Scalar States Research Articles

Impedance-Based Li-Ion Battery Forecasting amid Uneven Usage

Accurate forecasting of Li-ion battery performance is important for easing consumer concerns about the safety and reliability of electric vehicles. Most research on battery health prognostics focuses on the R&D setting where cells are subjected to the same usage patterns, yet in practice there is great variability in use across cells and cycles, making forecasting much more challenging.In my talk, I will show that a combination of battery `biomarkers’ derived from electrochemical impedance signals with probabilistic machine learning enables us to accurately forecast future battery performance amid uneven usage, even when cell history is completely unknown. More broadly, our results bring into question the concept of a scalar State of Health, and instead suggest that battery state is better quantified by a multidimensional vector. I will discuss how this insight lays the foundations for novel algorithms for battery prognostics and control. I will further outline our application of such algorithms in optimal protocol design for intelligent battery charging, and low-data inference via transfer learning across cell chemistries and usage patterns.

Newly observed a0(1817) as the scaling point of constructing the scalar meson spectroscopy

Stimulated by the newly observed $a_0(1817)$ by the BESIII Collaboration, we find a perfect Regge trajectory composed of the $a_0(980)$, $a_0(1450)$, and $a_0(1817)$, which leads us to categorize the $a_0(980)$, $a_0(1450)$, and $a_0(1817)$ into the isovector scalar meson family. This scenario is supported by their two-body Okubo-Zweig-Iizuka allowed strong decay behaviors. In this scheme, we also predict the third radial excitation of the $a_0(980)$, which is denoted as the $a_0(2115)$, accessible at future experiment as a direct test of this assignment. We find another Regge trajectory which contains three isoscalar scalar states $f_0(980)$, $X(1812)$, and $f_0(2100)$. We investigate their two-body Okubo-Zweig-Iizuka allowed strong decay patterns, which are roughly consistent with the experimental data. The $f_0(980)$, $X(1812)$, and $f_0(2100)$ can be well grouped into the isoscalar scalar meson family. We want to emphasize that these two Regge trajectories have a similar slope. In summary, the present work provides a scheme of constructing the scalar meson family based on these reported scalar states. The possibility of the $f_0(1710)$ as the candidate of the scalar glueball cannot be excluded by the observation of the $a_0(1817)$ since the $a_0(1817)$ is more suitable as the isovector partner of the $X(1812)$.

Glueball-meson mixing in holographic QCD

Top-down holographic QCD models often work in the “probe” (or “quenched”) limit, which assumes that the number of colors is much greater than the number of flavors. Relaxing this limit is essential to a fuller understanding of holography and more accurate phenomenological predictions. In this work, we focus on a mixing of glueball and meson mass eigenstates that arises from the DBI action as a finite Nf/Nc effect. For concreteness, we work in the Witten-Sakai-Sugimoto model, and show that this mixing must be treated in conjunction with the backreaction of the flavor branes onto the background geometry. Including the backreaction with the simplification that it is “smeared out” over the compact transverse direction, we derive a corrected effective action for the vector glueball and scalar states. Along the way, we observe a Stückelberg-like mechanism that restores translation invariance in the transverse direction. We also derive a general technique, that lends itself easily to numerics, for finding mass eigenstates of Lagrangians with vector-scalar mixing. We then calculate the first order corrections to the mass spectra of both the vector and scalar particles, and show that the term that explicitly mixes vector and scalar states is the most significant correction to the masses of low-lying scalar mesons.

Analysis of the doubly-charmed tetraquark molecular states with the QCD sum rules

In the present work, we investigate the scalar, axialvector and tensor doubly-charmed tetraquark molecular states without strange, with strange and with doubly-strange via the QCD sum rules, and try to make assignment of the $T^+_{cc}$ from the LHCb collaboration in the scenario of molecular states. The predictions favor assigning the $T^+_{cc}$ to be the lighter $DD^{*}$ molecular state with the spin-parity $J^P=1^+$ and isospin $I=0$, while the heavier $DD^{*}$ molecular state with the spin-parity $J^P=1^+$ and isospin $I=1$ still escapes experimental detections, the observation of the heavier $DD^{*}$ molecular state would shed light on the nature of the $T_{cc}^+$. All the predicted doubly-charmed tetraquark molecular states can be confronted to the experimental data in the future.

