We derive dispersion relations for the electroweak oblique observables measured at LEP in the context of $SO(5)/SO(4)$ composite Higgs models. We show how these relations can be used and must be modified when modeling the spectral functions through a low-energy effective description of the strong dynamics. We then use the dispersion relation for the parameter ${\epsilon }_3$ to estimate the contribution from spin-1 resonances at the one-loop level. Finally, we show that the sign of the contribution to the $\widehat{S}$ parameter from the lowest-lying spin-1 states is not necessarily positive definite but depends on the energy scale at which the asymptotic behavior of current correlators is attained.

In the search for the bottom squark (sbottom) in supersymmetry (SUSY) at the LHC, the common practice has been to assume a 100% decay branching fraction for a given search channel. In realistic minimal supersymmetric Standard Model scenarios, there are often more than one significant decay modes to be present, which significantly weaken the current sbottom search limits at the LHC. On the other hand, the combination of the multiple decay modes offers alternative discovery channels for sbottom searches. In this paper, we present the sbottom decays in a few representative mass parameter scenarios. We then analyze the sbottom signal for the pair production in QCD with one sbottom decaying via $\tilde{b}\to b{\chi }_1^0$, $b{\chi }_2^0$, and the other one decaying via $\tilde{b}\to t{\chi }_1^{\pm }$. With the gaugino subsequent decaying to gauge bosons or a Higgs boson ${\chi }_2^0\to Z{\chi }_1^0$, $h{\chi }_1^0$ and ${\chi }_1^{\pm }\to W^{\pm }{\chi }_1^0$, we study the reach of those signals at the 14 TeV LHC with $300{\mathrm{fb}}^{-1}$ integrated luminosity. For a left-handed bottom squark, we find that a mass up to 920 GeV can be discovered at $5\sigma$ significance for $250\mathrm{GeV}<m_{{\chi }_1^0}<350\mathrm{GeV}$, or excluded up to 1050 GeV at the 95% confidence level for the $h$ channel ($\mu >0$); similarly, it can be discovered up to 840 GeV, or excluded up to 900 GeV at the 95% confidence level for the $Z$ channel ($\mu <0$). The top squark reach is close to that of the bottom squark. The sbottom and stop signals in the same SUSY parameter scenario are combined to obtain the optimal sensitivity, which is about 150 GeV better than the individual reach of the sbottom or stop. For a right-handed bottom squark with the $\tilde{b}{\tilde{b}}^{*}\to b{\chi }_1^0$, $t{\chi }_1^{\pm }$ channel, we find that the sbottom mass up to 880 GeV can be discovered at $5\sigma$ significance, or excluded up to 1060 GeV at the 95% confidence level.

We calculate second- and fourth-order cumulants of conserved charges in a temperature range stretching from the QCD transition region towards the realm of (resummed) perturbation theory. We perform lattice simulations with staggered quarks; the continuum extrapolation is based on $N_t=10–24$ in the crossover region and $N_t=8–16$ at higher temperatures. We find that the hadron resonance gas model predictions describe the lattice data rather well in the confined phase. At high temperatures (above $\sim 250\mathrm{MeV}$) we find agreement with the three-loop hard thermal loop results.

We present a first analysis of parton-to-pion fragmentation functions at next-to-next-to-leading order accuracy in QCD based on single-inclusive pion production in electron-positron annihilation. Special emphasis is put on the technical details necessary to perform the QCD scale evolution and cross section calculation in Mellin moment space. We demonstrate how the description of the data and the theoretical uncertainties are improved when next-to-next-to-leading order QCD corrections are included.

In this work we investigate the entropic information measure in the context of braneworlds with nonconstant curvature. The braneworld entropic information is studied for gravity modified by the square of the Ricci scalar, besides the usual Einstein-Hilbert term. We showed that the minimum value of the brane configurational entropy provides a stricter bound on the parameter that is responsible for the $F(R)$ model differing from the Einstein-Hilbert standard one. Our results are moreover consistent to a negative bulk cosmological constant.

We develop an effective Gauss-Bonnet extension of loop quantum cosmology, by introducing holonomy corrections in modified $F(\mathcal{G})$ theories of gravity. Within the context of our formalism, we provide a perturbative expansion in the critical density, a parameter characteristic of loop quantum gravity theories, and we result in having leading order corrections to the classical $F(\mathcal{G})$ theories of gravity. After extensively discussing the formalism, we present a reconstruction method that makes it possible to find the loop quantum cosmology corrected $F(\mathcal{G})$ theory that can realize various cosmological scenarios. We exemplify our theoretical constructions by using bouncing cosmologies, and we investigate which loop quantum cosmology corrected Gauss-Bonnet modified gravities can successfully realize such cosmologies.

