Tuesday evening lecture with Stan Bentvelsen

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Tuesday evening lecture with Stan Bentvelsen
The observation of the Higgs particle
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Professor Stan Bentvelsen is programme leader of the FOM programme 'Exploration of new phenomena at the highest energy frontier with D0 and ATLAS' at Nikhef and is closely involved in the Higgs research at CERN. Bentvelsen studied Theoretical Physics at the University of Amsterdam and completed his PhD cum laude in experimental high-energy physics there in 1994. From 1994 until 2000 he was a staff researcher at CERN in Geneva. He then became a senior scientist at FOM-Nikhef. Since 2005 he has been Professor of 'Collider physics at the LHC' at the University of Amsterdam and programme leader at FOM. Bentvelsen is also a member of the FOM Governing Board.
Keywords higgs particle
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the big question is we have to particles denied the glass is it's half-empty where are full and style themselves a little soul about the move onto way to a 2nd particles that I like to work presented you I'm very happy that I am able here to work presented you dissolves that the obtained a and with our detected the others detector um and I'll be speaking on behalf of our other schools and what you see here on the cover is is the golf the observation of the 6 particle and put some pressure there because we are not so sure maybe as the previous speaker at the system the department at the world looking for but the evidence that was also alluded to is indeed something which system um close to 6 sigma fight and the but I think there is any indeed play a completely different kind of game and this is indeed lots of science and last year we were celebrating the 20th birthday all of the others compilation and imagine that you have to have division in 1992 to make the letter of intent for others it was approved by the Council of certain in 1994 we started installing some 10 years ago or so and that it was done in 2 0 0 8 and then needed to beta and I'd like to share with you some of the things that we saw in that data but before doing that I also like to presented the group of people from the Netherlands that are involved in this kind of research and highly experimental particle physics is the work I'm here on behalf of my team but the year people that I that really doing the hard work I would like to refer to the 2 2 more sessions focused session takes into focus and the palaces and subatomic physics because there you can hear all the details and all the negativity kind of hard work that has been going on in order to achieve this this fact so we are compilation of the maker of some of that about University and the University of Amsterdam so let's start by doing some particle physics and part of physics I mean particles without any sites without any form factor without just point like particles that can be described by mathematical points and you have to dive deep inside the the the nuclear to to encounter the clock here the up and down Sarkozy Romo and the lentils Latino and the electoral the bills are not the only particles that we know of because in the end last many years decades also it's also accelerated we know that this has to be extended by buying a new families of particles that have been discovered over the years for example the charm and the strains in the top and bottom the toll was only discovered in 1995 at the Tevatron in Chicago and that the was only made visible 5 years later sold the side and the basic constituents also of matter is interesting but may be much more interesting is how they interact with each other and their we know that there are 4 fundamental forces playing out of all and then in physics have listed them hear from you before you electromagnetism weak interactions so interactions and reputation and over 2 years ago and we have a created um quantum few cities to in order to describe them and for example 1948 by firemen and others not singer menace to down the quantum field theory of electromagnetism right you see that the messenger for the force is the fault of no known much later also the strong interaction was made in the pontiff you'll the goal also Marsalis is mediating the stone interactions but that action pose more problems and that it was only in in 1967 a soda glass house by Americans managed to lie down with the discovery in Mongol electromagnetism and the weak interactions by introducing the W and Z bosons W and bosons they're not so light they are actually pretty massive 1891 times supposed to Monticello and them and that caused the problems the vote was apparently sold now let me 1st um discussed with you that this dismal is actually the standard calling the standard knowledge you can write it down on a cup of tea and and it's very elegantly summarizes all these very fundamental forces based facilities on on Gates inventories and then look at the mall was made consistent around 97 to your soul and uh by the realization program also help monitors health and they have were awarded the Nobel Prize in 1999 and the when they were doing .period from their utilization program they discovered that they can that can easily be done not easily but could be done for massless particles but not for the massive particles so the WTC boast being massive were causing problems but then and it was noted that the some of variability 1964 and another way over dynamically generating Moss was on the market to the described by police as far as I know there and that was about and that was put in the standard model in order to give the W's