Particle Physics Seminars Spring 2007
Seminars 2003 Seminars Spring 2004 Seminars Autumn 2004Seminars 2005 Seminars Spring 2006 Seminars Autumn 2006
Location: Moseley Lecture Theatre
Usual time: Wednesdays 2-3pm
2007 | ||
Wed 7 Feb. | Robin Marshall (Manchester) | Schuster Colloquium |
14:30 Bragg | The Inversion of Heat Capacity: A Solution to a 100 year old Problem. | |
Abstract | ||
Wed 14 Feb | Paul Newman (Birmingham) | Experiment |
14:00 Moseley | Deep Inelastic Scattering: The Structure of Nothing | |
Wed 21 Feb | Neil Spooner (Sheffield) | Experiment |
14:00 Moseley | WIMP Dark Matter Searches | |
Wed 28 Feb | Andrzej Jerzy Buras (TU Munich) | Theory |
14:00 Moseley | FCNC Processes in the Littlest Higgs Model with T-Parity | |
Abstract | ||
Mon 5 Mar. | Konstantinos Dimopoulos (Lancaster) | Astroparticle |
13:30 Bragg | Generating the Curvature Perturbation with a Vector Field | |
Abstract | ||
Wed 7 Mar. | Lucio Piccirillo (Manchester) | Schuster Colloquium |
14:30 Bragg | Detecting primordial gravitational waves through the study of 3K Cosmic Background Radiation | |
Abstract | ||
Wed 14 Mar 2007 | Chris Damerell (RAL) | Experiment |
14:00 Moseley | Vertex detectors and the linear collider | |
Abstract | ||
Tues 20 Mar 2007 | Tomislav Prokopec ( Utrecht University) | Theory |
16:00 Moseley | Decoherence of cosmological perturbations | |
Abstract | ||
Wed 21 Mar 2007 | Chris Hays (Oxford) | Experiment |
14:00 Moseley | New W Mass Results | |
Tues 24 April | Gustavo Branco (Lisbon, CFTP & IST) | Theory |
16:00 Bragg | Leptogenesis, Invariants and Low Energy Observables | |
Wed 25 Apr | Stephen Watts (Manchester) | Experiment |
14:00 Moseley | Data Visualisation in Particle Physics | |
Abstract | ||
Slides | ||
Mon 30 April | Mark Hindmarsh (Sussex) | Astroparticle |
13:30 Bragg | Cosmic Strings and the Cosmic Microwave Background | |
Abstract | ||
Wed 9 May | Malin Sjodahl (Manchester) | Theory |
14:00 Moseley | Soft gluons in Higgs plus two jet production | |
Abstract | ||
Wed 16 May | Steve Koonin (BP) | Schuster Colloquium |
14:30 Moseley | A Physicist's view of the World Energy Situation | |
** CANCELLED ** | ||
Abstract | ||
Thurs 17 May | Todd Adams (Florida State) | Experiment |
14:00 Niels Bohr | Searches for Long-lived Particles at D0 | |
Tues 29 May | Joannis Papavassiliou (Valencia) | Theory |
13:30 Niels Bohr | On Dynamical Gluon Mass Generation | |
Abstract | ||
Wed 30 May | Nick Dorey (Cambridge) | Theory |
14:00 Moseley | Integrability in Four-Dimensional Gauge Theory | |
Abstract | ||
Tue 19 June | Asoke K Nandi (Liverpool) | Experiment |
14:00 Niels Bohr | Clustering and Classification | |
Abstract | ||
Fri 22 June. | Savas Dimopoulos (Stanford) | Schuster Colloquium |
14:30 Zochonis Th.A (B.5) | Particle Physics circa 2010 | |
Abstract | ||
Mon 25 June. | Stephen West (Oxford) | Astroparticle |
13:30 Bragg | Non-Perturbative Flat Direction Decay | |
Abstract | ||
Fri 29 June. | Qaisar Shafi (Bartol Research Institute) | Theory |
14:00 Moseley | Warped Extra Dimension | |
Abstracts
7 Feb Robin Marshall :
The heat capacity of a substance can be expressed as a Fredholm integral
equation of the first kind, with the Einstein function as kernel, multiplied
on the lattice and intra-molecular vibration spectrum. An analytic solution
for the inverse transformation, converting a heat capacity spectrum as a
function of temperature, into a vibration spectrum, has proved intractable
over the last 100 years. An method for the inverse transformation will be
presented here. Examples will be shown for alkali halides, ice and a number of
polyatomic carbides, such a Ti2Si3C, and interpreted in terms of the vibration
modes. Comparisons will be made with spectra obtained by Raman and inelastic
neutron scattering.