The Euclidean opening angle at the $r-t_E$ surface, ${\mathrm{\Theta }}_{r-t_E}$ at the horizon of a black hole, is canonically conjugate to the black hole entropy. We prove that for a $D1D5$ black hole there exists in addition to this pair, another canonical pair: the opening angle at the $r-y$ surface, ${\mathrm{\Theta }}_{r-y}$, and a Wald-like term $S_{Wr-y}$. This leads to an uncertainty at ${\mathrm{\Theta }}_{r-y}$ which suggests that the surface $r-y$ is actually a superposition of surfaces with different conical singularities. This corresponds to the same type of singularities obtained by string theory excitations of a $D1D5$ black hole.

Unlike crushing singularities, the so-called type IV finite time singularity offers the possibility that the Universe passes smoothly it, without any catastrophic effects. Then the question is if the effects of a type IV singularity can be detected in the process of cosmic evolution. In this paper we address this question in the context of $F(R)$ gravity. As we demonstrate, the effects of a type IV singularity appear in the Hubble flow parameters, which determine the dynamical evolution of the cosmological system. So we study various inflation models incorporating a type IV singularity, with the singularity occurring at the end of inflation. Particularly we study a toy model and a singular version of the $R^2$ gravity Hubble rate. As we evince, some of the Hubble flow parameters become singular at the singularity, an effect which indicates that at that point a dynamical instability occurs. This dynamical instability eventually indicates the graceful exit from inflation. We demonstrate that the toy model has an unstable de Sitter point at the singularity, so indeed graceful exit could be triggered. In the case of the singular inflation model, graceful exit proceeds in the standard way. In addition, we investigate how the form of the $F(R)$ gravity affects the singularity structure of the Hubble flow parameters. In the case of the singular inflation model, we found various scenarios for singular evolution, most of which are compatible with observations, and only one leads to severe instabilities. In addition, in one of these scenarios, the presence of the type IV singularity slightly modifies the spectral index of primordial curvature perturbations. We also compare the ordinary Starobinsky with the singular inflation model, and we point out the qualitative and quantitative differences. Finally, we study the late-time dynamics of the toy model and of the singular inflation model and we demonstrate that the unification of early and late-time acceleration can be achieved. We also show that it is possible to achieve late-time acceleration similar to the $\mathrm{\Lambda }$-cold dark matter model.

There is a growing interest in modified gravity theories based on torsion, as these theories exhibit interesting cosmological implications. In this work inspired by the teleparallel formulation of general relativity, we present its extension to Lovelock gravity known as the most natural extension of general relativity in higher-dimensional space-times. First, we review the teleparallel equivalent of general relativity and Gauss-Bonnet gravity, and then we construct the teleparallel equivalent of Lovelock gravity. In order to achieve this goal, we use the vielbein and the connection without imposing the Weitzenböck connection. Then, we extract the teleparallel formulation of the theory by setting the curvature to null.

We present a new effective-one-body (EOB) Hamiltonian with next-to-leading order (NLO) spin-spin coupling for black hole binaries endowed with arbitrarily oriented spins. The Hamiltonian is based on the model for parallel spins and equatorial orbits developed in [Physical Review D 90, 044018 (2014)] but differs from it in several ways. In particular, the NLO spin-spin coupling is not incorporated by a redefinition of the centrifugal radius $r_c$ but by separately modifying certain sectors of the Hamiltonian, which are identified according to their dependence on the momentum vector. The gauge-fixing procedure we follow allows us to reduce the 25 different terms of the NLO spin-spin Hamiltonian in Arnowitt–Deser–Misner coordinates to only nine EOB terms. This is an improvement with respect to the EOB model recently proposed in [Physical Review D 91, 064011 (2015)], where 12 EOB terms were involved. Another important advantage is the remarkably simple momentum structure of the spin-spin terms in the effective Hamiltonian, which is simply quadratic up to an overall square root. Moreover, a Damour–Jaranowski–Schäfer-type gauge could be established, thus allowing one to concentrate, in the case of circular and equatorial orbits, the whole spin-spin interaction in a single radial potential.

