Improved predictions for of the muon and

Physical Review D, 2011

We calculate the shift in the atomic energy levels induced by the presence of a scalar field which couples to matter and photons. We find that a combination of atomic measurements can be used to probe both these couplings independently. A new and stringent bound on the matter coupling springs from the precise measurement of the 1s to 2s energy level difference in the hydrogen atom, while the coupling to photons is essentially constrained by the Lamb shift. Combining these constraints with current particle physics bounds we find that the contribution of a scalar field to the recently claimed discrepancy in the proton radius measured using electronic and muonic atoms is negligible.

Physical Review D, 2007

The MSSM with large tan β and heavy squarks (Mq > ∼ 1 TeV) is a theoretically well motivated and phenomenologically interesting extension of the SM. This scenario naturally satisfies all the electroweak precision constraints and, in the case of not too heavy slepton sector (Ml < ∼ 0.5 TeV), can also easily accommodate the (g − 2) µ anomaly. Within this framework non-standard effects could possibly be detected in the near future in a few lowenergy flavour-violating observables, such as B(B → τ ν), B(B s,d → ℓ + ℓ − ), B(B → X s γ), and B(µ → eγ). Interpreting the (g − 2) µ anomaly as the first hint of this scenario, we analyse the correlations of these low-energy observables under the additional assumption that the relic density of a Bino-like LSP accommodates the observed dark matter distribution.

Journal of High Energy Physics, 2012

Discrete flavour groups have been studied in connection with special patterns of neutrino mixing suggested by the data, such as Tri-Bimaximal mixing (groups A 4 , S 4 . . . ) or Bi-Maximal mixing (group S 4 . . . ) etc. We review the predictions for sin θ 13 in a number of these models and confront them with the experimental measurements. We compare the performances of the different classes of models in this respect. We then consider, in a supersymmetric framework, the important implications of these flavour symmetries on lepton flavour violating processes, like µ → eγ and similar processes. We discuss how the existing limits constrain these models, once their parameters are adjusted so as to optimize the agreement with the measured values of the mixing angles. In the simplified CMSSM context, adopted here just for indicative purposes, the small tan β range and heavy SUSY mass scales are favoured by lepton flavour violating processes, which makes it even more difficult to reproduce the reported muon g − 2 discrepancy.

Physical Review D, 2008

Journal of High Energy Physics, 2008

Sparticle mass hierarchies will play an important role in the type of signatures that will be visible at the Large Hadron Collider. We analyze these hierarchies for the four lightest sparticles for a general class of supergravity unified models including nonuniversalities in the soft breaking sector. It is shown that out of nearly 10 4 possibilities of sparticle mass hierarchies, only a small number survives the rigorous constraints of radiative electroweak symmetry breaking, relic density and other experimental constraints. The signature space of these mass patterns at the Large Hadron Collider is investigated using a large set of final states including multi-leptonic states, hadronically decaying τ s, tagged b jets and other hadronic jets. In all, we analyze more than 40 such lepton plus jet and missing energy signatures along with several kinematical signatures such as missing transverse momentum, effective mass, and invariant mass distributions of final state observables. It is shown that a composite analysis can produce significant discrimination among sparticle mass patterns allowing for a possible identification of the source of soft breaking. While the analysis given is for supergravity models, the techniques based on mass pattern analysis are applicable to wide class of models including string and brane models.

Physical Review D, 2010

We re-examine the prospects for the detection of Higgs mediated lepton flavor violation at LHC, at a photon collider and in τ decays such as τ → µη, τ → µγ. We allow for the presence of a large, model independent, source of lepton flavor violation in the slepton mass matrix in the τ − µ sector by the mass insertion approximation and constrain the parameter space using the τ LFV decays together with the B-mesons physics observables, the anomalous magnetic moment of the muon and the dark matter relic density. We further impose the exclusion limit on spin-independent neutralinonucleon scattering from CDMS and the CDF limits from direct search of the heavy neutral Higgs at the TEVATRON. We find rates probably too small to be observed at future experiments if models have to accommodate for the relic density measured by WMAP and explain the (g − 2)µ anomaly: better prospects are found if these two constraints are applied only as upper bounds. The spin-independent neutralino-nucleon cross section in the studied constrained parameter space is just below the present CDMS limit and the running XENON100 experiment will cover the region of the parameter space where the lightest neutralino has large gaugino-higgsino mixing.

