Tagged Questions
1
vote
1answer
40 views
Interpreting the results
I have preformed the muon lifetime experiment at my uni's lab, and got the data. It's text file with 8190 numbers. My TDC unit was set so that the time gates were at 10 $\mu s$, and it has 8192 ...
3
votes
0answers
49 views
List of cross sections?
Sometimes I need to look up a certain cross section, say the inclusive Z production cross section at $\sqrt{s}$ = 7 TeV. Is there a place where 'all the' cross sections are tabulated ...
-1
votes
0answers
48 views
What is the difference between various fields of physics? [closed]
what is the difference between the fields of physics? like high energy physics, particle physics, cosmology, quantum physics, quantum mechanics, experimental physics, theoretical physics, applied ...
6
votes
0answers
84 views
Status of experimental searches for tachyons?
Now that the dust has settled on the 2011 superluminal neutrino debacle at OPERA, I'm interested in understanding the current status of experimental searches for neutrinos. Although the OPERA claim ...
1
vote
1answer
96 views
What is Transverse Energy?
What is transverse energy? Why we use transverse total energy instead of energy and transverse momentum in place of Total momentum in the particle detectors?
0
votes
1answer
116 views
Exploiting the Heisenberg Uncertainty Principle as a means to communicate
It seems as though I've come across a rather unusual conclusion that could either simply be a misinterpretation or a contradictory discovery. I seem to have found a way to utilize the Heisenberg ...
1
vote
1answer
118 views
Dalitz plot analysis
I have seen a few Dalitz plots so far and tried to understand how they are useful.
So one of the advantages of these plot is that the non-uniformity in the plots can tell something about the ...
9
votes
1answer
222 views
What dark matter can AMS currently find (or exclude)?
The rumor mill is running again, this time it's about the AMS experiment (Alpha Magnetic Spectrometer) that's going to make a major announcement soon.
I suppose they are looking for peaks in gamma ...
3
votes
0answers
70 views
What is the importance of the Higgs-strahlung process in the Higgs search?
I would particularly like to know why this process is considered the main search mode for Tevatron but useless for search at LHC.
3
votes
1answer
50 views
Single electron non-perturbing detector
I am designing an experiment where I need to trigger the release of an electron by a radioactive source (Sr-90).
The easy way to do it is to use a thin scintillator right after the source collimator. ...
1
vote
1answer
93 views
What are “hidden valley sectors”?
In this end of the year article, Prof. Strassler mentioned that hidden valley sectors could lead to some still open loopholes concerning the experimental discovery of supersymmetry and other BSM ...
2
votes
2answers
157 views
Identification of extended quantum objects?
In some physics theories like string theory we have notion of spatially extended quantum objects - strings, membranes etc. Assuming that such objects exist, how would they appear in experiments ? More ...
4
votes
2answers
406 views
How was the Oh-My-God particle observed?
How exactly was the Oh-My-God particle (ultra-high energy cosmic ray) observed and its energy measured?
4
votes
2answers
256 views
Basic question on experimental plots
On the following Higgs $\rightarrow$ Tau Tau plot, since we are plotting the ratio of $\frac{\sigma}{\sigma_{SM}}$ on the y axis, shouldn't the expected for this be 1? i.e., shouldn't the expected 68% ...
6
votes
1answer
183 views
Weinberg angle measurement methods
I was reading up on the history of $W/Z$ bosons today and I got a little puzzled. I always assumed that people measured $M_Z$ and $M_W$ and then derived the Weinberg angle. But it appears that they ...
2
votes
2answers
114 views
Compactness of spacetime: experiment and math
It is common to find models built on a compact spacetime. In mathematics, compactness is a very nice property $-$ and lot of powerful results depend on it.
But
how safe is assuming compactness of ...
1
vote
1answer
184 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. ...
1
vote
3answers
94 views
New physics at high energies, cosmic rays, particle-detectors in space
New physics is expected at high energies and cosmic rays have high energies, so have there been or are there any plans to put particle detectors in space to study cosmic rays for new physics ?
