Search results for "Particle physics"
showing 10 items of 6826 documents
Reconstructing WIMP properties with neutrino detectors
2008
If the dark matter of the Universe is constituted by weakly interacting massive particles (WIMP), they would accumulate in the core of astrophysical objects as the Sun and annihilate into particles of the Standard Model. High-energy neutrinos would be produced in the annihilations, both directly and via the subsequent decay of leptons, quarks and bosons. While Cherenkov neutrino detectors/telescopes can only count the number of neutrinos above some threshold energy, we study how, by exploiting their energy resolution, large magnetized iron calorimeter and, possibly, liquid argon and totally active scintillator detectors, planned for future long baseline neutrino experiments, have the capabi…
Anomalous top magnetic couplings
2012
The real and imaginary parts of the one-loop electroweak contributions to the left and right tensorial anomalous couplings of the tbW vertex in the Standard Model (SM) are computed.
Structure formation during an early period of matter domination
2014
In this work we show that modifying the thermal history of the Universe by including an early period of matter domination can lead to the formation of astronomical objects. However, the survival of these objects can only be possible if the dominating matter decays to a daughter particle which is not only almost degenerate with the parent particle but also has an open annihilation channel. This requirement translates in an upper bound for the coupling of such a channel and makes the early structure formation viable.
Dark, Cold, and Noisy: Constraining Secluded Hidden Sectors with Gravitational Waves
2018
We explore gravitational wave signals arising from first-order phase transitions occurring in a secluded hidden sector, allowing for the possibility that the hidden sector may have a different temperature than the Standard Model sector. We present the sensitivity to such scenarios for both current and future gravitational wave detectors in a model-independent fashion. Since secluded hidden sectors are of particular interest for dark matter models at the MeV scale or below, we pay special attention to the reach of pulsar timing arrays. Cosmological constraints on light degrees of freedom restrict the number of sub-MeV particles in a hidden sector, as well as the hidden sector temperature. Ne…
Studying neutrinos at the LHC: FASER and its impact to the cosmic-ray physics
2021
Studies of high energy proton interactions have been basic inputs to understand the cosmic-ray spectra observed on the earth. Yet, the experimental knowledge with controlled beams has been limited. In fact, uncertainties of the forward hadron production are very large due to the lack of experimental data. The FASER experiment is proposed to measure particles, such as neutrinos and hypothetical dark-sector particles, at the forward location of the 14 TeV proton-proton collisions at the LHC. As it corresponds to 100-PeV proton interactions in fixed target mode, a precise measurement by FASER would provide information relevant for PeV-scale cosmic rays. By studying three flavor neutrinos with …
Hard X-ray Emission from Low Mass X-ray Binaries
2003
In this paper we review our current knowledge of the hard X-ray emission properties of old accreting neutron stars in low mass X-ray binaries, with particular attention to recent results obtained for the brightest sources of this class, the so-called Z sources. While less luminous low mass X-ray binaries often show quite hard spectra, sometimes extending up to energies g 100 keV, the spectra of Z sources are always very soft, dominated by thermal components with characteristic temperatures ∼ 3-6 keV. However, recent broad band observations revealed the presence of a weak hard (power-law) component that is sometimes present in the spectra of these sources. These observations have strengthene…
Antideuterons as an indirect dark matter signature: Si(Li) detector development and a GAPS balloon mission
2010
著者人数：11名
Current status and future plans for the general antiparticle spectrometer (GAPS)
2008
著者人数: 13名
Flare diagnostics from loop modeling of a stellar flare observed with XMM-Newton
2006
Abstract XMM-Newton data of an X-ray flare observed on Proxima Centauri provide detailed and challenging constraints for flare modeling. The comparison of the data with the results of time-dependent hydrodynamic loop modeling of this flare allows us to constrain not only the loop morphology, but also the details of the heating function. The results show that even a complex flare event like this can be described with a relatively few – though constrained – components: two loop systems, i.e., a single loop and an arcade, and two heat components, an intense pulse probably located at the loop footpoints followed by a low gradual decay distributed in the coronal part of the loop. The similarity …
Efficient three-step, two-color ionization of plutonium using a resonance enhanced 2-photon transition into an autoionizing state
2004
Resonance ionization mass spectrometry (RIMS) has proven to be a powerful method for isotope selective ultra-trace analysis of long-lived radioisotopes. For plutonium detection limits of $\rm 10^{6}$ to $\rm 10^{7}$ atoms have been achieved for various types of samples. So far a three-step, three-color laser excitation scheme was applied for efficient ionization. In this work, a two-photon transition from an excited state into a high-lying autoionizing state, will be presented, yielding a similar overall efficiency as the three-step, three-color ionization scheme. In this way, only two tunable lasers are needed, while the advantages of a three-step, three-color excitation (high selectivity,…