Okay, so thank you for the invitation, I was asked to talk about lactone colliders
in the future colliders landscape. Now, given the time available, available, I'm
not gonna give actually a super complete overview of all work can be done with
electron colliders and the corresponding Of course counterpart of the same on the
same physics topics that can be done at hadron colliders. And the way I suggest
you to look at the physics briefing book that we prepared for this strategy update,
which is which is very cool, which is very complete. Instead what I will do is that I
will try to give basic concrete examples okay, but selected few of them, I will try
to outline what is the general what is the physics potential of weapon colliders and
now, especially this physics potential and the comparison with other machine changes
and evolves when you Race, the energy of these little Collider. So, we already saw
in the end and then you will know right that a satisfactory mid level position
program on x goblins, especially to those two vectors and so on. This is possible
only at the Higgs factory electron collider as far as we can tell today. And
so this is a unique feature that electron colliders had and and that's one of the
main reason for for interest talking about lepton colliders operating at as X Factor
is in the few hundreds, maybe up to the top threshold in the case of clicker
energies that and that there is a certain physics case when you when you start
considering things like click, which is three TV, for instance, in the Iron Age
situation changes, and then I will show you how the situation further changes if
we start dreaming somehow to an even more energetic lead compliance For example,
immune, immune. Okay, so let me start the from, from the standard picture actually
healing the beanstalk. I think this picture is not standard anymore, maybe it
was done a few years ago, but in any case, I'm going to argue that it is incomplete.
So, the comparison between add on electron colliders that brings together some sort
of philosophy, but it is also very concrete as always in science and the
standard picture which I would argue is incorrect, but as you have already seen
actually, is that well astral collide other collider physics potential coincides
with the possibility of performing direct response searches and let them collide
this thesis potential coincides with performing indirect searches. Okay, this
is a well all what you want to do and you have to do at the lead collider is to
measure some quantity that is predicting the sample model sample section and
compare with under my prediction and see if there are departures to be attributed
to new physics. This is an Indian In physics search, while the other collider
is good, essentially because it allows you to probe directly in physics to produce
the new resonances. And I think we have to emphasize the importance of exploring the
energy frontier in this way, because, well, it's a very complete way of
exploring, because in essentially all new physics and I will say no, there are new
particles that could be detected as resonances. And also it's very direct, as
the name says way of seeing what's the underlying physics because we literally
see the agents that then go back into the go into the Lagrangian and produce the
underlying theory right. So characterization is very easy. If you
discover a bomb okay or at least that we also and this is the advantage. The
disadvantage of course, is that you may fail as usual, because new particles could
be too heavy to be seen directly, but still they leave some visible imprint okay
in some indirect throw when in this case, you should go on the other side, you
should do something that exceptions signature which in this in this A
simplified picture coincides with building. The other way, of course, we
knew particles could be decoupled and or covered by background and you will not see
them. The advantage of index searches on the other hand, is similar in the sense
that it's also a very broad way of exploring the unknown because you physics
unavoidably changes based on the model predictions. And so you have a very robust
and rewarding and also say like the one of left right goes on textbook, the problem
of standard model, what we call Standard Model measurements, from which then you
can have wide it each shift on a wide set of VSM possibilities by a third party
tools. The disadvantage, of course, is that well, yeah, new physics will affect
your observables. But our match, for example, in the MSM, not in general in
supersymmetry, but in them it's the same. These indirect effects are tiny because
they come from loop
Do you measure a single observable, like he wants to experiment to find the
tension, you have a very hard time to see if this is really any physics and to
explain it so to turn this nation into a true new physics discovery, through
discovery of a new theory, okay, it's much more than that in direct as the name says,
of course, the balance of pros and cons is very much in physics to the bandit game
depends very much on the model and not so often in the parameter space fight in
which you are in this model, and is what we call a compliment added. And that's
definitely true, there is a lot of complementarity between direct and
indirect searches. What is not true is this direct correspondence of hadron
colliders for doing that association lepton colliders for doing that searches,
and that's why I am saying that is slightly different picture will emerge
during the dog, as especially when we raise the energy of our let them collide.
