are hypothetical, real (non-virtual) particles made up of gluons, the particle of the gluon field that interacts with quarks. The gluons have a color charge themselves and they can form a bound state (the ball). According to lattice computations in Quantum Chromodynamics, they have a mass that varies from . This mean that a bound state of massless particles can form a massive particle. Is the mass of the glueball non-zero only because the constituting gluons interact strongly? Don't massless particles stay massless, even when they form a bound state? Has the glueball a velocity less than c, while the gluons themselves speed with c (which would mean that it has mass)?
From      Glueballs are predicted by quantum chromodynamics to be massive, notwithstanding the fact that gluons themselves have zero rest mass in the Standard Model. Glueballs with all four possible combinations of quantum numbers P (parity) and C (c-parity) for every possible total angular momentum have been considered, producing at least fifteen possible glueball states including excited glueball states that share the same quantum numbers but have differing masses with the lightest states having masses as low as 1.4 GeV/c2 (for a glueball with quantum numbers J=0, P=+, C=+), and the heaviest states having masses as great as almost 5 GeV/c2 (for a glueball with quantum numbers J=0, P=+, C=-).   Rather than going through a list of possible mechanisms that unfortunately I know next to nothing about, such as can the mass be attributed to virtual quarks, or binding energy between the gluons, I would rather leave the question as in the title to find out as much as I can.  Also, although the SM is firmly established, would the discovery of Glueballs buttress it further?  My apologies for not knowing more about the interior of hadron like particles or if the answer is readily available (or worse, blindingly obvious).
Highlight \verb in inline text swap x and y axis on data generated plot I am considering trying to setup a  system. It seems like this would be pretty straight forward if I had two graphics cards or if I didn't need hardware based OpenGL acceleration. Is it possible to setup a multi seat system with only a single dual-headed graphics card? combine 2 fields in 1 to use it in the "group by" section of the reports is it possible to combine two fields in one and use that field to group by in reports? for example, i would like to combine ee id and ee name fields in 1 and show as 1 field in the "group by" section on reports. Before today, I would visit Stack Overflow every day and click somewhere in the upper-left corner (I've forgotten what it said, and it's gone now!) and if I didn't have any notifications I would see a list of interesting questions from various sites in the Stack Exchange network which - I believe - were classified as "hot".  Now this new top bar has appeared, and I have no idea how to get this list any more. I'm not really sure what it was called so my searches have been useless as well. First of all, I know that light does indeed travel slower in a medium like air or water, but that's because the photons are bouncing off of the medium's particles and in different directions so the light beam as a whole is slowed down (or at least that's the classical explanation I've read somewhere).  But my question is about light traveling freely in the vacuum. What if an astronaut during a spacewalk switches on a flashlight towards the opposite direction he is moving. Will that light travel slower than normal?  If not, is there another way to make light move slower? For example, can you make a beam of light move so slow that you can visually perceive it being affected by gravity? What does the (unary) * operator do in this Ruby code? How do I install wine? Can someone please explain how I can install  in the following ways?   By using the package manager? By downloading and installing a pre-built package? How to end paragraph text in an inverted pyramid shape? In many old books, the final paragraphs of chapters end in an inverted pyramid shape, like this:    I think this is beautiful, so I would like to imitate this for my book. I've found the code for a triangle in this post   \documentclass{article} \usepackage{microtype,shapepar}  \def\triangleupshape{% {0}% {0}b{0}\\% {8.66}t{-5}{10}\\% {17.32}t{-10}{20}\\% {17.32}e{0}% }      \begin{document} \shapepar{\triangleupshape}A ipsum dolor sit amet, consectetuer    adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. \par \end{document}   Which results in this:    But I'd like it to be inverted and the first part of the paragraph need to be full line width. Only the last few lines should end in an inverted pyramid like in the example above.  Is there a way to do this? Thanks in advance for your help. Trying to show that $\ln(x) = \lim_{n\to\infty} n(x^{1/n} -1)$ How do I show that $\ln(x) = \lim_{n\to\infty} n (x^{1/n} - 1)$?  I ran into this identity on . I haven't been able to find any proof online and my efforts to get from $\ln(x) := \int_1^x \frac{\mathrm dt}t$ to that limit have been a failure. I prefer to use bm package to bold math. However, I noticed that when used with eulervm, this gives inconsistent results for ‘&lt;’ and ‘>’ characters.  