World's largest particle accelerator built by the CERN (European Organization for Nuclear Research) near the Franco-Swiss frontier near Geneva, Switzerland. It is designed to collide beams of protons of up to 7 TeV. It contains the important detectors ALICE, ATLAS, CMS and LHCb.

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7
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460 views

How do tracking detectors in particle accelerators create the pretty pictures we see?

I have read several sources about tracking detectors used in particle accelerators like LHC, but still have not found a more detailed source that can still be understood by a layperson like myself. I ...
7
votes
3answers
1k views

Why don't protons just bounce off each other in the LHC?

Ok, this might sound like a silly question, but I was wondering, when particles (e.g. protons) are smashed together in the LHC, why do they break up into dozens of other particles, as opposed to just ...
5
votes
1answer
60 views

Why does gg fusion dominate over q qbar annihilation at the LHC?

The cross section of top quark pair production is dominated at the LHC by gluon-gluon fusion, whereas at Tevatron, quark-antiquark annihilation is more prevalent. Why is this? I know the fundamental ...
4
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0answers
41 views

Will the new LHC data falsify some theories? [closed]

There are plenty of extensions of the Standard Model, that all agree until the energy scales that have already been explored, but will differ at the new energy range of 14 TeV. This means the data ...
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3answers
491 views

Could the LHC be used for fusion experiments? [duplicate]

Just looking at the beam energy and peak power for the LHC, 360 MJ and petawatts, respectively, dumped in about 100 µs, would this be sufficient to do useful fusion experiments?
2
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2answers
62 views

Practical understanding of energies in LHC collisions

Is visible light emitted at the point of collision in the LHC? If so, how bright? How much water could be heated up by 10 degrees celsius (this is the energy from collision only, not the energy to ...
1
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3answers
113 views

Dark matter: Will Special Relativity hold?

Part 1: It’s been said that dark matter makes up about 26 % of the universe. The restart of LHC would be dealing with the existence of dark matter also. Consider a situation that the results are ...
2
votes
1answer
77 views

Why can't a high intensity beam be injected into the LHC when the machine is empty

Watching this YouTube video about the LHC at around 3 minutes and 50 seconds into the video the narrator says... For machine protection reasons we are not allowed to inject a high intensity beam ...
1
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1answer
80 views

Engravings in “Wandering the Immeasurable” sculpture outside the CERN globe? [closed]

Does anyone have a PDF or a file that shows all of the engravings on the "Wandering the Immeasurable" sculpture by Gayle Hermick outside of the CERN globe of science and initiative?
6
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1answer
58 views

What's the next big goal of the Large Hadron Collider?

Obviously, physics lovers everywhere were excited at the announcement that the LHC had verified the existence of the Higgs Boson. As a non-physicist, I like to keep up with what I can regarding the ...
5
votes
1answer
139 views

Statistical significance in Z boson excess paper

In a recent ATLAS paper, a excess of $3\sigma$ was reported from the Standard Model prediction in a search looking for a same-sign dilepton signal with an invariant mass around the Z peak. For brevity ...
21
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4answers
2k views

If the LHC-calculated mass of the Higgs is wrong, how long will it take to determine this with confidence? [closed]

After I watched "Particle Fever"--the movie about Large Hadron Collider (LHC) and the successful identification of the Higgs boson--I became a bit concerned with that team's handling of various ...
2
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0answers
61 views

Nature of particle spectra at ALICE

I have a question regarding the nature of the particle spectrum at ALICE as a function of momentum. The spectra in question can be seen here. My question is, why is it that the particle spectrum in ...
7
votes
3answers
261 views

Fiducial volume in collider/detector physics

I'm trying to make some sense of ATLAS measurements for a personal project to learn how to use Pythia, and part of my work requires me to recreate the distribution for Z boson decay. I encountered the ...
3
votes
3answers
364 views

What would happen to me if I was in the LHC while it was running? [duplicate]

This is possibly a stupid question, but one I have been always wondering. What would happen to me if I was in the center of the Large hadron Collider while it was running? Would the energy of the beam ...
6
votes
1answer
73 views

What is the temperature of an LHC Bunch?

