In this work we calculate the angular deflection of light in the strong field limit in two spacetimes which were previously studied within the Eddington-inspired Born-Infeld gravity, namely, a black hole and a wormhole, both with topological charge. We show that the presence of the parameters characterizing Eddington-inspired Born-Infeld gravity and the topological charge promote significant changes in the angular deflection of light with respect to that one obtained in Schwarzschild spacetime. Using the expression for angular deflection in the strong field limit, we calculate the position and magnification of the respective relativistic images.

The idea that, after their evaporation, Planck-mass black holes might tunnel into metastable white holes has recently been intensively studied. Those relics have been considered as a dark matter candidate. We show that the model is severely constrained and underline some possible detection paths. We also investigate, in a more general setting, the way the initial black hole mass spectrum would be distorted by both the bouncing effect and the Hawking evaporation.

We present a new method, called $x$-cut cosmic shear, which optimally removes sensitivity to poorly modeled scales from the two-point cosmic shear signal. We show that the $x$-cut cosmic shear covariance matrix can be computed from the correlation function covariance matrix in a few minutes, enabling a likelihood analysis at virtually no additional computational cost. Further we show how to generalize $x$-cut cosmic shear to galaxy-galaxy lensing. Performing an $x$-cut cosmic shear analysis of the Dark Energy Survey Year 1 (DESY1) shear data, we reduce the error on $S_8={\sigma }_8({\mathrm{\Omega }}_m/0.3{)}^{0.5}$ by 32% relative to a correlation function analysis with the same priors and angular scale cut criterion, while showing our constraints are robust to different baryonic feedback models. Largely driven by information at small angular scales, our result, $S_8=0.734\pm 0.026$, yields a $2.6\sigma$ tension with the Planck Legacy analysis of the cosmic microwave background. As well as alleviating baryonic modeling uncertainties, our method can be used to optimally constrain a large number of theories of modified gravity where computational limitations make it infeasible to model the power spectrum down to extremely small scales.

We calculate the response of a lead-based detector, such as the Helium and Lead Observatory (HALO) or its planned upgrade HALO-1kt to a Galactic core-collapse supernova. We pay particular attention to the time dependence of the reaction rates. All reaction rates decrease as the neutrino luminosity exponentially drops during the cooling period, but the ratio of one-neutron (1n) to two-neutron (2n) event rates in HALO is independent of this overall decrease. Nevertheless, we find that this ratio still changes with time due to the changing character of neutrino flavor transformations with the evolving conditions in the supernova. In the case of inverted hierarchy, this is caused by the fact that the spectral splits become less and less sharp with the decreasing luminosity. In the case of normal hierarchy, it is caused by the passage of the shock wave through the Mikheyev-Smirnov-Wolfenstein resonance region. However, in both cases, we find that the change in the ratio of 1n to 2n event rates is limited to a few percent.

We study the radio signals generated when an axion star enters the magnetosphere of a neutron star. As the axion star moves through the resonant region where the plasma-induced photon mass becomes equal to the axion mass, the axions can efficiently convert into photons, giving rise to an intense, transient radio signal. We show that a dense axion star with a mass $\sim {10}^{-13}{M}_{\odot }$ composed of $\sim 10\mu \mathrm{eV}$ axions can account for most of the mysterious fast radio bursts.

We investigate a neural-network-based hypothesis test to distinguish different $W^{\prime }$ and charged scalar resonances through the $\ell +{\cancel{E}}_T$ channel at hadron colliders. This is traditionally challenging due to a fourfold ambiguity at proton-proton colliders, such as the Large Hadron Collider. Of the neural network approaches we study, we find a multiclass classifier based on a fully connected neural network trained upon two-dimensional histograms made from kinematic variables of the final state $\ell$ to be the most powerful. Furthermore, by considering the one-jet processes, we demonstrate that one can generalize to multiple two-dimensional histograms to represent different variable pairs. Finally, as a comparison to traditional approaches, we compare our method with Bayesian hypothesis testing and discuss the pros and cons of each approach. The neural network scheme presented in this paper is a powerful tool that can help probe the properties of charged resonances.

