Post-Newtonian gravitational waves with cosmological constant from the Einstein-Hilbert theory

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U (1) B− L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U (1) B− L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM.

arXiv preprint arXiv:2403.03004

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM.

arXiv preprint arXiv:2308.13666

The detection of GW170817 (Abbott et al. 2017b) coincident with the short gamma-ray burst GRB 170817A (Goldstein et al. 2017; Savchenko et al. 2017) was a groundbreaking discovery for the multimessenger era. Not only was it the first binary neutron star (BNS) merger detected by the gravitational-wave (GW) instruments Advanced LIGO (Aasi et al. 2015) and Advanced Virgo (Acernese et al. 2014), it was also the first, and to date only, GW detection with a confirmed electromagnetic (EM) counterpart. Since then, the search for EM emission from more of these extreme events has been at the forefront of multimessenger astronomy, particularly in the gamma-ray energy band, since GRB 170817A demonstrated that BNS mergers are a progenitor of short gamma-ray bursts (GRBs; Abbott et al. 2017a). GWs have also been observed from the mergers of other compact objects, such as binary black hole (BBH) and …

Physical Review D

The second Gravitational-Wave Transient Catalog, GWTC-2, reported on 39 compact binary coalescences observed by the Advanced LIGO and Advanced Virgo detectors between 1 April 2019 15∶ 00 UTC and 1 October 2019 15∶ 00 UTC. Here, we present GWTC-2.1, which reports on a deeper list of candidate events observed over the same period. We analyze the final version of the strain data over this period with improved calibration and better subtraction of excess noise, which has been publicly released. We employ three matched-filter search pipelines for candidate identification, and estimate the probability of astrophysical origin for each candidate event. While GWTC-2 used a false alarm rate threshold of 2 per year, we include in GWTC-2.1, 1201 candidates that pass a false alarm rate threshold of 2 per day. We calculate the source properties of a subset of 44 high-significance candidates that have a …

Despite the growing number of candidates and the insight they have provided, the astrophysical sites and processes that produce the observed merging binaries remain uncertain. Multiple viable scenarios exist. The binary black holes could have formed in an isolated stellar binary (eg, Bethe & Brown 1998; Dominik et al. 2015; Inayoshi et al. 2017; Marchant et al. 2016; de Mink & Mandel 2016; Gallegos-Garcia et al. 2021), via dynamical interactions in dense stellar clusters (eg, Portegies Zwart & McMillan 2000; Banerjee et al. 2010; Ziosi et al. 2014; Morscher et al. 2015; Mapelli 2016; Rodriguez et al. 2016a; Askar et al. 2017) or triple systems (eg, Antonini et al. 2017; Martinez et al. 2020; Vigna-Gómez et al. 2021), or via gas capture in the disks of active galactic nuclei (AGN; eg, McKernan et al. 2012; Bartos et al. 2017; Fragione et al. 2019; Tagawa et al. 2020).

arXiv preprint arXiv:2312.10443

In this article we analyze an effective action derived from a 7-dimensional theory that, upon dimensional reduction, it transforms into an effective 4-dimensional action. Such resulting effective action involves a generic metric; however, we study a cosmological model described by a de Sitter universe, with a Hubble constant . We compute the barotropic parameter to analyze our solutions. Three different upshots are presented, where this model can transit from quintessence to the phantom regimes, crossing the theoretical phantom divide line. Thus the effective action represents a quintom scenario.

In this review we examine the amplitude intensity associated to tensorial and non-tensorial polarization modes generated by binary systems at their inspiral stage, within the alternative theories of gravity of Brans–Dicke, Rosen, and Lightman–Lee. This study is performed without making an explicit use of the Transverse Traceless gauge of the General Relativity approach, and at the Newtonian limit. Consequently such additional polarization modes appear (non-tensorial) due to additional degrees of freedom in modified theories of gravitation. We model and compare the different polarization modes and strain signals for each scheme varying the sky location. Our analysis allows us to identify the locations where these modes are more intense, and, therefore susceptible to being identified for the future interferometer detector network. This gives rise to a framework in which the amplitude and the intensity of all …

arXiv preprint arXiv:2308.03822

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass ) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities at Gpc yr at 90\% confidence level.

