From peter.skands at monash.edu Sat Feb 26 23:20:15 2022 From: peter.skands at monash.edu (Peter Skands) Date: Sun, 27 Feb 2022 10:20:15 +1100 Subject: [Pythia8-announce] Pythia 8.307 now available In-Reply-To: References: Message-ID: ===================================================================== Dear All, PYTHIA 8.307 has been released, and can be downloaded from ? http://pythia.org Main physics updates include extensions to the hadronic cross sections and beam types used for hadronic rescattering and cascades in the atmosphere, improvements for hidden valley scenarios, and a new framework for parallelisation (in addition to the existing openMP option). The release also contains a number of other technical improvements and bug fixes. A brief summary of all changes is included below and in the Update History part of the HTML manual. Wishing you an enjoyable experience with PYTHIA 8.307. Sincerely, The Pythia 8 Collaboration (Christian Bierlich, Nishita Desai, Leif Gellersen, Ilkka Helenius, Philip Ilten, Leif L?nnblad, Stephen Mrenna, Stefan Prestel, Christian Preuss, Torbj?rn Sj?strand, Peter Skands, Marius Utheim, Rob Verheyen) -------------------------------------------------------------------- CONTACT: write to authors at pythia.org if you need to contact any of the authors. This allows us to coordinate replies. You may also include the individual addresses of authors that are relevant for a specific issue. Never contact several persons independently on the same topic, thereby potentially leading to double work. Abuse will have consequences. When responding to emails from us at authors at pythia.org, please reply directly to the email, which has a unique return address of the form incoming+@incoming.gitlab.com. Do _not_ reply to authors at pythia.org, as this would start a new issue. Please consider allowing your correspondence to be made publicly available to other users via our issue tracker, by replying at any point with your express permission, e.g. "this correspondence can be made??public". ===================================================================== Summary list of changes for 8.307: * New option with interpolation between the low-energy hadronic cross sections, used for rescattering, and the more traditional SaS/DL cross sections, used at high energies. The latter framework has also been extended to include many more collinding hadron pairs. The Pythia::getSigmaTotal and Pythia::getSigmaPartial methods give the user direct access to these cross sections. These extend and replace the Pythia::getLowEnergySigma methods. * New "SU21" PDFs for some 20 mesons and baryons, to be used e.g. in the MPI scenarios in hadron-hadron collisions, e.g. in a cascade in the atmosphere. The pi+ default PDF has been upgraded from GRV92 LO to GRS99 LO. The GJR07 LO set has been included as an option for the proton. The default value of BeamRemnants:maxValQuark has been updated to allow also charm and bottom hadrons as incoming beam particles. * The framework for changing the beam kinematics between subsequent Pythia::next calls when using variable collision energies has been expanded. The Pythia::setKinematics methods mirror the frame type options for the beams. * As a further extension of the above, a new option exists wherein the first beam particle is initialized so it can be switched event-by-event between essentially any incoming hadron, while the second beam is restricted to be a proton or neutron. Again only SoftQCD and LowEnergyQCD processes are possible. To handle this feature, the code has been extended so that some 20 different PDFs are initialized, each with a corresponding MPI initialization and storage of required coefficients. * Extended and improved handling of the Hidden Valley (HV) scenario. Thanks to Matt Strassler and Suchita Kulkarni for useful input. ?? ? ? ?Improved tracing of hidden-valley colours through a hidden-valley shower evolution history, thereby avoiding problems for some topologies. ?? ? ? ?Introduced the possibility to bookkeep individual HV hadron types, in particular HV-mesons, and thereby manange masses and decay properties. The default remains the simpler scheme, where only a smaller set of HV-hadron properties need to be defined. The detailed scenario also involves a mass-dependent handling of the joining of hadronization chains, or the collapse into a single hadron. ?? ? ? ?The list of Zv decays has been expanded to include further HV-quarks. Some default masses have been modified. ?? ? ? ?It is possible to set different production rates for HV-quarks during hadronization, and for HV-diquarks leading to HV-baryon production. ?? ? ? ?Introduced an option to suppress production of one flavour-diagonal pseudoscalar state, representing the eta_1 flavour singlet. ?? ? ? ?The HiddenValley:spinFv default value has been changed from 1 to 0, to make it transparent that HV-quarks have spin 1/2 by default. ?? ? ? ?Expanded the list