There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

https://biblio.ugent.be/publication/685594/file/1130605.pdf

Review of Particle Physics

http://risa.stanford.edu/teaching/362/particledarkmatter.pdf

Particle dark matter: Evidence, candidates and constraints

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

/pdf/the-observation-of-gravitational-waves-from-a-binary-black-58srpupgg9.pdf

The Observation of Gravitational Waves from a Binary Black Hole Merger

The channeling of the recoiling nucleus in crystalline detectors after a WIMP collision would produce a larger scintillation or ionization signal in direct detection experiments than otherwise expected. I present estimates of channeling fractions obtained using analytic models developed from the 1960's onwards to describe channeling and blocking effects. We find the fractions to be too small to affect the fits to potential WIMP candidates. I also examine the possibility of detecting a daily modulation of the dark matter signal due to channeling.

Recoiling Ion-Channeling in Direct DM Detectors

After a brief introduction to dark matter in general and to WIMPs as candidates, we review recent results of direct dark matter searches. We concentrate on older and more recent hints pointing to light WIMP’s with mass below 10 GeV. 1. Dark Matter: what we know We know a lot about dark matter (DM). We know its abundance in the Universe to a few percent level, we know most of it is not baryonic and we know that it is not explained within the Standard Model (SM) of elementary particles. WMAP 7 year Cosmic Microwave Background anisotropy data combined with Type Ia supernovae and the Baryon Acoustic Oscillations data, give a total matter density fraction m = 27.8 ± 1.5% and, in agreements with Big-Bang Nucleosynthesis (BBN) data, a baryon abundance which is only 4-5% of the total density, b = 4.61±0.15%, so the rest of the matter is in DM, DM = 23.2±1.3% 1) . We know also from structure formation arguments that the bulk of the DM can only be either Cold (CDM) or Warm (WDM) (i.e. non-relativistic or becoming non-relativistic when the temperature of the Universe was T ≃ keV). Among the particles of the SM only neutrinos are part of the DM and they are Hot DM (i.e. relativistic when T ≃ keV). There are no WDM or CDM candidates in the SM, but there are many in all SM extensions. Because of spontaneous symmetry breaking arguments totally independent of the DM issue, we do expect new physics beyond the SM to appear at the electroweak scale explored by the Large Hadron Collider (LHC) at CERN. Physics beyond the SM is required by the DM and expected at the electroweak scale, but both new physics may or may not be related. Thus the experiments at the LHC and the searches for the DM in our galactic halo are independent and complementary. We will concentrate in the following on Weakly Interacting Massive Particles (WIMPs) as DM candidates.

Direct Dark Matter Searches: Fits to WIMP Candidates

Generations in the rishon model

This is an idiosyncratic account of the main results presented at the 31st Rencontres de Blois, which took place from June 2nd to June 7th, 2019 in the Castle of Blois, France.

Blois 2019: highlights and outlook.

Sub-GeV mass dark matter particles whose collisions with nuclei would not deposit sufficient energy to be detected, could instead be revealed through their interaction with electrons. Analyses of data from direct detection experiments usually require assuming a local dark matter halo velocity distribution. In the halo-independent analysis method, properties of this distribution are instead inferred from direct dark matter detection data, which allows then to compare different data without making any assumption on the uncertain local dark halo. This method has so far been developed for and applied to dark matter scattering off nuclei. Here we demonstrate how this analysis can be applied to scattering off electrons.

Graciela B. Gelmini

Papers

Recoiling Ion-Channeling in Direct DM Detectors

Direct Dark Matter Searches: Fits to WIMP Candidates

Generations in the rishon model

Blois 2019: highlights and outlook.

Halo-Independent Analysis of Direct Dark Matter Detection Through Electron Scattering