We pin down the origin of a peculiar dispersion relation of domain wall fluctuation, the so-called ripplon, in a superfluid-superfluid interface. A ripplon has a dispersion relation $\omega \propto k^{3/2}$ due to the nonlocality of the effective Lagrangian, which is mediated by gapless superfluid phonons in the bulk. We point out the analogy to the longitudinal phonon in the two-dimensional Wigner crystal.

We show that Poincaré-invariant topological gravity in even dimensions can be formulated as a transgression field theory in one higher dimension whose gauge connections are associated to linear and nonlinear realizations of the Poincaré group $ISO(d-1,1)$. The resulting theory is a gauged Wess-Zumino-Witten (WZW) model whereby the transition functions relating gauge fields live in the coset $\frac{ISO(d-1,1)}{SO(d-1,1)}$. The coordinate parametrizing the coset space is identified with the scalar field in the adjoint representation of the gauge group of the even-dimensional topological gravity theory. The supersymmetric extension leads to topological supergravity in two dimensions starting from a transgression field theory which is invariant under the supersymmetric extension of the Poincaré group in three dimensions. We also apply this construction to a three-dimensional Chern-Simons theory of gravity which is invariant under the Maxwell algebra and obtain the corresponding WZW model.

We compute the one- and two-loop corrected mode function of a massless minimally coupled scalar endowed with a quartic self-interaction in the locally de Sitter background of an inflating universe for a state which is released in Bunch-Davies vacuum at time $t=0$. We then employ it to correct the scalar’s tree-order scale invariant power spectrum ${\mathrm{\Delta }}_{\phi }^2$. The corrections are secular, and have a scale-dependent part that can be expanded in even powers of $k/(Ha)$, where $k$ is the comoving wave number, $H$ is the expansion rate and, $a$ is the cosmic scale factor. At one-loop, the scale invariant shift in the power spectrum grows as $(Ht{)}^2$ in leading order. The $k$-dependent shifts, however, are constants for each mode, in the late time limit. At two-loop order, on the other hand, the scale invariant shift grows as $(Ht{)}^4$ whereas the $k$-dependent shifts grow as $(Ht{)}^2$, in leading order. We finally calculate the scalar’s spectral index $n_{\phi }$ and the running of the spectral index ${\alpha }_{\phi }$. They imply that the spectrum is slightly red-tilted; hence, the amplitudes of fluctuations grow slightly toward the larger scales.

Despite the great successes of the cold dark matter (CDM) model in explaining a wide range of observations of the global evolution and the formation of galaxies and large-scale structure in the Universe, the origin and microscopic nature of dark matter is still unknown. The most common form of CDM considered to date is that of weakly interacting massive particles (WIMPs), but, so far, attempts to detect WIMPs directly or indirectly have not yet succeeded, and the allowed range of particle parameters has been significantly restricted. Some of the cosmological predictions for this kind of CDM are even in apparent conflict with observations (e.g., cuspy-cored halos and an overabundance of satellite dwarf galaxies). For these reasons, it is important to consider the consequences of different forms of CDM. We focus here on the hypothesis that the dark matter is comprised, instead, of ultralight bosons that form a Bose–Einstein condensate, described by a complex scalar field, for which particle number per unit comoving volume is conserved. We start from the Klein–Gordon and Einstein field equations to describe the evolution of the Friedmann–Robertson–Walker universe in the presence of this kind of dark matter. We find that, in addition to the radiation-, matter-, and $\mathrm{\Lambda }$-dominated phases familiar from the standard CDM model, there is an earlier phase of scalar-field domination, which is special to this model. In addition, while WIMP CDM is nonrelativistic at all times after it decouples, the equation of state of Bose–Einstein condensed scalar field dark matter (SFDM) is found to be relativistic at early times, evolving from stiff ($\overline{p}=\overline{\rho }$) to radiationlike ($\overline{p}=\overline{\rho }/3$), before it becomes nonrelativistic and CDM-like at late times ($\overline{p}=0$). The timing of the transitions between these phases and regimes is shown to yield fundamental constraints on the SFDM model parameters, particle mass $m$, and self-interaction coupling strength $\lambda$. We show that SFDM is compatible with observations of the evolving background universe, by deriving the range of particle parameters required to match observations of the cosmic microwave background (CMB) and the abundances of the light elements produced by big bang nucleosynthesis (BBN), including $N_{\mathrm{eff}}$, the effective number of neutrino species, and the epoch of matter-radiation equality $z_{\mathrm{eq}}$. This yields $m\ge 2.4\times 10^{-21}\mathrm{eV}/c^2$ and $9.5\times {10}^{-9}{\mathrm{eV}}^{-1}{\mathrm{cm}}^3\le \lambda /({\mathrm{mc}}^2{)}^2\le 4\times {10}^{-17}{\mathrm{eV}}^{-1}{\mathrm{cm}}^3$. Indeed, our model can accommodate current observations in which $N_{\mathrm{eff}}$ is higher at the BBN epoch than at $z_{\mathrm{eq}}$, probed by the CMB, which is otherwise unexplained by the standard CDM model involving WIMPs. We also show that SFDM without self-interaction (also called “fuzzy dark matter”) is not able to comply with the current constraints from BBN within 68% confidence and is therefore disfavored.

