We have performed a systematic study of the statistical behavior of non-Poissonian template fitting (NPTF), a method designed to analyze and characterize unresolved point sources in general counts datasets. In this paper, we focus on the properties and characteristics of the Fermi-LAT gamma-ray data set. In particular, we have simulated and analyzed gamma-ray sky maps under varying conditions of exposure, angular resolution, pixel size, energy window, event selection, and source brightness. We describe how these conditions affect the sensitivity of NPTF to the presence of point sources, for inner-galaxy studies of point sources within the Galactic Center excess, and for the simplified case of isotropic emission. We do not find opportunities for major gains in sensitivity from varying these choices, within the range available with current Fermi-LAT data. We provide an analytic estimate of the NPTF sensitivity to point sources for the case of isotropic emission and perfect angular resolution, and find good agreement with our numerical results for that case.

We revisit constraints on decaying very heavy dark matter (VHDM) using the latest ultrahigh-energy cosmic-ray (UHECR; $E\gtrsim {10}^{18}\mathrm{eV}$) data and ultrahigh-energy (UHE) $\gamma$-ray flux upper limits, measured by the Pierre Auger Observatory. We present updated limits on the VHDM lifetime (${\tau }_{\chi }$) for masses up to $\sim {10}^{15}\mathrm{GeV}$, considering decay into quarks, leptons, and massive bosons. In particular, we consider not only the UHECR spectrum but their composition data that favors heavier nuclei. Such a combined analysis improves the limits at $\lesssim {10}^{12}\mathrm{GeV}$ because VHDM decay does not produce UHECR nuclei. We also show that the constraints from the UHE $\gamma$-ray upper limits are $\sim 10$ more stringent than that obtained from cosmic rays, for all of the Standard Model final states we consider. The latter improves our limits to VHDM lifetime by a factor of two for dark matter mass $\gtrsim {10}^{12}\mathrm{GeV}$.

We study the detectability of gravitational-wave signals from subsolar-mass binary neutron star systems by the current generation of ground-based gravitational-wave detectors. We find that finite size effects from large tidal deformabilities of the neutron stars and lower merger frequencies can significantly impact the sensitivity of the detectors to these sources. By simulating a matched-filter based search using injected binary neutron star signals with tidal deformabilities derived from physically motivated equations of state, we calculate the reduction in sensitivity of the detectors. We conclude that the loss in sensitive volume can be as high as 78.4% for an equal mass binary system of chirp mass $0.17M_{\odot }$, in a search conducted using binary black hole template banks. We use this loss in sensitive volume, in combination with the results from the search for subsolar-mass binaries conducted on data collected by the LIGO-Virgo observatories during their first three observing runs, to obtain a conservative upper limit on the merger rate of subsolar-mass binary neutron stars. Since the discovery of a low-mass neutron star would provide new insight into formation mechanisms of neutron stars and further constrain the equation of state of dense nuclear matter, our result merits a dedicated search for subsolar-mass binary neutron star signals.

Proceeding from a stormy day on 22 September 2022, when seven thunderstorm ground enhancements occurred (TGEs, three of them very large), we analyze closely the TGEs’ energy spectra and conditions supporting the unleashing of the intense particle flux. For the first time, we present a detailed analysis of the shape of the TGE energy spectra in the energy range from 0.3 to 50 MeV and discuss the conditions of TGE origination. The cross calibration of different detectors is possible thanks to the $24/7$ monitoring of particle fluxes with numerous detectors and spectrometers operated on Aragats cosmic ray observatory. Despite the difficulties of measuring energy spectra from an electron accelerator with a beam size of several ${\mathrm{km}}^2$, which can change the electron energy in seconds, we reliably recover energy spectra of electrons and gamma rays. We estimate the intensity of the most significant particle flux to be $\approx 1,25$ million TGE particles with energies greater than 0.3 MeV hitting each square meter of surface on Aragats, 3200 asl. We analyze the charged structure of the thundercloud giving birth to the operation of the lower dipole, which accelerates electrons, and discuss the precursors of the lighting flashes.

