A detailed study of vortices is presented in Ginzburg-Landau (or Abelian Higgs) models with two complex scalars (order parameters) assuming a general $\mathrm{U}(1)\times \mathrm{U}(1)$ symmetric potential. Particular emphasis is given to the case in which only one of the scalars obtains a vacuum expectation value (VEV). It is found that for a significantly large domain in parameter space vortices with a scalar field condensate in their core [condensate core (CC)] coexist with Abrikosov-Nielsen-Olesen (ANO) vortices. Importantly, CC vortices are stable and have lower energy than the ANO ones. Magnetic bags or giant vortices of the order of 1000 flux quanta are favored to form for the range of parameters (“strong couplings”) appearing for the superconducting state of liquid metallic hydrogen (LMH). Furthermore, it is argued that finite energy/unit length 1VEV vortices are smoothly connected to fractional flux 2VEV ones. Stable, finite energy CC-type vortices are also exhibited in the case when one of the scalar fields is neutral.

The leading order of the large $N$ limit of the $\mathrm{O}(N)$ symmetric phi-six theory in three dimensions has a phase which exhibits spontaneous breaking of scale symmetry accompanied by a massless dilaton which is a Goldstone boson. At the next-to-leading order in large $N$, the phi-six coupling has a beta function of order $1/N$ and it is expected that the dilaton acquires a small mass, proportional to the beta function and the condensate. In this article, we show that this “light dilaton” is actually a tachyon. This indicates an instability of the phase of the theory with spontaneously broken approximate scale invariance.

We consider a real, massive scalar field on ${\text{PAdS}}_{d+1}$, the Poincaré domain of the ($d+1$)-dimensional anti–de Sitter (AdS) spacetime. We first determine all admissible boundary conditions that can be applied on the conformal boundary, noting that there exist instances where “bound states” solutions are present. Then, we address the problem of constructing the two-point function for the ground state satisfying those boundary conditions, finding ultimately an explicit closed form. In addition, we investigate the singularities of the resulting two-point functions, showing that they are consistent with the requirement of being of Hadamard form in every globally hyperbolic subregion of ${\text{PAdS}}_{d+1}$ and proposing a new definition of Hadamard states which applies to ${\text{PAdS}}_{d+1}$.

For a generic conformal field theory (CFT) in four dimensions, the scale anomaly dictates that on conformally flat backgrounds, the universal part of entanglement entropy across a sphere [${\mathcal{C}}_{\text{univ}}(S^2)$] is positive. Based on this fact, we explore the consequences of assuming a positive sign for ${\mathcal{C}}_{\text{univ}}(S^2)$ on such backgrounds in a four-dimensional scale-invariant theory (SFT). In the absence of a dimension two scalar operator ${\mathcal{O}}_2$ in the spectrum of a SFT, we show that this assumption suggests that SFT is a CFT. In the presence of ${\mathcal{O}}_2$, we show that this assumption can fix the coefficient of the nonlinear coupling term $\int d^{4}x\sqrt{g}R{\mathcal{O}}_2$ to a conformal value.

Vacuum polarization of scalar fields in the background of a long throat is investigated. The field is assumed to be both massive or massless, with arbitrary coupling to the scalar curvature, and in a thermal state at an arbitrary temperature. Analytical approximation for ${⟨{\phi }^2⟩}_{\text{ren}}$ is obtained.

Critical collapse of a spherically symmetric domain wall is investigated. The domain wall is made of a minimally coupled scalar field with a double well potential. We consider a sequence of the initial data which describe a momentarily static domain wall characterized by its initial radius. The time evolution is performed by a full general relativistic numerical code for spherically symmetric systems. In this paper, we use the maximal slice gauge condition, in which spacelike time slices may penetrate the black hole horizon differently from other widely used procedures. In this paper, we consider two specific shapes of the double well potential, and observe the Type II critical behavior in both cases. The mass scaling, subcritical curvature scaling, and those fine structures are confirmed. The index of the scaling behavior agrees with the massless scalar case.

