String Probes Research Articles

New infinite class of 6d , N=(1,0) supergravities

We present a new infinite class of non-Abelian, 6d supergravities with eight supercharges. These theories not only satisfy all known low-energy consistency conditions, such as being free of anomalies, but also evade the constraints arising from the consistency of string probes, even after assuming completeness of the Bogomol’nyi–Prasad–Sommerfield (BPS) spectrum. This demonstrates that some additional UV input or hitherto unknown IR condition is needed in order to be left with a finite landscape, as is generally anticipated from a theory of quantum gravity. Published by the American Physical Society 2024

Inscribing geodesic circles on the face of the superstratum

We use families of circular null geodesics as probes of a family of microstate geometries, known as (1, 0, n) superstrata. These geometries carry a left-moving momentum wave and the behavior of some of the geodesic probes is very sensitive to this background wave. The left-moving geodesics behave like BPS particles and so can be placed in circular orbits anywhere in the geometry and actually “float” at fixed radius and angle in the three-dimensional “capped BTZ” geometry. The right-moving geodesics behave like non-BPS particles. We show that they provide a simple geometric characterization of the black-hole bound: when the momentum charge of the geometry is below this bound, such geodesics can be placed anywhere, but exceeding the bound, even by a small amount, means these geodesics are restricted to the deep interior of the geometry. We also show that for left-moving string probes, the tidal forces remain comparable with those of global AdS3. Nevertheless, for some of these probes, the “bumps” in the geometry induce an oscillatory mass term and we discuss how this can lead to chaotic scrambling of the state of the string.

The dual of a tidal force in the D1D5 CFT

It was demonstrated that a string probe falling radially within a superstratum geometry would experience tidal forces. These tidal forces were shown to excite the string by converting its kinetic energy into stringy excitations. Using the AdS/CFT correspondence we seek to understand this behavior from the perspective of the dual D1D5 CFT. To study this process we turn on an interaction of the theory which is described by a deformation operator. We start with an initial state which is dual to a graviton probe moving within the superstratum geometry. We then use two deformation operators to compute transition amplitudes between this state and a final state that corresponds to stringy excitations. We show that this amplitude grows as t2 with t being the amount of time for which the deformation operators are turned on. We argue that this process in the CFT is suggestive of the tidal effects experienced by the probe propagating within the dual superstratum geometry.

Effects of the acceleration on holographic complexity

In this work, we consider a special kind of space–time called AdS accelerating black holes. This is a kind of black holes which have a stringlike singularity along polar axis attached to the black hole and it accelerates the black hole. In these kind of space–times, the growth of Einstein–Hilbert action is independent of the acceleration as found in S. Chen and Y. Pei, Int. J. Theor. Phys. 60, 917 (2021). By using a string as a probe, we found the effect of the acceleration is captured by the string probe [K. Nagasaki, arXiv:2108.05429 [hep-th]]. Here in this work, we consider the case of rotating black holes. By the probe string, we clearly describe the effect of the acceleration and its relation to the rotation of the black holes.

Programming an antibody-peptide sandwich procedure for selectivity and ultrasensitive detection of fibrin using double-stranded DNA (dsDNA) hemp string probe

A novel, highly sensitive and selective sandwich-like enzyme-linked immunoassay procedure for the detection of fibrin was developed. Firstly the monoclonal anti-fibrinogen which was coated on the surface of microtiter plate can interact with fibrin, and the probe of double-stranded DNA (dsDNA) hemp string containing the homing peptide can secondarily recognize the fibrin. On the other hand, combined with the hybridization chain reaction (HCR), the terminal of dsDNA can be folded to a long G-quadruplex-hemin DNAzyme, which can catalyze luminol–H2O2 system to generate strong chemiluminescence signal. Under the optimal experimental conditions, the assay showed a linear toward fibrin concentration in the range of 0.14–72.5 pM with detection limit of 0.04 pM. Because of high selectivity and ultra-sensitivity, the designed procedure provides great potential for applications in medical diagnosis.