We analyze constraints on parameters characterizing the preinflating universe in an open inflation model with a present slightly open $\mathrm{\Lambda }\mathrm{CDM}$ universe. We employ an analytic model to show that for a broad class of inflation-generating effective potentials, the simple requirement that some fraction of the observed dipole moment represents a preinflation isocurvature fluctuation allows one to set upper and lower limits on the magnitude and wavelength scale of preinflation fluctuations in the inflaton field, and the curvature of the preinflation universe, as a function of the fraction of the total initial energy density in the inflaton field as inflation begins. We estimate that if the preinflation contribution to the current cosmic microwave background (CMB) dipole is near the upper limit set by the Planck Collaboration then the current constraints on $\mathrm{\Lambda }\mathrm{CDM}$ cosmological parameters allow for the possibility of a significantly open ${\mathrm{\Omega }}_i\le 0.4$ preinflating universe for a broad range of the fraction of the total energy in the inflaton field at the onset of inflation. This limit to ${\mathrm{\Omega }}_i$ is even smaller if a larger dark-flow tilt is allowed.

We investigate the growth of matter fluctuations in holographic dark energy cosmologies. First, we use an overall statistical analysis involving the latest observational data in order to place constraints on the cosmological parameters. Then we test the range of validity of the holographic dark energy models at the perturbation level and its variants from the concordance $\mathrm{\Lambda }$ cosmology. Specifically, we provide a new analytical approach in order to derive, for the first time, the growth index of matter perturbations. Considering a homogeneous holographic dark energy, we find that the growth index is $\gamma \approx \frac{4}{7}$ which is somewhat larger ($\sim 4.8\%$) than that of the usual $\mathrm{\Lambda }$ cosmology, ${\gamma }^{(\mathrm{\Lambda })}\approx \frac{6}{11}$. Finally, if we allow clustering in the holographic dark energy models, then the asymptotic value of the growth index is given in terms of the effective sound speed $c_{\mathrm{eff}}^2$, namely, $\gamma \approx \frac{3(1-c_{\mathrm{eff}}^2)}{7}$.

Model-independent methods in cosmology have become an essential tool to deal with an increasing number of theoretical alternatives for explaining the late-time acceleration of the Universe. In principle, this provides a way of testing the cosmological concordance (or $\mathrm{\Lambda }\mathrm{CDM}$) model under different assumptions and ruling out whole classes of competing theories. One such model-independent method is the so-called “cosmographic approach”, which relies only on the homogeneity and isotropy of the Universe on large scales. We show that this method suffers from many shortcomings, providing biased results depending on the auxiliary variable used in the series expansion, and is unable to rule out models or adequately reconstruct theories with higher-order derivatives in either the gravitational or matter sector. Consequently, in its present form, this method seems unable to provide reliable or useful results for cosmological applications.

We investigate the double Higgs production and decay at the 14 TeV LHC and 33 TeV HE-LHC in both the standard model (SM) and Randall-Sundrum (RS) model. In our calculation we consider reasonably only the contribution of the lightest two Kaluza-Klein (KK) gravitons. We present the integrated cross sections and some kinematic distributions in both models. Our results show that the RS effect in the vicinities of $M_{HH}\sim M_1$, $M_2$ (the masses of the lightest two KK gravitons) or in the central Higgs rapidity region is quite significant, and can be extracted from the heavy SM background by imposing proper kinematic cuts on final particles. We also study the dependence of the cross section on the RS model parameters, the first KK graviton mass $M_1$, and the effective coupling $c_0$, and find that the RS effect is reduced obviously with the increment of $M_1$ or decrement of $c_0$.

Gravitino dark matter (DM) represents a compelling scenario in supersymmetry (SUSY), which brings together a variety of data from cosmology and collider physics. We discuss the constraints obtained from the LHC on supersymmetric models with gravitino dark matter and the neutralino next-to-lightest SUSY particle, which is the case most difficult to disentangle at colliders from a neutralino lightest SUSY particle forming DM. The phenomenological SUSY model with $19+1$ free parameters is adopted. Results are obtained from broad scans of the phase space of these uncorrelated parameters. The relation between gravitino mass, gluino mass and reheating temperature as well as the derived constraints on these parameters are discussed in detail. This relation offers a unique opportunity to place stringent bounds on the cosmological model, within the gravitino dark matter scenario, from the results of the LHC searches in run-2 and the planned high-luminosity upgrade.

