We study a coupled quintessence model in which the interaction with the dark-matter sector is a function of the quintessence potential. Such a coupling can arise from a field dependent mass term for the dark-matter field. The dynamical analysis of a standard quintessence potential coupled with the interaction explored here shows that the system possesses a late-time accelerated attractor. In light of these results, we perform a fit to the most recent Supernovae Ia, Cosmic Microwave Background, and Baryon Acoustic Oscillation data sets. Constraints arising from weak equivalence principle violation arguments are also discussed.

We provide an analytical study of the coupling of short and long wavelength fluctuation modes during the initial phase of reheating in two field models like hybrid inflation. In these models, there is—at linear order in perturbation theory—an instability in the entropy modes of cosmological perturbations which, if not cut off, could lead to curvature fluctuations which exceed the current observational values. Here, we demonstrate that the backreaction of short wavelength fluctuations is too weak to lead to a truncation of the instability for the long wavelength modes on time scales comparable to the typical instability time scale of the long wavelength entropy modes. Hence, unless there are other mechanisms which truncate the instability, then in models such as hybrid inflation the curvature perturbations produced during reheating on scales of current observational interest may be very important.

The forthcoming release of data from the Planck mission, and possibly from the next round of Wilkinson Microwave Anisotropy Probe (WMAP) observations, make it necessary to revise the evaluations of relic gravitational waves in the existing data and, at the same time, to refine the assumptions and data analysis techniques in preparation for the arrival of new data. We reconsider with the help of the commonly used CosmoMC numerical package the previously found indications of relic gravitational waves in the 7-year (WMAP7) data. The CosmoMC approach reduces the confidence of these indications from approximately $2\sigma$ level to approximately $1\sigma$ level, but the indications do not disappear altogether. We critically analyze the assumptions that are currently used in the cosmic microwave background (CMB) data analyses, and outline the strategy that should help avoid the oversight of relic gravitational waves in the future CMB data. In particular, it is important to keep away from the unwarranted assumptions about density perturbations. The prospects of confident detection of relic gravitational waves by the Planck satellite have worsened, but they are still good. It appears that more effort will be required in order to mitigate the foreground contamination.

We study symmetry restoration at finite temperature in the standard model during the electroweak phase transition in the presence of a weak magnetic field. We compute the finite temperature effective potential up to the contribution of ring diagrams, using the broken phase degrees of freedom, and keep track of the gauge parameter dependence of the results. We show that under these conditions, the phase transition becomes stronger first order.

Data taken during the final shallow-site run of the first tower of the Cryogenic Dark Matter Search (CDMS II) detectors have been reanalyzed with improved sensitivity to small energy depositions. Four $\sim 224\mathrm{g}$ germanium and two $\sim 105\mathrm{g}$ silicon detectors were operated at the Stanford Underground Facility (SUF) between December 2001 and June 2002, yielding 118 live days of raw exposure. Three of the germanium and both silicon detectors were analyzed with a new low-threshold technique, making it possible to lower the germanium and silicon analysis thresholds down to the actual trigger thresholds of $\sim 1$ and $\sim 2\mathrm{keV}$, respectively. Limits on the spin-independent cross section for weakly interacting massive particles (WIMPs) to elastically scatter from nuclei based on these data exclude interesting parameter space for WIMPs with masses below $9\mathrm{GeV}/c^2$. Under standard halo assumptions, these data partially exclude parameter space favored by interpretations of the DAMA/LIBRA and CoGeNT experiments’ data as WIMP signals, and exclude new parameter space for WIMP masses between 3 and $4\mathrm{GeV}/c^2$.

We find a solution to the strong $CP$ problem that may be testable at the LHC and future colliders. In this solution $CP$ is broken by parity conserving terms, while parity breaking vacuum expectation values conserve $CP$. The quark mass matrix is Hermitian at the tree level, and the strong $CP$ phase is generated only in loops where $CP$ and $P$ violating sectors interact. A full vectorlike quark family with parity symmetric mass terms that violate $CP$ softly is predicted. Since no Higgs vacuum expectation values [other than the $SU(2{)}_L$ breaking weak-scale vacuum expectation value] contribute to the masses of the new quarks, they can be naturally light, independent of parity breaking and other high energy scales.

In the $SO(5)\times U(1)$ gauge-Higgs unification model in the Randall-Sundrum warped space, there results the conservation of the $H$ parity. The $H$ parity is assigned to all 4D fields including excited modes in Kaluza-Klein towers. The neutral Higgs boson is the lightest particle of odd $H$ parity, consequently becoming absolutely stable. Its mass is found to be $70–135\mathrm{GeV}$ for the warp factor $z_L={10}^5–{10}^{15}$.

