higgs
catdynamics | August 9, 2013Lawrence Krauss just wrote an interesting letter: "Higgs Seesaw Mechanism as a Source for Dark Energy" - Krauss & Dent, PRL 2013
in it he argues for a see-saw mechanism in the Higgs sector which gives a natural scale for dark energy which is small, as observed.
The key point is that the energy scale is suppressed by
λ ~ (mH/mX)2)
where mH is the Higgs scale and X is some unification scale with mX >> mH
as a bonus you may expect a new long range weak force to go with the new physics.
Potentially interesting speculation.
Many moons ago, I wrote almost massless world on this here very…
esiegel | March 15, 2013"If you're a reporter, the easiest thing in the world is to get a story. The hardest thing is to verify. The old sins were about getting something wrong, that was a cardinal sin. The new sin is to be boring." -David Halberstam
It was only a few months ago that both collaborations at the Large Hadron Collider in CERN -- CMS and ATLAS -- announced the discovery of a new particle at about 125-126 GeV of energy: something that looked an awful lot like what the Standard Model predicted the Higgs Boson should be.
Image credit: the CMS detector at CERN, 2009.
This was the result of decades of…
catdynamics | December 19, 2012More Phenomenal random links to random stuff: life, the Universe and Everything
Phenomena - new blog group under National Geographic, including some long time scibloggers: The Loom, Not Exactly Rocket Science, Laelaps and Only Human, to begin with.
On the Usefulness of Useless Knowledge - Bee explains.
Substantive Advice to Admissions Committees - Or, why, all things being equal, we should prefer candidates from less prestigious institutions.
This is actually sensible - it is a "what have you done with what you were given" argument.
But, all things are very rarely equal... and no one ever…
esiegel | October 17, 2012"The particle and the planet are subject to the same laws and what is learned of one will be known of the other." -James Smithson
The entirety of the known Universe -- from the smallest constituents of the atoms to the largest superclusters of galaxies -- have more in common than you might think.
Image credit: Rogelio Bernal Andreo of http://blog.deepskycolors.com/about.html.
Although the scales differ by some 50 orders of magnitude, the laws that govern the grandest scales of the cosmos are the very same laws that govern the tiniest particles and their interactions with one another on the…
catdynamics | August 16, 2012Continuing slow live blog of the “New Particle Physics at the LHC and Its Connection to Dark Matter” workshop at the Aspen Center for Physics.
Series of short talks this morning:
"A WIMPy Baryogenesis Miracle" by
Yanou Cui, Lisa Randall, Brian Shuve (arXiv:1112.2704) interesting and possibly useful speculation on how electroweak scale WIMPs could couple to normal matter in early universe and actually generate some or all of the normal matter, in particular in such a way as to generate the observed matter/anti-matter asymmetry.
Aside: Quantum Diaries has the down and dirty details of the Higgs…
catdynamics | August 14, 2012"New Particle Physics at the LHC and Its Connection to Dark Matter" is the name of the current workshop at the Aspen Center for Physics running through Sep 9th.
I'm hanging out for the first few days and the first presentation is on "what has the LHC Higgs done to supersymmetry"?
So, basic point is that supersymmetry sort of predicts that the Higgs mass (125 GeV) should be close to the Z mass (91 GeV), up to some corrections. So the mass corrections can be parametrised in perturbative theory, and how do you nail a ~ 30% correction and keep everything natural?
We talk about our feelings.
We…
catdynamics | August 9, 2012Last talk of the LHC Shows the Way workshop, with the most provocative title.
Entries in this post may or may not be mangled misrepresentations of stuff the speaker made up just to be provocative...
Starting point: there is something at ~ 125 GeV and it is consistent with a boson, possibly a scalar, and quite likely a standard model Higgs boson.
Agreed.
Preliminary results for CMS experiments show branching ratio to ττ decay mode a little bit lower than normal.
ATLAS initially did simple crude analysis of this channel.
Now redone with more data and better technique.
ATLAS expect to make…
catdynamics | August 9, 2012The LHC Shows the Way workshop is about to end, and the slow live blog limps along with a presentation on the composite Higgs.
A model for having a light (~ 100 GeV ) scalar, is to have a composite Higgs instead of the alternative of either a true supersymmetric model or a light dilaton scalar.
As with such models in general, they violate unitarity if extrapolated to higher energies, so force a new energy scale, at, say, few TeV - like another particle there (cf old effective weak interaction theory).
Yes, if you work it out in detail, the effective coupling runsaway and you need to truncate…
catdynamics | August 7, 2012Back at the LHC Shows the Way workshop at the Aspen Center for Physics - more discussion of Higgs alternatives and peculiar branching ratios.
No, the branching ratios for the different decay modes of the 125 GeV boson that is putatively the Higgs are not anomalous at a statistically significant level, but, they are off a bit.
So, theorists go wild with ecstatic speculation - it is fun and not yet ruled out by data, what else can we do!
This morning Fan on 2:1 for Naturalness at the LHC? by Nima Arkani-Hamed, Kfir Blum, Raffaele Tito D'Agnolo, JiJi Fan
Later there will be discussion on jet…
catdynamics | August 2, 2012Back at the LHC Shows the Way workshop and slow live blogging of the discussion, with random asides for other stuff...
Astronomy Magazine has a contest - win Brian May's PhD thesis! - now separate post with added bonus question
Today:
fake Higgs - are there some new bosons which are not Higgs, but which look like Higgs. Specifically looking at other scalar or pseudoscalars, or the possibility of spin-2 tensor particles.
