In this work we deal with the presence of braneworld solutions in a five-dimensional space-time with a single extra spatial dimension of infinite extent. The braneworld scenario is built under the presence of a single real scalar field, and we modify the gravity sector to include generic function of the Gauss-Bonnet term. We study several specific models, and we construct exact braneworld solutions, in particular for including the Gauss-Bonnet term at first and second order power. As an interesting result, we show that the brane tends to split for a specific modification in the gravity sector, in the presence of a nonconstant Gauss-Bonnet term.

We investigate a large class of infinitesimal, but fully nonlinear in the field, transformations of the Galileon and search for extended symmetries. The transformations involve powers of the coordinates $x$ and the field $\pi$ up to any finite order $N$. Up to quadratic order the structure of these symmetry transformations is the unique generalization of both the infinitesimal version of the standard Galileon shift symmetry as well as a recently discovered infinitesimal extension of this symmetry. The only higher-order extensions of this symmetry we recover are (“Galileon dual” versions of) symmetries of the standard kinetic term.

We point out that domain wall formation is a more common phenomenon in the axiverse than previously thought. Level crossing could take place if there is a mixing between axions, and if some of the axions acquire a nonzero mass through nonperturbative effects as the corresponding gauge interactions become strong. The axion potential changes significantly during the level crossing, which affects the axion dynamics in various ways. We find that, if there is a mild hierarchy in the decay constants, the axion starts to run along the valley of the potential, passing through many crests and troughs, until it gets trapped in one of the minima: the axion roulette. The axion dynamics exhibits a chaotic behavior during the oscillations, and which minimum the axion is finally stabilized is highly sensitive to the initial misalignment angle. Therefore, the axion roulette is considered to be accompanied by domain wall formation. The cosmological domain wall problem can be avoided by introducing a small bias between the vacua. We discuss cosmological implications of the domain wall annihilation for baryogenesis and future gravitational wave experiments.

We investigate the prior dependence on the inferred spectrum of primordial tensor perturbations, in light of recent results from BICEP2 and taking into account a possible dust contribution to polarized anisotropies. We highlight an optimized parametrization of the tensor power spectrum, and adoption of a logarithmic prior on its amplitude $A_{\mathrm{T}}$, leading to results that transform more evenly under change of pivot scale. In the absence of foregrounds the tension between the results of BICEP2 and Planck drives the tensor spectral index $n_{\mathrm{T}}$ to be blue tilted in a joint analysis, which would be in contradiction to the standard inflation prediction ($n_{\mathrm{T}}<0$). When foregrounds are accounted for, the BICEP2 results no longer require nonstandard inflationary parameter regions. We present limits on primordial $A_{\mathrm{T}}$ and $n_{\mathrm{T}}$, adopting foreground scenarios put forward by Mortonson and Seljak and motivated by Planck 353 GHz observations, and assess what dust contribution leaves a detectable cosmological signal. We find that if there is sufficient dust for the signal to be compatible with standard inflation, then the primordial signal is too weak to be robustly detected by BICEP2 if $\text{Planck}+\mathrm{WMAP}$ upper limits from temperature and $E$-mode polarization are correct.

The simplest models of inflation predict small non-Gaussianities and a featureless power spectrum. However, there exist a large number of well-motivated theoretical scenarios in which large non-Gaussianties could be generated. In general, in these scenarios the primordial power spectrum will deviate from its standard power law shape. We study, in a model-independent manner, the constraints from future large-scale structure surveys on the local non-Gaussianity parameter $f_{\mathrm{NL}}$ when the standard power law assumption for the primordial power spectrum is relaxed. If the analyses are restricted to the large-scale-dependent bias induced in the linear matter power spectrum by non-Gaussianites, the errors on the $f_{\mathrm{NL}}$ parameter could be increased by 60% when exploiting data from the future DESI survey, if dealing with only one possible dark matter tracer. In the same context, a nontrivial bias $|\delta f_{\mathrm{NL}}|\sim 2.5$ could be induced if future data are fitted to the wrong primordial power spectrum. Combining all the possible DESI objects slightly ameliorates the problem, as the forecasted errors on $f_{\mathrm{NL}}$ would be degraded by 40% when relaxing the assumptions concerning the primordial power spectrum shape. Also, the shift on the non-Gaussianity parameter is reduced in this case, $|\delta f_{\mathrm{NL}}|\sim 1.6$. The addition of cosmic microwave background priors ensures robust future $f_{\mathrm{NL}}$ bounds, as the forecasted errors obtained including these measurements are almost independent on the primordial power spectrum features, and $|\delta f_{\mathrm{NL}}|\sim 0.2$, close to the standard single-field slow-roll paradigm prediction.

