LHCb Detects Decays of B-Mesons Which Hints At New Physics

The most promising signatures of something beyond what we know have been coming consistently from an experiment in LHC, CERN that has received the least public attention. While the CMS and ATLAS detectors (and collaborations) at the LHC are running their proton beams day and night in search of several things, primary among them being the Higgs Boson, the other big experiment, the LHCb, has been quietly chugging along with its own set of measurements.

Part of the LHCb detector

The latest from the LHCb detector, housed in the same compound as the CMS and ATLAS, is a result that just might signal physics from Beyond the Standard Model (BSM), fashionably titled New Physics. BSM has been a devoutly investigated area of interest for both CMS and ATLAS, but the LHCb focusses on very specific types of particles and observes their modes of decay.

‘Exotic’ Physics

The types of particles LHCb is interested in contains a very exotic type of quark – the bottom quark. Protons and neutrons don’t contain that quark; they are entirely made up of ‘up’ and ‘down’ quarks. The Standard Model accurately predicts the decay rates and lifetimes of particles and, so far, experiments and theory have always matched. The recent LHCb result, adding to a few other ‘anomalous’ results of the past, show deviation from the theoretical values. Of course, no one is jumping into the BSM bandwagon just yet, but there is clearly excitement.

The Result

The LHCb collaboration found that a specific decay – a B-meson (i.e. a particle containing the bottom quark) becoming a kaon (another short-lived ‘exotic’ particle) along with a muon-antimuon pair. Muons are like heavy electrons. The LHCb collaboration observed that there is a difference in the decay rates between a neutral B-meson going to a neutral Kaon-muon-anti-muon and a positive B-meson going to a positive Kaon-muon-antimuon. This difference – called ‘isospin asymmetry’ – is not predicted by the Standard Model and this is what is interesting.

More data is required to confirm whether this is really a BSM signal.

The CERN bulletin: https://cdsweb.cern.ch/journal/CERNBulletin/2012/21/News%20Articles/1451542?ln=en
The LHCb detector website: http://lhcb-public.web.cern.ch/lhcb-public/


Data From LHC and Tevatron Shows No Signs of the Existence Of Extra Dimensions

Negative results are important and the LHC just shows that. While the LHC hasn’t been able to find the Higgs Boson with absolute certainty as yet, it has done physics great service by eliminating a lot of different possibilities and put stringent bounds on existing theories. The CMS collaboration at LHC has just released a paper reporting their findings related to the existence of hidden extra dimensions. This is crucial to the very fabric of string theory.

The CMS detector at LHC

The CMS hasn’t found anything in their data that indicates that extra dimensions exist. The team has looked at the energy range of 2.3 to 3.8 TeV, which is the typical collision energy of protons, when the LHC runs at 7 TeV beam energy. The LHC recently upgraded to 8 TeV, 1 TeV up from the usual, but there is little hope of finding things at that energy. We can only wait till the LHC resumes its run after the break it is scheduled to take in a few days. It will be back at 14 TeV and maybe then we can get something on extra dimensions.

And the Tevatron adds to the misery…

Not only the LHC, even the Tevatron data eliminates the presence of extra dimensions, at least at low energies. The Tevatron is dead, but the data is still there and the D-Zero detector team is looking at the energy range around 260 GeV and have found nothing.

So far, the theoretical bounds on the energies at which particles might couple to extra dimensions have large errors. So this result really tells us what the lower limit for any experiment searching for extra dimensions should be.

The LHC is continuing to negate anything beyond the Standard Model. It has got good data to verify the one last piece of the Standard Model – the Higgs Boson – and the search is in its last few days. It seems that the emergence of physics beyond the Standard Model, except in the neutrino sector, isn’t happening at the moment.

Analysis of Tevatron Data Favors Low-Mass Higgs Boson; Confirms LHC Observations

A full analysis of the Tevatron data collected over ten years – a mind boggling 500 trillion proton-antiproton collision events – yields a narrower range for the Higgs mass. A new statistical fluctuation, seen with a confidence level of 2.2 sigma, narrows the range of the particle causing the fluctuation to between 115 GeV to 135 GeV. A GeV is a Giga electron Volts or a billion electron volts. These are pretty strong bounds on the mass. Furthermore, the entire regions between 147 to 179 GeV can be safely eliminated. This analysis confirms what the LHC data says – the Higgs is a low mass Higgs with a mass of about 125-126 GeV and the mass range above 141 GeV is eliminated with 95% confidence.

