Search

The constructions of the new high-intensity muon beamlines are progressing in facilities around the world, and new physics searches related to the muons are expected. The facilities can observe the transverse positron polarization of the polarized $\mu^+$ decay to test the standard model. The transition of muonium into antimuonium (Mu-to-$\bar{\text{Mu}}$ transition), which is one of the interesting possibilities in the models beyond the standard model, can be also tested. The near-future observation of the transition gives us a great impact since it indicates that there is an approximate discrete symmetry in the lepton sector. If the Mu-to-$\bar{\text{Mu}}$ transition operator is generated, a new muon decay operator can exist and it may interfere with the standard model muon decay operator to induce the corrections to the transverse positron polarization in the $\mu^+$ decay. In this paper, we examine the possibility that the Mu-to-$\bar{\text{Mu}}$ transition and the correction to the transverse positron polarization are related, and we show that those two are related in the model of a neutral flavor gauge boson. We also investigate the models to generate the Mu-to-$\bar{\text{Mu}}$ transition, such as an inert $SU(2)_L$ doublet, a $SU(2)_L$ triplet for the type-II seesaw model, a dilepton gauge boson, and a left-right model. The non-zero value of the transverse polarization for one of the two directions, $P_{\rm T_2}$, violates the time-reversal invariance, and the experimental constraint of the electron electric dipole moment can provide a severe constraint on $P_{\rm T_2}$ depending on the model., Comment: 28 pages, 2 figures

The constructions of the new high-intensity muon beamlines are progressing in facilities around the world, and new physics searches related to the muons are expected. The facilities can observe the transverse positron polarization of the polarized $μ^+$ decay to test the standard model. The transition of muonium into antimuonium (Mu-to-$\bar{\text{Mu}}$ transition), which is one of the interesting possibilities in the models beyond the standard model, can be also tested. The near-future observation of the transition gives us a great impact since it indicates that there is an approximate discrete symmetry in the lepton sector. If the Mu-to-$\bar{\text{Mu}}$ transition operator is generated, a new muon decay operator can exist and it may interfere with the standard model muon decay operator to induce the corrections to the transverse positron polarization in the $μ^+$ decay. In this paper, we examine the possibility that the Mu-to-$\bar{\text{Mu}}$ transition and the correction to the transverse positron polarization are related, and we show that those two are related in the model of a neutral flavor gauge boson. We also investigate the models to generate the Mu-to-$\bar{\text{Mu}}$ transition, such as an inert $SU(2)_L$ doublet, a $SU(2)_L$ triplet for the type-II seesaw model, a dilepton gauge boson, and a left-right model. The non-zero value of the transverse polarization for one of the two directions, $P_{\rm T_2}$, violates the time-reversal invariance, and the experimental constraint of the electron electric dipole moment can provide a severe constraint on $P_{\rm T_2}$ depending on the model., 28 pages, 2 figures

We study a renormalizable SUSY $SO(10)$ GUT model where the Yukawa couplings of single ${\bf 10}$, single ${\bf \overline{126}}$ and single ${\bf 120}$ fields, $Y_{10},Y_{126},Y_{120}$, account for the quark and lepton Yukawa couplings and the neutrino mass. We pursue the possibility that $Y_{10},Y_{126},Y_{120}$ reproduce the correct quark and lepton masses, CKM and PMNS matrices and neutrino mass differences, and at the same time suppress dimension-5 proton decays (proton decays via colored Higgsino exchange) through their texture, so that the soft SUSY breaking scale can be reduced as much as possible without conflicting the current experimental bound on proton decays. We perform a numerical search for such a texture, and investigate implications of that texture on unknown neutrino parameters, the Dirac CP phase of PMNS matrix, the lightest neutrino mass and the $(1,1)$-component of the neutrino mass matrix in the charged lepton basis. Here we concentrate on the case when the active neutrino mass is generated mostly by the Type-2 seesaw mechanism, in which case the correlation between the suppression of dimension-5 proton decays and the neutrino parameters is expected to be most direct., 38 pages, 5 figures. Version accepted for publication in PTEP. arXiv admin note: text overlap with arXiv:2002.11413

