Recently, a generalization of invertible disformal transformations containing higher-order derivatives of a scalar field has been proposed in the context of scalar-tensor theories of gravity. By applying this generalized disformal transformation to the Horndeski theory, one can obtain the so-called generalized disformal Horndeski (GDH) theories which are more general healthy scalar-tensor theories than ever. However, it is unclear whether or not the GDH theories can be coupled consistently to matter fields because introducing matter fields could break the degeneracy conditions of higher-order scalar-tensor theories and hence yield the unwanted Ostrogradsky ghost. We investigate this issue and explore the conditions under which a minimal coupling to a matter field is consistent in the GDH theories without relying on any particular gauge such as the unitary gauge. We find that all the higher-derivative terms in the generalized disformal transformation are prohibited to avoid the appearance of an extra degree of freedom in a generic gauge. Our analysis shows that, if one considers matter-coupled GDH theories, an extra degree of freedom shows up, though it might be a harmless nonpropagating mode when the scalar field has a timelike gradient.

It is well known that parity symmetry is broken in the weak interaction but conserved for Einstein’s general relativity and Maxwell’s electromagnetic theory. Nevertheless, parity symmetry could also be violated in the gravitational/electromagnetic sectors if a fundamental scalar field couples to the parity-violating gravitational/electromagnetic curvature terms. Such parity-violating terms, which flip signs under reversed spatial directions, can inevitably lead to a negative effective mass squared for the scalar field perturbations near nonspherically symmetric black holes and thus are expected to trigger tachyonic instability. As illustrative examples, we show that the scalar field coupled to gravitational/electromagnetic Chern-Simons terms near a Kerr-Newmann spacetime can develop tachyonic instabilities, leading to equilibrium scalar field configurations in certain parameter regions of black holes. This instability, which is an indication of the black hole scalarization process, can occur in a broad class of nonspherically symmetric black holes and parity-violating theories.

We introduce an action-angle formalism for bounded geodesic motion in Kerr black hole spacetime using canonical perturbation theory. Namely, we employ a Lie series technique to produce a series of canonical transformations on a Hamiltonian function describing geodesic motion in Kerr background written in Boyer-Lindquist coordinates to a Hamiltonian system written in action-angle variables. This technique allows us to produce a closed-form invertible relation between the Boyer-Lindquist variables and the action-angle ones, while it generates in analytical closed form all the characteristic functions of the system as well. The expressed in the action-angle variable Hamiltonian system is employed to model an extreme mass ratio inspiral (EMRI), i.e., a binary system where a stellar compact object inspirals into a supermassive black hole due to gravitational radiation reaction. We consider the adiabatic evolution of an EMRI, for which the energy and angular momentum fluxes are computed by solving the Teukolsky equation in the frequency domain. To achieve this a new Teukolsky equation solver code was developed.

Singularity-free regular black holes are a popular alternative to the singular mathematical black holes predicted by general relativity. Here, we derive a generic condition that spherically symmetric dynamical regular black holes must satisfy to be compatible with the first law of black hole mechanics based on an expression for the surface gravity at the outer horizon. We examine the dynamical generalizations of models typically considered in the literature and demonstrate that none of them satisfies the condition required for compatibility with the first law, suggesting that modifications are required to maintain its physical meaning. We show that the need for corrections is inherently linked to the introduction of a minimal length scale and can therefore be seen as a direct consequence of the spacetime regularization. We explicitly identify the additional work terms in the extended first law, comment on their thermodynamic interpretation, and show that the linear coefficient of the Misner-Sharp mass suffices to determine the relevant thermodynamic properties.

We discuss the wormholes in general dimensions by studying the Einstein-phantom scalar field with and without the cosmological constant. Solving anti–de Sitter (AdS) wormholes in general dimensions is hard due to the nonlinear nature of the theory. In this work, we implement the AdS/Ricci-flat correspondence, extended to include the axion field (the phantom scalar field), to construct AdS wormholes. Wormholes of the Ellis-Bronnikov class are discussed in general dimensions.

Stochastic inflation resolves primordial perturbations nonlinearly, probing their probability distribution deep into its non-Gaussian tail. The strongest perturbations collapse into primordial black holes. In typical black-hole-producing single-field inflation, the strongest stochastic kicks occur during a period of constant roll. In this paper, I solve the stochastic constant-roll system, drawing the stochastic kicks from a numerically computed power spectrum, beyond the usual de Sitter approximation. The perturbation probability distribution is an analytical function of the integrated curvature power spectrum ${\sigma }_k^2$ and the second slow-roll parameter ${\epsilon }_2$. With a large ${\epsilon }_2$, stochastic effects can reduce the height of the curvature power spectrum required to form asteroid mass black holes from ${10}^{-2}$ to ${10}^{-3}$. I compare these results to studies with the nonstochastic $\mathrm{\Delta }N$ formalism.

