http://arxiv.org/abs/1411.4849 Two structures are observed close to the kinematic threshold in the Ξ0bπ− mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb−1 recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content bds are expected in this mass region: the spin-parity JP=12+ and JP=32+ states, denoted Ξ′−b and Ξ∗−b. Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be m(Ξ′−b)−m(Ξ0b)−m(π−)=3.653±0.018±0.006 MeV/c2, m(Ξ∗−b)−m(Ξ0b)−m(π−)=23.96±0.12±0.06 MeV/c2, Γ(Ξ∗−b)=1.65±0.31±0.10 MeV, where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of Γ(Ξ′−b)<0.08 MeV at 95% confidence level. Relative production rates of these states are also reported. ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
from...... http://www.iflscience.com/physics/two-new-particles-discovered-worlds-largest-collider Two never-before-seen particles have just been detected at CERN’s Large Hadron Collider, the world’s largest particle accelerator, by the international LHCb collaboration. Known as Xi_b'- and Xi_b*-, the new particles belong to the baryon family. Baryons are made from three fundamental, subatomic particles called quarks, bound together by a strong force. The more familiar protons and neutrons are also baryons -- these combine with electrons to make up everything on the periodic table. “The building blocks of all known things, including cars, planets, stars and people, are quarks and electrons, which are tied together by strong, electromagnetic forces,” Steven Blusk of Syracuse University explains in a news release. And the quarks in these newly discovered baryons aren’t even the same type: Each of the new particles contains one beauty (b), one strange (s), and one down (d) quark. The new particles are more than six times as massive as a proton, thanks to their heavyweight b quarks and their angular momentum -- a particular attribute of quarks known as “spin.” In the Xi_b'- state, the spins of the two lighter quarks point in the opposite direction to the b quark, and in the Xi_b*- state, the spins are aligned. This difference in configuration makes Xi_b*- a little heavier. “Nature was kind and gave us two particles for the price of one," says Matthew Charles of the CNRS's LPNHE laboratory at Paris VI University in a CERN statement. "The Xi_b'- is very close in mass to the sum of its decay products: If it had been just a little lighter, we wouldn't have seen it at all using the decay signature that we were looking for.” But thanks to the sensitivity and precision of the LHCb detector, Blusk adds, “we’ve been able to separate a clean, strong signal from the background.” In addition to the masses of the new particles, the team also studied their relative production rates, their widths (a measurement of how unstable they are), and a few other details of their decays. The new baryons are very short-lived, CBC explains, lasting only a thousandth of a billionth of a second before breaking up into five smaller pieces. The existence of these particles were previously predicted in 2009, but no one has ever seen them until now. Right after the findings were released online this week, "I saw the title [and] I thought, 'Oh, I predicted those -- I wonder how it turned out?" Randy Lewis of York University tells CBC. "I looked up their numbers and I said, 'Yeah, that looks a lot like what I predicted -- great!" Lewis and colleagues predicted the mass and composition of the new particles based on mathematical rules for how quarks behave. The findings are available through arXiv and will be published in Physical Review Letters. :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Something else for us all to be thankful for, and just in time. Thanks, paddoboy. cosmictraveler: Both new particles are very massive, which explains why it would have been unlikely that any previous collider or instrument would have ever detected them before. It was literally all Fermilab's Tevatron could do to discover the top quark, near the highest energies possible for them to achieve. The impressive first runs of this fine instrument that is the LHC were well worth many times the initial investment, for finally getting the basic science right, if for no other reason. No surprise, these new particles did not simply drop out of the mathematics from anyone's notebooks before the experimentalists found them first. They do not seem to fit into any supersymmetry predictions yet either. The instances of new particles and physics being predicted from first principles is greatly reduced when first rate physics like the papers from Higgs, Englert, Brout, Guralnik, Hagen and Kibble are simply ignored, disbelieved and gather dust on bookshelves for 50 years while new theories with no bindings to experiments or reality are hatched which are impossible to test. No doubt, there were lots of other good physics ideas unjustly relegated to this fate. Notice these particles are likewise made of quarks. Two more reasons why the Higgs discovery is the most important one in the history of the human race and basic science, far surpassing events like the Apollo moon landing in sheer technical and computative sophistication. The inertial masses of the new particles theoretically come from the Higgs mechanism also.
Any idea of how much of the universe is made up of this new kind of matter? Or is it just produced in the LHC?
Essentially none of it. They have lifetimes of one thousand-billionth of a second - that's \(10^{-12}\) s. So, if any are produced naturally they very quickly decay. And so... They had to be created before they could be found. You wouldn't find any just floating around in space.
