Search results for "database."
showing 10 items of 2119 documents
Can one detect new physics in I=0 and/or I=2 contributions to the decays B ->pi pi
2005
We study the effects of new-physics contributions to B --> pi pi decays, which can be parametrized as four new complex quantities. A simple analysis is provided by utilizing the reparametrization invariance of the decay amplitudes. We find that six quantities can be reabsorbed into the definitions of Standard Model-like parameters. As a result, the usual isospin analysis provides only two constraints on new physics which are independent of estimates for the Standard Model contributions. In particular, we show that one is not sensitive to new physics affecting the I=0 amplitudes. On the other hand, I=2 new physics can be detected, and its parameters can be measured by using independent deter…
New Strong Bounds on sub-GeV Dark Matter from Boosted and Migdal Effects
2020
Due to the low nuclear recoils, sub-GeV dark matter (DM) is usually beyond the sensitivity of the conventional DM direct detection experiments. The boosted and Migdal scattering mechanisms have been proposed as two new complementary avenues to search for light DM. In this work, we consider the momentum-transfer effect in the DM-nucleus scattering to derive the new bounds on sub-GeV DM for these two scenarios. We show that such an effect is sizable so that the existing bounds on the DM-nucleus scattering cross section can be improved significantly.
Theory of Neutrinos
2004
After a brief overview of the present knowledge of neutrino masses and mixing, we summarize what can be learned about physics beyond the standard model from the various proposed neutrino experiments. We also comment on the impact of the experiments on our understanding of the origin of the matter-antimatter asymmetry of the Universe as well as what can be learned from some experiments outside the domain of neutrinos.
Probing Planck scale physics with IceCube
2005
Neutrino oscillations can be affected by decoherence induced e.g. by Planck scale suppressed interactions with the space-time foam predicted in some approaches to quantum gravity. We study the prospects for observing such effects at IceCube, using the likely flux of TeV antineutrinos from the Cygnus spiral arm. We formulate the statistical analysis for evaluating the sensitivity to quantum decoherence in the presence of the background from atmospheric neutrinos, as well as from plausible cosmic neutrino sources. We demonstrate that IceCube will improve the sensitivity to decoherence effects of ${\cal O}(E^2/M_{\rm Pl})$ by 17 orders of magnitude over present limits and, moreover, that it ca…
Double copies of fermions as only gravitational interacting matter
2016
Inspired by the recent progress in the field of scattering amplitudes, we discuss hypothetical particles which can be characterised as the double copies of fermions -- in the same way gravitons can be viewed as double copies of gauge bosons. As the gravitons, these hypothetical particles interact only through gravitational interactions. We present two equivalent methods for the computation of the relevant scattering amplitudes. The hypothetical particles can be massive and non-relativistic.
Supersymmetry in non commutative superspaces
2003
Non commutative superspaces can be introduced as the Moyal-Weyl quantization of a Poisson bracket for classical superfields. Different deformations are studied corresponding to constant background fields in string theory. Supersymmetric and non supersymmetric deformations can be defined, depending on the differential operators used to define the Poisson bracket. Some examples of deformed, 4 dimensional lagrangians are given. For extended superspace (N>1), some new deformations can be defined, with no analogue in the N=1 case.
Decoherent neutrino mixing, dark energy, and matter-antimatter asymmetry
2004
A CPT violating decoherence scenario can easily account for all the experimental evidence in the neutrino sector including LSND. In this work it is argued that this framework can also accommodate the Dark Energy content of the Universe, as well as the observed matter-antimatter asymmetry.
Physical Activity and Exercise: Text Mining Analysis
2021
It is currently difficult to have a global state of the art vision of certain scientific topics. In the field of physical activity (PA) and exercise, this is due to information overload. The present study aims to provide a solution by analysing a large mass of scientific articles using text mining (TM). The purpose was to analyse what is being investigated in the PA health field on young people from primary, secondary and higher education. Titles and abstracts published in the Web of Science (WOS) database were analysed using TM on 24 November 2020, and after removing duplicates, 85,368 remained. The results show 9960 (unique) words and the most frequently used bi-grams and tri-grams. A co-…
Distributed Data Collection for the ATLAS EventIndex
2015
The ATLAS EventIndex contains records of all events processed by ATLAS, in all processing stages. These records include the references to the files containing each event (the GUID of the file) and the internal “pointer” to each event in the file. This information is collected by all jobs that run at Tier-0 or on the Grid and process ATLAS events. Each job produces a snippet of information for each permanent output file. This information is packed and transferred to a central broker at CERN using an ActiveMQ messaging system, and then is unpacked, sorted and reformatted in order to be stored and catalogued into a central Hadoop server. This contribution describes in detail the Producer/Consu…
ATLAS operations in the GridKa T1/T2 Cloud
2011
The ATLAS GridKa cloud consists of the GridKa Tier1 centre and 12 Tier2 sites from five countries associated to it. Over the last years a well defined and tested operation model evolved. Several core cloud services need to be operated and closely monitored: distributed data management, involving data replication, deletion and consistency checks; support for ATLAS production activities, which includes Monte Carlo simulation, reprocessing and pilot factory operation; continuous checks of data availability and performance for user analysis; software installation and database setup. Of crucial importance is good communication between sites, operations team and ATLAS as well as efficient cloud l…