1. Muons from the decay of charmed baryons/antibaryons
Olga Piskounova
<P.N.Lebedev Physical Institute>
and Nikolai Nikitine
<Skobeltsyn Institute of Moscow State Univ.>,
Moscow

2. Plan Multiparticle production in the Quark-Gluon string model
Spectra of Lc and antiLc in the recent experiments
Procedure of spectra transformation into the laboratory system
Charm decay calculations
Lorentz boost and MC code
Resulting muon spectra and asymmetry
Summary
O.Piskounova

3. Quark-Gluon String Model
QGSM is based on N-Pomeron exchange disgrams that lead to 2N quark-antiquark chains.
Multiparticle production cross section are growing with the energy as:
sN(k)=sP (1-e-zSN-1(zk/k!))/Nz
where sP=8pgP(0)eD, =ln(s/s0),
z=3gP(0)exD/(R 2+a’P(0)x).
O.Piskounova

4. Baryon production distributions
Inclusive production cross section of hadrons H is written as a sum over N-Pomeron cylinder diagrams:
Distribution functions of Lc in p-p collisions are given by:

5. Spectra of charmed baryons in pp
E781(SELEX) √s=34GeV
∆ - Λc spectrum
▼- antiΛc
O.Piskounova

6. Transition to lab. system
E0=10000GeV
xds/dx=ds/dyc.m.s.=ds/dy lab.s.
ds/dEL = EL-1ds/dyc.m.s(E0,mLc,EL)
The procedure has been applied to calculations of antiproton spectra and gamma spectra from cosmic sources:
O.I.Piskounova Antiprotons in cosmic rays: quark-gluon string model approach.
Yad.Fiz.,47 (1988)749
O.I.Piskounova About the shape of photon spectra from proton cosmic sources of high energy.
Yad.Fiz.,51 (1990)1332
O.Piskounova

7. Description of the decay Λc Xs+ m +nm
This decay is described
at partonic level:
c → s m nm
All calculations are similar to the calculations in the book L.B.Okun “Leptons and quarks”, 1981.

8. Decay width and probability
The differential decay width for c → s m nm transition:
For the MC simulation the normalized matrix element
is used:

9. Initial momentum configuration

10. MC procedure Nm=0 Generating of s,t pair, calculating of w(s,t)
Accepting if rmdm(-1)<w(s,t) in (s,t)-physical area
Vector calculation: p1,k1,k2 in rest frame of c-quark
Random rotation:
Lorentz boost in Λc moving system
Recording of event: Nm=Nm+1

11. Resulting spectra of m+ and m-
Muon spectra are following to the spectra of c.
Muon charge symmetry is reproducing the leading asymmetry of charmed baryon spectra.

12. Asymmetry
E0 = 10 5; 10 6 GeV
A= (N+- N-) / (N+ + N-)
O.Piskounova

13. Conclusions O.Piskounova Spectra of all baryons in pp interaction of
high energy have a specific form: “knee” at
EL close to m, “shoulder” at EL=0.1E0 and
the slope of order E-1 in between;
Asymmetry between + and - is of the same form as leading asymmetry between the spectra of c/antic;
This generator can be used for the calculation of spectra of muons and neutrino in b decays as well.
O.Piskounova