The existence of interactions between dark matter and dark energy has been widely studied, since they can fit well the observational data and may provide new physics through such an interaction. In this work, we analyze these models and investigate their potential relation with future cosmological singularities. We find that every future singularity found in the literature can be mapped into a singularity of the interaction term, that we call the $Q$ singularity, where the energy flow between the dark components diverges. Furthermore, this framework allows us to identify a new type of future singularity induced by the divergence of the first derivative of the dark energy equation of state parameter.

In this paper, we investigate the possibility of setting a model of a nonsingular universe in the context of the extended Chaplygin gas model with the equation of state $p=A\rho -\frac{B}{{\rho }^{\alpha }}$ through the framework of four-dimensional Friedmann-Robertson-Walker background. We find the following solutions of the singularity-free cosmological model: a cyclic universe with the minimal and maximal values of the scale factor that remains the same in every cycle, for an open universe with $k=-1$ and a negative cosmological constant; a nonsingular oscillating universe as a single bouncing solution for the cases of $k=0$ and $k=1$ curvature; and an oscillating universe with the minimal and maximal values of the scale factor that periodically rises up and down in the presence of a self-interacting scalar field model for all cases of the curved universe (with $k=-1$, $k=0$ and $k=1$). We also study whether a nonsingular bounce requires violation of the null energy condition.

Future observations of 21 cm emission using neutral hydrogen intensity mapping will enable us to probe the large scale structure of the Universe over very large survey volumes within a reasonable observation time. We demonstrate that the three-dimensional information contained in such surveys will be an extremely powerful tool in searching for features that were imprinted in the primordial power spectrum and bispectrum during inflation. Here, we focus on the “resonant” and “step” inflation models and forecast the potential of upcoming 21 cm experiments to detect these inflationary features in the observable power spectrum and bispectrum. We find that the full scale Tianlai experiment and the Square Kilometre Array have the potential to improve on the sensitivity of current cosmic microwave background experiments by several orders of magnitude.

Primordial gravitational waves constitute a promising probe of the very early Universe and the laws of gravity. We study in this work changes to tensor-mode perturbations that can arise in various proposed modified gravity theories. These include additional friction effects, nonstandard dispersion relations involving a massive graviton, a modified speed, and a small-scale modification. We introduce a physically motivated parametrization of these effects and use current available data to obtain exclusion regions in the parameter spaces. Taking into account the foreground subtraction, we then perform a forecast analysis focusing on the tensor-mode modified-gravity parameters as constrained by the future experiments COrE, Stage-IV and PIXIE. For a fiducial value of the tensor-to-scalar ratio $r=0.01$, we find that an additional friction of 3.5–4.5% compared to GR will be detected at $3\text{−}\sigma$ by these experiments, while a decrease in friction will be more difficult to detect. The speed of gravitational waves needs to be by 5–15% different from the speed of light for detection. We find that the minimum detectable graviton mass is about $7.8–9.7\times {10}^{-33}\mathrm{eV}$, which is of the same order of magnitude as the graviton mass that allows massive gravity theories to produce late-time cosmic acceleration. Finally, we study the tensor-mode perturbations in modified gravity during inflation using our parametrization. We find that, in addition to being related to $r$, the tensor spectral index would be related to the friction parameter ${\nu }_0$ by $n_T=-3{\nu }_0-r/8$. Assuming that the friction parameter is unchanged throughout the history of the Universe, and that ${\nu }_0$ is much larger than $r$, the future experiments considered here will be able to distinguish this modified-gravity consistency relation from the standard inflation consistency relation, and thus can be used as a further test of modified gravity. In summary, tensor-mode perturbations and cosmic-microwave-background B-mode polarization provide a complementary avenue to test gravity theories.

We employ an ${}^{88}\mathrm{Y}/\mathrm{Be}$ photoneutron source to derive the quenching factor for neutron-induced nuclear recoils in germanium, probing recoil energies from a few hundred ${\mathrm{eV}}_{\mathrm{nr}}$ to $8.5{\mathrm{keV}}_{\mathrm{nr}}$. A comprehensive Monte Carlo simulation of our setup is compared to experimental data employing a Lindhard model with a free electronic energy loss $k$ and an adiabatic correction for $\mathrm{sub}\text{−}{\mathrm{keV}}_{\mathrm{nr}}$ nuclear recoils. The best fit $k=0.179\pm 0.001$ obtained using a Monte Carlo Markov chain (MCMC) ensemble sampler is in good agreement with previous measurements, confirming the adequacy of the Lindhard model to describe the stopping of few-keV ions in germanium crystals at a temperature of $\sim 77\mathrm{K}$. This value of $k$ corresponds to a quenching factor of 13.7% to 25.3% for nuclear recoil energies between 0.3 and $8.5{\mathrm{keV}}_{\mathrm{nr}}$, respectively.

