Abstract
Chiral perturbation theory provides a systematic method for discussing the consequences of the global flavor symmetries of QCD at low energies by means of an effective field theory. The effective Lagrangian is expressed in terms of those hadronic degrees of freedom which, at low energies, appear as observable asymptotic states. At very low energies these are just the members of the pseudoscalar octet \((\pi,K,\eta)\) which are regarded as the Goldstone bosons of the spontaneous breaking of the chiral \(\hbox{SU}(3)_L\times\hbox{SU}(3)_R\) symmetry down to \(\hbox{SU}(3)_V.\) The nonvanishing masses of the light pseudoscalars in the “real” world are related to the explicit symmetry breaking in QCD by the light-quark masses
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Notes
- 1.
The toy model serves pedagogical purposes only. As a (quantum) field theory it is not consistent because the energy is not bounded from below [14].
- 2.
The existence of mass-degenerate states of opposite parity is referred to as parity doubling .
- 3.
The subscript \(V\) (for vector) indicates that the generators result from integrals of the zeroth component of vector-current operators and thus transform with a positive sign under parity.
- 4.
Recall that each quark is assigned a baryon number 1/3.
- 5.
- 6.
The commutation relations also remain valid for \(equal\) times if the symmetry is explicitly broken.
- 7.
Accordingly, the right coset of \(g\) is defined as \(Hg=\{hg|h\in H\}.\) An \(invariant\) subgroup has the additional property that the left and right cosets coincide for each \(g\) which allows for a definition of the factor group \(G/H\) in terms of the complex product. However, here we do not need this property.
- 8.
There is a subtlety here, because \(F_0\) is traditionally reserved for the three-flavor chiral limit , whereas the two-flavor chiral limit (at fixed \(m_s\)) is denoted by \(F.\) In this section, we will use \(F_0\) for both cases.
- 9.
Since the Goldstone bosons are pseudoscalars, a true parity transformation is given by \(\phi_a(t,\vec{x})\mapsto -\phi_a(t,-\vec{x})\) or, equivalently, \(U(t,\vec{x})\mapsto U^\dagger(t,-\vec{x}).\)
- 10.
In view of the coupling to the external fields \(s+ip\) and \(s-ip\) (see Eq. 1.161) to be discussed in Sect. 3.4.3, we distinguish between \({{\fancyscript{M}}}\) and \({{\fancyscript{M}}}^\dagger\) even though for a real, diagonal matrix they are the same.
- 11.
Including all of the infinite number of effective functionals \(Z^{(2n)}_{\rm eff}[v,a,s,p]\) will generate a result which is equivalent to that obtained from \(Z_{\rm QCD}[v,a,s,p].\)
- 12.
In principle, we could also “gauge” the U(1)\(_V\) symmetry. However, this is primarily of relevance to the two-flavor sector in order to fully incorporate the coupling to the electromagnetic four-vector potential (see Eq. 1.165). Since in the three-flavor sector the quark-charge matrix is traceless, this important case is included in our considerations.
- 13.
Under certain circumstances it is advantageous to introduce for each object with a well-defined transformation behavior a separate covariant derivative. One may then use a product rule similar to the one of ordinary differentiation.
- 14.
Throughout this monograph we will reserve the notation \({{\fancyscript{O}}}(q^n)\) for power counting in chiral perturbation theory, whereas \(O(x^n)\) denotes terms of order \(x^n\) in the usual mathematical sense.
- 15.
There is a certain freedom in the choice of the elementary building blocks. For example, by a suitable multiplication with \(U\) or \(U^\dagger\) any building block can be made to transform as \(V_R \ldots V_R^\dagger\) without changing its chiral order. The present approach most naturally leads to the Lagrangian of Gasser and Leutwyler [53].
- 16.
At \({{\fancyscript{O}}}(q^2)\) invariance under \(C\) does not provide any additional constraints.
- 17.
Recall that the entries \(V_{ud}\) and \(V_{us}\) of the Cabibbo-Kobayashi-Maskawa matrix are real.
- 18.
Of course, in the chiral limit, the pion is massless and, in such a world, the massive leptons would decay into Goldstone bosons, e.g., \(e^-\to\pi^-\nu_e.\) However, at \({{\fancyscript{O}}}(q^2),\) the symmetry-breaking term of Eq. 3.55 gives rise to Goldstone-boson masses, whereas the decay constant is not modified at \({{\fancyscript{O}}}(q^2).\)
- 19.
