Of Particular Significance

Unexpected Decays of the Higgs Particle: What We Found

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 02/11/2014

A few weeks ago, I reported on the completion of a large project, with which I’ve been personally involved, to investigate how particle physicists at the Large Hadron Collider [LHC] could be searching, not only in the future but even right now, for possible “Exotic Decays” of the newly-discovered Higgs particle .

By the term “exotic decays” (also called “non-Standard-Model [non-SM] Decays”), we mean “decays of this particle that are not expected to occur unless there’s something missing from the Standard Model (the set of equations we use to describe the known elementary particles and forces and the simplest possible type of Higgs field and its particle).”  I’ve written extensively on this website about this possibility (see herehere,  hereherehereherehere and here), though mostly in general terms. In our recent paper on Exotic Decays, we have gone into nitty-gritty detail… the sort of detail only an expert could love.  This week I’m splitting the difference, providing a detailed and semi-technical overview of the results of our work.  This includes organized lists of some of the decays we’re most likely to run across, and suggestions regarding the ones most promising to look for (which aren’t always the most common ones.)

Before I begin, let me again mention the twelve young physicists who were co-authors on this work, all of whom are pre-tenure and several of whom are still not professors yet.  [ When New Scientist reported on our work, they unfortunately didn’t even mention, much less list, my co-authors.] They are (in alphabetical order): David Curtin, Rouven Essig, Stefania Gori, Prerit Jaiswal, Andrey Katz, Tao Liu, Zhen Liu, David McKeen, Jessie Shelton, Ze’ev Surujon, Brock Tweedie, and Yi-Ming Zhong.

The Project

With an immense variety of possible exotic decays of the observed Higgs particle, a thorough search poses a severe challenge.  Experimenters at ATLAS and CMS, the two general-purpose experiments at the LHC, have their work cut out for them. But the payoff would also be huge; if any such decay turned up, it would mean a revolutionary discovery of new forces and (almost always) new particles, ones that lie outside the Standard Model, which has stood as the predictive framework for particle physics for nearly 40 years.

Writing a paper that completely covers all the possibilities would have been impossible. We had to choose a more limited goal, and so the decision was to restrict ourselves to

It’s important to realize, then, that we left out a lot. But at least, with these restrictions, we had a finite list of cases (about 20 sub-classes) to consider, and it took us under 200 pages to do so.

Perhaps our most important observations are that:

  • Discoveries are still possible with the existing data set. CMS and ATLAS could add to our knowledge by looking more carefully at the data they already have, rather than waiting a year or two for more.
  • Some completed ATLAS and CMS searches for other phenomena, which weren’t intended for this purpose, nevertheless, according to our estimates, already put interesting and even sometimes stringent limits on non-SM Higgs decays. Of course, dedicated searches would certainly do even better.
  • There are many opportunities coming when the LHC turns on again in 2015. One of the big challenges is to assure that the trigger system, which faces even greater strain as the LHC collision energy and collision rate increase, can avoid discarding certain types of non-SM Higgs decays. This important issue must be studied this year!

Today, I’ve created a page summarizing what we know about possible Higgs decays to two new spin-zero particles, which in turn decay to quark pairs or lepton pairs according to our general expectation that heavier particles are preferred in spin-zero-particle decays. A number of theories (including models with more Higgs particles, certain non-minimal supersymmetric models, some Little Higgs models, and various dark matter models) predict this possibility.

Over the coming week or so, I’ll be adding more pages with other classes of decays, and pointing you to them as they’re ready.

Share via:


172 Responses

  1. I’m now not sure where you’re getting your info, however great topic.
    I must spend a while learning much more or working out more.
    Thank you for excellent information I used to be looking for
    this information for my mission.

  2. over the top, constituted as comfortable a shelter as could be herunterladen von buchern auf kindle over the top, constituted as comfortable
    a shelter as could be kostenloses e-book download over the top, constituted as comfortable a
    shelter as could be kostenlose bucher im pdf-format over the top, constituted as comfortable a shelter as could
    be kostenlose bucher over the top, constituted as comfortable a
    shelter as could be law books free download over the top, constituted as comfortable a
    shelter as could be e Commerce bucher kostenloser download

  3. What i do not realize is in truth how you’re no longer actually much more well-preferred than you may be right now.
    You are very intelligent. You recognize therefore considerably relating to
    this topic, produced me personally imagine it from numerous various angles.
    Its like women and men aren’t interested unless it’s one thing to do with
    Lady gaga! Your personal stuffs outstanding. All the time handle it up!

  4. fantastic points altogether, you simply gained a brand new reader.

    What could you suggest about your put up that you
    simply made a few days in the past? Any sure?

  5. Excellent items from you, man. I’ve have in mind
    your stuff previous to and you are just too magnificent.
    I actually like what you’ve obtained right here, really
    like what you are stating and the way in which wherein you say it.
    You’re making it entertaining and you continue to take care of to stay it sensible.
    I cant wait to learn much more from you. That is really a
    tremendous site.

  6. I’m curious to find out what blog system you have been working with?
    I’m experiencing some small security issues with my latest blog and I
    would like to find something more risk-free. Do you have any solutions?

  7. Link exchange is nothing else however it is only placing the other person’s
    blog link on your page at suitable place and other person will also
    do same in support of you.

  8. Whats up very cool web site!! Guy .. Excellent .. Wonderful ..
    I will bookmark your web site and take the feeds also?
    I’m satisfied to search out numerous helpful information right here
    in the put up, we’d like work out more strategies on this regard,
    thanks for sharing. . . . . .

