bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multi-mode vortex beams generation with single-layer transmissive metasurface
Authors: Wang Ziyue , Zhou Dongfang , Liu Qikun , Yan Mengyao , Wang Xian 
Published: November 2023

Abstract
Orbital angular momentum (OAM) is a phenomenon of vortex phase distribution in free space, the infinity of whose modes and the orthogonality between modes allow it to possess great potential in enhancing channel capacity. A transmissive metasurface consisting of a single-layer substrate and a two-layer metallic structure is proposed to enable vortex beam generation based on the concept of the Pancharatnam-Berry (PB) phase. The phase response is achieved by continuous phase modulation under circularly polarised (CP) wave incidence due to the simultaneous rotation of the upper and lower metal structures. Besides, through the introduction of both phase compensation on the metasurface and phase superposition of the beams to the array design, multi-beam generation is expected to be realized. A metasurface sample composed of 30

×

30 elements (450 mm

×

450 mm) is fabricated and measured in a microwave darkroom on the basis of the simulation results. Both the simulation and measurement results provide firm demonstration that the designed metasurface is capable of simultaneously generating four beams carrying OAM mode numbers of

±
1
/
±
2

and different beam directions at the same aperture. The designed metasurface in this paper utilized for generating multi-mode vortex multi-beams will be of wide application in multi-channel transmission in wireless communication systems.
The TSM-net: a new strategy for insulated bearings intelligent faults diagnosis
Authors: Yang Tongguang , Zhao Shubiao , Zhang Junan , Han Qingkai , Li Xuejun 
Published: November 2023

Abstract
With the development of power semiconductor devices, pulse width modulation technology is widely used in high-power frequency conversion control motors, which significantly improves the dynamic performance of variable-speed drive system equipment. However, the high-frequency shaft voltage generated during the drive process acts on the bearing to generate high-frequency current. The damage caused by the shaft current sharply shortens the fatigue wear process of the bearing, which in turn leads to premature failure of the bearing. A high insulating ceramic coating is prepared on the outer surface and side face of the inner and outer rings of the bearing by plasma spraying. That is, an insulating protective film is formed on the outer surface of the bearing, which can effectively isolate or reduce the bearing current, prevent the occurrence of electric erosion, and prolong the service life of the variable speed drive system equipment. However, the vibration excitation generated by the variable-speed drive system equipment will cause cracks or fatigue damage to the insulating bearing, resulting in a very complex fault mechanism of the vibration signal. The fault signal characterization lacks a professional signal analysis method, especially the high-reliability, high-precision and long-life high-performance insulating bearing. There is no qualitative formula or characteristic index to explain its failure. To fill this research gap, a new strategy for optimizing the temporal information fusion model and introducing the self-attention mechanism is innovatively developed, and it is named TSM-Net model, and the first attempt is made to realize intelligent identification of insulated bearing faults. Specifically, a multi-channel insulated bearing time information fusion diagnostic model is designed, and the coarse-grained characteristics with timing law are extracted from the measured insulated bearing fault data. Then, the self-attention mechanism is introduced into the designed insulated bearing time information fusion diagnostic model to optimize, and the weight coefficient is continuously updated to calculate the correlation weight between the insulated bearing fault data and the data, so that the final decision of the TSM-Net model is more focused, so as to improve the diagnostic accuracy. Finally, comparing the proposed TSM-Net model with the current five advanced methods, it is found that the proposed TSM-Net model has good diagnostic accuracy for rail transit motor insulated bearing faults, which verifies the effectiveness and superiority of the strategy, and provides a new way for the fault diagnosis of insulated bearings of high-power inverter control motors.
Statistical analysis of porcelain tiles’ technical properties: full factorial design investigation on oxide ratios and temperature
Authors: Zamani Mohsen , Yapicioglu Haluk , Kara Alpagut , Sevik Cem 
Published: November 2023

