Axionlike particles (ALPs) are very light, neutral, spin zero bosons predicted by many theories which try to extend and complete the standard model of elementary particles. ALPs interact primarily with two photons and can generate photon-ALP oscillations in the presence of an external magnetic field. They are attracting increasing interest since photon-ALP oscillations produce deep consequences in astrophysics particularly in the very high-energy (VHE) band, where they increase the transparency of the Universe to VHE photons by partially preventing absorption caused by the extragalactic background light. Furthermore, ALPs explain why photons coming from flat spectrum radio quasars (a particular class of active galactic nuclei, AGN) have been observed for energies above 30 GeV—which represents a first hint for the existence of an ALP. In addition, ALPs solve an anomalous redshift dependence of blazar (an AGN class) spectra—which represents a second hint for the existence of an ALP. In this paper, we study another effect of the photon-ALP interaction; the change of the polarization state of photons. In particular, we study the propagation of the photon-ALP beam, starting where photons are produced—we consider photons generated in a galaxy cluster or in the jet of a blazar—crossing several magnetized media (blazar jet, host galaxy, galaxy cluster, extragalactic space, Milky Way) up to its arrival at the Earth, where photons can be detected. In the presence of the photon-ALP interaction, we analyze the final photon survival probability $P_{\gamma \to \gamma }$ and the corresponding photon degree of linear polarization ${\mathrm{\Pi }}_L$ for observed energies in the range $(1-{10}^{15})\mathrm{eV}$ dividing it into three energy bands: (i) UV-x-ray band (${10}^{-3}\mathrm{keV}–{10}^2\mathrm{keV}$), (ii) high-energy (HE) band (${10}^{-1}\mathrm{MeV}–{10}^4\mathrm{MeV}$), and (iii) VHE band (${10}^{-2}\mathrm{TeV}–{10}^3\mathrm{TeV}$). We observe that those photons, which are expected as unpolarized in the absence of ALPs, are made partially polarized by the photon-ALP interaction, which generally modifies the initial photon degree of linear polarization ${\mathrm{\Pi }}_{L,0}$ in a sizable and measurable way. Our findings can be tested by observatories like IXPE (already operative), and by the proposed missions eXTP, XL-Calibur, NGXP and XPP in the x-ray band and by the proposed missions COSI (approved to launch), e-ASTROGAM and AMEGO in the HE range. A possible detection of a departure of the photon polarization from the standard expectations would represent an additional hint for the existence of an ALP. We also discover a peculiar feature in the VHE band, where photons at energies above $\sim (1–10)\mathrm{TeV}$ are fully polarized because of the photon-ALP interaction. A possible detection of this feature would represent a proof for the existence of an ALP, but, unfortunately, current technologies do not yet allow us to detect photon polarization up to such high energies.

We study quantum effects of recently discovered kink solitons which are constructed self-consistently by coupling to a single, excited fermion bound state. Our studies are based on the observation that in a semiclassical expansion the energies of this single level and of the Dirac sea should be treated equally. For these kink solutions we compute the energy of the Dirac sea as the fermion vacuum polarization energy. We find it to be substantial and to typically outweigh the energy gain from binding the single level.

We investigate the possibility to interpret the muon $g-2$ anomaly in terms of a massive spin-2 particle, $G$, which can be identified as the first Kaluza-Klein graviton in the generalized Randall-Sundrum model. In particular, we obtain the leading-order contributions to the muon $g-2$ by calculating the relevant one-loop Feynman diagrams induced by $G$. The analytic expression is shown to keep the gauge invariance of the quantum electrodynamics and to be consistent with the expected UV divergence structure. Moreover, we impose the theoretical bounds from the perturbativity and the experimental constraints from LHC and LEP-II on our model. Especially, we derive novel perturbativity constraints on nonrenormalizable operators related to $G$, which are the natural generalization of the counterpart for the renormalizable operators. As a result, we show that there exists a substantial parameter space, which can accommodate the muon $g-2$ anomaly allowed by all constraints. Finally, we also make comments on the possible explanation of the electron $g-2$ anomalies with the massive spin-2 particle.