  9. It’s not great for privacy and security when compared
    to L2TP or Open – VPN, but if your goal is to get a Korean IP address,
    then this will provide you with an easy to set up VPN, and a fast VPN connection. If you already have friends that play the game, you may want to play on the same server so that they can help you
    when you need it. Detailed product line: Include all types of web design products in your business portfolio.

  10. Good day! I could have sworn I’ve been to this blog before but after browsing through some of the post I realized it’s new to
    me. Anyhow, I’m definitely delighted I found it and I’ll be bookmarking and checking back

  11. Model’s measurements: Height 5’9″/175cm, bust 32″/81cm, waist 25″/64cm, hips 34″/86cm, gown dimension US 2.
    Designer About Charlie JadeThe Charlie Jade lady
    has a inventive soul a sense of playfulness, fantasy and shock.
    Gentle blue maxi skirt from Jean Louis Scherrer Vintage that includes a clip fastening,
    an a-line shape, patch pockets, aspect slits, a straight hem and a lightweight brown wavy
    print throughout.

  12. A fascinating discussion is worth comment. I think that you ought to
    write more about this topic, it may not be a taboo matter
    but typically folks don’t discuss such topics. To the next!

  13. Dear sir,
    I’m a 67 year old engineer and wish to thank you for your amazing website;
    I have many many questions , here is one ( which also posted under the subject : “if the Higgs field were zero…”possible fits better here):
    The Englert Brout Higgs field is giving some mass to electrons , quarks… The Higgs field is reacting with existing ( I suppose they exist before they react with the Higgs field) , let me call it pre-electron-as-we- know -it field , or a field that has not reacted yet with the Higgs field. Question : are there quanta in these fields already , electrons-light , quarks -light? If these exist ,do these travel at light speed?
    Is the Higgs field reacting with every pre-electron , pre-quark … or are there pre-electrons , pre-quarks that do not interact with the EBH field which one could call electrons-light ,quarks-light?
    Could these electrons-light , quarks –light survive as such ? Could these fields interact with each other and assemble in other structures that don’t travel at light speed any longer? Invisible because these structures likely don’t have the photon emitting mechanism. Could such structures be a candidate for dark matter?
    Thanks again

  14. The pillbox hat, very first launched by Balenciaga and later on modeled by Jackie Kennedy, grew to become 1 of the trendiest equipment of the decade. Episode 106 (Ethel’s Birthday) Air Date: 11-29-1954.Well, the movie’s themes recall another movie that came out this year which is ‘Transcendence’.My blog :: Lucy Télécharger HD

  15. I’m impressed, I have to admit. Seldom do I
    encounter a blog that’s equally educative and entertaining, and without a doubt, you’ve hit the nail
    on the head. The problem is something too few folks are speaking intelligently about.
    Now i’m very happy I stumbled across this during my hunt for something concerning this.

  16. Because many species of trout fly fishing trips as
    deep as the fishing will revolve around your rig are specific regulations for
    where you have conducted all necessary safety checks.
    Fly maggots and beetle grubs. A good idea to alpso bring new life again I don’t remember about fishing.
    Smallmouth bass fishing fanns get their bearings or even overstated in the
    sun and raincoat for fishing due to the back ground. Enjoying a weekend away from the Olympics snake wild and magnificent brownies who made the incident last Friday, Sept.

  17. Greetings! I know this is kinda off topic nevertheless I’d figured
    I’d ask. Would you be interested in trading links or maybe guest authoring a blog post
    or vice-versa? My site discusses a lot of
    the same subjects as yours and I believe we could greatly benefit from
    each other. If you’re interested feel free to shoot me an e-mail.
    I look forward to hearing from you! Fantastic blog by the way!

  18. Hey are using WordPress for your blog platform?
    I’m new to the blog world but I’m trying to gett started and create
    my own. Do you need any coding expertise to make your own blog?
    Any help would be really appreciated!

  19. Magnificent goods from you, man. I’ve understand your stuff previous to and you’re just extremely wonderful.
    I actually like what you’ve acquired here, really like what you’re saying and the way in which you say it.
    You make it enjoyable and you still care for to keep it sensible.
    I can not wait to read much more from you. This is actually a terrific web site.

  20. Hello! I could have sworn I’ve been to this blog before but after going through some of the articles I realized it’s new
    to me. Nonetheless, I’m certainly happy I found
    it and I’ll be book-marking it and checking back regularly!

  21. Undeniably believe that which you said. Your favorite reason seemed to
    be on the internet the easiest thing to be aware of.
    I say to you, I definitely get annoyed while people think about worries that they plainly do not know about.
    You managed to hit the nail upon the top as well as defined out the
    whole thing without having side effect , people can take a signal.

    Will likely be back to get more. Thanks

  22. Do you have a spam issue on this site; I also am a blogger,
    and I was wondering your situation; many of us have developed some
    nice procedures and we are looking to trade strategies with others, why
    not shoot me an email if interested.

  23. The more different ways you can incorporate the word,
    the better. I want to believe that NASCAR’s drug policy is
    for the benefit of the drivers and fans, and that it is fair and impartial.
    While there are lots ways to learn how to memorize things, the technique I
    will teach you for memorization is called the
    Memory Palace Method and has been used for thousands of years, back to the ancient Greeks.

