The Galactic center excess (GCE) remains one of the most intriguing discoveries from the Fermi Large Area Telescope (LAT) observations. We revisit the characteristics of the GCE by first producing a new set of high-resolution galactic diffuse gamma-ray emission templates. This diffuse emission, which accounts for the bulk of the observed gamma rays, is ultimately due to cosmic-ray interactions with the interstellar medium. Using recent high-precision cosmic-ray observations, in addition to the continuing Fermi-LAT observations and observations from lower energy photons, we constrain the properties of the galactic diffuse emission. We describe a large set of diffuse gamma-ray emission templates which account for a very wide range of initial assumptions on the physical conditions in the inner galaxy. The broad properties of the GCE that we find in this work are qualitatively unchanged despite the introduction of this new set of templates, though its quantitative features appear mildly different than those obtained in previous analyses. In particular, we find a high-energy tail at higher significance than previously reported. This tail is very prominent in the northern hemisphere, and less so in the southern hemisphere. This strongly affects one prominent interpretation of the excess: known millisecond pulsars are incapable of producing this high-energy emission, even in the relatively softer southern hemisphere, and are therefore disfavored as the sole explanation of the GCE. The annihilation of dark matter particles of mass ${40}_{-7}^{+10}\mathrm{GeV}$ (95% CL) to $b$ quarks with a cross-section of $⟨{\sigma }_{A}v⟩=1.4_{-0.3}^{+0.6}\times {10}^{-26}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ provides a good fit to the excess especially in the relatively cleaner southern sky. Dark matter of the same mass range annihilating to $b$ quarks or heavier dark matter particles annihilating to heavier Standard Model bosons can combine with millisecond pulsars to provide a good fit to the southern hemisphere emission as well, as can a broken power-law spectrum which would be related to recent cosmic-ray burst activity. As part of this paper, we make publicly available all of our templates and the data covariance matrix we have generated to account for systematic uncertainties.

We determine the threshold mass for prompt (no bounce) black hole formation in equal-mass neutron star (NS) mergers using a new set of 227 numerical relativity simulations. We consider 23 phenomenological and microphysical finite-temperature equations of state (EOS), including models with hyperons and first-order phase transitions to deconfined quarks. We confirm the existence of EOS-insensitive relations between the threshold mass, binary tidal parameter at the threshold (${\mathrm{\Lambda }}_{\mathrm{th}}$), maximum mass of nonrotating NSs, and radii of reference mass NSs. We combine the EOS-insensitive relations, phenomenological constraints on NS properties, and observational data from GW170817 to derive an improved lower limit on radii of maximum mass and a $1.6{\mathrm{M}}_{\odot }$ NS of 9.81 and 10.90 km, respectively. We also constrain the radius and quadrupolar tidal deformability ($\mathrm{\Lambda }$) of a $1.4{\mathrm{M}}_{\odot }$ NS to be larger than 10.74 km and 172, respectively. We consider uncertainties in all independent parameters—fitting coefficients as well as GW170817 masses while reporting the range of radii constraints. We discuss an approach to constrain the upper as well as lower limit of NS maximum mass using future binary NS detections and their identification as prompt or delayed collapse. With future observations, it will be possible to derive even tighter constraints on the properties of matter at and above nuclear density using the method proposed in this work.

Application of data mining and machine learning techniques can significantly improve the sensitivity of current interferometric gravitational-wave detectors. Such instruments are complex multi-input single-output systems, with close-to-linear dynamics and hundreds of active feedback control loops. We show how the application of brute-force data-mining techniques allows us to discover correlations between auxiliary monitoring channels and the main gravitational-wave output channel. We also discuss the result of the application of a parametric and time-domain noise subtraction algorithm, that allows a significant improvement of the detector sensitivity at frequencies below 30 Hz.

The axion provides a solution for the strong $CP$ problem and is one of the leading candidates for dark matter. This paper proposes an axion detection scheme based on quantum nondemolition detection of magnon, i.e., quanta of collective spin excitations in solid, which is expected to be excited by the axion-electron interaction predicted by the Dine-Fischer-Srednicki-Zhitnitsky model. The prototype detector is composed of a ferrimagnetic sphere as an electronic spin target and a superconducting qubit. Both of these are embedded inside a microwave cavity, which leads to a coherent effective interaction between the uniform magnetostatic mode in the ferrimagnetic crystal and the qubit. An upper limit for the coupling constant between an axion and an electron is obtained as $g_{aee}<2.6\times {10}^{-6}$ at the 95% confidence level for the axion mass of $33.117\mu \mathrm{eV}<m_a<33.130\mu \mathrm{eV}$.