We will refer to this parameterization as the square-root parameterization because of the square root multiplying the unit matrix.
- 20.
Recall that \(\Upgamma(z)\) is single-valued and analytic over the entire complex plane, save for the points \(z=-n,\,n=0,1,2,\ldots,\) where it possesses simple poles with residue \((-1)^n/n!.\)
- 21.
Note that the convention \(\varepsilon=2-{\frac{n}{2}}\) is also commonly used in the literature.
- 22.
More generally, renormalization is simply the process of expressing the parameters of the Lagrangian in terms of physical observables, independent of the presence of divergences [51].
- 23.
Note that Ref. [43] uses a slightly different convention which corresponds to the replacement \((\delta Z_\phi M^2 +Z_\phi\delta M^2)\to\delta M^2;\) analogously for \(\delta m^2.\)
- 24.
Note that the number of independent momenta is \(not\) the number of faces or closed circuits that may be drawn on the internal lines of a diagram. This may, for example, be seen using a diagram with the topology of a tetrahedron which has four faces but \(N_L=6-(4-1)=3\) (see, e.g., Chap. 6-2 of Ref. [63]).
- 25.
In distinction to the \(\overline{\hbox{MS}}\) scheme commonly used in Standard Model calculations, the \(\widetilde{\hbox{MS}}\) scheme contains an additional finite subtraction term. To be specific, in \(\widetilde{\hbox{MS}}\) one uses multiples of \( 2/(n-4)- \left[ \ln (4\pi )+\Upgamma '(1)+1\right]\) instead of \(2/(n-4)-\left[ \ln (4\pi )+\Upgamma '(1)\right]\) in \(\overline{\hbox{MS}}.\)
- 26.
For pedagogical reasons, we make use of the physical fields. From a technical point of view, it is often advantageous to work with the Cartesian fields and, at the end of the calculation, express physical processes in terms of the Cartesian components.
- 27.
Note that we work in the three-flavor sector and thus with the exponential parameterization of \(U.\)
- 28.
When deriving the Feynman rule of Exercise 3.14, we took account of 24 distinct combinations of contracting four field operators with four external lines. However, the Feynman diagram of Eq. 3.134 involves only 12 possibilities to contract two fields with each other and the remaining two fields with two external lines.
- 29.
- 30.
The subscript ano refers to anomalous.
References
Adeva, B., et al., DIRAC Collaboration: Phys. Lett. B 619, 50 (2005)
Adler, S.L.: Phys. Rev. 177, 2426 (1969)
Adler, S.L., Bardeen, W.A.: Phys. Rev. 182, 1517 (1969)
Adler, S.L.: In: Deser, S., Grisaru, M., Pendleton, H. (eds.) Lectures on Elementary Particles and Quantum Field Theory, 1970 Brandeis University Summer Institute in Theoretical Physics, vol. 1. M.I.T. Press, Cambridge (1970)
Ahrens, J., et al.: Eur. Phys. J. A 23, 113 (2005)
Akhoury, R., Alfakih, A.: Ann. Phys. 210, 81 (1991)
Ananthanarayan, B., Colangelo, G., Gasser, J., Leutwyler, H.: Phys. Rep. 353, 207 (2001)
Antipov, Y.M., et al.: Phys. Lett. B 121, 445 (1983)
Balachandran, A.P., Trahern, C.G.: Lectures on Group Theory for Physicists. Bibliopolis, Naples (1984)
Balachandran, A.P., Marmo, G., Skagerstam, B.S., Stern, A.: Classical Topology and Quantum States (Chap. 12.2). World Scientific, Singapore (1991)
