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Signals from ? and f0 in the AliRsn package

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?*(1530) ? p ~100 21 p p/d Au/Au Au 0. ?(782) p p- p0 89 23 p p/d Au 0 ... Only ONE p p- pair from f0. Recommendations for AliRsn: ... – PowerPoint PPT presentation

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Title: Signals from ? and f0 in the AliRsn package


1
Signals from ? and f0 in the AliRsn package
  • Sergey Kiselev, ITEP Moscow for the TOF group
  • Introduction
  • Motivation, Data, Estimations
  • Experience with the AliRsn package
  • Input, output info
  • ? ? KK- , K0? Kp-
  • ? ? pp , ?0 ? pp- , f0 ? pp-
  • ?0 , ?, K0 ? pp-
  • Conclusions and recommendations

2
Introduction
SQM07 short-lived resonances, motivation last
results
channel B.R.() c? (fm) RHIC data ?m
(MeV) ALICE studies
  • a1(1260) ? p ? 0.5 0.5
  • ?0(770) ? p p- 100 1.3
    pp/dA/AuAu -70 pp/AuAu
  • ?(1232) ? p p 100 1.6 pp/dAu
    -40
  • f0(980) ? p p- 66 2.6
    pp/AuAu
  • K(892) ? p K 100 4
    pp/dAu/AuAu -10 pp/AuAu
  • S(1385) ? ? p 88 5.5
    pp/dAu/AuA 0
  • ?(1520) ? p K 45 12.6
    pp/dAu/AuAu 0 pp/AuAu
  • ?(1530) ? ? p 100 21
    pp/dAu/AuAu 0
  • ?(782) ? p p- p0 89 23 pp/dAu
    0
  • ?(782) ? p0? 9 23
    pp/dAu/AuAu 0
  • ?(782) ? p p- 2 23
  • ?(782) ? ee- 7 10-2 23
    pp/dAu/AuAu in prog.
  • F(1020) ? K K- 49 44
    pp/dAu/AuAu 0 pp/AuAu
  • F(1020) ? ee- 3 10-2 44
    pp/dAu/AuAu in prog.

Life Time
3
Introduction ? motivation
P.Fachini SQM07
? ? Mass and Width
PDG
  • ? mass shift observed in both minimum bias pp
    and dAu at vsNN 200 GeV
  • Width agrees with PDG for both systems within
    errors
  • possible explanations p p- rescattering in pp
    collisions, P. Fachini et.al., J.Phys.G33431-440,
    2007

PDG
4
Introduction f0 motivation
A. Badalà- SQM07- Levoca 24/06/-29/06/07
Nuclear Modification Ratios (RCP) for resonances
RHIC results have shown as, in the intermediate
pt region, nuclear modification factors depend on
the constituent quarks rather than on particle
mass.
Recent suggestion by Maiani et al. (Phys. Lett.
B645(2007)138) to use this observable to solve
the problem of the real quark composition of some
resonances as the fo(980)( or
?)
5
RHIC data ?/p, f0 /p- ratios
nucl-ex/0305034
nucl-ex/0403026
?/p 0.20 f0/ p- 0.05
107 min.bias pp events
6
Estimations, SHAKER data ratios (31.03.08
PWG2/ALICE week)
7
AliRsn analysis input info
  • Two Alberto Pulvirentis macros
    AliRsnAnalysis.C, AddRsnAnalysisTask.C for the
    PROOF analysis on CAF
  • Main input values
  • ? 277500 Pythia6 min.bias pp _at_ 10 TeV events
    /COMMON/COMMON/LHC08c11_10TeV_0.5T
  • ? absolute value of the resonance code (e.g.
    2224 for ? and ant- ?, 10221 for f0). !!!
    Pythia6 code, mass, width, could differ from
    PDG ones (e.g. 9010221 for f0). Look at the
    PYTHIA6 particle table in the file
    AliRoot/PYTHIA6/AliDecayerPythia.cxx
  • ? The daughter pair of the resonance (ppi for
    ?, p-pi- for anti-?)
  • ? nMixedEvents 5
  • ? other parameters for tracking, vertex,