So The standard example for complementarity was discussed a long, long
ago. And you'll see much of a lot of updates again in this 1910, which is the
physics degree book I was suggesting you to look at is probing the idea that the
Higgs may have finite sides be a composite object, which is a way web pose the
question itself or even not talking about naturalness a position like this. If you
want to do this, you need two parameters, at least, which is the size of the x and
the inverse of these sides. Controls is a mass scale that controls the mass of the
extra particles that come together with the Higgs the Higgs is an add on is a
bound state of new Dynamics, which unavoidably also produces some kind of
Romanian for instance, taking an analogy from UCD for example, being one particle
to be to be produced the invasion production and the m star one or the x
length is they have to be At mass, the other parameter is the coupling to start.
Now, this coupling place sort of we're all into Cindy like theory, these two studies,
largish, maybe four pi or maybe a bit less, but you may consider the possibility
in which it is on a really wide range. And this gabbing g star is the coupling of the
resonances been between themselves and so it plays a sort of we're all when it comes
to for example producing this heavy row restaurants, single production now you bar
it go it goes through a beautiful gauge goes on and then you pay your mixing and
this mixing you see is the week gapping divided by the standard stuff. So the only
thing you have to know understand this slot is that Judo which is actually just
out here, okay? control so it's the inverse of this just that that controls
the strength of the single of the production of these particles and display
in why you see a small g star the searches are very effective, we have a very good
message okay. So which is the converse you would expect so just that is not The
cabling, but it's the inverse of the cabling in this in this plot if you want
and so, you have that for example, the FCC, these are very updated projection.
So, for updates, look here they have a very good mass storage. On the other hand,
when you go at large g star then the cabling becomes small and so you have to
rely on something else. And you discovered that when you start becomes larger, then
you add a fixer and start mass you stop that getting a big effect. So in escapees,
for example exempting to backdoor six couplings to, to top also. So you you go
for example, and you measure them at their meal. This is all the name of the lab for
what could be now they say more or less Do you see or click so the first some
something's factory that's not cool. Either. We make all things above design,
potentially excluded. Okay, and so you you you probe these other parts of the plane,
and so you'll see clearly complementarity and so you'll see that you do need the
electron They don't collide together in order to probe the complex composite
hypothesis in a meaningful way That is to say to answer what is the size of these
okay or what is the bound if you are unlucky on the size of the x you have to
move you have to be vertical right in this in this in this plane and, and you cannot
do that if you don't cover also this page
let's try to do an even simple thing which is a z prime boson Okay. Have you seen a
resonance of which can produce a bump at the FCC h h in for Gabbar to to the
electron for example, or whatever other final state here the situation is more
simple in the sense that the production cross section scales with the C prime
Catholic square, okay, so it's not the inverse, it's really get bigger when the
company gets bigger. And this is one way to prove it. That is to say to go at the
FCC h h and produce this orange line which corresponds to the direct search okay for
this particle which becomes more and more effective as the governing increase but
But well it saturates at some point, because you know at some point or to
luminosity function may these things become a bad thing. On the other hand, if
you go at for example, the FCC you can measure very precisely the indirect effect
of the same object, you can regulate it out you get the contact interaction for
fermium works like similar to the familiar if you want vertex which which corrects
the sender mother correct the perception by an amount the relative amount which is
again does that by cabling, okay, divided by the Prime Minister square times four
dimensional analysis their energy of of your processes that you're measuring, so,
it would be a couple of hundred gv if you are at FCC. So here there is no
complementarity. Well, there is less complementarity to start with in the sense
that when you have MATLAB, when now when you are at level two, Jesus Christ, Jesus
prime, both ways of probing it of probing is more that are more effective because
you don't have a way of thinking that the production goes as one over g stop
happening like the previous slide. But also quantitatively, you see that the FCC
is simple simply loses with respect to the direct searches, we perform it that the
FCC, Hh, okay? Really, it's very precise. So it's measuring this cross section and
the soul is capable to constrain the physics effect as much as it can matter
the precision of the order of 10 to the minus four or even 10 to the minus five.
