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Examining the self-interaction of dark matter through central cluster galaxy offsets
No full textWhile collisionless cold dark matter models have been largely successful in explaining a wide range of observational data, some tensions still exist, and it remains possible that dark matter possesses a non-negligible level of self-interactions. In this paper, we investigate a possible observable consequence of self-interacting dark matter: offsets between the central galaxy and the centre of mass of its parent halo. We examine 23 relaxed galaxy clusters in a redshift range of 0.1–0.3 drawn from clusters in the Dark Energy Survey and the Sloan Digital Sky Survey which have archival Chandra X-ray data of sufficient depth for centre and relaxation determination. We find that most clusters in our sample show non-zero offsets between the X-ray centre, taken to be the centroid within the cluster core, and the central galaxy position. All of the measured offsets are larger, typically by an order of magnitude, than the uncertainty in the X-ray position due to Poisson noise. In all but six clusters, the measured offsets are also larger than the estimated, combined astrometric uncertainties in the X-ray and optical positions. A more conservative cut on concentration to select relaxed clusters marginally reduces but does not eliminate the observed offset. With our more conservative sample, we find an estimated median X-ray to central galaxy offset of || kpc. Comparing to recent simulations, this distribution of offsets is consistent with some level of dark matter self-interaction, though further simulation work is needed to place constraints
Reaction plane correlated triangular flow in <math><mtext>Au</mtext><mo>+</mo><mtext>Au</mtext></math> collisions at <math><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>3</mn></mrow></math> GeV
No full textWe measure triangular flow relative to the reaction plane at 3 GeV center-of-mass energy in Au+Au collisions at the BNL Relativistic Heavy Ion Collider. A significant v3 signal for protons is observed, which increases for higher rapidity, higher transverse momentum, and more peripheral collisions. The triangular flow is essentially rapidity-odd with a slope at midrapidity, dv3/dy|(y=0), opposite in sign compared to the slope for directed flow. No significant v3 signal is observed for charged pions and kaons. Comparisons with models suggest that a mean field potential is required to describe these results, and that the triangular shape of the participant nucleons is the result of stopping and nuclear geometry
Search for singly produced vectorlike top partners in multilepton final states with <math display="inline"><mn>139</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>-</mo><mn>1</mn></mrow></msup></math> of <math display="inline"><mi>p</mi><mi>p</mi></math> collision data at <math display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math> with the ATLAS detector
No full textA search for the single production of a vectorlike top partner (T) with mass greater than 1 TeV decaying into a Z boson and a top quark is presented, using the full Run 2 dataset corresponding to 139 fb-1 of pp collisions at s=13 TeV, collected in 2015–2018 with the ATLAS detector at the Large Hadron Collider. The targeted final state is characterized by the presence of a pair of electrons or muons with opposite-sign charges which form a Z-boson candidate, as well as by the presence of b-tagged jets and forward jets. Events with exactly two or at least three leptons are categorized into two independently optimized analysis channels. No significant excess above the background expectation is observed and the results from the two channels are statistically combined to set exclusion limits at 95% confidence level on the masses and couplings of T. The results are interpreted in several benchmark scenarios to set limits on the mass and universal coupling strength (κ) of the vectorlike quark. For singlet T quarks, κ values between 0.22 and 0.64 are excluded for masses between 1000 and 1975 GeV. For T quarks in the doublet scenario, where the production cross section is much lower, κ values between 0.54 and 0.88 are excluded for masses between 1000 and 1425 GeV
Measurement of the and cross-sections in pp collisions at TeV with the ATLAS detector
No full textThe inclusive Higgs boson production cross-section is measured in the di-photon and the decay channels using 31.4 and 29.0 fb of pp collision data respectively, collected with the ATLAS detector at a centre-of-mass energy of . To reduce the model dependence, the measurement in each channel is restricted to a particle-level phase space that closely matches the channel's detector-level kinematic selection, and it is corrected for detector effects. These measured fiducial cross-sections are fb, and fb, in agreement with the corresponding Standard Model predictions of fb and fb. Assuming Standard Model acceptances and branching fractions for the two channels, the fiducial measurements are extrapolated to the full phase space yielding total cross-sections of pb and pb at 13.6 from the di-photon and measurements respectively. The two measurements are combined into a total cross-section measurement of pb, to be compared with the Standard Model prediction of pb
Measurement of simplified template cross sections of the Higgs boson produced in association with <math display="inline"><mi>W</mi></math> or <math display="inline"><mi>Z</mi></math> bosons in the <math display="inline"><mi>H</mi><mo stretchy="false">→</mo><mi>b</mi><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover></math> decay channel in proton-proton collisions at <math display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math>
No full textDifferential cross sections are measured for the standard model Higgs boson produced in association with vector bosons (W, Z) and decaying to a pair of b quarks. Measurements are performed within the framework of the simplified template cross sections. The analysis relies on the leptonic decays of the W and Z bosons, resulting in final states with 0, 1, or 2 electrons or muons. The Higgs boson candidates are either reconstructed from pairs of resolved b-tagged jets, or from single large-radius jets containing the particles arising from two b quarks. Proton-proton collision data at s=13 TeV, collected by the CMS experiment in 2016–2018 and corresponding to a total integrated luminosity of 138 fb-1, are analyzed. The inclusive signal strength, defined as the product of the observed production cross section and branching fraction relative to the standard model expectation, combining all analysis categories, is found to be μ=1.15-0.20+0.22. This corresponds to an observed (expected) significance of 6.3 (5.6) standard deviations
