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HEP Seminars

05 Apr 2020

UCL HEP Seminars 2005

07/12/2005, 3.30pm. Departmental Colloquium @ Harrie Massey : James Stirling (IPPP, Durham)

Quantum Chromodynamics and High-Energy Colliders: Fundamental Physics from Non-fundamental Particles

02/12/2005, 4pm : John Ellis (CERN)

How to look for supersymmetry?

Supersymmetry is still the most promising option for physics beyond the Standard Model, and there are good chances that it could be seen at the LHC. The experimental signature most frequently considered is missing energy, but an interesting alternative is offered by models with a metastable charged particle decaying into gravitino dark matter.

25/11/2005, 4pm : Charles Loomis (LAL Orsay)

Challenges of Analysis for Grid Computing

The LCG/EGEE production service is the largest operating grid infrastructure in the world. It is currently being used by both HEP and non-HEP applications for large scale productions. However, users wanting to run analyses on the grid will bring higher expectations and more difficult requirements with them. The presentation summarizes the current state of the grid and specific areas which will need to be improved to support analysis on grid infrastructures.

23/11/2005, 4pm. Departmental Colloquium @ Harrie Massey : Jens Als-Nielsen (Niels Bohr Institute, Copenhagen)

X-Ray synchrotron radiation - glimpses from the past and of the future

It is well known that synchrotron X-ray science - or maybe more precisely science based on X-ray synchrotron radiation (SR) - has undergone a revolution within the last couple of decades. The brilliance, the figure of merit often used for SR sources, exhibits a growth rate exceeding that of Moore~Rs law for semiconductors, and this development will continue with new large-scale projects such as the free electron X-ray laser. In this talk I shall, however, emphasize another aspect of X-ray science which will have a more direct impact on our daily lives, and that is the proliferation to universities, hospitals and companies of affordable, laser based SR sources equipped with novel X-ray optics. Amongst other benefits, this combination will allow the routine clinical use of phase-contrast imaging rather than conventional absorption-contrast imaging.

11/11/2005, 4pm : Silvia Pascoli

Determining neutrino masses

In recent years strong evidence of neutrino oscillations has been found. This implies that neutrinos are massive particles. At present, we have measured the solar and atmospheric mass squared differences but the overall neutrino mass scale and the type of hierarchy are still unknown. This information is crucial for our understanding of the origin of neutrino masses. I will review the present knowledge of neutrino parameters. I will discuss the strategies for determining the absolute values of neutrino masses (absolute mass scale and type of hierarchy). In particular, I will focus on neutrinoless double beta decay and long baseline experiments and, briefly, on direct mass searches. I will finally comment on the complementarity of these different approaches.

04/11/2005, 4pm : Oliver Rosten (Southampton)

Computing in SU(N) Yang-Mills without Fixing the Gauge

A manifestly gauge invariant Exact Renormalisation Group is constructed for SU(N) Yang-Mills, in a form convenient for computation at any loop order. A diagrammatic calculus is developed which facilitates a calculation of the two-loop beta function, for the first time without fixing the gauge or specifying the details of the regularisation scheme.

Wed 26/10/2005, 6pm. Departmental Colloquium @ Harrie Massey : Steve Jones (UCL)

Did Adam meet Eve? - the view from the genes

14/10/2005, 4pm : Alan Barr (UCL)

SUSY or extra dimensions? Can we find out with ATLAS?

Two of the most widely talked-about extensions to the Standard Model are supersymmetry and extra spatial dimensions. If applicable at the TeV-scale, both could be discovered at the LHC. However the signals from some extra dimensional models share many of the properties of supersymmetric events. I discuss some recent work which shows that ATLAS has the potential to distinguish between such models.

07/10/2005, 4pm : Hans Drevermann (CERN)

Data oriented projections in the ATLAS event display ATLANTIS

Based on simulated data of the two inner 3D tracking chambers of ATLAS, it will be shown that special projections of the data allow to check and understand complicated ATLAS interactions. These projections are optimized to suit human perception. The detection of the interactions and the cleaning of high luminosity data sets containing many noisy channels will be demonstrated.

17/06/2005, 4pm : Georg Weiglein (Durham)

Higgs Physics and Supersymmetry at Present and Future Colliders

Precision tests of the electroweak Standard Model (SM) and its minimal supersymmetric extension (MSSM) are analysed, and indirect constraints on the Higgs-boson mass in the SM and the scale of supersymmetry are discussed. In the MSSM the mass of the lightest Higgs boson is not a free parameter as in the SM, and a firm upper bound can be established. The phenomenology of Higgs physics in the MSSM can differ very significantly from the SM case. The phenomenology of Higgs physics in the MSSM at the Tevatron, the LHC and the ILC is discussed. The possible interplay between the LHC and ILC in analysing the mechanism of electroweak symmetry breaking and the underlying structure of Supersymmetric models is investigated.

