Vectorial Coupling Research Articles

Anomalies in bottom from new physics in top

We analyze the possibility to accommodate current b→sℓ+ℓ− anomalies with TeV-scale mediators that couple to right-handed top quarks and muons, contributing to b→sℓ+ℓ− at the one-loop level. We use the Standard Model Effective Field Theory (SMEFT) framework but also look at specific scenarios by taking into account all possible irreducible representations of the Lorentz and Standard Model gauge group for the mediators. From a global fit of b→sℓ+ℓ− data and LEP-I observables we find that the Wilson coefficients of two SMEFT operators: Oℓu=(ℓ¯LμγαℓLμ)(t¯RγαtR) and Oeu=(μ¯RγαμR)(t¯RγαtR) need to satisfy Ceu∼Cℓu. New physics enters then in b→sℓ+ℓ− mainly through the operator O9=(s¯γμPLb)(ℓ¯γμℓ) of the Weak Effective Theory. After discussing all possible mediators, we concentrate on two scenarios: A vector boson in the irreducible representation Zμ′∼(1,1,0) of the Standard Model gauge group with vectorial coupling to muons, and a combination of two leptoquarks: the scalar R2∼(3,2,7/6) and the vector U˜1μ∼(3,1,5/3). We derive LHC constraints by recasting di-muon resonance, pp→tt¯tt¯ and SUSY searches. Additionally, we analyze the prospects for discovering these mediators during the high-luminosity phase of the LHC.

Formation of a Spin Texture in a Quantum Gas Coupled to a Cavity.

We observe cavity mediated spin-dependent interactions in an off-resonantly driven multilevel atomic Bose-Einstein condensate that is strongly coupled to an optical cavity. Applying a driving field with adjustable polarization, we identify the roles of the scalar and the vectorial components of the atomic polarizability tensor for single and multicomponent condensates. Beyond a critical strength of the vectorial coupling, we infer the formation of a spin texture in a condensate of two internal states from the analysis of the cavity output field. Our work provides perspectives for global dynamical gauge fields and self-consistently spin-orbit coupled gases.

Full-Vectorial Mode Coupling in Optical Fibers

Optical full vectorial modes have closely attracted much attention because of their unique optical features and thus may develop the fundamental researches and new functionalities of light. Beyond the conventional linear polarization modal coupling, we thoroughly investigate the inherent polarizationdependence and polarization-isolation features for full vectorial mode coupling in optical fibers, as well as the coupling crosstalk in view of the modal degeneracy. We present the general full vectorial coupling mechanism and numerically simulate the full vectorial mode coupling for both fiber directional and grating assisted coupling cases. Furthermore, we give the detailed analyses of coupling crosstalk based on the unified threemode coupling model. Apart from lifting the modal degeneracy, significantly, the crosstalk can also be reduced by weakening the coupling coefficient and meanwhile increasing the coupling length. This extended full vectorial mode coupling mechanismmay provide theoretical guidance on exploiting new all fiberbased polarization-sensitive passive elements to control fullvectorial fields and modal polarization states.

Information Theoretical Methods as Discerning Quantifiers of the Equations of State of Neutron Stars

In this work we use the statistical measures of information entropy, disequilibrium and complexity to discriminate different approaches and parametrizations for different equations of state for quark stars. We confirm the usefulness of such quantities to quantify the role of interactions in such stars. We find that within this approach, a quark matter equation of state such as SU(2) NJL with vectorial coupling and phase transition is slightly favoured and deserves deeper studies.

Electric properties of the Cu+, Ag+ and Au+ cations in the ground 1S and excited 3D, 1D electronic states

The lowest-order electric properties of the coinage metal cations Cu+, Ag+ and Au+ are calculated ab initio. For the ground states, accurate coupled cluster estimations are presented for the static and dynamic dipole and quadrupole polarizabilities. Results of the similar quality are obtained for the static dipole polarizabilities and permanent quadrupole moments of the lowest excited triplet 3D states, whereas the first excited singlet 1D states are characterized at the lower level of correlation treatment. Effect of vectorial spin-orbit coupling is assessed using the spin-orbit configuration interaction method.