From various places, I've found that an LHC bunch seems to be about 100mm long, 0.1mm wide, and contains about $10^{11}$ protons or anti-protons. The de Broglie wavelength is about $10^{-18}$ meters, ...
2
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1answer
36 views

Hard processes in particle collisions

This is in reference to a MC generator called Pythia, but has wider applicability because the phrases are used widely in particle phyiscs, even though I have not managed to find a clear, ...
6
votes
2answers
67 views

Why must energy be increased in a cyclotron to refine measured distance?

I have been listening to Nima Arkani-Hamed's messenger lectures at Cornell, and was confused by one point. He says that in order to measure at increasingly small distances energy must be increased (he ...
0
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1answer
67 views

How experimentalists put bounds on new physics at the LHC?

I would like to understand how experimentalists search for new physics at the LHC. Lets imagine I want to use the LHC data to put a bound on the coupling of some new physics effective operator, say, ...
-1
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1answer
98 views

How possible is it that the Large Hadron Collider (LHC) on its second try, could disrupt the gravity of Earth?

How possible is it that the Large Hadron Collider, on its second try, could disrupt the gravity of Earth?
7
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1answer
67 views

Why is the energy of particles in accelerators much higher than the energy of the particles they are trying to find?

I have been wondering. In the LHC, or other particle accelerators for that matter, they are colliding particles with energies above TeV. The LHC is going to be 14 TeV or something like that the next ...
2
votes
0answers
22 views

Where can we find LHC results talks online?

I'm looking to educate myself on some searches at the LHC, but I find it easier to understand what's going on if I watch a LHC results talk (e.g. by ATLAS, CMS, or an overall summary by a theorist) ...
0
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1answer
71 views

Hadron Supercollider - How does smashing protons reveal facts of the inception of our universe?

How does smashing protons at high velocity reveal how our universe was formed? At some point, wouldn't the atoms need to come together in order to form planets etc? I am a curious student- not a ...
6
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2answers
342 views

How detectors in particle colliders can differentiate neutrons from antineutrons?

Their mass is the same. None of them interacts with EM fields. And their decay (around 1000s) is far too slow to see their decay products yet in the detector. How is it then possible to differentiate ...
3
votes
2answers
216 views

Nuclear fusion using electromagnetic fields

I was just thinking about how deuterium and tritium are charged particles and so I couldn't help but wonder why we don't use the same process used in the LHC(electromagnetic fields to accelerate ...
2
votes
2answers
122 views

Where can I find the datasets from LHC?

I know that most of the datasets from ATLAS or other particle physics experiments are terabytes, but I was just curious is there any place where one can find them to download? And one more question, ...
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2answers
157 views

LHC data and mathematics of QFT

I'm reading Frederic's Paugam Towards the Mathematics of Quantum Field Theory, an advanced theoretical physics book. I would like to know how I could apply the theories in this book. For example, ...
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2answers
196 views

Can the Large Hadron Collider break the speed of light? [closed]

Can Large Hadron Collider experiments break the speed of light at some point in the future?
9
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3answers
291 views

What are the main algorithms the LHC particle detectors use to reconstruct decay pathways?

I am just starting to look into how we understand the data from particle collisions. My question is, what are the algorithms or ways that these detectors interpret the data? Are there standard ...
4
votes
1answer
85 views

Has the possibility of Higgs boson being a composite particle excluded already?

I heard some theory, such as technicolor, predicts the Higgs-like particle discovered at LHC should be a composite particle (correct me if I am wrong). Has this possible been completely excluded ...
0
votes
3answers
115 views

Why do physicists use LHC?

My question is why are we colliding particles in LHC to produce new ones? And these particles that they sometimes say live for a fraction of a second, how in space they exists then? In space all ...
1
vote
2answers
97 views

For what rare events was the LHC built?

I understand that for low cross-section events a very high luminosity is necessary in order to obtain enough data to produce meaningful statistics. That is why the LHC was built. But which are these ...
5
votes
0answers
928 views

Impostor Higgs?