and as bosons announced also the defendants later on actually must end by the discovery of the z the W bosons in 1983 um uh that standard model as it was then called was made into a big success and also there was a prize given to adults quality questions from the media and also got so what is the this Hicks idea the idea is there but I told this based on the on the symmetries and the idea is that you need the gates symmetry in order to preserve the normalization and article in an unbroken phase with an unbroken somatic face the bottles cannot have a mosque and that would mean that they would move with the speed of light every particle that we know of in empty factory but the idea is that on the air in the Balkan faith in the vacuum there can exist in the fields of the Higgs field here and it is realized by somewhat lazy kind of of background field and particles to actually into action with this back on and bite interacting with his background field the act effectively apply remarks among particle is injecting a bit stronger with this background fewer than the other 1 and thereby effectively applying an different Marston you want some answers are described on a completely different way monsters are described as interactions interactions with and only presents a picture of you but in order to see if this description makes sense because here you have now a description rivets you can solve the problems of renormalization instead model
but um uh the consequence of this description is that also the vacuum itself can fluctuate and that this is in the smoking gun for this whole description which means that there is an expectation of this vacuum field and his article the particles and the Higgs particle is actually the only particle because it's a skater it's a bozo that does have a mosque in in the standard model but the trouble is that don't know the margin predicted by the sudden means that you basically have to look everywhere in order to see if this whole picture that represent here does make sense or not so in order to do that and you well aware that it was also alluded to appease the already have this magnificent accelerated being constructed many years ago already With 27 in circumference and and at the Baker um detectors and visualizing and detecting the collisions the other less detector and the counterparts this year actor because we do want to be pretty sure if we have a measurement that it's also measured independently by an independent group of scientists in our case the CMS people and I said to big challenges in the construction of this all this accelerated the 1st challenge is really to get ultimate height energy in order to create a heavy new residences that heavy particles and indeed it's in the TV James um the design 7 thousand to 7 thousand the Bolton to Paulden collisions In order to do so you have to really keep the particles in their and a circular path and therefore you need to magnets and there he is the 1 of the dipole magnets that is doing that 1 of the year 1234 dipole magnets that our installs in the accelerator it'll be order pulled to employ 9 Calvin with the liquid to helium and they ultimately give a magnetic field also at points in the 10th line to eventually debates monster over the years helium supply all 4 of the whole world is actually in this machine and a here you see on the other side downside you see added the 2 little holes something like 5 centimeters in diameter them along with the magnetic field doorknob word yellow 1 with a magnetic field going downward to sold out to the Balkans can now move in opposite directions to those so it's of these tubes and them then comes the 2nd challenge and a 2nd chance is merely to get an awful lot of collisions and people that luminosity dividers of the been the amount of collisions that said that he like to observe the you have to imagine that if you collide to Paul had all the chances of actually producing Hicks particle there it's 10 orders of magnitude below having a cross-section of all so is really looking for a needle in something like 10 million haystacks something and so in order to increase in the luminosity um uh the particles are actually accelerated in bunches is bonds consisting of 10 to 11 protons the bonds is followed by another bonds some 50 nanoseconds or something like 60 meters or so further down and so in this proceeding altering of bounces are going clockwise and altering of bonds going anti-clockwise and the bunches of football they actually very um um go past each other having a chance of a potent to inform on Bonds hitting a potent of the other bonds and the rest continuing to make a new chance in the next round show but you do when you operate system is seeing its you operated 24 hours 7 days a week between March and December it means you have to fill in missing at low energy at injection energy uh you have to and that up to to the energy of the high ultimate energy you start the collisions and that is is a stable configuration of something like 10 hours or so another 10 hours do you might be due to the intensity of beans has deviated a little bit due to the lifetime deposits it's just disappear and annually cycle and the recycling dates typically a few hours in the newly started the operation again and and all the time and the others detectors taking data taken collisions and whenever LHC gives you a call saying they listen we have a stable being here and there um so what about what you're doing and is looking at the end of the day individual collisions between protons but politicians are of course a bill out of fulfills boxes and bottles and the interesting physics that's the year obtained here isn't actually