We apply the full Will-Nordtvedt version of the parametrized post-Newtonian (PPN) formalism to a class of general relativity extensions that are based on nontrivial renormalization group (RG) effects at large scales. We focus on a class of models in which the gravitational coupling constant $G$ is correlated with the Newtonian potential. A previous PPN analysis considered a specific realization of the RG effects, and only within the Eddington-Robertson-Schiff version of the PPN formalism, which is a less complete and robust PPN formulation. Here we find stronger, more precise bounds, and with less assumptions. We also consider the external potential effect (EPE), which is an effect that is intrinsic to this framework and depends on the system environment (it has some qualitative similarities to the screening mechanisms of modified gravity theories). We find a single particular RG realization that is not affected by the EPE. Some physical systems have been pointed out as candidates for measuring the possible RG effects in gravity at large scales; for any of them the Solar System bounds need to be considered.

The merger of colliding black holes (BHs) should lead to the production of ringdown or quasinormal modes (QNMs), which may very well be sensitive to the state of the interior. We put this idea to the test with a recent proposal that the interior of a BH consists of a bound state of highly excited, long, closed, interacting strings; figuratively, a collapsed polymer. We show, using scalar perturbations for simplicity, that such BHs do indeed have a distinct signature in their QNM spectrum: A new class of modes whose frequencies are parametrically lower than the lowest-frequency mode of a classical BH and whose damping times are parametrically longer. The reason for the appearance of the new modes is that our model contains another scale, the string length, which is parametrically larger than the Planck length. This distinction between the collapsed-polymer model and general-relativistic BHs could be made with gravitational-wave observations and offers a means for potentially measuring the strength of the coupling in string theory. For example, GW150914 already allows us to probe the strength of the string coupling near the regime which is predicted by the unification of the gravitational and gauge-theory couplings. We also derive bounds on the amplitude of the collapsed-polymer QNMs that can be placed by current and future gravitational-wave observations.

The simultaneous creation of multiple electron-positron pairs by localized strong electric fields is studied by utilizing a time- and space-resolved quantum field theory approach. It is demonstrated that the number of simultaneously created pairs equals the number of the potential’s supercritical quasibound states in the Dirac sea. This means it can be controlled by tuning the potential parameters. Furthermore, the energy of the created particles corresponds to the energy of the supercritical quasibound states. The simultaneously created electrons and positrons are statistically correlated, which is reflected in the spatial distribution and the momentum distribution of these particles and antiparticles.

Sterile neutrinos, if they exist, are potential harbingers for physics beyond the Standard Model. They have the capacity to shed light on our flavor sector, grand unification frameworks, dark matter sector and origins of baryon antibaryon asymmetry. There have been a few seminal studies that have broached the subject of sterile neutrinos with low, electroweak-scale masses (i.e. ${\mathrm{\Lambda }}_{\mathrm{QCD}}\ll m_{N_R}\ll m_{W^{\pm }}$) and investigated their reach at hadron colliders using lepton jets. These preliminary studies nevertheless assume background-free scenarios after certain selection criteria which are overly optimistic and untenable in realistic situations. These lead to incorrect projections. The unique signal topology and challenging hadronic environment also make this mass-scale regime ripe for a careful investigation. With the above motivations, we attempt to perform the first systematic study of low, electroweak-scale, right-handed neutrinos at hadron colliders, in this unique signal topology. There are currently no active searches at hadron colliders for sterile neutrino states in this mass range, and we frame the study in the context of the 13 TeV high-luminosity Large Hadron Collider and the proposed FCC-hh/SppC 100 TeV $pp$-collider.

We find a set of necessary and sufficient conditions for the $CP$ conservation in the most general 2HDM in terms of observable quantities. This set contains two simple and relatively easily testable conditions instead of the more complex conditions usually discussed.

The refined Gribov-Zwanziger framework takes into account the existence of equivalent gauge field configurations in the gauge-fixing quantization procedure of Euclidean Yang-Mills theories. Recently, this setup was extended to the family of linear covariant gauges giving rise to a local and Becchi-Rouet-Stora-Tyutin (BRST)-invariant action. In this paper, we give an algebraic proof of the renormalizability of the resulting action to all orders in perturbation theory.

