Self-modulation of long electron beams in plasma at PITZ
The Photo Injector Test facility at DESY, Zeuthen site (PITZ), offers the unique possibility to study and demonstrate the self-modulation of long electron bunches in plasma. A set of numerical simulations with the particle-in-cell code OSIRIS has been carried out for a better understanding of the process. Of particular interest is the measurement of the energy modulation induced to the beam itself by means of the generated wakefields in plasma. It will reflect the key properties of the accelerating electric fields such as their magnitude and their phase velocity, both of significant importance in the design of experiments relying on this technique.

title: Design considerations for a laser‐plasma linear collider
abstract: Design considerations for a next‐generation electron‐positron linear collider based on laser‐plasma‐accelerators are discussed. Several of the advantages and challenges of laser‐plasma‐based accelerator technology are addressed. An example of the parameters for a 1 TeV laser‐plasma‐based collider is presented.

title: Long-range persistence of femtosecond modulations on laser-plasma-accelerated electron beams.
abstract: Laser plasma accelerators have produced femtosecond electron bunches with a relative energy spread ranging from 100% to a few percent. Simulations indicate that the measured energy spread can be dominated by a correlated spread, with the slice spread significantly lower. Measurements of coherent optical transition radiation are presented for broad-energy-spread beams with laser-induced density and momentum modulations. The long-range (meter-scale) observation of coherent optical transition radiation indicates that the slice energy spread is below the percent level to preserve the modulations.

title: Generation of single pulse particle beams in a plasma channel by laser injection in laser wakefield accelerators
abstract: A laser injection mechanism that generates a single pulse, high quality beam is described. In the past, different all-optical injection schemes for the generation of ultrashort electron bunches were proposed. A very promising scheme proposed by E. Esarey [E. Esarey, R.F. Hubbard, W.P. Leemans A. Ting and P. Sprangle,"  (1997)] uses the collision of two counterpropagation laser pulses to inject particles. However, the results of ours 2D particle-in-cell (PIC) simulations have shown that in addition to the bunch created by pulse collision, a train of pulses is also generated by a different mechanism. In this paper we show that is possible to achieve a single pulse, high quality beam if the generation of the plasma wakefield takes place in a channel and particles are injected by a phase-kick mechanism [J. Cary at this conference]. We have performed 2D PIC simulations of our proposed injection scheme using the code VORPAL [C. Nieter at this conference]. We have obtained a high quality 11 MeV., 6 fs. single electron bunch with energy spread of 4% and emittance of 0.01/spl pi/ - mm - mrad.

title: High Quality Electron Bunches up to 1 GeV from Laser Wakefield Acceleration at LBNL
abstract: Experiments at the LOASIS laboratory of LBNL have demonstrated production of 100 MeV to 1 GeV electron bunches with low energy spread and low divergence from laser wakefield acceleration. The radiation pressure of a 10 TW laser pulse, guided over 10 diffraction ranges by a few‐mm long plasma density channel, was used to drive an intense plasma wave (wakefield), producing electron bunches with energies on the order of 100 MeV and acceleration gradients on the order of 100 GV/m. Beam energy was increased from 100 MeV to 1 GeV by using a few‐cm long guiding channel at lower density, driven by a 40 TW laser, demonstrating the anticipated scaling to higher beam energies. Particle simulations indicate that the low energy spread beams were produced from self‐trapped electrons through the interplay of trapping, loading, and dephasing. Other experiments and simulations are also underway to control injection of particles into the wake, and hence improve beam quality and stability further.

