standard model of particle physics

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Three Experiments Hint at Physics Beyond the Standard Model

The Standard Model of particle physics is a series of mathematical equations used to describe and predict the behaviour of all known particles and forces except gravity. These experiments call into question something known as lepton universality. A lepton is a type of fundamental, half-integer spin particle (spin being intrinsic angular momentum). Half-integer spin fermions are constrained by the Pauli exclusion principle while integer spin Bosons are not (fermions are subatomic particles with a half-integer spin while Bosons are force carrying particles with an integer spin). The Pauli exclusion principle says that two or more identical fermions cannot occupy the same quantum state within a quantum system. For example, if two electrons are on the same orbital with the same principal quantum number, angular momentum and magnetic quantum number values then they must have opposite half-integer spins of ½ and -½.

Lepton universality states that the interactions of these elementary particles are the same regardless of their different masses and lifetimes. The three experiments conducted were measuring the relative ratios of B meson decay. What they found was that the heavy tau lepton has a much higher decay rate when compared to the lighter electrons and muons than the standard model predicts. Together these experiments challenge lepton universality to a level of four standard deviations indicating a 99.95% certainty. However, to be sure that the standard model has to be revised a significance of at least five standard deviations is required.

Changing the Standard Model is no easy feat. Adaptations made to equations anywhere can easily have a knock on effect causing the maths elsewhere to stop making sense. However nothing is certain yet and these results may well be flawed.

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James. 22. Physics-major-turned-zookeeper. I’m starting T tomorrow and if an astrological phenomenon unseen in nearly 100 years isn’t a sign from the universe then I don’t know what is. I am H Y P E y'all~

Hmu for animal pictures (I’m the new primary emu keeper!!), discourse about the fragility of the standard model of particle physics, or anything else lol. Always looking for more trans friends ✌🏽

<3

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Break The Standard Model? An Ultra-Rare Decay Threatens To Do What The LHC Can’t

“Just by sitting around with a bunch of unstable atoms, waiting for them to decay and measuring the decay products to incredible accuracy, we have the potential to finally break the Standard Model. Neutrinos are already the one type of particle known to go beyond the original Standard Model predictions, with potential ties to dark matter, dark energy, and baryogenesis in addition to their mass problem. Discovering that they undergo this bizarre, never-before-seen decay would make them their own antiparticles, and would introduce Majorana Fermions into the real world. If nature is kind to us, a box full of radioactive material might at last do what the LHC can’t: shed light on some of the deepest, most fundamental mysteries about the nature of our Universe.”

Want to uncover the secrets to the Universe? Find out what particles and interactions there are beyond the Standard Model? The conventional approach is to take particles up to extremely high energies and smash them together, hoping that something new and exciting comes out. That’s a solid approach, but it has its limits. In particular, we haven’t seen anything new at the LHC other than the Higgs Boson, and might not even if we run it forever. But another, more subtle approach might yield heavy dividends: simply gathering a very large number of unstable atoms and looking for a special type of decay: neutrinoless double beta decay. If this decay actually occurs in nature, it would mean that neutrinos aren’t like the other particles we know of, but rather that neutrinos and antineutrinos are the same particles: Majorana particles!

What would all of this mean, and what would it teach us about our Universe? Find out about our simplest hope for going beyond the Standard Model today!

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Antimatter measured for the first time!!!

Scientists have managed to trap and measure antimatter for the first time. Physicists at CERN successfully managed to create and maintain antihydrogen for 15 minutes by combining positrons and antiprotons in a vacuum tube using extremely strong magnetic fields to prevent the antimatter from colliding with the regular matter of the container and annihilating. Positrons occupy different energy levels just like electrons in regular atoms. A laser was used to excite the antihydrogen causing the positrons to move to a higher energy level. Just like in regular atoms, when the positrons are shifting back to their original energy levels electromagnetic radiation in the form of light is given off. The results of the experiment show that antihydrogen absorbs and then reflects the same wavelengths of light as regular Hydrogen as predicted by the standard model. They are hoping to run more precise experiments but so far it looks like we won’t have to change our understanding of physics yet.

