Showing papers in "Physical Review D in 2018"

APS : Review of Particle Physics, 2018-2019

Abstract: The complete Review(both volumes) is published online on the website of the Particle Data Group(http://pdg.lbl.gov) and in a journal. Volume 1 is available in print as thePDG Book. AParticle Physics Bookletwith the Summary Tables and essential tables, figures, and equations from selected review articles is also available.

Dark Energy Survey year 1 results: Cosmological constraints from galaxy clustering and weak lensing

Abstract: We present cosmological results from a combined analysis of galaxy clustering and weak gravitational lensing, using 1321 deg2 of griz imaging data from the first year of the Dark Energy Survey (DES Y1). We combine three two-point functions: (i) the cosmic shear correlation function of 26 million source galaxies in four redshift bins, (ii) the galaxy angular autocorrelation function of 650,000 luminous red galaxies in five redshift bins, and (iii) the galaxy-shear cross-correlation of luminous red galaxy positions and source galaxy shears. To demonstrate the robustness of these results, we use independent pairs of galaxy shape, photometric-redshift estimation and validation, and likelihood analysis pipelines. To prevent confirmation bias, the bulk of the analysis was carried out while "blind" to the true results; we describe an extensive suite of systematics checks performed and passed during this blinded phase. The data are modeled in flat ΛCDM and wCDM cosmologies, marginalizing over 20 nuisance parameters, varying 6 (for ΛCDM) or 7 (for wCDM) cosmological parameters including the neutrino mass density and including the 457×457 element analytic covariance matrix. We find consistent cosmological results from these three two-point functions and from their combination obtain S8≡σ8(Ωm/0.3)0.5=0.773-0.020+0.026 and Ωm=0.267-0.017+0.030 for ΛCDM; for wCDM, we find S8=0.782-0.024+0.036, Ωm=0.284-0.030+0.033, and w=-0.82-0.20+0.21 at 68% C.L. The precision of these DES Y1 constraints rivals that from the Planck cosmic microwave background measurements, allowing a comparison of structure in the very early and late Universe on equal terms. Although the DES Y1 best-fit values for S8 and Ωm are lower than the central values from Planck for both ΛCDM and wCDM, the Bayes factor indicates that the DES Y1 and Planck data sets are consistent with each other in the context of ΛCDM. Combining DES Y1 with Planck, baryonic acoustic oscillation measurements from SDSS, 6dF, and BOSS and type Ia supernovae from the Joint Lightcurve Analysis data set, we derive very tight constraints on cosmological parameters: S8=0.802±0.012 and Ωm=0.298±0.007 in ΛCDM and w=-1.00-0.04+0.05 in wCDM. Upcoming Dark Energy Survey analyses will provide more stringent tests of the ΛCDM model and extensions such as a time-varying equation of state of dark energy or modified gravity.

Dark Energy Survey Year 1 results: cosmological constraints from cosmic shear

Abstract: We use 26×106 galaxies from the Dark Energy Survey (DES) Year 1 shape catalogs over 1321 deg2 of the sky to produce the most significant measurement of cosmic shear in a galaxy survey to date. We constrain cosmological parameters in both the flat ΛCDM and the wCDM models, while also varying the neutrino mass density. These results are shown to be robust using two independent shape catalogs, two independent photo-z calibration methods, and two independent analysis pipelines in a blind analysis. We find a 3.5% fractional uncertainty on σ8(Ωm/0.3)0.5=0.782-0.027+0.027 at 68% C.L., which is a factor of 2.5 improvement over the fractional constraining power of our DES Science Verification results. In wCDM, we find a 4.8% fractional uncertainty on σ8(Ωm/0.3)0.5=0.777-0.038+0.036 and a dark energy equation-of-state w=-0.95-0.39+0.33. We find results that are consistent with previous cosmic shear constraints in σ8—Ωm, and we see no evidence for disagreement of our weak lensing data with data from the cosmic microwave background. Finally, we find no evidence preferring a wCDM model allowing w≠-1. We expect further significant improvements with subsequent years of DES data, which will more than triple the sky coverage of our shape catalogs and double the effective integrated exposure time per galaxy.