Abstract
This study focuses on optimizing the composition and firing temperature of porcelain tiles using statistical analysis techniques. A full factorial design, including model adequacy checking, analysis of variance, Pareto charts, interaction plots, regression model, and response optimizer is employed. The key factors were the Seger ratios of SiO2/Al2O3, Na2O/K2O, MgO/CaO, and firing temperature. The response variables investigated were bulk density, water absorption, linear shrinkage, coefficient of thermal expansion (at 500 °C), and strength. The statistical analysis revealed highly significant results, which were further validated, confirming their reliability for practical use in the production of porcelain tiles. The study demonstrated the effectiveness of utilizing Seger formulas and properties of typical raw materials to accurately predict the final properties of ceramic tiles. By employing SiO2/Al2O3 = 5.2, Na2O/K2O = 1.50, MgO/CaO = 3.0, and firing temperature of 1180 °C, optimized properties, such as maximum strength, maximum bulk density, and minimum water absorption, was achieved with a composite desirability of 0.9821.
Metastable cosmic strings
Authors: Buchmüller Wilfried , Domcke Valerie , Schmitz Kai 
Published: November 2023

Abstract
Many symmetry breaking patterns in grand unified theories (GUTs) give rise to cosmic
strings that eventually decay when pairs of GUT monopoles spontaneously nucleate along the string
cores. These strings are known as metastable cosmic strings and have intriguing implications for
particle physics and cosmology. In this article, we discuss the current status of metastable
cosmic strings, with a focus on possible GUT embeddings and connections to inflation, neutrinos,
and gravitational waves (GWs). The GW signal emitted by a network of metastable cosmic strings in
the early universe differs, in particular, from the signal emitted by topologically stable strings
by a suppression at low frequencies. Therefore, if the underlying symmetry breaking scale is close
to the GUT scale, the resulting GW spectrum can be accessible at current ground-based
interferometers as well as at future space-based interferometers, such as LISA, and at the same
time account for the signal in the most recent pulsar timing data sets. Metastable cosmic strings
thus nourish the hope that future GW observations might shed light on fundamental physics close to
the GUT scale.
Highly asymmetric probability distribution from a finite-width upward step during inflation
Authors: Kawaguchi Ryodai , Fujita Tomohiro , Sasaki Misao 
Published: November 2023

AbstractWe study a single-field inflation model in which the inflaton potential has an upward step between two slow-roll regimes by taking into account the finite width of the step. We calculate the probability distribution function (PDF) of the curvature perturbation P[ℛ] using the δNformalism. The PDF has an exponential-tail only for positive ℛ whose slope depends on the step width. We find that the tail may have a significant impact on the estimation of the primordial black hole abundance. We also show that the PDF P[ℛ] becomes highly asymmetric on a particular scale exiting the horizon before the step, at which the curvature power spectrum has a dip. This asymmetric PDF may leave an interesting signature in the large scale structure such as voids.
Reheating process in the R
2 inflationary model with the baryogenesis scenario
Authors: Jeong Hyun , Kamada Kohei , Starobinsky Alexei A. , Yokoyama Jun'ichi 
Published: November 2023

Abstract
Post-inflationary evolution and (re)heating of the viable inflationary model, the R
2 one, is made more realistic by including the leptogenesis scenario into it. For this purpose, right-handed Majorana neutrinos with a large mass are added to the matter sector of the Standard Model to explain the neutrino oscillation experiments and the baryon asymmetry of the Universe. We have found parameters that characterize this model: non-minimal coupling of the Higgs field ξ, the mass of the right-handed Majorana neutrino MN
α
and the Yukawa coupling matrix components for the right-handed Majorana neutrino. We have analyzed the effect of these parameters on the reheating process and leptogenesis in this model and how they affect the resultant physical quantities: spectral parameters of primordial perturbations and baryon asymmetry.
The polarization quaternion and its applications: a joint representation
of the Q/U Stokes parameters and E/B mode polarizations
Authors: Liu Hao , Creswell James , Tsai Chao-Wei , Naselsky Pavel 
Published: November 2023

