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Herwig++ News				(emacs -*- outline -*- format)

* Herwig++-2.6.0 release: 2012-05-21 (tagged at SVN r7407)

** New NLO framework
   Matchbox, a flexible and very general framework for performing NLO
   calculations at fixed order or matched to parton showers is
   provided with this release.

** Dipole shower algorithm
   A first implementation of the coherent dipole shower algorithm by
   Plätzer and Gieseke (arXiv:0909.5593 and arXiv:1109.6256) is
   available.

** Alternative samplers and the ExSample library
   The ExSample library by Plätzer (arXiv:1108.6182) is shipped along
   with Herwig++ in an extended version. The extended version provides
   SamplerBase objects which can be used alternatively to the default
   ACDCSampler.

** New BSM models
*** New colour sextet diquark model
    A colour sextet diquark model has been included, as described in
    Richardson and Winn (arXiv:1108.6154).

*** Models reproducing the CDF t-tbar asymmetry
    Four models that can reproduce the reported t-tbar asymmetry have
    been included. 
    
*** Zprime
    A simple standard model extension by one additional heavy neutral
    vector boson.

** Interface to AlpGen, with MLM merging
   The Contrib directory contains a new interface to the AlpGen matrix
   element generator. AlpGen events must be preprocessed with the
   provided AlpGenToLH.exe tool before they can be used. More
   information can be found in the Herwig++ 2.6 release note.

** HiggsVBF Powheg
   Higgs boson production by vector boson fusion is available at NLO
   in the POWHEG scheme, as described in d'Errico, Richardson
   (arXiv:1106.2983). The Powheg DIS processes were available in
   Herwig++-2.5.2 already.
   
** Statistical colour reconnection
   Alternative mechanisms to minimize the colour length Sum(m_clu)
   before the hadronization stage, based on Metropolis and annealing
   algorithms.

** Energy extrapolation of underlying-event tunes
   To describe underlying-event data at different c.m. energies, the
   energy-dependent parameter pT_min will now be adjusted
   automatically, following a power-law. The new tune parameters are
   the value at 7000 GeV "MPIHandler:pTmin0", and MPIHandler:Power.

** Ticket #239: Reporting of minimum-bias cross-section
   When simulating minimum-bias events using the MEMinBias matrix
   element, the correct unitarized cross section can now be reported
   via the standard facilities; it is no longer necessary to extract
   it from the .log file of the run. The corresponding functionality
   is enabled by inserting a MPIXSecReweighter object as a
   post-subprocess handler: 
   create Herwig::MPIXSecReweighter MPIXSecReweighter 
   insert LHCHandler:PostSubProcessHandlers 0 MPIXSecReweighter

** Dependency on 'boost'
   Herwig++ now requires the boost headers to build; if not detected
   in standard locations, specify with the --with-boost configure
   option.

** Tests directory
   The Tests directory now contains input cards for almost all Rivet
   analyses. A full comparison run can be initiated with 'make tests'.

** Minor changes
*** Default LHC energy now 8 TeV
    All LHC-based defaults have now been updated to use 8 TeV as the
    center-of-mass energy.

*** Herwig::ExtraParticleID -> ThePEG::ParticleID
    The namespace for additional particles has been unified into
    ThePEG::ParticleID

*** MEee2VectorMeson
    The e+e- -> vector meson matrix element has moved from Contrib into
    HwMELepton.so

*** SUSY numerics fixes
    Better handling of rare numerical instabilities.

*** YODA output for Rivet
    The built-in histogramming handler can now output data in the YODA
    format used by Rivet.

*** Consistency checks in SLHA file reader
    Better warnings for inconsistent SusyLHA files

*** better colour flow checking for development

** Bug fixes
*** Extremely offshell W from top decay
    Numerical improvements for very off-shell W bosons coming from top
    decays.

*** Ticket #367: problems in using SUSY + LHE
    Susy events from Les Houches event files are now handled better.

*** Infinite loop in remnant decayer
    The remnant decayer will now abort after 100 tries.

*** Fix to HiggsVBF LO diagrams 
    The diagram structure of HiggsVBF LO matrix elements has been fixed.

*** LEP thrust fix 
    The calculation of the transverse momentum of a branching from the
    evolution variable in final-state radiation can now be
    changed. While formally a sub-leading choice this enables a better
    description of the thrust distribution in e+e- collisions at
    small values of the thrust. Currently the default behaviour, where
    the cut-off masses are used in the calculation, remains the same
    as previous versions.




* Herwig++-2.5.2 release: 2011-11-01 (tagged at SVN r6928)

** Optional new jet vetoing model
   The jet vetoing model by Schofield and Seymour (arXiv:1103.4811) is
   available via Evolver:ColourEvolutionMethod,
   PartnerFinder:PartnerMethod and SplittingFunction:SplittingColourMethod.
   The default behaviour is unchanged.

** MPI tune
   Version 3 of the MPI tunes is now the default. Please note that the
   pT parameter is energy-dependent and needs to be modified when an
   LHC run is not at 7 TeV.
   The latest tunes are always available at 
     http://projects.hepforge.org/herwig/trac/wiki/MB_UE_tunes

** MPI PDFs
   MPI PDFs can now be controlled independently.

** Initialization time speedup
   A new BSMModel base class was introduced between StandardModel and
   the BSM model classes. Together with a restructured decay mode
   initialization, this offers significantly faster startup times for
   BSM runs. ThreeBodyDecays can now always be switched on without a
   large speed penalty.

** Decay mode file
   Decay mode files in the SLHA format can now be read separately in
   any BSM model with 'set Model:DecayFileName filename'

** Powheg DIS
   Charged- and neutral-current DIS processes implementing the POWHEG
   method are now available.

** Diffraction models
   Xi cut implemented in PomeronFlux

** Ticket #352: Colour reconnection fixed in DIS

** Ticket #353: Improved numerical stability in chargino decays

** Ticket #358: Infinite loop in top events with pT cut in shower

** Ticket #361: Problem with duplicate 2-body modes in BSM

** Tickets #362 / #363: Crashes with baryon number violating models
   Particle decays in SUSY models with RPV now work correctly in the
   colour 8 -> 3,3,3 case. Colour reshuffling now works for RPV
   clusters.

** Improved Fastjet detection
   The configure step uses fastjet-config to make sure all header file
   paths are seen.

** Darwin 11 / OS X Lion
   A configure bug was fixed which prevented 'make check' from
   succeeding on OS X Lion.

** Vertex classes
   The specification of QED / QCD orders has been moved to the vertex
   constructors, to allow ThePEG consistency checks. WWHH vertices in
   MSSM and NMSSM were fixed. Some Leptoquark and UED vertices fixed.

** Hadronization
   Cleanup of obsolete code.



* Herwig++-2.5.1 release: 2011-06-24 (tagged at SVN r6609)

** Example input files at 7 TeV
   All our example input files for LHC now have their beam energy set
   to 7 TeV instead of 14 TeV.

** Colour reconnection on by default
   The colour reconnection tunes are now the default setup. Version 2
   of the tunes replaces the *-1 tunes, which had a problem with LEP
   event shapes.

** Run name tags
   Aded possibility to add a tag to the run name when running with the
   '-t' option. One run file can thus be run with different seeds and
   results stored in different output files.

** Floating point exceptions
   The new command line option -D enables floating point error checking.

** General improvements to WeakCurrent decays

** Remnant decayer
   Hardwired gluon mass was removed.

** WeakCurrentDecayConstructor
   Instead of specifying separate Particle1...Particle5 vectors for
   the decay modes, the new interface DecayModes can be filled with
   decay tags in the standard syntax.

** BSM: improvements to handling of vertex and model initialisation

** Powheg Higgs
   Option to use pT or mT as the scale in alphaS and for the
   factorization scale in the PDFs

** Ticket #337: Tau polarization wrong in charged Higgs decay

** Ticket #339: Colour flows in GeneralThreeBody Decayers for 3bar -> 8 3bar 1

** Ticket #340: Crash for resonant zero-width particles

** Ticket #341: Varying scale for BSM processes
   The scale used is now ResonantProcessConstructor:ScaleFactor or
   TwoToTwoProcessConstructor:ScaleFactor multiplied by sHat.

** Ticket #346: Chargino decays
   Chargino decayers now automatically switch between the mesonic
   decays for mass differences less than 2 GeV and the normal partonic
   decays above 2 GeV.

** Ticket #349: Stop by default on input file errors
   The '--exitonerror' flag is now the default behaviour for the
   Herwig++ binary. To switch back to the old behaviour,
   '--noexitonerror' is required.

** Ticket #351: Four-body stop decays

** Tested with gcc-4.6



* Herwig++-2.5.0 release: 2011-02-08 (tagged at SVN r6274)

** Uses ThePEG-1.7.0
   Herwig++ 2.5.0 requires ThePEG 1.7.0 to benefit from various
   improvements, particularly: handling of diffractive processes;
   respecting LD_LIBRARY_PATH when loading dynamic libraries,
   including LHAPDF; improvements to repository commands for decay
   modes. See ThePEG's NEWS file for more details.

** POWHEG improvements

*** New POWHEG processes
    Simulation at NLO accuracy using the POWHEG method is now
    available for hadronic diboson production (pp to WW,WZ,ZZ), Higgs
    decays to heavy quarks, and e+e- to two jets or ttbar, including
    full mass dependence.

*** Input file changes
    The input files for setting up POWHEG process simulation have been
    simplified.  See the example files LHC-Powheg.in and TVT-Powheg.in
    for the improved command list.

*** Structural changes
    The POWHEG backend in the shower code has been restructured to
    make future additions easier: PowhegEvolver has merged with
    Evolver; both the matrix element corrections and real corrections
    in the POWHEG scheme are implemented directly in the ME or Decayer
    classes.

** New processes at leading order

*** Photon initiated processes
    We have added a matrix element for dijet production in gamma
    hadron collisions.
    
*** Bottom and charm in heavy quark ME
    The option of bottom and charm quarks is now supported for heavy
    quark production in MEHeavyQuark.

** Colour reconnection
   The cluster hadronization model has been extended by an option to
   reconnect coloured constituents between clusters with a given
   probability. This new model is different from the colour
   reconnection model used in FORTRAN HERWIG, and improves the
   description of minimum bias and underlying event data.

** Diffractive Processes
   Both single and double diffractive processes are now supported in
   Herwig++. The Pomeron PDF is implemented using a fit to HERA data,
   and a pion PDF can be used to model reggeon flux.

** BSM physics

*** New models 
    We have added new BSM models, particularly ADD-type extra
    dimension models and the next-to-minimal supersymmetric standard
    model (NMSSM).  Effects of leptoquarks can as well be simulated.

*** Vertex additions
    We have added flavour changing stop interactions (stop -
    neutralino - charm) and gravitino interactions with particular
    emphasis on numerical stability for very light gravitinos.
    Tri-linear Higgs and Higgs-Higgs/Vector-Vector four-vertices are
    available as well.

*** Input file changes
    The SUSY model can now also extract the SLHA information from the
    header of a Les Houches event file: replace the SLHA file name
    in the example input files with the LH file name.

*** Structure
    The backend structure of the HardProcessConstructor has changed,
    to allow easier inclusion of new process constructors. Some 2->3
    BSM scattering processes involving neutral higgs bosons are now
    included. The spin handling has been improved in the background. 

** Shower splitting code reorganized
   The selection of spin structures has been decoupled from the choice
   of colour structure. This gives more flexibility in implementing
   new splittings. Selected splittings can be disabled in the input
   files.

** B mixing
   B mixing, and indirect CP violation in the B meson system are
   included now.
   
** Looptools
   The Looptools directory has been updated to reflect T.Hahn's
   Looptools 2.6.

** Contrib changes
   The ROOT interface has been removed as deprecated. The MCPWNLO code
   has temporarily been removed from the Contrib directory as a major
   review of this code is required. Additionally, there are various
   fixes to all other codes shipped in Contrib.

** DIS improvements
   The momentum reshuffling in DIS events has been improved.

** mu and nu beams
   mu, nu_e and nu_mu and their antiparticles are now available as
   beam particles. They are all supported in the DIS matrix
   elements. mu+ mu- collisions are supported in the general
   matrix element code for BSM models, but not yet in the hard-coded
   matrix elements for lepton-lepton scattering.

** Structural changes

*** Inline code
    Inline code has been merged into the header files, .icc files were
    removed.

*** Silent build
    By default, Herwig++ now builds with silent build rules. To get
    the old behaviour, run 'make V=1'.

*** Debug level
    The debug level on the command line will now always have priority.

*** Event counter
    The event counter has been simplified.

*** Interpolator persistency
    Interpolators can now be written persistently.

** Ticket #307: Momentum violation check in BasicConsistency
   Added parameters AbsoluteMomentumTolerance and
   RelativeMomentumTolerance

** Example POWHEG input files
   The example input files for Powheg processes now set the NLO
   alpha_S correctly, and are run as part of 'make check'.

** Truncated shower
   A problem which lead to the truncated shower not being applied in
   some cases has been fixed.

** Fixes to numerical problems
   Minor problems with values close to zero were fixed in several
   locations.

** Remove duplicated calculation of event shapes
   An accidental duplication in the calculation of event shapes was
   removed, they are now only calculated once per event. Several other
   minor issues in the event shape calculations have also been fixed.

** MRST PDFs fixed
   An initialization problem in the internal MRST PDFs was fixed.

** Vertex scale choice
   The scale in the Vertex classes can now be zero where
   possible.

** Treatment of -N flag
   The Herwig++ main program now correctly treats the -N flag
   as optional.

** Numerical stability improved
   The numerical stability in the 'RunningMass' and
   'QTildeReconstructor' classes has been improved.  The
   stability of the boosts in the SOPTHY code for the
   simulation of QED radiation has been improved.
   The accuracy of boosts in the z-direction has been improved to
   fix problems with extremely high p_T partons.

** Bugfix in initial state splittings
   A bug in the implementation of the PDF weight in initial-state
   qbar -> qbar g  splittings has been fixed.

** Bugfix in chargino neutralino vertices
   A bug in the 'chi+- chi0 W-+' and charged
   Higgs-sfermions vertices has been fixed.

** Remove uninitialized variables written to repository
   A number of uninitialised variables which were written to the
   repository have been initialised to zero to avoid problems on some
   systems.

** Fix to QED radiation in hadronic collisions
   The longitudinal boost of the centre-of-mass frame in hadronic
   collisions is correctly accounted for now in the generation of QED
   radiation.

** Fix to numerical problems in two-body decays
   Numerical problems have been fixed, which appeared in the rare case
   that the three-momenta of the decay products in two-body decays are
   zero in the rest frame of the decay particle.

** A problem with forced splittings in the Remnant was fixed.

** ME correction for W+- decays applied properly
   The matrix element correction for QCD radiation in W+- decays
   which was not being applied is now correctly used.

** Top quark decays from SLHA file
   The presence of top quark decay modes in SLHA files is now handled
   correctly.

** Exceptional shower reconstruction kinematics
   Additional protection against problems due to the shower
   reconstruction leading to partons with x>1 has been added.

** Ordering of particles in BSM processes
   Changes have been made to allow arbitrary ordering of the outgoing
   particles in BSM processes.

** Bugfixes in tau decays
   Two bugs involving tau decays have been fixed. The wrong masses
   were used in the 'KPiCurrent' class for the scalar form factors
   and a mistake in the selection of decay products lead to
   tau- --> pi0 K- being generated instead of tau- --> eta K-.

** Avoid crashes in baryon number violating processes.
   To avoid crashes, better protection has been introduced for the
   case where diquarks cannot be formed from the quarks in a
   baryon-number violating process. In addition, the parents of the
   baryon-number violating clusters have been changed to avoid
   problems with the conversion of the events to HepMC.

** QED radiation in W- decays
   A bug in the 'QEDRadiationHandler' class which resulted
   in no QED radiation being generated in W- decays has been fixed.

** A number of minor fixes to the SUSY models have been made.

** Partial width calculations in BSM models  
   A fix for the direction of the incoming particle in the calculation
   of two-body partial widths in BSM models has been made.

** LoopTools improvements   
   The LoopTools cache is now cleared more frequently to
   reduce the amount of memory used by the particle.

** Negative gluino masses are now correctly handled.

** A problem with mixing matrices which are not square has been fixed. 

** Removed duplicate diagram
   The 'MEee2gZ2ll' class has been fixed to only include the
   photon exchange diagram once rather than twice as previously.

** Fix for duplicate particles in DecayConstructor
   A problem has been fixed which occurred if the same particle was
   included in the list of DecayConstructor:DecayParticles.

** Fixes for UED model vertices
   A number of minor problems in the vertices for the UED model have
   been fixed.

** Include missing symmetry factor
   The missing identical-particle symmetry factor in
   'MEPP2GammaGamma' has been included.

** Fix floating point problem in top decays
   A floating point problem in the matrix element correction for top
   decays has been fixed.



* Herwig++-2.4.2 release: 2009-12-11 (tagged at SVN r5022)

** Ticket #292: Tau decay numerical instability
   The momentum assignment in tau decays contained numerical
   instabilities which have been fixed by postponing the tau decay
   until after the parton shower. A new interface setting
   DecayHandler:Excluded is available to prevent decays in the shower
   step. This is enabled by default for tau only.

** Ticket #290: Missing MSSM colour structure
   The missing colour structure for gluino -> gluon neutralino was added.

** Ticket #294: Zero momentum in some decays
   Some rare phase space points lead to zero momentum in two-body
   decays. This has been fixed.

** Ticket #295: Stability of QED radiation for lepton collider processes
   The numerical stability of QED radiation momenta was improved
   further.

** Ticket #296: K0 oscillation vertex was wrong
   The oscillation from K0 to K0_L/S now takes place at the production
   vertex of K0.

** Ticket #289: Undefined variables in repository
   On some system configurations, undefined variables were written to
   the repository. These have been fixed.

** Fixed QED radiation for hadron processes
   The longitudinal boost of the centre-of-mass frame in hadronic
   collisions is correctly accounted for now.

** Numerical stability fixes 
   Small fixes in RunningMass and QTildeReconstructor.

** Powheg example input files
   The example input files for Powheg processes now set the NLO
   alpha_S correctly, and are run as part of 'make check'.

** OS X builds for Snow Leopard
   Snow Leopard machines will now be recognized as a 64bit
   architecture.




* Herwig++-2.4.1 release: 2009-11-19 (tagged at SVN r4932)

** Uses ThePEG-1.6.0 
   Herwig++ now requires ThePEG-1.6.0 to benefit from the improved
   helicity code there. If you have self-written vertex classes, see
   ThePEG's NEWS file for conversion instructions.

** Vertex improvements
   ThePEG's new helicity code allowed major simplification of the vertex
   implementations for all Standard Model and BSM physics models.

** New Transplanckian scattering model
   An example configuration is in LHC-TRP.in

** BSM ModelGenerator as branching ratio calculator
   The BSM ModelGenerator has a new switch to output the branching
   ratios for a given SLHA file in SLHA format, which can then be used
   elsewhere.

** BSM debugging: HardProcessConstructor
   New interface 'Excluded' to exclude certain particles from
   intermediate lines.  

** Chargino-Neutralino-W vertex fixed

** Spin correlations
   are now switched on by default for all perturbative decays.

** Ticket #276: Scale choice in BSM models' HardProcessConstructor
   New interface 'ScaleChoice' to choose process scale between 
   - sHat (default for colour neutral intermediates) and 
   - transverse mass (default for all other processes).

** Ticket #287: Powheg process scale choice
   The default choice is now the mass of the colour-singlet system.
   
** Ticket #278: QED radiation for BSM
   Soft QED radiation is now enabled in BSM decays and all
   perturbative decays by default. 

** Ticket #279: Full 1-loop QED radiation for Z decays
   Soft QED radiation in Z decays is now fully 1-loop by default.

** Ticket #280: Redirect all files to stdout
   This is now implemented globally. The files previously ending in
   -UE.out and -BSMinfo.out are now appended to the log file. They now
   also obey the EventGenerator:UseStdout flag.

** Ticket #270: LaTeX output updated
   After each run, a LaTeX file is produced that contains the full
   list of citations. Please include the relevant ones in publications.

** Ticket #256: Mac OS X problems
   An initialization problem that affected only some configurations has
   been identified and fixed.

** Tests directory added
   This contains many .in files, to exercise most matrix
   elements. 

** Minor fixes
*** Prevent rare x>1 partons in shower reconstruction.
*** SUSY-LHA parameter EXTPAR can be used to set tan beta
*** Improved Fastjet detection at configure time





* Herwig++-2.4.0 release: 2009-09-01 (tagged at SVN r4616)

** New matrix elements
   We have added a built-in implementation of several new matrix elements:
   PP --> WW / WZ / ZZ
   PP --> W gamma / Z gamma
   PP --> VBF Higgs
   PP --> Higgs tt / Higgs bb
   e+e- --> WW / ZZ
   gamma gamma --> ff / WW 



** Base code improvements
*** Ticket #257: Remnant handling
    A problem with forced splittings in the Remnant was fixed.

*** Ticket #264: Soft matrix element correction
    A problem with emissions form antiquarks was fixed. 



** PDF sets
*** New default set
    MRST LO** is the new default PDF set. LO* is also available built-in.

*** Shower PDFs can be set separately from the hard process
    Use the 'ShowerHandler:PDF' interface.



** Parameter tunes
    Shower, hadronization and underlying event parameters were retuned
    against LEP and Tevatron data respectively.



** BSM module improvements
*** Ticket #259: read error for some UED models
    Arbitrary ordering of outgoing lines in the process description is now
    possible.

*** Ticket #266: branching ratio sums
    The warning threshold for branching ratios not summing to 1 has
    been relaxed. It is now a user interface parameter.

*** Ticket #267: Top decay modes
    Top decay modes listed in SLHA files are now handled correctly.



** QED radiation 
*** Ticket #241: Soft QED radiation is now enabled by default

*** Ticket #265: Radiation off W+ and W- is now handled correctly



** Interfaces
*** Ticket #243: Fastjet
    Fastjet is now the only supported jet finder code. All example
    analyses have been converted to use Fastjet.

*** KtJet and CLHEP interfaces have been removed.

*** New interfaces to AcerDet and PGS available in Contrib

*** MCPWnlo distributed in Contrib

*** HepMC and Rivet interfaces moved to ThePEG



** Ticket #239: Inelastic cross-section for MinBias
   This information is now available in the ...-UE.out files.



** Technical changes
*** Ticket #186
    Configure now looks for ThePEG in the --prefix location first.

*** Configure information
    Important configuration information is listed at the end of the
    'configure' run and in the file 'config.thepeg'. Please provide
    this file in any bug reports.

*** New ZERO object
    The ZERO object can be used to set any dimensionful quantity to
    zero. This avoids explicit constructs like 0.0*GeV.

*** Exception specifiers removed
    Client code changes are needed in doinit() etc., simply remove the
    exception specifier after the function name.

*** Ticket #263: Tau polarizations can be forced in TauDecayer





* Herwig++-2.3.2 release: 2009-05-08 (tagged at SVN r4249)

** SUSY enhancements

*** Ticket #245: Select inclusive / exclusive production
    Using the new 'HardProcessConstructor:Processes' switch options
    'SingleParticleInclusive', 'TwoParticleInclusive' or 'Exclusive'
*** Improved three-body decay generation
    Several problems were fixed, incl. tickets #249 #250 #251
    Thanks to J.Tattersall and K.Rolbiecki for the stress-testing!
*** Looptools fix
    Release 2.3.1 had broken the Looptools initialization.
*** Improved warning message texts

** Ticket #237:
   Values of q2last can now be zero where possible.

** Ticket #240:
   The Herwig++ main program now correctly treats the -N flag as optional.

** Ticket #246:
   Extreme pT partons fixed by improving accuracy of z boosts.

** DIS
   Improved parton shower momentum reshuffling.

** Minimum Bias events
   The zero-momentum interacting particle used for
   bookkeeping is now labelled as a pomeron. 

** User Makefile
   Makefile-UserModules does not enable -pedantic anymore. User's ROOT
   code will not compile otherwise.

** Build system
   Small fixes in the build system.



* Herwig++-2.3.1 release: 2009-03-31 (tagged at SVN r4140)
** Initial state showers
   The PDF veto was wrongly applied to qbar->qbar g splittings.

** User interaction
   The Makefile-UserModules now includes the Herwig version number.
   The -N flag to 'Herwig++ run' is optional now, as was always intended.

** Contrib
   The contrib directory is now included in the tarball. The omission
   was accidental.

** Numerical accuracy
   Minor problems with values close to zero were fixed in several
   locations.

** LEP event shapes
   An accidental duplication was removed, they are now only calculated
   once per event.

** MRST PDF code
   Initialization problem fixed.

** Mac OS X
   The configure script was improved to detect libraries better.

** Libtool
   Updated to version 2.2.6


* Herwig++-2.3.0 release: 2008-12-02 (tagged at SVN r3939)
** Major release, with many new features and bug fixes

** Extension to lepton-hadron collisions

** Inclusion of several processes accurate at next-to-leading order
   in the POsitive Weight Hardest Emission Generator (POWHEG) scheme

** Inclusion of three-body decays and finite-width effects
   in BSM processes

** New procedure for reconstructing kinematics of the parton shower
   based on the colour structure of the hard scattering process

** New model for baryon decays including excited baryon multiplets

** Addition of a soft component to the multiple scattering model
   of the underlying event and the option to choose more than one hard
   scattering explicitly

** New matrix elements for DIS and e+e- processes

** New /Contrib directory added
   containing external modules that will hopefully be of use to some
   users but are not expected to be needed by most users and are not
   supported at the same level as the main Herwig++ code

** Minor changes to improve the physics simulation:

*** IncomingPhotonEvolver added
    to allow the simulation of partonic processes with incoming photons
    in hadron collisions

*** KTRapidityCut added
    to allow cuts on the p_T and rapidity, rather than just the p_T and
    pseudorapidity used in SimpleKTCut. This is now used by default for
    cuts on massive particles such as the $W^\pm$, $Z^0$ and Higgs
    bosons and the top quark

*** Several changes to the decayers of B mesons
    both to resolve problems with the modelling of partonic decays and
    improve agreement with $\Upsilon(4s)$ data

*** Changes to allow values other than transverse mass of final-state particles as maximum transverse momentum for radiation in parton shower
    either SCALUP for Les Houches events or the scale of the hard
    process for internally generated hard processes

*** Changed defaults for intrinsic transverse momentum in hadron collisions
    to 1.9GeV, 2.1GeV and 2.2GeV for the Tevatron and LHC at 10 TeV and
    14 TeV, respectively

*** Pdfinfo object is now created in the HepMC interface
    However in order to support all versions of HepMC containing this
    feature the PDF set is not specified as not all versions contain
    this information

*** New option of only decaying particles with lifetimes below user specified value

*** New options for the cut-off in the shower
    and some obsolete parameters removed

*** Added option of switching off certain decay modes in BSM models

*** Added a Matcher for Higgs boson
    to allow cuts to be placed on it

*** Diffractive particles deleted from default input files
    they were not previously used

** Technical changes:

*** Some AnalysisHandler classes comparing to LEP data have been renamed
    e.g. MultiplicityCount becomes LEPMultiplicityCount to avoid
    confusion with those supplied in /Contrib for observables at the
    Upsilon(4s) resonance

*** Reorganisation to remove the majority of the .icc files
    by moving inlined functions to headers in an effort to improve
    compile time

*** Restructured the decay libraries to reduce the amount of memory allocation
    and de-allocation which improves run-time performance

*** The switch to turn off LoopTools has been removed
    because LoopTools is now used by several core modules. As LoopTools
    does not work on 64-bit platforms with g77 this build option is not
    supported

*** Removed support for obsolete version of HepMC supplied with CLHEP
    and improved the support for different units options with HepMC

*** EvtGen interface has been removed until it is more stable

*** Support for ROOT has been removed
    it was not previously used

*** CKKW infrastructure has been removed from the release
    until a concrete implementation is available

*** Default optimisation has been increased from -O2 to -O3

*** Handling of the fortran compiler has been improved
    mainly due to improvements in the autotools

*** Use of FixedAllocator for Particle objects in ThePEG has been removed
    as it had no performance benefits

** Bugs fixed:

*** Problems with the mother/daughter relations in the hard process
    and diagram selection in W+- and Z0 production in association with a
    hard jet

*** In general matrix element code for fermion-vector to fermion-scalar
    where the outgoing fermion is coloured and the scalar neutral

*** In the selection of diagrams in some associated squark gaugino processes

*** h0->mu+mu- was being generated when h0->tau+tau-

*** Normalisation in the Histogram class for non unit-weight events

*** Protection against negative PDF values has been improved
    these can occur when using NLO PDF sets

*** Lifetime for BSM particles is now automatically calculated
    at the same time as the width

*** Hadrons containing a top quark now treated like hadrons containing BSM particles
    in order to support this possibility

*** Several ambiguous uses of unsigned int

*** Several variables that may have been used undefined

*** Several memory leaks at initialisation

*** The configuration now aborts if no fortran compiler is found
    as this is required to compile Looptools

*** Several minor floating point errors that did not affect results



* Herwig++-2.2.1 release: 2008-07-09 (tagged at SVN r3434)
** Ticket #181: BSM shower with a decay close to threshold
   Now fixed.

** Ticket #191: Split SUSY crash
   Improved error message. 

** Ticket #192: using SCALUP as the pT veto in the shower
   Now implemented.

** Ticket #194: production processes of ~chi_1(2)-
   Fixed bug in the diagram creation.

** Removed unused particles
   DiffractiveParticles.in was removed, they were never produced.

** Hadronization
   Top quark clusters now possible, handled as 'exotic' clusters.

** Improved handling of decay modes
   See ThePEG-1.3.0. 'defaultparticle' command is now obsolete. 

** Multi-Parton interactions
   Increased phase space sampling to have less than 1% uncertainty on
   average multiplicity.

** New libtool version
   gfortran is now used as default if it is available. Set FC=g77 to
   override this. 

** Fixed several memory leaks

** Memory allocation
   Now using plain 'new' and 'delete'.


* Herwig++-2.2.0 release: 2008-04-18 (tagged at SVN r3195)
** Major release: now as stand-alone library
   Herwig++ is now a stand-alone dlopen() plugin to ThePEG.
   No compile-time linking to Herwig code is required. The Herwig++
   binary is a simple executable steering ThePEG, which can
   be replaced by other frontends (such as setupThePEG / runThePEG).  

** New matrix elements
   p p   -> W + jet / Z + jet / W + higgs / Z + higgs
   e+ e- -> Z + higgs

** Looptools 
   Updated to version 2.2.

** Ticket #141: segfault from using 'run' command
   Fixed by using default allocators in Herwig++, and the
   Repository::cleanup() method in ThePEG 1.2.0. 

** Ticket #157: broken gsl library path on some 64bit systems
   Paths with lib64 are correctly identified now.

** Ticket #159: p_t spectrum of ttbar pair
   Fixed identical particle multiplier in Sudakov form factor.

** Ticket #161: glibc segfault
   Rare segfault in MPI handler fixed.

** Ticket #165: rare infinite loop in four-body decay
   All 4-body decays without dedicated decayers now use the Mambo algorithm.
   A loop guard has been introduced to 3-body decays to avoid infinite retries.

** Ticket #166: rare infinite loop in top ME correction
   These very rare events (O(1) in 10^7) close to mass threshold
   now are discarded.

** Higgs width fixes

** SatPDF
   Optionally, the PDF extrapolation behaviour outside a given range 
   can now be specified.

** gcc 4.3
   Herwig++-2.2 compiles cleanly with the new gcc 4.3 series.




* Herwig++-2.1.4 release: 2008-03-03 (tagged at SVN r3024)
** Ticket #152: Vertex positions
   All vertex positions of unphysical particles are set to zero until
   a fix for the previous nonsensical values can be implemented.




* Herwig++-2.1.3 release: 2008-02-25 (tagged at SVN r2957)
** Ticket #129: Baryon decays
   Fix for baryon decay modes.

** Ticket #131: HepMC
   Check if IO_GenEvent exists

** Ticket #134: Hadronization
   Smearing of hadron directions in cluster decay fixed.

** Ticket #137: HepMC
   HepMC conversion allows specification of energy and length units to
   be used. 

** Ticket #139: Neutral kaons
   Ratio K_L / K_S corrected.

** Ticket #140 / #141: Crash on shutdown
   Event generation from the 'read' stage or an interface now shuts
   down cleanly. Fixes a crash bug introduced in 2.1.1 which affected
   external APIs to ThePEG / Herwig.

** Ticket #146: BSM models can be disabled
   To save build time, some or all of the BSM models can be disabled
   using the '--enable-models' configure switch.

** Reorganised .model files
   The .model files now include the model-specific particles, too.

** Re-tune
   Re-tuned hadronization parameters to LEP data. 

** Other fixes in
   QSPAC implementation in Shower; Multi-parton interaction tuning;
   MRST initialization




* Herwig++-2.1.2 release: 2008-01-05 (tagged at SVN r2694)
** Ticket #127
   Thanks to a patch submitted by Fred Stober, HepMCFile now can
   output event files in all supported formats. 

** Ticket #128
   Fixed incorrect value of pi in histogram limits.

** Other fixes in
   CKKW Qtilde clusterers, BSM width cut, SUSY mixing matrices.




* Herwig++-2.1.1 release: 2007-12-08 (tagged at SVN r2589)
** Bug #123
   Fixed a bug with particle lifetimes which resulted in nan for some
   vertex positions.

** Secondary scatters
   Fixed bug which gave intrinsic pT to secondary scatters.

** gcc abs bug detection
   configure now checks for and works around
   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34130

** CKKW reweighting
   Fixed wrong check for top quarks.

** MPIHandler
   Fixed call order ambiguity.




* Herwig++-2.1.0 release: 2007-11-20 (tagged at SVN r2542)
** Major new release
   Herwig++-2.1 includes significant improvements, including
   multi-parton interactions, BSM physics and a new hadronic decay
   model, tuned to LEP data.

   For an overview of the changes, please see the release note
   arXiv:0711.3137




* Herwig++-2.0.3 release: 2007-08-21 (tagged at SVN r2101)

** Bug #90
   nan in top decay ME corrections fixed.

** unlisted
   Colour flow fix in LightClusterDecayer

** unlisted
   Updated version of MultiplicityCount analysis handler.




* Herwig++-2.0.2 release: 2007-07-06 (tagged at SVN r1716)

** Bug #80
   Separation of HepMC from CLHEP is handled properly now.

** Bug #83
   Workaround for OS X header problem

** unlisted
   Veto on very hard emissions from Shower.

** unlisted
   Detailed documentation in .in files




* Herwig++-2.0.1 release: 2006-12-05 (tagged at SVN r1195)

** Bug #54
   ClusterFissioner vertex calculation fixed.

** Bug #57
   Crash when showering W+jet events supplied by Les Houches interface.

** Bug #59
   Fix for #57 applied to LHC events.

** Bug #60
   Segfault when PDF is set to NoPDF.

** Bug #61
   Missing weight factor for I=0 mesons

** Bug #62
   Spinor vertex calculations broken when spinor rep is not default rep.

** Bug #63
   Top decay never produces tau.

** Bug #69
   TTbar and HiggsJet analysis handlers fixed.

** unlisted 
   Reorganization of Hadronization module gives 30% speedup. 
   Thanks to Vincenzo Innocente at CMS for his profiling work!

** unlisted
   cleaner automake files in include/ and src/

** unlisted 
   Hw64 hadron selection algorithm 'abortnow' fixed.

** unlisted 
   Top/LeptonDalitzAnalysis removed (only worked with modified code).

** unlisted
   removed f'_0 from particle list, decays were not handled




* Herwig++-2.0.0 release: 2006-09-28 (tagged at SVN r1066)

** Full simulation of hadron collisions