8

The Higgs-discovery experiment is a particle-counting experiment. Lots of particles are produced by collisions in the accelerator, and appear in its various detectors. Information about those particles is stored for later: when they appeared, the direction they were traveling, their kinetic energy, their charge, what other particles appeared elsewhere in the ...


7

I think this question may arise from a difference between somewhat rough layman's-terms presentations and the more careful statistics which goes on in the actual labs. But even after a given body of data has been analyzed to death, there is no formal way to capture in full the evidence underlying the way knowledge of physics grows. The evidence surrounding ...


5

Here I summarize the most important results: Gravitational waves are predicted by Einstein's theory of general relativity. According to general relativity, they are disturbances in the curvature of spacetime (so they are not a form of electromagnetic radiation). LIGO and Virgo observations have experimentally confirmed the existence of gravitational waves....


5

The null hypothesis here is that the data was generated by physics which obeys the effective field theory describing all the Standard Model particles except the Higgs. This model doesn't usually have a name, but could reasonably be called the 'Standard Model without Higgs'. It's a perfectly good effective field theory. It's predictions are barely ...


3

There would be no dent. The orbiting body would in fact draw the event horizon out towards itself in a bulge - otherwise it would never be able to reach the event horizon and fall in. But what if your camera was loosed into that passing bulge? As the bulge moves on, could it leave the camera high and dry? Sadly, no, as the event horizon subsided back again ...


3

Refresher on hypothesis testing In (frequentist) hypothesis testing one always have (at least) two hypotheses: the null hypothesis, and the alternative hypothesis. Then p-value is the probability of observing certain dataset, given that the null hypothesis is true, whereas the power of the test is the probability that the alternative hypothesis is true, ...


2

Lets consider the result of combining two Gaussian distributions of the measuring period $T$ (assumed the exact value $T_o$) with deviation $\sigma_1$ and $\sigma_2$: \begin{align} P_1(T) =& N_1 \exp\left(-\frac{(T-T_o)^2}{2\sigma_1^2}\right); \tag{1}\\ P_2(T) =& N_2 \exp\left(-\frac{(T-T_o)^2}{2\sigma_2^2}\right). \tag{2} \end{align} Where the $N_1$ ...


2

There are several errors in your analysis: The equivalent circuit of a voltmeter is not the one you represented: a real voltmeter should be represented as an ideal voltmeter, with infinite input resistance, in parallel with the voltmeter's input resistance ($R_2$ in your case), not in series. The correct value of $V_{C_\mathrm{max}}$ is $$V_{C_\mathrm{max}}...


2

With higher statistics, XENONnT and LZ will be able to recognize a potential tritium contamination by its energy spectrum and discriminate it from other explanations. For fairness, one should stress that this excess showed up in their background that is of little concern to their main science target, which are nuclear recoils from dark matter (or neutrinos). ...


2

In light of this new article: The mirrors themselves are near room temperature. The bulk translational motion of the object is "cooled" to far below what it would normally have if resting quiescently in thermal equilibrium. But how? The mirrors are in high vacuum and absorb very little light. They aren't metal, they are dielectric mirrors ...


2

First of all, it depends on the size and shape of the plate. As a rule of thumb, the wave length cannot be longer than two times the extent of the object, which gives us the rough estmate of frequency as $$f=\frac{v_{sound}}{\lambda}$$ A more precise answer requires finding the eigenmodes of the plate (i.e., solving the sound wave equation with the boundary ...


2

If you really want to maximise the volume, explain this to the other residents. Ask them join the test - to listen and to tell you if they can hear it. But remember, what might seem quiet to them in the daytime might seem loud if they are trying to sleep. So if they agree something, go for quieter than they agreed. Then you can enjoy the party with a ...


2

The sphericity axis is the direction about which the total squared transverse momentum of all the observed particles is minimum. This is easy to determine: you take the 3 by 3 matrix of the sum of the cartesian products of the particle momenta with themselves and diagonalise it. It's the analogy of the inertia tensor. Spherocity is slightly different: it ...


1

I would do the following Once I collect all the measures for $T, \bar{T}$ and $\sigma$, I would check what the value of $3\sigma$ is, since this way you would have a chance of 99.73% that all the possible error values is likely to be contained in that range. If you use only one sigma, you would be accounting only 68.27%. Note that in CERN and other big ...


1

Engineer's view, proceed with caution! When reporting uncertainty, you want to report every contribution together into a single value; but sometimes there is a need to distinguish between instrument limitations and uncertainty measured from repeated measurements. If you were an ideal measurer, you could simply say $1.3 \pm 0.05 \text{ s}$ where the stopwatch ...


1

Not at all in classical physics, assuming the wire is made of a simple conducting medium. Very little if correction to solid state physics is taken into account: The charge density within a (nanometers) thin layer near the conductor surface will change due to bound charges. They can influence conductivity especially for high-frequency currents. Still the ...


1

Two things you might want to do: your data aren't perfect, in particular, there are two vertical jumps in them, one at approx -2.6 and another at approx 1.5 (not sure if this is what you refer to as "dead time"). These vertical jumps are in fact phase jumps of your oscillations. You won't be able to fit the entire data set with a $\cos^2$ function ...


1

To estimate the fake objects in your signal region, a control region is used. This control region (CR) should be highly dominated by these fakes but otherwise similar to the signal region (SR). Typically you invert the lepton identification criterium. While in the SR you use leptons fulfiling the "Tight" identification working point (WP), in the ...


1

The very goal of particle physics experiments all through the past century is to extend the model describing the particle interactions, at present called the standard model. . As energy gets higher and accuracy of measurement lower over the years the model has been modified in order to fit the data and be predictive. Experiments are continually looking for ...


1

Your second equation has a wrong sign. The general formula is \begin{align} \sum_i P_i = \left( \sum_i c_i m_i + C \right) \frac{dT}{dt}. \end{align} Your expression has a minus sign for $P_{loss}$ that shouldn't be there. After this is changed, you should get a positive value for $P_{loss}$.


1

Yes, that is correct. But note however that most common materials yield and fail at stress levels far, far below that represented by the strength of the binding forces between their constituent atoms. This is because of defects in their crystalline structure which allow the material to bend and distort i.e., they contain deformation mechanisms that reduce ...


1

The physical background here is not that one type of wave has the same speed as the other by some sort of coincidence, but rather that both have the speed limit associated with spacetime itself. The speeds of either wave are of course predicted by the equations that describe the different physical phenomena (Maxwell equations and Einstein equation(s)), but ...


1

There are lots of unexplained >5-sigma results out there, and the only way establish that one of them was a statistical glitch would be to prove that it had no systematic errors. This is impossible. There is a well-known aphorism that "all models are wrong", and all real measurements have inherent systematic errors. We can work hard to keep ...


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