Semiclassical gravitational collapse of a radially symmetric massless scalar quantum field

We present a method to study the semiclassical gravitational collapse of a radially symmetric scalar quantum field in a coherent initial state. The formalism utilizes a Fock space basis in the initial metric, is unitary and time reversal invariant up to numerical precision. It maintains exact compatibility of the metric with the expectation values of the energy momentum tensor in the scalar field coherent state throughout the entire time evolution. We find a simple criterion for the smallness of discretization effects, which is violated when a horizon forms. As a first example, we study the collapse of a specific state in the angular momentum $l=0$ approximation. Outside the simulated volume it produces a Schwarzschild metric with $r_s \sim 3.5 \ell_p$. We see behaviour that is compatible with the onset of horizon formation both in the semiclassical and corresponding classical cases in a regime where we see no evidence for large discretization artefacts. In our example setting, we see that quantum effects accelerate the possible horizon formation and move it radially outward. We find that this effect is robust against variations of the radial resolution, the time step, the volume, the initial position and shape of the inmoving state, the vacuum subtraction, the discretization of the time evolution operator and the integration scheme of the metric. We briefly discuss potential improvements of the method and the possibility of applying it to black hole evaporation. We also briefly touch on the extension of our formalism to higher angular momenta, but leave the details and numerics for a forthcoming publication.

SOiCI and iCISO: combining iterative configuration interaction with spin–orbit coupling in two ways

The near-exact iCIPT2 approach for strongly correlated systems of electrons, which stems from the combination of iterative configuration interaction (iCI, an exact solver of full CI) with configuration selection for static correlation and second-order perturbation theory (PT2) for dynamic correlation, is extended to the relativistic domain. In the spirit of spin separation, relativistic effects are treated in two steps: scalar relativity is treated by the infinite-order, spin-free part of the exact two-component (X2C) relativistic Hamiltonian, whereas spin–orbit coupling (SOC) is treated by the first-order, Douglas–Kroll–Hess-like SOC operator derived from the same X2C Hamiltonian. Two possible combinations of iCIPT2 with SOC are considered, i.e., SOiCI and iCISO. The former treats SOC and electron correlation on an equal footing, whereas the latter treats SOC in the spirit of state interaction, by constructing and diagonalizing an effective spin–orbit Hamiltonian matrix in a small number of correlated scalar states. Both double group and time reversal symmetries are incorporated to simplify the computation. Pilot applications reveal that SOiCI is very accurate for the spin–orbit splitting (SOS) of heavy atoms, whereas the computationally very cheap iCISO can safely be applied to the SOS of light atoms and even of systems containing heavy atoms when SOC is largely quenched by ligand fields.

Event-triggered stabilization of uncertain scalar switched linear systems with bounded network delay

This paper aims to stabilize an uncertain scalar switched linear system whose feedback information is transmitted over a digital communication network. The system has a scalar state. That network can only supply a finite data rate to represent the state and suffers from time-varying bounded network delay. Due to the unknown mode switch time and the unknown network delay, mode mismatch between the plant and the controller is unavoidable. By applying reachable set approximation and propagation approaches, this paper quantitatively investigates the effects of mode mismatch and model uncertainty on the system’s stability and designs communication and control strategies to guarantee the desired stability. Moreover, it proposes some novel event-triggered sampling strategies, under which the required stabilizing bit rate can be lower than that required by traditional periodic sampling strategies. Simulations are done to verify the obtained results.