Thanks. Looking at half-lives it has come to my notice that some of the numerical elements have now got real names. 100Fermium257Fm100.5 daysIsotopes of fermium 101Mendelevium258Md51.5 daysIsotopes of mendelevium 102Nobelium259No58 minutesIsotopes of nobelium 103Lawrencium266Lr~11 hoursIsotopes of lawrencium 104Rutherfordium267Rf~1.3 hoursIsotopes of rutherfordium 105Dubnium268Db1.3 daysIsotopes of dubnium 106Seaborgium269Sg~2.1 minutesIsotopes of seaborgium 107Bohrium270Bh61 secondsIsotopes of bohrium 108Hassium277mHs~12 minutes[12]Isotopes of hassium 109Meitnerium278Mt7.6 secondsIsotopes of meitnerium 110Darmstadtium281mDs~3.7 minutesIsotopes of darmstadtium 111Roentgenium281Rg26 secondsIsotopes of roentgenium 112Copernicium285mCn~8.9 minutesIsotopes of copernicium 113Ununtrium286Uut19.6 secondsIsotopes of ununtrium 114Flerovium289mFl~1.1 minutesIsotopes of flerovium 115Ununpentium289Uup220 millisecondsIsotopes of ununpentium 116Livermorium293Lv61 millisecondsIsotopes of livermorium 117Ununseptium294Uus78 millisecondsIsotopes of ununseptium 118Ununoctium294Uuo890 microsecondsIsotopes of ununoctium http://en.wikipedia.org/wiki/Island_of_stability They should keep Ununoctium. Livermorium is in the same group as Oxygen.
I think the names Ununtrium, Ununpentium, Ununseptium and Ununoctium are place holders, because they just mean things like "the hundred-and-thirteenth element". I'm not sure whether the other names are internationally agreed yet, either.
yeah, but 'just been detected' is misleading. this happened several years ago, over the space of several years' observation. 1/3rd at 7 TeV, 2/3rd at 8 TeV; two completely separate runs. years ago. just now being released. oddly, the report gives no dates as to the runs themselves, only their energies. also, observations are by people; detections are by machines. so the LHC made no observations.
Some may know I have measured the length of some photons, and in discussion given in those posts, I noted that the longer ones (many more EM cycles) have their energy more precisely defined so the line widths are very narrow (after any Doppler is removed in the analysis). I. e. if the energy is precise, then then when they were emitted is vague. (QM's uncertainity principle, which often speaks of "delta t" instead of the more correct "when" as "t" is never an observable.) I. e. Long photons come from states that have low transition rate probabilities (when emitted is very uncertain) (Also they must come from a very low density gas, as the approach of another atom (or even just an electron) can perturb the energy levels of the emitter - this is called "collisional broadening") Only nature, not man, can produce photons more than a meter long - such as the green line* of the Northern Lights. Man can, with effort make vacuum's residual gas pressure low enough, but not in the huge volumes needed to get detectable (above noise) long wave length radiation. The photons I measured were ~30cm long. This general "when x energy" uncertainity principle is also related to the transition probabilities (rate of decay) of these new baryons, which can be considered to be "exited states" too. This is why in post 2 you can read and focus on part now bold: "In addition to the masses of the new particles, the team also studied their relative production rates, their widths (a measurement of how unstable they are), and a few other details of their decays." I.e. a rapid decay means that when it happened is well defined, and that means the energy (or width) or observed spread of the observed masses is less certain. * For a long time, no one knew what the green line's source was. It is oxygen exceited state that "can not" decay to the lower state it does - I. e. it is a transitions that violates the QM selection rules. I think it "needs" a weak (long range) collision to even exist - yet it is one of the strongest / dominate lines in the Northern Lights. As it has zero transition probability (without that "helping" collision) the concentration of O* can build up.
only was pointing out that they probably did not measure the energy of the new particles, but inferred it from observed life time (which in turn were probably inferred from intensity fall off as range from target to detectors increased.) I don't know - perhaps the inverse is what is done - my point is that energy measurements and life-times are related as I described.
Correct. There was a naming controversy induced by controversy between the Americans, Germans, and Russians (the so called Transfermium wars) over which teams discovered which elements for the elements between 104 and 108, because traditionally the team that discovers an element gets to name it. Eventually the following names were decided upon: 104: rutherforium 105: dubnium 106: seaborgium 107: bohrium 108: hassium 109: meitnerium The dispute was originally between the Americans and Russians over elements 104 and 105, but the Germans (undisputed discoverers of 107-109) were dragged into it by IUPAC suggesting that they could change the name of one of their elements to satisfy the Americans.
With regards to: Ununtrium has not been confirmed yet, and so IUPAC has yet to accept an official name for it. The same is true for Ununseptium and Ununoctium. Livermorium and Flerovium were accepted as the occifial names in 2011/2012.
Georgy Flyorov, worked on the russian atomic bomb project, discovered spontaneous fission with Konstantin Petrzhak, founded the Joint Institute for Nuclear Research in Dubna, of which he was the director until 1989 (now the Flyorov Laboratory of Nuclear Reactions), largely responsible for getting the soviet atomic bomb project underway - he wrote to Stalin pointing out the silence about nuclear fission in the US, and Europe (both allied and axis) and suggested that this meant it had become classified research and pushed for Russia to begin its own project.
Thanks, Trippy. It's interesting that even today Soviet scientists are so little known in the west. (Or is it just me?)
Naa, I don't think it's just you - I had to look up who Flyorov was when I first came across flerovium, although I did remember his story regarding the russian atomic bomb project. I'm fairly sure most people know the names like Pavlov, Sakharov, Euler, Fedorov, Gamow, Gusev, Markov, Landau, Mendeleyev, and Lenin had the equivalent of a first class degree. There are other names that people might recognize, or have heard but may not have realized: Tsiolkovsky and Korolev, for example. Or Oleg Antonov, Sergey Ilyushin, Mikhail Mil, Artem Mikoyan, Igor Sikorsky, Pavel Sukhoi, Alexi and Andrey Tupolev. I mean, do you even know the last name of the person who deigned the B52 or the B17? Or the Stratofortress for that matter?
