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Register a new userRare decays $B to X_{s,d} u bar u$ and $B_{s,d} to l^+ l^-$ in the Topcolor-assisted Technicolor Model
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We calculate the contributions to the rare decays $B to X_{s,d} u bar u$ and $B_{s,d} to l^+l^-$ from one-loop $Z^0$-penguin diagrams in the framework of Topcolor-assisted Technicolor Model. Within the parameter space, we find that: (a) the new contribution from technipions is less than 2% of the standard model prediction; (b) the top-pions can provide a factor of 10 to 30 enhancement to the ratios in question; (c) the topcolor-assisted technicolor model is consistent with the current experimental data.
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We calculate the contributions to the rare B-decays, $B to X_{s,d} u bar u$, $B_{s,d} to l^+l^- $ from the unit-charged technipions. Within the considered parameter space we find that: (a) the enhancements to the branching ratios in question can be as large as three orders of magnitude; (b) the ALEPH data of $B to X_s u bar u$ lead to strong mass bounds on $m_{p1}$ and $m_{p8}$: $m_{p8} geq 620, 475 GeV$ for $F_Q=40GeV$ and $m_{p1}=100, 400 GeV$ respectively. (c) the CDF data of $B_s to mu bar mu$ lead to a relatively weak limit: $m_{p8} geq 320 GeV$ for $F_Q=40GeV$ and $m_{p1}=200 GeV$.
We calculate tree-level contributions to the inclusive rare $bar B to X_{s(d)} , ell^+ell^-$ decays. At the partonic level they stem from the five-particle process $b to s(d) , q bar q , ell^+ell^-$, with $q in {u,d,s}$. While for $b to d$ transitions such five-body final states contribute at the same order in the Wolfenstein expansion compared to the three-body partonic decay, they are CKM suppressed in $b to s$ decays. In the perturbative expansion, we include all leading-order contributions, as well as partial next-to-leading order QCD and QED effects. In the case of the differential branching ratio, we present all results completely analytically in terms of polylogarithmic functions of at most weight three. We also consider the differential forward-backward asymmetry, where all except one interference could be obtained analytically. From a phenomenological point of view the newly calculated contributions are at the percent level or below.
In this work, we analyze the semi-leptonic decays $bar B^0/D^0 to (a_0(980)^{pm}topi^{pm}eta) l^{mp} u$ within light-cone sum rules. The two and three-body light-cone distribution amplitudes (LCDAs) of the $B$ meson and the only available two-body LCDA of the $D$ meson are used. To include the finite-width effect of the $a_0(980)$, we use a scalar form factor to describe the final-state interaction between the $pieta$ mesons, which was previously calculated within unitarized Chiral Perturbation Theory. The result for the decay branching fraction of the $D^0$ decay is in good agreement with that measured by the BESIII Collaboration, while the branching fraction of the $bar B^0$ decay can be tested in future experiments.
In this work, we perform a systematical investigation about the possible hidden and doubly heavy molecular states with open and hidden strangeness from interactions of $D^{(*)}{bar{D}}^{(*)}_{s}$/$B^{(*)}{bar{B}}^{(*)}_{s}$, ${D}^{(*)}_{s}{bar{D}}^{(*)}_{s}$/${{B}}^{(*)}_{s}{bar{B}}^{(*)}_{s}$, ${D}^{(*)}D_{s}^{(*)}$/${B}^{(*)}B_{s}^{(*)}$, and $D_{s}^{(*)}D_{s}^{(*)}$/$B_{s}^{(*)}B_{s}^{(*)}$ in a quasipotential Bethe-Salpeter equation approach. The interactions of the systems considered are described within the one-boson-exchange model, which includes exchanges of light mesons and $J/psi/Upsilon$ meson. Possible molecular states are searched for as poles of scattering amplitudes of the interactions considered. The results suggest that recently observed $Z_{cs}(3985)$ can be assigned as a molecular state of $D^*bar{D}_s+Dbar{D}^*_s$, which is a partner of $Z_c(3900)$ state as a $Dbar{D}^*$ molecular state. The calculation also favors the existence of hidden heavy states $D_sbar{D}_s/B_sbar{B}_s$ with spin parity $J^P=0^+$, $D_sbar{D}^*_s/B_sbar{B}^*_s$ with $1^{+}$, and $D^*_sbar{D}^*_s/B^*_sbar{B}^*_s$ with $0^+$, $1^+$, and $2^+$. In the doubly heavy sector, the bound states can be found from the interactions $(D^*D_s+DD^*_s)/(B^*B_s+BB^*_s)$ with $1^+$, $D_sbar{D}_s^*/B_sbar{B}_s^*$ with $1^+$, $D^*D^*_s/B^*B^*_s$ with $1^+$ and $2^+$, and $D^*_sD^*_s/B^*_sB^*_s$ with $1^+$ and $2^+$. Some other interactions are also found attractive, but may be not strong enough to produce a bound state. The results in this work are helpful for understanding the $Z_{cs}(3985)$, and future experimental search for the new molecular states.
We study R-parity violating contributions to the mixing parameter $y$ for $D^0 -bar D^0$ and $B^0_{d,s} - bar B^0_{d,s}$ systems. We first obtain general expressions for new physics contributions to $y$ from effective four fermion operators. We then use them to study R-parity contributions. We find that R-parity violating contributions to $D^0 - bar D^0$ mixing, and $B_{d}^0 - bar B_{d}^0$ to be small. There may be sizable contribution to $B_s^0 -bar B_s^0$ mixing. We also obtain some interesting bounds on R-parity violating parameters using known Standard Model predictions and experimental data.
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