The nearly right unitarity triangle can be simply obtained if a quark mass matrix is written as a linear combination of real rank-1 matrices and the coefficient which gives the mass of the second generation is pure imaginary. Supposing that the source of the CP violation is in the Yukawa coupling to an additional Higgs field which provides a factor for the strange quark and muon mass ratio, we obtain that the angle $\alpha= \phi_2$ of the unitarity triangle shifts from $90^{\rm o}$ by units of $V_{ub}/V_{us}$, and is postdicted as $\alpha \simeq 87^{\rm o}$ or $91^{\rm o}$. The Dirac CP phase $\delta$ which appears in the three-flavor neutrino oscillations is obtained to be $|\delta| \simeq 80^{\rm o}$ if the neutrino mass matrix gives tri-bimaximal-like mixing form. If the factor 3 for the muon and strange quark mass is considered in a simple manner in the quark-lepton unification, we obtain three distinctive prediction of $\delta$ for nearly right-angled phase as $|\delta| \simeq 70^{\rm o}$, $90^{\rm o}$, or $110^{\rm o}$ in an idealistic orthogonal structure of the neutrino mass matrix. The deviation from $90^{\rm o}$ is roughly given by $\arcsin(1/3)$ by inputting the experimental measurements., Comment: 15 pages, references added

The absence of any signal of supersymmetry (SUSY) at the LHC has raised the SUSY particle mass scale compared to $Z$ boson mass $M_Z$. We investigate the naturalness of the electroweak symmetry breaking after considering radiative symmetry breaking along with 125 GeV Higgs mass. We find that the important quantity to measure the naturalness of the hierarchy between the SUSY scale and $M_Z$ is the separation between the radiative symmetry breaking scale, i.e., where $m_{H_u}^2+\mu^2$ turns negative for large $\tan\beta$ case ($\mu$ is the Higgsino mass and $m_{H_u}$ is the SUSY breaking up-type Higgs boson mass) and the average stop mass. Using this measure, one can show that the electroweak symmetry breaking can be natural even if $\mu$ is large contrary to the prevailing claim that $\mu$ is needed to be small to maintain the naturalness., Comment: 15 pages, 3 figures

We explain the 2.3 sigma deviation in the recent measurements of the neutral B mesons decay into muon pairs from the standard model prediction in the framework of supersymmetric grand unified models using anti-symmetric coupling as a new source of flavor violation. We show a correlation between the B_d -> mu^+mu^- decay and the CP phase in the B_d -> J/psi K decay and that their deviations from the standard model predictions can be explained after satisfying constraints arising from various hadronic and leptonic rare decay processes, B-bar{B}, K-bar{K} oscillations data and electric dipole moments of electron and neutron. The allowed parameter space is typically represented by pseudoscalar Higgs mass m_A < 1 TeV and tan beta_H (= {v_u}/{v_d}) < 20 for squark and gluino masses around 2 TeV., Comment: 6 pages, 3 figures

We explain the 2.3 sigma deviation in the recent measurements of the neutral B mesons decay into muon pairs from the standard model prediction in the framework of supersymmetric grand unified models using anti-symmetric coupling as a new source of flavor violation. We show a correlation between the B_d -> mu^+mu^- decay and the CP phase in the B_d -> J/psi K decay and that their deviations from the standard model predictions can be explained after satisfying constraints arising from various hadronic and leptonic rare decay processes, B-bar{B}, K-bar{K} oscillations data and electric dipole moments of electron and neutron. The allowed parameter space is typically represented by pseudoscalar Higgs mass m_A < 1 TeV and tan beta_H (= {v_u}/{v_d}) < 20 for squark and gluino masses around 2 TeV., 6 pages, 3 figures

