Monochromatic gamma ray lines have long been known to provide potential smoking-gun signals for annihilating dark matter. Here, we demonstrate that the situation is particularly interesting for Kaluza-Klein dark matter because resonant annihilation is generically expected for small, but not necessarily vanishing relative velocities of the annihilating particles. We calculate the contribution from those hitherto neglected resonances and show that the annihilation rate into monochromatic photons can be significantly enhanced, in a way that is much more pronounced than for the associated production of continuum photons. For favorable astrophysical conditions, this leads to promising prospects for the detection of TeV-scale Kaluza-Klein dark matter. We also point out that the situation may be even more interesting in the vicinity of black holes, like the supermassive black hole at the center of our Galaxy, where in principle center-of-mass energies much larger than the rest mass are available. In this case, annihilating Kaluza-Klein dark matter may show the striking and unique signature of several gamma ray lines, with an equidistant spacing corresponding to twice the compactification radius of the extra dimension.

In light of the recent BICEP2 B-mode polarization detection, which implies a large inflationary tensor-to-scalar ratio $r_{0.05}=0.2_{-0.05}^{+0.07}$, we re-examine the evidence for an extra sterile massive neutrino, originally invoked to account for the tension between the cosmic microwave background (CMB) temperature power spectrum and local measurements of the expansion rate $H_0$ and cosmological structure. With only the standard active neutrinos and power-law scalar spectra, this detection is in tension with the upper limit of $r<0.11$ (95% confidence) from the lack of a corresponding low multipole excess in the temperature anisotropy from gravitational waves. An extra sterile species with the same energy density as is needed to reconcile the CMB data with $H_0$ measurements can also alleviate this new tension. By combining data from the Planck and ACT/SPT temperature spectra, WMAP9 polarization, $H_0$, baryon acoustic oscillation and local cluster abundance measurements with BICEP2 data, we find the joint evidence for a sterile massive neutrino increases to $\mathrm{\Delta }{N}_{\text{eff}}=0.98\pm 0.26$ for the effective number and $m_s=0.52\pm 0.13\mathrm{eV}$ for the effective mass, or $3.8\sigma$ and $4\sigma$ evidence, respectively. We caution the reader that these results correspond to a joint statistical evidence and, in addition, astrophysical systematic errors in the clusters and $H_0$ measurements, and small-scale CMB data could weaken our conclusions.

Motivated by the experimental study of $J/\psi \to \gamma +$ invisible decay by the CLEO Collaboration, we analyze the process $J/\psi \to \gamma \nu \overline{\nu }$, as the standard model background for this invisible decay, at the lowest order. Our investigation shows that $\mathrm{Br}(J/\psi \to \gamma \nu \overline{\nu })$ is far below the present experimental upper limit on the branching ratio of $J/\psi \to \gamma +$ invisible, which indicates that some interesting room for new physics in this channel might be expected. We also present a similar analysis of the ${\eta }_c\to \gamma \nu \overline{\nu }$ decay.

The masses of the low-lying baryons are evaluated using a total of ten ensembles of dynamical twisted mass fermion gauge configurations. The simulations are performed using two degenerate flavors of light quarks, and a strange and a charm quark fixed to approximately their physical values. The light sea quarks correspond to pseudo scalar masses in the range of about 210 to 430 MeV. We use the Iwasaki improved gluonic action at three values of the coupling constant corresponding to lattice spacing $a=0.094$, 0.082 and 0.065 fm determined from the nucleon mass. We check for both finite volume and cutoff effects on the baryon masses. We examine the issue of isospin symmetry breaking for the octet and decuplet baryons and its dependence on the lattice spacing. We show that in the continuum limit isospin breaking is consistent with zero, as expected. We performed a chiral extrapolation of the forty baryon masses using SU(2) $\chi \mathrm{PT}$. After taking the continuum limit and extrapolating to the physical pion mass our results are in good agreement with experiment. We provide predictions for the mass of the doubly charmed ${\mathrm{\Xi }}_{cc}^{*}$, as well as of the doubly and triply charmed $\mathrm{\Omega }$s that have not yet been determined experimentally.

