In this article we have calculated the spin-independent cross section of nucleon-dark matter scattering process at loop level, which is relevant to dark matter direct detection. Paying particular attention to the scattering of gluon with dark matter, which contributes as leading order in the perturbation, we have systematically evaluated loop diagrams with tracking the characteristic loop momentum which dominates in the loops. Here loop diagrams whose typical loop momentum scales are the masses of quarks and other heavier particles are separately presented. Then, we have properly taken into account each contribution to give the cross section. We assume that the dark matter is pure bino or wino in the supersymmetric models. The application to other models is straightforward.

We present a new study of $D$ semileptonic decays on the lattice which employs the highly improved staggered quark action for both the charm and the light valence quarks. We work with MILC unquenched $N_f=2+1$ lattices and determine the scalar form factor $f_0(q^2)$ for $D\to K$, $l\nu$ semileptonic decays. The form factor is obtained from a scalar current matrix element that does not require any operator matching. We develop a new approach to carrying out chiral/continuum extrapolations of $f_0(q^2)$. The method uses the kinematic “$z$”variable instead of $q^2$ or the kaon energy $E_K$ and is applicable over the entire physical $q^2$ range. We find $f_0^{D\to K}(0)\equiv f_{+}^{D\to K}(0)=0.747(19)$ in the chiral plus continuum limit and hereby improve the theory error on this quantity by a factor of $\sim 4$ compared to previous lattice determinations. Combining the new theory result with recent experimental measurements of the product $f_{+}^{D\to K}(0)*|V_{cs}|$ from BABAR and CLEO-c leads to a very precise direct determination of the CKM matrix element $|V_{cs}|$, $|V_{cs}|=0.961(11)(24)$, where the first error comes from experiment and the second is the lattice QCD theory error. We calculate the ratio $f_{+}^{D\to K}(0)/f_{D_s}$ and find $2.986\pm 0.087{\mathrm{GeV}}^{-1}$ and show that this agrees with experiment.

We study the thermodynamics of $\mathrm{SU}(N_c)$ pure gauge theories for $N_c=3$, 4 and 6. The continuum and thermodynamic limits of bulk quantities such as the pressure ($p$), energy density ($ϵ$) and the entropy density ($s$) are taken by using several different lattice spacings and volumes. There is no window of temperature in which a nontrivial conformal theory describes bulk thermodynamics. We extract the latent heat of the first-order deconfinement phase transitions and observe good scaling with $N_c$. For all quantities that we measure, strong $N_c$ scaling holds, except, possibly, very close to the transition temperature, $T_c$; however we are unable to find strong evidence for scaling with the ’t Hooft coupling in thermal quantities at the small values of $N_c$ which we study.

We update our previous determination of both the decay constant and the mass of the $D_s$ meson using the highly improved staggered quark formalism. We include additional results at two finer values of the lattice spacing along with improved determinations of the lattice spacing and improved tuning of the charm and strange quark masses. We obtain $m_{D_s}=1.9691(32)\mathrm{GeV}$, in good agreement with experiment, and $f_{D_s}=0.2480(25)\mathrm{GeV}$. Our result for $f_{D_s}$ is $1.6\sigma$ lower than the most recent experimental average determined from the $D_s$ leptonic decay rate and using $V_{cs}$ from Cabibbo-Kobayashi-Maskawa unitarity. Combining our $f_{D_s}$ with the experimental rate we obtain a direct determination of $V_{cs}=1.010(22)$, or alternatively $0.990\genfrac{}{}{0ex}{}{+0.013}{-0.016}$ using a probability distribution for statistical errors for this quantity which vanishes above 1. We also include an accurate prediction of the decay constant of the ${\eta }_c$, $f_{{\eta }_c}=0.3947(24)\mathrm{GeV}$, as a calibration point for other lattice calculations.

We evaluate the rare radiative kaon decays $K_{\mathrm{L},\mathrm{S}}\to 3\gamma$. Applying the requirements of gauge invariance and Bose symmetry, we derive a general form of the decay amplitude, including both parity-conserving and parity-violating contributions. We subsequently employ a chiral-Lagrangian approach combined with dimensional-analysis arguments to estimate the branching ratios of these decays in the standard model. The results are $1\times {10}^{-19}\lesssim \mathcal{B}(K_{\mathrm{L}}\to 3\gamma )\lesssim 7\times {10}^{-17}$ and $2\times {10}^{-22}\lesssim \mathcal{B}(K_{\mathrm{S}}\to 3\gamma )\lesssim 1\times {10}^{-19}$, the upper limits exceeding the predictions made previously by a few orders of magnitude. Measurements on the branching ratios which are significantly larger than these numbers would likely hint at the presence of new physics beyond the standard model.

