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| {{Quantum field theory}}
| | If you have the desire to process settings swiftly, loading files quickly, however the body is logy and torpid, what would you do? If you are a giant "switchboard" that is lack of efficient management system and powerful housekeeper, what would you do? If you have send the exact commands to your mind, nevertheless the body cannot do properly, what would you do? Yes! You need a full-featured repair registry!<br><br>We can reformat the computer to make it run faster. This might reset the computer to when we first used it. Always remember to back up all files and programs before doing this because this can remove the files from the database. Remember before you do this we need all motorists plus installation files plus this should be a last resort should you are trying to find slow computer tips.<br><br>With the Internet, the risk to your registry is much more plus windows XP error messages may appear frequently. Why? The malicious wares like viruses, Trojans, spy-wares, ad wares, plus the like gets recorded too. Cookies are perfect examples. You reach save passwords, and stuff, proper? That is a easy illustration of the register functioning.<br><br>Windows errors is caused by any amount of factors, however there's almost constantly 1 cause. There's a hidden piece of the program which is responsible for making 90% of all Windows errors, and it's called the 'registry'. This really is the central database for your program and is where the computer stores all its program files plus settings. It's a important part of Windows, that is should be capable to function. However, it's additionally among the biggest causes of difficulties on the PC.<br><br>After that, I additionally purchased the Regtool [http://bestregistrycleanerfix.com/tune-up-utilities tuneup utilities] Software, plus it further protected my laptop having system crashes. All my registry issues are fixed, plus I could function peacefully.<br><br>Another key element when you compare registry cleaners is having a center to manage the start-up jobs. This just signifies to select what programs we would like to commence when we begin the PC. If you have unwanted programs starting whenever you boot up a PC this can cause a slow running computer.<br><br>Why why this really is significant, is considering various of the 'dumb' registry products actually delete these files without even recognizing. They simply browse through your registry and try plus find the most issues possible. They then delete any files they see fit, plus considering they are 'dumb', they don't really care. This signifies that if they delete a few of these vital program files, they are really going to cause a LOT more harm than superior.<br><br>Registry cleaners will aid the computer run inside a more efficient mode. Registry cleaners must be part of the standard scheduled repair program for your computer. You don't have to wait forever for your computer or the programs to load and run. A small repair usually bring back the speed you lost. |
| {{about||the Murray–von Neumann coupling constant|von Neumann algebra|the coupling constant in NMR spectroscopy|Nuclear magnetic resonance spectroscopy|and|Proton NMR|coupling strength in bibliometrics|Bibliographic coupling}}
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| In [[physics]], a '''coupling constant''' is a number that determines the strength of the [[force]] exerted in an [[Fundamental interaction|interaction]]. Usually, the [[Lagrangian]] or the [[Hamiltonian mechanics|Hamiltonian]] of a system describing an interaction can be separated into a ''kinetic part'' and an ''interaction part''. The coupling constant determines the strength of the interaction part with respect to the kinetic part, or between two sectors of the interaction part. For example, the [[electric charge]] of a particle is a coupling constant.
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| A coupling constant plays an important role in dynamics. For example, one often sets up hierarchies of approximation based on the importance of various coupling constants. In the motion of a large lump of magnetized iron, the magnetic forces are more important than the gravitational forces because of the relative magnitudes of the coupling constants. However, in [[classical mechanics]] one usually makes these decisions directly by comparing forces.
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| ==Fine-structure constant==
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| The coupling constant arises naturally in a [[quantum field theory]]. A special role is played in relativistic quantum theories by coupling constants which are [[dimensionless]], i.e., are pure numbers. For example, the [[fine-structure constant]],
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| ::<math>\alpha = \frac{e^2}{4\pi\varepsilon_0\hbar c}</math>
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| (where '''<math>e</math>''' is the [[Elementary charge|charge of an electron]], '''<math>\varepsilon_0</math>''' is the [[permittivity of free space]], '''<math>\hbar</math>''' is the [[reduced Planck constant]] and '''<math>c</math>''' is the [[speed of light]]) is such a dimensionless coupling constant that determines the strength of the [[electromagnetic force]] on an electron.
