We investigate the effect of the stochastic gravitational wave (GW) background produced by kinks on infinite cosmic strings, whose spectrum was derived in our previous work, on the $B$-mode power spectrum of the cosmic microwave background (CMB) anisotropy. We find that the $B$-mode polarization due to kinks is comparable to that induced by the motion of the string network and hence the contribution of GWs from kinks is important for estimating the $B$-mode power spectrum originating from cosmic strings. If the tension of cosmic strings $\mu$ is large enough, i.e., $G\mu \gtrsim {10}^{-8}$, $B$-mode polarization induced by cosmic strings can be detected by future CMB experiments.

We show that the correlation functions of ghosts and gluons for the pure Yang-Mills theory in Landau gauge can be accurately reproduced for all momenta by a one-loop calculation. The key point is to use a massive extension of the Faddeev-Popov action. The agreement with lattice simulation is excellent in $d=4$. The one-loop calculation also reproduces all the characteristic features of the lattice simulations in $d=3$ and naturally explains the peculiarities of the propagators in $d=2$.

We study pion condensation at zero temperature in a hard-wall holographic model of hadrons with isospin chemical potential. We find that the transition from the hadronic phase to the pion condensate phase is first order except in a certain limit of model parameters. Our analysis suggests that immediately across the phase boundary the condensate acts as a stiff medium approaching the Zel’dovich limit of equal energy density and pressure.

We show that, despite appearances, a theoretical approach to neutrino oscillation in which the neutrino and its interaction partners are entangled yields the standard result for the neutrino oscillation wavelength. We also shed some light on the question of why plane-wave approaches to the neutrino oscillation problem can yield the correct oscillation wavelength even though they do not explicitly account for the localization of the neutrino source and the detector.

One of the primary goals of the Large Hadron Collider is to understand the electroweak symmetry breaking mechanism. In the standard model, electroweak symmetry breaking is described by the Higgs mechanism which includes a scalar Higgs boson. Electroweak measurements constrain the standard model Higgs boson mass to be in the 114.4 to $157\mathrm{GeV}/c^2$ range. For $m_h<135\mathrm{GeV}/c^2$, the Higgs predominantly decays into two $b$-quarks. As such, we investigate the prospect of observing the standard model Higgs decaying to $b\overline{b}$ produced in weak-boson-fusion with an associated central photon. An isolated, high $p_{\mathrm{T}}$, central photon trigger is expected to be available at the ATLAS and CMS experiments. In this study, we investigated the effects originating from showering, hadronization, the underlying event model, and jet performance including $b$-jet calibration on the sensitivity of this channel. We found that the choice of Monte Carlo simulation and its tune has a large effect on the efficacy of the central jet veto and consequently the signal significance. A signal significance of ${1.6}_{-0.3}^{+0.5}$ can be achieved for $m_h=115\mathrm{GeV}/c^2$ with $100{\mathrm{fb}}^{-1}$ of integrated luminosity which correspond to 1 yr at design luminosity at 14 TeV $pp$ collisions.

We investigate neutrino-induced one pion production on nucleons. The elementary neutrino-nucleon cross section is calculated as the sum of the leading Delta pole diagram and several background diagrams obtained within the nonlinear sigma model. This approach does not introduce any new adjustable parameters, which allows unambiguous predictions for the observables. Considering electroproduction experiments as benchmark, the model is shown to be applicable up to pion-nucleon invariant mass $W<1.4\mathrm{GeV}$ and provides a good accuracy. With respect to the total one pion cross section, the model predicts the background at the level of 10% for the $p{\pi }^{+}$, 30% for $p{\pi }^0$, and 50% for $n{\pi }^{+}$ final states. The results are compared with experimental data for various differential cross sections. Distributions with respect to muon-nucleon and muon-pion invariant masses are presented for the first time. The model describes the data quite well, with the discrepancies being of the same order as those between different data sets.

We present results for the charmonium-nucleon potential $V_{c\overline{c}\mathrm{\text{−}}N}(r)$ from quenched lattice QCD, which is calculated from the equal-time Bethe-Salpeter amplitude through the effective Schrödinger equation. Detailed information of the low-energy interaction between the nucleon and charmonia (${\eta }_c$ and $J/\psi$) is indispensable for exploring the formation of charmonium bound to nuclei. Our simulations are performed at a lattice cutoff of $1/a\approx 2.1\mathrm{GeV}$ in a spatial volume of $(3\mathrm{fm}{)}^3$ with the nonperturbatively $\mathcal{O}(a)$ improved Wilson action for the light quarks and a relativistic heavy quark action for the charm quark. We have found that the potential $V_{c\overline{c}\mathrm{\text{−}}N}(r)$ for either the ${\eta }_c$ or $J/\psi$ states is weakly attractive at short distances and exponentially screened at large distances. The spin averaged $J/\psi \mathrm{\text{−}}N$ potential is slightly more attractive than that of the ${\eta }_c\mathrm{\text{−}}N$ case.

