Questions tagged [large-hadron-collider]

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 with a centre of mass energy of up to 14 TeV. It contains the important detectors ALICE, ATLAS, CMS and LHCb.

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Why do protons need to moving at high speed to collide?

I want to know Why protons need to moving at high speed to collide? I know that both protons are positively charged so the electrostatic repulsive force would tend to make them miss each other at ...
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LHC on train tracks? [duplicate]

If the LHC can accelerate a proton to within 3 to 4 m/s of the speed of light, as a point of curiosity, what would happen if the entire LHC loop itself were constructed on train tracks, such that the ...
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Where can I find inclusive $p^+p^+ \to W^+W^-+X^{++}$ cross-section prediction at $14 TeV$ (NNLO)?

The title self explains.. I desperately need the theoretical NNLO (also NLO can work) prediction for inclusive diboson production (WW), a link to a paper would make my week!
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Effect of difference in no. of MC events and no. of LHC events expected in dataset on background estimation

Is there any effect on the background estimation of the fact that the no. of simulated monte carlo events used in LHC analysis may differ from the no. of events expected in the LHC dataset?
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Observables and different collider machines

Recently I heard that there is no point in going for the observable $\frac{d\sigma}{dq^2_T}$ in a $e^+ e^-$ collider (e.g. in the process $e^+ e^- \rightarrow Z$, measuring the transverse momenta $q_T$...
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Does deep inelastic scattering produce photon?

I know that DIS produces hadron jets, which are formed from the intense energy of the interaction. But I wonder, are photons also produced? And if so, what are the processes that create these photons?
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Hadronic decay experimental result

I am looking for experimental results of hadronic decays cross section of the two following decays: $\Delta^{+} \rightarrow p +\pi^0 $ and $\Sigma^{*0}\rightarrow p + K^{-}$ I have already computed ...
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What are the advantages of an electron-electron collider vs. An elec./positron one? Has one ever been built?

The current LHC is a proton-proton collider (instead of proton-antiproton) for reasons I have read about elsewhere. Why has there never been an electron-electron collider? Also, I am reading now ...
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Layman's questions about Supersymmetry

Please help me with two very silly questions. Assuming supersymmetry is correct, why don't we observe the superpartners of the Standard Model particles at ordinary energies? Why do we have to search ...
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If a particle and its antiparticle annihilate upon contact, how do they form bound states?

I am reading about some old discoveries in particle physics and early collider experiments from Perkin's Introduction to High Energy Physics. However, I didn't get the answers to all my questions. If ...
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How LHC sensors work? [closed]

newbie here. I am here because after working with Raspberry Pi sensors and Analog to Digital converters, and computer processors, I wondered how exactly do sensors in large scale physics experiments ...
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2019 Higgs Boson Mass?

Wiki, based on the 2018 Particle Data Group, gives the Higgs boson mass as $125.18 \pm 0.16$ GeV$/c^2$. OK. However, 2017 ATLAS gives a combined value of $124.98 \pm 0.28$ GeV$/c^2$. So what is ...
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What is the point of particle accelerators with lower energies than the LHC?

Brazil's scientists are building a synchrotron, named Sirius. I'm wondering what the point of building this synchrotron is. From Sirius's Wikipedia page, it reaches an electron energy of 3 GeV. This ...
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How to know what production channel Higgs came from?

There are four main production channels for SM Higgs: ggF, VBF, Higgstrahlung and associated top. In multiple occasion I've seen experimental bounds referring to say $\sigma(gg \to H \to \tau^+\tau^-)...
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Why there is accelerator chain at LHC?

Why can the LHC not accelerate protons to several TeV in one go? What is the limitation? My Answer: First reason is to minimize the cost of LHC accelerator construction by utilizing the previous ...
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Total cross section in hadron colliders with optical theorem?

In hadron colliders (like LHC) the total cross-section is calculated using the optical theorem. The origin of this is the scattering of two particles which is solved with the Schrödinger equation ...
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Hadronization in a collider

Say, in a collision, do the quarks need to first hadronize to pions? Or is there a probability that they can hadronize directly to heavier particles like the charm quarks.(quark-anti-quark pair) The ...
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Why is particle physics called high energy physics? [duplicate]

The highest energy accelerator till date is the LHC which operates at an energy scale of perhaps 10-100 TeV. In SI units this is about $\sim 10^{-6}-10^{-5}$ Joule which is several orders of magnitude ...
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No supersymmetric particles have been found in the LHC. Isn't this proof that Supersymmetry doesn't exist? [duplicate]

The LHC can reach energies from $7(TeV)$ to $13(TeV)$ (see here) and the question of which this is supposed a duplicate. Which I think it isn't, because in that question (which has been asked already ...
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What is the definition of beam energy in particle physics?

For example, the proton beams in the LHC collider have 7 TeV energy. Does this mean that the individual protons in the beam have 7 TeV energy or that the energy of all the protons in the beam add up ...
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What happens with the energy released after a particles collision?

From the website of CERN: "Collisions in the LHC generate temperatures more than 100,000 times hotter than the centre of the Sun.". My question is, what happens to the energy released after the ...
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Cherenkov light and refractive index

LHCb’s Ring Imaging CHerenkov detector (RICH) is aimed at telling different charged particles apart by measuring their velocity, which, together with an independent measurement of their momentum, is ...
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Energy of the particles in the particle accelerator

Recently I came across something and I was surprised. I always thought that huge amount of energy is required to accelerate particles in the accelerator in the particle physics.But looks like no. The ...
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How do we know the LHC results are robust?

