Supersymmetric contributions to B_s → K~-π~＋ decay

Recently,the CDF Collaboration has measured the branching fraction and time-integrated direct CP asymmetry of Bs → K-π＋ decay.The branching ratio is lower than the previous predictions based on QCD factorization.The experimental results favor a large CP asymmetry in Bs → K-π＋ decay while the standard model prediction is very small.We compute the supersymmetry contributions to Bs → K-π＋ decay using the mass insertion method,and find that the LR and RL mass insertions could suppress this branching ratio and increase this direct CP asymmetry well in line with the experimental data.     

Exclusive Semi-leptonic Decays b → s(d)ν in the Standard Model with Fourth Generation

We consider the effects of the fourth generation quarks on the rare B decay processes described by the b → s(d)ννˉ processes at the quark level.We find that the values of the branching ratios for some of these rare decay processes are much larger than the standard model(SM) predictions.These processes can be used to constrain the relevant free parameters.     

Search for new physics in the B→K~((*))l~+l~- decays at BABAR

Based on a data sample of 384 million BB pairs collected with the BABAR detector at the PEP-Ⅱ asymmetric e + e ￣ storage ring,we measure branching fractions,direct CP,isospin and lepton-flavor asymmetries for the rare decays B → K (*) l + l￣ in two di-lepton mass bins above and below the J/ψ resonance.For the B → K* l + l￣ decay,we also measure the K* longitudinal polarization fraction and the di-lepton forwardbackward asymmetry.     

Exclusive Semileptonic Rare Decays B → K^（＊）e＋e- in a Top Quark Two-Higgs-Doublet Model

Employing improved calculations of the decay form factors from light-cone sum rules, we evaluate the invariant mass spectrum, forward-backward asymmetry, and lepton polarizations of the exclusive processes B → K^（＊）e＋e- in the SM and T2HDM. From the recent measurements of their branching ratios, we find that these processes do provide additional bounds on the new parameters in the model considered here. After the inclusion of the new physics contributions, the large enhancement of FBA, which is unobservably small within the SM and of the lepton polarization at large tan β, may precisely test the SM or reveal new physics in forthcoming accurate experiments.     

Study of the s → dv■ rare hyperon decays in the Standard Model and new physics

FCNC processes offer important tools to test the Standard Model(SM)and to search for possible new physics.In this work,we investigate the s→dvv rare hyperon decays in SM and beyond.We find that in SM the branching ratios for these rare hyperon decays range from 10~(-14) to 10~(-11).When all the errors in the form factors are included,we find that the final branching ratios for most decay modes have an uncertainty of about 5% to 10%.After taking into account the contribution from new physics,the generalized SUSY extension of SM and the minimal 331 model,the decay widths for these channels can be enhanced by a factor of 2～7.     

Search for new physics in the B→K^（＊）l^＋l^- decays at BABAR

Based on a data sample of 384 million BB pairs collected with the BABAR detector at the PEP-Ⅱ asymmetric e ＋ e ￣ storage ring,we measure branching fractions,direct CP,isospin and lepton-flavor asymmetries for the rare decays B → K （＊） l ＋ l￣ in two di-lepton mass bins above and below the J/ψ resonance.For the B → K＊ l ＋ l￣ decay,we also measure the K＊ longitudinal polarization fraction and the di-lepton forwardbackward asymmetry.     

CP violation in B→φKs decay in R-parity violating supersymmetry

In the framework of R-parity violating supersymmetry, we investigate the time dependent CP asymmetry SφKs anomaly of B→φKs decay. When the values of the weak phase φ in the R-parity violating coupling fall into certain parameter spaces （246°〈 φ 〈 263°） we find that this anomaly can be easily explained; at the same time, the branching ratio of B→φKs decay can also be in agreement with experimental measurements.     

CP violation in B→φKs decay in R-parity violating supersymmetry

In the framework of R-parity violating supersymmetry, we investigate the time dependent CP asymmetry SφKs anomaly of B→φKs decay. When the values of the weak phase φ in the R-parity violating coupling fall into certain parameter spaces (246°<φ<263°) we find that this anomaly can be easily ex-plained; at the same time, the branching ratio of B →φKs decay can also be in agreement with experimental measurements.     

