String Tension Research Articles

Bioinspired Magnetized String with Tension-Dependent Eigenfrequencies for Wearable Human-Machine Interactions.

Flexible and wearable devices have exhibited potential for applications in the fields of human-machine interactions (HMIs) and Internet of Things. However, challenges remain in the improvement of the communication storage capacity with a simplified architecture. Inspired by tension regulation in natural tendons, a single-channel wearable HMI strategy is proposed using the eigenfrequency of magnetized strings as a sensing solution. Based on electromagnetic induction, mechanical vibration of the magnetized string can electrically induce periodical damping signals in the coil that are associated with the intrinsic eigenfrequency property of the string. Using a theoretical vibration model, nonoverlapping eigenfrequencies are precisely customized by designing the dimension/modulus or tension status of the string to broaden the eigenfrequency library. By integrating strings with different eigenfrequencies, multiple commands can be realized with a single communication channel. Moreover, identifiable commands can be flexibly tuned with only one magnetized string by customizing the tensile length (string tension) for eigenfrequency regulation. Demonstrations such as tactile addressing, authentication systems, and robotic control indicate the potential of the interface for multifunctional HMI applications. We expect that this strategy will provide a valuable reference for the future design of wearable HMI interfaces with high storage capacity and controllability in an accessible architecture.

Coulomb confinement in the Hamiltonian limit

The Gribov-Zwanziger scenario attributes the phenomenon of confinement to the instantaneous interaction term in the QCD Hamiltonian in the Coulomb gauge. For a static quark-antiquark pair, it leads to a potential energy that increases linearly with the distance between them. Lattice studies of the SU(2) Yang-Mills theory determined the corresponding (Coulomb) string tension for sources in the fundamental representation, σC, to be about 3 times larger than the Wilson loop string tension, σF. It is far above the Zwanziger variational bound, σC≥σF. We argue that the value often reported in the literature is artificially inflated. We examine the lattice definition of the instantaneous potential, find the source of the string tension’s enhancement, and perform its improved determination in SU(2) lattice gauge theory. We report our conservative estimate for the value of the Coulomb string tension as σC/σF=2.0±0.4 and discuss its phenomenological implications. Published by the American Physical Society 2024

Using Balancing Equipment in Archer Training

Background and purpose The implementation of balance equipment plays an essential role in archery training. It helps develop stability, accuracy, coordination, and muscular endurance, all critical for successful. Balance platforms, exercise balls, and specialized devices add extra load on stabilizer muscles, leading to a more efficient use of the body and assisting athletes in maintaining balance during string tension and targeting. The objective is to evaluate the effectiveness of balance exercises in archers' training. Material and methods Participants: 23 archers (aged 13-14) from the "KOMUNAR" Kharkiv City Specialized Youth Sports School of Olympic Archery Reserve. The experiment was conducted for 2 months from August to October 2024. At the beginning and end of the experiment, an interactive survey was conducted using a Google form. Theoretical analysis, data generalization, questionnaire method, and mathematical statistics Results Developed and implemented in the training process of exercises with fitness balls, balance pillows, boards, fitness trampolines, balancing platforms. In addition to the usual balance exercises, the archers performed stances with bowstring tension with closed and open eyes and archery on balancing devices. The use of an extended set of preparatory exercises in the training process of archers made it possible to change the attitude of athletes to physical training, improve technical skills and develop psychological stability. The introduction of new training tools contributed to increasing the motivation of archers, understanding the importance of a versatile approach in the training process to achieve high results in archery. Conclusions It is shown that the use of special exercises has a positive effect on the psychological state of young athletes, emotionality and self-confidence. Keywords Archery, balancing equipment, balance, young athletes.

Holographic QCD running coupling for light quarks in strong magnetic field

We study the influence of magnetic field on the running coupling constant using a bottom-up holographic model. We use the boundary condition that ensures the agreement with lattice calculations of string tension between quarks at zero chemical potential. The location of the 1st order phase transitions in (μ,T)-plane does not depend on the dilaton boundary conditions. We observe that the running coupling α decreases with increasing magnetic field for the fixed values of chemical potential and temperature. At the 1st order phase transitions, the functions α undergo jumps depending on temperature, chemical potential, and magnetic field. Published by the American Physical Society 2024

Kinetic mixing, proton decay and gravitational waves in SO(10)

We present an SO(10) model in which a dimension five operator induces kinetic mixing at the GUT scale between the abelian subgroups U(1)B−L and U(1)R. We discuss in this framework gauge coupling unification and proton decay, as well as the appearance of superheavy quasistable strings with Gμ ~ 10−8 – 10−5, where μ denotes the dimensionless string tension parameter. We use Bayesian analysis to show that for Gμ values ~ 4 × 10−7 − 10−5, the gravitational wave spectrum emitted from the quasistable strings is in good agreement with the recent pulsar timing array data. Corresponding to Gμ values ~ 10−8 − 2 × 10−7, proton decay is expected to occur at a rate accessible in the Hyper-Kamiokande experiment. Finally, we present the gravitational wave spectrum emitted by effectively stable strings with Gμ ≈ 10−8 that have experienced a certain amount of inflation. This can be tested with future detectors in the μHz frequency range.

