Of Particular Significance

Category: LHC Background Info

To tell you what you need to know for the presentations on the Higgs particle search coming up on December 13th, I’m writing a sequence of three articles about the Standard Model Higgs particle, the simplest form of Higgs particle that might be present in nature, and the one that is the main target, during Phase 1 of the search for the Higgs particle, that the Large Hadron Collider (LHC) experiments are aiming to discover or rule out.

Click here for Article # 1, which is about how these particles are made. There are five major processes by which the Standard Model Higgs particle may be produced at the LHC.  In this article I’ll tell you what they are, and what we’d learn if we measured each of them precisely.

Click here for Article #2: how the Standard Model Higgs particle decays, and what we can learn by measuring those decays precisely.

Sunday or Monday, Article #3: how we search for the Standard Model Higgs particle, combining what we know about its production and decay with what we know about other processes that will mimic its presence in an LHC detector.  And also [probably to be extended later in the week] how we will go about making precise measurements of the properties of any candidate Higgs particle that we observe, to confirm that it really is a Standard Model Higgs particle, and not something more complicated.

Enjoy!

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON December 10, 2011

To tell you what you need to know for the presentations on the Higgs particle search coming up on December 13th, I’m writing a sequence of three articles…

[OUT OF DATE: SEE THIS NEW POST]

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON December 9, 2011

While I was on my way to Johns Hopkins University Monday evening, I wrote the following post, for publication today (Wednesday). Tuesday morning, CERN stole some of my thunder by putting out a press release consistent with the conclusion I drew below.  Not that I mind.   A quote from the press release follows this post.

The rumor mills on various blogs have been going berserk, with claims that a Higgs particle of Standard Model type (the simplest possible version of the Higgs particle) has been found by ATLAS and CMS (the two large general purpose experiments at the Large Hadron Collider.)  The claims are that the Higgs signal is at a mass-energy [E=mc2] of 125 GeV;  that CMS, in its search for a Higgs particle decaying to two photons, sees a small excess (that’s two or so standard deviations, or 2 σ, away from zero signal); and that ATLAS sees a larger excess (perhaps 3 σ) in their similar analysis. (You may find it useful to read my recent article about a lightweight Standard Model Higgs particle, and why searching for it through its decays to two photons is the best way to find it but takes frustratingly long — or you might like my recent guest post on Cosmic Variance about the Higgs search.)

Well, rumors are sometimes true, and this one might be, more or less.

  • More precisely, it might be true that ATLAS and CMS see excesses of the claimed type and size. We’ll find out on December 13th.
  • And also, it might even be true that these excesses are signs of the Standard Model Higgs particle. We will not find that out on December 13th.

Why not? There’s just not enough data yet. (more…)

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON December 7, 2011

I’ve decided to write a new set of articles explaining why it takes time, potentially a long time, to discover the Higgs particle.  First article is done: why even to find a Standard Model Higgs particle (the simplest possible type of Higgs particle that might be present in nature) has taken quite a while, if the Higgs particle is relatively lightweight.  Coming soon: various exotic Higgs particles that would take several more years to discover.  

If you’ve missed my two posts from the weekend you may want to read them:

  1. Saturday: The media is providing misleading reports on the Higgs particle search, not always properly distinguishing between the Standard Model Higgs particle (the simplest type of Higgs particle that might be present in nature) and Higgs particles in general.  There’s a very big difference.
  2. Sunday: Although the search for the Standard Model Higgs particle is at least half over, it could take a very long time (as much as 10 years) to confirm that there are no Higgs particles of any type in nature.

I’m also recommending:  (more…)

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON December 5, 2011

After yesterday’s post concerning the media reporting on the Higgs search, a lot of people have been asking me this:  “Given that the Standard Model Higgs particle (the simplest possible Higgs particle) will be found or ruled out in the coming few months, why will it take as long as ten years to be sure nature sports no Higgs particle or particles of any type?”  (more…)

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON December 4, 2011

Did you know that most of the information produced in the proton-proton collisions at the Large Hadron Collider (LHC) is dumped irretrievably in the metaphorical trash bin — sent ingloriously into oblivion — yes, discarded permanently — as quickly as it comes in? By “most,” I don’t mean 75%. I don’t mean 95%. I mean 99.999% to 99.9999% of all the data at the Large Hadron Collider is erased within a second of its being collected.

It sounds crazy; how can a scientific experiment simply ignore the vast majority of its data?! Well, it’s not as insane as if first appears. Nor is it unprecedented; previous generations of hadron colliders have done something similar. And finally, it is absolutely necessary. In this article I’ll tell you why.

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON November 4, 2011

Ok, folks, after a few days of hard work, I have an article detailing how to look for supersymmetry, one of the most popular theories predicting new phenomena at the Large Hadron Collider.  You may first want to read about the particles of nature  and then about supersymmetry itself.

I’ve tried to take the most common answer to this question — essentially, look for an excess of collisions that produce both high energy quarks and invisible particles — and deconstruct it, showing you what it means at the level of particle physics (what is produced, what decays, how is it detected) and then work backwards to show you what physical assumptions lie underneath this answer.

I hope that once you’ve understood these assumptions, you’ll have a clearer idea what this answer’s strengths and weaknesses are.   And then we can go on, in a future post, to explore what the LHC has and hasn’t said so far about supersymmetry as a property of nature.

As always, comments on clarity and content are welcome!

8/16/11

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON August 16, 2011

Here’s an article intended to give a layperson a sense for why so many types of particles — most of them, in fact — decay away almost instantly, forcing us to discover them through various types of trickery.   This is relevant in the search for the Higgs particle, which decays away far too quickly to observe directly. (See the Higgs FAQ, the video clips from my recent public talk, or the article about recent hints of the Higgs for more info.)

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON August 4, 2011

Just finished my new article on the hints of a Higgs particle.  I hope you find it useful! I have tried to explain, in largely non-technical terms,

  • how experimentalists at the Large Hadron Collider are looking for the Higgs, using various methods;
  • what makes methods of this type easy or difficult, with analogies;
  • that the current hints of a Higgs particle rely on the more difficult techniques, making it unclear whether we should trust them;
  • that more data over the coming year will bring the simpler techniques into their own, eliminating this problem over time.

I welcome your comments, questions and advice as to how to make this article more transparent to the non-technical reader!

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON July 31, 2011

Ok, the third video clip from my talk at the Secret Science club from March 2011 is now uploaded for your enjoyment.  [But watch the other two clips first, it will make it a lot easier to follow!]  Learn how to find the Higgs particle!  (Or at least the easier ways — an explanation of the harder techniques, some of which are important in the current hints of a Higgs signal, and further details on the easier techniques, will be posted very soon.)

Attentive viewers will notice that in one of my plots of simulated data the Higgs particle has a mass between 140 and 150 GeV.  I promise you 🙂 I had no advanced warning of this month’s hints!!  […which happen currently to favor this regime…]

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON July 29, 2011

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