James Smallcombe: And so on. So now hand over and so please come in the bag of work.
skyler degenkolb: Wonderful, thank you, James, both for the kind introduction and for the invitation in the first place. It's always fun to talk to people from different backgrounds and
skyler degenkolb: With that in mind, I would encourage anyone who has a question to feel free to interrupt me as I go along. Because that's that's often a better way to get information across than to
skyler degenkolb: Wait until the end while I talk and everyone's just confused. So I will talk about searches for permanent electric dipole moments.
skyler degenkolb: This is a big field and I was a little over ambitious in the scope. Did I announced an abstract, so I will shamelessly tell you that I cherry picked some things that I think are particularly interesting but this is in no way a complete treatment and I'll try to provide references to
skyler degenkolb: publications and presentations, which may fill in some of the gaps. So, one of the nice things actually about this present moment.
skyler degenkolb: Is that there are a lot of online presentations, which you can go and watch of which this will only be one and I encourage you to follow up other people in the field who will talk about particular systems with much more nuanced and authority that I can
skyler degenkolb: This is global. This is actually where I'm sitting now as opposed to the usual situation I'm showing you this. I'm sure in a
skyler degenkolb: Room where would you share with me.
skyler degenkolb: The IO is this little cylindrical building. And when you look down into the research reactor
skyler degenkolb: You see chunk of radiation. So I feel like it's it's maybe worth a minute to just introduce this context, because as it turns out, most
skyler degenkolb: Nuclear Physics does not take place reactor isn't most physics that takes place reactors is not nuclear physics but nuclear and particle physics is a minority.
skyler degenkolb: Component a significant one but maybe 10% of the scientific output produced a di LL, and we have a small group with four or five public instruments in nuclear and particle physics of which you see on production and EDM searches are relatively low represented
skyler degenkolb: So before diving into the scientific and meat of the presentation. I also want to illustrate some of the orders of magnitude and units which are commonly thrown around in this field. This is unique, as far as I know, too low energy preserving metrology and
skyler degenkolb: In terms of frequency scale, the numbers that we talked about stem from nano hurts and below up two kilo hertz and
skyler degenkolb: A unit of electronic charge time centimeters has been kind of chosen by the field that as a way to represent the size of an electric dipole moment.
skyler degenkolb: Current experiments are using that unit with pre factor of 10 to the minus 26 or so, a more natural choice might have been
skyler degenkolb: The family when you talk about a neutron or a proton, but we'll just leave that 13 order of magnitude lover run in there, by convention.
skyler degenkolb: And when you apply a relatively large laboratory electric fields to a dipole moment of that strength and cast it and frequency units you come out with
skyler degenkolb: A few non efforts. And then the other frequencies scales that I've, I've listed below that.
skyler degenkolb: Are not randomly chosen, these are actually things which matter in the experiments so 11.6 microclimates is the frequency of the earth daily rotation.
skyler degenkolb: And that's something that we have to correct for because when you do spend procession measurements to a sufficient level of precision. It is a systematic shift. And it's a big one. When you're trying to measure 24 not
skyler degenkolb: A million Hertz is an even bigger number and it comes along in a different way. So that happened to be the frequency of
skyler degenkolb: The subway train in Munich, when we were doing an electric shock experiment with polarized xenon there at the Technical University.
skyler degenkolb: Over the last several years before to Berlin and then we use the magnetic moments of nucleus and electrons themselves.
skyler degenkolb: In order to measure magnetic fields and correct free systematics and those are separated by a factor.
skyler degenkolb: Of 2000 or so. So that brings us into the Hertz and kilo hertz regimes respectively for magnetic fields of about one micro Tesla, which is a typical value.
skyler degenkolb: In these experiments and then specifically for ultra called neutrons. I will introduce the unit of the nano electron volts. So going in the other direction from the base unit. The nuclear physicists are
skyler degenkolb: Commonly prepared to do and this is a unit which comes up in all of the major interactions of ultra called neutrons with standard model stuff. So if you raise
skyler degenkolb: A neutron, which has a massive about a GED proceed squared by one centimeter in Earth's gravity. That's a potential energy, again, of one evening. Similarly, magnetic fields.
skyler degenkolb: Entered the same scale. And one of the fascinating things about electrical neutrons, is that you can use all of the different standard model.
skyler degenkolb: ways of manipulating things so magnetic fields gravity. The week decay process and there they have a similar strength as far as the neutron was concerned.
skyler degenkolb: And then just to list some of the most recent experimental results from the field of searching for permanent electric dipole moments.
skyler degenkolb: The neutron the xenon 129 nuclear EDM in the context of a neutral Adam and the parent magnetic thorium oxide molecule which is commonly interpreted as a bound on the electron EDM. These are all at the level of 10 to the minus 26 or better in the standard units.
skyler degenkolb: So let's motivate this a little bit. Very broadly speaking, you can customize division to search for permanent electric moments in a number of ways. But they all connect back to precision tests of the standard model.
skyler degenkolb: Or searches for CP violation beyond it. I was a little bit deliberately provocative with my abstract because I said that the standard model predictions cannot be tested and that EDM searches test the standard model so
skyler degenkolb: We'll go into a bit more detail later about how that works. But basically, there were three parameters. There's a free parameter in the standard model.
skyler degenkolb: Which could be much bigger than zero and it appears to be very, very close to zero at least as close as we can better
skyler degenkolb: And that's very strange, but it's idioms that tell us that it shakes out that way. And if it weren't for Ed measurements, then that would be a potential sources CP violation that observation of how much baryonic matter of the universe contends tell us we need anyway.
skyler degenkolb: So this is the second major motivation that connection to deep questions about symmetry breaking, and the origin of the very hundred symmetry.
