The latest status of the Higgs Boson search at the LHC will be announced on the 4th of July. The conference will be held in Geneva. Incidentally, the International Conference on High Energy Physics (ICHEP), 2012, will also commence on the same date, but in faraway Melbourne.
The Higgs announcement
The announcement is expected to a big one – especially with the predicted discovery of the Higgs by the end of the year. The status of the Higgs will not be changed to ‘discovered’, but we will get to know how far we have actually reached.
We have already told you why you shouldn’t believe the rumors going around about the Higgs being discovered (LINK). It hasn’t been discovered as yet!
Just to sum up that post in the link, we predict that the CERN conference will announce that the Higgs bump in 8 TeV data matches with the bump in the 7 TeV data. Better make your way to that post!
CERN and murky money matters
CERN’s problem with making the official announcement from ICHEP in Melbourne is that Australia is not a ‘member state’ of CERN. Why make an official announcement in a country that doesn’t foot the bill for running of the LHC? So Geneva it is! And July 4th.
The CERN conference is scheduled for 0900 hours Geneva local time, which is GMT + 2 hours (i.e. it is two hours ahead of GMT) currently, due to daylight savings.
Do stay tuned to our coverage of the announcement.
Israel became the first non-European nation to join CERN. The decision was made at a meeting in Geneva on the 16th of September, 2011. Israel will be an Associate Member’ of the CERN collaboration and will keep that status for a minimum of 24 months.
Israel has been an Observer’ State for the CERN Council since 1991. It was promoted to special Observer’ in 2009. This move was inevitable.
Road Forward for CERN
Recently, at the Lepton Photon Conference, 2011, held at the Tata Institute of Fundamental Research, Mumbai, India, Rolf Heuer, the Director General of CERN, outlined the road ahead for CERN. He said that there were plans to include non-European nations into CERN in his speech. The E’ in CERN would no longer stand for European’, but would come to mean Everyone’, he said.
Rolf Heuer, DG, CERN and the Israeli Ambassador and Permanent Representative to the United Nations, H.E. Mr. Leshno-Yaar signed the agreement , which admitted Israel to the CERN Associate Membership. The document still needs to be ratified by the Knesset. This officially makes Israel a member for a minimum of 24 months.
Rolf Heuer said of this development:
It is a vital part of our mission to build bridges between nations. This agreement enriches us scientifically, and is an important step in that direction.
Israel had played a major role in the 1990’s, during the historic Large Electron Positron (LEP) Collider Experiment. This was an important milestone in the legacy of CERN.
More than just science
This move will gain Israel more monetary support from CERN to further its own research interests. Israel has supported Palestinian students in research by providing them funding and equipment on the same footing as Israeli students. It has sent mixed Israeli-Palestinian students at the various summer science camps organised by CERN.
The very act of systematically scouring for facts, known as science, might be the adhesive for the world that wise men have been looking for.
It was just yesterday, yet we have come so far! The first proton beams at a respectable 7 TeV energy was started only on 30th March, 2010. It has been hardly a year and a half and so much has already been achieved. This was the basic message sent out by CERN speakers Frederick Bordry and Rolf Heuer, also the Director of CERN at the Lepton Photon Conference, 2011, being held at Tata Institute of Fundamental Research, Mumbai, India.
There are a lot of projects on the horizon, both short time and long time. Obviously, the long term projects are ambitious and a bit ambiguous as of now. However, as Heuer said, they are practical. We should not be afraid that it is not easy, he said.
Among the many new developments happening or proposed at LHC is the development of magnets that can generate extremely high magnetic fields, called high-field magnets. These will be required to increase the energy of a beam, without lengthening the collider tunnel. Prof. Michael Peskin of SLAC, who was in the audience, asked if this is a dream or a programamidst chuckles, to which Bordry replied that it was certainly a realistic program.
The LHC is expected to have a long shutdown period from 2013 to mid 2014 for repairs and maintenance work.
New physics and monster accelerators
A number of new projects are upcoming, even though they haven’t been officially sanctioned. Yesterday’ it was the synergy of the Tevatron, HERA and SLAC that led to the discovery of the Standard Model, said Heuer, adding that the LHC results will guide the way at the energy frontier.
About the Higgs search, Heuer said that while finding the Higgs will be a discovery, not finding the Higgs and ruling it out will also be a major discovery. People should not say that these scientists are searching for nothing, he quipped. Not finding the Higgs will be a major result, since it will completely destroy the Standard Model, allowing other models of physics to come into the limelight.
