Mass Insertion Research Articles

Next-to-leading order strong interaction corrections to the ΔF= 2 effective Hamiltonian in the MSSM

We compute the next-to-leading order strong interaction corrections to gluino-mediated Delta F=2 box diagrams in the Minimal Supersymmetric Standard Model. These corrections are given by two loop diagrams which we have calculated in three different regularization schemes in the mass insertion approximation. We obtain the next-to-leading order Wilson coefficients of the Delta F=2 effective Hamiltonian relevant for neutral meson mixings. We find that the matching scale uncertainty is largely reduced at the next-to-leading order, typically from about 10-15% to few percent.

Proposed design and mass production of wire arrays and targets for a Z-pinch IFE power plant

This paper summarizes the results of a detailed study reported in Ref. [1]. A concept for a 1000 MW(e) Z-Pinch IFE power plant has ten reactor chambers. A Load, consisting of a wire array surrounding a cryogenic dynamic hohlraum target with a 3-GJ yield, must be produced, inserted into a Replaceable Transmission Lines (RTL), transported to one of the chambers, and shot every second. The conceptual design of the load facilitates automatic mass manufacturing and insertion at 1 Hz at minimum cost. A sequence of operations necessary to (1) fabricate each wire array on a holding and insertion tool, (2) manufacture, evacuate, fill with DT, freeze, layer, and assemble each target with helium gas and liquid hydrogen, (3) insert a wire array and a target under vacuum into an RTL, and (4) remove their debris, is described. Detailed cost estimates derived for the complete load production and solid debris removal cycle in a commercial-scale facility are summarized.

MSSM anatomy of the polarization puzzle inB→ϕK*decays

We analyze the $B\ensuremath{\rightarrow}\ensuremath{\phi}{K}^{*}$ polarization puzzle in the minimal supersymmetric standard model (MSSM) including the neutral Higgs boson (NHB) contributions. To calculate the nonfactorizable contributions to the hadronic matrix elements of operators, we have used the QCD factorization framework to the ${\ensuremath{\alpha}}_{s}$ order. It is shown that the recent experimental results of the polarization fractions in $B\ensuremath{\rightarrow}\ensuremath{\phi}{K}^{*}$ decays, which are difficult to be explained in SM, could be explained in MSSM if there are flavor nondiagonal squark mass matrix elements of 2nd and 3rd generations, which also satisfy all relevant constraints from known experiments ($B\ensuremath{\rightarrow}{X}_{s}\ensuremath{\gamma},{B}_{s}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}},B\ensuremath{\rightarrow}{X}_{s}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}},B\ensuremath{\rightarrow}{X}_{s}g,\ensuremath{\Delta}{M}_{s}$, etc.). We have shown in detail that the experimental results can be accommodated with the flavor nondiagonal mass insertion of chirality RL, $\mathrm{RL}+\mathrm{LR}$, RR, or $\mathrm{LL}+\mathrm{RR}$ when the NHB contributions as well as $\mathcal{O}({\ensuremath{\alpha}}_{s})$ corrections of hadronic matrix elements of operators are included. However, the branching ratios for the decay are smaller than the experimental measurements.

Constraints on SUSY lepton flavour violation by rare processes

We study the constraints on flavour violating terms in low energy SUSY coming from several processes as li -> lj gamma, li -> lj lj lj and mu -> e in Nuclei. We show that a combined analysis of the processes allows us to extract additional information with respect to an individual analysis of all the processes. In particular, it makes possible to put bounds on sectors previously unconstrained by li -> lj gamma. We perform the analysis both in the mass eigenstate and in the mass insertion approximations clarifying the limit of applicability of these approximations.

Probing the flavour structure of supersymmetry breaking with rare B-processes — a beyond leading order analysis

In the framework of minimal supersymmetry with general flavour mixing in the squark sector we consider dominant beyond leading order (BLO) effects in the rare processes $\bar{B}\to X_s\gamma$, $\bar{B}_s\mu^+\mu^-$ and $\bar{B}_s-B_s$ mixing. We present analytic expressions for corrected vertices, which are applicable in general, and provide a recipe for the inclusion of the dominant and subdominant BLO effects in existing LO calculations. We also derive similar expressions in the mass insertion approximation. We investigate in more detail the focusing effect pointed out in our earlier work, which, at large $\tan\beta$ and $\mu>0$, leads to a reduced supersymmetric contribution to the above processes. We also find that, in some cases, flavour dependence, that accidentally cancels at leading order, can reappear at BLO. We further include electroweak corrections, which, while generally subdominant, in some cases may have a substantial effect. For example, their contribution to the charged Higgs vertex in $\bar{B}\to X_s\gamma$ can be of the order of 20% at BLO. They can also reduce the contribution of LL insertions to $\bar{B}_s\to\mu^+\mu^-$ and $\bar{B}_s-B_s$ mixing by up to 20%, even at the LO. We also analyse radiative generation of CKM elements and find the possibility that the CKM matrix elements $K_{ts}$ and $K_{cb}$ can be generated entirely by LR insertions. This work constitutes the first complete analysis of dominant BLO effects in the GFM scenario.