skyler degenkolb: We know from looking at the universe that it contains more matter than anti matter at the level of about a partner intend to return. But that's far too much for the CP violation that we know would be needed.
skyler degenkolb: To produce it as compared to what's actually been observed in the standard model. And so we need new sources of CP violation.
skyler degenkolb: And EDM is not only test that. But they provide a particularly clean signature of time reversal violation without issues of funnel stick corrections that are commonly
skyler degenkolb: Difficult in interpreting the results of other classes of experiments.
skyler degenkolb: So very broadly speaking, if you want to search for new physics and sci fi violating physics in particular, you can look in this two dimensional parameter space that I'm borrowing from
skyler degenkolb: Vicenza Giuliano. This is one of the online talks that I would really encourage you to go and look at
skyler degenkolb: But it's a common conceptualization you have energy scale and variant massive one axis and coupling the strength on the other.
skyler degenkolb: Basically, you can go to colliders and try to directly exciting two degrees of freedom that we haven't seen yet.
skyler degenkolb: And high invariant mass or you can go to high intensity and look for the signature of a much weaker physics either virtual particles that don't occur as external legs.
skyler degenkolb: Or very light very weakly couple degrees degrees of freedom that may be directly excited. I would prefer to cast this in terms of precision rather than intensity, because often
skyler degenkolb: Statistical reach of the selected experimental systems doesn't necessarily justify the notion of a large number of particles, but that's a little bit of a technical point
skyler degenkolb: And then there are many places that you can look for more details on particular system. So what is an idiom.
skyler degenkolb: It's of course a dipole moment and I showed this picture for years before I realized that it has typos in it. And so this
skyler degenkolb: non relativistic Hamiltonian is a very simple thing. But when you write it down and start throwing pictures, it's, it's easy to confuse yourself and forget that parody operates and all three special axes in two dimensional representations of this
skyler degenkolb: Are almost necessarily misleading. So I would encourage you all to just write down the Hamiltonian as the list.
skyler degenkolb: Goes on the other hand, the classical moments are a good way to look at this, so you can produce
skyler degenkolb: An expansion of electrostatic or magnetic potential and multiple moments by integrating various powers position coordinates against the source distributions.
skyler degenkolb: And this produces moments of source distributions, if you like, which are defined in the following ways correspond rather directly to objects.
skyler degenkolb: In quantum field theory where we write down the matrix elements for an electromagnetic for me on current and this is parameter is
skyler degenkolb: For the momentum transfer in terms of fun factors and is fun factors correspond directly to the electromagnetic charge. So that's one that electric dipole
skyler degenkolb: F3 corresponds to the classical moment here mu is the magnetic moment. And this little a, is something which only occurs in relativistic electrodynamics. That's the so called so
skyler degenkolb: Unimportant I mentor a tutorial courage which circulates inside the nucleus. And there's also a poverty violating if
skyler degenkolb: There were a lot of different EDM techniques and a lot of different ways of measuring them, but you can conceptually divide them and just three broad classes each. So the pair of magnetic systems like these.
skyler degenkolb: Mainly the electron electric dipole moment and Skylar electron nucleus of corruption that Diane magnetic systems for nuclear on couplings. The neutron EDM.
skyler degenkolb: And QC d theta parameter and then particle systems, it depends on which particle, it is, but in all of these you can experimentally, put them in traps, you can
skyler degenkolb: Produce atomic molecular or particle beams and if they have charge, such as even molecular ions, you can put them in storage rings. And so there is an enormously broad parameter space of
skyler degenkolb: Approaches and primary sensitivities, which has just led to an explosion in the number of experiments that are currently active in the world. And it's not even
skyler degenkolb: remotely possible to survey them all now. So I'm going to cherry pick the ones that I've actually worked on, namely the neutron and xenon 129 to tell you a little bit about
skyler degenkolb: Later, it's interesting. Also to note that there is sort of a gap in the charts and there's no fundamental reasons for this, but it's easy to understand.
skyler degenkolb: That if you want to put something in the store during it needs a charge. And if you make an eye on by taking away electrons and
skyler degenkolb: In most cases, you end up with on parent electrons and see your dynamic. The next thing is no longer dynamic, so you'd have to dedicated way she was something where the charge balances out correctly with the electron
skyler degenkolb: And then even beyond this chart. There are many other things that people think about recently radioactive and polyatomic molecules have come up as hot topics but barely talk about those at all.
skyler degenkolb: So most people have heard of molecular electric dipole moments, not necessarily add ons are they different
skyler degenkolb: Let's look at on a Monday molecule. So let's put it in the vibrational ground state.
skyler degenkolb: That positive electric charge tends to collect around the hydrogen atoms because the electronic migrate from the nitrogen. This is an electric dipole moment is it an idiom. Well, no or yes it's different than
skyler degenkolb: These are symmetry again states, if you like, but they are not energy. I can states energy. I can states or liens and when you do your standard quantum mechanics, you can
skyler degenkolb: Represent the effect of the electric field into limits where it's very weak or very strong respectively. And essentially, this part.
skyler degenkolb: Where you have a linear dipole shift occurs when the molecule is fully polarized. Otherwise, you have an E squared shift, which is the signature of an induced dipole
skyler degenkolb: Not a fundamental one. So, before the molecule polarizes you have this quadratic dependence and then by the time it looks like an Ed Young. It's not because it's a fundamental permanent
skyler degenkolb: Dipole moment is because the molecule is polarized as it can be molecules are very polarized. So this is actually something which is quite easy to see.
skyler degenkolb: Adams and nuclei are much less polarized and the neutron, for example, is even less polarized than by several orders of magnitude.