Physical Review X

The third Gravitational-Wave Transient Catalog (GWTC-3) describes signals detected with Advanced LIGO and Advanced Virgo up to the end of their third observing run. Updating the previous GWTC-2.1, we present candidate gravitational waves from compact binary coalescences during the second half of the third observing run (O3b) between 1 November 2019, 15∶ 00 Coordinated Universal Time (UTC) and 27 March 2020, 17∶ 00 UTC. There are 35 compact binary coalescence candidates identified by at least one of our search algorithms with a probability of astrophysical origin p astro> 0.5. Of these, 18 were previously reported as low-latency public alerts, and 17 are reported here for the first time. Based upon estimates for the component masses, our O3b candidates with p astro> 0.5 are consistent with gravitational-wave signals from binary black holes or neutron-star–black-hole binaries, and we identify …

arXiv preprint arXiv:2304.11498

We present a methodology based on the implementation of a fully connected neural network to estimate the gravitational wave (GW) temporal evolution of the gmode fundamental resonant frequency for a Core Collapse Supernova (CCSN). To perform the estimation, we construct a training data set, using synthetic waveforms, that serves to train the ML algorithm, and then use several CCSN waveforms to test the model. According to the results obtained from the implementation of our model, we provide numerical evidence to support the classification of progenitors according to their degree of rotation. The relative error associated with the estimate of the slope of the resonant frequency versus time for the GW from CCSN signals is within for the tested candidates included in this study. This method of classification does not require priors or templates, it is based on physical modelling, and can be combined with studies that classify the progenitor with other physical features.

Journal of Cosmology and Astroparticle Physics

We present a method to determine the angular momentum of a black hole based on observations of the trajectories of the bodies in the Kerr spacetime. We use the Hamilton equations to describe the dynamics of a particle and present results for equatorial trajectories, obtaining an algebraic equation for the magnitude of the black hole's angular momentum with coefficients given by observable quantities. We tailor a numerical code to solve the dynamical equations and use it to generate synthetic data. We apply the method in some representative examples, obtaining the parameters of the trajectories as well as the black hole's angular momentum in good agreement with the input data.

Physics of the Dark Universe

Starting with the Lagrangian formulation of General Relativity, we will conduct an investigation into the production of spacetime waves, due to a geometric boundary term of a closed extended manifold, within the tensor and scalar sectors. This scheme will be studied in an inflationary universe. We explore two distinct scenarios: Cold Inflation and Warm Inflation. The scalar modes Z k R and Z k I oscillate within the horizon, and become constant at (or right after) horizon crossing k≃ a H and they remain so when radiation starts to dominate. The larger k/k 0 the Z k’s amplitudes increase too. In general, we can notice that radiation reduces the size of the Z k’s amplitudes, hence yielding smaller signals of such modes. The tensor sector shows an irregular journey due to their abrupt growth just as they cross the horizon. This in turn hinders any probable observational hint or signal. However, we expect that this novel …

arXiv preprint arXiv:2304.08393

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects.

In this paper we propose the use of a deep learning based model for inferring astrophysical information of binary black hole (BBH) systems from observed gravitational wave (GW) signals. We focused in estimating the total mass of BBH systems using a convolutional neural network regression (CNNR) model. We built a large dataset of 2D images representing the time-frequency evolution of BBH GW signals which are embedded in noise, where for each generated image the real total mass is known. . A hold-out cross-validation procedure was performed to train and evaluate five architectures of CNNR models with different number and sizes of kernels. The results indicate that the proposed deep neural network models for regression provide reliable point-parameter estimations with high accuracy. This estimation parameter approach can be easily extended to reconstruct more parameters from astrophysical sources directly from obseved GW events.

arXiv preprint arXiv:2304.01267

In this work, we obtain the error estimate of the rotation parameter from the core bounce phase of the characteristic gravitational wave signal of a rapidly rotating core collapse supernova (CCSN). We quantify the error with asymptotic expansions of the covariance of a Maximum Likelihood Estimator (MLE) in terms of inverse powers of Signal-Noise Ratio (SNR), this method has been previously applied to parameter estimation for compact binary coalescences. When the second order of this expansion is negligible, it indicates that the first order is a good approximation of the error that will have a matching filter approach when estimating . The analysis indicates that we should be able to resolve the presence of rotation for the galactic and nearby extragalactic progenitors. We show that the estimation error can be as small as a few percent and is larger for small values of .

