6,557 research outputs found
Quasi-exact solvability beyond the SL(2) algebraization
We present evidence to suggest that the study of one dimensional
quasi-exactly solvable (QES) models in quantum mechanics should be extended
beyond the usual \sla(2) approach. The motivation is twofold: We first show
that certain quasi-exactly solvable potentials constructed with the \sla(2)
Lie algebraic method allow for a new larger portion of the spectrum to be
obtained algebraically. This is done via another algebraization in which the
algebraic hamiltonian cannot be expressed as a polynomial in the generators of
\sla(2). We then show an example of a new quasi-exactly solvable potential
which cannot be obtained within the Lie-algebraic approach.Comment: Submitted to the proceedings of the 2005 Dubna workshop on
superintegrabilit
Broadband transverse susceptibility in multiferroic Y-type hexaferrite Ba0.5Sr1.5Zn2Fe12O22
Producción CientíficaNoncollinear spin systems with magnetically induced ferroelectricity from changes in spiral magnetic ordering have attracted significant interest in recent research due to their remarkable magnetoelectric effects with promising applications. Single phase multiferroics are of great interest for these new multifunctional devices, being Y-type hexaferrites good candidates, and among them the ZnY compounds due to their ordered magnetic behaviour over room temperature. Polycrystalline Y type hexaferrites with composition Ba0.5Sr1.5Zn2Fe2O22 (BSZFO) were sintered in 1050 °C–1250 °C temperature range. Transverse susceptibility measurements carried out on these BSZFO samples in the temperature range 80–350 K with DC fields up to ± 5000 Oe reveal different behaviour depending on the sintering temperature. Sample sintered at 1250 °C is qualitatively different, suggesting a mixed Y and Z phase like CoY hexaferrites. Sintering at lower temperatures produce single phase Y-type, but the transverse susceptibility behaviour of the sample sintered at 1150 °C is shifted at temperatures 15 K higher. Regarding the DC field sweeps the observed behaviour is a peak that shifts to lower values with increasing temperature, and the samples corresponding to single Y phase exhibit several maxima and minima in the 250 K–330 K range at low DC applied field as a result of the magnetic field induced spin transitions in this compound.Ministerio de Ciencia, Innovación y Universidades; Agencia Estatal de Investigación with FEDER (MAT2016-80784-P
Electric and weak electric dipole form factors for heavy fermions in a general two Higgs doublet model
A conjecture on Exceptional Orthogonal Polynomials
Exceptional orthogonal polynomial systems (X-OPS) arise as eigenfunctions of
Sturm-Liouville problems and generalize in this sense the classical families of
Hermite, Laguerre and Jacobi. They also generalize the family of CPRS
orthogonal polynomials. We formulate the following conjecture: every
exceptional orthogonal polynomial system is related to a classical system by a
Darboux-Crum transformation. We give a proof of this conjecture for codimension
2 exceptional orthogonal polynomials (X2-OPs). As a by-product of this
analysis, we prove a Bochner-type theorem classifying all possible X2-OPS. The
classification includes all cases known to date plus some new examples of
X2-Laguerre and X2-Jacobi polynomials
A Family of Quasi-solvable Quantum Many-body Systems
We construct a family of quasi-solvable quantum many-body systems by an
algebraic method. The models contain up to two-body interactions and have
permutation symmetry. We classify these models under the consideration of
invariance property. It turns out that this family includes the rational,
hyperbolic (trigonometric) and elliptic Inozemtsev models as the particular
cases.Comment: 9 pages, REVTeX4, final versio
Riemann Surfaces of genus g with an automorphism of order p prime and p>g
The present work completes the classification of the compact Riemann surfaces
of genus g with an analytic automorphism of order p (prime number) and p > g.
More precisely, we construct a parameteriza- tion space for them, we compute
their groups of uniformization and we compute their full automorphism groups.
Also, we give affine equations for special cases and some implications on the
components of the singular locus of the moduli space of smooth curves of genus
g.Comment: 28 pages, 5 figure
Exchange operator formalism for N-body spin models with near-neighbors interactions
We present a detailed analysis of the spin models with near-neighbors
interactions constructed in our previous paper [Phys. Lett. B 605 (2005) 214]
by a suitable generalization of the exchange operator formalism. We provide a
complete description of a certain flag of finite-dimensional spaces of spin
functions preserved by the Hamiltonian of each model. By explicitly
diagonalizing the Hamiltonian in the latter spaces, we compute several infinite
families of eigenfunctions of the above models in closed form in terms of
generalized Laguerre and Jacobi polynomials.Comment: RevTeX, 31 pages, no figures; important additional conten
Effect of the Photoexcitation Wavelength and Polarization on the Generated Heat by a Nd-Doped Microspinner at the Microscale
Thermal control at small scales is critical for studying temperature-dependent
biological systems and microfluidic processes. Concerning this, optical
trapping provides a contactless method to remotely study microsized heating
sources. This work introduces a birefringent luminescent microparticle of
NaLuF4:Nd3+ as a local heater in a liquid system. When optically trapped with
a circularly polarized laser beam, the microparticle rotates and heating is
induced through multiphonon relaxation of the Nd3+ ions. The temperature
increment in the surrounding medium is investigated, reaching a maximum
heating of ≈5 °C within a 30 μm radius around the static particle under
51 mW laser excitation at 790 nm. Surprisingly, this study reveals that the
particle’s rotation minimally affects the temperature distribution, contrary to
the intuitive expectation of liquid stirring. The influence of the microparticle
rotation on the reduction of heating transfer is analyzed. Numerical
simulations confirm that the thermal distribution remains consistent
regardless of spinning. Instead, the orientation-dependence of the
luminescence process emerges as a key factor responsible for the reduction in
heating. The anisotropy in particle absorption and the lag between the
orientation of the particle and the laser polarization angle contribute to this
effect. Therefore, caution must be exercised when employing spinning
polarization-dependent luminescent particles for microscale thermal analysis
using rotation dynamics.Projects CNS2022-135495,
PID2023-151078OB-I00 and TED2021-129937B-I00 funded by MCIN/AEI/10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR”Spanish Ministerio de Universidades, through the FPU program
(FPU19/04803)Consejería de Universidad, Investigación e Innovación de la
Junta de Andalucía and by FEDER “Una manera de hacer Europa” (P18-FR-3583
- …