8
AliRsn analysis output info
  • Main output
  • 3 types of the invariant mass distribution for
    particle pairs
  • 1. true event pairs, true signal, Strue, from
    Monte-Carlo (MC)
  • - will be fitted by the Breit-Wigner (BW)
    with parameters M0 , G0
  • 2. event pairs, signalsbackgrount (SB)
  • 3. mixed event pairs, background (Bmix)
  • - Bmix will be normalized to SB in the region
    Minv.mass gt Mb
  • - the extracted signal (SB) - Bmix
  • For each of the types
  • ? reconstructed info
  • ? MC info

9
AliRsn ? ? KK-
Mb 1.1 GeV Strue is in a good agreement
with (SB)-Bmix Higher statistics needed
10
AliRsn K0? Kp-
Mb 1.2 GeV ! (SB)-Bmix ,besides Strue,
has probably input from other resonances.
Recommendation to list all other mothers of the
pairs. ? Large ?2 /ndf G0 (fit)G0
(PYTHIA6)
11
AliRsn ? ? pp
Mb 1.4 GeV ? Ntrue (? ) Ntrue (?)
Recommendation to list primary
multiplicities. ? G0 (fit)80 MeV lt G0
(PYTHIA6) 120 MeV ? add anti- ? to increase
statistics
12
AliRsn anti-?
! The larger pt the larger discrepancy
between (SB)-Bmix and Strue Strue/Bmix
(2RMS) 3, 8 and 12 for pt 1-2, 2-3 and 3-4
GeV/c respectively (2 times lower than
estimations with SHAKER) reconstructed ? MC
13
with MC info
Results with MC are very close to ones with
reconstruction. All open questions still exist.
14
AliRsn ?0 ? pp- anti-?0
! discrepancy between (SB)-Bmix and Strue
larger than for ? Input from other
resonances? Additional source of signals in
PYTHIA6 GEANT primaries can be decay products of
resonances.
15
AliRsn f0 ? pp-
Only one true pair! PYTHIA6 multiplicity of f0
is too low !?
PDG

PYTHIA6 KF KC particle
chg col anti mass width
w-cut lifetime decay 10221 259
f_0 0 0 0 1.00000
0.00000 0.00000 0.00000E00 1
IDC on/off ME Br.rat. decay products
1574 1 0 0.520000 pi
pi-
1575 1 0
0.260000 pi0 pi0

1576 1 0 0.110000 K
K-
1577 1 0
0.055000 K_L0 K_L0

1578 1 0 0.055000 K_S0 K_S0
16
AliRsn ?0 ? pp-
Mb 1.2 CeV 2 times discrepancy between
(SB)-Bmix and Strue ? Contributions of
other resonances, ?,
17
AliRsn ? ? pp-
True pairs not from one channel ? ? pp-
(Br2.2) ? ? pp-p0 (Br89) AliRsn controls the
pair, not the channel
AliRsn K0 ? pp-
There is no such channel in PYTHIA6
313 K0 m 0.896 width0.050
Br.rat. decay products 0.665
K pi-

0.333 K0 pi0

0.002 K0 gamma
It looks like we observe the p p- pairs from the
chain K0 ? K0p0 ? pp-p0 Experts study the
problem
18
Conclusions and recommendations
  • The AliRsn package works well. Takes 10 min. on
    CAF for 3 105 pp _at_ 10 TeV events.
  • Thanks a lot Alberto with colleagues.
  • 1. The signal extracted with mixed events,
    (SB)-Bmix , is higher than the true signal Strue
    , exception ? ? KK-
  • 2. Large ?2 of the BW fit. G0(fit)lt G0(PYTHIA6),
    exception K0? Kp-
  • 3. PYTHIA6 multiplicity of f0 is too low! Only
    ONE pp- pair from f0
  • Recommendations for AliRsn
  • to test the package with a cocktail generator
    with random primary particles resonances
    (PYTHIA6 primaries can be decay products of
    resonances)
  • to list all mothers of the pair studied
  • to list multiplicity of all primaries
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