We show that the inference problem of constraining the dipole amplitude with inclusive deep inelastic scattering data can be written into a discrete linear inverse problem, in an analogous manner as can be done for computed tomography. To this formulation of the problem, we apply standard inverse problems methods and algorithms to reconstruct known dipole amplitudes from simulated reduced cross section data with realistic precision. The main difference of this approach to previous works is that this implementation does not require any fit parametrization of the dipole amplitude. The freedom from parametrization also enables us for the first time to quantify the uncertainties of the inferred dipole amplitude in a novel more general framework. This mathematical approach to small-$x$ phenomenology opens a path to parametrization bias-free inference of the dipole amplitude from HERA and Electron-Ion Collider data.

We investigate the production mechanism for doubly charmed tetraquark mesons within a coupled-channel formalism. The two-body Feynman kernel amplitudes are constructed using effective Lagrangians that respect heavy quark symmetry, chiral symmetry, SU(3) flavor symmetry, and hidden local symmetry. The fully off-shell coupled scattering equations are solved within the Blankenbecler-Sugar reduction scheme. We find three positive-parity and one negative-parity tetraquark states with total spin $J=1$. Among them, two positive-parity states appear as bound states in the isoscalar and isovector $D{D}^{*}$ channels, while another appears as a resonance in the $D^{*}{D}^{*}$ channel. A negative-parity resonance is also predicted in the isoscalar channel. We analyze the coupling strengths of these tetraquark states to various channels. The dependence of the results on the reduced cutoff mass ${\mathrm{\Lambda }}_0$ is examined. The most significant tetraquark state remains stable within the range of ${\mathrm{\Lambda }}_0=(600–700)\mathrm{MeV}$.

We investigate the possible existence of triple-strangeness hidden-charm pentaquark states in the off-shell coupled-channel formalism. The open-charm meson-baryon ${\overline{D}}_s{\mathrm{\Omega }}_c$, ${\overline{D}}_s{\mathrm{\Omega }}_c^{*}$, ${\overline{D}}_s^{*}{\mathrm{\Omega }}_c$, and ${\overline{D}}_s^{*}{\mathrm{\Omega }}_c^{*}$ channels are considered, together with the hidden-charm $J/\psi \mathrm{\Omega }$ channel. The two-body kernel Feynman amplitudes are constructed from an effective Lagrangian based on hidden local symmetry and heavy-quark spin symmetry. The coupled Blankenbecler-Sugar equation is solved in the partial-wave helicity basis. We observe two triple-strangeness hidden-charm pentaquark states: $P_{c\overline{c}sss}(4787)$ and $P_{c\overline{c}sss}(4841)$, both with $J^P=1/2^{-}$. The $P_{c\overline{c}sss}(4787)$ couples dominantly to the ${\overline{D}}_s^{*}{\mathrm{\Omega }}_c$ and ${\overline{D}}_s^{*}{\mathrm{\Omega }}_c^{*}$ channels, while the $P_{c\overline{c}sss}(4841)$ couples almost exclusively to the ${\overline{D}}_s^{*}{\mathrm{\Omega }}_c^{*}$ channel. The total transition cross sections of ${\overline{D}}_s^{(*)}{\mathrm{\Omega }}_c^{(*)}\to J/\psi \mathrm{\Omega }$ indicate that the $P_{c\overline{c}sss}(4787)$ is clearly visible in the $J/\psi \mathrm{\Omega }$ invariant mass spectrum, whereas the $P_{c\overline{c}sss}(4841)$ is obscured by cusp structures and background contributions.