The local significances of the Higgs signature, both from the LHC and the Tevatron. Notice the continuous black line rising way above the dotted black line within the 115 to 127 GeV range. The horizontal light across the graph is the Standard Model prediction probability. The actual observed probability has to be greater than this line.

Excluded ranges and the range to look out for

The data, collected from CDF and DZero detectors of the now-deceased Tevatron, combines well with the LHC data, specifically with that supplied by the ATLAS detector, to restrict the Higgs mass between 115 GeV and 129 GeV. This also provides more confidence to the 3.6 sigma peak announced during the 13th December 2011 CERN broadcast. Kindly check the link here for very specific details of the seminar: http://techie-buzz.com/science/higgs-boson-cern-seminar-results.html

However, this result shows that the LHC and the Tevatron results match and that’s great, but it doesn’t get us any closer to actually finding the Higgs. Of course, if the Tevatron had disagreed, then we would’ve been in serious trouble.

Bottom line

Two things come out of this confirmation: The Higgs is most probably a low mass Higgs, having a mass of about 125-126 GeV. This is pretty interesting in itself, since this is not just the boring Standard Model Higgs, but gives an inkling of the success of supersymmetric theories. Secondly, the “look elsewhere” effect may not be as significant as was previously thought, now that the bounds are tighter. The “look elsewhere effect” takes into account the probability of finding the Higgs at every point within a certain range and not just at a very small interval. This considerably reduces the significance of the observed bump in general. Since the “look elsewhere effect” may decrease its contribution, concentrating on local significances may be quite the right thing to do!

Of course, the game will only be decided by the LHC. We expect to have enough data to pinpoint the Higgs by the end of this year, before the LHC goes into hibernation for 15 months. The game is heating up and getting interesting. Stay tuned…

CP Violation: Tevatron Detector Data Reconfirms What The LHC Had Already Said

The Tevatron at Fermilab may not be active any longer, but the data it has collected over its lifetime is still capable of inspiring great thoughts. The data, now fully analysed, has revealed what the LHCb had already found earlier, thus giving more credence to hypothetical ideas. The data yields answers to questions as basic as “Why is there matter in the Universe?”.

The CDF detector

CP Violation

In November 2011, we had reported about a reported CP violation in the charm quark sector. We inferred that by looking at the so-called D0-D0 bar mixing. The news can be found here. A more detailed discussion and explanation of the various things is given here.

So, let me just quote the basic figure. The LHCb quotes a figure of 0.82% deviation from the expected value of zero, from the Standard Model. A non-zero value of CP violation goes towards answering the question of why matter won over anti-matter, when equal amounts of the two were produced right after the Big Bang. Now, the CDF gives the same hints.

The CDF quotes a deviation of 0.67 % from zero. The result says -0.67% +/- 0.16%. Alongwith the LHCb results, the CP Violation stands at 3.8 sigma confidence level.

The Standard Model predicts that if CP violation is detected, it might signal the existence of new particles. So far, we have no data to indicate that so far!

With Upgrades, LHC Will Be More Energetic And Be Able To Handle More Collisions

The LHC is taking a vacation right now, but it promise to return with a bang! The LHC is due to run very soon, but instead of the usual 7 TeV (1TeV = 1 Trillion electron volts) total energy, it will try and go a bit higher and reach 8 TeV. Also the luminosity (basically number of collisions per second) will increase, but the increase won’t be substantial and there are reasons for that. Physicists promise enough data to pinpoint the Higgs and to verify the tantalizing 125 GeV peak that was reported earlier(here). Furthermore, after a packed 2012 schedule, the LHC will hibernate for a longer time and will wake up in 2014. During this time, the LHC will be fitted with newer instruments.