Analysis of $B^{0}_{d} \to \phi K^{{*0}} $ decay mode with supersymmetry

Motivated by the recent measurement of low longitudinal polarization fraction in the decay mode $\B \to \phi K^{*0}$, which appears not to be in agreement with the standard model expectation, we analyze this mode in the minimal supersymmetric standard model with mass insertion approximation. Within the standard model, with factorization approximation, the longitudinal polarization is expected to be $f_L \sim 1-{\cal O}(1/m_b^2)$. We find that this anomaly can be explained in the minimal supersymmetric standard model with either $LR$ or $RL$ mass insertion approximation.

Time-dependentCPasymmetry inB0→ρ0γdecay to probe the origin ofCPviolation

Since the $CP$ violation in the $B$ system has been investigated up to now only through processes related to the $B--\overline{B}$ mixing, urgently required is a new way of study for the $CP$ violation and establishing its origin in the $B$ system independent of the mixing process. In this work, we explore the exclusive ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{0}\ensuremath{\gamma}$ decay to obtain the time-dependent $CP$ asymmetry in the $b\ensuremath{\rightarrow}d$ decay process in the standard model and the supersymmetric model. We find that the complex $RL$ and $RR$ mass insertion to the squark sector in the minimal supersymmetric standard model can lead to a large $CP$ asymmetry in $B\ensuremath{\rightarrow}\ensuremath{\rho}\ensuremath{\gamma}$ decay through the gluino-squark diagrams, which is suppressed in the standard model and $B\ensuremath{\rightarrow}\ensuremath{\rho}\ensuremath{\gamma}$ may be a new window to study the new physics in the future.

Comparative study of CP asymmetries in supersymmetric models

We systematically analyze the supersymmetric contributions to the mixing CP asymmetries and branching ratios of B → ϕ K S and B → η ′ K S processes. We consider both gluino and chargino exchanges in a model independent way by using the mass insertion approximation method. While we adopt the QCD factorization approach for evaluating the corresponding hadronic matrix elements, a critical comparison with predictions in naive factorization one is also provided. We find that pure chargino contributions cannot accommodate the current experimental results on CP asymmetries, mainly due to b → s γ constraints. We show that charged Higgs contributions can relax these constraints making chargino responsible for large asymmetries. On the other hand, pure gluino exchanges can easily saturate both the constraints on B → ϕ K S and B → η ′ K S CP asymmetries. Moreover, we also find that the simultaneous contributions from gluino and chargino exchanges could easily account for the present experimental results on the mentioned asymmetries. Remarkably, large experimentally allowed enhancements of B → η ′ K S branching ratio can easily be achieved by the contribution of two mass insertions in gluino exchanges. Finally, we analyze the correlations between the CP asymmetries of these processes and the direct CP asymmetry in b → s γ decay. When all experimental constraints are satisfied, supersymmetry favors large and positive values of b → s γ asymmetry.

New Higgs effects in B-physics in supersymmetry with general flavour mixing

We investigate the effect of general flavour mixing among squarks on the rare decays B¯→Xsγ, B¯s→μ+μ− and B¯s–Bs mixing beyond the leading order in perturbation theory. We include all large tanβ-enhanced corrections whilst also taking into account the effects of general flavour mixing on the uncorrected quark mass matrix and SU(2)L×U(1)Y breaking. For B¯s→μ+μ− and B¯s–Bs mixing we find that, in analogy to B¯→Xsγ, there appears a focusing effect which can reduce the contribution due to the δRR (and the δLL) insertion by up to a factor of two at large tanβ and μ>0. A dependence on δLR and δRL, that otherwise cancels to first order in the mass insertion approximation, is also reintroduced. Taking into account the current experimental bounds on ΔMBs and BR(B¯s→μ+μ−), we find that the insertions δRL and δRR can be significantly constrained compared to bounds obtained from B¯→Xsγ only.