We study the initial and final state interaction effects in the transverse momentum dependent parton distributions in the small-$x$ saturation region. In particular, we discuss the quark distributions in the semi-inclusive deep inelastic scattering, Drell-Yan lepton pair production, and dijet-correlation processes in $pA$ collisions. We calculate the quark distributions in the scalar-QED model and then extend to the color glass condensate formalism in QCD. The quark distributions are found universal between the deep inelastic scattering and Drell-Yan processes. On the other hand, the quark distribution from the $q{q}^{\prime }\to q{q}^{\prime }$ channel contribution to the dijet-correlation process is not universal. However, we find that it can be related to the quark distribution in deep inelastic scattering process by a convolution with the normalized unintegrated gluon distribution in the color glass condensate formalism in the large $N_c$ limit.

We consider contributions of nonstandard $tbW$ effective operators to the decay of an unpolarized top quark into a bottom quark and a $W$ gauge boson at next-to-leading order in QCD. We find that ${\mathcal{O}}_{LR}\equiv {\overline{b}}_L{\sigma }_{\mu \nu }{t}_R{W}^{\mu \nu }$ contribution to the transverse-plus $W$ helicity fraction (${\mathcal{F}}_{+}$) is significantly enhanced compared to the leading order result at nonvanishing bottom quark mass. Nonetheless, presently the most sensitive observable to direct ${\mathcal{O}}_{LR}$ contributions is the longitudinal $W$ helicity fraction ${\mathcal{F}}_L$. In particular, the most recent CDF measurement of ${\mathcal{F}}_L$ already provides the most stringent upper bound on ${\mathcal{O}}_{LR}$ contributions, even when compared with indirect bounds from the rare decay $B\to X_s\gamma$.

Many extensions of the standard model predict the existence of extra neutral vector bosons, generically referred as $Z^{\prime }$. This boson may be discovered at the LHC but in this case it will be necessary to study the respective parameters in order to discriminate to which model it belongs to. This is a task for a much clean lepton linear collider as the future International Linear Collinear. In this paper we develop an exemplary study of the capability of several asymmetries on and off $Z^{\prime }$ peak in discriminating among those extensions with (almost) no ambiguities.

A search for sidereal modulation in the flux of atmospheric muon neutrinos in IceCube was performed. Such a signal could be an indication of Lorentz-violating physics. Neutrino oscillation models, derivable from extensions to the standard model, allow for neutrino oscillations that depend on the neutrino’s direction of propagation. No such direction-dependent variation was found. A discrete Fourier transform method was used to constrain the Lorentz and $CPT$-violating coefficients in one of these models. Because of the unique high energy reach of IceCube, it was possible to improve constraints on certain Lorentz-violating oscillations by 3 orders of magnitude with respect to limits set by other experiments.

A numerical study of the ghost Dyson–Schwinger equation in Coulomb gauge is performed and solutions for the ghost propagator found. As input, lattice results for the spatial gluon propagator are used. It is shown that in order to solve completely, the equation must be supplemented by a nonperturbative boundary condition (the value of the inverse ghost propagator dressing function at zero momentum), which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until forced to freeze out in the infrared to the value of the boundary condition. The renormalization is shown to be largely independent of the boundary condition. The boundary condition and the pattern of the solutions can be interpreted in terms of the Gribov gauge-fixing ambiguity. The connection to the temporal gluon propagator and the infrared slavery picture of confinement is explored.

Assuming the hoop conjecture in classical general relativity and quantum mechanics, any observer who attempts to perform a localized experiment in an arbitrarily small region will be stymied by the formation of a trapped surface within the spatial domain of the experiment. This thought experiment is frequently invoked in arguments for a fundamental minimum length in physics, which in turn is usually considered to be fairly independent of observer or experimental setup. We examine this conclusion in asymptotically safe gravity by modifying a proof of the hoop conjecture for spherically symmetric systems in general relativity to include higher curvature terms in the effective action as well as running couplings. We show that the modified proof fails, and so the argument for the mandatory formation of a trapped surface within the domain of an experiment also falls apart in this context. However, neither is there any contrary proof that local trapped surfaces do not form. Instead, in this approach whether or not an observer can perform local measurements in arbitrarily small regions depends on the specific numerical values of the couplings near the UV fixed point. In this sense, there is no longer any purely local version of the minimum length argument. However, when an experiment is localized to be much smaller than the Planck length we argue that at least one trapped surface must still form outside the experiment. This enshrouding horizon precludes any local information from reaching infinity and so there is still an effective minimum length for observers at infinity.