I recently came across this article, published in the respectable European Physical Journal A. (Apparently, there isn't any corresponding arXiv article for this, so I'm sorry if everyone isn't able to ...
3
votes
1answer
92 views

Why can't we measure branching ratios of the Higgs at LHC?

There are theoretical predictions for SM Higgs decay branching ratios. What about the experimental results on BRs? All that I found was measurements of signal-strengths $\mu = \frac{(\sigma \cdot ...
2
votes
1answer
98 views

Different cross section for W and Z boson

At hadron colliders the cross section for W production is about ten times larger than the production cross section for Z bosons (e.g. Figure 2 in this review article). I guess the dominant ...
2
votes
1answer
131 views

What would happen if two entangled particles collided?

Does that is even possible? I have almost zero knowledge in quantum physics, it is just a curiosity that popped in my mind.
4
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0answers
177 views

Baryonic density in collision experiments

Does anyone know any way of estimating the net baryon density in collision experiments, e.g. in LHC, RHIC, or the upcoming ones at GSI-FAIR? I have comes across many hand-waving arguments, sample - ...
2
votes
1answer
55 views

Easy formula for ultrarelativistic bremsstrahlung?

I am very curious if an easy calculable formula for the bremstrahlung radiation of deeply relativistic, charged particles exists, if they are moving on circular orbit: $P(E,m_0,Q,r)=?$ ...where ...
2
votes
2answers
75 views

What were the maximal collision energy of the LHC if it were rewired to $e^{-}-e^{+}$ collisions?

Yes, I know, that it weren't a large hadron collider then. No, I don't think, that the creators of the LHC didn't know what they do. I am just curious. How could it be calculated? A such rewiring ...
4
votes
0answers
179 views

Jet rapidity vs. Pseudorapidity

thanks to this post Why is pseudorapidity defined as $-\log \tan \theta/2$ I got a better understanding of what makes (pseudo) rapidity an interesting an often-used concept. Tangentially working ...
0
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1answer
94 views

Reusing the bremsstrahlung energy in circular accelerators?

I think the Bremsstrahlung happens as a strong radiation emitted by the accelerated particle stream. As in this question is visible, it is the main cause of the energy loss in such big particle ...
17
votes
4answers
2k views

Why doesn't the LHC accelerate electrons?

Electrons have a much bigger charge density as the protons (and especially lead nuclei), aren't compound particles as the protons (and especially lead nuclei) are able to get a much bigger energy ...
3
votes
1answer
87 views

W + jets at NLO

I would like to calculate $pp \rightarrow W (\rightarrow \ell \nu)$ + n-jets (n=2, maybe also 3) at NLO, with some cuts and plot some distributions. I used MadGraph extensively for LO processes and I ...
6
votes
2answers
212 views

Could a tetraquark $q \bar{q} q \bar{q}$ be colorless?

CERN just posted this article where it informs that it was found an hadron which cannot be classified within the traditional quark model. What other models are there to explain this result? Or is it ...
2
votes
0answers
160 views

How far could the LHC “fire” a particle

Very simple question, and frankly quite a silly one, but I'm currently writing a lecture for secondary school kids and I'd love to tell them how far the Large Hadron Collider could fire a proton. The ...
6
votes
3answers
212 views

Are there any Meson colliders?

There are no stable mesons as far as I know. Are there any meson-colliders analogous to for example proton-proton colliders? Edit: This edit was made more than a year after the original question was ...
0
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0answers
39 views

References on the LHC experiments

I'm looking for a references / short book which discusses what is going on LHC collider - specific experiments, collision processes, analysis of data, how exactly the facility is operating (not ...
4
votes
1answer
161 views

Why 1 Month LHC Magnet Cooling Times

An often quoted figure is that the LHC magnets take a month to completely cool and a month to warm. There is never an explanation as to why that is. I can conjure any number of reasons (slow changes ...
1
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1answer
261 views

LHC Experiments for finding parallel universes?

I watched this video featuring Michio Kaku explaining parallel universes. In the last two minutes he said that experiments in the LHC could reveal that there might be parallel universes and then he ...
2
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0answers
81 views

How do they draw collision pictures in Atlas?

Is the picture below a simulation? How to they draw these pictures? The picture is from here.