We investigate the impact of stochastic quantum noise due to trans-Planckian effects on the primordial power spectrum for gravity waves during inflation. Given an energy scale $\mathrm{\Lambda }$, expected to be close to the Planck scale $m_{\mathrm{Pl}}$ and larger than the Hubble scale $H$, this noise is described in terms of a source term in the evolution equation for comoving modes $k$ which changes its amplitude growth from early times as long as the mode physical wavelength is smaller than ${\mathrm{\Lambda }}^{-1}$. We model the source term as due to a gas of black holes in the trans-Planckian regime and the corresponding Hawking radiation. In fact, for energy scales larger than, or of the order of $\mathrm{\Lambda }$, it is expected that trapped surfaces may form due to large energy densities. At later times the evolution then follows the standard sourceless evolution. We find that this mechanism still leads to a scale-invariant power spectrum of tensor perturbations, and in agreement with CMB data for $\mathrm{\Lambda }/m_{\mathrm{Pl}}\sim {10}^{-2}$.

The vector portal/kinetic mixing simplified model of dark matter, in which thermal dark matter of a mass ranging from a few MeV to a few GeV can be realized with a dark sector $U(1)$, relies on a small kinetic mixing term between this dark $U(1)$ and the Standard Model (SM) hypercharge. It is well known that kinetic mixing of the right magnitude can be generated at one loop by the inclusion of “portal matter” fields which are charged under both the dark $U(1)$ and the SM hypercharge, and it has been previously argued on phenomenological grounds that fermionic portal matter fields must exhibit a specific set of characteristics: They must be vector-like and have the same Standard Model group representations as existing SM fermions. A natural explanation for the presence of dark $U(1)$ charged copies of SM fermions would be to enlarge the dark gauge group and embed the SM and the portal matter into a single dark multiplet; however, previous works in this direction require significant ad hoc additions to ensure that the portal matter fields are vector-like while the SM fields are chiral, and they rely on complicated dark Higgs sectors to realize the appropriate symmetry breaking. In this paper, we argue that a model with large extra dimensions can easily generate chiral SM fermions and vector-like portal matter from a single dark bulk multiplet, while allowing for a far simpler dark Higgs sector. We present a minimal construction of this “Kaluza-Klein (KK) portal matter” and explore its phenomenology at the LHC, noting that even our simple realization exhibits signatures unique from those of more conventional models with large extra dimensions and 4D portal matter. Generically, the portal matter sector fields will be much lighter than the other KK fields in the model, so the portal matter sector has the potential to be the first observable experimental signature of an extra dimension.

The recent measurement of the $CP$ asymmetry in the decay $D\to K^{+}{K}^{-}$ by LHCb, combined with $\mathrm{\Delta }{A}_{CP}$, evidences a sizable $CP$ asymmetry in the decay $D\to {\pi }^{+}{\pi }^{-}$, which requires a dynamical enhancement of standard model higher-order contributions over tree-level ones by a factor of 2. The data furthermore imply huge $U$-spin breaking, about 4–5 times larger than the nominal standard model one of $\lesssim 30\%$ in charm. Enhanced breakdown of the two approximate symmetries points to models that violate $U$-spin and $CP$ and disfavors flavor singlet contributions such as chromomagnetic dipole operators as explanations of the data. We analyze the reach of flavorful $Z^{\prime }$ models for charm $CP$ asymmetries. Models generically feature explicit $U$-spin and isospin breaking, allowing for correlations with $D\to {\pi }^0{\pi }^0$ and $D^{+}\to {\pi }^{+}{\pi }^0$ decays with corresponding $CP$ asymmetries at similar level and sign as $D\to {\pi }^{+}{\pi }^{-}$, about $\mathcal{O}(1-2)\times {10}^{-3}$. Experimental and theoretical constraints very much narrow down the shape of viable models: Viable, anomaly-free models are leptophobic—or at least electron- and muophobic—with light $Z^{\prime }$ below $\mathcal{O}(20)\mathrm{GeV}$ and can be searched for in low mass dijets at the LHC or in $\mathrm{\Upsilon }$ and charmonium decays, as well as dark photon searches. A $Z^{\prime }$ around $\sim 3$ or $\sim (5–7)\mathrm{GeV}$ can relieve the tensions in the $J/\psi \to {\pi }^{+}{\pi }^{-}$ and ${\psi }^{\prime }\to {\pi }^{+}{\pi }^{-}$ branching ratios with pion form factor values from fits to BABAR and JLab data and simultaneously explain the charm $CP$ asymmetries. Models can also feature sizable branching ratios into light right-handed neutrinos or vectorlike dark fermions, which can be searched for in $e^{+}{e}^{-}\to \mathrm{hadrons}+\mathrm{invisibles}$ at Belle II and BESIII. Because of the low new physics scale, dark fermions can easily induce an early Landau pole, requiring models to be UV completed near the TeV scale.

