Using data taken at 23 center-of-mass energies between 4.0 and 4.6 GeV with the BESIII detector at the Beijing Electron Positron Collider and with a total integrated luminosity of approximately $15{\mathrm{fb}}^{-1}$, the process $e^{+}{e}^{-}\to 2(p\overline{p})$ is studied for the first time. The Born cross sections for $e^{+}{e}^{-}\to 2(p\overline{p})$ are measured, and no significant structure is observed in the lineshape. The baryon pair ($pp$ and $\overline{p}\overline{p}$) invariant mass spectra are consistent with phase space, therefore no hexaquark or di-baryon state is found.

Nonlinear terms in the equations of motion can induce secularly growing loop corrections to correlation functions. Recently such corrections were shown to affect the particle production by a nonuniformly moving ideal mirror. We extend this conclusion to the cases of ideal vibrating cavity and single semitransparent mirror. These models provide natural IR and UV scales and allow a more accurate study of the loop behavior. In both cases we confirm that two-loop correction to the Keldysh propagator quadratically grows with time. This growth indicates a breakdown of the semiclassical approximation and emphasizes that bulk nonlinearities in the dynamical Casimir effect cannot be neglected for large evolution times.

The classical Eisenhart lift is a method by which the dynamics of a classical system subject to a potential can be recreated by means of a free system evolving in a higher-dimensional curved manifold, known as the lifted manifold. We extend the formulation of the Eisenhart lift to quantum systems, and show that the lifted manifold recreates not only the classical effects of the potential but also its quantum mechanical effects. In particular, we find that the solutions of the Schrödinger equations of the lifted system reduce to those of the original system after projecting out the new degrees of freedom. In this context, we identify a conserved quantum number, which corresponds to the lifted momentum of the classical system. We further apply the Eisenhart lift to quantum field theory (QFT). We show that a lifted field space manifold is able to recreate both the classical and quantum effects of a scalar field potential. We find that, in the case of QFT, the analog of the lifted momentum is a quantum charge that is conserved not only in time but also in space. The different possible values for this charge label an ensemble of Fock spaces that are all disjoint from one another. The relevance of these extended Fock spaces to the cosmological constant and gauge hierarchy problems is considered.

We revisit the “sequester” proposal of Kaloper, Padilla and collaborators, in which the amplitude of the cosmological constant is decoupled from large contributions due to loops containing Standard Model particles. We review the different formulations of the model that have appeared in the literature, and estimate the importance of a particular class of quantum corrections—those that dress the interaction between the “rigid” scalars and infrared properties of the spacetime such as its 4-volume and integrated curvature. In formulations that do not adequately sequester graviton loops we argue that dressing of these interactions causes further failures of complete sequestration. We estimate the size of the effect and find that it is typically smaller than the cosmological term directly induced by loops containing a single virtual graviton. Meanwhile, in the most developed formulation of the scenario (where a rigid scalar couples to the Gauss–Bonnet density), this dressing can be absorbed into a rescaling of the rigid fields and is therefore harmless.

Strong gravitational lensing along with the distance sum rule method can constrain both cosmological parameters as well as density profiles of galaxies without assuming any fiducial cosmological model. To constrain galaxy parameters and cosmic curvature $({\mathrm{\Omega }}_{k0})$, we use the distance ratio data from a recently compiled database of 161 galactic scale strong lensing systems. We use databases of supernovae type-Ia (Pantheon) and gamma ray bursts (GRBs) for calculating the luminosity distance. To study the model of the lens galaxy, we consider a general lens model namely, the extended power-law model. Further, we take into account two different parametrizations of the mass density power-law index ($\gamma$) to study the dependence of $\gamma$ on redshift. The best value of ${\mathrm{\Omega }}_{k0}$ suggests a closed universe, though a flat universe is accommodated at 68% confidence level. We find that parametrizations of $\gamma$ have a negligible impact on the best fit value of the cosmic curvature parameter. Furthermore, measurement of time delay can be a promising cosmographic probe via the “time delay distance” that includes the ratio of distances between the observer, the lens and the source. We again use the distance sum rule method with time-delay distance dataset of H0LiCOW to put constraints on the cosmic distance duality relation (CDDR) and the cosmic curvature parameter $({\mathrm{\Omega }}_{k0})$. For this we consider two different redshift-dependent parametrizations of the distance duality parameter ($\eta$). The best fit value of ${\mathrm{\Omega }}_{k0}$ clearly indicates an open universe. However, a flat universe can be accommodated at 95% confidence level. Further, at 95% confidence level, no violation of CDDR is observed. We believe that a larger sample of strong gravitational lensing systems is needed in order to improve the constraints on the cosmic curvature and distance duality parameter.