03/06/2005, 4pm : Edwige Tournefier (Annecy)

Gravitational waves and the VIRGO detector

Gravitational waves are predicted by general relativity but have not yet been experimentally observed. A new generation of interferometric experiments aimed at their detection, such as Virgo, is now being commissioned. After an introduction on gravitationnal waves I will give an overview of the world programme before focusing on the Virgo detector and its commissioning.

Exceptionally on Tuesday 31/05/2005, 11am at Cruciform Seminar Room 2 : Wit Busza (MIT)

Surprises from RHIC

20/05/2005, 4pm : Claire Gwenlan (Oxford)

QCD analyses of HERA data: determination of proton PDFs

13/05/2005, 4pm : Lucio Cerrito (Oxford)

Top Quark Physics at the Tevatron

The observation of top quarks is still an exclusive privilege of only two experiments operating at the Tevatron Collider. However, never forming bound states, rapidly decaying and with unmeasurably small rare decays the top may appear like a rather uninteresting specie. Or is it ? I will review the latest measurements in top physics at the Tevatron, with focus on the CDF experiment. It emerges a rich programme that is currently testing the Standard Model at the highest energy ever reached in laboratory.

06/05/2005, 4pm : Simon Dean (UCL)

Once in a lifetime: Investigating Z -> tau tau -> e mu + neutrinos at D0

The sum of signed impact parameters in a two-track system is proposed as a tool for discriminating channels with lifetime in the final state. Z ->tau tau -> e mu is shown to be a realistic process for demonstrating this effect and a signal sample is selected from the D0 RunII dataset.

22/04/2005, 4pm : Emily Nurse (UCL)

Electroweak physics at the Tevatron

Run II of the Tevatron is now well underway and results are starting to come out thick and fast. I will present the recent electroweak results from CDF and Dzero, going through one analysis in detail to give some insight into how precision measurements are done at hadron colliders.

15/04/2005, 4pm : Philip Burrows (QMUL)

The Linear Collider: microscope on physics at the TeV scale

I will discuss the power of the Linear Collider in terms of precision measurements and discovery potential for new physics at the TeV scale. I will discuss the joint potential of the Linear Collider and the LHC. I will review briefly the status of the International Linear Collider project and the UK contributions.

Exceptionally on Monday 04/04/2005, 4pm : Chris Quigg (FermiLab)

The Double Simplex; envisioning particles and interactions

Exceptionally on Tuesday 01/03/2005, 4pm : Glen Marshall

Recent results from the TWIST experiment

The TRIUMF Weak Interaction Symmetry Test (TWIST) has recently completed its first physics analyses. The results represent a significant increase in precision for two of the four Michel parameters describing the energy and angle distributions of positrons from polarized positive muon decay. This is the first step toward our eventual goal of improving upon previous determinations for three of the parameters by at least an order of magnitude, as a test the Standard Model in the purely leptonic decay interaction. TWIST uses a polarized muon beam stopping at the center of a spectrometer consisting of a low mass, high precision array of planar drift chambers in a two tesla solenoidal field. The talk will focus on the operation of the device and the methods which are used to extract the decay parameters in a reliable way. Systematic uncertainties are especially important, as they will limit the final results.

25/02/2005, 4pm : Yoshi Uchida

The KamLAND experiment

18/02/2005, 4pm : Hans Kraus (Oxford)

The CRESST Dark Matter Search

Dark Matter is one of the key issues in the field of particle-astrophysics. We understand many phenomena in great detail, but yet, we do not know what the bulk of the Universe is made of. Dark Matter and Dark Energy appear to dominate normal matter by a large factor. I summarize the astrophysics evidence we have for the existence of Dark Matter; explain how particle physics provides a good candidate for Dark Matter particles and talk about the experimental challenges one has to master in attempting to detect WIMP Dark Matter. I review the general requirements every Dark Matter experiment has to satisfy and summarize some of the physics carried out within underground laboratories. The focus of the presentation is on novel cryogenic detectors that CRESST uses to search for WIMPs. These detectors are scintillating low-temperature calorimeters operating in the milli-kelvin temperature range and providing event type recognition to distinguish between a potential signal and backgrounds. The presentation concludes with a summary on how far the world-wide search for Dark Matter has progressed.

04/02/2005, 4pm : Steward Boogert (UCL)

Physics of/at a linear e+ e- collider

28/01/2005, 4pm : Philip Harris (Sussex)

The neutron EDM experiment