Physical Review D

We present a methodology based on the implementation of a fully connected neural network algorithm to estimate the temporal evolution of the high-frequency gravitational wave emission for a core collapse supernova (CCSN). For this study, we selected a fully connected deep neural network (DNN) regression model because it can learn both linear and nonlinear relationships between the input and output data, it is more appropriate for handling large-dimensional input data, and it offers high performance at a low computational cost. To train the Machine Learning (ML) algorithm, we construct a training dataset using synthetic waveforms, and several CCSN waveforms are used to test the algorithm. We performed a first-order estimation of the high-frequency gravitational wave emission on real interferometric LIGO data from the second half of the third observing run (O3b) with a two detector network (L1 and H1). The …

Journal of Mathematical Physics

In this work, we describe the partial collapse of a compact object and the emission of spacetime waves as a result of back-reaction effects. As a source mass term, we propose a non-smooth continuous function that describes a mass-loss, and we then obtain the solution of such setting. We present three distinct examples of the evolution of the norm∣ Rnl (t, r∗)∣ in terms of t, and four different results are shown for the parameter l= 1, 2, 5, 10; here, r∗ is the fixed radius of an observer outside the compact object. In all cases, the decay behavior is actually present at t≫ 1 and becomes more evident for larger l. In addition, for the results that have smaller l’s, their amplitudes are larger when the asymptotic character of∣ Rnl (t, r∗)∣ clearly appears. Finally, the farther away an observer is set, the fewer oscillations are perceived; however, from our particular fixed set of parameters, the best spot to observe the wiggles of the …

Physical Review X

We report on the population properties of compact binary mergers inferred from gravitational-wave observations of these systems during the first three LIGO-Virgo observing runs. The Gravitational-Wave Transient Catalog 3 (GWTC-3) contains signals consistent with three classes of binary mergers: binary black hole, binary neutron star, and neutron star–black hole mergers. We infer the binary neutron star merger rate to be between 10 and 1700 Gpc− 3 yr− 1 and the neutron star–black hole merger rate to be between 7.8 and 140 Gpc− 3 yr− 1, assuming a constant rate density in the comoving frame and taking the union of 90% credible intervals for methods used in this work. We infer the binary black hole merger rate, allowing for evolution with redshift, to be between 17.9 and 44 Gpc− 3 yr− 1 at a fiducial redshift (z= 0.2). The rate of binary black hole mergers is observed to increase with redshift at a rate proportional …

The Astrophysical Journal

Fast radio bursts (FRBs) are millisecond duration radio pulses that have been observed out to cosmological distances, several with inferred redshifts greater than unity (Lorimer et al. 2007; Cordes & Chatterjee 2019; Petroff et al. 2019). Although intensely studied for more than a decade, the emission mechanisms and progenitor populations of FRBs are still one of the outstanding questions in astronomy. Some FRBs have been shown to repeat (Amiri et al. 2019a; CHIME/FRB Collaboration et al. 2019; Kumar et al. 2019), and the recent association of an FRB with the Galactic magnetar SGR 1935+ 2154 proves that magnetars can produce FRBs (Bochenek et al. 2020; CHIME/FRB Collaboration et al. 2020). Alternative progenitors and mechanisms to produce nonrepeating FRBs are still credible and have so far not been ruled out (Zhang 2020a). Data currently suggest that both repeating and nonrepeating classes of …

Physical Review D

The precision with which hadronic vacuum polarization (HVP) is obtained determines how accurately important observables, such as the muon anomalous magnetic moment a μ or the low-energy running of the electromagnetic coupling α, are predicted. The two most precise approaches for determining HVP are dispersive relations combined with e+ e−→ hadrons cross section data and lattice QCD. However, the results obtained in these two approaches display significant tensions, whose origins are not understood. Here we present a framework that sheds light on this issue and—if the two approaches can be reconciled—allows them to be combined. Via this framework, we test the hypothesis that the tensions can be explained by modifying the R-ratio in different intervals of center-of-mass energy s. As ingredients, we consider observables that have been precisely determined in both approaches. These are the …

Physical Review D

A search for quantum black holes in electron+ jet and muon+ jet invariant mass spectra is performed with 140 fb− 1 of data collected by the ATLAS detector in proton-proton collisions at s= 13 TeV at the Large Hadron Collider. The observed invariant mass spectrum of lepton+ jet pairs is consistent with Standard Model expectations. Upper limits are set at 95% confidence level on the production cross section times branching fractions for quantum black holes decaying into a lepton and a quark in a search region with invariant mass above 2.0 TeV. The resulting quantum black hole lower mass threshold limit is 9.2 TeV in the Arkani-Hamed-Dimopoulos-Dvali model, and 6.8 TeV in the Randall-Sundrum model.