We show that the Borel representations of $\tau$ hadronic spectral function moments based on contour-improved perturbation theory (CIPT) in general differ from those obtained within fixed-order perturbation theory (FOPT) in the presence of IR renormalons in the underlying Adler function. The Borel sums obtained from both types of Borel representations in general differ as well, and the apparently conflicting behavior of the FOPT and CIPT spectral function moment series at intermediate orders, which has been subject to many studies in the past literature, can be understood quantitatively using concrete Borel function models. The difference between the CIPT and FOPT Borel sums, which we call the “asymptotic separation,” can be computed analytically for any Borel function model and is proportional to inverse exponential terms in the strong coupling. Even though moments can be designed where the asymptotic separation is strongly suppressed, it is as a matter of principle unavoidable. If the Borel function of the Euclidean Adler function has a sizeable gluon condensate renormalon cut, the asymptotic separation can explain the observed disparity of the CIPT and FOPT spectral function moments at the 5-loop level. The existence of the asymptotic separation implies that the power corrections in the operator product expansion for the spectral function moments in the CIPT expansion approach do not have the commonly assumed analytic standard form.

Many scenarios of physics beyond the standard model predict new light, weakly coupled degrees of freedom, populated in the early universe and remaining as cosmic relics today. Due to their high abundances, these relics can significantly affect the evolution of the universe. For instance, massless relics produce a shift $\mathrm{\Delta }{N}_{\mathrm{eff}}$ to the cosmic expectation of the effective number of active neutrinos. Massive relics, on the other hand, additionally become part of the cosmological dark matter in the later universe, though their light nature allows them to freely stream out of potential wells. This produces novel signatures in the large-scale structure (LSS) of the universe, suppressing matter fluctuations at small scales. We present the first general search for such light (but massive) relics (LiMRs) with cosmic microwave background (CMB) and LSS data, scanning the 2D parameter space of their masses $m_X$ and temperatures $T_X^{(0)}$ today. In the conservative minimum-temperature ($T_X^{(0)}=0.91\mathrm{K}$) scenario, we rule out Weyl (and higher-spin) fermions—such as the gravitino—with $m_X\ge 2.3\mathrm{eV}$ at 95% C.L., and set analogous limits of $m_X\le 11$, 1.1, 1.6 eV for scalar, vector, and Dirac-fermion relics. This is the first search for LiMRs with joint CMB, weak-lensing, and full-shape galaxy data; we demonstrate that weak-lensing data is critical for breaking parameter degeneracies, while full-shape information presents a significant boost in constraining power relative to analyses with only baryon acoustic oscillation parameters. Under the combined strength of these datasets, our constraints are the tightest and most comprehensive to date.

We propose a method to substantially improve the signal-to-noise ratio of lattice correlation functions for bosonic operators or other operator combinations with disconnected contributions. The technique is applicable for correlations between operators on two planes (zero momentum correlators) when the dimension of the plane is larger than the separation between the two planes which are correlated. In this case, the correlation arises primarily from points whose in-plane coordinates are close, but noise arises from all pairs of points. By breaking each plane into bins and computing bin-bin correlations, it is possible to capture these short-distance correlators exactly while replacing (small) correlators at large spatial extent with a fit, with smaller uncertainty than the data. The cost is only marginally larger than averaging each plane before correlating, but the improvement in signal-to-noise can be substantial. We test the method on correlators of the gradient-flowed topological charge density and squared field strength, finding noise reductions by a factor of $\sim 3–7$ compared to the conventional approach on the same ensemble of configurations.

Event geometry and initial state correlations have been invoked as possible explanations of long-range azimuthal correlations observed in high-multiplicity $\mathrm{p}+\mathrm{p}$ and $\mathrm{p}+\mathrm{Pb}$ collisions. We study the rapidity dependence of initial state momentum correlations and event-by-event geometry in $\sqrt{s}=5.02\mathrm{TeV}$ $\mathrm{p}+\mathrm{Pb}$ collisions within the $3+1\mathrm{D}$ IP-Glasma model [B. Schenke and S. Schlichting, Phys. Rev. C 94, 044907 (2016)], where the longitudinal structure is governed by Jalilian-Marian-Iancu-McLerran-Weigert-Leonidov-Kovner rapidity evolution of the incoming nuclear gluon distributions. We find that the event geometry is correlated across large rapidity intervals whereas initial state momentum correlations are relatively short-range in rapidity. Based on our results, we discuss implications for the relevance of both effects in explaining the origin of collective phenomena in small systems.

