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Register a new userOpen charm production in binary reactions within the Regge theory
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We analyze the open charm production in the binary $pi p to bar{D} Lambda_c$ and $pi(rho) J/psi$ reactions within the Regge theory including the absorption corrections. The calculations show that the total cross section is about a few $mu$b for the first processes and a few mb for the second reactions at energy close to the threshold. Then it decreases with increasing energy according to the true Regge asymptotics.
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The processes of dielectron production in deuteron-proton collisions at intermediate incident deuteron beam energies are analyzed in the spectator model within the one-pion exchange reggeized approach. We focus mainly on the momentum and angle distributions of the proton-spectator and the proton emitted in quasi-free $NN$ processes at small angles in the laboratory frame. It is shown that the inclusion of many channels in quasi-free $NN$ interaction allows us to describe the HADES data quite satisfactorily at incident deuteron kinetic energies of about 2.5 GeV.
The mass modifications of the open charm ($D$ and $D^*$) mesons, and their effects on the decay widths $D^*rightarrow Dpi$ as well as of the charmonium state, $Psi(3770)$ to open charm mesons ($Psi(3770)rightarrow Dbar D$), are investigated in the presence of strong magnetic fields. These are studied accounting for the mixing of the pseudoscalar ($P$) and vector ($V$) mesons ($D-D^*$, $eta_c-Psi(3770)$ mixings), with the mixing parameter, $g_{PV}$ of a phenomenological three-point ($PVgamma$) vertex interaction determined from the observed radiative decay width of $Vrightarrow Pgamma$. For charged $D-D^*$ mixing, this parameter is dependent on the magnetic field, because of the Landau level contributions to the vacuum masses of these mesons. The masses of the charged $D$ and $D^*$ mesons modified due to $PV$ mixing, in addition, have contributions from the lowest Landau levels in the presence of a strong magnetic field. The effects of the magnetic field on the decay widths are studied using a field theoretic model of composite hadrons with quark (and antiquark) consittuents. The parameter for the charged $D-D^*$ mixing is observed to increase appreciably with increase in the magnetic field. This leads to dominant modifications to their masses, and hence the decay widths of charged $D^*rightarrow Dpi$ as well as $Psi(3770)rightarrow D^+D^-$ at large values of the magnetic field. The modifications of the masses and decay widths of the open and hidden charm mesons in the presence of strong magnetic fields should have observable consequences on the production of the open charm ($D$ and $D^*$) mesons as well as of the charmonium states resulting from non-central ultrarelativistic heavy ion collision experiments.
In this note we provide a detailed derivation of the kinematic limit of the charm production in fixed-target experiments with the intrinsic charm coming from the target. In addition, we discuss the first measurement of charm quark production in the fixed-target configuration at the LHC.
We investigate the in-medium masses of open charm mesons ($D$($D^0$, $D^+$), $bar{D}$($bar{D^0}$, $D^-$), $D_s$(${D_{s}}^+$, ${D_{s}}^-$)) and charmonium states ($J/psi$, $psi(3686)$, $psi(3770)$, $chi_{c0}$, $chi_{c2}$) in strongly magnetized isospin asymmetric strange hadronic matter using a chiral effective model. In the presence of the magnetic field, the number density and scalar density of charged baryons have contributions from Landau energy levels. The mass modifications of open charm mesons arise due to their interactions with nucleons, hyperons, and the scalar fields (the non-strange field $sigma$, strange field $zeta$ and isovector field $delta$) in the presence of the magnetic field. The mass modifications of the charmonium states arise from the variation of dilaton field ($chi$) in the magnetized medium, which simulates the gluon condensates of QCD. The in-medium mass of open charm mesons and charmonia are observed to decrease with an increase in baryon density, whereas the charged $D^+$, $D^-$, ${D_{s}}^+$ and ${D_{s}}^-$ mesons have additional positive mass shifts due to Landau quantization in the presence of the magnetic field. The effects of strangeness fraction are found to be more dominant for the $bar{D}$ mesons as compared to the $D$ mesons. The mass shifts of charmonia are observed to be larger in hyperonic medium compared to the nuclear medium.
We calculate the rate of double open charm production in the forward kinematics studied recently in the LHCb experiment. We find that the mean field approximation for the double parton GPD (Generalized parton distributions), which neglects parton - parton correlations, underestimates the rate by a factor of two. The enhancement due to the perturbative QCD correlation 12 mechanism which explains the rate of double parton interactions at the central rapidities is found to explain 60 $div$ 80 % of the discrepancy. We argue that the nonperturbative fluctuations leading to non-factorized (correlated) contributions to the initial conditions for the DGLAP collinear evolution of the double parton GPD play an important role in this kinematics. Combined, the two correlation mechanisms provide a good description of the rate of double charm production reported by the LHCb. We also give predictions for the variation of the effs (i.e. the ratio of double and square of single inclusive rates) in the discussed kinematics as a function of $p_t$. The account for two correlation mechanisms strongly reduces sensitivity of the results to the starting point of the QCD evolution.
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