77 research outputs found
N=1/2 gauge theory and its instanton moduli space from open strings in R-R background
We derive the four dimensional N=1/2 super Yang-Mills theory from tree-level
computations in RNS open string theory with insertions of closed string
Ramond-Ramond vertices. We also study instanton configurations in this gauge
theory and their ADHM moduli space, using systems of D3 and D(-1) branes in a
R-R background.Comment: 29 pages, 6 figures, JHEP class (included
N=1/2 quiver gauge theories from open strings with R-R fluxes
We consider a four dimensional N=1 gauge theory with bifundamental matter and
a superpotential, defined on stacks of fractional branes. By turning on a flux
for the R-R graviphoton field strength and computing open string amplitudes
with insertions of R-R closed string vertices, we introduce a
non-anticommutative deformation and obtain the N=1/2 version of the theory. We
also comment on the appearance of a new structure in the effective Lagrangian.Comment: 30 pages, 5 figures, JHEP class (included); some comments and a
reference adde
Next-generation ultra-compact calorimeters based on oriented crystals
Calorimeters based on oriented crystals provide unparalleled compactness and resolution in measuring the energy of electromagnetic particles. Recent experiments performed at CERN and DESY beamlines by the AXIAL/ELIOT experiments demonstrated a significant reduction in the radiation length inside tungsten and PbWO4, the latter being the scintillator used for the CMS ECAL, observed when the incident particle trajectory is aligned with a lattice axis within ∼1∘. This remarkable effect, being observed over the wide energy range from a few GeV to 1 TeV or higher, paves the way for the development of innovative calorimeters based on oriented crystals, featuring a design significantly more compact than currently achievable while rivaling the current state of the art in terms of energy resolution in the range of interest for present and future forward detectors (such as the KLEVER Small Angle Calorimeter at CERN SPS) and source-pointing space-borne γ-ray telescopes
Nonanticommutative U(1) SYM theories: Renormalization, fixed points and infrared stability
Renormalizable nonanticommutative SYM theories with chiral matter in the
adjoint representation of the gauge group have been recently constructed in
[arXiv:0901.3094]. In the present paper we focus on the U*(1) case with matter
interacting through a cubic superpotential. For a single flavor, in a
superspace setup and manifest background covariant approach we perform the
complete one-loop renormalization and compute the beta-functions for all
couplings appearing in the action. We then generalize the calculation to the
case of SU(3) flavor matter with a cubic superpotential viewed as a nontrivial
NAC generalization of the ordinary abelian N=4 SYM and its marginal
deformations. We find that, as in the ordinary commutative case, the NAC N=4
theory is one-loop finite. We provide general arguments in support of all-loop
finiteness. Instead, deforming the superpotential by marginal operators gives
rise to beta-functions which are in general non-vanishing. We study the
spectrum of fixed points and the RG flows. We find that nonanticommutativity
always makes the fixed points unstable.Comment: 1+30 pages, 5 figure
Homogeneous self-standing curved monocrystals, obtained using sandblasting, to be used as manipulators of hard X-rays and charged particle beams
A technique to obtain self-standing curved crystals has been developed. The method is based on a sandblasting process capable of producing an amorphized layer on the substrate. It is demonstrated that the amorphized layer behaves as a thin compressive film, causing the curvature of the substrate. This procedure permits the fabrication of homogeneously curved crystals in a fast and economical way. It is shown that a sandblasted crystal can be used as an X-ray optical element for astrophysical or medical applications. A sandblasted bent crystal can also be used as an optical element for steering charged particles in accelerator beamlines. Several samples were manufactured and bent using the sandblasting method at the Sensor and Semiconductor Laboratory of Ferrara, Italy. Their curvature was verified using interferometric profilometry, showing a deformation in agreement with the Stoney formalism. The curvature of the machined samples was also tested using γ-ray diffraction at the Institut Laue-Langevin (ILL), Grenoble, France. A good agreement with the dynamical theory of diffraction was observed. In particular, the experiment showed that the crystalline quality of the bulk was preserved. Moreover, the method allowed curved samples to be obtained free of any additional material. Finally, a crystalline undulator was produced using sandblasting and tested using γ-ray diffraction at the ILL. The crystal showed a precise undulating pattern, so it will be suitable for hard X-ray production
Development of crystal optics for Multi-Projection X-ray Imaging for synchrotron and XFEL sources
X-ray Multi-Projection Imaging (XMPI) is an emerging technology that allows
for the acquisition of millions of 3D images per second in samples opaque to
visible light. This breakthrough capability enables volumetric observation of
fast stochastic phenomena, which were inaccessible due to the lack of a
volumetric X-ray imaging probe with kHz to MHz repetition rate. These include
phenomena of industrial and societal relevance such as fractures in solids,
propagation of shock waves, laser-based 3D printing, or even fast processes in
the biological domain. Indeed, the speed of traditional tomography is limited
by the shear forces caused by rotation, to a maximum of 1000 Hz in
state-of-the-art tomography. Moreover, the shear forces can disturb the
phenomena in observation, in particular with soft samples or sensitive
phenomena such as fluid dynamics. XMPI is based on splitting an X-ray beam to
generate multiple simultaneous views of the sample, therefore eliminating the
need for rotation. The achievable performances depend on the characteristics of
the X-ray source, the detection system, and the X-ray optics used to generate
the multiple views. The increase in power density of the X-ray sources around
the world now enables 3D imaging with sampling speeds in the kilohertz range at
synchrotrons and megahertz range at X-ray Free-Electron Lasers (XFELs). Fast
detection systems are already available, and 2D MHz imaging was already
demonstrated at synchrotron and XFEL. In this work, we explore the properties
of X-ray splitter optics and XMPI schemes that are compatible with synchrotron
insertion devices and XFEL X-ray beams. We describe two possible schemes
designed to permit large samples and complex sample environments. Then, we
present experimental proof of the feasibility of MHz-rate XMPI at the European
XFEL.Comment: 47 pages, 17 figure
Towards a Muon Collider
A muon collider would enable the big jump ahead in energy reach that is
needed for a fruitful exploration of fundamental interactions. The challenges
of producing muon collisions at high luminosity and 10 TeV centre of mass
energy are being investigated by the recently-formed International Muon
Collider Collaboration. This Review summarises the status and the recent
advances on muon colliders design, physics and detector studies. The aim is to
provide a global perspective of the field and to outline directions for future
work.Comment: 118 pages, 103 figure
Towards a muon collider
A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work
Towards a muon collider
A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work
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