skyler degenkolb: And so this can be experiment, an experimental important detail in atomic and molecular systems, but it's it's important to recognize that
skyler degenkolb: The unit of one Dubai from a molecular physics is about to 10 to the minus nine in a centimeter units and it's a fundamentally different thing, which has nothing to do with basic symmetries, if you like.
skyler degenkolb: An EDM can also be thought of as arising from polarization physics, but it's induced at the most fundamental level by some CPU violet and process. And that's what generates a polarization moment. So again, the symmetry character is different.
skyler degenkolb: In a look around June for for me on which has magnetic and electric dipole moments.
skyler degenkolb: You write it down like this and I'll just share this briefly before giving you the non relativistic Hamiltonian again because it's clear here. The iron front tells you this violates time reversal symmetry t
skyler degenkolb: And the gamma five tells you that it violates parody. And if you assume the CPT serum as you're more or less forced to do for quantum field theory is that respect local the rents of variance
skyler degenkolb: Then violation of P in violation of tea implies three conservation of CPT violation of CP, and this is why Idioms are frequently presented as being
skyler degenkolb: prob of CP violation in reality or a more direct prob of tea violation, but within the context of testing the standard model and searching for
skyler degenkolb: New physics directly beyond it CPI Alicia has a good proxy for that.
skyler degenkolb: In the non relativistic case, you have a very simple Hamiltonian. There's a linear energy shift from playing a magnetic field do the magnetic dipole moments and similarly for the electric field. It's the same character.
skyler degenkolb: In the red zone if you turn the up, then you have a linear exam on splitting between spin up and spin down for it's been one half particle
skyler degenkolb: And if you turn on an airfield. On top of that, then so little bit tricky to draw four lines for two states system, but okay. If the fields of parallel or anti parallel
skyler degenkolb: That it makes a difference whether these two energy shifts together or subtract from each other.
skyler degenkolb: And if you do both experiments, that is to say if you measure both of these energy splints, then you can combine them, get rid of the tomb UB
skyler degenkolb: And focus only on the D E interaction that you actually want to care about you know the value of the electric field because you've applied it in a laboratory
skyler degenkolb: And then you can find out what the moment is a couple of very bright atomic physicists following and other Nobel laureate actually all three of these guys won Nobel Prizes.
skyler degenkolb: Pointed out that a precision measurements or they seem to have lost my
skyler degenkolb: Slides.
skyler degenkolb: Let's try this again.
skyler degenkolb: Cornell and Wyman
skyler degenkolb: Pointed out that you should measure things as frequencies. If you want to do precision measurements.
skyler degenkolb: This working. Can someone tell me
James Smallcombe: I can't see.
skyler degenkolb: The slides.
Now,
James Smallcombe: should still be enabled. Yep.
James Smallcombe: Yeah, I have a slide one but that's showing
skyler degenkolb: Yeah, we'll find the relevance.
skyler degenkolb: precision measurements are
skyler degenkolb: Almost necessarily frequency measurements, because there is no fundamental bottom. The next to the sensitivity, you can just continue measuring as long as you understand your system.
skyler degenkolb: And so if you want to do with precision measurements, then your best bet is to find a way to measure this and you're interested in
skyler degenkolb: And the way that we do that here is to use energy time uncertainty and measure frequency which is directly proportional to the linear energy shift from D.
skyler degenkolb: In practice,
skyler degenkolb: There were other parameters that matter, of course. So not only the size of the electric field you apply, but the signal to noise of your system and the coherence time it's let's in a couple of different directions. Determine depending on whether you're more limited by
skyler degenkolb: Shopping wiser phase notice or drifter fluctuations differently differently.
skyler degenkolb: But at the end of the day, you'll notice all of these sensitivity equations have a number of experimental parameters in the denominator and the experimentalists job is to maximize those to the greatest extent possible, in order to push down the sensitivity on the electric
skyler degenkolb: So,
skyler degenkolb: How can we measure an EDM as a frequency in practice we can polarize a system of magnetic dipole moments as well as an EDM. And then we let it evolve in time.
skyler degenkolb: First we apply, apply every to pulse and the magnetic field forces spin to process and then we apply a second pi over to pulse after relate the phase of all for some finite time
skyler degenkolb: The pulse structure looks like this. And this is simply the technique invented by Norman Ramsey to originally measure
skyler degenkolb: Nuclear moments in molecular beans and did this initially established the technique and did the experiment, both in 1950 but the result was not published.
skyler degenkolb: Until 1957 for the neutron because we hadn't discovered already violation until them.
skyler degenkolb: And this. This is a figure from the 1957 paper, the frequency of this is hard to read but this is eating kilohertz. And the range from left to right, is something like 100 words.
skyler degenkolb: This year, there is a new measurement of the neutron electric dipole moment. And this is also a central interference, French, but the frequency access is knowing Millie hurts and from left to right, you have for millions so
skyler degenkolb: Since 1957 until 2022 there is, there's been a substantial many order of magnitude progress in doing these types of frequency measurements I precision and we're still essentially using the same time.
skyler degenkolb: Unfortunately, there's a conceptual Hiccup, and that is that when you have a system of electric charges and you put them in an electric fields. They're bound together so that they don't just accelerate off in all directions.
skyler degenkolb: That will displace each other in such a way that it exactly councils any permanent electric dipole moment of the constituents and that means that the EDM is not observable. So this is a result did a shift in
skyler degenkolb: 1963 and I believe john angle came up with the formulation that I'm showing you here. So let's take
skyler degenkolb: Bear Hamiltonian p squared over to M plus on electromagnetic potential and we'll add the idioms as a perturbations. This is a
skyler degenkolb: Constituent idioms of all components in the main Hamiltonian and now we added as a prohibition. So, d e gradient of a potential gradient operator is just the same thing as a momentum operator up to factors of each bar.