The EDGES experiment has observed an excess trough ($-500_{-500}^{+200}\mathrm{mK}$) in the brightness temperature $T_{21}$ of the 21-cm absorption line of neutral Hydrogen atom (HI) from the era of cosmic dawn ($z\simeq 17.2$). We consider possible interaction of dark matter and dark energy fluid along with the cooling off of the baryon matter by its collision with dark matter to explain the observed excess trough of $T_{21}$. We make use of three different dark matter-dark energy (DM-DE) interaction models to test the viability of those models in explaining the EDGES results. The evolution of Hubble parameter is modified by DM-DE interactions and this is also addressed in this work. This in turn influences the optical depth of HI 21-cm as well as the baryon temperature and thus effects the $T_{21}$ brightness temperature. In addition we also find that the DM-DE interaction enables us to explore dark matter with varied mass regimes and their viabilities in terms of satisfying the EDGES result.

We consider Horndeski modified gravity models obeying stability, velocity of gravitational waves $c_T$ equals $c$ and quasistatic approximation on subhorizon scales. We assume further a Lambda cold dark matter background expansion and a monotonic evolution on the cosmic background of the $\alpha$ functions as ${\alpha }_i={\alpha }_{i0}{a}^s$ where $i=M$, $B$, $a$ is the scale factor and ${\alpha }_{i0}$ (${\alpha }_{M0},{\alpha }_{B0}$), $s$ are arbitrary parameters. We show that the growth and lensing reduced (dimensionless) gravitational couplings $\mu \equiv G_{\text{growth}}/G$, $\mathrm{\Sigma }\equiv G_{\text{lensing}}/G$ exhibit the following generic properties today: ${\mathrm{\Sigma }}_0<1$ for all viable parameters, ${\mu }_0<1$ (weak gravity today) is favored for small $s$ while ${\mu }_0>1$ is favored for large $s$. We establish also the relation $\mu \ge \mathrm{\Sigma }$ at all times. Taking into account the $f{\sigma }_8$ and $E_G$ data we constrain the parameter $s$ to satisfy $s\lesssim 2$. Hence these data select essentially the weak gravity regime today (${\mu }_0<1$) when $s<2$, while ${\mu }_0>1$ subsists only marginally for $s\approx 2$. At least the interval $0.5\lesssim s\lesssim 2$ would be ruled out in the absence of screening. We consider further the growth index $\gamma (z)$ and identify the $({\alpha }_{M0},{\alpha }_{B0},s)$ parameter region that corresponds to specific signs of the differences ${\gamma }_0-{\gamma }_0^{\mathrm{\Lambda }\mathrm{CDM}}$, and ${\gamma }_1-{\gamma }_1^{\mathrm{\Lambda }\mathrm{CDM}}$, where ${\gamma }_0\equiv \gamma {|}_{z=0}$ and ${\gamma }_1\equiv \frac{\mathrm{d}\gamma }{\mathrm{dz}}{|}_{z=0}$. In this way important information is gained on the past evolution of $\mu$. We obtain in particular the signature ${\gamma }_0>{\gamma }_0^{\mathrm{\Lambda }\mathrm{CDM}}$ for $s<2$ in the selected weak gravity region.

Merging neutron stars are expected to produce hot, metastable remnants in rapid differential rotation, which subsequently cool and evolve into rigidly rotating neutron stars or collapse to black holes. Studying this metastable phase and its further evolution is essential for the prediction and interpretation of the electromagnetic, neutrino, and gravitational signals from such a merger. In this work, we model binary neutron star merger remnants and propose new rotation and thermal laws that describe postmerger remnants. Our framework is capable to reproduce quasiequilibrium configurations for generic equations of state, rotation and temperature profiles, including nonbarotropic ones. We demonstrate that our results are in agreement with numerical relativity simulations concerning bulk remnant properties like the mass, angular momentum, and the formation of a massive accretion disk. Because of the low computational cost for our axisymmetric code compared to full $3+1$-dimensional simulations, we can perform an extensive exploration of the binary neutron star remnant parameter space studying several hundred thousand configurations for different equations of state.