The transit of primordial black holes through a white dwarf causes localized heating around the trajectory of the black hole through dynamical friction. For sufficiently massive black holes, this heat can initiate runaway thermonuclear fusion causing the white dwarf to explode as a supernova. The shape of the observed distribution of white dwarfs with masses up to $1.25M_{\odot }$ rules out primordial black holes with masses $\sim {10}^{19}–{10}^{20}\mathrm{gm}$ as a dominant constituent of the local dark matter density. Black holes with masses as large as ${10}^{24}\mathrm{gm}$ will be excluded if recent observations by the NuStar Collaboration of a population of white dwarfs near the galactic center are confirmed. Black holes in the mass range ${10}^{20}–{10}^{22}\mathrm{gm}$ are also constrained by the observed supernova rate, though these bounds are subject to astrophysical uncertainties. These bounds can be further strengthened through measurements of white dwarf binaries in gravitational wave observatories. The mechanism proposed in this paper can constrain a variety of other dark matter scenarios such as Q balls, annihilation/collision of large composite states of dark matter and models of dark matter where the accretion of dark matter leads to the formation of compact cores within the star. White dwarfs, with their astronomical lifetimes and sizes, can thus act as large spacetime volume detectors enabling a unique probe of the properties of dark matter, especially of dark matter candidates that have low number density. This mechanism also raises the intriguing possibility that a class of supernova may be triggered through rare events induced by dark matter rather than the conventional mechanism of accreting white dwarfs that explode upon reaching the Chandrasekhar mass.

The latest Planck results reconfirm the existence of a slight but chronic tension between the best-fit cosmic microwave background (CMB) and low-redshift observables: power seems to be consistently lacking in the late universe across a range of observables (e.g. weak lensing, cluster counts). We propose a two-parameter model for dark energy where the dark energy is sufficiently like dark matter at large scales to keep the CMB unchanged but where it does not cluster at small scales, preventing concordance collapse and erasing power. We thus exploit the generic scale-dependence of dark energy instead of the more usual time-dependence to address the tension in the data. The combination of CMB, distance and weak lensing data somewhat prefer our model to $\mathrm{\Lambda }\mathrm{CDM}$, at $\mathrm{\Delta }{\chi }^2=2.4$. Moreover, this improved solution has ${\sigma }_8=0.79\pm 0.02$, consistent with the value implied by cluster counts.

Cosmological parameters deduced from the Planck measurements of anisotropies in the cosmic microwave background are at some tension with direct astronomical measurements of various parameters at low redshifts. Very recently, it has been conjectured that this discrepancy can be reconciled if a certain fraction of dark matter is unstable and decays between recombination and the present epoch. Herein we show that if the superheavy relics have a branching into neutrinos ${\mathcal{B}}_{X\to \nu \overline{\nu }}\sim 5\times {10}^{-8}$, then this scenario can also accommodate the recently discovered extraterrestrial flux of neutrinos, relaxing the tension between IceCube results and Fermi LAT data. The model is fully predictive and can be confronted with future IceCube data. We demonstrate that in 10 years of observation IceCube will be able to distinguish the monoenergetic signal from $X$ decay at the $3\sigma$ level. In a few years of data taking with the upgraded IceCube-Gen2 enough statistics will be gathered to elucidate the dark matter–neutrino connection at the $5\sigma$ level.

We consider grand unified theories based on $SO(10)$ which originate from $\text{string}/M$ theory on $G_2$ manifolds or Calabi-Yau spaces with discrete symmetries. In this framework we are naturally led to a novel solution of the doublet-triplet splitting problem previously considered by Dvali which involves an extra vectorlike Standard Model family and light but weakly coupled color triplets. These additional states are predicted to be accessible at the LHC and also induce R-parity violation. Gauge coupling unification occurs with a larger GUT coupling.

