Field In Space Research Articles

Sharpening the Distance Conjecture in diverse dimensions

The Distance Conjecture holds that any infinite-distance limit in the scalar field moduli space of a consistent theory of quantum gravity must be accompanied by a tower of light particles whose masses scale exponentially with proper field distance ‖ϕ‖ as m ~ exp(−λ‖ϕ‖), where λ is order-one in Planck units. While the evidence for this conjecture is formidable, there is at present no consensus on which values of λ are allowed. In this paper, we propose a sharp lower bound for the lightest tower in a given infinite-distance limit in d dimensions: λ ≥ 1/sqrt{d-2} . In support of this proposal, we show that (1) it is exactly preserved under dimensional reduction, (2) it is saturated in many examples of string/M-theory compactifications, including maximal supergravity in d = 4 – 10 dimensions, and (3) it is saturated in many examples of minimal supergravity in d = 4 – 10 dimensions, assuming appropriate versions of the Weak Gravity Conjecture. We argue that towers with λ < 1/sqrt{d-2} discussed previously in the literature are always accompanied by even lighter towers with λ ≥ 1/sqrt{d-2} , thereby satisfying our proposed bound. We discuss connections with and implications for the Emergent String Conjecture, the Scalar Weak Gravity Conjecture, the Repulsive Force Conjecture, large-field inflation, and scalar field potentials in quantum gravity. In particular, we argue that if our proposed bound applies beyond massless moduli spaces to scalar fields with potentials, then accelerated cosmological expansion cannot occur in asymptotic regimes of scalar field space in quantum gravity.

What can we learn from the total width of the Higgs boson?* *Supported in part by the National Science Foundation of China (11725520, 11675002, 11635001, 12022514, 11875003, 12047503). JHY is also supported by the National Key Research and Development Program of China (2020YFC2201501)

As one of the key properties of the Higgs boson, the Higgs total width is sensitive to the global profile of the Higgs boson couplings, and thus new physics would modify the Higgs width. We investigate the total width in various new physics models, including various scalar extensions, composite Higgs models, and the fraternal twin Higgs model. Typically, the Higgs width is smaller than the standard model value due to mixture with other scalars if the Higgs is elementary, or curved Higgs field space for the composite Higgs. On the other hand, except for the possible invisible decay mode, the enhanced Yukawa coupling in the two Higgs doublet model or the exotic fermion embeddings in the composite Higgs could enhance the Higgs width greatly. The precision measurement of the Higgs total width at the high-luminosity LHC can be used to discriminate certain new physics models.

Hollow cylindrical linear stator vibrator using a traveling wave of longitudinal axisymmetric vibration mode

Ultrasonic motors (USMs) are expected to be used in special environments: high magnetic field environments and space environments, which require lightweight and multiple degrees of freedom. However, when used as linear ultrasonic motors (LUSMs), a linear guide and a preload mechanism are required, complicating the structure. In the present paper, a hollow cylindrical linear stator without an extra linear guide has been considered. The stator consists of a metal pipe and two piezoelectric (PZT) tubes installed at both ends of the metal pipe. Their connected parts are tapered for the first longitudinal axisymmetric vibration mode of the cylinder, namely L(0,1) mode excitation, and the metal pipe is subjected to radial strain. The vibration of the stator is assumed to be one-dimensional and is modeled by an electromechanical equivalent circuit. The principle that the traveling wave is formed on the metal pipe by dual-PZT-tube phase difference excitation was clarified. Finite element analysis and some measurements were conducted to confirm that the theory was consistent. The analyses and measurements were in good agreement. Therefore, the operating principle was confirmed. The results of the transport experiment showed that the average speed of the 8.5-g slider was 7.9 mm/s.

