We point out that for a range of parameters, the flux of DM may be stopped significantly by its interactions with the Earth. This can significantly degrade the sensitivity of direct detection experiments to DM candidates with large interactions with terrestrial nuclei. We find that a significant region of parameter space remains unconstrained for DM $\lesssim$ a few GeV. For DM candidates with moderate levels of stopping power, the flux of DM may be blocked from below but not above a detector, thereby producing a novel daily modulation. This can be explored by low threshold detectors placed on the surface or in shallow sites in the south hemisphere.

During the 2014 summer conferences, both the ATLAS and CMS Collaborations of the LHC experiments have demonstrated tremendous efforts in treatment of data and processing more data such that most data on signal strengths have improved, especially the diphoton and fermionic modes of both experiments. Here in this paper we perform an update to our previous model-independent Higgs precision analysis—Higgcision. We found the following: (i) the uncertainties on most couplings shrink about 10%–20%, (ii) the nonstandard (e.g. invisible) decay branching ratio of the Higgs boson is constrained to be less than 19% if only the width is allowed to vary, (iii) the gauge-Higgs coupling $C_v$ is constrained to be ${0.94}_{-0.12}^{+0.11}$, in which the uncertainty is reduced by about 10%, and (iv) the standard model (SM) Higgs boson still provides the best fit to all the Higgs boson data, and compared to the previous results the SM Higgs boson now enjoys a higher $p$ value than the last year.

Observables sensitive to top-quark polarization are important for characterizing or even discovering new physics. The most powerful spin analyzer in top decay is the down-type fermion from the $W$, which in the case of leptonic decay allows for very clean measurements. However, in many applications it is useful to measure the polarization of hadronically decaying top quarks. Usually it is assumed that at most 50% of the spin analyzing power can be recovered in this case. This paper introduces a simple and truly optimal hadronic spin analyzer, with a power of 64% at leading order (LO). The improvement is demonstrated to be robust at next-to-leading order, and in a handful of simulated measurements including the spins and spin correlations of boosted top quarks from multi-TeV $t\overline{t}$ resonances, the spins of semi-boosted tops from chiral top-squark decays, and the potentially $CP$-violating spin correlations induced in continuum $t\overline{t}$ by color-dipole operators. For the boosted studies, we explore jet substructure techniques that exhibit improved mapping between subjets and quarks.

The need for ever higher energies in lepton colliders gives rise to the investigation of new accelerator schemes for elementary particle physics experiments. One perceivable way to increase the collision energy would be to combine conventional lepton acceleration with strong laser fields, making use of the momentum boost a charged particle experiences inside a plane electromagnetic wave. As an example for a process taking place in such a laser-boosted collision, Higgs boson creation is studied in detail. We further discuss other possible particle production processes that could be implemented in such a collider scheme and specify the required technical demands.

We make predictions for the ratios of branching fractions of ${\overline{B}}^0$ and ${\overline{B}}_s^0$ decays into $J/\psi$ and the scalar mesons $f_0(1370)$, $f_0(1710)$ or tensor mesons $f_2(1270)$, $f_2^{\prime }(1525)$, $K_2^{*}(1430)$. The theoretical approach is based on results of chiral unitary theory where these resonances are shown to be generated from the vector meson–vector meson interaction. Eight independent ratios can be predicted, and comparison is made with the recent data on ${\overline{B}}_s^0$ decay into $J/\psi f_2^{\prime }(1525)$ versus the ${\overline{B}}_s^0$ decay into $J/\psi f_2(1270)$.

We discuss the implementation of the nuclear model based on realistic nuclear spectral functions in the GENIE neutrino interaction generator. Besides improving on the Fermi gas description of the nuclear ground state, our scheme involves a new prescription for $Q^2$ selection, meant to efficiently enforce energy-momentum conservation. The results of our simulations, validated through comparison to electron scattering data, have been obtained for a variety of target nuclei, ranging from carbon to argon, and cover the kinematical region in which quasielastic scattering is the dominant reaction mechanism. We also analyze the influence of the adopted nuclear model on the determination of neutrino oscillation parameters.

Using the boundary state formalism we obtain the partition function corresponding to a dynamical (rotating-moving) $\mathrm{D}p$-brane in the presence of electromagnetic and tachyonic background fields in the superstring theory. The instability of such a $\mathrm{D}p$-brane due to the tachyon condensation is investigated.

We describe the simplest example of an instanton bag in Euclidean space. It consists of a monopole wall and a Kaluza-Klein monopole wall, lifted to one higher dimension, trapping the instanton charge in the middle. This object has finite instanton density in a three-dimensional volume. Baryon physics in holographic QCD models gets translated into a multi-instanton problem in the bulk, and a state with a high density baryonic charge consists of a nondiluted multi-instanton solution. The instanton bag is a good candidate for this high-density state. We compute its parameters via moduli stabilization. Chiral symmetry restoration is exhibited by this state, and it is a direct consequence of its nondiluted features.

