arXiv subjects

M. S. Brown

Publications and source records attributed to M. S. Brown.

7 recordsLinked to original sources

arXiv2018

Oscillator Strengths for Ultraviolet Transitions in P II -The Multiplet at 1308 Å

We report lifetimes, branching fractions, and the resulting oscillator strengths for transitions within the P II multiplet (3s23p2 3P - 3s3p3 3Po) at 1308 Å. These comprehensive beam-foil measurements, which are the most precise set currently available experimentally, resolve discrepancies involving earlier experimental and theoretical results. Interstellar phosphorus abundances derived from λ1308 can now be interpreted with greater confidence. In the course of our measurements, we also obtained an experimental lifetime for the 3p4s 3P0o level of P IV. This lifetime agrees well with the available theoretical calculation.

physics.atom-ph↗

arXiv2017

An extended model of the quantum free-electron laser

Previous models of the quantum regime of operation of the Free Electron Laser (QFEL) have performed an averaging and the application of periodic boundary conditions to the coupled Maxwell - Schrodinger equations over short, resonant wavelength intervals of the interaction. Here, an extended, one-dimensional model of the QFEL interaction is presented in the absence of any such averaging or application of periodic boundary conditions, the absence of the latter allowing electron diffusion processes to be modeled throughout the pulse. The model is used to investigate how both the steady-state (CW) and pulsed regimes of QFEL operation are affected. In the steady-state regime it is found that the electrons are confined to evolve as a 2-level system, similar to the previous QFEL models. In the pulsed regime Coherent Spontaneous Emission (CSE) due to the shape of the electron pulse current distribution is shown to be present in the QFEL regime for the first time. However, unlike the classical case, CSE in the QFEL is damped by the effects of quantum diffusion of the electron wavefunction. Electron recoil from the QFEL interaction can also cause a diffusive drift between the recoiled and non-recoiled parts of the electron pulse wavefunction, effectively removing the recoiled part from the primary electron-radiation interaction.

physics.acc-ph↗

arXiv2014

Composite Higgs searches at the LHC and beyond

General Composite Higgs models provide an elegant solution to the hierarchy problem present in the Standard Model and give an alternative pattern leading to the mechanism of electroweak (EW) symmetry breaking. We present an analysis of a realistic realization of this general idea, namely the 4DCHM, analysing the Higgs production and decay modes, fitting them to the latest LHC showing the compatibility with the results of the CERN machine. We then present the prospects of a future electron positron collider of testing this model against the expected experimental accuracies in the various Higgs decay channels accessible herein.

hep-ph↗

arXiv2013

Higgs Boson in the 4DCHM: LHC phenomenology

Composite Higgs models provide an elegant solution to the hierarchy problem present in the Standard Model (SM) and give an alternative pattern leading to the mechanism of Electro-Weak Symmetry Breaking (EWSB). We present an analysis of the Higgs boson production and decay within a recently proposed realistic realization of this general idea: the 4D Composite Higgs Model (4DCHM). Comparing our results with the latest Large Hadron Collider (LHC) data we show that the 4DCHM could provide an alternative explanation with respect to the SM of the LHC results pointing to the discovery of a Higgs-like particle at 125 GeV.

hep-ph↗

arXiv2013

The 4-Dimensional Composite Higgs Model (4DCHM) and the 125 GeV Higgs-like signals at the LHC

We show that the 4-Dimensional Composite Higgs Model (4DCHM) could provide an even better explanation than the Standard Model (SM) of the current Large Hadron Collider (LHC) data pointing to the discovery of a neutral Higgs boson. The full particle spectrum of this scenario is derived without any approximation and implemented in automated computational tools to enable fast phenomenological investigation. Several benchmark sets compliant with the aforementioned data are presented and discussed.

hep-ph↗

arXiv2013

The Higgs sector of the 4DCHM after the XLVIII Rencontres de Moriond

In this proceeding, we present the current status of a $χ^2$ fit extracted from the profiling of the Higgs couplings performed at the LHC in the context of the 4-Dimensional Composite Higgs Model. Especially, we consider the data presented by the ATLAS and CMS collaborations during the XLVIII Rencontres de Moriond.

hep-ph↗

arXiv2013

A 4D Composite Higgs Model: Testing its Scalar Sector at the LHC

We explain the current Large Hadron Collider (LHC) data pointing to the discovery of a neutral Higgs boson in the context of a 4-Dimensional Composite Higgs Model (4DCHM). The full particle spectrum of this scenario is derived without any approximation and implemented in automated computational tools to enable fast phenomenological investigation. Several parameter configurations compliant with experimental constraints are presented and discussed. A $χ^2$ fit to the LHC data quantifying the consistency of the 4DCHM as a whole with experimental evidence is finally performed.

hep-ph↗