skyler degenkolb: That's very simple. We cannot calculate what happens to the ground state and the ground state goes to a new ground state where the energy has shifted
skyler degenkolb: By the matrix elements of this prohibition weighted by effects to each state and the spectrum. And so, okay, this is a complete set of states, you now have
skyler degenkolb: Your new ground state in terms of your old grandson. Fine. Let's calculate what the observable dipole moment is because it's not just the EDM, or is the sum of die polls.
skyler degenkolb: Due to the fact that the charges occupied different positions and when you add these together and you re express this new ground state in terms of the old one you dear algebra you come up with this computer.
skyler degenkolb: And the computer is just the commentator of our empty because he is just our
skyler degenkolb: And when you work it out and get all of the signs and factors of I correct it councils to zero.
skyler degenkolb: And so what you measure is nothing, no matter how big the DNS inside the system are imagine that you have a hydrogen atom with a proton and electron and they each have an enormous EDM. You can't see it.
skyler degenkolb: Fortunately, to establish this result we had to make some incorrect assumptions. One of them is that the particles are like and nuclei are not playing like so the fact that
skyler degenkolb: A point particle can escape to exactly the position where it's electrostatic energy leads to this cancellation of the observable moment.
skyler degenkolb: Is not true because the particles have finite size and the thing which is left over which you can measure is called a shift moment and it's something like the r squared with a dipole density, you have to subtract off a bit of a quad report moment.
skyler degenkolb: But there's a rich literature on that and there are theorists calculating these things for different atomic systems.
skyler degenkolb: They scale as a power between two and three of the atomic number. So when you want to measure this, you go to heavy items and that's relatively intuitive because those are the larger nuclei.
skyler degenkolb: There's another assumption which is less relevant for the nuclear idioms, but for atoms, where
skyler degenkolb: You want to measure an electron EDM instead it's important, and that is that reality has relativity in it and therefore the EDM which you measure has this
skyler degenkolb: Gamma better de de de de de each arm and the difference between the rest for a medium and the lab frame EDM gives you again something that you can. So there are references for both of those. I'm happy to answer questions to this.
skyler degenkolb: Now what system do you want to look at
skyler degenkolb: Well, the one where you can actually discover an EDM, obviously, but unfortunately we don't yet know which one that might be
skyler degenkolb: I'll tell you about the two that I've worked on xenon 129 and the free neutron
skyler degenkolb: But again, there were dozens of these experiments. And it's actually very important to have dozens of them for reasons that I'll get to sort of the end of the talk.
skyler degenkolb: But these are relatively similar in in the experimental space of EDM projects that exists with us trapped polarized particles in the case of xenon on the left.
skyler degenkolb: You have a small cell with hyper polarizing nuclei is unit 129 and helium three which undergo spin procession and are measured by a squid over
skyler degenkolb: some period of time. Normally, a few hours per run. And on the right, you have a much more complex apparatus, because we have to keep making neutrons from the reactor, but there's basically a source a magnetic shield
skyler degenkolb: And some measurement cells inside it. And this is a cutaway view of the magnetic shields with one measurements along saw a second measurement cell.
skyler degenkolb: On the bottom and the essential principle is the same. You apply electric and magnetic fields you do spend procession.
skyler degenkolb: You look for a phase or frequency shift at the end of the measurement which correlates with the direction of your applied electric field you check that and also matches the strength you apply that it doesn't
skyler degenkolb: Scale as a square and then use it abound on the EDM. In practice, of course, this is an exercise in the detailed management of systematic effects.
skyler degenkolb: And for this reason most of the effort goes not into just clicking run and waiting for a measurement to be over. But into tracking all of the other things that are going on that could look like an EDM, even though fundamentally it's not
skyler degenkolb: And so both both experiments have very stringent magnetic field control requirements and effectively use the same outer magnetic shield. So the helium.
skyler degenkolb: xenon EDM on the left this outer shield is the same outer shield as the neutron EDM or it was when we began the experiment we're waiting in unit to have ultra neutrons delivered and the tsunami do something to do what we did eventually this experiment to Berlin and there's a larger
skyler degenkolb: magnetic shield with more layers, which is a bit better characterized there and this, this one came to the Iowa to do the neutron EDM experiment. There
skyler degenkolb: In the helium xenon experiments. There's only one cell in the UC unexpressed or two and this is a bit related to the fact that while you can measure continuous spend per session with a squid.
skyler degenkolb: For the noble gases we don't have enough neutrons to do that. And so we have to count them at the end of the measurement and you get one number
skyler degenkolb: Per run. And so you actually need a second measurement, where the field is pointing down instead of up that was performing simultaneously.
skyler degenkolb: In order to compensate drifts which we can take care of more easily on the left, because we have a data set.
skyler degenkolb: With points in time that spans the entire interval of the measurement, whereas here at the end of a five minutes in procession run
skyler degenkolb: We only get one number and that number includes the accumulation of all drifts and fluctuations that may have occurred during the five minutes and then this is just to show the master equation again for sensitivity in terms of
skyler degenkolb: Standard deviation on the electric
skyler degenkolb: I'm going to read this a little bit differently for the two cases because you're here for the neutrons. The end our numbers of neutrons and numbers of measurement repetitions, the uranium xenon experiment gets the data that looks more like this. So you can
skyler degenkolb: Exponential waiting sinusitis. If you zoom and you can see the oscillations. IT'S BEATING between two frequencies, one for you.
skyler degenkolb: Know, and you have an electric field and you have an observation time which here is tell that you have both an observation time under coherence time, whereas in the neutron case, you only have the measurement time
skyler degenkolb: And you don't worry so much about phase fluctuations or frequency drifts because again you only get one number at the end. So that means that on the right hand side, each one of these data points.
