We point out that the anomaly of the muon $g-2$ can easily be explained in a focus point supersymmetry (SUSY) scenario, which realizes the seminatural SUSY. Among known focus point SUSY scenarios, we find that a model based on Higgs-gaugino mediation works with a mild fine-tuning $\mathrm{\Delta }=40–80$. We propose two new focus point SUSY scenarios where the anomaly of the muon $g-2$ is also explained. These scenarios are variants of the widely known focus point SUSY based on gravity mediation with universal scalar masses.

We compute the entanglement entropy of soft gluons in the wave function of a fast moving hadron and discuss its basic properties. We also derive the expression for entropy production in a high energy hadronic collision within the color glass formalism. We show that long range rapidity correlations give negative contribution to the production entropy. We calculate the (naturally defined) temperature of the produced system of particles, and show that it is proportional to the average transverse momentum of the produced particles. Our calculations apply to the situation when at least one of the colliding objects is dilute.

The minimal Type I seesaw model cannot explain the observed neutrino masses and the baryon asymmetry of the Universe via hierarchical thermal leptogenesis without ceding naturalness. We show that this conclusion can be avoided by adding a second Higgs doublet with $\tan \beta \gtrsim 4$. The models considered naturally accommodate a standard model-like Higgs boson and predict TeV-scale scalar states and low- to intermediate-scale hierarchical leptogenesis with ${10}^3\mathrm{GeV}\lesssim M_{N_1}\lesssim {10}^8\mathrm{GeV}$.

While Lorentz invariance, the fundamental symmetry of Einstein’s theory of general relativity, has been tested to a great level of detail, grand unified theories that combine gravity with the other three fundamental forces may result in a violation of Lorentz symmetry at the Planck scale. These energies are unattainable experimentally. However, minute deviations from Lorentz invariance may still be present at much lower energies. These deviations can accumulate over large distances, making astrophysical measurements the most sensitive tests of Lorentz symmetry. One effect of Lorentz invariance violation is an energy-dependent photon dispersion of the vacuum resulting in differences of the light travel time from distant objects. The Standard Model Extension (SME) is an effective theory to describe the low-energy behavior of a more fundamental grand unified theory, including Lorentz- and $CPT$-violating terms. In the SME the Lorentz-violating operators can in part be classified by their mass dimension $d$, with the lowest order being $d=5$. However, measurements of photon polarization have constrained operators with $d=5$ setting lower limits on the energy at which they become dominant well beyond the Planck scale. On the other hand, these operators also violate $CPT$, and thus $d=6$ could be the leading order. In this paper we present constraints on all 25 real coefficients describing anisotropic nonbirefringent Lorentz invariance violation at mass dimension $d=6$ in the SME. We used Fermi-LAT observations of 25 active galactic nuclei to constrain photon dispersion and combined our results with previously published limits in order to simultaneously constrain all 25 coefficients. This represents the first set of constraints on these coefficients of mass dimension $d=6$, whereas previous measurements were only able to constrain linear combinations of all 25 coefficients.

We derive the modified diffusion equations defined on kappa spacetime and, using these, investigate the change in the spectral dimension of kappa spacetime with the probe scale. These deformed diffusion equations are derived by applying Wick’s rotation to the $\kappa$-deformed Schrödinger equations obtained from different choices of Klein-Gordon equations in the $\kappa$-deformed spacetime. Using the solutions of these equations, obtained by perturbative method, we calculate the spectral dimension for different choices of the generalized Laplacian and analyze the dimensional flow in the $\kappa$ spacetime. In the limit of commutative spacetime, we recover the well-known equality of spectral dimension and topological dimension. We show that the higher-derivative term in the deformed diffusion equations makes the spectral dimension unbounded (from below) at high energies. We show that the finite mass of the probe results in the spectral dimension becoming infinitely negative at low energies also. In all these cases, we have analyzed the effect of finite size of the probe on the spectral dimension.

The first-order semiclassical Einstein field equations are solved in the interior of the Schwarzschild-Tangherlini black holes. The source term is taken to be the stress-energy tensor of the quantized massive scalar field with arbitrary curvature coupling calculated within the framework of the Schwinger-DeWitt approximation. It is shown that for the minimal coupling the quantum effects tend to isotropize the interior of the black hole (which can be interpreted as an anisotropic collapsing universe) for $D=4$ and 5, whereas for $D=6$ and 7 the spacetime becomes more anisotropic. Similar behavior is observed for the conformal coupling with the reservation that for $D=5$ isotropization of the spacetime occurs during (approximately) the first $1/3$ of the lifetime of the interior universe. On the other hand, we find that regardless of the dimension, the quantum perturbations initially strengthen the growth of curvature and its later behavior depends on the dimension and the coupling. It is shown that the Karlhede’s scalar can still be used as a useful device for locating the horizon of the quantum-corrected black hole, as expected.

