We investigate the small-scale static configurations of K-mouflage models defined by a general function $K(\chi )$ of the kinetic terms. The fifth force is screened by the nonlinear K-mouflage mechanism if $K^{\prime }(\chi )$ grows sufficiently fast for large negative $\chi$. In the general nonspherically symmetric case, the fifth force is not aligned with the Newtonian force. For spherically symmetric static matter density profiles, we show that the results depend on the potential function $W_{-}(y)=y{K}^{\prime }(-y^2/2)$; i.e., $W_{-}(y)$ must be monotonically increasing to $+\infty$ for $y\ge 0$ to guarantee the existence of a single solution throughout space for any matter density profile. Small radial perturbations around these static profiles propagate as travelling waves with a velocity greater than the speed of light. Starting from vanishing initial conditions for the scalar field and for a time-dependent matter density corresponding to the formation of an overdensity, we numerically check that the scalar field converges to the static solution. If $W_{-}$ is bounded, for high-density objects there are no static solutions throughout space, but one can still define a static solution restricted to large radii. Our dynamical study shows that the scalar field relaxes to this static solution at large radii, whereas spatial gradients keep growing with time at smaller radii. If $W_{-}$ is not bounded but nonmonotonic, there is an infinite number of discontinuous static solutions. However, the Klein–Gordon equation is no longer a well-defined hyperbolic equation, which leads to complex characteristic speeds and exponential instabilities. Therefore, these discontinuous static solutions are not physical, and these models are not theoretically sound. Such K-mouflage scenarios provide an example of theories that can appear viable at the cosmological level, for the cosmological background and perturbative analysis, while being meaningless at a nonlinear level for small-scale configurations. This shows the importance of small-scale nonlinear analysis of screening models. All healthy K-mouflage models should satisfy $K^{\prime }>0$, and $W_{\pm }(y)=y{K}^{\prime }(\pm y^2/2)$ are monotonically increasing to $+\infty$ when $y\ge 0$.

The origin of large scale magnetic fields is one of the most puzzling topics in cosmology and astrophysics. It is assumed that the observed magnetic fields result from the amplification of an initial field produced in the early universe. In this paper we compute the exact power spectrum of magnetic fields created after inflation best known as post-inflationary magnetic fields, using the first order cosmological perturbation theory. Our treatment differs from others’ works because we include an infrared cutoff which encodes only causal modes in the spectrum. The cross-correlation between magnetic energy density with Lorentz force and the anisotropic part of the electromagnetic field are exactly computed. We compare our results with previous works finding agreement in cases where the ratio between lower and upper cutoff is very small. However, we found that spectrum is strongly affected when this ratio is greater than 0.2. Moreover, the effect of a post-inflationary magnetic field with a lower cutoff on the angular power spectrum in the temperature distribution of cosmic microwave background was also exactly calculated. The main feature is a shift of the spectrum’s peak as a function of the infrared cutoff, therefore analyzing this effect we could infer the value of this cutoff and thus constraining the primordial magnetic fields generation models.

We extend the warm inflationary scenario to the case of the noncanonical scalar fields. The equation of motion and the other basic equations of this new scenario are obtained. The Hubble damped term is enhanced in noncanonical inflation. A linear stability analysis is performed to give the proper slow-roll conditions in warm noncanonical inflation. We study the density fluctuations in the new picture and obtain an approximate analytic expression of the power spectrum. The energy scale at the horizon crossing is depressed by both noncanonical effect and thermal effect, and so is the tensor-to-scalar ratio. Besides the synergy, the noncanonical effect and the thermal effect are competing in the case of the warm noncanonical inflation.

The Born-Infeld determinantal gravity has been recently proposed as a way to smooth the big bang singularity. This theory is formulated on the Weitzenböck space-time and the teleparallel representation is used instead of the standard Riemannian representation. We find that although this theory is shown to be singularity free for a certain region of the parameter space in which the divergence of the Hubble rate in the high-energy regime is substituted by a de Sitter stage or a bounce in a Friedmann-Lemaître-Robertson-Walker universe, cosmological singularities—such as a big rip, big bang, big freeze, and sudden singularities—can emerge in other regions of the configuration space of the theory. We also show that all these singular events exist even though the universe is filled with a perfect fluid with a constant equation of state.

