Charm production in SIBYLL

TL;DR

An improved release (2.3rc1) of SIBYLL is presented, tuned to LHC data and extended to include charm production. It covers cross-section refits, enhanced baryon production, and PDF updates (GRV) affecting minijet dynamics, alongside a new charm quark extension with both perturbative and non-perturbative components. The perturbative channel uses $g g \rightarrow c\bar{c}$ with a charm fraction $P^{i}_{c\bar{c}} = P^{i}_{c,0} \exp(- m_{ m eff}/\hat{s})$ and an effective mass scale $m_{ m eff}=20\,\mathrm{GeV}^2$, while the non-perturbative component attaches charm to soft strings to capture forward production. The model is tuned to ALICE and LHCb central data and compared to perturbative benchmarks like the MRS calculation, with implications for atmospheric muon and neutrino flux predictions and plans to quantify forward-charm uncertainties in future work.

Abstract

SIBYLL 2.1 is an event generator for hadron interactions at the highest energies. It is commonly used to analyze and interpret extensive air shower measurements. In light of the first detection of PeV neutrinos by the IceCube collaboration the inclusive fluxes of muons and neutrinos in the atmosphere have become very important. Predicting these fluxes requires understanding of the hadronic production of charmed particles since these contribute significantly to the fluxes at high energy through their prompt decay. We will present an updated version of SIBYLL that has been tuned to describe LHC data and extended to include the production of charmed hadrons.

Figures (9)

• Figure 1: Inelastic $p$-$p$ cross section in SIBYLL. The updated cross section is shown in blue, the old version is in black. The red squares are the measurements by TOTEM Antchev:2011vs. The black diamond at the highest energy is the estimate from the Auger Observatory Auger:2012wtAbraham:2004dt. The second energy axis shows the equivalent laboratory energy for $p$-$p$ interactions as applicable to air shower detectors (one proton at rest). The measurement ranges of the IceTop air shower array IceCube:2012nn and the Pierre Auger Observatory Abraham:2004dt are indicated by black lines.
• Figure 2: Average antiproton multiplicity as a function of center-of-mass energy. The low energy data are a compilation of fixed target and ISR experiments that cover the full phase space or were extrapolated to full phase space Antinucci73. The CMS data Chatrchyan:2012qb are taken in a phase space region with $|y|<1.0$. PHENIX Adare:2011vy data are taken in the range $|\eta|<0.35$. The prediction by the models are shown for the full and CMS phase spaces only. SIBYLL 2.1 is shown as dashed line, the updated version as solid line.
• Figure 3: Inclusive cross section for charged particles as function of the transverse momentum. The results obtained with the old and new versions of SIBYLL are compared with CMS data at different c.m. energies Khachatryan:2010xsKhachatryan:2010us.
• Figure 4: Pseudorapidity distribution of charged particles. The data are from NA22 Adamus:1988xc,UA5 Alner:1986xu,CDF Abe:1989td and CMS Khachatryan:2010us. The prediction by SIBYLL 2.1 is shown by the dashed line, the one for the updated model by the solid line.
• Figure 5: Inclusive charm and $D$-meson cross sections as a function of c.m. energy. The data at low energy are $D$-meson cross sections in fixed target experiments Alves:1996rzAguilarBenitez:1988sbAmmar:1988taZoccoli:2005yn. The measurements at the highest energies are $c\bar{c}$ from ALICE Abelev:2012vraALICE:2011aa. Here data are shown extrapolated to full phase space (red circles) and visible only (blue empty squares). At intermediate energies the data taken at RHIC by the STAR Adamczyk:2012af and PHENIX Adare:2010de experiments are shown (also extrapolated). The model prediction for the inclusive $c\bar{c}$ cross section is shown by the solid line, the prediction for the production of $D$-mesons is shown by the dotted line.