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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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 ...
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179 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 ...
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1answer
54 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 ...
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1answer
54 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 ...
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0answers
115 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 - ...
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1answer
82 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.
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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 ...
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1answer
34 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 ...
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2answers
61 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 ...
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38 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 ...
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1answer
54 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 ...
3
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1answer
70 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 ...
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2answers
173 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 ...
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0answers
21 views

The Magnetic Field around the Proton Beams in the LHC

How would one most appropriately model the magnetic field around each bunch of protons in the LHC at maximum operating speed? Is the assumption of a wire of the same length of the beams (~30cm) with ...
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6answers
2k views

What would happen if Large Hadron Collider would collide electrons?

After some reading about the Large Hadron Collider and it's very impressive instruments to detect and investigate the collision results, there is a remaining question. What would happen if the ...
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0answers
134 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 ...
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3answers
158 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?
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2answers
622 views

Can black holes be created on a miniature scale?

A black hole is so powerful to suck everything into itself. So is it possible that mini black holes can be created? If not then we could have actively disproved the rumors spread during LHC ...
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1answer
135 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 ...
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0answers
34 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 ...
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1answer
116 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 ...
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3answers
390 views

How do they handle energy in magnets at LHC?

I'm guessing that when the LHC ramps up to 4000 GeV this means they are increasing the current in the superconducting magnets as RF fields accelerate the beams. Where does this current go when they ...
2
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0answers
63 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.
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3answers
16k views

What is the current status of string theory (2013)?

I've seen a bunch of articles talking about how new findings from the LHC seem to disprove (super)string theory and/or supersymmetry, or at least force physicists to reformulate them and change ...
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2answers
99 views

Deciding what to collide at particle accelerator

Different particle accelerators use different types of collisions. For instance at the LHC they investigated p Pb collisions while its predecessor (LEP), used to collide electrons with proton and at ...
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4answers
276 views

how long do large hadron collider experiments take?

This travel stackexchange answer has kinda got me wondering... how long do experiments involving the large hadron collider usually take? I'd expect you run it for a few seconds and bam - higgs boson ...
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2answers
436 views

Particle Accelerator Energy and Luminosity

Both beam energy and luminosity are important for succesful particle accelerator experiments. The LHC's nominal design is for 7 TeV beams and 1E34 cm^-2 sec^-1 luminosity, while the SSC's nominal ...
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0answers
28 views

what does “medium-induced gluon radiation” mean

I've often run across phrases such as "medium-induced gluon radiation" from some papers,what is "medium-induced gluon radiation"?
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3answers
363 views

The LHC - Proton Speed Limit [duplicate]

I'm originally from stack overflow, so this is my first foray into this particular community. I've read in numerous places that the Large Hadron Collider is capable of accelerating protons at ...
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3answers
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Can the technology behind Particle accelerators can be used for space propulsion?

As I understand, the kinetic energy of the proton beam in a hadron collider is quite large. Can you build a space propulsion system that is based on accelerating a proton bean to relativistic speeds ...
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4answers
5k views

What if the LHC doesn't see SUSY?

A question in four parts. What are the main problems which supersymmetry purports to solve? What would constitute lack of evidence for SUSY at the proposed LHC energy scales (e.g. certain predicted ...
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0answers
34 views

Why don't photons crash into each other occasionally? Or do they? [duplicate]

At the LHC, researchers smash particles into each other at speeds close to speed of light. Photons, on the other hand, already move at the speed of light. Do they ever smash into each other? Or do ...
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1answer
109 views
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176 views

Achieving almost the speed of light

I am much interested in physics. I have been caught up with one serious question related to speed of light. Hearing about Large Hadron Collider (LHC), it is said that protons in there are accelerated ...
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3answers
68 views

Predicting the mass of the Higgs particle

Physicists in Europe said that only after combining data collected at a laboratory in Switzerland with data collected at a laboratory in the U.S, were they finally able to announce the discovery of a ...
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2answers
238 views

Why is the Higgs boson created so infrequently at the CERN collider?

Although each collision at CERN has the available energy to create a Higgs boson each time, the vast majority of the time it does not create one. I suspect that part of the reason for this is that ...
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Hawking's alternative to Higgs Boson

I have seen in popular media, claims that Hawking does not believe the Higgs boson exists due to microscopic black holes and even made a bet against it. This is based on something published in ...
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1answer
300 views

The future of supersymmetry [duplicate]

Considering the fault of any experimental evidence from LHC for supporting the supersymmetry idea until now, can we say that it is dead? Generally the people who are working on this subject say that ...
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1answer
231 views

Which SUSY models are affected by the recent LHCb result?

The LHCb has recently published the observation of $B_s \rightarrow \mu^+ \mu^-$ with a branching ratio that agrees with the Standard Model (SM). There are many blog posts about it (See: Of Particular ...
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3answers
253 views

LHC vacuum tube diameter [closed]

What's the diameter of the tube where the protons fly around? I dont mean the overall diameter (~1-10 m), instead the inner most ultra-high vacuum tube where the protons are. The inner pipe, the ...
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2answers
193 views

If you could look at the LHC beam, what would you see?

Kind of a weird question compared to what I normally ask on here, but I've been wondering about this for a while. Does the LHC beam generate any photons within the visible light spectrum? Assuming ...
0
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1answer
93 views

how do they rip one single atom from something?

this is simple. what i actually want to ask is, when they do the subatomic particle collision experiments, how do they produce one single subatomic particle, e.g proton, neutron? how do they rip one ...
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2answers
404 views

What does the LHC do afterwards?

Astronomical telescopes are now mega projects and cost $1Bn and although they are pitched to solve the current interest of the day they are general purpose machines and with upgrades and new ...
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4answers
316 views

SUSY and the Large hadron collider

Did the LHC rule out SUSY as a solution to the hierarchy problem ? What's the common belief among theorists regarding the possibility of discovering SUSY in the 2015 run of the LHC ? Did the absence ...
3
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2answers
517 views

Missing transverse energy, exact definition

This might seem basic, but it is a bit confusing. You hear about missing transverse energy a lot in SUSY searches due to the LSP which cannot be detected. Let's say I have the 4-vector for the LSP. ...
26
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5answers
2k views

Is a proton collision (collisions like in the LHC) visible to the human eye?

I was curious if a proton collision is visible to the human eye. (This might sound like a really basic question and forgive me if it is. I am very inexperienced in Physics and just wanted an answer ...
2
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2answers
404 views

If LHC is the most powerful microscope in the world, what does it magnify?

Some experts (and non experts) have called LHC the most powerful microscope in the world. I am wondering, what does the LHC magnify? Or is calling it a microscope just wrong and misleading?
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2answers
134 views

How does the Cern LHC collide particles head on if uncertainty principle limits the precision

I have been wondering why doesn't the uncertainty principle prevent the LHC experiment as if one want to collide two particles together one must accelerate a particle to certain speed and aim it at ...
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0answers
42 views

Can TOTEM's T2 detector measure differential cross sections?

My current research involves making a prediction for data collected by the TOTEM experiment at the LHC. The experiment is primarily designed to measure the total inelastic and elastic scattering cross ...