Top left image is antihydrogen atoms coming into consideration contact with the sides of the container, annihilating and giving of energy in the form of light.

Here is a link to the pdf of the experiment.

http://www.nature.com/nature/journal/vaap/ncurrent/full/nature21040.html

tomorrow is my last exam ever

and I don’t know how to feel about that. it’s an oral exam that can range from 15 to 60 minutes and covers my whole field of specialization.. which is A LOT (standard model of particle physics and detector physics). They could literally ask anything? The written exams on both went great and I think I know quite a bit about the field but the huge range if topics is a bit scary. And I don’t know how deep I have to know everything?

also i won’t have exams after that anymore? That has been like.. my whole life???

Five fiendish physics problems

1. Consider a perfectly spherical cow of 1 metre diameter and uniform density. This cow needs milking. How are you going to do it?

2. I am pointing a 15 MW laser at the back of your head right now. No, don’t turn around. I’m not asking you to solve this problem, I’m just suggesting that you do have a problem here and asking you to acknowledge it. I probably won’t turn the laser on.

3. Derive Maxwell’s equations. To do this, you will need to use the fundamental constants pi and c. Note: both of these constants are hungry and one of them needs a wee. Your derivation will probably proceed much more smoothly if you can sort out their needs first.  

4. Consider two trains of mass m speeding towards each other. Train 1 is travelling at 50% of the speed of light, and train 2 at 20% of the speed of light. You are a passenger on train 2. Roughly how much energy will be released when they crash, and don’t you think you’d better find a way to get off before answering this question?

5. You are in a Hollywood film in which Love is postulated as the fifth fundamental force. Derive a plausible extension of the Standard Model of particle physics to include the Love Force, based on its observed effects at a macro level (flushed cheeks, hormonal release, last-minute assignations in airports, etc.).

Scientists Are Using the Universe as a “Cosmological Collider”


Physicists are capitalizing on a direct connection between the largest cosmic structures and the smallest known objects to use the universe as a “cosmological collider” and investigate new physics.

The three-dimensional map of galaxies throughout the cosmos and the leftover radiation from the Big Bang – called the cosmic microwave background (CMB) – are the largest structures in the universe that astrophysicists observe using telescopes. Subatomic elementary particles, on the other hand, are the smallest known objects in the universe that particle physicists study using particle colliders.

A team including Xingang Chen of the Harvard-Smithsonian Center for Astrophysics (CfA), Yi Wang from the Hong Kong University of Science and Technology (HKUST) and Zhong-Zhi Xianyu from the Center for Mathematical Sciences and Applications at Harvard University has used these extremes of size to probe fundamental physics in an innovative way. They have shown how the properties of the elementary particles in the Standard Model of particle physics may be inferred by studying the largest cosmic structures. This connection is made through a process called cosmic inflation.

Cosmic inflation is the most widely accepted theoretical scenario to explain what preceded the Big Bang. This theory predicts that the size of the universe expanded at an extraordinary and accelerating rate in the first fleeting fraction of a second after the universe was created. It was a highly energetic event, during which all particles in the universe were created and interacted with each other. This is similar to the environment physicists try to create in ground-based colliders, with the exception that its energy can be 10 billion times larger than any colliders that humans can build.

Inflation was followed by the Big Bang, where the cosmos continued to expand for more than 13 billion years, but the expansion rate slowed down with time. Microscopic structures created in these energetic events got stretched across the universe, resulting in regions that were slightly denser or less dense than surrounding areas in the otherwise very homogeneous early universe. As the universe evolved, the denser regions attracted more and more matter due to gravity. Eventually, the initial microscopic structures seeded the large-scale structure of our universe, and determined the locations of galaxies throughout the cosmos.

In ground-based colliders, physicists and engineers build instruments to read the results of the colliding events. The question is then how we should read the results of the cosmological collider.

“Several years ago, Yi Wang and I, Nima Arkani-Hamed and Juan Maldacena from the Institute of Advanced Study, and several other groups, discovered that the results of this cosmological collider are encoded in the statistics of the initial microscopic structures. As time passes, they become imprinted in the statistics of the spatial distribution of the universe’s contents, such as galaxies and the cosmic microwave background, that we observe today,” said Xingang Chen. “By studying the properties of these statistics we can learn more about the properties of elementary particles.”

