We systematically study two-body nonleptonic decays of light lambda hyperon $\mathrm{\Lambda }\to p{\pi }^{-}(n{\pi }^0)$ with account for both short- and long-distance effects. The short-distance effects are induced by five topologies of external and internal weak $W^{\pm }$ exchange, while long-distance effects are saturated by an inclusion of the so-called pole diagrams with intermediate ${\frac{1}{2}}^{+}$ and ${\frac{1}{2}}^{-}$ baryon resonances. The contributions from ${\frac{1}{2}}^{+}$ resonances are calculated straightforwardly by account for nucleon and $\mathrm{\Sigma }$ baryons whereas the contributions from ${\frac{1}{2}}^{-}$ resonances are calculated by using the well-known soft-pion theorem in the current-algebra approach. It allows one to express the parity-violating $S$-wave amplitude in terms of parity-conserving matrix elements. From our previous analysis of heavy baryons we know that short-distance effects induced by internal topologies are not suppressed in comparison with external $W$-exchange diagram and must be included for description of data. Here, in the case of $\mathrm{\Lambda }$ decays we found that the contribution of external and internal $W$-exchange diagrams is sizably suppressed, e.g., by one order of magnitude in comparison with data, which are known with quite good accuracy. Pole diagrams play the major role to get consistency with experiment.

The deployment of a low-noise 3 kg p-type point contact germanium detector at the Dresden-II power reactor, 8 meters from its $2.96{\mathrm{GW}}_{\mathrm{th}}$ core, is described. This location provides an unprecedented (anti)neutrino flux of $8.1\times {10}^{13}\overline{{\nu }_e}/{\mathrm{cm}}^2\mathrm{s}$. When combined with the $0.2{\mathrm{keV}}_{ee}$ detector threshold achieved, a first measurement of $\mathrm{CE}\nu \mathrm{NS}$ from a reactor source appears to be within reach. We report on the characterization and abatement of backgrounds during initial runs, deriving improved limits on extensions of the Standard Model involving a light vector mediator, from preliminary data.

The relation between the specific shear viscosity $\eta /s$ and the dimensionless jet quenching parameter $\widehat{q}/T^3$ in perturbative QCD is explored at next-to-leading order in the coupling constant. It is shown that the relation changes little, although both transport coefficients independently are subject to large modifications at the next-to-leading order level. This finding confirms that the relationship is robust.

In recent times, a considerable effort has been dedicated to identify certain conditions—the so-called swampland conjectures—with an eye on identifying effective theories which have no consistent UV-completions in string theory. In this paper, we examine the anti–de Sitter vacua corresponding to solutions which arise from purely nonperturbative contributions to the superpotential and show that these solutions satisfy the (axionic) weak gravity conjecture and the AdS-moduli scale separation conjecture, without particular fine-tuning of the parameters. We also sketch out their advantages over other constructions.

We argue that the choice of boundary condition for the wave function in quantum cosmology depends on the UV completion of general relativity. We provide an explicit example using a braneworld scenario in which a de Sitter cosmology is induced on the surface of a Coleman-de Luccia bubble in a 5-dimensional AdS space. The corresponding boundary conditions are unambiguously fixed by demanding consistency with the known physics of bubble nucleation and this selects the Vilenkin weighting for the amplitude from a 4D viewpoint.

In a previous paper it was shown how to calculate the ground-state energy density $\mathcal{E}$ and the $p$-point Green’s functions $G_p(x_1,x_2,\dots ,x_p)$ for the $\mathcal{PT}$-symmetric quantum field theory defined by the Hamiltonian density $\mathcal{H}=\frac{1}{2}(\nabla \varphi {)}^2+\frac{1}{2}{\varphi }^2(i\varphi {)}^{ϵ}$ in $D$-dimensional Euclidean spacetime, where $\varphi$ is a pseudoscalar field. In this earlier paper $\mathcal{E}$ and $G_p(x_1,x_2,\dots ,x_p)$ were expressed as perturbation series in powers of $ϵ$ and were calculated to first order in $ϵ$. (The parameter $ϵ$ is a measure of the nonlinearity of the interaction rather than a coupling constant.) This paper extends these perturbative calculations to the Euclidean Lagrangian $\mathcal{L}=\frac{1}{2}(\nabla \varphi {)}^2+\frac{1}{2}{\mu }^2{\varphi }^2+\frac{1}{2}g{\mu }_0^2{\varphi }^2(i{\mu }_0^{1-D/2}\varphi {)}^{ϵ}-iv\varphi$, which now includes renormalization counterterms that are linear and quadratic in the field $\varphi$. The parameter $g$ is a dimensionless coupling strength and ${\mu }_0$ is a scaling factor having dimensions of mass. Expressions are given for the one-, two-, and three-point Green’s functions, and the renormalized mass, to higher order in powers of $ϵ$ in $D$ dimensions ($0\le D\le 2$). Renormalization is performed perturbatively to second order in $ϵ$ and the structure of the Green’s functions is analyzed in the limit $D\to 2$. A sum of the most divergent terms is performed to all orders in $ϵ$. Like the Cheng-Wu summation of leading logarithms in electrodynamics, it is found here that leading logarithmic divergences combine to become mildly algebraic in form. Future work that must be done to complete the perturbative renormalization procedure is discussed.