In this paper, we explore asymptotically flat charged thin-shell wormholes of third order Lovelock gravity in higher dimensions, taking into account the cut-and-paste technique. Using the generalized junction conditions, we determine the energy-momentum tensor of these solutions on the shell, and explore the issue of the energy conditions and the amount of normal matter that supports these thin-shell wormholes. Our analysis shows that for negative second-order and positive third-order Lovelock coefficients, there are thin-shell wormhole solutions that respect the weak energy condition. In this case, the amount of normal matter increases as the third-order Lovelock coefficient decreases. We also find novel solutions which possess specific regions where the energy conditions are satisfied for the case of a positive second-order and negative third-order Lovelock coefficients. Finally, a linear stability analysis in higher dimensions around the static solutions is carried out. Considering a specific cold equation of state, we find a wide range of stability regions.

Through second order in perturbative general relativity, a small compact object in an external vacuum spacetime obeys a generalized equivalence principle: although it is accelerated with respect to the external background geometry, it is in free fall with respect to a certain effective vacuum geometry. However, this single principle takes very different mathematical forms, with very different behaviors, depending on how one treats perturbed motion. Furthermore, any description of perturbed motion can be altered by a gauge transformation. In this paper, I clarify the relationship between two treatments of perturbed motion and the gauge freedom in each. I first show explicitly how one common treatment, called the Gralla-Wald approximation, can be derived from a second, called the self-consistent approximation. I next present a general treatment of smooth gauge transformations in both approximations, in which I emphasize that the approximations’ governing equations can be formulated in an invariant manner. All of these analyses are carried through second perturbative order, but the methods are general enough to go to any order. Furthermore, the tools I develop, and many of the results, should have broad applicability to any description of perturbed motion, including osculating-geodesic and two-timescale descriptions.

We calculate static and spherically symmetric solutions for the Rastall modification of gravity to describe neutron stars (NS). The key feature of the Rastall gravity is the nonconservation of the energy-momentum tensor proportionally to the space-time curvature. Using realistic equations of state for the NS interior we place a conservative bound on the non-general relativity behavior of the Rastall theory which should be $\lesssim 1\%$ level. This work presents the more stringent constraints on the deviations of general relativity caused by the Rastall proposal.

We examine an interacting dark matter variable vacuum energy model for a spatially flat Friedmann-Roberston-Walker spacetime, focusing on the appearance of cosmological singularities such as big rip, big brake, big freeze, and big separation along with abrupt events (infinite $\gamma$- singularity and new w-singularity) at late times. We introduce a phenomenological interaction which has a nonlinear dependence on the total energy density of the dark sector and its derivative, solve exactly the source equation for the model and find the energy density as a function of the scale factor as well as the time dependence of the approximate scale factor in the neighborhood of the singularities. We describe the main characteristics of these singularities by exploring the type of interaction that makes them possible along with behavior of dark components near them. We apply the geometric Tipler and Królak method for determining the fate of timelike geodesic curves around the singularities. We also explore the strength of them by analyzing the leading term in some geometric invariants such as the square Riemann scalar and the Ricci scalar.

We estimate the degree of circular polarization for the gravitational waves generated during the electroweak and QCD phase transitions from the kinetic and magnetic helicity generated by bubble collisions during those cosmological phase transitions.

Heterodyne laser phase measurements in a space-based gravitational wave interferometer are degraded by the phase fluctuations of the onboard clocks, resulting in unacceptable sensitivity performance levels of the interferometric data. In order to calibrate out the clock phase noises, it has previously been suggested that additional interspacecraft phase measurements must be performed by modulating the laser beams. With the advent of self-referenced optical frequency combs, it is possible to generate a heterodyne microwave signal that is coherently referenced to the onboard laser. We show in this case that the microwave noise can be canceled directly by applying modified second-generation time-delay interferometric combinations to the heterodyne phase measurements. This approach avoids the use of modulated laser beams as well as the need for additional ultrastable oscillator clocks.

We correct Eqs. (27), (32), (36), (44), and (A7) of Ref. [1]. All results and conclusions are unaffected.

We investigate the $\rho D\overline{D}$ three body system using the fixed-center approximation to the Faddeev equations. The study is made assuming scattering of a $\rho$ on a $D\overline{D}$ cluster, which is known to generate the $X(3700)$ or a $\overline{D}$ on a $\rho D$ cluster, which has been shown to generate the $D_1(2420)$. In the case of the $\rho -X(3700)$ scattering we find a state with mass around 4320 MeV and width about 25 MeV for the total three body with isospin-1. Considering the $\overline{D}-D_1(2420)$ scattering we obtain a state with mass around 4256 MeV and width similar to that of the $\rho -X(3700)$ state for the $I=1$ case. For the case of $I=0$ we find a state with mass around 4241 MeV and width about 20 MeV. In all cases we find bound states, and for $I=1$ the states could be associated with the $X(4260)$ and $X(4360)$ mesons.