Recent Patents on Piano Tuning System

Piano tuning plays a very important role in piano playing and music education. Regular tuning can prolong the service life of the piano, improve the sound saturation, and make the sound more concentrated and full. Automated mechanical equipment, controllers, sensors, and other equipment are used to automatically tune pianos to solve the problems of human error, overtone resonance interference, string breakage, etc., occurring in manual tuning. To solve the above problems, based on the synthesis of related patents and research results, the patents on automatic tuning system and methods for modulating piano are introduced in detail. An automatic tuning system can replace manual tuning, simplify the complex process of tuning, and consider the problem of overtone interference caused by the vibration of the strings to improve the accuracy of tuning; it can, at the same time, perform real-time monitoring of the string tension, protecting the strings from breaking due to tuning. The automatic tuning system has a simple structure and a high degree of automation; its method is highly accurate and it can replace professional tuning technicians, being highly innovative and widely practical.

Spectrum of global string networks and the axion dark matter mass

Cold dark matter axions produced in the post-inflationary Peccei-Quinn symmetry breaking scenario serve as clear targets for their experimental detection, since it is in principle possible to give a sharp prediction for their mass once we understand precisely how they are produced from the decay of global cosmic strings in the early Universe. In this paper, we perform a dedicated analysis of the spectrum of axions radiated from strings based on large scale numerical simulations of the cosmological evolution of the Peccei-Quinn field on a static lattice. Making full use of the massively parallel code and computing resources, we executed the simulations with up to 112643 lattice sites, which allows us to improve our understanding of the dependence on the parameter controlling the string tension and thus give a more accurate extrapolation of the numerical results. We found that there are several systematic effects that have been overlooked in previous works, such as the dependence on the initial conditions, contaminations due to oscillations in the spectrum, and discretisation effects, some of which could explain the discrepancy in the literature. We confirmed the trend that the spectral index of the axion emission spectrum increases with the string tension, but did not find a clear evidence of whether it continues to increase or saturates to a constant at larger values of the string tension due to the severe discretisation effects. Taking this uncertainty into account and performing the extrapolation with a simple power law assumption on the spectrum, we find that the dark matter mass is predicted in the range of m a ≈ 95–450 μeV.

Thermodynamic relation of accelerating black holes in anti-de Sitter spacetime

We consider accelerating black holes in four-dimensional anti-de Sitter spacetime and investigate the extremality relations by examining perturbative corrections to both the entropy of black holes and their extremality bounds. It is shown that the so-called Goon and Penco (univeral) relation is also valid for accelerating black holes. Furthermore, it is found that an appropriate matching condition is necessary between the perturbation parameter of the relation with the perturbative correction to such black holes, and the parameter with information about the conical deficits on the north and south poles with the cosmic string tensions in order to satisfy the extremality relations. This result indicates that the extremality (univeral) relation of a class of accelerating black holes holds exhibit behavior similar to the Weak Gravity Conjecture.

Bootstrapping the Abelian lattice gauge theories

We study the ℤ2 and U(1) Abelian lattice gauge theories using a bootstrap method, in which the loop equations and positivity conditions are employed for Wilson loops with lengths L ⩽ Lmax to derive two-sided bounds on the Wilson loop averages. We address a fundamental question that whether the constraints from loop equations and positivity are strong enough to solve lattice gauge theories. We answer this question by bootstrapping the 2D U(1) lattice gauge theory. We show that with sufficiently large Lmax = 60, the two-sided bounds provide estimates for the plaquette averages with precision near 10−8 or even higher, suggesting the bootstrap constraints are sufficient to numerically pin down this theory. We compute the bootstrap bounds on the plaquette averages in the 3D ℤ2 and U(1) lattice gauge theories with Lmax = 16. In the regions with weak or strong coupling, the two-sided bootstrap bounds converge quickly and coincide with the perturbative results to high precision. The bootstrap bounds are well consistent with the Monte Carlo results in the nonperturbative region. We observe interesting connections between the bounds generated by the bootstrap computations and the Griffiths’ inequalities. We present results towards bootstrapping the string tension and glueball mass in Abelian lattice gauge theories.

