WorldWideScience

Sample records for u1 electroweak models

  1. A SU(3) x U(1) model for electroweak interactions

    International Nuclear Information System (INIS)

    Pisano, F.; Pleitez, V.

    1992-01-01

    We consider a gauge model based on a SU(3) vector U(1) symmetry in which the lepton number is violated explicitly by charged scalar and gauge boson, including a vector field with double electric charge. (author)

  2. O(5) x U(1) electroweak theory

    International Nuclear Information System (INIS)

    Mukku, C.; Sayed, W.A.

    1980-12-01

    An anomaly free O(5) x U(1) theory of electroweak interactions is described which provides a unified description of electroweak phenomena for two families of standard leptons and quarks. No ''new'' non-sequential type fermions of the standard model are introduced as has been the case for all past studies based on this group. The present scheme requires the introduction of two further charged and three more neutral gauge fields over and above the Wsup(+-), Z and photon fields of SU(2) x U(1) giving rise to new neutral and charged currents. In this note we outline our reasons for proposing the present electroweak scheme, give the basic structure of the model, discuss the symmetry breaking pattern which ensures that SU(2)sub(L) x U(1) is the low energy symmetry, point out the new interactions present in the extended framework and obtain limits on the masses of all the gauge fields. (author)

  3. O(5) x U(1) electroweak theory

    International Nuclear Information System (INIS)

    Mukku, C.; Sayed, W.A.

    1981-01-01

    An anomaly-free O(5) x U(1) theory of electroweak interactions is described which provides a unified description of electroweak phenomena for two families of standard leptons and quarks. No ''new'' nonsequential-type fermions are introduced, unlike the case for all past studies based on this group. The present scheme requires the introduction of two further charged and three more neutral gauge fields over and above those of SU(2) x U(1) giving rise to new neutral and charged currents

  4. Electroweak radiative corrections in the SU(2) x U(1) standard model

    International Nuclear Information System (INIS)

    Hollik, W.

    1986-01-01

    This paper contains a discussion of the 1-loop renormalization of the standard model and applications of the radiative corrections to fermion processes. Thereby we restrict the discussion to leptonic processes since these allow the cleanest access to the more subtle parts of the theory avoiding theoretical uncertainties as far as possible. Actual measurements of the W +- ,Z masses and of sin 2 θ W already indicate the presence of higher order effects in electroweak processes between fermions. More accurate measurements in the near future colliders LEP and SLC will allow to test the standard model beyond the tree level. At the 1-loop level a big amount of work has already been done with a satisfactory agreement between the individual calculations for the standard processes: μ decays, ν-scattering, and e + e → μ + μ - . 38 refs

  5. Anomalous U(1)A and electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Gogoladze, I.; Tsulaya, M.

    2000-01-01

    A new mechanism for electroweak symmetry breaking in the supersymmetric Standard Model is suggested. Our suggestion is based on the presence of an anomalous U(1) A gauge symmetry, which naturally arises in the four-dimensional superstring theory, and heavily relies on the corresponding Fayet-Illiopoulos ξ-term

  6. Anomalous U(1)A and electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Gogoladze, Ilia

    2000-10-01

    We suggest a mechanism for electroweak symmetry breaking in the Supersymmetric Standard Model. Our suggestion is based on the presence of an anomalous U(1) A gauge symmetry, which naturally arises in the four dimensional superstring theory, and heavily relies on the value of the corresponding Fayet-Illiopoulos ξ-term. (author)

  7. String completion of an SU(3c⊗SU(3L⊗U(1X electroweak model

    Directory of Open Access Journals (Sweden)

    Andrea Addazi

    2016-08-01

    Full Text Available The extended electroweak SU(3c⊗SU(3L⊗U(1X symmetry framework “explaining” the number of fermion families is revisited. While 331-based schemes can not easily be unified within the conventional field theory sense, we show how to do it within an approach based on D-branes and (unoriented open strings, on Calabi–Yau singularities. We show how the theory can be UV-completed in a quiver setup, free of gauge and string anomalies. Lepton and baryon numbers are perturbatively conserved, so neutrinos are Dirac-type, and their lightness results from a novel TeV scale seesaw mechanism. Dynamical violation of baryon number by exotic instantons could induce neutron–antineutron oscillations, with proton decay and other dangerous R-parity violating processes strictly forbidden.

  8. Phenomenology of the spontaneous C P violation in SU(3)L x U(1)Y electroweak models

    International Nuclear Information System (INIS)

    Epele, Luis N.; Gomez Dumm, Daniel A.

    1994-01-01

    This work studies the phenomenological consequence of the spontaneous C P violation in a SU(3) L x U(1) Y model with three Higgs triplets and one sextuplet, which has been recently proposed. Since this C P-violating effects are due to the presence of complex vacuum expectation values in the Higgs sector, our analysis requires a detailed study of the enlarged potential

  9. Electroweak Supersymmetry with an Approximate U(1)_PQ

    Energy Technology Data Exchange (ETDEWEB)

    Hall, L.J.; Watari, T.

