We perform the first global fit to inclusive B → Xsγ measurements using a model-independent treatment of the nonperturbative b-quark distribution function, with next-to-next-to-leading logarithmic ...resummation and ... fixed-order contributions. The normalization of the ... decay rate, given ... is sensitive to physics beyond the standard model (SM). We determine ... in good agreement with the SM prediction, and the b-quark mas ... Our results suggest that the uncertainties in the extracted ... rate have been underestimated by up to a factor of 2, leaving more room for beyond-SM contributions.(ProQuest: ... denotes formulae omitted.)
Full text
Available for:
CMK, CTK, FMFMET, NUK, UL
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).A combination is presented of all inclusive deep inelastic cross sections previously published by the H1 and ZEUS ...collaborations at HERA for neutral and charged current ... scattering for zero beam polarisation. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV. The data correspond to an integrated luminosity of about 1 fb... and span six orders of magnitude in negative four-momentum-transfer squared, ..., and Bjorken x. The correlations of the systematic uncertainties were evaluated and taken into account for the combination. The combined cross sections were input to QCD analyses at leading order, next-to-leading order and at next-to-next-to-leading order, providing a new set of parton distribution functions, called HERAPDF2.0. In addition to the experimental uncertainties, model and parameterisation uncertainties were assessed for these parton distribution functions. Variants of HERAPDF2.0 with an alternative gluon parameterisation, HERAPDF2.0AG, and using fixed-flavour-number schemes, HERAPDF2.0FF, are presented. The analysis was extended by including HERA data on charm and jet production, resulting in the variant HERAPDF2.0Jets. The inclusion of jet-production cross sections made a simultaneous determination of these parton distributions and the strong coupling constant possible, resulting in ... An extraction of ... and results on electroweak unification and scaling violations are also presented.
Abstract
We report the discovery of a candidate galaxy with a photo-
z
of
z
∼ 12 in the first epoch of the James Webb Space Telescope (JWST) Cosmic Evolution Early Release Science Survey. Following ...conservative selection criteria, we identify a source with a robust
z
phot
=
11.8
−
0.2
+
0.3
(1
σ
uncertainty) with
m
F200W
= 27.3 and ≳7
σ
detections in five filters. The source is not detected at
λ
< 1.4
μ
m in deep imaging from both Hubble Space Telescope (HST) and JWST and has faint ∼3
σ
detections in JWST F150W and HST F160W, which signal a Ly
α
break near the red edge of both filters, implying
z
∼ 12. This object (Maisie’s Galaxy) exhibits F115W − F200W > 1.9 mag (2
σ
lower limit) with a blue continuum slope, resulting in 99.6% of the photo-
z
probability distribution function favoring
z
> 11. All data-quality images show no artifacts at the candidate’s position, and independent analyses consistently find a strong preference for
z
> 11. Its colors are inconsistent with Galactic stars, and it is resolved (
r
h
= 340 ± 14 pc). Maisie’s Galaxy has log
M
*
/
M
⊙
∼ 8.5 and is highly star-forming (log sSFR ∼ −8.2 yr
−1
), with a blue rest-UV color (
β
∼ −2.5) indicating little dust, though not extremely low metallicity. While the presence of this source is in tension with most predictions, it agrees with empirical extrapolations assuming UV luminosity functions that smoothly decline with increasing redshift. Should follow-up spectroscopy validate this redshift, our universe was already aglow with galaxies less than 400 Myr after the Big Bang.
Ingredients for 21 cm Intensity Mapping Villaescusa-Navarro, Francisco; Genel, Shy; Castorina, Emanuele ...
The Astrophysical journal,
10/2018, Volume:
866, Issue:
2
Journal Article
Peer reviewed
Open access
Current and upcoming radio telescopes will map the spatial distribution of cosmic neutral hydrogen (H i) through its 21 cm emission. In order to extract the maximum information from these surveys, ...accurate theoretical predictions are needed. We study the abundance and clustering properties of H i at redshifts z ≤ 5 using TNG100, a large state-of-the-art magnetohydrodynamic simulation of a 75 h−1 Mpc box size, which is part of the IllustrisTNG Project. We show that most of the H i lies within dark matter halos, and we provide fits for the halo H i mass function, i.e., the mean H i mass hosted by a halo of mass M at redshift z. We find that only halos with circular velocities larger than 30 km s−1 contain H i. While the density profiles of H i exhibit a large halo-to-halo scatter, the mean profiles are universal across mass and redshift. The H i in low-mass halos is mostly located in the central galaxy, while in massive halos the H i is concentrated in the satellites. Our simulation reproduces the bias value of damped Ly systems from observations. We show that the H i and matter density probability distribution functions differ significantly. Our results point out that for small halos, the H i bulk velocity goes in the same direction and has the same magnitude as the halo peculiar velocity, while in large halos, differences show up. We find that halo H i velocity dispersion follows a power law with halo mass. We find a complicated H i bias, with H i already becoming nonlinear at k = 0.3 h Mpc−1 at z 3. The clustering of H i can, however, be accurately reproduced by perturbative methods. We find a new secondary bias by showing that the clustering of halos depends not only on mass but also on H i content. We compute the amplitude of the H i shot noise and find that it is small at all redshifts, verifying the robustness of BAO measurements with 21 cm intensity mapping. We study the clustering of H i in redshift space and show that linear theory can explain the ratio between the monopoles in redshift and real space down to 0.3, 0.5, and 1 h Mpc−1 at redshifts 3, 4, and 5, respectively. We find that the amplitude of the Fingers-of-God effect is larger for H i than for matter, since H i is found only in halos above a certain mass. We point out that 21 cm maps can be created from N-body simulations rather than full hydrodynamic simulations. Modeling the one-halo term is crucial for achieving percent accuracy with respect to a full hydrodynamic treatment. Although our results are not converged against resolution, they are, however, very useful as we work at the resolution where the model parameters have been calibrated to reproduce galaxy properties.
PDF