As in ground-based colliders, before scientists explore new physics, it is crucial to understand the behavior of known fundamental particles in this cosmological collider, as described by the Standard Model of particle physics.

“The relative number of fundamental particles that have different masses – what we call the mass spectrum – in the Standard Model has a special pattern, which can be viewed as the fingerprint of the Standard Model,” explained Zhong-Zhi Xiangyu. “However, this fingerprint changes as the environment changes, and would have looked very different at the time of inflation from how it looks now.”

The team showed what the mass spectrum of the Standard Model would look like for different inflation models. They also showed how this mass spectrum is imprinted in the appearance of the large-scale structure of our universe. This study paves the way for the future discovery of new physics.

“The ongoing observations of the CMB and large-scale structure have achieved impressive precision from which valuable information about the initial microscopic structures can be extracted,” said Yi Wang. “In this cosmological collider, any observational signal that deviates from that expected for particles in the Standard Model would then be a sign of new physics.”

The current research is only a small step towards an exciting era when precision cosmology will show its full power.

“If we are lucky enough to observe these imprints, we would not only be able to study particle physics and fundamental principles in the early universe, but also better understand cosmic inflation itself. In this regard, there are still a whole universe of mysteries to be explored,” said Xianyu.

This research is detailed in a paper published in the journal Physical Review Letters on June 29, 2017, and the preprint is available online.

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Where is new physics hiding, and how can we find it?

“Strictly speaking, it isn’t the mass that is relevant to the question whether a particle can be discovered, but the energy necessary to produce the particles, which includes binding energy. An interaction like the strong nuclear force, for example, displays “confinement” which means that it takes a lot of energy to tear quarks apart even though their masses are not all that large. Hence, quarks could have constituents – often called “preons” – that have an interaction – dubbed “technicolor” – similar to the strong nuclear force.”

The Standard Model plus General Relativity gives tremendous successes, and has so far accurately described every small-scale, quantum interaction (for the Standard Model) and every gravitational phenomenon (for General Relativity) ever tested, measured or observed. Yet there are still a whole host of unanswered questions about physics, including the puzzles of dark matter, dark energy, strong CP-violation, neutrino masses, baryogenesis, quantum gravity and more. We aren’t simply relegated, however, to looking for these answers at the LHC or other high-energy colliders. There are also insights from weak coupling and large statistics, high precision and indirect measurements, tabletop experiments, cosmic scale features and more.

Sabine Hossenfelder has the full scoop on where new physics might be hiding, and how we intend to find it anyway!

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Could No New Particles At The LHC Be Exactly What Physics Needs?

“That’s why I’d love it if the bump goes away. Because it would be a clear signal that we’ve been doing something seriously wrong, that our experience from constructing the standard model is no longer a promising direction to continue.

We already know we’ve been doing something wrong – bump or no bump – because naturalness has gone out the window. But if the bump stays, chances are we’d try to absorb it into the mathematics we already have rather than look for something really new. Sometimes things have to get really bad before they can get better. That’s why for me no-bump is the most hopeful outcome.”

At the end of its second, high-energy run, the Large Hadron Collider appeared to display evidence that perhaps a new particle existed at an energy of 750 GeV. The excess of twin photons produced at that energy appeared in both the ATLAS and CMS detectors, and might indicate the first particle beyond the standard model. It might also be a little-understood feature of the standard model itself, or — perhaps most likely — it may be merely statistical noise. But perhaps the ‘nightmare scenario’ of no new particles is exactly what physics needs, to divert us away from the dead ends of naturalness, elegance, unification and greater and greater symmetries, which have borne no experimental fruits in more than 40 years.

Flavour vs Family vs Generation 

You have your quarks and leptons: 

There are 12 flavours. You can think of it as 12 types since the word flavour doesn’t have a significant meaning, it’s just refering to the 12 different types of quarks and leptons. There’s 6 quark flavours, 6 lepton flavours, for a total of 12 flavours. You can also refer to the neutrinos as 3 neutrino flavours, since there’s 3 types of neutrinos. 

