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Measurement of groomed jet substructure observables in p+p collisions at √s = 200 GeV with STAR
(2020)
In this letter, measurements of the shared momentum fraction (zg) and the groomed jet radius (Rg), as defined in the SoftDrop algorithm, are reported in p+p collisions at √s = 200 GeV collected by the STAR experiment. These substructure observables are differentially measured for jets of varying resolution parameters from R = 0.2 − 0.6 in the transverse momentum range 15 < pT,jet < 60 GeV/c. These studies show that, in the pT,jet range accessible at √s = 200 GeV and with increasing jet resolution parameter and jet transverse momentum, the zg distribution asymptotically converges to the DGLAP splitting kernel for a quark radiating a gluon. The groomed jet radius measurements reflect a momentum-dependent narrowing of the jet structure for jets of a given resolution parameter, i.e., the larger the pT,jet, the narrower the first splitting. For the first time, these fully corrected measurements are compared to Monte Carlo generators with leading order QCD matrix elements and leading log in the parton shower, and to state-of-the-art theoretical calculations at next-to-leading-log accuracy. We observe that PYTHIA 6 with parameters tuned to reproduce RHIC measurements is able to quantitatively describe data, whereas PYTHIA 8 and HERWIG 7, tuned to reproduce LHC data, are unable to provide a simultaneous description of both zg and Rg, resulting in opportunities for fine parameter tuning of these models for p+p collisions at RHIC energies. We also find that the theoretical calculations without non-perturbative corrections are able to qualitatively describe the trend in data for jets of large resolution parameters at high pT,jet, but fail at small jet resolution parameters and low jet transverse momenta.
Investigation of the linear and mode-coupled flow harmonics in Au+Au collisions at √sNN = 200 GeV
(2020)
Flow harmonics (vn) of the Fourier expansion for the azimuthal distributions of hadrons are commonly employed to quantify the azimuthal anisotropy of particle production relative to the collision symmetry planes. While lower order Fourier coefficients (v2 and v3) are more directly related to the corresponding eccentricities of the initial state, the higher-order flow harmonics (vn>3) can be induced by a modecoupled response to the lower-order anisotropies, in addition to a linear response to the same-order anisotropies. These higher-order flow harmonics and their linear and mode-coupled contributions can be used to more precisely constrain the initial conditions and the transport properties of the medium in theoretical models. The multiparticle azimuthal cumulant method is used to measure the linear and mode-coupled contributions in the higher-order anisotropic flow, the mode-coupled response coefficients, and the correlations of the event plane angles for charged particles as functions of centrality and transverse momentum in Au+Au collisions at nucleon-nucleon center-of-mass energy √sN N= 200 GeV. The results are compared to similar LHC measurements as well as to several viscous hydrodynamic calculations with varying initial conditions.
We report results on the total and elastic cross sections in proton-proton collisions at √s = 200 GeV obtained with the Roman Pot setup of the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The elastic differential cross section was measured in the squared four-momentum transfer range 0.045 ≤ −t ≤ 0.135 GeV2. The value of the exponential slope parameter B of the elastic differential cross section dσ/dt ∼ e−Bt in the measured −t range was found to be B = 14.32 ± 0.09(stat.)+0.13 −0.28(syst.) GeV−2. The total cross section σtot, obtained from extrapolation of the dσ/dt to the optical point at −t = 0, is σtot = 54.67 ± 0.21(stat.)+1.28 −1.38(syst.) mb. We also present the values of the elastic cross section σel = 10.85 ± 0.03(stat.)+0..49 −0.41(syst.) mb, the elastic cross section integrated within the STAR t-range σ det el = 4.05 ± 0.01(stat.)+0.18−0.17(syst.) mb, and the inelastic cross section σinel = 43.82 ± 0.21(stat.)+1.37−1.44(syst.) mb. The results are compared with the world data
In 2017, a new project was begun to assess the biodiversity of national parks and forest reserves in the Republic of Panama. Designated “Proyecto Sistema de Producción Sostenible Conservación de la Biodiversidad (PSPSCB)”, this project is managed by Panama’s Ministerio de Ambiente. The first park sampled in 2017 was Omar Torrijos Herrera National Park (OTHNP). Trichoptera (Insecta) were collected at four locations using both Malaise traps and UV light traps. The rugged terrain and lack of access in this remote park limited the sampled area. Sampling included streams in both the Caribbean and Pacific drainages. Seven new species of microcaddisflies (Hydroptilidae: Alistotrichia coclensis Armitage and Harris, Cerasmatrichia akanthos Armitage and Harris, Metrichia corazones Armitage and Harris, Neotrichia espinosa Armitage and Harris, Neotrichia michaeli Armitage and Harris, Neotrichia pierpointorum Armitage and Harris, and Neotrichia yayas Armitage and Harris) and one new country record, Metrichia macrophallata Flint, were identified from this preliminary survey and are reported herein. Other recently described species are reported here for the first time outside of their type localities. Based on other areas more extensively sampled compared to this modest survey, many more new species and new country records await discovery in OTHNP as are reported herein. There are now 439 species distributed among 15 families and 55 genera known from Panama.
After publication of Armitage and Harris (2020), it was noticed that the wrong illustrations were used for the species Neotrichia espinosa Armitage and Harris (Fig. 9) and Neotrichia michaeli Armit-age and Harris (Fig. 10), resulting in images that did not correspond to the captions. The authors and the Insecta Mundi editorial staff apologize for this error. The intended versions of Figures 9 and 10 are reproduced here. Insecta Mundi has also released a revised version of the Armitage and Harris (2020) manuscript, with this error corrected. However, the revised version is not an official peer-reviewed article, and anyone wishing to reference the findings of Armitage and Harris (2020) should cite the original manuscript or this erratum.
The Republic of Panama currently includes 414 recorded species of Trichoptera. Herein we add two new genera (Hydroptilidae: Angrisanoia Ozdikmen, 2008 and Mayatrichia Mosely, 1937) and 17 new country records (Philopotamidae: Chimarra (C.) tapanti Blahnik, Wormaldia bolivari Muñoz-Quesada and Holzenthal, and Wormaldia zunigae Muñoz-Quesada and Holzenthal; Hydropsychidae: Centromacronema pygmaeum Botosaneanu; Hydroptilidae: Brysopteryx esparta Harris and Holzenthal, Byrsopteryx solisi Harris and Holzenthal, Costatrichia falsa Santos, Takiya, and Nessimian, Mayatrichia illobia Harris and Holzenthal, Metrichia amplitudinis Bueno-Soria and Holzenthal, Ochrotrichia boquillas Moulton and Harris, O. conformalis Bueno-Soria and Holzenthal, O. quinealensis Bueno-Soria and Holzenthal, and O. unica Bueno-Soria and Santiago; Leptoceridae: Triaenodes morai Holzenthal and Andersen; Odontoceridae: Marilia kingsolveri Bueno-Soria and Rojas-Ascencio; and, Helicopsychidae: Helicopsyche alajuela Johanson and Holzenthal and Helicopsyche breviterga Flint) to Panama’s caddisfly fauna. The newly recorded taxa increase Panama’s total known caddisfly fauna to 431 species, distributed among 15 families and 55 genera. These results are part of an ongoing effort to characterize the caddisfly fauna of Panama, and to evaluate the aquatic insect diversity of the country’s major watersheds (cuencas).