We discuss spectra of gravitational waves which are originated by the strongly first order phase transition at the electroweak symmetry breaking, which is required for a successful scenario of electroweak baryogenesis. Such spectra are numerically evaluated without high temperature expansion in a set of extended scalar sectors with additional $N$ isospin-singlet fields as a concrete example of renormalizable theories. We find that the produced gravitational waves can be significant, so that they are detectable at future gravitational wave interferometers such as DECIGO and BBO. Furthermore, since the spectra strongly depend on $N$ and the mass of the singlet fields, our results indicate that future detailed observation of gravitational waves can be in general a useful probe of extended scalar sectors with the first order phase transition.

The chiral extrapolation of the $X(3872)$ binding energy is investigated using the modified Weinberg formulation of chiral effective field theory for the $D{\overline{D}}^{*}$ scattering. Given its explicit renormalizability, this approach is particularly useful to explore the interplay of the long- and short-range $D{\overline{D}}^{*}$ forces in the $X(3872)$ from studying the light-quark (pion) mass dependence of its binding energy. In particular, the parameter-free leading-order calculation shows that the $X$ pole disappears for unphysically large pion masses. On the other hand, without contradicting the naive dimensional analysis, the higher-order pion-mass-dependent contact interaction can change the slope of the binding energy at the physical point, yielding the opposite scenario of a more strongly bound $X$ at pion masses larger than its physical value. An important role of the pion dynamics and of the three-body $D\overline{D}\pi$ effects for chiral extrapolations of the $X$ pole is emphasized. The results of the present study should be of practical value for lattice simulations since they provide a nontrivial connection between lattice points at unphysical pion masses and the physical world.

The opacity of the Earth to incident ultrahigh energy neutrinos is directly connected with the behavior of the neutrino-nucleon (${\sigma }^{\nu N}$) cross sections in a kinematic range utterly unexplored. In this work we investigate how the uncertainties in ${\sigma }^{\nu N}$ due the different QCD dynamic models modify the neutrino absorption while they travel across the Earth. In particular, we compare the predictions of two extreme scenarios for the high energy behavior of the cross section, which are consistent with the current experimental data. The first scenario considered is based on the solution of the linear Dokshitzer-Gribov-Lipatov-Altarelli-Parisi equations at small $x$ and large $Q^2$, while the second one takes into account the unitarity effects in the neutrino-nucleon cross section by the imposition of the Froissart bound behavior in the nucleon structure functions at large energies. Our results indicate that the probability of absorption and the angular distribution of neutrino events are sensitive to the QCD dynamics at ultrahigh energies.

This paper reports a measurement by the T2K experiment of the ${\nu }_{\mu }$ charged current quasielastic (CCQE) cross section on a carbon target with the off-axis detector based on the observed distribution of muon momentum ($p_{\mu }$) and angle with respect to the incident neutrino beam (${\theta }_{\mu }$). The flux-integrated CCQE cross section was measured to be $⟨\sigma ⟩=(0.83\pm 0.12)\times {10}^{-38}{\mathrm{cm}}^2$. The energy dependence of the CCQE cross section is also reported. The axial mass, $M_A^{\mathrm{QE}}$, of the dipole axial form factor was extracted assuming the Smith-Moniz CCQE model with a relativistic Fermi gas nuclear model. Using the absolute (shape-only) $p_{\mu }\text{−}\cos {\theta }_{\mu }$ distribution, the effective $M_A^{\mathrm{QE}}$ parameter was measured to be $1.26_{-0.18}^{+0.21}\mathrm{GeV}/c^2$ ($1.43_{-0.22}^{+0.28}\mathrm{GeV}/c^2$).

In this paper, we propose a novel expansion to compute the large interval limit of the Rényi entropy of 2D conformal field theory (CFT) at high temperature. Via the replica trick, the single interval Rényi entropy of 2D CFT at finite temperature could be read from the partition function on $n$-sheeted torus connected with each other along a branch cut. We calculate the partition function by inserting a complete basis across the branch cut. Because of the monodromy condition across the branch cut in the large interval limit, the basis of the states should be the ones in the twist sector. We study the twist sector of a general module of CFT and find that there is a one-to-one correspondence between the twist sector states and the normal sector states. As an application, we revisit the noncompact free scalar theory and discuss the large interval limit of the Rényi entropy of this theory by using our proposal. We find complete agreement in the leading and next-leading orders with direct expansion of the exact partition function. Moreover, we prove the relation (10) between thermal entropy and the entanglement entropy for a generic CFT with discrete spectrum.