We present a search for the decay $B^{+}\to a_1^{+}(1260)K^{*0}(892)$. The data, collected with the BABAR detector at the SLAC National Accelerator Laboratory, represent $465\times {10}^6$$B\overline{B}$ pairs produced in $e^{+}{e}^{-}$ annihilation at the energy of the $\mathit{{\rm Y}}(4S)$. We find no significant signal and set an upper limit at 90% confidence level on the product of branching fractions $\mathcal{B}(B^{+}\to a_1^{+}(1260)K^{*0}(892))\times \mathcal{B}(a_1^{+}(1260)\to {\pi }^{+}{\pi }^{-}{\pi }^{+})$ of $1.8\times {10}^{-6}$.

Up to now there has been no search for gravitational waves from the $r$-modes of neutron stars in spite of the theoretical interest in the subject. Several oddities of $r$-modes must be addressed to obtain an observational result: The gravitational radiation field is dominated by the mass current (gravitomagnetic) quadrupole rather than the usual mass quadrupole, and the consequent difference in polarization affects detection statistics and parameter estimation. To astrophysically interpret a detection or upper limit it is necessary to convert the gravitational-wave amplitude to an $r$-mode amplitude. Also, it is helpful to know indirect limits on gravitational-wave emission to gauge the interest of various searches. Here I address these issues, thereby providing the ingredients to adapt broad-band searches for continuous gravitational waves to obtain $r$-mode results. I also show that searches of existing data can already have interesting sensitivities to $r$-modes.

We calculate solar models including dark matter (DM) weakly interacting massive particles (WIMPs) of mass 5–50 GeV and test these models against helioseismic constraints on sound speed, convection-zone depth, convection-zone helium abundance, and small separations of low-degree $p$-modes. Our main conclusion is that both direct detection experiments and particle accelerators may be complemented by using the Sun as a probe for WIMP DM particles in the 5–50 GeV mass range. The DM most sensitive to this probe has suppressed annihilations and a large spin-dependent elastic scattering cross section. For the WIMP cross section parameters explored here, the lightest WIMP masses $<10\mathrm{GeV}$ are ruled out by constraints on core sound speed and low-degree frequency spacings. For WIMP masses 30–50 GeV, the changes to the solar structure are confined to the inner 4% of the solar radius and so do not significantly affect the solar $p$-modes. Future helioseismology observations, most notably involving $g$-modes, and future solar neutrino experiments may be able to constrain the allowable DM parameter space in a mass range that is of current interest for direct detection.

A basic aim of ongoing and upcoming cosmological surveys is to unravel the mystery of dark energy. In the absence of a compelling theory to test, a natural approach is to better characterize the properties of dark energy in search of clues that can lead to a more fundamental understanding. One way to view this characterization is the improved determination of the redshift-dependence of the dark energy equation of state parameter, $w(z)$. To do this requires a robust and bias-free method for reconstructing $w(z)$ from data that does not rely on restrictive expansion schemes or assumed functional forms for $w(z)$. We present a new nonparametric reconstruction method that solves for $w(z)$ as a statistical inverse problem, based on a Gaussian process representation. This method reliably captures nontrivial behavior of $w(z)$ and provides controlled error bounds. We demonstrate the power of the method on different sets of simulated supernova data; the approach can be easily extended to include diverse cosmological probes.

We show that the class of antenna layouts for telescope arrays allowing cheap analysis hardware (with correlator cost scaling as $N\log N$ rather than $N^2$ with the number of antennas $N$) is encouragingly large, including not only previously discussed rectangular grids but also arbitrary hierarchies of such grids, with arbitrary rotations and shears at each level. We show that all correlations for such a 2D array with an $n$-level hierarchy can be efficiently computed via a fast Fourier transform in not two but $2n$ dimensions. This can allow major correlator cost reductions for science applications requiring exquisite sensitivity at widely separated angular scales, for example, 21 cm tomography (where short baselines are needed to probe the cosmological signal and long baselines are needed for point source removal), helping enable future 21 cm experiments with thousands or millions of cheap dipolelike antennas. Such hierarchical grids combine the angular resolution advantage of traditional array layouts with the cost advantage of a rectangular fast Fourier transform telescope. We also describe an algorithm for how a subclass of hierarchical arrays can efficiently use rotation synthesis to produce global sky maps with minimal noise and a well-characterized synthesized beam.

We derive a simple analytical expression for the two-body force in a subclass of modified Newtonian dynamics (MOND) theories and make testable predictions in the modification to the two-body orbital period, shape, precession rate, escape speed, etc. We demonstrate the applications of the modified Kepler’s law in the timing of satellite orbits around the Milky Way, and checking the feasibility of MOND in the orbit of the large Magellanic cloud, the M31 galaxy, and the merging bullet clusters. MOND appears to be consistent with satellite orbits although with a tight margin. Our results on two-bodies are also generalized to restricted three-body, many-body problems, rings, and shells.