We analyze the dynamics of a light scalar field responsible for the $\mu$ term of the Higgs potential and coupled to matter via the Higgs-portal mechanism. We find that this dilaton model is stable under radiative corrections induced by the standard model particle masses. When the background value of the scalar field is stabilized at the minimum of the scalar potential, the scalar field fluctuations only couple quadratically to the massive fields of the standard model preventing the scalar direct decay into standard model particles. Cosmologically and prior to the electroweak symmetry breaking, the scalar field rolls down along its effective potential before eventually oscillating and settling down at the electroweak minimum. These oscillations can be at the origin of dark matter due to the initial misalignment of the scalar field compared to the electroweak minimum, and we find that, when the mass of the scalar field is less than the electron volt scale and acts as a condensate behaving like dark matter on large scales, the scalar particles cannot thermalize with the standard model thermal bath. As matter couples in a composition-dependent manner to the oscillating scalar, this could lead to a violation of the equivalence principle aboard satellites such as the MICROSCOPE experiment and the next generation of tests of the equivalence principle. Local gravitational tests are evaded thanks to the weakness of the quadratic coupling in the dark matter halo, and we find that, around other sources, these dilaton models could be subject to a screening akin to the symmetron mechanism.

The kinetic mixing (KM) of a dark photon (DP) with the familiar one of the Standard Model (SM) requires the existence of a new set of fields, called portal matter (PM), which carry both SM and dark sector quantum numbers, some of whose masses may lie at the TeV scale. In the vanilla KM model, the dark gauge group is just the simple $G_{\mathrm{Dark}}=U(1{)}_D$ needed to describe the DP while the SM gauge interactions are described by the usual $G_{\mathrm{SM}}=SU(3{)}_c\times SU(2{)}_L\times U(1{)}_Y$. However, we need to go beyond this simple model to gain a better understanding of the interplay between $G_{\mathrm{SM}}$ and $G_{\mathrm{Dark}}$ and, in particular, determine how they both might fit into a more unified construction. Following our previous analyses, this generally requires $G_{\mathrm{Dark}}$ to be extended to a non-Abelian group, e.g., $SU(2{)}_I\times U(1{)}_{Y_I}$, under which both the PM and SM fields may transform nontrivially. In this paper, also inspired by our earlier work on top-down models, we consider extending the SM gauge group to that of the left-right symmetric model (LRM) and, in doing so, through common vacuum expectation values, link the mass scales associated with the breaking of $G_{\mathrm{Dark}}\to U(1{)}_D$ and the PM fields to that of the RH-neutrino as well as the heavy gauge bosons of the LRM. This leads to an interesting interplay between the now coupled phenomenologies of both visible and dark sectors at least some of which may be probed at, e.g., the LHC and/or at the future FCC-hh.

The $W$-boson mass measurement recently reported by the CDF-II experiment exhibits a significant deviation from both the Standard Model prediction and previous measurements. There is also a long-standing deviation between the Standard Model prediction of the forward-backward asymmetry of the bottom quark ($A_{\mathrm{FB}}^{0,b}$) and its measurement at the LEP experiment. The beautiful mirror model, proposed to resolve the $A_{\mathrm{FB}}^{0,b}$ discrepancy, introduces vectorlike quarks that modify the $W$-boson mass at the one-loop level. In this study, we find an interesting region in the model parameter space that could potentially explain both discrepancies, which puts the new quarks in the multi-TeV region. This region is mostly consistent with current LHC bounds from direct searches and Higgs coupling measurements, but will be thoroughly probed at the high-luminosity LHC. As such, the beautiful mirror model as an explanation of the $m_W$ and $A_{\mathrm{FB}}^{0,b}$ discrepancies could be confirmed or falsified in the near future.

In the framework of the quark delocalization color screening model, we search for the double-charm and double-strange tetraquark $X_{cc\overline{s}\overline{s}}$ with two structures: $Q\overline{q}-Q\overline{q}$ and $QQ-\overline{q}\overline{q}$. The bound-state calculation shows that there is no bound state in the present work. However, by applying a stabilization calculation and coupling all channels of both structures, two new resonance states with $I{J}^P=00^{+}$ are obtained, one with mass and width around 4250 and 6 MeV, respectively, and another one with mass and width around 4300 and 19 MeV, respectively. Both of these states are more likely to be the compact resonance states. Although no significant signals were observed in the present experiment at the Belle Collaboration, there are still some structures around 4.3 GeV in the distributions of $M_{D_s^{+}{D}_s^{+}}$ and $M_{D_s^{*+}{D}_s^{*+}}$. We suggest that the experiment can be further tested with a larger amount of data.

