Particle Physics Group

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High Energy Physics Seminars 2004

Seminars 2003 page


Schuster Colloquia: 2.30-3.30pm, Bragg Lecture Theatre

Normal seminar coordinates: Wednesdays 2-3pm, Moseley Lecture Theatre


Wednesday 4 Feb Prof Otto Nachtmann (Heidelberg) Theory

Towards a nonperturbative foundation of the dipole picture   (Abstract)

Wednesday 11 Feb, 2.30pm Prof Ed Hinds (Imperial)    SCHUSTER COLLOQUIUM

Quantum gases in microscopic traps   (Abstract)

Thursday 12 Feb, 3pm, 2nd Floor Seminar Room Prof Ed Hinds (Imperial) Experiment

Electric dipole moments: a search for new physics  (ppt only)

Tuesday 17 Feb, 2-3pm Dr Stefan Gieseke (Cambridge)Blackett Lecture Theatre Theory

The new MC generator Herwig++   (Abstract)

Wednesday 18 Feb, 2.30pm Prof Anthony Leggett (Illinois)    SCHUSTER COLLOQUIUM

Testing the limits of quantum mechanics: motivation, state of play, prospects   (Abstract)

Wednesday 3 March Simon Dean (Manchester) Experiment

Once in a Lifetime: Investigating Z -> tau tau -> e mu at D0   (Abstract)

Wednesday 10 March Dr Peter Richardson (Durham - IPPP) Phenomenology

Simulation of multi-jet and lepton final states   (Abstract)

Wednesday 17 March, 2.30pm Prof R J Young (UMIST/VUM)    SCHUSTER COLLOQUIUM

Racing cars, spiders and Nanotubes   (Abstract)

Wednesday 24 March Dr B. Todd Huffman (Oxford) Experiment

Why B Physics is Interesting (with a CDF focus)   (Abstract)

Thursday 22 April Jozef Dudek (Oxford)
Niels Bohr Common Room
Theory

Pentaquark Phenomenology - Further States, Decay Systematics and Dynamics   (Abstract)

Wednesday 28 April, 2.30pm Prof Ray Bishop (UMIST)    SCHUSTER COLLOQUIUM

Confronting the Quantum Many-Body Problem   (Abstract)

Thursday 29 April Dr David Bugg (RAL) Niels Bohr Common Room Experiment

Four sorts of mesons   (Abstract)

Wednesday 5 May Dr Thomas Teubner (Liverpool) Theory

Testing the Standard Model at highest precision: g-2 of the muon and alpha_QED(M_Z)   (Abstract)

Wednesday 12 May Dr Georg Weiglein (Durham) Theory

Higgs Physics and Supersymmetry at Present and Future Colliders   (Abstract)

Wednesday 19 May Dr Kenneth Long (Imperial College)
Bragg Lecture Theatre
Experiment

Neutrino factory: motivation, machine and MICE   (Abstract)

Thursday 20 May Prof Tony Signal (Massey Univ, NZ)
2pm, Niels Bohr Common Room
Theory

Symmetry Breaking in Quark Distributions of the Proton   (Abstract)

Wednesday 26 May Bragg Lecture Theatre
Yaw Ming Chia          
My Project, PAW and I   (Abstract)
Shiv Kaushal
Grid Security and Accounting   (Abstract)

Wednesday 2 June Bragg Lecture Theatre
Christina Edgar          
Particle Identification at BaBar: establishing what's what!   (Abstract)
Yu-Hsiang Lin
Study of the Central Tracker at DØ Run II   (Abstract)
Will Plano
Better particle identification by the dE/dx method   (Abstract)

Thursday 10 June Bragg Lecture Theatre
Andrew Pilkington
Diffractive Processes at the LHC   (Abstract)
Muhammad Shahzad
Common Mode Noise in the ATLAS SCT silicon detector   (Abstract)
Hassan Chagani
The Scalar Top at TESLA   (Abstract)


Abstracts

4 Feb. O Nachtmann:
We study real and virtual photon-photon scattering in a nonperturbative framework and classify different contributions to this process. We investigate the approximations and assumptions that are necessary to derive something like the dipole model of high energy scattering from a generally nonperturbative description. We find that the naive dipole model formula has to be supplemented by an extra term describing rescattering corrections of the quark and antiquark forming the colour dipole.

11 Feb. E Hinds:
Clouds of cold atoms, collected and refrigerated by laser light, can be cooled to the lowest temperatures in the universe. This has created the new field of atom optics where cold atoms are manipulated, much as photons are controlled in traditional optics using mirrors, lenses, and waveguides. I will show some of the first movies of atom clouds being manipulated. From the viewpoint of basic science these clouds are a fantastic new tool for studying the quantum physics of gases close to absolute zero.

It is now becoming possible to confine and manipulate atoms and Bose Einstein condensates in extremely small traps and single-mode matter wave guides that are only ~10-8m across. Atoms flowing in such microscopic traps and tubes could provide the basis for a new technology similar to electronics but based on the flow and interaction of neutral atoms rather than on electricity in wires. I will describe how atom "chips" are being realised and how these might lead to sensitive new devices including integrated atom interferometers and perhaps quantum information processors.