We discuss the appearance of superconducting strings in $E_6$ grand unification, keeping track of the magnetic monopole flux that precedes the formation of the string flux tube. This flux matching ensures compatibility with the quantum tunneling of a monopole-antimonopole pair on a metastable string. We identify two realistic $E_6$ models with superconducting (metastable) strings that also carry zero modes of the right-handed Majorana neutrinos and dark matter particles. Depending on the symmetry breaking scale associated with the strings, the latter could be a source of observable gravitational waves, intermediate scale dark matter, and the observed baryon asymmetry via leptogenesis. Topologically stable superconducting strings also appear if the $E_6$ symmetry breaking leaves unbroken the $Z_2$ subgroup of $Z_4$, the center of SO(10). The zero modes of the Standard Model fermions are the charge carriers in this case. Finally, the flux matching condition ensures that the Aharonov-Bohm phase change in going around the metastable strings is an integer multiple of $2\pi$ for all fields. The fields in the spinorial representation of SO(10) acquire a phase change of $\exp (\pm i\pi )$ if taken around the topologically stable $Z_2$ string.

In this work, we consider how a dynamical oscillating and phantom crossing dark energy era can be realized in the context of $F(R)$ gravity. We approach the topic from a theoretical standpoint considering all the conditions that may lead to a consistent phantom crossing behavior and, separately, how the $F(R)$ gravity context may realize an oscillating dark energy era. Apart from our qualitative considerations, we study, in a quantitative way, two $F(R)$ gravity dark energy models which are viable cosmologically and also simultaneously exhibit phantom crossing behavior and oscillating dark energy. We consider these models by numerically solving the field equations using appropriate statefinder parameters engineered for dark energy studies. As we show, $F(R)$ provides a natural extension of Einstein’s general relativity which can naturally realize a transition from a phantom era to a quintessential era, a feature supported by recent observational data, without resorting to phantom scalar fields to realize the phantom evolution.

In this paper, we present a kinematic analysis of the Universe’s expansion history using cosmography, with a particular emphasis on the jerk parameter $j_0$, which is equal to one in the standard $\mathrm{\Lambda }\mathrm{CDM}$ scenario. We use distance measurements from DESI DR2, both independently and in combination with current type Ia supernova (SN) samples, to constrain the cosmographic parameters up to the fourth order without relying on a specific cosmological model. Our results show that, for the DESI DR2 data alone, the $\mathrm{\Lambda }\mathrm{CDM}$ prediction ($j_0=1$) falls within the $2\sigma$ confidence region. However, when DESI DR2 is combined with the Union3, $\mathrm{Pantheon}+$, and DESY5 SN datasets, the result obtained is discrepant with the $\mathrm{\Lambda }\mathrm{CDM}$ model at about $3.4\sigma$, $4.1\sigma$, and $5.4\sigma$, respectively. These results are consistent with the conclusions based on dark energy parametrizations reported by the DESI collaboration, which suggest the presence of a dynamic dark energy component in the Universe.

This work investigates the impact of mirror dark matter (DM) on the global properties of rotating neutron stars (NSs) across evolutionary stages, from hot, lepton-rich protoneutron stars to cold, catalyzed NSs along the Kelvin-Helmholtz timescale. The baryonic matter (BM) is modeled using a relativistic mean-field approach with density-dependent couplings, while the dark sector mirrors the visible sector with analogous thermodynamic conditions. Using a two-fluid formalism with purely gravitational DM-BM interaction, we find that rotation enlarges the star, whereas DM admixture increases compactness and enhances gravitational stability. However, increased compactness due to DM lowers the threshold for rotational instabilities, making DM-admixed stars more susceptible. Rotation decreases central temperature behavior by redistributing thermal energy over a larger volume and reducing central density, while DM raises temperatures by deepening the gravitational potential and increasing thermal energy. Stars become more prone to collapse and rotational instabilities as frequency ($\nu$) rises and the polar-to-equatorial radius ratio ($r_p/r_e$) decreases, especially near the Keplerian limit (${\nu }_K$). DM-admixed stars also show higher surface gravitational redshifts due to their compactness. Our results qualitatively agree with universal relations primarily derived for rotating cold stars. These findings highlight competing effects of rotation and DM on NS thermal evolution, structure, and observables, potentially offering indirect probes of DM within NSs.

