Round Table: Resolving Physics BSM at Low Energies

Abstract

Low-energy precision experiments can reveal physics beyond the standard model through either the observation of the violation of expected fundamental symmetries or an observed deviation from a precision calculation. We offer an overview of the possibilities, thereby illuminating the subfield's essential challenges and themes.

On the structure of the correlation coefficients S(E_e) and U(E_e) of the neutron beta decay

“…This agrees well with the result obtained by Ebel and Feldman [2]. However, in addition to the result obtained by Ebel and Feldman [2] we, following [48][49][50][51][52] (see also [3,16,18,19,47]), have taken the contributions of the phenomenological vector coupling constants C V and CV in the linear approximation, i.e. C V = 1 + δC V and CV = −1 + δ CV , where we have used the notations of [3,16,18,19,47].…”

QCD and strongly coupled gauge theories: challenges and perspectives

“…Direct searches for new particles and interactions at colliders certainly involve precision measurements and in the search for new physics in low-energy processes. There is a large array of possible observables to consider; we refer the reader to a brief, recent overview [1237], as well as to a dedicated suite of reviews [1238][1239][1240][1241][1242][1243][1244][1245]. In this chapter we describe the theoretical framework in which such experiments can be analyzed before delving more deeply into examples which illustrate the themes we have described.…”

On the correlation coefficient T(E_e) of the neutron beta decay, caused by the correlation structure invariant under discrete P, C and T symmetries

“…In addition we have calculated the contributions of interactions beyond the SM, expressed in terms of i) the phenomenological coupling constants of the effective phenomenological interactions proposed by Jackson et al [25], and ii) the phenomenological coupling constants of the second class currents, measuring the strength of G-odd correlations [66,73,74] (see also [30,31]). We have found that in the linear approximation for the phenomenological vector, axial-vector, scalar and tensor coupling constants [18][19][20][21][22] (see also [28,29,31]) the contribution of interactions beyond the SM, defined by the effective Lagrangian Eq. (25), is equal to zero, i.e.…”

“…At the replacement C V = − CV = 1, C A = − CA = g A and C S = CS = C P = CP = C T = CT = 0 the factor ξ reduces to ξ = 2(1 + 3g 2 A ). In the linear approximation for the phenomenological vector and axial-vector coupling constants C V = 1 + δC V , CV = −1 + δ CV , C A = g A + δC A and CA = −g A + δ CA the contributions of the vector and axial-vector phenomenological coupling constants can absorbed by renormalization of the axial coupling constant g A and the Cabibbo-Kobayashi-Maskawa (CKM) matrix element V ud (it is included into G V ) [18][19][20][21][22] (see also [28,29,31]). Thus, in the linear approximation for the phenomenological vector, axial-vector, scalar and tensor coupling constants [18][19][20][21][22] (see also [28,29,31]) the contribution of interactions beyond the SM, defined by the effective Lagrangian Eq.…”

“…After the discovery by Chadwick in 1932 [1], neutron has started to play an unprecedentedly important role in particle and nuclear physics, astrophysics and cosmology [2]- [8]. The experimental analysis of correlation coefficients of the neutron beta decay allows to obtain precise information about the structure of the Standard Model (SM) interactions [9][10][11][12][13][14] and interactions beyond the SM [2,3,[15][16][17] at low and high energies [18][19][20][21][22][23][24]. For the first time the most general form of the electron-energy and angular distribution of the neutron beta decay for a polarized neutron, a polarized electron and an unpolarized proton was proposed by Jackson et al [25][26][27].…”