I wonder what causes it and can the usage bm be fixed to get proper ‘&lt;’.  \documentclass{article}  \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc}  %\usepackage{amsmath}  \usepackage[euler-digits,euler-hat-accent]{eulervm}  \usepackage{bm}  \begin{document}      \texttt{\hphantom{mathbold}\llap{bm}}: \quad $ 1 + 1 &lt; 3; \quad \bm{1 + 1 &lt; 3} $      \texttt{mathbold}: \quad $ 1 + 1 &lt; 3; \quad \mathbold{1 + 1 &lt; 3} $  \end{document} Why is FIFA against adding instant replay to the game? Is there any evidence or reason why FIFA is so against adding instant replay to soccer? I find myself seeing many unlucky or just plain wrong decisions made by refs that could be corrected with instant replay. Easier way to debug a Windows service How do I repeat a theorem number? Often in my papers I want to mention theorems in the introduction that are introduced in more detail and proved in a later section.  I'd like to include the statement of these theorems twice over, each time numbered as the theorem would naturally appear in its later section.  My current solution (using amsthm) is, e.g.  %(in the introduction) \newtheorem*{thm:associativity}{Theorem \ref{thm:associativity}} \begin{thm:associativity} Lorem ipsum ... \end{thm:associativity}  %(in a later section) \begin{thm} \label{thm:associativity} Lorem ipsum ... \end{thm}      Can anyone think of a cleaner solution? How to interpret the margin of error in a poll? Recently the media reported on a political poll that stated that "46% of Republican voters in Mississippi think that interracial marriage should be illegal".  One example story (of many around the 'net) is this one from the NY Daily News: .  From that article:     A survey conducted last month shows 46% of GOP voters in the state   believe interracial marriage should be illegal - a plurality of the   people questioned   Given that I know many people in interracial marriages (including in my own family) I was motivated to track down the full story rather than fall to the obvious hysteria.  I located the press release on the poll from Public Policy Polling  (PDF)  which has:     46% of these hardcore Republican voters believe interracial marriage   should be illegal, while 40% think it should be legal. With Barbour   included, Huckabee gets more support (22%) from the former than the   latter (15%), as does Palin (13-6). The support for Bachmann (10-2),   Gingrich (13-8), and Pawlenty (4-1) works the opposite way.   And at the end of the first page they state:     PPP surveyed 400 usual Mississippi Republican primary voters from   March 24th to 27th. The survey’s margin of error is +/-4.9%.   Now what I don't understand is how to interpret the results especially the margin of error value.    From the raw numbers, 46% (~50%) of 400 voters is 200 voters who responded who think that interracial marriages should be illegal.  But from stats of Mississippi in the 2008 Federal election, McCain polled about 725,000 Republican votes (to Obamas 556,000). My gut feeling is that you can't extrapolate that 46% number to the other 724,600 Republican voters and still retain a 5% margin of error.  So is the media misrepresenting the numbers (really? the media would do that?!?!?!) Or are there statistics at work that I don't understand?  Thanks for your help! What logical fallacy considers a personal experience to be common place While my wife and I were discussing the news a few days ago I stated  that an argument expressed (in a news article, not by my wife) was a fallacy -- but I've been unable to put a name to it.  Basically, it is when a person experiences some experience (personally or thru acquaintance), and thus considers it a common experience because they have experienced it. Parallel universes: are there an infinite amount of universes? Parallel universe: in every universe, you are presented with a different decision. Does that mean there are an infinite amount of parallel universes? I.e., if in one universe I choose to go left, I am then presented with different choices vs if i choose right, and that creates more universes with more decisions to be made.  Or does it mean that in the end of one's life we end up in the same place, meaning that its just one parallel universe that eventually collides with the other. MySQL Access denied for user 'root'@'localhost' In my server, everytime I try to access MySQL I get the error:        Access denied for user 'root'@'localhost' (using password: NO)   when I try mysqladmin -u root -p password I get        Access denied for user 'root'@'localhost' (using password: YES)   How can I access MySQL in my Ubuntu server 12.04? $\forall x,y>0, x^x+y^y \geq x^y + y^x$ Prove that $\forall x,y&gt;0, x^x+y^y \geq x^y + y^x$   A friend of mine told me none of the teachers in my school have succeeded in proving this seemingly simple inequality (it was asked at an oral exam last year). I tried it myself, but I made no significant progress. Is there any difference in equals and == for String variables? if ('text'.equals(str))   or   if ('text' == str)   Is there any difference? If yes, then what is it?   Added, after answered.  String q = 'teXt'; system.debug('teXt'.equals(q)); // true system.debug('teXt' == q);      // true system.debug('text'.equals(q)); // false system.debug('text' == q);      // true