That's what you can do, for example, for a plus a minus two plus b minus measurement
from which this bomb could be extracted at the FCC, but you can either make it
because this ends that find suppression is too much if you want to be sensitive, for
example, to this point. If you now go to a higher energy level Collider, for example,
click at its 3d v energy ran, then all what you win is simply this square factor
that now becomes three TVs where rather than being few hundred gv square, and so
the relative effect induced by this underlying model is simply bigger. Okay,
it's bigger and so you you have bigger things. Which you can probe and the in
this case you can project the limit which goes here and you see it covers much. I
mean some amount of space okay, that that searches at the FCC, Hh would not actually
actually cover Okay, so to see he loses and click weeds and this is due to this
energy announcement is very simple. On the other hand, well it's not the end of the
story because the ICC hh can also perform in that it searches and and and Michaela
already already mentioned it is actually since the effects we have started we are
targeting our energy announced that we don't need the say 10 to the minus four
measurements which of course you cannot do at an atom Collider in order to see them.
Okay, so to catch this energy growth, you don't need that the amazing accuracy which
is proper, which is the feature of Lego colliders if you want you can really do it
also FCC h h. And similar things can also be done at the LSD actually, we'd
measurements at the percent or 2% accuracy in systematic Accuracy for example, this
would come from some bilateral final state studies at the FCC. Ah, this is pretty
important that this kind of the cool lie energy probes are somehow the idea of
making some measurements or exploiting some accuracy, but the Thai energy that is
exploiting energy and the Curiosity together and when it is possible, like in
this example it can, it can bring something some new interesting direction
of inspiration. And this is of course, very promising for direction at the FCC,
Hh. And so we go to the first element here, which I want to which I want to
somehow slightly modify, which is, well, I don't like this, what precision is
possible, it doesn't go like this. And we already saw examples in the previous store
on top of the ones that I'm making here.
And so, well, you can build another collider also if you're interested in
performing that it searches of some particular types in some particular
condition. On the other hand, destroyed that the lepton colliders I mean let them
colliders Of course, if they are a tie energy can also exploit these mechanism as
we saw from from click in this block that you see click it was slightly better than
the SEC ah but somehow comparable okay. So, keep in mind the other advantage of
his energy probe is that somehow the correspondence between what is growing
with energy and then aligned physics is much more direct the energy growth is sort
of the center of the beans is much more striking evidence of new physics and also
the characterization is easier because you have you can more easily disentangle
effective operator contact interaction is responsible for the growth and then
complete it becomes a little bit easier. So, also on this side, I think we should
reconsider a bit this this generalization feeling that people ask in this respect.
And now let's come to the last last point which is a whether or not It's true that
that let them go like this you can only do index searches okay. Actually, if I knew
nothing about accelerator physics, which is more or less the case I would not think
like that I would think the opposite right? Because let them colliders to the
principal be very good at performing that searches because Latin colliders do is
that indeed have the competitive advantage over problem machine over I don't go lie
this simply the energy is stored the energy that you give to the beam is stored
in fundamental particles which then when they collide, that they produce reactions,
which are part of the reaction, okay? And the percent of the time, okay? Instead
that if you are at the alkalizer, as you know very well that apart from
distribution functions, and you waste a lot of energy, if you've been 14, TV, etc,
you don't have access to, for example, a production of 70 particles, you don't
really have access to 14 TV, central Monster Energy in the bathtub. And so
opportunity again, The high energy physics is probing this probe better is probed at
the higher scale with the smaller energy of the collider if you are at lepton
collider rather than nothing at the problem okay. And of course, this starts
becoming interesting if let them go like this can add a little bit more energy than
the one of like, for example level 10 or 14 Db like in this plot here and this may
be feasible, maybe, for example with the immune Collider, okay, which is something
we are trying to see. You're gonna have a look here
right. So, so, this plot is supposed to show this very simple observation. In this
block that we have, we consider some new particles, which we producing bear, the
particles have a mass m, which is taken to be of the order of the square root of S.
