The behavior of the $\varphi$ meson at finite density is studied, making use of a QCD sum rule approach in combination with the maximum entropy method. It is demonstrated that a possible mass shift of the $\varphi$ in nuclear matter is strongly correlated to the strangeness content of the nucleon, which is proportional to the strange sigma term, ${\sigma }_{sN}=m_s⟨N|\overline{s}s|N⟩$. Our results furthermore show that, depending on the value of ${\sigma }_{sN}$, the $\varphi$ meson could receive both a positive or negative mass shift at nuclear matter density. We find that these results depend only weakly on potential modifications of the width of the $\varphi$ peak and on assumptions made on the behavior of four-quark condensates at finite density. To check the stability of our findings, we take into account several higher order corrections to the operator product expansion, including ${\alpha }_s$-corrections, terms of higher order in the strange quark mass, and terms of higher twist that have not been considered in earlier works.

The spectrum of electrons from muons decaying in an atomic bound state is significantly modified by their interaction with the nucleus. Somewhat unexpectedly, its first measurement, at the Canadian laboratory TRIUMF, differed from basic theory. We show, using a combination of techniques developed in atomic, nuclear, and high-energy physics, that radiative corrections eliminate the discrepancy. In addition to solving that outstanding problem, our more precise predictions are potentially useful for interpreting future high-statistics muon experiments that aim to search for exotic interactions at ${10}^{-16}$ sensitivity.

Discretized formulations of 2-form Abelian and non-Abelian gauge fields on $d$-dimensional hypercubic lattices have been discussed in the past by various authors and most recently by Lipstein and Reid-Edwards [J. High Energy Phys. 09 (2014) 034]. In this paper we recall that the Hamiltonian of a ${\mathbb{Z}}_2$ variant of such theories is one of the family of generalized Ising models originally considered by Wegner. For such “${\mathbb{Z}}_2$ lattice Gerbe theories” general arguments can be used to show that a phase transition for Wilson surfaces will occur for $d>3$ between volume and area scaling behavior. In $3d$ the model is equivalent under duality to an infinite coupling model and no transition is seen, whereas in $4d$ the model is dual to the $4d$ Ising model and displays a continuous transition. In $5d$ the ${\mathbb{Z}}_2$ lattice Gerbe theory is self-dual in the presence of an external field and in $6d$ it is self-dual in zero external field.

When global symmetries are spontaneously broken in supersymmetric vacua, there appear quasi-Nambu-Goldstone (NG) fermions as superpartners of NG bosons. In addition to these, there can appear quasi-NG bosons in general. The quasi-NG bosons and fermions together with the NG bosons are organized into chiral multiplets. Kähler potentials of low-energy effective theories were constructed some years ago as supersymmetric nonlinear realizations. It is known that higher-derivative terms in the superfield formalism often encounter the auxiliary field problem; the auxiliary fields that accompanied with space-time derivatives and cannot be eliminated. In this paper, we construct higher-derivative corrections to supersymmetric nonlinear realizations in the off-shell superfield formalism free from the auxiliary field problem. As an example, we present the manifestly supersymmetric chiral Lagrangian.

We study the higher derivative chiral models with four supercharges and Bogomol’nyi–Prasad–Sommerfield (BPS) states in these models. The off-shell Lagrangian generically includes higher powers of the auxiliary fields $F$, which causes distinct on-shell branches associated with the solutions to the auxiliary fields equation. We point out that the model admits a supersymmetric completion of arbitrary higher derivative bosonic models of a single complex scalar field, and an arbitrary scalar potential can be introduced even without superpotentials. As an example, we present a supersymmetric extension of the Faddeev–Skyrme model without four time derivatives, in contrast to the previously proposed supersymmetric Faddeev–Skyrme-like model containing four time derivatives. In general, higher derivative terms together with a superpotential result in deformed scalar potentials. We find that higher derivative corrections to $1/2$ BPS domain walls and $1/2$ BPS lumps are exactly canceled out, while the $1/4$ BPS lumps (as compact baby Skyrmions) depend on a characteristic feature of the higher derivative models. We also find a new $1/4$ BPS condition for domain wall junctions, which generically receives higher derivative corrections.