Writing and reading with the longitudinal component of light using carbazole-containing azopolymer thin films

It is well known that azobenzene-containing polymers (azopolymers) are sensitive to the polarization orientation of the illuminating radiation, with the resulting photoisomerization inducing material transfer at both the meso- and macroscale. As a result, azopolymers are efficient and versatile photonic materials, for example, they are used for the fabrication of linear diffraction gratings, including subwavelength gratings, microlens arrays, and spectral filters. Here we propose to use carbazole-containing azopolymer thin films to directly visualize the longitudinal component of the incident laser beam, a crucial task for the realization of 3D structured light yet remaining experimentally challenging. We demonstrate the approach on both scalar and vectorial states of structured light, including higher-order and hybrid cylindrical vector beams. In addition to detection, our results confirm that carbazole-containing azopolymers are a powerful tool material engineering with the longitudinal component of the electric field, particularly to fabricate microstructures with unusual morphologies that differentiate from the total intensity distribution of the writing laser beam.

Primordial gravitational waves from excited states

We show that a scalar excited state with large occupation numbers during inflation leads to an enhancement of tensor modes and a characteristic pattern of order-one oscillations in the associated stochastic gravitational wave background (SGWB) sourced during inflation. An effective excited state, i.e. a departure from the Bunch-Davies vacuum, can emerge dynamically as the result of a transient non-adiabatic evolution, e.g. a sharp feature along the inflationary history. We provide an explicit example in a multifield context where the sharp feature triggering the excited state is identified with a strong turn in the inflationary trajectory. En passant, we derive a universal expression for the tensor power spectrum sourced at second order by an arbitrary number of scalar degrees of freedom during inflation, crucially taking into account the nontrivial structure of the Hilbert space in multifield setups. The SGWB sourced during inflation can overcome the standard scalar-induced SGWB sourced at horizon re-entry of the fluctuations after inflation, while being less constrained by perturbativity and backreaction bounds. In addition, one may entertain the possibility of detecting both since they peak at different frequencies exhibiting oscillations with distinct periods.

Geometric-phase-based shearing interferometry for broadband vortex state decoding

Given that spin and orbital angular momenta of photons have been widely investigated in optical communication and information processing systems, efficient decoding of optical vortex states using a single element is highly anticipated. In this work, a wavelength-independent holographic scheme has been proposed for total angular momentum sorting of both scalar and vector vortex states with a stationary broadband geometric-phase waveplate by means of reference-free shearing interferometry. The entangled spin and orbital angular momentum modes can be distinguished simultaneously based on the spin–orbit optical Hall effect in order to realize single-shot vortex detection. The viability of our scheme has also been demonstrated experimentally.

Primordial black hole evaporation and dark matter production. I. Solely Hawking radiation

Hawking evaporation of black holes in the early Universe is expected to copiously produce all kinds of particles, regardless of their charges under the Standard Model gauge group. For this reason, any fundamental particle, known or otherwise, could be produced during the black hole lifetime. This certainly includes dark matter (DM) particles. This paper improves upon previous calculations of DM production from primordial black holes (PBH) by consistently including the greybody factors, and by meticulously tracking a system of coupled Boltzmann equations. We show that the initial PBH densities required to produce the observed relic abundance depend strongly on the DM spin, varying in about $\sim 2$ orders of magnitude between a spin-2 and a scalar DM in the case of non-rotating PBHs. For Kerr PBHs, we have found that the expected enhancement in the production of bosons reduces the initial fraction needed to explain the measurements. We further consider indirect production of DM by assuming the existence of additional and unstable degrees of freedom emitted by the evaporation, which later decay into the DM. For a minimal setup where there is only one heavy particle, we find that the final relic abundance can be increased by at most a factor of $\sim 4$ for a scalar heavy state and a Schwarzschild PBH, or by a factor of $\sim 4.3$ for a spin-2 particle in the case of a Kerr PBH.