Among a plethora of futuristic plans announced, the most spectacular was the announcement of a hadron-lepton collider the LHeC. The LHC is a hadron-hadron collider. It can collide protons together or lead/silver nuclei etc. A hadron-lepton collider will be able to collide a proton, and say an electron. The energy per beam of the LHeC will be 16.5 TeV, combining to give a massive 33 TeV in total. The LHeC design is on my desk right now, but I shouldn’t be mentioning that here, he remarked drawing loud laughter from the global audience. As far as LHC physics is concerned, he said that 2012 will be a decisive year. The TeV results will either lead to the discovery of new particles and some new physics will be known or it will be a reformulation of the physics we already know. Both will be progressive steps for particle physics.
Heuer spoke at length on the building of the linear accelerators International Linear Collider (ILC) and the Compact LInear Collider (CLIC). Today, we need to keep our choices openwas Heuer’s advice.
On the question of collaboration, Heuer said that CERN was throwing its doors open to non-European countries. The E’ in CERN is going from European’ to Everybody’. We’re not changing our name, however, said Heuer.
Exciting times in particle physics beckon us! As usual this sentiment was put emphatically in Heuer’s own words -We are just beginning to explore 95% of the universe.
I’ll let the scientist in Heuer have the final word on this report. When asked if he’ll be bothered if the next big accelerator is located in the US, instead of at CERN, Heuer put it beautifully, I don’t care where the collider is! I only care about the science coming out of it.
The scientific enterprise is a greater binding factor than anything else. It’s a silent messenger of world peace, uniting the world in the pursuit of truth and never advertising that facet.
If a high energy collision means fast billiard balls colliding or a train wreck, this article is tailor made for you. As the world, or at least the 0.042% of it who are interested in particle physics, gets their opinions ready about the yet unsuccessful Higgs search at the Large Hadron Collider (LHC), CERN, we thought it might be a good idea to explain what physicists mean by what they say. However, we don’t want to explain why they speak that way.
Here we will list out a few things you’ve heard and are likely to hear in the coming days, along with what they might possibly mean.
Units and Particles:
In particle physics, people prefer to use units of energy, instead of that of mass to measure mass. The idea is a good one, since we can use Einstein’s relation E=mc2 directly. The unit of energy is an electron volt or eV. If you force an electron to go through one volt, then it has the energy of 1 eV. It’s too small to use, so people use 1Mega eV (MeV) 1 million eV, or 1Giga eV (GeV) 1 billion eV. If that is not large enough, the LHC demands that we use 1 Tera eV (TeV) or 1 million million eV. The LHC is currently operating at 7 TeV.
The more important point to note about energy is what is considered big! How much really is 1 TeV of energy in human scales? It’s much less than the kinetic energy of a house-fly! So why is it called high-energy physics? It’s because this energy is carried by particles that are really really small! If a proton having 3 TeV of energy is scaled up to our scales, then we would each have energy exceeding that of a Supersonic jet plane. There’s a large amount of energy packed into a small volume.
About particles, there are just two types Fermions and Bosons. Know that fermions don’t like hanging out together, while bosons have no such ego issues. You can stuff a lot of bosons at one place, while that is impossible in case of fermions. Leptons are one kind of fermions, which are electron-like. Photons are bosons. (As to why this happens, it’s related to the Pauli Exclusion Principle, a fundamental result from quantum mechanics, responsible for single-handedly creating all of chemistry! Fermions follow Pauli Principle, bosons do not).
This is probably the most important phenomenon in this story, so pay attention. This is the deal. Every modern physical theory has some symmetry associated with it. For example, if you made all the positive charges in the Universe negative and the negative charges positive, the Universe will still look exactly like it does. Here’s the crucial part with every (continuous) symmetry, is associated a quantity that is conserved, or doesn’t change value. Example: Take time translation. If time were to flow backwards, at the microscopic scale, we would notice nothing. This symmetry leads to conservation of energy. Symmetry breaking refers to the fact that under certain circumstances, a physical theory loses the symmetry it started out with. We can then distinguish between different states. We can choose.
A Useful Analogy
The best analogy I’ve heard asks you to picture a round table with 10 people sitting equally spaced from each other. There is one glass of water kept identically placed between each two adjacent persons, making it 10 glasses in total. Assuming that the glasses are all identical, one can go and reach out for either one there is no preferred choice as yet. (Situation 1 in the graphic below.) But, say someone does pick up a glass say the glass placed to his/her right.(Situation 2 in the graphic below.) Then, everybody will HAVE to pick the glass to his/her right (assuming that no one wants chaos!). Now, you can differentiate between this system and another such system in which someone went for the glass on the left. Symmetry breaking has allowed us to identify a parameter, which had earlier left the system invariant. The word spontaneous’ is clear from this context. The perturbation has to come from within the system and everyone will choose a glass. The symmetry has been spontaneously broken!
In physics too, there arises situations in which the ground state (or state of lowest energy) of a theory is invariant under certain symmetries. This symmetry can, however, be broken and spontaneously, too if the system interacts with a field. It can be shown that this leads to two distinguishable states one having mass. Physicist believe that this is how mass is generated. The interaction field is named Higgs field’ and the force carrying boson associated with the field (as with any force field) is the Higgs Boson.