title: Mono-Energetic Beams from Laser Plasma Interactions
abstract: A laser driven wakefield accelerator has been tuned to produce high energy electron bunches with low emittance and energy spread by extending the interaction length using a plasma channel. Wakefield accelerators support gradients thousands of times those achievable in RF accelerators, but short acceleration distance, limited by diffraction, has resulted in low energy beams with 100% electron energy spread. In the present experiments on the L’OASIS laser, the relativistically intense drive pulse was guided over 10 diffraction ranges by a plasma channel. At a drive pulse power of 9 TW, electrons were trapped from the plasma and beams of percent energy spread containing > 200 pC charge above 80 MeV and with normalized emittance estimated at < 2 π-mm-mrad were produced. Data and simulations (VORPAL code) show the high quality bunch was formed when beam loading turned off injection after initial trapping, and when the particles were extracted as they dephased from the wake. Up to 4 TW was guided without trapping, potentially providing a platform for controlled injection. The plasma channel technique forms the basis of a new class of accelerators, with high gradients and high beam quality.

title: Lattice calculation of composite dark matter form factors
abstract: Composite dark matter candidates, which can arise from new strongly-coupled sectors, are well-motivated and phenomenologically interesting, particularly in the context of asymmetric generation of the relic density. In this work, we employ lattice calculations to study the electromagnetic form factors of electroweak-neutral dark-matter baryons for a three-color, QCD-like theory with Nf = 2 and 6 degenerate fermions in the fundamental representation. We calculate the (connected) charge radius and anomalous magnetic moment, both of which can play a significant role for direct detection of composite dark matter. We find minimal Nf dependence in these quantities. We generate mass-dependent cross-sections for dark matter-nucleon interactions and use them in conjunction with experimental results from XENON100, excluding dark matter candidates of this type with masses below 10 TeV.

title: Twelve fundamental and two sextet fermion flavors
abstract: We report extended simulation results and their new analysis in two important gauge theories with twelve fermion flavors in the fundamental SU(3) color representation and two fermions in the sextet representation. We probe the $N_f=12$ model with respect to the conformal window using mass deformed finite size scaling (FSS) theory driven by the fermion mass anomalous dimension. Our results at fixed gauge coupling show problems with the conformal scenario of the $N_f=12$ model. In the sextet model with two flavors, under the conformal hypothesis, we determine large values for the anomalous fermion mass dimension with $\gamma\geq 1$. Since our sextet analysis favors the chiral symmetry breaking hypothesis without conformality, the large exponent $\gamma$ could play an important role in understanding the composite Higgs mechanism. The new results discussed here include our extended data sets and exceed what was presented at the conference.

title: Nearly conformal electroweak sector with chiral fermions
abstract: SU(3) gauge theory with dynamical overlap fermions in the 2-index symmetric (sextet) representation is considered. This model may be a viable model of the electroweak symmetry breaking sector along the lines of the walking technicolor paradigm. The number of fermion species is chosen such that the theory is expected to be below the conformal window. We will discuss how the epsilon-regime and random matrix theory can be used to test whether at any given set of parameters (N_c, N_f, representation) the theory is in the conformal phase or indeed just below it. Quenched Monte Carlo results are included in the fundamental representation and also preliminary dynamical ones in the 2-index symmetric representation.

title: Conformal finite size scaling of twelve fermion flavors
abstract: Extended simulation results and their analysis are reported in a strongly coupled gauge theory with twelve fermion flavors in the fundamental SU(3) color representation. The conformality of the model is probed using mass deformed conformal finite size scaling (FSS) theory driven by the fermion mass anomalous dimension. Two independent conformal FSS fitting procedures are used in the analysis. The first one deploys physics motivated scaling functions, complemented by a second fitting procedure with spline based general B-forms for the scaling functions. The results at fixed gauge coupling show unresolved problems with the conformal hypothesis.

title: Calculating the running coupling in strong electroweak models
abstract: One possibility for Beyond Standard Model physics is a new strongly-interacting gauge theory. One way to determine if a non-abelian gauge theory is QCD-like or conformal is to measure the running of the renormalized gauge coupling. We define the renormalized coupling from Wilson loop ratios, and measure these ratios via lattice simulations. We test this method in SU(3) pure gauge theory and show some first results for simulations with dynamical fermions in the fundamental representation.