Optimal spatial patterns in feeding, fishing, and pollution

<p style='text-indent:20px;'>Infinite time horizon spatially distributed optimal control problems may show so–called optimal diffusion induced instabilities, which may lead to patterned optimal steady states, although the problem itself is completely homogeneous. Here we show that this can be considered as a generic phenomenon, in problems with scalar distributed states, by computing optimal spatial patterns and their canonical paths in three examples: optimal feeding, optimal fishing, and optimal pollution. The (numerical) analysis uses the continuation and bifurcation package <inline-formula><tex-math id="M1">\begin{document}$\mathtt{pde2path} $\end{document}</tex-math></inline-formula> to first compute bifurcation diagrams of canonical steady states, and then time–dependent optimal controls to control the systems from some initial states to a target steady state as <inline-formula><tex-math id="M2">\begin{document}$ t\to\infty $\end{document}</tex-math></inline-formula>. We consider two setups: The case of discrete patches in space, which allows to gain intuition and to compute domains of attraction of canonical steady states, and the spatially continuous (PDE) case.</p>

Modifications on the Properties of \(D^*_{s0}\)(2317) as Four-quark State in Thermal Medium

Since the low mass of $D^*_{s0}(2317)$ has still been a problem to the conventional quark model, one can consider other options regarding as multi-quark system. Therefore we investigate the scalar open-charm state $D^*_{s0}(2317)$ by Thermal QCD Sum Rules (TQCDSR) method using the two-point correlation function together with contributions of the non-perturbative condensates up to dimension six. Deriving and numerically analyzing thermal mass and pole residue sum rules, we accomplish the effects on the properties of $D^*_{s0}(2317)$ resonance in hot medium. Our numerical evaluations indicate that the variations in mass and pole residue values are stable through the growing temperature up to $T\cong100~\mathrm{MeV}$, but they begin to fall after this point. At critical temperature, the values of mass and pole residue change up to $91\%, 70\% $ of their values in vacuum in the molecular scenario and $ 91\%, 69\% $ in the diquark-antidiquark scenario. Our results does not give any definite information as to whether $D^*_{s0}(2317)$ resonance has molecular or diquark-antidiquark structure since they are very close to each other to differentiate them. Besides, we predict the hadronic parameters of the bottom partner of the $D^*_{s0}(2317)$ resonance in both molecular and diquark-antidiquark pictures. This bound state is worth investigating in future experiments. Also the detailed search of hot medium effects on the hadronic parameters of open-charm meson $D^*_{s0}(2317)$ and the bottom partner could have some implications to define the QCD phase diagram obtained from heavy-ion collision experiments. Moreover these results can be useful in distinguishing conventional quark model mesons from exotica.

Modeling student engagement using optimal control theory

<p style='text-indent:20px;'>Student engagement in learning a prescribed body of knowledge can be modeled using optimal control theory, with a scalar state variable representing mastery, or self-perceived mastery, of the material and control representing the instantaneous cognitive effort devoted to the learning task. The relevant costs include emotional and external penalties for incomplete mastery, reduced availability of cognitive resources for other activities, and psychological stresses related to engagement with the learning task. Application of Pontryagin's maximum principle to some simple models of engagement yields solutions of the synthesis problem mimicking familiar behaviors including avoidance, procrastination, and increasing commitment in response to increasing mastery.</p>

A Symmetric Two Higgs Doublet Model

In the light of ongoing experimental search efforts for the dark matter and the post-Higgs Beyond the Standard Model (BSM) null results at the Large Hadron Collider (LHC), the Electroweak sector demands to be investigated for possible new scalar states discoverable at the LHC fulfilling the role of the dark matter. In this work we present a symmetric two Higgs doublet model with a discrete interchange symmetry among the two Higgs doublets (Φ1 ↔ Φ2). Apart from the Standard Model (SM)-like scalar state (h) with mh = 125 GeV, the model has several distinguishing features including the pseudoscalar (A), the charged scalars(H±) and the neutral scalar H, not having any direct coupling to the fermions. The neutral scalar H is assumed to have mass lighter than the 125 GeV SM-like Higgs state h. Due to the presence of a residual Z2 symmetry after the spontaneous symmetry breaking (SSB), the neutral scalar H can emerge as a viable dark matter candidate. We discuss the constraints on such scalar dark matter from the current direct and indirect detection experiments. As a by-product of this construction, the SM-like scalar h ends up having an extra invisible decay mode of h → HH in this model which can also influence the dark matter parameter space. We discuss these model features in detail along with a guideline of relevant phenomenological searches at the LHC for this scenario.

