Higgs Search in CMS and ATLAS

While we are coming to the end of this year, there were lots of rumors on Higgs last week. Today at CERN the two big experiment CMS and ATLAS which are explicitly designed to discover the so-called Higgs particle announced the last finding of Higgs.

Both experiments found some excess in $115-130 GeV/c^2$ (ATLAS $115-130GeV/c^2$, CMS $115-127GeV/c^2$) and that could be due to Higgs boson decay. The experimental scientists at CERN carefully analyzed the all known decays of all known particles, then did some Monte Carlo simulations for a particle behaves like Higgs and compared the results. Indeed there is excess both in ATLAS and CMS more importantly in a few different decay channels those channels have quite different backgrounds so seeing that excess is quite significant. If Higgs really exist and its mass is in that region today could be one of the days that will be remembered and mentioned in popular science physics textbooks.

A candidate event for H->Diphoton in CMS.

But in human history there are many false discovery claims, surely it could be false, and in time when we get enough data, the excess could be just a statistical fluctuation. In 2012 the LHC will continue to deliver proton beams and both experiments will continue to gather the data from the debris of proton collisions, possibly at the end of 2012 the data will be at least two folded and then we could certainly falsify the Higgs or celebrate the discovery.

Here you can find the famous excess both in CMS and ATLAS. I also attached statements and the presentations below.

In CMS a total of $~4.6fb^{-1}$ data is analyzed.

In ATLAS in total up to $~4.9fb^{-1}$ data is analyzed.

Scientist to find out whether an excess of the data is indeed a particle or just statistical fluctuations they use statistical techniques. So to claim a discovery, they use a parameter called $sigma$. Let me try to explain simply what the particle physicists mean when they say "we observed an excess with $sigma$ equals to something."

If Newton were sitting under his apple tree and making observations of falling apples, so he can claim the discovery of gravitation, and made 100 observations of falling apples and hitting him in the head and only ONE instance of those falling apples didn't hit him in the head, it is called $\sigma=2.5$. At $\sigma=3$ apples fell and didn't hit Newton in one out of every 370 times. That is not a scientific discovery either. If you observe the falling apples for a more than million times and only one of the apple doesn't hit in the head then we say $\sigma=5$. THAT is what we call a SCIENTIFIC DISCOVERY.

The CMS Statement

The ATLAS Statement

You may also check these links where you could watch the presentations held by ATLAS and CMS Spokesperson, 

http://cdsweb.cern.ch/record/1406052

http://cdsweb.cern.ch/record/1406051

Do the neutrinos break the speed of light?

Neutrinos have such small mass,

we couldn't even measure it but

constrain what it could be at most. 

Last week according to the result published by the OPERA experiment held between CERN (Geneve-Switzerland) and Gran Sasso (Italy) seems like neutrinos- created by electroweak interactions- appears like travel faster than the speed of light. The last report from that experiment suggest that neutrinos with an average energy 17GeV exceed the speed of light about 

$(v-c)/c=2.48\pm0.28(stat.)\pm0.30(sys.) \times 10^{-5}$

here $c=299\,\,\,792\,\,\,458m/s$ is the speed of light in vacuum. Neutrinos are created at CERN, and they travel to Gran Sasso about $730534.61m$ and according to the detailed analysis by OPERA experiment neutrinos exceed the speed of light by an amount of $~7435m$. That seems quite small compared to the speed of light but if it is true the implications on modern physics and the understanding of the laws of the universe are unthinkable. Therefore I would like to point out that since I see a lot of articles about Einstein implying that he was wrong or his theory just broke apart. In fact, in the article about special relativity, he never claimed that nothing could travel higher than the speed of light, contrary he claimed that nothing could accelerate and exceed the speed of light.

To be more clear I would like to write down the speed of light and the speed of neutrinos. 

speed of light         $299\,\,\,792\,\,\,458 \,m/s$

speed of neutrinos  $299\,\,\,799\,\,\,893 \,m/s$

Just notice the last four digits. If you would like to learn much about the experiment or the analysis you could read the report in arXiv.

Update: Recently the OPERA collaboration after more analysis on the data and new data, they analyzed systematic error sources and backed up their first result that neutrinos indeed travel exceeding the speed of light. Sure a lot of discussions and possible explanations for the phenomena emerge, here one of the blog pages where a lot of discussions still going on.

