Okay,
so thanks a lot first of all to the organizers for for the invitation to give
a talk on the X 17 access measure by by any 64 experiments. So we are a non Alexey
experiments I will try to give an overview of why these kind of services are
internecine and a beat to try to explain very quickly, what is m 64 experiment? So,
first of all, where do we put these kind of searches are inside what is called a
Dark Sector framework. It's an interesting framework to explain the origin or for
that matter and it is based on the existence of weakly for force apart from
gravity which couple the standard mother and and the dad market and then these that
sector they can be gay into that method can be days. So, among all the landscaper
of that sector that you can see, I don't know if you see my mouse, maybe one
second. Maybe now you see my mouse, okay, I would do it like that. So like that. I
can point that So, among all the lines the landscape of that sector, which covers a
broader mass range, and as you can see, this cannot be covered by a single
experiment. So that is really worldwide theoretical and experimental effort trying
to combine different approaches and different techniques to try to really put
all the information together. But among all the broden, a landscaper, any 64 is
basically on the mid gv region and the world is trying to look for is the time to
probe the models whether that sector on the standard model they are the uncoupled
through kinetic mixing, and the mediator of these forces is carried by a new
massive vector boson call that photo Why are we interested in them? ebgp range is
because we have certain experimental anomalies such as the video you made or
the anomalous new magnetic moments, which can be explained through the existence of
these that sectors with these cards. other candidates in this energy range. This is a
bit what is our target and how we do this. So, which is the technique that we we try
to do. So we are an experiment using what is called an active dump. So, this is
quite simple, what we have is an initial high energy electron beam which is going
to collide with a target with a gamble. And they're what we expect this to produce
through Brunstrom, our bossom candidate which then depending on its mass will
decay basically. So, the kickbacks to combine all the particles that we can
measure in our detector, and this will be the signature or if the mass of the photon
is larger than the dark matter particles, what is going to happen is like in the end
with decay invasively and what is our signature in this pediment is just missing
energy.
So, this
is a bit of our work in principle and the what is any 64 so as I mentioned before,
you An experiment at Western SPSS is designed to probe that sector physics. So,
we had quite a small experiment in comparison with galaxies, but even so, we
adapted for disagree cities from 14 institutions and in addition, we are quite
young experiments. So, it was proposed in 2014. And we started taking data in 2016.
So, we have a broader physics program and trying to cover all this kind of data of
that photon Surtees indeed with an electron beam we started in 2016. And we
took data in 2016 17 and 18 in invisible and visible mode, and in 2021 also we are
already approved to continue taking data in electron beam. Moreover, the
collaboration has proposals to do these kind of surgeries, but with a with a
medium beam what also we can address other planets as you can see here, the the
physics program has been input also of the of the European strategy for particle
physics and we are also part of the physics be on collider Gruber accent. So,
this is basically the broad physics program that we have, but my talk is going
to be focus basically on this channel on the excellent team going to understand the
model a particle, which in this case is electron positron. As you can see on the
on the arrow we we perform the searches the first one was in 2017 was a search
combine also to the A prime decay into a plus b minus and then we also took data in
2018. And then we have what we are going to explain are relatively short with a
target combined results from 2017 and 2018. So, why are these entities
intelligent Why are we trying to look for this extra thing which I will present now.
So, that is their autonomy collaboration. Would you report it indeed, and accessed
on the events coming from the deck cetacean of the very unit Awesome. So,
when these nuclei was excited it was emitting an e plus e minus particle and
the the measure the angle dependence of the submission on the on the body mass and
go to realize what the success around 17 me among all the different possibilities
that you can use to to explain the SEC 17. There is a modeller done by you by fingers
you can see in this paper, which assumes like this, this normally can be explained
through the existence of Afro phobic gauge boson with a mass around a digital. So
this particle to the couple newlyweds not universally with the quads, and should
have a coupling to the electrons in the range, which in the end translates in a
lifetime between 10 to the minus 14 and 10 to minus two. And indeed, this kind of
coupling to electrons is exactly what we can try to test in experiments at any 64
when we have a high energy electron beam. So this is a bit the motivation of our
searches And then. So in 2017, we try to look for these kind of both compatible and
how we did this. So what you have to take to keep in mind also is like, in 2017, we
were set up already, they are for invisible charities. So what we tried to
do was to reuse as much as possible I was set up from the invisible surface and try
to other people to do a visual search is to apply a mind spread. So in the end, the
principle is very, very simple. And what we just succeeded was we added another
electromagnetic calorimeter upstream of our detector, which I'm going to give you
a detail in a moment. So, in the end, what we did was here is where we will have our
high energy electron beam and then we add this small, compact target. So how do we
know if we have produced an X 17 so how many 64 works in an auction so very
simple. We have 100 gb left Through from the h2 SPS beam line they are going to
collide with a with a compactor tungsten scintillator calorimeter, which you have
here and is our active target. So they're what we expect this to produce x 17
through grams per hour. If we produce this particle what is going to happen is like
we should have an energy loss of on the energy measure on the W car. If x 17 then
is produced, what is going to happen is like embraceable should decay after the
dump show what we have to guarantee like the case exactly after the lungs after the
dump sorry. So, to reject any particular leak, we have here a veto when we should
not have any activity in case of the X 70 production.
