In [Phys. Rev. D 90, 043006 (2014)], we proposed a new ghost-free massive spin-two model in flat spacetime. Furthermore, as some extension, we coupled the new model with a nondynamical curved background in [Phys. Rev. D 90, 123013 (2014)] and constructed new interaction terms without the appearance of an extra mode. The characteristic property of the new model is the existence of nonlinear potential terms which give the nontrivial vacua. The presence of the nontrivial vacua, however, does not mean that the particle can be defined around all vacua. Therefore, in this paper, we discuss the conditions for the new model to have stable vacua in flat spacetime and curved spacetime. Then, we couple this spin-two theory with a dynamical background and obtain the solutions. Moreover, we investigate the effect of this new spin-two model on the Einstein gravity by calculating the black hole entropy, since the gravity coupled with massive spin-two theory admits a black hole solution in addition to the (anti-)de Sitter space solution.

We consider the minimal $\mathrm{U}(1{)}^{\prime }$ extension of the standard model (SM) with conformal invariance at the classical level, where in addition to the SM particle contents, three generations of right-handed neutrinos and a $\mathrm{U}(1{)}^{\prime }$ Higgs field are introduced. In the presence of the three right-handed neutrinos, which are responsible for the seesaw mechanism, this model is free from all the gauge and gravitational anomalies. The $\mathrm{U}(1{)}^{\prime }$ gauge symmetry is radiatively broken via the Coleman-Weinberg mechanism, by which the $\mathrm{U}(1{)}^{\prime }$ gauge boson ($Z^{\prime }$ boson) mass as well as the Majorana mass for the right-handed neutrinos are generated. The radiative $\mathrm{U}(1{)}^{\prime }$ symmetry breaking also induces a negative mass squared for the SM Higgs doublet to trigger the electroweak symmetry breaking. In this context, we investigate a possibility to solve the SM Higgs vacuum instability problem. The model includes only three free parameters ($\mathrm{U}(1{)}^{\prime }$ charge of the SM Higgs doublet, $\mathrm{U}(1{)}^{\prime }$ gauge coupling and $Z^{\prime }$ boson mass), for which we perform parameter scan, and identify a parameter region resolving the SM Higgs vacuum instability. We also examine naturalness of the model. The heavy states associated with the $\mathrm{U}(1{)}^{\prime }$ symmetry breaking contribute to the SM Higgs self-energy. We find an upper bound on $Z^{\prime }$ boson mass, $m_{Z^{\prime }}\lesssim 6\mathrm{TeV}$, in order to avoid a fine-tuning severer than 10% level. The $Z^{\prime }$ boson in this mass range can be discovered at the LHC Run-2 in the near future.

We study the semileptonic $B_s$ and $B$ decays into the $D_{s0}^{*}(2317)$ and $D_0^{*}(2400)$ resonances, respectively. With the help of a chiral unitarity model in coupled channels we compute the ratio of the decay widths of both processes. Using current values of the width for the ${\overline{B}}^0\to D_0^{*}(2400{)}^{+}{\overline{\nu }}_l{l}^{-}$ we make predictions for the rate of the ${\overline{B}}_s^0\to D_{s0}^{*}(2317{)}^{+}{\overline{\nu }}_l{l}^{-}$ decay and for the $DK$ invariant mass distribution in the ${\overline{B}}_s^0\to DK{\overline{\nu }}_l{l}^{-}$ decay.

We make a detailed eikonal fit to current data on the total and elastic scattering cross sections, the ratios $\rho$ of the real to the imaginary parts of the forward elastic scattering amplitudes, and the logarithmic slopes $B$ of the differential cross sections $d\sigma /dt$ at $t=0$, for proton-proton and antiproton-proton scattering at center-of-mass energies $W$ from 5 GeV to 57 TeV. The fit allows us to investigate the structure of the eikonal amplitudes in detail, including the impact-parameter structure of the energy-independent edge in the scattering amplitude shown to exist by Block et al., [Phys. Rev. D 91, 011501(R) (2015)]. We show that the edge region has an essentially fixed shape with a peak at approximately the “black disk” radius $R_{\mathrm{tot}}=\sqrt{{\sigma }_{\mathrm{tot}}/2\pi }$ of the scattering amplitude, a constant width $t_{\text{edge}}\approx 1\mathrm{fm}$, and migrates to larger impact parameters with increasing energy proportionally to $R_{\mathrm{tot}}$. We comment on possible physical mechanisms which could lead to the edge. We show that the eikonal results for the cross sections and $\rho$ values are described to high accuracy by analytic expressions of the forms used in earlier analyses by Block and Halzen, and extend the result to the elastic-scattering slope parameter $B$. These expressions provide simple extrapolations of the results to much higher energies where the cross sections approach the black disk limit with ${\sigma }_{\text{elas}}$, ${\sigma }_{\text{inel}}\to {\sigma }_{\mathrm{tot}}/2$ and $B\to {\sigma }_{\mathrm{tot}}/8\pi$. Finally, we calculate the survival probabilities for large rapidity gaps in the scattering.