17 Feb. S Gieseke:
The Monte Carlo event generator Herwig++ 1.0 for e+e- Annihilation is presented. Herwig++ is a complete rewrite of the existing Fortran program HERWIG. I will explain the underlying formalism of the new parton shower and the improvements that have been made in comparison to HERWIG. We have tested the program against a wide range of LEP data. I present these results and give an overview over planned future developments.

18 Feb. A Leggett:
I present the motivation for experiments which attempt to generate, and verify the existence of quantum superpositions of two or more states which are by some reasonable criterion "macroscopically" distinct and show that various a priori objections to this program made in the literature are flawed. I review the extent to which such experiments currently exist in the areas of free-space molecular diffraction, magnetic biomolecules, quantum optics and Josephson devices, and sketch possible future lines of development of the program.

3 Mar. S Dean:
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 studying this effect and the current best method of signal selection is presented.

10 Mar. P Richardson:
Following a brief review of the approximations and models involved in Monte Carlo simulations I will discuss recent progress in the simulation of high multiplicity final states from both particle decays and QCD radiation. These are important in the simulation of processes such as top production at the Tevatron and the search for new physics at the LHC.

17 Mar. R Young:
The presentation will be concerned with the relationships between structure and properties of high-performance fibrous materials. Spectacular advances have been made in the field of fibre-reinforced composite materials to underpin the technology of the modern Formula 1 racing car. Such composites materials have unprecedented levels of stiffness and strength being as strong and stiff as steel but with only a fraction of the density.

Silk is a protein-based polymer fibre that is employed widely by arthropods (spiders and insects) and a particularly strong version of spider silk, the dragline only 2 microns in diameter, can support the entire weight of a spider.

Carbon nanotubes are a newly-discovered fibrous form of carbon that are responsible in part for the development of "nanotechnology". The interest in single-wall carbon nanotubes has increased steadily since their discovery in 1993, due to their exceptional electronic and mechanical properties. Their outstandingly high Young's modulus (about 1 TPa and similar to diamond) and their structure-dependent electronic properties make them ideal candidates for applications ranging from nanoscale sensors to satellite tethers.

24 Mar. BT Huffman:
B physics is being pursued in many places around the world. There are detailed results coming from both hadronic and leptonic colliders on the masses, branching ratios, lifetimes, and the presence of mixing and CP violation from a variety of decay modes. There are even discoveries of new hadronic bound states. But through all of these detailed measurements it is important to realise that the Bottom quark provides us with an important and unique window on realms of physics that are far-removed from the relatively low energies required for its production. In this talk I will emphasize those aspects of B physics that may well help us to limit and define what laws govern nature beyond the standard model along with the results of the CDF experiment that are setting some of those limits.

22 April, J Dudek:
I will discuss the growing phenomenology of pentaquarks with particular emphasis on experimental observations which can discriminate between models.

Quark-based models have been proposed in which the pentaquark contains one unit of orbital angular momentum. In such pictures the $\theta$ is partnered by a spin-3/2 baryon with a mass separation dictated by spin-orbit forces. I will outline a model in which we find a small splitting. The existence of such a partner state would pose questions for the Chiral Soliton Model.

In general it is difficult to distinguish between a non-exotic pentaquark and a conventional baryon resonance. I will demonstrate that the flavour structure of certain pentaquark models is such that there are selection rules for the decay of pentaquarks that would not apply for three-quark states.

Finally, I will briefly present a simple quark model in which, it seems, one can find a realisation of the pentaquark structure proposed by Jaffe & Wilczek.

28 April, R Bishop:
Examples of quantum many-body systems abound in Nature. Thus, it is clear that in fields like molecular, solid-state, and nuclear physics most of the fundamental objects of discourse are interacting many-body systems. But even in elementary particle physics one is usually dealing with more than one particle. For example, at some level of reality a nucleon comprises three quarks interacting via gluons and surrounded by a cloud of mesons, which are themselves made of quark-antiquark pairs. Even more fundamentally, even the “physical vacuum” of any quantum field theory is endowed with an enormously complex infinite many-body structure due to virtual excitations. A key central role in modern physics is thus occupied by quantum many-body theory, where we are especially interested in the possible existence of any universal techniques that are powerful enough to treat the full range of many-body and field-theoretic systems. One such method is the coupled cluster method. This has become one of the most pervasive, most powerful, and most successful of all fully microscopic formulations of quantum many- body theory. It has probably been applied to more systems in quantum field theory, quantum chemistry, nuclear, subnuclear, condensed matter and other areas of physics than any other competing method. It has yielded numerical results which are among the most accurate available for an incredibly wide range of both finite and extended systems on either a spatial continuum or a regular discrete lattice. In this talk I aim to give an overview of the method itself and some illustrative examples of its power and range of applicability.