Muon g − 2 and α ( M Z 2 ) : A new data-based analysis

Abstract: This work presents a complete reevaluation of the hadronic vacuum polarization contributions to the anomalous magnetic moment of the muon, aμhad,VP, and the hadronic contributions to the effective QED coupling at the mass of the Z boson, Δαhad(MZ2), from the combination of e+e-→hadrons cross section data. Focus has been placed on the development of a new data combination method, which fully incorporates all correlated statistical and systematic uncertainties in a bias free approach. All available e+e-→hadrons cross section data have been analyzed and included, where the new data compilation has yielded the full hadronic R-ratio and its covariance matrix in the energy range mπ≤s≤11.2 GeV. Using these combined data and perturbative QCD above that range results in estimates of the hadronic vacuum polarization contributions to g-2 of the muon of aμhad,LO VP=(693.26±2.46)×10-10 and aμhad,NLO VP=(-9.82±0.04)×10-10. The new estimate for the Standard Model prediction is found to be aμSM=(11659182.04±3.56)×10-10, which is 3.7σ below the current experimental measurement. The prediction for the five-flavor hadronic contribution to the QED coupling at the Z boson mass is Δαhad(5)(MZ2)=(276.11±1.11)×10-4, resulting in α-1(MZ2)=128.946±0.015. Detailed comparisons with results from similar related works are given.

GW170817, general relativistic magnetohydrodynamic simulations, and the neutron star maximum mass.

Abstract: Recent numerical simulations in general relativistic magnetohydrodynamics (GRMHD) provide useful constraints for the interpretation of the GW170817 discovery. Combining the observed data with these simulations leads to a bound on the maximum mass of a cold, spherical neutron star (the TOV limit): ${M}_{\mathrm{max}}^{\mathrm{sph}}\ensuremath{\lesssim}2.74/\ensuremath{\beta}$, where $\ensuremath{\beta}$ is the ratio of the maximum mass of a uniformly rotating neutron star (the supramassive limit) over the maximum mass of a nonrotating star. Causality arguments allow $\ensuremath{\beta}$ to be as high as 1.27, while most realistic candidate equations of state predict $\ensuremath{\beta}$ to be closer to 1.2, yielding ${M}_{\mathrm{max}}^{\mathrm{sph}}$ in the range $2.16--2.28{M}_{\ensuremath{\bigodot}}$. A minimal set of assumptions based on these simulations distinguishes this analysis from previous ones, but leads a to similar estimate. There are caveats, however, and they are enumerated and discussed. The caveats can be removed by further simulations and analysis to firm up the basic argument.

Coincident General Relativity

Abstract: The metric-affine variational principle is applied to generate teleparallel and symmetric teleparallel theories of gravity. From the latter we discover an exceptional class which is consistent with ...

ForwArd Search ExpeRiment at the LHC

Abstract: New physics has traditionally been expected in the high-pT region at high-energy collider experiments. If new particles are light and weakly coupled, however, this focus may be completely misguided: light particles are typically highly concentrated within a few mrad of the beam line, allowing sensitive searches with small detectors, and even extremely weakly coupled particles may be produced in large numbers there. We propose a new experiment, forward search experiment, or FASER, which would be placed downstream of the ATLAS or CMS interaction point (IP) in the very forward region and operated concurrently there. Two representative on-axis locations are studied: a far location, 400 m from the IP and just off the beam tunnel, and a near location, just 150 m from the IP and right behind the TAN neutral particle absorber. For each location, we examine leading neutrino- and beam-induced backgrounds. As a concrete example of light, weakly coupled particles, we consider dark photons produced through light meson decay and proton bremsstrahlung. We find that even a relatively small and inexpensive cylindrical detector, with a radius of ∼10 cm and length of 5–10 m, depending on the location, can discover dark photons in a large and unprobed region of parameter space with dark photon mass mA′∼10–500 MeV and kinetic mixing parameter e∼10-6-10-3. FASER will clearly also be sensitive to many other forms of new physics. We conclude with a discussion of topics for further study that will be essential for understanding FASER’s feasibility, optimizing its design, and realizing its discovery potential.

