29,663 research outputs found
On the arithmetic of tight closure
We provide a negative answer to an old question in tight closure theory by showing that the containment x^3y^3 \in (x^4,y^4,z^4)^* in K[x,y,z]/(x^7+y^7-z^7) holds for infinitely many but not for almost all prime
characteristics of the field K. This proves that tight closure exhibits a strong dependence on the arithmetic of the prime characteristic. The ideal (x,y,z) \subset K[x,y,z,u,v,w]/(x^7+y^7-z^7, ux^4+vy^4+wz^4+x^3y^3) has then
the property that the cohomological dimension fluctuates arithmetically between 0 and 1
Versatile analog pulse height computer performs real-time arithmetic operations
Multipurpose analog pulse height computer performs real-time arithmetic operations on relatively fast pulses. This computer can be used for identification of charged particles, pulse shape discrimination, division of signals from position sensitive detectors, and other on-line data reduction techniques
Multi-Gigabit Wireless data transfer at 60 GHz
In this paper we describe the status of the first prototype of the 60 GHz
wireless Multi-gigabit data transfer topology currently under development at
University of Heidelberg using IBM 130 nm SiGe HBT BiCMOS technology. The 60
GHz band is very suitable for high data rate and short distance applications as
for example needed in the HEP experments. The wireless transceiver consist of a
transmitter and a receiver. The transmitter includes an On-Off Keying (OOK)
modulator, an Local Oscillator (LO), a Power Amplifier (PA) and a BandPass
Filter (BPF). The receiver part is composed of a BandPass- Filter (BPF), a Low
Noise Amplifier (LNA), a double balanced down-convert Gilbert mixer, a Local
Oscillator (LO), then a BPF to remove the mixer introduced noise, an
Intermediate Amplifier (IF), an On-Off Keying demodulator and a limiting
amplifier. The first prototype would be able to handle a data-rate of about 3.5
Gbps over a link distance of 1 m. The first simulations of the LNA show that a
Noise Figure (NF) of 5 dB, a power gain of 21 dB at 60 GHz with a 3 dB
bandwidth of more than 20 GHz with a power consumption 11 mW are achieved.
Simulations of the PA show an output referred compression point P1dB of 19.7 dB
at 60 GHz.Comment: Proceedings of the WIT201
Looking at the photoproduction of massive gauge bosons at the LHeC
In this contribution we report on the investigation of the photoproduction of
W and Z bosons in the planned electron-proton/nucleus collider, the LHeC. The
production cross sections and the number of events are provided and theoretical
uncertainties are discussed. We also analyze the sensitivity of the LHeC
experiment to physics beyond Standard Model by studying the role played by
anomalous WWgamma coupling in the presented process.Comment: Contribution to the proceedings of the XXI International Workshop on
Deep-Inelastic Scattering and Related Subjects (DIS2013), Marseille, 22-26
April 201
Quarkonium plus prompt-photon associated hadroproduction and nuclear shadowing
The quarkonium hadroproduction in association with a photon at high energies
provides a probe of the dynamics of the strong interactions as it is dependent
on the nuclear gluon distribution. Therefore, it could be used to constrain the
behavior of the nuclear gluon distribution in proton-nucleus and
nucleus-nucleus collisions. Such processes are useful to single out the
magnitude of the shadowing/antishadowing effects in the nuclear parton
densities. In this work we investigate the influence of nuclear effects in the
production of JPsi + photon and Upsilon + photon and estimate the transverse
momentum dependence of the nuclear modification factors. The theoretical
framework considered in the JPsi (Upsilon) production associated with a direct
photon at the hadron collider is the non-relativistic QCD (NRQCD) factorization
formalism.Comment: 8 pages, 4 figures. Final version to be published in European
Physical Journal
The fractional Keller-Segel model
The Keller-Segel model is a system of partial differential equations
modelling chemotactic aggregation in cellular systems. This model has blowing
up solutions for large enough initial conditions in dimensions d >= 2, but all
the solutions are regular in one dimension; a mathematical fact that crucially
affects the patterns that can form in the biological system. One of the
strongest assumptions of the Keller-Segel model is the diffusive character of
the cellular motion, known to be false in many situations. We extend this model
to such situations in which the cellular dispersal is better modelled by a
fractional operator. We analyze this fractional Keller-Segel model and find
that all solutions are again globally bounded in time in one dimension. This
fact shows the robustness of the main biological conclusions obtained from the
Keller-Segel model
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