In this paper, we apply reconstruction techniques to recover the potential parameters for a particular class of single-field models, the $\alpha$-attractor (supergravity) models of inflation. This also allows us to derive the inflaton vacuum expectation value at horizon crossing. We show how to use this value as one of the input variables to constrain the postaccelerated inflationary phase. We assume that the tensor-to-scalar ratio $r$ is of the order of ${10}^{-3}$, a level reachable by the expected sensitivity of the next-generation cosmic macrowave background (radiation) experiments.

The relic abundance of the dark matter (DM) particle $d$ is studied in a secluded DM scenario, in which the $d$ number decreasing process dominantly occurs not through the pair annihilation of $d$ into the standard model particles, but via the $dd\to mm$ scattering process with a subsequently decaying mediator particle $m$. It is pointed out that the cosmologically observed relic abundance of DM can be accomplished even with a massive mediator having a mass $m_m$ non-negligibly heavy compared with the DM particle mass $m_d$. In the degenerated $d-m$ case ($m_d=m_m$), the DM relic abundance is realized by adjusting the $dd\to mm$ scattering amplitude large enough and by choosing an appropriate mediator particle lifetime. The DM evolution in the early universe exhibits characteristic “terrace” behavior, or two-step number density decreasing behavior, having a “fake” freeze-out at the first step. Based on these observations, a novel possibility of the DM model buildings is introduced in which the mediator particle $m$ is unified with the DM particle $d$ in an approximate dark symmetry multiplet. A pionic DM model is proposed to illustrate this idea in a renormalizable field theory framework.

We study gauge symmetry breaking patterns of the five-dimensional $SU(5)$ grand gauge-Higgs unification compactified on an orbifold $S^1/{\mathbb{Z}}_2$ with the Hosotani mechanism in the framework of the diagonal embedding method. We find matter contents that lead to the $SU(3)\times SU(2)\times U(1)$ gauge symmetry on the global minimum of the effective potential and also present examples of matter content for which each regular subgroup of $SU(5)$ is realized as vacuum configuration. The finite-temperature phase transitions for the models with the gauge symmetry of the standard model at zero temperature and also for supersymmetric models are studied. We show in a certain model with supersymmetry that the vacuum of the standard model selected dynamically before the inflation continues to stay there up to the present.

We study the cosmological history of the classical conformal $B-L$ gauge extension of the standard model, in which the physical scales are generated via the Coleman-Weinberg-type symmetry breaking. In particular, we consider the thermal phase transition of the $\mathrm{U}(1{)}_{B-L}$ symmetry in the early Universe and resulting gravitational wave production. Due to the classical conformal invariance, the phase transition tends to be a first-order one with ultra-supercooling, which enhances the strength of the produced gravitational waves. We show that, requiring (1) $\mathrm{U}(1{)}_{B-L}$ is broken after the reheating, (2) the $B-L$ gauge coupling does not blow up below the Planck scale, and (3) the thermal phase transition completes in almost all the patches in the Universe, the gravitational wave spectrum can be as large as ${\mathrm{\Omega }}_{\mathrm{GW}}\sim {10}^{-8}$ at the frequency $f\sim 0.01–1\mathrm{Hz}$ for some model parameters, and a vast parameter region can be tested by future interferometer experiments.

Using a finite volume gradient flow renormalization scheme with Schrödinger Functional boundary conditions, we compute the nonperturbative running coupling in the range $2.2\lesssim {\overline{g}}_{\mathrm{GF}}^2(L)\lesssim 13$. Careful continuum extrapolations turn out to be crucial to reach our high accuracy. The running of the coupling is always between one loop and two loop and very close to one loop in the region of $200\mathrm{MeV}\lesssim \mu =1/L\lesssim 4\mathrm{GeV}$. While there is no convincing contact to two-loop running, we match nonperturbatively to the Schrödinger functional coupling with background field. In this case, we know the $\mu$-dependence up to $\sim 100\mathrm{GeV}$ and can thus connect to the $\mathrm{\Lambda }$-parameter.

Classical lattice Yang-Mills calculations provide a good way to understand different nonequilibrium phenomena in nonperturbatively overoccupied systems. Above the Debye scale the classical theory can be matched smoothly to kinetic theory. The aim of this work is to study the limits of this quasiparticle picture by determining the plasmon mass in classical real-time Yang-Mills theory on a lattice in three spatial dimensions. We compare three methods to determine the plasmon mass: a hard thermal loop expression in terms of the particle distribution, an effective dispersion relation constructed from fields and their time derivatives, and the measurement of oscillations between electric and magnetic field modes after artificially introducing a homogeneous color electric field. We find that a version of the dispersion relation that uses electric fields and their time derivatives agrees with the other methods within 50%.