The Crackpot Index

Well, once in a while I indeed face an uneducated fella who claims that Einstein's energy-mass relation is wrong not knowing there is momentum as well in the equation or some other who just discovered a machine that could run forever or a way to produce energy but giving less. Anyway, I have found a way to index all these ideas thank John Baez for supplying this list. Here is some of them

A simple method for rating potentially revolutionary contributions to physics:

1. A -5 point starting credit.
2. 1 point for every statement that is widely agreed on to be false.
3. 2 points for every statement that is clearly vacuous.
4. 3 points for every statement that is logically inconsistent.
5. 5 points for each such statement that is adhered to despite careful correction.
6. 5 points for using a thought experiment that contradicts the results of a widely accepted real experiment.
7. 5 points for each word in all capital letters (except for those with defective keyboards).
8. 5 points for each mention of "Einstien", "Hawkins" or "Feynmann".
9. 10 points for each claim that quantum mechanics is fundamentally misguided (without good evidence).
10. 10 points for pointing out that you have gone to school as if this were evidence of sanity.

The rest of the list.

13.8 Billion Years Ago: All set, let's fire this COLLIDER

Couple of days ago I found a comic on one of the doors in Theory Division @ CERN. I took a photo. Whenever I  look at it still makes me laugh :) I congratulate whoever draw it. Sorry don't know who to credit.

TED Talks

I know a lot of people who watches TED talks, and most of the days I, indeed, try to watch at least one interesting talk I have found irresistible to watch. There are a lot of joy in the stories and also one the speakers. The talks are in wide broad from science, fascinating facts even on how to tie your shoe lashes. I strongly suggest to search or go to main page and look at already smartly labeled talks like

• ... persuasive
• ... courageous
• ... ingenious
• ... fascinating
• ... inspiring
• ... beautiful
• ... funny
• ... informative

The motto of TED is IDEAS WORTH SPREADING.

One talk I found interesting...

The stories of Murray Gell-Mann, Freeman Dyson

I stumbled on a great website where experts tell the story of their life, and besides of Nobel Prize winners, there are great physicists. I have found outstanding stories like Freeman Dyson, Murray Gell-Mann, and Hans Bethe. I strongly suggest watching, since it is also my research area, especially the speeches on the development of Quantum Field Theory.

I would like to express my difficulty of learning QFT even though there are so many resources on it, it really takes time and study to understand the idea behind every calculation/computation or idea. Also why it is invented and the way of thinking of the inventor.

Finding that great website on the stories of great experts on physics was really helpful for me because I, usually, go and read the original papers.

Here some interesting videos I have found interesting . . .

Freeman Dyson's Work

Murray's Gell-Mann: The Sakata Model
                                  Sheldon Glashow Model
Hans Bethe: The Bethe-Heitler Formula
John Wheeler: Witnessing the explosion. Edward Teller's seismograph

Pierre Louis Maupertuis

Pier Louis Maupertius

In my spare times usually, I look at the work of mathematicians and physicists of old times and seek the original papers just to understand what was in the mind of the writer. It is still under debate who earns the credit, but Maupertius is the one who first formulated the Least Action Principle. After a little search, I found the English translation Accord between different laws of Nature that seemed incompatible (1744) and Derivation of the laws of motion and equilibrium from a metaphysical principle (1746).

Therefore, I would like to stress that even though the least action principle initially is formulated for the equation of motion of a mechanical system. Later by Hamilton and Lagrange developed the Hamilton and Lagrange formulation of classical mechanics. In 20th century Schrödinger used the principle to write down the famous wave equation for de Broglie waves which is Schrödinger Equation. The interpretation of the Schrödinger equation led to the probability waves in the atomic world and the birth of quantum mechanics. The same principle is also applied in the development of Relativity. Last but not least, it plays the essential role in the development of Quantum Field Theory.

Here the life of Pierre Louis Maupertuis, the one who formulated the Least Action Principle in Wikipedia.

It would also be nice to mention French mathematician Lagrange who formulated the known by his name the Lagrange formulation of classical mechanics. His original work in French (it would be really nice if somebody points to the English translation), and autobiography. Lagrange solves the system in 2nd-order differential equations in n-dimensional configuration space. The configuration space is simply defined as the degrees of freedom in the system.