Then you got your generations, aka families. They mean the same thing. See the top quarks is just a heavier version of the charm quark which is just a heavier up quark, so the up quark is part of the 1st generation (orange background), the charm is part of the 2nd generation (green background), the top is part of the 3rd generation (blue background). 

Same with the other ones, the bottom quark is a heavier strange quark is a heavier down quark; the tau is a heavier muon is a heavier electron (as for the neutrinos, we’re not too sure about neutrino masses yet). There’s no difference in interaction (again with exceptions) or properties like charge or spin between generations, they’re just heavier and less stable (ie. will easily decay) versions of the first generation. Because the 2nd and 3rd generations tend to decay into the 1st generation, protons and neutrons are made of up and down quarks, with an electron orbiting it (as oposed to a muon or tau) (again the neutrinos are weird). 

Dark Matter Particle Could be Size of Human Cell

Dark matter could be made of particles that each weigh almost as much as a human cell and are nearly dense enough to become miniature black holes, new research suggests.

While dark matter is thought to make up five-sixths of all matter in the universe, scientists don’t know what this strange stuff is made of. True to its name, dark matter is invisible — it does not emit, reflect or even block light. As a result, dark matter can currently be studied only through its gravitational effects on normal matter. The nature of dark matter is currently one of the greatest mysteries in science.

If dark matter is made of such superheavy particles, astronomers could detect evidence of them in the afterglow of the Big Bang, the authors of a new research study said.

Previous dark matter research has mostly ruled out all known ordinary materials as candidates for what makes up this mysterious stuff. Gravitational effects attributed to dark matter include the orbital motions of galaxies: The combined mass of the visible matter in a galaxy, such as stars and gas clouds, cannot account for a galaxy’s motion, so an additional, invisible mass must be present. The consensus so far among scientists is that this missing mass is made up of a new species of particles that interact only very weakly with ordinary matter. These new particles would exist outside the Standard Model of particle physics, which is the best current description of the subatomic world.

Some dark matter models suggest that this cosmic substance is made of weakly interacting massive particles, or WIMPs, that are thought to be about 100 times the mass of a proton, said study co-author McCullen Sandora, a cosmologist at the University of Southern Denmark. However, despite many searches, researchers have not conclusively detected any WIMPs so far, leaving open the possibility that dark matter particles could be made of something significantly different.

Now Sandora and his colleagues are exploring the upper mass limit of dark matter — that is, they’re trying to discover just how massive these individual particles could possibly be, based on what scientists know about them. In this new model, known as Planckian interacting dark matter, each of the weakly interacting particles weighs about 1019 or 10 billion billion times more than a proton, or “about as heavy as a particle can be before it becomes a miniature black hole,” Sandora said.

A particle that is 1019 the mass of a proton weighs about 1 microgram. In comparison, research suggests that a typical human cell weighs about 3.5 micrograms.

The genesis of the idea for these supermassive particles “began with a feeling of despondency that the ongoing efforts to produce or detect WIMPs don’t seem to be yielding any promising clues,” Sandora said. “We can’t rule out the WIMP scenario yet, but with each passing year, it’s getting more and more suspect that we haven’t been able to achieve this yet. In fact, so far there have been no definitive hints that there is any new physics beyond the Standard Model at any accessible energy scales, so we were driven to think of the ultimate limit to this scenario.”

At first, Sandora and his colleagues regarded their idea as little more than a curiosity, since the hypothetical particle’s massive nature meant that there was no way any particle collider on Earth could produce it and prove (or refute) its existence.


But now the researchers have suggested that if these particles exist, signs of their existence might be detectable in the cosmic microwave background radiation, the afterglow of the Big Bang that created the universe about 13.8 billion years ago.

Currently, the prevailing view in cosmology is that moments after the Big Bang, the universe grew gigantically in size. This enormous growth spurt, called inflation, would have smoothed out the cosmos, explaining why it now looks mostly similar in every direction.

