We propose a search for dark photons $A^{\prime }$ at the LHCb experiment using the charm meson decay $D^{*}(2007{)}^0\to D^0{A}^{\prime }$. At nominal luminosity, $D^{*0}\to D^0\gamma$ decays will be produced at about 700 kHz within the LHCb acceptance, yielding over 5 trillion such decays during Run 3 of the LHC. Replacing the photon with a kinetically mixed dark photon, LHCb is then sensitive to dark photons that decay as $A^{\prime }\to e^{+}{e}^{-}$. We pursue two search strategies in this paper. The displaced strategy takes advantage of the large Lorentz boost of the dark photon and the excellent vertex resolution of LHCb, yielding a nearly background-free search when the $A^{\prime }$ decay vertex is significantly displaced from the proton-proton primary vertex. The resonant strategy takes advantage of the large event rate for $D^{*0}\to D^0{A}^{\prime }$ and the excellent invariant-mass resolution of LHCb, yielding a background-limited search that nevertheless covers a significant portion of the $A^{\prime }$ parameter space. Both search strategies rely on the planned upgrade to a triggerless-readout system at LHCb in Run 3, which will permit the identification of low-momentum electron-positron pairs online during data taking. For dark photon masses below about 100 MeV, LHCb can explore nearly all of the dark photon parameter space between existing prompt-$A^{\prime }$ and beam-dump limits.

We demonstrate that the entirety of the data on proton-proton and antiproton-proton scattering between 6 GeV and 57 TeV center-of-mass energy—the measured scattering cross sections, $\rho$ values, and the forward slope parameters $B$ for the differential cross sections—is sufficient to show that ${\sigma }_{\text{elas}}/{\sigma }_{\text{tot}}\to 1/2$ and $8\pi B/{\sigma }_{\text{tot}}\to 1$ at very high energies. These relations demonstrate convincingly that the asymptotic $pp$ and $\overline{p}p$ scattering amplitudes approach those of scattering from a black disk. This result obviously introduces a constraint on any physics beyond the Standard Model that modifies the forward scattering amplitudes.

Missing data are a common problem in experimental and observational physics. They can be caused by various sources, such as an instrument’s saturation, a contamination from an external event, or a data loss. In particular, they can have a disastrous effect when one is seeking to characterize a colored-noise-dominated signal in Fourier space, since they create a spectral leakage that can artificially increase the noise. It is therefore important to either take them into account or to correct for them prior to, e.g., a least-square fit of the signal to be characterized. In this paper, we present an application of the inpainting algorithm to mock MICROSCOPE data. Inpainting is based on a sparsity assumption, and has already been used in various astrophysical contexts; MICROSCOPE is a French Space Agency mission (whose launch is expected in 2016) that aims to test the weak equivalence principle down to the $10^{-15}$ level. We then explore the inpainting dependence on the number of gaps and the total fraction of missing values. We show that, in a worst-case scenario, after reconstructing missing values with inpainting a least-square fit may allow us to significantly measure a $1.1\times {10}^{-15}$ equivalence principle violation signal, which is sufficiently close to the MICROSCOPE requirements to implement inpainting in the official MICROSCOPE data processing and analysis pipeline. Together with the previously published KARMA method, inpainting will then allow us to independently characterize and cross-check an equivalence principle violation signal detection down to the $10^{-15}$ level.

An axially symmetric ansatz is proposed to investigate the properties of a baryon in a uniform magnetic field. The baryon number is shown to be conserved, while the baryon shape is stretched along the magnetic field. It is found that with increasing magnetic field strength, the static mass of the baryon first decreases and then increases, while the size of the baryon first increases and then decreases. Finally, in the core part of the magnetar, the equation of state strongly depends on the magnetic field, which modifies the mass limit of the magnetar.

We propose a unified mass matrix model for quarks and leptons, in which 16 observables of mass ratios and mixings of the quarks and neutrinos are described by using no family-number-dependent parameters except for the charged lepton masses and only six family-number-independent free parameters. The model is constructed by extending the so-called “Yukawaon” model to a seesaw-type model. As a result, once the six parameters are fixed by the quark mixing and the mass ratios of quarks and neutrinos, no free parameters are left in the lepton mixing matrix. The results are in excellent agreement with the neutrino mixing data. We predict ${\delta }_{CP}^{\ell }=-68°$ for the leptonic $CP$ violating phase and $⟨m⟩\simeq 21\mathrm{meV}$ for the effective Majorana neutrino mass.

