Measurement of prompt hadron production ratios in pp collisions at $\sqrt{s} = 0.9\mbox{ and }7~\mathrm{TeV}$

Abstract

The charged-particle production ratiosp/p,are measured with the LHCb detector using 0.3 nb −1 of pp collisions delivered by the LHC at √ s = 0.9 TeV and 1.8 nb −1 at √ s = 7 TeV. The measurements are performed as a function of transverse momentum p T and pseudorapidity η. The production ratios are compared to the predictions of several Monte Carlo generator settings, none of which are able to describe adequately all observables. The ratiop/p is also considered as a function of rapidity loss, y ≡ y beam − y, and is used to constrain models of baryon transport.

Hadronic interaction model sibyll2.3cand inclusive lepton fluxes

“…The open-source software Matrix Cascade Equations (MCEq) 1 [43] solves the system of discrete coupled cascade equations…”

“…5.4). LHCb [1], the detector that provides particle identification with the largest rapidity coverage at the LHC, only covers a small region of longitudinal phase space x F 0.1 and therefore can not constrain the leading charge ratios. In a proposed fixed target configuration for LHCb [67,91], the charge ratios in the forward region could be determined for √ s = 104 GeV.…”

Probing collective effects in hadronisation with the extremes of the underlying event

“…Starting from Rick Field's observation with his "Tune A" [34] of the PYTHIA 6 MPI model [35,36] to Tevatron data [10] that a much higher degree of colour correlation than anticipated (between partons from different MPI systems) was required to fit the p ⊥ spectra of particles in the UE at CDF, there have appeared progressively more indications that the physics of hadron collisions is more complicated than was previously thought. The clues include the increase of the average p ⊥ with event multiplicity [35,[37][38][39][40][41][42], the large yields of hyperons [43][44][45][46][47][48][49][50], and the overall relatively steep increase of average p ⊥ with hadron mass [45,46,[49][50][51][52][53][54] observed in pp collisions. There are also more subtle indications, such as the unexpected ridge-like structure in two-particle correlations at low ∆φ in high-multiplicity minimum-bias pp collisions observed by CMS and ATLAS [55,56].…”

Measurement of Antiproton Production in p−He Collisions at sNN=110 Aaij1, Beteta2, Adeva3 et al. 2018Phys. Rev. Lett.Self Cite601600View full textAdd to dashboardCite

“…Two methods are used to determine thep fraction in each kinematic bin: a two-dimensional binned extended-maximum-likelihood fit, illustrated in Fig. 1, and a cut-and-count method [24], which uses exclusive high-purity samples selected with tight requirements for each particle species. The probability P ij that a candidate of species i is classified as species j is obtained from the templates.…”