Semianalytic calculation of gravitational wave spectrum nonlinearly induced from primordial curvature perturbations

Abstract: Whether or not the primordial gravitational wave (GW) produced during inflation is sufficiently strong to be observable, GWs are necessarily produced from the primordial curvature perturbations in the second order of perturbation. The induced GWs can be enhanced by curvature perturbations enhanced at small scales or by the presence of matter-dominated stages of the cosmological history. We analytically calculate the integral in the expression of the power spectrum of the induced GWs, which is a universal part independent of the spectrum of the primordial curvature perturbations. This makes the subsequent numerical integrals significantly easy. In simple cases, we derive fully analytic formulas for the induced GW spectrum.

Test of lepton flavor universality by the measurement of the B0 →d∗-τ+ντ branching fraction using three-prong τ decays

Abstract: The ratio of branching fractions R(D∗-)≡B(B0→D∗-τ+ντ)/B(B0→D∗-μ+νμ) is measured using a data sample of proton-proton collisions collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb-1. The τ lepton is reconstructed with three charged pions in the final state. A novel method is used that exploits the different vertex topologies of signal and backgrounds to isolate samples of semitauonic decays of b hadrons with high purity. Using the B0→D∗-π+π-π+ decay as the normalization channel, the ratio B(B0→D∗-τ+ντ)/B(B0→D∗-π+π-π+) is measured to be 1.97±0.13±0.18, where the first uncertainty is statistical and the second systematic. An average of branching fraction measurements for the normalization channel is used to derive B(B0→D∗-τ+ντ)=(1.42±0.094±0.129±0.054)%, where the third uncertainty is due to the limited knowledge of B(B0→D∗-π+π-π+). A test of lepton flavor universality is performed using the well-measured branching fraction B(B0→D∗-μ+νμ) to compute R(D∗-)=0.291±0.019±0.026±0.013, where the third uncertainty originates from the uncertainties on B(B0→D∗-π+π-π+) and B(B0→D∗-μ+νμ). This measurement is in agreement with the Standard Model prediction and with previous measurements.

Searching for long-lived particles: A compact detector for exotics at LHCb

Abstract: Author(s): Gligorov, VV; Knapen, S; Papucci, M; Robinson, DJ | Abstract: We advocate for the construction of a new detector element at the LHCb experiment, designed to search for displaced decays of beyond Standard Model long-lived particles, taking advantage of a large shielded space in the LHCb cavern that is expected to soon become available. We discuss the general features and putative capabilities of such an experiment, as well as its various advantages and complementarities with respect to the existing LHC experiments and proposals such as SHiP and MATHUSLA. For two well-motivated beyond Standard Model benchmark scenarios - Higgs decay to dark photons and B meson decays via a Higgs mixing portal - the reach either complements or exceeds that predicted for other LHC experiments.

Second law of quantum complexity

Abstract: We give arguments for the existence of a thermodynamics of quantum complexity that includes a ``second law of complexity.'' To guide us, we derive a correspondence between the computational (circuit) complexity of a quantum system of $K$ qubits, and the positional entropy of a related classical system with ${2}^{K}$ degrees of freedom. We also argue that the kinetic entropy of the classical system is equivalent to the Kolmogorov complexity of the quantum Hamiltonian. We observe that the expected pattern of growth of the complexity of the quantum system parallels the growth of entropy of the classical system. We argue that the property of having less-than-maximal complexity (uncomplexity) is a resource that can be expended to perform directed quantum computation. Although this paper is not primarily about black holes, we find a surprising interpretation of the uncomplexity resource as the accessible volume of spacetime behind a black hole horizon.

Primordial black hole dark matter from single field inflation

Abstract: We propose a model of inflation capable of generating a population of light black holes (about 10-16–10-14 solar masses) that might account for a significant fraction of the dark matter in the Universe. The effective potential of the model features an approximate inflection point arising from two-loop order logarithmic corrections in well-motivated and perturbative particle physics examples. This feature decelerates the inflaton before the end of inflation, enhancing the primordial spectrum of scalar fluctuations and triggering efficient black hole production with a peaked mass distribution. At larger field values, inflation occurs thanks to a generic small coupling between the inflaton and the curvature of spacetime. We compute accurately the peak mass and abundance of the primordial black holes using the Press-Schechter and Mukhanov-Sasaki formalisms, showing that the slow-roll approximation fails to reproduce the correct results by orders of magnitude. We study as well a qualitatively similar implementation of the idea, where the approximate inflection point is due to competing terms in a generic polynomial potential. In both models, requiring a significant part of the dark matter abundance to be in the form of black holes implies a small blue scalar tilt with a sizable negative running and a tensor spectrum that may be detected by the next-generation probes of the cosmic microwave background. We also comment on previous works on the topic.