We introduce a methodology and investigate the feasibility of measuring quantum properties of tau lepton pairs in the $H\to {\tau }^{+}{\tau }^{-}$ decay at future lepton colliders. In particular, observation of entanglement, steerability, and violation of Bell inequalities are examined for the International Linear Collider (ILC) and Future Circular $e^{+}{e}^{-}$ Collider (FCC-ee). We find that detecting quantum correlation crucially relies on precise reconstruction of the tau lepton rest frame, and a simple kinematics reconstruction does not suffice due to the finite energy resolution of the colliding beams and detectors. To correct for energy mismeasurements, a log-likelihood method is developed that incorporates the information of impact parameters of tau lepton decays. We demonstrate that an accurate measurement of quantum properties is possible with this method. As a by-product, we show that a novel model-independent test of $CP$ violation can be performed and the $CP$ phase of $H\tau \tau$ interaction can be constrained with an accuracy comparable to dedicated analyses, i.e., up to 7.9° and 5.4° at ILC and FCC-ee, respectively.

Can modern cosmological observations be reconciled with a general-relativistic Universe without an antigravitating energy source? Usually, the answer to this question by cosmologists is in the negative, and it is commonly believed that the observed excess dimming of supernovae relative to that in the Milne model is evidence for dark energy. In this paper, we develop theorems that clarify the conditions for such an excess dimming, based on which we argue that the answer to the above question may counterintuitively be “yes.”

We investigate aspects of spontaneous breakdown of symmetry for the $O(N)$ symmetric linear sigma model in the background of Rindler and anti–de Sitter spacetimes respectively. In the large $N$ limit, by computing the one-loop effective action, we report that in three dimensional Rindler space, there is a phase transition from the disordered phase to an ordered phase past a certain critical Rindler acceleration parameter “$a$.” Connections with finite temperature field theory results are established, thereby further reinforcing the idea that Rindler space can indeed be a proxy for Minkowski spacetime with finite temperature. We extend our calculations to anti-de Sitter space in various dimensions and observe that symmetry is broken in three dimensions, but not in four dimensions. We discuss the implications of our results.

The Gildener-Weinberg models are of particular interest in the context of extensions to the Standard Model of particle physics. These extensions may encompass a variety of theories, including double Higgs models, grand unification theories, and proposals for dark matter, among others. In order to rigorously test these models experimentally, obtaining precise results is of crucial importance. In this study, we employ the renormalization group equation and its one-loop functions to obtain a deeper understanding of the higher-loop effective potential. Our findings reveal that the radiatively generated mass of the light particle in the Gildener-Weinberg approach experiences a substantial correction. Furthermore, our results suggest that not all flat directions are equivalent and some may be preferred by nature.

A perturbative scheme is applied to calculate corrections to the leading, exponentially small (beyond-all-orders) amplitude of the “trailing” wave asymptotics of weakly localized solitons. The model considered is a Korteweg–de Vries equation modified by a fifth order derivative term, ${\epsilon }^2{\partial }_x^5$ with $\epsilon \ll 1$ (fKdV). The leading order corrections to the tail amplitude are calculated up to $\mathcal{O}({\epsilon }^5)$. An arbitrary precision numerical code is implemented to solve the fKdV equation and to check the perturbative results. Excellent agreement is found between the numerical and analytical results. Our work also clarifies the origin of a long-standing disagreement between the $\mathcal{O}({\epsilon }^2)$ perturbative result of Grimshaw and Joshi [SIAM J. Appl. Math. 55, 124 (1995)] and the numerical results of Boyd [Comput. Phys. 9, 324 (1995)].

We propose a new simple model of acoustic black hole in a thin tube, where the difference in the gravitational potential is used to create a transonic flow. The main merit of our transonic flow model is that the Euler equations can be solved analytically. In fact, we can obtain an exact solution to the equation in terms of a height function in the monatomic case $\gamma =5/3$. For arbitrary $\gamma$, we find that it takes a simple form by the near-sonic approximation. Moreover, we obtain two analytic solutions describing a backward wave and a forward wave, from which we can confirm the existence of sonic horizons.