The next generation of gravitational-wave observatories will achieve unprecedented strain sensitivities with an expanded observing band. They will detect $\mathcal{O}({10}^5)$ binary neutron star (BNS) mergers every year, the loudest of which will be in the band for $\approx 90$ minutes with signal-to-noise ratios $\approx 1500$. We show that subtleties arising from the rotation of the Earth and the free-spectral range of gravitational-wave interferometers dramatically increases the complexity of next-gen BNS signals compared to the one-minute signals seen by LIGO-Virgo. Reduced-order quadrature, a compression method currently relied upon to speed up the most expensive BNS calculations, may no longer be effective in determining the astrophysical parameters of next-gen BNS signals. We carry out reduced-order inference on a simulated next-gen BNS signal taking into account the Earth’s rotation and the observatories’ free-spectral range. We show that reduced-order modeling becomes impractical, and the full problem becomes computationally infeasible, when we include data below $\approx 16\mathrm{Hz}$—a part of the observing band that is critical for precise sky localization. We discuss potential paths toward solving this complex problem.

Leptoquark models are prime candidates for new physics (NP) explanations of the longstanding anomalies in semileptonic $B$ decays; $b\to c\tau \overline{\nu }$ [encoded in $R(D^{(*)})$] and $b\to s\ell \overline{\ell }(\ell =e,\mu )$ transitions. Furthermore, Belle II and NA62 reported weaker-than-expected limits on $B^{+}\to K^{+}\nu \overline{\nu }$ and $K^{+}\to {\pi }^{+}\nu \overline{\nu }$, respectively. While the $R(D^{(*)})$ and $b\to s\ell \overline{\ell }$ measurements can be explained with NP contributions at the $\mathcal{O}(10\%)$ level, the neutrino channels suggest that the NP effect could be comparable in size to the Standard Model one. In this context, we consider the two types of leptoquark models with minimal sets of the couplings that can best describe the semileptonic $B$ anomalies and lead at the same time to effects in the neutrino modes, the singlet-triplet scalar leptoquark model ($S_1+S_3$) and the singlet vector leptoquark model ($U_1$). More specifically, the neutrino channels pose nontrivial constraints on the parameter space, and we find that large effects (i.e., accounting for the current central value) in $B\to K^{(*)}\nu \overline{\nu }$ are only possible in the $S_1+S_3$ setup, while both models can account for the central value of $K^{+}\to {\pi }^{+}\nu \overline{\nu }$.

Numerous theories beyond the standard model predict the existence of exotic bosons that could serve as candidates for dark matter. Here we present the Space-based Quantum Sensing for Interaction and Exotic Bosons Research Exploration scheme, along with a demonstration of a prototype space quantum sensor designed for near-future space experiments. The core concept involves probing exotic-boson-mediated spin-spin-velocity interactions between the spins within space quantum sensors and the electrons within the Earth. Unlike terrestrial counterparts, our space-based searches benefit from the significantly increased velocity provided by the orbital motion of the space quantum sensors around the Earth, which approaches the first cosmic speed. Additionally, the substantial abundance of polarized electrons within the Earth also enhances the scope of our mission. We demonstrate that our prototype space quantum sensor can suppress geomagnetic interference in space by 12 orders of magnitude, achieving a single-shot sensitivity of 4.3 fT in the sub-mHz regime. This illustrates the feasibility of conducting exotic-boson searches in the challenging space environment. As a result, the search sensitivity for such exotic interactions can be significantly enhanced by up to approximately 7 orders of magnitude compared to both terrestrial experiments and proposals. This work opens up a novel approach for searching for new physics, including space-based axion-halo searches and $CPT$ violation probes.