The Sivers effect describes the correlation of the unpolarized parton’s transverse momentum with the transverse spin of the nucleon. It manifests as a sine modulation of the cross section for single-hadron semi-inclusive deep inelastic scattering (SIDIS) on a transversely polarized nucleon with the azimuthal angle between the produced hadron’s transverse momentum and the nucleon spin (${\phi }_h$ and ${\phi }_S$, respectively). It has been recently suggested that the Sivers effect can also be measured in a two-hadron SIDIS process as sine modulations involving the azimuthal angles ${\phi }_T$ and ${\phi }_R$ of both the total and the relative transverse momenta of the hadron pair. Here we present the detailed derivation of the two-hadron SIDIS cross section using simple parton-model inspired functional forms for both the parton distribution and the fragmentation functions. We show explicitly that the terms corresponding to the $\sin ({\phi }_R-{\phi }_S)$ and $\sin ({\phi }_T-{\phi }_S)$ modulations are nonzero. Further, we derive the cross section expressions for single-hadron production in the two-hadron sample. Finally, we employ a modified version of the lepto Monte Carlo event generator that includes the Sivers effect to estimate the size of single spin asymmetries corresponding to these modulations independent of the formalism developed.

We investigate the processes $e^{+}{e}^{-}$ annihilating to $J/\psi \pi \pi$, ${\psi }^{\prime }\pi \pi$ and $h_c\pi \pi$. The coupled-channel effects induced by the couplings between the widely accepted $D$-wave charmonium $\psi (4160)$ and $D_{1}D$, $D_1{D}^{*}$ and $D_2{D}^{*}$ charmed meson pairs in the $S$-wave state with couplings given by heavy quark spin symmetry are analyzed. The line shapes show the presence of cusps that result from the singularities of the rescattering loops, which could be helpful in understanding the nature of $Y(4260)$, $Y(4360)$, $Z_c(3900)/Z_c(3885)$ and $Z_c(4020)/Z_c(4025)$.

The possibility to construct inflationary models for the renormalization-group (RG) improved potentials corresponding to scalar electrodynamics and to $SU(2)$ and $SU(5)$ models is investigated. In all cases, the tree-level potential, which corresponds to the cosmological constant in the Einstein frame, is seen to be nonsuitable for inflation. Rather than adding the Hilbert-Einstein term to the action, quantum corrections to the potential, coming from the RG equation, are included. The inflationary scenario is analyzed with unstable de Sitter solutions that correspond to positive values of the coupling function, only. We show that, for the finite $SU(2)$ model and $SU(2)$ gauge model, there are no de Sitter solutions suitable for inflation, unless exit from it occurs according to some weird, nonstandard scenarios. Inflation is realized both for scalar electrodynamics and for $SU(5)$ RG-improved potentials, and the corresponding values of the coupling function are seen to be positive. It is shown that, for quite reasonable values of the parameters, the inflationary models obtained both from scalar electrodynamics and from the $SU(5)$ RG-improved potentials are in good agreement with the most recent observational data coming from the Planck 2013 and BICEP2 collaborations.

The network of cosmic strings generated in a phase transition during inflation enters the scaling regime later than that of usual strings. If it occurs after the recombination, temperature anisotropies of the cosmic microwave background (CMB) at high multipole moments are significantly reduced. In this paper, we study such effects qualitatively and show that the constraint on the cosmic string tension from the CMB temperature anisotropies and B-mode polarizations can be relaxed. It is shown to be difficult to explain the recent BICEP2 and POLARBEAR results in terms of signals induced by cosmic strings alone even if we take into account the delayed scaling. However, the inflationary tensor-to-scalar ratio required to explain the observed B-mode signals can be slightly reduced to be consistent with the Planck constraint.

