In this talk I shall discuss the present status of various rare Higgs decays, especially focusing on the Higgs to Z photon decay. I will discuss the blinded 2016 data and will also summarise the results from the Run I data. I will discuss the background fitting methodology adopted in this study. Besides, I will review the status of Higgs decaying to a pair of muons and to gamma* gamma . Finally, I will discuss certain well motivated exotic Higgs decays including the lepton flavour violating decays.
27/12/2017 at 3:00 pm
Dr. Mrutyunjaya Bhunya
Seminar of General Interest
IOP Lecture Hall
Document Date:
The surface properties of neutron-rich exotic nuclei : A source studying the nuclear symmetry energy
The Physics behind the Smart Cut TMProcess for thin film transfer
Abstract
Today, the Smart Cut TM technology is currently used to transfer sub-micrometer thick layers of many crystalline materials (Si, Ge, SiGe, GaN, SiC, Ferroelectrics) onto various substrates. This technology is based on the ion implantation of hydrogen and/or helium in the material to be transferred and on the bonding of this material onto another material, followed by thermal annealing.In this talk, we will review the knowledge we have recently gained of the different mechanisms by which the implanted H/He evolve during annealing finally leading to the fracture and separation of the surface layer.We will identify the different defects which play a role in this phenomenon (VnHm complexes, platelets, micro-cracks) and of the mechanisms by which they grow and eventually transform from one into the other. This discussion will be based on large collection of TEM, Raman, FTIR and X-rays data, including direct imaging of some of these transformations in situ, in the microscope. Finally, we will identify and discriminate the mechanisms driving “gentle” transformations dictated by thermodynamics (nucleation, diffusion, Ostwald ripening) from those driving “catastrophic” transformations (strain assisted coalescence, fracture propagation). Remaining questions to be answered before the full simulation of the process is thinkable will be indicated. The possible extension of this technology to the direct transfer of ultra-thin layers (<50 nm) will be discussed.
18/12/2017 at 4:00 pm
Dr. Swagata Mukherjee, RWTH Aachen University, Germany
The latest results of searches for exotic new physics from the CMS collaboration will be presented. The primary focus will be the searches of new particles decaying to leptons, including hadronically decaying tau leptons. Experimental signatures involving leptons are one of the cleanest probes of new physics at the LHC. These searches are based on proton-proton collision data at the LHC. In this talk, the status of data scouting will also be presented. CMS collaboration introduced the concept of data scouting as an alternative strategy to normal data-taking technique, allowing to take data that otherwise would be rejected by the trigger filters. This special data flow, based on event-size reduction rather than event filtering, is considered as a coherent discovery tool, and will be reviewed in this talk.
Spin Hall Effect (SHE) and its inverse enables generation, manipulation and detection of pure spin current [1,2] in heavy metal thin films. The most common heavy metal that is heavily investigated is Pt. The β-phase of Ta and W offer higher spin Hall angle [3, 4] compared to Pt. However, there is significant variation in the values of spin Hall angle reported in the literature for both Ta and W. In this work, we explore the electrical and optical detection of spin currents of sputtered Ta thin films using Spin torque ferromagnetic resonance (STFMR), inverse spin Hall effect (ISHE) and magneto-optical Kerr (MOKE) measurements. In STFMR measurement, we show an anti-damping spin-orbit torque in epitaxial-Py/β-Ta that leads to nearly 30 % modulation of the effective Gilbert damping constant. The observed torque cannot be explained using the spin Hall effect and may arise from the interface or the crystalline structure of Py thin films [5]. We demonstrate a strong correlation of measured ISHE voltage with crystalline phase of Ta thin films and found a large spin Hall angle for a mixed crystalline phase of Ta.
We optically detect spin accumulation due to the spin Hall effect in single layer Ta films by applying a square wave current and using Fourier analysis in a MOKE setup that uses spatially modulated incident light. We show that there exists a threshold current density (Jth) above which spin current can be detected via the optical technique. Jth, which is a measure of spin current efficiency, is found to be the lowest in the mixed phase of Ta and is strongly correlated with the crystalline phase of Ta [6].
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