The Newtonian simulations describing the formation of large-scale structures do not include relativistic effects. A new approach to this problem is proposed, which consists of splitting the Hawking-Hayward quasilocal energy of a closed spacelike 2-surface into a “Newtonian” part due to local perturbations and a “relativistic” part due to the cosmology. It is found that the Newtonian part dominates over the relativistic one as time evolves, lending support to the validity of Newtonian simulations.

In this paper we study the equilibrium configurations of anisotropic self-gravitating fermions, by extending to general relativity the solutions obtained in a previous paper. This treatment also generalizes to anisotropic systems the relativistic self-gravitating Fermi gas model, by considering different degrees of anisotropy. We discuss some important characteristics of the models and the obtained density profiles, and generalize the relation between the anisotropy and the mass of particles in the relativistic regime. These relativistic models may also be applied to the study of superdense neutron stars with anisotropic pressure or super-Chandrasekhar white dwarfs generated by the presence of a magnetic field.

We correct Fig. 2 and its discussion in subsection II A. The remainder of the paper remains unaffected.

In models of low-energy gauge mediation, the observed Higgs mass is in tension with the cosmological limit on the gravitino mass $m_{3/2}\lesssim 16\mathrm{eV}$. We present an alternative mediation mechanism of supersymmetry breaking via a $U(1)$ $D$ term with an $E_6$-inspired particle content, which we call vector mediation. The gravitino mass can be in the eV range. The sfermion masses are at the 10 TeV scale, while gauginos are around a TeV. This mechanism also greatly ameliorates the $\mu$ problem.

It is expected that nucleons and their parity partners become degenerate when chiral symmetry is restored. We investigate this question in the context of the thermal transition from the hadronic phase to the quark-gluon plasma, using lattice QCD simulations with $N_f=2+1$ flavors. We observe a clear sign of parity doubling in the quark-gluon plasma. Besides, we find that the nucleon ground state is, within the uncertainty, largely independent of the temperature, whereas temperature effects are substantial in the negative-parity ($N^{*}$) channel, already in the confined phase.

In this paper we propose the study of the $W^{+}{W}^{-}$ and ${\mu }^{+}{\mu }^{-}$ production by two-photon interactions in $pp$ collisions at LHC energies to constrain the photon flux associated with an ultrarelativistic proton. We consider the current parametrizations for the photon distribution of the proton and estimate the effective photon-photon luminosities for elastic, semielastic, and inelastic processes. Moreover, we present predictions for the rapidity and invariant mass distributions for the two-photon production of $W^{+}{W}^{-}$ and ${\mu }^{+}{\mu }^{-}$ in $\gamma \gamma$ interactions at LHC energies. We demonstrate that the semielastic and inelastic predictions are strongly dependent on the description of the inelastic photon flux and that the relative contribution of the different processes depends on the invariant mass of the final state. Our results imply that a dedicated experimental analysis of the two-photon production of $W^{+}{W}^{-}$ and ${\mu }^{+}{\mu }^{-}$ with the tagging of one of the protons in the final state can be useful to constrain the magnitude of the inelastic component of the photon distribution.

In this work, we study the high-spin states with masses below 3 GeV observed in experiments, and we perform an analysis of mass spectrum and an investigation of strong decay behaviors of the high-spin states. Comparing our results with the experimental data, we can reveal the underlying properties of these high-spin states; more importantly, we also predict their abundant decay features, which can provide valuable information for experimental exploration of these high-spin states.

Assuming the Majorana nature of neutrinos, we investigate the singular one texture zero neutrino mass matrices in the flavor basis. We find that for the normal mass ordering with $m_1=0$, all six one texture zero classes are now ruled out at $3\sigma$ confidence level, whereas for inverted mass ordering with $m_3=0$ only four classes out of the six total can accommodate the latest neutrino oscillation data at $3\sigma$ confidence level. Moreover, only two classes can accommodate the present data at $1\sigma$ confidence level. We examine the phenomenological implications of the allowed classes for the effective Majorana mass and Dirac and Majorana $CP$-violating phases. Working within the framework of the type-I seesaw mechanism, we present simple discrete Abelian symmetry models leading to all the phenomenologically allowed classes.

When the singlet-doublet fermion dark matter model is extended with additional $Z_2$-odd real singlet scalars, neutrino masses and mixings can be generated at the one-loop level. In this work, we discuss the salient features arising from the combination of the two resulting simplified dark matter models. When the lightest $Z_2$-odd particle is a scalar singlet, $\mathrm{Br}(\mu \to e\gamma )$ could be measurable provided that the singlet-doublet fermion mixing is small enough. In this scenario, the new decay channels of vector-like fermions into scalars can also generate interesting leptonic plus missing transverse energy signals at the LHC. On the other hand, in the case of doublet-like fermion dark matter, scalar coannihilations lead to an increase in the relic density which allows one to lower the bound of doublet-like fermion dark matter.