to park or to the bottom of this potent make the pollution that makes the heart condition where some new physics is itself year happening you see on the right side of the pool to read the time goes to the right and how we visualize the 2 proteins um hating each other producing new physics you have to detect the decay products of the collision and for that be build the Atlas detector and here you see a part of the others detective with the beam of a perpendicular his perpendicular to the beam piped into impact that the downside of this picture and like onion rings and various sub detectors subsequently putting 1 after the other so in the very heart of the detector you find detecting chambers which are measuring the the direction and the momentum of the charged particles because they're Bennett in a magnetic field than the kilometres were stalled the particles like electrons and photons in order to measure the energy and then there's 1 particular particle the mule 2 other times as heavy as an electoral basically that is able to penetrate protocol in meters and hitting and a very outside of the detector the Muenster must now this is says simulate what is a picture of the others attacked you have to mention 44 meters long and 22 meters high detector where you see here assimilation of area of an event is not that he didn't and the and what they did the and office of knickers in this project it's both industry instrumentation in R for developing new ways of detecting particles in the we are heavily involved in electronica and the calibration uh now we are heavily involved in the analysis in the Solver development in the computing etc. so that's all bonds of activities that he actually doing in this detector and if you make it more complete it means that we have built part of the Muallem position chambers we have uh uh the active toys from the industry we have and semiconducting track and kept and made it clear in Amsterdam and put it downstairs in Geneva vaulted the ticket and the data acquisition attacking and injuring an analysis visor involved in the supersymmetry researchers Hicks physics as I will tell you about mental part so um 10 years ago or so we were in the face that it could be the end of the year the cavern and start building this thing and
here is a very big movie on that discovery the
sieges about always being built up that part of the the immune system and that at the very characteristic of you will be out of the director of the you
inside the loneliness of being installed and there is some movement set up and out of the room to cook everything together he is he the following made inside the uh the magnitude of the pudding so that's quite a lot um effort that also as told you it may after we have done that I asked are not only fair share but at the trial which you see some impression on the year on the people that have been doing that for some sometime and I couldn't resist showing the support of then go with 1 of our is the students that actually installing 1 of the calibration systems for the for the new chamber so at the moment .period in 2008 also said that the detector and seem all done and then we had famous discovery of that group had so if he had no difficulty it is a disaster I have 1 of the nicest fisheries actually did the tools to use a long dipole magnets they are joined up by um by electromechanical by by elected joint here and there it there's something went along and there was a spot developing and sparked a actually started to blow up or meltdown part of the pirated liquid helium was in liquid helium started to escape and was of oppression base inside the collided itself as something like 400 meters the of the accelerated the story and it took us a year or so to recover from this some 100 dipole magnets really effective affected by this but incident that means that after a year when we were fully covered um galaxy is not planning and design energy of 7 thousand it's easy to be that half of its energy the enough thousand and in this year pursuant to president of 4 thousand and that we will be stopping at a program next month in order to work in a Seoul safety valves and to make more adjustments in order to decide of the scene at the end of 2014 with full energy so we're going in the shutdown period for well nevertheless 2011 it was extremely successful the year the year of the expectations for the luminosity were exceeded by a factor of 5 or so and again last year in 2012 the luminosity was exceeded by by expectations it means that in total we have something now like the 1 . 8 times tends to the 15 collisions and um fueled by the year others detective uh the detector did did an excellent was performing excellently taking efficiencies of 294 cent 96 per cent of the terms operation these all the things that need to be did you get the details that we are worrying about and that's what makes this so successful and and and look at the has environments here you see uh actually an overlapping uh uh uh advanced costing I was telling you that in the months costing you have a chance of on alternating another plot on the day that is actually not the case at all here you see overlapping 20 politicians or 27 collisions among bonds courses and 1 of them is actually doing some interesting physics in 1 of them is the boson is being produced but now you have to figure out what it is and you have to get rid of the the so what we do when we analyze our data is the following me on something like 10 to 20 million collisions 2nd this is a diesel observing the others detector uh we have an online trading system which spits out at of 600 1st events that are selected by 1 of the many many taken menus over