We consider asymptotically free nonlinear sigma models in two dimensions which, due to their internal symmetries, allow for a conserved charge. Introducing nonzero chemical potential for the $SO(2)$ subgroup of the symmetry group, we discuss two expected phase transitions, which are related to charge condensation and percolation of merons, respectively. The latter are topological objects with half integer charge similar to vortices in the Abelianized $O(2)$ theory that emerge for large chemical potentials due to the suppression of the complementary field components. We conjecture a particular ordering of these transitions supported by large $N$ calculations, and discuss dualities helpful for the understanding of these systems in the continuum and on the lattice. We suggest that a similar behavior is to be expected in QCD at nonzero density.

In this work we review the application of the theory of Gaussian processes to the modeling of noise in pulsar-timing data analysis, and we derive various useful and optimized representations for the likelihood expressions that are needed in Bayesian inference on pulsar-timing-array data sets. The resulting viewpoint and formalism lead us to two improved parameter-sampling schemes inspired by Gibbs sampling. The new schemes have vastly lower chain autocorrelation lengths than the Markov-chain Monte Carlo methods currently used in pulsar-timing data analysis, potentially speeding up Bayesian inference by orders of magnitude. The new schemes can be used for a full-noise-model analysis of the large data sets currently being assembled by pulsar-timing-array collaborations, which generally present a serious computational challenge to existing methods.

The population of stellar-mass, compact object binaries that merge with non-negligible eccentricity may be large enough to motivate searches with ground-based gravitational wave detectors. Such events could be exceptional laboratories to test General Relativity in the dynamical, strong-field regime, as a larger fraction of the energy is emitted at high velocities, compared to quasicircular inspirals. A serious obstacle here, however, is the challenge of computing theoretical waveforms for eccentric systems with the requisite accuracy for use in a matched-filter search. The corresponding waveforms are more a sequence of concentrated bursts of energy emitted near periapse than a continuous waveform. Based on this, an alternative approach, stacking excess power over the set of time-frequency tiles coincident with the bursts, was recently suggested as a more practical (though suboptimal) detection strategy. The leading-order “observable” that would be inferred from such a detection would be a sequence of discrete numbers characterizing the position and size of each time-frequency tile. In General Relativity, this (possibly large) sequence of numbers is uniquely determined by the small set of parameters describing the binary at formation. In this paper, following the spirit of the parametrized post-Einsteinian framework developed for quasicircular inspiral, we propose a simple, parametrized deformation of the baseline general relativistic burst algorithm for eccentric inspiral events that would allow for model-independent tests of Einstein’s theory in this high-velocity, strong-field regime.

The recent measurements of the cosmic microwave background anisotropies provided by the Planck satellite experiment have significantly improved the constraints on several cosmological parameters. In this brief paper we point out a small but interesting tension present between recent values of the primordial deuterium measured from quasar absorption line systems and the same value inferred, albeit indirectly, from the Planck measurements assuming $\mathrm{\Lambda }\mathrm{CDM}$ and big bang nucleosynthesis. Here we discuss this tension in detail investigating the possible new physics that could be responsible for the tension. We found that, among 8 extra parameters, only an anomalous lensing component and a closed universe could change the Planck constraint towards a better consistency with direct deuterium measurements.

The apparent excess of gamma rays in an extended region in the direction of the Galactic Center has a spatial distribution and amplitude that are suggestive of dark matter annihilations. If this excess is indeed due to dark matter annihilations, it would indicate the presence of both dark matter and an additional particle beyond the Standard Model that mediates the interactions between the dark matter and Standard Model states. We introduce reference models describing dark matter annihilation to pairs of these new mediators, which decouples the SM-mediator coupling from the thermal annihilation cross section and easily explains the lack of direct detection signals. We determine the parameter regions that give good descriptions of the gamma-ray excess for several motivated choices of mediator couplings to the SM. We find fermion dark matter with mass 7–26 GeV and a dark vector mediator, or scalar dark matter in the 10–50 GeV range (Higgs portal mediator) or 10–65 GeV range (gluophilic mediator) can provide a comparable or improved fit, compared to the case of direct annihilation. We demonstrate that these models can easily satisfy all constraints from collider experiments, direct detection, and cosmology.

We revisit the cosmological viability of the Hu-Sawicki modified gravity scenario. The impact of such a modification on the different cosmological observables, including gravitational waves, is carefully described. The most recent cosmological data, as well as constraints on the relationship between the clustering parameter ${\sigma }_8$ and the current matter mass-energy density ${\mathrm{\Omega }}_m$ from cluster number counts and weak lensing tomography, are considered in our numerical calculations. The strongest bound we find is $|f_{R0}|<3.7\times {10}^{-6}$ at 95% C.L. Forthcoming cluster surveys covering $10000{\mathrm{deg}}^2$ in the sky, with galaxy surface densities of $\mathcal{O}(10){\mathrm{arcmin}}^{-2}$ could improve the precision in the ${\sigma }_8$-${\mathrm{\Omega }}_m$ relationship, tightening the above constraint.