We present a study of the $b-\tau$ Yukawa unified supersymmetric $SU(4{)}_c\times SU(2{)}_L\times SU(2{)}_R$ model (with $\mu >0$), which predicts the existence of gluino—neutralino and stop—neutralino coannihilation scenarios compatible with the desired relic lightest supersymmetric particle neutralino dark matter abundance and other collider constraints. The next to lightest supersymmetric particle (NLSP) gluino or NLSP stop masses vary between 400 GeV and $\sim 1\mathrm{TeV}$. The NLSP gluinos will be accessible at the 14 TeV LHC, while we hope that the NSLP stop solutions will be probed in future LHC searches. We also identify regions of the parameter space in which the gluino and the lighter stop are closely degenerate in mass, interchangeably playing the role of NLSP and next to next to lightest supersymmetric particle (NNLSP). We also update a previous study of $t-b-\tau$ Yukawa unification and show that NLSP gluino of mass $\sim 1\mathrm{TeV}$, with a mass difference between the gluino and neutralino of less than 80 GeV, can be realized, consistent with the current collider and astrophysical constraints. We present benchmark points for $b-\tau$ and $t-b-\tau$ Yukawa unification that can be accessible at the LHC.

We show that new resonance shapes—a pure dip, nothingness, and an enhanced pure peak—can be produced from the interference between the resonance and continuum with a relative phase. Production conditions of those new shapes are derived based on a general parametrization of the interference. The narrow width approximation is modified to work with the nonzero imaginary part of interference, and the correction factor can characterize the resonance shape. We demonstrate that the new resonance shapes of heavy Higgs bosons, $H^0$ and $A^0$ in the type-II aligned two Higgs doublet model, generally show up in $gg\to H^0/A^0\to t\overline{t}$ as well as $b\overline{b}$ and $\gamma \gamma$ channels. The pure $A^0$ resonance dip in the $t\overline{t}$ channel is a particularly interesting signal as it can be probed by the current search techniques that do not even take into account interferences; the high-luminosity LHC 14 TeV can perhaps probe a large part of its parameter space.

In this paper we introduce an equation of state (EOS) of quark matter within the framework of Dyson-Schwinger equations to study the structure of compact stars. The smooth crossover from hadronic matter to quark matter in the hybrid star is studied. We compare different strategies to obtain crossover EOSs and find a new way to construct two-solar-mass hybrid stars with even a relatively soft quark EOS, while earlier works showed that the quark EOS should be stiff enough to support a massive hybrid star.

In the present work, we use three-body interaction formalism to investigate the $K$–multi-$\rho$ interactions. First, we reproduce the resonances $f_2(1270)$ and $K_1(1270)$ in the $\rho \rho$ and $\rho K$ two-body interactions, respectively, as the clusters of the fixed-center approximation. Then, we study the three-body $K–\rho \rho (f_2)$ and $\rho –\rho K(K_1)$ interactions with the fixed-center approximation of the Faddeev equations. Furthermore, we extrapolate the formalism to study the four-body, five-body, and six-body systems containing one $K$ meson and multiple $\rho$ mesons. In our research, without introducing any free parameters, we generate the $K_2(1770)$ state in the three-body interaction with the mass of 1707 MeV and a width about 113 MeV, which are consistent with the experiments. We also find a clear resonant structure in our results of the five-body interaction, with a mass 2505 MeV and a width about 32 MeV or more, which is associated with the $K_4(2500)$ state, where we obtain consistent results with the experimental findings. Furthermore, we predict some new states in the other many-body interactions, $K_3(2080)$, $K_5(2670)$ (isospin $I=1/2$), and $K_4(2640)$ (isospin $I=3/2$), with uncertainties.

Resonances and final state interactions (FSI) play a role in the formation of charge parity ($CP$) violation (CPV) constrained by $CPT$ invariance. We provide a general formulation of CPV including resonances and FSI starting from the $CPT$ constraint. Our discussion is elaborated within a simple $B$ decay model with the $\rho$ and $f_0(980)$ resonances plus a nonresonant background including the $\pi \pi \to KK$ coupled amplitude. We consider a few illustrative examples to show the interference patterns appearing in the $CP$ asymmetry, namely, that from the $\rho$ resonance plus a nonresonant amplitude, and that from the interference of the $\rho$ and $f_0(980)$ resonances. We perform the fit of the $CP$ asymmetry for the charmless three-body $B^{\pm }$ decay channel $B^{\pm }\to {\pi }^{\pm }{\pi }^{+}{\pi }^{-}$ and obtain as outcome the $B^{\pm }\to {\pi }^{\pm }{K}^{+}{K}^{-}$ for $\pi \pi$ channel asymmetry in the mass region below 1.6 GeV in fair agreement with the new LHCb data. Analogously, we also describe the $CP$ asymmetry of the $B^{\pm }\to K^{\pm }{\pi }^{+}{\pi }^{-}$ decay, with that from the $B^{\pm }\to K^{\pm }{K}^{+}{K}^{-}$ channel obtained as output. As in the previous case, we also found agreement with LHCb experimental data.