Nature article on reproducibility in science. According to that article, a (surprisingly) large number of experiments aren't reproducible, or at least there have been failed attempted reproductions. ...
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Antiproton production threshold

Why is the antiproton threshold on cern 6* m_p and on uspas it is 7 * m_p?
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What superstring or brane phenomenology can be observed in LHC heavy ion collisions?

What superstring or brane phenomenology can be observed in heavy ion collisions at the LHC energy densities. Of course, I am aware that LHC experiments can constrain the conclusions from the ...
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Big Data Handling at the LHC

My understanding is that much of the data that is is collected at the Large Hadron Collider is similar to that in the image below, and that a vast amount of the data contains little of specific and ...
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Can modern/future particle accelerators create a blackhole that “eats” the planet?

I dont think so myself, but this article: Earth could be crushed to the size of a soccer field... on Science Alert is being picked up by media. It seems to be a regurgitation of this article from UK's ...
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Don't matter-antimatter annihilate each other completely releasing energy as photon?

Matter and antimatter should annihilate each other completely releasing energy in the form of photon, however it is discovered that smashing electron and positron together can also spew out higgs ...
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Could we use experimental evidence of micro black holes to prove the existence of additional spatial dimensions?

They are planning to create a new particle accelerator that can smash particles together at a much higher energy than the LHC. If in the process we observe the decay of a micro black hole, would that ...
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Does superconducting magnet prevents energy loss when hadron is being accelerated?

I read up on how synchrotron works and electron will heats up by emitting photon when it is steering(accelerating) around a bend, so more bends more heat loss. By heat I mean energy not necessarily ...
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What are “large hadrons”? Are there also “small hadrons”?

The BBC News article Cern plans even larger hadron collider for physics search says: The difficulty with Cern's proposals for a larger Large Hadron Collider is that no one knows what energies will ...
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How to analyse the LHC signal for Higgs?

With increasing energy the collision decreases in the plot for signal in LHC. why is that? and at an energy 125GeV the no of events suddenly increases. How this proves that higgs has a mass of 125GeV?
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What would happen if antiprotons were studied under the conditions of particle deceleration that they are collected under? [closed]

I have not had a very clear understanding of how antiprotons are collected, but I do know that when they collide with matter they explode in a puff of energy. Or so I have been told. If the current ...
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Is anything expected to be found at CERN with 14 trillion electron volts that wasn't found at 13?

Based on this article the accelerator has smashed together approximately 16 million billion protons since 2015, when it reached its current energy of 13 trillion electron volts. Planned ...
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Is it possible to replicate condition at planck time after big bang by smashing 2 protons really hard?

Because we need to achieve really really high temperature to mimick the condition just planck time after big bang, so suppose we can accelerate 2 protons at extremely close to speed of light and let ...
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How can a single particle hit many pixels in Large Hadron Collider?

In the Large Hadron Collider, the way particles are detected (specifically in ATLAS) is analogous to detecting photons using a photodiode(analogous is an exaggeration, but will suffice for the ...
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How is antimatter stored in the large hadron collider?

we studied that antimatter can be stored in the large hadron collider. what i dont get is that the collider is used to collide particles and antiparticles together right? so how is antimatter stored ...
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Collider Luminosity basics

In a collider experiment, the Luminosity is defined as the proportionality factor between the interaction rate and the interaction cross section $dN/dt = L\times\sigma$, with units of $cm^{-2}s^{-1}$. ...
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Light neutrino number from the invisible decay width of $Z$ boson, and precluding heavy neutrinos as dark matter candidate

The $Z$ boson decays into pairs of quarks and leptons. While the decays to quarks pairs and charged lepton pairs can be observed, the decays to $\nu\bar\nu$ are cannot be. By subtracting the visible ...
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Invisible energy in a particle collision

I read a lot about the so-called "missing" energy in hadronic collisions. I always thought that it was mainly due to neutrinos and also nuclear deformations, but today I read that "on average, 30% of ...
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The Large Hadron Collider and Black Holes

Last week, I went to Switzerland and visited the LHC. I took a tour, and the guide told us that it is possible for black holes to appear in the LHC, but they will be so small, that they would ...
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Mass vs cross-section studies

Let's assume we have a event generator like "Pythia", and from that I have collected four momentum of a certain lepton production. the leptons are from excited gamma state. And the excited ...
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Can a rebranded super-symmetry be consistent with the null results at the LHC

To explain the null results on SUSY at the LHC, it continues to be assumed that the achievement of the energy threshold for the creation of the SUSY partners is beyond the capability of the ...
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How are particles in a collision chosen?

In synchrotron particle colliders, how are the particles which are collided chosen? For the most part, collisions of different types of particles don't do anything like you might expect in a video ...
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high $p_T$ and low $p_T$ b-jet energy correction factor

For b-jets, to get the true transverse momentum using the reconstructed $p_T$, we use a correction factor $p_{T}^{gen}/p_{T}^{reco}$ obtained using MC. Now suppose I make a plot of $p_{T}^{gen}/p_{T}^{...
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Does the vertex efficiency include track reconstruction efficiency?

Consider a document of ATLAS collaboration on displaced vertex level efficiency. On the first two pages there is a description of cut-offs required to background free displaced vertex reconstruction. ...
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Why are the elastic and total cross-section of $pp$ collisions increasing as the C.O.M. energy grows?

Well, that's about it. I don't find any reasonable explanation for this fact. Are they transversally expanding as the energy increases? Please, remember that strong interactions are short ranged and ...
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Pile-up in particle physics

Regarding pile-up, I came across two definitions. One dealing with electronics of detector where more than one event get recorded at the same time and other regarding all the pp collisions in the ...
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If the LHC test energy levels present just after the Big Bang, is it possible to test higher energies? [closed]

And, if so, would that be relevant to anything in this universe?

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