Conformal block expansion in celestial CFT

The 4D 4-point scattering amplitude of massless scalars via a massive exchange is expressed in a basis of conformal primary particle wavefunctions. This celestial amplitude is expanded in a basis of 2D conformal partial waves on the unitary principal series, and then rewritten as a sum over 2D conformal blocks via contour deformation. The conformal blocks include intermediate exchanges of spinning light-ray states, as well as scalar states with positive integer conformal weights. The conformal block prefactors are found as expected to be quadratic in the celestial OPE coefficients.

Quantum backreaction on a classical universe

We study a first-order formulation for the coupled evolution of a quantum scalar field and a classical Friedmann universe. The model is defined by a state dependent Hamiltonian constraint and the time dependent Schr\"odinger equation for the scalar field. We solve the resulting nonlinear equations numerically for initial data consisting of a Gaussian scalar field state and gravity phase space variables. This gives a self-consistent semiclassical evolution that includes nonperturbative ``backreaction'' due to particle production. We compare the results with the evolution of a quantum scalar field on a fixed background, and find that the backreaction modifies both particle production and cosmological expansion, and that these effects remain bounded.

The THDMa Revisited

The THDMa is a new physics model that extends the scalar sector of the Standard Model by an additional doublet as well as a pseudoscalar singlet and allows for mixing between all possible scalar states. In the gauge-eigenbasis, the additional pseudoscalar serves as a portal to the dark sector, with a priori any dark matter spins states. The option where dark matter is fermionic is currently one of the standard benchmarks for the experimental collaborations, and several searches at the LHC constrain the corresponding parameter space. However, most current studies constrain regions in parameter space by setting all but 2 of the 12 free parameters to fixed values. In this work, we performed a generic scan on this model, allowing all parameters to float. We applied all current theoretical and experimental constraints, including bounds from current searches, recent results from B-physics, in particular Bs→Xsγ, as well as bounds from astroparticle physics. We identify regions in the parameter space which are still allowed after these were applied and which might be interesting for an investigation of current and future collider machines.

Complexity from spinning primaries

We define circuits given by unitary representations of Lorentzian conformal field theory in 3 and 4 dimensions. Our circuits start from a spinning primary state, allowing us to generalize formulas for the circuit complexity obtained from circuits starting from scalar primary states. These results are nicely reproduced in terms of the geometry of coadjoint orbits of the conformal group. In contrast to the complexity geometry obtained from scalar primary states, the geometry is more complicated and the existence of conjugate points, signaling the saturation of complexity, remains open.

Long-lived electroweak-singlet colored scalars

There has been much recent interest in long-lived massive particles at the LHC, understood as those with lifetimes between tens of micrometers and several meters. In this context, we consider the possibility of long-lived electroweak singlet scalars charged under the color SU(3) with masses near a TeV. The shortest lifetime of interest is already longer than typical hadronization scales. These exotic new particles would therefore appear as color-singlet bound states of the new scalars with quarks and gluons, and it is their color charge that prevents them from decaying. In particular, we consider color representations consistent with maintaining asymptotic freedom, those with dimensionality ${d}_{R}\ensuremath{\le}15$. We find that only the octets can decay, and they do so into multijet final states through the two-gluon channel. The other representations are stable and form fractionally charged color singlets, with the decuplet being the only one that can form electrically neutral color singlets.