A scalar field having the Coleman-Weinberg type effective potential arises in various contexts of particle physics and serves as a useful framework for discussing cosmic inflation. According to recent studies based on the Markov chain Monte Carlo analysis, the coefficients of such an effective potential are severely constrained by the cosmological data. We investigate the impact of this observation on the physics beyond the Standard Model, focusing on an inflationary model based on the $U(1{)}_X$-extended Standard Model as a well-motivated example. We examine the parameter region that is not excluded by the Large Hadron Collider (LHC) run-2 at $139{\mathrm{fb}}^{-1}$ integrated luminosity, and show that the model parameters can be further constrained by the high-luminosity LHC experiments in the near future. We also comment on the possible reheating mechanism and the dark matter candidates of this scenario.

It has long been known that the sharpened tension between the observed and inferred values of the Hubble constant $H_0$ can be alleviated if a fraction of dark-matter particles of type $\chi$ were produced nonthermally in association with photons $\gamma$ through the decays of a heavy and relatively long-lived state, viz., $X\to \chi \gamma$. It was recently proposed that this model can also resolve the long-standing lithium (also known as ${}^7\mathrm{Li}$) problem if $M=4\mathrm{MeV}$ and $m=0.04\mathrm{keV}$, where $M$ and $m$ are, respectively, the masses of $X$ and $\chi$. We confront this proposal with experiment and demonstrate that cold dark matter decaying before recombination cannot resolve the $H_0$ problem. Moreover, we show that the best-case scenario for alleviating the $H_0$ tension within the context of cold dark matter decaying before recombination arises when the particles decay exclusively into dark radiation, while leaving completely unmodified the production of light elements. To this end, we calculate the general functional form describing the number of equivalent light neutrino species $\mathrm{\Delta }{N}_{\mathrm{eff}}$ carried by $\chi$. We show that to resolve the $H_0$ tension at the $1\sigma$ level, a 55% correction in $m$ is needed and that the required $\mathrm{\Delta }{N}_{\mathrm{eff}}$ is excluded at 95% C.L. by Planck data. We argue in favor of a more complex model of dynamical dark matter to relax the $H_0$ tension.

We perform a feasibility study of a beam dump experiment at the International Linear Collider (ILC). To investigate the sensitivity to new light particles at the experiment, we consider models for axion-like particles (ALPs) and a light scalar particle coupled to charged leptons. For both models, we show that the detection sensitivity is almost an order of magnitude higher than other beam dump experiments in the small coupling region. For ALPs, it is shown that the ILC beam dump experiment is highly complementary to bounds from astrophysics. In addition, for the model of the scalar particle, the region favored by the muon $g-2$ experiment can be explored.

We evaluate the contribution of the $CP$-violating gluon chromo-electric dipole moment (the so-called Weinberg operator, denoted as $w$) to the electric dipole moment (EDM) of nucleons in the nonrelativistic quark model. The $CP$-odd interquark potential is modeled by the perturbative one-loop level gluon exchange generated by the Weinberg operator with massive quarks and gluons. The nucleon EDM is obtained by solving the nonrelativistic Schrödinger equation of the three-quark system using the Gaussian expansion method. It is found that the resulting nucleon EDM, which may reasonably be considered as the irreducible contribution, is smaller than the one obtained after “${\gamma }_5$ rotating” the anomalous magnetic moment using the $CP$-odd mass calculated with QCD sum rules. We estimate the total contribution to be $d_n=w\times 20e\mathrm{MeV}$ and $d_p=-w\times 18e\mathrm{MeV}$ with 60% of theoretical uncertainty.