Twisted strings in three-dimensional black holes

We revisit the classical dynamics of fundamental strings in BTZ black holes with NSNS flux. We analyze probe strings in the black hole background and determine their classical energy using a Nambu–Goto action. Three-dimensional gravity has a non-local effect on the metric surrounding a massive object which can be measured by winding strings. We also study the behaviour of short and long strings in the Wess–Zumino–Witten orbifold and show that their energy matches the long string probe analysis. In the process, we fix subtleties in the Lorentzian choice of NSNS flux. In Euclidean signature, we analyze the one-loop fundamental string partition function on the BTZ black hole and interpret the off-shell degrees of freedom as those of a coset orbifold. Finally, we speculate on how to identify the quantum Lorentzian string spectrum from the Euclidean orbifold partition function.

Elliptical and purely NS superstrata

We analyze the BPS equations in the “superstratum sector” of three-dimensional gauged supergravity. We obtain multi-parameter supersymmetric solutions that include elliptical deformations of the supertubes that underlie standard superstrata. We uplift the three-dimensional solutions to obtain the corresponding six-dimensional geometries. This yields new families of elliptically-deformed, ambi-bolar hyper-Kähler geometries in four dimensions with a non-tri-holomorphic U(1) isometry. We also find a new family of scaling superstrata whose S-dual lives entirely within the NS-sector of supergravity, and will thus be more amenable to exact analysis using string probes. In all these new superstrata, including the scaling ones, if the momentum charge is non-zero we find that the ellipse stays away from the degeneration locus in which the ellipse becomes flat.

Open string probe in soft hair BTZ

We study the boundary CFT under supertranslation in terms of the AdS/CFT correspondence. In particular, we probe the soft hair BTZ background by several open string configurations as follows. The Ryu–Takayanaki formula of holographic entanglement remains intact under supertranslation. The U-shape string probe indicates that the flat part of meson potential is altered by the soft charge. The trailing string solution shows that the hair parameter plays the role of external field in the drag force. The study of hanging string in the Brownian motion suggests the transport variables, such as friction coefficient are likely affected by supertranslation.

TCFHs, hidden symmetries and type II theories

We present the twisted covariant form hierarchies (TCFH) of type IIA and IIB 10-dimensional supergravities and show that all form bilinears of supersymmetric backgrounds satisfy the conformal Killing-Yano equation with respect to a TCFH connection. We also compute the Killing-Stäckel, Killing-Yano and closed conformal Killing-Yano tensors of all spherically symmetric type II brane backgrounds and demonstrate that the geodesic flow on these solutions is completely integrable by giving all independent charges in involution. We then identify all form bilinears of common sector and D-brane backgrounds which generate hidden symmetries for particle and string probe actions. We also explore the question on whether charges constructed from form bilinears are sufficient to prove the integrability of probes on supersymmetric backgrounds.

Probe strings on anti-de Sitter accelerating black holes

AbstractIn this work we consider a spacial kind of spacetime called an anti-de Sitter accelerating black hole. This is a kind of black hole that contains a stringlike singularity along polar axes attached to the black hole that accelerates it. By using a string as a probe, we study the properties of the complexity growth of black holes following the complexity–action duality. We find that the growth in the Einstein–Hilbert action is independent of the acceleration but the string probe detects the effects of acceleration.

Programming an Antibody-Peptide Sandwich Procedure for Selectivity and Ultrasensitive Detection of Fibrin Using Double-Stranded DNA (Dsdna) Hemp String Probe

Programming an Antibody-Peptide Sandwich Procedure for Selectivity and Ultrasensitive Detection of Fibrin Using Double-Stranded DNA (Dsdna) Hemp String Probe