When a nonrelativistic particle interacts with a scalar quantum field, the standard perturbation theory leads to a dependence of the energy of its ground state on an undefined parameter—“momentum cutoff”—due to the ultraviolet divergence. We show that the use of nonasymptotic states of the system results in a calculation scheme in which all observable quantities remain finite and continuously depend on the coupling constant without any additional parameters. It is furthermore demonstrated that the divergence of traditional perturbation series is caused by the energy being a function with a logarithmic singularity for small values of the coupling constant.

In a previous paper, we considered the motion of massive spinning test particles in the “pole-dipole” approximation, as described by the Mathisson-Papapetrou-Dixon (MPD) equations and examined its properties in dependence on the spin supplementary condition. We decomposed the equations in the orthonormal tetrad based on the timelike vector fixing the spin condition and on the corresponding spin, while representing the curvature in terms of the Weyl scalars obtained in the Newman-Penrose null tetrad naturally associated with the orthonormal one; the projections thus obtained did not contain the Weyl scalars ${\mathrm{\Psi }}_0$ and ${\mathrm{\Psi }}_4$. In the present paper, we choose the interpretation tetrad in a different way, attaching it to the tangent $u^{\mu }$ of the worldline representing the history of the spinning body. Actually two tetrads are suggested, both given “intrinsically” by the problem and each of them incompatible with one specific spin condition. The decomposition of the MPD equation, again supplemented by writing its right-hand side in terms of the Weyl scalars, is slightly less efficient than in the massive case, because $u^{\mu }$ cannot be freely chosen (in contrast to $V^{\mu }$) and so the $u^{\mu }$-based tetrad is less flexible. In the second part of this paper, a similar analysis is performed for massless spinning particles; in particular, a certain intrinsic interpretation tetrad is again found. The respective decomposition of the MPD equation of motion is considerably simpler than in the massive case, containing only ${\mathrm{\Psi }}_1$ and ${\mathrm{\Psi }}_2$ scalars and not the cosmological constant. An option to span the spin-bivector eigenplane, besides the worldline null tangent, by a main principal null direction of the Weyl tensor can lead to an even simpler result.

As galaxy surveys begin to measure the imprint of baryonic acoustic oscillations (BAO) on large-scale structure at the subpercent level, reconstruction techniques that reduce the contamination from nonlinear clustering become increasingly important. Inverting the nonlinear continuity equation, we propose an Eulerian growth-shift reconstruction algorithm that does not require the displacement of any objects, which is needed for the standard Lagrangian BAO reconstruction algorithm. In real-space dark matter-only simulations the algorithm yields 95% of the BAO signal-to-noise obtained from standard reconstruction. The reconstructed power spectrum is obtained by adding specific simple 3- and 4-point statistics to the prereconstruction power spectrum, making it very transparent how additional BAO information from higher-point statistics is included in the power spectrum through the reconstruction process. Analytical models of the reconstructed density for the two algorithms agree at second order. Based on similar modeling efforts, we introduce four additional reconstruction algorithms and discuss their performance.

The Jordan frame action for general disformal theories is presented and studied for the first time, motivated by several unresolved mysteries that arise when working in the Einstein frame. We present the Friedmann equations and, specializing to exponential functions, study the late-time cosmology using both dynamical systems methods and by finding approximate solutions. Our analysis reveals that either the disformal effects are irrelevant or the Universe evolves towards a phantom phase where the equation of state of dark energy is $-3$. There is a marginal case where the asymptotic state of the Universe depends on the model parameters and de Sitter solutions can be obtained. Our findings indicate that the metric singularity found using the Einstein frame construction corresponds to phantom behavior in the Jordan frame and we argue that this is the case for general disformal theories.

In a supersymmetric extension of the standard model with local gauged baryon and lepton numbers (BLMSSM), there are new sources for lepton flavor violation, because the right-handed neutrinos and new gauginos are introduced. In BLMSSM, we study the charged lepton flavor violating processes $l_j\to l_i+\gamma$ and $l_j\to 3l_i$ in detail. The numerical results show that in some parameter space the branching ratios for charged lepton flavor violating processes can be large enough to be detected in the near future.