High-energy gravitational scattering and the general relativistic two-body problem

Abstract: A technique for translating the classical scattering function of two gravitationally interacting bodies into a corresponding (effective one-body) Hamiltonian description has been recently introduced [Phys. Rev. D 94, 104015 (2016)]. Using this technique, we derive, for the first time, to second-order in Newton's constant (i.e. one classical loop) the Hamiltonian of two point masses having an arbitrary (possibly relativistic) relative velocity. The resulting (second post-Minkowskian) Hamiltonian is found to have a tame high-energy structure which we relate both to gravitational self-force studies of large mass-ratio binary systems, and to the ultra high-energy quantum scattering results of Amati, Ciafaloni and Veneziano. We derive several consequences of our second post-Minkowskian Hamiltonian: (i) the need to use special phase-space gauges to get a tame high-energy limit; and (ii) predictions about a (rest-mass independent) linear Regge trajectory behavior of high-angular-momenta, high-energy circular orbits. Ways of testing these predictions by dedicated numerical simulations are indicated. We finally indicate a way to connect our classical results to the quantum gravitational scattering amplitude of two particles, and we urge amplitude experts to use their novel techniques to compute the two-loop scattering amplitude of scalar masses, from which one could deduce the third post-Minkowskian effective one-body Hamiltonian.

CaloGAN: Simulating 3D high energy particle showers in multilayer electromagnetic calorimeters with generative adversarial networks

Abstract: The precise modeling of subatomic particle interactions and propagation through matter is paramount for the advancement of nuclear and particle physics searches and precision measurements. The most computationally expensive step in the simulation pipeline of a typical experiment at the Large Hadron Collider (LHC) is the detailed modeling of the full complexity of physics processes that govern the motion and evolution of particle showers inside calorimeters. We introduce CaloGAN, a new fast simulation technique based on generative adversarial networks (GANs). We apply these neural networks to the modeling of electromagnetic showers in a longitudinally segmented calorimeter and achieve speedup factors comparable to or better than existing full simulation techniques on CPU ($100\ifmmode\times\else\texttimes\fi{}--1000\ifmmode\times\else\texttimes\fi{}$) and even faster on GPU (up to $\ensuremath{\sim}{10}^{5}\ifmmode\times\else\texttimes\fi{}$). There are still challenges for achieving precision across the entire phase space, but our solution can reproduce a variety of geometric shower shape properties of photons, positrons, and charged pions. This represents a significant stepping stone toward a full neural network-based detector simulation that could save significant computing time and enable many analyses now and in the future.

Circuit complexity in fermionic field theory

Abstract: We define and calculate versions of complexity for free fermionic quantum field theories in 1 + 1 and 3 + 1 dimensions, adopting Nielsen's geodesic perspective in the space of circuits. We do this both by discretizing and identifying appropriate classes of Bogoliubov-Valatin transformations, and also directly in the continuum by defining squeezing operators and their generalizations. As a closely related problem, we consider cMERA tensor networks for fermions: viewing them as paths in circuit space, we compute their path lengths. Certain ambiguities that arise in some of these results because of cutoff dependence are discussed.

