The boson, the spin and the graviton

Some days ago, ATLAS has been released a draft about the spin of the new boson. The decay channels studied are the fab four: $H \rightarrow \gamma \gamma$, $H \rightarrow WW^*$, $H \rightarrow l\nu l\nu$, $H \rightarrow ZZ^* \rightarrow 4l$. The idea is combining data from the four channels in order to understand the spin of the new boson, in detail to distinguish between two cases: spin 0 ($J^P = 0^+$), and so a boson compatible with the Standard Model, and spin 2 ($J^P = 2^+$), that it could be connected with a model (arXiv) that represents a light coupling between the Standard Model's fields and the hypothetical graviton.
These the ATLAS' conclusions:

The data are in good agreement with the expected distributions of a $J^P=0^+$ particle while the graviton-inspired $J^P=2^+$ model, that is expected to be produced dominantly via the gluon fusion process, is excluded at more than 99.9% confidence level.

We could say that it starting the elimination process of the models that would lead the research of the new physics beyond the Standard Model for the next years. A good luck to all of them, but we don't forget the key role of the Standard Model, that is in some sense confirmed by this last draft from ATLAS.

Letter to LHC by Peter Higgs

posted by @ulaulaman via @marcodelmastro #LHC #PeterHiggs #boson #ATLAS #CMS

From Observation of a new particle at LHC: Booklet / Journal issue via Marco Delmastro

Is it the Higgs? The spin will tell us!

a couple of video about #Higgs via @CMSexperiment posted by @ulaulaman

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:

Habemus papers (about the new boson)

posted by @ulaulaman thanks to @tanzmax @spimpompam #Higgs #boson #newboson #LHC #CMS #ATLAS #CERN

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)

Les Cernettes

posted by @ulaulaman about #LesHorriblesCernettes #music #cern #HardronicMusicFestival

Les Horribles Cernettes is a rock-swing group that started its activity with the... birth of the web!
Indeed the first photo uploaded on web by Tim Berners-Lee was a promotional photoshop by the fab four girl from LHC!

The group is, today, formed by three girls Michele de Gennaro, Anne MacNabb, Colette Marx-Nielsen, and this is the original story from the official web site:

Once upon a summer there was a girl. She was a CERN secretary tired of waiting day and night for her permanently-on-shift physicist boyfriend, and so she decided to attract his attention by stepping on stage during the CERN Hardronic Festival to sing about her lonely nights in front of the entire CERN population. She asked Silvano [de Gennaro, an IT developer who worked with Tim Berners-Lee] to write a song about her life and a couple of girlfriends to back her up on stage. A few weeks later the Cernettes were on stage for the first time, for the delight of thousands of happy Physicists, singing Collider, the song that since that day became the National Anthem of the High Energy Kingdom.

Their first success was Liquid Nitrogen, but today I would share a live version of Mr. Higgs:

Joe Incandela talks about the new boson

#newboson #cern #cms #JoeIncandela #Higgs #lhc #video #youtube #physics

Linux at CERN

#linux #cern #lhc #physics #newboson #Higgs

On reddit (via Ubuntu Vibes) an anonimous researcher from CERN published the following message:

I don't see any CERN related things here, so I want to mention how Linux (specifically, Scientific Linux and Ubuntu) had a vital role in the discovery of the new boson at CERN. We use it every day in our analyses, together with hosts of open software, such as ROOT, and it plays a major role in the running of our networks of computers (in the grid etc.) used for the intensive work in our calculations.
Yesterday's extremely important discovery has given us new information about how reality works at a very fundamental level and this is one physicist throwing Linux some love.

If you want, you can download the distributions used at CERN at the page Linux @ CERN. The CERN distribution is a Scientific Linux (a distribution used also at Fermilab) rebuilded with the Red Hat. In general the Linux distributions are the most used in the scientific world, in particular in physics and mathematics, and the reasons are the same that the anonimous research writes in another comment:

In terms of data analysis, Windows could be used in principle. We could also use some type of device that manipulates symbols on a strip of tape according to a simple table of rules. Linux is used because it is most appropriate for the job. Linux is ubiquitous in HPC and we use a lot of computing power in LHC physics, so the arguments for the use of Linux in HPC are very similar to the arguments for the use of Linux in LHC physics analyses. Naturally, it's important to have an operating system that is free, open source and reliable (Scientific Linux is basically Red Hat Linux), but here's a quotation from the Scientific Linux website that should give some idea of why Scientific Linux is needed:
"Our main goal for the base distribution is to have everything compatible with Enterprise, with only a few minor additions or changes. Examples of items that were added are Alpine, and OpenAFS.
Our secondary goal is to allow easy customization for a site, without disturbing the Scientific Linux base. The various labs are able to add their own modifications to their own site areas. By the magic of scripts, and the anaconda installer, each site is to be able to create their own distributions with minimal effort. Or, if a user wishes, they can simply install the base SL release."
I work primarily in physics, not in computing, so I doubt that I am able to argue very competently for Linux over something such as BSD. The fact is that Linux was the operating system used in the overwhelming majority of the analyses contributing to the discovery, so, in that sense I think I am justified in claiming that Linux played a vital role in the discovery.

And he also writes about Apple and Comic Sans:

In many ways, some Apple fans are similar to religious people in their devotion to something; that is, their support is not really derived from a critical appraisal of the technical standard of Apple products. I don't identify with this kind of motivation, but I am much happier seeing people religiously attached to new technological gadgetry than to invisible sky daddies.
Similarly, Comic Sans is grotesque, but if it contributes to directing attention to the recent discovery, then it could be argued that it is a good thing.
In direct answer to your question, I think that you can thank Microsoft Bob for the existence of Comic Sans.

And finally he explain (one of many) that, with the data collected since june 2012, we can say that the new particle is a new boson, but we are not certain that it is a Higgs boson:

The properties of the discovered boson have yet to be scrutinised thoroughly before one can reliably claim it to be a Higgs boson (note that I do not claim the discovered boson to be the Higgs particle in the post). This is a phase of analysis we are now moving into.

And don't forget to read the post about the discover of the new boson!

Discovering a boson

posted by @ulaulaman #Higgs #ICHEP2012

I'm partially wrong! Yesterday I write that no Higgs could be announced, but today ATLAS and CMS presented the observation of a new boson, that it's to soon to identify with certainty like the Higgs boson, but it is certainly a new boson to add to the picture of the universe. The next quest is to find its properties and to confront with the theoretical properties of the Higgs boson. It could be that the new boson presented today could be different for a bit of properties from the Higgs, but this is not so incredible: like I write, with a Higgs boson with a mass around 125 GeV, we need other ingredients to complete a picture of our stable universe.

Candidate Higgs decay to four electrons recorded by ATLAS in 2012 (source ATLAS)

But... what did it happen today?
The two experiments, CMS, represented by Joe Incandela, and ATLAS, represented by Fabiola Gianotti, showed the results of their last data elaboration about Higgs research. The results come from the combination of the complete data set from 2011 (see, for example, the ATLAS' preprint) with the first part of data from 2012. The conclusions are: CMS sees an excess with $m_H = 125.3 \pm 0.6 GeV$ with a significance of $4.9 \sigma$; ATLAS sees an excess with $m_H = 126.5 GeV$ with a significance of $5.0 \sigma$, that it means discover!

CMS' final result

ATLAS' final result