The Earth-stopping effect plays a crucial role in the direct detection of sub-GeV dark matter. Besides the elastic scattering process, the quasielastic and deep inelastic scatterings between dark matter and nucleus that are usually neglected can dominate the interaction, especially in the accelerated dark matter scenarios, which may affect the dark matter detection sensitivity significantly for the underground experiments. We calculate such inelastic scattering contributions in the Earth-stopping effect and illustrate the essence of our argument with the atmospheric dark matter. With the available data, we find that the resulting upper limits on the atmospheric dark matter-nucleus scattering cross section can differ from those only considering the elastic scattering process by about 1 order of magnitude.

We study the potential of the future Higgs factories, including the ILC, CEPC, and FCC-ee with $\sqrt{s}=240–250\mathrm{GeV}$ on discovering axionlike particles (ALPs) through various production channels in the leptonic final states, $e^{+}{e}^{-}\to f\overline{f}a$, where $f=e$, $\mu$, $\nu$. We show that the $e^{+}{e}^{-}\to e^{+}{e}^{-}a$ with $a\to \gamma \gamma$ provides the best bounds for the $g_{a\gamma \gamma }$ and $g_{aZZ}$ couplings, while $e^{+}{e}^{-}\to \nu \overline{\nu }a$, with $a\to \gamma \gamma$ offers the best bounds for the $g_{aZZ}$ and $g_{aZ\gamma }$ couplings. The $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}a$ with $a\to \gamma \gamma$ provides intermediate sensitivity to the $g_{aZZ}$ coupling. Our estimates of the bounds for the $g_{a\gamma \gamma }$, $g_{aZ\gamma }$, and $g_{aZZ}$ couplings as a function of ALP mass ($M_a$) ranging from 0.1 to 100 GeV provide valuable insights for future experiments aiming to detect ALPs. We find that $g_{a\gamma \gamma }$ around $1.5\times {10}^{-4}{\mathrm{GeV}}^{-1}$ for $M_a=0.1–6\mathrm{GeV}$ is currently not ruled out by any other experiments.

In the collider phenomenology of extensions of the Standard Model with partner particles, cascade decays occur generically, and they can be challenging to discover when the spectrum of new particles is compressed and the signal cross section is low. Achieving discovery-level significance and measuring the properties of the new particles appearing as intermediate states in the cascade decays is a long-standing problem, with analysis techniques for some decay topologies already optimized. We focus our attention on a benchmark decay topology with four final state particles where there is room for improvement and where multidimensional analysis techniques have been shown to be effective in the past. We apply machine learning techniques in order to identify effective human-level kinematic observables for discovery, spin determination, and mass measurement. We quantify the performance of these analyses as a function of the signal size. In agreement with past work, we confirm that the kinematic observable ${\mathrm{\Delta }}_4$ is highly effective.

Many scenarios of beyond the Standard Model (BSM) physics give rise to new top-philic interactions that can be probed at proton machines such as the Large Hadron Collider through a variety of production and decay modes. On the one hand, this will enable a detailed determination of the BSM model’s parameters when a discovery is made and additional sensitivity in nondominant production modes can be achieved. On the other hand, the naive narrow width approximation in dominant production modes such as gluon fusion might be inadequate for some BSM parameter regions due to interference effects, effectively making less dominant production modes more relevant in such instances. In this work, we consider both these questions in the context of four top quark final states at the LHC. First, we show that the SM potential can be enhanced through the application of targeted graph neural network techniques that exploit data correlations beyond cut-and-count approaches. Second, we show that destructive interference effects that can degrade BSM sensitivity of top-philic states from gluon fusion are largely avoided by turning to four top final states. This achieves considerable exclusion potential, e.g., the two Higgs doublet model. This further motivates four top final states as sensitive tools for BSM discovery in the near future of the LHC.

In this work, we investigate the spectroscopic properties of $1F$-wave charmed baryons, which have not yet been observed in experiments. We employ a nonrelativistic potential model and utilize the Gaussian expansion method to obtain the mass spectra of these charmed baryons. Additionally, we focus on the two-body Okubo-Zweig-Iizuka allowed strong decay behaviors, which plays a crucial role in characterizing the properties of these baryons. Our analyses of the mass spectra and two-body Okubo-Zweig-Iizuka allowed decay behaviors provides valuable insights for future experimental investigations. This study contributes to our understandings of the spectroscopic properties of $1F$-wave charmed baryons.

