Top-quark flavor-changing tqZ couplings and rare $$\Delta F=1$$ ΔF=1 processes
Abstract We study the impacts of anomalous tqZ couplings ($$q=u,c$$ q=u,c ), which lead to the $$t\rightarrow q Z$$ t→qZ decays, on low energy flavor physics. It is found that the tuZ-coupling effect can significantly affect the rare K and B decays, whereas the tcZ-coupling effect is small. Using th...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2019-08-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | http://link.springer.com/article/10.1140/epjc/s10052-019-7133-5 |
| _version_ | 1818281868943949824 |
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| author | Chuan-Hung Chen Takaaki Nomura |
| author_facet | Chuan-Hung Chen Takaaki Nomura |
| author_sort | Chuan-Hung Chen |
| collection | DOAJ |
| description | Abstract We study the impacts of anomalous tqZ couplings ($$q=u,c$$ q=u,c ), which lead to the $$t\rightarrow q Z$$ t→qZ decays, on low energy flavor physics. It is found that the tuZ-coupling effect can significantly affect the rare K and B decays, whereas the tcZ-coupling effect is small. Using the ATLAS’s branching ratio (BR) upper bound of $$BR(t\rightarrow uZ) < 1.7\times 10^{-4}$$ BR(t→uZ)<1.7×10-4 , the influence of the anomalous tuZ-coupling on the rare decays can be found as follows: (a) The contribution to the Kaon direct CP violation can be up to $$Re(\epsilon '/\epsilon ) \lesssim 0.8 \times 10^{-3}$$ Re(ϵ′/ϵ)≲0.8×10-3 ; (b) $$BR(K^+\rightarrow \pi ^+ \nu {\bar{\nu }}) \lesssim 12 \times 10^{-11}$$ BR(K+→π+νν¯)≲12×10-11 and $$BR(K_L \rightarrow \pi ^0 \nu {\bar{\nu }})\lesssim 7.9 \times 10^{-11}$$ BR(KL→π0νν¯)≲7.9×10-11 ; (c) the BR for $$K_S \rightarrow \mu ^+ \mu ^-$$ KS→μ+μ- including the long-distance effect can be enhanced by $$11\%$$ 11% with respect to the standard model result, and (d) $$BR(B_d \rightarrow \mu ^+ \mu ^-) \lesssim 1.97 \times 10^{-10}$$ BR(Bd→μ+μ-)≲1.97×10-10 . In addition, although $$Re(\epsilon '/\epsilon )$$ Re(ϵ′/ϵ) cannot be synchronously enhanced with $$BR(K_L\rightarrow \pi ^0 \nu {\bar{\nu }})$$ BR(KL→π0νν¯) and $$BR(K_S\rightarrow \mu ^+ \mu ^-)$$ BR(KS→μ+μ-) in the same region of the CP-violating phase, the values of $$Re(\epsilon '/\epsilon )$$ Re(ϵ′/ϵ) , $$BR(K^+ \rightarrow \pi ^+ \nu {\bar{\nu }})$$ BR(K+→π+νν¯) , and $$BR(B_d \rightarrow \mu ^+ \mu ^-)$$ BR(Bd→μ+μ-) can be simultaneously increased. |
| first_indexed | 2024-12-13T00:11:58Z |
| format | Article |
| id | doaj.art-41559531b9c34a92ab3e8051927366db |
| institution | Directory Open Access Journal |
| issn | 1434-6044 1434-6052 |
| language | English |
| last_indexed | 2024-12-13T00:11:58Z |
| publishDate | 2019-08-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | European Physical Journal C: Particles and Fields |
| spelling | doaj.art-41559531b9c34a92ab3e8051927366db2022-12-22T00:05:56ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60441434-60522019-08-017981910.1140/epjc/s10052-019-7133-5Top-quark flavor-changing tqZ couplings and rare $$\Delta F=1$$ ΔF=1 processesChuan-Hung Chen0Takaaki Nomura1Department of Physics, National Cheng-Kung UniversitySchool of Physics, KIASAbstract We study the impacts of anomalous tqZ couplings ($$q=u,c$$ q=u,c ), which lead to the $$t\rightarrow q Z$$ t→qZ decays, on low energy flavor physics. It is found that the tuZ-coupling effect can significantly affect the rare K and B decays, whereas the tcZ-coupling effect is small. Using the ATLAS’s branching ratio (BR) upper bound of $$BR(t\rightarrow uZ) < 1.7\times 10^{-4}$$ BR(t→uZ)<1.7×10-4 , the influence of the anomalous tuZ-coupling on the rare decays can be found as follows: (a) The contribution to the Kaon direct CP violation can be up to $$Re(\epsilon '/\epsilon ) \lesssim 0.8 \times 10^{-3}$$ Re(ϵ′/ϵ)≲0.8×10-3 ; (b) $$BR(K^+\rightarrow \pi ^+ \nu {\bar{\nu }}) \lesssim 12 \times 10^{-11}$$ BR(K+→π+νν¯)≲12×10-11 and $$BR(K_L \rightarrow \pi ^0 \nu {\bar{\nu }})\lesssim 7.9 \times 10^{-11}$$ BR(KL→π0νν¯)≲7.9×10-11 ; (c) the BR for $$K_S \rightarrow \mu ^+ \mu ^-$$ KS→μ+μ- including the long-distance effect can be enhanced by $$11\%$$ 11% with respect to the standard model result, and (d) $$BR(B_d \rightarrow \mu ^+ \mu ^-) \lesssim 1.97 \times 10^{-10}$$ BR(Bd→μ+μ-)≲1.97×10-10 . In addition, although $$Re(\epsilon '/\epsilon )$$ Re(ϵ′/ϵ) cannot be synchronously enhanced with $$BR(K_L\rightarrow \pi ^0 \nu {\bar{\nu }})$$ BR(KL→π0νν¯) and $$BR(K_S\rightarrow \mu ^+ \mu ^-)$$ BR(KS→μ+μ-) in the same region of the CP-violating phase, the values of $$Re(\epsilon '/\epsilon )$$ Re(ϵ′/ϵ) , $$BR(K^+ \rightarrow \pi ^+ \nu {\bar{\nu }})$$ BR(K+→π+νν¯) , and $$BR(B_d \rightarrow \mu ^+ \mu ^-)$$ BR(Bd→μ+μ-) can be simultaneously increased.http://link.springer.com/article/10.1140/epjc/s10052-019-7133-5 |
| spellingShingle | Chuan-Hung Chen Takaaki Nomura Top-quark flavor-changing tqZ couplings and rare $$\Delta F=1$$ ΔF=1 processes European Physical Journal C: Particles and Fields |
| title | Top-quark flavor-changing tqZ couplings and rare $$\Delta F=1$$ ΔF=1 processes |
| title_full | Top-quark flavor-changing tqZ couplings and rare $$\Delta F=1$$ ΔF=1 processes |
| title_fullStr | Top-quark flavor-changing tqZ couplings and rare $$\Delta F=1$$ ΔF=1 processes |
| title_full_unstemmed | Top-quark flavor-changing tqZ couplings and rare $$\Delta F=1$$ ΔF=1 processes |
| title_short | Top-quark flavor-changing tqZ couplings and rare $$\Delta F=1$$ ΔF=1 processes |
| title_sort | top quark flavor changing tqz couplings and rare delta f 1 δf 1 processes |
| url | http://link.springer.com/article/10.1140/epjc/s10052-019-7133-5 |
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