  24. May I simply just say what a relief to find someone that actually understands what they are talking about on the internet.
    You certainly realize how to bring a problem to light and make it important.
    A lot more people must look at this and understand this side of the story.
    I was surprised you’re not more popular since you surely possess the gift.

  25. Around the mid ’90s, Japanese anime started to get very popular in the United States, causing a whole
    new level of awareness for cartoons in general.
    Didn’t the world seem a lot better during Saturday morning cartoons.
    Astro Boy was groundbreaking, as the style of animation used epitomized what would later became known throughout
    the world as “anime.

  26. Magnificent goods from you, man. I’ve understand your stuff previous to and you
    are just extremely fantastic. I actually like what you’ve acquired here,
    certainly like what you’re saying and the way in which you say it.
    You make it enjoyable and you still care for to keep it sensible.
    I cant wait to read far more from you. This is actually a terrific website.

  27. Thanks for the marvelous posting! I certainly enjoyed reading it, you could be a great author.
    I will remember to bookmark your blog and will often come back later
    in life. I want to encourage you to continue your great
    writing, have a nice holiday weekend!

  28. Hey there would you mind letting me know which web host you’re working with?
    I’ve loaded your blog in 3 different internet
    browsers and I must say this blog loads a lot quicker then most.
    Can you suggest a good hosting provider at a fair price?
    Cheers, I appreciate it!

  29. There is No tension in his face or in apprehension in his eyes.

    In 1933 he began his official football career by accepting a scholarship to Fordham University in the Bronx
    borough of New York. He turned things around and the
    team ended up finishing 11th.

  30. Hi there, You have done an incredible job. I’ll definitely
    digg it and personally suggest to my friends. I’m confident they will
    be benefited from this web site.

  31. Ruby for IIS does some patching to Rails and Ruby to allow IIS to route its
    requests to Fast – CGI and eventually to Rails. Use
    it at your own risk. SAP B1 was initially designed with International Business considerations and we know examples when major multinational corporation decided to
    switch completely from Microsoft Dynamics GP (Great Plains) to SAP Business One in its headquarters after implementing SAP Business One for Brazilian subsidiary.

  32. After we complete our evaluation the team will undoubtedly be looking to
    take the program right into a second clinical research in sufferers infected with the herpes simplex virus”.
    There is absolutely no treat for Herpes, but there’s hope for one.

  33. After I initially left a comment I appear to
    have clicked the -Notify me when new comments are added- checkbox and now each time a comment is added I recieve four emails with the exact same
    comment. Is there a way you can remove me from that service?
    Thank you!

  34. Thanks for ones marvelous posting! I definitely enjoyed reading it, you could be a great author.
    I will be sure to bookmark your blog and definitely will come back later in life.
    I want to encourage you continue your great writing,
    have a nice weekend!

  35. It’s perfect ttime to make a few plans for the longer term and it is time to be
    happy. I’ve read this submit and iif I may just
    I want to suggest yoou few fascinating issues orr advice.
    Maybe you can write next articles referring to this article.
    I want to learn more things about it!

  36. Your style is very unique in comparison to other people I’ve read stuff from.
    Thanks for posting when you’ve got the opportunity, Guess I’ll just bookmark this page.

  37. The electrician san diego electricians can evaluate
    and solve electrical problems. Instead, they distribute products from manufacturers in wholesale
    price and they get commission per sales. Workers should resist resetting the circuit
    or fuse until the cause is determined. Electrical work is very hard, difficult
    and rough tasks very vital, needy moreover an exciting
    job and the experience in electrical jobs.

  38. Electrical cords in most small appliances use cord wires of copper strands insulated with heat-resistant
    plastic. This means that once you do the service without it.
    In case they price a assistance fee, you may want to verify that the company’s repair technicians are
    always available for all the homeowners when they are needed.
    And in times like this, once in every 6 months. Generally user groups
    also post opinions on the quality of work will compensate for this.

  39. Goldberg, who overcame a harrowing drug addiction years ago, revealed
    on the Dr. It promotes gastric secretion and promotes digestion, regularizes blood pressure, eases weight reduction and fights physical and mental
    fatigue. In this day and age of plastic surgery, everyone is looking
    for different ways to perfect their body.

  40. Information auspicious writeup. It actually was as soon as a leisure accounts this. Appear complex to be able to significantly unveiled flexible on your part! Incidentally, the way may possibly most people be in contact?

  41. This is because your regular shops always forward your vehicle tristar law center to automotive transmission repair or adjustments
    can be accomplished possibly manually as
    with a stick move, you may have developed
    a leak.

  42. Fantastic good from you, man.I’ve understand your stuf previous to and you are just too magnificent.

    I actually like wbat you’ve acquired here, really like
    what you are saying aand the wayy in which you say
    it. You make it entertaining and you still care for to keep it wise.
    I can not wait to read far more from you. This is aftually a
    tremendous website.

  43. My brother recommended I may like this web site. He was once entirely right.
    This publish truly made my day. You cann’t believe just
    how so much time I had spent for this info! Thank you!

  44. You actually make it appear so easy together with your
    presentation however I find this topic to be really one thing that I think I’d
    by no means understand. It kind of feels too complex and extremely wide
    for me. I’m having a look forward in your next publish, I’ll attempt to get
    the cling of it!

  45. I absolutely love your blog and find a lot of your post’s to be
    exactly I’m looking for. Would you offer guest writers to
    write content in your case? I wouldn’t mind producing
    a post or elaborating on many of the subjects you write
    in relation to here. Again, awesome website!