Results are reported from a search for $R$-parity violating supersymmetry in proton-proton collision events collected by the CMS experiment at a center-of-mass energy of $\sqrt{s}=8\mathrm{TeV}$. The data sample corresponds to an integrated luminosity of $17.6{\mathrm{fb}}^{-1}$. This search assumes a minimal flavor violating model in which the lightest supersymmetric particle is a long-lived neutralino or gluino, leading to a signal with jets emanating from displaced vertices. In a sample of events with two displaced vertices, no excess yield above the expectation from standard model processes is observed, and limits are placed on the pair production cross section as a function of mass and lifetime of the neutralino or gluino. At 95% confidence level, the analysis excludes cross sections above approximately 1 fb for neutralinos or gluinos with mass between 400 and 1500 GeV and mean proper decay length between 1 and 30 mm. Gluino masses are excluded below 1 and 1.3 TeV for mean proper decay lengths of $300\mu \mathrm{m}$ and 1 mm, respectively, and below 1.4 TeV for the range 2–30 mm. The results are also applicable to other models in which long-lived particles decay into multijet final states.

We investigate left-right symmetric extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. The left-handed and right-handed fermions transform as doublets under $Sp(1{)}_L$ and $Sp(1{)}_R$, and so their masses must be generated by the introduction of Higgs fields in a bifundamental $(\mathbf{2},\mathbf{2})$ representation under the two $Sp(1)$ gauge groups. For such D-brane configurations the left-right symmetry must be broken by Higgs fields in the doublet representation of $Sp(1{)}_R$ and therefore Majorana mass terms are suppressed by some higher physics scale. The left-handed and right-handed neutrinos pair up to form Dirac fermions which control the decay widths of the right-handed $W^{\prime }$ boson to yield comparable branching fractions into dilepton and dijet channels. Using the most recent searches at LHC13 Run II with 2016 data we constrain the $(g_R,m_{W^{\prime }})$ parameter space. Our analysis indicates that independent of the coupling strength $g_R$, gauge bosons with masses $m_{W^{\prime }}\gtrsim 3.5\mathrm{TeV}$ are not ruled out. As the LHC is just beginning to probe the TeV scale, significant room for $W^{\prime }$ discovery remains.

Two particle irreducible effective actions (2PIEAs) are valuable nonperturbative techniques in quantum field theory; however, finite truncations of them violate the Ward identities (WIs) of theories with spontaneously broken symmetries. The symmetry improvement (SI) method of Pilaftsis and Teresi attempts to overcome this by imposing the WIs as constraints on the solution; however, the method suffers from the nonexistence of solutions in linear response theory and in certain truncations in equilibrium. Motivated by this, we introduce a new method called soft-symmetry improvement (SSI) which relaxes the constraint. Violations of WIs are allowed but punished in a least-squares implementation of the symmetry improvement idea. A new parameter $\xi$ controls the strength of the constraint. The method interpolates between the unimproved ($\xi \to \infty$) and SI ($\xi \to 0$) cases, and the hope is that practically useful solutions can be found for finite $\xi$. We study the SSI 2PIEA for a scalar $\mathrm{O}(N)$ model in the Hartree-Fock approximation. We find that the method is IR sensitive; the system must be formulated in finite volume $V$ and temperature $T={\beta }^{-1}$, and the $V\beta \to \infty$ limit must be taken carefully. Three distinct limits exist. Two are equivalent to the unimproved 2PIEA and SI 2PIEA respectively, and the third is a new limit where the WI is satisfied but the phase transition is strongly first order and solutions can fail to exist depending on $\xi$. Further, these limits are disconnected from each other; there is no smooth way to interpolate from one to another. These results suggest that any potential advantages of SSI methods, and indeed any application of (S)SI methods out of equilibrium, must occur in finite volume.

Scale invariant fluctuations of metric are a universal feature of quantum gravity in de Sitter spacetime. We construct an effective Lagrangian which summarizes their implications on local physics by integrating superhorizon metric fluctuations. It shows infrared quantum effects are local and render fundamental couplings time dependent. We impose Lorenz invariance on the effective Lagrangian as it is required by the principle of general covariance. We show that such a requirement leads to unique physical predictions by fixing the quantization ambiguities. We explain how the gauge parameter dependence of observables is canceled. In particular the relative evolution speed of the couplings are shown to be gauge invariant.

Ultracold neutrons confined in the Earth’s gravitational field display quantized energy levels that have been observed for over a decade. In recent resonance spectroscopy experiments [T. Jenke et al., Nat. Phys. 7, 468 (2011)], the transition between two such gravitational quantum states was driven by the mechanical oscillation of the plates that confine the neutrons. Here we show that by applying a sinusoidal modulation with slowly varying frequency (chirp), the neutrons can be brought to higher excited states by climbing the energy levels one by one. The proposed experiment should make it possible to observe the quantum-classical transition that occurs at high neutron energies. Furthermore, it provides a technique to realize superpositions of gravitational quantum states, to be used for precision tests of gravity at short distances.