One of the great challenges of QCD is to determine the partonic structure of the nucleon from first principles. In this work, we provide such a determination of the flavor nonsinglet ($u-d$) unpolarized parton distribution function (PDF), utilizing the nonperturbative formulation of QCD on the lattice. We apply Radyushkin’s pseudodistribution approach to lattice results obtained using simulations with the light quark mass fixed to its physical value; this is the first ever attempt for this approach directly at the physical point. The extracted coordinate-space matrix elements are used to find the relevant physical Ioffe time distributions from a matching procedure. The full Bjorken-$x$ dependence of PDFs is resolved using several reconstruction methods to tackle the ill-conditioned inverse problem encountered when using discrete lattice data. We consider both the valence distribution $q_v$ and the combination with antiquarks $q_v+2\overline{q}$, related to, respectively, the real and imaginary part of extracted matrix elements. Good agreement is found with PDFs from global fits already within statistical uncertainties and it is further improved by quantifying several systematic effects. The results presented here are the first ever ab initio determinations of PDFs fully consistent with global fits in the whole $x$ range. Thus, they pave the way to investigating a wider class of partonic distributions, such as e.g., singlet PDFs and generalized parton distributions. Therefore, essential and yet missing first-principle insights can be achieved, complementing the rich experimental programs dedicated to the structure of the nucleon.

We study theoretically the resonant structure of the double Cabibbo suppressed $D^{+}\to K^{-}{K}^{+}{K}^{+}$ decay. We start from an elementary production diagram, considered subleading in previous approaches, which cannot produce a final $K^{-}{K}^{+}$ pair at the tree level but which we show to be able to provide the strength of the decay through final meson-meson state interaction. The different meson-meson elementary productions are related through SU(3), and the final rescattering is implemented from a suitable implementation of unitary extensions of chiral perturbation theory, which generate dynamically the scalar resonances $f_0(980)$ and $a_0(980)$. We obtain a good agreement with recent experimental data from the LHCb Collaboration with a minimal freedom in the fit and show the dominance of the $a_0(980)$ contribution close to the threshold of the $K^{-}{K}^{+}$ spectrum.

We study the decay of ${\mathrm{\Lambda }}_b\to J/\psi \mathrm{\Lambda }\varphi$ by taking into account the intermediate resonances $X(4140)$, $X(4160)$, and $P_{cs}(4459)$. In addition to the peak of the $X(4140)$, we also find a bump structure around 4160 MeV followed by a cusp structure around $D_s^{*}{\overline{D}}_s^{*}$ threshold in the $J/\psi \varphi$ invariant mass distribution of the ${\mathrm{\Lambda }}_b\to J/\psi \mathrm{\Lambda }\varphi$ process, which can be associated to the $D_s^{*}{\overline{D}}_s^{*}$ molecular state $X(4160)$. We also show that this reaction can also be used to confirm the existence of the hidden-charm pentaquark $P_{cs}(4459)$ with strangeness. We predict an enhancement structure close to the threshold in the $D_s^{*}{\overline{D}}_s^{*}$ invariant mass distribution of the ${\mathrm{\Lambda }}_b\to D_s^{*}{\overline{D}}_s^{*}\mathrm{\Lambda }$ process, which is the reflection of the $X(4160)$ and should not be misidentified with a new resonance. We strongly suggest experimentalists to further measure these processes, which can be useful to clarify the nature of $X(4140)$ and $X(4160)$ resonances, and to confirm the existence of the $P_{cs}(4459)$.