More work: ATLAS detector


The hardware upgrade will have to wait till end of 2012, when the LHC will shut down for an extended period of 14 months, waking up again in 2014. The hardware upgrade will allow the LHC to run at a huge energy of 14 TeV and much higher luminosity. This is crucial, since it is not only the energy, but the number of collisions that makes a lot of difference in the experimental data. More luminosity means lower uncertainty in the measured values. The current electronics won’t be able to handle the rate of data acquisition that the LHC is planning to achieve.

Higher luminosity

The LHC currently runs at 3.5 TeV per beam, giving 7 TeV on a two-beam collision. They plan to upgrade it to 4 TeV per beam, giving a total energy of 8 TeV. Each beam of protons is made up of bunches of protons, with each bunch being separated by a certain amount of time. Each bunch has a certain number of protons. The team will also look to increase the number of protons per bunch, but keep the number of bunches constant, thereby increasing the luminosity. The current bunch spacing is 50 nanoseconds. The LHC electronics is built so as to handle bunches separated by 25 ns. The LHC team might look at this small deadtime when it resumes in 2014.

All in all, the full blown search for Higgs might end soon, but the LHC is poised for more daring adventures!

Higgs Search Becomes More Promising With More Data Analysis; CERN Increases Confidence Level

The Higgs search gets hotter and hotter. Recent analysis of old data have raised the confidence level of the Higgs detection from the older value of 3.8-sigma overall to a much healthier 4.3-sigma, as indicated by the two papers sent for publication, one by CMS and the other by ATLAS. The Compact Muon Solenoid (CMS) detector group had given the confidence level of 2.5-sigma. Now, with the analysis of more data, they have pushed it up to 3.1-sigma. Remember that a 5-sigma confidence level is what you need for tagging something as a discovery – so 4.3-sigma, though exciting, is not momentous.

A Higgs simulation at CMS

There – but not quite there

The results overwhelmingly predict a Higgs mass in the range of 124-126 GeV, which is exactly what scientists had reported on December 13th.

A 5-sigma means that one is 99.99997% sure, while a 4.3-sigma result means that scientists are 99.996% sure that the identified peak is the Higgs peak.

Just a joke!

This is just an improvement over the ‘initial’ December announcements by CERN. The data is not new, since the LHC hasn’t been taking any since November, but a more thorough analysis has been done and this is what it says. I suspect that this is as far as CERN can go at the moment with the Higgs confidence levels, and they will require much more data to be completely sure.

The 3.8-sigma confidence levels shouldn’t be taken too seriously. There have been peaks of this confidence level, but they had vanished. Fortunately, this hasn’t.

A new chapter

We should have to wait another year or so before the LHC can give something definite on the Higgs search. Now that the LHC is temporarily closed down for mandatory maintenance efforts, the big bosses, meeting at Charminox, France, are discussing the energy and the luminosity it will be tuned to when it opens later this year. The scale up to 8 TeV in energy is expected, but the luminosity is not yet revealed.

Higgs Boson Definitely ‘Observed’, But Not ‘Discovered’ As Yet: Official Word From CERN

The Higgs search is not yet over and is all set to go on at LHC, CERN. This is the natural consequence of the CERN official seminar.

The Higgs has been definitely observed at the energy 126 GeV at a 3.6  2.3-sigma confidence level at ATLAS, combining all decay channels!

The data presented at ATLAS, by ATLAS boss Fabiola Gianotti, is more-or-less in line with Standard Model expectations.

Result from ATLAS:

The Higgs officially lies between 114 GeV to 141 GeV. The rest of the mass range has been eliminated with 95% confidence level.Several channels like the Higgs-> WW* has been excluded.

The mass range between 113 t0 115.5 GeV has been excluded, as has been the range from 131-453 GeV, with the exception of a window from 237-251 GeV at 95% confidence.

The Higgs-> gamma-gamma is a very promising channel and this suggests the 126 GeV figure for the mass of the Higgs. This suggests the presence of a ‘low-mass’ Higgs, which is quite in line with the Standard Model.  More data in 2012 will help CERN make a more definitive statement.