  46. I blog quite often and I genuinely thank you for your information. This great article has really peaked my interest. I’m going to bookmark your blog and keep checking for new details about once per week.I opted in for your Feed too.Feel free to surf to my web-site; Fifa 15 Ultimate Team Hack

  47. بيع,شراء,بيع واشتري,بيع وشراء,مستعمل,جديد,لاب توب للبيع,سياره,سياره
    للبيع,كلب للبيع,موبايل ,لبيع,موبايل,تاب,تابلت,
    في الماركت,في الماركت
    دوت نت,بيع واشتري في الماركت,
    بيع واشتري في الماركت دوت نت,


  48. Have you ever thought about publishing an ebook or guest authoring on other blogs?
    I have a blog centered on the same ideas you discuss and would love to have you share some stories/information. I know
    my subscribers would value your work. If you are even remotely interested, feel
    free to shoot me an e mail.

  49. I loved as much as you will receive carried out right here.
    The sketch is attractive, your authored subject matter
    stylish. nonetheless, you command get got an shakiness over that you wish be delivering the
    following. unwell unquestionably come more formerly again as
    exactly the same nearly very often inside case you shield this increase.

  50. Hello! This post could not be written any better!
    Reading through this post reminds me of my good old
    room mate! He always kept chatting about this. I will
    forward this post to him. Pretty sure he will have a good read.
    Thanks for sharing!

  51. But first things first – how many chickens are you planning to raise and house in your garden. Searching the best plans that fit
    with your planning. This allows birds to balance well, to sit on their feet to keep them
    warm in the Winter, to scoot in the dark when other birds move at night, and
    to feel secure.

  52. So many beauty therapists are now providing the beauty home services using the best beauty products.
    But appropriate skincare can flip a mediocre pores and skin flawless
    also. As the song by Macy Gray goes, “There is beauty in the world.

  53. With a turnover for the group of companies over the 7 billion US dollar mark, Amway is
    a great prospect to work with. With the internet, you are now able
    to succeed using the online mlm marketing system.

    For example, if you’re looking for super deals in birthday gifts, you can type the
    related words and get the best results.

  54. Receiving such a great score is not simple nowadays.
    The price range for submission of one article by some submission services could be $20 to $40, when in fact these are article directories
    that have no prominence in the search engines. Except as provided in this paragraph, these Terms
    of Use may not be amended.

  55. Definitely believe that which you stated. Your favorite justification appeared to be on the net the simplest thing to be aware of.
    I say to you, I certainly get irked while people think about worries that they plainly don’t
    know about. You managed to hit the nail upon the top
    and also defined out the whole thing without having side-effects , people
    could take a signal. Will likely be back to get more. Thanks

  56. Je ne pensais qu’à regarder le baron. Il me semble que ses
    sœurs tout en feignant la plus grande bêtise que
    j’aie trouvé un qui me faites, casino je suis passé par ici cette année
    189. On faisait casino lever tous les feux des Indiens.
    C’était le gagne-pain de presque tous ces événements, est
    un des plus convenables pour courir vers un confessionnal et ne reconnut la fine

  57. Another type of pipe is also known as a flange plunger then I would recommend that you go into the stairwell in rez and
    notice a waterfall. You may be able to make certain that the individual you choose is licensed and certified.
    Your neighbors are tristar an excellent resource for getting the plumbers license exam.

  58. I think that everything said was very logical.

    However, think on this, suppose you were to write a killer title?
    I mean, I don’t wish to tell you how to run your website, but what if you added something that grabbed
    folk’s attention? I mean Unexpected Decays of
    the Higgs Particle: What We Found | Of Particular Significance is a little
    boring. You might glance at Yahoo’s home page and see how
    they create post titles to get people interested.

    You might add a related video or a pic or two to get readers interested about everything’ve
    got to say. In my opinion, it would make your blog a little bit more interesting.

  59. Hello there! This is kind of off topic but I need some help from an established blog.
    Is it very hard to set up your own blog?

    I’m not very techincal but I can figure things out pretty fast.
    I’m thinking about creating my own but I’m not sure where to begin. Do you have any
    tips or suggestions? Appreciate it

  60. For the kids, San Diego Zoo and Sea World are not far from the Beach Cottages.
    If you want to do nothing but rest and relax then go to a luxury hotel that has all
    the luxuries like swimming pool, spa and gym and sauna.
    There are innumerable seaside trip destinations from where you can make a variety.

  61. My story is the account of an entrepreneur victimized by the Stemberg-Romney strategy
    that used any means possible including bribery and infiltrating my organization in order to destroy a major competitor.
    Save any left over paste in an air tight container and refrigerate.
    Essentially, most of the top resulting sites show up because they have been optimized for internet search results.

  62. My doctor says that some people take even more
    without any problems. However, as with any vitamin, you should be
    careful not to overdo it. Vitamin B1 is one of the members of the vitamin B complex,
    it is also known as thiamin or thiamine.

  63. I think this is one of the most vital information for
    me. And i am glad reading your article. But should remark on some
    general things, The website style is great, the articles is really great
    : D. Good job, cheers

  64. Thanks for your marvelous posting! I actually enjoyed reading it, you’re
    a great author. I will be sure to bookmark your blog and may come back
    in the future. I want to encourage you continue your great posts, have a nice

  65. Conceptualized by Nintendo visionary Shigeru Miyamoto, Mario has enjoyed over
    30 years of video game superiority, with titles such as Donkey
    Kong, Super Mario 64, and Paper Mario and many more ranking among the top must-buy games of generations of gamers.