Information theoretical methods as discerning quantifiers of the equations of state of neutron stars

Abstract In this work we use the statistical measures of information entropy, disequilibrium and complexity to discriminate different approaches and parametrizations for different equations of state for quark stars. We confirm the usefulness of such quantities to quantify the role of interactions in such stars. We find that within this approach, a quark matter equation of state such as SU(2) NJL with vectorial coupling and phase transition is slightly favoured and deserves deeper studies.

Exclusive central diffractive production of scalar, pseudoscalar and vector mesons

We discuss exclusive central diffractive production of scalar ($f_{0}(980)$, $f_{0}(1370)$, $f_{0}(1500)$), pseudoscalar ($\eta$, $\eta'(958)$), and vector ($\rho^{0}$) mesons in proton-proton collisions. The amplitudes are formulated in terms of effective vertices required to respect standard rules of Quantum Field Theory and propagators for the exchanged pomeron and reggeons. Different pomeron-pomeron-meson tensorial (vectorial) coupling structures are possible in general. In most cases two lowest orbital angular momentum - spin couplings are necessary to describe experimental differential distributions. For the $f_{0}(980)$ and $\eta$ production the reggeon-pomeron, pomeron-reggeon, and reggeon-reggeon exchanges are included in addition, which seems to be necessary at relatively low energies. The theoretical results are compared with the WA102 experimental data, in order to determine the model parameters. For the $\rho^{0}$ production the photon-pomeron and pomeron-photon exchanges are considered. The coupling parameters of tensor pomeron and/or reggeon are fixed from the H1 and ZEUS experimental data of the $\gamma p \to \rho^{0} p$ reaction. We present first predictions of this mechanism for $pp \to pp \pi^{+} \pi^{-}$ reaction being studied at COMPASS, RHIC, Tevatron, and LHC. Correlation in azimuthal angle between outgoing protons and distribution in pion rapidities at $\sqrt{s} = 7$TeV are presented. We show that high-energy central production of mesons could provide crucial information on the spin structure of the soft pomeron.

A Master Switch Couples Mg2+-Assisted Catalysis to Domain Motion in B. stearothermophilus Tryptophanyl-tRNA Synthetase

We demonstrate how tryptophanyl-tRNA synthetase uses conformation-dependent Mg(2+) activation to couple catalysis of tryptophan activation to specific, functional domain movements. Rate acceleration by Mg(2+) requires ∼-6.0 kcal/mol in protein⋅Mg(2+) interaction energy, none of which arises from the active site. A highly cooperative interaction between Mg(2+) and four residues from a remote, conserved motif that mediates the shear of domain movement (1) destabilizes the pretransition state conformation, thereby (2) inducing the Mg(2+) to stabilize the transition state for k(cat) by ∼-5.0 kcal/mol. Cooperative, long-range conformational effects on the metal therefore convert an inactive Mg(2+) coordination into one that can stabilize the transition state if, and only if, domain motion occurs. Transient, conformation-dependent Mg(2+) activation, analogous to the escapement in mechanical clocks, explains vectorial coupling.

Confusing nonzeroθ13with nonstandard interactions in the solar neutrino sector

Solar and KamLAND data are in slight tension when interpreted in the standard two-flavor oscillations framework and this may be alleviated allowing for a nonzero value of the mixing angle ${\ensuremath{\theta}}_{13}$. Here we show that, likewise, nonstandard flavor-changing interactions (FCI), possibly intervening in the propagation of solar neutrinos, are equally able to alleviate this tension and therefore constitute a potential source of confusion in the determination of ${\ensuremath{\theta}}_{13}$. By performing a full three-flavor analysis of solar and KamLAND data in presence of FCI we provide a quantitative description of the degeneracy existing between ${\ensuremath{\theta}}_{13}$ and the vectorial coupling ${ϵ}_{e\ensuremath{\tau}}^{dV}$ characterizing the nonstandard transitions between ${\ensuremath{\nu}}_{e}$ and ${\ensuremath{\nu}}_{\ensuremath{\tau}}$ in the forward scattering process with $d$-type quarks. We find that couplings with magnitude ${ϵ}_{e\ensuremath{\tau}}^{dV}\ensuremath{\sim}10%$, compatible with the existing bounds, can mimic the nonzero values of ${\ensuremath{\theta}}_{13}$ indicated by the latest analyses.