Let's say they are square root of s over two to be just below the threshold. The
production threshold is guru professor of electrical life. See me on Collider, okay,
this particular production will have a certain cross section. And now we go and
we go to an apathetic admin Collider in which we want to produce the same fate of
particles and we say raise the energy of this proton collider until when we find a
quality of cross sections okay. So for example at this point here the this energy
for the proton collider would be such that the same particle okay the same production
particles with the mass of around the you see here around 70 V which is alpha 14,
okay would be would be produced with the same rate at the collider and at the
corresponding level. And there are two lines because if you have particles that
bring the QC D color on top of electroweak charge, then they algrim collider is
favoured by the fact that can produce this particle in pairs you can produce these
particles in pairs using Cassini. And so this is the blue line while this is the
dashed line which is for part two Because that only add electroweak charge. So, this
reference point is particularly fortunate because somehow by chance, I would say,
but it so happens that this estimate gives that 14 to Vimeo will light them up and
whoever happens to correspond to in under TV, another machine. So, the FCC, the FCC
h in terms of equality of cross section, and this can be verified if you look at
some examples. So, you have the cross sections and you can somehow verify that
somehow the estimates fade from below some sometimes from above about more or less
for particles to bring about color and the electroweak charge like the stop or the
partners of composites, you can see that this estimate is verified. And with the
Start Here you can mark what is the reach of the estimated reach from the FCC, HHS,
collaboration, collaboration. And then his message for example, in the case of the
stop will be retired NTV Why they won not this hypothetical energy left on collider
would be some of the threshold for TPP divided to seven, but in this case it
would be better and and and so on as you see, as you see here, and then of course,
if it goes to exceed we know two electroweak shattered only particles then
one may say that well in terms of perception you do out you do have a lot of
new have an advantage as shown in the previous plot and in some cases also in
terms of in terms of reach. And of course, one can also imagine in terms of
characterization really having more events, this will be an advantage. Okay.
Ah, yeah, so, this requires a certain luminosity, what this requires a certain
energy and I would say that it targets reasonable targets to have a direct
aspiration program which is better than the one of the luminosity really
significantly. Okay, maybe not yet at the level of the SEC Ah, would be to have a TV
okay with 14 TV, you You may say you are as good as FCC Ah, but we tend to be you
can still be say you are exploring directly in junk junk off center of mass
energies that the police you cannot probe. And this is the scaling of luminosity that
you need in order to achieve these and the other goals of this kind of approach. Four
minutes left. Yeah, I will. Yeah, just just few words, because I think it's clear
where I want to go. If I want to discuss it, what happens in the transition from
sec II and click right. So if I then raise the energy, again, these energy probes
will become incredibly more effective than they are than they are a click Okay, if I
could offer at least 10 and when when you put your energy. So for example, this
blog, I haven't shown it before, but essentially, it's a version of the blog on
x compositing, it said at the beginning, completed in several different ways. And
this is the reach of click that and this is compare compatible, or even better,
when compatible with the one of the FCC Together with a change, okay. So, you can
imagine if instead of TV I do 30 TV just to exaggerate plus or minus Collider, I
should in order to get rich I should redo this plot four times and then I will find
my reach on the components compositing scale, which is far above what any other
project can do. And if you said I do 10 I will do I will go steal somewhere here
just have to divide by three okay. So, clearly I energy blobs now that they have
much more energy becomes much more effective than any other project that you
may they have constructed. Now, there is also space for precision in the standard
sense, it is to say you have a lot of luminosity for low energy processes like
for example, low energy in this respect is doubling production abilities production
we have plenty of double X's which may allow just the statistics after the
termination of the extra linear which is actually slightly better than what the FCC
h will do. But claims should be made with care because neon collider is a weird
environment. Okay. If so there are no, you want the full detector studies of any of