  • Bottom Line: Local Significance – 3.6-sigma; Global Significance – 2.3-sigma  at 126 GeV

Result from CMS:

The CMS results ruled out a high mass Higgs, much like the ATLAS results. 270-440 GeV was excluded and the Higgs->gamma-gamma channel gave very clear results. This low mass Higgs is very consistent with the previously announced ATLAS results, which is extremely good news.  There were excess events noticed between 110-130 GeV, in the tau-tau and bottom-bottom decay channels; this eliminates 134-158 GeV mass range.

A curious 4-lepton excess was noticed at 125 GeV, which is bang on target, if you take the ATLAS results (above) at face-value. This is again, very good news. The Higgs-> WW and Higgs-> ZZ excludes 129-270 GeV mass range. Multiple channel “modest excess” was noticed just below 129 GeV!

  • Bottom Line: Local Significance – 2.6-sigma; Global Significance – 1.9-sigma  at 124 GeV  
One of the key slides from today's seminar. Look at the excess in each of the channels at 126 GeV! (Courtesy: CERN live webcast)

The global results take into account the so-called ‘look elsewhere’ effect, which means that it factors in the chances of observing this same local excess at any point within a certain range and also in all channels.

The CERN announcement

CERN announced today that the Higgs has been observed’, but not detected’. The subtle difference between these two words lies in mathematics. When CERN says that they have observed the Higgs, it means that they are 99.73% sure that the Higgs is there. This is, however, not enough to guarantee the tag of a discovery. For that, the confidence level has to go up to 5-sigma, which gives a 99.99994% surety. This is very important, since 3-sigma effects have been known to go away in the past.

The non-discovery of the Higgs, as yet

The only reasonable explanation for the less-than-discovery tag at the moment is because LHC still doesn’t have enough data or rather, not enough data has been crunched.

This is surely great news for the particle physics community. The Higgs may be there in this and there are strong indications from both ATLAS and CMS that it is there and this means that the Standard Model has passed its stringent test yet! However, the mass is still to be ascertained exactly. The error bars haven’t been fully established.

So, the wait continues.

The Super Symmetric Models

This mass of the Higgs Boson, if actually true, is extremely exciting. It lends credibility to the cMSSM models, which is one of the basic Super Symmetric Models. There were widespread news reports that LHC has ruled out super-symmetric models or at least the simplest ones. Not quite! The cMSSM can accommodate a Higgs of 121 GeV mass and no higher. However, a small tweaking of the parameters yield a different version of the theory, which can very well accommodate a 125 GeV Higgs.

Another revolution may be just around the corner! Watch out!

Rumors Of A 125-126 GeV Higgs Observation

The Higgs seems to be playing the game better than ever, peeking out once in a while, but not for long enough time! Initial analysis of the data from both ATLAS and CMS indicate an excess in the gamma-gamma channel for the Higgs at about 125-126 GeV. ATLAS detects this at a high 3.5 sigma confidence level and CMS comes in at a more tentative 2 sigma confidence level. This is good enough to tag it as a proper observation. None is good enough to warrant the tag of a discoveryof the Higgs, which requires 5 sigma confidence levels.

More info here:  http://blog.vixra.org/2011/12/02/higgs-rumour-anaylsis-points-to-125-gev/

Both ATLAS and CMS observations are in the gamma-gamma or diphoton channel.

A simulated Higgs Event at LHC, CERN

We had told you about the Higgs search coming to an end here and also that there is a joint seminar in CERN on the 13th of this month. The announcement at this seminar is expected to be the definitive on the Higgs search. It will make or break the Higgs, and, thus, a part of the Standard Model as well.

125 GeV Higgs more interesting than a 140 GeV one!

In a way, a 125-GeV Higgs would be awesome news for physicists, since this mass would require corrections to the Standard Model, since the vacuum becomes unstable at high energies. A 140 GeV Higgs would’ve been more mundane, and would’ve been the simplest of all the scenarios.

The situation is a bit ironic really. The Tevatron had almost eliminated the Higgs gamma-gamma channel decay process. Many scientists were convinced that the gamma-gamma channel was no good, and if the Higgs is found, it will be via the ZZ or WW channels. Though this is not incorrect, the gamma-gamma channel has given one of the strongest signals of the Higgs till date and right before the big announcement at the seminar.