    Develop a fun video displaying how great it is to work together with
    your team or company. To find other fun racing games search the Internet
    for a complete list of racing games, pick your favorite and enjoy the race.

  66. Hi there are using WordPress for your site platform? I’m new to the blog world but I’m trying to get started and create my own. Do you require any coding knowledge to make
    your own blog? Any help would be really appreciated!

  67. Hi! I jhst want to offer you a big thumbs up for the great information you have got
    here on this post. I’ll be coming back to your site for more

  68. Diabetes is a highly treatable, but potentially deadly, disease if left untreated
    or undiagnosed. It was interesting to note how many of the diabetic patients
    were in the normal range (i. Track3 Diabetes Planner tracks blood glucose,
    diet, exercise, medication and insulin requirements of a diabetic

  69. Now the very first matter you must do straight away
    soon after the collision is speak to your insurance policies business.

    Only a specialized lawyer is well-versed with
    the clauses of the law and can determine how much compensation you are
    entitled to get. Finding a lawyer that specializes in auto accident law will prove vital at this point.

  70. Magnificent beat ! I wish to apprentice whilst you amend your web site,
    how can i subscribe for a blog site? The account helped me a applicable deal.
    I were tiny bit familiar of this your broadcast offered vibrant transparent concept

  71. Thanks for a marvelous posting! I truly enjoyed reading it, you will be a great author.I
    will remember to bookmark your blog and
    definitely will come back sometime soon. I want to encourage you to continue your great writing, have a nice evening!

  72. I have to thank you for the efforts you’ve put in penning
    this site. I’m hoping to see the same high-grade content from you
    in the future as well. In truth, your creative writing abilities has motivated me to get my very own site now 😉

  73. Phruit Limited designs campaigns after having a discussion with
    the client. Books and other multimedia are available for
    online viewing and instant download. Exclusively at Target:
    Hop Blu-ray Combo Pack with free wearable bunny ears and printable Easter party

  74. Thanks for another wonderful submit. The location otherwise may any one obtain that kind of information and facts in their normal great means of creating? I have a business presentation pursuing 1 week, and I am about the hunt for such info.

  75. It’s the best time to make a few plans for the future and it is time to be
    happy. I’ve read this put up and if I may just I want to suggest you
    few fascinating issues or suggestions. Maybe you can write
    next articles relating to this article. I want
    to learn even more things approximately it!

  76. Hello, i think that i saw you visited my site thus i came to “return the favor”.I am attempting to find things to improve my web site!I
    suppose its ok to use a few of your ideas!!

  77. Hmm is anyone else experiencing problems with the images on this
    blog loading? I’m trying to find out if its
    a problem on my end or if it’s the blog. Any suggestions would be greatly appreciated.

  78. Par quel mode Ainsi si vous voulez en être besoin sur
    trouver accepter et approprié succès, il est certain produits avertissement à stop intimidateurs résumé départ psn code generator telecharger voleur sûreté pour alter ego .
    ( 6 ) être adaptable – Force Loom grand que vous appréciez leur Immeuble à propos mis à nu combien vous admirer
    engagé vie . Psn Code de la morale Alternateur peut autre
    tout de commuer presque net .

  79. Wow! This can be one particular of the most useful blogs We have ever arrive across on this subject.
    Basically Great. I am also a specialist in this topic therefore I can
    understand your hard work.

  80. I am not sure where you’re getting your information, but good topic.
    I needs to spend some time learning much more or understanding
    more. Thanks for wonderful info I was looking for this information for my mission.

  81. You may have the skills to get to masters in 1v1,
    however’2v2 is a completely different story. While Halo Wars is a great RTS that plays beautifully with
    the 360s controller, the numbers don’t lie. (Oops, change the sentence because Pluto is no longer considered a planet).

  82. Thank you Matt for a very interesting and clear presented Blog. I understand that the Higgs mechanism is to explain, via the Standard Model, how elementary (not composite) particles obtain mass and especially so called massless particles. Is it not essential that the fundamental principles are first fully understood otherwise there is a risk to science, where the starting point is evidentially based on an incorrect assumption or understanding, of questioning the validity in any further developments.

    If you take Einstein’s formulation E = hf , the energy of photons related to their wave frequency, then you have a reference or starting point of (h) Planck’s constant; the minimum quanta of energy, which suggests, in this formulation, that photons emanate with a minimum rest energy.

    Long wave radio frequencies of <= 1 Hz plainly points to Einstein's formulation being incorrect at these frequencies. (At 1 Hz photons moving towards the speed of light are instead at rest or, at the lower frequencies, are below the minimum quanta of energy.) Not going into too much detail to keep this comment short, on investigation, this inaccuracy in Einstein's formulation extends but diminishes towards 10^10 Hz. Using Einstein's relativistic equation – denoted by gamma (γ) – rectification of this inaccuracy at lower frequencies is by E = hγ. Thereby, if a photon was at rest (where γ = 1) would retain a rest energy of h (and a rest mass of 4.14 x 10^-21 MeV/c^2).

    Further, from investigation, the values of γ and f converge towards 10^10 Hz allowing the eventual infinity, produced by γ, to be renormalized by: γ = f (validating E = hf). The renormalization of γ would then establish particle velocities (v) to be directly related to their frequencies: v = c – (1/f); used to ascertain γ in reconciling the inaccuracy in Einstein's original formulation at lower frequencies.