One of the fundamental results used in observational cosmology is the distance duality relation (DDR), which relates the luminosity distance, ${\mathrm{D}}_{\mathrm{L}}$, with angular diameter distance, ${\mathrm{D}}_{\mathrm{A}}$, at a given redshift $z$. We employ the observed limits of this relation to constrain the coupling of axionlike particles (ALPs) with photons. With our detailed $3D$ ALP-photon mixing simulation in standard $\mathrm{\Lambda }\mathrm{CDM}$ universe and latest DDR limits observed in Holanda and Barros [Phys. Rev. D 94, 023524 (2016)]. we limit the coupling constant $g_{\varphi }\le 6\times {10}^{-13}{\mathrm{GeV}}^{-1}(\frac{nG}{⟨B{⟩}_{\mathrm{Mpc}}})$ for ALPs of mass $\le {10}^{-15}\mathrm{eV}$. The DDR observations can provide very stringent constraint on ALPs mixing in the future. Also any deviation in DDR can be conventionally explained as photons decaying to axions or vice-versa.

The Sun’s gravitational potential at Earth varies during a year due to varying Earth-Sun distance. Comparing the results of very accurate measurements of atomic clock transitions performed at different times in the year allows us to study the dependence of the atomic frequencies on the gravitational potential. We examine the measurement data for the ratio of the frequencies in ${\mathrm{Hg}}^{+}$ and ${\mathrm{Al}}^{+}$ clock transitions and absolute frequency measurements (with respect to the caesium frequency standard) for Dy, Sr, H, hyperfine transitions in Rb and H and obtain significantly improved limits on the values of the gravity-related parameter of the Einstein equivalence principle violating term in the electron sector of the Standard Model extension Hamiltonian $c_{00}=(-3.0\pm 5.7)\times {10}^{-7}$ and the parameter for the gravity-related variation of the fine structure constant ${\kappa }_{\alpha }=(-5.3\pm 10)\times {10}^{-8}$.

The pole structure of the $\mathrm{\Lambda }(1405)$ is examined by fitting the couplings of an underlying Hamiltonian effective field theory to cross sections of $K^{-}p$ scattering in the infinite-volume limit. Finite-volume spectra are then obtained from the theory, and compared to lattice QCD results for the mass of the $\mathrm{\Lambda }(1405)$. Momentum-dependent, nonseparable potentials motivated by the well-known Weinberg-Tomozawa terms are used, with SU(3) flavor symmetry broken in the couplings and masses. In addition, we examine the effect on the behavior of the spectra from the inclusion of a bare triquarklike isospin-zero basis state. It is found that the cross sections are consistent with the experimental data with two complex poles for the $\mathrm{\Lambda }(1405)$, regardless of whether a bare-baryon basis state is introduced or not. However, it is apparent that the bare baryon is important for describing the results of lattice QCD at high pion masses.

We evaluate the light-quark meson contributions to three exact light-by-light scattering sum rules in light of new data by the Belle Collaboration, which recently has extracted the transition form factors of the tensor meson $f_2(1270)$ as well as of the scalar meson $f_0(980)$. We confirm a previous finding that the $\eta ,{\eta }^{\prime }$ and helicity-2 $f_2(1270)$ contributions saturate one of these sum rules up to photon virtualities around $1\mathrm{Ge}{\mathrm{V}}^2$. At larger virtualities, our sum rule analysis shows an important contribution of the $f_2(1565)$ meson and provides a first empirical extraction of its helicity-2 transition form factor. Two further sum rules allow us to predict the helicity-0 and helicity-1 transition form factors of the $f_2(1270)$ meson. Furthermore, our analysis also provides an update for the scalar and tensor meson hadronic light-by-light contributions to the muon’s anomalous magnetic moment.

We reconsider the possibility that the tension in the $|V_{cb}|$ determinations from inclusive and exclusive $B$ decay modes is due to a new physics effect. We modify the Standard Model effective Hamiltonian for semileptonic $b\to c$ transitions including a tensor operator with a lepton flavor-dependent coupling ${\epsilon }_T^{\ell }$ and investigate separately the muon and electron modes. The interference term between SM and NP, proportional to the lepton mass, has different impact in the inclusive and exclusive $B$ modes to muon. Moreover, even when the lepton mass is small as for the electron, the NP effect is different in inclusive and exclusive $B$ channels. For both $\mu$ and $e$, we find a region of ${\epsilon }_T^{\mu ,e}$ where the constraints from $B^{-}\to D^{(*)0}{\ell }^{-}{\overline{\nu }}_{\ell }$ and $B\to X_c\ell {\overline{\nu }}_{\ell }$ are satisfied for the same $|V_{cb}|$.

