An extra dimension for LHCb

The Standard Model of particle physics is like a jigsaw into which physicists are gradually fitting pieces. Though most results fit well and are compatible with Standard Model predictions, there are physicists hoping for results that don’t fit the jigsaw and so could point to new physics.

Jonas Rademacker of the University of Bristol and the Large Hadron Collider beauty (LHCb) collaboration is one of those physicists. “We’re hoping to find the jigsaw piece that looks like it should fit, but when you look very closely, the pattern isn’t quite right,” he says.

Rademacker has developed a new way of analysing data from LHCb that offers an unprecedented level of detail and precision. His technique requires analyzing special scatter plots called Dalitz plots in five dimensions rather than two. These plots represent the strange quantum-mechanical interference effects that happen in particle decays, and Rademacker and his colleagues use them at LHCb as a precision tool to measure CP violation.

Though five-dimensional analysis is a complicated feat, it is worth the effort because it significantly increases the precision of LHCb measurements.

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By: Stephanie Hills

thenewenlightenmentage:

Beyond Higgs: 5 Elusive Particles That May Lurk in the Universe

With the recent confirmation of a Higgs Boson discovery, many physicists were at least a little disappointed. That’s because all signs point to it confirming the Standard Model, the nearly 100-year-old theory that explains the tiny bits of matter that make up the universe.

But some physicists still hold out hope for results that could provide a bigger shake-up, looking for the Large Hadron Collider (LHC) and physics experiments at other facilities to reveal other hidden particles lurking in the universe. From gravitons to winos, here are five bizarre things that may exist beyond the Higgs:

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Prediction: Physics Enters A New Era

On July 4, 2012, a panel of scientists at the Large Hadron Collider in Geneva announced the discovery of a new particle, the long-anticipated Higgs boson (or something very much like it). The Higgs is the final piece of the Standard Model of particle physics, a theory that accounts for everything we experience in our lives, from rocks to puppies to stars and planets. After decades of searching and billions of dollars, the Higgs discovery marked the end of one era and the beginning of another, which scientists will embark upon in 2013.

If the previous era was about understanding the physics of everyday stuff, the next will be dominated by the attempt to grasp more elusive realms, including one of the most mysterious of all: dark matter. Astronomers have verified that the universe has about five times more matter than we can account for with the “ordinary” particles we’ve discovered here on Earth. The rest is dark matter. Physicists haven’t observed it directly yet, but they’re getting much closer.

Several different detectors are currently searching for dark matter underground, conducting experiments designed to sense a dark matter particle scattering off the nucleus of an ordinary atom. A couple of them have already yielded tantalizing evidence—not enough to convince most physicists, but enough to get people excited. The LUX detector, recently installed in a South Dakota mine, should prove the most sensitive one yet when it begins collecting data in 2013.

Alternatively, dark matter could be found by looking up into space. Scientists analyzing observations of cosmic gamma rays in 2012 discovered an unusual excess at a particular energy emanating from the center of our galaxy. One explanation for the signal is that dark matter particles are colliding and converting into high-energy radiation. This coming year will no doubt bring new data, better analysis, and maybe, just maybe, evidence that pins down dark matter once and for all.

By Sean Caroll

particularphysics:

CERN Seminar - 4th July - 9am CET - LHC Higgs ICHEP Results

In the particle physics world, one of the big conferences of the year is ICHEP (International Conference of High Energy Physics). Inevitably, this conference is going to be dominated somewhat by the ATLAS and CMS presentations of the results of their Higgs searches using proton-proton collision from the LHC at 8 TeV. What is also of interest is if these results have been combined with the results from 2011.

This is not a completely trivial task as the systematic uncertainties between channels in a the same data taking configuration can be split into ones which are fully correlated or completely uncorrelated. However when you have different environmental settings between the datasets this is a bit more involved (and that isn’t to say that the combination is not complicated in itself!) but hopefully both experiments will present such results. 

I know somewhat how the ATLAS results will look, so for me it is the CMS results which will be interesting. However, something that came out recently is that the CERN Council is clearly not keen on the people at ICHEP getting the first look at both sets of results.