2
votes
1answer
229 views
What is a Pseudoscalar particle?
Can someone explain to me what is a pseudoscalar particle?
And how do experiments figure out that what they're dealing with is a scalar or pseudoscalar?
4
votes
0answers
150 views
Parity and Helicity of the Higgs Boson
I have been studying how the spin and parity of the new boson discovered at the LHC will be studied and have run into some confusion. The Standard Model Higgs is expected to be a scalar (i.e. have ...
4
votes
2answers
235 views
Vector Boson Fusion
I have been reading about the production mechanisms for the Higgs at the LHC. It is always mentioned that for Vector Boson Fusion, the initial quarks cause jets that are back to back and with a higher ...
3
votes
2answers
157 views
Experimental observation of elementary particles?
I posted a similar yet totally unrelated question recently, and got really satisfying responses to it. Thus, on the same theme...
How have we come to realize the existence of elementary particles in ...
6
votes
3answers
414 views
How are the masses of unstable elementary particles measured?
I am interested in knowing how (Q1) the particle's masses are experimentally determined from accelerator observations.
What kind of particles? They must be as far as we know elementary and unstable ...
6
votes
2answers
287 views
Use of Monte-Carlo simulation in High-energy Physics
I've been doing some research into the analysis used in particle physics when determining the significance of a finding (e.g. the recent Higgs candidate was announced as a boson in the 125-126 ...
2
votes
1answer
67 views
random triggers
I understand that a small proportion of events at the LHC that would not trigger on any deterministic trigger are saved on what might be called a random trigger, so that, amongst other uses, proposed ...
2
votes
0answers
58 views
Remaining Potential Experimental Particle Physics Discoveries at the TeV Scale?
With the discovery of the Higgs Boson, some have been calling it the end of experimental particle physics for our generation, due to the fact that all of the particles predicted by the standard model ...
1
vote
1answer
170 views
Why not accurate masses of elementary particles?
In the standard model of particle accuracy in calculating mass is very low.
And you can not predict the upper limit of Higgs particle mass accurately. Why not accurate masses of elementary particles?
3
votes
4answers
812 views
What is meant by “Nothing” in Physics/Quantum Mechanics(QM)?
I am not a phycisist, so please forgive my ignorance. This is related to my posts and this.
I am trying to undertand what is meant by the term "Nothing" in physics or Quantum Mechanics since it seems ...
1
vote
1answer
2k views
Negative and positive energy and Hawking [closed]
I don't have any physics background (except the material we did in high school-long time ago).
I was watching a documentary with Stephen Hawking about whether God created the Universe and I could not ...
2
votes
1answer
219 views
Has the Higgs really been discovered at CERN?
Many news media round the world such as this http://www.scientificamerican.com/article.cfm?id=higgs-lhc have reported the possible discovery of the Higgs at CERN, to be announced at a conference on ...
2
votes
0answers
58 views
How can one activate the decay of the quark b with PYTHIA event generator?
This is my problem and I hope finding a solution.
_In the simplest alternative, MSTJ(22) = 2, the comparison is based on the average lifetime, or rather (c*tau "time life") , measured in mm. Thus ...
2
votes
2answers
138 views
How the nucleon structure has been identified experimentally?
It is known that nucleons (proton, neutron) are composed of partons (quarks, etc.). How was this identified experimentally? In particular, how it has been identified that nucleons comprise of more ...
1
vote
1answer
264 views
Enlightening experimental physics books/resources
Most book recommendations I've seen are usually geared toward theoretical understanding. It would be nice to know at least one or two classic experimental physics books.
e.g. from Carl Brannen's ...
1
vote
3answers
272 views
What is the reason behind specific values for charge of electrons, protons?
Why do things like protons and neutrons have specific values. Also speed of light is a speed in which even if you go towards it, the speed does not vary. But why does light have to travel at speed?