Then the next ingredient is okay once our particle is produced is going to decay
into in our decay region into an E plus a minus b. How do we know that we have
produced Plus the minus pair basically what we placed there are a set of macro
omegas and gems trackers and the plus two scintillator that we have here s three and
s four which should measure the position of two of these. Finally, to be sure that
we can produce the simplest remains, what we have is our electromagnetic calorimeter
that was the one used for the invisible surface, which is, in this case, a lead
scintillator sandwich calorie meter in a six month six month weeks session. And
basically they're all the missing energy that we have lost in the W call should be
proceeded here in case of XML in production. We are producing but we cannot
produce anything else what we have is a huge are the only economy there at the end
of the setup we should measure no energy the position and also a veto here. Really
guarantee like we don't have additional energy energy appreciation data. So this
is basically the working principle of the of the experiment. And then this is the
result from 2017. So basically what we did, which is our even selection, so just
in in three in three key elements is like First of all, we should guarantee that we
have a neutral exceeding the W car, so no activity on the beat the Wi Fi, they will
have to guarantee that we have charged particles into the K volume, so we have to
reduce any black square. So we should see something about rockets, I mean, our
simulators. And finally, we should be sure that we don't have any other than a last
gathering. So basically, we have no activity on the veto and on the relay at
the end of the setup. In the end, the signature of Covenant annex 17 in our
case, will be basically two electromagnetic showers one in the eagle
wanting the W Cal and the total energies to be just the energy of our union. CRP.
So it would block the energy on the Calvert Sudan and Uganda, but you can,
what signal books will be the gray region we have no signal like even says in the in
the 2017 plan indeed we have one compatible with a quality cuts for a
signal but it was out of our signal about three years. And the other point that you
can see here are basically neutral events and we know that they are neutral events
because we don't see any a charged particle indicator. What we can do is when
when we don't we have open our signal bowls, which are no events, basically what
we define is the region in the region in epsilon, which is the coupling to this to
this dark boson particle and the mass of the X 17. So, if x 17 comes from these
proto phobic origin with a particle of mass 17 mV which can explain them and you
know, normally the mass and the coupling should be in the region. So basically the
message is specs and we should cover the region in epsilon. And basically this is
the limit from any 64 using 2017 data compared also with predictions from other
experiment. So in 2017 when we bought our result, what we did was say okay, let's
try to optimize our setup to cover the remaining parameter space. So basically,
what we have to do to put us in context is to go to larger companies, which means
short lifetime particle
in order to improve our service on the region. Basically, what we did was several
improvements. So first of all, we change the beam energy from 100 to 150 Db to
really boost eco Dec 17 production outside the UK. Then we had a short interval you
can to prove better a shorter lifetime video. And then we add also a female veto
just after w can to be to minimize the probability that excellence indicates
moreover to improve our our Background suppression, what we did was to install a
vacuum pipe. And in addition, thanks a lot, we allowed to the distance between
the eagle, a and the Wk. And we had also some trackers. So after all these
improvements, this is our combined resource to use in 2017 and 2018 data. And
one thing that you have to keep in mind is epsilon as a function of the of the math.