In very dense environments, neutrinos can undergo fast flavor conversions on scales as short as a few centimeters provided that the angular distribution of the neutrino lepton number crosses zero. This work presents the first attempt to establish whether the non-negligible abundance of muons and their interactions with neutrinos in the core of supernovae can affect the occurrence of such crossings. For this purpose we employ state-of-the-art one-dimensional core-collapse supernova simulations, considering models that include muon-neutrino interactions as well as models without these reactions. Although a consistent treatment of muons in the equation of state and neutrino transport does not seem to modify significantly the conditions for the occurrence of fast modes, it allows for the existence of an interesting phenomenon, namely fast instabilities in the $\mu -\tau$ sector. We also show that crossings below the supernova shock are a relatively generic feature of the one-dimensional simulations under investigation, which contrasts with the previous reports in the literature. Our results highlight the importance of multidimensional simulations with muon creation, where our results must be tested in the future.

Scalar-field dark matter (SFDM) halos exhibit a core-envelope structure with soliton-like cores and cold-dark matter(CDM)-like envelopes. Simulations without self-interaction (free-field case) have reported a core-halo mass relation of the form $M_c\propto M_h^{\beta }$, with either $\beta =1/3$ or $\beta =5/9$. These results can be understood if the core and halo follow some special energy or velocity scaling relations. We extend these core-halo mass relations here to include the case of SFDM with self-interaction, either repulsive or attractive, and investigate its implications for the possible gravitational instability and collapse of solitonic cores, leading to the formation of supermassive black holes (SMBHs). Core sizes are set by the larger of two length scales, the de Broglie wavelength (in the free-field limit) or the radius $R_{\mathrm{TF}}$ of the ($n=1$)-polytrope for repulsive SFDM (in the Thomas-Fermi regime), depending upon particle mass $m$ and interaction strength $\lambda$. For parameters selected by previous literature to make approximately Kpc-sized cores and CDM-like structure formation on large scales but suppressed on small scales, we find that cores are stable for all galactic halos of interest, from the free-field to the repulsive Thomas-Fermi limit. For attractive self-interaction in this regime, however, halos of mass $M_h\sim {10}^{10}–{10}^{12}{M}_{\odot }$ have cores that collapse to form seed SMBHs with $M_{\mathrm{SMBH}}\sim {10}^6–{10}^8{M}_{\odot }$, as observations seem to require, while smaller-mass halos have stable cores, for particle masses $m=2.14\times {10}^{-22}–9.9\times {10}^{-20}\mathrm{eV}/c^2$, if the free-field limit has $\beta =1/3$, or $m=2.23\times {10}^{-21}–1.7\times {10}^{-18}\mathrm{eV}/c^2$, if $\beta =5/9$. We also place bounds on $\lambda$ for this case. For free-field and repulsive cases, if previous constraints on particle parameters are relaxed to allow much smaller (subgalactic scale) cores, then halos can also form SMBHs, for the same range of halo and black hole masses, as long as $\beta =5/9$ is correct for the free-field limit. In that case, structure formation in SFDM would be largely indistinguishable from that in CDM. As such, while these SFDM models might not help to resolve the small-scale structure problems of CDM, they would explain the formation of SMBHs quite naturally, which is otherwise not a direct feature of CDM. Since CDM, itself, has not yet been ruled out, such SFDM models must also be viable.

Considering the $B$ mesonic distribution amplitude ${\varphi }_{B2}$, we reinvestigated the $B\to PP$ (where $P=\pi$ and $K$) decays with the perturbative QCD (pQCD) approach based on the $k_T$ factorization for three scenarios. It is found that the contributions of ${\varphi }_{B2}$ to form factors $F_0^{B\to P}(0)$ and branching ratios are comparable with those from the NLO corrections. The $B\to K\pi$ decays could be well explained by considering the ${\varphi }_{B2}$. Hence, when the nonleptonic $B$ decays are studied with the pQCD approach, the ${\varphi }_{B2}$ should be taken into account seriously.

