Observation of the Rare Decay of the η Meson to Four Muons

A search for the rare η → μ+μ−μ+μ− double-Dalitz decay is performed using a sample of proton-proton collisions, collected by the CMS experiment at the CERN LHC with high-rate muon triggers during 2017 and 2018 and corresponding to an integrated luminosity of 101 fb−1. A signal having a statistical significance well in excess of 5 standard deviations is observed. Using the η → μ+μ− decay as normalization, the branching fraction β(η → μ+μ−μ+μ−) = [5.0 ± 0.8(stat) ± 0.7(syst) ± 0.7(β2μ)] × 10−9 is measured, where the last term is the uncertainty in the normalization channel branching fraction. This work achieves an improved precision of over 5 orders of magnitude compared to previous results, leading to the first measurement of this branching fraction, which is found to agree with theoretical predictions

ENHANCING E-COMMERCE CUSTOM REGULATION FOR SEAMLESS TRADE IN EAEU: A POLICY PAPER

This policy paper provides a comprehensive analysis of the e-commerce sector within the Eurasian Economic Union (EAEU), highlighting its challenges, opportunities, and potential for driving economic growth. It sets forth a series of well-crafted policy recommendations aimed at establishing a conducive environment for e-commerce development. By implementing these measures, policymakers can fully unleash the potential of e-commerce, fostering economic growth, and advancing digital inclusion. As the e-commerce sector flourishes, it necessitates the establishment of a fair and efficient regulatory framework to facilitate smooth cross-border transactions. Addressing the custom regulation and taxation of e-commerce transactions requires collaborative efforts. Policymakers must strive to develop transparent and equitable customs and taxation systems that prevent tax evasion while easing the burden on small and medium-sized enterprises. One essential consideration is the implementation of destination-based taxation, ensuring that taxes are paid in the countries where products and services are consumed. This approach fosters fairness and discourages tax avoidance strategies. The policy paper aims to propose specific measures to enhance e-commerce custom regulation, effectively tackling the unique challenges presented by online trade. Leveraging technology and fostering international cooperation are pivotal in designing streamlined customs processes, creating an enabling environment for e-commerce growth. Such endeavors will ensure compliance, minimize illicit activities, and foster a flourishing e-commerce landscape within the EAEU

Quantized form factor shift in the presence of free electron laser radiation

In electron scattering, the target form factors contribute significantly to the diffraction pattern and carry information on the target electromagnetic charge distribution. Here we show that the presence of electromagnetic radiation, as intense as currently available in Free Electron Lasers, shifts the dependence of the target form factors by a quantity that depends on the number of photons absorbed or emitted by the electron as well as on the parameters of the electromagnetic radiation. As example, we show the impact of intense ultraviolet and soft X-ray radiation on elastic electron scattering by Ne-like Argon ion and by Xenon atom. We find that the shift brought by the radiation to the form factor is in the order of some percent. Our results may open up a new avenue to explore matter with the assistance of laser

Fractional Angular Momenta, Gouy and Berry Phases in Relativistic Bateman-Hillion-Gaussian Beams of Electrons

A new Bateman-Hillion solution to the Dirac equation for a relativistic Gaussian electron beam taking explicit account of the four-position of the beam waist is presented. This solution has a pure Gaussian form in the paraxial limit but beyond it contains higher order Laguerre-Gaussian components attributable to the tighter focusing. One implication of the mixed mode nature of strongly diffracting beams is that the expectation values for spin and orbital angular momenta are fractional and are interrelated to each other by intrinsic spin-orbit coupling. Our results for these properties align with earlier work on Bessel beams [Bliokh et al., Phys. Rev. Lett. 107, 174802 (2011)] and show that fractional angular momenta can be expressed by means of a Berry phase. The most significant difference arises, though, due to the fact that Laguerre-Gaussian beams naturally contain Gouy phase, while Bessel beams do not. We show that Gouy phase is also related to Berry phase and that Gouy phase fronts that are flat in the paraxial limit become curved beyond it

Application of Market Models to Network Equilibrium Problems

We present a general two-side market model with divisible commodities and price functions of participants. A general existence result on unbounded sets is obtained from its variational inequality re-formulation. We describe an extension of the network flow equilibrium problem with elastic demands and a new equilibrium type model for resource allocation problems in wireless communication networks, which appear to be particular cases of the general market model. This enables us to obtain new existence results for these models as some adjustments of that for the market model. Under certain additional conditions the general market model can be reduced to a decomposable optimization problem where the goal function is the sum of two functions and one of them is convex separable, whereas the feasible set is the corresponding Cartesian product. We discuss some versions of the partial linearization method, which can be applied to these network equilibrium problems.Comment: 18 pages, 3 table

Essential L-Amino Acid-Functionalized Graphene Oxide for Liquid Crystalline Phase Formation

The colloidal 2D materials based on graphene and its modifications are of great interest when it comes to forming LC phases. These LC phases allow controlling the orientational order of colloidal particles, paving the way for the efficient processing of modified graphene with anisotropic properties. Here, we present the peculiarities of AA functionalization of GO, along with the formation of its LC phase and orientational behavior in an external magnetic field. We discuss the influence of pH on the GOLC, ultimately showing its pH-dependent behavior for GO-AA complexes. In addition, we observe different GO morphology changes due to the presence of AA functional groups, namely L-cysteine dimerization on the GO platform. The pH dependency of AA-functionalized LC phase of GO is examined for the first time. We believe that our studies will open new possibilities for applications in bionanotechnologies due to self-assembling properties of LCs and magnificent properties of GO.Comment: 10 pages, 16 figure

An approach for integrating kerberized non web-based services with web-based identity federations

Many identity federations are designed to be used with web browsers. This paper proposes an approach for integrating non web-based applications with web-based identity federations using Kerberos protocol. We evaluate this approach by making NFS server available for users of SAML-based identity federation of Baden-Württemberg state of Germany. We make use of LDAP-Facade software for federating non web-based services. We have modified the web-interface component of LDAP-Facade to enable the registration with kerberized services. Our approach can be used without modifications on the client side. Copyright © 2015 SCITEPRESS - Science and Technology Publications. All rights reserved

Underlining some limitations of the statistical formalism in quantum mechanics

We show that two chosen ensembles of spin states, which are differently prepared but are described by the same density matrix in quantum mechanics, do not fully share the same measurable characteristics. One characteristic on which they differ is shown to be the variance of the spin along a given direction. We conclude that the statistical description of an ensemble of states as given by its density matrix, although sufficient in many cases, should be considered incomplete, as it does not fully describe the measurable characteristics of the ensemble. A discussion a posteriori on the problem is provided