    2004-05-12

    A predictive framework for supersymmetry at the TeV scale is presented, which incorporates the Ciafaloni-Pomarol mechanism for the dynamical determination of the \\mu parameter of the MSSM. It is replaced by (\\lambda S), where S is a singlet field, and the axion becomes a heavy pseudoscalar, G, by adding a mass, m_G, by hand. The explicit breaking of Peccei-Quinn (PQ) symmetry is assumed to be sufficiently weak at the TeV scale that the only observable consequence is the mass m_G. Three models for the explicit PQ breaking are given; but the utility of this framework is that the predictions for all physics at the electroweak scale are independent of the particular model for PQ breaking. Our framework leads to a theory similar to the MSSM, except that \\mu is predicted by the Ciafaloni-Pomarol relation, and there are light, weakly-coupled states in the spectrum. The production and cascade decay of superpartners at colliders occurs as in the MSSM, except that there is one extra stage of the cascade chain, with the next-to-LSP decaying to its"superpartner" and \\tilde{s}, dramatically altering the collider signatures for supersymmetry. The framework is compatible with terrestrial experiments and astrophysical observations for a wide range of m_G and. If G is as light as possible, 300 keV< m_G< 3 MeV, it can have interesting effects on the radiation energy density during the cosmological eras of nucleosynthesis and acoustic oscillation, leading to predictions for N_{\

  10. Closing the SU(3)LxU(1)X symmetry at the electroweak scale

    International Nuclear Information System (INIS)

    Dias, Alex G.; Montero, J. C.; Pleitez, V.

    2006-01-01

    We show that some models with SU(3) C xSU(3) L xU(1) X gauge symmetry can be realized at the electroweak scale and that this is a consequence of an approximate global SU(2) L+R symmetry. This symmetry implies a condition among the vacuum expectation value of one of the neutral Higgs scalars, the U(1) X 's coupling constant, g X , the sine of the weak mixing angle sinθ W , and the mass of the W boson, M W . In the limit in which this symmetry is valid it avoids the tree level mixing of the Z boson of the standard model with the extra Z ' boson. We have verified that the oblique T parameter is within the allowed range indicating that the radiative corrections that induce such a mixing at the 1-loop level are small. We also show that a SU(3) L+R custodial symmetry implies that in some of the models we have to include sterile (singlets of the 3-3-1 symmetry) right-handed neutrinos with Majorana masses, since the seesaw mechanism is mandatory to obtain light active neutrinos. Moreover, the approximate SU(2) L+R subset of SU(3) L+R symmetry implies that the extra nonstandard particles of these 3-3-1 models can be considerably lighter than it had been thought before so that new physics can be really just around the corner

  11. Models of electroweak symmetry breaking

    CERN Document Server

    Pomarol, Alex

    2015-01-01

    This chapter present models of electroweak symmetry breaking arising from strongly interacting sectors, including both Higgsless models and mechanisms involving a composite Higgs. These scenarios have also been investigated in the framework of five-dimensional warped models that, according to the AdS/CFT correspondence, have a four-dimensional holographic interpretation in terms of strongly coupled field theories. We explore the implications of these models at the LHC.

  12. Electroweak breaking in supersymmetric models

    CERN Document Server

    Ibáñez, L E

    1992-01-01

    We discuss the mechanism for electroweak symmetry breaking in supersymmetric versions of the standard model. After briefly reviewing the possible sources of supersymmetry breaking, we show how the required pattern of symmetry breaking can automatically result from the structure of quantum corrections in the theory. We demonstrate that this radiative breaking mechanism works well for a heavy top quark and can be combined in unified versions of the theory with excellent predictions for the running couplings of the model. (To be published in ``Perspectives in Higgs Physics'', G. Kane editor.)

  13. U(1) x U(1) x U(1) symmetry of the Kimura 3ST model and phylogenetic branching processes

    International Nuclear Information System (INIS)

    Bashford, J D; Jarvis, P D; Sumner, J G; Steel, M A

    2004-01-01

    An analysis of the Kimura 3ST model of DNA sequence evolution is given on the basis of its continuous Lie symmetries. The rate matrix commutes with a U(1) x U(1) x U(1) phase subgroup of the group GL(4) of 4 x 4 invertible complex matrices acting on a linear space spanned by the four nucleic acid base letters. The diagonal 'branching operator' representing speciation is defined, and shown to intertwine the U(1) x U(1) x U(1) action. Using the intertwining property, a general formula for the probability density on the leaves of a binary tree under the Kimura model is derived, which is shown to be equivalent to established phylogenetic spectral transform methods. (letter to the editor)

