Because detectable mass only makes up about 5 percent of the universe - and the universe is expanding faster now than in the past - a rethink of mass and gravity has been required. The umbrella term for this mass that must exist, but can't be detected, is "dark matter." Don't worry if that definition is vague, no one knows any more than that.
Dark matter can be inferred by gravitational effects - and things like antimatter and baryonic clouds can be excluded - and so hundreds of explanations have been created for it. A new one by Mikhail Medvedev, professor of physics and astronomy at the University of Kansas is called "flavor-mixed multicomponent dark matter."
Among the viable extensions of the standard model, an intriguing class of models involve the concept of a "hidden sector" of new particles only weakly coupled to the standard model one. These particles could be produced in the decay of heavy standard model particles, be invisible, but unstable, and thus soon decay back into standard model bodies, giving funny experimental signatures that our detectors could spot -if we looked for them carefully enough.
Until the second half of the nineties, when the LEP collider started to be upgraded to investigate higher centre-of-mass energies of electron-positron collisions than those until then produced at the Z mass, the Higgs boson was not the main focus of experiments exploring the high-energy frontier. The reason is that the expected cross section of that particle was prohibitively small for the comparatively low luminosities provided by the facilities available at the time. Of course, one could still look for anomalously high-rate production of final states possessing the characteristics of a Higgs boson decay; but those searches had a limited appeal.
Using the Borexino instrument, located deep beneath Italy's Apennine Mountains and one of the most sensitive neutrino detectors on the planet, an international team of physicists has directly detected neutrinos created by the "keystone" proton-proton (pp) fusion process going on at the sun's core.
The pp reaction is the first step of a reaction sequence responsible for about 99 percent of the Sun's power. Solar neutrinos are produced in nuclear processes and radioactive decays of different elements during fusion reactions at the Sun's core. These particles stream out of the star at nearly the speed of light, as many as 420 billion hitting every square inch of the Earth's surface per second.
Here is something counter-intuitive: researchers have developed a new quantum imaging technique in which the image has been obtained without ever detecting the light that was used to illuminate the imaged object, while the light revealing the image never touches the imaged object.
As everyone knows, outside the world of quantum mechanics, to obtain an image of an object one has to illuminate it with a light beam and use a camera to sense the light that is either scattered or transmitted through that object. The type of light used to shine onto the object depends on the properties that one would like to image. Unfortunately, in many practical situations the ideal type of light for the illumination of the object is one for which cameras do not exist.
The Holometer, an experiment at Fermi National Accelerator Laboratory, has started collecting data but researchers are not going to wait to start their media blitz; they are throwing out mind-bending speculation, like that perhaps we live in a hologram.
Much like characters on a television show would not know that their seemingly 3-D world exists only on a 2-D screen, we could be clueless that our 3-D space is just an illusion. The information about everything in our universe could actually be encoded in tiny packets in two dimensions.
Wave-particle duality suggests that elementary particles, like electrons and photons, cannot be completely described as either waves or particles, because they exhibit both types of properties. In the double-slit experiment, observing a photon pass through one of the two slits is an example of a particle-like property; a particle can only pass through one or the other. When two waves converge to form an interference pattern, the photon must have passed through both slits simultaneously—a wave-like property.
Trying to measure both types of properties simultaneously is problematic because the interference pattern disappears as soon as it is known through which slit the photon has passed.
Interaction with matter changes the neutrino mixing and effective mass splitting in a way that depends on the mass hierarchy. Consequently, results of oscillations and flavor conversion are different for the two hierarchies.
Sensitivity to the mass hierarchy appears whenever the matter effect on the 1-3 mixing and mass splitting becomes substantial. This happens in supernovae in large energy range, and in the matter of the Earth.
The Earth density profile is a multi-layer medium where the resonance enhancement of oscillations as well as the parametric enhancement of oscillations occur. The enhancement is realized in neutrino (antineutrino) channels for normal (inverted) mass hierarchy.
Preparing the documents needed for an exam for a career advancement, to a scientist like me, is something like putting order in a messy garage. Leave alone my desk, which is indeed in a horrific messy state - papers stratified and thrown around with absolutely no ordering criterion, mixed with books I forgot I own and important documents I'd rather have reissued rather than searching for them myself. No, I am rather talking about my own scientific production - pubished articles that need to be put in ordered lists, conference talks that I forgot I have given and need to be cited in the curriculum vitae, refereeing work I also long forgot I'd done, internal documents of the collaborations I worked in, students I tutored, courses I gave.
Earth's magnetic field, a familiar directional indicator over long distances, is routinely probed in applications ranging from geology to archeology, and now it has provided the basis for a technique which could characterize the chemical composition of fluid mixtures in their native environments.
Researchers from the Lawrence Berkeley National Laboratory conducted a proof-of-concept nuclear magnetic resonance experiment in which a mixture of hydrocarbons and water was analyzed using a high-sensitivity magnetometer and a magnetic field comparable to that of the Earth.