Исследование воздействия волны-убийцы на плавучий объект в мореходном бассейне

Object and purpose of research. This paper describes physical modeling of interaction process of abnormal wave (freak wave) with a marine floating structure in a seakeeping tank of the Krylov State Research Center. Freak wave is extremely dangerous because of the difference from wind waves by an unusually steep front slope and a gentle trough. Freak wave appears suddenly and collapses rapidly. Research of effect process features is necessary for understanding and analysis of the object behavior at extreme sea conditions. As experiment results it was necessary to obtain empirical data of sea object motions and accelerations at interaction with freak wave on different course angles and speeds. The obtained physical experiment results will be the foundation of theoretical studies and numerical calculation methods. Materials and methods. Physical modeling of the interaction process of freak wave with a marine floating structure was conducted in a deep seakeeping tank. Freak wave was generated by the linear superposition method of four twodimensional unidirectional regular waves with variable steepness in frequency range of 2 to 6 rad/s. To create a control signal was using special software. Wave packets were formed consisting of a sequence of a four harmonicas with a given frequency, height and duration. For parameters registration of freak wave were used string probes installed with a certain step along the length of the tank. A marine floating structure model was fixed by elastic fastening system in a window of a tow cart. For measure the motions of marine floating structure and its accelerations in define points at encounter with freak wave the contactless optic system and two-component acceleration sensors (accelerometers) were used. Cases of structure interaction with freak wave at different course angles and speeds were considered. Main results. As result of physical experimental data of floating structure motions in the interaction with freak wave in conditions of regular sea state at five course angles with speed and without speed were obtained. Dependencies of roll, pitch and heave motions at different course angles and various speeds were built. Similar dependencies of vertical and transverse accelerations on a stem also were built. Comparative analysis of results with data, which were obtained on intensive irregular sea state (spectrum JONSWAP) at identical experiment conditions, and also with foreign results was carried out. Conclusions. The greatest roll and maximum accelerations are registered at alongside position to abnormal wave, but cargo vessel has a sufficient reserve of dynamic stability to withstand such an impulse effect. The values of roll motion and accelerations on irregular sea state are close to the parameters measured at freak wave effect. This similarity is explained by rocking effect of periodic impact of irregular sea state, the proximity of natural period of roll oscillations to average period of waves and sufficiently high waves. In comparison with foreign researches, a wider range of heading angles and speeds is considered, and data about accelerations in a stem are obtained.

The harder they fall, the bigger they become: tidal trapping of strings by microstate geometries

We consider the fate of a massless (or ultra-relativistic massive) string probe propagating down the BTZ-like throat of a microstate geometry in the D1-D5 system. Far down the throat, the probe encounters large tidal forces that stretch and excite the string. The excitations are limited by the very short transit time through the region of large tidal force, leading to a controlled approximation to tidal stretching. We show that the amount of stretching is proportional to the incident energy, and that it robs the probe of the kinetic energy it would need to travel back up the throat. As a consequence, the probe is effectively trapped far down the throat and, through repeated return passes, scrambles into the ensemble of nearby microstates. We propose that this tidal trapping may lead to weak gravitational echoes.

Thin-shell wormholes in AdS5 and string dioptrics

We consider string probes in a traversable wormhole geometry that connects two locally AdS5 asymptotic regions. Holographically, this describes two interacting copies of a 4-dimensional gauge theory. We consider string configurations whose endpoints are located either in the same boundary or in the two different boundaries of the wormhole. A string with both endpoints in the same boundary is dual to a quark-antiquark pair charged under the same gauge field, while a string extending through the wormhole describes a pair of colored particles charged under two different gauge fields. When one considers a quark-antiquark pair in each boundary, the system undergoes a phase transition: while for small separation each pair of charges exhibits Coulomb interaction, for large separation the charges in different field theories pair up. This behavior had previously been observed in other geometric realizations such as locally AdS5 wormhole solutions with hyperbolic throats. The geometries we consider here, in contrast, are stable thin-shell wormholes with flat codimension-one hypersurfaces at fixed radial coordinate. They appear as electrovacuum solutions of higher-curvature gravity theories coupled to Abelian gauge fields. The presence of the thin-shells produces a refraction of the string configurations in the bulk, leading to the presence of cusps in the phase space diagram. We discuss these and other features of the phase diagram, including the analogies and difference with other wormhole solutions considered in related contexts.

Branes and the swampland

Completeness of the spectrum of charged branes in a quantum theory of gravity naturally motivates the question of whether consistency of what lives on the branes can be used to explain some of the Swampland conditions. In this paper we focus on consistency of what lives on string probes, to show some of the theories with ${\cal N}=(1,0)$ supersymmetry in 10d and 6d, which are otherwise consistent looking, belong to the Swampland. Gravitational and gauge group anomaly inflow on these probes can be used to compute the gravitational central charges $(c_L,c_R)$ as well as the level of the group's current algebra $k_L$. The fact that the left-moving central charge on the string probes should be large enough to allow {\it unitary} representations of the current algebra with a given level, can be used to rule out some theories. This in particular explains why it has not been possible to construct the corresponding theories from string theory.

