Using a $2.93{\mathrm{fb}}^{-1}$ data sample of electron-positron collisions taken with the BESIII detector at a center-of-mass energy of 3.773 GeV, which corresponds to $(8296\pm 31\pm 64)\times {10}^3{D}^{+}{D}^{-}$ pairs, we search for the baryon and lepton number violating decays $D^{+}\to \overline{\mathrm{\Lambda }}({\overline{\mathrm{\Sigma }}}^0)e^{+}$ and $D^{+}\to \mathrm{\Lambda }({\mathrm{\Sigma }}^0)e^{+}$. No obvious signals are found with the current statistics and upper limits on the branching fractions of these four decays are set at the level of ${10}^{-6}$ at 90% confidence level.

A 0.93 g $1\times 1\times 0.4{\mathrm{cm}}^3$ SuperCDMS silicon HVeV detector operated at 30 mK was illuminated by 1.91 eV photons using a room temperature pulsed laser coupled to the cryostat via fiber optic. The detector’s response under a variety of specific operating conditions was used to study the detector leakage current, charge trapping, and impact ionization in the high-purity Si substrate. The measured probabilities for a charge carrier in the detector to undergo charge trapping ($0.713\pm 0.093\%$) or cause impact ionization ($1.576\pm 0.110\%$) were found to be nearly independent of bias polarity and charge-carrier type (electron or hole) for substrate biases of $\pm 140\mathrm{V}$.

A matter-coupled scalar field model is presented to obtain a scalar fifth force when the constraint of the current cosmological constant is satisfied. The interaction potential energy density between the scalar field and matter has a symmetry-breaking form with two potential wells. We prove that the cosmological constant is a value of the scalar field’s self-interaction potential energy density at the minimum of the effective matter-density-dependent potential energy density. The effective potential is a sum of the interaction potential and the self-interaction potential of the scalar field. The scalar field can stably sit at the minimum; then the time-dependent cosmological “constant” behaves like a constant. The scheme does not conflict with chameleon no-go theorems. However, since the quintessence is trapped by one of the interaction potential wells, the observed cosmic acceleration can be accounted for by the scalar field. The scalar field is also extrapolated to account for inflation at the inflationary era of the Universe. In this era matter fluid is relativistic, and the interaction potential wells vanish. The unconfined quintessence therefore dominates the evolution of the Universe. We conclude that Planck 2018 results favor the closed space of the Universe. The reasons for this are the measured value of the current Hubble constant and the observation of a concave potential in the framework of single-field inflationary models. By invoking a pseudopotential in the inflationary era, the concave feature can be attributed to the pseudopotential, although the self-interaction potential is a convex function. The pseudopotential is defined by a sum of the self-interaction potential and the energy density scale of the curvature of the Universe. The positive curvature leads to the concave feature of the pseudopotential. Within the constraints of the cosmological constants, including the maximum cosmological constant in the inflationary era, we find that the strength of the fifth force is large compared with gravity. Due to the short range of the interaction, the local test of gravity is satisfied. The coupling coefficient denoting the force strength is inversely proportional to the ambient density, while the interaction range is inversely proportional to the square root of the density. For the current matter density $\sim {10}^{-27}\mathrm{kg}/{\mathrm{m}}^3$ of the Universe, the corresponding interaction range is $\sim 5\mu \mathrm{m}$ and the coupling coefficient is $\sim 10^{31}$. Since the fifth force is localized in an extreme thin shell, experiments might be designed so that the test objects can pass through the thin shell.

We show that equations of Newtonian hydrodynamics and gravity with Einstein’s cosmological constant included admit gravitostatic wave solutions propagating in the background of Einstein’s static universe. In the zero pressure limit these waves exist at an average matter density exceeding that of Einstein’s universe. They have the form of a lattice of integrable density singularities localized at the maxima of the gravitational potential. These singularities are steady-state counterparts of the so-called Zeldovich pancakes (ZP), interim wall-like structures appearing at nonlinear stages of development of gravitational instability. As the average matter density decreases, the period of the ZP lattice increases, diverging at the density of Einstein’s universe. Solitary wave solutions are found at exactly the density of Einstein’s universe, and at a slightly larger density, the wave may be viewed as a lattice of well-separated ZP solitons.

We study the chiral phase transition of the two-flavor Nambu–Jona-Lasinio model in a sphere with the MIT boundary condition. We find that the spherical MIT boundary condition results in stronger finite size effects than the antiperiodic boundary condition. Our work may be helpful to study the finite size effects in heavy-ion collisions in a more realistic way.