26
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0answers
504 views
What is the upper-limit on intrinsic heating due to dark matter?
Cold dark matter is thought to fill our galactic neighborhood with a density $\rho$ of about 0.3 GeV/cm${}^3$ and with a velocity $v$ of roughly 200 to 300 km/s. (The velocity dispersion is much ...
8
votes
1answer
332 views
Could LEP II have discovered a 125GeV Higgs?
LEP II eliminated the Higgs up to 114.5GeV. If it had been run for longer could it have detected a Higgs at 125GeV?
I Googled for this without any luck, though I did find a comment that LEP II topped ...
0
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0answers
38 views
Why has the ether been disregarded as a valid medium through which light can propagate? [duplicate]
Possible Duplicate:
Ether theory acceptance
Although the Einstein's theory of relativity seemed to make the concept of an ether obsolete, did it necessarily invalidate it? Are there any ...
1
vote
2answers
181 views
Where to find cross section data for e- + p -> p + e-?
Where to find cross section data for e- + p -> p + e-?
PDG's cross section data listing does not include it.
3
votes
1answer
581 views
How can Kaluza-Klein particles be told apart from winding modes at the LHC?
I`ve already asked this in the comments below this article ...
3
votes
2answers
2k views
What is p_T? (transverse momentum?)
I've been looking at a few papers in experimental physics (from the ATLAS collaboration, for example) and I've often run across phrases such as "high-p_T electron." What exactly is p_T? Is it simply ...
3
votes
1answer
259 views
What are the advantages of the ILC over the LHC?
USA Today has an article on Japan's interest as the site for the $10 billion future International Linear Collider. This accelerator will utilize electron/positron collisions (like CERN's former LEP ...
4
votes
0answers
103 views
Is there precision experimental evidence for Furry's theorem — that only even degree VEVs are non-zero?
Is there precision experimental evidence for or contradicting Furry's theorem -- that only even degree VEVs are non-zero, specifically for the EM field?
4
votes
2answers
192 views
What do “local” and “global” mean when talking about standard deviations in experimental particle physics?
I found the following sentence:
The excess is most compatible with a SM Higgs hypothesis in the vicinity
of 124 GeV and below, but the statistical significance (2.6σ local and 1.9σ
global after ...
5
votes
1answer
196 views
What is the smallest distance between a decaying vertex and an interaction point a detector can measure?
A short lived particle is created at the interaction point and then decaying a distance $d$ away, in some detector. My question is what is the smallest distance $d$ that can be measured ...
0
votes
1answer
233 views
Where to find experimental/theoretical value of (charge) radius of particles?
Where to find experimental/theoretical value of (charge) radius of particles like proton, neutron, $pi^+$, etc. ?
4
votes
1answer
284 views
What's jet multiplicity?
That's a basic thing, but, surprisingly, it is very difficult to find concise explanation of:
What is the definition of jet multiplicity?
Why is it interesting?
3
votes
2answers
253 views
What is the highest accuracy of measuring time differences achievable today?
I was wondering if it would be possible to shorten the distance between detectors when measuring the speed of neutrinos to, say, 7m rather than the current ~700km? In this way the distance traveled ...
12
votes
1answer
303 views
How are neutrino beams emitted at CERN?
As far I know they come from accelerator collisions, but I have read confusing things like magnetically focused. How could neutrinos be guided magnetically if they aren't affected by
the ...
10
votes
2answers
69 views
ATLAS Higgs Interpretation
I came across this abstract, and I am curious as to what the ATLAS Team has actually discovered:
Abstract Motivated by the result of the Higgs boson candidates at LEP with a mass of about ...
1
vote
0answers
62 views
What is the variable plotted on the y-axis on these Higgs exclusion graphs? [duplicate]
Possible Duplicate:
Particle physics plots
I have seen graphs like this in lots of talks by phenomenologists talking about the Higgs search (see for example FIG 3 in this paper or this blog ...