Abstract
In this work, we point out that the Q/U Stokes parameters and E/B mode
polarizations are the four components of a unique quaternion, which describes at
the same time the directions and the parity states of spherical linear
polarizations. We then point out that, with this polarization quaternion, the
mathematical form of all Q/U and E/B transforms are greatly simplified, to an
extent that requires only one quaternion multiplication for each transform. A
preliminary application of the polarization quaternion is shown as an example to
detect peculiar pixel domain patterns within the E- and B-families, which are
the former and latter halves of the polarization quaternion.
Spectro-spatial evolution of the CMB. Part II. Generalised Boltzmann hierarchy
Authors: Chluba Jens , Ravenni Andrea , Kite Thomas 
Published: November 2023

Abstract
In this paper, we formulate a generalised photon Boltzmann hierarchy that allows us to
model the evolution and creation of spectral distortion anisotropies caused by energy
release in the early Universe. We directly build on our first paper in this series, extending
the thermalisation Green's function treatment to the anisotropic case. We show that the problem
can be described with the common Boltzmann hierarchy for the photon field extended by new spectral
parameters — a step that reduces the complexity of the calculation by at least two orders of
magnitude. Our formalism describes the effects of i) Doppler and potential driving, ii) spectral
evolution by Compton scattering, iii) perturbed thermalisation and iv) anisotropic heating on the
distortion anisotropies. We highlight some of the main physical properties of the equations and
also outline the steps for computing CMB power spectra including distortion
anisotropies. Limitations and extensions of the formulation are also briefly discussed. The novel
Boltzmann hierarchy given here is the basis for a series of companion papers studying how
distortion anisotropies evolve in the perturbed Universe and which physical processes could be
constrained using future CMB imaging techniques.
Parity-violating trispectrum from Chern-Simons gravity
Authors: Creque-Sarbinowski Cyril , Alexander Stephon , Kamionkowski Marc , Philcox Oliver 
Published: November 2023

Abstract
A potential source for parity violation in the Universe is inflation. The simplest
inflationary models have two fields: the inflaton and graviton, and the lowest-order
parity-violating coupling between them is dynamical Chern-Simons (dCS) gravity with a decay
constant f. Here, we show that dCS imprints a parity-violating signal in primordial scalar
perturbations. Specifically, we find that, after dCS amplifies one graviton helicity due to a
tachyonic instability, the graviton-mediated correlation between two pairs of scalars develops a
parity-odd component. This correlation, the primordial scalar trispectrum, is then transferred to
the corresponding curvature correlator and thus is imprinted in both large-scale structure (LSS)
and the cosmic microwave background (CMB). We find that the parity-odd piece has roughly the same
amplitude as its parity-even counterpart, scaled linearly by the degree of gravitational circular
polarization Πcirc ∼ √ε[h
2/(M
Pl
f)] ≤ 1, with
ε the slow-roll parameter, H the inflationary Hubble scale, and the upper bound
saturated for purely circularly-polarized gravitons. We also find that, in the collapsed limit,
the ratio of the two trispectra contains direct information about the graviton's spin. In models
beyond standard inflationary dCS, e.g. those with multiple scalar fields or superluminal scalar
sound speed, there can be a large enhancement factor F ≳ 106 to the trispectrum. We find
that an LSS survey that contains N
modes linear modes would place an nσ constraint
on Πcirc

r
of ∼ 0.04 (n/3)(106/F)(106/N
modes)1/2 from the parity-odd
galaxy trispectrum, for tensor-to-scalar ratio r. We also forecast for several spectroscopic and
21-cm surveys. This constraint implies that, for high-scale single-field inflation parameters, LSS
can probe very large dCS decay constants f ≲ 4 × 109
GeV(3/n)(F/106)(N
modes/106)1/2. Our result is the first example of a
massless particle yielding a parity-odd scalar trispectrum through spin-exchange.
Global and local stability for ghosts coupled to positive energy degrees of freedom
Authors: Deffayet Cédric , Held Aaron , Mukohyama Shinji , Vikman Alexander 
Published: November 2023