Lattice QCD simulations provide a promising way to disentangle different interpretations of hadronic resonances, which might be of particular relevance to understand the nature of the so-called $XYZ$ particles. Recent studies have shown that in addition to the well-established naive quark model picture, the axial-vector meson $f_1(1285)$ can also be understood as a dynamically generated state built upon the $K{K}^{*}$ interaction. In this work, we calculate the energy levels of the $K{K}^{*}$ system in the $f_1(1285)$ channel in finite volume using the chiral unitary approach. We propose to calculate the loop function in the dimensional regularization scheme, which is equivalent to the hybrid approach adopted in previous studies. We also study the inverse problem of extracting the bound state information from synthetic lattice QCD data and comment on the difference between our approach and the Lüscher method.

We apply (fractional) analytic perturbation theory (FAPT) to the QCD analysis of the nonsinglet nucleon structure function $F_2(x,Q^2)$ in deep inelastic scattering up to the next leading order and compare the results with ones obtained within the standard perturbation QCD. Based on a popular parametrization of the corresponding parton distribution we perform the analysis within the Jacobi polynomial formalism and under the control of the numerical inverse Mellin transform. To reveal the main features of the FAPT two-loop approach, we consider a wide range of momentum transfer from high $Q^2\sim 100{\mathrm{GeV}}^2$ to low $Q^2\sim 0.3{\mathrm{GeV}}^2$ where the approach still works.

We present a quantitative study of the $\nu N$ cross section in the neutrino energy range ${10}^4<E_{\nu }<{10}^{14}\mathrm{GeV}$ within two transversal QCD approaches: next-to-leading-order Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution using different sets of parton distribution functions and Balitsky-Kovchegov (BK) small-$x$ evolution with running coupling and kinematical corrections. We show that the nonlinear effects embodied in the BK equation yield a slower raise in the cross section for $E_{\nu }\gtrsim {10}^8\mathrm{GeV}$ than the usual DGLAP-based calculation. Finally, we translate this theoretical uncertainty into upper bounds for the ultrahigh-energy neutrino flux for different experiments.

I obtain the complex pole squared mass of the $Z$ boson at full two-loop order in the Standard Model in the pure $\overline{\mathrm{MS}}$ renormalization scheme. The input parameters are the running gauge couplings, the top-quark Yukawa coupling, the Higgs self-coupling, and the vacuum expectation value that minimizes the Landau gauge effective potential. The effects of nonzero Goldstone boson mass are resummed. Within a reasonable range of renormalization scale choices, the scale dependence of the computed pole mass is found to be comparable to the current experimental uncertainty, but the true theoretical error is likely somewhat larger.

We perform a new analysis of electron-proton scattering data to determine the proton electric and magnetic radii, enforcing model-independent constraints from form factor analyticity. A wide-ranging study of possible systematic effects is performed. An improved analysis is developed that rebins data taken at identical kinematic settings and avoids a scaling assumption of systematic errors with statistical errors. Employing standard models for radiative corrections, our improved analysis of the 2010 Mainz A1 Collaboration data yields a proton electric radius $r_E=0.895(20)\mathrm{fm}$ and magnetic radius $r_M=0.776(38)\mathrm{fm}$. A similar analysis applied to world data (excluding Mainz data) implies $r_E=0.916(24)\mathrm{fm}$ and $r_M=0.914(35)\mathrm{fm}$. The Mainz and world values of the charge radius are consistent, and a simple combination yields a value $r_E=0.904(15)\mathrm{fm}$ that is $4\sigma$ larger than the CREMA Collaboration muonic hydrogen determination. The Mainz and world values of the magnetic radius differ by $2.7\sigma$, and a simple average yields $r_M=0.851(26)\mathrm{fm}$. The circumstances under which published muonic hydrogen and electron scattering data could be reconciled are discussed, including a possible deficiency in the standard radiative correction model which requires further analysis.