Identification of the degree of load on the farm tractor operator in the spatial structure of the treated field

The purpose of this study was to spatially identify the degree of mental fatigue of a farm tractor operator within the experimental field during grain sowing. In addition, to determine possible relationships between field space conditions and operator mental workload. The study was conducted on a John Deere 6210R tractor aggregated with a Horsch Pronto 4D seeder. The operator operated the tractor's on-board computer, the seeder's control computer, and a Trimble CFX-750 satellite navigation system. The mental workload of the tractor operator was monitored using a Muse 2 headband. The headband allows monitoring of brainwave activity, position and acceleration of the operator's head movements, and heart rate. It was found that the average value of attention was as high as 58% and was characteristic for seeding in the central part of the field (yellow) and in the north-western part of the field. The areas that required a much higher level of operator concentration (about 80%) were located in the southeastern part of the field and in the western part of the field. The applied research methodology allowed to generate spatial maps of the operator's level of mental engagement and thus to locate the value of mental engagement in a specific area of the field. On the basis of maps of spatial variation of the level of attention engagement by the operator, it is possible to generate information on which parts of the field on the farm will require special attention.

Toward inflation with ns=1 in light of the Hubble tension and implications for primordial gravitational waves

Recently, it has been found that complete resolution of the Hubble tension might point to a scale-invariant Harrison-Zeldovich spectrum of primordial scalar perturbation, i.e., ${n}_{s}=1$ for ${H}_{0}\ensuremath{\sim}73\text{ }\text{ }\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$. We show that, for well-known slow-roll models, if inflation ends by a waterfall instability with respect to another field in the field space while inflaton is still at a deep slow-roll region, then ${n}_{s}$ can be lifted to ${n}_{s}=1$. A surprise of our result is that with prerecombination early dark energy, chaotic ${\ensuremath{\phi}}^{2}$ inflation, strongly disfavored by $\mathrm{Planck}+\mathrm{BICEP}/\mathrm{Keck}$ in standard $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$, can be revived, which is now well within testable region of upcoming cosmic microwave background B-mode experiments.

Preliminary Modelling of Solar Quiet Geomagnetic Field Average using Non-Linear Autoregressive with Exogeneous Input (NARX)

This paper discusses geomagnetic field attempt modelling using an Artificial Neural Network (ANN). The local horizontal component of geomagnetic field data was collected on April 2011 (equinox) during a solar quiet day at recent solar cycle inclination-24 using the Magnetic Data Acquisition System (MAGDAS) in Langkawi, Malaysia, in the low latitude region. The calculated average values (mean) of the H component geomagnetic field variation during Equinox 2011 characterised the dominant geomagnetic field during that particular solar cycle. The difference in amplitude of maximum and minimum values shows a regular diurnal variation of the geomagnetic field during Sq inthe low latitude region. The output training utilised these calculated mean values during the modelling attempt. Meanwhile, the input training utilised proton density, solar wind plasma speed, plasma flow pressure, and Interplanetary Magnetic Field (IMF) space data using Non-Linear Auto Regressive Input (NARX). The best modelling outputs were 3, 2, and 3 for input delay (𝑛𝑢), output delay (𝑛y), and hidden layer size (h), respectively. Residual test and model fit analysis show an unbiased and high overlap between predicted and actual geomagnetic field average values, suggesting the model can potentially anticipate the geomagnetic field average during solar quiet in November (month of Equinox) on solar cycle inclination.

Research on the Current new Characteristics, Operation Problems and Innovation Strategies of the Official WeChat official account of Chinese Universities Driven by "Generation Z"

Today, the official WeChat official account of Chinese universities has entered a new era with "Generation Z" (1995-2009) college students as the main audience and content producers. While opening up a broader communication space and more diversified communication possibilities for Chinese universities, it also provides a campus media platform for "Generation Z" college students with distinctive personality, rationality, independence and tolerance to create, share, express and talk. However, the current official WeChat official account of Chinese universities shows many new features and problems in accuracy, innovation, cohesion, empathy and integration. Based on this situation, this study proposes innovative and optimized strategies for the operation, construction and development of the official WeChat official account of Chinese colleges and universities from the aspects of deep cultivation of content, distribution interaction, team building, brand communication, management mode, etc., in combination with the cultural circle characteristics and subcultural needs of Chinese "Generation Z" young college students, in order to diversify, multi circle Find the balance and fit point between "official publicity" and "Gen Z demand" in a multi field space, and build an influential official WeChat official account brand of Chinese universities.