We could like to conclude this brief glossary of explanations here. Know that these explanations are highly simplified and the whole picture is much richer in beauty and technical details than this. Unfortunately, I won’t be able to communicate that beauty to a person, not having enough background in physics (being a major in physics is a must) and maths. If you already have a background, you’ve probably already seen a bit of the beauty. Go in search of more.
The world is not only queerer than we suppose, remember; it is much queerer than we can possibly suppose. In the words of the immortal Richard Feynman, I think Nature’s imagination is so much greater than Man’s, She’s never going to let us relax.
Links to related articles:
The Higgs search being unsuccessful so far, ATLAS and CMS collaborations of CERN jointly announce. Initial report here.
The figures and numbers (statistics) from the CERN announcement here.
The latest results on the Higgs search are out. Results were presented separately by ATLAS and CMS detectors of LHC, CERN today(i.e. 22st August, 2011) at the Lepton-Photon Conference, 2011. In this semi-technical article, we present the most important results in a systematic form. The verdict is, however, out the Higgs hasn’t been found as yet.
Check out our first (non-technical) post on this discovery here. A countdown to the Lepton Photon Conference itself is here.
Higgs Production and Decay channels
There are a few things that should be kept in mind right throughout the article. The Higgs boson is primarily produced by interaction of two gluons. (A gluon is what keeps protons and neutrons in an atomic nucleus together.) This is called gluon-gluon production of the Higgs boson.
Next, the Higgs, being highly massive (i.e. having a high mass) decays into lighter particles. This is what massive particles always do they decay into lighter particles. The only thing is that different particles decay at different rates. Heavier particles will decay much faster than comparatively lighter particles.
The Higgs can decay into a number of lighter products. Each of these products leaves a distinctive signature on the detectors and the different modes of decay are called different decay channels’. The Higgs primarily has a gamma-gamma (Higgs decaying into two gamma ray photons.) channel, a WW and a ZZ channel. These are the main channels of interest. The gamma-gamma channel will be the preferred channel if the Higgs is a comparatively light particle about 100 GeV in mass. If the Higgs decays by producing two Z-bosons (the ZZ channel) or two W-bosons (WW channel) then its mass is above 130 GeV. In other words, the gamma-gamma channel fixes the upper limit of the Higgs mass at 130 GeV, while the WW and ZZ channels fix the lower energy bound at 130 GeV.
Now, here is the interesting part. The WW or ZZ bosons are themselves quite heavy and decay into a number of products. These decay channels produce characteristic detection patterns in the detectors. Comparing the observed rate of decay into these channels with that of the expected value, the data is reconstructed to see if this indeed was a Higgs event.
Now for more technical details
The ATLAS detector found no significant excess in the gamma-gamma channel. The bottom-bottombar (b-bbar) channel (this is what the WW bosons break down into bottom and anti-bottom quarks) gave big excess of Higgs event above the theoretically expected Standard Model(SM) production rates. Even though the excess was nearly 10 times the SM predictions, the sensitivity needs to be improved. Furthermore, Tevatron has a much greater say in the b-bbar channel than the LHC, given that it has recorded much higher number of events and has a higher luminosity at that energy range. The tau-tau (tau is a lepton, an electron like particle) channel gave a 4 to 5 times excess.
Overall, there was no significant excess in any of the channels to warrant a discovery. There was no significant excess number of events noticed for the Higgs in the mass range of 110 GeV to 160 GeV. This mass range is tentatively excluded with 95% confidence level. However, at 99% confidence level, there is a window about 142 GeV, which can be a possible detection window. Further experiments will probe this window more thoroughly.
CMS detected no excess in the gamma-gamma channel. A slight excess was noticed in the tau-tau channel and this is expected to be an important channel for further investigation, owing to the fact that data reconstruction from this channel points to a Higgs mass of about 140 GeV.
Excess of events in the WW going to lepton-lepton channel suggests a mass range of 130 GeV to 200 GeV. Three pairs of events have been notices at three mass ranges 122, 142 and 165 GeV for the ZZ channel. Only the 142 GeV event is consistent with Standard Model predictions. Happily, this is the very window that wasn’t excluded earlier with 99% confidence level.
Out of theoretically expected mass range exclusion of 145 to 440 GeV, three ranges have been excluded 145 to 216 GeV, 226 to 288 GeV and 310 to 400 GeV. Anything above 400 GeV is unlikely and the crucial 130 to 145 GeV window is still open. These mass ranges have been excluded with 98% confidence level.
Higgs search continues with full force. LHC will provide a lot more data samples in the coming months and this might ultimately lead us to achieve the Holy Grail of Particle Physics.
