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From the machine side, a symmetric $p\bar{p}$ collider can have only one beampipe, so it is much simpler. On the other hand if you fill it with many bunches they will start to collide all around the machine. You may manage to separate their orbits, but they will still feel the fields reciprocally generated (long-range beam-beam interaction) that will limit ...

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The experiments, both CMS and ATLAS report 2.5 and 3 sigma candidates, but not at the same spot/channel. The place to look is at Cern's document server , asking for "supersymmetric" for example in conjunction with CMS or Atlas. This general talk is about limits . Lubos Motl in his blog discusses an Atlas 3 sigma possible excess and there are links there. ...

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First of all, the uncertainty principle and observer effects are completely irrelevant. The tracking devices in modern detectors are large enough to be firmly in the realm of classical physics. Any uncertainty in the detector's wavefunction is negligible compared to the size and energy of the device itself, and the effect of detected particles on the tracker ...

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OK, I have found additional material on the CERN site which further describes the tracker detector and the silicon pixels and silcon strips within the detectors. Fascinating stuff. The first article says that each measurement of the detector is accurate to 10 micrometers. Seems like great accuracy, esp. for their purposes. However, I calculate about ...

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Elastic collisions do happen at the LHC. The TOTEM experiment measures the differential cross section (rate as a function of angle) for proton-proton elastic scattering at the LHC. Here is their latest result. They don't publish an estimate of the elastic cross section, but according to their data it must be at least 25 mb (millibarns) (my first version of ...

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Anything that is not forbidden must happen. That's an important statement to keep in mind when approaching quantum physics. It doesn't mean that anything that can happen always happens, but it must happen at some time or another just like someone eventually has to win the lottery. That said, some protons do go through the LHC, ram into each other and ...

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elementary particles (e.g. protons) Protons aren't elementary particles, they're made of partons (quarks and gluons) in "soup". Below, $\lambda$ is the wavelength corresponding to the energy of the interaction via the usual de Broglie relation and $r_p$ is the radius of the proton. At low energy with $\lambda >> r_p$ the interactions are just ...

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