thousand figure possibilities that we have and that means that we are restoring something like a gigabyte of data per 2nd this data is then spread out all over the world in the 10 centers 1 of them being assigned and make efforts in Amsterdam and um and so that he can then look at the data from there and do our analysis and this is what the PC students typically are doing when they make the analysis had here's an example this actually quite acute example because you see in the detector you see the other was attacked as it told you do you won't stay of penetrating goal coming at the completely out of the detector so these exotic presented by the headlines in this in this event is that this is a yield data and as you see that the 2 Muenster actually are a signature Fawzi bows on so here's the Zeballos on producer was to see if you can play the master of the 2 new ones you actually get a mastery close to the sea Bozo and sold the observation but I'm not so interested in the bosons we noted that the Rosen is there and we have found it back but you want to look for the particle now so here is the status of of the it's uh uh particle before we started to doing collisions on the line below you see somewhere between 0 and 5 from the Jedi uh they're listed in games in which he expects Higgs particle to exist indicating the mother the ball to the minds of the W bows on the gold atoms and also that had area and the area which has been excluded too ready before Alex started of 214 TV yourself so um menu making expired Missouri when you search for Hicks particles you 1st have to produce Hicks particles it's there now the prediction with the data the 2012 is said depending on its mast which we don't know something like 200 thousand 177 thousand of those Hicks particles of interest to the 18 million collisions once you have created 1 that doesn't exist for a long time and actually the case and that it has raised possibilities of decaying so 1 of the promising Golden channels is decay told to particles that subsequently became for left see here on the bottom side you see sensitivity of this channel as a function of the Hicks must so if it's summer in the blue curve on the rule line we will be sure that you find particle if it has a master's in that area that's not the only channel and other possibilities Higgs decays into 2 photos and you
see that a completely different sensitivity exceed what call sensitivity around 114 on intent yourself and then a 3rd channel which Israel makes the occasion to 2 W bosons decaying into 2 letters and there's a bit of a problem because the W's also detained to Latinos and that you cannot measure so we resident only through missing energy nicely also the maker flak 48 channels that we have put an emphasis on within our group sold the naming and Lopez very active for examples were next to the W W and as well and now In the 1st round of data in 2011 we were able to exclude the existence of the 6 particle for a very long chains of it's possible must be forced out of somewhere between 141 up to something like 472 you renewal from the data edited to fit in 2011 that it was not there so that leaves only a tiny gap let's say a meeting hundreds of 1441 to see if there is a new particles now here's an example of a display where you see Hicks to a W W going to 2 in this case and electron and a new 1 and 2 Latinos which you cannot see so that this political missing energy and from here you have to pick a fight back the kinematics in order to see if you can find that states must not carry much more straightforward is rendered is the decaying into to the bosons and to boson and subsequently 2 2 4 electrons of Formula One's and you see a beautiful example actually of a collision ready to see for those new ones in the final state and and video calculating the amount of this of Formula One's you will find that this adds up to 125 went on TV and but this on events and that's not a significant enough that you can imagine but we found out is not alone where you have again all those belongs in in the final state and it's in this case the demands of the year Formula One's at up 224 . 6 G's yourself so having having all this data in your hands you start to make distributions of course you know that we have looking in a certain window for masters so um uh here is then the plot a of the invariant master on the horizontal axis of the 4 leftovers I gave it to examples and here's the plot that is covering the range between 0 and 250 g and then what we do is the blind data 1st not in order to work to work and has to be too biased so what you see here is the blinded data um them before combining them to you but you see here is that the data itself and had his cigar and that you see based on our calculations that mediates um very also have formulated a final set of 4 letters I should say in the final state but I dare not coming from the Higgs particle they the background so this is a beckons for continuous Azizi background and you see some sort of the firemen diagram on the told there which it shows you that you can't have also contributions there's no picture of all involved in the game but you still have the same signature in new detector so you have to disentangle the 2 and they're gone .period started to unwind and then a lower boldly found something which you can say is a small signal and the significance of the . 6 sigma conceded that it basically consists of something like 11 events that are above the red background which is beautician significantly . 