Probing resonance decays to two visible and multiple invisible particles

We consider the decay of a generic resonance to two visible particles and any number of invisible particles. We show that the shape of the invariant mass distribution of the two visible particles is sensitive to both the mass spectrum of the new particles, as well as the decay topology. We provide the analytical formulas describing the invariant mass shapes for the nine simplest topologies (with up to two invisible particles in the final state). Any such distribution can be simply categorized by its endpoint, peak location and curvature, which are typically sufficient to discriminate among the competing topologies. In each case, we list the effective mass parameters which can be measured by experiment. In certain cases, the invariant mass shape is sufficient to completely determine the new particle mass spectrum, including the overall mass scale.Comment: Added new figures, conclusions unchanged, published versio

Asymmetric scattering and non-orthogonal mode patterns in optical micro-spirals

Quasi-bound states in an open system do in general not form an orthogonal and complete basis. It is, however, expected that the non-orthogonality is weak in the case of well-confined states except close to a so-called exceptional point in parameter space. We present numerical evidence showing that for passive optical microspiral cavities the parameter regime where the non-orthogonality is significant is rather broad. Here we observe almost-degenerate pairs of well-confined modes which are highly non-orthogonal. Using a non-Hermitian model Hamiltonian we demonstrate that this interesting phenomenon is related to the asymmetric scattering between clockwise and counterclockwise propagating waves in the spiral geometry. Numerical simulations of ray dynamics reveal a clear ray-wave correspondence.Comment: 8 pages, 10 figure

The Development of Smart, Multi-Responsive Core@Shell Composite Nanoparticles

The unique optical, magnetic, and electronic properties of metal nanoparticles (NPs) give rise to photothermal, therapeutic, and electronic device applications, correspondingly. On the other hand, the limited range of the properties of simple spherical metal NPs has complicated their ability to function in many of these applications. Therefore, this chapter starts by reviewing a specific type of NP that can be classified into three main groups: silica coated with metal (silica@metal) NPs, metal coated with silica (metal@silica) NPs, and other similar forms of core@shell structures. The objective of this review is to introduce the concept of multi-responsive core@shell nanoparticles. More specifically, this chapter highlights "smart" core@shell composite NPs having multiple response mechanisms (e.g., temperature, light, and/or an applied magnetic field) due to the ability of these systems to perform a task by remotely responding to stimuli. Additionally, hydrogel-coated metal@silica NPs, with the ability to store drugs in a mesoporous silica (m-silica) interlayer, are examined because these nano-materials potentially provide substantial advantages for carrying cargos to targeted sites. To demonstrate this capability, we examine recent research that provided initial tests of composite NPs with a pH- and temperature-responsive hydrogel coating, including the application of an underlying m-silica interlayer to improve the capacity of these NPs to load and release small molecules

Assessing the Design Innovation Potential of Timber Prefabricated Housing Through Axiomatic Design

Despite the current building sector slowdown in Italy, timber housing industry market is growing. But its growth has been limited mainly by the high costs of ad-hoc full-customized buildings and the lack of customer appreciation for mass-produced buildings. In order to satisfy the current demand for affordable customized housing, building industry should focus on solutions based on the combination of personalized and mass-produced parts. In this way, clients would have the chance to personalize crucial parts, and building industry can limit costs by the mass-production of the others. This combination between mass production and customization involves artefact flexibility and robustness with regard to the designer’s viewpoint. These requirements are set in the conceptual design phase, but in this stage architect’s decision making is not adequately supported. Since Axiomatic Design (AD) is able to support the analysis of designs with respect to the specified requirements, AD is applied to the review of prefabricated housing archetypes and current timber construction systems. This study shows the effectiveness of applying AD to prefabricated building design: crucial design decisions that affect the specified requirements are identified; inputs limiting their fulfilment in the timber building prefabrication are highlighted, and recommendations for developing adequate systems are provided

Improving the sensitivity of stop searches with on-shell constrained invariant mass variables