We explore $G\times G$ unified theories with the visible and the hidden or dark sectors paired under a ${\mathbb{Z}}_2$ symmetry. Developing a system of “asymmetric symmetry breaking” we motivate such models on the basis of their ability to generate dark baryons that are confined with a mass scale just above that of the proton, as motivated by asymmetric dark matter. This difference is achieved from the distinct but related confinement scales that develop in unified theories that have the two factors of $G$ spontaneously breaking in an asymmetric manner. We show how Higgs potentials that admit different gauge group breaking chains in each sector can be constructed, and demonstrate the capacity for generating different fermion mass scales. Lastly we discuss supersymmetric extensions of such schemes.

In the framework of relativistic ideal hydrodynamics, we study the production mechanism for vorticity and magnetic field in relativistic ideal fluids. It is demonstrated that in the uncharged fluids the thermal vorticity will always satisfy the Kelvin’s theorem and the circulation must be conserved. However, in the charged fluids, the vorticity and magnetic field can be produced by the interaction between the entropy gradients and the fluid velocity gradients. Especially, in the multiple charged fluids, the vorticity and magnetic field can be produced by the interaction between the inhomogeneous charge density ratio and the fluid velocity gradients even if the entropy distribution is homogeneous, which provides another mechanism for the production of vorticity and magnetic field in relativistic plasmas or in the early universe.

In this paper the polarized and unpolarized lepton pair forward-backward asymmetries and their averages in $\overline{B}\to {\overline{K}}_1(1270){\ell }^{+}{\ell }^{-}$ and $\overline{B}\to {\overline{K}}^{*}{\ell }^{+}{\ell }^{-}$ decays using model III of the two Higgs doublet model are investigated. The obtained results of both decay modes are compared to each other and to those of SM. In addition, by obtaining the minimum required number of events for detecting each asymmetry and comparing them with the number of produced $B\overline{B}$ pairs at the LHC or supposed to be produced at the Super-LHC, we present a comprehensive discussion regarding the polarized and unpolarized forward-backward asymmetries of $\overline{B}\to {\overline{K}}_1(1270){\ell }^{+}{\ell }^{-}$ and $\overline{B}\to {\overline{K}}^{*}{\ell }^{+}{\ell }^{-}$ decays. We discover that the study of these asymmetries and the corresponding averages in $\overline{B}\to {\overline{K}}_1(1270){\ell }^{+}{\ell }^{-}$ and $\overline{B}\to {\overline{K}}^{*}{\ell }^{+}{\ell }^{-}$ decays can provide good signals for probing new physics beyond the SM in the future B-physics experiments.

After the discovery of the standard model-like Higgs boson at the LHC, the structure of the Higgs sector remains unknown. We discuss how it can be determined by the combination of direct and indirect searches for additional Higgs bosons at future collider experiments. First of all, we evaluate expected excluded regions for the mass of additional neutral Higgs bosons from direct searches at the LHC with the 14 TeV collision energy in the two Higgs doublet models with a softly broken $Z_2$ symmetry. Second, precision measurements of the Higgs boson couplings at future experiments can be used for the indirect search of extended Higgs sectors if the measured coupling constant with the gauge boson slightly deviates from the standard model value. In particular, in the two Higgs doublet model with the softly broken discrete symmetry, there are four types of Yukawa interactions, so that they can be discriminated by measuring the pattern of deviations in Yukawa coupling constants. Furthermore, we can fingerprint various extended Higgs sectors with future precision data by detecting the pattern of deviations in the coupling constants of the standard model-like Higgs boson. We demonstrate how the pattern of deviations can be different among various Higgs sectors that predict the electroweak rho parameter to be unity, such as models with additional an isospin singlet, a doublet, triplets, or a septet. We conclude that, as long as the gauge coupling constant of the Higgs boson slightly differs from the standard model prediction but is enough to be detected at the LHC and its high-luminosity run or at the International Linear Collider, we can identify the nonminimal Higgs sector even without direct discovery of additional Higgs bosons at the LHC.