We reexamine the static and spherical symmetric compact star configuration in the $R^2$ model of the $F(R)$ gravity theory. With asymptotic solutions for the additional scalar degrees of freedom, we refine analysis on the external geometry and settle the scalar-hair problem argued in previous works. Performing the numerical integration of the modified Tolman-Oppenheimer-Volkoff equations as a two-boundaries-value problem, we further discuss the scalar-field distribution inside the compact stars and its influence on the mass-radius relation. We show that the chameleon potential plays an essential role in determining the scalar field inside the star. The scalar field often behaves as a quintessential field that effectively decreases the mass of compact stars with lower central energy density.

Studies of black hole superradiance often focus on the growth of a cloud in isolation, accompanied by the spin-down of the black hole. In this paper, we consider the additional effect of the accretion of matter and angular momentum from the environment. We show that, in many cases, the black hole evolves by drifting along the superradiance threshold, in which case the evolution of its parameters can be described analytically or semianalytically. We quantify the conditions under which accretion can serve as a mechanism to increase the cloud-to-black hole mass ratio, beyond the standard maximum of about 10%. This occurs by a process we call oversuperradiance, whereby accretion effectively feeds the superradiance cloud, by way of the black hole. We give two explicit examples: accretion from a vortex expected in wave dark matter and accretion from a baryonic disk. In the former case, we estimate the accretion rate by using an analytical fit to the asymptotic behavior of the confluent Heun function. Level transition, whereby one cloud level grows while the other shrinks, can be understood in a similar way.

In this paper, writing the most general form $f(R)={\sum }_{i=1}^n{a}_i{R}^i+\mathrm{\Lambda }$ the solutions of the pure geometric thick $f(R)$ brane are investigated. For the certain value of $n$, the analytical thick brane solution can be calculated, and when $n=3$, $n=4$, and $n=10$, the thick brane solutions are presented. The solutions are stable against linear tensor perturbations. The zero mode of gravity and scalar field can be localized on thick $f(R)$ branes naturally. The zero mode of a vector field and left-chiral fermion can be localized on thick $f(R)$ branes by introducing the coupling with scalar curvature $R$ of spacetime, and the massive resonant modes can be quasilocalized on the brane with the large coupling coefficients.

We analyze the quasinormal modes (QNMs) of a recently obtained solution of a Schwarzschild black hole (BH) with corrections motivated by Loop Quantum Gravity (LQG). This spacetime is regular everywhere and presents the global structure of a black bounce, whose radius depends on a LQG parameter. We focus on the investigation of massless scalar field perturbations over the spacetime. We compute the QNMs with the Wentzel-Kramers-Brillouin approximation as well as the continued fraction method. The QNM frequency orbits, for $l=0$ and $n>0$, where $l$ and $n$ are the multipole and overtone numbers, respectively, are self-intersecting, spiraling curves in the complex plane. These orbits accumulate to a fixed complex value corresponding to the QNMs of the extremal case. We obtain that, for small values of the LQG parameter, the overall damping decreases as we increase the LQG parameter. Moreover, the spectrum of the quantum corrected black hole exhibits an oscillatory pattern, which might imply in the existence of QNMs with vanishing real part. This pattern suggests that the limit $n\to \infty$ for the real part of the QNMs is not well defined, which differs from Schwarzschild’s case. We also analyze the time-domain profiles for the scalar perturbations, showing that the LQG correction does not alter the Schwarzschild power-law tail. We compute the fundamental mode from the time profile by means of the Prony method, obtaining excellent agreement with the two previously mentioned methods.

We recently studied neutrinos flavor oscillations in vacuum within conformal coupling models. In this paper, we extend that analysis by investigating neutrino flavor oscillations inside matter within a general conformal coupling scenario. We first derive the general formula for the flavor transition probability inside matter in arbitrary static and spherically symmetric spacetimes. The modified resonance formula of the Mikheyev-Smirnov-Wolfenstein effect is derived and the corresponding adiabaticity parameter of the effect is extracted. An application of our results to the case of two-flavor neutrinos within the well-known chameleon and symmetron conformal coupling models is made.

By considering a misaligned (asymptotically uniform) magnetic field in the background of a rotating black hole, we uncover a possibility for a highly nontrivial motion of Carrollian particles on the black hole horizon that is characterized by a time-dependent velocity field and reminds us (because of its latitudinal oscillations) of a “monarch butterfly migration.”