28 Feb Andrzej Jerzy Buras
After a short introduction in the field of FCNC processes I will briefly
describe the Littlest Higgs Model with T parity. The interactions of the
mirror fermions in this model with the standard quarks and leptons bring new
sources of flavour and CP violation. I will present the implications of these
interactions on FCNC processes both in the quark and lepton sectors.
5 March Konstantinos Dimopoulos
Cosmic Inflation is the most compelling solution to many of the problems of
Hot Big Bang Cosmology. One of the major successes of inflation is that it can
explain the origin of the curvature perturbations in the Universe, through
particle production of light fields. These curvature perturbations are
responsible for the formation of the observed Large Scale Structure in the
Universe (distiribution of galactic cluster and superclusters) as well as the
observed CMB primordial anisotropies. Traditionally, inflation produces the
curvature perturbation by the gravitational amplification of quantum
fluctuations of light scalar fields to superhorizon classical perturbations.
In contrast, I investigate the possibility that the observed curvature
perturbation is due to a massive vector field. To avoid generating a large
scale anisotropy the vector field is assumed to become important only after
inflation when it may dominate the Universe and imprint its perturbation
spectrum before its decay, as in the curvaton scenario. After inflation the
vector field engages into oscillations, during which it behaves as isotropic
pressureless matter. Hence, large scale anisotropy can be avoided, when the
vector field dominates the Universe.
7 March Lucio Piccirillo:
The 3K Cosmic Background Radiation is a fantastic tool to study the origin and
evolution of the universe. The study of CMB spatial anisotropy provides
information used to infer many parameters, for example the density and
geometry of the universe. With recent advances in technology, cosmologists now
plan to measure the polarisation of the CMB. Scalar and tensor perturbations
generated by primordial gravitational waves could be detected through their
imprints in the CMB B-modes polarisation. The challenges of the new
generations of instruments to measure these B-modes will be discussed.
14 March Chris Damerell:
I review the physics needs, technical requirements, and current status of R&D
for vertex detectors, which will offer unprecedented capability for tagging of
heavy flavour jets (b and c) including sign-selection of the quark charge (b
vs bbar, c vs cbar) which is needed for a broad range of ILC physics.
20 March Tomislav Prokopec:
The problem of decoherence of cosmological perturbations has been with us for
a couple of decades, and it is still an open problem. Namely, cosmological
perturbations are generated during inflation in a pure quantum state which
exhibits strong quantum coherence when viewed in the field amplitude basis. I
shall present a mechanism by which cosmological perturbations efficiently
decohere during inflation: when inflation is realised by two light scalar
fields, the field that corresponds to the isocurvature mode (that does not
couple directly to gravitational potentials), efficiently decoheres the
adiabatic perturbation, which couples directly to primordial gravitational
potentials. The decohered potentials are then accurately described as a
classical stochastic state, which is usually assumed without proof.
25 April Stephen Watts
Visualisation of data in particle physics currently involves event displays,
histograms, line graphs and scatterplots. Since 1975 there has been an
explosion of techniques for data visualisation driven by highly interactive
computer systems and ideas from statistical graphics. This field has been
driven by demands for data mining of large databases and genomics. Two key
areas are direct manipulation of visual data and new methods for visualising
high-dimensional data. The first area has seen the use of linked views,
brushing and pruning. The second area has seen the introduction of methods
such as parallel coordinates and the grand tour. In this talk, these ideas are
applied to particle physics data to evaluate their ability to reduce data
analysis time and improve pattern recognition. In particular, parallel
coordinates will be used to analyse a sample of K-short Monte Carlo events. It
will be shown that this graphical technique significantly reduces the time
taken to determine the key variables for event selection.
The talk will also give a brief review of some data mining techniques and show how visualisation can help one to understand the effectiveness (or not) of some of these methods.
