Could the Higgs boson have been discovered with earlier accelerators?

In summary, the LEP collider, which operated at a maximum of 209 GeV, was not able to confirm the existence of the 125.3 GeV Higgs boson due to the required energy for its production. The CERN teams examined the 145-466 GeV range first in the search for the Higgs boson, before examining the 125 GeV range where it was eventually found. This was due to the fact that at lower energies, it is easier to exclude or find the Higgs boson. The required collision energy to observe a Higgs boson is the sum of the Z and Higgs boson masses. The minimum number of collisions required to reach a five standard deviation significance for the H
  • #1
John Peterson
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Could the Higgs boson have been confirmed with earlier accelerators?

The LEP collider operated at a maximum of 209 GeV. Could it have been used to confirm the existence of the 125.3 GeV Higgs boson?

I also read on Wikipedia that the CERN teams were apparently examining the 145–466 GeV range first in the search for the Higgs boson with the LHC, as they reported a year ago that no Higgs boson existed in that range, before examining the 125 GeV range that it's now found at. What is the reason for this? Was it considered more probably to find the Higgs boson in the 145–466 GeV range than in the 125 GeV range?

Thanks!
 
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  • #2
With electron-positron collisions, you do not get a Higgs alone with a relevant rate. The dominant production channel is [itex]e^- e^+ \to Z \to ZH[/itex]. For a reasonable rate, the energy has to be high enough to produce a Higgs (~126 GeV if LHC found it) and a Z-boson (~90 GeV) at the same time. As you can see, LEP probably just missed it.

I also read on Wikipedia that the CERN teams were apparently examining the 145–466 GeV range first in the search for the Higgs boson with the LHC, as they reported a year ago that no Higgs boson existed in that range, before examining the 125 GeV range that it's now found at.
They examined the whole range at the same time. In the range of 145-400 GeV, it is easier (requires less data) to exclude or find the Higgs boson, as it would decay into two W or two Z bosons quite frequently.
 
  • #3
mfb said:
For a reasonable rate, the energy has to be high enough to produce a Higgs (~126 GeV if LHC found it) and a Z-boson (~90 GeV) at the same time. As you can see, LEP probably just missed it.
So the required collision energy to observe a H is the sum of the Z (91.2 GeV) and H (125.3 GeV) masses, 216.5 GeV?

Whats the minimum number of collisions (or samples) required to reach a five standard deviation significance for H existence? Tevatron place it at 125 GeV (halfway between their 115 and 135 range) with a 2.9 standard deviation significance from 500 trillion collisions[1].

How long does it take to observe 500 trillion collisions? The D0 experiment observe p+p collisions at a 1.7 M/s rate, meaning 9 years to observe 500 trillion collisions.
 
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  • #4
John Peterson said:
So the required collision energy to observe a H is the sum of the Z (91.2 GeV) and H (125.3 GeV) masses, 216.5 GeV?
It is not a sharp line between "possible" and "impossible", as the Z boson has a very short lifetime and therefore a broad energy spectrum, but the general concept is correct.

Whats the minimum number of collisions (or samples) required to reach a five standard deviation significance for H existence?
That depends on the amount of background. It is impossible to give any number, if you do not know the background level.

How long does it take to observe 500 trillion collisions? The D0 experiment observe p+p collisions at a 1.7 M/s rate, meaning 224 years to observe 500 trillion collisions.
A simple division would yield 9 years. However, the 1.7MHz refers to beam crossings - each crossing can have multiple proton-antiproton collisions. Therefore, the collision rate is higher in operation, and lower during downtimes (of course :p), and the total time required to take this data is something like 10 years again.
 

1. Could the Higgs boson have been discovered earlier by using other accelerators?

This is a commonly asked question and the answer is no. The Higgs boson is a very elusive particle and requires extremely high energies to be produced. Only the Large Hadron Collider (LHC) at CERN has the capability to reach these energies. Previous accelerators did not have the necessary energy levels to produce the Higgs boson.

2. Why is the Large Hadron Collider (LHC) the only accelerator that can discover the Higgs boson?

The LHC is the world's largest and most powerful particle accelerator, capable of reaching energies up to 13 TeV. This energy level is necessary to produce the Higgs boson, which is a very heavy particle. Other accelerators, such as the Tevatron at Fermilab, were capable of reaching energies up to 2 TeV, but this was not enough to produce the Higgs boson.

3. How long did it take for the Higgs boson to be discovered at the LHC?

The search for the Higgs boson began in the 1960s and it took about 50 years for it to be discovered at the LHC in 2012. This was a result of advancements in technology and the construction of more powerful accelerators, like the LHC, which were necessary to produce and detect the Higgs boson.

4. Is the discovery of the Higgs boson the end of particle physics?

No, the discovery of the Higgs boson is not the end of particle physics. It is a major milestone in understanding the fundamental building blocks of our universe, but there are still many unanswered questions and mysteries in the field of particle physics that scientists are working to unravel.

5. How does the discovery of the Higgs boson impact our understanding of the universe?

The discovery of the Higgs boson confirmed the existence of the Higgs field, which gives particles their mass. This is a crucial piece in the puzzle of understanding the fundamental forces and particles that make up our universe. It also supports the Standard Model of particle physics, but there are still many unanswered questions and theories that scientists are exploring in order to deepen our understanding of the universe.

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