We propose an adjoint $SU(5)$ GUT model with a $T_7$ family symmetry and an extra $Z_2\otimes Z_3\otimes Z_4\otimes Z_4^{\prime }\otimes Z_{12}$ discrete group that successfully describes the prevailing Standard Model fermion mass and mixing pattern. The observed hierarchy of the charged fermion masses and the quark mixing angles arises from the $Z_3\otimes Z_4\otimes Z_{12}$ symmetry breaking, which occurs near the GUT scale. The light active neutrino masses are generated by type-I and type-III seesaw mechanisms mediated by the fermionic $SU(5)$ singlet and the adjoint $\mathbf{24}$-plet. The model predicts the effective Majorana neutrino mass parameter of neutrinoless double beta decay to be $m_{\beta \beta }=4$ and 50 meV for the normal and the inverted neutrino spectra, respectively. We construct several benchmark scenarios, which lead to $SU(5)$ gauge coupling unification and are compatible with the known phenomenological constraints originating from the lightness of neutrinos, proton decay, dark matter, etc. These scenarios contain TeV-scale colored fields, which could give rise to a visible signal or be stringently constrained at the LHC.

We present a hydrodynamical description of the QCD Dirac spectrum at finite chemical potential as an incompressible droplet in the complex eigenvalue space. For a large droplet, the fluctuation spectrum around the hydrostatic solution is gapped by a longitudinal Coulomb plasmon and exhibits a frictionless odd viscosity. The stochastic relaxation time for the restoration or breaking of chiral symmetry is set by twice the plasmon frequency. The leading droplet size correction to the relaxation time is fixed by a universal odd viscosity to density ratio ${\eta }_O/{\rho }_0=(\beta -2)/4$ for the three Dyson ensembles $\beta =1$, 2, 4.

We construct canonical transformations to reformulate SU(N) Kogut-Susskind lattice gauge theory in terms of a set of fundamental loop and string flux operators along with their canonically conjugate loop and string electric fields. The canonical relations between the initial SU(N) link operators and the final SU(N) loop and string operators, consistent with SU(N) gauge transformations, are explicitly constructed over the entire lattice. We show that as a consequence of SU(N) Gauss laws all SU(N) string degrees of freedom become cyclic and decouple from the physical Hilbert space ${\mathcal{H}}^p$. The Kogut-Susskind Hamiltonian rewritten in terms of the fundamental physical loop operators has global SU(N) invariance. There are no gauge fields. We further show that the ($1/g^2$) magnetic field terms on plaquettes create and annihilate the fundamental plaquette loop fluxes while the ($g^2$) electric field terms describe all their interactions. In the weak coupling ($g^2\to 0$) continuum limit the SU(N) loop dynamics is described by SU(N) spin Hamiltonian with nearest neighbor interactions. In the simplest SU(2) case, where the canonical transformations map the SU(2) loop Hilbert space into the Hilbert spaces of hydrogen atoms, we analyze the special role of the hydrogen atom dynamical symmetry group $SO(4,2)$ in the loop dynamics and the spectrum. A simple tensor network ansatz in the SU(2) gauge invariant hydrogen atom loop basis is discussed.

The spatial curvature ($K$ or ${\mathrm{\Omega }}_K$) is one of the most fundamental parameters of an isotropic and homogeneous universe and has a close link to the physics of the early Universe. Combining the radial and angular diameter distances measured via the baryon acoustic oscillation (BAO) experiments allows us to unambiguously constrain the curvature. The method is primarily based on the metric theory, and is less sensitive to the theory of structure formation (other than the existence of the BAO scale) and is free of any model of dark energy. In this paper, we estimate a best achievable accuracy of constraining the curvature with the BAO experiments. We show that an all-sky, cosmic-variance-limited galaxy survey covering the Universe up to $z\gtrsim 4$ enables a precise determination of the curvature to an accuracy of $\sigma ({\mathrm{\Omega }}_K)\simeq 10^{-3}$. When we assume a model of dark energy—either the cosmological constraint or the $(w_0,w_a)$ model—it can achieve a precision of $\sigma ({\mathrm{\Omega }}_K)\simeq \text{a few}\times {10}^{-4}$. These forecasts require a high sampling density of galaxies, and are degraded by up to a factor of a few for a survey with a finite number density of $\sim {10}^{-3}(h/\mathrm{Mpc}{)}^3$.

Using the latest observational data we obtain a lower bound on the initial value of the quintessence field in thawing quintessence models of dark energy. For potentials of the form $V(\varphi )\sim {\varphi }^{\pm 2}$ we find that the initial value $|{\varphi }_i|>7\times {10}^{18}\mathrm{GeV}$. We then relate ${\varphi }_i$ to the duration of inflation by assuming that the initial value of the quintessence field is determined by quantum fluctuations of the quintessence field during inflation. From the lower bound on ${\varphi }_i$ we obtain a lower bound on the number of e-foldings of inflation, namely, $N>2\times {10}^{11}$. We obtain similar bounds for other power law potentials for which too we obtain $|{\varphi }_i|>O(M_P)$.

