Toolkit for partonic process data storage and manipulation

1
Toolkit for partonic process data storage and
manipulation
Balatenichev S., Cherstnev A., Ilyin V.
(SINP MSU)

• Reasons and ideas of the toolkit
• New standard of partonic events storage
• Toolkit utilities
• Current status of the toolkit development

2
Why do we need this toolkit?

• Modern complexity of MC generation has resulted
  in separation of 2 stages of the generation ME
  (e.g. CompHEP) and SH (e.g. PYTHIA)
• II. Many collaborations have and develop
  databases of Monte-Carlo events at hard partonic
  level. Since MC generation in many cases is heavy
  task, changes of the data is faster to do by
  direct operations with the events without
  re-generation.

One needs interface between these stages
Toolkit of utilities for these manipulation
3
Structure of the toolkit
Visualization (Root)
Partonic events database
ME (CompHEP)
SH (PYTHIA)

• Data manipulation
• (mixing, updating, cuts and etc.)

4
New data storage standard

• Text file format is optimal for partonic events
  storage, in our opinion. Thus, a some
  standardization is needed for these files.
• The standard we proposed gives flexibility for
  data description and manipulations.
• Specific points for this standard are
• A physical information from ME to SH is highly
  heterogeneous. Our standard allows to transfer
  different types of the information within uniform
  syntax.
• We assume that SH generator or a manipulation
  utility will take that information transferred
  which can interpret.

5
New data storage standard
Text file of partonic events
Description of physical information beams,
processes, etc. Event 1 Event 2
Header of the file
Partonic event records
6
Header Syntax

• Basic unit of information in the header command
• Syntax command name command value
• Command value can be of numerical type or string
  (in that case it encloses in quotes).
• Some commands can be grouped under tags.
• Tag syntax Tag name command 1,, command N,
• Double the beginning of the tag
• semicolon the end of the tag
• The header information is stored as a set of
  tags. The tags are separated from event records
  by extra semicolon.

7
Example of the tags set

• generator nameCompHEP, version4.2.00,
• beam energy1.000E03, KF2212,
  nameproton', mass9.380E-01,
• strfun name'CTEQ', version'5m1', PDFid833,
  PDFgr11, PDFfilePDF/cteq5m1.pdf',
• process ID1, name'u D -gt E1 n1 b B ',
  CrosSec3.69595E-02,
• CrosSecErr4.61224E-03,
  Nparton6, master3,
• n_event IDprocess1, N1000, multN1,
  maxW2.96610E00,
• parton IDprocess1, in1, KF2, name'u',
  mass0.00000E00,
• parton IDprocess1, out2, KF11,
  namen1', mass0.00000E00,
• total Nprocess1, CrosSec3.69595E-02,
  CrosSecErr4.61224E-03, Nevent1000,
  
• QCDprocess IDprocess1, NL2,
  Qnorm9.11870E01, QCDalpha1.18108E-01,
  file_name'GEN/c_source/num/alpha_s.c',
• func_name'alpha_c(int q)',

8
Event record

• Event record occupies one line in the data file.
• For the interpretation of event records we
  introduce special tag
• format IDprocess5, ProcNumber'i',
  p1.3'13.6E', p2.3'13.6E',
• p3.1'13.6E', p3.2'13.6E', p3.3'13.6E',
  p4.1'13.6E', p4.2'13.6E', p4.313.6E',
  Q'10.3E', color_chainstring,
• 2. event record consists of statements divided
  with colons.
• Event record example
  1 2.825664E02-1.593711E02 8.204448E01
• -1.468924E00 6.821391E01-1.024018E01
  3.039867E01 2.797844E019.119E01(1 2)(6 5)

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Advantages of the standard

• Our text file standard corresponds to Les Houches
  generic format for events storage in FORTRAN
  common blocks (hep/ph-0109068).
• 2. Immediate advantages are
• Independence of programming languages for ME and
  SH generators.
• readability
• Simple realization.

10
Connection to Les Houches format

• We re-write FORTRAN Les Houches common blocks to
  C structures. Example is
• define maxproc 100
• typedef struct procinfo
• int id_beam2
  / KF of beam particle /
• double ebmup2
  / Beam energy /
• int pdf_group2, pdf_set2 /
  PDF information /
• int master, n_proc, proc_list /
  Master switch, number of subp
• double csmaxproc, cs_errmaxproc,
  cs_maxmaxproc / Cross sec
• int list_prcmaxproc, max_weightmaxproc
  / Extra info
• procinfo
• Toolkit writer(reader) writes(reads) data
  to(from) datafile from(to) these structures or
  FORTRAN common blocks.

11
Toolkit utilities

• Storage of partonic events data in text files of
  this standard allows to manipulate easily with
  the data.
• We suppose that the toolkit will include
  utilities
• Mixing and de-mixing in practice, we
  generate several files with partonic events and
  would like to mix them to one event flow and visa
  versa.
• Apply kinematical cuts phenomenological
  tasks require to apply kinematical cuts on
  events. Storage of data in our format allows to
  develop a utility for cut applying.

12
Toolkit utilities

• Event visualization we intend to make some
  utilities for remote visualization of process
  information and histogamming of events and etc.
• Updating this utility will allow to
  re-weigh events by MC algorithm. If distribution
  of new events weights is sufficiently smooth
  function, not very large part of the events
  statistic will be lost. For instance, this
  utility is convenient for updating of structure
  functions.
• Rewriter of old events files this utility
  rewrites events generated by CompHEP of old
  versions into new standard.

13
Current status of toolkit

• At present the toolkit is in test stage.
• We have developed
• Reader and writer to Les Houches common blocks (C
  structures) on C and FORTRAN
• Mixing utility
• CompHEP 4.2 outputs data in the standard
• My supposition the toolkit will be in site
• http//theory.sinp.msu.ru/
• In next some months.