Abstract
Negative kinetic energies correspond to ghost degrees of freedom, which are potentially of
relevance for cosmology, quantum gravity, and high energy physics. We present a novel wide class
of stable mechanical systems where a positive energy degree of freedom interacts with a
ghost. These theories have Hamiltonians unbounded from above and from below, are integrable, and
contain free functions. We show analytically that their classical motion is bounded for all
initial data. Moreover, we derive conditions allowing for Lyapunov stable equilibrium points. A
subclass of these stable systems has simple polynomial potentials with stable equilibrium points
entirely due to interactions with the ghost. All these findings are fully supported by numerical
computations which we also use to gather evidence for stability in various nonintegrable systems.
Axial perturbations of black holes in scalar-tensor gravity:
near-horizon behaviour
Authors: Noui Karim , Roussille Hugo , Langlois David 
Published: November 2023

Abstract
We consider axial (or odd-parity) perturbations of non-spinning hairy black holes (BH) in shift-symmetric DHOST (Degenerate Higher-Order Scalar-Tensor) theories, including terms quartic and cubic in second derivatives of the scalar field.
We give a new formulation of the effective metric in which axial perturbations propagate as in general relativity. We then introduce a generic parametrization of the effective metric in the vicinity of the background BH horizon. Writing the dynamics of the perturbations in terms of a Schrödinger-like operator, we discuss in which cases the operator is (essentially) self-adjoint, thus leading to an unambiguous time evolution, according to the choice of parameters characterizing the near-horizon effective metric. This is in particular useful to investigate the stability of the perturbations.
We finally illustrate our general analysis with two examples of BH solutions.
A test of gravity with Pulsar Timing Arrays
Authors: Liang Qiuyue , Lin Meng-Xiang , Trodden Mark 
Published: November 2023

Abstract
A successful measurement of the Stochastic Gravitational Wave Background (SGWB) in Pulsar Timing Arrays (PTAs) would open up a new window through which to test the predictions of General Relativity (GR). We consider how these measurements might reveal deviations from GR by studying the overlap reduction function — the quantity that in GR is approximated by the Hellings-Downs curve — in some sample modifications of gravity, focusing on the generic prediction of a modified dispersion relation for gravitational waves. We find a distinct signature of such modifications to GR — a shift in the minimum angle of the angular distribution — and demonstrate that this shift is quantitatively sensitive to any change in the phase velocity. In a given modification of gravity, this result can be used, in some regions of parameter space, to distinguish the effect of a modified dispersion relation from that due to the presence of extra polarization modes.
GEO-FPT: a model of the galaxy bispectrum at mildly non-linear scales
Authors: Novell-Masot Sergi , Gualdi Davide , Gil-Marín Héctor , Verde Licia 
Published: November 2023

Abstract
We present GEO-FPT (Geometric Fitted Perturbation Theory), a new model for the galaxy bispectrum anisotropic signal in redshift space, with functional form rooted in perturbation theory. It also models the dependence of the bispectrum with the geometric properties of the triangles in Fourier space, and has a broader regime of validity than
state-of-the-art theoretical models based on perturbation theory. We calibrate the free parameters of this model using high-resolution dark matter simulations and perform stringent tests to show that GEO-FPT
describes the galaxy bispectrum accurately up to scales of k ≃ 0.12hMpc-1 for different cosmological models, as well as for biased tracers of the dark matter field, considering a survey volume of 100 (Gpc h-1)3. In particular, a joint analysis of
the power spectrum and bispectrum anisotropic signals, taking into account their full covariance matrix, reveals that the
relevant physical quantities —
the BAO peak position (along and across the line-of-sight), and the growth of structure parameters times the amplitude of dark matter fluctuations, fσ
8 — are recovered in an unbiased way, with an accuracy better than 0.4% and 2% respectively (which is our 2σ statistical limit of the systematic error estimate).
In addition, the bispectrum signal breaks the fσ
8 degeneracy without detectable bias: f and σ
8 are recovered with better than 2.7% and 3.8% accuracy respectively (which is our 2σ statistical limit of the systematic error estimate).