We study collective excitations in hot rotating chiral media in the presence of a magnetic field in kinetic theory, namely, a chiral heat wave and its mixings with a chiral vortical wave and chiral magnetic wave. Our results for velocities of these waves have slight alterations from those obtained earlier. We explain the origin of these alterations and also give the most general expressions for the velocities of all these waves in a hydrodynamic approach.

If massive neutrinos are Dirac particles, the proposed PTOLEMY experiment will hopefully be able to discover the cosmic neutrino background via ${\nu }_e+{}^3\mathrm{H}\to {}^3\mathrm{He}+e^{-}$ with a capture rate of ${\mathrm{\Gamma }}_{\mathrm{D}}\approx 4{\mathrm{yr}}^{-1}$. Recently, it has been pointed out that right-handed components of Dirac neutrinos could also be copiously produced in the early Universe and become an extra thermal or nonthermal ingredient of cosmic relic neutrinos, enhancing the capture rate to ${\mathrm{\Gamma }}_{\mathrm{D}}\approx 5.1{\mathrm{yr}}^{-1}$ or ${\mathrm{\Gamma }}_{\mathrm{D}}\approx 6.1{\mathrm{yr}}^{-1}$. In this work, we investigate the possibility to distinguish between thermal and nonthermal spectra of cosmic relic neutrinos by measuring the annual modulation of the capture rate. For neutrino masses of 0.1 eV, we find that the amplitude of annual modulation in the standard case is $\mathcal{M}\approx 0.05\%$, which will be increased to 0.1% and 0.15% in the presence of additional thermal and nonthermal right-handed neutrinos, respectively. The future detection of such a modulation will be helpful in understanding the Majorana or Dirac nature of massive neutrinos.

We analyze chiral restoration within the $O(N+1)/O(N)$ nonlinear sigma model for large $N$ as an effective theory for low-energy QCD at finite temperature $T$. The free energy is constructed diagrammatically to $\mathcal{O}(T{M}^3)$ in the pion mass expansion, which allows us to derive the quark condensate and the scalar susceptibility in the chiral limit. At this order, we do not have to deal with renormalization, either from divergences from mass tadpoles or from those of higher order loop contributions. Our results for the critical behavior are consistent with expectations from lattice analysis and with previous works where the susceptibility is saturated by the thermal $f_0(500)$ pole.

We investigate a spontaneously broken $U(1{)}_d$ gauge symmetry with a muon-specific dark Higgs. Our first goal is to verify how the presence of a new dark Higgs, $\varphi$, and a dark gauge boson, $V$, can simultaneously face the anomalies from the muon magnetic moment and the proton charge radius. Second, by assuming that $V$ must decay to an electron-positron pair, we explore the corresponding parameter space determined with the low-energy constraints coming from $K\to \mu X$, electron $(g-2{)}_e$, $K\to \mu {\nu }_{\mu }{e}^{+}{e}^{-}$, $K\to \mu {\nu }_{\mu }{\mu }^{+}{\mu }^{-}$, and $\tau \to {\nu }_{\tau }\mu {\nu }_{\mu }{e}^{+}{e}^{-}$. We focus on the scenario where the $V$ mass is below $\sim 2m_{\mu }$ and the $\varphi$ mass runs from few MeV to 250 MeV, with $V$-photon mixing of the order $\sim \mathcal{O}({10}^{-3})$. Among weak process at low energies, we check the influence of the new light vector on kaon decays as well as on the scattering $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}{e}^{+}{e}^{-}$ and discuss the impact of the dark Higgs on $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$. Finally, we consider contributions of the $V$-photon mixing in the decays ${\pi }^0\to \gamma e^{+}{e}^{-}$, $\eta \to \gamma e^{+}{e}^{-}$, $\rho \to \pi e^{+}{e}^{-}$, $K^{*}\to K{e}^{+}{e}^{-}$, and $\varphi (1020)\to \eta e^{+}{e}^{-}$.