Airy function and 4d quantum gravity

We study four-dimensional quantum gravity with negative cosmological constant in the minisuperspace approximation and compute the partition function for the S3 boundary geometry. In this approximation scheme the path integrals become dominated by a class of asymptotically AdS “microstate geometries.” Despite the fact that the theory is pure Einstein gravity without supersymmetry, the result precisely reproduces, up to higher curvature corrections, the Airy function in the S3 partition function of the maximally supersymmetric Chern-Simons-matter (CSM) theory which sums up all perturbative 1/N corrections. We also show that this can be interpreted as a concrete realization of the idea that the CFT partition function is a solution to the Wheeler-DeWitt equation as advocate in the holographic renormalization group. Furthermore, the agreement persists upon the inclusion of a string probe and it reproduces the Airy function in the vev of half-BPS Wilso loops in the CSM theory. These results may suggest that the supergravity path integrals localize to the minisuperspace in certain cases and the use of the minisuperspace approximation in AdS/CFT may be a viable approach to study 1/N corrections to large N CFTs.

Strings on AdS wormholes and nonsingular black holes

Certain AdS black holes in the STU model can be conformally scaled to wormhole and black hole backgrounds which have two asymptotically AdS regions and are completely free of curvature singularities. While there is a delta-function source for the dilaton, classical string probes are not sensitive to this singularity. According to the AdS/CFT correspondence, the dual field theory lives on the union of the disjoint boundaries. For the wormhole background, causal contact exists between the two boundaries and the structure of certain correlation functions is indicative of an interacting phase for which there is a coupling between the degrees of freedom living at each boundary. The nonsingular black hole describes an entangled state in two non-interacting identical conformal field theories. By studying the behavior of open strings on these backgrounds, we extract a number of features of the ‘quarks’ and ‘anti-quarks’ that live in the field theories. In the interacting phase, we find that there is a maximum speed with which the quarks can move without losing energy, beyond which energy is transferred from a quark in one field theory to a quark in the other. We also compute the rate at which moving quarks within entangled states lose energy to the two surrounding plasmas. While a quark–antiquark pair within a single field theory exhibits Coulomb interaction for small separation, a quark in one field theory exhibits spring-like confinement with an anti-quark in the other field theory. For the entangled states, we study how the quark–antiquark screening length depends on temperature and chemical potential.

Quantum hair and the string–black hole correspondence

We consider a thought experiment in which an energetic massless string probes a ‘stringhole’ (a heavy string lying on the correspondence curve between strings and black holes) at large enough impact parameter for the regime to be under theoretical control. The corresponding, explicitly unitary, S-matrix turns out to be perturbatively sensitive to the microstate of the stringhole: in particular, at leading order in ls/b, it depends on a projection of the stringhole's Lorentz-contracted quadrupole moment. The string–black hole correspondence is therefore violated if one assumes quantum hair to be exponentially suppressed as a function of black-hole entropy. Implications for the information paradox are briefly discussed.

Thermal string probes in AdS and finite temperature Wilson loops

We apply a new description of thermal fundamental string probes to the study of finite temperature Wilson loops in the context of the AdS/CFT correspondence. Previously this problem has been considered using extremal probes even though the background is at finite temperature. The new description of fundamental string probes is based on the blackfold approach. As a result of our analysis we find a new term in the potential between static quarks in the symmetric representation which for sufficiently small temperatures is the leading correction to the Coulomb force potential. We also find an order 1/N correction to the onset of the Debye screening of the quarks. These effects arise from including the thermal excitations of the string probe and demanding the probe to be in thermodynamic equilibrium with the Anti-de Sitter black hole background.

Calculating the jet quenching parameter in the plasma of noncommutative Yang-Mills theory from gauge/gravity duality

A particular decoupling limit of non-extremal (D1, D3) brane bound state system of type IIB string theory is known to give the gravity dual of space-space non- commutative Yang-Mills (NCYM) theory at finite temperature. We use a string probe in this background to compute the jet quenching parameter in the strongly coupled plasma of hot non-commutative Yang-Mills theory in (3+1)-dimensions from gauge/gravity duality. We give the expressions for the jet quenching parameter for both small and large non-commutativity. For small non-commutativity, we find that the value of the jet quenching parameter gets reduced from its commutative value. The reduction is enhanced with temperature as T^{7} for fixed non-commutativity and the fixed 't Hooft coupling. We further generalize the results for the non-commutative Yang-Mills theories in diverse dimensions.