skyler degenkolb: Is the results of one run of a few minutes duration and you just get one number of spin up particles in one number of spin down particles as opposed to seeing what the entire ensemble is doing for the entire time.
skyler degenkolb: On the left, and so the systematics are handled a little bit differently. And it's a noise bandwidth epsilon is used here rather as I'm the alpha, which is a polarization asymmetry in the case of the neutrons. But again,
skyler degenkolb: The electric field has to be large, the measurement of time has to be long and ultimately the extent to which you can control the systematics coupled with how patient, you are in terms of repeating the experiment or set the final limit that you have 10
skyler degenkolb: This systematic checks look like this. In the case of helium and xenon for the neutrons. I can't really tell you in so much detail because we haven't reached that point in the experiment, yet we're still Commission.
skyler degenkolb: But basically everything which you can change you do to be sure that when it shouldn't have any effect.
skyler degenkolb: It indeed does not the general classes of systematic effects are these, I won't go through them laborious Lee. But again, I'm happy to answer questions and the ones that we really checked in detail.
skyler degenkolb: For this experiment or the following the main message is that this gray bound
skyler degenkolb: Is more or less the final results and the fact that none of these systematic checks deviate too much from that central value. So whether it was data, we took in 2017 or 2018
skyler degenkolb: These are three different measurements selves. We change the gas pressure. So we changed the direction of the magnetic field we change the rate at which the devil did was turned on.
skyler degenkolb: We even controlled for a potential systematic which correlates with the size of the error bar and the data set. So you have to try to bend over backwards.
skyler degenkolb: To prove yourself wrong and these experiments and then whatever holds up with the young is what you're left with
skyler degenkolb: This is the final our budget from EMC on. So this was a result from last year. And at the end of the day we improved by a factor of five over the limit
skyler degenkolb: From 2001. So these are long, slow laborious experiments that kind of making marginal progress.
skyler degenkolb: In the end, but at the same time it's exciting because of discovery potential and because of the bands that you can set for multiple systems. And I'll get into that.
skyler degenkolb: And then just to reiterate, on the right hand side. This is what we expect for Penny D on but these are projected numbers for them so
skyler degenkolb: This is how you do an experiment. This is what the result looks like. Now we have to interpret the results and see what that means in terms of constraints on the model or identifying
skyler degenkolb: I'm going to try to view this through the lens of global analysis, which is a familiar notion to people and other fields. It's commonly used in the context of characterizing Standard Model CP violation. For example, the
skyler degenkolb: Systems and the point is that you can't measure every parameter that matters in a single experiment.
skyler degenkolb: And in fact, for EDM experiments that were about 13 parameters that matter and see. We need 13 experiments to disentangle them.
skyler degenkolb: And although we have more than 13 experiments. They're not sufficiently orthogonal to do that in an ideal way, but there is an apparatus for doing this. And it's not as effective fields.
skyler degenkolb: Basically CP violation enters
skyler degenkolb: Its really frustrating CP violation enters the Standard Model through two sources and
skyler degenkolb: Could be three, but will ignore the neutrinos and I get the slides back up again. Basically,
skyler degenkolb: Can you see the screen again it says I'm
James Smallcombe: Screen shares backup.
skyler degenkolb: Wonderful three, but I don't know why this keeps crashing.
skyler degenkolb: Standard Model CP violation occurs in the cK A matrix which mixes quarks and in this state of parameter which can be thought of as the vacuum phase of the strong direction.
skyler degenkolb: In the TCT Lagrangian. This is the one which are allowed to write down and there's no real reason for having it be of one size as opposed to another.
skyler degenkolb: A natural assumption would be that this data bar is an order one.
skyler degenkolb: This connects to the Matter, Antimatter is symmetry on the neutron EDM tells us that it has to be less than 10 to the minus 10. And so that's a high degree of fine tuning. This is known as the strong CP from
skyler degenkolb: The CPM phase is a very weak source of CP violation in general. So, this is this is mediated by the the charge Trent W. Bush was on and it has a similar structure to the neutrino mixing matrix, but much smaller animals.
skyler degenkolb: This is the dominant sources CPU violation in the standard model. And this is what the Amazon experiments focusing. Once you've exhausted. These and ignored neutrinos because it turns out that contributes much further along.
skyler degenkolb: At higher levels of precision all that's left is beyond standard models.
skyler degenkolb: And so you can calculate the standard model predictions from the CPM fits and the very small. So the electron EDM comes in at for loops. This is about 10 to the minus 38
skyler degenkolb: Centimeters. Right now, we've hit the 10 to the minus 29 level with experiments, the new 20 DM is a bit tricky. So, you can write down a CPM contribution in terms of villains forks.
skyler degenkolb: And it's quite small, up to the minus 34 don't notice it's 10 to the minus 31 here. And that's because this is not the contribution. It's actually mess on exchange.
skyler degenkolb: And diagrams like this which on it. So this is a long range contribution to the neutron EDM. If you like the CPI living vertex here can be something like this where you have
skyler degenkolb: A delta x equals one transition. And here is the W fields that showed up in the Lagrangian before
skyler degenkolb: We can calculate the valence Corp EDM.
skyler degenkolb: rather well compared to other things that we can calculate idioms for and there's there's a rich literature on that and theorists are mainly working actually on nuclear dramatic matrix elements.
skyler degenkolb: That propagate is into the neutron and nuclei in order to provide a clear connection to the results of experiments because it's a multi scale.
skyler degenkolb: I just mentioned this very briefly, but the neutron EDM is sort of directly connected to the fate of parameter, if you would measure a finite neutron EDM at the current level of precision.