So this will be the region, and 2017 is the dashed line. And basically, the
continuous line is improvement. After the 2018 data, we were able to collect a point
fourth into it then electronics on target. And basically thanks to improve on the
setup, we were able to really reach larger values of epsilon because otherwise our
our sensitivity would only increase nobody, luckily with the number of
electrons on that. So you can see here also the two signal box is for 2017 and
2018. As you can see on 2018 basically we'll have only three new tracks because
we improve a lot our back prediction with increase of the distance and also the
installation of the baquba. But this is not all from our side. So what we expect
to do is to continue around in 2021 we were already approved by SM SPS, and
basically what we plan to do is to really explore the remaining parameter space. So,
we will really want to see if this x 17 comes from a can explain the anomaly even
anomaly and try to cover the full parameter space. In addition, so, Tonkin
collaboration has recent also show new results. So, now, there are nuclei similar
to very similar process to what they observe the MRI you know, normally, but in
this case, you see a boom. So, this has also introduced an additional motivation
to have an independent measurement on these kind of anomalies and try to give a
definite answer. So, indeed, which are our plans for 2021. As I mentioned before, we
want to fully cover the parameter space, but what is missing? Bottom is like in
case that we see some signal like events, what we want to do, thanks a lot is to
really measure the embodied mass. So to be able to reconcile the volume bars for the
small coupling, what is the challenge is to be able to measure the angle and to
really measure the position energy of the blast in mind how we expect to do that
very simple, we want to do a more compact calorie meter, but keeping the number of
radiation dense, so we keep our energy solution and our stimulation of the
background. Then what we want to do is to a large vacuum tube where before our decay
region to really minimize the multiple scattering of the of the particles
produce. And finally, as a magnet, which we spent more than two hours, keep in mind
so we can really measure the separation of the two servers with the tragus And in
addition, measure the position on the electromagnetic calorimeter. We thought
this improvements we expect to be able to to see the environment reconstruction of
the past extracting candidate events with a precision of the 2%. I just come to my
summary very quickly. So I hope that they convinced you that that sector centrality
framework and a 6040 is an idea to to try to probe or rule out many candidates out
there is sort of our combined data in 2017 and 2018. With the 8.4 template and target
have been able to probe with Dec 17 hypotheses is planning they will normally
with koplin below 6.8 10 to the minus four and Amaz around 17. And our future
prospect is to cover completely the region and in case of signal like being able to
register the body mass with 2% precision. To do that, we have estimated we need 710
to the 11 electron targets at 100 gV which correspond roughly with three months of
data taking. And then this search also is expected to be bagging on free up to them
to AdWords. So thanks a lot for your attention and if you have questions
Thank you so much Lara for such a nice talk. Do we have a question from the
audience? So I know Katherine has a question. Please go ahead, Katherine.
Hey, yeah, this was a really, really interesting talk. Thank you so much. And
you go back to your slide 19. This nice. You have, I guess my first question here
is in terms of the area you've highlighted as remaining parameter space, it looks as
though quite a bit of that is within an exclusion curve for na 48 that you've
drawn on there. Is that yeah, that's relevant to this model as well. So it
would seem that maybe their parameter space is actually just a little bit
between any 40 year limit,
yes, or resale because of the bump that they did their model. Yes. But indeed,
they by meter spacing, really between any 48 down there. Yeah. This is basically
what you want to cover.
Yeah. Fantastic. My other question is about the interpretation that you're
using. I'm not so familiar with this. So I'm not sure how much overlap there is
between possible models that could give you the excess autonomy as observed and
the model that you are models that you would be sensitive to. So, are there are
there any sort of situations that would mean that you wouldn't be sensitive to the
same processes or is this pretty conclusive?
So, in principle, what we are what we can cover is basically they the regions where
we can go with the full region associated with explanation coming from this
protocol, because planation but also there are other models as we pointed out that
can explain the anomaly of the of the upset by atomic collaboration with other
kinds of particles have also a model so vector axial particles and indeed our idea
is also try to explore other other kinds of models in the in the next in the next
search. Fantastic. Thanks. Welcome.
I also have a question on this light. So is there any other experiments that are
also sensitive to this region or so to some of these uncover face to face? Yes,
or some of the other face space that is uncover.
So yeah, in principle, so these limits also, for example, the measurement of
alpha on the T minus two is going to get down the skirt. So it's going to explore
some part but for the moment for this particular region a find my where, well, I
think are the most sensitive to this. But I'm not 100% sure I know that they from
the minute to with that grade of the new alpha measurements, we are going to have
more constraint there and to really consider
Okay, thank you so much. And again, this
is all based on explanation of these. Yeah, of this protocol become more than
Okay, another movie
okay. Thank you so much louder. So we'll go to the discussion part of our session
then. And if you give me a minute, I will start projecting some slides.