We propose a strategy for new physics searches in channels which contain a boosted $Z$ boson and a boosted massive jet in the final state. Our proposal exploits the previously overlooked advantages of boosted $Z\to \nu \overline{\nu }$ topologies, where collimated neutrinos result in signals with large missing energy. We illustrate the advantage of this channel in a case study of singly produced TeV scale charge $2/3$ fermionic top partners ($T^{\prime }$) which decay to $tZ$ final states. A comparison with the di-leptonic channel reveals that, despite the large $t\overline{t}$ background, signals with missing energy combined with jet substructure techniques offer superior probes of new physics at TeV scales. The effect can be attributed to a factor of $\sim 3$ enhancement in the signal cross section, coming from the branching ratio of $Z\to \nu \overline{\nu }$. We exploit the unique event topology of singly produced top partners to suppress the $t\overline{t}$ background, as well as further improve on the existing proposals to detect $T^{\prime }$ in the boosted di-lepton channel. Our conclusions on advantages of $Z\to \nu \overline{\nu }$ can be extended to most resonance searches which utilize a boosted $Z$ boson in the final state.

The sum of active neutrino masses is well constrained, $58\mathrm{meV}\le m_{\nu }\lesssim 0.23\mathrm{eV}$, but the origin of this scale is not well understood. Here we investigate the possibility that it arises by environmental selection in a large landscape of vacua. Earlier work noted the detrimental effects of neutrinos on large-scale structure. However, using Boltzmann codes to compute the smoothed density contrast on Mpc scales, we find that dark matter halos form abundantly for $m_{\nu }\gtrsim 10\mathrm{eV}$. This finding rules out an anthropic origin of $m_{\nu }$, unless a different catastrophic boundary can be identified. Here we argue that galaxy formation becomes inefficient for $m_{\nu }\gtrsim 10\mathrm{eV}$. We show that in this regime, structure forms late and is dominated by cluster scales, as in a top-down scenario. This is catastrophic: baryonic gas will cool too slowly to form stars in an abundance comparable to our Universe. With this novel cooling boundary, we find that the anthropic prediction for $m_{\nu }$ agrees at better than $2\sigma$ with current observational bounds. A degenerate hierarchy is mildly preferred.

Breather-type (time-periodic and spatially localized) solutions with spherical symmetry are investigated in a massless scalar field theory coupled to Einstein’s gravity with cosmological constant in $d$ spatial dimensions imposing anti–de Sitter (AdS) asymptotics on space-time. Using a code constructed with the Kadath library that enables the use of spectral methods, the phase space of breather solutions is explored in detail for $d=3$ and $d=4$. It is found that there are discrete families of solutions indexed by an integer and by their frequency. Using a time evolution code these AdS breathers are found to be stable for up to a critical central density, in analogy to boson stars. Using an analytical perturbative expansion small amplitude breathers are worked out for arbitrary dimensions $d$.

In this paper we study the polarized vacuum energy on the conducting surface of a topological insulator characterized by both $Z_2$ topological index and time reversal symmetry. This boundary is subject to the action of a static and spatially homogeneous magnetic field perpendicular to it as well as of an electric field that is uniform near the considered surface and produced by a biased voltage, at zero temperature. To do this, we consider modifications in the Gauss law that arise due to the nonzero gradient of the axionlike pseudoscalar factor coupled to the applied magnetic field, which accounts for the topological properties of the system. Such a term allows us to find a correction to the induced charges which modifies the quantum vacuum of the spinor field regarding an ordinary surface. The polarized vacuum energy is calculated in both the weak-field approximation and in the general case, and since the found energy depends on a length defined on the boundary, we show that there is a radial density of force or a surface shear stress that tends to shrink it.

In this paper we extend the analysis of gravitational collapse of spherically symmetric generalized Vaidya spacetimes to higher dimensions, in the context of the cosmic censorship conjecture. We present the sufficient conditions on the generalized Vaidya mass function that will generate a locally naked singular end state. Our analysis here generalizes all the earlier works on collapsing higher dimensional generalized Vaidya spacetimes. With specific examples, we show the existence of classes of mass functions that lead to a naked singularity in four dimensions, which gets covered on transition to higher dimensions. Hence for these classes of mass function cosmic censorship gets restored in higher dimensions and the transition to higher dimensions restricts the set of initial data that results in a naked singularity.

We present a class of exact solutions in the framework of $(2+1)$-dimensional Einstein gravity coupled minimally to a doublet of scalar fields. Our solution can be interpreted upon the tuning of parameters as an asymptotically flat wormhole as well as a particle model in $2+1$ dimensions.

We pursue a class of visible axion models where the axion mass is enhanced by strong dynamics in a mirrored copy of the Standard Model in the line of the idea put forward by Rubakov. In particular, we examine the consistency of the models with laboratory, astrophysical, and cosmological constraints. As a result, viable parameter regions are found, where the mass of the axion is of $O(100)\mathrm{MeV}$ or above while the Peccei-Quinn breaking scale is at around ${10}^{3–5}\mathrm{GeV}$.