After inflation ended, research suggests that the leftover energy heated the newborn universe during an epoch called “reheating.” Sandora and his colleagues suggest that extreme temperatures generated during reheating could have produced large amounts of their superheavy particles, enough to explain dark matter’s current gravitational effects on the universe.

However, for this model to work, the heat during reheating would have had to be significantly higher than what is typically assumed in universal models. A hotter reheating would in turn leave a signature in the cosmic microwave background radiation that the next generation of cosmic microwave background experiments could detect. “All this will happen within the next few years hopefully, next decade, max,” Sandora said.

If dark matter is made of these superheavy particles, such a discovery would not only shed light on the nature of most of the universe’s matter, but also yield insights into the nature of inflation and how it started and stopped — all of which remains highly uncertain, the researchers said.

For example, if dark matter is made of these superheavy particles, that reveals “that inflation happened at a very high energy, which in turn means that it was able to produce not just fluctuations in the temperature of the early universe, but also in space-time itself, in the form of gravitational waves,” Sandora said. “Second, it tells us that the energy of inflation had to decay into matter extremely rapidly, because if it had taken too long, the universe would have cooled to the point where it would not have been able to produce any Planckian interacting dark matter particles at all.”

Sandora and his colleagues detailed their findings online March 10 in the journal Physical Review Letters.

SYNNETRY MAGAZINE


Scientists make rare achievement in study of antimatter


10/19/17

|By Kimber Price

Through hard work, ingenuity and a little cooperation from nature, scientists on the BASE experiment vastly improved their measurement of a property of protons and antiprotons.

Scientists at CERN are celebrating a recent, rare achievement in precision physics: Collaborators on the BASE experiment measured a property of antimatter 350 times as precisely as it had ever been measured before.

The BASE experiment looks for undiscovered differences between protons and their antimatter counterparts, antiprotons. The result, published in the journal Nature, uncovered no such difference, but BASE scientists say they are hopeful the leap in the effectiveness of their measurement has potentially brought them closer to a discovery.

“According to our understanding of the Standard Model [of particle physics], the Big Bang should have created exactly the same amount of matter and antimatter, but [for the most part] only matter remains,” says BASE Spokesperson Stefan Ulmer. This is strange because when matter and antimatter meet, they annihilate one another. Scientists want to know how matter came to dominate our universe.

“One strategy to try to get hints to understand the mechanisms behind this matter-antimatter symmetry is to compare the fundamental properties of matter and antimatter particles with ultra-high precision,” Ulmer says.

Scientists on the BASE experiment study a property called the magnetic moment. The magnetic moment is an intrinsic value of particles such as protons and antiprotons that determines how they will orient in a magnetic field, like a compass. Protons and antiprotons should behave exactly the same, other than their charge and direction of orientation; any differences in how they respond to the laws of physics could help explain why our universe is made mostly of matter.

This is a challenging measurement to make with a proton. Measuring the magnetic moment of an antiproton is an even bigger task. To prevent antiprotons from coming into contact with matter and annihilating, scientists need to house them in special electromagnetic traps.

While antiprotons generally last less than a second, the ones used in this study were placed in a unique reservoir trap in 2015 and used one by one, as needed, for experiments. The trapped antimatter survived for more than 400 days.

During the last year, Ulmer and his team worked to improve the precision of the most sophisticated technqiues developed for this measurement in the last decade.

They did this by improving thier cooling methods. Antiprotons at temperatures close to absolute zero move less than room-temperature ones, making them easier to measure.

Previously, BASE scientists had cooled each individual antiproton before measuring it and moving on to the next. With the improved trap, the antiprotons stayed cool long enough for the scientists to swap an antiproton for a new one as soon as it became too hot.

“Developing an instrument stable enough to keep the antiproton close to absolute zero for 4-5 days was the major goal,” says Christian Smorra, the first author of the study.

This allowed them to collect data more rapidly than ever before. Combining this instrument with a new technique that measures two particles simultaneously allowed them to break their own record from last year’s measurement by a longshot.

“This is very rare in precision physics, where experimental efforts report on factors of greater than 100 magnitude in improvement,” Ulmer says.