We use a continuum $\mathrm{quark}+\mathrm{diquark}$ approach to the nucleon bound-state problem in relativistic quantum field theory to deliver parameter-free predictions for the nucleon axial and induced pseudoscalar form factors, $G_A$ and $G_P$, and unify them with the pseudoscalar form factor $G_5$ or, equivalently, the pion-nucleon form factor $G_{\pi NN}$. We explain how partial conservation of the axial-vector current and the associated Goldberger-Treiman relation are satisfied once all necessary couplings of the external current to the building blocks of the nucleon are constructed consistently; in particular, we fully resolve the seagull couplings to the diquark-quark vertices associated with the axial-vector and pseudoscalar currents. Among the results we describe, the following are worth highlighting. A dipole form factor defined by an axial charge $g_A=G_A(0)=1.25(3)$ and a mass scale $M_A=1.23(3)m_N$, where $m_N$ is the nucleon mass, can accurately describe the pointwise behavior of $G_A$. Concerning $G_P$, we obtain the pseudoscalar charge $g_p^{*}=8.80(23)$, and find that the pion pole dominance approach delivers a reliable estimate of the directly computed result. Our computed value of the pion-nucleon coupling constant, $g_{\pi NN}/m_N=14.02(33)/\mathrm{GeV}$ is consistent with recent precision determinations.

We study a hypothetical ${\mathrm{\Delta }}^0{\mathrm{\Delta }}^0$ dibaryon state by means of the QCD sum rule method. We construct a scalar interpolating current to extract the mass and decay constant of this state taking into account contributions of various quark, gluon, and mixed vacuum condensates. The predictions for the mass and decay constants are $m_D=2326_{-126}^{+114}\mathrm{MeV}$ and $f_D=2.94_{-0.34}^{+0.30}\times {10}^{-4}{\mathrm{GeV}}^7$, respectively. We also made an estimation about binding energy and size of the ${\mathrm{\Delta }}^0{\mathrm{\Delta }}^0$ dibaryon. The obtained mass value is below the ${\mathrm{\Delta }}^0{\mathrm{\Delta }}^0$ threshold and may be a good dibaryon candidate for being observed experimentally.

We determine the chiral phase structure of ($2+1$)-flavor QCD in dependence of temperature and the light flavor quark mass with Dyson-Schwinger equations. Specifically, we compute the renormalized chiral condensate and its susceptibility. The latter is used to determine the (pseudo)critical temperature for general light current quark masses. In the chiral limit we obtain a critical temperature of about 141 MeV. This result is in quantitative agreement with recent functional renormalization group results in QCD and is compatible with the respective lattice results. We also compute the order parameter potential of the light chiral condensate, map out the regime in the phase diagram which exhibits quasi-massless modes, and discuss the respective chiral dynamics.

We report the first measurements of the absolute branching fractions of $D^0\to K_L^0\varphi$, $D^0\to K_L^0\eta$, $D^0\to K_L^0\omega$, and $D^0\to K_L^0{\eta }^{\prime }$, by analyzing $2.93{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data taken at a center-of-mass energy of 3.773 GeV with the BESIII detector. Taking the world averages of the branching fractions of $D^0\to K_S^0\varphi$, $D^0\to K_S^0\eta$, $D^0\to K_S^0\omega$, and $D^0\to K_S^0{\eta }^{\prime }$, the $K_S^0-K_L^0$ asymmetries $\mathcal{R}(D^0,X)$ in these decay modes are obtained. The $CP$ asymmetries in these decays are also determined. No significant $CP$ violation is observed.

In this paper we address the potential of a 3 TeV center-of-mass energy Compact Linear Collider (CLIC) to measure the branching fraction of the Higgs boson decay to two photons, $\mathrm{BR}(H\to \gamma \gamma )$. Since photons are massless, the Higgs boson coupling to photons is realized through higher order processes involving heavy particles either from the Standard Model or beyond. Any deviation of the measured $\mathrm{BR}(H\to \gamma \gamma )$, and consequently of the Higgs coupling $g_{H\gamma \gamma }$ from the predictions of the Standard Model, may indicate new physics. The Higgs decay to two photons is thus an interesting probe of the Higgs sector. This study is performed using the simulation of the detector for CLIC and by considering all relevant physics and beam-induced processes in a full reconstruction chain. It is shown that the product of the Higgs production cross section in $W^{+}{W}^{-}$ fusion and $\mathrm{BR}(H\to \gamma \gamma )$ can be measured with a relative statistical uncertainty of 5.5%, assuming the integrated luminosity of $5{\mathrm{ab}}^{-1}$ and unpolarized beams.