We present analytic parametrizations for the ${\gamma }^{*}N\to N(1440)$ form factors derived from light-front holography in leading twist approximation. The new parametrizations describe the electromagnetic form factors using analytic functions dependent on the masses of the $\rho$ meson and respective radial excitations, as well as the masses of the nucleon and the resonance $N(1440)$. The free parameters of the model, associated with three independent couplings, are interpreted as bare couplings, and are fixed by the nucleon data for large $Q^2$. The proposed parametrizations compare remarkably well with the empirical data for $Q^2>2{\mathrm{GeV}}^2$, corroborating the dominant role of the valence quark degrees of freedom in the ${\gamma }^{*}N\to N(1440)$ transition.

We have searched for the Cabibbo-suppressed decay ${\mathrm{\Lambda }}_c^{+}\to \varphi p{\pi }^0$ in $e^{+}{e}^{-}$ collisions using a data sample corresponding to an integrated luminosity of $915{\mathrm{fb}}^{-1}$. The data were collected by the Belle experiment at the KEKB $e^{+}{e}^{-}$ asymmetric-energy collider running at or near the $\mathrm{\Upsilon }(4S)$ and $\mathrm{\Upsilon }(5S)$ resonances. No significant signal is observed, and we set an upper limit on the branching fraction of $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to \varphi p{\pi }^0)<15.3\times {10}^{-5}$ at 90% confidence level. The contribution of nonresonant ${\mathrm{\Lambda }}_c^{+}\to K^{+}{K}^{-}p{\pi }^0$ decays is found to be consistent with zero, and the corresponding upper limit on its branching fraction is set to be $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to K^{+}{K}^{-}p{\pi }^0{)}_{\mathrm{NR}}<6.3\times {10}^{-5}$ at 90% confidence level. We also search for an intermediate hidden-strangeness pentaquark decay $P_s^{+}\to \varphi p$. We see no evidence for this intermediate decay and set an upper limit on the product branching fraction of $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to P_s^{+}{\pi }^0)\times \mathcal{B}(P_s^{+}\to \varphi p)<8.3\times {10}^{-5}$ at 90% confidence level. Finally, we measure the branching fraction for the Cabibbo-favored decay ${\mathrm{\Lambda }}_c^{+}\to K^{-}{\pi }^{+}p{\pi }^0$; the result is $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to K^{-}{\pi }^{+}p{\pi }^0)=(4.42\pm 0.05(\text{stat})\pm 0.12(\text{syst})\pm 0.16(\text{norm}))\%$, which is the most precise measurement to date.

For a perturbation of the state of a conformal field theory (CFT), the response of the entanglement entropy is governed by the so-called “first law” of entanglement entropy, in which the change in entanglement entropy is proportional to the change in energy. Whether such a first law holds for other types of perturbations, such as a change to the CFT Lagrangian, remains an open question. We use holography to study the evolution in time $t$ of entanglement entropy for a CFT driven by a $t$-linear source for a conserved $U(1)$ current or marginal scalar operator. We find that although the usual first law of entanglement entropy may be violated, a first law for the rates of change of entanglement entropy and energy still holds. More generally, we prove that this first law for rates holds in holography for any asymptotically ($d+1$)-dimensional anti–de Sitter metric perturbation whose $t$ dependence first appears at order $z^d$ in the Fefferman-Graham expansion about the boundary at $z=0$.

Defining a new $r$-matrix compatible with the scalar product at the basis of the Chern-Simons action for a particle coupled to ($2+1$) Lorentzian gravity with cosmological constant, I show how deformed symmetries of $\kappa$-de Sitter and, in the vanishing cosmological limit, of $\kappa$-Poincaré kind, arise naturally as quantum deformation of three dimensional gravity. I obtain, moreover, the noncommutative spacetime associated with these kinds of symmetries.

