正弦-戈尔登方程

正弦-戈尔登方程是十九世纪发现的一种偏微分方程：

钟形孤立子

${\displaystyle \varphi _{tt}-\varphi _{xx}=\sin \varphi }$

來自下面的拉量：

${\displaystyle {\mathcal {L}}={\frac {1}{2}}(\varphi _{t}^{2}-\varphi _{x}^{2})+\cos \varphi }$

由于正弦-戈尔登方程有多种孤立子解而倍受瞩目。

名字是物理家熟悉的克莱因-戈尔登方程（Klein-Gordon）的雙關語。^[1]

孤立子解

利用分离变数法可得正弦-戈尔登方程的多种孤立子解。^[2]

扭型孤立子

${\displaystyle p1:=-4*arctan((1/2)*(1.5*exp(-4*sqrt(2))-exp(2*x*sqrt(2)))*exp(t-2-x*sqrt(2)+2*sqrt(2))*sqrt(2)/(1.5*exp(-4)+exp(2*t)))}$ 

${\displaystyle p2:=-4*arctan((1/2)*(1.5*exp(2*x*sqrt(2))-exp(-4*sqrt(2)))*exp(t-2-x*sqrt(2)+2*sqrt(2))*sqrt(2)/(1.5*exp(2*t)+exp(-4)))}$ 

Sine-Gordon kink soliton plot1

Sine-Gordon kink soliton plot2

钟型孤立子

正弦-戈尔登方程有如下孤立子解：

${\displaystyle \varphi _{\text{soliton}}(x,t):=4\arctan e^{m\gamma (x-vt)+\delta }\,}$ 

其中

${\displaystyle \gamma ^{2}={\frac {1}{1-v^{2}}}.}$ 

顺时针孤立子

反时针孤立子

双孤立子解

${\displaystyle px1:=(8*(1.5*exp(-4)+exp(2*t)))*exp(t-2-x*sqrt(2)+2*sqrt(2))*(exp(2*x*sqrt(2))+1.5*exp(-4*sqrt(2)))/(4.50*exp(-8)+2*exp(4*t)+2.25*exp(2*t-4-2*x*sqrt(2)-4*sqrt(2))+3.0*exp(2*t-4)+exp(2*t-4+2*x*sqrt(2)+4*sqrt(2)))}$ 

${\displaystyle px2:=-(8*(1.5*exp(2*t)+exp(-4)))*exp(t-2-x*sqrt(2)+2*sqrt(2))*(1.5*exp(2*x*sqrt(2))+exp(-4*sqrt(2)))/(4.50*exp(4*t)+2*exp(-8)+2.25*exp(2*t-4+2*x*sqrt(2)+4*sqrt(2))+3.0*exp(2*t-4)+exp(2*t-4-2*x*sqrt(2)-4*sqrt(2)))}$ 

Sine-Gordon colliding soltons plot1

Sine-Gordon colliding soltons plot2

Sine-Gordon bright & dark solitons plot1

& dark solitons plot2

扭型与反扭型碰撞

扭型-扭型碰撞

驻波呼吸子

大振幅行波呼吸子   小振幅呼吸子

三孤立子解

扭型行波呼吸子与驻波呼吸子碰撞

反扭型行波呼吸子与驻波波呼吸子碰撞

呼吸子解

 

正弦-戈尔登方程的呼吸子解

${\displaystyle u=4\arctan \left({\frac {{\sqrt {1-\omega ^{2}}}\;\cos(\omega t)}{\omega \;\cosh({\sqrt {1-\omega ^{2}}}\;x)}}\right),}$ 

${\displaystyle pz1:=4*arctan((28.460498941515413988*(exp(1.8973665961010275992*x)+sqrt(exp(3.7947331922020551984*x))))*sin(OmegaT)*csgn(1/cos(OmegaT))*exp(-.94868329805051379960*x)/(18.+5.*exp(1.8973665961010275992*x)))}$ 

${\displaystyle pz2:=4*arctan((28.460498941515413988*(exp(1.8973665961010275992*x)+sqrt(exp(3.7947331922020551984*x))))*sin(OmegaT)*csgn(1/cos(OmegaT))*exp(-.94868329805051379960*x)/(18.+5.*exp(1.8973665961010275992*x)))}$ 

Sine-Gordon breather plot1

Sine-Gordon breather plot2

几何解释

 

三维欧几里德空间的负常曲率曲面

根據陳省身的研究，正弦-戈尔登方程有一个几何解释：三维欧几里德空间的负常曲率曲面（偽球面）。^[3]

正弦-戈尔登方程是：^[4]

${\displaystyle \varphi _{tt}-\varphi _{xx}=\sinh \varphi }$ 

跟戶田場論（英语：Toda field theory）有關。^[5]

量子場論

正弦-戈尔登是Thirring模特（英语：Thirring model）的S對偶。

半經典量子化：^[6]

參見

• 瞬子
• 孤子
• 統計場論的Coulomb氣體

参考文献

1. Rajaraman, R. Solitons and instantons : an introduction to solitons and instantons in quantum field theory. Amsterdam https://www.worldcat.org/oclc/17480018. (1987 [printing]). ISBN 0-444-87047-4. OCLC 17480018.  请检查|date=中的日期值 (帮助); 缺少或|title=为空 (帮助)
2. Inna Shingareva Carlos Lizarraga Celaya, Solving Nonlinear Partial Differential Equations with Maple and Mathematica, p86-94,Springer
3. 陈省身 Geometrical interpretation of the sinh-Gordon equation。annals Polonici Mathematici XXXIX 1981
4. Poli︠a︡nin, A. D. (Andreĭ Dmitrievich). Handbook of nonlinear partial differential equations. 2nd ed. Boca Raton, FL: CRC Press https://www.worldcat.org/oclc/751520047. 2012. ISBN 978-1-4200-8723-9. OCLC 751520047.  缺少或|title=为空 (帮助) 引文格式1维护：冗余文本 (link)
5. Xie, Yuanxi; Tang, Jiashi. A unified method for solving sinh-Gordon-type equations. Il Nuovo Cimento B. 2006-05-10, 121 (2): 115–120. ISSN 0369-3554. doi:10.1393/ncb/i2005-10164-6. 
6. Faddeev, L.D.; Korepin, V.E. Quantum theory of solitons. Physics Reports. 1978-06, 42 (1): 1–87 [2020-02-03]. doi:10.1016/0370-1573(78)90058-3. （原始内容于2021-03-08） （英语）. 

閱讀

• Bour E (1862). "Théorie de la déformation des surfaces" （页面存档备份，存于互联网档案馆）. J. Ecole Imperiale Polytechnique. 19: 1–48.
• Rajaraman, R. (1989). Solitons and Instantons: An Introduction to Solitons and Instantons in Quantum Field Theory. North-Holland Personal Library. 15. North-Holland. pp. 34–45. ISBN 978-0-444-87047-6.
• Polyanin, Andrei D.; Valentin F. Zaitsev (2004). Handbook of Nonlinear Partial Differential Equations. Chapman & Hall/CRC Press. pp. 470–492. ISBN 978-1-58488-355-5.
• Dodd, Roger K.; J. C. Eilbeck, J. D. Gibbon, H. C. Morris (1982). Solitons and Nonlinear Wave Equations. London: Academic Press. ISBN 978-0-12-219122-0.
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