A search for invisible decays of the Higgs boson produced via vector boson fusion (VBF) has been performed with $101{\mathrm{fb}}^{-1}$ of proton-proton collisions delivered by the LHC at $\sqrt{s}=13\mathrm{TeV}$ and collected by the CMS detector in 2017 and 2018. The sensitivity to the VBF production mechanism is enhanced by constructing two analysis categories, one based on missing transverse momentum and a second based on the properties of jets. In addition to control regions with Z and W boson candidate events, a highly populated control region, based on the production of a photon in association with jets, is used to constrain the dominant irreducible background from the invisible decay of a Z boson produced in association with jets. The results of this search are combined with all previous measurements in the VBF topology, based on data collected in 2012 (at $\sqrt{s}=8\mathrm{TeV}$), 2015, and 2016, corresponding to integrated luminosities of 19.7, 2.3, and $36.3{\mathrm{fb}}^{-1}$, respectively. The observed (expected) upper limit on the invisible branching fraction of the Higgs boson is found to be 0.18 (0.10) at the 95% confidence level, assuming the standard model production cross section. The results are also interpreted in the context of Higgs-portal models.

We revisit the roller-coaster cosmology based on multiple stages of monodromy inflation. Working within the framework of effective flux monodromy field theory, we include the full range of strong coupling corrections to the inflaton sector. We find that flattened potentials $V\sim {\varphi }^p+\cdots$ with $p\lesssim 1/2$, limited to $N\lesssim 25-40$ $e$-folds in the first stage of inflation, continue to fit the cosmic microwave background. They yield $0.96\lesssim n_s\lesssim 0.97$ and produce relic gravity waves with $0.006\lesssim r\lesssim 0.035$, in full agreement with the most recent bounds from BICEP/Keck. The nonlinear derivative corrections generated by strong dynamics in effective field theory (EFT) also lead to equilateral non-Gaussianity $f_{\mathrm{NL}}^{\mathrm{eq}}\simeq \mathcal{O}(1)-\mathcal{O}(10)$, close to the current observational bounds. Finally, in the multistage roller coaster, an inflaton–hidden sector $U(1)$ coupling can produce a tachyonic chiral vector background, which converts rapidly into tensors during the short interruption by matter domination. The produced stochastic gravity waves are chiral, and so they may be clearly identifiable by gravity wave instruments like LISA, Big Bang Observer, Einstein Telescope, NANOgrav, or SKA, depending on the precise model realization. We also point out that the current attempts to resolve the $H_0$ tension using early dark energy generically raise $n_s$. This might significantly alter the impact of BICEP/Keck data on models of inflation.

Recently, active galactic nuclei (AGN) have been proposed as “standardizable candles,” thanks to an observed nonlinear relation between their x-ray and optical-ultraviolet (UV) luminosities, which provides an independent measurement of their distances. In this paper, we use these observables for the first time to estimate the parameters of $f(R)$ gravity models (specifically, the Hu-Sawicki and the exponential models) together with the cosmological parameters. The importance of these types of modified gravity theories lies in the fact that they can explain the late time accelerated expansion of the universe without the inclusion of a dark energy component. We have also included other observable data to the analyses such as estimates of the Hubble parameter $H(z)$ from cosmic chronometers (CCs), the Pantheon Type Ia (SnIa) supernovae compilation, and baryon acoustic oscillation (BAO) measurements. The $1\sigma$ inferred constraints using all datasets are $b\le 0.276$, ${\mathrm{\Omega }}_m=0.304_{-0.011}^{+0.010}$, and $H_0=67.553_{-0.936}^{+1.242}$ for the Hu-Sawicki model, and $b=0.785_{-0.606}^{+0.409}$ ${\mathrm{\Omega }}_m=0.305_{-0.010}^{+0.011}$ and $H_0=68.348_{-0.760}^{+0.959}$ for the exponential one, but we stress that for both $f(R)$ models results within $2\sigma$ are consistent with the $\mathrm{\Lambda }$ cold dark matter (CDM) model. Our results show that the allowed space parameter is restricted when both AGN and BAO data are added to CC and SnIa data, with the BAO dataset being the most restrictive one. We can conclude that both the $\mathrm{\Lambda }\mathrm{CDM}$ model and small deviations from general relativity given by the $f(R)$ models studied in this paper are allowed by the considered observational datasets.

