Λc+/Λc−and

Wai Kin Lai

¹

,

Adam K. Leibovich

²

Observation of a $$ {\varLambda}_b^0 $$ − $$ {\overline{\varLambda}}_b^0 $$ production asymmetry in proton-proton collisions at $$ \sqrt{s} $$ = 7 and 8 TeV

“…(6.7). The coefficients C sim | p| are determined with simulation in momentum ranges of [5,15], [15,30] and [30,75] GeV/c to be 0.91 ± 0.02, 0.85 ± 0.02 and 0.73 ± 0.05. Using the proton momentum and the last hit JHEP10(2021)060 of the proton track in the VELO, the path of the proton through the detector is determined and the expected proton-interaction asymmetry is calculated according to eq.…”

Forward-backward asymmetries of $(B^-, B^+)$, $(\Lambda_b, \bar\Lambda_b)$ and $(\Lambda,\bar\Lambda)$ in $p\bar p$ collisions at D0

“…Figure 3 shows the reconstructed Λ b mass in the rapidity range 0.5 < |y| < 1.0 for both the forward and backward definitions along with a fit to the data. Figure 4 shows the measured asymmetry as a function of rapidity compared to a Heavy Quark Recombination model [8] and a simulation showing the effects of the "beam drag" effect. Integrating over rapidity yields a forward backward asymmetry of A FB =0.04 ± 0.07(stat.)…”

Forward-Backward asymmetry in $\Lambda_{b}$ production and search for the $\Xi^{-}_{b}$ and $\Omega^{-}_{b}$ baryons in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV

“…predictions of the Heavy Quark Recombination model [43] and a simulated effect of the longitudinal momentum shift due to beam drag (see Ref [31] and text). The background asymmetry is obtained from J/ψΛ candidates in the Λ 0 b mass sidebands (uncertainties are small compared to the symbol size).…”

“…There is a wide range of model predictions for this asymmetry. The "Heavy Quark Recombination" (HQR) model [43], as shown in Figure 6.6, predicts a modest asymmetry, reaching ∼ 2.5% near y = 2. While Pythia predicts no asymmetry, the MC@NLO generator predicts a large asymmetry, reaching 100% near y = 2.…”

“…Such an asymmetry would result from clusters formed by a b quark and ud diquarks having a small mass, just sufficient to coalesce into a single particle. The asymmetry integrated over rapidity is A = 0.04 ± 0.06 ± 0.02 .6: Measured forward-backward asymmetry A versus rapidity |y| compared to predictions of the Heavy Quark Recombination model [43] and a simulated effect of the longitudinal momentum shift due to beam drag (see Ref [31] and text). The background asymmetry is obtained from J/ψΛ candidates in the Λ 0 b mass sidebands (uncertainties are small compared to the symbol size).…”