We study the two-point cross-correlation function between two populations of galaxies: for instance, a bright population and a faint population. We show that this cross-correlation is asymmetric under the exchange of the line-of-sight coordinate of the galaxies, i.e. that the correlation is different if the bright galaxy is in front of, or behind, the faint galaxy. We give an intuitive, quasi-Newtonian derivation of all the effects that contribute to such an asymmetry in large-scale structure: gravitational redshift, Doppler shift, lensing, light-cone, evolution and Alcock-Paczynski effects; interestingly, the gravitational redshift term is exactly canceled by some of the others, assuming geodesic motion. Most of these effects are captured by previous calculations of general relativistic corrections to the observed galaxy density fluctuation; the asymmetry arises from terms that are suppressed by the ratio ($\mathcal{H}/k$)—$\mathcal{H}$ is the Hubble constant and $k$ is the wave number—which are more readily observable than the terms suppressed by $(\mathcal{H}/k{)}^2$. Some of the contributions to the asymmetry, however, arise from terms that are generally considered “Newtonian”—the lensing and evolution—and thus represent a contaminant in the search for general relativistic corrections. We propose methods to disentangle these different contributions. A simple method reduces the contamination to a level of $\lesssim 10\%$ for redshifts $z\lesssim 1$. We also clarify the relation to recent work on measuring gravitational redshifts by stacking clusters.

We study the possibility that primordial magnetic fields generated in the transition between inflation and reheating posses magnetic helicity, $H_M$. The fields are induced by stochastic currents of scalar charged particles created during the mentioned transition. We estimate the rms value of the induced magnetic helicity by computing different four-point scalar quantum electrodynamics Feynman diagrams. For any considered volume, the magnetic flux across its boundaries is in principle not null, which means that the magnetic helicity in those regions is gauge dependent. We use the prescription given by Berger and Field and interpret our result as the difference between two magnetic configurations that coincide in the exterior volume. In this case, the magnetic helicity gives only the number of magnetic links inside the considered volume. We calculate a concrete value of $H_M$ for large scales and analyze the distribution of magnetic defects as a function of the scale. Those defects correspond to regular as well as random fields in the considered volume. We find that the fractal dimension of the distribution of topological defects is $D=1/2$. We also study if the regular fields induced on large scales are helical, finding that they are and that the associated number of magnetic defects is independent of the scale. In this case, the fractal dimension is $D=0$. We finally estimate the intensity of fields induced at the horizon scale of reheating and evolve them until the decoupling of matter and radiation under the hypothesis of the inverse cascade of magnetic helicity. The resulting intensity is high enough and the coherence length long enough to have an impact on the subsequent process of structure formation.

We test the consistency of several independent astrophysical measurements of fundamental dimensionless constants. In particular, we compare direct measurements of the fine-structure constant $\alpha$ and the proton-to-electron mass ratio $\mu =m_p/m_e$ (mostly in the optical/ultraviolet) with combined measurements of $\alpha$, $\mu$, and the proton gyromagnetic ratio $g_p$ (mostly in the radio band). We point out some apparent inconsistencies, which suggest that hidden systematics may be affecting some of the measurements. These findings demonstrate the importance of future, more precise measurements with ALMA, ESPRESSO, and ELT-HIRES. We also highlight some of the implications of the currently available measurements for fundamental physics, specifically for unification scenarios.

I discuss fluctuations in the neutral hydrogen density of the $z\approx 2.3$ intergalactic medium and show that their relation to cosmic overdensity is strongly scale dependent. This behavior arises from a linearized version of the well-known “proximity effect,” in which bright sources suppress atomic hydrogen density. Using a novel, systematic and detailed linear-theory radiative-transfer calculation, I demonstrate how Hi density consequently anticorrelates with total matter density when averaged on scales exceeding the Lyman-limit mean-free path. The radiative-transfer thumbprint is highly distinctive and should be measurable in the Lyman-$\alpha$ forest. Effects extend to sufficiently small scales to generate significant distortion of the correlation function shape around the baryon acoustic oscillation peak, although the peak location shifts only by 1.2 percent for a mean source bias of $b_j=3$. The distortion changes significantly with $b_j$ and other astrophysical parameters; measuring it should provide a helpful observational constraint on the nature of ionizing photon sources in the near future.