skyler degenkolb: That conclusion would be either this is beyond the standard model of physics or you're seeing the signature of a small bit fine.
skyler degenkolb: Without other experiments. You can't distinguish those two possibilities.
skyler degenkolb: This is one of the reasons we need other experiments and indeed the neutron contains contributions, not just from theater bar, but from multiple play on nuclear on couplings, and from multiple quark Ed Young's uncork from our audience and so
skyler degenkolb: It's important to have many experiments with different dependencies on these parameters in order to disentangle what CPU violation ends up were in a measurement
skyler degenkolb: And then turn. Secondly, the strong CPU problem has led to the proposal of dynamical accion field and this connects to other
skyler degenkolb: Areas of physics in terms of dark matter searches and so forth. There are also extended theory is which includes CPU violation via leptin quarks to explain
skyler degenkolb: The Amazon decay anomalies and even Meyer on neutrinos. All of these connect with EDM experiments in the sense that the CP violation included in these models will generate an EDM, at some level, so
skyler degenkolb: The leptin corks or less constrained by EDM measurements at the moment, and they are by the decays and the ironic neutrino thing doesn't come in until several orders of magnitude past our current experimental position, but I think it's still
skyler degenkolb: A bit ahead of the standard model. So it's actually very interesting when you have a sophisticated theoretical apparatus to interpret the results of many experiments.
skyler degenkolb: To do this in a global way as possible because it has an impact not just on a single beyond Standard Model CPU violating model, but on other models that have been thought up for other things after the discovery of CP violation and I think
skyler degenkolb: Someone pointed out that the neutron idiom and violated more are excluded more 30s than any other experiments in the history, physics, just because the 1964 discovery of CPU violation gave birth to so many proposals which were not possible to test if there was
skyler degenkolb: So phenomenal logically, we have the effective field theory apparatus which has these dimensions six operators and Wilson coefficients, the standard model is here, and that includes the CK
skyler degenkolb: And feta terms. So which master mentioned those internet depends on gauging variance and how many eggs fields you need. But basically,
skyler degenkolb: After we've set that to the side, we have order six available for beyond standard model of physics, but
skyler degenkolb: We don't necessarily need a model dependence interpretation. So all of the degrees of freedom, which are proposed by a given model can be integrated out as we say in jargon in the sense that there's degrees of freedom are
skyler degenkolb: Removed and we have effective vertices for the interactions which is still CP violating but these coefficients. These see some eyes.
skyler degenkolb: Are what dependent on the masses and couplings of the new degrees of freedom and at the level where this is brought into the standard model and interpreted in terms of experiments.
skyler degenkolb: You only have to concern yourself with dimension was constants and Standard Model fields.
skyler degenkolb: And so whatever the fundamental source of CP violation is over here, whether it's within the Standard Model CK and CCD, or it could be a multi Higgs supersymmetry.
skyler degenkolb: Left Fred symmetric Technicolor whatever you get about 13 of these dimensions Wilson coefficients and these
skyler degenkolb: Enter at the different energy scales, where we can do experiments with different readings and in terms of the primary types of systems. I told you about before, these are the primary sensitivities.
skyler degenkolb: So what are these things. This is the list, you have the Q CD set a parameter you have something which is like the electronic medium dimension with units.
skyler degenkolb: You have some electronic coupling. Once you have a core EDM, you have a core EDM which arises from the glue on field, you have a similar thing for the glue on field itself and then you have more complicated multiple cork interactions, for which actually
skyler degenkolb: Is are still problematic, right now, but you can write down the effectively grungy and if my general way. And therefore, when a theorist tells you how a given system like as you know nucleus depends on the G pi couplings, and the tensor electronically on interaction.
skyler degenkolb: You can
skyler degenkolb: Rather than describing the entire thing to a fundamental EDM of the constituent Nick Leon's or the constituent quirks. If you go high up enough on energy scale.
skyler degenkolb: You can say something about the linear dependence. When you combine it with a second question.
skyler degenkolb: And indeed a dramatic level we have an effective Lagrangian in terms of the appropriate nuclear on fields and it mainly involves Digi pie couplings here.
skyler degenkolb: These are the short range contributions to the nuclear medium. And so the things that we're all in the table of theoretical predictions.
skyler degenkolb: A couple of slides ago. And then at the level of nucleus, you hold the Shift moment which includes these nuclear mediums, as well as the pie on nuclear on couplings.
skyler degenkolb: Again, did you play to we can frequently ignore for reasons related to kind of symmetry.
skyler degenkolb: And then the shift moment is one component of the EDM you see on a diet magnetic Adam and every item that comes in with its own waiting coefficient that depends on atomic structure. And you also get the semi electronic parts.
skyler degenkolb: Namely the tensor electronically on interactions in the case of die and magnetic Adams and mainly the scale or ones in the case of para magnetic atoms and molecules.
skyler degenkolb: So the sole source approach to this is basically what I said, parenthetically, a moment ago that you can make a measurement and say it all came from one thing
skyler degenkolb: So if you do that, for example, with rim oxide experiments that can be interpreted as a band on the electronic medium. If you interpreted only as a bound on the electronic medium, then you get this
skyler degenkolb: In principle, it can also have a contribution from the C sub s the scale or electronically on interaction. And if you interpret it only as a bouncy sub s
skyler degenkolb: You get the point 610 to the minus nine, as usual, the truth is expected to to live somewhere in between these extremes. But exactly where
skyler degenkolb: We can't say without a model or without an independent measurements in a system where the linear dependence on D MCS is different from what it is. I'm sorry, I'm oxide.
