Future $e^+e^-$ colliders are called to play a fundamental role in measuring
Standard Model (SM) parameters with unprecedented precision and the discovery
of physics beyond the SM (BSM). This study ...focus on a QCD-like Hidden Valley
(HV) scenario, with relatively light v-quarks ($\lesssim 100$ GeV), perturbing
the QCD partonic cascade and increasing azimuthal and (pseudo)rapidity
correlations of final-state SM hadrons. Using Pythia8 and detector fast
simulation tools we study $ridge$-$like$ structures arising in the two-particle
angular correlation function, including selection cuts and detector effects.
The analysis of angular particle correlations can yield valuable insights
into the initial state of matter in high-energy collisions, thereby potentially
revealing the existence of Beyond the ...Standard Model scenarios such as Hidden
Valley (HV). In this study, we focus on a QCD-like hidden sector with
relatively massive HV quarks ($\lesssim 100$~GeV) which might enlarge and
strengthen azimuthal correlations of final-state SM hadrons. In particular, we
study the formation and possible observation of \textit{ridge-like} structures
in the angular two-particle correlation function at future $e^+e^-$ colliders,
with a much cleaner environment than in hadron colliders, such as the LHC.
Future \(e^+e^-\) colliders are called to play a fundamental role in measuring Standard Model (SM) parameters with unprecedented precision and the discovery of physics beyond the SM (BSM). This study ...focus on a QCD-like Hidden Valley (HV) scenario, with relatively light v-quarks (\(\lesssim 100\) GeV), perturbing the QCD partonic cascade and increasing azimuthal and (pseudo)rapidity correlations of final-state SM hadrons. Using Pythia8 and detector fast simulation tools we study \(ridge\)-\(like\) structures arising in the two-particle angular correlation function, including selection cuts and detector effects.
The analysis of angular particle correlations can yield valuable insights into the initial state of matter in high-energy collisions, thereby potentially revealing the existence of Beyond the ...Standard Model scenarios such as Hidden Valley (HV). In this study, we focus on a QCD-like hidden sector with relatively massive HV quarks (\(\lesssim 100\)~GeV) which might enlarge and strengthen azimuthal correlations of final-state SM hadrons. In particular, we study the formation and possible observation of \textit{ridge-like} structures in the angular two-particle correlation function at future \(e^+e^-\) colliders, with a much cleaner environment than in hadron colliders, such as the LHC.
KM3NeT is a research infrastructure being installed in the deep Mediterranean Sea. It will house a neutrino telescope comprising hundreds of networked moorings - detection units or strings equipped ...with optical instrumentation to detect the Cherenkov radiation generated by charged particles from neutrino-induced collisions in its vicinity. In comparison to moorings typically used for oceanography, several key features of the KM3NeT string are different: the instrumentation is contained in transparent and thus unprotected glass spheres; two thin Dyneema ropes are used as strength members; and a thin delicate backbone tube with fibre-optics and copper wires for data and power transmission, respectively, runs along the full length of the mooring. Also, compared to other neutrino telescopes such as ANTARES in the Mediterranean Sea and GVD in Lake Baikal, the KM3NeT strings are more slender to minimise the amount of material used for support of the optical sensors. Moreover, the rate of deploying a large number of strings in a period of a few years is unprecedented. For all these reasons, for the installation of the KM3NeT strings, a custom-made, fast deployment method was designed. Despite the length of several hundreds of metres, the slim design of the string allows it to be compacted into a small, re-usable spherical launching vehicle instead of deploying the mooring weight down from a surface vessel. After being lowered to the seafloor, the string unfurls to its full length with the buoyant launching vehicle rolling along the two ropes.The design of the vehicle, the loading with a string, and its underwater self-unrolling are detailed in this paper.
The branching fraction of the rare \(B^0_s\rightarrow\phi\mu^+\mu^-\) decay is measured using data collected by the LHCb experiment at center-of-mass energies of \(7\), \(8\) and \(13\,\rm{TeV}\), ...corresponding to integrated luminosities of \(1\), \(2\) and \(6\,{\rm fb}^{-1}\), respectively. The branching fraction is reported in intervals of \(q^2\), the square of the dimuon invariant mass. In the \(q^2\) region between \(1.1\) and \(6.0\,{\rm Ge\kern -0.1em V}^2\!/c^4\), the measurement is found to lie \(3.6\) standard deviations below a Standard Model prediction based on a combination of Light Cone Sum Rule and Lattice QCD calculations. In addition, the first observation of the rare \(B^0_s\rightarrow f_2^\prime(1525)\mu^+\mu^-\) decay is reported with a statistical significance of nine standard deviations and its branching fraction is determined.