The talk will describe some publicly available software tools that include many of the new statistical graphics techniques and conclude that no single tool includes all the most powerful new techniques and argue that urgent work is required to integrate these ideas into data analysis tools for particle physics.
30 April Mark Hindmarsh
I will report on the first field-theoretic calculations of the contribution
made by cosmic strings to the temperature power spectrum of the Cosmic
Microwave Background, and the results of fitting inflationary models with
strings to the CMB data. Intriguing hints are found that strings may be
contributing about 10% of the signal.
9 May Malin Sjodahl
I will talk about soft gluon resummation in the context of qq -> qqH. Not
surprisingly, the probability for additional gluon emission depends
critically on whether the underlying hard process is a colour octet
exchange, as in qq -> qqH via gluon fusion, or a colour singlet exchange,
as in qq -> qqH via weak boson fusion). This can be used to experimentally
discriminate between these channels of Higgs production at the LHC.
Performing the all order soft gluon resummation also allows us to
calculate the interference between the two processes.
16 May Steve Koonin:
The world's demand for energy will grow by some 60% in the next 25 years.
Satisfying the demand in an economical and environmentally acceptable manner
is one of the most significant challenges facing this society. New
technologies will play a central role in meeting this challenge, albeit
conditioned by the economic, social and political contexts in which they are
developed and deployed. The presentation will focus on the major forces
shaping the world's energy future and the technologies required to respond to
them
29 May Joannis Papavassiliou:
At present it is generally accepted that the non-perturbative QCD dynamics
lead to the generation of an infrared regulator that may be thought of as an
effective gluon mass. The generation of such a mass does no affect the local
gauge invariance of the theory, which remains intact. In addition to its
theoretical appeal, this description is rather succesfull in low-energy QCD
phenomenology, especially in nucleon-nucleon scattering (two-gluon exchange
model). In this talk I will present a general introduction to the subject,
addressing some of the main conceptual and technical issues. In the
non-perturbative framework of the Schwinger-Dyson equations I will study the
gluon propagator of pure (quark-less) QCD, focusing on a special type of
solutions that are free of the Landau singularity, and reach a finite value in
the deep infrared. The strong coupling obtained displays asymptotic freedom in
the ultraviolet and freezes at a finite value at low energies, thus giving
rise to an infrared fixed point for QCD. Various open questions and possible
future directions will be briefly discussed.
30 May Nick Dorey:
I will introduce the concept of integrability and review its role in recent
progress towards an exact solution of N=4 SUSY Yang-Mills in the limit of many
colours.
19 June A K Nandi:
Clustering is the classification of objects into different groups, or more
precisely, the partitioning of a data set into subsets (clusters), so that the
data in each subset (ideally) share some common trait - often proximity
according to some defined distance measure. Data clustering is a common
technique for statistical data analysis, which is used in many fields,
including machine learning, data mining, pattern recognition, image analysis
and bioinformatics. [source: wikipedia on the web].
Statistical classification is a statistical procedure in which individual items are placed into groups based on quantitative information on one or more characteristics inherent in the items (referred to as traits, variables, characters, etc) and based on a training set of previously labeled items. [source: wikipedia]. This has numerous applications in medical imaging, speech recognition, handwriting recognition, document classification, biometric identification, etc.
Effective, informative and efficient visualisation of complex data needs to be closely related to clustering and classification. In my presentation, I shall explore some of the ideas involved and some of the algorithms used. I shall demonstrate their applications on some data and their results. I aim to start from the very basic and plan to take you to some of the most current, advanced ideas.
22 June Savas Dimopoulos:
We will survey some of the ideas for physics beyond the Standard Model that
have been developed in the last quarter century. These are now undergoing
significant re-evaluation in view of the cosmological constant problem, and
the apparent presence of an enormous number of ground states in string theory.
We will also discuss experimental tests of these ideas in the Large Hadron
Collider, which will begin in 2008.
25 June Stephen West:
The cosmological fate of flat directions provides a major
ingredient for the history of the early universe. Flat directions
can provide mechanisms for generating the baryon asymmetry of the
universe and can play an important role in reheating after
inflation. We analyze the possibility that the flat direction
condensate decays non-perturbatively in a way similar to
preheating in models of inflation.
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