We perform a calculation of the interaction of the $D\overline{D}$, $D_s{\overline{D}}_s$ coupled channels and find two bound states, one coupling to $D\overline{D}$ and another one at higher energies coupling mostly to $D_s^{+}{D}_s^{-}$. We identify this latter state with the $X_0(3930)$ seen in the $D^{+}{D}^{-}$ mass distribution in the $B^{+}\to D^{+}{D}^{-}{K}^{+}$ decay, and also show that it produces an enhancement of the $D_s^{+}{D}_s^{-}$ mass distribution close to threshold which is compatible with the recent LHCb observation in the $B^{+}\to D_s^{+}{D}_s^{-}{K}^{+}$ decay which has been identified as a new state, $X_0(3960)$.

We present measurements of the branching fractions for the singly Cabibbo-suppressed decays $D^{+}\to K^{+}{K}^{-}{\pi }^{+}{\pi }^0$ and $D_s^{+}\to K^{+}{\pi }^{-}{\pi }^{+}{\pi }^0$, and the doubly Cabibbo-suppressed decay $D^{+}\to K^{+}{\pi }^{-}{\pi }^{+}{\pi }^0$, based on $980{\mathrm{fb}}^{-1}$ of data recorded by the Belle experiment at the KEKB $e^{+}{e}^{-}$ collider. We measure these modes relative to the Cabibbo-favored modes $D^{+}\to K^{-}{\pi }^{+}{\pi }^{+}{\pi }^0$ and $D_s^{+}\to K^{+}{K}^{-}{\pi }^{+}{\pi }^0$. Our results for the ratios of branching fractions are $\mathcal{B}(D^{+}\to K^{+}{K}^{-}{\pi }^{+}{\pi }^0)/\mathcal{B}(D^{+}\to K^{-}{\pi }^{+}{\pi }^{+}{\pi }^0)=(11.32\pm 0.13\pm 0.26)\%$, $\mathcal{B}(D^{+}\to K^{+}{\pi }^{-}{\pi }^{+}{\pi }^0)/\mathcal{B}(D^{+}\to K^{-}{\pi }^{+}{\pi }^{+}{\pi }^0)=(1.68\pm 0.11\pm 0.03)\%$, and $\mathcal{B}(D_s^{+}\to K^{+}{\pi }^{-}{\pi }^{+}{\pi }^0)/\mathcal{B}(D_s^{+}\to K^{+}{K}^{-}{\pi }^{+}{\pi }^0)=(17.13\pm 0.62\pm 0.51)\%$, where the uncertainties are statistical and systematic, respectively. The second value corresponds to $(5.83\pm 0.42)\times {\tan }^4{\theta }_C$, where ${\theta }_C$ is the Cabibbo angle; this value is larger than other measured ratios of branching fractions for a doubly Cabibbo-suppressed charm decay to a Cabibbo-favored decay. Multiplying these results by world average values for $\mathcal{B}(D^{+}\to K^{-}{\pi }^{+}{\pi }^{+}{\pi }^0)$ and $\mathcal{B}(D_s^{+}\to K^{+}{K}^{-}{\pi }^{+}{\pi }^0)$ yields $\mathcal{B}(D^{+}\to K^{+}{K}^{-}{\pi }^{+}{\pi }^0)=(7.08\pm 0.08\pm 0.16\pm 0.20)\times {10}^{-3}$, $\mathcal{B}(D^{+}\to K^{+}{\pi }^{-}{\pi }^{+}{\pi }^0)=(1.05\pm 0.07\pm 0.02\pm 0.03)\times {10}^{-3}$, and $\mathcal{B}(D_s^{+}\to K^{+}{\pi }^{-}{\pi }^{+}{\pi }^0)=(9.44\pm 0.34\pm 0.28\pm 0.32)\times {10}^{-3}$, where the third uncertainty is due to the branching fraction of the normalization mode. The first two results are consistent with, but more precise than, the current world averages. The last result is the first measurement of this branching fraction.

We propose a novel experimental scheme, called DAMSA (Dump-produced Aboriginal Matter Searches at an Accelerator), for searching for dark-sector particles, using rare nuclear isotope accelerator facilities that provide high-flux proton beams to produce a large number of rare nuclear isotopes. The high-intensity nature of their beams enables the investigation of dark-sector particles, including axionlike particles (ALPs) and dark photons. By contrast, their typical beam energies are not large enough to produce the backgrounds such as neutrinos resulting from secondary charged particles. The detector of DAMSA is then placed immediate downstream of the proton beam dump to maximize the prompt decay signals of dark-sector particles, which are often challenging to probe in other beam-dump-type experiments featuring a longer baseline, at the expense of an enormous amount of the beam-related neutron background. We demonstrate that beam-related neutrons can be significantly suppressed if the signal accompanies multiple, correlated visible particles in the final state. We show that the close proximity of the detector to the ALP production dump makes it possible to probe a high-mass region of ALP parameter space that the existing experiments have never explored.