Supersymmetric SO(10) grand unified models with renormalizable Yukawa couplings involving {\bf 10}, {\bf 126} and {\bf 120} Higgs fields have been shown to give a very economical theory for understanding quark-lepton flavor in a unified framework. In previous papers, we showed how nucleon decay can be suppressed in these models without invoking cancellation, by choice of Yukawa flavor texture within a type II seesaw framework for neutrinos that explains all mixings and masses including the recently observed "large" $��_{13}$. In this follow-up paper, we extend our earlier work to the case of type I seesaw and show that the recently measured "large" $��_{13}$ can be accommodated in this case while suppressing proton decay. We then point out that the two cases (type I and II) lead to different testable predictions for $B(��\to e+��)$ and $B(��\to ��(e) +��)$ as well as different flavor final states in nucleon decay. In particular, we find that for the type I seesaw case, $B(��\to ��+��)$ can be observable while at the same time suppressing $B(��\to e+��)$, whereas in the type II seesaw case, $B(��\to ��+��)$ is always suppressed whereas $B(��\to e+��)$ is observable., 27 pages, 2 figures

A Higgs-like new boson with mass around 126 GeV is now established, but its true nature probably cannot be settled with 2011--2012 LHC data. We assume it is a dilaton with couplings weaker than the Higgs boson (except to $\gamma\gamma$ and $gg$), and explore dynamical symmetry breaking (DSB) by strong Yukawa coupling of a yet unseen heavy chiral quark doublet $Q$. Assuming the actual Higgs boson to be heavy, the Goldstone boson $G$ of electroweak symmetry breaking still couples to $Q$ with Yukawa coupling $\lambda_Q$. A ``bootstrap" gap equation without a Higgs particle is constructed. Electroweak symmetry breaking via strong $\lambda_Q$ generates both heavy mass for $Q$, while self-consistently justifying $G$ as a massless Goldstone particle in the loop. The spontaneous breaking of scale invariance in principle \emph{allows} for a dilaton. We numerically solve such a gap equation and find the mass of the heavy quark to be a couple of TeV. We offer a short critique on the results of the scale-invariant model of Hung and Xiong, where a similar gap equation is built with a massless scalar doublet. Through this we show that a light SM Higgs at 126 GeV cannot be viable within our approach to DSB, while a dilaton with weaker couplings is consistent with our main result., Comment: updated with ICHEP and HCP 2012 results on discovery of Higgs-like particle, version still under review at JHEP (figures unchanged)

We suggest natural TeV-scale seesaw with non-negligible left-right neutrino mixings as preserving tiny neutrino masses. Our analysis is exhibited, without loss of generality, by taking a basis of the neutrino matrices, in which the condition to obtain the left-right mixings is clear. We also suggest a flavor symmetry as an underlying theory, which naturally realizes our setup to preserve tiny neutrino masses. Our setup can predict a magnitude of sin theta_13 in a region of 0.10 to 0.20, depending on the deviation from maximal atmospheric neutrino mixing and CP phase. We also investigate experimental constraints and phenomenology in our setup., 18 pages, 1 figure

We investigate the recent CDF measurement of the Br(B_s --> mu+mu-) which shows excess over the Standard Model. We consider minimal supergravity motivated models (mSUGRA)/CMSSM and grand unified models, SU(5) and SO(10). In the grand unified models, the neutrino mixings provide an additional source of squark flavor violation through the quark-lepton unification. In the context of minimal SU(5) model, we find that the new CDF measurement has imposed a lower bound on the branching ratio of tau --> mu gamma for a large CP phase in the B_s-bar B_s mixing. Recall that there have been indication for a large CP phase in B_s mixing from B_s --> J/psi phi (Tevatron and LHCb) and dimuon asymmetry (D0). We also predict Br(tau --> mu eta) for the possible range of values of Br(tau --> mu gamma)., Comment: 15 pages, 7 figures

