Production of the neutral top-pion at theeγcolliders

Abstract

In the framework of the top-color-assisted technicolor ͑TC2͒ model, we study a neutral top-pion production process e Ϫ ␥→e Ϫ ⌸ t 0 in this paper. Our results show that the production cross section of e Ϫ ␥→e Ϫ ⌸ t 0 can reach the level of several tens of femtobarns, and over 10 3 neutral top-pion events can be produced in the planned e ϩ e Ϫ linear colliders each year. Therefore, such a top-pion production process provides us a unique chance to detect top-pion events and test the TC2 model. On the other hand, the cross section of e Ϫ ␥ →e Ϫ ⌸ t 0 is about one order of magnitude larger than those of some similar processes in the standard model ͑SM͒ and the minimally supersymmetric standard model ͑MSSM͒ ͓i.e., e Ϫ ␥→e Ϫ H in the SM and e Ϫ ␥ →e Ϫ H 0 (A 0 ,h 0 ) in the MSSM͔. So we can easily distinguish the neutral top-pion from other neutral Higgs bosons in the SM and MSSM.

SO(10) thick branes and perturbative stability

“…The perturbative stability of scenarios were studied and as a result we find that gravitation favors the stability of the SO(10) walls and its absence, on the contrary, weakens the integrity of the scenarios. In flat case, in addition to four-dimensional translation mode, massive states and tachyonic Pöschl-Teller states along SO(10) and SO (6) for the symmetric and asymmetric kink respectively are obtained in the spectrum of the scalar fluctuations. Fortunately, when gravity is included, the unstable tachyonic excitations are not already present and the scalar perturbation spectrum is defined only for m 2 ≥ 0.…”

“…In more realistic models the thickness of the worldsheet is taken into account, in this case the brane is generated by a domain wall, a solution to Einstein gravity theory interacting with a scalar field where the scalar field is a standard kink interpolating between the minima of a potential with spontaneously broken symmetry [4][5][6][7][8][9][10][11][12]. This scenarios are topologically stables and, consequently, the analysis of small fluctuations of both the metric tensor and the scalar field [13], revels a tower of modes free of tachyonic instabilities.…”

Hybrid metric-Palatini brane system

“…In more realistic thick brane models the original singular brane is replaced by a smooth domain wall generated by matter fields. The thick brane models have been extensively studied in the context of higher-dimensional gravity theories [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. The linearization of a brane system is one of the most important issues in brane models [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56].…”

Study of the single neutral top pion production process atγγcollider

“…t c 0 t , e ÿ ! e ÿ 0 t [12,13]. In general, the cross sections of the above processes are at the level of 10 0 ÿ 10 1 fb, and it is promising to observe the top pions at future linear colliders with high luminosity.…”