119235558
Renormalization group equations and matching in a general quantum field theory with kinetic mixing
Abstract We work out a set of simple rules for adopting the two-loop renormalization group equations of a generic gauge field theory given in the seminal works of Machacek and Vaughn to the most general case with an arbitrary number of Abelian gauge factors and comment on the extra subtleties possibly encountered upon matching a set of effective gauge theories in such a framework.
31040253
Calculating the renormalisation group equations of a SUSY model with Susyno
Susyno is a Mathematica package dedicated to the computation of the 2-loop renormalisation group equations of a supersymmetric model based on any gauge group (the only exception being multiple U(1) groups) and for any field content. Supersymmetry (SUSY) is an elegant and well known extension of the Standard Model (SM) which aims at solving or softening some of the SM theoretical and experimental shortcomings. Supersymmetric models based on Grand Unified Theories (GUTs) offer the appealing feature of being described by a unique gauge group and coupling constant; furthermore, the potential new superfields, as well as their dynamics, can provide answers to fundamental problems. For example SO(10) based models offer a natural explanation for neutrino masses and mixings via a type-I seesaw. This occurs since the spinor representation of the group contains a SM singlet superfield (with the appropriate quantum numbers). Even larger and/or more complex groups are often considered, for example E6 in string inspired models. The analysis of the theoretical and phenomenological implications of SUSY GUT models requires a careful study of the evolution of the fundamental parameters from the high-energy scale down to the electroweak scale, at which observables are computed and constraints applied. As such, knowledge of the renormalisation group equations (RGEs) is necessary. Although the RGEs of several models (e.g., MSSM, NMSSM) are already known [1, 3], for other SUSY extensions of the SM complicated general equations must be used [1, 2]. Here we describe Susyno, a Mathematica-based package that addresses this issue. The program takes as input the gauge group, the representations (i.e., the chiral superfield content), the number of flavours/copies 1 of each representation, and any abelian discrete symmetries (e.g., R-parity). Susyno then constructs the most general superpotential and soft SUSY breaking Lagrangian consistent with the field content and symmetries imposed. Once these elements have been derived, Susyno then computes the 2-loop �-functions of all the parameters of the model, which is its main output.
118530599
Running soft parameters in SUSY models with multiple U(1) gauge factors
Abstract We generalize the two-loop renormalization group equations for the parameters of the softly broken SUSY gauge theories given in the literature to the most general case when the gauge group contains more than a single Abelian gauge factor. The complete method is illustrated at two-loop within a specific example and compared to some of the previously proposed partial treatments.
118081166
Renormalization in supersymmetric models
There are reasons to believe that the Standard Model is only an effective theory, with new Physics lying beyond it. Supersymmetric extensions are one possibility: they address some of the Standard Model's shortcomings, such as the instability of the Higgs boson mass under radiative corrections. In this thesis, some topics related to the renormalization of supersymmetric models are analyzed. One of them is the automatic computation of the Lagrangian and the renormalization group equations of these models, which is a hard and error-prone process if carried out by hand. The generic renormalization group equations themselves are extended so as to include those models which have more than a single abelian gauge factor group. Such situations can occur in grand unified theories, for example. For a wide range of SO(10)-inspired supersymmetric models, we also show that the renormalization group imprints on sparticle masses some information on the higher energies behavior of the models. Finally, in some cases these theories introduce charged lepton flavor violating interactions, which can change the ratio $\Gamma\left(K\rightarrow e\nu\right)/\Gamma\left(K\rightarrow\mu\nu\right)$. In light of experimental bounds on other observables, our analysis shows that any change over the Standard Model prediction must be smaller than the current experimental sensitivity on this observable.