Top rare decays t→cV in mirror twin Higgs models

The decay t→cV(V=γ,Z,g)processes in mirror twin Higgs models with colorless top partners are studied in this paper.We report that the branchi ng ratios of these decays can strongly affect the standard model expectations in some parameter spaces and may be detectable according to the current precision electroweak measurements.Thus,constraints on the model parameters may be obtained from the branching fraction of the decay processes,which may serve as a robust detection tool for this new physics model.     

Effect of Asymmetry of Dichotomous Noise on Transport of Particles

In this paper, an additive dichotomous noise model and a multiplicative dichotomous noise model are investigated for the effect of the asymmetry of the additive and multiplicative dichotomous noises on the transport of the particles, in the presence of spatial symmetry and asymmetry, respectively. It is shown that, in the presence of spatial asymmetry, the asymmetry of the dichotomous noise can weaken or enhance the transport of the particles; while in the absence of spatial asymmetry, the nonzero current induced by the noise＇s asymmetry is ＂symmetric＂ around the zero current. In addition, a current reversal can be produced by controlling the noise＇s asymmetry parameter; and we find that, for some values of the noise＇s asymmetry parameter, the multiplicative dichotomous noise can more easily induce the transport of the particles than the additive dichotomous noise.     

Direct CP violation in B(s)→J/ψP(V)

In the framework of factorization, we study direct CP violation in the decays of B_(s)→J/ψP(V) (P(V) refer to the pseudoscalar (vector) meson). The CP violation depends strongly on Cabibbo-Kobayashi- Maskawa (CKM) matrix elements and the effective parameter, N_c. The recent experimental data for the branching ratios of B_(s)→J/ψP(V) are accurate enough and we can give a strong constraint on the range of N_c. We nd that the CP violating asymmetry is consistent with the available experiment values for the b→d transition, and a little smaller than the b→s transition. We also predict the CP violation of other decay channels for B_(s)→J/ψP(V). We expect our results can give valuable guidance for experiments.     

The study of B→K*l+l- decays in family non-universal Z′ models

In a combined investigation of B → K ( * ) l + l - decays, constraints on the related couplings in family non-universal Z′ models are derived. We find that within the allowed parameter space, the recently observed forward-backward asymmetry in the B → K * l + l - decay can be explained by flipping the signs of the Wilson coefficients C eff 9 and C 10 . With the obtained constraints, we also calculate the branching ratio of the B s →μ + μ - decay. The upper bound of our prediction is nearly an order of magnitude smaller than the upper bound given by the CDF Collaboration recently.     

Higgsino asymmetry and direct-detection constraints of light dark matter in the NMSSM with non-universal Higgs masses

In this study,we analyze the direct-detection constraints of light dark matter in the next-to minimal supersymmetric standard model(NMSSM)with non-universal Higgs masses(NUHM);we specially focus on the correlation between higgsino asymmetry and spin-dependent(SD)cross section.We draw the following conclusions.(i)The SD cross section is proportional to the square of higgsino asymmetry in dark matter X₁⁰in the NMSSM-NUHM,and hence,it is small for highly singlino-dominated dark matter,(ii)The higgsino-mass parameter μeff is smaller than approximately 335 GeV in the NMSSM-NUHM due to the current muon g-2 constraint,but our scenario with light dark matter can still be alive under current constraints including the direct detection of dark matter in the spindependent channel.(iii)With a sizeable higgsino component in the light dark matter,the higgsino asymmetry and SD cross section can also be sizeable,but dark matter relic density is always small;thus,it can escape the direct detections.(iv)Light dark matter in the h₂-and Z-funnel annihilation channels with sufficient relic density can be covered by future LUX-ZEPLIN(LZ)7-ton in SD detections.(v)The spin-independent(SI)cross section is dominated by h₁-and h₂-exchanging channels,which can even cancel each other in some samples,leaving an SI cross section smaller by a few orders of magnitude than that of one individual channel.     

