GENXICC2.0: An upgraded version of the generator for hadronic production of double heavy baryons ΞccΞcc, ΞbcΞbc and ΞbbΞbb

Department of Physics, Chongqing University, Chongqing 400044, China; CCAST (World Laboratory), P.O. Box 8730, Beijing 100190, China; Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190, China; Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918(4), Beijing 100049, PR China
Computer Physics Communications (Impact Factor: 2.41). 06/2010; 181(6):1144-1149. DOI: 10.1016/j.cpc.2010.02.008
Source: DBLP

ABSTRACT An upgraded (second) version of the package GENXICC ({\bf A Generator for Hadronic Production of the Double Heavy Baryons $\Xi_{cc}$, $\Xi_{bc}$ and $\Xi_{bb}$ by C.H. Chang, J.X. Wang and X.G. Wu,} [its first version: in Comput. Phys. Commun. {\bf 177} (2007) 467-478]) is presented. Users, with this version being implemented in PYTHIA and a GNU C compiler, may simulate full events of the production in various experimental environments conveniently. In comparison with the previous version, in order to implement it in PYTHIA properly, a subprogram for the fragmentation of the produced double heavy diquark to the relevant baryon is complemented and the interphase of the generator to PYTHIA is changed accordingly. In the subprogram, with explanation, certain necessary assumptions (approximations) are made so as to conserve the momenta and the QCD `color' flow for the fragmentation. Comment: 15 pages, 2 figures

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    ABSTRACT: We present a detailed discussion on the hadronic production of $\Xi_{cc}$ at a fixed target experiment at the LHC (After@LHC). It is produced via the channel ${\rm Proton} + {\rm Proton}\to\Xi_{cc}+X$, whose subprocesses include $g+g\to \Xi_{cc} +\bar{c} +\bar{c}$, $g+c\to \Xi_{cc}+\bar{c}$, and $c+c\to \Xi_{cc}+g$. The $\Xi_{cc}$ can be produced via a binding diquark first and then by grabbing soft light-quarks or gluons. Both two diquark configurations $(cc)[^3S_1]_{\bf\bar 3}$ and $(cc)[^1S_0]_{\bf 6}$ have sizable contributions to $\Xi_{cc}$ production. We show that large number of $\Xi_{cc}$ events can be generated at the After@LHC, whose total production cross section is larger than that of SELEX by about thirty-five times. It is even possible to study the properties of $\Xi_{bc}$. That is, about $8.3 \times 10^6$ $\Xi_{cc}$ events/year and $1.8 \times 10^4$ $\Xi_{bc}$ events/year can be generated when the integrated luminosity equals $2$ fb$^{-1}$/year. Thus, in addition to the hadronic experiments SELEX and LHC itself, the After@LHC can also provide a useful platform for studying the baryon properties and has its own advantages.
    Physical Review D 01/2014; 89(7). · 4.86 Impact Factor
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    ABSTRACT: The production of the heavy charmonium and $(c\bar{b})$-quarkonium, through the top quark semi-exclusive decays via the flavor changing neutral currents (FCNC), has been systematically studied within the non-relativistic QCD. In different to the conventional squared amplitude approach, to simplify the results as much as possible, we adopt the `improved trace technology' to do our calculation, which deals with the hard scattering directly at the amplitude level. If assuming the higher excited heavy-quarkonium states, such as the color-singlet and spin-triplet $S$-wave state $|[^3S_1]_{\bf 1}\rangle$, the color-singlet $P$-wave states $|[^1P_1]_{\bf 1}\rangle$ and $|[^3P_J]_{\bf 1}\rangle$ (with $J=0,1,2$), and the two color-octet components $|[^1S_0]_{\bf 8}g\rangle$ and $|[^3S_1]_{\bf 8}g\rangle$, decay to the ground color-singlet and spin-singlet $S$-wave state $|[^1S_0]_{\bf 1}\rangle$ with 100% efficiency via the electromagnetic or hadronic radiations, we obtain the total decay width: $\Gamma_{t\to |(c\bar{c})[^1S_0]_{\bf 1}\rangle} = 171.1^{+147.7}_{-68.8}$ KeV and $\Gamma_{t\to |(c\bar{b})[^1S_0]_{\bf 1}\rangle} =7.32^{+2.49}_{-1.75}$ KeV, where the uncertainties are caused by varying $m_t=172.0\pm4.0$ GeV, $m_b=4.90\pm0.40$ GeV and $m_c=1.50\pm0.25$ GeV. At the LHC with the center-of-mass energy $\sqrt{S}=14$ TeV and a high luminosity ${\cal L}\propto 10^{34}{\rm cm}^{-2}{\rm s}^{-1}$, sizable heavy-quarkonium events can be produced through the top quark decays via FCNC.
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    ABSTRACT: We report a search for the doubly charmed baryon $\Xi_{cc}^{+}$ through the decay $\Xi_{cc}^{+} \to \Lambda_{c}^{+} K^{-} \pi^{+}$, using a data sample corresponding to an integrated luminosity of $0.65~\mathrm{pb^{-1}}$ of $pp$ collisions at $\mathrm{\sqrt{s}} = 7~\mathrm{TeV}$. In the mass range 3300-3800$~\mathrm{MeV}/c^{2}$ no significant signal is observed. Upper limits at $95\%$ confidence level are set on $R$, the ratio of the production cross section of the $\Xi_{cc}^{+}$ times the relevant branching fraction over the $\Lambda_{c}^{+}$ cross section, as a function of the $\Xi_{cc}^{+}$ mass and lifetime. The largest upper limits on $R$ over the investigated mass range are $R<1.5\times10^{-2}$ for a lifetime of $100~\mathrm{fs}$ and $R<3.9\times10^{-4}$ for a lifetime of $400~\mathrm{fs}$.

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