The difference between the $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ longitudinal spin transfers in the semi-inclusive deep inelastic scattering process is intensively studied. The study is performed in the current fragmentation region, by considering the intermediate hyperon decay processes and sea quark fragmentation processes, while the strange sea $s\overline{s}$ asymmetry in the nucleon is taken into account. The calculation in the light-cone quark-diquark model shows that the strange sea asymmetry gives a proper trend to the difference between the $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ longitudinal spin transfers. When considering the nonzero final hadron transverse momentum, our results can explain the COMPASS data reasonably. The nonzero final hadron transverse momentum is interpreted as a natural constraint to the final hadron $z$ range where the longitudinal spin transfer is more sensitive to the strange sea $s\overline{s}$ asymmetry.

We study the consequences of including the running of the QCD coupling in the equation describing the evolution of the jet quenching parameter $\widehat{q}$ in the double logarithmic approximation. To start with, we revisit the case of a fixed coupling, for which we obtain exact solutions valid for generic values of the transverse momentum (above the medium saturation scale) and corresponding to various initial conditions. In the case of a running coupling, we construct approximate solutions in the form of truncated series obtained via successive iterations, whose convergence is well under control. We thus deduce the dominant asymptotic behavior of the renormalized $\widehat{q}$ in the limit of a large “evolution time” $Y\equiv \ln (L/\lambda )$, with $L$ the size of the medium and $\lambda$ the typical wavelength of a medium constituent. We show that the asymptotic expansion is universal with respect to the choice of the initial condition at $Y=0$ and, moreover, it is remarkably similar to the corresponding expansion for the saturation momentum of a “shockwave” (a large nucleus). As expected, the running of the coupling significantly slows down the increase of $\widehat{q}$ with $Y$ in the asymptotic regime at $Y\gg 1$. For the phenomenologically interesting value $Y\simeq 3$, we find an enhancement factor close to 3, independently of the initial condition and for both fixed and running coupling.

We have calculated the axial-vector form factors of the low-lying octet baryons ($N$, $\mathrm{\Sigma }$, $\mathrm{\Xi }$, and $\mathrm{\Lambda }$) in the chiral constituent quark model. In particular, we have studied the implications of chiral symmetry breaking and SU(3) symmetry breaking for the singlet ($g_A^0$) and nonsinglet ($g_A^3$ and $g_A^8$) axial-vector coupling constants expressed as combinations of the spin polarizations at zero momentum transfer. The conventional dipole form of parametrization has been used to analyze the $Q^2$ dependence of the axial-vector form factors [$G_A^0(Q^2)$, $G_A^3(Q^2)$, and $G_A^8(Q^2)$]. The total strange singlet and nonsinglet contents [$G_s^0(Q^2)$, $G_s^3(Q^2)$, and $G_s^8(Q^2)$] of the nucleon determining the strange quark contribution to the nucleon spin ($\mathrm{\Delta }s$) have also been discussed.

This work deals with braneworld models in the presence of auxiliary fields. We investigate the case where Einstein’s equation is modified with the inclusion of extra, nondynamical terms. We show that the model supports first-order differential equations that solve the equations of motion, but the standard braneworld scenario changes under the presence of the parameter that controls the nondynamical or auxiliary fields that modifies Einstein’s equation.

The first detection of high-energy astrophysical neutrinos by IceCube provides new opportunities for tests of neutrino properties. The long baseline through the cosmic neutrino background ($\mathrm{C}\nu \mathrm{B}$) is particularly useful for directly testing secret neutrino interactions ($\nu \mathrm{SI}$) that would cause neutrino-neutrino elastic scattering at a larger rate than the usual weak interactions. We show that IceCube can provide competitive sensitivity to $\nu \mathrm{SI}$ compared to other astrophysical and cosmological probes, which are complementary to laboratory tests. We study the spectral distortions caused by $\nu \mathrm{SI}$ with a large s-channel contribution, which can lead to a dip, bump, or cutoff on an initially smooth spectrum. Consequently, $\nu \mathrm{SI}$ may be an exotic solution for features seen in the IceCube energy spectrum. More conservatively, IceCube neutrino data could be used to set model-independent limits on $\nu \mathrm{SI}$. Our phenomenological estimates provide guidance for more detailed calculations, comparisons to data, and model building.