    But then again I am not a scientist so what do I know! http://scienceau.com

  83. Matt
    Thank you. This explanation and rereading your earlier posts on the subject greatly relieved my confusion. I deeply appreciate the time you took to explain this yet again. I also just completed professor Lederman’s book, Beyond the God Particle(he seem intent on maintaining that name). That book in combination with your explanations have been most enlightening.

    Also, thanks to, Doc, for providing an additional reference. I am beginning my day with a deeper understanding of this subject, which brings me great joy.

  84. Thank you, Matt, for taking the time to explain this. It is more clear, however still somewhat confusing to me. I will go back and read your references on this subject more carefully. Something still is not adding up for me, but as you say it can be confusing for non experts and I am clearly no expert. Thanks, again.

    1. It would definitely have been easier if the term “mass” hadn’t gotten multiple definitions!

      The key point is that there’s a famous formula relating energy, momentum and mass for particles:

      E^2 – (pc)^2 = (mc^2)^2

      where “m” means “rest mass” and c is the speed of light. This is the formula that particle physicists stick with; you notice E = mc^2 only if a particle is at rest, i.e. p=0. Then it is easy to say what is happening. The Higgs field produced the electron’s m; the particle’s motion, however, determines p, and the combination determines E. In Newton’s theory, m would have produced gravity. But in Einstein’s theory, E and p produce the gravity. Now it is true that if p = 0, E and m are proportional, so Newton’s theory looks just like Einstein’s for a stationary (or very slow) object, like the Earth relative to the Sun. But in Newton’s theory, a massless particle (m=0, E=pc) produces no gravity because m is zero, while in Einstein’s theory a massless particle DOES produce gravity because E isn’t zero. The fact that light rays will deflect each other gravitationally is the statement that E produces the gravity, not the [rest] mass m.

      Now if you simply DEFINE relativistic mass to be E/c^2, as many people do (or something similar), then indeed it will appear from this point of view that relativistic mass (also known as “energy”, up to a constant) produces gravity. But that’s not the same as rest mass. A photon has a relativistic mass but no rest mass. Particle physicists hate this kind of confusing talk, and are very clear about it within their own community: photons have energy and no mass, and the energy is what generates the gravity. I’ve never heard a modern professional theoretical particle physicist or string theorist use relativistic mass as a concept.

      1. If I’m not mistaken, for a few years after Einstein published his paper on GR, there was some arguing among physicists about “rest mass” and “relativistic mass”, until the issue was settled and from that moment on, nobody would use these two terms anymore, as you have stated that is the norm among experts nowadays.

        1. Einstein took both points of view during his life, which confused matters further. His view late in life is concordant with the one particle physicists use today, whose value only became clear as particle physics developed further.

          One sees articles for the public regularly using the old view, and first-year physics textbooks are incredibly confusing on the matter.

          1. It is my understanding that we should always consider the pythagorean relationship as the “complete picture” regarding mass, energy and momentum: E^2 – (pc)^2 = (mc^2)^2

            With this in mind as the only complete picture for any particle and for any physical body, we should always be on the safe side.

            But for this to be useful, we must know for each particle and body what numerical values apply for each term: in the case of a massless particle like the photon, in this case, massless means that it does not have rest mass, so, the term (mc^2)^2 will be equal to zero since m is the rest mass, which is equal to zero, and this is what precisely it is meant when we say “the photon is massless”.

  85. Matt said
    There’s no connection with space or space-time curvature; see above article. There is absolutely no connection between the Higgs field (which gives things their rest mass) and gravity (which in Einstein’s theory, unlike Newton’s, responds to their energy and momentum.)

    I am not sure I understand the statment above. If the Higgs field gives some particles(it is my understanding that not all particles get their mass from the Higgs field) their mass and if in GR mass of an object tells space how to curve, which tells objects how to move in space(gravity), then how is there not connection between the HIggs field and gravity.

    Or is there no connection between the concept of mass on the quantum level and mass on the scale of the universe?

    1. The Higgs field gives particles their mass (as particle physicists mean it: that is, what some people call their “rest” mass, or “invariant” mass. I call it “mass” on this website.)

      In GR, energy and momentum, not [rest] mass, tell space how to curve. Some people confuse the issue by defining energy and mass to be equal, up to a factor of c^2; but that definition of mass is called “relativistic” mass, and is NOT, generally, what the Higgs provides. (I don’t use “relativistic mass” on this website; I call it “energy”.)

      A photon always has energy; therefore every photon has zero rest mass and non-zero relativistic mass. Do you want to call it a massless particle or not?

      This is continually confusing to non-experts, because there are two entirely different interpretations of the equation E=mc^2, and if you confuse one for the other, you will remain confused forever about this issue. See http://profmattstrassler.com/articles-and-posts/particle-physics-basics/mass-energy-matter-etc/more-on-mass/the-two-definitions-of-mass-and-why-i-use-only-one/ Actually in general relativity this can even become a little more confusing, but I’ll skip that point.

      If a particle is at rest, or moving very slowly, then its energy equals its rest mass times c^2. In that case ONLY, the curvature of spacetime is proportional to the [rest] mass, which is what the Higgs provides. That’s the case in which Newton’s theory and Einstein’s theory of gravity agree.

      But photons have no rest mass, yet a photons will most definitely curve space-time. That’s because they have energy, even though they have no rest mass.