We explore an extension of the type-III scotogenic model through the inclusion of a real scalar singlet, which play the role of the inflaton by virtue of its nonminimal coupling to the Ricci scalar. This scalar field not only drives inflation but also decays into other particles embedded within the type-III scotogenic framework. Within this theoretical structure, both the inert scalar doublet and the fermionic triplet are instrumental in radiatively generating neutrino masses, while also emerging as viable candidates for dark matter component of the Universe. We conduct a detailed analysis of their relic abundance and assess their prospects for direct detection. Additionally, we examine the potential collider signatures associated with this framework, emphasizing avenues for experimental verification in forthcoming high energy physics experiments. Owing to the suppressed production cross section of the fermionic triplet at the LHC, we extend our analysis to the Future Circular Collider in its hadron-hadron mode (FCC-hh). Within this context, we identify the monoleptonic decay channel of the triplet fermion, accompanied by substantial missing transverse energy, as a salient and experimentally distinguishable signature of the model. Furthermore, our study reveals that the leading-order production cross section of low-mass scalar dark matter lies within the prospective sensitivity reach of both leptonic and hadronic collider experiments, thereby offering promising avenues for experimental scrutiny.

Since neutrino oscillation was observed, several experiments have been built to measure its parameters. NuMI Off-axis ${\nu }_e$ Appearance ($\mathrm{NO}\nu \mathrm{A}$) and Tokai-to-Kamioka (T2K) are two long-baseline experiments dedicated to measuring mainly the mixing angle ${\theta }_{23}$, the charge-parity ($CP$) conjugation phase ${\delta }_{\mathrm{CP}}$, and the mass ordering. However, there is a tension in current data. The T2K allowed region is in conflict with the region allowed by $\mathrm{NO}\nu \mathrm{A}$. We propose a nonstandard charged current interaction (CC-NSI) in neutrino production to relieve this tension. The CC-NSI is computed through quantum field theory formalism, where we derive perturbative analytical formulae considering CC-NSI in the pion decay. Within this new approach, we can alleviate $\mathrm{NO}\nu \mathrm{A}$ and T2K tension for CC-NSI complex parameters of order ${10}^{-3}$. We show the new phase has a degeneracy to the Dirac $CP$ phase of the form ${\delta }_{\mathrm{CP}}\pm \varphi =1.5\pi$, being a possible source of violation of charge-parity symmetry.

A growing number of applications in particle physics and beyond use neural networks as unbinned likelihood ratio estimators applied to real or simulated data. Precision requirements on the inference tasks demand a high-level of stability from these networks, which are affected by the stochastic nature of training. We show how physics concepts can be used to stabilize network training through a physics-inspired optimizer. In particular, the energy conserving descent (ECD) optimization framework uses classical Hamiltonian dynamics on the space of network parameters to reduce the dependence on the initial conditions while also stabilizing the result near the minimum of the loss function. We develop a version of this optimizer known as ${\mathsf{ECD}}_{q=1}$, which has few free hyperparameters with limited ranges guided by physical reasoning. We apply ${\mathsf{ECD}}_{q=1}$ to representative likelihood-ratio estimation tasks in particle physics and find on average that it out-performs the widely used Adam optimizer. We expect that ECD will be a useful tool for wide array of data-limited problems, where it is computationally expensive to exhaustively optimize hyperparameters and mitigate fluctuations with ensembling.

We have developed a novel methodology utilizing molecular dynamics simulations to evaluate the ionization yields of nuclear recoils in crystalline silicon. This approach enables analytical exploration of atomic-scale transport within the lattice without necessitating parametrization. The quenching factors across the nuclear recoil energy range from 20 eV to 10 keV have been thoroughly investigated. A remarkable agreement with experimental data is achieved, particularly for the minimal energy regime conducted to date, reaching the level of a single electron-hole pair. This work presents a crucial and fundamental distribution of the quenching factor, which can be associated to the collisional interactions underlying the transport phenomena. The discrepancies observed with Lindhard’s model for the quenching factor at nuclear recoil energies below 4 keV are primarily attributed to lattice binding effects and the specific characteristics of the crystal structure. In contrast, a gradual functional relationship is identified below approximately 100 eV, indicating that the quenching factor is influenced by the crystallographic orientation of the target material. From a distributional perspective, our analysis allows for the determination of the minimum exclusion mass for the dark matter nucleon elastic scattering channel at $0.29\mathrm{GeV}/c^2$, thereby significantly enhancing sensitivity for the sub-$\mathrm{GeV}/c^2$ mass region.