We calculated next-to-leading-order (NLO) QCD perturbative contributions to a $J^{PC}=0^{+-}$, $du\overline{d}\overline{u}$ tetraquark (diquark-antidiquark) correlator in the chiral limit of massless $u$ and $d$ quarks. At NLO, there are four quark self-energy diagrams and six gluon-exchange diagrams. Nonlocal divergences were canceled using diagrammatic renormalization. Dimensionally regularized integrals were numerically computed using pySecDec. The combination of pySecDec with diagrammatic renormalization establishes a valuable new methodology for NLO calculations of QCD correlation functions. Compared to leading-order (LO) perturbation theory, we found that NLO perturbation theory is significant. To quantify the impact of NLO perturbation theory on physical predictions, we computed NLO perturbative contributions to QCD Laplace, Gaussian, and finite-energy sum rules. Using QCD sum rules, we determined upper and lower bounds on the $0^{+-}$, $du\overline{d}\overline{u}$ tetraquark ground-state mass, $M$; at NLO in perturbation theory, we found $2.2\mathrm{GeV}\lesssim M\le 4.2\mathrm{GeV}$ whereas, at LO, we found $2.4\mathrm{GeV}\lesssim M\le 4.6\mathrm{GeV}$. This mass range suggests the possibility of mixing between $0^{+-}$, light-quark (i.e., $u$ and $d$ quarks) hybrid and $du\overline{d}\overline{u}$ tetraquark states. Taking into account uncertainties in QCD parameters, we found no evidence for a $0^{+-}$, $du\overline{d}\overline{u}$ tetraquark under 1.9 GeV.

Generation of ultrarelativistic polarized leptons during interaction of an ultrarelativistic electron beam with a counterpropagating ultraintense laser pulse is investigated in the quantum radiation-dominated domain. While the symmetry of the laser field tends to average the radiative polarization of leptons to zero, we demonstrate the feasibility of sizable radiative polarization through breaking the symmetry of the process in the reflection regime. After the reflection, the off-axis particles escape the tightly focused beam with polarization correlated to the emission angle, while the particles at the beam center are more likely to be captured in the laser field with unmatched polarization and kinetic motion. Meanwhile, polarization along the electric field emerges due to the spin rotation in the transverse plane via precession. In this way, the combined effects of radiative polarization, spin precession, and the laser field focusing are shaping the angle-dependent polarization for outgoing leptons. Our spin-resolved Monte Carlo simulations demonstrate an angle-dependent polarization degree up to $\sim 20\%$ for both electrons and positrons, with a yield of one pair per seed electron. It provides a new approach for producing polarized high density electron and positron jets at ultraintense laser facilities.

Using an $e^{+}{e}^{-}$ collision data sample with a total integrated luminosity of $3.19{\mathrm{fb}}^{-1}$ collected with the BESIII detector at a center-of-mass energy of 4.178 GeV, the branching fraction of the inclusive decay of the $D_s^{+}$ meson to final states including at least three charged pions is measured for the first time to be $\mathcal{B}(D_s^{+}\to {\pi }^{+}{\pi }^{+}{\pi }^{-}X)=(32.81\pm 0.35_{\mathrm{stat}}\pm 0.63_{\mathrm{syst}})\%$. In this measurement the charged pions from $K_S^0$ meson decays are excluded. The partial branching fractions of $D_s^{+}\to {\pi }^{+}{\pi }^{+}{\pi }^{-}X$ are also measured as a function of the ${\pi }^{+}{\pi }^{+}{\pi }^{-}$ invariant mass.

We make an ansatz for the Mellin representation of the four-point amplitude of half-BPS operators of arbitrary charges at order ${\lambda }^{-\frac{5}{2}}$ in an expansion around the supergravity limit. Crossing symmetry and a set of constraints on the form of the spectrum uniquely fix the amplitude and double-trace anomalous dimensions at this order. The results exhibit a number of natural patterns which suggest that the bootstrap approach outlined here will extend to higher orders in a simple way.

Quantum gravity phenomenology suggests the interesting possibility that black holes are not eternal. Collapse could be halted by some unknown mechanism, or Hawking radiation might leave behind a regular spacetime. Here we investigate a simple bouncing geometry, with (outer and inner) apparent horizons but no event horizon. We show that the inner horizon blueshifts radiation, which can lead to a gigantic amplification of energy observable from far away regions. Thus, if such phenomena exist in our Universe, then they can power high-energy bursts at late stages in their lives, when the horizons disappear and spacetime bounces back to a flat geometry.