We study the reflection and transmission coefficients and the absorption cross section for scalar fields in the background of a Lifshitz black hole in three-dimensional conformal gravity with $z=0$, and we show that the absorption cross section vanishes at the low- and high-frequency limits. Also, we determine the quasinormal modes of scalar perturbations, and then we study the stability of these black holes under scalar field perturbations.

In the present work we show that the widely believed pathology of the nonunitarity of anisotropic quantum cosmological models cannot be a generic problem. We exhibit a nontrivial example, a Bianchi-I model with an ultrarelativistic fluid, that has a well-behaved time independent norm. We also show that a suitable operator ordering should produce time independent norms for the wave packets in the case of other more realistic fluids as well.

Several recent works have reported the detection of an unidentified x-ray line at 3.55 keV, which could possibly be attributed to the decay of dark matter (DM) particles in the halos of galaxy clusters and in the M31 galaxy. We analyze all publicly available XMM-Newton satellite data of dwarf spheroidal galaxies to test the possible DM origin of the line. Dwarf spheroidal galaxies have high mass-to-light ratios, and their interstellar medium is not a source of diffuse x-ray emission; thus, they are expected to provide the cleanest DM decay line signal. Our analysis shows no evidence for the presence of the line in the stacked spectra of the dwarf galaxies. It excludes the sterile neutrino DM decay origin of the 3.5 keV line reported by Bulbul et al. (2014) at the level of $4.1\sigma$ under standard assumptions about the Galactic DM column density in the direction of selected dwarf galaxies and at the level of $3.2\sigma$ assuming minimal Galactic DM column density. Our analysis is still consistent with the estimate of sterile neutrino DM parameters by Boyarsky et al. (2014) because of its larger uncertainty. However, the central value of their estimate of the mixing angle is inconsistent with our dwarf spheroidals data at the $3.4\sigma$ ($2.5\sigma$) level assuming the mean (minimal) Galactic DM column density. As a byproduct of our analysis, we provide updated upper limits to the mixing angle of sterile neutrino DM in the mass range between 2 and 20 keV.

We analyze the possible contribution of topological defects to cosmic microwave anisotropies, both temperature and polarization. We allow for the presence of both inflationary scalars and tensors, and of polarized dust foregrounds that may contribute to or dominate the B-mode polarization signal. We confirm and quantify our previous statements that topological defects on their own are a poor fit to the B-mode signal. However, adding topological defects to a model with a tensor component or a dust component improves the fit around $\ell =200$. Fitting simultaneously to both temperature and polarization data, we find that textures fit almost as well as tensors ($\mathrm{\Delta }{\chi }^2=2.0$), while Abelian Higgs strings are ruled out as the sole source of the B-mode signal at low $\ell$. The 95% confidence upper limits on models combining defects and dust are $G\mu <2.7\times 10^{-7}$ (Abelian Higgs strings), $G\mu <9.8\times 10^{-7}$ (semilocal strings) and $G\mu <7.3\times 10^{-7}$ (textures), a small reduction on the Planck bounds. The most economical fit overall is obtained by the standard $\mathrm{\Lambda }$–cold dark matter model with a polarized dust component.

We provide a cosmological implementation of the evolutionary quantum gravity, describing an isotropic Universe, in the presence of a negative cosmological constant and a massive (preinflationary) scalar field. We demonstrate that the considered Universe has a nonsingular quantum behavior, associated to a primordial bounce, whose ground state has a high occupation number. Furthermore, in such a vacuum state, the super-Hamiltonian eigenvalue is negative, corresponding to a positive emerging dust energy density. The regularization of the model is performed via a polymer quantum approach to the Universe scale factor and the proper classical limit is then recovered, in agreement with a preinflationary state of the Universe. Since the dust energy density is redshifted by the Universe de Sitter phase and the cosmological constant does not enter the ground state eigenvalue, we get a late-time cosmology, compatible with the present observations, endowed with a turning point in the far future.