It is unlikely that CERN will say anything about this before the 13th December announcement. Fingers crossed!

More info here:  http://blog.vixra.org/2011/12/02/higgs-rumour-anaylsis-points-to-125-gev/

Revealing the God Particle: CERN To Hold Joint Higgs Boson Seminar On Tuesday!

There is palpable tension at CERN for sure people might not sleep till Tuesday, the 13th. The premier particle physics laboratory is all set to hold a special seminar that day, possibly to announce latest in the search for the Higgs boson. The search is nearing an end and this is expected to be a landmark announcement, possibly one that can either confirm or rule out the Higgs boson.

The 13th  December joint announcement might be the last one on the Higgs. We are hoping for either a confirmation or nullification.  

A 125-126 GeV peak for the Higgs? Tantalizing:  http://techie-buzz.com/science/higgs-discovery-rumours.html
The tunnel - to the final answer?

We had covered a seminar given jointly by the ATLAS and CMS collaborations last month here and we had told you that the search was nearing an end.

The latest news yet!

The mass ranges for finding the Higgs has been narrowed down to just 30 GeV between 114 to 144 GeV, as per the simplest version of the Standard Model. The finding of the Higgs boson is a crucial step, as it would be the final confirmation of the tremendous success of the Standard Model.

Get your camera out! Or maybe not!

The Standard Model

The Standard Model of particle physics is a framework based on very fundamental principles of physics. It describes the interaction between different particles and the three forces electromagnetism, weak and strong. Although there are a number of freely adjustable parameters, the Standard Model has been the most successful theory of physics ever. The progress of physics in this direction has been extremely rapid, especially in the 1950’s to the 1990’s. Each of the particles predicted by the Standard Model has been detected, giving both theorists and experimentalists enormous confidence that this is the correct model. Theory has always been immediately confirmed by experiments, and they have invariably confirmed the Standard Model predictions! All that remains is finding the Higgs and this one last piece is playing hard-to-get.


Many physicists are tensed about the prospect of there being no Higgs! Many others, among them notably Nobel Prize winner Steven Weinberg, feels that it would be exciting if the Standard Model Higgs is not found! There are many alternative models and these would then gain center stage.

All in all, it is safe to say that this one announcement may be the fork in the path for physics going forward. Higgs or no Higgs – that is the question. The answer comes on the 13th!

A 125-126 GeV peak for the Higgs? Tantalizing:  http://techie-buzz.com/science/higgs-discovery-rumours.html

Higgs Search At LHC Nears End – Has The Higgs Already Been Found?

The Higgs Boson may have finally have been caught or, may be, not! Only a clutch of scientists with direct access to latest LHC data knows whether the Higgs has been found or not! Whatever the result be, one thing is for sure the Higgs hunt is nearly over. CERN researchers have restricted the Higgs mass to a window of only 30 GeV, taking into results from the Large Electron Positron (LEP) collider, the Tevatron and, of course, from the LHC itself.

A simulated Higgs event at LHC

The Higgs, if present in Nature, has got extremely little energy space to hide in. At a conference in Paris, held today (18th November), ATLAS and CMS researchers got together and erased out a HUGE range for the possible mass of the Higgs. A large swathe from 141 to 476 GeV was wiped out in one fell swoop. Says Guido Tonelli, the spokesman for CMS

We’ll know the outcome within weeks.

This is surely going to increase the pulse rate of any particle physicist in the world.

The mass range as it looks now (Courtesy: Nature)

What if…

What happens if the Higgs is not found? A lot of problems for the Standard Model. The Higgs boson is the simplest way to generate masses for fermions (like electrons and protons) and bosons (like W and Z bosons). There are other possibilities, but this one Higgs model is the simplest and most beautiful of all the possible models. However, as Feynman would say, if theory disagrees with experiment, then it’s wrong and it doesn’t matter how beautiful the theory might be.

For long, has the Higgs mass been pinned at about 140 GeV. There is still a strong possibility that the Higgs, if found, will be of this mass. We may be on the brink of history.

More Info:  http://www.nature.com/news/higgs-hunt-enters-endgame-1.9399