pythia8130 distributed with AliRoot

[u/mrichter/AliRoot.git] / PYTHIA8 / pythia8130 / xmldoc / ErrorChecks.xml

<chapter name="Error Checks">

<h2>Error Checks</h2>

There is a few settings related to error checking during program
execution. Many other checks are performed as well, but do not 
have any specific setting related to themselves.

<flag name="Check:particleData" default="off">
Check the particle data tables for potential problems during 
initialization. This includes inconsistent use of charge in particle 
names, inconsistent setup of mass, mass range, width and lifetime, 
sum of branching ratios not unity (allowed but discouraged) or charge 
not conserved in a decay channel. Warnings should be viewed as reasons 
to check further, but need not indicate a true problem, and also not all 
problems may be caught. 
The <code>pythia.particleData.checkTable(level)</code> method,
used for these checks, may also be called directly. 
</flag>

<modepick name="Check:levelParticleData" default="1">
The level of verbosity and checks of particle data, if switched on.
<option value="0">mimimal amount of checks, e.g. that no channels open.
</option>
<option value="1">further warning if individual channels closed,
except for resonances.</option>
<option value="2">also print branching-ratio-averaged threshold mass
except for resonances.</option>
<option value="11">as 1, but include resonances in detailed checks.
</option>
<option value="12">as 2, but include resonances in detailed checks.
</option>
</modepick>

<flag name="Check:event" default="on">
When an event has been successfully generated, check that the 
final event record in <code>event</code> does not contain any 
unphysical particles, or nonconserved charge or energy-momentum. 
If this check fails, then <code>pythia.next()</code> obtains the 
value <code>false</code>, i.e. the event is counted as aborted.
</flag>

<modeopen name="Check:nErrList" default="0">
The number of erroneous events, in the above check, for which 
event listing and other detailed information will be printed. 
After that, only the normal error messages will be issued. 
Error counters are always updated, and accumulated numbers can be   
shown with <code>pythia.statistics()</code> at the end of the run.
</modeopen>

<parm name="Check:epTolErr" default="1e-4">
Maximum allowed summed deviation of <ei>E</ei>, <ei>p_x</ei>, 
<ei>p_y</ei> and <ei>p_z</ei> between the incoming beams and the 
final state, as a fraction of the initial energy, above which the 
event is counted as aborted.
(Unfortunetely roundoff errors do not scale linearly with the energy, 
and also have a very long tail. So while most events at lower energies 
may be correct to better than 1e-10, at LHC it does not have to signal 
any fundamental bug if also the default tolerance above is violated 
occasionally.)
</parm>

<parm name="Check:epTolWarn" default="1e-6">
A check on the same summed deviation as above, but counted as a 
warning rather than an error, and not leading to the event being
classified as aborted.
</parm>

</chapter>

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