Journal of High Energy Physics, 2007

We explore 'benchmark surfaces' suitable for studying the phenomenology of Higgs bosons in the minimal supersymmetric extension of the Standard Model (MSSM), which are chosen so that the supersymmetric relic density is generally compatible with the range of cold dark matter density preferred by WMAP and other observations. These benchmark surfaces are specified assuming that gaugino masses m 1/2 , soft trilinear supersymmetry-breaking parameters A 0 and the soft supersymmetry-breaking contributions m 0 to the squark and slepton masses are universal, but not those associated with the Higgs multiplets (the NUHM framework). The benchmark surfaces may be presented as (M A , tan β) planes with fixed or systematically varying values of the other NUHM parameters, such as m 0 , m 1/2 , A 0 and the Higgs mixing parameter µ. We discuss the prospects for probing experimentally these benchmark surfaces at the Tevatron collider, the LHC, the ILC, in B physics and in direct dark-matter detection experiments. An Appendix documents developments in the FeynHiggs code that enable the user to explore for her/himself the WMAP-compliant benchmark surfaces.

The European Physical Journal C, 2016

In this work we analyze the possibility to explain the muon anomalous magnetic moment discrepancy within theory and experiment through lepton flavor violation processes. We propose a flavor extended MSSM by considering a hierarchical family structure for the trilinear scalar Soft-Supersymmetric terms of the Lagrangian, present at the SUSY breaking scale. We obtain analytical results for the rotation mass matrix, with the consequence of having non-universal slepton masses and the possibility of leptonic flavour mixing. The one-loop supersymmetric contributions to the leptonic flavour violating process τ → µγ are calculated in the physical basis, instead of using the well known Mass Insertion Method. The flavor violating processes BR(l i → l j γ) are also obtained, in particular τ → µγ is well within the experimental bounds. We present the regions in parameter space where the muon g-2 problem is either entirely solved or partially reduced through the contribution of these flavor violating processes.

Chinese Physics C, 2010

We update our Standard Model predictions for g−2 of the muon and for the hadronic contributions to the running of the QED coupling, ∆α (5) had (M 2 Z). Particular emphasis is put on recent changes in the hadronic contributions from new data in the 2π channel and from the energy region just below 2 GeV.

Acta Physica Slovaca. Reviews and Tutorials, 2000

Analyticity in a Phenomenology of Electro-Weak Structure of HadronsThe utility of an application of the analyticity in a phenomenology of electro-weak structure of hadrons is demonstrated in a number of obtained new and experimentally verifiable results. With this aim first the problem of an inconsistency of the asymptotic behavior of VMD model with the asymptotic behavior of form factors of baryons and nuclei is solved generally and a general approach for determination of the lowest normal and anomalous singularities of form factors from the corresponding Feynman diagrams is reviewed. Then many useful applications by making use of the analytic properties of electro-weak form factors and amplitudes of various electromagnetic processes of hadrons are carried out.

Journal of High Energy Physics

We show that a unified framework based on an SU(2)H horizontal symmetry which generates a naturally large neutrino transition magnetic moment and explains the XENON1T electron recoil excess also predicts a positive shift in the muon anomalous magnetic moment. This shift is of the right magnitude to be consistent with the Brookhaven measurement as well as the recent Fermilab measurement of the muon g − 2. A relatively light neutral scalar from a Higgs doublet with mass near 100 GeV contributes to muon g − 2, while its charged partner induces the neutrino magnetic moment. In contrast to other multi-scalar theories, in the model presented here there is no freedom to control the sign and strength of the muon g − 2 contribution. We analyze the collider tests of this framework and find that the HL-LHC can probe the entire parameter space of these models.

Journal of High Energy Physics, 2010

We perform a forecast of the MSSM with universal soft terms (CMSSM) for the LHC, based on an improved Bayesian analysis. We do not incorporate ad hoc measures of the fine-tuning to penalize unnatural possibilities: such penalization arises from the Bayesian analysis itself when the experimental value of M Z is considered. This allows to scan the whole parameter space, allowing arbitrarily large soft terms. Still the low-energy region is statistically favoured (even before including dark matter or g-2 constraints). Contrary to other studies, the results are almost unaffected by changing the upper limits taken for the soft terms. The results are also remarkable stable when using flat or logarithmic priors, a fact that arises from the larger statistical weight of the low-energy region in both cases. Then we incorporate all the important experimental constrains to the analysis, obtaining a map of the probability density of the MSSM parameter space, i.e. the forecast of the MSSM. Since not all the experimental information is equally robust, we perform separate analyses depending on the group of observables used. When only the most robust ones are used, the favoured region of the parameter space contains a significant portion outside the LHC reach. This effect gets reinforced if the Higgs mass is not close to its present experimental limit and persits when dark matter constraints are included. Only when the g-2 constraint (based on e + e − data) is considered, the preferred region (for µ > 0) is well inside the LHC scope. We also perform a Bayesian comparison of the positive-and negative-µ possibilities.