We study a simple two-Higgs-doublet model in the Randall-Sundrum scenario, with an IR brane localized Higgs field and a second doublet arising from a $t\overline{t}$ condensate due to strong Kaluza-Klein gluon effects. The effective two-Higgs-doublet model predicts that the ratio of the brane to condensate vacuum expectation values $\tan \beta \sim 3$. It also predicts a standard-model-like Higgs boson of mass $\mathcal{O}(100)\mathrm{GeV}$ and a heavier scalar at the scale of the lowest Kaluza-Klein gluon mass, which we take to be $M_{\mathrm{KK}}\gtrsim 1.5\mathrm{TeV}$. The pseudoscalar and the charged scalars are degenerate in mass at tree level and are $\mathcal{O}(M_{\mathrm{KK}})$. There are no tree-level flavor-changing neutral currents for the down-type quarks and the standard model results hold there. In contrast, flavor-changing neutral current decays of the $t$ quark larger than in the standard model are expected.

Triggering the electroweak symmetry breaking may not be the only key role played by the Higgs boson in particle physics. In a recently proposed warped five-dimensional $SO(5)\otimes U(1)$ gauge-Higgs unification model, the Higgs boson can also constitute the dark matter that permeates the universe. The stability of the Higgs boson in this model is guaranteed in all orders of perturbation theory by the conservation of an H-parity quantum number that forbids triple couplings to all standard model (SM) particles. Such a unique feature of the model shows up as a delay in the restoration of the tree-level unitarity, which in turn enhances the production cross section as compared to the standard model analogue. Recent astrophysical data constrain the mass of such a Higgs dark matter particle to a narrow window of 70–90 GeV range. We show that the Large Hadron Collider can observe these Higgs bosons in the weak boson fusion channel with about $260{\mathrm{fb}}^{-1}$ of integrated luminosity in that mass range.

Center vortices are studied in $SU(3)$ gauge theory using maximal center gauge (MCG) fixing. Stout link smearing and over-improved stout link smearing are used to construct a preconditioning gauge-field transformation which is applied to the original gauge field before fixing to MCG. We find that preconditioning successfully achieves higher maxima of the gauge functional used in MCG. We observe a reduction in the number of identified vortices when this preconditioning method is used, and also a reduction in the string tension as measured on the identified vortex matter.

We apply novel jet techniques to investigate the spin and $\mathcal{C}\mathcal{P}$ quantum numbers of a heavy resonance $X$, singly produced in $pp\to X\to ZZ\to {\ell }^{+}{\ell }^{-}jj$ at the LHC. We take into account all dominant background processes to show that this channel, which has been considered unobservable until now, can qualify under realistic conditions to supplement measurements of the purely leptonic decay channels $X\to ZZ\to 4\ell$. We perform a detailed investigation of spin- and $\mathcal{C}\mathcal{P}$-sensitive angular observables on the fully simulated final state for various spin and $\mathcal{C}\mathcal{P}$ quantum numbers of the state $X$, tracing how potential sensitivity communicates through all the steps of a subjet analysis. This allows us to elaborate on the prospects and limitations of performing such measurements with the semihadronic final state. We find our analysis particularly sensitive to a $\mathcal{C}\mathcal{P}$-even or $\mathcal{C}\mathcal{P}$-odd scalar resonance, while, for tensorial and vectorial resonances, discriminative features are diminished in the boosted kinematical regime.

We report a parton distribution function analysis of a complete set of hadron scattering data, in which a color-octet fermion (such as a gluino of supersymmetry) is incorporated as an extra parton constituent along with the usual standard model constituents. The data set includes the most up-to-date results from deep inelastic scattering and from jet production in hadron collisions. Another feature is the inclusion in the fit of data from determinations of the strong coupling ${\alpha }_s(Q)$ at large and small values of the hard scale $Q$. Our motivation is to determine the extent to which the global parton distribution function analysis may provide constraints on the new fermion, as a function of its mass and ${\alpha }_s(M_Z)$, independent of assumptions such as the mechanism of gluino decays. Based on this analysis, we find that gluino masses as low as 30 to 50 GeV may be compatible with the current hadronic data. Gluino masses below 15 GeV (25 GeV) are excluded if ${\alpha }_s(M_Z)$ varies freely (is equal to 0.118). At the outset, stronger constraints had been anticipated from jet production cross sections, but experimental systematic uncertainties, particularly in normalization, reduce the discriminating power of these data.

We show that the polarized proton-antiproton Drell-Yan process is ideal to probe the pretzelosity distribution ($h_{1T}^{\perp }$), which is one of the new transverse-momentum-dependent parton distributions of the nucleon. We present predictions of the $\cos (2\varphi +{\varphi }_a-{\varphi }_b)$ asymmetry in the transversely polarized proton-antiproton Drell-Yan process at PAX kinematics and find that the results are significantly larger compared with those of the $\sin (3{\varphi }_h-{\varphi }_S)$ asymmetry in the semi-inclusive deep inelastic scattering process at HERMES, COMPASS, and JLab kinematics. We conclude that the $\cos (2\varphi +{\varphi }_a-{\varphi }_b)$ asymmetry in the PAX experiment can probe the new physical quantity of the pretzelosity distribution.