Within the framework of nonrelativistic QCD factorization formalism, we compute the helicity amplitude as well as the decay width of ${\eta }_{Q2}$ ($Q=c$, $b$) electromagnetic decay into two photons up to next-to-next-to-leading order in ${\alpha }_s$ expansion. For the first time, we verify the validity of nonrelativistic QCD factorization for the $D$-wave quarkonium decay at next-to-next-to-leading order. We find that the $\mathcal{O}({\alpha }_s)$ and $\mathcal{O}({\alpha }_s^2)$ corrections to the helicity amplitude are negative and moderate, nevertheless both corrections combine to suppress the leading-order prediction for the decay width significantly. By approximating the total decay width of ${\eta }_{Q2}$ as the sum of those for the hadronic decay and the electric $E1$ transition, we obtain the branching ratios $\text{Br}({\eta }_{c2}\to 2\gamma )\approx 5\times {10}^{-6}$ and $\text{Br}({\eta }_{b2}\to 2\gamma )\approx 4\times {10}^{-7}$. To explore the potential measurement on ${\eta }_{Q2}$, we further evaluate the production cross section of ${\eta }_{Q2}$ at LHCb at the lowest order in ${\alpha }_s$ expansion. With the kinematic constraint on the longitudinal rapidity $4.5>y>2$ and transverse momentum $P_T>(2–4)m_Q$ for ${\eta }_{Q2}$, we find the cross section can reach 2–50 nb for ${\eta }_{c2}$, and 1–22 pb for ${\eta }_{b2}$. Considering the integrated luminosity $\mathcal{L}=10{\mathrm{fb}}^{-1}$ at $\sqrt{s}=7$, 13 TeV, we estimate that there are several hundreds events of $pp\to {\eta }_{c2}\to 2\gamma$. Since the background is relatively clean, it is promising to reconstruct ${\eta }_{c2}$ through its electromagnetic decay. On the other hand, due to the small branching ratio and production cross section, it is quite challenging to detect ${\eta }_{b2}\to 2\gamma$ at LHCb.

This paper presents a study of the reconstruction and identification of $H\to W{W}^{*}$ with high transverse momentum, where both $W^{(*)}$ bosons decay hadronically. We show that the boosted $H\to W{W}^{*}$ can be effectively reconstructed as a single jet and identified using jet substructures in the center-of-mass frame of the jet. Such a reconstruction and identification approach can discriminate the boosted $H\to W{W}^{*}$ in the full hadronic final state from QCD jets. This result will significantly improve experimental sensitivities of searches for potential new physics phenomena beyond the standard model in final states containing highly boosted Higgs bosons.

We show that the current search for Lorentz invariance violation (LIV) in the summed energy spectra of electrons in $2\nu \beta \beta$ decay can be extended by investigating the single electron spectra and the angular correlation between the emitted electrons. We derive and calculate the LIV contributions to these spectra associated with the isotropic part of the countershaded operator and controlled through the coefficient ${\stackrel{\circ }{a}}_{\mathrm{of}}^{(3)}$ and discuss possible signatures that may be probed in experiments. First, we show that some distortion occurs in the single electron spectrum, maximal at small electron energies. Then, we show that other LIV effects may be highlighted by analyzing the angular correlation spectra and the ratio between the Standard Model extension electron spectra and their Standard Model forms. We found that these LIV signatures depend on the magnitude of ${\stackrel{\circ }{a}}_{\mathrm{of}}^{(3)}$, manifest differently for positive and negative values of this coefficient, and become more pronounced as the electron energy approaches the $Q$ value. Finally, we propose an alternative, new method to constrain ${\stackrel{\circ }{a}}_{\mathrm{of}}^{(3)}$ through the measurement of the angular correlation coefficient. Using this method, and considering only statistical uncertainties, we obtain bounds of ${\stackrel{\circ }{a}}_{\mathrm{of}}^{(3)}$ at the level of present ones, obtained from summed energy spectra. We show that future experiments can improve these limits significantly. Our study is performed for ${}^{100}\mathrm{Mo}$, but the results hold qualitatively for other nuclei that undergo a double-beta decay. We hope our results will provide additional motivation for the LIV analyses performed in DBD experiments.