Dark energy can modify the dynamics of dark matter if there exists a direct interaction between them. Thus, a measurement of the structure growth, e.g., redshift-space distortions (RSDs), can provide a powerful tool to constrain the interacting dark energy (IDE) models. For the widely studied $Q=3\beta H{\rho }_{\mathrm{de}}$ model, previous works showed that only a very small coupling [$\beta \sim \mathcal{O}({10}^{-3})$] can survive in current RSD data. However, all of these analyses had to assume $w>-1$ and $\beta >0$ due to the existence of the large-scale instability in the IDE scenario. In our recent work [Phys. Rev. D 90, 063005 (2014)], we successfully solved this large-scale instability problem by establishing a parametrized post-Friedmann framework for the IDE scenario. So we, for the first time, have the ability to explore the full parameter space of the IDE models. In this work, we re-examine the observational constraints on the $Q=3\beta H{\rho }_{\mathrm{de}}$ model within the parametrized post-Friedmann framework. By using the Planck data, the baryon acoustic oscillation data, the JLA sample of supernovae, and the Hubble constant measurement, we get $\beta =-0.010_{-0.033}^{+0.037}$ ($1\sigma$). The fit result becomes $\beta =-0.0148_{-0.0089}^{+0.0100}$ ($1\sigma$) once we further incorporate the RSD data in the analysis. The error of $\beta$ is substantially reduced with the help of the RSD data. Compared with the previous results, our results show that a negative $\beta$ is favored by current observations, and a relatively larger interaction rate is permitted by current RSD data.

The IceCube experiment recently detected the first flux of high-energy neutrinos in excess of atmospheric backgrounds. We examine whether these neutrinos originate from within the same extragalactic sources as ultrahigh energy cosmic rays. Starting from rather general assumptions about spectra and flavors, we find that producing a neutrino flux at the requisite level through pion photoproduction leads to a flux of protons well below the cosmic-ray data at $\sim 10^{18}\mathrm{eV}$, where the composition is light, unless pions/muons cool before decaying. This suggests a dominant class of accelerator that allows for cosmic rays to escape without significant neutrino yields.

We provide a metriclike formulation of the spin-3 gravity in three dimensions. It is shown that the Chern–Simons formulation of the spin-3 gravity can be reformulated as an Einstein–Cartan–Sciama–Kibble theory coupled with the higher-spin matter fields. A dualitylike transformation is also identified from this metriclike formulation.

The annually modulating $\sim \mathrm{keV}$ scintillations observed in the DAMA/NaI and DAMA/Libra experiments might be due to dark matter-electron scattering. Such an explanation is now favored given the stringent constraints on nuclear recoil rates obtained by LUX, SuperCDMS, and other experiments. We suggest that multicomponent dark matter models featuring light dark matter particles of mass $\sim \mathrm{MeV}$ can potentially explain the data. A specific example, kinetically mixed mirror dark matter, is shown to have the right broad properties to consistently explain the experiments via dark matter-electron scattering. If this is the explanation of the annual modulation signal found in the DAMA experiments then a sidereal diurnal modulation signal is also anticipated. We point out that the data from the DAMA experiments show a diurnal variation at around $2.3\sigma$ C.L. with phase consistent with that expected. This electron scattering interpretation of the DAMA experiments can potentially be probed in large xenon experiments (LUX, XENON1T,…), as well as in low threshold experiments (CoGeNT, CDEX, C4,…) by searching for annually and diurnally modulated electron recoils.

We discuss the sparticle (and Higgs) spectrum in a class of flavor symmetry-based minimal supersymmetric standard models, referred to here as sMSSM. In this framework the supersymmetry breaking Lagrangian takes the most general form consistent with a grand unified symmetry such as $SO(10)$ and a non-Abelian flavor symmetry acting on the three families with either a $\mathbf{2}\mathbf{+}\mathbf{1}$ or a $\mathbf{3}$ family assignment. Models based on gauged $SU(2)$ and $SO(3)$ flavor symmetry, as well as non-Abelian discrete symmetries such as $S_3$ and $A_4$, have been suggested which fall into this category. These models describe supersymmetry breaking in terms of seven phenomenological parameters. The soft supersymmetry breaking masses at $M_{\mathrm{GUT}}$ of all sfermions of the first two families are equal in sMSSM, which differ in general from the corresponding third family mass. In such a framework we show that the muon $g-2$ anomaly, the observed Higgs boson mass of $\sim 125\mathrm{GeV}$, and the observed relic neutralino dark matter abundance can be simultaneously accommodated. The resolution of the muon $g-2$ anomaly in particular yields the result that the first two generation squark masses, as well the gluino mass, should be $\lesssim 2\mathrm{TeV}$, which will be tested at LHC14.