Combined explanations of (g -2 )μ ,e and implications for a large muon EDM

Abstract: With the long-standing tension between experiment and standard-model (SM) prediction in the anomalous magnetic moment of the muon, ${a}_{\ensuremath{\mu}}=(g\ensuremath{-}2{)}_{\ensuremath{\mu}}/2$, at the level of $3--4\ensuremath{\sigma}$, it is natural to ask if there could be a sizable effect in the electric dipole moment (EDM) ${d}_{\ensuremath{\mu}}$ as well. In this context it has often been argued that in UV complete models the electron EDM, which is very precisely measured, excludes a large effect in ${d}_{\ensuremath{\mu}}$. However, the recently observed $2.5\ensuremath{\sigma}$ tension in ${a}_{e}=(g\ensuremath{-}2{)}_{e}/2$, if confirmed, requires that the muon and electron sectors effectively decouple to avoid constraints from $\ensuremath{\mu}\ensuremath{\rightarrow}e\ensuremath{\gamma}$. We briefly discuss UV complete models that possess such a decoupling, which can be enforced by an Abelian flavor symmetry ${L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}$. We show that, in such scenarios, there is no reason to expect a correlation between the electron and muon EDM, so that the latter can be sizable. New limits on ${d}_{\ensuremath{\mu}}$ improved by up to two orders of magnitude are expected from the upcoming $(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$ experiments at Fermilab and J-PARC. Beyond, a proposed dedicated muon EDM experiment at PSI could further advance the limit. In this way, future improved measurements of ${a}_{e}$, ${a}_{\ensuremath{\mu}}$, as well as the fine-structure constant $\ensuremath{\alpha}$ are not only set to provide exciting precision tests of the SM, but, in combination with EDMs, to reveal crucial insights into the flavor structure of physics beyond the SM.

Results from phase 1 of the HAYSTAC microwave cavity axion experiment

Abstract: We report on the results from a search for dark matter axions with the HAYSTAC experiment using a microwave cavity detector at frequencies between 5.6 and 5.8 GHz. We exclude axion models with two photon coupling ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}\ensuremath{\gtrsim}2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$, a factor of 2.7 above the benchmark KSVZ model over the mass range $23.15l{m}_{a}l24.0\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$. This doubles the range reported in our previous paper. We achieve a near-quantum-limited sensitivity by operating at a temperature $Tlh\ensuremath{ u}/2{k}_{B}$ and incorporating a Josephson parametric amplifier (JPA), with improvements in the cooling of the cavity further reducing the experiment's system noise temperature to only twice the standard quantum limit at its operational frequency, an order of magnitude better than any other dark matter microwave cavity experiment to date. This result concludes the first phase of the HAYSTAC program utilizing a conventional copper cavity and a single JPA.

Model of vector leptoquarks in view of the B -physics anomalies

Abstract: Lepton number as a fourth color is an intriguing theoretical idea which is combined with a possible left-right symmetry within the famous Pati-Salam (PS) model. In the conventional PS model, a spontaneous breaking of the PS gauge group down to the SM, one can only take place at very high scales (above the PeV scale) due to the stringent bounds from ${K}_{L}\ensuremath{\rightarrow}\ensuremath{\mu}e$ and $K\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\mu}e$ induced by the resulting vector leptoquarks. In this paper, we show that these constraints can be avoided once additional vectorlike fermions are introduced and, thus, a breaking at the TeV scale is possible. We consider the flavor phenomenology of this model in the context of the intriguing hints for new physics in semileptonic $B$ decays. The necessary violation of lepton flavor universality is induced by mixing SM and vectorlike fermions. Concerning $R(D)$ and $R({D}^{*})$, we find that sizable effects are possible while respecting the bounds from other flavor observables but predicting a large enhancement of ${B}_{s}\ensuremath{\rightarrow}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$. Furthermore, also in $b\ensuremath{\rightarrow}s{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ transitions, the observed deviations from the SM predictions [including $R(K)$ and $R({K}^{*})$] can be explained with natural values for the free parameters of the model without any fine-tuning, predicting sizable decay rates for $b\ensuremath{\rightarrow}s\ensuremath{\tau}\ensuremath{\mu}$. Finally, the anomaly in the anomalous magnetic moment of the muon can be accounted for by a loop contribution involving the vector leptoquark and vectorlike leptons.

Scalar-tensor theories and modified gravity in the wake of GW170817

Abstract: Theories of dark energy and modified gravity can be strongly constrained by astrophysical or cosmological observations, as illustrated by the recent observation of the gravitational wave event GW170817 and of its electromagnetic counterpart GRB 170817A, which showed that the speed of gravitational waves, ${c}_{g}$, is the same as the speed of light, within deviations of order ${10}^{\ensuremath{-}15}$. This observation implies severe restrictions on scalar-tensor theories, in particular theories whose action depends on second derivatives of a scalar field. Working in the very general framework of degenerate higher-order scalar-tensor (DHOST) theories, which encompass Horndeski and beyond Horndeski theories, we present the DHOST theories that satisfy ${c}_{g}=c$. We then examine, for these theories, the screening mechanism that suppresses scalar interactions on small scales, namely the Vainshtein mechanism, and compute the corresponding gravitational laws for a nonrelativistic spherical body. We show that it can lead to a deviation from standard gravity inside matter, parametrized by three coefficients which satisfy a consistency relation and can be constrained by present and future astrophysical observations.