Twist fields emerge in a number of physical applications ranging from entanglement entropy to scattering amplitudes in four-dimensional gauge theories. In this work, their vacuum expectation values are studied in the path integral framework. By performing a gauge transformation, their correlation functions are reduced to field theory of matter fields in external Aharonov-Bohm vortices. The resulting functional determinants are then analyzed within the zeta-function regularization for the spectrum of Bessel zeros, and concise formulas are derived.

Geodesic bulk diagrams were recently shown to be the geometric objects which compute global conformal blocks. We show that this duality continues to hold in $p$-adic $\mathrm{AdS}/\mathrm{CFT}$, where the bulk is replaced by the Bruhat–Tits tree, an infinite regular graph with no cycles, and the boundary is described by $p$-adic numbers, rather than reals. We apply the duality to evaluate the four-point function of scalar operators of generic dimensions using tree-level bulk diagrams. Relative to standard results from the literature, we find intriguing similarities as well as significant simplifications. Notably, all derivatives disappear in the conformal block decomposition of the four-point function. On the other hand, numerical coefficients in the four-point function as well as the structure constants take surprisingly universal forms, applicable to both the reals and the $p$-adics when expressed in terms of local zeta functions. Finally, we present a minimal bulk action with nearest neighbor interactions on the Bruhat–Tits tree, which reproduces the two-, three-, and four-point functions of a free boundary theory.

We explore the low-energy phenomenology of an F-theory-based $SU(5)$ model which, in addition to the known quarks and leptons, contains Standard Model (SM) singlets and vectorlike color triplets and $SU(2)$ doublets. Depending on their masses and couplings, some of these new particles may be observed at the LHC and future colliders. We discuss the restrictions by Cabibbo-Kobayashi-Maskawa matrix constraints on their mixing with the ordinary down quarks of the three chiral families. The model is consistent with gauge coupling unification at the usual supersymmetric GUT scale; dimension-five proton decay is adequately suppressed, while dimension-six decay mediated by the superheavy gauge bosons is enhanced by a factor of 5–7. The third generation charged fermion Yukawa couplings yield the corresponding low-energy masses in reasonable agreement with observations. The hierarchical nature of the masses of lighter generations is accounted for via nonrenormalizable interactions, with the perturbative vacuum expectation values (VEVs) of the SM singlet fields playing an essential role.

The critical exponent $\omega$ is evaluated at $O(1/N)$ in $d$ dimensions in the Gross-Neveu model using the large $N$ critical point formalism. It is shown to be in agreement with the recently determined three-loop $\beta$-functions of the Gross-Neveu-Yukawa model in four dimensions. The same exponent is computed for the chiral Gross-Neveu and non-Abelian Nambu–Jona-Lasinio universality classes.

In the context of scalar-tensor theories of gravity we compute the third-order corrected spectral indices in the slow-roll approximation. The calculation is carried out by employing the Green’s function method for scalar and tensor perturbations in both the Einstein and Jordan frames. Then, using the interrelations between the Hubble slow-roll parameters in the two frames we find that the frames are equivalent up to third order. Since the Hubble slow-roll parameters are related to the potential slow-roll parameters, we express the observables in terms of the latter which are manifestly invariant. Nevertheless, the same inflaton excursion leads to different predictions in the two frames since the definition of the number of $e$-folds differs. To illustrate this effect we consider a nonminimal inflationary model and find that the difference in the predictions grows with the nonminimal coupling, and it can actually be larger than the difference between the first and third order results for the observables. Finally, we demonstrate the effect of various end-of-inflation conditions on the observables. These effects will become important for the analyses of inflationary models in view of the improved sensitivity of future experiments.

Higher mass dimension terms in an effective field theory framework for tests of spacetime symmetries are studied. Using a post-Newtonian expansion method, we derive the spacetime metric and the equations of motion for a binary system. This reveals an effective inverse cubic force correction to post-Newtonian general relativity that depends on the velocity of the bodies in the system. The results are studied in the context of laboratory and space-based tests including the effects on solar-system ephemeris, laser ranging observations, and gravimeter tests. This work reveals the coefficient combinations for mass dimension 5 operators controlling $CPT$ violation for gravity that can be measured using analysis from these tests. Other tests including light propagation can be used to probe these coefficients. Sensitivity estimates are provided and the results are contrasted with the minimal mass dimension 4 terms in the gravity sector.

