“God particle” ???“Goddamn particle” since it was so difficult to find

Moo-Young Han Editor-in-Chief,  IEKAS To Higgs or Not to Higgs The July the 4th week has seen more than the traditional fireworks celebrating the Independence Day, at least among the global community of physicists. On July the 2nd, the latest update on the search for the Higgs particle by two teams at the Fermi National Laboratory (Fermilab) near Chicago reported “strong evidences” for the particle (This was the last hurrah for the Fermilab whose accelerator Tevatron was shut down for good last fall). This was followed on July the 4th by a climactic seminar and press conference at CERN in Geneva, Switzerland during which two groups at the Large Hadron Collider (LHC) reported, much to the applause of the global physics community, almost-discovery of the long-sought-after Higgs boson. As the news spread, the media went into frenzy: the “God particle” discovered that explained how all matter in the Universe got their masses in the first place. Some commentators went even beyond the hyperbole: it is the greatest physics achievement since Newton and Einstein and it explains why the Universe was created at all – why the Big Bang “banged!” [The name “God particle” is not well embraced by the physics community. When the Nobel laureate Leon Lederman penned a book about the particle physics, he wanted to call this Higgs boson a “Goddamn particle” since it was so difficult to find. The publisher of the book however objected and suggested shortening it to “God particle.” The name stuck much to the chagrin of the physicists.] To be sure, it is a climax for the LHC, the largest particle accelerator in the world, its incredibly smooth operation, and the discovery of an entirely new particle never seen before: it is a scalar boson (spin zero) that decays in a manner consistent with the way the Standard Model Higgs boson would decay. 5 But the leaders of LHC experiments as well as the Director of the lab stopped short of calling it the discovery of the Standard Model Higgs boson, at least not yet, with good reasons. To put this in perspective, the proton-proton collisions at LHC occur at the rate of some 40 million times per second, as two bunches of protons traveling in opposite directions at almost the speed of light collide in mini-big-bang like fireballs some trillion times during the experiments. There is no way to analyze all those collisions and a grid of state-of-the-art computers are programmed to pick out set of collisions according to the simulated triggering instructions. Out of some 40 million collisions per second, some 300 events are selected by computers for full analyses. The selection criteria are determined by theoretical calculations and simulations by the rules of the Standard Model. The rest, 40 million minus 300 events, that may contain wealth of significant events, are thrown away as “junk.” The results presented at the July the 4th seminar at CERN are based on the selection of events corresponding to the production of a single Higgs boson and its subsequent decays. The new scalar particle discovered may have many other decay modes that are not selected for examination. Even within the confines of the Standard Model, there are still many other decay modes available for the Higgs boson, including production of two or three Higgs bosons at yet higher energies. To sum up, LHC experiments did indeed discover a boson that, among other decay modes, decays the same way the Higgs boson would decay. To quote John Ellis, theoretical physicist at CERN, “it will take at least until the end of 2012 to decide whether this new particle is indeed the Standard Model Higgs boson or not.” No doubt it was a great discovery that will open up new vista beyond the Standard Model, but we should take more cautious position on this and not carried away by the frenzy of the media and some far-out commentators.