2008

We investigate a neutrino mass model in which the neutrino data is accounted for by bilinear R– parity violating supersymmetry with anomaly mediated supersymmetry breaking. We focus on the CERN Large Hadron Collider (LHC) phenomenology, studying the reach of generic supersymmetry search channels with leptons, missing energy and jets. A special feature of this model is the existence of long lived neutralinos and charginos which decay inside the detector leading to detached vertices. We demonstrate that the largest reach is obtained in the displaced vertices channel and that practically all of the reasonable parameter space will be covered with an integrated luminosity of 10 fb−1. We also compare the displaced vertex reaches of the LHC and Tevatron. Electronic address: camposc@feg.unesp.br Electronic address: mad@susy.fis.puc.cl Electronic address: eboli@fma.if.usp.br Electronic address: magro@fma.if.usp.br Electronic address: porod@physik.uni-wuerzburg.de Electronic address: solveig@...

Journal of High Energy Physics, 2009

We study the LHC signature of the minimal supersymmetric standard model with non-universal sfermion masses. In the model, soft masses of gauginos and the 3rd generation of 10 of SU(5) are around the weak scale, while other sfermion soft mass is universal and around a few TeV. Such sfermion mass spectrum is motivated not only from flavor, CP and naturalness constraints but also from E 6 grand unified model with non-Abelian horizontal (flavor) symmetry. The characteristic signature of the model at the LHC is the dominance of the events with 4 b partons in the final state together with high rate of mildly boosted top quark arising from gluino decay. The prominent high p T jet also arises from squark decay. We show it is possible to find the characteristic signature in the early stage of the LHC. The discrimination of our scenario from some CMSSM model points with similar signature may be possible with large integrated luminosity. The result of sparticle mass measurement using exclusive channel with the help of hemisphere analysis, and inclusive measurement of gluino and squark masses using M T 2 and M min T 2 in some representative model points are presented.

Physics Reports, 2020

We review the present status of the Standard Model calculation of the anomalous magnetic moment of the muon. This is performed in a perturbative expansion in the fine-structure constant α and is broken down into pure QED, electroweak, and hadronic contributions. The pure QED contribution is by far the largest and has been evaluated up to and including O(α 5) with negligible numerical uncertainty. The electroweak contribution is suppressed by (m µ /M W) 2 and only shows up at the level of the seventh significant digit. It has been evaluated up to two loops and is known to better than one percent. Hadronic contributions are the most difficult to calculate and are responsible for almost all of the theoretical uncertainty. The leading hadronic contribution appears at O(α 2) and is due to hadronic vacuum polarization, whereas at O(α 3) the hadronic light-by-light scattering contribution appears. Given the low characteristic scale of this observable, these contributions have to be calculated with nonperturbative methods, in particular, dispersion relations and the lattice approach to QCD. The largest part of this review is dedicated to a detailed account of recent efforts to improve the calculation of these two contributions with either a data-driven, dispersive approach, or a first-principle, lattice-QCD approach. The final result reads a SM µ = 116 591 810(43) × 10 −11 and is smaller than the Brookhaven measurement by 3.7σ. The experimental uncertainty will soon be reduced by up to a factor four by the new experiment currently running at Fermilab, and also by the future J-PARC experiment. This and the prospects to further reduce the theoretical uncertainty in the near future-which are also discussed here-make this quantity one of the most promising places to look for evidence of new physics.