Stabilization of vector soliton complexes in nonlocal nonlinear media

We introduce vector soliton complexes in nonlocal Kerr-type nonlinear media. We discover that under proper conditions the combination of nonlocality and vectorial coupling has a remarkable stabilizing action on multihumped solitons. In particular, we find that stable bound states featuring several field oscillations in each soliton component do exist. This affords stabilization of vector soliton trains incorporating a large number of humps, a class of structures known to self-destroy via strong instabilities in scalar settings.

Multipole vector solitons in nonlocal nonlinear media

We show that multipole solitons can be made stable via vectorial coupling in bulk nonlocal nonlinear media. Such vector solitons are composed of mutually incoherent nodeless and multipole components jointly inducing a nonlinear refractive index profile. We found that stabilization of the otherwise highly unstable multipoles occurs below certain maximum energy flow. Such a threshold is determined by the nonlocality degree.

Linear detection of phase-modulated optical signals with ac-biased cubic photorefractive crystals: Influence of coupling effects

We apply the theory of vectorial wave coupling in cubic photorefractive crystals subjected to ac-field to describe the transformation of a momentary phase changes of one of the input beams into the output intensity modulation (the so-called grating translation technique). In contrast to the previous studies, we take into account the change of the space-charge field amplitude across the crystal owing to the coupling effects. The theory developed is employed to optimize the conditions for the linear signal detection under polarization filtering for the transverse and longitudinal optical configurations. We also analyze the possibility of the linear detection without polarization filtering.

Vectorial two-beam coupling with arbitrary shifted photorefractive gratings: An analytical approach

An analytical solution is presented to the vectorial coupled wave equations for the steady state amplitudes of two waves interacting in cubic photorefractive crystals. The solution accounts for pump depletion as well as an arbitrary phase shift between the interference pattern and photorefractive grating. It is shown that bidirectional vectorial amplification and polarization orthogonalization of the interacting beams take place in photorefractive crystal with diffusion, drift or mixed mechanism of space-charge formation.

Solutions for vectorial beam coupling under ac field in cubic photorefractive crystals

We develop a theory of vectorial wave coupling in cubic photorefractive crystals placed in an alternating ac field to enhance the nonlinear response. It is proven in the general case that despite essential differences between the diffusion and the ac nonlocal responses, the latter keeps the light interference fringes straight during the interaction. This fundamental feature allows, under certain restrictions, to reduce the nonlinear problem of vectorial coupling to the known linear problem of vectorial Bragg diffraction from a spatially uniform grating, which admits an exact solution. As a result, the nonlinear vectorial problem can be effectively solved for a number of practically important cases. These cases include nontrivial polarization effects and also the high-contrast effects. The presence of conservation laws involving the polarization degrees of freedom is shown. A number of particular cases relevant to experiments with BTO crystals are considered.

Numerical analysis of vectorial two-beam coupling in photorefractive materials

A numerical model is presented for the analysis of vectorial twobeam coupling in photorefractive materials. A powerful software tool has been developed for design purposes. For Fe,Ce-doped lithium niobate crystals, conversion efficiency and signal gain dependences on experimental parameters and beam polarization have been found. The good accuracy of the model has been demonstrated by comparisons with experimentally measured parameters.

Grating translation technique for vectorial beam coupling and its applications to linear signal detection

We develop the theory of vectorial beam coupling in cubic photorefractive crystals to describe the effect of fast phase modulation on output intensities and polarizations. Special emphasis is given to new features of the grating translation technique compared with its scalar variant. We show, in particular, that a strong nonlocal ac response in crystals of the sillenite family can be effectively used for the linear detection of fast signals. Theoretical results are supported by polarization ac experiments with Bi12TiO20 crystals.