Wilson loops and random matrices

Linear confinement with Casimir scaling of the string tension in confining gauge theories is a consequence of a certain property of the Polyakov loop related to random matrices. This mechanism does not depend on the details of the theories (neither the gauge group nor dimensions) and explains approximate Casimir scaling below string-breaking length. In this paper, we study 3d SU(2) pure Yang-Mills theory numerically and find the same random-matrix behavior for rectangular Wilson loops. We conjecture that this is a universal feature of strongly coupled confining gauge theories.

Nonextensivity and temperature fluctuations of the Higgs boson production

We determine the temperature fluctuations associated with the Higgs boson pT spectrum through the derivation of the string tension distribution corresponding to the QCD-based Hagedorn function, frequently used to fit the transverse momentum distribution (TMD). The identified string tension fluctuations are heavy tailed, behaving similarly to the q-Gaussian distribution. After the convolution with the Schwinger mechanism, both approaches correctly describe the entire TMD. This approach leads to the nonthermal description of the particle production in ultrarelativistic pp collisions. By analyzing the data of pp collisions at s=13 TeV, we found that the average temperature associated with the Higgs boson differential cross section is around 85 times greater than the estimated value for the charged particle TMD. Our results show that the Higgs boson production exhibits the largest deviation from the thermal description. Published by the American Physical Society 2024

Investigating two-dimensional adjoint QCD on the lattice

We present our investigations of SU(N) adjoint QCD in two dimensions with one Majorana fermion on the lattice. We determine the relevant parameter range for the simulations with Wilson fermions and present results for Polyakov loop, chiral condensate, and string tension. In the theory with massive fermions, all observables we checked show qualitative agreement between numerical lattice data and theory, while the massless limit is more subtle since chiral and non-invertible symmetry of the continuum theory are explicitly broken by lattice regularization. In thermal compactification, we observe N perturbative vacua for the holonomy potential at high-T with instanton events connecting them, and a unique vacuum at low-T. At finite-N, this is a cross-over and it turns to a phase transition at large-N thermodynamic limit. In circle compactification with periodic boundary conditions, we observe a unique center-symmetric minimum at any radius. In continuum, the instantons in the thermal case carry zero modes (for even N) and indeed, in the lattice simulations, we observe that chiral condensate is dominated by instanton centers, where zero modes are localized. We present lattice results on the issue of confinement vs. screening in the theory and comment on the roles of chiral symmetry and non-invertible symmetry.

Investigation of the ensemble of maximal center gauge

The maximal center gauge aims to detect center vortices by maximizing a gauge functional and then projecting onto the center elements of the respective group. The requirement for unrestricted maximization of the gauge functional has proven to be untenable because it was shown that it leads to an underestimation of the string tension. To counter this problem, the ensemble of local gauge maxima is investigated and it is found that the unrestricted maximization can be replaced by a maximization restricted to the Gaussian distributed part of the ensemble. Such restricted maximization weakens the problem of an underestimated string tension. Published by the American Physical Society 2024

Confinement slingshot and gravitational waves

In this paper, we introduce and numerically simulate a quantum-field-theoretic phenomenon called the gauge “slingshot” effect and study its production of gravitational waves. The effect occurs when a source, such as a magnetic monopole or a quark, crosses the boundary between the Coulomb and confining phases. The corresponding gauge field of the source, either electric or magnetic, gets confined into a flux tube stretching in the form of a string (cosmic or a QCD type) that attaches the source to the domain wall separating the two phases. The string tension accelerates the source toward the wall as sort of a slingshot. The slingshot phenomenon is also exhibited by various sources of other codimensionality, such as cosmic strings confined by domain walls or vortices confined by Z2 strings. Apart from the field-theoretic value, the slingshot effect has important cosmological implications, as it provides a distinct source for gravitational waves. The effect is expected to be generic in various extensions of the standard model such as grand unification. Published by the American Physical Society 2024

Effective interactions of the open bosonic string via field theory

We describe a method to extract an effective Lagrangian description for open bosonic strings, at zero transcendentality. The method relies on a particular formulation of its scattering amplitudes derived from color-kinematics duality. More precisely, starting from a (DF)2 + YM quantum field theory, we integrate out all the massive degrees of freedom to generate an expansion in the inverse string tension α′. We explicitly compute the Lagrangian terms through O\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{O} $$\\end{document}(α′4), and target the sector of operators proportional to F4 to all orders in α′.