Gravitational lensing is a good probe into the topological structure of dark gravitating celestial objects. In this paper, we investigate the light curve of a light ray that passes through the throat of an Ellis wormhole, the simplest example of traversable wormholes. The method developed here is also applicable to other traversable wormholes. To study whether the light curve of a light ray that passes through a wormhole throat is distinguishable from that which does not, we also calculate light curves without the passage of a throat for an Ellis wormhole, a Schwarzschild black hole, and an ultrastatic wormhole with the spatial geometry identical to that of the Schwarzschild black hole in the following two cases: (i) “microlensing,” where the source, lens, and observer are almost aligned in this order and the light ray starts at the source, refracts in the weak gravitational field of the lens with a small deflection angle, and reaches the observer; and (ii) “retrolensing,” where the source, observer, and lens are almost aligned in this order, and the light ray starts at the source, refracts in the vicinity of the light sphere of the lens with a deflection angle very close to $\pi$, and reaches the observer. We find that the light curve of the light ray that passes through the throat of the Ellis wormhole is clearly distinguishable from that by the microlensing but not from that by the retrolensing. This is because the light curve of a light ray that passes by a light sphere of a lens with a large deflection angle has common characters, irrespective of the details of the lens object. This implies that the light curves of the light rays that pass through the throat of more general traversable wormholes are qualitatively the same as that of the Ellis wormhole.

We present new $(3+1)\mathrm{D}$ numerical relativity simulations of the binary neutron star (BNS) merger and postmerger phase. We focus on a previously inaccessible region of the binary parameter space spanning the binary’s mass ratio $q\sim 1.00–1.75$ for different total masses and equations of state, and up to $q\sim 2$ for a stiff BNS system. We study the mass ratio effect on the gravitational waves (GWs) and on the possible electromagnetic (EM) emission associated with dynamical mass ejecta. We compute waveforms, spectra, and spectrograms of the GW strain including all the multipoles up to $l=4$. The mass ratio has a specific imprint on the GW multipoles in the late-inspiral-merger signal, and it affects qualitatively the spectra of the merger remnant. The multipole effect is also studied by considering the dependency of the GW spectrograms on the source’s sky location. Unequal mass BNSs produce more ejecta than equal mass systems with ejecta masses and kinetic energies depending almost linearly on $q$. We estimate luminosity peaks and light curves of macronova events associated with the mergers using a simple approach. For $q\sim 2$ the luminosity peak is delayed for several days and can be up to 4 times larger than for the $q=1$ cases. The macronova emission associated with the $q\sim 2$ BNS is more persistent in time and could be observed for weeks instead of a few days ($q=1$) in the near infrared. Finally, we estimate the flux of possible radio flares produced by the interaction of relativistic outflows with the surrounding medium. Also in this case a large $q$ can significantly enhance the emission and delay the peak luminosity. Overall, our results indicate that the BNS merger with a large mass ratio has EM signatures distinct from the equal mass case and more similar to black hole–neutron star binaries.

We extend the dynamical systems analysis of scalar-fluid interacting dark energy models performed in C. G. Boehmer et al., Phys. Rev. D 91, 123002 (2015) by considering scalar field potentials beyond the exponential type. The properties and stability of critical points are examined using a combination of linear analysis, computational methods and advanced mathematical techniques, such as center manifold theory. We show that the interesting results obtained with an exponential potential can generally be recovered also for more complicated scalar field potentials. In particular, employing power law and hyperbolic potentials as examples, we find late time accelerated attractors, transitions from dark matter to dark energy domination with specific distinguishing features, and accelerated scaling solutions capable of solving the cosmic coincidence problem.

We revisit the inflationary dynamics in detail for theories with Gauss-Bonnet gravity coupled to scalar functions, in light of the Planck data. Considering the chaotic inflationary scenario, we constrain the parameters of two models involving inflaton-Gauss-Bonnet coupling by current Planck data. For nonzero inflaton-Gauss-Bonnet coupling $\beta$, an inflationary analysis provides us a big cosmologically viable region in the space of ($m$, $\beta$), where $m$ is the mass of the inflaton. However, we study further on constraining $\beta$ arising from reheating considerations and unitarity of tree-level amplitude involving 2-graviton $\to 2$-graviton ($hh\to hh$) scattering. Our analysis, particularly on reheating significantly reduces the parameter space of ($m$, $\beta$) for all models. The quadratic Gauss-Bonnet coupling parameter turns out to be more strongly constrained than that of the linear coupling. For the linear Gauss-Bonnet coupling function, we obtain $\beta \lesssim 10^3$, with the condition $\beta (m/M_P{)}^2\simeq {10}^{-4}$. However, the study of the Higgs inflation scenario in the presence of a Gauss-Bonnet term turns out to be completely disfavored.