Synchronization of chaotic semiconductor laser systems: a vectorial coupling-dependent scenario.

We demonstrate the influence of vectorial coupling on the synchronization behavior of complex systems. We study two semiconductor lasers subject to delayed optical feedback which are unidirectionally coherently coupled via their optical fields. Our experimental and numerical results demonstrate a characteristic synchronization scenario in dependence on the relative feedback phase leading cyclically from chaos synchronization to almost uncorrelated states, and back to chaos synchronization. Finally, we reveal the influence of the feedback phase on the dynamics of the solitary delay system.

Theory of photorefractive vectorial wave coupling in cubic crystals.

We present an analytical theory of vectorial wave coupling in photorefractive cubic crystals which are, in general, optically active. The theory is based on the systematic use of the spatial symmetry properties and the apparatus of the Pauli operators to deal with two-dimensional vectors and matrices. It allows one to give a unified description of a wide spectrum of photorefractive phenomena, including the efficiency and polarization properties of Bragg diffraction, polarization two-beam coupling enhanced by ac fields, the influence of the photoelastic effect, etc. Applications of the theory to crystals of the sillenite family and to particular photorefractive phenomena are given. A good qualitative agreement between the theoretical predictions and experimental data for Bi12TiO20 (BTO) crystals is shown.

Iteration Profiles in Radiative Transfer Problems. I. From Vectorial to Scalar Coupling

view Abstract Citations (1) References (7) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Iteration Profiles in Radiative Transfer Problems. I. From Vectorial to Scalar Coupling Crivellari, L. ; Simonneau, E. Abstract We have recently introduced a new algorithm, the implicit integral method (IIM), for solving radiative transfer problems in which the specific source functions (for each frequency and direction) depend linearly on the radiation field via a single quantity which is independent of both frequency and direction. We define this kind of relationship as scalar coupling. The fact that our method turned out to be fast, robust, and highly reliable leads us to seek its extension to include those problems where the above, necessary condition is not fulfilled. In these problems, the specific source functions depend on the radiation field through a nonfactorable redistribution operator. In our definition, these are cases of vectorial coupling. In this paper we present the successful application of the IIM, through an iterative procedure, to two specific instances of vectorial coupling. The first is the determination of the temperature distribution, self-consistent with the energy conservation constraint, within a LTE stellar atmosphere model. Here the physical processes other than radiative transfer require an iterative procedure for the global solution of the problem. Thus we take advantage of this circumstance to solve iteratively the radiative transfer part as well. The second is the case of the non-LTE two-level-atom line formation problem in which partial redistribution is taken into account in the presence of a background continuum. This problem allows a direct solution, but at the cost of using algorithms that necessarily require the storage and inversion of very high order matrices. On the contrary, we show that a solution based on the iterative application of the IIM, thanks to the outstanding features of the latter, is not only fast, but above all much more reliable in numerical terms. Publication: The Astrophysical Journal Pub Date: September 1995 DOI: 10.1086/176222 Bibcode: 1995ApJ...451..328C Keywords: LINE: FORMATION; METHODS: NUMERICAL; RADIATIVE TRANSFER; STARS: ATMOSPHERES full text sources ADS |

Photorefractive ring resonators with vectorial two-beam coupling: Theory and applications.

Oscillation conditions for unidirectional ring resonators containing cubic photorefractive crystals are analyzed. The coupling of pump beams to intracavity modes is presumed to occur via the vectorial two-beam coupling in the crystal. It is also presumed that the intracavity field as well as the pump field are composed of two orthogonally polarized components. The solution of slowly varying envelope wave equations in the degenerate and steady-state limit is used to determine the grating action and to derive threshold conditions for both the transmission and the reflection geometry of the wave-mixing process. A number of special cases of wave-mixing coupling constants is considered. Potential applications of two-wave mixing rings in different photorefractive devices, such as optical amplifiers, switches, and logic circuits are discussed.