Aside: cool 2D fluid flow web site - GPU powered 512k sim run live through WebGL - hypnotic turbulence to crash your browser
Look for general models where some particle…
catdynamics | July 31, 2012Continuing lazy live blog of the LHC Shows the Way workshop, with random interludes of alternative considerations, including the more esoteric aspects of German finance...
Patio session (informal presentation of in-progress results on blackboard, outside) - didn't catch speaker's name, got here a couple of minutes late.
Being reminded that Higgs is not the only scalar that may exist out there - could the LHC 125 GeV bump be a dilaton?
Paper by Csaki and collaborators coming out in August on arXiv.
Aside: the proliferation of chargeless scalars in quantum field theories has always bothered me…
catdynamics | July 26, 2012LHC Shows the Way workshop: general colloquium reviewing the LHC and the Higgs discovery.
Kyle Cramner from NYU: "We discovered the goddamned particle"
More slow live blog.
Cute opening video of LHC construction.
Factoid: kinetic energy of LHC beam is about that of a jumbo jet at cruise speed
Starting point: Standard Model is ridiculously successful, at the part per million quantitative level.
In the regime in which it is valid.
Add Higgs and you don't just get mass, you get coupling to fermion decay is proportional to the Higgs induced mass of the fermion.
Can calculate Higgs boson…
catdynamics | July 26, 2012The LHC Shows the Way workshop rolls on, looking at the implications of the Higgs at 125-126 GeV for supersymmetry.
I live blog, slowly.
Where are the sparticles.
Coloured supersymmetric partners, the quark and gluon supersymmetric partners, must be massive - greater than ~ 1,000 GeV
in some natural implementation of supersymmetry, natch, clever theorists can of course think of increasingly contrived ways to get around most any limit, at the expense of fewer and fewer people believing them.
Minimal supersymmetric extensions to the standard model, with the Higgs mass assumed to be 126 GeV and…
catdynamics | July 9, 2012time for all new linkedy links here at the new digs
Quantum Frontiers - a new blog from the Institute for Quantum Information and Matter, with kickoff by John Preskill hisself.
Question of the day: explain quantum mechanics in five words
My attempt: Probability Amplitudes, Observables don't Commute
Good to know John still does khakis and chalk, but we gots to know: does he still have the diet pepsi?
Took me years to break the habit... not that I was overly impressionable as a tender young grad turkey taking QFT or anything.
Subtleties of the Crappy Job Market - for Scientists, that is.…
sciencepunk | July 9, 2012
This three-story-tall mural was painted by international artist Josef Kristofoletti on the side of the ATLAS control room directly above the detector:
This project was inspired by the same questions that physicists are trying to answer; where did we come from, what does it mean to be human, and what is our place in the universe? The artist worked closely with physicists at CERN over the course of a year to create the mural. It depicts the artist's interpretation of what the Higgs boson might look like.
This short, time-lapse video was finished June 2012, using photos that were taken during…
catdynamics | July 7, 2012In which we remind people of the Ten Commandments of the God Particle.
Now with added footnotes.
I I am the Higgs. Thou shalt have no other Higgs before me.1
II Thou shalt not make unto thee any graven image, or any likeness of any thing that is in heaven above, or that is in the earth beneath, or that is in the water under the earth:Thou shalt not bow down thyself to them, nor serve them: for I the HIGGS thy God Particle am a jealous God Particle, visiting the iniquity of the fathers upon the children unto the third and fourth generation of them that hate me. 2
III Thou shalt not take the…
esiegel | July 6, 2012"Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe?" -Stephen Hawking
After a long search spanning more than my entire lifetime (so far), the Higgs boson has finally been discovered at both detectors -- CMS and ATLAS -- at the Large Hadron Collider at CERN.
Image credit: CERN / Particle Physics for Scottish Schools.
For a little more on this, check out the earlier posts here celebrating Higgs week:
The Biggest Firework of them all: The Higgs
How the Higgs…
esiegel | July 5, 2012"We knew that we had indeed done something that was very different and very exciting, but we still didn't expect it to have something to do with physical reality." -Gerald Guralnik, co-developer of the Higgs mechanism
Might as well make this entire week "Higgs week" here on Starts With A Bang, given how important yesterday's discovery/announcement was! It isn't every day, after all, that you see a theoretical physicist on the 7PM news. (Video here.)
Image credit: KGW.com.
(So proud of Portland, OR's local TV station, KGW NewsChannel 8, for being willing to promote science to the whole city…
catdynamics | July 4, 2012In the beginning there was light.
Sort of.
When energies were high enough, particles were effectively massless and the universe was a nice seething mess of particle/anti-particle creation and annihilation.
As the universe cools, a symmtery, the Electroweak symmetry breaks, a field condenses out, and interesting stuff starts happening.
Hence we get chemistry, and the autocatalytic evolving goo that reaches out and ties to puzzle out where it all came from.
In the Standard Model of Particle Physics, the rest mass of the spectrum of normal matter particles is dynamically generated. The mass we…
esiegel | July 4, 2012"This is evidently a discovery of a new particle. If anybody claims otherwise you can tell them they have lost connection with reality." -Tommaso Dorigo
You've probably heard the news by now: the Higgs boson -- the last undiscovered fundamental particle of nature -- has been found.
The fundamental types of particles in the Universe, now complete.
Indeed the news reports just keep rolling in; this is easily the discovery of the century for physics, so far. I'm not here to recap the scientific discovery itself; I wrote what to expect yesterday, and that prediction was pretty much exactly what…