Black holes provide a natural laboratory to study particle physics and astrophysics. When black holes are surrounded by matter fields, there will be plenty of phenomena which can have observational consequences, from which we can learn about the matter fields as well as black hole spacetime. In this work, we investigate the massive scalar field in the vicinity of a newly proposed rotating regular black hole inspired by quantum gravity. We will especially investigate how this nonsingular spactime will affect the superradiance instability and quasinormal modes of the scalar filed. We derive the superradiant conditions and the amplification factor by using the matching-asymptotic method, and the quasinormal modes are computed through continued fraction method. In the Kerr limit, the results are in excellent agreements with previous research. We also demonstrate how the quasinormal modes will change as a function of black hole spin, regularity described by a parameter $k$ and scalar field mass respectively, with other parameters taking specific values.

We study the scattering of gravitational waves by a Schwarzschild black hole and its perturbed siblings to investigate influences of proposed spectral instability of quasinormal modes on the ringdown signal. Our results indicate that information of dominant ringdown signals, which are ascribed to the fundamental (i.e., least damping) quasinormal mode of unperturbed Schwarzschild black holes, is imprinted in the phase shift defined from the transmission amplitude ($1/A_{\mathrm{in}}$ in our notation). This approximately parallels the fact that the resonance of quantum systems is imprinted in the phase shift of the $S$ matrix. The phase shift around the oscillation frequency of the fundamental mode is modified only perturbatively even if the quasinormal-mode spectrum is destabilized by a perturbative bump at a distant location, signifying the stability of the ringdown signal. At the same time, the phase shift at low frequencies is modulated substantially reflecting the late-time excitation of echo signals associated with the quasinormal-mode spectrum after destabilization.

We implement adaptive mesh refinement (AMR) simulations of global topological strings using the public code, grchombo. We perform a quantitative investigation of massive radiation from single sinusoidally displaced string configurations, studying a range of string widths defined by the coupling parameter $\lambda$ over two orders of magnitude, effectively varying the mass of radiated particles $m_H\sim \sqrt{\lambda }$. We perform an in-depth investigation into the effects of AMR on massive radiation emission, including radiation trapping and the refinement required to resolve high frequency modes. We use quantitative diagnostic tools to determine the eigenmode decomposition, showing a complex superposition of high frequency propagating modes with different phase and group velocities. We conclude that massive radiation is generally strongly suppressed relative to the preferred massless channel, with suppression increasing at lower amplitudes and higher $\lambda$. Only in extreme nonlinear regimes (e.g., with relative amplitude $ϵ\sim 1.5$ and $\lambda <1$) do we observe massive and massless radiation to be emitted at comparable magnitude. We find that massive radiation is emitted in distinct high harmonics of the fundamental frequency of the string, and we demonstrate that, for the sinusoidal configurations studied, massive radiation is exponentially suppressed with $\sqrt{\lambda }$ (i.e., the particle mass). Finally, we place these results in the context of axions and gravitational waves produced by cosmological cosmic string networks, and note that AMR provides a significant opportunity to explore higher $\lambda$ (thin string) regimes while using fewer computational resources.

Using the data of the Pierre Auger Observatory, we report on a search for signatures that would be suggestive of super-heavy particles decaying in the Galactic halo. From the lack of signal, we present upper limits for different energy thresholds above $\gtrsim {10}^8\mathrm{GeV}$ on the secondary by-product fluxes expected from the decay of the particles. Assuming that the energy density of these super-heavy particles matches that of dark matter observed today, we translate the upper bounds on the particle fluxes into tight constraints on the couplings governing the decay process as a function of the particle mass. Instantons, which are nonperturbative solutions to Yang-Mills equations, can give rise to decay channels otherwise forbidden and transform stable particles into metastable ones. Assuming such instanton-induced decay processes, we derive a bound on the reduced coupling constant of gauge interactions in the dark sector: ${\alpha }_X\lesssim 0.09$, for ${10}^9\lesssim M_X/\mathrm{GeV}<{10}^{19}$. Conversely, we obtain that, for instance, a reduced coupling constant ${\alpha }_X=0.09$ excludes masses $M_X\gtrsim 3\times {10}^{13}\mathrm{GeV}$. In the context of dark matter production from gravitational interactions alone during the reheating epoch, we derive constraints on the parameter space that involves, in addition to $M_X$ and ${\alpha }_X$, the Hubble rate at the end of inflation, the reheating efficiency, and the nonminimal coupling of the Higgs with curvature.

