### Is it the Higgs? The spin will tell us!

The CMS experiment posted on its Google Plus page a couple of video about the new boson and the future research of its spin, an important tool in order to understand if the new particle is a Higgs boson or someone like it, but with some, little differences:

### The birth of a planet

When I write about the Nice model, I explain how a group of researchers try to explain the birth of our Solar System. The approach of the group is to design some simulations about the dynamics of the whole Solar System. This approach is very used in physics, in particular when calculation by hand are too complicated. So, today I would propose you a video with the interview to a new group that perform some simulations in order to explain how a planet could born. The group, leaded by Sally Dodson-Robinson is
(...) carrying out a series of computer simulations of the proto-stellar disks. The simulations provide some important parameters, such as the turbulence and the temperature of the disc, which influence how and where the planets are formed. In a disk with a high percentage of turbulence, the particles forming the planetesimals move very quickly and go away from each other. At the other hand, in a less turbulent situation, there will be a much more probability that the particles collide and are aggregated together in order to give rise to future planets. In 1988, it was known only an extrasolar planet, and today almost 2400 waiting to be confirmed. Therefore, understanding those favorable conditions for the formation of a planet will allow astronomers to discover more and more of them and, at the same time, will provide important new clues about the birth and evolution of the Earth and then of the Solar System.(1)

(1) Translated from AstronomicaMens

### The invisible universe

Today will be open in Milano an exhibition about the x-ray astronomy in order to celebrate the discover of the first cosmic x-ray source in 1962. And today I try to resume the story of this research.
The beginning of this branch of the astronomy is in 1946 when Bruno Rossi, who has worked with Enrico Fermi during Manhattan project, started to deal with physics of cosmic rays while teaching at MIT about X-ray. In 1958, with the birth of the American Science & Enginnering (AS&E), Bruno Rossi joined it as chairman of the board of directors and scientific advisor and a year later he called to work even Riccardo Giacconi. One of the first experimental successes includes the launch of the first rocket equipped with detectors for X-rays in 1962. The team of this project as well as Giacconi included, Herb Gursky, Frank Paolini, and Bruno Rossi. With this mission, it was reported the first cosmic X-ray source outside the sun, Scorpius X-1 in the constellation Scorpius.(1, 2)
The uniqueness of the observations of Scorpius X-1 is due mainly to its properties. In fact, while the X-radiation from the sun has an intensity that is approximately 10-6 times than visible light, Scorpius X-1 has a X-brightness that is 103 times higher than its same brightness in the visible light. It was subsequently discovered that its intrinsic brightness is 103 times that of the Sun!(1)
There was therefore in front of the discovery of new celestial objects, which had X-rays produced in different physical processes compared to the processes made in the laboratories of the Earth, since their efficiency (99.9%) was unmatched!(1)
1960s were, therefore, rich for X-rockets into space, but for the very first X-satellite was launched only in 1970 thanks to a new group leaded by Giacconi(1):
The X-ray astronomy achieved great success with the launch of the first satellite dedicated to X-rays, Uhuru, launched in 1970, with it performed an initial mapping of the X-ray sources in space. It was discovered that the universe is full of objects that emit X-rays, from the black holes to the pulsars, to the binary stars. In fact after this mission, the X-ray astronomy assumes an important role between the international scientific community. It soon became clear that, in order to better understand the secrets of the sky, instead of simply detecting the X-rays, it would be useful to make observations with a telescope sensitive to X-rays. The development of this telescope began with the entry into AS&E team of Giuseppe Vaiana, who leaded the program about the solar X-ray astronomy and the construction of the first telescope. In 1973, Skylab was launched, the U.S. space laboratory directed by Vaiana, that, in addition to various scientific experiments, carried on the observation of the Sun and the corona in X-rays. In 1978 it was sent into orbit the Einstein Observatory, the first X-ray space telescope. The important discoveries of the ROSAT and Chandra followed.(2)
One of the successive results of astronomy X, always signed Giacconi, in this case with Ethan Schreier, was the discovery of an X-ray source around Cen X-3(1).
Very important discoveries of Uhuru, however, were mainly those concerning the existence of neutron stars and binary systems consisting of a visible star and an unseen companion, a black hole(1)!