Implications from GW170817 and I-Love-Q relations for relativistic hybrid stars

Abstract: Gravitational wave observations of GW170817 placed bounds on the tidal deformabilities of compact stars, allowing one to probe equations of state for matter at supranuclear densities. Here we design new parametrizations for hybrid hadron-quark equations of state, which give rise to low-mass twin stars, and test them against GW170817. We find that GW170817 is consistent with the coalescence of a binary hybrid star-neutron star. We also test and find that the I-Love-Q relations for hybrid stars in the third family agree with those for purely hadronic and quark stars within $\ensuremath{\sim}3%$ for both slowly and rapidly rotating configurations, implying that these relations can be used to perform equation-of-state independent tests of general relativity and to break degeneracies in gravitational waveforms for hybrid stars in the third family as well.

Measurements of Higgs boson properties in the diphoton decay channel with 36 fb−1 of pp collision data at s√=13 TeV with the ATLAS detector

Abstract: Properties of the Higgs boson are measured in the two-photon final state using 36.1 fb-1 of proton? proton collision data recorded at ffiffi √s = 13 TeV by the ATLAS experiment at the Large Hadron Collider. Cross-section measurements for the production of a Higgs boson through gluon-gluon fusion, vectorboson fusion, and in association with a vector boson or a top-quark pair are reported. The signal strength, defined as the ratio of the observed to the expected signal yield, is measured for each of these production processes as well as inclusively. The global signal strength measurement of 0.99 ± 0.14 improves on the precision of the ATLAS measurement at √s = 7 and 8 TeV by a factor of two. Measurements of gluon-gluon fusion and vector-boson fusion productions yield signal strengths compatible with the Standard Model prediction. Measurements of simplified template cross sections, designed to quantify the different Higgs boson production processes in specific regions of phase space, are reported. The cross section for the production of the Higgs boson decaying to two isolated photons in a fiducial region closely matching the experimental selection of the photons is measured to be 55 ± 10 fb, which is in good agreement with the Standard Model prediction of 64 ± 2 fb. Furthermore, cross sections in fiducial regions enriched in Higgs boson production in vector-boson fusion or in association with large missing transverse momentum, leptons or top-quark pairs are reported. Differential and double-differential measurements are performed for several variables related to the diphoton kinematics as well as the kinematics and multiplicity of the jets produced in association with a Higgs boson. These differential cross sections are sensitive to higher order QCD corrections and properties of the Higgs boson, such as its spin and CP quantum numbers. No significant deviations from a wide array of Standard Model predictions are observed. Finally, the strength and tensor structure of the Higgs boson interactions are investigated using an effective Lagrangian, which introduces additional CP-even and CP-odd interactions. No significant new physics contributions are observed.

Scalar leptoquarks from grand unified theories to accommodate the B -physics anomalies

Abstract: We address the $B$-physics anomalies within a two scalar leptoquark model. The low-energy flavor structure of our setup originates from two $SU(5)$ operators that relate Yukawa couplings of the two leptoquarks. The proposed scenario has a UV completion, can accommodate all measured lepton flavor universality ratios in $B$-meson decays, is consistent with related flavor observables, and is compatible with direct searches at the LHC. We provide prospects for future discoveries of the two light leptoquarks at the LHC and predict several yet-to-be-measured flavor observables.

Revisiting big-bang nucleosynthesis constraints on long-lived decaying particles

Abstract: The authors provide a state of the art analysis of the effects of long-lived non-Standard Model massive particles, decaying during big-bang nucleosynthesis (BBN), on the primordial abundances of light elements. Besides updated standard BBN reaction rates, additional processes and new numerical algorithms are implemented to discuss also solutions to the Lithium problem and the possible gravitino mass for leptogenesis to work.

