Measurement of neutral mesons inp+pcollisions ats=200  GeVand scaling properties of hadron production

Abstract

The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the invariant differential cross section for production of K 0 S , ω, η ′ , and φ mesons in p + p collisions at √ s = 200 GeV. Measurements of ω and φ production in different decay channels give consistent results. New results for the ω are in agreement with previously published data and extend the measured pT coverage. The spectral shapes of all hadron transverse momentum distributions measured by PHENIX are well described by a Tsallis distribution functional form with only two parameters, n and T , determining the high-pT and characterizing the low-pT regions of the spectra, respectively. The values of these parameters are very similar for all analyzed meson spectra, but with a lower parameter T extracted for protons. The integrated invariant cross sections calculated from the fitted distributions are found to be consistent with existing measurements and with statistical model predictions.

Lateral distribution of muons in IceCube cosmic ray events

“…Sibyll 2.1 generates particle p T using two approaches [20]. In soft (low p T ) interactions, quark-antiquark pairs are given a p T that follows a Gaussian distribution, with a mean of 0.3, 0.45, or 0:6 þ 0:08log 10 ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi s=ð30 GeVÞ p GeV, for light quarks, strange quarks, and diquarks respectively; diquarks lead to the production of baryons. Hard interactions are simulated using lowest order pQCD, with the Glück-Reya-Vogt structure functions, including a saturation correction.…”

“…At low p T the spectrum follows expðÀp T =TÞ, with T % 220 MeV=c for pions (somewhat higher for kaons and protons) [10]. At higher p T , the spectrum falls as 1=ð1 þ p T =p 0 Þ n , where one fit found n ¼ 13:0 þ1:0 À0:5 and p 0 ¼ 1:9 þ0:2 À0:1 GeV=c [11].…”

Measurement of transverse energy at midrapidity in Pb-Pb collisions atsNN=2.76TeV

“…To calculate the contribution from the η meson and its uncertainties, we assume that the shapes of its spectra for all centrality bins as a function of transverse mass are the same as the pion spectra, using the transverse mass scaling [53], and that the η/π ratio is independent of the collision system, as observed by PHENIX [54]. We also consider a scenario where the η spectrum is assumed to have the same shape as the kaon spectrum, as would be expected if the shape of the η spectrum was determined by hydrodynamical flow.…”

Nonextensive statistical mechanics and high energy physics

“…In high-energy physics there is a plethora of applications as well ( [52][53][54][55][56][57][58][59][60][61][62][63][64][65] among many others). A remarkable recent example is shown in Fig.…”