Particle Physics Group



Particle Physics Seminars Autumn 2006

Seminars 2003     Seminars Spring 2004     Seminars Autumn 2004
Seminars 2005     Seminars Spring 2006    

New location: Moseley Lecture Theatre

Usual time: Wednesdays 2-3pm

Wed. 20 Sept.     Adnan Bashir (Durham) Theory
14:00 Moseley Gauge Invariant Masses (Sparing the Blushes of Ward Identities)
Mon. 25 Sept.     Mike Albrow (FNAL) Special Seminar
16:00 Moseley Exclusive Central Production in Proton-Proton Collisions: from Glueballs to Higgs.
Wed 27 Sept.     Guennadi Borissov (Lancaster) Experiment
14:00 Moseley B Physics at D0
Wed 11 Oct.     Kostya Novoselov Schuster Colloquium
14:30 Bragg QED in a Pencil Trace
  Graphene: a newly discovered system of a single layer of atoms with massless electrons.
Tues 17 Oct.     Ki-Young Choi (Sheffield) Astroparticle
12:00 Moseley Gravitino Dark Matter in the CMSSM
Wed 18 Oct.     John Campbell (Glasgow) Theory
14:00 Moseley Higgs Boson Production in Association With Two Hard Jets
Tues 24 Oct.     T.E.J. Underwood (Durham) Astroparticle
12:00 Moseley The Minimal Phantom Sector of the Standard Model: Higgs Phenomenology and Dirac Leptogenesis
Wed 25 Oct.     Un-Ki Yang (Manchester) Experiment
14:00 Moseley Latest measurement of top mass at CDF
Wed 1 Nov.     Durgaprasad P. Roy (Tata Inst. Mumbai & Durham) Theory
14:00 Moseley Prospects of Charged Higgs Boson Discovery at Colliders
Tues 7 Nov.     Antonio De Felice (Sussex) AstroParticle
12:00 Moseley Generalized Modified Gravity Models: ghosts and dynamical bounds
Wed 8 Nov.     Prof. Wolfgang Demtroder Schuster Colloquium
14:30 Bragg New Techniques in High Resolution Spectroscopy
  Several new methods for detecting small concentrations in the atmosphere
Wed 15 Nov.     Joerg Jaeckel (Durham) Theory
14:00 Moseley Photons as a Probe of fundamental Physics
Tues 21 Nov.     David Maybury (Oxford) Astroparticle
11:50 Moseley Phenomenological Aspects of Axions in Warped Extra Dimensions
Wed 22 Nov.     David Evans (Birmingham) Experiment
14:00 Moseley Alice and the Physics of Quark Matter
Wed 29 Nov.     Yazid Delenda (Manchester) Theory
14:00 Moseley Impact of kt algorithm on QCD resummation
Thurs 30 Nov.     John Ellis (CERN) Exceptional Seminar
12:00 Moseley Novel signatures for supersymmetry
Tues 5 Dec.     Richard Battye (Manchester) Astroparticle
11:50 Moseley Constraints on Supersymmetric Hybrid Inflation
Wed 6 Dec.     Prof. John Dainton, FRS Schuster Colloquium
14:00 Moseley The Cockroft Institute
  A new adventure at the forefronts of basic research and applications
Wed 13 Dec.     Athanasios Dedes (Durham) Theory
14:00 Bragg Higgs penguin effects at Tevatron, B-factories and LHC


Adnan Bashir, Gauge Invariant Masses (2006-09-20)
When coupling is strong, fermions can acquire masses through self interactions. In continuum, Schwinger-Dyson equations (SDEs) provide a natural means to study the problem of dynamical mass generation. However, in an attempt to solve these equations in strong coupling regime, we run into the problem of gauge non-invariance. I shall discuss if and how we can attempt to recuperate gauge invariance.

Mike Albrow, Exclusive Central Production in Proton-Proton Collisions: from Glueballs to Higgs (2006-09-25)
In high energy proton-proton collisions it is possible for both protons to be diffractively scattered, losing only a few percent of their energy in creating a central state. At the LHC it should be possible to create Higgs bosons (if they exist) this way, a form of "vacuum excitation". If so, using part of the LHC accelerator as a spectrometer, we can measure the Higgs mass, spin and other quantum numbers from the very forward protons.

Ki-Young Choi, Gravitino Dark Matter in the CMSSM (2006-10-17)
Gravitino is still a good candidate for dark matter. We investigate the possibility of Gravitino as Dark Matter and the implications in the Constrained Minimal Supersymmetric Standard Model (CMSSM). We calculate the relic density of Gravitino from thermal and non-thermal process and consider the constraints from Colliders and Cosmology. Assuming the Gravitino mass around GeV, we find the Gravitino can be Dark Matter with stau as next Lightest Supersymmetric Particle. One of the notable prediction of Gravitino dark matter is that cosmic Lithium problems can be solved in this scenario from the decay of stau in the early Universe. The other implication of Gravitino dark matter is that we can infer the vacuum structure of our Universe from considering the scalar potentials in the CMSSM.