We introduce a model for nonstandard neutral current interaction (NSI) between neutrinos and the matter fields, with an arbitrary coupling to the up and down quarks. The model is based on a new $U(1)$ gauge symmetry with a light gauge boson that mixes with the photon. We show that the couplings to the $u$ and $d$ quarks can have a ratio such that the contribution from NSI to the coherent elastic neutrino-nucleus scattering ($\mathrm{CE}\nu \mathrm{NS}$) amplitude vanishes, relaxing the bound on the NSI from the $\mathrm{CE}\nu \mathrm{NS}$ experiments. Additionally, the deviation of the measured value of the anomalous magnetic dipole moment of the muon from the standard-model prediction can be fitted. The most limiting constraints on our model come from the search for the decay of the new gauge boson to $e^{-}{e}^{+}$ and invisible particles, carried out by $\mathrm{NA}48/2$ and NA64, respectively. We show that these bounds can be relaxed by opening up the decay of the new gauge boson to new light scalars that eventually decay into the $e^{-}{e}^{+}$ pairs. We show that there are ranges that can lead to both a solution to the $(g-2{)}_{\mu }$ anomaly and values of ${\epsilon }_{\mu \mu }={\epsilon }_{\tau \tau }$ large enough to be probed by future solar neutrino experiments.

If ultralight ($\ll \mathrm{eV}$), bosonic dark matter couples to right-handed neutrinos, active neutrino masses and mixing angles depend on the ambient dark matter density. When the neutrino Majorana mass, induced by the dark matter background, is small compared to the Dirac mass, neutrinos are “pseudo-Dirac” fermions that undergo oscillations between nearly degenerate active and sterile states. We present a complete cosmological history for such a scenario and find severe limits from a variety of terrestrial and cosmological observables. For scalar masses in the “fuzzy” dark matter regime ($\sim {10}^{-20}\mathrm{eV}$), these limits exclude couplings of order ${10}^{-30}$, corresponding to Yukawa interactions comparable to the gravitational force between neutrinos and surpassing equivalent limits on time variation in scalar-induced electron and proton couplings.

We investigate the use of persistent homology, a tool from topological data analysis, as a means to detect and quantitatively describe center vortices in SU(2) lattice gauge theory in a gauge-invariant manner. We provide evidence for the sensitivity of our method to vortices by detecting a vortex explicitly inserted using twisted boundary conditions in the deconfined phase. This inspires the definition of a new phase indicator for the deconfinement phase transition. We also construct a phase indicator without reference to twisted boundary conditions using a simple $k$-nearest-neighbors classifier. Finite-size scaling analyses of both persistence-based indicators yield accurate estimates of the critical $\beta$ and critical exponent of correlation length $\nu$ of the deconfinement phase transition.

The charged current (anti)neutrino induced eta production from the nucleons is studied in a model based on the effective Lagrangians to evaluate the contribution from the nonresonant and resonant diagrams. The contribution from the nonresonant background terms has been obtained using a microscopic model based on the SU(3) chiral Lagrangians. The contribution from the resonant diagrams due to the low lying $S_{11}(1535)$, $S_{11}(1650)$, and $P_{11}(1710)$ resonances has been evaluated using an effective phenomenological Lagrangian with its parameters determined from the experimental values of their branching ratios and decay widths to the $N\eta$ channel. The model is first used to reproduce satisfactorily the experimental data from the MAINZ and JLab on the total cross sections for the photo- and electro- production of $\eta$ mesons, which fixes the model parameters in the vector current interaction. The partially conserved axial vector current (PCAC) hypothesis and generalized Goldberger-Treiman relation are used to fix the parameters of the axial vector current interaction. The model is then applied to study the weak production of eta mesons induced by the neutrinos and antineutrinos, and predicts the numerical values for the $Q^2$-distribution, $\eta$-momentum distribution, and the total cross section for the reactions ${\nu }_{\mu }+n\to {\mu }^{-}+p+\eta$ and ${\overline{\nu }}_{\mu }+p\to {\mu }^{+}+n+\eta$ in the energy region up to 2 GeV. It is found that the photo, electro, and (anti)neutrino induced production of eta mesons is dominated by the contribution from the $S_{11}(1535)$ resonance. The results discussed in this work are relevant for the present and future accelerator experiments like MicroBooNE, T2K, NOvA, MINERvA, T2-HyperK, and DUNE as well as for the atmospheric neutrino experiments.