We analyze the puzzle of the dimuon CP asymmetry in B_s decays in two Higgs doublet models. We show that the flavor changing neutral current (FCNC) induced by the Higgs coupling in a type III two Higgs doublet model provides a solution to the dimuon charge asymmetry puzzle by enhancing the absorbtive part of the mixing amplitude \Gamma_{12}^s. We investigate different experimental constraints and show that it is possible to enhance \Gamma_{12}^s in order to explain the dimuon asymmetry observed by D0. This enhancement requires large Higgs couplings to the first and second generations of quarks which may also explain the recent 3.2 \sigma Wjj excess observed by CDF., Comment: 13 pages, 3 figures

We investigate the recent CDF measurement of the Br(B_s --> mu+mu-) which shows excess over the Standard Model. We consider minimal supergravity motivated models (mSUGRA)/CMSSM and grand unified models, SU(5) and SO(10). In the grand unified models, the neutrino mixings provide an additional source of squark flavor violation through the quark-lepton unification. In the context of minimal SU(5) model, we find that the new CDF measurement has imposed a lower bound on the branching ratio of tau --> mu gamma for a large CP phase in the B_s-bar B_s mixing. Recall that there have been indication for a large CP phase in B_s mixing from B_s --> J/psi phi (Tevatron and LHCb) and dimuon asymmetry (D0). We also predict Br(tau --> mu eta) for the possible range of values of Br(tau --> mu gamma)., 15 pages, 7 figures

We investigate the effect of the dimuon CP asymmetry from the B decay modes, recently observed at 3.2 sigma deviation from the Standard Model (SM) by the D0 collaboration, in the context of SU(5) and SO(10) GUT models. We exhibit that a large amount of flavor violation between the second and the third generation is generated due to the large neutrino atmospheric mixing angle and this flavor violation can be responsible for the observed large CP asymmetry due to the presence of new phases (not present in the CKM matrix) in the Yukawa couplings. We also study the implication of the parameter space in these GUT models with large CP violating lepton asymmetry for different phenomenologies, e.g., Br(tau -> mu + gamma), Br(B_s -> mu + mu) at the Fermilab, direct detection of dark matter (DM) in the ongoing detectors and measurement of muon flux from solar neutrinos at the IceCube experiment., 23 pages, 5 figures

We combine the analyses for flavor changing neutral current processes and dark matter solutions in minimal-type supersymmetric grand unified theory (GUT) models, SO(10) and SU(5), with a large B_s - anti-B_s mixing phase and large tan beta. For large tan beta, the double penguin diagram dominates the SUSY contribution to the B_s - anti-B_s mixing amplitude. Also, the Br(B_s -> mu mu) constraint becomes important as it grows as tan^6 beta, although it can still be suppressed by large pseudoscalar Higgs mass m_A. We investigate the correlation between B_s -> mu mu and the dark matter direct detection cross-section through their dependence on m_A. In the minimal-type of SU(5) with type I seesaw, the large mixing in neutrino Dirac couplings results in large lepton flavor violating decay process tau to mu gamma, which in turn sets upper bound on m_A. In the SO(10) case, the large mixing can be chosen to be in the Majorana couplings instead, and the constraint from Br(tau -> mu gamma) can be avoided. The heavy Higgs funnel region turns out to be an interesting possibility in both cases and the direct dark matter detection should be possible in the near future in these scenarios., Comment: 19 pages, 8 figures

We investigate the possibility of a large B_s-\bar B_s mixing phase in the context of grand unified theory (GUT) models, e.g., SO(10) and SU(5). In these models, we find that a large phase of B_s mixing is correlated with Br(b -> s gamma), Br(tau -> mu gamma) and Br(B_s -> mu mu) for large tan beta. In the case of the SO(10) model, the large phase of B_s mixing is correlated with Br(b -> s gamma) and Br(B_s -> mu mu) and we find that a large B_s mixing corresponds to an enhanced Br(B_s -> mu mu) about to be probed by the Tevatron. In the case of the SU(5) model, the large phase is correlated with Br(tau -> mu gamma) and Br(B_s -> mu mu). In this case, the Br(tau -> mu gamma) constraint requires a smaller pseudo-scalar Higgs mass which in turn generates a large Br(B_s -> mu mu) almost at the edge of present experimental constraint. If the present observation of large phase of B_s mixing persists in the upcoming data, using all these branching ratios, we will be able to distinguish these models., Comment: 17 pages, 3 figures