Physical Review D

A search for quantum black holes in electron+ jet and muon+ jet invariant mass spectra is performed with 140 fb− 1 of data collected by the ATLAS detector in proton-proton collisions at s= 13 TeV at the Large Hadron Collider. The observed invariant mass spectrum of lepton+ jet pairs is consistent with Standard Model expectations. Upper limits are set at 95% confidence level on the production cross section times branching fractions for quantum black holes decaying into a lepton and a quark in a search region with invariant mass above 2.0 TeV. The resulting quantum black hole lower mass threshold limit is 9.2 TeV in the Arkani-Hamed-Dimopoulos-Dvali model, and 6.8 TeV in the Randall-Sundrum model.

Physical Review D

In this work we analyze the motion of charged particles in the background of the Kiselev geometry, which is considered here as an exact solution in the context of power-Maxwell electrodynamics. As it is well known, one can use either an electric ansatz or a magnetic one for the nonlinear electromagnetic field. We study the motion of an electrically charged particle for an electrically charged black hole and also for a magnetically charged black hole. In the second case the motion is restricted to Poincaré cones of various angles, as expected.

Physical Review D

Ultracold atomic gases can undergo phase transitions that mimic relativistic vacuum decay, allowing us to empirically test early Universe physics in tabletop experiments. We investigate the physics of these analog systems, going beyond previous analyses of the classical equations of motion to study quantum fluctuations in the cold-atom false vacuum. We show that the fluctuation spectrum of this vacuum state agrees with the usual relativistic result in the regime where the classical analogy holds, providing further evidence for the suitability of these systems for studying vacuum decay. Using a suite of semiclassical lattice simulations, we simulate bubble nucleation from this analog vacuum state in a 1D homonuclear potassium-41 mixture, finding qualitative agreement with instanton predictions. We identify realistic parameters for this system that will allow us to study vacuum decay with current experimental …

Physical Review D

The evolution of linear initial conditions present in the early Universe into extended halos of dark matter at late times can be computed using cosmological simulations. However, a theoretical understanding of this complex process remains elusive; in particular, the role of anisotropic information in the initial conditions in establishing the final mass of dark matter halos remains a long-standing puzzle. Here, we build a deep learning framework to investigate this question. We train a three-dimensional convolutional neural network to predict the mass of dark matter halos from the initial conditions, and quantify in full generality the amounts of information in the isotropic and anisotropic aspects of the initial density field about final halo masses. We find that anisotropies add a small, albeit statistically significant amount of information over that contained within spherical averages of the density field about final halo mass …

Physical Review D

We investigate the hypothetical X17 boson on neutron stars and quark stars (QSs) using various hadronic equation of states (EoSs) with phenomenological or microscopic origin. Our aim is to set realistic constraints on its coupling constant and the mass scaling, with respect to causality and various possible upper mass limits and the dimensionless tidal deformability Λ 1.4. In particular, we pay special attention to two main phenomenological parameters of the X17, one is related to the coupling constant g that it has with hadrons or quarks and the other with the in-medium effects through regulator C. Both are very crucial concerning the contribution on the total energy density and pressure. In the case of considering the X17 as a carrier of nuclear force in relativistic mean field theory, an admixture into the vector boson segment was constrained by 20% and 30%. In our investigation, we came to the general conclusion …

Physical Review D

The recent analysis on the central compact object in the HESS J1731-347 remnant suggests interestingly small values for its mass and radius. Such an observation favors soft nuclear models that may be challenged by the observation of massive compact stars. In contrast, the recent PREX-II experiment, concerning the neutron skin thickness of Pb 208, points toward stiff equations of state that favor larger compact star radii. In the present study, we aim to explore the compatibility between stiff hadronic equations of state (favored by PREX-II) and the HESS J1731-347 remnant in the context of hybrid stars. For the construction of hybrid equations of state we use three widely employed Skyrme models combined with the well-known vector MIT bag model. Furthermore we consider two different scenarios concerning the energy density of the bag. In the first case, that of a constant bag parameter, we find that the resulting …

