Friday, Aug. 28, 2015
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Fermilab Board Game Guild

Call for proposals: URA Visiting Scholars Program - deadline is Aug. 31

Fermilab employee art show - submission deadline Sept. 1

Bible exploration group starting new study called "Live Justly" - Sept. 8

Fermilab golf outing - Sept. 11

September AEM meeting date change to Sept. 14

Fermilab Lecture Series: Visualizing the Future of Biomedicine - Sept. 18

Fermilab Arts Series: 10,000 Maniacs - Sept. 26

Python Programming Basics is scheduled for Oct. 14-16

Python Programming Advanced - Dec. 9-11

Fermilab Prairie Plant Survey

New line dancing class

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From symmetry

Looking for strings inside inflation

Theorists from the Institute for Advanced Study have proposed a way forward in the quest to test string theory. Image: Sandbox Studio

Two theorists recently proposed a way to find evidence for an idea famous for being untestable: string theory. It involves looking for particles that were around 14 billion years ago, when a very tiny universe hit a growth spurt that used 15 billion times more energy than a collision in the Large Hadron Collider.

Scientists can't crank the LHC up that high, not even close. But they could possibly observe evidence of these particles through cosmological studies, with the right technological advances.

Unknown particles
During inflation — the flash of hyperexpansion that happened 10-33 seconds after the big bang — particles were colliding with astronomical power. We see remnants of that time in tiny fluctuations in the haze of leftover energy called the cosmic microwave background.

Scientists might be able to find remnants of any prehistoric particles that were around during that time as well.

"If new particles existed during inflation, they can imprint a signature on the primordial fluctuations, which can be seen through specific patterns," says theorist Juan Maldacena of the Institute for Advanced Study at Princeton University.

Maldacena and his IAS collaborator, theorist Nima Arkani-Hamed, have used quantum field theory calculations to figure out what these patterns might look like. The pair presented their findings at an annual string theory conference held this year in Bengaluru, India, in June.

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Troy Rummler

In Brief

Neutrino Seminar Series starts up on Sept. 3

Learn all about neutrinos at this season's Neutrino Seminar Series.

A new season of the Neutrino Seminar Series begins on Sept. 3.

The series is intended to provide an opportunity to communicate ideas between Fermilab neutrino experiments, inject insight from relevant outside experts and present new results. Topics cover accelerator-based neutrino physics, low-energy neutrino experiments, new detection technologies, neutrinos in astrophysics and astroparticle physics, and neutrino theory.

This season's program will cover 24 orders of magnitude in neutrino energy, from the lowest-energy neutrino measurements at meV in neutrinoless double beta decay to searches for ultrahigh-energy neutrinos of astrophysical origin with ZeV energies.

There will also be results from experiments including NOvA, Daya Bay, ICARUS and MINERvA, as well as talks on neutrino flux understanding with the NA61/SHINE experiment and presentations on neutrino theory.

The seminar is usually held biweekly on Thursdays at 1:30 p.m. Announcements can be found in the Fermilab calendar.

In the News

President Obama nominates two science leaders

From Physics Today, Aug. 25, 2015

On 5 August, President Obama announced a slate of nominations for key science posts in his administration, including Cherry Murray to be director of the Department of Energy's Office of Science and Richard Buckius to be deputy director of NSF. Both nominees must be confirmed by the Senate before stepping into their respective positions.

Murray is a renowned American physicist who served as the dean of the Harvard School of Engineering and Applied Sciences from 2009 through 2014. She was the president of the American Physical Society, an AIP member society, in 2009, and chaired the division of engineering and physical sciences for the National Research Council from 2008 to 2013. Murray also previously served as principal associate director for science and technology at Lawrence Livermore National Laboratory and was senior vice president for physical sciences and wireless research at Bell Laboratories. President Obama awarded her the National Medal of Technology and Innovation in 2014, and Discover magazine named her one of the 50 most important women in science in 2002.

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Frontier Science Result: CMS

Looking in Schrödinger's box

This diagram shows two ways that a b quark can turn into an s quark and μ+μ. Everything inside the box is fundamentally unobservable, so both of these processes are happening at the same time, like the two states of Schrödinger's cat.

In a famous thought experiment, Erwin Schrödinger proposed putting a cat in a box with a quantum mechanical device that may or may not kill the cat. Until the box is opened, the cat is both alive and dead.

There are many reasons why this can't be done in practice, one of which is that you can't make the walls of the box opaque enough to truly hide all information. However, particle physicists regularly deal with an analogue of the cat-in-a-box: intermediate particles that are too short-lived to be observed. These particles disappear before they can interact even once with their environment, so they are completely hidden.

Take, for example, the subject of a recent study by CMS scientists, B0 → K∗0μ+μ. The B0 meson (which is a b quark bound to a lightweight quark) decays into three particles: K∗0 (which is an s quark bound to a lightweight quark), μ+ and μ. For this decay to be possible, nature must find a way to connect the one-particle initial state to the three-particle final state using fundamental interactions. In the Standard Model, negatively charged b quarks cannot transform directly into negatively charged s quarks, so you might think that this decay can never occur.

Two possible solutions are shown above, and both involve a pair of transformations: b quark to t quark and t quark to s quark. Either way, short-lived particles are needed to bridge the gap. Much like Schrödinger's unfortunate cat, the two intermediate processes are both happening at the same time: the t-W-Z loop lives and dies in the same place at the same time as the t-W-ν-W loop. All of the final particles can be fully reconstructed as tracks, so physicists can see evidence of the two realities mixing in their angular distributions.

Exciting as it sounds, that part is old news. This analysis was performed because the two overlapping Standard Model solutions might not be the only ones. If as-yet undiscovered particles interact with any of the above, there might be a third way to get from from a B0 meson to K∗0µ+µ, further distorting the angular distributions.

This could even happen if the new particle is too heavy to create directly. Short-lived intermediaries can exist with different masses than their real counterparts, so they can be observed this way even if they are beyond the reach of the LHC. Nothing unusual was seen this time, further tightening constraints on new physics.

Jim Pivarski

These U.S. CMS scientists made important contributions to this analysis.
Photo of the Day

Wind in the weeds

Queen Anne's lace is buffeted wildly by the wind. The flower is ubiquitous throughout North America, but it is not native to the area. Although it is considered invasive in some prairies, such as those with gravel or sandy soils, it is not considered invasive on the Fermilab grounds. Photo: Elliott McCrory, AD
In the News

Particle physics: Positrons ride the wave

From Nature, Aug. 27, 2015

Particle accelerators and colliders have been the backbone of research into elementary particle physics for almost a century. The next generation of colliders must be able to generate collision energies for lepton particles, such as electrons and positrons, in the teraelectronvolt range (1 TeV is 1012 electronvolts). This will complement discoveries being made by the Large Hadron Collider at CERN, Europe's particle-physics laboratory near Geneva, Switzerland. On page 442 of this issue, Corde et al. report a system for accelerating positrons — the antimatter counterparts of electrons — that might enable such instruments to be realized.

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