Skip to main content

LHC signal hints at cracks in physics' standard model

LHC signal hints at cracks in physics' standard model

Collider spots same anomaly seen by two other experiments, but more data are needed to claim a discovery.

Article tools

Rights & Permissions
CERN
A view inside the LHCb experiment's muon detector at the Large Hadron Collider.
An intriguing signal from the Large Hadron Collider (LHC) might prove to be the crack that prises apart the standard model — physicists’ current best description of how matter and forces interact.
Analysis of data gathered during 2011–12 at the collider at CERN, Europe’s particle-physics laboratory near Geneva, Switzerland, suggests that in particular decays, short-lived particles called B-mesons create taus more frequently than they create muons. (Taus and muons are heavier cousins of electrons.) But the standard model says that once the particles’ mass differences are taken into account, the decays should occur at exactly the same rate. The finding will be published in Physical Review Letters this month (and has been on the arXiv1 pre-print server since June).
The discrepancy in decay rates, spotted at the collider’s LHCb experiment, is small and cannot be claimed as a discovery, because the anomaly may be merely a statistical fluctuation that could fade as more data are collected on B-meson decays. Particle physicists’ usual threshold for announcing a discovery is, in statistical parlance, 5 sigma; the LHCb signal has reached only 2.1 sigma.
But physicists are excited because the same anomaly has also been seen in results from two previous experiments: the ‘BaBar’ experiment at the SLAC National Accelerator Laboratory in Menlo Park, California, which reported it in 20122, and the ‘Belle’ experiment at Japan’s High Energy Accelerator Research Organization (KEK) in Tsukuba, which reported its latest results at a conference in May. LHCb's result is “bang on" the previous two, says Mitesh Patel, a physicist at Imperial College London who works on the experiment.
“A 2-sigma difference in a single measurement isn’t interesting by itself,” says Tara Shears, a particle physicist at the University of Liverpool, UK, and a member of the LHCb collaboration. “But a series of 2-sigma differences, found in different types of decay and independently by different people in a different experiment, become very intriguing indeed.”

New physics?

Last year, LHCb found a similar bias, with a significance of 2.6 sigma, in decays of another type of B meson, this time a preference to decay into electrons rather than muons. What makes both measurements so exciting is that if the results prove real, they could point to the same underlying new physics, says Shears.
Both biases could potentially be explained, for example, by positing another kind of Higgs boson, which possesses charge and interacts differently with the various particles involved in the decays. Supersymmetry, a popular theory that seeks to extend the standard model, predicts such multiple Higgs bosons, although Patel says that, should the signal prove real, this is just one of many potential explanations.
Don Lincoln, a physicist at another LHC experiment called CMS, cautions that the findings are still most probably a statistical fluctuation or an improperly estimated uncertainty in the experiment. But seeing the discrepancy in multiple places should make people pay attention. “This is clearly something that must be studied in more detail,” he says.
The finding is based on data from the LHC’s first run, and physicists will have to wait for as long as a year to gather a similar amount of data from the collider’s second run, which began on 3 June. In the meantime, the LHCb team will examine other similar decays in existing data to see if further biases emerge, says Patel.
Physicists at CMS and the LHC experiment ATLAS are chasing their own intriguing results. They search for new particles directly (unlike LHCb, which tries to spot such particles by their indirect influence on known decays). Both CMS and ATLAS have seen low-significance ‘bumps’ within roughly the same mass region of their data — around 2 teraelectronvolts (TeV) — which could be caused by decays of a new particle, although it is not clear whether the findings are entirely compatible. The latest ATLAS paper, available on the arXiv, puts the signal’s statistical significance at 3.4 sigma.
Since the 1970s, experiments have time and again proved the accuracy of the standard model. Yet its failure to account for phenomena such as gravity and dark matter leads many physicists to think that it is merely an approximation of another description beneath. Patel says that he finds LHCb’s tantalizing results more convincing than those seen by its rival experiments, but would be happy to see either emerge as real as more data and analysis come in. “The standard model has stood for too long, and we’ll take its fall in any way it comes.”
Nature
 
doi:10.1038/nature.2015.18307

Popular posts from this blog

Hidden Wiki

Welcome to The Hidden WikiNew hidden wiki url 2015 http://zqktlwi4fecvo6ri.onion Add it to bookmarks and spread it!!!
Editor's picks Bored? Pick a random page from the article index and replace one of these slots with it.
The Matrix - Very nice to read. How to Exit the Matrix - Learn how to Protect yourself and your rights, online and off. Verifying PGP signatures - A short and simple how-to guide. In Praise Of Hawala - Anonymous informal value transfer system. Volunteer Here are five different things that you can help us out with.
Plunder other hidden service lists for links and place them here! File the SnapBBSIndex links wherever they go. Set external links to HTTPS where available, good certificate, and same content. Care to start recording onionland's history? Check out Onionland's Museum Perform Dead Services Duties. Introduction PointsAhmia.fi - Clearnet search engine for Tor Hidden Services (allows you to add new sites to its database). DuckDuckGo - A Hidden S…

[SOLVED] IDM WAS REGISTERED WITH A FAKE SERIAL NUMBER

[SOLVED] IDM WAS REGISTERED WITH A FAKE SERIAL NUMBER
Good News [May 08, 2015]: IDM developers got smarter, but the crackers are always a step ahead. Follow this article and send an email to uglyduckblog@gmail.com if you are desperate. I can NOT post any crack here for legal reasons. Happy Downloading with IDM. ;) *********** first tip is to use latest crack for idm from  onhax.net idm universal web crack and make sure u are using all latest vers I am sure many of us are too much dependent on Internet Download Manager a.k.a. IDM. The main reason didn’t permanently switch to linux was IDM. I mainly use it for batch downloading and download streaming videos. Till yesterday, IDM was working fine with me (of course with fake serial numbers, keygen, crack, patch etc. which could be found with little effort). But few days ago, with the latest update version 6.18 build 7 (released on Nov 09, 2013) Internet Download Manager was literally had a breakthrough and crushed all the serial numbers, …

Mouse, touchpad, and keyboard problems in Windows

Mouse, touchpad, and keyboard problems in Windows Introduction This tutorial is designed to help you identify and fix common mouse, touchpad, and keyboard problems in Windows. It doesn't cover device problems related to specific programs. Mouse, touchpad, and keyboard problems can have a number of causes: Cables that aren't connected properly Incorrect device settings Missing updates Corrupted or incompatible drivers Hardware problems Check hardware Many mouse, touchpad, and keyboard problems are caused by hardware that isn't set up properly. Here's some information about how to check your device, make sure cables are connected properly, make sure the hardware has power, and check the settings. Make sure cables are connected properly Check that all cables are plugged in to the correct locations. This can include mouse and keyboard, PS2 and USB cables, and, in some cases, external USB touchpad cables. Disconnect USB cables and wait for a short time for the device drive…