Mirror dark matter offers a framework to explain the existing dark matter direct detection experiments. Here we confront this theory with the most recent experimental data, paying attention to the various known systematic uncertainties, in quenching factor, detector resolution, galactic rotational velocity, and velocity dispersion. We perform a detailed analysis of the DAMA and CoGeNT experiments assuming a negligible channeling fraction and find that the data can be fully explained within the mirror dark matter framework. We also show that the mirror dark matter candidate can explain recent data from the CDMS/Ge, EdelweissII, and CRESSTII experiments and we point out ways in which the theory can be further tested in the near future.

We present a search for the lightest supersymmetric partner of the top quark in proton-antiproton collisions at a center-of-mass energy $\sqrt{s}=1.96\mathrm{TeV}$. This search was conducted within the framework of the $R$ parity conserving minimal supersymmetric extension of the standard model, assuming the stop decays dominantly to a lepton, a sneutrino, and a bottom quark. We searched for events with two oppositely-charged leptons, at least one jet, and missing transverse energy in a data sample corresponding to an integrated luminosity of $1{\mathrm{fb}}^{-1}$ collected by the Collider Detector at Fermilab experiment. No significant evidence of a stop quark signal was found. Exclusion limits at 95% confidence level in the stop quark versus sneutrino mass plane are set. Stop quark masses up to $180\mathrm{GeV}/c^2$ are excluded for sneutrino masses around $45\mathrm{GeV}/c^2$, and sneutrino masses up to $116\mathrm{GeV}/c^2$ are excluded for stop quark masses around $150\mathrm{GeV}/c^2$.

A static and axisymmetric solution of the Einstein vacuum equations with a finite number of relativistic multipole moments (RMM) is written in multipole symmetry adapted (MSA) coordinates up to certain order of approximation, and the structure of its metric components is explicitly shown. From the equation of equatorial geodesics, we obtain the Binet equation for the orbits and it allows us to determine the gravitational potential that leads to the equivalent classical orbital equations of the perturbed Kepler problem. The relativistic corrections to Keplerian motion are provided by the different contributions of the RMM of the source starting from the monopole (Schwarzschild correction). In particular, the perihelion precession of the orbit is calculated in terms of the quadrupole and $2^4$-pole moments. Since the MSA coordinates generalize the Schwarzschild coordinates, the result obtained allows measurement of the relevance of the quadrupole moment in the first order correction to the perihelion frequency-shift.

We investigate the pattern of chiral-symmetry restoration of QCD for $N_c=3$ and $N_f=2$ at finite temperature ($T$) beyond the chiral limit. To this end, we employ the instanton-vacuum configuration for the flavor SU(2) sector and the Harrington-Shepard caloron for modifying relevant instanton parameters as functions of $T$. The meson loop corrections (MLC), which correspond to $1/N_c$ corrections, are also taken into account to reproduce appropriate $m_q$ dependences of chiral order parameters. We compute the chiral condensate as a function of $T$ and/or $m_q$. We observe that MLC play an important role to have a correct universality-class behavior of chiral-restoration patterns in this framework, depending on $m_q$: Second-order phase transition in the chiral limit $m_q=0$ and cross-over for $m_q\ne 0$. Without MLC, all the restoration patterns are crossover, due to simple saddle-point approximations. It turns out that $T_c^{\chi }=159\mathrm{MeV}$ in the chiral limit and $T_c^{\chi }=(177,186,196)\mathrm{MeV}$ for $m_q=(5,10,15)\mathrm{MeV}$, using the phenomenological choices for the instanton parameters at $T=0$.

We construct a simple ${\mathrm{AdS}}_4\times S^1$ flux compactification stabilized by a complex scalar field winding the single extra dimension and demonstrate an instability to nucleation of a bubble of nothing. This occurs when the Kaluza-Klein dimension degenerates to a point, defining the bubble surface. Because the extra dimension is stabilized by a flux, the bubble surface must be charged, in this case under the axionic part of the complex scalar. This smooth geometry can be seen as a de Sitter topological defect with asymptotic behavior identical to the pure compactification. We discuss how a similar construction can be implemented in more general Freund-Rubin compactifications.

We investigate the vacuum expectation value of the fermionic current induced by a magnetic flux in a ($2+1$)-dimensional conical spacetime in the presence of a circular boundary. On the boundary the fermionic field obeys the MIT bag boundary condition. For irregular modes, a special case of boundary conditions at the cone apex is considered, when the MIT bag boundary condition is imposed at a finite radius, which is then taken to zero. We observe that the vacuum expectation values for both the charge density and azimuthal current are periodic functions of the magnetic flux with the period equal to the flux quantum whereas the expectation value of the radial component vanishes. For both exterior and interior regions, the expectation values of the current are decomposed into boundary-free and boundary-induced parts. For a massless field the boundary-free part in the vacuum expectation value of the charge density vanishes, whereas the presence of the boundary induces nonzero charge density. Two integral representations are given for the boundary-free part in the case of a massive fermionic field for arbitrary values of the opening angle of the cone and magnetic flux. The behavior of the induced fermionic current is investigated in various asymptotic regions of the parameters. At distances from the boundary larger than the Compton wavelength of the fermion particle, the vacuum expectation values decay exponentially with the decay rate depending on the opening angle of the cone. We make a comparison with the results already known from the literature for some particular cases.