Diverse mass and mixing patterns between the quarks and leptons makes it challenging to construct a simple grand unified theory of flavor. We show that SO(10) SUSY GUTs with type II seesaw mechanism giving neutrino masses provide a natural framework for addressing this issue. A simple ansatz that the dominant Yukawa matrix (the 10-Higgs coupling to matter) has rank one, appears to simultaneously explain both the large lepton mixings as well as the observed quark flavor hierarchy in these models. A testable prediction of this ansatz is the neutrino mixing, U_{e3}, which should be observable in planned long baseline experiments., Comment: 24 pages, 8 figures

We combine the analyses for flavor changing neutral current processes and dark matter solutions in minimal-type supersymmetric grand unified theory (GUT) models, SO(10) and SU(5), with a large B_s - anti-B_s mixing phase and large tan beta. For large tan beta, the double penguin diagram dominates the SUSY contribution to the B_s - anti-B_s mixing amplitude. Also, the Br(B_s -> mu mu) constraint becomes important as it grows as tan^6 beta, although it can still be suppressed by large pseudoscalar Higgs mass m_A. We investigate the correlation between B_s -> mu mu and the dark matter direct detection cross-section through their dependence on m_A. In the minimal-type of SU(5) with type I seesaw, the large mixing in neutrino Dirac couplings results in large lepton flavor violating decay process tau to mu gamma, which in turn sets upper bound on m_A. In the SO(10) case, the large mixing can be chosen to be in the Majorana couplings instead, and the constraint from Br(tau -> mu gamma) can be avoided. The heavy Higgs funnel region turns out to be an interesting possibility in both cases and the direct dark matter detection should be possible in the near future in these scenarios., 19 pages, 8 figures

We construct an orbifold model in which all the standard model particles are unified in a gauge multiplet in higher dimensional supersymmetric gauge theory. We find that a flavor symmetry has to remain in four dimensions due to the discrete charge conservation for orbifold conditions if the colored Higgs components in the gauge multiplet are projected out. When the flavor symmetry originates from the E_8 bulk gauge symmetry, the successful unification model can be constructed. In the model, all the Dirac Yukawa couplings for quarks and leptons are generated by the higher dimensional gauge interaction., Comment: 17 pages

We consider the possibility of a large phase of B_s-\bar B_s mixing in supersymmetric SU(5) and SO(10) models. We find that in the SU(5) model, the magnitude of this phase is correlated with the branching ratio of \tau -> \mu\gamma and the phase can be within 2\sigma of the recent UTfit analysis. In the case of SO(10) models, this correlation can be relaxed and a large phase can be obtained. In this scenario, a non-zero value of CP asymmetry for B -> X_s\gamma will be predicted. We predict the sparticle mass ranges for the LHC for these models once the UTfit result is accommodated and discuss the dark matter and the anomalous magnetic moment constraints on this analysis., Comment: 5 pages, 3 figures

We study the constraint arising from the recently observed D - anti-D mixing in the context of supersymmetric models with left-right symmetry. In these models, the supersymmetric contributions in the mixing amplitudes of D - anti-D, K - anti-K and B - anti-B are all correlated. We compare the constraint from the D - anti-D mixing with the K - anti-K mixing and find that the D - anti-D mixing constrains the maximal supersymmetric contribution to the B_s - anti-B_s mixing amplitude. The maximal supersymmetric contribution can allow a large CP phase of B_s - anti-B_s mixing which agrees with the recent measurement of the CP asymmetry of B_s -> J/psi phi decay., 5 pages, 3 figures