Gravitational-wave (GW) data contains non-Gaussian noise transients called “glitches.” During the third LIGO-Virgo observing run about 24% of all gravitational-wave candidates were in the vicinity of a glitch, while even more events could be affected in future observing runs due to increasing detector sensitivity. This poses a problem since glitches can affect the estimation of GW source parameters, including sky localization, which is crucial to identify an electromagnetic counterpart. This is the first of its kind study that evaluates the importance of relative glitch positioning in time with respect to a GW signal. In this paper we estimate how much sky localization is affected by a nearby glitch in low latency. We injected binary black hole (BBH), binary neutron star (BNS), and neutron star-black hole (NSBH) signals into data containing three different classes of glitches: blips, thunderstorms and fast scatterings. The impact of these glitches was assessed by estimating the number of tile pointings that a telescope would need to search over until the true sky location of an event is observed. We find that blip glitches generally do not affect the localization of our tested GW signals, however in very rare cases of a blip glitch overlap with a BBH or a NSBH signal can cause the true position of the event to lie well outside the 90% computed sky localization, severely compromising electromagnetic follow-up. Thunderstorm glitches have a noticeable impact on BBH and NSBH events, especially if there is no third interferometer. In such cases we find that the electromagnetic follow-up efforts with telescopes as large as $20{\mathrm{deg}}^2$ field of view (FOV) are affected. Observing BBH and NBSH signals with three-detector network reduces the bias in sky localization caused by thunderstorm glitches, making the bias to affect only small ($\mathrm{FOV}=1{\mathrm{deg}}^2$) telescopes. BNS events appear to be not affected by thunderstorm glitches. Fast scattering glitches have no impact on the low latency localization of BBH and BNS signals. For NSBH signals observed with two-detector network, the sky localization bias due to fast scattering glitches is significant enough to affect even large ($\mathrm{FOV}=20{\mathrm{deg}}^2$) telescopes. Observing NSBH signals with three interferometers reduces the bias such that it impacts only small ($\mathrm{FOV}=1{\mathrm{deg}}^2$) telescopes.

Dark matter particles may bind with nuclei if there exists an attractive force of sufficient strength. We show that a dark photon mediator of mass $\sim (10–100)\mathrm{MeV}$ that kinetically mixes with Standard Model electromagnetism at the level of $\sim {10}^{-3}$ generates keV-scale binding energies between dark matter and heavy elements, while forbidding the ability to bind with light elements. In underground direct detection experiments, the formation of such bound states liberates keV-scale energy in the form of electrons and photons, giving rise to monoenergetic electronic signals with a time structure that may contain daily and seasonal modulations. We show that data from liquid-xenon detectors provides exquisite sensitivity to this scenario, constraining the galactic abundance of such dark particles to be at most $\sim {10}^{-18}–{10}^{-12}$ of the galactic dark-matter density for masses spanning $\sim (1–{10}^5)\mathrm{GeV}$. However, an exponentially small fractional abundance of these dark particles is enough to explain the observed electron recoil excess at XENON1T.

We present a perturbative calculation of the energy profile width of rigid strings up to two loops in $D$ dimensions. The perturbative expansion of the extrinsic curvature term, signifying the rigidity/smoothness of the string in Polyakov-Kleinert action, is taken around the free Nambu-Goto string. The mean-square width of the string field is derived for open strings with the Dirichlet boundary condition. We compare the broadening of the smooth Polyakov-Kleinert string to the lattice Monte Carlo data of the QCD flux tube just before the deconfinement point and find a good match at the intermediate and large color source separation.

The new charmed resonance $D_2^{*}(3000)$ was observed by the LHCb Collaboration in $B$ decays. In this paper, by assigning it as four possible excited states of the $2^{+}$ family, we use the instantaneous Bethe-Salpeter method to calculate their Okubo-Zweig-Iizuka-allowed two-body strong decays. The results of $1^3{F}_2$ and $3^3{P}_2$ states deviate from the present experimental observation while $2^3{P}_2$ and $2^3{F}_2$ are in the error range. Our study also reveals that the widths of these states depend strongly on the masses. Due to the large uncertainties and different mass input, variable models get inconsistent conclusions at the moment. The analysis in this work can provide essential assistance for future measurements and investigations.