      All of this is to say that when you said “If the Higgs field gives some particles(it is my understanding that not all particles get their mass from the Higgs field) their mass and if in GR mass of an object tells space how to curve”, you can either say that your second clause is simply wrong (because it’s energy and momentum which does the job) or you can say that you used one definition of mass [rest mass] in the first clause and a different definition of mass [relativistic mass] in the second clause. I prefer to say it the first way because I don’t want two definitions of mass running around.

  86. So, to me, this leads to at least two questions:

    a) Is the LHC capable to detect this Higgs “force”, some time in the future, either with its current design or with some possible modification?

    b) How important would this validation of the theory be in terms of its prospect for “New Physics”?

    1. The LHC can potentially do it if measurements of W particle pair production are accurate enough by 2025 or so. IF not, a proposed International Linear Collider would be able to; precision measurements of top quark/anti-quark pair production are needed. Alternatively, dark matter might show up in dark matter detectors through Higgs force interactions, but that’s a long shot.

      I don’t think this validation is going to be that important; if the theory’s invalid in this regard, we’ll probably discover that in some other way first.

  87. If I remember right, Matt has remarked earlier that exchange of Higgs also can result in a force. It may be difficult to detect in presence of other forces, but just because it has spin zero, it is not disqualified as a force carrier, I think!! Actually in QFT exchange of any particle can be thought of as exerting a force on the particles exchanging that. I would like Matt to correct this statement or support it!!

        1. Look up Yukawa forces; a boson (a pion, in particular) is formed as a bound state made from fermions, and helps bind protons and neutrons into nuclei. This is what I called the “residual strong nuclear force” in my articles on nuclei.

      1. Thanks for the reply. I would like to understand why fermion exchange has a shorter range than boson exchange, If it is a long argument, do you have a reference handy?

  88. As far as I know (I’m not an expert), forces are mediated by vector bosons (bosons with spin larger than zero).

    The Higgs, both predicted by the theory and validated by experiments at the LHC, is a scalar boson.

    As far as we know, this Higgs boson could not be the mediator of a force.

  89. The Higgs is not like any other particle, at least for now.

    It is the first scalar boson that is detected in nature.

    Even though the Higgs boson is not a force mediator (like the photon or the Z boson), it is an elementary particle, like the vector bosons that mediate forces.

    1. Gaston,

      Exactly, which is why many prefer to call it the Higgs particle rather than Higgs boson. Spin zero perhaps contributes an extra layer of suspicion.

      However, would it not be incredible to one day discover that the Higgs actually does mediate a force, one that (besides gravity) is evidently unaccounted for in the SM? Could that even be possible??

      1. That’s really not right. “Boson” means any integer spin, not just spin zero. And we know the Higgs particle is a boson, because it decays to two photons, a combination of particles whose spin must be an integer.

        The reason I generally don’t use “boson” is that it sounds more mysterious than it is. There are lots of other bosons in nature; photons, W’s, Z’s, gluons, gravitons, composite objects like pions, hydrogen atoms, helium nuclei, etc.

        The Higgs IS predicted to mediate a force in the Standard Model: http://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-known-forces-of-nature/the-strength-of-the-known-forces/

        1. Thanks Matt. I thimk my very poorly worded first paragraph failed to convey my meaning, which is the following: While all bosons are, by definition, particles with integer spin, suspicion is cast on the Higgs because it is the only known elementary particle with spin zero. I need to be much more careful with my verbiage 😉

      2. All bosons are particles.

        Particles are either fermions or bosons, either elementary or composite.

        Fermions (both elementary and composite) have a non integer value of spin, and are affected by Pauli’s exclusion principle when under bounded systems.

        Bosons (both elementary and composite) have an integer value of spin, and are not affected by Pauli’s exclusion principle under no circunstance.

        The name used for any given particle is just a naming convention, and the convenient conventions could change over time.

        We could just call it “Peter’s thang”, but it does not sound “scientificky” enough, isn’t it?

        1. A nice example is the laser beam, which wouldn’t be phycially possible if photons (a type of spin 1 boson) obeyed the exclusion principle.

    2. First “apparently-elementary” scalar boson.

      And it is a force mediator, see below. Note this force is not related to how the Higgs field gives masses to particles, however.

      1. I read out there somewhere that only vector bosons could be force mediators, or something of that sort, but clearly it is the wrong concept.

        I apologize for conveying wrong info.

        Kind regards, GEN

            1. A) I think that’s true, but maybe I’m forgetting something at the moment. Worth emphasizing that it’s the boson FIELD, not its particle, which is responsible. http://profmattstrassler.com/articles-and-posts/particle-physics-basics/mass-energy-matter-etc/the-energy-that-holds-things-together/

              B) True for all known *elementary* bosons, and true for pions, which are hadrons (http://profmattstrassler.com/articles-and-posts/largehadroncolliderfaq/whats-a-hadron-as-in-large-hadron-collider/ ). Not true, say, for hydrogen atoms, at least not in the sense we mean it here.

  90. What interest me more than what residues the Higgs gives is whether you could measure with this big machine how the Higgs mechanism does its work. What it is supposed to do is couple the gravitation potential of fermions to the gravitation potential of the massive bosons. Or with other words how this mechanism couples space curvature caused by fermions to space curvature that is caused by massive bosons.
    Are you sure that the Higgs is an elementary particle? Or with other words that it is not a composite?
    Did you find any means to explain the origin of space curvature. If not why does this community then state that the Higgs provides mass to (certain kinds of) elementary particles?
    Without the Higgs mechanism the Higgs is just another particle. What are its potentials? What is the difference between these potentials and the Higgs field. How does the Higgs particle generate its Higgs field? How does any particle generate its fields?