6 seconds but we couldn't claim a discovery we were looking also at other channels here is a channel that you have a Higgs decaying into 2 of these photons and useful tools they are um don't carry any charge so what they do is they leave their signature in the colony that these are the yellow blobs that you see in this in this event display and the head of the severe the circles and what you see is that the yellow blobs you can measure the energy of the photons by this absorption in the and because you know the direction you can calculate the event must again and what you find this year amounts of 126 Gigi This is not a toll to reveal because there are many processes that also leads to a twofold in the final state the backhand again and there are basically 2 important Razorback of fake photos for example a pioneer in order pioneers 0 can into 2 photos that are very convenient and it's not so easy to disentangle the upon default on former from a decaying pine also you have photos again not from Maddox said the case is a showing that in the poll tear down below so effectively what you do it if you calculate the event miles the whole set you get a distribution like this and you see that it is a completely different behavior that was about as show before and through form you once but again as a function of the year Hicks must you see our continue but I'm really looking for peace here and indeed if you had the continuum and subtracted from from the observation you see little peak here with the significance of something like 4 of Sigma yeah you can combine all this information that this on and the previous channels and then at some point you work can calculate the data's significance for its margin this is the situation of July 4th in 2012 we see today the significance as a function of the Hicks Mast Holdings between 110 Jedi to 5 from something DVD uh the PCO value I think you know that um um and you see a dip their at riches a heating something like 6 sigma and the date means that you cannot describe the data without having anything anything new in it and this is what even ,comma discovered 5 stigma but by claiming toast a the discovery we also have to look at our friends from the same escalation and on that date you're extremely media duties to what they were showing and indeed there were also having at the very same sport 126 were you significance of 5 Sigma so that led to this
to this observation officer and director general of Gaza
go much you will
to really the group Wolseley movements of the mood was lifted in history I LPG a little bit that he was completely cured I'm flabbergasted by the fact that the founders of particles so soon and also In in the Netherlands we have .period we had our fair share of celebrating and we have to sign the deal was me obviously didn't do much for and so what happened since July the 4th not a question is is it the standard model makes me now in the interfacing in which the early and very much detail um um going to find if if the predictions of the Standard Model once we know the mosques are actually valid so what you see here is appalled this difficulty maybe because you see the different decay channels and Hicks to cover government is easy and and the expectation from the standard model is given by the vertical line and you see that the data is not on the vertical line and very nicely sold via now in an intermediate states like this is something that we don't understand or do we just need more collisions I realize that have something like two-thirds of the total dataset on blinded so we still have a new data on the shelves that we haven't looked at something else very intriguing but we found actually not so long ago is if you look at the Masters of the Higgs particle when decays to to follow order must of the 6 particle and in the case of 4 letters we don't find the same aspect and a demands differences something like the the analogy to win something Sigma um is significant enough to claim that maybe we are not dealing with the simple style and although Hicks something more complex we don't know yet but this is clearly something that's a forestry need more data I think that this this discovery is actually 1 of the most important discoveries in particle physics for the last 42 years yourself we have definitely observed a particle but if it's really hates the don't know completely for sure yet but In the whole LHC program imagine that only 1 per cent of the data has been delivered at this moment the problem continues for many more years to come in the near future yet the energies of the double bill doing in the ethnic studies we'll search for beyond the standard model physics and in the far future Congresses to where it go for very high luminosity is reality and maybe doing high-precision physics in the plus minus collided so that leads me to my very last and I think that this discovered it was really a major leap in understanding with our new questions that are now getting a very urgent that really has to find out more about a quantum numbers of the particles on a more Higgs particles or under any other particles is at elementary wasn't the composite how does a couple to itself and and that what we also don't know because it's a scalar particle well-executed must former being at the Planck scale and there's all there is a whole connection to cosmology and there maybe it's nice to Cloverfield momma always use telling in his lectures on the Onyx physics you know you have this huge vacuum and it takes few this also contains energy and if you start calculating and uh modesty curvature of this set of this effect of be having energy in our universe it will mean that the universe would at to the size of a football and then a it clearly means that the lack of understanding of what's really going on that is the fundamental so the room into