We reassess employing the holographic technique to the description of a 4D minimal composite Higgs model with $SO(5)\to SO(4)$ global symmetry breaking pattern. This particular 5D bottom-up holographic treatment is inspired by previous work in the context of QCD and it allows us to study spin one and spin zero resonances. The resulting spectrum consists of the states transforming under the unbroken $SO(4)$ subgroup and those with quantum numbers in the $SO(5)/SO(4)$ coset. The spin one states are arranged in linear radial trajectories, and the states from the broken subgroup are generally heavier. The spin zero states from the coset space correspond to the four massless Goldstone bosons in 4D. One of them takes the role of the Higgs boson. Restrictions derived from the experimental constraints (Higgs couplings, $S$ parameter, etc.) are then implemented and we conclude that the model is able to accommodate new vector resonances with masses in the range 2 TeV to 3 TeV without encountering phenomenological difficulties. The couplings governing the production of these new states in the processes of the Standard Model gauge boson scattering are also estimated. The method can be extended to other breaking patterns.

We discuss the infrared structure of processes with massive quarks in the initial state. It is well known that, starting from next-to-next-to-leading order in perturbative QCD, such processes exhibit a violation of the Bloch-Nordsieck theorem, in that the sum of real and virtual contributions to partonic cross sections contains uncanceled infrared singularities. The main purpose of this paper is to present a simple physical argument that elucidates the origin of these singularities and simplifies the derivation of infrared-singular contributions to heavy-quark initiated cross sections.

We present a method to compute thermodynamic quantities within functional continuum frameworks that is independent of the employed truncation. As a proof of principle, we first apply it to a Nambu-Jona-Lasinio model in mean-field approximation. Then, we use the method with solutions obtained from a coupled set of truncated Dyson-Schwinger equations for the quark and gluon propagators of ($2+1$)-flavor quantum chromodynamics in Landau gauge to obtain the pressure, entropy density, energy density, and interaction measure across the phase diagram of strong-interaction matter. We also discuss the limitation of the proposed method.

Respecting the angular momentum conservation of torque-free systems, it is natural to consider rotating solutions of massive objects. Besides that, motivated by the realistic astrophysical black holes that rotate, we consider a nonlinearly charged regular rotating black hole. We investigate the geometrical properties of the metric by studying the boundary of ergosphere. We also analyze thermodynamic properties of the solution in anti–de Sitter spacetime and examine thermal stability and the existence of phase transition. In addition, we perturb the black hole by using of a real massless scalar field as a probe to investigate its dynamic stability. We also obtain an analytic expression for the real and imaginary parts of the quasinormal frequencies.

Inferring the properties of black holes and neutron stars is a key science goal of gravitational-wave (GW) astronomy. To extract as much information as possible from GW observations, we must develop methods to reduce the cost of Bayesian inference. In this paper, we use artificial neural networks (ANNs) and the parallelization power of graphics processing units (GPUs) to improve the surrogate modeling method, which can produce accelerated versions of existing models. As a first application of our method, the artificial neural networks surrogate model (ANN-Sur), we build a time-domain surrogate model of the spin-aligned binary black hole (BBH) waveform model SEOBNRv4. We achieve median mismatches of approximately $2\mathrm{e}-5$ and mismatches no worse than approximately $2\mathrm{e}-3$. For a typical BBH waveform generated from 12 Hz with a total mass of $60M_{\odot }$, the original SEOBNRv4 model takes 1794 ms. Existing custom-made code optimizations (SEOBNRv4opt) reduced this to 83.7 ms, and the interpolation-based, frequency-domain surrogate SEOBNRv4ROM can generate this waveform in 3.5 ms. Our ANN-Sur model when run on a CPU takes 1.2 ms and when run on a graphics processing unit (GPU) takes just 0.5 ms. ANN-Sur can also generate large batches of waveforms simultaneously. We find that batches of up to ${10}^3$ waveforms can be evaluated on a GPU in just 1.57 ms, corresponding to a time per waveform of 0.0016 ms. This method is a promising way to utilize the parallelization power of GPUs to drastically increase the computational efficiency of Bayesian parameter estimation.

Axionlike particles (ALPs) rotate the linear polarization of photons through the ALP-photon coupling and convert the cosmic microwave background (CMB) $E$ mode to the $B$ mode. We derive the relation between the ALP dynamics and the rotation angle by assuming that the ALP $\varphi$ has a quadratic potential, $V=m^2{\varphi }^2/2$. We compute the current and future sensitivities of CMB observations to the ALP-photon coupling $g$, which can reach $g=4\times {10}^{-21}{\mathrm{GeV}}^{-1}$ for ${10}^{-32}\mathrm{eV}\lesssim m\lesssim {10}^{-28}\mathrm{eV}$ and extensively exceed the other searches for any mass $m\lesssim {10}^{-25}\mathrm{eV}$. We find that the fluctuation of the ALP field at the observer, which has been neglected in previous studies, can induce significant isotropic rotation of the CMB polarization. The measurements of isotropic and anisotropic rotation allow us to put bounds on relevant quantities, such as the ALP mass $m$ and the ALP density parameter ${\mathrm{\Omega }}_{\varphi }$. In particular, if LiteBIRD detects anisotropic rotation, we obtain the lower bound on the tensor-to-scalar ratio as $r>5\times {10}^{-9}$.

