5,706 research outputs found
Measurement of the H/A -> tau tau cross section and possible constraints on tan beta
The achievable precision of the cross section times branching ratio
measurement from the event rates is estimated for the MSSM H/A -> tau tau decay
in the associated production process gg -> b bbar H/A at large tan beta in CMS.
This work demonstrates that the above production and decay process exhibit a
large sensitivity to tan beta and thus add as a significant observable to a
global fit of the SUSY parameters. To illustrate this potential an example is
given concerning the achievable tan beta determination accuracy that could be
reached from the event rates and for a given set of SUSY parameters and
uncertainties
Feasibility of study magnetic proximity effects in bilayer "superconductor/ferromagnet" using waveguide-enhanced Polarized Neutron Reflectometry
A resonant enhancement of the neutron standing waves is proposed to use in
order to increase the magnetic neutron scattering from a
"superconductor/ferromagnet"(S/F) bilayer. The model calculations show that
usage of this effect allows to increase the magnetic scattering intensity by
factor of hundreds. Aspects related to the growth procedure (order of
deposition, roughness of the layers etc) as well as experimental conditions
(resolution, polarization of the neutron beam, background etc) are also
discussed.
Collected experimental data for the S/F heterostructure
Cu(32nm)/V(40nm)/Fe(1nm)/MgO confirmed the presence of a resonant 60-fold
amplification of the magnetic scattering.Comment: The manuscript of the article submitted to Crysstalography Reports.
23 pages, 5 figure
Evidence for nonmonotonic magnetic field penetration in a type-I superconductor
Polarized neutron reflectometry (PNR) provides evidence that nonlocal
electrodynamics governs the magnetic field penetration in an extreme low-k
superconductor. The sample is an indium film with a large elastic mean free
path (11 mkm) deposited on a silicon oxide wafer. It is shown that PNR can
resolve the difference between the reflected neutron spin asymmetries predicted
by the local and nonlocal theories of superconductivity. The experimental data
support the nonlocal theory, which predicts a nonmonotonic decay of the
magnetic field.Comment: 5 pages, 4 figures, LaTex, corrected typos and figure
Photon Physics in Heavy Ion Collisions at the LHC
Various pion and photon production mechanisms in high-energy nuclear
collisions at RHIC and LHC are discussed. Comparison with RHIC data is done
whenever possible. The prospect of using electromagnetic probes to characterize
quark-gluon plasma formation is assessed.Comment: Writeup of the working group "Photon Physics" for the CERN Yellow
Report on "Hard Probes in Heavy Ion Collisions at the LHC", 134 pages. One
figure added in chapter 5 (comparison with PHENIX data). Some figures and
correponding text corrected in chapter 6 (off-chemical equilibrium thermal
photon rates). Some figures modified in chapter 7 (off-chemical equilibrium
photon rates) and comparison with PHENIX data adde
Adrenomedullin and tumour angiogenesis
The angiogenic activity of peptide adrenomedullin (AM) was first shown in 1998 . Since then, a number of reports have confirmed the ability of AM to induce the growth and migration of isolated vascular endothelial and smooth muscle cells in vitro and to promote angiogenesis in xenografted tumours in vivo. In addition, knockout murine models point to an essential role for AM in embryonic vasculogenesis and ischaemic revascularisation. AM expression is upregulated by hypoxia (a typical feature of solid tumours) and a potential role as a regulator of carcinogenesis and tumour progression has been proposed based on studies in vitro and in animal models. Nevertheless, translational research on AM, and in particular, confirmation of its importance in the vascularisation of human tumours has lagged behind. In this commentary, we review current progress and potential directions for future research into the role of AM in tumour angiogenesis
The Higgs Working Group: Summary Report (2001)
Report of the Higgs working group for the Workshop `Physics at TeV
Colliders', Les Houches, France, 21 May - 1 June 2001. It contains 7 separate
sections: A. Theoretical Developments B. Higgs Searches at the Tevatron C.
Experimental Observation of an invisible Higgs Boson at LHC D. Search for the
Standard Model Higgs Boson using Vector Boson Fusion at the LHC E. Study of the
MSSM channel at the LHC F. Searching for Higgs Bosons in
Production G. Studies of Charged Higgs Boson Signals for the
Tevatron and the LHCComment: 120 pages, latex, many figures, proceedings of the Workshop `Physics
at TeV Colliders', Les Houches, France, 21 May - 1 June 2001, full Author
list included in paper. Typos corrected, author list and acknowledgements
completed. Convernors: D. Cavalli, A. Djouadi, K. Jakobs, A. Nikitenko, M.
Spira, C.E.M. Wagner, W.-M. Ya
Hard Probes in Heavy Ion Collisions at the LHC: Jet Physics
We discuss the importance of high-pT hadron and jet measurements in
nucleus-nucleus collisions at the CERN Large Hadron Collider.Comment: The writeup of the working group "Jet Physics" for the CERN Yellow
Report on "Hard Probes in Heavy Ion Collisions at the LHC", 123 pages.
Subgroup convenors: R. Baier, X.N. Wang, U.A. Wiedemann (theory) and I.P.
Lokhtin, A. Morsch (experiment). Editor: U.A. Wiedeman
Atomic structure of dislocation kinks in silicon
We investigate the physics of the core reconstruction and associated
structural excitations (reconstruction defects and kinks) of dislocations in
silicon, using a linear-scaling density-matrix technique. The two predominant
dislocations (the 90-degree and 30-degree partials) are examined, focusing for
the 90-degree case on the single-period core reconstruction. In both cases, we
observe strongly reconstructed bonds at the dislocation cores, as suggested in
previous studies. As a consequence, relatively low formation energies and high
migration barriers are generally associated with reconstructed
(dangling-bond-free) kinks. Complexes formed of a kink plus a reconstruction
defect are found to be strongly bound in the 30-degree partial, while the
opposite is true in the case of 90-degree partial, where such complexes are
found to be only marginally stable at zero temperature with very low
dissociation barriers. For the 30-degree partial, our calculated formation
energies and migration barriers of kinks are seen to compare favorably with
experiment. Our results for the kink energies on the 90-degree partial are
consistent with a recently proposed alternative double-period structure for the
core of this dislocation.Comment: 12 pages, two-column style with 8 postscript figures embedded. Uses
REVTEX and epsf macros. Also available at
http://www.physics.rutgers.edu/~dhv/preprints/index.html#rn_di
Les Houches "Physics at TeV Colliders 2003" Beyond the Standard Model Working Group: Summary Report
The work contained herein constitutes a report of the ``Beyond the Standard
Model'' working group for the Workshop "Physics at TeV Colliders", Les Houches,
France, 26 May--6 June, 2003. The research presented is original, and was
performed specifically for the workshop. Tools for calculations in the minimal
supersymmetric standard model are presented, including a comparison of the dark
matter relic density predicted by public codes. Reconstruction of
supersymmetric particle masses at the LHC and a future linear collider facility
is examined. Less orthodox supersymmetric signals such as non-pointing photons
and R-parity violating signals are studied. Features of extra dimensional
models are examined next, including measurement strategies for radions and
Higgs', as well as the virtual effects of Kaluza Klein modes of gluons. An LHC
search strategy for a heavy top found in many little Higgs model is presented
and finally, there is an update on LHC studies.Comment: 113 pages, ed B.C. Allanach, v5 has changes to part XV
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