    1. Ok — a few things to fix here. First, the gravitational potential has nothing to do with this; http://profmattstrassler.com/2012/10/15/why-the-higgs-and-gravity-are-unrelated/ . So the last two sentences of your first paragraph are mistaken. If you have a little univeristy math background you may want to read http://profmattstrassler.com/articles-and-posts/particle-physics-basics/how-the-higgs-field-works-with-math/ , which is based on http://profmattstrassler.com/articles-and-posts/particle-physics-basics/fields-and-their-particles-with-math/ .

      We are not sure the Higgs particle is elementary, although so far it is behaving like an elementary particle. Measurements continue. http://profmattstrassler.com/articles-and-posts/the-higgs-particle/taking-stock-of-the-higgs-jan-2013/2-perhaps-composite/

      There’s no connection with space or space-time curvature; see above article. There is absolutely no connection between the Higgs field (which gives things their rest mass) and gravity (which in Einstein’s theory, unlike Newton’s, responds to their energy and momentum.)

      Finally, you have things backwards; all particles are ripples in their own fields. The Higgs particle is a ripple in the Higgs field just as the photon is a ripple in the electromagnetic field and a muon is a ripple in a muon field, etc. The fields that particles emit — such as the electric field emitted by muon — is a result of a fundamental interaction between electric fields and muon fields. I have written extensively about these things on this website; try googling “Of Particular Significance particles ripples” and things like that and you should find the answers to your questions.

  91. Matt: In the triggering process, did they keep all the events where an unknown particle was produced with an energy around 125 GeV. If I remember right, Higgs was mainly identified in two photon and four leptons channels, everything else was background(?) Just curious how many such events are saved in the data set?

    1. “did they keep all the events where an unknown particle was produced with an energy around 125 GeV?” You can’t do that, for a host of reasons. (a) You can’t identify events as having unknown particles; if you could, that would make discoveries pretty easy. You can only identify them by collecting all events that possibly could contain such particles, and then looking for deviations from the predictions of the Standard Model. (b) Unless the events are already easy to trigger on for other reasons, then they almost certainly include particles that are challenging to measure well, if at all (jets from quarks and gluons, taus, neutrinos). In this case you may not be able to reconstruct the mass of any particle that MIGHT have been produced to better than 10-20%, especially in the quick moment that the trigger system has availale. (c) Stray jets are always produced, and it’s not generally clear whether you should include them in your best guess as to the mass of any new particle that MIGHT have been produced; so this leads to ambiguities. (d) The number of events in which two jets are produced with an observed invariant mass of ~110-140 GeV/c^2, which (because of measurement uncertainties) could in principle have come from a particle of mass 125 GeV/c^2, exceeds Higgs production by hundreds of thousands. You can’t store all those events.

  92. Does “more Higgs particles” imply more or different Higgs fields than the field associated with the Higgs particle already detected? If so can all of these fields be unified?

    1. Yes, it implies more Higgs fields, whose ripples are more types of Higgs particles. They’re quite easy to come by.

      “Unified” depends on your point of view. Generally, at this stage, we’re not really worrying about that issue. To unify a group of things, you have to have the complete list of them, which means you have to first discover all of them (or most of them, so you can guess what might be missing). But to show that there’s something interesting going on, you only need to discover one of them. Let’s start with that!

    1. It has nothing to do with the collisions. The collisions are the same as always; the Higgs is produced in the same ways as usual; only the decay of the Higgs is different.

  93. Matt,

    You mentioned the following: “decays in which the number of observable electrons, muons, taus, photons, quarks, or gluons (or their anti-particles) is at most 4.”

    Could you explain the main reasons for the limit of “at most 4”.?

    Is it because the amount of possible decay paths to evaluate for larger sets (larger than 4) of particle is too large to tackle?

    Is it because there is another technical limitation, like say, the information already captured at the LHC precludes the analysis of decays with larger sets?

    Any other reason I can’t imagine at this time?

    Kind regards, GEN

    1. As you suspected: the number of options simply spirals out of control as one goes above 4.

      Although this wasn’t a reason we didn’t explore them, more complex decays are also often more technically difficult to discover. The Higgs mass-energy of 125 GeV is fixed, and unless it’s produced with a very high velocity, which is rare, its total energy is rarely above 200 GeV. If it decays to 4 particles, those particles typically have 30-50 GeV, and it is common for one of them to have energy below 20. If it decays to 8 particles, divide those numbers by two. Well, particles with 10 GeV of energy are commonly going to be lost — just too hard to detect amid all of the debris from the proton-proton collisions. Moreover, with 8 particles, the probability that one of them goes into a region of the detector which is not instrumented (e.g., a region with cables) is becoming high. Finally, the background processes (i.e. other, Standard Model processes that mimic the signal) are harder and harder to model as the number of particles increases. So as the numbers of particles go up, the strategies required become more and more difficult, optimization becomes more and more non-obvious, efficiency for detecting the events becomes lower and lower, and it’s harder and harder for theorists to study the processes and help determine the best strategies.

Leave a Reply


Buy The Book

A decay of a Higgs boson, as reconstructed by the CMS experiment at the LHC


The idea that a field could be responsible for the masses of particles (specifically the masses of photon-like [“spin-one”] particles) was proposed in several papers

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 04/16/2024

Although I’ve been slowly revising the Higgs FAQ 2.0, this seemed an appropriate time to bring the Higgs FAQ on this website fully into the

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 04/15/2024