A robust mechanism was recently proposed in which thermal freeze-out of WIMPs can provide a unified origin of dark matter and baryon abundances in our universe. We point out that this WIMP-triggered baryogenesis mechanism can exhibit a rich collider phenomenology and be tested at the current and near-future experiments at LHC, even in the case where the WIMPs are completely devoid of SM gauge and Higgs portal interactions, as may be motivated by the persistent null results of WIMP dark matter searches. We catalog a rich array of LHC signatures robustly present in such a scenario. In particular, the simplest such implementation can already offer a very clean signal of a TeV-scale resonance that decays to diphotons with a cross section that can easily be within the reach of the current and near-future LHC runs in the region of parameter space that leads to a successful baryogenesis. Other characteristic signatures include the production of multiple bottom and/or multiple top quarks, promptly or displaced. An even more exotic possibility is the production of two separate sets of isolated emerging jets connected by a charged track, which may require new dedicated studies. Finally, dinucleon decay can also provide a powerful probe of the mechanism.

The energy density and the pressure of SU(3) gauge theory at finite temperature are studied by direct lattice measurements of the renormalized energy-momentum tensor obtained by the gradient flow. Numerical analyses are carried out with $\beta =6.287–7.500$ corresponding to the lattice spacing $a=0.013–0.061\mathrm{fm}$. The spatial (temporal) sizes are chosen to be $N_s=64$, 96, 128 ($N_{\tau }=12$, 16, 20, 22, 24) with the aspect ratio, $5.33\le N_s/N_{\tau }\le 8$. Double extrapolation, $a\to 0$ (the continuum limit) followed by $t\to 0$ (the zero flow-time limit), is taken using the numerical data. Above the critical temperature, the thermodynamic quantities are obtained with a few percent precision including statistical and systematic errors. The results are in good agreement with previous high-precision data obtained by using the integral method.

We compute the gradient expansion for anisotropic hydrodynamics. The results are compared with the corresponding expansion of the underlying kinetic-theory model with the collision term treated in the relaxation time approximation. We find that a recent formulation of anisotropic hydrodynamics based on an anisotropic matching principle yields the first three terms of the gradient expansion in agreement with those obtained for the kinetic theory. This gives further support for this particular hydrodynamic model as a good approximation of the kinetic-theory approach. We further find that the gradient expansion of anisotropic hydrodynamics is an asymptotic series, and the singularities of the analytic continuation of its Borel transform indicate the presence of nonhydrodynamic modes.

Within the framework of higher-twist collinear factorization, transverse momentum broadening for the final hadrons in semi-inclusive deeply inelastic $e+A$ collisions is studied at the next-to-leading order (NLO) in perturbative QCD. Through explicit calculations of real and virtual corrections at twist 4, the transverse-momentum-weighted differential cross section due to double scattering is shown to factorize at NLO and can be expressed as a convolution of twist-4 nuclear parton correlation functions, the usual twist-2 fragmentation functions and hard parts which are finite and free of any divergences. A QCD evolution equation is also derived for the renormalized twist-4 quark-gluon correlation function which can be applied to future phenomenological studies of transverse momentum broadening and jet quenching at NLO.

In this paper, we consider the fragmentation of a parton into a jet with small jet radius $R$. Perturbatively, logarithms of $R$ can appear, which for narrow jets can lead to large corrections. Using soft-collinear effective theory, we introduce the fragmentation function to a jet (FFJ), which describes the fragmentation of a parton into a jet. We discuss how these objects are related to the standard jet functions. Calculating the FFJ to next-to-leading order, we show that these objects satisfy the standard Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations, with a natural scale that depends upon $R$. By using the standard renormalization group evolution, we can therefore resum logarithms of $R$. We further use the soft-collinear effective theory to prove a factorization theorem where the FFJs naturally appear, for the fragmentation of a hadron within a jet with small $R$. Finally, we also show how this formalism can be used to resum the ratio of jet radii for a subjet to be emitted from within a fat jet.