Probing the Dark Matter Direct Detection Blind Spot Scenario Using Directional Detection

Kenny Buffo Author

04/06/2021 Added

19 Plays

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Discussion of research as it pertains to experimental dark matter detection and theoretical extensions to probe current blind spot scenarios.

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[00:00:01.430]Hello, my name is Kenny Buffo,
[00:00:03.170]and today I'd like to talk to you
[00:00:04.460]about an ongoing research project
[00:00:06.660]that I am conducting alongside my advisor,
[00:00:09.220]Dr. Peisi Huang, a member of the High-Energy Physics group
[00:00:12.950]here at UNL.
[00:00:15.120]My research is a theoretical study of the blind spot regions
[00:00:18.750]that occur in attempting direct detection
[00:00:21.530]of dark matter and how we can resolve them.
[00:00:25.060]But what exactly is dark matter?
[00:00:29.600]Dark matter is a form of matter
[00:00:31.610]that is unlike ordinary matter
[00:00:33.190]or what physicists call baryonic matter.
[00:00:36.250]Baryonic matter is the type of matter that we see,
[00:00:38.930]feel, and experience in our everyday lives.
[00:00:42.650]Anything that's composed of atoms,
[00:00:44.370]including protons and neutrons, is baryonic matter.
[00:00:48.520]However, dark matter behaves very differently
[00:00:50.940]than the baryonic matter that we're used to.
[00:00:53.630]Evidence of its existence comes
[00:00:55.230]from calculations done on the mass distribution
[00:00:57.890]of distant galaxies.
[00:01:00.270]Astronomers found that the baryonic matter present
[00:01:02.780]in things like stars attributed to only small percentages
[00:01:06.950]of the mass needed in order to keep the stars
[00:01:09.240]from flying away outside the galaxies' reach.
[00:01:13.340]So we know that this mysterious matter
[00:01:15.220]interacts with normal matter via the gravitational force,
[00:01:19.640]but currently, it has never been directly seen.
[00:01:23.240]This is because it does not seem to interact
[00:01:25.140]with electromagnetic radiation,
[00:01:27.250]meaning it does not reflect light or absorb light,
[00:01:30.210]hence the name dark matter.
[00:01:33.680]This study of galaxies implied
[00:01:35.240]that there must be something else present in our universe,
[00:01:38.060]and a lot of it to keep everything in check.
[00:01:41.900]Current models that parameterize the Big Bang
[00:01:44.220]tell us that only about 5%
[00:01:45.620]of the universe's mass energy content is baryonic.
[00:01:50.170]This leaves a much larger portion
[00:01:51.970]to be made up of dark matter,
[00:01:53.720]and even more abundantly by dark energy.
[00:01:56.740]Dark energy is an even stranger phenomenon
[00:01:59.630]that is thought to cause the accelerating expansion
[00:02:02.330]of the universe.
[00:02:09.830]So what's the purpose of studying it?
[00:02:12.190]Why does dark matter?
[00:02:15.620]Well, particle physicists tend to make use
[00:02:18.590]of something that's referred to as the Standard Model
[00:02:21.000]when making predictions of physical events.
[00:02:23.700]The Standard Model describes three
[00:02:25.360]of the four fundamental forces, including electromagnetism,
[00:02:29.470]and the strong and weak nuclear forces.
[00:02:31.920]It currently excludes gravity.
[00:02:34.710]The Standard Model also classifies
[00:02:36.490]all the known elementary particles.
[00:02:39.100]An elementary particle is a particle
[00:02:41.440]that cannot be broken down further
[00:02:42.960]into constituent entities.
[00:02:46.530]The Standard Model lays out the rules
[00:02:48.950]that govern how these basic building blocks can interact
[00:02:52.250]and thus encompass nearly every physical process we know of.
[00:02:56.690]It is also highly accurate in its predictions,
[00:02:59.360]making it one of the most important constructions
[00:03:02.420]of 20th century physics.
[00:03:06.670]However, the Standard Model is currently incomplete.
[00:03:09.840]It does not describe dark matter,
[00:03:11.480]particularly what it's made up of
[00:03:13.480]and the rules that govern its interaction
[00:03:15.230]with other particles.
[00:03:16.840]Herein lies the motivation to devise a way
[00:03:19.220]of detecting dark matter.
[00:03:21.240]But how is it done?
[00:03:26.800]A very popular method is known as direct detection.
[00:03:29.940]These experiments aim to observe direct interactions
[00:03:32.930]between dark matter particles and ordinary matter.
[00:03:35.930]One of the most prominent ongoing experiments
[00:03:38.320]is the XENON collaboration.
[00:03:40.700]In these experiments,
[00:03:41.740]researchers place large tubes filled with xenon gas
[00:03:44.620]deep underground to filter out noise
[00:03:46.560]from unwanted detections.