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| ==Gauge coupling==
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| In a non-Abelian gauge theory, the '''gauge coupling parameter''', '''<math>g</math>''', appears in the [[Lagrangian]] as
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| ::<math>\frac1{4g^2}{\rm Tr}\,G_{\mu\nu}G^{\mu\nu}</math>
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| (where '''<math>G</math>''' is the gauge [[field (physics)|field]] tensor) in some conventions. In another widely used convention, '''<math>G</math>''' is rescaled so that the coefficient of the kinetic term is 1/4 and '''<math>g</math>''' appears in the [[covariant derivative]]. This should be understood to be similar to a dimensionless version of the electric charge defined as
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| ::<math>\sqrt{4\pi\varepsilon_0\alpha}.</math>
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| ==Weak and strong coupling==
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| In a [[quantum field theory]] with a dimensionless coupling constant ''g'', if ''g'' is much less than 1 then the theory is said to be ''weakly coupled''. In this case it is well described by an expansion in powers of ''g'', called [[perturbation theory (quantum mechanics)|perturbation theory]]. If the coupling constant is of order one or larger, the theory is said to be ''strongly coupled''. An example of the latter is the [[hadron]]ic theory of [[strong interaction]]s (which is why it is called strong in the first place). In such a case non-perturbative methods have to be used to investigate the theory.
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| ==Running coupling==
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| [[Image:Renormalized-vertex.png|right|200px|Virtual particles renormalize the coupling]]
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| One can probe a [[quantum field theory]] at short times or distances by changing the wavelength or momentum, '''k''', of the probe one uses. With a high frequency (i.e., short time) probe, one sees [[virtual particles]] taking part in every process. This apparent violation of the [[conservation of energy]] can be understood heuristically by examining the [[uncertainty relation]]
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| :<math>\Delta E\Delta t\ge\hbar,</math>
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| which allows such violations at short times. The previous remark only applies to some formulations of quantum field theory, in particular, [[canonical quantization]] in the [[interaction picture]]. In other formulations, the same event is described by "virtual" particles going off the [[mass shell]]. Such processes [[renormalization|renormalize]] the coupling and make it dependent on the energy scale, <math>\mu</math> at which one observes the coupling. The dependence of a coupling ''g''(μ) on the energy-scale is known as running of the coupling. The theory of the running of couplings is known as the [[renormalization group]].
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| ==Beta functions==
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| {{main|Beta function (physics)}}
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| In quantum field theory, a ''beta function'' β(''g'') encodes the running of a coupling parameter, ''g''. It is defined by the relation
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| ::<math>\beta(g) = \mu\frac{\partial g}{\partial \mu} = \frac{\partial g}{\partial \ln \mu},</math>
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| where μ is the energy scale of the given physical process. If the beta functions of a quantum field theory vanish, then the theory is [[Conformal field theory|scale-invariant]].
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| The coupling parameters of a quantum field theory can flow even if the corresponding classical [[field (physics)|field]] theory is [[Scale invariance|scale-invariant]]. In this case, the non-zero beta function tells us that the classical scale-invariance is [[Conformal anomaly|anomalous]].
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| ==QED and the Landau pole==
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| If a beta function is positive, the corresponding coupling increases with increasing energy. An example is [[quantum electrodynamics]] (QED), where one finds by using [[Perturbation theory (quantum mechanics)|perturbation theory]] that the [[beta function (physics)#Examples|beta function]] is positive. In particular, at low energies, α ≈ 1/137, whereas at the scale of the [[Z boson]], about 90 [[GeV]], one measures α ≈ 1/127. | |
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| Moreover, the perturbative beta function tells us that the coupling continues to increase, and QED becomes ''strongly coupled'' at high energy. In fact the coupling apparently becomes infinite at some finite energy. This phenomenon was first noted by [[Lev Landau]], and is called the [[Landau pole]]. However, one cannot expect the perturbative beta function to give accurate results at strong coupling, and so it is likely that the Landau pole is an artifact of applying perturbation theory in a situation where it is no longer valid. The true scaling behaviour of <math>\alpha</math> at large energies is not known.
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| ==QCD and asymptotic freedom==
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| In non-Abelian gauge theories, the beta function can be negative, as first found by [[Frank Wilczek]], [[David Politzer]] and [[David Gross]]. An example of this is the [[beta function (physics)#Examples|beta function]] for [[Quantum Chromodynamics]] (QCD), and as a result the QCD coupling decreases at high energies.
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| Furthermore, the coupling decreases logarithmically, a phenomenon known as [[asymptotic freedom]] (the discovery of which was awarded with the [[Nobel Prize in Physics]] in 2004). The coupling decreases approximately as
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| ::<math> \alpha_s(k^2) \ \stackrel{\mathrm{def}}{=}\ \frac{g_s^2(k^2)}{4\pi} \approx \frac1{\beta_0\ln(k^2/\Lambda^2)},</math>
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| where β<sub>0</sub> is a constant computed by Wilczek, Gross and Politzer.