Motivated by the recent discovery of two new states in the $B^{+}\to D^{+}{D}^{-}{K}^{+}$ decay by the LHCb Collaboration, we study the $D\overline{D}K$ three-body system by solving the Schrödinger equation with the Gaussian Expansion Method. We show that the $D\overline{D}K$ system can bind with quantum numbers $I(J^P)=\frac{1}{2}(0^{-})$ and a binding energy of $B_3(D\overline{D}K)={48.9}_{-2.4}^{+1.4}\mathrm{MeV}$. It can decay into $J/\psi K$ and $D_s{\overline{D}}^{*}$ via triangle diagrams, yielding a partial decay width of about 1 MeV. As a result, if discovered, it will serve as a highly nontrivial check on the nature of the many exotic hadrons discovered so far and on nonperturbative QCD as well. Assuming heavy quark spin symmetry, the same formalism is applied to study the $D{\overline{D}}^{*}K$ system, which is shown to also bind with quantum numbers $I(J^P)=\frac{1}{2}(1^{-})$ and a binding energy of $B_3(D{\overline{D}}^{*}K)\simeq {77.3}_{-6.6}^{+3.1}\mathrm{MeV}$, consistent with the results of previous works.

We study quantum field theories with sextic interactions in $3-\epsilon$ dimensions, where the scalar fields ${\varphi }^{ab}$ form irreducible representations under the $O(N{)}^2$ or $O(N)$ global symmetry group. We calculate the beta functions up to four-loop order and find the renormalization group (RG) fixed points. In an example of large $N$ equivalence, the parent $O(N{)}^2$ theory and its antisymmetric projection exhibit identical large $N$ beta functions that possess real fixed points. However, for projection to the symmetric traceless representation of $O(N)$, the large $N$ equivalence is violated by the appearance of an additional double-trace operator not inherited from the parent theory. Among the large $N$ fixed points of this daughter theory we find complex conformal field theories. The symmetric traceless $O(N)$ model also exhibits very interesting phenomena when it is analytically continued to small noninteger values of $N$. Here we find unconventional fixed points, which we call “spooky.” They are located at real values of the coupling constants $g^i$, but two eigenvalues of the Jacobian matrix $\partial {\beta }^i/\partial g^j$ are complex. When these complex conjugate eigenvalues cross the imaginary axis, a Hopf bifurcation occurs, giving rise to RG limit cycles. This crossing occurs for $N_{\text{crit}}\approx 4.475$, and for a small range of $N$ above this value we find RG flows that lead to limit cycles.

We bring to light a novel mechanism through which turbulent matter density fluctuations can induce collective neutrino flavor conversions in core-collapse supernovae, i.e., the leakage of flavor instabilities between different Fourier modes. The leakage mechanism leaves its notable fingerprint on the flavor stability of a dense neutrino gas by coupling flavor conversion modes on different scales which in turn, makes the flavor instabilities almost ubiquitous in the Fourier space. This intriguing phenomenon arises from the fact that unlike the case of collective neutrino oscillations in a homogenous medium, the neutrino flavor conversion modes depend linearly on each other at different supernova zones in a turbulent medium. The most remarkable consequence of this effect is in that it allows for the presence of significant flavor conversions in the deepest supernova regions even in the absence of the so-called fast modes. This is yet another crucial impact of turbulence on the physics of core-collapse supernovae which can profoundly change our understanding of neutrino flavor conversions in the supernova environment.

The Einstein-Maxwell dilaton-axion gravity arises in the low energy effective action of the heterotic string theory and provides a simple framework to explore the signatures of the same. The dilaton and the axion fields inherited in the action from string compactifications have interesting consequences in inflationary cosmology and in explaining the present accelerated expansion of the Universe. It is therefore worthwhile to search for the footprints of these fields in the available astrophysical observations. Since Einstein gravity is expected to receive quantum corrections in the high curvature domain, the near horizon regime of black holes seems to be the ideal astrophysical laboratory to test these deviations from general relativity. Exact, stationary and axisymmetric black hole solution in Einstein-Maxwell dilaton-axion gravity corresponds to the Kerr-Sen spacetime that carries dilaton charge, while the angular momentum is sourced by the axion field. The ballistic jets and the peak emission of the continuum spectrum from the accretion disk are believed to be launched very close to the event horizon and hence should bear the imprints of the background spacetime. We compute the jet power and the radiative efficiency derived from the continuum spectrum in the Kerr-Sen background and compare them with the corresponding observations of microquasars. Our analysis reveals that Kerr black holes are more favored compared to Kerr-Sen black holes with dilaton charges.