The results confirm that the two particles behave exactly the same, as the laws of physics would predict. So the mystery of the imbalance between matter and antimatter remains.

Ulmer says that the group will continue to improve the precision of their work. He says that, in five to 10 years, they should be able to make a measurement at least twice as precise as this latest one. It could be within this range that they will be able to detect subtle differences between protons and antiprotons.

“Antimatter is a very unique probe,” Ulmer says. “It kind of watches the universe through very different glasses than any matter experiments. With antimatter research, we may be the only ones to uncover physics treasures that would help explain why we don’t have antimatter anymore.”

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Why is it so hard to find a new particle?

“The success of the Standard Model is both a blessing and a curse. It’s a blessing that we’ve uncovered a theory that describes nature so well, and that appears to work for all the particle decays and interactions we’ve ever seen so far. But it’s a curse, in that we know there must be more Universe out there, as there are questions the Standard Model can’t answer.”

When it comes to physics, there are a tremendous number of unsolved problems that seem to mandate the existence of a new particle. These include the dark matter problem, the matter-antimatter asymmetry problem, the massive neutrino problem and the strong-CP problem. Moreover, these particles required cannot be part of the Standard Model: they must lie beyond it. Yet not only have detectors and colliders failed to turn up anything new despite 50 years of searches, but most models that would solve these problems are theoretically doomed from the start. Constraints on what new physics could do from big bang nucleosynthesis and the lack of observed flavor-changing neutral currents forbid almost all of the theoretical models we can build.

CWRU Theoretical Physicists Suggest Dark Matter May Be Massive

In a new study, theoretical physicists from Case Western Reserve University suggest that dark matter may be massive and that the Standard Model may account for it.

The physics community has spent three decades searching for and finding no evidence that dark matter is made of tiny exotic particles. Case Western Reserve University theoretical physicists suggest researchers consider looking for candidates more in the ordinary realm and, well, more massive.

Dark matter is unseen matter, that, combined with normal matter, could create the gravity that, among other things, prevents spinning galaxies from flying apart. Physicists calculate that dark matter comprises 27 percent of the universe; normal matter 5 percent.

Instead of WIMPS, weakly interacting massive particles, or axions, which are weakly interacting low-mass particles, dark matter may be made of macroscopic objects, anywhere from a few ounces to the size of a good asteroid, and probably as dense as a neutron star, or the nucleus of an atom, the researchers suggest.

Physics professor Glenn Starkman and David Jacobs, who received his PhD in Physics from CWRU in May and is now a fellow at the University of Cape Town, say published observations provide guidance, limiting where to look. They lay out the possibilities in a paper listed below.

The Macros, as Starkman and Jacobs call them, would not only dwarf WIMPS and axions, but differ in an important way. They could potentially be assembled out of particles in the Standard Model of particle physics instead of requiring new physics to explain their existence.

“We’ve been looking for WIMPs for a long time and haven’t seen them,” Starkman said. “We expected to make WIMPS in the Large Hadron Collider, and we haven’t.”

WIMPS and axions remain possible candidates for dark matter, but there’s reason to search elsewhere, the theorists argue.

“The community had kind of turned away from the idea that dark matter could be made of normal-ish stuff in the late ’80s,” Starkman said. “We ask, was that completely correct and how do we know dark matter isn’t more ordinary stuff— stuff that could be made from quarks and electrons?”

After eliminating most ordinary matter, including failed Jupiters, white dwarfs, neutron stars, stellar black holes, the black holes in centers of galaxies and neutrinos with a lot of mass, as possible candidates, physicists turned their focus on the exotics.

Matter that was somewhere in between ordinary and exotic—relatives of neutron stars or large nuclei—was left on the table, Starkman said. “We say relatives because they probably have a considerable admixture of strange quarks, which are made in accelerators and ordinarily have extremely short lives,” he said.

Although strange quarks are highly unstable, Starkman points out that neutrons are also highly unstable. But in helium, bound with stable protons, neutrons remain stable.

“That opens the possibility that stable strange nuclear matter was made in the early universe and dark matter is nothing more than chunks of strange nuclear matter or other bound states of quarks, or of baryons, which are themselves made of quarks,” he said. Such dark matter would fit the Standard Model.

