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#117 closed defect (fixed)
Error when initialising MPI at very low energies
| Reported by: | Frank Siegert | Owned by: | Stefan Hoeche |
|---|---|---|---|
| Priority: | minor | Milestone: | |
| Component: | Unknown | Version: | 1.2.3 |
| Keywords: | Cc: | Anton.Karneyeu@cern.ch |
Description
If you want to run pp or ppbar at really low center-of-mass energies (e.g. 53 GeV) and experience an error of the type "\sigma_{hard} < \sigma_{nd}" then increase the RESCALE_EXPONENT a bit. For sqrt(s)=53GeV a value of 0.21 works fine. Alternatively you can use the cteq6l1 tune which runs fine at 53 GeV by default.
This will be fixed in the next release of Sherpa.
Attachments (0)
Change History (6)
comment:1 Changed 13 years ago by
| Cc: | Anton.Karneyeu@cern.ch added |
|---|
comment:2 Changed 13 years ago by
| Resolution: | → fixed |
|---|---|
| Status: | new → closed |
comment:3 Changed 13 years ago by
| Resolution: | fixed |
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| Status: | closed → reopened |
| Type: | question → defect |
comment:4 Changed 13 years ago by
| Owner: | changed from hoeth to Stefan Hoeche |
|---|---|
| Status: | reopened → new |
comment:5 Changed 13 years ago by
| Resolution: | → fixed |
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| Status: | new → closed |
This problem is solved with r17035. The fix will be part of Sherpa v1.2.4.
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Amisic should be modified to accomodate for the fact that \sigma_{hard} < \sigma_{nd} is possible at very low energies. This would however imply that unitarity is violated in this model and that BFKL effects dominate the QCD dynamics.