skyler degenkolb: The PR magnetic systems are relatively clean
skyler degenkolb: These are the two primary things that depend on for diamond magnetic systems you have a lot more possibilities.
skyler degenkolb: Mainly for the CT 2G pie coupling and the short bench part of the neutron medium but you can write down a matrix. And you can say that the EDM I measure depends on the Wilson coefficients with some parameters and then you invert the matrix and you have what you want.
skyler degenkolb: You can drop this space more easily in two dimensions that in 13 so I'll show this just for the paramedics systems.
skyler degenkolb: This is now this is a perspective, which is gained a lot of currency over the last few years in the community of experiments lists of theorists studying idioms and I'm happy to see that it's it's been quite mature in
skyler degenkolb: Metaphysics and elsewhere, but it took a while to get traction here and in this way on the right, in particular, this this great band comes not from the parent magnetic system.
skyler degenkolb: But from a diet magnetic system, the neutral mercury 199 Adam, which has a very orthogonal dependence that sort of diverges quite rapidly because the parameters in question the D and the Cs.
skyler degenkolb: Or not the primary sensitivities of the mercury system. So even when you have a bounce from a system which to lead in order
skyler degenkolb: does not involve these parameters defects that the experiment can be done very precisely, and mercury and can actually have an important impact on the global picture in this 2D CS amp D picture. So, and then here just to note the
skyler degenkolb: On the upper
skyler degenkolb: Scale. This is rescaling the CS in terms of the dimension was
skyler degenkolb: Wilson coefficient which is created by the square in the face value of the scale of new physics. So this is the parameter ization that gives you the
skyler degenkolb: The dimension was action which you need and it tells you, at the same time in a very rough order of magnitude estimate sort of way.
skyler degenkolb: What scale of new physics, you may be probing with a given level of experimental precision because we we know what the Higgs valve is about 300 GV
skyler degenkolb: And then some of these experiments are reaching willing to TV space and beyond. So for example, in the case of anomalous CP violating Higgs couplings.
skyler degenkolb: Idioms are actually much more constraining than LDC data, except in the case of the parks where the Muslim countries have done a lot of work.
skyler degenkolb: Okay, so that's that's the last science slide I want to very briefly abuse my position your guest speaker to advertise a couple of things on my collaborators. So, one, one, is it if well okay if you want to learn more.
skyler degenkolb: We'll be doing a lecture series for about a week at the end of September, beginning of October.
skyler degenkolb: Electronically but hosted by the island, the Technical University of Munich, so you can contact me or Peter Salinger to participate enough
skyler degenkolb: We'll also have a workshop, at least in early 2021. We're still figuring out the logistical details of how that will work in our current
skyler degenkolb: global crisis, but we're looking forward to it. And we're always on the lookout for talented students and postdocs, particularly for the penny Diem
skyler degenkolb: Collaboration, so you can get in touch with us. If you are one of those or you know someone who is
skyler degenkolb: Looking for young and then this is the Thank You slide I've assembled a lot of information from my
skyler degenkolb: Experimental and theoretical collaborators and from other people who just give talks and it's a huge community efforts like I can't in any way take responsibility for the totality of it, except for the parts which I presented wrongly so I give you the chance to come the
skyler degenkolb: Streets.
James Smallcombe: Thank you very much, Scott.
James Smallcombe: Yes. Do we have any questions. So if you go into the participants menu and use the raise hand icon in there or if you don't have a microphone, please do go to the chat box.
James Smallcombe: I thought I saw a hand fly out
James Smallcombe: Immediately retracted so I can ask one question. Get started with some pretty, it's very
James Smallcombe: Basic on betraying my my lack of understanding of most things, if you're feeling mechanical so you've got this big chamber for the magnetic field thing. Is there some collaborative aspect to that or is it just a lot of material.
skyler degenkolb: Whether or not it's clever. As a matter of opinion, but the way you make it so that works as it needs to is that you model it and you force the model to obey Maxwell's equations.
skyler degenkolb: magnetic shielding is tricky because there's there's historically been a lot of black magic and making sort of cylindrical curved surfaces and annealing them properly.
skyler degenkolb: And so we tried to do as little as possible. And this is mainly built out of flat sheets and anytime you have a joint is covered with another slushy.
skyler degenkolb: On both sides and we can model a bit better what happens with flat pieces and we can with perverted kneeled ones and so
skyler degenkolb: This was actually a major undertaking by my collaborator Peter feeling or two to design it in the first place, but that's that's basically what was done it was it was modeled and the when you model it Maxwell's equations or a day to the networks in the end.
skyler degenkolb: It's very heavy and expensive and delicate to do properly and you have to sort of profit from the Lord magnetic shield design when you're putting it together and not use stainless steel anywhere and so forth. But there's no there's no overwhelming secret to it. It's
Yeah.
James Smallcombe: Do we have any other questions.
James Smallcombe: Yes, please. Peter
Peter Butler: Hello, scott. I can you hear me. Hi.
Peter Butler: Yes, we can even see me okay
Peter Butler: Yes. Right. Yeah. You alluded at the end of your talk to
Peter Butler: Comparing the limits that, you know, various dynamic magnetic and pair of magnetic atoms.
Peter Butler: Have given neutron idioms and so on.
Peter Butler: To by comparing the limits or what you've achieved with those. And what what you can say about the bsm physics.
Peter Butler: From la FC experiments.