The search for light stops is of paramount importance, both in general as a promising path to the discovery of beyond the standard model physics and more specifically as a way of evaluating the success of the naturalness paradigm. While the LHC experiments have ruled out much of the relevant parameter space, there are "stop gaps", i.e., values of sparticle masses for which existing LHC analyses have relatively little sensitivity to light stops. We point out that techniques involving on-shell constrained M_2 variables can do much to enhance sensitivity in this region and hence help close the stop gaps. We demonstrate the use of these variables for several benchmark points and describe the effect of realistic complications, such as detector effects and combinatorial backgrounds, in order to provide a useful toolkit for light stop searches in particular, and new physics searches at the LHC in general.Comment: 49 pages, 28 figures, revised version published in JHEP, references adde

On-shell constrained M2M_2 variables with applications to mass measurements and topology disambiguation

We consider a class of on-shell constrained mass variables that are 3+1 dimensional generalizations of the Cambridge $M_{T2}$ variable and that automatically incorporate various assumptions about the underlying event topology. The presence of additional on-shell constraints causes their kinematic distributions to exhibit sharper endpoints than the usual $M_{T2}$ distribution. We study the mathematical properties of these new variables, e.g., the uniqueness of the solution selected by the minimization over the invisible particle 4-momenta. We then use this solution to reconstruct the masses of various particles along the decay chain. We propose several tests for validating the assumed event topology in missing energy events from new physics. The tests are able to determine: 1) whether the decays in the event are two-body or three-body, 2) if the decay is two-body, whether the intermediate resonances in the two decay chains are the same, and 3) the exact sequence in which the visible particles are emitted from each decay chain.Comment: 44pages, 17 figures. revised version, published in JHEP. Minor addition: a paragraph discussing the effect on the background at the end of section 5.

The 750 GeV Diphoton Excess May Not Imply a 750 GeV Resonance

We discuss non-standard interpretations of the 750 GeV diphoton excess recently reported by the ATLAS and CMS Collaborations which do not involve a new, relatively broad, resonance with a mass near 750 GeV. Instead, we consider the sequential cascade decay of a much heavier, possibly quite narrow, resonance into two photons along with one or more invisible particles. The resulting diphoton invariant mass signal is generically rather broad, as suggested by the data. We examine three specific event topologies - the antler, the sandwich, and the 2-step cascade decay, and show that they all can provide a good fit to the observed published data. In each case, we delineate the preferred mass parameter space selected by the best fit. In spite of the presence of invisible particles in the final state, the measured missing transverse energy is moderate, due to its anti- correlation with the diphoton invariant mass. We comment on the future prospects of discriminating with higher statistics between our scenarios, as well as from more conventional interpretations.Comment: Discussion about the ATLAS Moriond EW2016 added. Matched to PRL accepted versio

Micro-Doppler Extraction and ANalysis of the Ballistic Missile Using RDA Based on the Flight Scenario

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Internal localized eigenmodes on spin discrete breathers in antiferromagnetic chains with on-site easy axis anisotropy

We investigate internal localized eigenmodes of the linearized equation around spin discrete breathers in 1D antiferromagnets with on-site easy axis anisotropy. The threshold of occurrence of the internal localized eigenmodes has a typical structure in parameter space depending on the frequency of the spin discrete breather. We also performed molecular dynamics simulation in order to show the validity of our linear analysis.Comment: 4 pages including 5 figure

Electron orbital valves made of multiply connected armchair carbon nanotubes with mirror-reflection symmetry: tight-binding study

Using the tight-binding method and the Landauer-B\"{u}ttiker conductance formalism, we demonstrate that a multiply connected armchair carbon nanotube with a mirror-reflection symmetry can sustain an electron current of the $\pi$-bonding orbital while suppress that of the $\pi$-antibonding orbital over a certain energy range. Accordingly, the system behaves like an electron orbital valve and may be used as a scanning tunneling microscope to probe pairing symmetry in d-wave superconductors or even orbital ordering in solids which is believed to occur in some transition-metal oxides.Comment: 4 figures, 12 page