality. Yet, it is possible to extract a regulated part out from $sigma_parallel$ with an extra condition to neutralize the matter chirality. This regulated quantity is interpreted as an Ohmic part of $sigma_parallel$. We show that the longitudinal Ohmic conductivity increases with increasing $B$ for small $alpha$, while it is suppressed with larger $B$ for physical $alpha=3/4$ due to anomaly induced interactions.
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