Decaying cold dark matter (CDM) has been considered as a mechanism to tackle the tensions in the Hubble expansion rate and the clustering of matter. However, polarization measurements of the cosmic microwave background (CMB) severely constrain the fraction of dark matter decaying before recombination, and lensing of the CMB anisotropies by large-scale structure sets strong constraints on dark matter decaying after recombination. Together, these constraints make an explanation of the Hubble tension in terms of decaying dark matter unlikely. In response to this situation, we investigate whether a dark matter ensemble with CDM particles decaying into free streaming dark radiation in different epochs can alleviate the problem. We find that it does not.

Minimal dark energy models, described by the same number of free parameters of the standard cosmological model with cold dark matter plus a cosmological constant to parametrize the dark energy component, constitute very appealing scenarios which may solve long-standing, pending tensions. On the one hand, they alleviate significantly the tension between cosmological observations and the presence of one sterile neutrino motivated by the short-baseline anomalies: we obtain a 95% CL cosmological bound on the mass of a fully thermalized fourth sterile neutrino ($N_{\mathrm{eff}}=4$) equal to $m_s<0.65(1.3)\mathrm{eV}$ within the Phenomenologically Emergent Dark Energy (PEDE) and Vacuum Metamorphosis (VM) scenarios under consideration. Interestingly, these limits are in agreement with the observations at short-baseline experiments, and the PEDE scenario is favored with respect to the $\mathrm{\Lambda }\mathrm{CDM}$ case when the full data combination is considered. On the other hand, the Hubble tension is satisfactorily solved in almost all the minimal dark energy schemes explored here. These phenomenological scenarios may therefore shed light on differences arising from near and far Universe probes, and also on discrepancies between cosmological and laboratory sterile neutrino searches.

We study the existence of charged fluid nonconducting structures orbiting in the background given by a Schwarzschild black hole immersed in a monopolelike magnetic field introduced in the context of the Blandford-Znajek process. Due to fact that the split-monopole magnetic field is not defined in the equatorial plane, where typical accretion disks are located, we focus on searching for off-equatorial charged toroidal structures. We demonstrate that charged nonconducting tori can arise very close to the symmetry axis of the magnetized black hole; thus representing a possible obstacle for jets created due to the Blanford-Znajek process.

We show that a dark Higgs field charged under ${\mathrm{U}(1)}_{\mathrm{H}}$ gauge symmetry is trapped at the origin for a long time, if dark photons are produced by an axion condensate via tachyonic preheating. The trapped dark Higgs can drive late-time inflation, producing a large amount of entropy. Unlike thermal inflation, the dark Higgs potential does not have to be very flat because the effective mass for the dark Higgs is enhanced by large field values of dark photons with extremely low momentum. After inflation, the dark Higgs decays into massive dark photons, which further decay into the SM particles through a kinetic mixing. We show that a large portion of the viable parameter space is within the future experimental searches for the dark photon because the kinetic mixing is bounded below for successful reheating. We also comment on the Schwinger effect, which can hamper the tachyonic production of dark photons, when the mass of the dark photon is not the Stückelberg mass but is generated by the Higgs mechanism. Such nonthermal trapped inflation could be applied to other cosmological scenarios such as the early dark energy, which is known as one of the solutions to the Hubble tension.

Electroweak (EW) triboson production processes with at least one heavy gauge boson are of increasing interest at the Large Hadron Collider (LHC) as direct precision probes of one of the least-tested sectors of the Standard Model (SM), the quartic couplings of the EW gauge bosons. These processes therefore offer promising opportunities for searches for indirect signals of beyond the SM physics. In this paper, we present results for fiducial cross sections at next-to-leading-order (NLO) EW and NLO QCD to $pp\to e^{+}{\nu }_e{\mu }^{+}{\mu }^{-}\gamma$ at the 13 TeV LHC. This signature includes the triboson production process $pp\to W^{+}Z\gamma$ with leptonic decays, $W^{+}\to e^{+}{\nu }_e$ and $Z\to {\mu }^{+}{\mu }^{-}$. The computation is based on the complete set of LO contributions of $\mathcal{O}({\alpha }^5)$ and on NLO EW and NLO QCD cross sections of $\mathcal{O}({\alpha }^6)$ and $\mathcal{O}({\alpha }^5{\alpha }_{\mathrm{s}})$, respectively, and thus off shell effects, spin correlations and nonresonance contributions are fully taken into account. We construct a Monte Carlo framework that provides total and differential cross sections for a chosen set of basic analysis cuts. We find that while NLO EW corrections enhance the fiducial LO total cross section by only 1%, they can significantly change some distributions in certain kinematic regions. For example, the relative NLO EW corrections to the muon transverse momentum distribution at 500 GeV amounts to $-20\%$. To illustrate how missing NLO EW corrections could masquerade as beyond the SM physics, we show examples for the impact of dimension-eight operators in the SM effective field theory framework on selected kinematic distributions.

In this work, we investigate the dark sector of a supersymmetric axion model, consisting of the late-decaying gravitino/axino dark matter and axion dark radiation. In the early Universe, the decay of the scalar superpartner of the axion (saxion) will produce a large amount of entropy. The additional entropy can not only dilute the relic density of the gravitino/axino dark matter to avoid overclosing the Universe but also relax the constraint on the reheating temperature $T_R$ after inflation. Meanwhile, the axion dark radiation from the saxion decay will increase the effective number of neutrino species $N_{\mathrm{eff}}$, which can help to reduce the cosmological Hubble tension. In the late Universe, the decay of long-lived gravitino/axino dark matter produces the axions with MeV-scale kinetic energy. We study the potential of searching for such energetic axions through the inverse Primakoff process $a+A\to \gamma +A$ in the neutrino experiments, such as Hyper-Kamiokande.

We demonstrate that ultralight axion dark matter with a coupling to photons induces an oscillating global terrestrial magnetic-field signal in the presence of the background geomagnetic field of the Earth. This signal is similar in structure to that of dark-photon dark matter that was recently pointed out and searched for in [Fedderke et al. Phys. Rev. D 104, 075023 (2021)] and [Fedderke et al. Phys. Rev. D 104, 095032 (2021)]. It has a global vectorial pattern fixed by the Earth’s geomagnetic field, is temporally coherent on long timescales, and has a frequency set by the axion mass $m_a$. In this work, we both compute the detailed signal pattern and undertake a search for this signal in magnetometer network data maintained by the SuperMAG Collaboration. Our analysis identifies no strong evidence for an axion dark-matter signal in the axion mass range $2\times {10}^{-18}\mathrm{eV}\lesssim m_a\lesssim 7\times {10}^{-17}\mathrm{eV}$. Assuming the axion is all of the dark matter, we place constraints on the axion-photon coupling $g_{a\gamma }$ in the same mass range; at their strongest, for masses $3\times {10}^{-17}\mathrm{eV}\lesssim m_a\lesssim 4\times {10}^{-17}\mathrm{eV}$, these constraints are comparable to those obtained by the CAST helioscope.

Heavy neutral leptons ($N$) below the kaon mass are severely constrained by cosmology and lab-based searches for their decays in flight. If $N$ interacts via an additional force, $N\to \nu e^{+}{e}^{-}$ decays are enhanced and cosmological limits can be avoided. We show that the T2K and MicroBooNE neutrino experiments provide the best limits on the mixing of $N$ with muon neutrinos, outperforming past-generation experiments, previously thought to dominate. We constrain models with electromagnetically decaying and long-lived $N$, such as in a transition-magnetic-moment portal and in a leptophilic axionlike particle portal, invoked to explain the MiniBooNE excess. By considering these models as representative examples, our results show that explanations of the MiniBooNE excess that involve $e^{+}{e}^{-}$ pairs from long-lived particles are in tension with T2K, PS191, and MicroBooNE data. Similarly, these searches also constrain MiniBooNE explanations based on single photons due to the associated $e^{+}{e}^{-}$ decay mode via a virtual photon.

Although the Hamiltonian formalism is, so far, favored for quantum computation of lattice gauge theory, the path integral formalism would never be useless. The advantages of the path integral formalism are the knowledge and experience accumulated by classical lattice simulation and manifest Lorentz invariance. In this article, we will discuss quantum computation of lattice gauge theory in the path integral formalism, utilize a quantum sampling algorithm to generate gauge configurations, and demonstrate a benchmark test of $Z_2$ lattice gauge theory on a four-dimensional hypercube.