The stellar density distribution of the bulge is analyzed through one of its tracers. We use oxygen-rich Mira variables from the Catchpole et al. survey and OGLE-III survey as standard candles. The ...average age of these stars is around 9 Gyr. The population traced by Mira variables matches a boxy bulge prediction, not an X-shaped one, because only one peak is observed in the density along the analyzed lines of sight, whereas the prediction of an X-shape gives two clear peaks.
ABSTRACT
Statistical analyses of measurements of the Hubble–Lemaître constant H0 (163 measurements between 1976 and 2019) show that the statistical error bars associated with the observed parameter ...measurements have been underestimated – or the systematic errors were not properly taken into account – in at least 15–20 per cent of the measurements. The fact that the underestimation of error bars for H0 is so common might explain the apparent discrepancy of values, which is formally known as the Hubble tension. Here we have carried out a recalibration of the probabilities with this sample of measurements. We find that thexσ deviation is indeed equivalent in a normal distribution to the xeqσ deviation in the frequency of values, where xeq = 0.83x0.62. Hence, a tension of 4.4σ, estimated between the local Cepheid–supernova distance ladder and cosmic microwave background (CMB) data, is indeed a 2.1σ tension in equivalent terms of a normal distribution of frequencies, with an associated probability P(>xeq) = 0.036 (1 in 28). This can be increased up to a equivalent tension of 2.5σ in the worst of the cases of claimed 6σ tension, which may occur anyway as a random statistical fluctuation.
Context. Cosmic chronometers may be used to measure the age difference between passively evolving galaxy populations to calculate the Hubble parameter H(z) as a function of redshift z. The age ...estimator emerges from the relationship between the amplitude of the rest frame Balmer break at 4000 Å and the age of a galaxy, assuming that there is one single stellar population within each galaxy. Aims. First, we analyze the effect on the age estimates from the possible contamination (< 2.4% of the stellar mass in our high-redshift sample) of a young component of ≲ 100 Myr embedded within the predominantly old population of the quiescent galaxy. Recent literature has shown this combination to be present in very massive passively evolving galaxies. Second, we evaluate how the available data compare with the predictions of nine different cosmological models. Methods. For the first task, we calculated the average flux contamination due to a young component in the Balmer break from the data of 20 galaxies at z > 2 that included photometry from the far-ultraviolet to near-infrared at rest. For the second task, we compared the data with the predictions of each model, using a new approach of distinguishing between systematic and statistical errors. In previous work with cosmic chronometers, these have simply been added in quadrature. We also evaluated the effects of contamination by a young stellar component. Results. The ages inferred using cosmic chronometers represent a galaxy-wide average rather than a characteristic of the oldest population alone. The average contribution from the young component to the rest luminosity at 4000 Å may constitute a third of the luminosity in some samples, which means that this is far from negligible. This ratio is significantly dependent on stellar mass, proportional to M−07. Consequently, the measurements of the absolute value of the age or the differential age between different redshifts are at least partially incorrect and make the calculation of H(z) very inaccurate. Some cosmological models, such as the Einstein-de Sitter model or quasi-steady state cosmology, which are rejected under the assumption of a purely old population, can be made compatible with the predicted ages of the Universe as a function of redshift if we take this contamination into account. However, the static Universe models are rejected by these H(z) measurements, even when this contamination is taken into account.
Aims. We explore the outer Galactic disc up to a Galactocentric distance of ≈30 kpc to derive its parameters and measure the magnitude of its flare. Methods. We obtained the 3D density of stars of ...type F8V-G5V with a colour selection from extinction-corrected photometric data of the Sloan Digital Sky Survey – Sloan Extension for Galactic Understanding and Exploration (SDSS-SEGUE) over 1400 deg2 in off-plane low Galactic latitude regions and fitted it to a model of flared thin+thick disc. Results. The best-fit parameters are a thin-disc scale length of 2.0 kpc, a thin-disc scale height at solar Galactocentric distance of 0.24 kpc, a thick-disc scale length of 2.5 kpc, and a thick-disc scale height at solar Galactocentric distance of 0.71 kpc. We derive a flaring in both discs that causes the scale height of the average disc to be multiplied with respect to the solar neighbourhood value by a factor of 3.3+2.2-1.6 at R = 15 kpc and by a factor of 12+20-7 at R = 25 kpc. Conclusions. The flare is quite prominent at large R and its presence explains the apparent depletion of in-plane stars that are often confused with a cut-off at R ≳ 15 kpc. Indeed, our Galactic disc does not present a truncation or abrupt fall-off there, but the stars are spread in off-plane regions, even at z of several kpc for R ≳ 20 kpc. Moreover, the smoothness of the observed stellar distribution also suggests that there is a continuous structure and not a combination of a Galactic disc plus some other substructure or extragalactic component: the hypothesis to interpret the Monoceros ring in terms of a tidal stream of a putative accreted dwarf galaxy is not only unnecessary because the observed flare explains the overdensity in the Monoceros ring observed in SDSS fields, but it appears to be inappropriate.
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