Recently, a more than 2sigma discrepancy has been observed between the well measured inclusive value of Vub and the predicted value of Vub from the unitarity triangle fit using the world average value of sin2beta. We attempt to resolve this tension in the context of grand unified SO(10) and SU(5) models where the neutrino mixing matrix is responsible for flavor changing neutral current at the weak scale and the models with non-proportional A-terms (can be realized simply in the context of intersecting D-brane models) and investigate the interplay between the constraints arising from B_{s,d}-\bar B_{s,d} mixings, epsilon_K, Br(tau -> mu gamma), Br(mu -> e gamma) and a fit of this new discrepancy. We also show that the ongoing measurement of the phase of Bs mixing will be able to identify the grand unified model. The measurement of Br(tau -> e gamma) will also be able to test these scenarios, especially the models with non-proportional A-terms., 20 pages, 4 figures. Minor corrections, references added

We study B_s-\bar{B}_s mixing in grand unified SO(10), SU(5) models where the mixings among the second and third generation squarks arise due to the existence of flavor violating sources in the Dirac and Majorana couplings which are responsible for neutrino mixings. We find that when the branching ratio of tau->mu gamma decay is enhanced to be around the current experimental bound, B_s-\bar{B}_s mixing may also contain large contribution from supersymmetry in the SO(10) boundary condition. Consequently, the phase of B_s-\bar{B}_s mixing is large (especially for small tan beta and large scalar mass m_0) and can be tested by measuring CP asymmetries of B_s decay modes., 5 pages, 3 figures. Modifications in the text and the title, references added, results unchanged, to appear in PRL

It has recently been shown that a minimal SO(10) model with a single {\bf 10} and single {\bf 126} Higgs field breaking B-L symmetry predicts large solar and atmospheric mixings in agreement with observations if it is assumed that the neutrino mass obeys the type II seesaw formula. No additional symmetries need to be assumed for this purpose. Understanding CP violation in the renormalizable version of the model however requires a significant non-CKM source. In this paper we show that if we extend the model by the inclusion of a heavy {\bf 120} dimensional Higgs field, then it can accomodate CKM CP violation while remaining predictive in the neutrino sector. Among the predictions are:(i) solar mixing angle in the observed range; (ii)\theta_{13} in the range of 0.1 to 0.26; (iii) the Dirac phase close to maximal for the central value of the solar mixing angle., Comment: 16 pages, 10 figures, Comments are added, Typos are corrected, An erroneous sentence on discrete symmetry is modified, Results are unchanged

We suggest a solution to the \mu problem of gauge mediated supersymmtery breaking models based on flavor symmetries. In this scenario the \mu term arises through the vacuum expectation value of a singlet scalar field which is suppressed by a flavor symmetry factor relative to the scale of dynamical SUSY breaking. The same flavor symmetry also ensures that the soft SUSY breaking parameter B\mu is not much larger than \mu^2, a necessary condition for the stability of electroweak symmetry breaking. Explicit examples where B\mu ~ \mu^2 and B\mu << \mu^2 are presented. The latter case provides a natural solution to the supersymmetric CP problem. We show that the same flavor symmetry that suppresses the \mu and the B\mu parameters can also play a role in explaining the fermion mass and mixing hierarchy puzzle., Comment: 12 pages in LaTeX

It is studied that `no-scale' model makes hierarchy between scalar top mass and Z boson mass naturally. The supersymmetry breaking parameters are constrained by flavor changing neutral currents in minimal supersymmetric standard model. One of the solution of the problem is that gaugino mass is the only source of the supersymmetry breaking parameters at Planck scale. However, in such scenario, we need a cancellation between Higgs mass parameters in minimization condition of the Higgs potential. We insist that there is no such cancellation in no-scale model, and that the no-scale model gives us the prediction of scalar top mass and lightest Higgs mass. The lightest Higgs mass is predicted as $m_H = 110 \pm 5 $ GeV., 21 pages, 9 figures, Minor corrections