Physical Review D, 2014

The discovery of the Higgs boson at the Large Hadron Collider (LHC) has a great impact on the minimal supersymmetric extension of the Standard Model (MSSM). In the context of the constrained MSSM (CMSSM) and its extension with non-universal masses for the MSSM Higgs doublets (NUHM2), sparticles with masses > 1 TeV are necessary to reproduce the observed Higgs boson mass of 125-126 GeV. On the other hand, there appears to be a significant amount of discrepancy between the measured muon g − 2 and the Standard Model prediction. A successful explanation of this discrepancy in the MSSM requires new contributions involving relatively light sparticles with masses < 1 TeV. In this paper, we attempt to accommodate the two conflicting requirements in an SU(5) inspired extension of the CMSSM. We assign non-universal but flavor blind soft supersymmetry breaking masses to the scalar components in5 and 10 matter supermultiplets. The two MSSM Higgs doublets in the 5,5 representations of SU (5) are also assigned unequal soft mass 2 at M GU T. We identify parameter regions which can simultaneously accommodate the observed Higgs boson mass and the muon g − 2 data, and which are compatible with other phenomenological constraints such as neutralino dark matter relic abundance and rare B-meson decays. Some regions of the allowed parameter space will be explored at the upgraded LHC and by dark matter direct detection experiments.

Journal of High Energy Physics, 2011

We investigate the impact of recent direct supersymmetry (SUSY) searches on a non-universal sfermion mass scenario focusing on naturalness. One of the advantages of this scenario is that the non-universality between third generation and first two generation sfermion masses can relax the tension between naturalness and constraints from flavour and CP violating observables. In the parameter region, where various phenomenological constraints are satisfied, the constraints to this scenario from ATLAS 165 pb −1 "0-lepton" search and 35 pb −1 "b-jet" search are much weaker than those to the constrained minimal SUSY standard model, because of differences in the main SUSY production processes and the main decay chains. Naturalness can be easily achieved in this scenario in accord with the current direct SUSY searches. An additional dedicated analysis may be needed to discover/exclude this scenario.

Physical Review D, 2015

Physical Review Letters, 2017

The first ionization potential (IP) and electron affinity (EA) of the gold atom have been determined to an unprecedented accuracy using relativistic coupled cluster calculations up to the pentuple excitation level including the Breit and QED contributions. We reach meV accuracy (with respect to the experimental values) by carefully accounting for all individual contributions beyond the standard relativistic coupled cluster approach. Thus, we are able to resolve the long-standing discrepancy between experimental and theoretical IP and EA of gold.

Physical Review D, 2008

Effects of vacuum polarization by hadronic and heavy-fermion insertions were the last unknown two-loop QED corrections to high-energy Bhabha scattering and have been announced in [S. Actis, M. Czakon, J. Gluza, and T. Riemann, Phys. Rev. Lett. 100, 131602 (2008).]. Here we describe the corrections in detail and explore their numerical influence. The hadronic contributions to the virtual Oð 2 Þ QED corrections to the Bhabha-scattering cross section are evaluated using dispersion relations and computing the convolution of hadronic data with perturbatively calculated kernel functions. The technique of dispersion integrals is also employed to derive the virtual Oð 2 Þ corrections generated by muon-, tau-, and top-quark loops in the small electron-mass limit for arbitrary values of the internal-fermion masses. At a meson factory with 1 GeV center-of-mass energy the complete effect of hadronic and heavy-fermion corrections amounts to less than 0.5 per mille and reaches, at 10 GeV, up to about 2 per mille. At the Z resonance it amounts to 2.3 per mille at 3 degrees; overall, hadronic corrections are less than 4 per mille. For ILC energies (500 GeV or above), the combined effect of hadrons and heavy fermions becomes 6 per mille at 3 degrees; hadrons contribute less than 20 per mille in the whole angular region.

Journal of High Energy Physics, 2008

We analyse the phenomenology of orbifold scenarios from the heterotic superstring, and the resulting theoretical predictions for the direct detection of neutralino dark matter. In particular, we study the parameter space of these constructions, computing the low-energy spectrum and taking into account the most recent experimental and astrophysical constraints, as well as imposing the absence of dangerous charge and colour breaking minima. In the remaining allowed regions the spin-independent part of the neutralino-proton cross section is calculated and compared with the sensitivity of dark matter detectors. In addition to the usual non universalities of the soft terms in orbifold scenarios due to the modular weight dependence, we also consider D-term contributions to scalar masses. These are generated by the presence of an anomalous U (1), providing more flexibility in the resulting soft terms, and are crucial in order to avoid charge and colour breaking minima. Thanks to the D-term contribution, large neutralino detection cross sections can be found, within the reach of projected dark matter detectors.