We calculate for the first time the form factors of the semileptonic decays of the $D_s$ meson to $\eta$ and ${\eta }^{\prime }$ using lattice techniques. As a by-product of the calculation we obtain the masses and leading distribution amplitudes of the $\eta$ and ${\eta }^{\prime }$ mesons. We use $N_f=2+1$ nonperturbatively improved clover fermions on configurations with a lattice spacing $a\sim 0.075\mathrm{fm}$. We are able to obtain clear signals for relevant matrix elements, using several noise reduction techniques, for both the connected and the disconnected contributions. This includes a new method for reducing the variance of pseudoscalar disconnected two-point functions. At zero momentum transfer, we obtain for the scalar form factors, $|f_0^{D_s\to \eta }|=0.564(11)$ and $|f_0^{D_s\to {\eta }^{\prime }}|=0.437(18)$ at $M_{\pi }\approx 470\mathrm{MeV}$, as well as $|f_0^{D_s\to \eta }|=0.542(13)$ and $|f_0^{D_s\to {\eta }^{\prime }}|=0.404(25)$ at $M_{\pi }\approx 370\mathrm{MeV}$, where the errors are statistical only.

We investigate QCD threshold resummation effects beyond the next-to-leading logarithmic (NLL) order for the process $H_1{H}_2\to h_1{h}_{2}X$ at high invariant mass of the produced hadron pair. We take into account the color structure of the underlying partonic hard-scattering cross sections and determine the relevant hard and soft matrices in color space that contribute to the resummed cross section at next-to-next-to-leading logarithmic (NNLL) accuracy. We present numerical results for fixed-target and collider regimes. We find a significant improvement compared to previous results at NLL accuracy. In particular, the scale dependence of the resummed cross section is greatly reduced. Use of the most recent set of fragmentation functions also helps in improving the comparison with the experimental data. Our calculation provides a step towards a systematic NNLL extension of threshold resummation also for other hadronic processes, in particular for jet production.

The electromagnetic properties of neutrinos, which are either trivial or negligible in the context of the Standard Model, can probe new physics and have significant implications in astrophysics and cosmology. The current best direct limits on the neutrino millicharges and magnetic moments are both derived from data taken with germanium detectors with low thresholds at keV levels. In this paper, we discuss in detail a robust, ab initio method: the multiconfiguration relativistic random-phase approximation, that enables us to reliably understand the germanium detector response at the sub-keV level, where atomic many-body physics matters. By using existing data with sub-keV thresholds, limits on the reactor antineutrino’s millicharge, magnetic moment, and charge radius squared are derived. The projected sensitivities for next-generation experiments are also given and discussed.

In light of the recent discovery of nonzero ${\theta }_{13}$, we have analyzed the Altarelli-Feruglio $A_4$ flavor symmetry model extended with additional flavon. The inclusion of the new field leads to the deviation from the exact tri-bimaximal neutrino mixing pattern in the context of a type-I seesaw by producing a nonzero ${\theta }_{13}$ consistent with the recent experimental results at the leading order. A sum rule for light neutrino masses is also obtained in this context. The setup constrains the two Majorana phases involved in the lepton mixing matrix in terms of $A_4$ parameter space. We have shown that a nonzero lepton asymmetry can be generated while next-to-leading order contributions to the neutrino Yukawa couplings are considered. The two Majorana phases play a crucial role in CP-asymmetry parameter and the involvement of ${\theta }_{13}$ in it, is exercised.

If the Standard Model (SM) is valid up to extremely high energy scales, then the Higgs potential becomes unstable at approximately $10^{11}\mathrm{GeV}$. However, calculations of the lifetime of the SM vacuum have shown that it vastly exceeds the age of the Universe. It was pointed out by two of us (V. B., E. M.) that these calculations are extremely sensitive to effects from Planck scale higher-dimensional operators and, without knowledge of these operators, firm conclusions about the lifetime of the SM vacuum cannot be drawn. The previous paper used analytical approximations to the potential and, except for Higgs contributions, ignored loop corrections to the bounce action. In this work, we do not rely on any analytical approximations and consider all contributions to the bounce action, confirming the earlier result. It is surprising that the Planck scale operators can have such a large effect when the instability is at $10^{11}\mathrm{GeV}$. There are two reasons for the size of this effect. In typical tunneling calculations, the value of the field at the center of the critical bubble is much larger than the point of the instability; in the SM case, this turns out to be numerically within an order of magnitude of the Planck scale. In addition, tunneling is an inherently nonperturbative phenomenon and may not be as strongly suppressed by inverse powers of the Planck scale. We include effective ${\mathrm{\Phi }}^6$ and ${\mathrm{\Phi }}^8$ Planck-scale operators and show that they can have an enormous effect on the tunneling rate.