While many interactions of dark matter (DM) with the standard model (SM) affect direct detection and LHC searches, there are only a few operators generating annihilation of DM into photons. All of these operators, except four of them, give rise to unsuppressed rates, rendering indirect detection superior to other search strategies. For two of the four effective interactions with velocity-suppressed annihilation cross sections, we identify a new type of loop effect which significantly enhances the associated direct detection rates. As a result, relevant constraints from next-generation direct detection experiments on DM-SM interactions, so far only bounded by the LHC, are obtained.

We perform a detailed, fully correlated study of the chiral behavior of the pion mass and decay constant, based on $2+1$ flavor lattice QCD simulations. These calculations are implemented using tree-level, $O(a)$-improved Wilson fermions, at four values of the lattice spacing down to 0.054 fm and all the way down to below the physical value of the pion mass. They allow a sharp comparison with the predictions of $SU(2)$ chiral perturbation theory ($\chi \mathrm{PT}$) and a determination of some of its low energy constants. In particular, we systematically explore the range of applicability of next-to-leading order (NLO) $SU(2)$ $\chi \mathrm{PT}$ in two different expansions: the first in quark mass ($x$ expansion), and the second in pion mass ($\xi$ expansion). We find that these expansions begin showing signs of failure for $M_{\pi }\gtrsim 300\mathrm{MeV}$, for the typical percent-level precision of our $N_f=2+1$ lattice results. We further determine the LO low energy constants (LECs), $F=88.0\pm 1.3\pm 0.2$ and $B^{\overline{\mathrm{MS}}}(2\mathrm{GeV})=2.61(6)(1)\mathrm{GeV}$, and the related quark condensate, ${\mathrm{\Sigma }}^{\overline{\mathrm{MS}}}(2\mathrm{GeV})=(272\pm 4\pm 1\mathrm{MeV}{)}^3$, as well as the NLO ones, ${\overline{\ell }}_3=2.6(5)(3)$ and ${\overline{\ell }}_4=3.7(4)(2)$, with fully controlled uncertainties. We also explore the next-to-next-to-leading order (NNLO) expansions and the values of NNLO LECs. In addition, we show that the lattice results favor the presence of chiral logarithms. We further demonstrate how the absence of lattice results with pion masses below 200 MeV can lead to misleading results and conclusions. Our calculations allow a fully controlled, ab initio determination of the pion decay constant with a total 1% error, which is in excellent agreement with experiment.

New parametrizations for the electric and the magnetic form factors of a proton and neutron are presented. The proton form factors describe well the recent measurements by the BABAR Collaboration and earlier ones of the ratio of the form factors in a spacelike region. The neutron form factors are consistent with earlier measurements of neutron pair production and ratio of the form factors in the spacelike region. These form factors are implemented into the generator phokhara, which simulates the reactions $e^{+}{e}^{-}\to \overline{p}p\gamma$ and $e^{+}{e}^{-}\to \overline{n}n\gamma$. The influence of final state radiation is investigated.

The analysis of hadronic interactions with effective field theory techniques is complicated by the appearance of a large number of low-energy constants, which are usually fitted to data. On the other hand, the large-$N_c$ limit helps to impose natural short-distance constraints on these low-energy constants, providing a parameter reduction. A Bayesian interpretation of the expected $1/N_c$ accuracy allows for an easy and efficient implementation of these constraints, using an augmented ${\chi }^2$. We apply this approach to the analysis of meson-meson scattering, in conjunction with chiral perturbation theory to one loop and coupled-channel unitarity, and show that it helps to largely reduce the many existing ambiguities and simultaneously provide an acceptable description of the available phase shifts.

We consider the experimental data on $\phi$-meson production in hadron-nucleon collisions for a wide energy region. The quark-gluon string model quantitatively describes the spectra of secondary $\phi$, as well as the ratios of $\phi /{\pi }^{-}$ and $\phi /K^{-}$ production cross sections.

The link between the electroweak gauge boson masses and the Fermi constant via the muon lifetime measurement is instrumental for constraining and eventually pinning down new physics. We consider the simplest extension of the standard model with an additional real scalar $SU(2{)}_L\otimes U(1{)}_Y$ singlet and compute the electroweak precision parameter $\mathrm{\Delta }r$, along with the corresponding theoretical prediction for the W-boson mass. When confronted with the experimental W-boson mass measurement, our predictions impose limits on the singlet model parameter space. We identify regions, especially in the mass range which is accessible by the LHC, where these correspond to the most stringent experimental constraints that are currently available.