[00:03:49.260]The idea is that an incoming dark matter particle
[00:03:51.770]would transfer a tiny amount of energy
[00:03:53.750]when coming into contact with the gas.
[00:03:57.330]This would cause a scintillation,
[00:03:59.230]or sudden flash of light as a property of xenon.
[00:04:03.440]Researchers can then detect these flashes
[00:04:05.660]within a tube to detect events.
[00:04:13.990]The most recent data from the XENON1T experiment
[00:04:17.260]on spin-independent dark matter is shown on the left.
[00:04:21.360]The abscissa denotes
[00:04:22.930]the possible dark matter particle mass,
[00:04:26.120]while the ordinate shows the nuclear cross-section
[00:04:29.680]of detection.
[00:04:31.120]The cross-section is directly related to the probability
[00:04:34.070]of detecting an event at that cross-section.
[00:04:37.390]This means the higher the cross-section,
[00:04:39.610]the more likely we are to see an event take place
[00:04:42.090]within the detector.
[00:04:44.870]This green band shows the current limit
[00:04:48.170]of the probed parameter space or cross-section
[00:04:52.090]that XENON has achieved.
[00:04:54.140]From this, we know that events will not take place
[00:04:57.060]above this line,
[00:05:00.000]but this still leaves this area below unprobed.
[00:05:05.500]Let us now turn our attention to the graph on the right,
[00:05:08.370]which comes from a paper published by Dr. Huang, my adviser.
[00:05:12.250]This graph describes the cross-section
[00:05:14.020]as it relates to the Higgs boson pseudoscalar mass
[00:05:17.540]under a new proposed model that extends the Standard Model.
[00:05:22.292]We see that at certain masses
[00:05:23.230]of the Higgs pseudoscalar mass,
[00:05:25.700]around 1000 giga electron volts in this graph,
[00:05:30.650]that the cross-section drops completely,
[00:05:33.140]meaning we would not find any events at this mass.
[00:05:36.360]These are referred to as blind spots,
[00:05:38.720]as experiments such as XENON
[00:05:42.034]would not be able to detect events under these conditions.
[00:05:45.680]A large portion of my research
[00:05:47.460]has been dedicated to studying the most recent data
[00:05:50.320]of spin-independent direct detection experiments
[00:05:53.870]along with the current prominent theories
[00:05:56.070]that describe the dark matter particle.
[00:06:01.997]Currently, I have been studying
[00:06:03.409]the Minimal Supersymmetric Standard Model
[00:06:06.108]and how these blind spots arise within it.
[00:06:08.955]This has required me to learn a lot
[00:06:10.492]of new theoretical physics along with multiple descriptions
[00:06:13.090]of extending the Standard Model.
[00:06:16.507]However, in order to find a way
[00:06:17.810]to probe these blind spot regions,
[00:06:20.853]I have begun using software
[00:06:21.686]to study the outcomes of these models
[00:06:24.997]and how that characterizes the dark matter particle.
[00:06:36.428]MicrOMEGAS is a software that allows
[00:06:38.735]for the study of dark matter.
[00:06:40.982]In particular, it allows me to study a specific model
[00:06:44.107]that extends the Standard Model,
[00:06:46.371]then input parameters to characterize a scenario
[00:06:49.381]within that model.
[00:06:51.891]For instance, here we see that I have set values
[00:06:54.267]for things like the Higgs mixing parameter,
[00:06:57.535]the light and heavy Higgs boson, and so on,
[00:07:00.274]all within this text file.
[00:07:03.063]Then the software does calculations
[00:07:05.290]to simulate the Minimal Supersymmetric Model, in this case.
[00:07:10.142]Finally, it outputs a lot of useful information,
[00:07:12.946]such as here we can see the breakdown of the composition
[00:07:15.651]of the dark matter particle into its constituent components.
[00:07:21.147]We can even determine if the calculated dark matter particle
[00:07:24.118]fits within the limit set by the XENON experiment.
[00:07:28.060]As seen here, it is excluded by the XENON1T experiment data
[00:07:33.836]from 2018, which means
[00:07:35.783]that this proposed dark matter particle
[00:07:38.255]would not be a good candidate
[00:07:44.947]To probe the blind spots,
[00:07:46.400]I am currently configuring the software to allow
[00:07:48.442]for directional detection as well.
[00:07:51.426]This means that the number of detected events
[00:07:54.966]will depend on the direction
[00:07:56.968]the incident dark matter particle comes from.
[00:07:59.997]My advisor and I also have plans
[00:08:01.790]to expand this to other models.
[00:08:10.087]Here's a list of my references,
[00:08:11.706]and I'd like to thank you for your time,
[00:08:13.453]and hope you enjoyed watching.

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Probing the Dark Matter Direct Detection Blind Spot Scenario Using Directional Detection

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