Electromagnetic properties of neutrinos, if ever observed, could help to decide the Dirac versus Majorana nature of neutrinos. We show that the magnetic moments of Majorana neutrinos have to fulfill triangle inequalities, $|{\mu }_{{\nu }_{\tau }}{|}^2\le |{\mu }_{{\nu }_{\mu }}{|}^2+|{\mu }_{{\nu }_e}{|}^2$ and cyclic permutations, which do not hold for Dirac neutrinos. Observing a violation of these inequalities, e.g., by measuring the magnetic moment of ${\nu }_{\tau }$ at SHiP, would thus strongly hint either at the Dirac nature of neutrinos or at the presence of at least one extra light sterile mode.

A search for the decay to a pair of new particles of either the 125 GeV Higgs boson ($h$) or a second charge parity ($CP$)-even Higgs boson ($H$) is presented. The data set corresponds to an integrated luminosity of $20.3{\mathrm{fb}}^{-1}$ of $pp$ collisions at $\sqrt{s}=8\mathrm{TeV}$ recorded by the ATLAS experiment at the LHC in 2012. The search was done in the context of the next-to-minimal supersymmetric standard model, in which the new particles are the lightest neutral pseudoscalar Higgs bosons ($a$). One of the two $a$ bosons is required to decay to two muons while the other is required to decay to two $\tau$ leptons. No significant excess is observed above the expected backgrounds in the dimuon invariant mass range from 3.7 to 50 GeV. Upper limits are placed on the production of $h\to aa$ relative to the standard model $gg\to h$ production, assuming no coupling of the $a$ boson to quarks. The most stringent limit is placed at 3.5% for $m_a=3.75\mathrm{GeV}$. Upper limits are also placed on the production cross section of $H\to aa$ from 2.33 to 0.72 pb, for fixed $m_a=5\mathrm{GeV}$ with $m_H$ ranging from 100 to 500 GeV.

We study nonrelativistic field theory coupled to a torsional Newton-Cartan (NC) geometry both directly and holographically. The latter involves gravity on asymptotically local Lifshitz space-times. We define an energy-momentum tensor and a mass current and study the relation between conserved currents and conformal Killing vectors for flat Newton-Cartan backgrounds. It is shown that flat NC space-time realizes two copies of the Lifshitz algebra that together form a Schrödinger algebra (without the central element). We show why the Schrödinger scalar model has both copies as symmetries and the Lifshitz scalar model only one. Finally we discuss the holographic dual of this phenomenon by showing that the bulk Lifshitz space-time realizes the same two copies of the Lifshitz algebra.

We analyze a nonrelativistic approximation of the Dirac equation for slow fermions, coupled to the chameleon field and torsion in the spacetime with the Schwarzschild metric, taken in the weak gravitational field of the Earth approximation. We follow the analysis of the Dirac equation in the curved spacetime with torsion, proposed by Kostelecky [Phys. Rev. D 69, 105009 (2004)], and apply the Foldy-Wouthuysen transformations. We derive the effective low-energy gravitational potentials for slow fermions, coupled to the gravitational field of the Earth, the chameleon field and to torsion with minimal and nonminimal couplings.

We use exceptional field theory as a tool to work out the full nonlinear reduction ansatz for the ${\mathrm{AdS}}_5\times S^5$ compactification of IIB supergravity and its noncompact counterparts in which the sphere $S^5$ is replaced by the inhomogeneous hyperboloidal space $H^{p,q}$. The resulting theories are the maximal 5D supergravities with gauge groups $\mathrm{SO}(p,q)$. They are consistent truncations in the sense that every solution of 5D supergravity lifts to a solution of IIB supergravity. In particular, every stationary point and every holographic renormalization group flow of the scalar potentials for the compact and noncompact 5D gaugings directly lift to solutions of IIB supergravity.

We show that the Kondo effect occurs in light quark matter which contains heavy quarks as impurities. We consider a scattering between a heavy-flavor impurity and a light quark near a Fermi surface which is mediated by gluon-exchange interactions. We find that the scattering amplitude has a logarithmic infrared divergence originating from imperfect cancellation between quark-impurity and hole-impurity scatterings in a loop integral, implying the presence of a strongly coupled regime near the Fermi surface. Renormalization group method is used to find the Kondo scale where a running coupling constant hits a Landau pole. Following an illustration by a simple contact-interaction model, we examine gluon-exchange interactions on the basis of high density QCD.