Question

One of the predictions of the Standard Model is the Higgs boson' - a new short-lived particle. It is common in particle physics to search for particles by looking at the products of particle collisions. In case of the Large Hadron Collider, it is usually the head-on collision of two highly energetic proton beams formed by bunches of around 1011 protons passing each other roughly 40 million times per second. If one measures all the collision products the final distribution must be formed by the allowed production channels. In particular, figure 1 represents a distribution of events where we measure two photons moving in opposite directions after a proton-proton collision as a function of their rest energy. This quantity can be retrieved directly from experimental data? 2000 1800 Data B+S (fit) ...B B Uncertainty 1600 1400 1200 Number of Entries 1000 800 600 400 200 0 120 140 my (GeV) Figure 1: Histogram showing the rest mass spectra for Higgs boson collisions from the 2012 discovery, published by the CMS experiment [1]. These particular collisions are tagged by the presence of back-to-back emissions of gamma rays. The yellow and green lines represent the background significance level of one sigma and two sigma respectively. When two protons collide, they can form short-lived particles that can further decay into photons - the number of these events depends on all possible decay channels. Among the possible decay channels is that of the Higgs boson (H → vy). If the Higgs boson did not exist, we would expect a background formed only by the decays of the other allowed collision products - this is represented by the red dashed line in figure 1 and can be well described by an exponential distribution. The excess Higgs signal corresponds to the small bump around 125 GeV, which sits on top of the large background. The signal shape can be parameterised

Hi, sir.

I am doing an assignment, but I don't know the meaning of this graph.

Could you explain :

(1) the process of forming Higg Boson

(2) What is the meaning of x,y axes

(3)What is the meaning of background

Thanks a lot.

Answer 1

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