Cosmic string solution to the radio synchrotron background

We investigate the low-frequency spectral emission from a network of superconducting cosmic string loops in hopes of explaining the observed radio synchrotron background. After considering constraints from a variety of astrophysical and cosmological measurements, we identify a best-fit solution with string tension Gμ≃6.5×10−12 and current I≃2.5×106 GeV. This model yields a convincing fit to the data and may be testable in the near future by spectral distortion (TMS, BISOU) and 21 cm experiments (HERA, SKA, REACH). We also find that soft photon heating protects us against current constraints from global 21 cm experiments. Published by the American Physical Society 2024

Exploring the physical properties of strange star SAXJ1808.4–3658 in rainbow gravity

This study investigated the formation and evolution of a strange star known as SAX.J1808.4–3658 in the Krori–Barua Rainbow spacetime, resulting from the collapse of string fluid. The study examined the dynamical variables derived from the field equations, taking into consideration the influence of the particle’s energy on the mass density, pressure, and string tension. Additionally, various techniques were employed to analyze the physical properties, including gradients, energy conditions, anisotropy, stability, the Tolman–Oppenheimer–Volkoff equation, mass function, compactness, and red-shift. The study’s findings revealed that the strange star SAX.J1808.4–3658 satisfies all the conditions necessary for its evolution from an anisotropic string fluid. This discovery suggests that strange stars might have emerged during the string-oriented quark era of the Universe. The researchers presented all the physical quantities within the frameworks of both rainbow gravity and general relativity, while also utilizing graphical representations to aid in comprehending the study’s findings. The energy conditions and anisotropy were found to be fulfilled, indicating the stability of the strange star. Furthermore, the Tolman–Oppenheimer–Volkoff equation was employed to determine the maximum mass of the strange star, which was found to align with observational data.

The θ-dependence of the Yang-Mills spectrum from analytic continuation

We study the θ-dependence of the string tension and of the lightest glueball mass in four-dimensional SU(N) Yang-Mills theories. More precisely, we focus on the coefficients parametrizing the Oθ2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{O}\\left({\ heta}^2\\right) $$\\end{document} dependence of these quantities, which we investigate by means of numerical simulations of the lattice-discretized theory, carried out using imaginary values of the θ parameter. Topological freezing at large N is avoided using the Parallel Tempering on Boundary Conditions algorithm. We provide controlled continuum extrapolations of such coefficients in the N = 3 case, and we report the results obtained on two fairly fine lattice spacings for N = 6.

All-order exact solutions for non-linear Yang–Mills theory

We show that the so-called ’t Hooft–Polyakov monopole solution in D=(3,1) dimensions satisfies the field equations of a wide set of non-linear Yang–Mills (YM) actions to all orders in the parameter α that is inversely proportional to the string tension T. Here the expression D=(s,t) is for the (s+t)dimensional space–time with the signature ((+)s,(−)t), namely s positive and t negative signatures. We show that the so-called Born–Infeld (BI) action is only a special case of a general set of non-linear YM theories. We also consider BI-actions in D=(2,2) dimensions, and show that the self-dual SU(2) instanton (BPSTH) solution satisfies the field equations of BI-like actions perturbatively to all orders inα. In D=(2,2) dimensions, the usual action-principle problem for (anti)self-dual ((A)SD) YM field strengths is avoided by auxiliary-gravity lagrangians. The conditions on non-linear YM theories to have the ’t Hooft–Polyakov monopole solution to all orders in α in D=(3,1) dimensions, or similarly the BPSTH instanton solution in D=(2,2) dimensions, allow infinitely many non-linear YM actions in these dimensions.

Quantum tunneling in the early universe: stable magnetic monopoles from metastable cosmic strings

We present a novel mechanism for producing topologically stable monopoles (TSMs) from the quantum mechanical decay of metastable cosmic strings in the early universe. In an SO(10) model this mechanism yields TSMs that carry two units (4π/e) of Dirac magnetic charge as well as some color magnetic charge which is screened. For a dimensionless string tension parameter Gμ ≈ 10-9-10-5, the monopoles are superheavy with masses of order 1015-1017 GeV. Monopoles with masses of order 108-1014 GeV arise from metastable strings for Gμ values from ∼ 10-22 to 10-10. We identify the parameter space for producing these monopoles at an observable level with detectors such as IceCube and KM3NeT. For lower Gμ values the ultra-relativistic monopoles should be detectable at Pierre Auger and ANITA. The stochastic gravitational wave emission arise from metastable strings with Gμ ∼ 10-9-10-5 and should be accessible at HLVK and future detectors including the Einstein Telescope and Cosmic Explorer. An E 6 extension based on this framework would yield TSMs from the quantum mechanical decay of metastable strings that carry three units (6π/e) of Dirac magnetic charge.