Enhancements in LCFI Physics Studies: LCFI.Vertex.Package and Vertex Detector Optimization

1. WP 1 – Simulation and Physics Studies • Introduction to LCFI Physics Studies Sonja Hillert 5 min • Current status of C++ ZVTOP Ben Jeffery 10 min • The ghost track algorithm Dave Jackson 5 min • Towards release of the LCFI Vertex Package Sonja Hillert 10 min

2. Simulation and Physics Studies - Overview • aim: optimisation of vertex detector parameters and evaluation of its performance • two main areas of work: • Development of high-level reconstruction tools: • current focus: development of C++ based Vertex Package comprising vertex finder ZVTOP, NN-based flavour tag and quark charge sign selection • to be interfaced to LCIO and released mid of this year • release will be followed by work on upgrades • Study of Physics channels: • goal is to realistically quantify performance following vertex detector contribution to physics analysis through entire analysis chain • in parallel: performance comparison of different detector designs using fast MC SGV • (human readable detector description), • to be replaced by full simulation and reconstruction framework in the future

3. track & jet parameters (LCIO format) release planned in mid 2006 first release later extensions neural net ZVTOP (ZVRES & ZVKIN) charge dipole use of additional information (e.g. particle ID) NN-based flavour tag quark-sign selection for charged vertices vertex quantities, flavour tag, vertex charge (LCIO format) The LCFI Vertex Package ready being written coded and under test under development ready for b bbar; to be extended to c cbar people involved: Dave Jackson, Dave Bailey Ben Jeffery, Mark Grimes, Sonja Hillert people involved: Dave Jackson, Dave Bailey Ben Jeffery, Mark Grimes, Sonja Hillert joining soon: Victoria Martin

4. Vertex Package Validation • fast MC SGV provides good basis for testing the new software: no complication from issues • like track finding / pattern recognition at subdetector interfaces seen in the past in full MC • results for performance obtained with FORTRAN version of ZVTOP available for cross-checks • detailed comparison of different versions possible by using identical input events • C++ based code should perform at least as well as FORTRAN version; • improvements of code wrt FORTRAN will be guided by comparison with MC information • first replace core ZVTOP, then also replace calculation of input variables for flavour tag • neural net and vertex charge reconstruction; at each stage compare performance • final step before release: • interface to LCIO to allow package to be included in the standard ILC software

5. 250 mm 60 mm 25 mm 15 mm 8 mm e+e- BEAM 100 mm S. Hillert Comparing different detector designs Exploration of different detector designs straightforward in SGV • importance of small beam pipe radius demonstrated • by recent study of probability l0 for reconstructing • neutral hadron as charged (Snowmass 2005) • differences between designs most pronounced at • low jet energy and large cos q • Study recently begun (Erik Devetak): • variation of positions of all detector layers • evaluation of effects of reduced hit efficiency • and comparison to loss of complete sensor

6. S. Riemann LC-TH-2001-007 Study of physics processes • extra-dimensions model predicts deviation of ALR • from Standard Model ine+e- b bbar • quark charge sign selection (obtained from vertex charge, for charged hadrons) permits unfolding cross section • study of this channel to begin soon (Ben Jeffery, Sonja Hillert) • other processes expected to be sensitive to quark charge sign selection & detector design • includeHiggs (e.g. e+e-  ZHH) and SUSY studies • LCFI in contact with Lancaster group studying scalar top production • motivation: dark matter theory, study expected to be sensitive to charm tagging • signal extracted using Iterative Discriminant Analysis (IDA); result used to compare different • detector designs; for further details see presentation by A Sopczak at LCWS 2006