Bardeen, W.A.: Phys. Rev. 184, 1848 (1969)
Bär, O., Wiese, U.J.: Nucl. Phys. B 609, 225 (2001)
Batley, J.R., et al., NA48/2 Collaboration: Eur. Phys. J. C 54, 411 (2008)
Baym, G.: Phys. Rev. 117, 886 (1960)
Bell, J.S., Jackiw, R.: Nuovo Cim. A 60, 47 (1969)
Bijnens, J., Cornet, F.: Nucl. Phys. B 296, 557 (1988)
Bijnens, J., Bramon, A., Cornet, F.: Z. Phys. C 46, 599 (1990)
Bijnens, J.: Int. J. Mod. Phys. A 8, 3045 (1993)
Bijnens, J., Ecker, G., Gasser, J.: In: Maiani, L., Pancheri, G., Paver, N. (eds.) The Second DA\(\Phi\)NE Physics Handbook, vol. 2, pp. 125–143. SIS, Frascati (1995)
Bijnens, J., Colangelo, G., Ecker, G., Gasser, J., Sainio, M.E.: Phys. Lett. B 374, 210 (1996)
Bijnens, J., Colangelo, G., Ecker, G., Gasser, J., Sainio, M.E.: Nucl. Phys. B 508, 263 (1997)
Bijnens, J., Colangelo, G., Ecker, G.: JHEP 9902, 020 (1999)
Bijnens, J., Girlanda, L., Talavera, P.: Eur. Phys. J. C 23, 539 (2002)
Bijnens, J.: Prog. Part. Nucl. Phys. 58, 521 (2007)
Bijnens, J., Jemos, I.: In: PoS (CD09), 087 (2009)
Bissegger, M., Fuhrer, A., Gasser, J., Kubis, B., Rusetsky, A.: Phys. Lett. B 659, 576 (2008)
Bissegger, M., Fuhrer, A., Gasser, J., Kubis, B., Rusetsky, A.: Nucl. Phys. B 806, 178 (2009)
Borasoy, B., Lipartia, E.: Phys. Rev. D 71, 014027 (2005)
Burgess, C.P.: Phys. Rep. 330, 193 (2000)
Bürgi, U.: Nucl. Phys. B 479, 392 (1996)
Cabibbo, N.: Phys. Rev. Lett. 93, 121801 (2004)
Cabibbo, N., Isidori, G.: JHEP 0503, 021 (2005)
Callan, C.G., Coleman, S.R., Wess, J., Zumino, B.: Phys. Rev. 177, 2247 (1969)
Chisholm, J.: Nucl. Phys. 26, 469 (1961)
Colangelo, G., Gasser, J., Leutwyler, H.: Phys. Lett. B 488, 261 (2000)
Colangelo, G., Gasser, J., Leutwyler, H.: Phys. Rev. Lett. 86, 5008 (2001)
Colangelo, G., Gasser, J., Leutwyler, H.: Nucl. Phys. B 603, 125 (2001)
Colangelo, G., Gasser, J., Kubis, B., Rusetsky, A.: Phys. Lett. B 638, 187 (2006)
Colangelo, G., Gasser, J., Rusetsky, A.: Eur. Phys. J. C 59, 777 (2009)
Colangelo, G., et al.: arXiv:1011.4408 [hep-lat]
Coleman, S.: J. Math. Phys. 7, 787 (1966)
Coleman, S.R., Wess, J., Zumino, B.: Phys. Rev. 177, 2239 (1969)
Collins, J.C.: Renormalization. Cambridge University Press, Cambridge (1984)
Donoghue, J.F., Wyler, D.: Nucl. Phys. B 316, 289 (1989)
Donoghue, J.F.: In: PoS (EFT09), 001 (2009)
Ebertshäuser, T., Fearing, H.W., Scherer, S.: Phys. Rev. D 65, 054033 (2002)
Ecker, G., Gasser, J., Pich, A., de Rafael, E.: Nucl. Phys. B 321, 311 (1989)
Ecker, G.: arXiv:hep-ph/0507056
Fearing, H.W., Scherer, S.: Phys. Rev. D 53, 315 (1996)
Frlež, E., et al.: Phys. Rev. Lett. 93, 181804 (2004)
Gasser, J., Leutwyler, H.: Phys. Rep. 87, 77 (1982)
Gasser, J., Leutwyler, H.: Ann. Phys. 158, 142 (1984)
Gasser, J., Leutwyler, H.: Nucl. Phys. B 250, 465 (1985)
Gasser, J., Sainio, M.E., Švarc, A.: Nucl. Phys. B 307, 779 (1988)
Gasser, J., Ivanov, M.A., Sainio, M.E.: Nucl. Phys. B 745, 84 (2006)
Gell-Mann, M., Oakes, R.J., Renner, B.: Phys. Rev. 175, 2195 (1968)
Georgi, H.: Weak Interactions and Modern Particle Theory. Benjamin/Cummings, Menlo Park (1984)
Georgi, H.: Ann. Rev. Nucl. Part. Sci. 43, 207 (1993)
Gerber, P., Leutwyler, H.: Nucl. Phys. B 321, 387 (1989)