We compare different methods of computing the orbital eccentricity of quasicircular binary black-hole systems using the orbital variables and gravitational-wave phase and frequency. For eccentricities of about a per cent, most methods work satisfactorily. For small eccentricity, however, the gravitational-wave phase allows a particularly clean and reliable measurement of the eccentricity. Furthermore, we measure the decay of the orbital eccentricity during the inspiral and find reasonable agreement with post-Newtonian results. Finally, we measure the periastron advance of nonspinning binary black holes, and we compare them to post-Newtonian approximations. With the low uncertainty in the measurement of the periastron advance, we positively detect deviations between fully numerical simulations and post-Newtonian calculations.

We present a complete, viable model of gravity-mediated supersymmetry breaking that is safe from all flavor constraints. The central new idea is to employ a supersymmetry breaking sector without singlets, but with $D$-terms comparable to $F$-terms, causing supersymmetry breaking to be dominantly communicated through $\mathrm{U}(1{)}_R$-symmetric operators. We construct a visible sector that is an extension of the minimal supersymmetric standard model where an accidental $\mathrm{U}(1{)}_R$-symmetry emerges naturally. Gauginos acquire Dirac masses from gravity-mediated $D$-terms and tiny Majorana masses from anomaly-mediated contributions. Contributions to soft breaking scalar $(\mathrm{mass}{)}^2$ arise from flavor-arbitrary gravity-induced $F$-terms plus one-loop finite flavor-blind contributions from Dirac gaugino masses. Renormalization group evolution of the gluino causes it to naturally increase nearly an order of magnitude larger than the squark masses. This hierarchy, combined with an accidentally $\mathrm{U}(1{)}_R$-symmetric visible sector, nearly eliminates all flavor violation constraints on the model. If we also freely tune couplings and phases within the modest range 0.1–1, while maintaining nearly flavor-anarchic Planck-suppression contributions, we find our model to be safe from $\Delta m_K$, ${ϵ}_K$, and $\mu \to e$ lepton flavor violation. Dangerous $\mathrm{U}(1{)}_R$-violating Kähler operators in the Higgs sector are eliminated through a new gauged $\mathrm{U}(1{)}_X$ symmetry that is spontaneously broken with electroweak symmetry breaking. Kinetic mixing between $\mathrm{U}(1{)}_X$ and $\mathrm{U}(1{)}_Y$ is present with loop-suppressed (but log-enhanced) size $ϵ$. The $Z^{\prime }$ associated with this $\mathrm{U}(1{)}_X$ has very peculiar couplings—it has order one strength to Higgs doublets and approximately $ϵ$ strength to hypercharge. The $Z^{\prime }$ could be remarkably light and yet have escaped direct and indirect detection.

Experiments designed to measure neutrino oscillations also provide major opportunities for discovering very weakly-coupled states. In order to produce neutrinos, experiments such as Liquid Scintillator Neutrino Detector collide thousands of Coulombs of protons into fixed targets, while MINOS and MiniBooNE also focus and then dump beams of muons. The neutrino detectors beyond these beam dumps are therefore an excellent arena in which to look for long-lived pseudoscalars or for vector bosons that kinetically mix with the photon. We show that these experiments have significant sensitivity beyond previous beam dumps and are able to partially close the gap between laboratory experiments and supernovae constraints on pseudoscalars. Future upgrades to the NuMI beamline and Project X will lead to even greater opportunities for discovery. We also discuss thin target experiments with muon beams, such as those available in COMPASS, and show that they constitute a powerful probe for leptophilic pseudo-Nambu-Goldstones.

We present a search for the rare decays $B^{+}\to K^{+}\nu \overline{\nu }$ and $B^0\to K^0\nu \overline{\nu }$ using $459\times {10}^6$ $B\overline{B}$ pairs collected with the BABAR detector at the SLAC National Accelerator Laboratory. Flavor-changing neutral-current decays such as these are forbidden at tree level but can occur through one-loop diagrams in the standard model (SM), with possible contributions from new physics at the same order. The presence of two neutrinos in the final state makes identification of signal events challenging, so reconstruction in the semileptonic decay channels $B\to D^{(*)}l\nu$ of the $B$ meson recoiling from the signal $B$ is used to suppress backgrounds. We set an upper limit at the 90% confidence level (CL) of $1.3\times {10}^{-5}$ on the total branching fraction for $B^{+}\to K^{+}\nu \overline{\nu }$, and $5.6\times {10}^{-5}$ for $B^0\to K^0\nu \overline{\nu }$. We additionally report 90% CL upper limits on partial branching fractions in two ranges of dineutrino mass squared for $B^{+}\to K^{+}\nu \overline{\nu }$.