Eccentric Black Hole Mergers Forming in Globular Clusters

Abstract: We derive the probability for a newly formed binary black hole (BBH) to undergo an eccentric gravitational wave (GW) merger during binary-single interactions inside a stellar cluster. By integrating over the hardening interactions such a BBH must undergo before ejection, we find that the observable rate of BBH mergers with eccentricity $g0.1$ at 10 Hz relative to the rate of circular mergers can be as high as $\ensuremath{\sim}5%$ for a typical globular cluster (GC). This further suggests that BBH mergers forming through GW captures in binary-single interactions, eccentric or not, are likely to constitute $\ensuremath{\sim}10%$ of the total BBH merger rate from GCs. Such GW capture mergers can only be probed with an $N$-body code that includes general relativistic corrections, which explains why recent Newtonian cluster studies have not been able to resolve this population. Finally, we show that the relative rate of eccentric BBH mergers depends on the compactness of their host cluster, suggesting that an observed eccentricity distribution can be used to probe the origin of BBH mergers.

Deep Neural Networks to Enable Real-time Multimessenger Astrophysics

Abstract: Gravitational wave astronomy has set in motion a scientific revolution. To further enhance the science reach of this emergent field of research, there is a pressing need to increase the depth and speed of the algorithms used to enable these ground-breaking discoveries. We introduce Deep Filtering---a new scalable machine learning method for end-to-end time-series signal processing. Deep Filtering is based on deep learning with two deep convolutional neural networks, which are designed for classification and regression, to detect gravitational wave signals in highly noisy time-series data streams and also estimate the parameters of their sources in real time. Acknowledging that some of the most sensitive algorithms for the detection of gravitational waves are based on implementations of matched filtering, and that a matched filter is the optimal linear filter in Gaussian noise, the application of Deep Filtering using whitened signals in Gaussian noise is investigated in this foundational article. The results indicate that Deep Filtering outperforms conventional machine learning techniques, achieves similar performance compared to matched filtering, while being several orders of magnitude faster, allowing real-time signal processing with minimal resources. Furthermore, we demonstrate that Deep Filtering can detect and characterize waveform signals emitted from new classes of eccentric or spin-precessing binary black holes, even when trained with data sets of only quasicircular binary black hole waveforms. The results presented in this article, and the recent use of deep neural networks for the identification of optical transients in telescope data, suggests that deep learning can facilitate real-time searches of gravitational wave sources and their electromagnetic and astroparticle counterparts. In the subsequent article, the framework introduced herein is directly applied to identify and characterize gravitational wave events in real LIGO data.

DarkSide-50 532-day dark matter search with low-radioactivity argon

Abstract: The DarkSide-50 direct-detection dark matter experiment is a dual-phase argon time projection chamber operating at Laboratori Nazionali del Gran Sasso. This paper reports on the blind analysis of a (16 660±270) kg d exposure using a target of low-radioactivity argon extracted from underground sources. We find no events in the dark matter selection box and set a 90% C.L. upper limit on the dark matter–nucleon spin-independent cross section of 1.14×10-44 cm2 (3.78×10-44 cm2, 3.43×10-43 cm2) for a WIMP mass of 100 GeV/c2 (1 TeV/c2, 10 TeV/c2).

Dark Sectors at the Fermilab SeaQuest Experiment

Abstract: We analyze the unique capability of the existing SeaQuest experiment at Fermilab to discover well-motivated dark sector physics by measuring displaced electron, photon, and hadron decay signals behind a compact shield. A planned installation of a refurbished electromagnetic calorimeter could provide powerful new sensitivity to GeV-scale vectors, dark Higgs bosons, scalars, axions, and inelastic and strongly interacting dark matter models. This sensitivity is both comparable and complementary to NA62, SHiP, and FASER. SeaQuest’s ability to collect data now and over the next few years provides an especially exciting opportunity.

Atmospheric neutrino oscillation analysis with external constraints in Super-Kamiokande I-IV

Abstract: An analysis of atmospheric neutrino data from all four run periods of Super-Kamiokande optimized for sensitivity to the neutrino mass hierarchy is presented. Confidence intervals for Δm2 32, sin2 θ23, sin2 θ13 and δCP are presented for normal neutrino mass hierarchy and inverted neutrino mass hierarchy hypotheses, based on atmospheric neutrino data alone. Additional constraints from reactor data on θ13 and from published binned T2K data on muon neutrino disappearance and electron neutrino appearance are added to the atmospheric neutrino fit to give enhanced constraints on the above parameters. Over the range of parameters allowed at 90% confidence level, the normal mass hierarchy is favored by between 91.9% and 94.5% based on the combined Super-Kamiokande plus T2K result.