We consider cosmological inflationary models in which vector fields play some role in the generation of the primordial curvature perturbation $\zeta$. Such models are interesting because the involved vector fields naturally seed statistical anisotropy in the primordial fluctuations which could eventually leave a measurable imprint on the cosmic microwave background fluctuations. In this article, we estimate the scale and shape dependent effects on the non-Gaussianity (NG) parameters due to the scale dependent statistical anisotropy in the distribution of the fluctuations. For concreteness, we use a power spectrum (PS) of the fluctuations of the quadrupolar form: $P_{\zeta }(\overrightarrow{k})\equiv P_{\zeta }(k)[1+g_{\zeta }(k)(\widehat{n}·\widehat{k}{)}^2]$, where $g_{\zeta }(k)$ is the only quantity which parametrizes the level of statistical anisotropy and $\widehat{n}$ is a unitary vector which points towards the preferred direction. Then, we evaluate the contribution of the running of $g_{\zeta }(k)$ on the NG parameters by means of the $\delta N$ formalism. We focus specifically on the details for the $f_{\mathrm{NL}}$ NG parameter, associated with the bispectrum $B_{\zeta }$, but the structure of higher order NG parameters is straightforward to generalize. Although the level of statistical anisotropy in the power spectrum is severely constrained by recent observations, the importance of statistical anisotropy signals in higher order correlators remains to be determined, this being the main task that we address here. The precise measurement of the shape and scale dependence (or running) of statistical parameters such as the NG parameters and the statistical anisotropy level could provide relevant elements for model building and for the determination of the presence (or nonpresence) of inflationary vector fields and their role in the inflationary mechanism.

The IceCube evidence for cosmic neutrinos in the high-energy starting events (HESE) sample has inspired a large number of hypotheses on their origin, mainly due to the poor precision on the measurement of the direction of showering events. The fact that most HESE are downward going suggests a possible Galactic component. This could be originated either by a single pointlike source or to a directional excess from an extended Galactic region. These hypotheses are reviewed and constrained, using the present available upper limits from the ANTARES neutrino telescope. ANTARES detects ${\nu }_{\mu }$ from sources in the Southern sky with an effective area larger than that providing the IceCube HESE for $E_{\nu }<60\mathrm{TeV}$ and a factor of about two smaller at 1 PeV. The use of the ${\nu }_{\mu }$ signal enables an accurate measurement of the incoming neutrino direction. The Galactic signal allowed by the IceCube HESE and the corresponding ANTARES limits are studied in terms of a power law flux $E^{-\mathrm{\Gamma }}$, with spectral index $\mathrm{\Gamma }$ ranging from 2.0 to 2.5 to cover most astrophysical models.

IceCube has observed neutrinos that are presumably of extra-Galactic origin. Since specific sources have not yet been identified, we discuss what could be learned from the conceptual point of view. We use a simple model for neutrino production from the interactions between nuclei and matter, and we focus on the description of the spectral shape and flavor composition observed by IceCube. Our main parameters are the spectral index, maximal energy, magnetic field, and composition of the accelerated nuclei. We show that a cutoff at PeV energies can be achieved by soft enough spectra, a cutoff of the primary energy, or strong enough magnetic fields. These options, however, are difficult to reconcile with the hypothesis that these neutrinos originate from the same sources as the ultrahigh-energy cosmic rays. We demonstrate that heavier nuclei accelerated in the sources may be a possible way out if the maximal energy scales appropriately with the mass number of the nuclei. In this scenario, neutrino observations can actually be used to test the ultrahigh-energy cosmic ray acceleration mechanism. We also emphasize the need for a volume upgrade of the IceCube detector for future precision physics, for which the flavor information becomes a statistically meaningful model discriminator as well as a qualitatively new ingredient.

Primordial magnetic fields create a large squeezed-type non-Gaussianity in tensor perturbation, which generates non-Gaussian temperature fluctuations in the cosmic microwave background. We for the first time derive an observational constraint on such a tensor non-Gaussianity from observed cosmic microwave background maps. Analyzing temperature maps of the WMAP 7-year data, we find that such a tensor non-Gaussianity is consistent with zero. This gives an upper bound on primordial magnetic field strength smoothed on 1 Mpc as $B_{1\mathrm{Mpc}}<3.1\mathrm{nG}$ at 95% C.L.

We derive a light-front Schrödinger-type equation of motion for the quark-antiquark wave function of heavy quarkonia imposing constraints from the holographic soft-wall model.

We investigate the possibility of a composite $Z^{\prime }$ vector boson. For the compositeness, the required gauge coupling $g$ in low energy is not so big, $g^2/(4\pi )\gtrsim 0.015$ in the case of the $U(1{)}_{B-L}$ model. We show that the Stückelberg model is effectively induced in low energy via the fermion loop from the Nambu-Jona-Lasinio model having the vectorial four-fermion interaction. In terms of the renormalization group equations, this situation is expressed by the compositeness conditions. We find that the solutions of the renormalization group equations with the compositeness conditions are determined by the infrared fixed points. As a result, the ratio of the masses of the extra electroweak singlet scalar and the right-handed neutrino is fixed. The mass of the composite $Z^{\prime }$ boson contains the contribution $\mathrm{\Delta }$ of the Stückelberg mass term. This nonzero $\mathrm{\Delta }$ might be a remnant of a strongly interacting theory in high energy.