29 April, D Bugg:
The overall status of light q-qbar mesons, glueballs, hybrids and the light scalars will be sketched.

Crystal Barrel data identify a simple and fairly complete spectrum of q-qbar mesons up to 2400 MeV. In addition there are six `extra' states. Four of them coincide well with Lattice QCD predictions for the four lightest glueballs. Two others are candidates for a pair of JPC = 2-+ hybrids.

The light scalars Sigma, Kappa, f0(980) and a0(980) appear to make a nonet of weakly bound states resembling the deuteron.

5 May, T Teubner:
The anomalous magnetic moment of the muon is discussed, paying particular attention to the evaluation of the hadronic contributions. Confronted with the latest measurement from BNL, the Standard Model prediction currently shows a 2.7 sigma deviation, allowing -- but at the same time constraining -- new physics. I also present a new result for alpha_QED(M_Z) which influences the indirect determination of the Higgs mass from fits of electroweak precision observables.

12 May, G Weiglein:
The present status of precision tests of the electroweak Standard Model (SM) is summarised and the resulting indirect constraints on the mass of the SM Higgs boson are discussed. In the Minimal Supersymmetric extension of the Standard Model (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 at the next generation of colliders is discussed. The possible interplay between the LHC and a future Linear Collider in analysing the mechanism of electroweak symmetry breaking and the underlying structure of Supersymmetric models is investigated.

19 May, K Long:
The discovery of neutrino oscillations implies that neutrinos are massive and that the Standard Model is incomplete, making the neutrino sector the only window on physics beyond the Standard Model that is presently accessible. The worldwide consensus is that only a Neutrino Factory - an intense high-energy neutrino source derived from the decay of a stored muon beam - will be adequate for the requisite precision studies. The physics case for the Neutrino Factory will be reviewed briefly and the layout of the facility summarised. The critical components of the facility are the proton driver, the pion-production target and collection system, the ionisation cooling channel and the muon acceleration system. These components will be reviewed and the status and plans of the relevant R&D programmes described. A key component of the machine R&D is the demonstration of ionisation cooling using the Muon Ionisation Cooling Experiment (MICE). The status of MICE will be described in detail.

20 May, A Signal:
Symmetries play a key role in modern physics, especially in the understanding of the strong interaction. Over the past fifteen years deep inelastic experiments have observed the breaking of a number of quark model symmetries. The problem I shall address is whether these observations at can tell us anything new about the non-perturbative physics that governs the structure of the proton. I shall introduce the meson cloud model, which allows the calculation of a number of symmetry breaking effects within a single framework, and compare predictions of the model with recent experimental data.

26 May, Y M Chia:
In this talk I will talk on my journey in becoming a particle physicist and the interesting things that I have met. I will talk about one of them here. I will also mention briefly what I am doing now and the benefits of being a PAW fan.

26 May, S Kaushal:
A brief introduction to the Grid and a look at some of the Grid related work being done in Manchester. GridSite is introduced and the security aspects discussed in detail. Accounting and accounting issues are also introduced.

2 June, C Edgar:
Reliably identifying particles is crucial in any analysis. The idea behind "bitwords" and the particle identification selectors they describe at BaBar are introduced. The role of Monte Carlo truth lists is also discussed. As a case study, preliminary research into identifying pions for the tau->5pi analysis is described.

2 June, Y-S Lin:
The performance of the central tracker for advanced tracking studies at DØ is reported. This upgrade version is used by the new package, l1ft2b.

Comparison of different samples from Monte Carlo is made, l1ft2b is also optimized and tracking efficiency of 98% is found using various equations to simulate the real tracking algorithm. Finally, an investigation of how to smear the fake rate down to 2% is presented.

2 June, W Plano:
A look at the process of estimation, maximum likelihood, minimum variance and a possibility of improving the resolution of dE/dx measurements. I will present my latest data on the subject and hopefully show that the prognosis is not as bad as it seems.

10 June, A Pilkington:
Measuring diffractive Higgs production by tagging protons in roman pot type detectors results in very good mass resolution and a reduction in the relevant backgrounds. The diffractive mechanism will be presented, along with the current best estimates in some of the background processes.

10 June, M Shahzad:
Common Mode Noise (CMN) is of particular concern in the analysis of binary data obtained from analogue signals which is effected by coherent distortions. The ATLAS SCT silicon detector is an example of such a system. CMN can create artificial hit patterns. Therefore, it is vital for a digital system to have negligible CMN. However CMN can only be estimated on a statistical basis, analysing some sample events. Gaussian CMN is most difficult to detect.

10 June, H Chagani:
The discovery potential of the scalar top from photon collisions is investigated at the TESLA collider looking in detail at the decay ~t -> t ~X^{0}. Various techniques are employed in an attempt to reduce the main background of top quark pair production, which happens to be a golden channel process at TESLA. Unfortunately, the same cannot be said for stop pair production.
Notes:
For help with AV equipment: Joe Lee, ext 54038 (please give 2-3 days notice)


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