Peter Butler: Now,
Peter Butler: Could you could you possibly just simply expand on that a little. I mean, what you're essentially said is that for many of these
Peter Butler: Standard Model parameters you put restraints, which you can only measure at TV have much higher energies that then as possible. The ELYSEE, but there is still a windows of opportunity that
Peter Butler: The ELYSEE can discover, I assume.
skyler degenkolb: Well, yeah. So the basic problem there is that when when you held a forum to at least see data, you might gain a factor is
skyler degenkolb: In the balance on things like pseudo scanner you colors and exclude blue and other anomalous couplings that are interesting. When the context of CP violation.
skyler degenkolb: And that will that's invaluable factor of two. But we usually look at these energy scales on a lot
skyler degenkolb: In the context of EDM, you make a linear improvement. So I don't want to say relatively easily. But without building a new LH see at least. And a lot of them at the current level are actually dominated by theoretical uncertainties. So a lot of calculations for particular matrix elements.
skyler degenkolb: And generally the way that these these giant results are interpreted is to say we have some theoretical handle on
skyler degenkolb: The dependence of a given experimental system on the Wilson coefficients that may arise from a particular model.
skyler degenkolb: And given the downs that the experiment gives us we can set a minimum mass scale for new physics process and those those math skills are usually what's compared between EDM thumbs and LLC. And so the LSC definitely still wings on that into the sector, but
skyler degenkolb: The, the gums are
skyler degenkolb: Either a head or about to be digit improvements in the theory everywhere else.
skyler degenkolb: I don't know if that answers your question.
Peter Butler: Yeah, I think that's fine. Yes you meant to where it has it.
Peter Butler: That's the window of opportunity, I assume, so that's
skyler degenkolb: Yeah, that's this right but that's the, I don't know, maybe the interesting part there would be the SDK anomalies in the Muslims. So I'm unitary is a little bit
skyler degenkolb: Intention, and they've been very stringent tests of that. So I think that's a very natural place to drill down at delicacy in this context.
Peter Butler: Okay, thank you.
James Smallcombe: Okay. Do we have any other questions.
James Smallcombe: Okay, I'm gonna say now if for whatever reason you can't use the raise hand icon or the system is clutching for me again. And I don't see you. Please can you unmute yourself and just go ahead with your question.
Andy Briscoe: Is Carla.
Andy Briscoe: Nice. Very, very nice talk. I really enjoyed it. I wanted to
skyler degenkolb: Talk.
Andy Briscoe: A bit more about the actual measurements on 01 29 I didn't really understand how the measurement actually
skyler degenkolb: Fundamentally operated and I
Andy Briscoe: Ask, is this these types of measurements are they restricted only for stable species or could they be doing something on stable as well.
skyler degenkolb: That is an excellent question.
skyler degenkolb: To answer the second part of it first know it works also an unstable species and that's even been
skyler degenkolb: Variously done and planned and other systems. So the, the most natural parallel in the case of xenon would be one of the radon isotopes to 21 or 223 and that's been that was proposed a long time ago for the science program trials.
skyler degenkolb: It's sort of stagnated. A little bit. I think we need a little bit more data about the nuclear states in question that
skyler degenkolb: Are supposed to take advantage of an optical different mission. But anyway, that's a bit of a digression.
skyler degenkolb: In principle, this works for anything where you can fill a measurement cell like this one with polarized particles and then measure the processing magnet position with a squid.
skyler degenkolb: That's the basic contribution of the technique that's what was new convert everything that had been done before.
skyler degenkolb: And the polarization process is totally transferable the unstable species that's done by spin exchange optical pumping
skyler degenkolb: Normally with an alkali in this case rubidium so the Rubidium is laser polarized. There's a family contact interaction.
skyler degenkolb: Between the rubidium electrons, the xenon or helium nuclei, the spin transfers to the noble gas nucleus.
skyler degenkolb: Where it has a much longer coherence time and then this is all done outside the magnetic fields we can fill a cell and bring it into a small hole in the wall and and the cell sits there with polarized gas in it and we do Mr on it and so that fundamentally works as well with read on.
skyler degenkolb: Depending on the level of conceptual abstraction that you're willing to accept it also works for
skyler degenkolb: Things like radium which are not trapped in room temperature cells, but in in vacuum chamber is via laser trapping and cooling and you can imagine similar things.
skyler degenkolb: For radioactive molecules. And this is actually a very hot topic at the moment for molecules. In particular, it often makes sense to go to
skyler degenkolb: A beam geometry, because the the trapping and cooling technology is not so far advanced as it is for Adams and
skyler degenkolb: In species where you have strong wall interactions basically here with a cell, you only get away with it because it's a noble gas and the electrons shielding English very well. Once you get along greens time
skyler degenkolb: In systems where that's not the case. You have to do it a bit differently. But these are all very active areas of research by other collaborations that focus on particular species, and especially in the unstable.
skyler degenkolb: Systems. It's very interesting to pursue because you can get large enhancements of the shift moment. And if you get a few orders of magnitude there. Then you may compensates or overcompensate from little particle statistics or a slightly were signal to noise in the experiment.
skyler degenkolb: Great. Thanks. That was a really good answer. I enjoyed it. Thanks.
Andy Briscoe: Right.
James Smallcombe: Okay. Do we have any last questions.
James Smallcombe: Don't
James Smallcombe: See any. So I think we'll call time there, and also thank you very much for coming and speaking with today. Skylar
James Smallcombe: My pleasure. And thank you for joining us. And before I let you go. I'll just do the club for the upcoming talks.
James Smallcombe: So on Wednesday. The, the other address hosted by Manchester, we've got the student talk session. So this Wednesday. We've got ocean one from Sheffield will be talking to us about you Tron spectroscopy for fusion environments.
James Smallcombe: And then back here plenary session next Monday. Same time 3pm PST I won't go Constantine master false from UWS he's gonna be talking to about pygmy dipole resonance in
James Smallcombe: So please join us again. Then a lot. Have a great week. And thank you for joining us. And thank you again. Bye for now.