Rare Decay B_c → D_s *μ~+ μ~- in a Family Non-Universal Z′ Model

Using the form factors calculated in the three-point QCD sum rules, we calculate the new physics contributions to the physical observables of B c → Ds* μ+ μ decay in a family non-universal Z′ model. Under the consideration of three cases of the new physics parameters, we find that: (a) the Z′ boson can provide large contributions to the differential decay rates; (b) the forward-backward asymmetry (FBA) can be increased by about 47%, 38%, and 110% at most in S1, S2, and extreme limit values (ELV), respectively. In addition, the zero crossing can be shifted in all the cases; (c) when s 0.08, the value of P L can be changed from 1 in the Standard Model (SM) to 0.5 in S1, 0.6 in S2, and 0 in extreme limit values, respectively; (d) the new physics corrections to P T will decrease the SM prediction about 25% for the cases of S1     

New physical effects on the decay Bs→γγ in the technicolor model

In this paper we calculate the contributions to the branching ratio of Bs→γγ from charged pseudo-Goldstone bosons appearing in the one generation Technicolor model. We find that the theoretical value of the branching ratio, BR(Bs→γγ), including the contributions of PGBs, P± and P±8, is very different from the standard model (SM) prediction. The new physical effects can provide a one to two order of magnitude enhancement of the SM results. It is shown that the decay Bs→γγ can test new physical signals from the technicolor model.     

Recent results from NA48/2

Recent results on radiative K^± decays from the NA48/2 experiment are reported. From the full NA48/2 data set, about a million K^±→π^±π^γ decays were reconstructed. Based on this sample, the first measurement of the interference between direct photon emission and inner bremsstrahlung in K^±→π^±π^γ decays was performed. Stringent limits on CP violation in this decay were also set. In addition, a precise measurement of the branching fraction of K^±→π^±γγ is presented. This measurement was based on a data sample of more than 1000 event candidates. Also the related decay K^±→π^±e^＋e^-γ has first been observed. Results of the measurement of the decay rate and the decay parameter 5 are summarized.     

Investigation of rare semileptonic B_c→(D_(s,d)~((*))μ~+μ~- decays with non-universal Z' effect

We analyze different decay observables of semileptonic decays B_c→(D_(s,d)~((*)))μ~+μ~-,such as the branching ratio,forward-backward asymmetry,polarization fraction,and lepton polarization asymmetry in the non-universal Z'model.We further study the dependence of the branching fraction to the new model parameters and find that the values of different decay parameters increase in the Z' model,which indicates a possible approach for the search of new physics as well as for the unknown phenomena of the charm B meson.     

Recent results from NA48/2

Recent results on radiative K± decays from the NA48/2 experiment are reported.From the full NA48/2 data set,about a million K±→π±π0γ decays were reconstructed.Based on this sample,the first measurement of the interference between direct photon emission and inner bremsstrahlung in K±→π±π0γ decays was performed.Stringent limits on CP violation in this decay were also set.In addition,a precise measurement of the branching fraction of K±→π±γγ is presented.This measurement was based on a data sample of more than 1000 event candidates.Also the related decay K±→π±e+e-γ has first been observed.Results of the measurement of the decay rate and the decay parameter c are summarized.     

Next-to-leading order QCD corrections to the decay of Higgs to vector meson and Z boson

The exclusive decay of the Higgs boson to a vector meson(J/ψ or Υ(1 S)) and Z boson is studied in this work. The decay amplitudes are separated into two parts in a gauge invariant manner. The first part comes from the direct coupling of the Higgs boson to the charm(bottom) quark and the other from the HZZ*or the loop-induced HZγ*vertexes in the standard model. While the branching ratios from the direct channel are much smaller than those of the indirect channel, their interference terms give nontrivial contributions. We further calculate the QCD radiative corrections to both channels, which reduce the total branching ratios by around 20% for both J/ψ and Υ(1S) production. Our results provide a possible chance to check the SM predictions of the Hcc(Hbb)coupling and to seek for hints of new physics at the High Luminosity LHC or future hadron colliders.     

Rare Decay Process K→πvv^- in Three-Site Higgsless Model]

Rare decay processes K→πvv^- and KL→π^0vv^- are considered in the framework of three-site Higgsless model. The contributions of this new physics model to these two decay processes come from the new heavy gauge bosons and the correction terms for the couplings of the ordinary gauge bosons with fermions. Our numerical results show that the branching ratios of these two decay processes can be enhanced by 40% and 50% relative to those predicted by the standard model.