A first measurement of time-reversal (T) asymmetries that are not also $CP$ asymmetries has been recently achieved by the BaBar collaboration. We analyze the measured asymmetries in the presence of direct $CP$ violation, $CPT$violation, wrong strangeness decays and wrong sign semileptonic decays. We note that the commonly used $S_{\psi K}$ and $C_{\psi K}$ parameters are $CP$-odd, but have a T-odd $CPT$-even part and a T-even $CPT$-odd part. We introduce parameters that have well-defined transformation properties under $CP$, T and $CPT$. We identify contributions to the measured asymmetries that are T conserving. We explain why, in order that the measured asymmetries would be purely odd under time-reversal, there is no need to assume the absence of direct $CP$ violation. Instead, one needs to assume (i) the absence of $CPT$ violation in strangeness changing decays, and (ii) the absence of wrong sign decays.

The propagation of a high-energy quark disturbs the confining QCD vacuum inducing the currents in Dirac sea. Since quarks possess electric charge, these induced vacuum quark currents act as a source of soft photon radiation. This can lead to the enhancement of the soft photon production above the expectations based on the charged hadron yields and the Low theorem. We illustrate the phenomenon by using the exactly soluble $1+1$ dimensional massless Abelian gauge model that shares with QCD all of the ingredients involved in this mechanism: confinement, chiral symmetry breaking, axial anomaly, and the periodic $\theta$ vacuum. We show that the propagating quark throughout the process of hadronization induces in the vacuum charged transition currents that lead to a strong resonant enhancement of the soft photon yield; the Low theorem, however, remains accurate in the limit of very soft momenta. We then construct on the basis of our result a simple phenomenological model and apply it to the soft photon production in the fragmentation of jets produced in $Z^0$ decays. We find a qualitative agreement with the recent result from the DELPHI Collaboration.

We perform a next-to-leading-order QCD analysis to world data on polarized structure functions $g_1$ and $g_2$ in a fixed-flavor number scheme. We include target mass corrections and higher twist effects in our fitting procedure and study their non-negligible effects on physically interesting quantities. Twist-3 contributions to both polarized structure functions are determined, and the accuracy of the extracted polarized parton distribution functions is improved. ${}^3\mathrm{He}$ and ${}^3\mathrm{H}$ polarized structure functions are described based on our fit result. Moreover, sum rules are derived and compared with available theoretical and experimental results.

We analyze, within a dipole model, the inclusive deep inelastic scattering cross section data, obtained from the combination of the measurements of the H1 and ZEUS experiments performed at the HERA collider. We show that these high precision data are very well described within the dipole model framework, which is complemented with valence quark structure functions. We discuss the properties of the gluon density obtained in this way.

We derive an analytical solution for the flavor evolution of a neutrino through a turbulent density profile which is found to accurately predict the amplitude and transition wavelength of numerical solutions on a case-by-case basis. The evolution is seen to strongly depend upon those Fourier modes in the turbulence which are approximately the same as the splitting between neutrino eigenvalues. Transitions are strongly enhanced by those Fourier modes in the turbulence which are approximately the same as the splitting between neutrino eigenvalues. We also find a suppression of transitions due to the long wavelength modes when the ratio of their amplitude and the wave number is of order, or greater than, the first root of the Bessel function $J_0$.

We report a search for the decay ${\overline{B}}^0\to {\mathrm{\Lambda }}_{\mathrm{c}}^{+}\overline{p}p\overline{p}$. Using a data sample of $471\times 10^6$ $B\overline{B}$ pairs collected with the BABAR detector at the PEP-II2 storage ring at SLAC, we find no events and set an upper limit on the branching fraction $\mathcal{B}({\overline{B}}^0\to {\mathrm{\Lambda }}_{\mathrm{c}}^{+}\overline{p}p\overline{p})\times \frac{\mathcal{B}({\mathrm{\Lambda }}_{\mathrm{c}}^{+}\to p{K}^{-}{\pi }^{+})}{0.050}<2.8\times 10^{-6}$ at 90% C.L., where we have normalized $\mathcal{B}({\mathrm{\Lambda }}_{\mathrm{c}}^{+}\to p{K}^{-}{\pi }^{+})$ to the world average value.