Within the framework of nonrelativisitic QCD factorization formalism, we present the next-to-leading-order relativistic corrections to $\mathrm{\Upsilon }$ exclusive decay into ${\eta }_c$ plus $J/\psi$. The double charmonia can be produced through several immediate channels, i.e., $\mathrm{\Upsilon }\to g^{*}{g}^{*}{g}^{*}\to {\eta }_c+J/\psi$, $\mathrm{\Upsilon }\to g^{*}{g}^{*}{\gamma }^{*}\to {\eta }_c+J/\psi$, and $\mathrm{\Upsilon }\to {\gamma }^{*}\to {\eta }_c+J/\psi$. The amplitudes of these three channels are obtained accurate up to $\mathcal{O}({\alpha }_s^3{v}^2)$, $\mathcal{O}(\alpha {\alpha }_s^2{v}^2)$, and $\mathcal{O}(\alpha {\alpha }_s^2{v}^2)$, respectively, where $v$ indicates the typical heavy quark velocity in bottomonium and/or charmonium rest frame. The decay rates are also presented. We find that the next-to-leading-order relativistic corrections to the short-distance coefficients as well as the decay rates are both significant and negative, especially for the corrections from bottomonium. More seriously, the decay rates are even brought into negative by including the relativistic corrections, which indicates the poor convergence for the velocity expansion in this kind of process. Detailed analysis is given in the paper.

The symmetric orbifold of K3 is believed to be the conformal field theory (CFT) dual of string theory on ${\mathrm{AdS}}_3\times {\mathrm{S}}^3\times \mathrm{K}3$ at the tensionless point. For the case when the K3 is described by the orbifold ${\mathbb{T}}^4/{\mathbb{Z}}_2$, we identify a subsector of the symmetric orbifold theory that is dual to a higher spin theory on ${\mathrm{AdS}}_3$. We analyze how the Bogomol’nyi-Prasad-Sommerfield (BPS) spectrum of string theory can be described from the higher spin perspective and determine which single-particle BPS states are accounted for by the perturbative higher spin theory.

We show that the universal $\alpha$-attractor models of inflation can be realized by including an auxiliary vector field $A_{\mu }$ for the Starobinsky model with the Lagrangian $f(R)=R+R^2/(6M^2)$. If the same procedure is applied to general modified $f(R)$ theories in which the Ricci scalar $R$ is replaced by $R+A_{\mu }{A}^{\mu }+\beta {\nabla }_{\mu }{A}^{\mu }$ with constant $\beta$, we obtain the Brans-Dicke theory with a scalar potential and the Brans-Dicke parameter ${\omega }_{\mathrm{BD}}={\beta }^2/4$. We also place observational constraints on inflationary models based on auxiliary vector modified $f(R)$ theories from the latest Planck measurements of the cosmic microwave background anisotropies in both temperature and polarization. In the modified Starobinsky model, we find that the parameter $\beta$ is constrained to be $\beta <25$ (68% confidence level) from the bounds of the scalar spectral index and the tensor-to-scalar ratio.

We give updated constraints on hypothetical light bosons with a two-photon coupling such as axions or axion-like particles (ALPs). We focus on masses and lifetimes where decays happen near big bang nucleosynthesis (BBN), thus altering the baryon-to-photon ratio and number of relativistic degrees of freedom between the BBN epoch and the cosmic microwave background’s (CMB) last scattering epoch, in particular such that $N_{\text{eff}}^{\mathrm{CMB}}<N_{\text{eff}}^{\mathrm{BBN}}$ and ${\eta }^{\mathrm{CMB}}<{\eta }^{\mathrm{BBN}}$. New constraints presented here come from Planck measurements of the CMB power spectrum combined with the latest inferences of primordial ${}^4\mathrm{He}$ and D/H abundances. We find that a previously allowed region in parameter space near $m=1\mathrm{MeV}$ and $\tau =100\mathrm{ms}$, consistent with a QCD axion arising from a symmetry breaking near the electroweak scale, is now ruled out at $>3\sigma$ by the combination of $\mathrm{CMB}+D/H$ measurements if only ALPs and three thermalized neutrino species contribute to $N_{\text{eff}}$. The bound relaxes if there are additional light degrees of freedom present which, in this scenario, have their contribution limited to $\mathrm{\Delta }{N}_{\text{eff}}=1.1\pm 0.3$. We give forecasts showing that a number of experiments are expected to reach the sensitivity needed to further test this region, such as Stage-IV CMB and SUPER-KEKB, the latter a direct test insensitive to any extra degrees of freedom.