The Macros would have to be assembled from ordinary and strange quarks or baryons before the strange quarks or baryons decay, and at a temperature above 3.5 trillion degrees Celsius, comparable to the temperature in the center of a massive supernova, Starkman and Jacobs calculated. The quarks would have to be assembled with 90 percent efficiency, leaving just 10 percent to form the protons and neutrons found in the universe today.

The limits of the possible dark matter are as follows:

  • A minimum of 55 grams. If dark matter were smaller, it would have been seen in detectors in Skylab or in tracks found in sheets of mica.
  • A maximum of 1024 (a million billion billion) grams. Above this, the Macros would be so massive they would bend starlight, which has not been seen.
  • The range of 1017 to 1020 grams per centimeter squared should also be eliminated from the search, the theorists say. Dark matter in that range would be massive for gravitational lensing to affect individual photons from gamma ray bursts in ways that have not been seen.

If dark matter is within this allowed range, there are reasons it hasn’t been seen.

  • At the mass of 1018 grams, dark matter Macros would hit the Earth about once every billion years.
  • At lower masses, they would strike the Earth more frequently but might not leave a recognizable record or observable mark.
  • In the range of 109 to 1018, dark matter would collide with the Earth once annually, providing nothing to the underground dark matter detectors in place.
youtube

Step Inside the World’s Largest Particle Accelerator in This 360-Degree Video

Recently, the BBC got to take a tour inside the largest particle physics laboratory in the world. Thankfully, it brought virtual reality cameras with it, providing an awesome tour.

To utilize the 360-degree features, simply drag your cursor around in the video to look up, down, and sideways. At the end, you get a sense of just how giant the LHC is, which makes discoveries like the one in 2012 possible. Back then, the collider detected the sub-atomic Higgs boson particle, a cornerstone of the Standard Model theory, which explains how particles interact.  

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New LHC Results Hint At New Physics… But Are We Crying Wolf?

“What we’re seeing right now is a response from the community is what we’d expect to an alarm that’s crying “Wolf!” There might be something fantastic and impressive out there, and so, of course we have to look. But we know that, more than 99% of the time, an alarm like this is merely the result of which way the wind blew. Physicists are so bored and so out of good, testable ideas to extend the Standard Model – which is to say, the Standard Model is so maddeningly successful – that even a paltry result like this is enough to shift the theoretical direction of the field.”

The Standard Model of particle physics – with its six quarks in three colors, its three generations of charged leptons and neutrinos, the antiparticle counterparts to each, and its thirteen bosons, including the Higgs – describes all the known particles and their interactions in the Universe. This extends to every experiment ever performed in every particle accelerator. In short, this is a problem: there’s no clear path to what new physics lies beyond the Standard Model. So physicists are looking for any possible anomalies at all, at any theoretical ideas that lead to new predictions at the frontiers, and any experimental result that differs from the Standard Model predictions. Unfortunately, we’re looking at thousands of different composite particles, decays, branching ratios, and scattering amplitudes. Our standards for what’s a robust measurement and a compelling result need to be extremely high.

The newest LHCb results offer a hint of something interesting, but it’s got a long way to go before we can say we’ve discovered anything new. Come find out what we’ve seen today!

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Will the LHC be the end of experimental particle physics?

“It’s no stretch to predict that you’re going to see a flurry of articles, presentations and talks over the coming few years on the topic of, “Have we found the first signs of particle physics beyond the Standard Model?”

And if the answer is, “not definitively,” have this be the takeaway: the Standard Model might be all our particle colliders can access in our lifetime. ”

At the end of the 19th century, Lord Kelvin famously said, “There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.” He was talking about how Newtonian gravity and Maxwell’s electromagnetism seemed to account for all the known phenomena in the Universe. Of course, nuclear physics, quantum mechanics, general relativity and more made that prediction look silly in hindsight. But in the 21st century, the physics of the Standard Model describes our Universe so well that there truly may be nothing else new to find not only at the LHC, but at any high-energy particle collider we could build here on Earth.