The analysis of the Higgs boson search predicted by the Standard Model of Particle Physics, presented by the ATLAS and CMS experiments of the Large Hadron Collider (LHC) at the European Center for Nuclear Research (CERN) last December , have been sent today for publication to Physics Letters B. After further analysis, the statistical significance of the results remains close to that presented at that seminar, highlighting the conclusion that the Higgs boson of the Standard Model, if it exists, is likely to have a mass between 116 and 131 GeV (gigaelectronvolts ), according to the ATLAS experiment, and 115-127 GeV, according to CMS.
“Our analysis of the Higgs boson of the Standard Model with the data obtained so far by the LHC leaves us in a very stimulating position for 2012,” said CERN Research Director Sergio Bertolucci.”With the data obtained this year, we will be able to confirm or definitively rule out the Higgs boson predicted by the Standard Model.”
The Standard Model of Particle Physics is the theory that describes the behavior of fundamental particles and the forces that interact with each other. It describes the ordinary matter that we are made of and everything we see in the Universe. However, the Standard Model does not describe 96% of the Universe, which is invisible. One of the main objectives of the LHC research program is to look for physics beyond the Standard Model, for which the Higgs boson could be the key.
The existence of the Higgs boson as predicted by the Standard Model would confirm this theory, proposed in the 1960s, but there are other models of the Higgs boson related to theories that go beyond the Standard Model. Even a Higgs boson like the one proposed by the Standard Model could point the way to new physics through subtleties in their behavior that would arise after studying a large number of Higgs particle decays.
A Higgs boson other than the Standard Model, currently outside the scope of the LHC experiments with the data obtained so far, would immediately open the door to new physics, considering that the absence of a Higgs boson of the Standard Model would strongly indicate the presence of new physics in energy for which the LHC,14 TeV (teraelectronvolts), is planned to be achieved after 2014. Whether or not ATLAS and CMS show in the coming months that the Higgs boson of the Standard Model exists or not , the LHC program is opening the way to new physics.
Since the launch of the ATLAS detector , where 3,000 scientists from 174 institutions from 38 countries participate, researchers from the Institute of Corpuscular Physics ( IFIC ), a joint center of the Higher Council for Scientific Research ( CSIC ) and the University of Valencia ; the Institut de Fisica d’Altes Energies ( IFAE ), a consortium between the Generalitat de Catalunya and the Autonomous University of Barcelona ; the Institute of Microelectronics of Barcelona (CNM? IMB? CSIC); and the Autonomous University of Madrid ( UAM), actively participate in the operation and maintenance of the detectors, with a strong presence in the alignment and calibration activities.
Within the broad research program of the LHC, Spanish groups in ATLAS participate in a large number of research lines in the analysis of the data, which cover many of the most interesting a priori topics of the LHC program. In particular, in the case of the search for the Higgs boson of the Standard Model, the groups have studied different final states resulting from the disintegration of the Higgs particle into two photons, two taus leptons, and two Z or W bosons.
For its part, in CMS , where 3,000 scientists from 172 institutes in 40 countries participate, experimental groups from the Institute of Physics of Cantabria ( IFCA ), mixed center CSIC-University of Cantabria; the University of Oviedo ; the Center for Energy, Environmental and Technological Research ( CIEMAT); and the Autonomous University of Madrid (UAM), which participate in the search for the Higgs boson. It highlights the relevant participation of researchers from the University of Oviedo and IFCA in the analysis of the Higgs boson decay channel in WW bosons, and the CIEMAT and UAM researchers in the ZZ boson decay channel, both very relevant in this search and that have been key to exclude that its mass is between 127 and 600 GeV.
The participation of the Spanish research groups in the LHC is supported by the National Particle Physics Program and the National Center for Particle, Astroparticle and Nuclear Physics (CPAN), Consolider-Ingenio 2010 project whose main objectives are the promotion and scientific coordination of the Spanish participation in international projects, the development of common R&D activities and the training and incorporation of new researchers and technicians into the groups. The CPAN intends to consolidate these actions by establishing a permanent network center, analogous to those existing in other countries around us.