At the heart of quantum many-body physics lies the understanding of mechanisms that avoid quantum thermalization in an isolated system quenched far from equilibrium. A prominent example is Hilbert space fragmentation, which has recently emerged as an ergodicity-breaking mechanism in constrained spin models. Here, we show that Kogut-Susskind formulations of lattice gauge theories in $d+1\mathrm{D}$ ($d$ spatial and one temporal dimensions) give rise to Hilbert space fragmentation, and discuss possible implications for understanding continuum physics. Our findings not only prove that lattice gauge theories are a natural platform for Hilbert space fragmentation, they also serve as a guide to the conditions under which these models can be faithfully used to infer the thermalization properties of quantum chromodynamics.

We investigate properties of nuclear matter, equation of state of neutron stars, and its mass-radius relation in a hard-wall AdS/QCD model by regarding baryons as solitonic configurations in gauge fields. Compared with previous approaches, we employ a different homogeneous approximation that takes into account the equations of motion for the pure gauge fields. By choosing appropriate parameters, we realize a chiral phase transition within the baryonic phase, where the chiral condensate decreases with the baryon chemical potential, until it reaches zero—chiral symmetry is restored. In addition, independent of the existence of chiral phase transition, we also find that the speed of sound converges to the conformal limit at the density relevant to cores of massive stars but the trace of energy-momentum tensor does not vanish, which indicates the pseudoconformal structure and intrinsic manifestation of scale symmetry in compact star matter. Through calculations, we obtain an equation of state that is more tightly constrained than previous works, and the resulting mass-radius relation of neutron stars is consistent with current observations.

These notes present a comprehensive analysis of shock wave geometries in holographic settings, focusing on $\mathrm{T}\overline{\mathrm{T}}$-deformed Bañados–Teitelboim–Zanelli black holes and their extensions. By constructing deformed metrics and employing Kruskal coordinates, we examine out-of-time-ordered correlators as probes of quantum chaos. We also study localized shock wave solutions and analyze their backreaction, highlighting regimes in which the Mezei-Stanford bound on the butterfly velocity is potentially violated. The results obtained via shock wave methods are corroborated with recent developments in pole skipping phenomena and the entanglement wedge approach, demonstrating consistency among distinct probes of chaos in holographic theories.

The most active area of research in quantum-gravity phenomenology investigates the possibility of Planck-scale-modified dispersion relations, focusing mainly on two alternative scenarios: the Lorentz invariance violation (LIV) scenario, characterized by a specific mechanism of breakdown of relativistic symmetries, and the “DSR” scenario, which preserves overall relativistic invariance but with deformed laws of relativistic transformation. Two recent studies of modified dispersion relations, one relying on Finsler geometry and one based on heuristic reasoning, raised the possibility of potentially observable effects for time dilation and argued that this might apply also to the LIV and DSR scenarios. We observe that the description of Lorentz transformations in the LIV scenario is such that time dilation cannot be modified. The DSR scenario allows for modifications of time dilation, and establishing their magnitude required us to obtain novel results on the effects of finite DSR boosts in the spacetime sector, with results showing in particular that the modification of time dilation is too small for experimental testing.

It is shown to all orders of perturbation theory that in the effective field theory of general relativity the condition of vanishing of the vacuum energy leads to the same value of the cosmological constant viewed as a parameter of the effective Lagrangian, as obtained by demanding the consistency of the effective field theory in the Minkowski background. The resulting effective action is characterized by the cosmological constant term that vanishes exactly.