of invisible particles accordingly. ?? ? ? ?A few minor bug fixes. ?? ? ? ?A significantly expanded description in Hidden Valley Processes. * Added a new class PythiaParallel for easily making runs in parallel. See main161, main162 and main163 for usage examples. NOTE: this is an experimental feature. Feedback and bug reports should be sent to authors at pythia.org. * New option introduced, where MPI initialization data can be stored on file and reused in a later run, to save time. Also option to symmetrize the MPI rate between e.g. pi^+ p and pi^- p. * New options allow a harder fragmentation function for a beam-remnant diquark, by a separate choice of the a and b parameters, and also forbid the popcorn mechanism for it. * New diffractive states introduced, to cover all five-flavour mesonic states, and all baryonic ones with at most one c or b quarks. Furthermore, nitrogen and oxygen have been added to the set of nuclei * New processes SoftQCD:singleDiffractiveXB and SoftQCD:singleDiffractiveAX allow to set single diffraction to occur only by A B ? X B or only by A B ? A X. * Reorganised and consolidated the interface to external matrix element generators. Renamed ShowerMEs to ExternalMEs and ShowerMEsMadgraph to ExternalMEsMadgraph. Introduced new HelicitySampler class to sample helicities using external matrix elements. * New options to get and set the state of the random number generator, Rndm::getState and Rndm::setState, as a direct-transfer option to the file-based dumpState/readState methods. * New methods Hist::fillTable to read back in a table of histogram data, specifically as written by the Hist::table methods. * Some minor rearrangements in HadronLevel to better structure the interleaving of hadronic rescattering and particle decays. New method Pythia::moreDecays(int i) to perform the decay of a single specified particle. * Switched tunes to by default prefer LHAPDF 6 PDFs over LHAPDF 5 ones, via the setting Tune:preferLHAPDF. * New LHAPDF:xSymmetric parameters allow the user to choose to use symmetric PDFs for s, c, and b quarks when using LHAPDF for a performance boost. By default, c and b are taken as symmetric (this matches the previous behaviour). * Info::pTnow() can now also be used for showers during resonance decays, and when using the shower() method. The latter so far only for the Simple and Vincia shower models. * New switch "SLHA:allowOnlyOffShell? to allow SLHA decay tables with only off-shell decays. * Corrected a bug that mainly affects beam-remnant fragmentation in the QCD CR model. Previously, diquark-antidiquark systems with invariant masses below the threshold for baryon-antibaryon production would be combined into tetraquark-like states that do not exist in PYTHIA, resulting in errors with unknown particle codes and charge non-conservation. Now, MiniStringFragmentation::ministring2two() instead reconnects such topologies into two mesons, noting that this is consistent with the colour structure. Further motivation comes from studies of low-mass junction-antijunction systems. * Introduced fix to prevent the central description of Les Houches events showered with global recoil from shifting when shower variations are enabled. * Fixed a few issues in Vincia's sector merging. Specifically, while the merging itself still only handles QCD corrections, Vincia's QED showers can now be left on during merging. Also corrected a bug leading to incomplete histories replacing complete ones with smaller probability, and fixed an inconsistent treatment of trial showers in systems with coloured resonances. * When running Angantyr at very low energies, initialization would abort due to an incorrect initialization of the high-mass diffraction MPI machinery. Logic has been introduced to prevent this initializatoin. * Fixed memory leaks in the ColourReconnection class. * Fixed some recent compiler warnings and errors; thanks to Mattias Ellert * Removed the deprecated SubCollisionModel called MultiRadial from the heavy ion machinery. * Added an abort in Pythia initialization to prevent using a low energy process with a hard process. Thanks to Jenna Bacon. * Broke a circular shared pointer reference in ResonanceWidths and ParticleDataEntry which caused a small memory leak. Thanks to Gabriele Inghirami. * Minor fix to avoid unnecessary (attempted) MPI initialization. * Fixed issue with Dire getting stuck when showering soft QCD events. Note, Dire has not been validated for these types of events. Thanks to Giancarlo Panizzo and Marvin Flores for reporting the issue. ===================================================================== -------------- next part -------------- An HTML attachment was scrubbed... URL: From peter.skands at monash.edu Wed Mar 30 12:18:45 2022 From: peter.skands at monash.edu (Peter Skands) Date: Wed, 30 Mar 2022 22:18:45 +1100 Subject: [Pythia8-announce] Finally - a complete manual for Pythia 8 In-Reply-To: References: Message-ID: <652c246a-8150-4507-af04-aa27a5d7831e@Spark> Dear friends of Pythia, We are very glad to announce the completion of?A comprehensive guide to the physics and usage of PYTHIA 8.3?which was put on arXiv last week (e-Print:?2203.11601). This guide offers the first self-contained dedicated coverage of all aspects of Pythia 8 in depth. Spanning 315 pages, the contents are split into three parts:?Introduction,?Physics, and?Usage, and there is a helpful detailed table of contents at the front and an index and acronym list at the back. Previous descriptions of Pythia 8 were limited to summaries and introductions, and still often referred to the old Pythia 6.4 manual for details. However, with the physics and capabilities of Pythia 8 increasingly surpassing those of Pythia 6, the correspondence with the 6.4 manual was becoming less reliable, and in any case the algorithmic context there was the very differently structured Pythia 6 library. The new comprehensive?guide?to Pythia 8.3 has been rewritten from the ground up to stand on its own without referring to the 6.4 manual except casually where appropriate. This guide is therefore intended to fully replace the 6.4 manual as the main review-style reference for the physics and usage of Pythia 8. As usual, even a document this size cannot hope to capture all derivations and physical arguments in detail. Pythia relies on a large body of original work - contributed to by authors, students, external contributors, and the community at large, including experimental studies - which we have made an effort to point to throughout the guide with references that you can turn to for further details. When using the program to produce your own??results, we ask that you also make an effort to respect these works - and their authors - by citing not just the Pythia manual but also those original works that could be deemed to have direct bearing on your study. This was a collaborative project which?involved?all of the members of?the?Pythia Collaboration. But especially Christian Bierlich?deserves thanks?for coordinating and pulling the effort together as editor-in-chief during the approximately two years it took to complete. Sincerely, The?Pythia Collaboration https://pythia.org -------------- next part -------------- An HTML attachment was scrubbed... URL: From peter.skands at monash.edu Thu Nov 24 00:36:50 2022 From: peter.skands at monash.edu (Peter Skands) Date: Thu, 24 Nov 2022 11:36:50 +1100 Subject: [Pythia8-announce] Pythia 8.308 now available References: Message-ID: Dear PYTHIA subscriber, PYTHIA 8.308 has been released, and can be downloaded from ? https://pythia.org/ Main physics updates include new functionality geared towards cosmic-ray studies, several updates for Hidden-Valley scenarios, and an update to FxFx merging (see list below for details, and/or the update notes online). The default value of the top quark mass has also been updated, from 171 GeV to 173 GeV. Technical updates include new methods in Pythia?s Hist class to compute statistical uncertainties, higher moments, and more, and a couple of new ROOT-based example programs to visualise event and jet structure in (eta, phi) space provided by D. Gillberg, in addition to the usual minor improvements and bug fixes (see full list below). This release coincides with the journal publication of the PYTHIA 8.3 manual. Please update relevant bibtex reference databases to include the full journal reference: ? C. Bierlich, S. Chakraborty, N. Desai, L. Gellersen, I. Helenius, P. Ilten, L. L?nnblad, S. Mrenna, S. Prestel, C. T. Preuss, T. Sj?strand, P. Skands, M. Utheim, R. Verheyen, A comprehensive guide to the physics and usage of PYTHIA 8.3, SciPost Physics Codebases 8 (2022), doi:10.21468/SciPostPhysCodeb.8. Also note that there is a GitLab issue desk for PYTHIA 8.3, where already hundreds of questions have been posted (and most of them answered). Most of these are publicly visible and can be searched and filtered, to see if a question you have has already been discussed: ? https://gitlab.com/Pythia8/releases/-/issues/?sort=updated_desc&state=all&first_page_size=50 A brief summary of all changes is included below and in the Update History part of the HTML manual. Wishing you an enjoyable experience with PYTHIA 8.308. Sincerely, The Pythia 8 Collaboration (Christian Bierlich, Nishita Desai, Leif Gellersen, Ilkka Helenius, Philip Ilten, Leif L?nnblad, Stephen Mrenna, Stefan Prestel, Christian Preuss, Torbj?rn Sj?strand, Peter Skands, Marius Utheim, Rob Verheyen) -------------------------------------------------------------------- CONTACT: write to authors at pythia.org if you need to contact any of the authors. This allows us to coordinate replies. You may also include the individual addresses of authors that are relevant for a specific issue. Never contact several persons independently on the same topic, thereby potentially leading to double work. Abuse will have consequences. When responding