This paper reports constraints on Higgs boson production with transverse momentum above 1 TeV. The analyzed data from proton–proton collisions at a center-of-mass energy of 13 TeV were recorded with the ATLAS detector at the Large Hadron Collider from 2015 to 2018 and correspond to an integrated luminosity of $136{\mathrm{fb}}^{-1}$. Higgs bosons decaying into $b\overline{b}$ are reconstructed as single large-radius jets recoiling against a hadronic system and are identified by the experimental signature of two $b$-hadron decays. The experimental techniques are validated in the same kinematic regime using the $Z\to b\overline{b}$ process. The 95% confidence-level upper limit on the cross section for Higgs boson production with transverse momentum above 450 GeV is 115 fb, and above 1 TeV it is 9.6 fb. The Standard Model cross section predictions for a Higgs boson with a mass of 125 GeV in the same kinematic regions are 18.4 fb and 0.13 fb, respectively.

A search for resonant Higgs boson pair production in the $b\overline{b}b\overline{b}$ final state is presented. The analysis uses $126{\mathrm{fb}}^{-1}–139{\mathrm{fb}}^{-1}$ of $pp$ collision data at $\sqrt{s}=13\mathrm{TeV}$ collected with the ATLAS detector at the Large Hadron Collider. The analysis is divided into two channels, targeting Higgs boson decays which are reconstructed as pairs of small-radius jets or as individual large-radius jets. Spin-0 and spin-2 benchmark signal models are considered, both of which correspond to resonant $HH$ production via gluon-gluon fusion. The data are consistent with Standard Model predictions. Upper limits are set on the production cross section times branching ratio to Higgs boson pairs of a new resonance in the mass range from $251\mathrm{GeV}$ to $5\mathrm{TeV}$.

In our previous paper, we have presented a covariant BRST quantization of unimodular gravity which may account for the smallness of the cosmological constant, and we have shown that the physical degrees of freedom in the theory are the same as general relativity. The formulation has been given by using rank-2 antisymmetric tensor fields for both ghosts and antighosts. Here we give an alternative formulation using a vector field for the antighost but keeping the same structure for the ghosts. This gives a significantly simpler covariant quantization with less ghosts and no tripole modes in the ghost sector. We show that this also gives only two physical transverse modes as in general relativity.

Based on the assumption that quasars (QSOs) and gamma-ray bursts (GRBs) represent standardizable candles, we provide evidence that the Hubble constant $H_0$ adopts larger values in hemispheres aligned with the cosmic microwave background (CMB) dipole direction. If substantiated, this trend signals a departure from Friedmann-Lemaître-Robertson-Walker cosmology. In particular, QSOs show a definite trend, whereas our findings in GRBs are consistent with an isotropic universe, but we show in a sample of GRBs calibrated with type Ia supernovae (SNe) that this conclusion may change as one focuses on GRBs more closely (mis)aligned with the CMB dipole direction. The statistical significance in QSOs alone is $\gtrsim 2\sigma$, and when combined with similar trends in strong lensing, type Ia SNe, and calibrated GRBs, this increases to $\sim 3\sigma$. Our findings are consistent with reported discrepancies in the cosmic dipole and anisotropies in galaxy cluster scaling relations. The reported variations in $H_0$ across the sky suggest that Hubble tension may be a symptom of a deeper cosmological malaise.

In this work, we explore the phenomenology of generalized dark matter (GDM) which interacts with photons ($\gamma$). We assume that DM establishes elastic scattering with $\gamma$ when it has already become nonrelativistic, otherwise the abundance of DM today is disfavored by current observations. Within this scenario, the equation of state (EoS) of DM is determined by its mass ($m_{\chi }$) and the DM-$\gamma$ scattering cross section. The distinctive imprints of a nonzero EoS of DM on CMB angular power spectrum allow us to set a lower limit on $m_{\chi }$ with Planck 2018 data alone, i.e., $m_{\chi }>8.7\mathrm{keV}$ at 95% C.L. In the study of cosmic concordance problems, we find that the GDM scenario preserves the sound horizon ($r_s(z_{*})$) predicted in the fiducial $\mathrm{\Lambda }\mathrm{CDM}$ model, and thus does not solve the $H_0$ tension. When performing the joint analysis of $Planck+\mathrm{LSS}$ datasets, the best-fit $S_8=0.785\pm 0.017$ closely matches the given $S_8$ prior. This suggests that the GDM scenario can be counted as a viable candidate to restore the $S_8$ (${\sigma }_8$) tension.