John Campbell, Higgs Boson Production in Association With Two Hard Jets (2006-10-18)
The search for the origin of electroweak symmetry breaking is one of the primary goals of the LHC programme. In the Standard Model this breaking is achieved by introducing a Higgs boson which has so far eluded all searches at LEP and the Tevatron. In this talk I will discuss two of the most promising Higgs production channels, via gluon fusion and vector boson fusion, and discuss how they may be used to probe properties of the Higgs boson. In so doing, I will introduce a recent calculation of the next-to-leading order QCD corrections to the production of a Higgs boson and two hard jets via gluon fusion.

T.E.J. Underwood, The Minimal Phantom Sector of the Standard Model: Higgs Phenomenology and Dirac Leptogenesis (2006-10-24)
We propose the minimal, lepton-number conserving, SU(3)xSU(2)xU(1) gauge singlet, or phantom, extension to the Standard Model. The model provides Dirac neutrinos using couplings of O(1), imitating the Majorana see-saw. We find that small neutrino masses and successful Dirac leptogenesis imply that a phantom sector, global U(1) should be spontaneously broken at the electroweak scale - triggering consistent electroweak symmetry breaking. The existence of a Goldstone boson suppresses the Higgs to bb branching ratio and instead the Higgs bosons will mainly decay to invisible Goldstone and/or to visible vector boson pairs. The implications of this scenario for the LHC are examined, and we note that this may be an interesting scenario to study with central exclusive diffractive Higgs production.

Durgaprasad P. Roy, Prospects of Charged Higgs Boson Discovery at Colliders (2006-11-01)
After a brief introduction to the Charged Higgs boson in the MSSM I shall discuss the signatures of a relatively light Charged Higgs boson in top quark decay. Then I shall consider the signatures of a heavy Charged Higgs boson at LHC in the MSSM as well as some common extensions like NMSSM and CPV-MSSM. I shall conclude with a brief discussion of SUSY quantum corrections to the Charged Higgs boson signatures.

Antonio De Felice, Generalized Modified Gravity Models: ghosts and dynamical bounds (2006-11-07)
Modified gravity models seem to have classical instabilities, ghosts degrees of freedom and superluminal modes. Besides these constraints new dynamical bounds have found to be typical of these models. The cosmological nature of all these constraints is discussed.

Joerg Jaeckel, Photons as a Probe of fundamental Physics (2006-11-15)
Recently the PVLAS collaboration reported a non-vanishing signal for a rotation in the polarization of laser light passing through a strong magnetic field. Motivated by this observation we discuss possible explanations such as the production of axion like particles or millicharged particles. We point out that suitable millicharged particles occur naturally in the hidden sector of string theory. To test and distinguish between these scenarios one can use a variety of experiments, e.g. ''light shining through a wall'' experiments or setups looking for the nonperturbative Schwinger pair production in the electric fields of accelerator cavities. Finally, for all those who are still not willing to come to this talk we stress that the mass scale of the suggested new particles is of the order of meV, the mysterious scale of neutrinos, dark energy etc.

David Maybury, Phenomenological Aspects of Axions in Warped Extra Dimensions (2006-11-21)
Motivated by multi-throat considerations, we study the phenomenological implications of a bulk axion in a slice of AdS with a large extra dimension. In particular, we examine the differences of axion physics with a warped geometry relative to flat compactifications. As in flat compactification scenarios, we find that the mass of the axion can become independent of the underlying Peccei-Quinn scale. We find that the axion's invisibility and cosmological viability remain essentially unaltered in comparison to flat compactifications.

Yazid Delenda, Impact of kt algorithm on QCD resummation
We study the effect of the kt clustering algorithm on QCD predictions for energy flow observables. We perform a resummation of the large logarithms involved in the study, that for the first time accounts properly for the use of the kt clustering algorithm. We provide a prediction based on these studies for ZEUS photoproduction data and point to studies in other collider experiments where these observations will be important.

Richard Battye, Constraints on Supersymmetric Hybrid Inflation
We will summarise the constraints on inflationary models provided by the recent WMAP3 data and in particular focus on models of SUSY hybrid inflation which predict a spectral index between 0.98 and 1. These models can be made to be compatible with the data by taking into account a sub-dominant contribution to the anisotropy due to the cosmic strings formed during the phase transition at the end of inflation.

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