Goldstone, J., Salam, A., Weinberg, S.: Phys. Rev. 127, 965 (1962)
Guskov, A., On behalf of the COMPASS collaboration: J. Phys. Conf. Ser. 110, 022016 (2008)
Holstein, B.R.: Comm. Nucl. Part. Phys. A 19, 221 (1990)
Itzykson, C., Zuber, J.B.: Quantum Field Theory. McGraw-Hill, New York (1980)
Jones, H.F.: Groups, Representations and Physics. Hilger, Bristol (1990)
Kamefuchi, S., O’Raifeartaigh, L., Salam, A.: Nucl. Phys. 28, 529 (1961)
Kaplan, D.B.: arXiv:nucl-th/9506035
Kermani, M., et al., CHAOS Collaboration: Phys. Rev. C 58, 3431 (1998)
Knecht, M., Moussallam, B., Stern, J., Fuchs, N.H.: Nucl. Phys. B 457, 513 (1995)
Leibbrandt, G.: Rev. Mod. Phys. 47, 849 (1975)
Leutwyler, H.: In: Ellis, R.K., Hill, C.T., Lykken, J.D. (eds.) Perspectives in the Standard Model. Proceedings of the 1991 Advanced Theoretical Study Institute in Elementary Particle Physics, Boulder, CO, 2–28 June 1991. World Scientific, Singapore (1992)
Leutwyler, H.: Ann. Phys. 235, 165 (1994)
Li, L.F., Pagels, H.: Phys. Rev. Lett. 26, 1204 (1971)
Manohar, A.V., Georgi, H.: Nucl. Phys. B 234, 189 (1984)
Manohar, A.V.: arXiv:hep-ph/9606222
Nakamura, K., et al., Particle Data Group: J. Phys. G 37, 075021 (2010)
Necco, S.: In: PoS (Confinement8), 024 (2008)
O’Raifeartaigh, L.: Group Structure of Gauge Theories. Cambridge University Press, Cambridge (1986)
Pich, A.: arXiv:hep-ph/9806303
Pich, A.: In: PoS (Confinement8), 026 (2008)
Pislak, S., et al., BNL-E865 Collaboration: Phys. Rev. Lett. 87, 221801 (2001)
Pislak, S., et al.: Phys. Rev. D 67, 072004 (2003) [Erratum, ibid. D 81, 119903 (2010)]
Polchinski, J.: arXiv:hep-th/9210046
Preston, M.A.: Physics of the Nucleus. Addison-Wesley, Reading (1962)
Rosselet, L., et al.: Phys. Rev. D 15, 574 (1977)
Roy, S.M.: Phys. Lett. B 36, 353 (1971)
Scherer, S., Fearing, H.W.: Phys. Rev. D 52, 6445 (1995)
Scherer, S.: Adv. Nucl. Phys. 27, 277 (2003)
Schwinger, J.S.: Phys. Lett. B 24, 473 (1967)
Terent’ev, M.V.: Yad. Fiz. 16, 162 (1972)
Terent’ev, M.V.: Sov. J. Nucl. Phys. 16, 87 (1973)
’t Hooft, G., Veltman, M.J.: Nucl. Phys. B 44, 189 (1972)
’t Hooft, G., Veltman, M.J.: Nucl. Phys. B 153, 365 (1979)
Unkmeir, C., Scherer, S., L’vov, A.I., Drechsel, D.: Phys. Rev. D 61, 034002 (2000)
Vafa, C., Witten, E.: Nucl. Phys. B 234, 173 (1984)
Veltman, M.J.: Diagrammatica. The Path to Feynman Rules. Cambridge University Press, Cambridge (1994)
Watson, K.M.: Phys. Rev. 95, 228 (1954)
Weinberg, S.: Phys. Rev. Lett. 17, 616 (1966)
Weinberg, S.: Phys. Rev. Lett. 18, 188 (1967)
Weinberg, S.: Phys. Rev. 166, 1568 (1968)
Weinberg, S.: Physica A 96, 327 (1979)
Weinberg, S.: The Quantum Theory of Fields. Foundations, vol. I (Chap. 12). Cambridge University Press, Cambridge (1995)
Wess, J., Zumino, B.: Phys. Lett. B 37, 95 (1971)
Witten, E.: Nucl. Phys. B 223, 422 (1983)
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Scherer, S., Schindler, M.R. (2011). Chiral Perturbation Theory for Mesons. In: A Primer for Chiral Perturbation Theory. Lecture Notes in Physics, vol 830. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-19254-8_3
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