Taming the landscape of effective theories

We introduce a generalized notion of finiteness that provides a structural principle for the set of effective theories that can be consistently coupled to quantum gravity. More concretely, we propose a Tameness Conjecture that states that all valid effective theories are labelled by a definable parameter space and must have scalar field spaces and coupling functions that are definable using the tame geometry built from an o-minimal structure. We give a brief introduction to tame geometry and describe how it restricts sets, manifolds, and functions. We then collect evidence for the Tameness Conjecture by studying various effective theories arising from string theory compactifications by using some recent advances in tame geometry. In particular, we will exploit the fact that coset spaces and period mappings are definable in an o-minimal structure and argue for non-trivial tameness results in higher-supersymmetric theories and in Calabi-Yau compactifications. As strongest evidence for the Tameness Conjecture over a discrete parameter space, we then discuss a recent theorem stating that the locus of self-dual flux vacua of F-theory admits a tame geometry even if one allows for any flux choice satisfying the tadpole constraint. This result implies the finiteness of self-dual flux vacua in F-theory.

G-Equivariant Embedding Theorems for CR Manifolds of High Codimension

Let (X,T1,0X) be a (2n+1+d)-dimensional compact CR manifold with codimension d+1, d≥1, and let G be a d-dimensional compact Lie group with CR action on X and T be a globally defined vector field on X such that CTX=T1,0X⊕T0,1X⊕CT⊕Cg_, where g_ is the space of vector fields on X induced by the Lie algebra of G. In this work, we show that if X is strongly pseudoconvex in the direction of T and n≥2, then there exists a G-equivariant CR embedding of X into CN for some N∈N. We also establish a CR orbifold version of Boutet de Monvel’s embedding theorem.

Creating Resilient Research Findings: Using Ethnographic Methods to Combat Research Amnesia

Product teams, including those I work with, struggle to connect the challenges observed in prior research to issues that endure in the field and market space. As a shortcut for efficiency gains, product partners rely on researchers to succinctly summarize deep insights, sometimes preferring reductive quantitative interpretations to enable a bias toward action in product development cycles. Challenges facing researchers in product development include maintaining the relevance of prior research, providing a way to make it evergreen and accessible, and building on it to deepen and expand an existing model of behavior. This case introduces the concept of Research Amnesia, which poses a threat to organizational resilience. Using core ethnographic methods, a strategic methodological approach is outlined to frameshift the value of existing research within a company to develop new insights, bring together disparate analyses and teams, and propel product partners forward by offering more questions as a means to answers.

Regularized polysymplectic geometry and first steps towards Floer theory for covariant field theories

It is the goal of this paper to present the first steps for defining the analogue of Hamiltonian Floer theory for covariant field theory, treating time and space relativistically. While there already exist a number of competing geometric frameworks for covariant field theory generalizing symplectic geometry, none of them are readily suitable for variational techniques such as Hamiltonian Floer theory, since the corresponding action functionals are too degenerate. Instead, we show how a regularization procedure introduced by Bridges leads to a new geometric framework for which we can show that the finite energy L2-gradient lines of the corresponding action functional, called Floer curves, converge asymptotically to space-time periodic solutions. As a concrete example we prove the existence of Floer curves, and hence also of space-time periodic solutions, for a class of coupled particle-field systems defined in this new framework.

Classification of Abelian domain walls

We discuss domain walls from spontaneous breaking of Abelian discrete symmetries $Z_N$. A series of different domain wall structures are predicted, depending on the symmetry and charge assignments of scalars leading to the spontaneous symmetry breaking (SSB). A widely-existing type of domain walls are those separating degenerate vacua which are adjacent in the field space. We denote these walls as adjacency walls. In the case that $Z_N$ terms are small compared with the $U(1)$ terms, the SSB of $U(1)$ generates strings first and then adjacency walls bounded by strings are generated after the SSB of $Z_N$. For symmetries larger than $Z_3$, non-adjacent vacua exist, we regard walls separating them as non-adjacency walls. These walls are unstable if $U(1)$ is a good approximation. If the discrete symmetry is broken via multiple steps, we arrive at a complex structure that one kind of walls wrapped by another type. On the other hand, if the symmetry is broken in different directions independently, walls generated from the different breaking chains are blind to each other.