Extensions of the Standard Model that include vectorlike quarks commonly also include additional particles that may mediate new production or decay modes. Using the minimal linear $\sigma$ model as an example, which reduces to the minimal $SO(5)/SO(4)$ composite Higgs model in a specific limit, we consider the phenomenology of vectorlike quarks when a scalar singlet $\sigma$ is present. This new particle may be produced in the decays $T\to t\sigma$, $B\to b\sigma$, where $T$ and $B$ are vectorlike quarks of charges $2/3$ and $-1/3$, respectively, with the subsequent decay $\sigma \to W^{+}{W}^{-}$, $ZZ$, $hh$. By scanning over the allowed parameter space we find that these decays may be dominant. In addition, we find that the presence of several new particles allows for single $T$ production cross sections larger than those expected in minimal models. We discuss the observability of these new signatures in existing searches.

We propose a new strategy to evaluate the partition function of lattice QCD with Wilson gauge action coupled to staggered fermions, based on a strong coupling expansion in the inverse bare gauge coupling $\beta =2N/g^2$. Our method makes use of the recently developed formalism to evaluate the $\mathrm{SU}(N)$ 1-link integrals and consists in an exact rewriting of the partition function in terms of a set of additional dual degrees of freedom which we call “decoupling operator indices” (DOI). The method is not limited to any particular number of dimensions or gauge group $\mathrm{U}(N)$, $\mathrm{SU}(N)$. In terms of the DOI, the system takes the form of a tensor network which can be simulated using wormlike algorithms. Higher order $\beta$-corrections to strong coupling lattice QCD can be, in principle, systematically evaluated, helping to answer the question whether the finite density sign problem remains mild when plaquette contributions are included. Issues related to the complexity of the description and strategies for the stochastic evaluation of the partition function are discussed.

The energy momentum tensor (EMT) form factors pave new ways for exploring hadron structure. Especially, the $D$-term related to the EMT form factor $D(t)$ has received a lot of attention due to its attractive physical interpretation in terms of mechanical properties. We study the nucleon EMT form factors and the associated densities in the bag model which we formulate for an arbitrary number of colors $N_c$ and show that the EMT form factors are consistently described in this model in the large-$N_c$ limit. The simplicity of the model allows us to test in a lucid way many theoretical concepts related to EMT form factors and densities including recently introduced concepts like normal and tangential forces, or monopole and quadrupole contributions to the angular momentum distribution. We also study the $D$-terms of the $\rho$-meson, Roper resonance, other $N^{*}$ states, and $\mathrm{\Delta }$-resonances. Among the most interesting outcomes is the lucid demonstration of the deeper connection of EMT conservation, stability, the virial theorem, and the negative sign of the $D$-term.

We report here the first experimental result for the anisotropy of the one-way maximum attainable speed of the electron, $\mathrm{\Delta }{\overrightarrow{c}}_{1,e}$, obtained via the study of a sidereal time dependence of the difference between momenta of the counterrotating electron and positron beams in the Cornell Electron Storage Ring at Cornell University. At 95% confidence, an upper limit for the component of $\mathrm{\Delta }{\overrightarrow{c}}_{1,e}/c$ perpendicular to Earth’s rotational axis is found to be $5.5\times {10}^{-15}$.

We show that the phase II upgrade of the CMS tracking detector could enable the experiment to trigger on very low mass $\mathcal{O}(1\mathrm{GeV})$ displaced muon pairs with minimal $p_T$ cuts. As a result, CMS can be competitive with LHCb when searching for low mass displaced exotics originating from heavy flavor decays. The method can also be applied to signatures without muons but with a moderate amount of missing transverse energy, $H_T$ or multiple displaced vertices in the event.

Classical double copy is an intriguing relationship between classical solutions to a gravity theory and solutions to classical Yang-Mills equations. Although formally inspired by the double copy relation between (quantum) scattering amplitudes in Yang-Mills and perturbative gravity, a direct proof of the former from the latter continues to be under investigation. In this paper, we attempt to prove classical double copy from the color-kinematics duality symmetry of scalar QCD amplitudes in a restricted setting. That is, we consider radiative solutions with classical scattering sources in Yang-Mills theory and perturbative gravity in $D>4$ spacetime dimensions. We show that when the frequency of radiation is much smaller than the characteristic frequency of the process, then at the subleading order in frequency, the classical double copy relating radiative gluon field to radiative gravitational field can be proved from the color-kinematics duality of scalar QCD amplitudes.

Starting from the swampland distance conjecture, and using the species bound for a large number of weakly coupled particles, we give a derivation of the recently proposed trans-Planckian censorship conjecture. Our argument demonstrates how a quantum gravity principle requires that trans-Planckian quantum fluctuations should never cross the Hubble horizon. We also comment on how logarithmic corrections to the de Sitter conjecture arise naturally from such an approach when one relaxes the requirement of traversing parametrically large distances on field space.

We discuss the question of time in a Bianchi I quantum cosmology in the framework of singularity avoidance. We show that time parameters fall into two distinct classes, that are such that the time development of the wave function either always leads to the appearance of a singularity (fast-gauge time) or that always prevents it from occurring (slow-gauge time). Furthermore, we find that, in the latter case, there exists an asymptotic regime, independent of the clock choice. This may point to a possible solution of the clock issue in quantum cosmology if there exists a suitable class of clocks all yielding identical relevant physical consequences.