Theories of large extra dimensions (LEDs) such as the Arkani-Hamed, Dimopoulos and Dvali scenario predict a “true” Planck scale $M_{\star }$ near the TeV scale, while the observed $M_{pl}$ is due to the geometric effect of compact extra dimensions. These theories allow for the creation of primordial black holes (PBHs) in the early Universe, from the collisional formation and subsequent accretion of black holes in the high-temperature plasma, leading to a novel cold dark matter (sub)component. Because of their existence in a higher-dimensional space, the usual relationship between mass, radius, and temperature is modified, leading to distinct behavior with respect to their four-dimensional counterparts. Here, we derive the cosmological creation and evolution of such PBH candidates, including the graybody factors describing their evaporation, and obtain limits on LED PBHs from direct observation of evaporation products, effects on big bang nucleosynthesis, and the cosmic microwave background angular power spectrum. Our limits cover scenarios of two to six extra dimensions, and PBH masses ranging from 10 to ${10}^{21}\mathrm{g}$. We find that for two extra dimensions, LED PBHs represent a viable dark matter candidate with a range of possible black hole masses between ${10}^{17}$ and ${10}^{23}\mathrm{g}$ depending on the Planck scale and reheating temperature. For $M_{\star }=10\mathrm{TeV}$, this corresponds to PBH dark matter with a mass of $M\simeq {10}^{21}\mathrm{g}$, unconstrained by current observations. We further refine and update constraints on “ordinary” four-dimensional black holes.

Four next-to-tribimaximal (NTBM) mixing patterns are widely considered as the feasible candidates for the observed leptonic mixing structure. With the recent measurements from T2K, as well as intensive global fits, the interval of $\sin {\delta }_{CP}>0$ for the Dirac $CP$-violating phase is persistently small in the normal ordering while $\sin {\delta }_{CP}<0$ is successively obtained up to $3\sigma$ level in the inverted ordering. In this paper, we advocate the fitting results of Dirac $CP$-violating phase as a constraint, and show that it can basically rule out half of the regions allowed by the constraint from three mixing angles only. In addition, given the small $\sin {\delta }_{CP}>0$ interval, we find that a unique NTBM pattern can be selected out of the four candidates within $3\sigma$ uncertainty of the latest nufit5.1, when the patterns are exposed to a Yukawa texture-independent leptogenesis for the baryon asymmetry of the Universe. For the surviving pattern, we find an interesting correlation between the Dirac $CP$-violating phase and the octant of atmospheric angle ${\theta }_{23}$, where ${\theta }_{23}>45°$ can be predicted once $5\pi /6<{\delta }_{CP}<\pi$ in the normal ordering can be confirmed in the future measurements.

It has recently been shown that a subdominant hidden sector of atomic dark matter in the early Universe provides a novel avenue toward resolving the Hubble ($H_0$) tension while maintaining good agreement with cosmic microwave background era observables. However, such a mechanism requires a hidden sector whose energy density ratios are the same as in our sector and whose recombination also takes place at redshift $z\approx 1100$, which presents an apparent fine-tuning. We introduce a realistic model of this scenario that dynamically enforces these coincidences without fine tuning. In our setup, the hidden sector contains an identical copy of Standard Model (SM) fields but has a smaller Higgs vacuum expectation value (VEV) and a lower temperature. The baryon asymmetries and reheating temperatures in both sectors arise from the decays of an Affleck-Dine scalar field, whose branching ratios automatically ensure that the reheating temperature in each sector is proportional to the corresponding Higgs VEV. The same setup also naturally ensures that the hydrogen binding energy in each sector is proportional to the corresponding VEV, so the ratios of binding energy to temperature are approximately equal in the two sectors. Furthermore, our scenario predicts a correlation between the SM/hidden temperature ratio and the atomic dark matter abundance and automatically yields values for these quantities favored by concordant early- and late-Universe measurements of $H_0$.

In this article we study the unquenched three-gluon and ghost-gluon vertex in the entire momentum range from the ultraviolet to infrared regime using the Curci-Ferrari model at one loop in Landau gauge, as an extension of the results presented in by Pelaez et al. [Phys. Rev. D 88, 125003 (2013)]. Results are compared with recent lattice data for SU(3) in the unquenched case. This calculation is a pure prediction of the model because it does not require fixing any parameter once two-point functions are fitted. An analysis of the influence of dynamical quarks at the position of the zero crossing of the three-gluon vertex is presented. Due to the recent improvements in infrared lattice data for the quenched three-gluon correlation function [Phys. Lett. B 818, 136352 (2021)], we also redo the comparison between our one-loop results in this limit and the lattice results, obtaining a very good match.