Observation of a New Particle in the Search for the Standard Model Higgs Boson with the ATLAS Detector ATLAS Collaboration

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 Observation of a New Particle in the Search for the Standard Model Higgs Boson with the ATLAS Detector 2012 Physics Letters B / arXiv 1207.7214 atlas2012-higgs atlas2012-higgs.txt, the project's staged copy 44279439658c3bed68e04257f9d0bec37b25e52c arxiv-open physics

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 0 spans located by searching the stored text for the quote's exact words, allowing any whitespace between them Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. experiment Quotation withheld because this record is not cleared for redistribution. the whole search is reduced to ONE parameter of interest - a signal strength that scales the predicted signal - and it is defined so that zero is the background-only hypothesis and one is the Standard Model Higgs signal, so the hypothesis under test is a value of that one factor Quotation withheld because this record is not cleared for redistribution. hypothesised values of that strength are tested with a profile likelihood ratio, which extracts the signal strength from a full likelihood fit whose function INCLUDES all the parameters describing the systematic uncertainties and their correlations Quotation withheld because this record is not cleared for redistribution. exclusion is decided by a stated numerical rule rather than by judgement: a signal strength is excluded at 95% confidence when its CLs value falls below 5%, and a Standard Model Higgs of a given mass counts as excluded when the value one is excluded at that mass Quotation withheld because this record is not cleared for redistribution. the size of an excess is first expressed as the probability that background alone could produce a fluctuation at least that large, and only then converted into the equivalent number of standard deviations - the local significance Quotation withheld because this record is not cleared for redistribution. that local number is then corrected for having searched a whole mass range rather than one point: the ratio of global to local probability is the trials factor, and the paper states what it depends on - the range of hypotheses considered, the mass resolutions of the channels combined, and the size of the excess itself Quotation withheld because this record is not cleared for redistribution. the tests are run in steps across the hypothesised mass rather than at one chosen point, and the asymptotic approximation the results rest on is not assumed to hold - it is validated by a separately described method Quotation withheld because this record is not cleared for redistribution. the combination across channels is built on the same single signal strength together with an explicit identification of which nuisance parameters correspond to the CORRELATED sources of systematic uncertainty Quotation withheld because this record is not cleared for redistribution. the jet energy scale and resolution are handled by a deliberately simplified scheme - independent nuisance parameters attached to final states with materially different selections and process sensitivity - and the simplification is defended by measurement: the results were found insensitive to the assumptions made about how those sources correlate Quotation withheld because this record is not cleared for redistribution. what this limits: the identification of the particle, as distinct from its discovery: THESE RESULTS ARE COMPATIBLE WITH THE HYPOTHESIS THAT THE NEW PARTICLE IS THE STANDARD MODEL HIGGS BOSON, [but] MORE DATA ARE NEEDED TO ASSESS ITS NATURE IN DETAIL Quotation withheld because this record is not cleared for redistribution. what this limits: the 8 TeV WW analysis specifically: SINCE THE e-mu CHANNEL PROVIDES MOST OF THE SENSITIVITY OF THE SEARCH, ONLY THIS FINAL STATE IS USED - pile-up degraded the resolution the same-flavour states needed Quotation withheld because this record is not cleared for redistribution. what this limits: the 5.9 sigma figure as the discovery significance: the paper gives about 5.1 sigma globally over 110-600 GeV, and a different value again over a narrower range Quotation withheld because this record is not cleared for redistribution. what this limits: comparing significances across searches: the trials factor depends on the range of hypotheses considered, so the same excess yields different global significances Quotation withheld because this record is not cleared for redistribution. what this limits: the result as agreement with the Standard Model: the paper quantifies the compatibility at 1.5 sigma Quotation withheld because this record is not cleared for redistribution. what this limits: the new particle's spin: only spin-1 is disfavoured here, by the diphoton observation alone Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. eliminates: a background estimate taken from the same events as the signal - the reversed criteria give regions where the signal cannot be, and the background can therefore be measured rather than assumed · outcome (stated by the tagger, no quotation): held Quotation withheld because this record is not cleared for redistribution. eliminates: checking the background model on the very regions that were used to fit it - the distinction is what keeps the check independent of the fit · outcome (stated by the tagger, no quotation): held Quotation withheld because this record is not cleared for redistribution. eliminates: reliance on simulation for the backgrounds hardest to simulate - jets faking photons is precisely where Monte Carlo is least trusted, so that component is measured from data · outcome (stated by the tagger, no quotation): held Quotation withheld because this record is not cleared for redistribution. eliminates: having looked in many places and reported the luckiest - the look-elsewhere correction is what makes the quoted significance a statement about the search rather than about one bin · outcome (stated by the tagger, no quotation): held Quotation withheld because this record is not cleared for redistribution. local significance Quotation withheld because this record is not cleared for redistribution. global significance Quotation withheld because this record is not cleared for redistribution. trials factor Quotation withheld because this record is not cleared for redistribution. Standard Model Higgs boson Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. global significance local significance strength of the relation: 1 Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but the span reports the global significance of a local excess; distinct-from is loose. Quotation withheld because this record is not cleared for redistribution. trials factor global significance strength of the relation: 1 Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but the trials factor is the RATIO of global to local probabilities, used to correct; part-of is loose. Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. Quotation withheld because this record is not cleared for redistribution. Higgs boson mass mH Quotation withheld because this record is not cleared for redistribution. centre-of-mass energy √s Quotation withheld because this record is not cleared for redistribution. integrated luminosity Quotation withheld because this record is not cleared for redistribution. pile-up Quotation withheld because this record is not cleared for redistribution. SM Higgs boson Quotation withheld because this record is not cleared for redistribution. electroweak symmetry Quotation withheld because this record is not cleared for redistribution. Standard Model Quotation withheld because this record is not cleared for redistribution. pile-up Quotation withheld because this record is not cleared for redistribution. chi-square about this quote: QUOTE RECOVERED FROM THE PAPER'S OWN CHARACTERS. The recorded quote was LETTERS-ONLY IDENTICAL to this stretch of the staged text but not an exact substring of it - spaces, hyphens, ligature glyphs or mathematical operators differed, so it could never anchor. This is the file's own text between the same two letters: not produced by a rule about the damage, copied out of the file. Round-trip checked (the recovered span is letters-only equal to the original) and length-checked. The text as originally recorded is kept in evidence as extracted. Quotation withheld because this record is not cleared for redistribution. p-value Quotation withheld because this record is not cleared for redistribution. statistical-power Quotation withheld because this record is not cleared for redistribution.

The full text of this article is not redistributable, so it is not included here. The evidence sentences are withheld with it; the tag layer and its grounding status remain. The article itself is at https://arxiv.org/abs/1207.7214.