SUPERSYMMETRIC CONTRIBUTIONS TO THE CP ASYMMETRY OF THE B→ϕKS AND B→η'KS

We analyse the CP asymmetry of the B→ϕKS and B→η'KS processes in general supersymmetric models. We consider both gluino and chargino exchanges in a model-independent way by using the mass insertion approximation method. We adopt the QCD factorization method for evaluating the corresponding hadronic matrix elements. We show that chromomagnetic type of operator may play an important role in accounting for the deviation of the mixing CP asymmetry between B→ϕKS and B→J/ψKS processes observed by Belle and BaBar experiments. We also show that due to the different parity in the final states of these processes, their supersymmetric contributions from the R-sector have an opposite sign, which naturally explain the large deviation between their asymmetries.

Quark mass dependence of the pseudoscalar hairpin vertex

In a recent investigation of chiral behavior in quenched lattice QCD, the flavor-singlet pseudoscalar ``hairpin'' vertex associated with the ${\ensuremath{\eta}}^{\ensuremath{'}}$ mass was studied for pion masses ranging from $\ensuremath{\approx}275$ to 675 MeV. It has been observed by Sharpe that, with a consistent NLO calculation in quenched chiral perturbation theory, the quark-mass dependence of the hairpin vertex is uniquely predicted in terms of the single-pole coefficient ${\ensuremath{\alpha}}_{\ensuremath{\Phi}}$ and the Leutwyler parameter ${L}_{5}$. Since ${\ensuremath{\alpha}}_{\ensuremath{\Phi}}$ is found to be $\ensuremath{\approx}0$, the chiral slope of the double-pole residue determines a value for ${L}_{5}$, providing a consistency check between the chiral slope of the hairpin mass insertion and that of the pion decay constant. We investigate the consistency of these mass dependences in our Monte Carlo results at two values of lattice spacing. Within statistics, the slopes are found to be consistent with the $Q\ensuremath{\chi}PT$ prediction.

Can there be any new physics in b→d penguins

We analyze the possibility of observing new physics effects in the b→d penguin amplitudes. For this purpose, we consider the decay mode Bd0→K00, which has only b→d penguin contributions. Using the QCD factorization approach, we find very tiny CP violating effects in the standard model for this process. Furthermore, we show that the minimal supersymmetric standard model with LR mass insertion and R-parity violating supersymmetric model can provide substantial CP violation effects. Observation of sizable CP violation in this mode would be a clear signal of new physics.

Hadronic electric dipole moments induced by strangeness and constraints on supersymmetricCPphases

We consider hadronic CP violation induced by chromoelectric dipolemoments (CEDMs) of light quarks and the QCD theta parameter ($?overline{?theta}$). We concentrate on the strange quark CEDM especially in this paper. Using effective CP violating nucleon interactions induced by the CEDMs and $?overline{?theta}$ with the SU(3) chiral Lagrangian technique, we calculate the EDMs for the $^{199}$Hg atom, neutron and deuteron. We also discuss supersymmetric contributions to the electric dipole moments with the mass insertion approximations and give stringent constraints on the CP phases of the flavor changing SUSY breaking terms.

Pre-logarithmic and logarithmic fields in a sandpile model

We consider the unoriented two-dimensional Abelian sandpile model onthe half-plane with open and closed boundary conditions, and relateit to the boundary logarithmic conformal field theory with central chargec = −2. Building on previous results, we first perform a complementary latticeanalysis of the operator effecting the change of boundary conditionbetween open and closed, which confirms that this operator is a weight−1/8 boundary primary field, whose fusion agrees with lattice calculations. We then consider theoperators corresponding to the unit height variable and to a mass insertion at an isolatedsite of the upper half-plane and compute their one-point functions in the presenceof a boundary containing the two kinds of boundary conditions. We show thatthe scaling limit of the mass insertion operator is a weight 0 logarithmic field.

CP asymmetries in [formula omitted] and [formula omitted] in MSSM

We study the B → ϕ K S and B → η ′ K S decays in MSSM by calculating hadronic matrix elements of operators with QCD factorization approach and including neutral Higgs boson (NHB) contributions. We calculate the Wilson coefficients of operators including the new operators which are induced by NHB penguins at LO using the MIA with double insertions. We calculate the α s order hadronic matrix elements of the new operators for B → ϕ K S and B → η ′ K S . It is shown that the recent experimental results on the time-dependent CP asymmetries in B → ϕ K S and B → η ′ K S , S ϕ K S is negative and S η ′ K S is positive, which cannot be explained in SM, can be explained in MSSM if there are flavor non-diagonal squark mass matrix elements of 2nd and 3rd generations whose size satisfies all relevant constraints from known experiments ( B → X s γ , B s → μ + μ − , B → X s μ + μ − , B → X s g , Δ M s , etc.). In particular, we find that one can explain the experimental results with a flavor non-diagonal mass insertion of chirality LL or LR when α s corrections of hadronic matrix elements of operators are included, in contrast with the claim in the literature. At the same time, the branching ratios for the two decays can also be in agreement with experimental measurements.