Axiogenesis with a heavy QCD axion

We demonstrate that the observed cosmological excess of matter over anti-matter may originate from a heavy QCD axion that solves the strong CP problem but has a mass much larger than that given by the Standard Model QCD strong dynamics. We investigate a rotation of the heavy QCD axion in field space, which is transferred into a baryon asymmetry through weak and strong sphaleron processes. This provides a strong cosmological motivation for heavy QCD axions, which are of high experimental interest. The viable parameter space has an axion mass ma between 1 MeV and 10 GeV and a decay constant fa< 105 GeV, which can be probed by accelerator-based direct axion searches and observations of the cosmic microwave background.

Infinitesimal automorphisms of algebraic varieties and vector fields on elliptic surfaces

We give several results concerning the connected component ${\rm Aut}_X^0$ of the automorphism scheme of a proper variety $X$ over a field, such as its behaviour with respect to birational modifications, normalization, restrictions to closed subschemes and deformations. Then, we apply our results to study the automorphism scheme of not necessarily Jacobian elliptic surfaces $f: X \to C$ over algebraically closed fields, generalizing work of Rudakov and Shafarevich, while giving counterexamples to some of their statements. We bound the dimension $h^0(X,T_X)$ of the space of global vector fields on an elliptic surface $X$ if the generic fiber of $f$ is ordinary or if $f$ admits no multiple fibers, and show that, without these assumptions, the number $h^0(X,T_X)$ can be arbitrarily large for any base curve $C$ and any field of positive characteristic. If $f$ is not isotrivial, we prove that ${\rm Aut}_X^0 \cong \mu_{p^n}$ and give a bound on $n$ in terms of the genus of $C$ and the multiplicity of multiple fibers of $f$. As a corollary, we re-prove the non-existence of global vector fields on K3 surfaces and calculate the connected component of the automorphism scheme of a generic supersingular Enriques surface in characteristic $2$. Finally, we present additional results on horizontal and vertical group scheme actions on elliptic surfaces which can be applied to determine ${\rm Aut}_X^0$ explicitly in many concrete cases.

Nonlinear flexure mechanics of mixture unified gradient nanobeams

The mixture unified gradient theory of elasticity is invoked for the nanoscopic study of the nonlinear flexure mechanics of nanobeams. A mixed variational framework is conceived based on ad hoc functional space of kinetic test fields, wherein a complete set of governing equations, classical and non-standard boundary conditions, and the constitutive relations are integrated into a solitary functional. The size-effect phenomenon associated with the nonlinear flexure of nanobeams are efficiently realized as the stress gradient theory, the strain gradient theory, and the classical elasticity theory are consistently unified within the framework of the mixture unified gradient elasticity. A viable numerical approach is introduced based on the conceived mixed variational framework while the autonomous series solution of the kinematic and kinetic field variables is implemented. As the kinetic field variables are directly determined rather than utilizing post-computations, the established consistent variational theory provides an advantageous means for efficacious approximate approaches. The nonlinear flexural response of the mixture unified gradient beams with kinematics constraints of practical interest in nano-mechanics is detected and thoroughly compared with the linear counterparts in terms of the characteristic parameters. The detected nonlinear flexural characteristics of nano-sized beams can pave the way ahead in the nonlinear mechanics of nano-structures.

Asymptotic scalar field cosmology in string theory

Asymptotic (late-time) cosmology depends on the asymptotic (infinite-distance) limits of scalar field space in string theory. Such limits feature an exponentially decaying potential V ~ exp(−cϕ) with corresponding Hubble scale H ~ sqrt{{dot{phi}}^2+2V} ~ exp(−λHϕ), and at least one tower of particles whose masses scale as m ~ exp(−λϕ), as required by the Distance Conjecture. In this paper, we provide evidence that these coefficients satisfy the inequalities sqrt{left(d-1right)/left(d-2right)} ≥ λH≥ λlightest≥ 1/ sqrt{d-2} in d spacetime dimensions, where λlightest is the λ coefficient of the lightest tower. This means that at late times, as the scalar field rolls to ϕ → ∞, the low-energy theory remains a d-dimensional FRW cosmology with decelerated expansion, the light towers of particles predicted by the Distance Conjecture remain at or above the Hubble scale, and both the strong energy condition and the dominant energy condition are satisfied.