The composition of neutron stars at the extreme densities reached in their cores is currently unknown. Besides nuclear matter of normal neutrons and protons, the cores of neutron stars might harbor exotic matter such as deconfined quarks. In this paper we study strong hadron-quark phase transitions in the context of gravitational wave observations of inspiraling neutron stars. We consider upcoming detections of neutron star coalescences and model the neutron star equations of state with phase transitions through the Constant-Speed-of-Sound parametrization. We use the fact that neutron star binaries with one or more hadron-quark hybrid stars can exhibit qualitatively different tidal properties than binaries with hadronic stars of the same mass, and hierarchically model the masses and tidal properties of simulated populations of binary neutron star inspiral signals. We explore the parameter space of phase transitions and discuss under which conditions future observations of binary neutron star inspirals can identify this effect and constrain its properties, in particular the threshold density at which the transition happens and the strength of the transition. We find that if the detected population of binary neutron stars contains both hadronic and hybrid stars, the onset mass and strength of a sufficiently strong phase transition can be constrained with 50–100 detections. If the detected neutron stars are exclusively hadronic or hybrid, then it is possible to place lower or upper limits on the transition density and strength.

We study the motion of photons in the background of a three-dimensional rotating Hořava-AdS black hole that corresponds to a Lorentz-violating version of the Bañados-Teitelboim-Zanelliblack hole, and we analyze the effect of the breaking of Lorentz invariance on the null geodesics structure, by solving analytically the equations of motion. Mainly we find that, through a fine-tuning of the parameters of the theory, new kinds of orbits are allowed, such as unstable circular orbits and trajectories of the first kind. Also, we show that an external observer will see that photons arrive at spatial infinity in a finite coordinate time.

In this paper, we construct rotating boson stars composed of the coexisting states of two scalar fields, including the ground and first excited states. We show the coexisting phase with both the ground and first excited states for rotating multistate boson stars. In contrast to the solutions of the nodeless boson stars, the rotating boson stars with two states have two types of nodes, including the ${}^{1}S{}^{2}S$ state and the ${}^{1}S{}^{2}P$ state. Moreover, we explore the properties of the mass $M$ of rotating boson stars with two states as a function of the synchronized frequency $\omega$, as well as the nonsynchronized frequency ${\omega }_2$. Finally, we also study the dependence of the mass $M$ of rotating boson stars with two states on angular momentum for both the synchronized frequency $\omega$ and the nonsynchronized frequency ${\omega }_2$.

In this paper we study the survival of the entanglement of a scalar field state created during inflation. We find that there exist UV-finite subdominant contributions to the entanglement entropy per momentum mode that scale with the number of $e$-folds between horizon exit and the end of inflation, and that depend on the logarithm of the radius of the entangling surface, which can be taken to be the Hubble sphere. We argue that this entanglement entropy allows for the formation of entangled primordial black holes (PBHs). We find that the entropy arising from the entanglement between PBHs is small compared with their Bekenstein entropy.

We consider the possibility that, in the semiclassical Einstein equation for cosmological spacetimes, gravity is sourced by the amount of stress-energy that is above that of the instantaneous ground state. For this possibility to be consistent, the Bianchi identities must continue to hold. This is nontrivial, because it means that the ground state expectation value of the stress-energy tensor must be covariantly conserved in spite of the fact that the ground state is generally a different state at different times. We prove that this consistency condition does hold. As a consequence, we find that the vacuum stress-energy which is above the instantaneous ground state does not renormalize the cosmological constant, as long as the instantaneous ground states and the instantaneous adiabatic vacua exist.

We study the new mechanism of the axion production suggested recently in [H. Fischer, X. Liang, Y. Semertzidis, A. Zhitnitsky, and K. Zioutas, Phys. Rev. D 98, 043013 (2018), K. Lawson, X. Liang, A. Mead, M. S. R. Siddiqui, L. Van Waerbeke, and A. Zhitnitsky, Phys. Rev. D 100, 043531 (2019)]. This mechanism is based on the so-called axion quark nugget (AQN) dark matter model, which was originally invented to explain the similarity of the dark and visible cosmological matter densities. We perform numerical simulations to evaluate the axion flux on the Earth’s surface. We examine annual and daily modulations, which have been studied previously and are known to occur for any type of dark matter. We also discuss a novel type of short time enhancements which are unique to the AQN model: the statistical fluctuations and burstlike amplification, both of which can drastically amplify the axion signal, up to a factor $\sim {10}^2–{10}^3$ for a very short period of time. The present work studies the AQN-induced axions within the mass window ${10}^{-6}\mathrm{eV}\lesssim m_a\lesssim {10}^{-3}\mathrm{eV}$ with typical velocities $⟨v_a⟩\sim 0.6c$. We also comment on the broadband detection strategy to search for such relativistic axions by studying the daily and annual time modulations as well as random burstlike amplifications.