B→φKSand supersymmetry

The rare decay B --> Phi K_S is a well-known probe of physics beyond the Standard Model because it arises only through loop effects yet has the same time-dependent CP asymmetry as B --> Psi K_S. Motivated by recent data suggesting new physics in B --> Phi K_S, we look to supersymmetry for possible explanations, including contributions mediated by gluino loops and by Higgs bosons. Chirality-preserving LL and RR gluino contributions are generically small, unless gluinos and squarks masses are close to the current lower bounds. Higgs contributions are also too small to explain a large asymmetry if we impose the current upper limit on B(B_s --> mu mu). On the other hand, chirality-flipping LR and RL gluino contributions can provide sizable effects and while remaining consistent with related results in B --> Psi K_S, Delta M_s, B --> X_s gamma and other processes. We discuss how the LR and RL insertions can be distinguished using other observables, and we provide a string-based model and other estimates to show that the needed sizes of mass insertions are reasonable.

Top flavour violating decays in general supersymmetric models

We analyse the top flavour violating decays in general supersymmetric model using the mass insertion approximation. In particular, we discuss the impact of a light right-handed top-squark and large mixing between the first or second and third generation of up-squarks on processes as t→qγ,g. We also take into account the relevant experimental constraints from B-physics and the requirements for a successfull electroweak baryogenesis on squark mixings. We show that for general large mixings in squarks mass matrix, the branching ratio of the t→qγ,g(q=u,c) can be as large as 10−6.

Bs0−Bs0mixing and theBs→J/ψφasymmetry in supersymmetric models

We analyze supersymmetric contributions to ${B}_{s}$ mixing and their impact on mixing-induced CP asymmetries, using the mass insertion approximation. We discuss in particular the correlation of supersymmetry (SUSY) effects in the CP asymmetries of ${B}_{s}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\varphi}$ and ${B}_{d}\ensuremath{\rightarrow}\ensuremath{\varphi}{K}_{S}$ and find that the mass insertions dominant in ${B}_{s}$ mixing and ${B}_{d}\ensuremath{\rightarrow}\ensuremath{\varphi}{K}_{S}$ are $({\ensuremath{\delta}}_{23}^{d}{)}_{LL,RR}$ and $({\ensuremath{\delta}}_{23}^{d}{)}_{LR,RL},$ respectively. We show that models with dominant $({\ensuremath{\delta}}_{23}^{d}{)}_{LR,RL}$ can accommodate a negative value of ${S}_{\ensuremath{\varphi}{K}_{S}},$ in agreement with the Belle measurement of that observable, but yield a ${B}_{s}$ mixing phase too small to be observed. On the other hand, models with dominant $({\ensuremath{\delta}}_{23}^{d}{)}_{LL,RR}$ predict sizable SUSY contributions to both $\ensuremath{\Delta}{M}_{s}$ and the mixing phase, but do not allow the asymmetry in ${B}_{d}\ensuremath{\rightarrow}\ensuremath{\varphi}{K}_{S}$ to become negative, except for small values of the average down squark mass, which, in turn, entail a value of $\ensuremath{\Delta}{M}_{s}$ too large to be observed at the Fermilab Tevatron and CERN LHC. We conclude that the observation of ${B}_{s}$ mixing at hadron machines, together with the confirmation of a negative value of ${S}_{\ensuremath{\varphi}{K}_{S}},$ disfavors models with a single dominant mass insertion.

Probing new physics in B→φπ decay

We analyze the rare decay mode B→φπ, which is a pure penguin induced process, receiving dominant contribution from the electroweak penguins. Thus the Standard Model branching ratio is expected to be very small, which makes it as a sensitive probe of new physics. Using QCD factorization approach, we find the branching ratio in the Standard Model as Br(B−→φπ−)≃5×10−9. Exploring some of the beyond Standard Model scenarios the branching ratio is found to be ∼O(10−8) in the minimal supersymmetric Standard Model (MSSM) with mass insertion approximation and in the extended technicolor model (TC2). The existence of an extra vector-like down quark (VLDQ) model predicts it to be ∼O(10−7). The recent BaBar result on B0→φπ0 might be a strong indication of new physics effect present in the penguin induced process B→φπ.

Grand unification of quark and lepton flavor changing neutral currents.

In the context of supersymmetric grand unified theories with soft breaking terms arising at the Planck scale, it is generally possible to link flavor changing neutral current and CP violating processes occurring in the leptonic and hadronic sectors. We study the correlation between flavor changing squark and slepton mass insertions in models à la SU(5). We show that the constraints coming from lepton flavor violation exhibit a strong impact on CP-violating B decays.