Motivated by the indications of a possible deficit of muon tracks in the first three-year equivalent data set of IceCube we investigate the possibility that the astrophysical (anti)neutrino flux (in the PeV energy range) could originate from $\beta$-decay of relativistic neutrons. We show that to accommodate IceCube observations it is necessary that only about 1% to 10% of the emitted cosmic rays in the energy decade ${10}^{8.5}\lesssim E_{\mathrm{CR}}/\mathrm{GeV}\lesssim {10}^{9.5}$, yielding antineutrinos on Earth ($10^{5.5}\lesssim E_{\overline{\nu }}/\mathrm{GeV}\lesssim 10^{6.5}$), are observed. Such a strong suppression can be explained assuming magnetic shielding of the secondary protons which diffuse in extragalactic magnetic fields of strength $10\lesssim B/\mathrm{nG}\lesssim 100$ and coherence length $\lesssim \mathrm{Mpc}$.

We present a model of partially interacting dark matter within the framework of supersymmetry with gauge mediated symmetry breaking. Dark sector atoms are produced through Affleck-Dine baryogenesis in the dark sector while avoiding the production of $Q$-ball relics. We discuss the astrophysical constraints relevant for this model and the possibility of dark galactic disk formation. In addition, jet emission from rotating black holes is discussed in the context of this class of models.

The quest for finding self-consistent background solutions in quantum field theory is closely related to the way one decides to set the renormalization scale $k$. This freedom in the choice of the scale setting can lead to ambiguities and conceptual inconsistencies such as the nonconservation of the stress-energy tensor. In this paper a setting for the “scale field” is proposed at the level of effective action, which avoids such inconsistencies by construction. The mechanism and its potential is exemplified for scalar ${\varphi }^4$ theory and for Einstein-Hilbert-Maxwell theory.

We study and measure the transmission coefficient of counterpropagating shallow-water waves produced by a wave generator and scattered by an obstacle. To precisely compare theoretical predictions and experimental data, we consider $\sim 25$ frequencies for five subcritical background flows, where the maximum value of the Froude number ranges from 0.5 to 0.75. For each flow, the transmission coefficient displays a sharp transition separating total transmission from wave blocking. Both the width and the central frequency of the transition are in good agreement with their theoretical values. The shape of the obstacle is identical to that used by the Vancouver team in the recent experiment aiming at detecting the analog of stimulated Hawking radiation. Our results are compatible with the observations that have been reported. They complete them by establishing that the contribution of the transmission coefficient cannot be neglected for the lower half of the probed frequency range.

We study some geometric properties of Killing horizons in four-dimensional stationary and axisymmetric space-times with an electromagnetic field and a cosmological constant. Using a $(1+1+2)$ space-time split, we construct relations between the space-time Riemann tensor components and the components of the Riemann tensor corresponding to the horizon surface. The Einstein equations allow to derive the space-time scalar curvature invariants—Kretschmann, Chern-Pontryagin, and Euler—on the two-dimensional spacelike horizon surface. The derived relations generalize the relations known for Killing horizons of static and axisymmetric four-dimensional space-times. We also present the generalization of Hartle’s curvature formula.

This paper investigates self-gravitating spherically symmetric fluid models in Brans-Dicke gravity by incorporating structure scalars. We obtain ten scalar quantities using orthogonal splitting of the Reimann tensor and write down the set of governing equations in terms of these scalars. We determine inhomogeneity factors and conclude that inhomogeneity is a necessary condition for the resultant fluid models. Finally, we explore static inhomogeneous anisotropic spherical solutions with the help of these structure scalars.

Recent CMS searches for dileptoquark production report local excesses of $2.4\sigma$ in an $eejj$ channel and $2.6\sigma$ in an $e{\cancel{p}}_{T}jj$ channel. Here, we simultaneously explain both excesses with resonant slepton production in $\mathcal{R}$-parity violating supersymmetry. We consider resonant slepton production, which decays to a lepton and a chargino/neutralino, followed by three-body decays of the neutralino/chargino via an $\mathcal{R}$-parity violating coupling. There are regions of parameter space which are also compatible at the 95% confidence level with a $2.8\sigma$ $eejj$ excess in a recent CMS $W_R$ search, while being compatible with other direct search constraints. Phase II of the GERDA neutrinoless double beta decay ($0\nu \beta \beta$) experiment will probe a sizable portion of the good-fit region.

Double-parton scattering (DPS) has become very relevant as a background to interesting analyses performed by the experiments at the LHC. It encodes knowledge of correlations between the proton constituents not accessible in single-parton scattering. Within perturbative QCD DPS is described in terms of partonic subprocesses and double-parton distributions (DPDs). There exists a large number of different DPDs describing the different possible states of two partons inside a proton. They include correlations between the two partons and interferences between the two hard subprocesses. Taking the probability interpretation of the DPDs as a starting point, we derive limits on the interference DPDs and thereby constrain the size of correlations between two partons inside an unpolarized proton.

We construct two interpolating solutions in type II string theory which interpolate between ${\mathrm{AdS}}_5$ in the UV and a hyperscaling-violating three (spatial)-dimensional Lifshitz spacetime in the IR. The first solution is nonsupersymmetric and is obtained from a known intersecting nonsupersymmetric D3-brane with a chargeless D0-brane solution of type IIB string theory, by restricting some parameters characterizing the solution and going to a new coordinate. In the IR the dilaton is nonconstant in general and the metric is three (spatial)-dimensional hyperscaling-violating Lifshitz spacetime with dynamical critical exponent $z=(3+3\gamma )/(3-\gamma )$ and hyperscaling-violation exponent $\theta =12/(3-\gamma )$, where $\gamma$ is a real parameter and can take continuous values from $-1$ to $+1$. At the two extreme values, i.e., for $\gamma =\pm 1$, the dilaton is constant. On physical grounds it is found that $\gamma$ must be restricted to lie in the range $-1\le \gamma \le 0$. The second solution is supersymmetric and is obtained from the known F-D2 bound-state solution of type IIA string theory by zooming into a particular region of space. In the UV, the proper description is given in a $T$-dual frame which is ${\mathrm{AdS}}_5$, whereas in the IR, it gives a three-dimensional hyperscaling-violating Lifshitz spacetime with $z=3$ and $\theta =2=d-1$.

We show that pure Yang-Mills theories with Lorentz violation are renormalizable to all orders in perturbation theory. To do this, we employ the algebraic renormalization technique. Specifically, we control the breaking terms with a suitable set of external sources, which eventually attain certain physical values. The Abelian case is also analyzed as a starting point. The main result is that the renormalizability of the usual Maxwell and Yang-Mills sectors are both left unchanged. Furthermore, in contrast to Lorentz-violating QED, the $CPT$-odd violation sector of Yang-Mills theories renormalizes independently. Moreover, the method induces mass terms for the gauge field in a natural way, while the photon remains massless (at least in the sense of a Proca-like term). The entire analysis is carried out in the Landau gauge.

We utilize generalized unitarity and recursion relations combined with effective field theory techniques to compute spin-dependent interaction terms for an inspiralling binary system in the post-Newtonian (PN) approximation. Using these methods offers great computational advantage over traditional techniques involving Feynman diagrams, especially at higher orders in the PN expansion. As a specific example, we reproduce the spin-orbit (up to 2.5PN order) and the leading-order $S^2$ (2PN) Hamiltonian for a binary system with one of the massive objects having nonzero spin using the $S$-matrix elements of elementary particles. For the same system, we also obtain the $S^3$ (3.5PN) spin Hamiltonian for an arbitrary massive object, which was until now known only for a black hole. Furthermore, we derive the missing $S^4$ Hamiltonian at leading order (4PN), again for an arbitrary massive object and establish that the minimal coupling of an elementary particle to gravity automatically captures the physics of a spinning black hole. Finally, the Kerr metric is obtained as a series in $G_N$ by comparing the action of a test particle in the vicinity of a spinning black hole to the derived potential.

We show that the Schrödinger-Newton equation, which describes the nonlinear time evolution of self-gravitating quantum matter, can be made compatible with the no-signaling requirement by elevating it to a stochastic differential equation. In the deterministic form of the equation, as studied so far, the nonlinearity would lead to diverging energy corrections for localized wave packets and would create observable correlations admitting faster-than-light communication. By regularizing the divergencies and adding specific random jumps or a specific Brownian noise process, the effect of the nonlinearity vanishes in the stochastic average and gives rise to a linear and Galilean invariant evolution of the density operator.

We investigate properties of strange quark matter in the framework of the SU(3) Nambu–Jona-Lasinio model with vector interactions under strong magnetic fields. The effects of vector-isoscalar and vector-isovector interactions on the equation of state of strange quark matter are investigated, and it is found that the equation of state is not sensitive to the vector-isovector interaction; however, a repulsive interaction in the vector-isoscalar channel gives a stiffer equation of state for cold dense quark matter. In the presence of a magnetic field, gluons will be magnetized via quark loops, and the contribution from magnetized gluons to the equation of state is also estimated. The sound velocity square is a quantity to measure the hardness or softness of dense quark matter, and in the Nambu–Jona-Lasinio model without vector interaction at zero magnetic field, the sound velocity square is always less than $1/3$. It is found that a repulsive vector-isoscalar interaction and a positive pressure contribution from magnetized gluons can enhance the sound velocity square, which can even reach 1. To construct quark magnetars under strong magnetic fields, we consider anisotropic pressures and use a density-dependent magnetic field profile to mimic the magnetic field distribution in a quark star. We also analyze the parameter region for the magnitude of vector-isoscalar interaction and the contribution from magnetized gluons in order to produce two-solar-mass quark magnetars.