Physics

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The evolution operator U(t) for a time-independent parity-time-symmetric systems is well studied in the literature. However, for the non-Hermitian time-dependent systems, a closed form expression for the evolution operator is not available. In this paper, we make use of a procedure, originally developed by A.R.P. Rau [Phys.Rev.Lett, 81, 4785-4789 (1998)], in the context of deriving the solution of Liuville-Bloch equations in the product formof exponential operatorswhen time-dependent external fields are present, for the evaluation of U(t) in the interaction picture wherein the corresponding Hamiltonian is time-dependent and in general non-Hermitian. This amounts to a transformation of the whole scheme in terms of addressing a nonlinear Riccati equation the existence of whose solutions depends on the fulfillment of a certain accompanying integrability condition. © 2018 Andromeda Publishing And Academic Services LTD. All right reserved.

(SoNS) School of Natural Sciences

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Letters in High Energy Physics

Evolution operator for time-dependent non-Hermitian Hamiltonians

We address the presently reported significant flavor anomalies in the Kaon and B meson systems such as the CP violating Kaon decay (ϵ′/ϵ) and lepton-flavor universality violation in B meson decays (RK(*),RD(*)), by proposing flavorful and chiral vector bosons as the new physics constitution at around TeV scale. The chiral-flavorful vectors (CFVs) are introduced as a 63-plet of the global SU(8) symmetry, identified as the one-family symmetry for left-handed quarks and leptons in the standard model (SM) forming the 8-dimensional vector. Thus the CFVs include massive gluons, vector leptoquarks, and W′, Z′-type bosons, which are allowed to have flavorful couplings with left-handed quarks and leptons, and flavor-universal couplings to right-handed ones, where the latter arises from mixing with the SM gauge bosons. The flavor texture is assumed to possess a “minimal” structure to be consistent with the current flavor measurements on the K and B systems. Among the presently reported significant flavor anomalies in the Kaon and B meson systems (ϵ′/ϵ, RK(*),RD(*)), the first two ϵ′/ϵ and RK(*) anomalies can simultaneously be interpreted by the presence of CFVs; the RD(*) anomaly is predicted not to survive, due to the approximate SU(8) flavor symmetry. Remarkably, we find that as long as both of the ϵ′/ϵ and RK(*) anomalies persist beyond the SM, the CFVs predict the enhanced K+→ π+νν¯ and KL→ π0νν¯ decay rates compared to the SM values, which will readily be explored by the NA62 and KOTO experiments, and they will also be explored in new resonance searches at the Large Hadron Collider. © 2018, The Author(s).

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Journal of High Energy Physics

Simultaneous interpretation of K and B anomalies in terms of chiral-flavorful vectors

Two polymers based on (3E,7E)-3,7-bis(2-oxoindolin-3-ylidene)benzo[1,2-b:4,5-b′]difuran-2,6(3H,7H)-dione (BIBDF) coupled with (E)-2-(2-(thiophen-2-yl)vinyl)thiophene (TVT) or dithienylbenzothiadiazole (TBT), namely PBIBDF-TVT and PBIBDF-TBT were synthesized via the Stille coupling reaction. The effect of benzothiadiazole or vinylene-π spacer of the copolymers on optical properties, energy levels, electronic device performance and microstructure were studied. It was found that PBIBDF-TBT based OFET devices, annealed at 180 °C, showed better performance with the highest electron mobility of 2.9 × 10-2 cm2 V s-1 whereas PBIBDF-TVT polymer exhibited 5.0 × 10-4 cm2 V s-1. The two orders of magnitude higher electron mobility of PBIBDF-TBT over PBIBDT-TVT is a clear indicator of the better charge transport ability of this polymer semiconductor arising from its higher crystallinity and better donor-acceptor interaction. © 2018 The Royal Society of Chemistry.

RSC Advances

Vinylene and benzo[c] [1,2,5]thiadiazole: Effect of the π-spacer unit on the properties of bis(2-oxoindolin-3-ylidene)-benzodifuran-dione containing polymers for n-channel organic field-effect transistors

The efficacy of 50 keV Ar+-ion irradiation toward the interfacial and stoichiometric engineering of strained Al-doped ZnO (AZO)/TiO2 heterostructure is systematically investigated using a variety of experimental techniques, notably by cross-sectional transmission electron microscopy. Glancing-angle X-ray diffraction evidences the release of in-plane compressive stress from the as-grown AZO/TiO2 bilayer structure at a critical fluence of 1 × 1016 ions/cm2, and we discuss in the light of microcracks and voids formation combined with the dewetting phenomenon. Ion irradiation also leads to an improvement of stoichiometry in both top AZO and underneath amorphous TiO2 layers, as manifested by depth-dependent energy dispersive X-ray spectroscopy owing to the large diffusion of oxygen toward the AZO/TiO2 interfacial region through the AZO defect sites. Such ion beam induced self-healing in stoichiometry of AZO/TiO2 heterostructure has been attributed to a conjunction of sputtering and diffusion phenomena involving the constituent elements (Zn, Ti, and O). Further increase in ion fluence up to 5 × 1016 ions/cm2 causes a complete deterioration of the heterostructure with the formation of a graded layer via intermixing of these elements, followed by the evolution of voids. © 2018 Author(s).