Measurement of (anti)alpha production in central Pb–Pb collisions at <math altimg="si1.svg"><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi mathvariant="normal">NN</mi></mrow></msub></mrow></msqrt><mo linebreak="goodbreak" linebreakstyle="after">=</mo><mn>5.02</mn></math> TeV
No full textIn this letter, measurements of (anti)alpha production in central (0–10%) Pb–Pb collisions at a center-of-mass energy per nucleon–nucleon pair of sNN = 5.02 TeV are presented, including the first measurement of an antialpha transverse-momentum spectrum. Owing to its large mass, the production of (anti)alpha is expected to be sensitive to different particle production models. The production yields and transverse-momentum spectra of nuclei are of particular interest because they provide a stringent test of these models. The averaged antialpha and alpha spectrum is compared to the spectra of lighter particles, by including it into a common blast-wave fit capturing the hydrodynamic-like flow of all particles. This fit is indicating that the (anti)alpha also participates in the collective expansion of the medium created in the collision. A blast-wave fit including only protons, (anti)alpha, and other light nuclei results in a similar flow velocity as the fit that includes all particles. A similar flow velocity, but a significantly larger kinetic freeze-out temperature is obtained when only protons and light nuclei are included in the fit. The coalescence parameter B4 is well described by calculations from a statistical hadronization model but significantly underestimated by calculations assuming nucleus formation via coalescence of nucleons. Similarly, the (anti)alpha-to-proton ratio is well described by the statistical hadronization model. On the other hand, coalescence calculations including approaches with different implementations of the (anti)alpha substructure tend to underestimate the data
Observation of and decays
No full textThe and decays are observed for the first time using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of , corresponding to an integrated luminosity of . The relative branching fractions times the beauty-baryon production cross-sections are measured to be \begin{align*} \mathcal{R}\left(\frac{\Xi_b^0}{\Lambda_b^0}\right) \equiv \frac{\sigma\left(\Xi_b^0\right)}{\sigma\left(\Lambda_b^0\right)} \times \frac{\mathcal{B}\left(\Xi_b^0 \rightarrow \Xi_c^+ D_s^-\right)}{\mathcal{B}\left(\Lambda_b^0 \rightarrow \Lambda_c^0 D_s^-\right)} =(15.8\pm1.1\pm0.6\pm7.7)\%, \mathcal{R}\left(\frac{\Xi_b^-}{\Lambda_b^0}\right) \equiv \frac{\sigma\left(\Xi_b^-\right)}{\sigma\left(\Lambda_b^0\right)} \times \frac{\mathcal{B}\left(\Xi_b^- \rightarrow \Xi_c^0 D_s^-\right)}{\mathcal{B}\left(\Lambda_b^0 \rightarrow \Lambda_c^0 D_s^-\right)} =(16.9\pm1.3\pm0.9\pm4.3)\%, \end{align*} where the first uncertainties are statistical, the second systematic, and the third due to the uncertainties on the branching fractions of relevant charm-baryon decays. The masses of and baryons are measured to be and , where the uncertainties are statistical, systematic, and those due to charm-hadron masses, respectively
Comments on integrability in the symmetric orbifold
No full textWe present a map between the excitation of the symmetric-product orbifold CFT of T, and of the worldsheet-integrability description of AdS × S × T of Lloyd, Ohlsson Sax, Sfondrini, and Stefański at k = 1. We discuss the map in the absence of RR fluxes, when the theory is free, and at small RR flux, h ≪ 1, where the symmetric-orbifold CFT is deformed by a marginal operator from the twist-two sector. We discuss the recent results of Gaberdiel, Gopakumar, and Nairz, who computed from the perturbed symmetric-product orbifold the central extension to the symmetry algebra of the theory and its coproduct. We show that it coincides with the h ≪ 1 expansion of the lightcone symmetry algebra known from worldsheet integrability, and that hence the S matrix found by Gaberdiel, Gopakumar, and Nairz maps to the one bootstrapped by the worldsheet integrability approach
Mass-redshift dependency of supermassive black hole binaries for the gravitational wave background
No full textStudying how the black hole (BH)–(galaxy) bulge mass relation evolves with redshift provides valuable insights into the co-evolution of supermassive black holes and their host galaxies. However, obtaining accurate measurement of BH masses is challenging due to the bias towards the most massive and luminous galaxies. Instead, we focus on the BH and bulge masses as they vary with redshift using the EAGLE, Illustris, TNG100, TNG300, Horizon-AGN, and SIMBA large-scale cosmological simulations. We use an analytical astrophysical model with galaxy stellar mass function, pair fraction, merger time-scale and BH–bulge mass relation extended to include redshift evolution. The model can predict the intensity of the gravitational wave background (GWB) produced by a population of supermassive black hole binary (SMBHB) as a function of the frequency. This allows us to compare the predictions of this model with the constraints of pulsar timing array observations. Here, we employ Bayesian analysis for the parameter inference. We find that all six simulations are consistent || with a range of simulated GWB spectra. By fixing the BH–bulge mass parameters to the simulations we analyse the changes in the constraints on the other astrophysical parameters. Furthermore, we also examine the variation in SMBHB merger rate with mass and redshift between these large-scale simulations
Relativistic effects in Green's function Monte Carlo calculations of neutrino-nucleus scattering
No full textMicroscopic calculations of neutrino-nucleus scattering cross sections are critical for the success of the neutrino-oscillation program. In addition to retaining nuclear correlations in the initial and final state of the reaction, they are based on consistent nuclear interactions and transition current operators, thereby enabling robust uncertainty quantification. In this work, we address a significant limitation of these microscopic methods, which arises from their nonrelativistic nature. By performing the calculations in a reference frame that minimizes nucleon momenta and utilizing the so-called two-fragment model, we extend the applicability of Green's function Monte Carlo calculations of neutrino-nucleus scattering to higher momenta than currently possible. To validate this approach, we compare our theoretical predictions against inclusive data measured by the MiniBooNE, T2K, and MINERνA experiments