A warm inflationary universe scenario on a warped Dvali-Gabadadze-Porrati brane during intermediate inflation is studied. We consider a general form for the dissipative coefficient $\mathrm{\Gamma }(T,\varphi )\propto T^m/{\varphi }^{m-1}$, and also study this model in the weak and strong dissipative regimes. We analyze the evolution of the Universe in the slow-roll approximation and find the exact solutions to the equations of motion. In both regimes, we utilize recent data from the BICEP2 experiment and also from the Planck satellite to constrain the parameters in our model in accordance with the theory of cosmological perturbations.

In this paper, we describe an analysis of Apollo-era lunar seismic data that places an upper limit on an isotropic stochastic gravitational-wave background integrated over a year in the frequency range 0.1–1 Hz. We find that because the Moon’s ambient noise background is much quieter than that of the Earth, significant improvements over an Earth-based analysis were made. We find an upper limit of ${\mathrm{\Omega }}_{\mathrm{GW}}<1.2\times {10}^5$, which is 3 orders of magnitude smaller than a similar analysis of a global network of broadband seismometers on Earth and the best limits in this band to date. We also discuss the benefits of a potential Earth-Moon correlation search and compute the time-dependent overlap reduction function required for such an analysis. For this search, we find an upper limit an order of magnitude larger than the Moon-Moon search.

In the minimal left-right model the choice of left-right symmetry is twofold: either generalized parity $\mathcal{P}$ or charge conjugation $\mathcal{C}$. In the minimal model with spontaneously broken strict $\mathcal{P}$, a large tree-level contribution to strong $CP$ violation can be computed in terms of the spontaneous phase $\alpha$. Searches for the neutron electric dipole moments then constrain the size of $\alpha$. Following the latest update on indirect $CP$ violation in the kaon sector, a bound on $W_R$ mass at 20 TeV is set. Possible ways out of this bound require a further hypothesis, either a relaxation mechanism or explicit breaking of $\mathcal{P}$. To this end, the chiral loop of the neutron electric dipole moment at next-to-leading order is recomputed and provides an estimate of the weak contribution. Combining this constraint with other $CP$-violating observables in the kaon sector allows for $M_{W_R}\gtrsim 3\mathrm{TeV}$. On the other hand, $\mathcal{C}$ symmetry is free from such constraints, leaving the right-handed scale within the experimental reach.

In this paper, we analyze the Higgs sector of the minimal $S(3)$-invariant extension of the Standard Model. This extension includes three Higgs SU(2) doublets fields and $CP$ invariant. We compute the Higgs boson physical masses in terms of the potential parameters and the scalar Higgs matrix rotation angles ${\theta }_S$ and ${\omega }_3$ ($\tan {\theta }_P=\tan {\theta }_C=\cot {\omega }_3$). The angles ${\theta }_S$, ${\theta }_P$ and ${\theta }_C$ are related to the scalar, pseudoscalar and charged Higgs matrix rotation respectively. Furthermore, within this model we can also write down in an explicit form the trilinear self-couplings ${\lambda }_{ijk}$ in terms of the Higgs masses and two free parameters, ${\theta }_S$ and ${\omega }_3$. Moreover, we show that the Higgs masses and trilinear Higgs boson self-couplings are closely linked to the Higgs potential structure given by the discrete symmetry $S(3)$, which can be helpful in distinguishing this model from other extensions. In our analysis the lightest Higgs boson mass is taken to be fixed to 125 GeV. In concordance with the results reported in the literature for other Standard Model extensions, one finds that the numerical values ${\lambda }_{ijk}$ of the minimal $S(3)$-invariant extension of the Standard Model are significantly different from the trilinear Higgs self-coupling of the Standard Model.

We develop a first-principle generalized density-of-states method for numerically studying quantum field theories with a complex action. As a proof of concept, we show that with our approach we can numerically solve the strong sign problem of the $Z_3$ spin model at finite density. Our results are confirmed by standard simulations of the theory dual to the considered model, which is free from a sign problem. Our method opens new perspectives on ab initio simulations of cold dense quantum systems, and in particular of Yang-Mills theories with matter at finite densities, for which Monte Carlo-based importance sampling is unable to produce sufficiently accurate results.

We study QCD under the influence of background magnetic fields and isospin chemical potentials using lattice simulations. This setup exhibits a sign problem which is circumvented using a Taylor expansion in the magnetic field. The ground state of the system in the pion condensation phase is found to exhibit a pronounced diamagnetic response. We elaborate on how this diamagnetism may contribute to the pressure balance in the inner core of strongly magnetized neutron stars. In addition we show that the onset of pion condensation shifts to larger chemical potentials due to the enhancement of the charged pion mass for growing magnetic fields. Finally, we summarize the magnetic nature of QCD matter on the temperature-isospin chemical potential phase diagram.

The annihilation process $p\overline{p}\to p{D}^0{\overline{\mathrm{\Lambda }}}_c(2286)$ is studied taking into account $t$-channel $D^0$, $D^{*0}$ meson exchange and the resonance contribution of ${\mathrm{\Lambda }}_c(2286)$ and ${\mathrm{\Lambda }}_c(2940)$ baryons. We assume that the ${\mathrm{\Lambda }}_c(2940)$ baryon is a $p{D}^{*0}$ molecular state with spin-parity ${\frac{1}{2}}^{+}$ and ${\frac{1}{2}}^{-}$. Our results show that near the threshold of $p\overline{p}\to {\mathrm{\Lambda }}_c(2286){\overline{\mathrm{\Lambda }}}_c(2286)$ the contribution from the intermediate state ${\mathrm{\Lambda }}_c(2940)$ is also sizeable and can be observed at the $\overline{P}\mathrm{ANDA}$ experiment. Another conclusion is that the spin-parity assignment ${\frac{1}{2}}^{-}$ for ${\mathrm{\Lambda }}_c(2940)$ gives enhancement for the cross section in comparison with a choice ${\frac{1}{2}}^{+}$.

$\mathrm{Nucleon}\to \mathrm{\Delta }(1232)$ transition electroweak form factors are discussed in a single pion production model with nonresonant background terms originating from a chiral perturbation theory. Fits to electron-proton scattering $F_2$ as well as neutrino scattering bubble chamber experimental data are performed. Both $\nu$-proton and $\nu$-neutron channel data are discussed in a unified statistical model. A new parametrization of the $N\to \mathrm{\Delta }(1232)$ vector form factors is proposed. In the case of model with deuteron nuclear effects fit to neutrino scattering data gives the axial mass $M_{A\mathrm{\Delta }}={0.85}_{-0.08}^{+0.09}\mathrm{GeV}$ and $C_5^A(0)={1.10}_{-0.14}^{+0.15}$ in accordance with the Goldberger-Treiman relation. However, the consistency is spoiled when the deuteron effects are omitted; i.e., in this case the fit gives the axial mass $M_{A\mathrm{\Delta }}=0.81_{-0.09}^{+0.09}\mathrm{GeV}$ and $C_5^A(0)=0.93_{-0.13}^{+0.13}$.

Using $1.06\times 10^8$ $\psi (3686)$ events recorded in $e^{+}{e}^{-}$ collisions at $\sqrt{s}=3.686\mathrm{GeV}$ with the BESIII at the BEPCII collider, we present searches for $C$-parity violation in $J/\psi \to \gamma \gamma$ and $\gamma \varphi$ decays via $\psi (3686)\to J/\psi {\pi }^{+}{\pi }^{-}$. No significant signals are observed in either channel. Upper limits on the branching fractions are set to be $\mathcal{B}(J/\psi \to \gamma \gamma )<2.7\times 10^{-7}$ and $\mathcal{B}(J/\psi \to \gamma \varphi )<1.4\times 10^{-6}$ at the 90% confidence level. The former is one order of magnitude more stringent than the previous upper limit, and the latter represents the first limit on this decay channel.

We study relevant deformations of conformal field theory on a cylinder using conformal perturbation theory, and in particular the one-point function of the deformation operator and the energy in a system after a quench. We do the one-point function calculation in both AdS and the conformal field theory and we show that the results match. Our calculations are done with arbitrary spacetime dimension, as well as arbitrary scaling dimension of the relevant operator. The only singularities that appear in the end calculation can be related to logarithmic singularities in dimensional regularization. We also study time-dependent setups in the field theory and we show how the response of the system can be calculated in a Hamiltonian-based approach. We use this procedure to explain certain short time universal results that have been found previously.