Physical Review D

The second Gravitational-Wave Transient Catalog, GWTC-2, reported on 39 compact binary coalescences observed by the Advanced LIGO and Advanced Virgo detectors between 1 April 2019 15∶ 00 UTC and 1 October 2019 15∶ 00 UTC. Here, we present GWTC-2.1, which reports on a deeper list of candidate events observed over the same period. We analyze the final version of the strain data over this period with improved calibration and better subtraction of excess noise, which has been publicly released. We employ three matched-filter search pipelines for candidate identification, and estimate the probability of astrophysical origin for each candidate event. While GWTC-2 used a false alarm rate threshold of 2 per year, we include in GWTC-2.1, 1201 candidates that pass a false alarm rate threshold of 2 per day. We calculate the source properties of a subset of 44 high-significance candidates that have a …

Physical Review D

We study the compact binary dynamics in the post-Newtonian approach implemented to the Einstein-Hilbert action adding the cosmological constant Λ at first post-Newtonian (1PN) order. We consider very small values of Λ finding that it plays the role of a PN factor to derive the Lagrangian of a compact two-body system at the center of mass frame at 1PN. Furthermore, the phase function ϕ (t) is obtained from the balance equation, and the two polarizations h+ and h× are also calculated. We observe changes due to Λ only at very low frequencies, and we notice that it plays the role of “stretch” the spacetime such that both amplitudes become smaller. However, given its nearly negligible value, Λ has no relevance at higher frequencies whatsoever.

Physical Review D

The nuclear reaction network within the interior of the Sun is an efficient MeV physics factory and can produce long-lived particles generic to dark sector models. In this work we consider the sensitivity of satellite instruments, primarily the RHESSI spectrometer, that observe the quiet Sun in the MeV regime where backgrounds are low. We find that quiet Sun observations offer a powerful and complementary probe in regions of parameter space, where the long-lived particle decay length is longer than the radius of the Sun and shorter than the distance between the Sun and Earth. We comment on connections to recent model-building work on heavy neutral leptons coupled to neutrinos and high-quality axions from mirror symmetries.

Physical Review D

Within the framework of relative and absolute quantum field theories (QFTs), we present a general formalism for understanding polarizations of the intermediate defect group and constructing noninvertible duality defects in theories in 2 k spacetime dimensions with self-dual gauge fields. We introduce the polarization pair, which fully specifies absolute QFTs as far as their (k− 1)-form defect groups are concerned, including their (k− 1)-form symmetries, global structures (including discrete θ-angle), and local counterterms. Using the associated symmetry topological field theory (TFT), we show that the polarization pair is capable of succinctly describing topological manipulations, eg, gauging (k− 1)-form global symmetries and stacking counterterms, of absolute QFTs. Furthermore, automorphisms of the (k− 1)-form charge lattice naturally act on polarization pairs via their action on the defect group; they can be viewed as …

Physical Review D

Recent measurements of charm-baryon production in hadronic collisions have questioned the universality of charm-quark fragmentation across different collision systems. In this work the fragmentation of charm quarks into charm baryons is probed, by presenting the first measurement of the longitudinal jet momentum fraction carried by Λ c+ baryons, z∥ ch, in hadronic collisions. The results are obtained in proton-proton (p p) collisions at s= 13 TeV at the LHC, with Λ c+ baryons and charged (track-based) jets reconstructed in the transverse momentum intervals of 3≤ p T Λ c+< 15 GeV/c and 7≤ p T jet ch< 15 GeV/c, respectively. The z∥ ch distribution is compared to a measurement of D 0-tagged charged jets in p p collisions as well as to pythia 8 simulations. The data hints that the fragmentation of charm quarks into charm baryons is softer with respect to charm mesons, in the measured kinematic interval, as …

Physical Review D

The second Gravitational-Wave Transient Catalog, GWTC-2, reported on 39 compact binary coalescences observed by the Advanced LIGO and Advanced Virgo detectors between 1 April 2019 15∶ 00 UTC and 1 October 2019 15∶ 00 UTC. Here, we present GWTC-2.1, which reports on a deeper list of candidate events observed over the same period. We analyze the final version of the strain data over this period with improved calibration and better subtraction of excess noise, which has been publicly released. We employ three matched-filter search pipelines for candidate identification, and estimate the probability of astrophysical origin for each candidate event. While GWTC-2 used a false alarm rate threshold of 2 per year, we include in GWTC-2.1, 1201 candidates that pass a false alarm rate threshold of 2 per day. We calculate the source properties of a subset of 44 high-significance candidates that have a …