Therefore there is going to be a public seminar at CERN on the 4th July at 9am CET (which is at 8am for those in the UK…and other times elsewhere ;-) ), so I will be planning to get up early for once and try and get a seat. As far as I am aware, the seminar will be broadcast online at webcast.cern.ch. If a permalink becomes available I will post that too.

I guess I’ll try to cover the seminar as a blog post, but I know there are many other CERN bloggers out there who do a better job than I.

So a short post to say keep your eyes peeled around the 4th July if you have an interest in the hunt for the Higgs!

nationalpost:

Higgs boson-hunting CERN scientists closing in on Big Bang particle

Physicists investigating the make-up of the universe are closing in on the elusive particle thought to have been key to turning debris from the Big Bang into stars, planets and finally life

“Beautiful” New Particle Found at LHC — Xi(b)* a “brick in the wall” for solving how matter’s made, expert says.

An atom-smashing experiment at the Large Hadron Collider (LHC) has detected a new subatomic particle—and it’s a beauty.

Known as Xi(b)* (pronounced “csai bee-star”), the new particle is a baryon, a type of matter made up of three even smaller pieces called quarks. Protons and neutrons, which make up the nuclei of atoms, are also baryons.

The Xi(b)* particle belongs to the so-called beauty baryons, particles that all contain a bottom quark, also known as a beauty quark.

The newfound particle had long been predicted by theory but had never been observed. Although finding Xi(b)* wasn’t exactly a surprise, the discovery should help scientists solve the larger puzzle of how matter is formed.

“It’s another brick in the wall,” said James Alexander, a physicist at Cornell University who conducts experiments with the LHC. 

Sorting Through the Mess

Unlike protons and neutrons, beauty baryons are extremely short-lived—Xi(b)* lasted mere fractions of a second before it decayed into 21 other ephemeral particles.

The particle also requires extremely high energies to create, so it’s found nowhere on Earth except in the hearts of atom-smashers such as the LHC, operated by the European Center for Nuclear Research (CERN) in Geneva.

The new beauty baryon is a higher energy version of one that was detected last summer by scientists using the Tevatron particle accelerator at Fermilab in Illinois.

LHC scientists didn’t detect the new particle directly. Instead they saw evidence of its decay in the messy aftermath of a proton-proton collision captured by the facility’s Compact Muon Solenoid (CMS) detector.

“Finding this particle is really very hard,” CMS physicist Vincenzo Chiochia, a co-discoverer of the new particle, told Symmetry Breaking magazine.

“Finding this complicated decay in such a messy event makes us confident in our abilities to find other new particles in the future.”

The CMS scientists say the new particle’s existence has been confirmed to a sigma level of five, which means the researchers are 99.99-percent confident that the result isn’t due to chance.

Hunt Still on for Higgs

The discovery is further confirmation that physicists are essentially correct in their understanding of how quarks are bound together, said Fermilab scientist Patrick Lukens, who was not involved in the study.

The particle was predicted by a wildly successful theory in physics known as quantum chromodynamics, which models how quarks combine and are held together to create heavier particles.

However, Lukens said, finding Xi(b)* has no bearing on the hunt for the Higgs boson, a particle that would explain why mass exists in the universe and that’s also predicted by quantum chromodynamics.

Cornell’s Alexander added that the Higgs “is a huge pivot point for the entire theory” of quantum chromodynamics. “Whether the Higgs is or is not there—everything rests on that.”

Ker Than, National Geographic News

thenewenlightenmentage:

New Particle Discovered at CERN

ScienceDaily (Apr. 27, 2012) — Physicists from the University of Zurich have discovered a previously unknown particle composed of three quarks in the Large Hadron Collider (LHC) particle accelerator. A new baryon could thus be detected for the first time at the LHC. The baryon known as Xi_b^* confirms fundamental assumptions of physics regarding the binding of quarks.

In particle physics, the baryon family refers to particles that are made up of three quarks. Quarks form a group of six particles that differ in their masses and charges. The two lightest quarks, the so-called “up” and “down” quarks, form the two atomic components, protons and neutrons. All baryons that are composed of the three lightest quarks (“up,” “down” and “strange” quarks) are known. Only very few baryons with heavy quarks have been observed to date. They can only be generated artificially in particle accelerators as they are heavy and very unstable.

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