Iodine is distinguished from other elements used in dark matter direct detection experiments both by its large mass as well as its large magnetic moment. Inelastic dark matter utilizes the large mass of iodine to allay tensions between the dark matter (DAMA) annual modulation signature and the null results from other experiments. We explore models of inelastic dark matter that also take advantage of the second distinct property of iodine, namely, its large magnetic moment. In such models the couplings are augmented by magnetic, rather than merely electric, interactions. These models provide simple examples where the DAMA signal is compatible with all existing limits. We consider dipole moments for the WIMP, through conventional magnetism as well as dark magnetism, including both magnetic-magnetic and magnetic-electric scattering. We find XENON100 and Cryogenic Rare Event Search with Superconducting Thermometers (CRESST) should generically see a signal although suppressed compared with electric inelastic dark matter models, while Korea Invisible Mass Search (KIMS) should see a modulated signal comparable to or larger than that of DAMA. In a large portion of parameter space, deexcitation occurs promptly, producing a $\sim 100\mathrm{keV}$ photon inside large xenon experiments alongside the nuclear recoil. This effect could be searched for, but if not properly considered may cause nuclear recoil events to fail standard cuts.

In the decoupling limit, the Dvali-Gabadadze-Porrati model reduces to the theory of a scalar field $\pi$, with interactions including a specific cubic self-interaction—the Galileon term. This term, and its quartic and quintic generalizations, can be thought of as arising from a probe 3-brane in a five-dimensional bulk with Lovelock terms on the brane and in the bulk. We study multifield generalizations of the Galileon and extend this probe-brane view to higher codimensions. We derive an extremely restrictive theory of multiple Galileon fields, interacting through a quartic term controlled by a single coupling, and trace its origin to the induced brane terms coming from Lovelock invariants in the higher codimension bulk. We explore some properties of this theory, finding de Sitter like self-accelerating solutions. These solutions have ghosts if and only if the flat space theory does not have ghosts. Finally, we prove a general nonrenormalization theorem: multifield Galileons are not renormalized quantum mechanically to any loop in perturbation theory.

We develop analytic solutions for the linear evolution of metric perturbations in the Dvali-Gabadadze-Porrati braneworld modified gravity scenario including near-horizon and superhorizon modes where solutions in the bulk are required. These solutions apply to both the self-accelerating and normal branch and elucidate the nature of coordinate singularities and initial data in the bulk as well as their effect on perturbation evolution on the brane. Even on superhorizon scales, the evolution of metric perturbations is no longer necessarily scale free due to multiple resonances in the bulk. Based on these analytic solutions, we devise convenient fitting functions for the evolutions that bridge the various spatial and temporal regimes. Compared with a direct numerical integration of the bulk equations, the fits are accurate at the percent level and are sufficient for current and upcoming observational tests.

In 1998, Shibata and Sasaki [Phys. Rev. D 58, 104011 (1998)] presented an approximate analytical formula for the radius of the innermost stable circular orbit (ISCO) of a neutral test particle around a massive, rotating, and deformed source. In the present paper, we generalize this expression by including the magnetic dipole moment. We show that our approximate analytical formula is accurate enough by comparing it with the six-parametric exact solution calculated by Pachón et. al. [Phys. Rev. D 73, 104038 (2006)] along with the numerical data presented by Berti and Stergioulas [Mon. Not. R. Astron. Soc. 350, 1416 (2004)] for realistic neutron stars. As a main result, we find that in general, the radius at ISCO exhibits a decreasing behavior with an increasing magnetic field. However, for magnetic fields below 100 GT the variation of the radius at ISCO is negligible and hence the nonmagnetized approximate expression can be used. In addition, we derive approximate analytical formulas for angular velocity, energy, and angular momentum of the test particle at ISCO.

We propose a new method for obtaining the four-dimensional effective gravitational theory for five-dimensional braneworld models with arbitrary numbers of branes in a low-energy regime, based on a two-length-scale expansion. The method is straightforward and computationally efficient, and is applicable to both compactified and uncompactified models. Particular emphasis is placed on the behavior of the radion modes of the model, while the massive effective fields are automatically truncated. Generally, the radion modes are found to form an ($N-1$)-dimensional nonlinear sigma model. We illustrate the method for a $N$-brane model in an uncompactified extra dimension.