to emails from us at authors at pythia.org, please reply directly to the email, which has a unique return address of the form incoming+@incoming.gitlab.com. Do _not_ reply to authors at pythia.org, as this would start a new issue. Please consider allowing your correspondence to be made publicly available to other users via our issue tracker, by replying at any point with your express permission, e.g. "this correspondence can be made??public". UNSUBSCRIBE: You received this email because you subscribe to the list pythia8-announce at projects.hepforge.org . Please update your preferences there if you do not wish to receive future PYTHIA announcements. ===================================================================== Summary list of changes for 8.308: ? The HIInfo class now has information about the impact parameter angle between colliding nuclei in the phi() function. In addition the impact parameter positions of the incoming nuclei are now set properly in Particle::vProd(). ? A new PythiaCascade wrapper class (in include/Pythia8Plugins) implements the functionality to perform fixed-target hadron-nucleus collisions and decays, as useful for the tracking of cascades is the atmosphere or in solid materials. The code in this class now is set up to handle any target nucleus. The new main184.cc example shows how to use PythiaCascade to track an atmospheric cascade, equivalent to the standalone main183.cc. An even simpler new example is found in main185.cc. ? The option to completely forbid popcorn baryon production from the beam remnant has been replaced by the possibility of a continuous suppression, see BeamRemnants:dampPopcorn. ? A new option for Pomeron flux has been added to provide more flexibility to modify the shape of the flux. ? Modified handling for resolved-lepton remnants so that also lepton-lepton collisions with unequal masses are correctly dealt with. ? Explicit bookkeeping of Hidden Valley (HV) colours in SU(N) scenarios has been introduced. These colours can be accessed in the event record, but are not shown by default. This allows for a more robust tracking of HV colours in showers. Notaby a Higgs decay to a pair of HV gluons can now be handled, which used to be impossible. The functionality of the TimeShower:recoilToColoured switch is extended also to apply to the HV colours. ? Update to decay method of ParticleDecays class allows for proper showering of leptons produced in Hidden Valley particle decays. ? A simple example of Hidden Valley production mechanisms introduced with main171.cc. ? Fixed a bug that could block the radiation of HV photons in a broken U(1) scenario, i.e. where the HV photons acquire mass. Affected was radiation in the decay of Fv states, i.e. states with a charge both in the normal and in the HV sector. ? Two new ROOT-based example programs, main94.cc and main95.cc, illustrating how to visualize events and jets, respectively, in (y, phi)-space. Thanks to D. Gillberg for contributing these examples. ? Added handling of statistical uncertainties to the Hist class, with error propagation in the various histogram operations and friend methods, for both unweighted and weighted events. Updated Hist compatibility for current Matplotlib. ? Updated JetMatching to support improved treatment of non-enhanced jets in FxFx merging, see Jet Merging for more details. The updated treatment also fixes a bug that led to an asymmetric treatment of heavy quarks and the corresponding anti-quarks. Thanks to Rikkert Frederix. ? Vincia's tune initialisation has been changed to not override initialization, event-generation, statistics, and main-program settings. ? Included particle ID code in error message when a workable decay channel cannot be found in ParticleDecays::decay(). Thanks to K. Pedro for suggesting this. ? Added additional protection for Pythia intialization. ? Fixed an issue in the tau decays which caused segmentation faults when a tau nu final state is present in the event record without a mother W. Thanks to S. Jeon for reporting the problem. ? Corrected several typos in antiName and chargeType properties for particle ID codes for diffractive states (e.g., 9904230) in ParticleData.xml; thanks to A. Verbytskyi, G. Panizzo, and D. Konstantinov. ? Updated default top quark mass to 173 GeV (up from 171 GeV) in line with current PDG average (rounded to nearest GeV). Added particle data for a few more nuclei. ? Corrected a bug that affected the read-in of RPV couplings via SLHA files. In the erroneous version, a coupling for the third generation in the first index (i.e. 3,i,j) could not be set. ? Fixed bug preventing the generation of Python bindings in MacOS. Also fixed external library issue with Makefiles for MacOS. ? Updated WeightsBase::getWeightNames to provide RIVET compatible names. ===================================================================== -------------- next part -------------- An HTML attachment was scrubbed... URL: