The Pythia program can be used to generate high-energy-physics ''events'', i.e. sets of outgoing particles produced in the interactions between two incoming particles. The objective is to provide as accurate as possible a representation of event properties in a wide range of reactions, within and beyond the Standard Model, with emphasis on those where strong interactions play a role, directly or indirectly, and therefore multihadronic final states are produced. The physics is then not understood well enough to give an exact description; instead the program has to be based on a combination of analytical results and various QCD-based models. This physics input is summarized here, for areas such as hard subprocesses, initial- and final-state parton showers, underlying events and beam remnants, fragmentation and decays, and much more. Furthermore, extensive information is provided on all program elements: subroutines and functions, switches and parameters, and particle and process data. This should allow the user to tailor the generation task to the topics of interest.

/pdf/pythia-6-4-physics-and-manual-3dvwmijpnq.pdf

PYTHIA 6.4 Physics and Manual

http://risa.stanford.edu/teaching/362/particledarkmatter.pdf

Particle dark matter: Evidence, candidates and constraints

This paper gives the 2010 self-consistent set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA) for international use. The 2010 adjustment takes into account the data considered in the 2006 adjustment as well as the data that became available from 1 January 2007, after the closing date of that adjustment, until 31 December 2010, the closing date of the new adjustment. Further, it describes in detail the adjustment of the values of the constants, including the selection of the final set of input data based on the results of least-squares analyses. The 2010 set replaces the previously recommended 2006 CODATA set and may also be found on the World Wide Web at physics.nist.gov/constants.

/pdf/codata-recommended-values-of-the-fundamental-physical-4bsdant71c.pdf

CODATA Recommended Values of the Fundamental Physical Constants: 2006

Theory and phenomenology of two-Higgs-doublet models

We review the present status of QCD corrections to weak decays beyond the leading-logarithmic approximation, including particle-antiparticle mixing and rare and $\mathrm{CP}$-violating decays. After presenting the basic formalism for these calculations we discuss in detail the effective Hamiltonians of all decays for which the next-to-leading-order corrections are known. Subsequently, we present the phenomenological implications of these calculations. The values of various parameters are updated, in particular the mass of the newly discovered top quark. One of the central issues in this review are the theoretical uncertainties related to renormalization-scale ambiguities, which are substantially reduced by including next-to-leading-order corrections. The impact of this theoretical improvement on the determination of the Cabibbo-Kobayashi-Maskawa matrix is then illustrated. [S0034-6861(96)00304-2]

Weak decays beyond leading logarithms

Workshop on the standard model at low-energies: Miniproceedings

We review the status of the hadronic light-by-light contribution to the muon anomalous magnetic moment and critically compare recent calculations. We also study in detail which momentum regions the pi^0 exchange main contribution originates. We also argue that a_\mu^{light-by-light} = (11 \pm 4) \times 10^{-10} encompasses the present understanding of this contribution and comment on some directions to improve on that.

The Hadronic Light-by-Light Contribution to the Muon Anomalous Magnetic Moment: Where do we stand?

We show that the characteristic p_\perp spectrum yields valuable information for the test of models for the production of narrow graviton resonances in the TeV range at LHC. Furthermore, it is demonstrated that in those scenarios the parton showering formalism agrees with the prediction of NLO matrix element calculations.

/pdf/qcd-signatures-of-narrow-graviton-resonances-in-hadron-1khggrlngm.pdf

QCD Signatures of Narrow Graviton Resonances in Hadron Colliders

We apply hard pion Chiral Perturbation Theory to charmonium decays to ππ, KK and ηη. We first discuss why we expect to be able to provide results for the chiral logarithms in χc0 and χc2 decays to two pseudoscalars while for the decays from J/ψ, ψ(nS) and χc1 no simple prediction is possible. The leading chiral logarithm turns out to be absent for χc0, χc2 → PP. This result is true for all fully chiral singlet states of spin zero and two.

/pdf/chiral-symmetry-and-charmonium-decays-to-two-pseudoscalars-2cpq7p9694.pdf

Chiral symmetry and charmonium decays to two pseudoscalars

We report on recent advances on the computation of the matrix elements of the electroweak penguins Q(7) and Q(8) which are relevant for the DeltaI = 3/2 contribution to epsilon'(K) in the chiral limit. The matching of scale and scheme dependences between Wilson coefficients and these matrix elements is done analytically at NLO in alpha(S).

Johan Bijnens

Papers

Workshop on the standard model at low-energies: Miniproceedings

The Hadronic Light-by-Light Contribution to the Muon Anomalous Magnetic Moment: Where do we stand?

QCD Signatures of Narrow Graviton Resonances in Hadron Colliders

Chiral symmetry and charmonium decays to two pseudoscalars

Matching the electroweak penguins Q(7) and Q(8)