In a recent work Bender et al. [Phys. Rev. D 98, 125003 (2018)] proposed to study non-Hermitian $\mathcal{P}\mathcal{T}$-symmetric quantum field theories within the framework of the logarithmic expansion. For a single component scalar field theory, the $\mathcal{P}\mathcal{T}$-symmetric interaction term is written as $g{\varphi }^2(i\varphi {)}^{\epsilon }$ (generic values of $\epsilon$). The logarithmic expansion is obtained by considering $\epsilon$ as a small parameter, and expanding $(i\varphi {)}^{\epsilon }$ in powers of $\epsilon$. Approximations to Green’s functions ${\mathcal{G}}_n$ are obtained by truncating the interaction at finite orders in $\epsilon$, and the first order contribution was calculated by Bender et al. The value of $\epsilon$ that corresponds to the original theory is then replaced in the final results. It was also suggested that this expansion could be used to implement a systematic renormalization of the theory order by order in $\epsilon$. Using techniques that we developed recently for the analysis of a Hermitian scalar theory, in the present work we calculate Green’s functions at $\mathcal{O}({\epsilon }^2)$, pushing also the analysis to higher orders. We find that, at each finite order in $\epsilon$, the theory is noninteracting for any dimension $d\ge 2$. Therefore, differently from the weak-coupling and the $\hslash$ expansions, a systematic renormalization of the theory order by order in $\epsilon$ cannot be realized. Actually, as long as we limit ourselves to finite orders in $\epsilon$, it is not even possible to define the theory. We are then lead to consider resummations, and we start by resumming the ultraviolet leading diagrams. Unfortunately, the results are quite poor, as these resummations simply give the lowest order results of the weak-coupling expansion. We also consider the resummation of subleading terms, but the outcome does not improve much: we get nothing more than the $\mathcal{O}(g^2)$ weak-coupling results.

The asymptotic approach derived by Kozameh-Quiroga provides a modern framework to obtain the evolution of global variables of isolated sources of gravitational radiation. We test the Kozameh-Quiroga formalism evolving the equations of motion for the center of mass, the intrinsic angular momentum, and several other global variables, for black hole binary coalescence. First, we evolve the equations of motion using 777 simulations from the RIT catalog of numerical data of ${\psi }_4$ [J. Healy and C. O. Lousto, Third RIT binary black hole simulations catalog, Phys. Rev. D 102, 104018 (2020).]. We then analyze the trajectory of the center of mass and compute the final state of other physical variables after the coalescence has taken place. Finally, we show that the results obtained from our equations of motion are consistent with those in the Rochester metadata.

We study the prospects of future gravitational wave (GW) detectors in probing primordial black hole (PBH) binaries. We show that across a broad mass range from ${10}^{-5}{M}_{\odot }$ to ${10}^7{M}_{\odot }$, future GW interferometers provide a potential probe of the PBH abundance that is more sensitive than any currently existing experiment. In particular, we find that galactic PBH binaries with masses as low as ${10}^{-5}{M}_{\odot }$ may be probed with ET, AEDGE and LISA by searching for nearly monochromatic continuous GW signals. Such searches could independently test the PBH interpretation of the ultrashort microlensing events observed by OGLE. We also consider the possibility of observing GWs from asteroid mass PBH binaries through graviton-photon conversion.

We show that if dark energy evolves in time, its dynamical component could be dominated by a bath of dark radiation. Within current constraints this radiation could have up to $\sim {10}^3$ times more energy density than the cosmic microwave background. We demonstrate particular models in which a rolling scalar field generates different forms of dark radiation such as hidden photons, millicharged particles, and even Standard Model neutrinos. We find the leading effect on the late-time cosmological expansion history depends on a single parameter beyond the standard cosmological model, namely the temperature of the dark radiation today. Cosmological observations of this modified expansion rate could provide a striking signature of this scenario. The dark radiation itself could even be directly detectable in laboratory experiments, suggesting a broader experimental program into the nature of dark energy.

Axionlike particles (ALPs) are predicted in some well-motivated theories beyond the Standard Model. The TeV gamma-rays from active galactic nuclei (AGN) suffer attenuation by the pair production interactions with the cosmic background light (EBL/CMB) during its travel to the earth. The attenuation can be circumvented through photon-ALP conversions in the AGN and Galaxy magnetic-field, and a flux enhancement is expected to arise in the observed spectrum. In this work, we study the potential of the AGN gamma-ray spectrum for energy up to above 100 TeV to probe ALP-parameter space at around $\mu \mathrm{eV}$, where the coupling $g_{a\gamma }$ is so far relatively weakly constrained. We find the nearby and bright sources, Mrk 501, IC 310 and M 87, are suitable for our objective. Assuming an intrinsic spectrum exponential cutoff energy, we extrapolate the observed spectra of these sources up to above 100 TeV by the models with/without ALPs. For $g_{a\gamma }\gtrsim 2\times {10}^{-11}{\mathrm{GeV}}^{-1}$ with $m_a\lesssim 0.5\mu \mathrm{eV}$, the flux at around 100 TeV predicted by the ALP model can be enhanced more than an order of magnitude than that from the standard absorption, and could be detected by LHAASO. Our result is subject to the uncertainty from the intrinsic cutoff energy and the AGN lobe (or plume) magnetic-field. For an optimistic estimation, the constraint can be improved to $g_{a\gamma }\gtrsim 2\times {10}^{-11}{\mathrm{GeV}}^{-1}$ with $m_a\lesssim 1\mu \mathrm{eV}$. This require further observations on these sources by the forthcoming CTA, LHAASO, SWGO and so on.

We compute corrections to the hard thermal (or dense) loop photon polarization tensor associated to a small mass $m$ of the fermions of an electromagnetic plasma at high temperature $T$ (or chemical potential $\mu$). To this aim we use the on-shell effective field theory, amended with mass corrections. We also carry out the computation using transport theory, reaching to the same result. Intermediate steps in the computations reveal the presence of potential infrared divergencies. We use dimensional regularization, as it is respectful with the gauge symmetry, and then show that all infrared divergencies cancel in the final result. We compare the mass corrections with both the power and two-loop corrections, and claim that they are equally important if the mass is soft, that is, of order $eT$ (or $e\mu$), where $e$ is the gauge coupling constant, but are dominant if the mass obeys $eT<m\ll T$ (or $e\mu <m\ll \mu$).

We show that QCD instantons can generate large effects at small length scales in the ultraviolet in standard composite Higgs models that utilize partial compositeness. This has important implications for possible solutions of the strong $CP$ problem in these models. First we show that in the simplest known UV completions of composite Higgs models, if an axion is also present, it can have a mass much larger than the usual QCD axion. Even more remarkable is the case where there are no axions, but the strong $CP$ problem can be solved by generating the up quark mass entirely from the contribution of instantons thus reviving the massless up-quark solution for these models. In both cases no additional field content is required apart from what is required to realize partial compositeness.

We point out a novel role for the Standard Model neutrino in dark matter phenomenology where the exchange of neutrinos generates a long-range potential between dark matter particles. The resulting dark matter self interaction could be sufficiently strong to impact small-scale structure formation, without the need of any light dark force carrier. This is a generic feature of theories where dark matter couples to the visible sector through the neutrino portal. It is highly testable with improved decay rate measurements at future $Z$, Higgs, and $\tau$ factories, as well as precision cosmology.

In this work we carry out an exhaustive study to find quark mass matrices in the Standard Model (SM), with the maximum number of texture zeros consistent with the experimental data. We found four viable configurations of five texture zeros that adjust the quark masses, the mixing angles and the $CP$ violation phase, with deviations below $1\sigma$ level respect to the current SM best fit values. One of the most important aspects of this work is an economic procedure to find the texture zeros: we resort to the weak basis transformation method, which, as we will show, exhaustively search every possible configuration. We report various leading order relations between the mixing angles and the quark masses for each case.

Quantum chromodynamics (QCD) claims that the major source of the nucleon invariant mass is not the Higgs mechanism but the trace anomaly in the QCD energy-momentum tensor. Although experimental and theoretical results support such a conclusion, a direct demonstration is still absent. We present the first lattice QCD calculation of the quark and gluon trace anomaly contributions to the hadron masses, using the overlap fermion on the $2+1$-flavor dynamical domain wall quark ensemble at $m_{\pi }=340\mathrm{MeV}$ and lattice spacing $a=0.1105\mathrm{fm}$. The result shows that the gluon trace anomaly contributes to most of the nucleon mass, the contribution in the pion state is smaller than that in others nearly by a factor of $\sim 10$, and the gluon trace anomaly density in the center of the pion is negative. The gluon trace anomaly coefficient $\beta /g^3=-0.056(6)$ we obtained is consistent with its regularization-independent leading-order value $(-11+\frac{2N_f}{3})/(4\pi {)}^2$ perfectly.

We propose an analysis method for the leading-twist operator product expansion based lattice QCD determinations of the valence parton distribution function (PDF). In the first step, we determine the confidence-intervals of the leading-twist $\overline{\mathrm{MS}}$ Wilson coefficients, $C_n({\mu }^2{z}^2)$, of the equal-time bilocal quark bilinear, given the lattice QCD matrix element of Ioffe-time distribution for a particular hadron $H$ as well as the prior knowledge of the valence PDF, $f(x,\mu )$ of the hadron $H$ determined via global fit from the experimental data. In the next step, we apply the numerically estimated $C_n$ in the lattice QCD determinations of the valence PDFs of other hadrons, and for the zero-skewness generalized parton distribution (GPD) of the same hadron $H$ at nonzero momentum transfers. Our proposal still assumes the dominance of leading-twist terms, but it offers a pragmatic alternative to the usage of perturbative Wilson coefficients and their associated higher-loop uncertainties such as the effect of all-order logarithms at larger sub-Fermi quark-antiquark separations $z$.

Hamiltonian formulation of lattice gauge theories (LGTs) is the most natural framework for the purpose of quantum simulation, an area of research that is growing with advances in quantum-computing algorithms and hardware. It, therefore, remains an important task to identify the most accurate, while computationally economic, Hamiltonian formulation(s) in such theories, considering the necessary truncation imposed on the Hilbert space of gauge bosons with any finite computing resources. This paper is a first step toward addressing this question in the case of non-Abelian LGTs. Such theories require the imposition of non-Abelian Gauss’s laws on the Hilbert space, introducing additional computational complexity. Focusing on the case of SU(2) LGT in $1+1$ dimensions coupled to one flavor of fermionic matter, a number of different formulations of the original Kogut-Susskind framework are analyzed with regard to the dependence of the dimension of the physical Hilbert space on boundary conditions, system size, and the cutoff on the excitations of gauge bosons. The impact of such dependencies on the accuracy of the spectrum and dynamics obtained from a Hamiltonian computation is examined, and the (classical) computational-resource requirements given these considerations are studied. Besides the well-known angular-momentum formulation of the theory, the cases of purely fermionic and purely bosonic formulations (with open boundary conditions) and the loop-string-hadron formulation are analyzed, along with a brief discussion of a quantum-link-model formulation of the same theory. Clear advantages are found in working with the loop-string-hadron framework which implements non-Abelian Gauss’s laws a priori using a complete set of gauge-invariant operators. It is argued that the substantially reduced cost of simulation within the loop-string-hadron formulation compared with the angular-momentum basis has implications for more efficient and robust quantum simulations of the same theory. Future studies will extend this investigation to the analysis of resource requirements for quantum simulations of non-Abelian LGT, with the goal of shedding light on the most efficient Hamiltonian formulation of gauge theories of relevance in nature.

We investigate the two-dimensional transverse charge distributions of the transversely polarized nucleon. As the longitudinal momentum ($P_z$) of the nucleon increases, the electric dipole moment is induced, which causes the displacement of the transverse charge and magnetization distributions of the nucleon. The induced dipole moment of the proton reaches its maximum value at around $P_z\approx 3.2\mathrm{GeV}$ due to the kinematical reason. We also investigate how the Abel transformations map the three-dimensional charge and magnetization distributions in the Breit frame onto the transverse charge and magnetization ones in the infinite momentum frame.