A Borel summation scheme of subtracting the perturbative contribution from the average plaquette is proposed using the bilocal expansion of the Borel transform. It is shown that the remnant of the average plaquette, after subtraction of the perturbative contribution, scales as a dim-4 condensate. A critical review of the existing procedure of renormalon subtraction is presented.

We present a phenomenological constraint on a long-range spin-dependent interaction ${\alpha }^{\prime \prime }({\mathbf{s}}_1·{\mathbf{s}}_2){\mathrm{e}}^{-\lambda r}/r$, which can be induced by a pseudovector light boson beyond the standard model. In the range of masses from $4\mathrm{keV}/c^2$ to those related to macroscopic distances (${\lambda }^{-1}\sim 1\mathrm{cm}$) the spin-dependent coupling constant ${\alpha }^{\prime \prime }$ of the electron-muon interaction is constrained at the level below a part in ${10}^{15}$. The constraint is weakened if extended to higher masses. The strongest constraint is related to the lepton-lepton interaction. Constraints on spin-dependent interactions of an electron with some other particles are also discussed. The results are obtained from data on the hyperfine splitting (HFS) interval of the ground state in muonium and a few other light hydrogenlike atoms.

We report the first determination of the relative strong-phase difference between $D^0\to K_{S,L}^0{K}^{+}{K}^{-}$ and ${\overline{D}}^0\to K_{S,L}^0{K}^{+}{K}^{-}$. In addition, we present updated measurements of the relative strong-phase difference between $D^0\to K_{S,L}^0{\pi }^{+}{\pi }^{-}$ and ${\overline{D}}^0\to K_{S,L}^0{\pi }^{+}{\pi }^{-}$. Both measurements exploit the quantum coherence between a pair of $D^0$ and ${\overline{D}}^0$ mesons produced from $\psi (3770)$ decays. The strong-phase differences measured are important for determining the Cabibbo-Kobayashi-Maskawa angle $\gamma /{\varphi }_3$ in $B^{-}\to K^{-}{\tilde{D}}^0$ decays, where ${\tilde{D}}^0$ is a $D^0$ or ${\overline{D}}^0$ meson decaying to $K_S^0{h}^{+}{h}^{-}$ ($h=\pi$, $K$), in a manner independent of the model assumed to describe the $D^0\to K_S^0{h}^{+}{h}^{-}$ decay. Using our results, the uncertainty in $\gamma /{\varphi }_3$ due to the error on the strong-phase difference is expected to be between 1.7° and 3.9° for an analysis using $B^{-}\to K^{-}{\tilde{D}}^0$, ${\tilde{D}}^0\to K_S^0{\pi }^{+}{\pi }^{-}$ decays, and between 3.2° and 3.9° for an analysis based on $B^{-}\to K^{-}{\tilde{D}}^0$, ${\tilde{D}}^0\to K_S^0{K}^{+}{K}^{-}$ decays. A measurement is also presented of the $CP$-odd fraction, ${\mathcal{F}}_{-}$, of the decay $D^0\to K_S^0{K}^{+}{K}^{-}$ in the region of the $\varphi \to K^{+}{K}^{-}$ resonance. We find that in a region within $0.01{\mathrm{GeV}}^2/c^4$ of the nominal $\varphi$ mass squared ${\mathcal{F}}_{-}>0.91$ at the 90% confidence level.

Based on $122\times {10}^6\mathit{{\rm Y}}(3S)$ events collected with the BABAR detector, we have observed the $\mathit{{\rm Y}}(1^3{D}_J)$ bottomonium state through the $\mathit{{\rm Y}}(3S)\to \gamma \gamma \mathit{{\rm Y}}(1^3{D}_J)\to \gamma \gamma {\pi }^{+}{\pi }^{-}\mathit{{\rm Y}}(1S)$ decay chain. The significance for the $J=2$ member of the $\mathit{{\rm Y}}(1^3{D}_J)$ triplet is 5.8 standard deviations including systematic uncertainties. The mass of the $J=2$ state is determined to be $10164.5\pm 0.8(\mathrm{stat})\pm 0.5(\mathrm{syst})\mathrm{MeV}/c^2$. We use the ${\pi }^{+}{\pi }^{-}$ invariant mass distribution to confirm the consistency of the observed state with the orbital angular momentum assignment of the $\mathit{{\rm Y}}(1^3{D}_J)$.

We correct two errors in our previous computation of one-loop corrections to the vortex string tension: (i) the contribution of the longitudinal and timelike modes of the gauge fields were forgotten and are included now; (ii) a trivial error in the numerical code has led to considerable errors in the subtracted integrals. We here present the corrected results.