6533b853fe1ef96bd12ac894

RESEARCH PRODUCT

D-meson production according to the parton model and their detection in ALICE

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description

Modern understanding in particle physics is constructed over lay- ers and layers of work. Most of the work was done during last century, starting from the quantum mechanics. Modern theoretical basis is the parton model, which is constructed from three independent parts: distribution of momentum to partons inside hadron, partonic cross-sections from QCD and from fragmentation of parton to hadrons. All of these parts are discussed in this work. Future experiments are aiming for higher energies and/or greater number of intresting events than what previous experiments were capable to gain. Main example of this is LHC and ALICE-experiment on it in CERN. While simulations have benefited greatly from fast increase of computing power during last few decades. With the following assumptions, p$_t$ $>$ 1 GeV, fixed QCD scale Q = 5 GeV, massless quarks and only gluon-gluon channel in partonic cross-section and $\delta$-function fragmentation, the lowest order simulations for production of D-meson with midrapidity y = 0 and rapidity interval $\Delta$y = 1 at proton-proton collision predicts that 51% of D$^0$ and 76% of D$^+$ decay at transverse distance l $>$ 60 $\mu$m from the main interaction point and thus ALICE is capable of detecting them from reconstructed tracks of their decay products. With same assumptions production rate of D-mesons in prime interaction in ALICE is 108,000,000 in one hour. 3/4 of them are on excited states D$^*$ and of the rest half are charged D$^+$-mesons and half are neutral D$^0$- mesons. This sums up into 6,890,000 D$^0$ and 10,300,000 D$^+$ events from primary D-mesons are available to detection in one hour of op- eration in LHC.