3,406 research outputs found
Renormalization and ultraviolet sensitivity of gauge vertices in universal extra dimensions
When computing radiative corrections in models with compactified extra dimen-
sions, one has to sum over the entire tower of Kaluza-Klein excitations inside
the loops. The loop corrections generate a difference between the coupling
strength of a zero-mode gauge boson and the coupling strength of its
Kaluza-Klein excitation, although both originate from the same
higher-dimensional gauge interaction. Furthermore, this dis- crepancy will in
general depend on the cutoff scale and assumptions about the UV completion of
the extra-dimensional theory. In this article, these effects are studied in
detail within the context of the minimal universal extra dimension model
(MUED). The broad features of the cutoff scale dependence can be captured
through the so- lution of the functional flow equation in five-dimensional
space. However, an explicit diagrammatic calculation reveals some modifications
due to the compactification of the extra dimension. Nevertheless, when imposing
a physical renormalization condition, one finds that the UV sensitivity of the
effective Kaluza-Klein gauge-boson vertex is relatively small and not very
important for most phenomenological purposes. Similar conclusions should hold
in a larger class of extra-dimensional models besides MUED.Comment: 20 pages, 5 figure
QCD corrections to massive color-octet vector boson pair production
This paper describes the calculation of the next-to-leading order (NLO) QCD
corrections to massive color-octet vector boson pair production at hadron
colliders. As a concrete framework, a two-site coloron model with an internal
parity is chosen, which can be regarded as an effective low-energy
approximation of Kaluza-Klein gluon physics in universal extra dimensions. The
renormalization procedure involves several subtleties, which are discussed in
detail. The impact of the NLO corrections is relatively modest, amounting to a
reduction of 11-14% in the total cross-section, but they significantly reduce
the scale dependence of the LO result
Radiative corrections to masses and couplings in Universal Extra Dimensions
Models with an orbifolded universal extra dimension receive important
loop-induced corrections to the masses and couplings of Kaluza-Klein (KK)
particles. The dominant contributions stem from so-called boundary terms which
violate KK number. Previously, only the parts of these boundary terms
proportional to have been computed, where is the radius of
the extra dimension and is cut-off scale. However, for typical values
of , the logarithms are not particularly large and
non-logarithmic contributions may be numerically important. In this paper,
these remaining finite terms are computed and their phenomenological impact is
discussed. It is shown that the finite terms have a significant impact on the
KK mass spectrum. Furthermore, one finds new KK-number violating interactions
that do not depend on but nevertheless are non-zero. These
lead to new production and decay channels for level-2 KK particles at
colliders.Comment: V2: KK-top (mass and decays) updated, correcting a mistake in the
literatur
Axinos in Cosmology and at Colliders
The axino, the fermionic superpartner of the axion, is a well-motivated
candidate for cold dark matter if it is the lightest supersymmetric particle.
Since the axino couples very weakly to the matter multiplets, the
next-to-lightest supersymmetric particle (NLSP) has a long lifetime, which has
important consequences for both cosmology and collider phenomenology. Assuming
that a charged slepton is the NLSP, we calculate the complete leading one- and
two-loop contributions to its decay. We analyze in detail constraints on the
parameters space from cosmology and discuss how this scenario can be probed at
colliders. Scenarios in which both the axino and the gravitino are lighter than
the long-lived charged slepton are also explored with particular emphasis on
cosmological constraints and collider phenomenology.Comment: 64 pages, 22 figure
Membrane Deflection-based Fabrication and Design Automation for Integrated Acoustofluidics
Continuous-flow microfluidic large-scale integration (mLSI) is a developing field first introduced in the early 2000s, that continues to offer promising solutions to many biochemical, biophysical and biomedical problems. In his seminal paper, Thorsen et al. 2002 demonstrated the fabrication of high-density microfluidic systems capable of complex fluidic routing in combinatory arrays of multiplexors, mixers, and storage assemblies integrated with micromechanical valves. mLSI has been a powerful tool for scientific research by allowing for dramatic reduction in the volume of reagent needed for experimentation and offering highly parallelizable and dynamic process flows. These systems have since been the focus of strong interdisciplinary academic research efforts. Despite the success in scientific applications, the mLSI technologies have not found widespread use in commercial environments. One critical issue preventing mLSI to realize its full potential is the need for specialized fabrication techniques that are scalable and more suitable for the unique requirements of biology.
The work presented here demonstrates an mLSI integrated acoustofluidic platform that offers versatility while maintaining a robust fabrication process. In particular, conductive liquid metal-based acoustic transducers integrated with micromechanical valves to facilitate dynamic switching of the resonant frequency of the device and generated surface acoustic waves (SAWs) is demonstrated. Shortcomings in the fabrication of fluidic channels for mLSI integrated acoustofluidic applications are examined, and solutions to these problems are presented. A novel and scalable soft-lithographic method is introduced, that allows for the fabrication of large valvable channels with tunable height that exceeds practical limitations dictated by previous photolithographic techniques. A thorough characterization of this method and demonstration of its robustness are included here as a promising data to promote further exploration of the technique as a viable commercial solution for the fabrication of many classes of mLSI bio-devices. The testing of a computeraided design software, Columba, is briefly discussed
Linear cryptanalysis of pseudorandom functions
Relatório de projeto de pesquisa.In this paper, we study linear relations propagating across block ciphers from the key input to the ciphertext (for a fixed plaintext block). This is a usual setting of a one-way function, used for instance in modes of operation such as KFB (key feedback). We instantiate the block cipher with the full 16-round DES and -DES, 10-round LOKI91 and 24-round Khufu, for which linear relations with high bias are well known. Other interesting targets include the full 8.5-round IDEA and PES ciphers for which high bias linear relations exist under the assumption of weak keys. Consequences of these findings impact the security of modes of operation such as KFB and of pseudorandom number/bit generators. These analyses were possible due to the linear structure and the poor diffusion of the key schedule algorithms. These findings shall motivate carefull (re)design of current and future key schedule algorithms
Development of new chemical entities based on natural scaffolds with therapeutic potential towards age-related disorders.
- …