We investigate fermionic dark matter interactions with standard model particles from an additional U(1)X gauge symmetry,assuming kinetic mixing between the U(1)X and U(1)Y gauge fields as well as a nonzero U(1)X charg...We investigate fermionic dark matter interactions with standard model particles from an additional U(1)X gauge symmetry,assuming kinetic mixing between the U(1)X and U(1)Y gauge fields as well as a nonzero U(1)X charge of the Higgs doublet.To ensure gauge-invariant Yukawa interactions and the cancellation of gauge anomalies,standard model fermions are assigned Y-sequential U(1)X charges proportional to the Higgs charge.Although the Higgs charge should be small owing to collider constraints,it is useful to decrease the effective cross section of dark matter scattering off nucleons by two orders of magnitude to easily evade direct detection bounds.After performing numerical scans in the parameter space,we find that the introduction of the Higgs charge can also enhance the dark matter relic density by at least two orders of magnitude.In the case where the resonance effect is important for dark matter freeze-out,when the observed relic density and direct detection constraints are tangled,the Higgs charge can expand physical windows to some extent by relieving the tension between the relic density and direct detection.展开更多
We constructed a gauge B-L model with D_(4)×Z_(4)×Z_(2)symmetry to explain the quark and lepton mass hierarchies and their mixings with realistic CP phases via the type-I seesaw mechanism.Six quark mases,thr...We constructed a gauge B-L model with D_(4)×Z_(4)×Z_(2)symmetry to explain the quark and lepton mass hierarchies and their mixings with realistic CP phases via the type-I seesaw mechanism.Six quark mases,three quark mixing angles,and the CP phase in the quark sector take the central values whereas Yukawa couplings in the quark sector are diluted in a range of difference of three orders of magnitude by the perturbation theory at the first order.Concerning the neutrino sector,a small neutrino mass is achieved by the type-I seesaw mechanism.Both inverted and normal neutrino mass hierarchies are consistent with the experimental data.The predicted sum of neutrino masses for normal and inverted hierarchies,the effective neutrino masses,and the Dirac CP phase are also consistent with recently reported limits.展开更多
Using the efective Hamiltonian method, we analyze the B0-ˉB0mixing in the extension of the standard model(SM) where baryon number and lepton number are local gauge symmetries. The numerical results indicate the corre...Using the efective Hamiltonian method, we analyze the B0-ˉB0mixing in the extension of the standard model(SM) where baryon number and lepton number are local gauge symmetries. The numerical results indicate the correction from the extra particles to the mass diference mB is significant. There is a 60% enhancement compared to the SM prediction for mB at most, which agrees with the current experimental result.展开更多
基金Supported by the National Natural Science Foundation of China(12135014)。
文摘We investigate fermionic dark matter interactions with standard model particles from an additional U(1)X gauge symmetry,assuming kinetic mixing between the U(1)X and U(1)Y gauge fields as well as a nonzero U(1)X charge of the Higgs doublet.To ensure gauge-invariant Yukawa interactions and the cancellation of gauge anomalies,standard model fermions are assigned Y-sequential U(1)X charges proportional to the Higgs charge.Although the Higgs charge should be small owing to collider constraints,it is useful to decrease the effective cross section of dark matter scattering off nucleons by two orders of magnitude to easily evade direct detection bounds.After performing numerical scans in the parameter space,we find that the introduction of the Higgs charge can also enhance the dark matter relic density by at least two orders of magnitude.In the case where the resonance effect is important for dark matter freeze-out,when the observed relic density and direct detection constraints are tangled,the Higgs charge can expand physical windows to some extent by relieving the tension between the relic density and direct detection.
基金funded by Tay Nguyen University under grant number T2023-45CBTD。
文摘We constructed a gauge B-L model with D_(4)×Z_(4)×Z_(2)symmetry to explain the quark and lepton mass hierarchies and their mixings with realistic CP phases via the type-I seesaw mechanism.Six quark mases,three quark mixing angles,and the CP phase in the quark sector take the central values whereas Yukawa couplings in the quark sector are diluted in a range of difference of three orders of magnitude by the perturbation theory at the first order.Concerning the neutrino sector,a small neutrino mass is achieved by the type-I seesaw mechanism.Both inverted and normal neutrino mass hierarchies are consistent with the experimental data.The predicted sum of neutrino masses for normal and inverted hierarchies,the effective neutrino masses,and the Dirac CP phase are also consistent with recently reported limits.
基金Supported by the National Natural Science Foundation of China(NNSFC)under Grant Nos.10975027,11275036,and 11047002
文摘Using the efective Hamiltonian method, we analyze the B0-ˉB0mixing in the extension of the standard model(SM) where baryon number and lepton number are local gauge symmetries. The numerical results indicate the correction from the extra particles to the mass diference mB is significant. There is a 60% enhancement compared to the SM prediction for mB at most, which agrees with the current experimental result.