We report a search for the charmless hadronic decay $B^0\to \eta {\pi }^0$ with a data sample corresponding to an integrated luminosity of $694{\mathrm{fb}}^{-1}$ containing $753\times 10^6$ $B\overline{B}$ pairs. The data were collected by the Belle experiment running on the $\mathrm{{\rm Y}}(4S)$ resonance at the KEKB $e^{+}{e}^{-}$ collider. We measure a branching fraction $\mathcal{B}(B^0\to \eta {\pi }^0)=(4.1_{-1.5-0.7}^{+1.7+0.5})\times 10^{-7}$, where the first uncertainty is statistical and the second is systematic. Our measurement gives an upper limit of $\mathcal{B}(B^0\to \eta {\pi }^0)<6.5\times 10^{-7}$ at 90% confidence level. The signal has a significance of 3.0 standard deviations and constitutes the first evidence for this decay mode.

The coefficients of the membrane instantons in the ABJM theory are known to be quadratic polynomials of the chemical potential. For better insight into this nonconstantness, we consider more general superconformal Chern–Simons theories labelled by two parameters $(q,p)$. In these theories, we show that the membrane instantons split into three types of nonperturbative effects, one more type compared with the previous observation. We also determine their explicit coefficients which are independent of the chemical potential. We find that, although these constants contain poles at certain values of $q$ and $p$ including the ABJM case, all of the poles cancel among themselves, and the finite quadratic polynomial coefficients are reproduced at these values. This is similar to what happens between the membrane instantons and the worldsheet instantons in the ABJM theory.

We update our original low-energy constant computations to the $O(p^6)$ order, including two and three flavors, the normal and anomalous ones. Following a comparative analysis, the $O(p^4)$ order results are considered better. In the $O(p^6)$ order, most of our results are consistent with or better than those we have found in the literature, although several are worse.

The emergence of gauge particles (e.g., photons and gravitons) as Goldstone bosons arising from spontaneous symmetry breaking is an interesting hypothesis which would provide a dynamical setting for the gauge principle. We investigate this proposal in the framework of a general $\mathrm{SO}(N)$ non-Abelian Nambu model (NANM), effectively providing spontaneous Lorentz symmetry breaking in terms of the corresponding Goldstone bosons. Using a nonperturbative Hamiltonian analysis, we prove that the $\mathrm{SO}(N)$ Yang-Mills (YM) theory is equivalent to the corresponding NANM, after both current conservation and the Gauss laws are imposed as initial conditions for the latter. This equivalence is independent of any gauge fixing in the YM theory. A substantial conceptual and practical improvement in the analysis arises by choosing a particular parametrization that solves the nonlinear constraint defining the NANM. This choice allows us to show that the relation between the NANM canonical variables and the corresponding ones of the YM theory, $A_i^a$ and $E^{bj}$, is given by a canonical transformation. In terms of the latter variables, the NANM Hamiltonian has the same form as the YM Hamiltonian, except that the Gauss laws do not arise as first-class constraints. The dynamics of the NANM further guarantees that it is sufficient to impose them only as initial conditions, in order to recover the full equivalence. It is interesting to observe that this particular parametrization exhibits the NANM as a regular theory, thus providing a substantial simplification in the calculations.

We show that it is possible to construct a wide class of Lorentzian wormholes in Eddington-inspired Born-Infeld gravity with a stress energy which does not violate the weak or null energy condition. The wormholes exist in a certain region of the parameter space. In fact, it is shown that there is a critical value of a parameter defined in our work, below which we have wormholes. Above the critical value, we have a regular black hole spacetime. We put a restriction on the equation of state parameter $\alpha$ ($p_{\theta }=\alpha \rho$) to have wormholes. We also put a lower limit on both the theory parameter $|\kappa |$ and the throat radius, to restrict the tidal acceleration (at the throat) below one Earth gravity. As a special case of our general solution, we retrieve the wormhole supported by an electric field for a charge-to-mass ratio greater than the critical value ${(\frac{Q}{M})}_c\approx 1.144$.