Journal of Applied Physics

Probing the impact of energetic argon ions on the structural properties of ZnO:Al/TiO2 heterostructures

The flexibility of amorphous anodized alumina (AAO) in developing radiation dosimeter for hadron therapy is reported by controlled carbon ion implantation, followed by thermoluminescence (TL) measurements. The efficacy of amorphous AAO in controlling TL sensitivity is found to be governed by an increase in F+ defect centers as a function of carbon concentration, as revealed from the close resemblance of the trend in photoluminescence intensity. Moreover, its nanoporous structure is demonstrated to be advantageous for defect engineering due to the increase in the surface-to-volume ratio. Detailed X-ray photoelectron spectroscopy analysis suggests the formation of F+ centers by substituting Al3+ ions with C2+ in the vicinity of oxygen vacancies, where depth-dependent study showed the evolution of conducting channels owing to sp2 hybridized C-C bonding, leading to a differential charging effect. This work provides a direction to tune nanoporous AAO in its amorphous form for future ion beam dosimetry. © 2018 Author(s).

Carbon doping controlled thermoluminescent defect centers in nanoporous alumina for ion beam dosimetry

First layer Aurivillius Bismuth Molybdate Tungstate ceramic [Bi2Mo1−xWxO6 (BMoW); x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08 and 0.10] compositions are prepared using deep penetrating microwave sintering in air. All samples show known perovskite phase formation just after 5 h calcinations at 575 °C. X-ray diffraction and transmission electron microscopy based energy dispersive spectroscopy are used to confirm the phase-purity and gross elemental concentration change besides particle size. Nearly doubleε′-values are obtained for investigated BMoW materials compared to earlier reported values. Silver percolation through electrodes in bismuth oxide deficient surfaces of BMoW ceramic powders induces radio wave absorption in the frequency range 2 to 4 MHz. Characteristic third phase transition (γ→ γ″ ′) of Bi2MoO6 material dissolves gradually on increasing tungsten concentration. The introduction of tungsten in BMo matrix increases the dipolar strength of MoO6 octahedrons bending against infrared absorption as evidenced from FTIR analysis. Additionally appearing FTIR peaks provide a strong indication of CO and CO2 contamination on exposed powder surfaces useful for photocatalytic applications. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.

Journal of Materials Science: Materials in Electronics

Integrating third phase transition and CO/CO2 contamination in microwave tailored Bi2Mo1−xWxO6 nano materials

We investigate a new realization of extended quantum-mechanical supersymmetry. We first show that an N = 2 quantum-mechanical supersymmetry is hidden in the four-dimensional (4D) spectrum of the KaluzaKlein decomposition for the higher dimensional Dirac field, that is, KaluzaKlein mode functions of 4D right-handed spinors and 4D left-handed ones form N = 2 supermultiplets. In addition to N = 2 supersymmetry, we discover that an N-extended supersymmetry (N = d + 2 (d + 1) for d = even (odd) extra dimensions) is further hidden in the 4D spectrum. The extended symmetry can explain additional degeneracy of the spectrum. Furthermore, we show that a superpotential can be introduced into the N-extended supercharges and clarify the condition to preserve the supersymmetry. The partial breaking of the supersymmetry is also demonstrated. © 2018 IOP Publishing Ltd Printed in the UK.

Journal of Physics A: Mathematical and Theoretical

Extended supersymmetry in Dirac action with extra dimensions

We address the presently reported significant flavor anomalies in the K and B meson systems such as the CP violating Kaon decay (ε′/ε) and lepton-flavor universality violation in B meson decays (RK(∗), and also commenting RD(∗)), by proposing flavorful and chiral vector bosons as the new physics constitution at ∼ 1TeV. Interestingly, if the new (composite) vector bosons are quite heavier than ∼ 1TeV, we face a difficulty in addressing the anomaly in ε′/ε consistently with the constraint from the K0-K0 mixing. Both of the anomalies can be addressed within 1σ confidence levels individually, where the relevant parameter space will be investigated by the NA62 and KOTO experiments, in addition to direct searches at the large hadron collider. © Copyright owned by the author(s) under the terms of the Creative Commons.

Proceedings of Science

Simultaneous explanation of K and B anomalies in vectorlike compositeness

The probability that all eigenvalues of a product of m independent N× N subblocks of a Haar distributed random real orthogonal matrix of size (Li+ N) × (Li+ N) , (i= 1 , ⋯ , m) are real is calculated as a multidimensional integral, and as a determinant. Both involve Meijer G-functions. Evaluation formulae of the latter, based on a recursive scheme, allow it to be proved that for any m and with each Li even the probability is a rational number. The formulae furthermore provide for explicit computation in small order cases. © 2017, Springer Science+Business Media New York.

Journal of Theoretical Probability

The Probability That All Eigenvalues are Real for Products of Truncated Real Orthogonal Random Matrices

The room temperature resistive switching behavior in 50 keV O+-ion irradiated TiO2-x layers at an ion fluence of 5 × 1016 ions cm-2 is reported. A clear transformation from columnar to layered polycrystalline films is revealed by transmission electron microscopy with increasing ion fluence, while the complementary electron energy loss spectroscopy suggests an evolution of oxygen vacancy (OV) in TiO2-x matrix. This is further verified by determining electron density with the help of x-ray reflectivity. Both local and device current-voltage measurements illustrate that the ion-beam induced OVs play a key role in bistable resistive switching mechanism. © 2018 IOP Publishing Ltd.