An electron-positron collider operating at a center-of-mass energy $E_{\mathrm{CM}}$ can collect events at all lower energies through initial-state radiation (ISR or radiative return). We explore the capabilities for radiative return studies by a proposed high-luminosity collider at $E_{\mathrm{CM}}=250$ or 90 GeV, to fill in gaps left by lower-energy colliders such as PEP, PETRA, TRISTAN, and LEP. These capabilities are compared with those of the lower-energy $e^{+}{e}^{-}$ colliders as well as hadron colliders such as the Tevatron and the CERN Large Hadron Collider (LHC). Some examples of accessible questions in dark photon searches and heavy flavor spectroscopy are given.

In the post-LHC8 world—where a Standard Model-like Higgs boson has been established but there is no sign of supersymmetry (SUSY)—the detailed profiling of the Higgs boson properties has emerged as an important road towards discovery of new physics. We present calculations of the expected deviations in Higgs boson couplings ${\kappa }_{\tau ,b}$, ${\kappa }_t$, ${\kappa }_{W,Z}$, ${\kappa }_g$ and ${\kappa }_{\gamma }$ versus the naturalness measure ${\mathrm{\Delta }}_{\mathrm{EW}}$. Low values of ${\mathrm{\Delta }}_{\mathrm{EW}}\sim 10–30$ give rise to a natural little hierarchy characterized by light Higgsinos with a mass of $\mu \sim m_Z$ while top squarks are highly mixed but lie in the several TeV range. For such models with radiatively driven naturalness, one expects the Higgs boson $h$ to look very SM-like although deviations can occur. The more promising road to SUSY discovery requires direct Higgsino pair production at a high energy $e^{+}{e}^{-}$ collider operating with the center-of-mass energy $\sqrt{s}>2\mu \sim \sqrt{2{\mathrm{\Delta }}_{\mathrm{EW}}}{m}_Z$.

We propose the pure sea-quark contributions to the magnetic form factors of $\mathrm{\Sigma }$ baryons, $G_{{\mathrm{\Sigma }}^{-}}^u$ and $G_{{\mathrm{\Sigma }}^{+}}^d$, as priority observables for the examination of sea-quark contributions to baryon structure, both in present lattice QCD simulations and possible future experimental measurement. $G_{{\mathrm{\Sigma }}^{-}}^u$, the $u$-quark contribution to the magnetic form factor of ${\mathrm{\Sigma }}^{-}$, and $G_{{\mathrm{\Sigma }}^{+}}^d$, the $d$-quark contribution to the magnetic form factor of ${\mathrm{\Sigma }}^{+}$, are similar to the strange-quark contribution to the magnetic form factor of the nucleon, but promise to be larger by an order of magnitude. We explore the size of this quantity within chiral effective field theory, including both octet and decuplet intermediate states. The finite range regularization approach is applied to deal with ultraviolet divergences. Drawing on an established connection between quenched and full QCD, this approach makes it possible to predict the sea-quark contribution to the magnetic form factor purely from the meson loop. In the familiar convention where the quark charge is set to unity $G_{{\mathrm{\Sigma }}^{-}}^u=G_{{\mathrm{\Sigma }}^{+}}^d$. We find a value of ${-0.38}_{-0.17}^{+0.16}{\mu }_N$, which is about seven times larger than the strange magnetic moment of the nucleon found in the same approach. Including quark charge factors, the $u$-quark contribution to the ${\mathrm{\Sigma }}^{-}$ magnetic moment exceeds the strange-quark contribution to the nucleon magnetic moment by a factor of 14.

We study the two-baryon system with two units of charm looking for the possible existence of a loosely bound state resembling the $H$ dibaryon. We make use of a chiral constituent quark model tuned in the description of the baryon and meson spectra as well as the $NN$ interaction. The presence of the heavy quarks makes the interaction simpler than in light baryon systems. We analyze possible quark-Pauli effects that would be present in spin-isospin saturated channels. Our results point to the nonexistence of a charmed $H$-like dibaryon, although it may appear as a resonance above the ${\mathrm{\Lambda }}_c{\mathrm{\Lambda }}_c$ threshold.

Assuming the possible existence of an intrinsic (or valencelike) heavy quark component in the proton distribution functions, we analyze the vector boson $Z/W$ production, accompanied by heavy-flavor jets, in $pp$ collisions at the LHC energies. We present theoretical predictions for differential cross sections of such processes and demonstrate their large sensitivity to parton distribution functions including an intrinsic charm component to the proton in some kinematical regions. Ratio measurements of the $Z+$ heavy-flavor jets differential cross sections over the corresponding spectra in $W+$ heavy jets events are proposed. These ratios are studied as a function of two different observables that maximize their sensitivity to the intrinsic charm component of the proton: the transverse momentum of the leading heavy-flavor jet and the longitudinal momentum fraction $x_F^Q$ of this jet. Such measurements look very promising for the LHC experiments because they can supply unique information about the intrinsic charm hypothesis.