this. And also the fact that that wasn't scattering, you have also a lot of single
x actually produced maybe you will not need if the factory happens before. And
also the fact that you can, I don't know, but troublesome scattering rates which are
very high. And you know, vector scattering is somehow philosophical, even if they're
all built the fundamental nature of electroweak symmetry breaking the
fundamental nature of the terms of utilization of WWE. So let me summarize, I
really don't know but I mean, from my viewpoint, it's likely that the next
collider will be electron Collider, because precisely scabbing measurements
have a broad dsme impact, and one should not neglect that there is more than the X
rays, also electroweak measurements, if you will redo that but with a factor of 10
or 20 more precision, you do learn a lot of things, even if you just look at that
poll, and there are many more things to be looked at that just kind of projects and
also the top If possible, quite high energy electron collider like clique would
substantially improve over low energies factory and striking examples are these
high energy probes, the access to the Selenium that was mentioned also in the
previous talk and also some direct production of some particles not so light
but for example, not so heavy Otherwise, you will not be able but like the sooner
that matter can be done to TV click some singlet model. I mean, there is there is a
long list of things that can be interesting, but it's fair to say that if
you combine the FCC project in a single project that is E plus h h, as you're
allowed to do even the way the project is structured, then you can know nearly the
same Okay, there are a few cases in which we do a little bit better and then these
other projects, but on the other hand, you have a much better return on on direct
searches. A if you instead start talking about the barrier energy weapon colliders,
which to me means 10 TV or more, I think This should be studied in several ways,
but from my viewpoint in several respects, so this would surpass any present day
proposal. Future Collider. Don't worry, there's no competition, because this is
not at the moment is published to be technologically feasible. hopes. And maybe
Danny will talk about this will rely on this concept of plasma Lego which will not
say entitled to judge. But or the idea of immutable either which maybe is more is
more is more than
this very energy left on collider is a dream. And so, I mean, it's correct that
it comes at the end of the talk. But the idea is that we should try to see if it
could become reality because this will really make me a step forward in the in
the way we depict the future possible collapse. Thank you.
Thank you, Andrea.
And the floor is open for questions and comments. Please raise your hands.
I don't see
this one.
We get a Please go ahead. Yes, very quick question. You say that the very idea that
on collider is superior to any other proposal for, you know, for a high energy
Collider. So I suppose in all the cases you presented, it looks like it's the case
I was wondering how if this holds, so like, for example, if you want to produce
only strongly coupled residences, you can do right with the napkin Collider. So how
big of a limitation in terms of spectrum of you know UTM is that you can test it
Right right right right. Yeah I tried to make clear this is this has to be made the
judgment has to be made as overall because it as far as I can tell you, if you don't
go maybe to 30 TV which you probably cannot will not go okay. You will not be
able to do all the things which can be done at the FCC ah ah and the more you
will be able to do more or better okay but there are things that you will not be able
to do and so at some point you will have to choose so for example apart from I
don't know details reach that still have to be established whether you do the stop
attend TV or at seven TV this this I mean let's let's be beside this data is a case
of physics which of course, you may miss will be the one of purely you should call
it the new physics. Okay, new physics that brings only to see the color and for that
you will have a rather poor perspectives even if I'll pour these To be stuck. On
the other hand, there are things like, I don't know, that matter most people it's
either math or multiplets which as far as I understand would be done only at
collider like this one. And then you have contentedly for example, that if you ask
yourself that each one is compositing us or the rich in that iteration, that's the
prime in the under the TV mass range, you cannot do with your cc h h and you can do
here. So, I agree with you there are there are there is some amount of receiver
complementarity, but I will be able, I mean, I will say I wouldn't be able to
defend or tie to the final place that this will be clearly better than the tch but
this may just mean that.
Okay, other further questions or comments? I don't see any. So thank you, Andrea.
Thank you, and then we move to last presentation by Daniel short on possible
realizations.