Reaching the sufficient sensitivity to detect primordial B-modes requires modern CMB polarization experiments to rely on new technologies, necessary for the deployment of arrays of thousands of detectors with a broad frequency coverage and operating them for extended periods of time. This increased complexity of experimental design unavoidably introduces new instrumental and systematic effects, which in turn may impact performance of the new instruments. In this work we extend the standard data analysis pipeline by including a (parametric) model of instrumental effects directly in the data model. We then correct for them in the analysis, accounting for the additional uncertainty in the final results. We embed these techniques within a general, end-to-end formalism for estimating the impact of the instrument and foreground models on constraints on the amplitude of the primordial B-mode signal. We focus on the parametric component separation approach which we generalize to allow for simultaneous estimation of instrumental and foreground parameters. We demonstrate the framework by studying in detail the effects induced by an achromatic half-wave plate (HWP), which lead to a frequency-dependent variation of the instrument polarization angle, and experimental bandpasses which define observational frequency bands. We assume a typical Stage-3 CMB polarization experiment, and show that maps recovered from raw data collected at each frequency band will unavoidably be linear mixtures of the $Q$ and $U$ Stokes parameters. We then derive a new generalized data model appropriate for such cases, and extend the component separation approach to account for it. We find that some of the instrumental parameters, in particular those describing the HWP, can be successfully constrained by the data themselves without need for external information, while others, like bandpasses, need to be known with good precision in advance. We also show that if the assumed model is an accurate description of the HWP and we have sufficient information about bandpasses, our approach can successfully correct for these effects. In particular, we recover the tensor-to-scalar ratio $r$ down to the precision levels typical of Stage-3 experiments, which aim at setting a ($1\sigma$) upper limit on $r$ of $\sim {10}^{-3}$ if $r=0$.

The detection of gravitational waves from core-collapse supernova (CCSN) explosions is a challenging task, yet to be achieved, in which it is key the connection between multiple messengers, including neutrinos and electromagnetic signals. In this work, we present a method for detecting these kind of signals based on machine learning techniques. We tested its robustness by injecting signals in the real noise data taken by the Advanced LIGO-Virgo network during the second observing run, O2. We trained a newly developed Mini-Inception Resnet neural network using time-frequency images corresponding to injections of simulated phenomenological signals, which mimic the waveforms obtained in 3D numerical simulations of CCSNe. With this algorithm we were able to identify signals from both our phenomenological template bank and from actual numerical 3D simulations of CCSNe. We computed the detection efficiency versus the source distance, obtaining that, for signal to noise ratio higher than 15, the detection efficiency is 70% at a false alarm rate lower than 5%. We notice also that, in the case of the O2 run, it would have been possible to detect signals emitted at 1 kpc of distance, while lowering down the efficiency to 60%, the event distance reaches values up to 14 kpc.

Ultralight bosons can form clouds around rotating black holes if their Compton wavelength is comparable to the black hole size. The boson cloud spins down the black hole through a process called superradiance, lowering the black hole spin to a characteristic spin determined by the boson mass and the black hole mass. It has been suggested that spin measurements of the black holes detected by ground-based gravitational-wave detectors can be used to constrain the mass of ultralight bosons. Unfortunately, a measurement of the individual black hole spins is often uncertain, resulting in inconclusive results. Instead, we use hierarchical Bayesian inference to combine information from multiple gravitational-wave sources and to obtain stronger constraints. We show that hundreds of high signal-to-noise ratio gravitational-wave detections are enough to exclude (confirm) the existence of noninteracting bosons in the mass range $[{10}^{-13},3\times {10}^{-12}]\mathrm{eV}$ $([{10}^{-13},{10}^{-12}]\mathrm{eV})$. The precise number depends on the distribution of black hole spins at formation and the mass of the boson.