HIGGS SEARCH RETURNS A BLANK! HIGGS BOSON NOT FOUND BY LHC, CERN!
This is the joint announcement made by the ATLAS and CMS teams, LHC, CERN at the Lepton-Photon Conference, 2011 being held at Tata Institute of Fundamental Research (TIFR), Mumbai, India. This is likely to be a disappointment for many around the world, both within and without the particle physics community. The search is however on!
A warmup countdown post to this Lepton Photon Conference, 2011 is here. Semi-technical post showing all relevant results and figures can be found here.
The Higgs Boson
The Higgs Boson, predicted from considerations of symmetry in Quantum Field Theory by Peter Higgs, is the particle theoretically responsible for endowing every other massive particle with mass. It’s a boson with spin zero, with positive parity and charge.
There were a number of weak signals noticed that preceded the event. These Higgs signatures’ included the W-W or the Z-Z decay channel for the Higgs as the primary decay channel. This means that the Higgs once produced will decay into two W or Z-bosons, which will in turn break up into electron-positron pairs or muon-antimuon pairs. Unfortunately, none of these events could stand up to the rigors of analysis and survive till the 5 sigma confidence level was reached in both ATLAS and CMS detectors, as yet.
No such significant excess has been observed in the lower mass gamma-gamma channel. Also, more exotic branches like the tau-tau and b-bbar (bottom-bottombar quarks) have not offered anything promising.
The results of Tevatron, Fermilab are similarly blank, with no significant excess noticed in any channel.
This is also an exciting opportunity it opens up new possible physical theories. Spontaneous symmetry breaking, at least what we know of it now, may not be the whole story. There are many rival’ theories of the Standard Model, many requiring no Higgs boson to achieve mass. These Higgless models may become the focus of mainstream research and the LHC may be next used to test the predictions of such theories.
However, it is too early to make such claims. The Higgs search is going on at full blast.
And a Promise
We will bring more articles soon, explaining what this means for the Standard Model and particle physics in general. We will also run an article elucidating the jargon of particle physics. Hold on for that it’ll come sooner that you think.
Actual results from the ATLAS and CMS joint announcement on the Higgs Boson search can be found here. All relevant facts and figures present.
Some big news is just around the corner. The ATLAS collaboration at LHC, CERN is all set to announce the status of the Higgs Boson search at the giant collider in the upcoming week at the Lepton-Photon Conference 2011, being held in Mumbai from 22-27 August, 2011. The announcement is one of particular importance since it is rumored to be the definitive one in the quest for the Higgs Boson. Whether the Standard Model of Physics, one of the most beautiful and successful edifices of physics ever constructed, will stand or need revision will hinge crucially on this one announcement.
The Lepton-Photon Conference, 2011
The Conference The XXV International Symposium on Lepton-Photon Interactions at High Energy will take place in Tata Institute of Fundamental Research, Mumbai, India and will attract prominent personalities from the world of high-energy physics. The coming week is expected to be a hectic one for both students and physicists at the Institute, with the who’s who of particle physics presenting and discussing current progress, while also charting the road ahead. Preparations are on at full swing within the Institute premises.
We at Techie-Buzz will be covering the huge scientific event from Ground Zero and presenting all the major announcements in real time from it. You might want to bookmark the website and visit it frequently or subscribe to our newsletter, if you aren’t already on the subscription list.
Some exciting developments precede the event
The watch-word is Higgs’ for everyone and with certain encouraging signs noticed in the last few months, everyone is excited. Particularly stunning are the two results graphed below. Explanations follow the graphs.
Look at the two graphs (don’t get scared!). The thick black line in each graph represents the Higgs signals. The dashed line represents the predicted Higgs production rate by Standard Model Calculations. A proper signature is said to be found when the observed signal overtakes the predicted signal. Look at the region marked, just between 130 to 150 MeV, where the production rate far exceeds the predicted rate. This coincides with the predicted mass range for the Higgs. This in itself proves nothing, as this might be due to something completely different. What is exciting is the fact that this weaksignal is being noticed in both the LHC detectors, ALICE and CMS. Concurrent results have a better chance of surviving thorough data analysis.
For clarity let me reiterate the two important takeaway points: First, both detectors, ATLAS and CMS, agree on the Higgs signature. Second, the signals have been noticed in the theoretically expected mass range (about 130-150 GeV).
The results are now quoted at a 95% confidence level (or 2 sigma) and do not warrant the label of a discovery’. For that, you’ll require 99.997% confidence (or 5 sigma) from both detectors. We might be onto that.
At the risk of being repetitive, let me again emphasize that the announcement at the Conference in the coming week will nearly finalise the fate of the search for the Higgs Boson. If not found, it may be the beginning of new physics.
Hope to see you here through next week.
Update: The CERN Announcement on the ATLAS and CMS results on the Higgs Search is here. Check it out, its big news.