118680546
Revisiting the $\Gamma(K \to e \nu)/\Gamma(K \to \mu \nu)$ ratio in supersymmetric unified models
It has been pointed out that supersymmetric extensions of the Standard Model can induce significant changes to the theoretical prediction of the ratio $\Gamma(K\rightarrow e\nu)/\Gamma (K\rightarrow\mu\nu)\equiv R_{K}$, through lepton flavour violating couplings. In this work we carry out a full computation of all one-loop corrections to the relevant $\nu\ell H^{+}$ vertex, and discuss the new contributions to $R_{K}$ arising in the context of different constrained (minimal supergravity inspired) models which succeed in accounting for neutrino data, further considering the possibility of accommodating a near future observation of a $\mu\to e\gamma$ transition. We also re-evaluate the prospects for $R_{K}$ in the framework of unconstrained supersymmetric models. In all cases, we address the question of whether it is possible to saturate the current experimental sensitivity on $R_{K}$ while in agreement with the recent limits on $B$-meson decay observables (in particular BR($B_{s}\to\mu^+\mu^-$) and R($B_{u}\to\tau\nu$)), as well as BR($\tau\to e \gamma$) and available collider constraints. Our findings reveal that in view of the recent bounds, and even when enhanced by effective sources of flavour violation in the right-handed $\tilde{e}-\tilde{\tau}$ sector, constrained supersymmetric (seesaw) models typically provide excessively small contributions to $R_{K}$. Larger contributions can be found in more general settings, where the charged Higgs mass can be effectively lowered, and even further enhanced in the unconstrained MSSM. However, our analysis clearly shows that even in this last case SUSY contributions to $R_{K}$ are still unable to saturate the current experimental bounds on this observable, especially due to a strong tension with the $B_{u}\to\tau\nu$ bound.
118851022
Kinetics of Particles in Relativistic Collisionless Shocks
Charged plasma particles form an anisotropic counter-streaming distribution at the front of a shock. In the nearand ultra-relativistic regimes, Weibel (or twostream) instability produces near-equipartition, chaotic, small-scale magnetic fields. The fields introduce effective collisions and “thermalize” the plasma particles via pitch-angle scattering. The properties of jitter radiation emitted by accelerated electrons from these small-scale fields are markedly different from synchrotron spectra. Here we theoretical summary and the results of recent numerical 3D PIC plasma kinetic simulations. The relation of the obtained results to the theory of gamma-ray bursts is outlined.
28592387
Ion motion in self-modulated plasma wakefield accelerators.
The effects of plasma ion motion in self-modulated plasma-based accelerators are examined. An analytical model describing ion motion in the narrow beam limit is developed and confirmed through multidimensional particle-in-cell simulations. It is shown that the ion motion can lead to the early saturation of the self-modulation instability and to the suppression of the accelerating gradients. This can reduce the total energy that can be transformed into kinetic energy of accelerated particles. For the parameters of future proton-driven plasma accelerator experiments, the ion dynamics can have a strong impact. Possible methods to mitigate the effects of the ion motion in future experiments are demonstrated.
15403869
3D simulations of pre-ionized and two-stage ionization injected laser wakefield accelerators
In plasma based accelerators (LWFA and PWFA), the methods of injecting high quality electron bunches into the accelerating wakefield is of utmost importance for various applications. To fully understand the numerical effect of simulating the trapping process, numerous numerical convergence tests were performed to ensure the correctness of preionized simulations which confirm the physical picture first proposed in [1]. We Further investigate the use of a two-stage ionization injected LWFA to achieve high quality monoenergetic beams through the use of 3D PIC simulations. The first stage constitutes the Injection Regime, which is 99.5% He and 0.5% N, while the second stage constitutes the Acceleration Regime, which is entirely composed of He. Two of the simulations model the parameters of the LWFA experiments for the LLNL Callisto laser, at laser powers of 90 and 100TW. energies as high as 680MeV were observed in the 90TW simulation, and those as high as 1.44GeV were observed in the 100TW simulation. The aff...
2877366
Very high Mach-number electrostatic shocks in collisionless plasmas.
The kinetic theory of collisionless electrostatic shocks resulting from the collision of plasma slabs with different temperatures and densities is presented. The theoretical results are confirmed by self-consistent particle-in-cell simulations, revealing the formation and stable propagation of electrostatic shocks with very high Mach numbers (M>>10), well above the predictions of the classical theories for electrostatic shocks.
108655217
Modeling of E‐164X Experiment
In current plasma‐based accelerator experiments, very short bunches (100–150μm for E164 and 10–20 μm for E164X experiment at Stanford Linear Accelerator Center (SLAC)) are used to drive plasma wakes and achieve high accelerating gradients, on the order of 10–100GV/m. The self‐fields of such intense bunches can tunnel ionize neutral gases and create the plasma. This may completely change the physics of plasma wakes. A 3‐D object‐oriented fully parallel PIC code OSIRIS is used to simulate various gas types, beam parameters, etc. to support the design of the experiments. The simulation results for real experiment parameters are presented.