We present a class of models in the framework of gauge mediation supersymmetry breaking where the standard model is supplemented by additional $U(1)$ symmetry which acts only on the third generation fermions. The messenger fields carry a nontrivial $U(1)$ charge and are vectorlike particles under this symmetry. This leads to additional contributions to the soft supersymmetry breaking mass terms for the third-generation squarks and sleptons. In this framework we show that the muon $g-2$ anomaly, the observed 125 GeV Higgs boson mass and the detected relic dark matter abundance (gravitino in our case) can be simultaneously accommodated. The resolution of the muon $g-2$ anomaly, in particular, yields the result that masses of squarks in the first two families, as well the gluino mass, should be $\lesssim 2.5\mathrm{TeV}$, which will be tested at LHC14.

We report a study of the suppressed $B^{-}\to D{K}^{-}{\pi }^{+}{\pi }^{-}$ and favored $B^{-}\to D{\pi }^{-}{\pi }^{+}{\pi }^{-}$ decays, where the neutral $D$ meson is detected through its decays to the $K^{\mp }{\pi }^{\pm }$ and $CP$ -even $K^{+}{K}^{-}$ and ${\pi }^{+}{\pi }^{-}$ final states. The measurement is carried out using a proton-proton collision data sample collected by the LHCb experiment, corresponding to an integrated luminosity of $3.0{\mathrm{fb}}^{-1}$. We observe the first significant signals in the $CP$ -even final states of the $D$ meson for both the suppressed $B^{-}\to D{K}^{-}{\pi }^{+}{\pi }^{-}$ and favored $B^{-}\to D{\pi }^{-}{\pi }^{+}{\pi }^{-}$ modes, as well as in the doubly Cabibbo suppressed $D\to K^{+}{\pi }^{-}$ final state of the $B^{-}\to D{\pi }^{-}{\pi }^{+}{\pi }^{-}$ decay. Evidence for the suppressed decay $B^{-}\to D{K}^{-}{\pi }^{+}{\pi }^{-}$, with $D\to K^{+}{\pi }^{-}$, is also presented. From the observed yields in the $B^{-}\to D{K}^{-}{\pi }^{+}{\pi }^{-}$, $B^{-}\to D{\pi }^{-}{\pi }^{+}{\pi }^{-}$ and their charge conjugate decay modes, the most probable value of the weak phase $\gamma$ corresponds to $\gamma =(74_{-19}^{+20})°$. This is one of the most precise single-measurement determinations of $\gamma$ to date.

For a field theory with a gravitational dual, following Susskind’s proposal we define holographic complexity for a subsystem. The holographic complexity is proportional to the volume of a codimension one time slice in the bulk geometry enclosed by the extremal codimension two hypersurface appearing in the computation of the holographic entanglement entropy. The proportionally constant, up to a numerical order of 1 factor is $GR$ where $G$ is the Newton constant and $R$ is the curvature of the space-time. We study this quantity in certain holographic models. We also explore a possible relation between the defined quantity and fidelity appearing in quantum information literature.

We explore magnetic-field amplification due to the Kelvin-Helmholtz instability during binary neutron star mergers. By performing high-resolution general relativistic magnetohydrodynamics simulations with a resolution of 17.5 m for 4–5 ms after the onset of the merger on the Japanese supercomputer “K”, we find that an initial magnetic field of moderate maximum strength ${10}^{13}\mathrm{G}$ is amplified at least by a factor of $\approx {10}^3$. We also explore the saturation of the magnetic-field energy and our result shows that it is likely to be $\gtrsim 4\times {10}^{50}\mathrm{erg}$, which is $\gtrsim 0.1\%$ of the bulk kinetic energy of the merging binary neutron stars.

The magnetic order of the triangular lattice with antiferromagnetic interactions is described by an $SO(3)$ field and allows for the presence of $Z_2$ magnetic vortices as defects. In this work we show how these $Z_2$ vortices can be fitted into a local $SU(2)$ gauge theory. We propose simple Ansätze for vortex configurations and calculate their energies using well-known results of the Abelian gauge model. We comment on how Dzyaloshinskii-Moriya interactions could be derived from a non-Abelian gauge theory and speculate on their effect on nontrivial configurations.