The Original Derivation of Schrödinger Equation

Taken from wikipedia:

In January 1926, Schrödinger published in Annalen der Physik the paper "Quantisierung als Eigenwertproblem" [tr. Quantization as an Eigenvalue Problem] on wave mechanics and what is now known as the Schrödinger equation. In this paper he gave a "derivation" of the wave equation for time independent systems, and showed that it gave the correct energy eigenvalues for the hydrogen-like atom. This paper has been universally celebrated as one of the most important achievements of the twentieth century, and created a revolution in quantum mechanics, and indeed of all physics and chemistry.

A second paper was submitted just four weeks later that solved the quantum harmonic oscillator, the rigid rotor and the diatomic molecule, and gives a new derivation of the Schrödinger equation.

A third paper in May showed the equivalence of his approach to that of Heisenberg and gave the treatment of the Stark effect.

A fourth paper in this most remarkable series showed how to treat problems in which the system changes with time, as in scattering problems. These papers were the central achievement of his career and were at once recognized as having great significance by the physics community.

The English translation of these papers could be downloaded HERE.

Lebesgue Integral and Fubini Theorem

Lebesgue Integral:         $F(x)=\int_0^xf(y)dy$


Fubini Thorem:              $\int_a^b\int_c^df(x,y)dxdy=\int_c^d\int_a^b f(x,y)dydx$


If one day, for some reason, you need to calculate double integrals and the integral is a kind of Lebesgue Integral defined above. You simply want to change the order of integration. Then, you need to use Fubini theorem.  One simple example is given below:

$\int_0^1\int_0^xf(y)dydx=\int_0^1\int_y^1f(y)dxdy$

But, to be able to apply the Fubini theorem, you have to note that If the double integration is defined as $\int_a^b\int_c^df(x,y)dxdy=\infty$ then $\int_a^b\int_c^df(x,y)dxdy\ne \int_c^d\int_a^bf(x,y)dydx$. For more information and step by step example is given in this video.

Introduction to Quantum Field Theory

In the 20th century, the first paradigm in physics was the probabilistic approach to the interaction of particles in the atomic world. Since then quantum field theory (QFT) for the interaction of particle fields via force fields is developed. Undoubtedly, to solve the equation of motions numerous advanced techniques are also developed. I use quantum field calculations to get the probability (amplitude) of various kind of interaction between the elementary particles. Then, compare the results/implications to the experiments.

I spent a lot of times on studying QFT, and there are still a lot of things to learn. Indeed, I do that every day. After the revolution of the www, or should I say search machines like Google, it is much easier to reach the information you seek. I have found a lot of resources on QFT, many of them are downloaded, and wait to be reviewed, and many of them are done. Along the way, since, it is in the nature of learning that you think you understand the idea by putting it in the pre-learned concepts in your mind. But, most of the time you do not get the concept/idea entirely, and just fill in the blank areas in time. It also possible that you misunderstand some of it. By solving problems, re-reading the textbooks and other resources it is possible to correct the mistakes and the blank areas in your mind. Then, you understand/learn the concept. Therefore, it is vital and a strong requirement for you to read as many resources as you find, repeat all the steps in the proofs so that you could be on the shoulders of the giants before you.

Here I have gathered a list, where you can find valuable lectures on QFT, either you can watch and read.

Books and Text:

1. Quantum Field Theory by de Wit
2. Introduction to Quantum Field Theory by Peskin and Schroeder
3. http://theory.fi.infn.it/casalbuoni/

Videos

1. Quantum Field Theory by Bernard de Wit @ CERN (1991) 
2. Lectures on QFT by Kevin Cahill
3. Explorations In Particle Theory
4. African Summer Theory Institute
5. TASI 2010 Videos especially the one given by Matthew Strassler about the Higgs sector in SM and fundamentals in Particle Physics.

I have many links to post, but I don't have time to update :)

Update: I have added the lectures given by de Witt, it is presented so long ago like 20 years ago at CERN, and just recently I had spare time to watch and go through the lectures. I must say that the details given in these lectures are really fascinating. To grasp those details from somewhere else is almost impossible (too much time consuming). Otherwise, you should read many textbooks and do a lot of problem-solving. I also checked his web page for notes, and I have also found many resources. The notes, indeed, have many details and you see a lot when you walk through this wild topic compared to other textbooks.

I wanted to update this blog since I created but somehow time passes, and I just can't do due to the absence of free time. You may find some interesting links on this FaceBook Group Page. I try to gather interesting kind of news in High Energy Physics.