By the Poincare sections, the dynamical behaviors of the ring string in the anti-de Sitter–Gauss-Bonnet black hole are studied. A threshold value of the Gauss-Bonnet parameter $\lambda$ is found by the numerical method, below which the behavior of this dynamical system is nonchaotic and above which the behavior becomes gradually chaotic. The chaotic behavior becomes stronger with the increases of the Gauss-Bonnet parameter. It is different from the case in the anti-de Sitter–Schwarzschild black hole, which is weakly chaotic. Furthermore, we confirm our findings by the fast Lyapunov indicator.

We provide a simple and explicit construction of local bulk operators that describe the interior of a black hole in the AdS/CFT correspondence. The existence of these operators is predicated on the assumption that the mapping of CFT operators to local bulk operators depends on the state of the CFT. We show that our construction leads to an exactly local effective field theory in the bulk. Barring the fact that their charge and energy can be measured at infinity, we show that the commutator of local operators inside and outside the black hole vanishes exactly, when evaluated within correlation functions of the CFT. Our construction leads to a natural resolution of the strong subadditivity paradox of Mathur and Almheiri et al. Furthermore, we show how, using these operators, it is possible to reconcile small corrections to effective field theory correlators with the unitarity of black hole evaporation. We address and resolve all other arguments, advanced in A. Almheiri et al. J. High Energy Phys. 09 (2013) 018 and D. Marolf and J. Polchinski, Phys. Rev. Lett. 111, 171301 (2013), in favor of structure at the black hole horizon. We extend our construction to states that are near equilibrium, and thereby also address the “frozen vacuum” objections of R. Bousso, Phys. Rev. Lett. 112, 041102 (2014). Finally, we explore an intriguing link between our construction of interior operators and Tomita-Takesaki theory.

New self-dualities involving two index tensors are derived. These new self-dualities are used to build various duality cascades. Both vectorlike and chiral cascades are presented. Aside from ending in confinement, these duality cascades can also end in interacting conformal field theories, free field theories, and metastable supersymmetry breaking. Higgsing effects are built into the self-duality so that when the gauge groups are small enough, supersymmetry is broken through the rank condition. Dynamical supersymmetry restoration occurs far from the SUSY breaking vacuum resulting in a long-lived metastable vacuum. It is found that Coulomb branches are critical in the stabilization of runaways and dynamical supersymmetry restoration.

The Starobinsky inflationary model of $(R+R^2)$ gravity is extended to the new-minimal $(40+40)$ off-shell 4D, $\mathrm{N}=2$ supergravity in $\mathrm{N}=2$ chiral (curved) superspace. In its dual formulation, as a matter-coupled $\mathrm{N}=2$ Einstein supergravity, the inflaton belongs to a massive $\mathrm{N}=2$ vector multiplet.

Unruh-DeWitt detectors interacting locally with a quantum field are systems under consideration for relativistic quantum information processing. In most works, the detectors are assumed to be pointlike and, therefore, couple with the same strength to all modes of the field spectrum. We propose the use of a more realistic detector model where the detector has a finite size conveniently tailored by a spatial profile. We design a spatial profile such that the detector, when inertial, naturally couples to a peaked distribution of Minkowski modes. In the uniformly accelerated case, the detector couples to a peaked distribution of Rindler modes. Such distributions are of special interest in the analysis of entanglement in noninetial frames. We use our detector model to show the noise detected in the Minkowski vacuum and in single particle states is a function of the detector’s acceleration.

The nearby Universe is expected to create an anisotropic stochastic gravitational-wave background (SGWB). Different algorithms have been developed and implemented to search for isotropic and anisotropic SGWBs. The aim of this paper is to quantify the advantage of an optimal anisotropic search, specifically comparing a point source with an isotropic background. Clusters of galaxies appear as point sources to a network of ground-based laser-interferometric detectors. The optimal search strategy for these sources is a “directed radiometer search.” We show that the flux of SGWBs created by the millisecond pulsars in the Virgo cluster produces a significantly stronger signal than the nearly isotropic background of unresolved sources of the same kind. We compute their strain power spectra for different cosmologies and the distribution of populations over redshifts. We conclude that a localized source, like the Virgo cluster, can be resolved from the isotropic background with very high significance using the directed-search algorithm. For backgrounds dominated by nearby sources, up to a redshift of about 3, we show that the directed search for a localized source can have a signal-to-noise ratio that is greater than that for the all-sky integrated isotropic search.