We present the first search for the weak radiative decays ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\gamma$ and ${\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0\gamma$ using a data sample of $980{\mathrm{fb}}^{-1}$ collected by the Belle detector operating at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. There are no evident ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\gamma$ or ${\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0\gamma$ signals. Taking the decays ${\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+}$ and ${\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+}$ as normalization channels, the upper limits at 90% credibility level on the ratios of branching fractions $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\gamma )/\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+})<4.0\times {10}^{-3}$ and $\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0\gamma )/\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+})<1.2\times {10}^{-2}$ are determined. We obtain the upper limits at 90% credibility level on the absolute branching fractions $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\gamma )<2.6\times {10}^{-4}$ and $\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0\gamma )<1.8\times {10}^{-4}$.

The dynamics of perturbed nonrotating black holes (BHs) can be described in terms of master equations of the wave type with a potential. In the frequency domain, the master equations become time-independent Schrödinger equations with no discrete spectrum. It has been recently shown that these wave equations possess an infinite number of symmetries that correspond to the flow of the infinite hierarchy of Korteweg–de Vries (KdV) equations. As a consequence, the infinite set of associated conserved quantities, the KdV integrals, are the same for all the different master equations that we can consider. In this paper we show that the BH scattering reflection and transmission coefficients characterizing the continuous spectrum can be fully determined via a moment problem, in such a way that the KdV integrals provide the momenta of a distribution function depending only on the reflection coefficient. We also discuss the existence and uniqueness of solutions, strategies to solve the moment problem, and finally show the case of the Pöschl-Teller potential where all the steps can be carried out analytically.

We present the improved Mathematica code which computes quasinormal frequencies with the help of the Bernstein spectral method for a general class of black holes, allowing for asymptotically flat, de Sitter or anti–de Sitter asymptotic. The method is especially efficient when searching for purely imaginary and unstable modes, and here it is used for detecting the instability region of a charged scalar field in the background of the charged asymptotically de Sitter dilatonic black hole. We show that the instability has superradiant nature and the dilaton field essentially influences the region of instability.

We compute bounds on screened scalar field theories from hydrogenlike systems. New light scalar fields generically have a direct coupling to matter. Such a coupling is strongly constrained by myriad experimental measurements. However, certain theories possess a screening mechanism that allows the effects of this coupling to weaken dynamically, and to evade many such bounds. We compute the perturbations to the energy levels of hydrogenlike systems due to screened scalar fields. We then use this result in two ways. First, we compute bounds from hydrogen spectroscopy, finding significantly weaker bounds than have been reported before as screening effects were overlooked. Second, we show that muonium is an intrinsically much more sensitive probe of screened scalar fields. For chameleon models, muonium experiments probe a large part of the parameter space that is as yet unexplored by low-energy physics and has so far only been tested by high-energy particle physics experiments.

We demonstrate the consistency of the quark deconfinement phase transition parameters in the beta-stable neutron star matter and in the nearly symmetric nuclear matter formed in heavy-ion collisions (HICs). We investigate the proton and $\mathrm{\Lambda }$ flow in $\mathrm{Au}+\mathrm{Au}$ collisions at 3 and $4.5\mathrm{GeV}/\mathrm{nucleon}$ incident beam energies with the pure hadron cascade version of a multiphase transport model. The phase transition in HICs and neutron stars is described based on a class of hybrid equations of state from the quark mean-field model for the hadronic phase and a constant-speed-of-sound parametrization for the high-density quark phase. The measurements of the anisotropic proton flow at $3\mathrm{GeV}/\mathrm{nucleon}$ by the STAR Collaboration favor a relatively low phase transition density lower than $\sim 2.5$ times saturation density indicated by the gravitational wave and electromagnetic observations of neutron stars. And the proton flow data at the higher energy of $4.5\mathrm{GeV}/\mathrm{nucleon}$ can be used to effectively constrain the softness of high-density quark matter equations of state. Finally, compared to the proton flow, the $\mathrm{\Lambda }$ flow is found to be less sensitive and not constraining to the equations of state.