Some exact, nonlinear, vacuum gravitational wave solutions are derived for certain polynomial $f(R)$ gravities. We show that the boundaries of the gravitational domain of dependence, associated with events in polynomial $f(R)$ gravity, are not null as they are in general relativity. The implication is that electromagnetic and gravitational causality separate into distinct notions in modified gravity, which may have observable astrophysical consequences. The linear theory predicts that tachyonic instabilities occur, when the quadratic coefficient $a_2$ of the Taylor expansion of $f(R)$ is negative, while the exact, nonlinear, cylindrical wave solutions presented here can be superluminal for all values of $a_2$. Anisotropic solutions are found, whose wave fronts trace out time- or spacelike hypersurfaces with complicated geometric properties. We show that the solutions exist in $f(R)$ theories that are consistent with Solar System and pulsar timing experiments.

Under the commonly used spherical collapse model, we study how dark energy affects the growth of large scale structures of the Universe in the context of agegraphic dark energy models. The dynamics of the spherical collapse of dark matter halos in nonlinear regimes is determined by the properties of the dark energy model. We show that the main parameters of the spherical collapse model are directly affected by the evolution of dark energy in the agegraphic dark energy models. We compute the spherical collapse quantities for different values of agegraphic model parameter $\alpha$ in two different scenarios: first, when dark energy does not exhibit fluctuations on cluster scales, and second, when dark energy inside the overdense region collapses similar to dark matter. Using the Sheth-Tormen and Reed mass functions, we investigate the abundance of dark matter halos in the framework of agegraphic dark energy cosmologies. The model parameter $\alpha$ is a crucial parameter in order to count the abundance of dark matter halos. Specifically, the present analysis suggests that the agegraphic dark energy model with a bigger (smaller) value of $\alpha$ predicts less (more) virialized halos with respect to that of $\mathrm{\Lambda }\mathrm{CDM}$ cosmology. We also show that in agegraphic dark energy models, the number of halos strongly depends on clustered or uniformed distributions of dark energy.

Semileptonic transitions $\overline{B}\to D^{(n)}\ell \overline{\nu }$, where $D^{(n)}(n\ne 0)$ is a radially excited meson, have recently attracted much attention as a way to understand some puzzles between theory and data. In the heavy quark limit the inelastic Isgur-Wise function vanishes at zero recoil, ${\xi }^{(n)}(1)=0(n\ne 0)$. We consider here the $1/m_Q$ corrections within heavy quark effective theory. We find simple formulas that involve the derivative of the inelastic IW function at $w=1$, ${\xi }^{(n{)}^{\prime }}(1)(n\ne 0)$. We propose a number of ways of isolating this important quantity in practice, with emphasis on lattice QCD. We formulate also a generalization to the inelastic case of Luke’s theorem.

In this work, we consider the process $e^{+}+e^{-}\to b\overline{b}+{\cancel{E}}_T$, at the future electron-positron colliders such as the International Linear Collider and Compact Linear Collider, to look for the dark matter (DM) effect and identify its nature at two different center-of-mass energies $E_{\mathrm{c}.\mathrm{m}.}=500\mathrm{GeV}$ and 1 TeV. For this purpose, we take two extensions of the standard model, in which the DM could be a real scalar or a heavy right-handed neutrino (RHN) similar to many models motivated by neutrino mass. In the latter extension, the charged leptons are coupled to the RHNs via a lepton flavor violating interaction that involves a charged singlet scalar. After discussing different constraints, we define a set of kinematical cuts that suppress the background and generate different distributions that are useful in identifying the DM nature. The use of polarized beams (like the polarization $P(e^{-},e^{+})=[+0.8,-0.3]$ at the International Linear Collider) makes the signal detection easier and the DM identification more clear, where the statistical significance gets enhanced by twice (five times) for scalar (RHN) DM.