### A circle around Higgs boson

After the post about D0 abstracts, I return to write about Higgs boson after the last Fermilab's press release about the mass limit of Higgs boson. Combinig data from D0 and CDF, Tevatron's limits are 114-137 GeV/c2. The results was presented last week in Grenoble at the EPS High-Energy Physics conference, that it will finish on the 27th July.
During the same conference also LHC's experiments presented their first results, analyzed in about one month! And the conclusion seems un-huppy for Tevatron: the Fermilab's particle accelerator has only one chance to find Higgs boson before LHC. Why? We can simply see the following plots presented by ATLAS and CMS (via Résonaances, Tommaso Dorigo):

The two european experiments presented only a little region around 115 GeV/c2, the Tevatron's region, to 140 GeV/c2. The data from this region are probably analized and published before the end of the year, so we must wait only some months to know if Tevatron could found Higgs or not(1).
Tomasso examined in details some CMS preprint in which they are studied a lot of Higgs production channels, and also Philip Gibbs write a great summary about LHC presentations, who realize a great conclusion plot:

### Observation of a new neutral baryon

In the origin (late 1960s) the particle zoo(1) is the colloquially word used to describe the extensive list of known elementary particles. Indeed, before Standard Model becames the more accepted theory in particle physics, physicists discovered a lot of particles in their accelerators, but we know today that they are simply a combination of a little numbers of particles classified in three fundamental families: leptons, quarks (that they constitute fermions, particles with half-integer spin) and bosons (particles with integer spin).
We can classify also particles in a lot of sub-families, like baryons, the heavy particles constituted by three quarks: for example proton and neutron are barions, with the following composition: uud and udd respectively, where u is the up quark and d the down quark.
We know six types of quarks: up (u) and down (d), that explain protons and neutrons, charm (c), strange (s), top (t) and bottom (b) that explain a lot of other heavy particles. Standard Model predicts a series of combination of this quarks that they are summirized in a picture like this:
In the up there is with angular momentum $J =1/2$ and down with angular momentum $J=3/2$. Today we examine $J=1/2$ group, in particular to the last discover by CDF, one collaboration at Tevatron in Fermilab. Indeed, not all particles predicted by SM are found, and the hunt to them is open. On the 20th July, Pat Lukens announced the first observation of $\Xi_b^0$, a baryon with the structure usb:
In orther to detect the new baryon, researchers at Tevatron must reconstruct the following decay chain:

### Brian May, astrophysicist

Brian May is the famous guitarist of the Queen, Freddie Mercury's rock band (and one of my favourite band!), but is also an astrophysicist!
He wasborn 19 July 1947 in Twickenham, London. He studied mathematics and physics at Imperial College, where he started also the PhD program, but he abandoned when Queen became a succesful band in the world. He completed his PhD in 2007(5), but he did not forget his research activity, indeed he written with Patrick Moore and Chris Lintott Bang! – The Complete History of the Universe (2006)... but... just a moment... research activity? Yeah!
In 1972 and 1973 two papers signed by Mr.May are be published: MgI Emission in the Night-Sky Spectrum and An Investigation of the Motion of Zodiacal Dust Particles (Part I), written with Mr.Hicks and Mr.Reay.
May and collegues are interestend in zodiacal light, in particular in MgI spectrum, near the 5183.62 Å wavelength.
The importance of this kind of studies is that the MgI and MgII formation is one feature in the interaction between atmosphere and star radiations(2, 3).
But go to the papers: in order to determine the absorbtion lines from zodiacal light, Brian and friends used the Fabry-Perot interferometer:
The method was to sample, for 48 s, each of up 18 points acrossthe spectral interval. Pulse counting electronics and a line printer recordedthe signal levelat each sample point. A second channel of pulse counting monitored the overall sky background over a widewaveband, thus allowing correction forfluctation in sky transparency. The resolving power of the interferometer was 3500, corresponding to an instrumental profile width of 1.5 Å.
Obesrvation time is September, October 1971 and April 1972 from the observatory at Izana on Tenerife, Canary Islands.

### D0 abstracts: Higgs limits and dimuon asymmetry

I usually publish abstract's digests on posterous, but in this case I think this is necessary an exception. D0 collaboration at Tevatron, indeed, released two papers on arxiv, and I think that it is important sharing with the much number of readers their work. I startwith Search for neutral Higgs bosons decaying to $\tau$ pairs produced in association with $b$ quarks in $p \bar{p}$ collisions at $\sqrt s = 1.96$ TeV, shared by Tommaso:
We report results from a search for neutral Higgs bosons produced in association with b quarks using data recorded by the D0 experiment at the Fermilab Tevatron Collider and corresponding to an integrated luminosity of 7.3 $fb^{-1}$. This production mode can be enhanced in several extensions of the standard model (SM) such as in its minimal supersymmetric extension (MSSM) at high tanBeta. We search for Higgs bosons decaying to tau pairs with one tau decaying to a muon and neutrinos and the other to hadrons. The data are found to be consistent with SM expectations, and we set upper limits on the cross section times branching ratio in the Higgs boson mass range from 90 to 320 $GeV/c^2$. We interpret our result in the MSSM parameter space, excluding tanBeta values down to 25 for Higgs boson masses below 170 $GeV/c^2$.
The other two papers are in Antimatter Tevatron mystery gains ground, a great BBC's article. In particular BBC writes about Measurement of the anomalous like-sign dimuon charge asymmetry with 9 $fb^{-1}$ of $p \bar{p}$ collisions:

### A solution to a maximal independent set problem

A distributed system is a set of autonomous computer that comunicate in a network in order to reach a certain goal. So a maximal independent set (MIS) is a distributed system's subject. But, what we intend for MIS?
In graph theory, a maximal independent set or maximal stable set is an independent set that is not a subset of any other independent set.
Some example of MIS are in the graph of cube:
You can see that every maximal independent set is constituted by point that aren't adjacent.
The goal of maximum independet set problem is find the maximum size of the maximal independent set in a given graph or network. In other words the problem is the search of the leaders in a local network of connected processors, and forleaderwe intend an active node connected with an inactive node. This problem is a NP-problem.
Following Afek, Alon, Barad, Hornstein, Barkai and Bar-Joseph,
no methods has been able to efficiently reduce message complexity without assuming knowledge fo the number of neighbours.
But a similar network occurs in the precursors of the fly's sensory bristles, so researchers idea is to use data from this biological network to solve the starting computational problem!
Such system is called sensory organ precursors, SOP.