Physical Review D

The second Gravitational-Wave Transient Catalog, GWTC-2, reported on 39 compact binary coalescences observed by the Advanced LIGO and Advanced Virgo detectors between 1 April 2019 15∶ 00 UTC and 1 October 2019 15∶ 00 UTC. Here, we present GWTC-2.1, which reports on a deeper list of candidate events observed over the same period. We analyze the final version of the strain data over this period with improved calibration and better subtraction of excess noise, which has been publicly released. We employ three matched-filter search pipelines for candidate identification, and estimate the probability of astrophysical origin for each candidate event. While GWTC-2 used a false alarm rate threshold of 2 per year, we include in GWTC-2.1, 1201 candidates that pass a false alarm rate threshold of 2 per day. We calculate the source properties of a subset of 44 high-significance candidates that have a …

Physical Review D

A search for quantum black holes in electron+ jet and muon+ jet invariant mass spectra is performed with 140 fb− 1 of data collected by the ATLAS detector in proton-proton collisions at s= 13 TeV at the Large Hadron Collider. The observed invariant mass spectrum of lepton+ jet pairs is consistent with Standard Model expectations. Upper limits are set at 95% confidence level on the production cross section times branching fractions for quantum black holes decaying into a lepton and a quark in a search region with invariant mass above 2.0 TeV. The resulting quantum black hole lower mass threshold limit is 9.2 TeV in the Arkani-Hamed-Dimopoulos-Dvali model, and 6.8 TeV in the Randall-Sundrum model.

Physical Review D

Recent measurements of charm-baryon production in hadronic collisions have questioned the universality of charm-quark fragmentation across different collision systems. In this work the fragmentation of charm quarks into charm baryons is probed, by presenting the first measurement of the longitudinal jet momentum fraction carried by Λ c+ baryons, z∥ ch, in hadronic collisions. The results are obtained in proton-proton (p p) collisions at s= 13 TeV at the LHC, with Λ c+ baryons and charged (track-based) jets reconstructed in the transverse momentum intervals of 3≤ p T Λ c+< 15 GeV/c and 7≤ p T jet ch< 15 GeV/c, respectively. The z∥ ch distribution is compared to a measurement of D 0-tagged charged jets in p p collisions as well as to pythia 8 simulations. The data hints that the fragmentation of charm quarks into charm baryons is softer with respect to charm mesons, in the measured kinematic interval, as …

Physical Review D

A search for quantum black holes in electron+ jet and muon+ jet invariant mass spectra is performed with 140 fb− 1 of data collected by the ATLAS detector in proton-proton collisions at s= 13 TeV at the Large Hadron Collider. The observed invariant mass spectrum of lepton+ jet pairs is consistent with Standard Model expectations. Upper limits are set at 95% confidence level on the production cross section times branching fractions for quantum black holes decaying into a lepton and a quark in a search region with invariant mass above 2.0 TeV. The resulting quantum black hole lower mass threshold limit is 9.2 TeV in the Arkani-Hamed-Dimopoulos-Dvali model, and 6.8 TeV in the Randall-Sundrum model.

Physical Review D

We use data from the Atacama Cosmology Telescope (ACT) DR4 to search for the presence of neutrino self-interaction in the cosmic microwave background. Consistent with prior works, the posterior distributions we find are bimodal, with one mode consistent with Λ CDM and one where neutrinos strongly self-interact. By combining ACT data with large-scale information from WMAP, we find that a delayed onset of neutrino free streaming caused by significantly strong neutrino self-interaction is compatible with these data at the 2− 3 σ level. As seen in the past, the preference shifts to Λ CDM with the inclusion of Planck data. We determine that the preference for strong neutrino self-interaction is largely driven by angular scales corresponding to 700≲ ℓ≲ 1000 in the ACT E-mode polarization data. This region is expected to be key to discriminate between neutrino self-interacting modes and will soon be probed with …

Physical Review D

We determine the fine-tuning of the Yukawa couplings of supersymmetric QCD, discretized on a lattice. We use perturbation theory at one-loop level. The modified minimal subtraction scheme (MS) is employed; by its definition, this scheme requires perturbative calculations, in the continuum and/or on the lattice. On the lattice, we utilize the Wilson formulation for gluon, quark, and gluino fields; for squark fields we use naive discretization. The sheer difficulties of this study lie in the fact that different components of squark fields mix among themselves at the quantum level and the action’s symmetries, such as parity and charge conjugation, allow an additional Yukawa coupling. Consequently, for an appropriate fine-tuning of the Yukawa terms, these mixings must be taken into account in the renormalization conditions. All Green’s functions and renormalization factors are analytic expressions depending on the number of …