Using a generalization of the Madelung transformation, we derive the hydrodynamic representation of the Klein-Gordon-Einstein equations in the weak field limit. We consider a complex self-interacting scalar field with a $\lambda |\phi {|}^4$ potential. We study the evolution of the spatially homogeneous background in the fluid representation and derive the linearized equations describing the evolution of small perturbations in a static and in an expanding Universe. We compare the results with simplified models in which the gravitational potential is introduced by hand in the Klein-Gordon equation, and assumed to satisfy a (generalized) Poisson equation. Nonrelativistic hydrodynamic equations based on the Schrödinger-Poisson equations or on the Gross-Pitaevskii-Poisson equations are recovered in the limit $c\to +\infty$. We study the evolution of the perturbations in the matter era using the nonrelativistic limit of our formalism. Perturbations whose wavelength is below the Jeans length oscillate in time while perturbations whose wavelength is above the Jeans length grow linearly with the scale factor as in the cold dark matter model. The growth of perturbations in the scalar field model is substantially faster than in the cold dark matter model. When the wavelength of the perturbations approaches the cosmological horizon (Hubble length), a relativistic treatment is mandatory. In that case, we find that relativistic effects attenuate or even prevent the growth of perturbations. This paper exposes the general formalism and provides illustrations in simple cases. Other applications of our formalism will be considered in companion papers.

During inflation, scalar fields, including the Higgs boson, may acquire a nonzero vacuum expectation value, which must later relax to the equilibrium value during reheating. In the presence of the time-dependent condensate, the vacuum state can evolve into a state with a nonzero particle number. We show that, in the presence of lepton-number violation in the neutrino sector, the particle production can explain the observed matter-antimatter asymmetry of the Universe. We find that this form of leptogenesis is particularly effective when the Higgs condensate decays rapidly and at low reheat scale. As part of the calculation, we present some exact results for the Bogoliubov transformations for Majorana fermions with a nonzero time-dependent chemical potential, in addition to a time-dependent mass.

An analysis is given of the decay $\mu \to e+\gamma$ in an minimal supersymmetric standard model extension with a vectorlike generation. Here mixing with the mirrors allows the possibility of this decay. The analysis is done at the one-loop level with the exchange of charginos and neutralinos and of sleptons and mirror sleptons in the loops. A one-loop analysis with W- and Z-boson exchange and mirror leptons and neutrinos is also considered. The effects of $CP$-violating phases from the new sector on the decay $\mu \to e\gamma$ are analyzed in detail. The constraints arising from the current upper limit on the branching ratio $\mathcal{B}(\mu \to e\gamma )$ from the MEG experiment of $2.4\times {10}^{-12}$ (at 90% C.L.) on the parameter space of supersymmetry (SUSY) models and on vectorlike models are explored. Further, the MEG experiment is likely to improve the upper limit by an order of magnitude in the coming years. The improved limits will allow one to probe a much larger domain of the parameter space of the extended models.

QCD strings originate from high-energy scattering in the form of Reggeons and Pomerons, and have been studied in some detail in lattice numerical simulations. Production of multiple strings, with their subsequent breaking, is now a mainstream model of high-energy $pp$ and $pA$ collisions. Recent LHC experiments revealed that the high multiplicity ends of such collisions show interesting collective effects. This ignited an interest in the interaction of QCD strings and multistring dynamics. Holographic models, collectively known as AdS/QCD, developed in the last decade, describe both hadronic spectroscopy and basic thermodynamics, but so far no studies of the QCD strings have been done in this context. The subject of this paper is to do this. First, we study in more detail the scalar sector of hadronic spectroscopy, identifying “glueballs” and “scalar mesons,” and calculate the degree of their mixing. The QCD strings, holographic images of the fundamental strings, thus have a “gluonic core” and a “sigma cloud.” The latter generates $\sigma$ exchanges and collectivization of the strings, affecting, at a certain density, the chiral condensate and even the minimum of the effective string potential, responsible for the very existence of the QCD strings. Finally, we run dynamical simulations of the multistring systems, in the “spaghetti” setting approximating central $pA$ collisions, and specify conditions for their collectivization into a black hole, or the dual quark gluon plasma fireball.

We compute the interference between the resonant process $pp\to H(\to \gamma \gamma )+2\text{jets}$ and the corresponding continuum background at leading order in QCD. For the Higgs signal, we include gluon fusion (GF) and vector boson fusion (VBF) production channels, while for the background we consider all tree-level contributions, including pure EW effects ($\mathcal{O}({\alpha }_{\mathrm{QED}}^4)$) and QCD contributions ($\mathcal{O}({\alpha }_{\mathrm{QED}}^2{\alpha }_s^2)$), plus the loop-induced gluon-initiated process. After convolution with the experimental mass resolution, the main effect of the interference is to shift the position of the mass peak, as in the inclusive GF case studied previously. The apparent mass shift is small in magnitude but strongly dependent on the Higgs width, potentially allowing for a measurement of, or bound on, the width itself. In the $H(\to \gamma \gamma )+2\text{jets}$ channel, the VBF and GF contributions generate shifts of opposite signs which largely cancel, depending on the sets of cuts used, to as little as 5 MeV (toward a lower Higgs mass). The small magnitude of the shift makes this channel a good reference mass for measuring the inclusive mass shift of around 60 MeV in the Standard Model.