Time-domain effective-one-body gravitational waveforms for coalescing compact binaries with nonprecessing spins, tides, and self-spin effects

Abstract: We present TEOBResumS, a new effective-one-body (EOB) waveform model for nonprecessing (spin-aligned) and tidally interacting compact binaries. Spin-orbit and spin-spin effects are blended together by making use of the concept of centrifugal EOB radius. The point-mass sector through merger and ringdown is informed by numerical relativity (NR) simulations of binary black holes (BBHs) computed with the SpEC and bam codes. An improved, NR-based phenomenological description of the postmerger waveform is developed. The tidal sector of TEOBResumS describes the dynamics of neutron star binaries up to merger and incorporates a resummed attractive potential motivated by recent advances in the post-Newtonian and gravitational self-force description of relativistic tidal interactions. Equation-of-state-dependent self-spin interactions (monopole-quadrupole effects) are incorporated in the model using leading order post-Newtonian results in a new expression of the centrifugal radius. TEOBResumS is compared to 135 SpEC and 19 bam BBH waveforms. The maximum unfaithfulness to SpEC data ¯ F—at design Advanced LIGO sensitivity and evaluated with total mass M with a variance of 10M⊙≤M≤200M⊙—is always below 2.5×10−3 except for a single outlier that grazes the 7.1×10−3 level. When compared to bam data, ¯ F is smaller than 0.01 except for a single outlier in one of the corners of the NR-covered parameter space that reaches the 0.052 level. TEOBResumS is also compatible, up to merger, to high-end NR waveforms from binary neutron stars with spin effects and reduced initial eccentricity computed with the bam and thc codes. The data quality of binary neutron star waveforms is assessed via rigorous convergence tests from multiple resolution runs and takes into account systematic effects estimated by using the two independent high-order NR codes. The model is designed to generate accurate templates for the analysis of LIGO-Virgo data through merger and ringdown. We demonstrate its use by analyzing the publicly available data for GW150914.

Cosmological implications of ultralight axionlike fields

Abstract: Cosmological observations are used to test for imprints of an ultralight axionlike field (ULA), with a range of potentials $V(\ensuremath{\phi})\ensuremath{\propto}[1\ensuremath{-}\mathrm{cos}(\ensuremath{\phi}/f){]}^{n}$ set by the axion-field value $\ensuremath{\phi}$ and decay constant $f$. Scalar field dynamics dictate that the field is initially frozen and then begins to oscillate around its minimum when the Hubble parameter drops below some critical value. For $n=1$, once dynamical, the axion energy density dilutes as matter; for $n=2$ it dilutes as radiation and for $n=3$ it dilutes faster than radiation. Both the homogeneous evolution of the ULA and the dynamics of its linear perturbations are included, using an effective fluid approximation generalized from the usual $n=1$ case. ULA models are parametrized by the redshift ${z}_{c}$ when the field becomes dynamical, the fractional energy density ${f}_{{z}_{c}}\ensuremath{\equiv}{\mathrm{\ensuremath{\Omega}}}_{a}({z}_{c})/{\mathrm{\ensuremath{\Omega}}}_{\mathrm{tot}}({z}_{c})$ in the axion field at ${z}_{c}$, and the effective sound speed ${c}_{s}^{2}$. Using Planck, BAO and JLA data, constraints on ${f}_{{z}_{c}}$ are obtained. ULAs are degenerate with dark energy for all three potentials if $1+{z}_{c}\ensuremath{\lesssim}10$. When $3\ifmmode\times\else\texttimes\fi{}{10}^{4}\ensuremath{\gtrsim}1+{z}_{c}\ensuremath{\gtrsim}10$, ${f}_{{z}_{c}}$ is constrained to be $\ensuremath{\lesssim}0.004$ for $n=1$ and ${f}_{{z}_{c}}\ensuremath{\lesssim}0.02$ for the other two potentials. The constraints then relax with increasing ${z}_{c}$. These results have implications for ULAs as a resolution to cosmological tensions, such as discrepant measurements of the Hubble constant, or the EDGES measurement of the global 21 cm signal.