GEO-FPT boosts the applicability of the bispectrum signal of galaxy surveys beyond the current limitation of k ≲ 0.08hMpc-1 and makes the bispectrum a key statistic to unlock the information content from the mildly non-linear regime in the on-going and forthcoming galaxy redshift surveys.
Separability and classification of multipartite quantum states
Authors: Ma Pan-Wen , Zhao Hui , Jing Naihuan 
Published: November 2023

Abstract
We study separability in arbitrary multipartite quantum systems based on principal base matrices. Necessary conditions are presented for different kinds of separable states. These conditions can give a complete classification of multipartite quantum states. While the usual Bloch representation of a density matrix uses three types of generators, the representation with principal base matrices has one uniform type of generator which simplifies computation. In this paper, we take advantage of this simplicity to derive useful and operational criteria to detect multipartite separability. We first obtain criteria on detecting

1
−
3

separable,

2
−
2

separable,

1
−
1
−
2

separable and fully separable four-partite quantum states. We then study k-separability for multipartite quantum states in arbitrary dimensions. Detailed examples are given to show that our criteria are able to detect more entanglement states than some existing criteria.
Stationary state of harmonic chains driven by boundary resetting
Authors: Sarkar Ritwick , Roy Pritam 
Published: November 2023

Abstract
We study the nonequilibrium steady state of an ordered harmonic chain of N oscillators connected to two walls which undergo diffusive motion with stochastic resetting. The intermittent resetting of the walls effectively emulates two nonequilibrium reservoirs that exert temporally correlated forces on the boundary oscillators. These reservoirs are characterized by the diffusion constants and resetting rates of the walls. We find that, for any finite N, the velocity distribution of the bulk oscillators remains non-Gaussian, as evidenced by a non-zero bulk kurtosis that decays

∼

N

−
1

. We calculate the spatio-temporal correlation of the velocity of the oscillators

⟨

v
l

(
t
)

v

l

′

(

t

′

)
⟩

both analytically as well as using numerical simulation. The signature of the boundary resetting is present at the bulk in terms of the two-time velocity correlation of a single oscillator and the equal-time spatial velocity correlation. For the resetting driven chain, the two-time velocity correlation decay as

t

−

1
2

at the large time, and there exists a non-zero equal-time spatial velocity correlation

⟨

v
l

(
t
)

v

l

′

(

t

′

)
⟩

when

l
≠

l

′

. A non-zero average energy current will flow through the system when the boundary walls reset to their initial positions at different rates. This average energy current can be computed exactly in the thermodynamic limit. Numerically we show that the distribution of the instantaneous energy current at the boundary is independent of the system size. However, the distribution of the instantaneous energy current in the bulk approaches a stationary distribution in the thermodynamic limit.
Beam test result of the sealed MRPC prototype for CEE-eTOF
Authors: Wang Botan , Xu Haoqian , Sun Kai , Liu Daming , Han Dong , Wang Yi , Zhao Lei , Guo Baohong , Wang Hexiang , Huang Shiya 
Published: November 2023

Abstract
We report the beam test and result of the sealed Multigap Resistive Plate Chambers (MRPC) for the external Time of Flight (eTOF) wall of the Cooler-strorage-ring External-target Experiment (CEE). The test stand detects the secondary charged particles produced from heavy ion collisions in the Heavy Ion Research Facility in Lanzhou (HIRFL), and it serves as a joint evaluation of the future CEE system, including the detectors, readout electronics, data acquisition, trigger system, etc. The collision is achieved by a Fe beam and a Fe target, with an estimated beam energy of 300 MeV/u. The sealed MRPC prototypes work stably during the test with a 20 sccm low gas flow. The whole test system is triggered from the channel multiplicity provided by the TOF detectors. A tracking method is implemented to the analysis in order to resolve the events with multiple tracks on the detectors. The result shows that the detectors reach 98% efficiency at their working point. With proper corrections, the time resolution is evaluated to be 60 ps, which fulfills the requirement to the eTOF wall.