### In serach of the ETs with the distributed computing

One of the most intriguing question of the mankind is if we are alone in the universe, if in a some little part of the cosmos it exists intelligent life. Starting from this quest, a lot of science fiction writers gave us some good sci fi novels. For example The Voyage of the Space Beagle by Alfred Elton van Vogt, inspired by the journey of Charles Darwin on the Beagle. In this novel, during the search of alien life, the spaceship Argus found not only vestiges of vanished civilizations, but also interacted with real aliens.
But the research for other cosmic intelligences beyond the limits of our Solar System has also fascinated, for many reasons, the scientists themselves. It is famous the dinner (or maybe it was a lunch) where Enrico Fermi explained his equally famous paradox from which Frank Drake drew inspiration for his famous equation. And Drake became one of the founders of the SETI project(5), Search for extraterrestrial intelligence, a project that involved a lot of researchers around the world. This kind of research, which may seem absurd as to get the ghostbuster, is based, first, on the assumption that
(...) an alien civilization wishing to make contact with other races would broadcast a signal that is easily detectable and easily distinguishable from natural sources of radio emission. One way to achieve these goals is to send a narrowband signal. By concentrating the signal power in a very narrow frequency band, the signal will stand out among the natural broadband sources of noise.(1)
At the beginning SETI focused its activity on listening to radio signals from space. The type of signal that should be detected presents some problems: first, the frequency stability, caused by the acceleration of the transmitter and receiver(1), which for example they are influenced by the speed of rotation (around the axis, around the star). Solving this problem is not in principle impossible: certainly we know very well the properties of our planet in order to perform this kind of correction, but it is not the same thing for an alien planet. In this last case, the story is certainly very different, especially if the planet is completely unknown
An alien civilization narrowly beaming signals at the earth could correct the outgoing signal for the transmitter's motions, but a civilization transmitting an omnidirectional beacon could not make such an adjustment.(1)
One way to remedy is to use the Doppler effect(1), but this means making a lot of calculations, and answering to a lot of questions about the characteristics of the signal itself:
at what frequency will it be transmitted? What is its bandwidth? Will it be pulsed? If so at what period? Fully investigating a wide range of these parameters requires proportionally larger computing power.(1)
And we don't forget that we have to understand if the detected signal with a presumed extraterrestrial origin is not, in reality, of cosmic origin (i.e. produced by a star or a galaxy or some other not artificial object traveling in space).
All these calculations are extremely complex and require a much greater computing power than supercomputers. It is for this reason that in 1995, David Gedye, a project manager at Starwave Corp., proposed to use the distributed computing in order to create a virtual supercomputer: the birth SETI@home(2).
The first step in the construction of the project is to find a good radio telescope. The ideal candidate was the telescope in Arecibo, Puerto Rico, administrated by Cornell University and the National Science Foundation(2). This choice, however, had a small problem: the time of use. SETI could not have the exclusive use of the telescope, because it was already being used for various astronomical and meteorological researches. The problem was solved in 1997 by Berkeley's SERENDIP project, who developed a technique to use a second antenna(2).

### Habemus papers (about the new boson)

Finally Physics Letters B published the two papers by ATLAS and CMS about the discovery of the new boson at LHC (via tanzmax):
A search for the Standard Model Higgs boson in proton–proton collisions with the ATLAS detector at the LHC is presented. The datasets used correspond to integrated luminosities of approximately $4.8 \, fb^{−1}$ collected at $\sqrt{s} = 7$ TeV in 2011 and $5.8 \, fb^{−1}$ at $\sqrt{s} = 8$ TeV in 2012. Individual searches in the channels $H \rightarrow ZZ^{(*)} \rightarrow 4l$, $H \rightarrow \gamma \gamma$ and $H \rightarrow WW^{(*)} \rightarrow e \nu \mu \nu$ in the 8 TeV data are combined with previously published results of searches for $H \rightarrow ZZ^{(*)}$, $WW^{(*)}$, $b \bar{b}$ and $\tau^+ \tau^-$ in the 7 TeV data and results from improved analyses of the $H \rightarrow ZZ^{(*)} \rightarrow 4l$ and $H \rightarrow \gamma \gamma$ channels in the 7 TeV data. Clear evidence for the production of a neutral boson with a measured mass of 126.0 ± 0.4 (stat) ± 0.4 (sys) GeV is presented. This observation, which has a significance of 5.9 standard deviations, corresponding to a background fluctuation probability of 1.7 × 10−9, is compatible with the production and decay of the Standard Model Higgs boson.
Aad, G., Abajyan, T., Abbott, B., Abdallah, J., Abdel Khalek, S., Abdelalim, A.A., Abdinov, O., Aben, R., Abi, B., Abolins, M. & (2012). Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC, Physics Letters B, 716 (1) 29. DOI: 10.1016/j.physletb.2012.08.020
Results are presented from searches for the standard model Higgs boson in proton–proton collisions at $\sqrt{s} =$ 7 and 8 TeV in the Compact Muon Solenoid experiment at the LHC, using data samples corresponding to integrated luminosities of up to $5.1 fb^{−1}$ at 7 TeV and $5.3 fb^{−1}$ at 8 TeV. The search is performed in five decay modes: $\gamma \gamma$, $ZZ$, $W^+ W^−$, $\tau^+ \tau^-$, and $b \bar{b}$. An excess of events is observed above the expected background, with a local significance of 5.0 standard deviations, at a mass near 125 GeV, signalling the production of a new particle. The expected significance for a standard model Higgs boson of that mass is 5.8 standard deviations. The excess is most significant in the two decay modes with the best mass resolution, $\gamma \gamma$ and $ZZ$; a fit to these signals gives a mass of 125.3 ± 0.4 (stat.) ± 0.5 (syst.) GeV. The decay to two photons indicates that the new particle is a boson with spin different from one.
Chatrchyan, S., Khachatryan, V., Sirunyan, A.M., Tumasyan, A., Adam, W., Aguilo, E., Bergauer, T., Dragicevic, M., Erö, J., Fabjan, C. & (2012). Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC, Physics Letters B, 716 (1) 61. DOI: 10.1016/j.physletb.2012.08.021

To the previous papers, I add also the following (via spimpompam), that it could be interesting to read:
Following recent ATLAS and CMS publications we interpret the results of their Higgs searches in terms of Standard Model operators. For a Higgs mass of 125 GeV we determine several Higgs couplings from 2011 data and extrapolate the results towards different scenarios of LHC running. Even though our analysis is limited by low statistics we already derive meaningful constraints on modified Higgs sectors.
Klute, M., Lafaye, R., Plehn, T., Rauch, M. & Zerwas, D. (2012). Measuring Higgs Couplings from LHC Data, Physical Review Letters, 109 (10) DOI: 10.1103/PhysRevLett.109.101801 (arXiv)