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| Conversely, the coupling increases with decreasing energy. This means that the coupling becomes large at low energies, and one can no longer rely on [[Perturbation theory (quantum mechanics)|perturbation theory]].
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| ==QCD scale==
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| In [[quantum chromodynamics]] (QCD), the quantity Λ is called the '''QCD scale'''. The value is
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| ::<math>\Lambda_{MS} = 217^{+25}_{-23}{\rm\ MeV}.</math>
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| This value is to be used at a scale above the bottom [[quark]] mass of about 5 [[GeV]]. The meaning of Λ<sub>MS</sub> is given in the article on [[dimensional transmutation]]. | |
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| The [[proton-to-electron mass ratio]] is primarily determined by the QCD scale.
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| ==String theory==
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| A remarkably different situation exists in [[string theory]]{{why|date=December 2013}}. Each perturbative description of string theory depends on a string coupling constant. However, in the case of string theory, these coupling constants are not pre-determined, adjustable, or universal parameters; rather they are dynamical [[scalar field]]s that can depend on the position in space and time and whose values are determined dynamically.
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| ==See also==
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| *[[Canonical quantization]], [[renormalization]] and [[dimensional regularization]]
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| *[[Fine structure constant]]
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| *[[Gravitational coupling constant]]
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| *[[Quantum field theory]], especially [[quantum electrodynamics]] and [[quantum chromodynamics]]
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| *[[Gluon field]], [[Gluon field strength tensor]]
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| ==References==
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| <!--<references/>-->
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| *''An introduction to quantum field theory'', by M.E.Peskin and H.D.Schroeder, ISBN 0-201-50397-2
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| ==External links==
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| *[http://www.nobelprize.org/nobel_prizes/physics/laureates/2004/ The Nobel Prize in Physics 2004 – Information for the Public]
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| *[http://hyperphysics.phy-astr.gsu.edu/hbase/forces/couple.html Department of Physics and Astronomy of the Georgia State University - Coupling Constants for the Fundamental Forces]
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| [[Category:Interaction]]
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| [[Category:Quantum field theory]]
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| [[Category:Quantum mechanics]]
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| [[Category:Statistical mechanics]]
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| [[Category:Renormalization group]]
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If you have the desire to process settings swiftly, loading files quickly, however the body is logy and torpid, what would you do? If you are a giant "switchboard" that is lack of efficient management system and powerful housekeeper, what would you do? If you have send the exact commands to your mind, nevertheless the body cannot do properly, what would you do? Yes! You need a full-featured repair registry!
We can reformat the computer to make it run faster. This might reset the computer to when we first used it. Always remember to back up all files and programs before doing this because this can remove the files from the database. Remember before you do this we need all motorists plus installation files plus this should be a last resort should you are trying to find slow computer tips.
With the Internet, the risk to your registry is much more plus windows XP error messages may appear frequently. Why? The malicious wares like viruses, Trojans, spy-wares, ad wares, plus the like gets recorded too. Cookies are perfect examples. You reach save passwords, and stuff, proper? That is a easy illustration of the register functioning.
Windows errors is caused by any amount of factors, however there's almost constantly 1 cause. There's a hidden piece of the program which is responsible for making 90% of all Windows errors, and it's called the 'registry'. This really is the central database for your program and is where the computer stores all its program files plus settings. It's a important part of Windows, that is should be capable to function. However, it's additionally among the biggest causes of difficulties on the PC.
After that, I additionally purchased the Regtool tuneup utilities Software, plus it further protected my laptop having system crashes. All my registry issues are fixed, plus I could function peacefully.
Another key element when you compare registry cleaners is having a center to manage the start-up jobs. This just signifies to select what programs we would like to commence when we begin the PC. If you have unwanted programs starting whenever you boot up a PC this can cause a slow running computer.
Why why this really is significant, is considering various of the 'dumb' registry products actually delete these files without even recognizing. They simply browse through your registry and try plus find the most issues possible. They then delete any files they see fit, plus considering they are 'dumb', they don't really care. This signifies that if they delete a few of these vital program files, they are really going to cause a LOT more harm than superior.
Registry cleaners will aid the computer run inside a more efficient mode. Registry cleaners must be part of the standard scheduled repair program for your computer. You don't have to wait forever for your computer or the programs to load and run. A small repair usually bring back the speed you lost.