Holography of the photon ring

Space-based next-generation interferometers propose to measure the Lyapunov exponents of the nearly bound geodesics that comprise the photon ring surrounding the black hole M87*. We argue that these classical Lyapunov exponents equal the quantum Ruelle resonances describing the late-time approach to thermal equilibrium of the quantum microstate holographically dual to any Kerr black hole such as M87*. Moreover, we identify ‘near-ring regions’ in the phase space of fields propagating on Kerr that exhibit critical behavior, including emergent conformal symmetries. These are analogues for sub-extremal Kerr of the much-studied ‘near-horizon regions’ of (near-)extremal black holes. The emergent conformal symmetries greatly constrain the observational predictions for the fine photon ring substructure around M87* and for quasinormal gravitational-wave ringdowns, as well as any proposal for a quantum holographic dual to the Kerr black hole. More generally, we hope that our identification of several universal features of Kerr spectroscopy provides a useful starting point for a bottom-up approach to holography for astrophysical black holes.

Cosmic perturbations from a rotating field

Complex scalar fields charged under approximate U(1) symmetries appear in well-motivated extensions of the Standard Model. One example is the field that contains the QCD axion field associated with the Peccei-Quinn symmetry; others include flat directions in supersymmetric theories with baryon, lepton, or flavor charges. These fields may take on large values and rotate in field space in the early universe. The relevant approximate U(1) symmetry ensures that the angular direction of the complex field is light during inflation and that the rotation is thermodynamically stable and is long-lived. These properties allow rotating complex scalar fields to naturally serve as curvatons and explain the observed perturbations of the universe. The scenario imprints non-Gaussianity in the curvature perturbations, likely at a level detectable in future large scale structure observations. The rotation can also explain the baryon asymmetry of the universe without producing excessive isocurvature perturbations.

Real-time passive cavitation mapping with high spatial-temporal resolution

Shock wave lithotripsy (SWL) and laser lithotripsy (LL) have been widely used for clinical treatment of kidney stones. Cavitation plays an important role in stone fragmentation in both SWL and LL, yet it may also contribute to renal tissue injury. It is therefore crucial to determine the spatiotemporal distributions of cavitation activities to maximize stone fragmentation while minimizing tissue injury. Passive cavitation mapping (PCM) has most practical applications in deep biological tissues and is most promising for clinical translation. We have developed a set of technologies for 2D/3D PCM that can be seamlessly integrated with ultrasound imaging and photoacoustic imaging. Our 2D/3D PCM has achieved a spatial resolution of hundreds of micrometers and a temporal resolution of several microseconds. We also developed a transient angular spectrum approach for PCM reconstruction, which is ten times faster than the traditional delay-and-sum method. Using the 2D/3D PCM system, we imaged shockwave- and laser-induced single cavitation bubbles in both free field and constricted space, as well as on large animal models. Collectively, our results have demonstrated the high reliability and spatial-temporal accuracy of the 2D/3D PCM approach, which paves the way for future in vivo applications and human studies during SWL and LL.

Planar Conformal Deformation of Robotic S-Isothermic Surface

Robotic surfaces can design the space they cover by deforming and can be used in laparoscopic surgery to secure a surgical field space. In medical applications, a coordinate transformation is crucial to cooperate with other robots. However, allowing shear in the robot surfaces' deformations makes accurate coordinate transformations difficult. Robotic S-isothermic surfaces, given their mathematics, are only slightly deform in shear. In a system that combines this robot with rigid-body robots, each coordinate system can be entirely unified in the orthogonal coordinate system, simplifying the control. However, it has not been thoroughly investigated whether the deformed robot's local coordinate system is Cartesian or not. In this study, we use a rubber-like resin robotic S-isothermic surface and demonstrate that its deformation in a plane is conformal. We also show that when the deformation to the desired shape is small, there are conformal parameters close to the shape even during the deformation.