We improve the theoretical predictions for the decays of the Higgs boson to an $S$-wave vector quarkonium plus a photon by calculating the relativistic correction of order $v^2$, where $v$ is the heavy-quark velocity in the quarkonium rest frame. Our numerical results are given for the $J/\psi$ and $\mathrm{\Upsilon }(nS)$ channels, with $n=1$, 2, 3. The numerical results include a previously calculated correction of order ${\alpha }_s$ and summations, to all orders in ${\alpha }_s$, of leading logarithms of $m_H^2/m_Q^2$, where $m_H$ is the Higgs-boson mass and $m_Q$ is the heavy-quark mass. These QCD corrections apply to the contribution of leading order in $v$ and to part of the order-$v^2$ correction. For the remainder of the order-$v^2$ correction, we sum leading logarithms of $m_H/m_Q$ through order ${\alpha }_s^2$. These refinements reduce the theoretical uncertainties in the direct-production amplitudes for $H\to J/\psi +\gamma$ and $H\to \mathrm{\Upsilon }(1S)+\gamma$ by approximately a factor of 3 and open the door to improved determinations at the LHC of the Higgs-boson Yukawa couplings to the charm and bottom quarks.

Short-baseline neutrino anomalies suggest the existence of low-mass [$m\sim \mathcal{O}(1)\mathrm{eV}$] sterile neutrinos ${\nu }_s$. These would be efficiently produced in the early universe by oscillations with active neutrino species, leading to a thermal population of the sterile states seemingly incompatible with cosmological observations. In order to relieve this tension it has been recently speculated that new “secret” interactions among sterile neutrinos, mediated by a massive gauge boson $X$ (with $M_X\ll M_W$), can inhibit or suppress the sterile neutrino thermalization, due to the production of a large matter potential term. We note however, that they also generate strong collisional terms in the sterile neutrino sector that induce an efficient sterile neutrino production after a resonance in matter is encountered, increasing their contribution to the number of relativistic particle species $N_{\text{eff}}$. Moreover, for values of the parameters of the ${\nu }_s\text{−}{\nu }_s$ interaction for which the resonance takes place at temperature $T\lesssim \text{few}\mathrm{MeV}$, significant distortions are produced in the electron (anti)neutrino spectra, altering the abundance of light element in big bang nucleosynthesis (BBN). Using the present determination of ${}^4\mathrm{He}$ and deuterium primordial abundances we determine the BBN constraints on the model parameters. We find that ${}^2\mathrm{H}/\mathrm{H}$ density ratio exclude much of the parameter space if one assumes a baryon density at the best fit value of Planck experiment, ${\mathrm{\Omega }}_B{h}^2=0.02207$, while bounds become weaker for a higher ${\mathrm{\Omega }}_B{h}^2=0.02261$, the 95% C.L. upper bound of Planck. Due to the large error on its experimental determination, the helium mass fraction $Y_p$ gives no significant bounds.

We study several aspects of electroweak vacuum metastability when an extra gauge singlet scalar, a viable candidate for a dark matter particle, is added to the standard model of particle physics, which is assumed to be valid up to the Planck scale. Phase diagrams are drawn for different parameter spaces, and based on that, we graphically demonstrate how the confidence level, at which stability of electroweak vacuum is excluded, depends on such new physics parameters.

We present the results of an amplitude analysis of ${\overline{B}}^0\to J/\psi K^{-}{\pi }^{+}$ decays. A new charged charmoniumlike state $Z_c(4200{)}^{+}$ decaying to $J/\psi {\pi }^{+}$ is observed with a significance of $6.2\sigma$. The mass and width of the $Z_c(4200{)}^{+}$ are $4196_{-29-13}^{+31+17}\mathrm{MeV}/c^2$ and $370_{-70-132}^{+70+70}\mathrm{MeV}$, respectively; the preferred assignment of the quantum numbers is $J^P=1^{+}$. In addition, we find evidence for $Z_c(4430{)}^{+}\to J/\psi {\pi }^{+}$. The analysis is based on a $711{\mathrm{fb}}^{-1}$ data sample collected by the Belle detector at the asymmetric-energy $e^{+}{e}^{-}$ collider KEKB.