  14. Global analysis of general SU(2) x SU(2) x U(1) models with precision data

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Ken; Yu, Jiang-Hao; Yuan, C.P. [Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy; Schmitz, Kai [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy

    2010-05-15

    We present the results of a global analysis of a class of models with an extended electroweak gauge group of the form SU(2) x SU(2) x U(1), often denoted as G(221) models, which include as examples the left-right, the lepto-phobic, the hadro-phobic, the fermio-phobic, the un-unified, and the non-universal models. Using an effective Lagrangian approach, we compute the shifts to the coeffcients in the electroweak Lagrangian due to the new heavy gauge bosons, and obtain the lower bounds on the masses of the Z' and W' bosons. The analysis of the electroweak parameter bounds reveals a consistent pattern of several key observables that are especially sensitive to the effects of new physics and thus dominate the overall shape of the respective parameter contours. (orig.)

  15. Global analysis of general SU(2) x SU(2) x U(1) models with precision data

    International Nuclear Information System (INIS)

    Hsieh, Ken; Yu, Jiang-Hao; Yuan, C.P.; Schmitz, Kai; Michigan State Univ., East Lansing, MI

    2010-05-01

    We present the results of a global analysis of a class of models with an extended electroweak gauge group of the form SU(2) x SU(2) x U(1), often denoted as G(221) models, which include as examples the left-right, the lepto-phobic, the hadro-phobic, the fermio-phobic, the un-unified, and the non-universal models. Using an effective Lagrangian approach, we compute the shifts to the coeffcients in the electroweak Lagrangian due to the new heavy gauge bosons, and obtain the lower bounds on the masses of the Z' and W' bosons. The analysis of the electroweak parameter bounds reveals a consistent pattern of several key observables that are especially sensitive to the effects of new physics and thus dominate the overall shape of the respective parameter contours. (orig.)

  16. Two-dimensional gauge model with vector U(1) and axial-vector U(1) symmetries

    International Nuclear Information System (INIS)

    Watabiki, Y.

    1989-01-01

    We have succeeded in constructing a two-dimensional gauge model with both vector U(1) and axial-vector U(1) symmetries. This model is exactly solvable. The Schwinger term vanishes in this model as a consequence of the above symmetries, and negative-norm states appear. However, the norms of physical states are always positive semidefinite due to the gauge symmetries

  17. Heavy charged leptons in an SU(3)L x U(1)N model

    International Nuclear Information System (INIS)

    Pleitez, V.; Tonasse, M.D.

    1992-12-01

    An SU(3) L x U(1) N model for the electroweak interactions which includes additional heavy charged leptons is considered. These leptons have not strong constraints on their masses since they do not couple in the same way as the lightest leptons to the neutral-currents and also because new contributions to the muon g-2 factor already suppressed because of the massive new vector boson present in this model. (author)

  18. Electroweak Calibration of the Higgs Characterization Model

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    I will present the preliminary results of histogram fits using the Higgs Combine histogram fitting package. These fits can be used to estimate the effects of electroweak contributions to the p p -> H mu+ mu- Higgs production channel and calibrate Beyond Standard Model (BSM) simulations which ignore these effects. I will emphasize my findings' significance in the context of other research here at CERN and in the broader world of high energy physics.

  19. Neutrinoless double beta decay in an SU(3)L x U(1)N model

    International Nuclear Information System (INIS)

    Pleitez, V.; Tonasse, M.D.

    1993-01-01

    A model for the electroweak interactions with SU (3) L x U(1) N gauge symmetry is considered. It is shown that, it is the conservation of F = L + B which forbids massive neutrinos and the neutrinoless double beta decay, (β β) On u. Explicit and spontaneous breaking of F imply that the neutrinos have an arbitrary mass and (β β) On u proceeds also with some contributions that do not depend explicitly on the neutrino mass. (author)

  20. Electroweak baryogenesis and the standard model

    International Nuclear Information System (INIS)

    Huet, P.

    1994-01-01

    Electroweak baryogenesis is addressed within the context of the standard model of particle physics. Although the minimal standard model has the means of fulfilling the three Sakharov's conditions, it falls short to explaining the making of the baryon asymmetry of the universe. In particular, it is demonstrated that the phase of the CKM mixing matrix is an, insufficient source of CP violation. The shortcomings of the standard model could be bypassed by enlarging the symmetry breaking sector and adding a new source of CP violation

  1. Electroweak symmetry breaking beyond the Standard Model

    International Nuclear Information System (INIS)

    Bhattacharyya, Gautam

    2012-01-01

    In this paper, two key issues related to electroweak symmetry breaking are addressed. First, how fine-tuned different models are that trigger this phenomenon? Second, even if a light Higgs boson exists, does it have to be necessarily elementary? After a brief introduction, the fine-tuning aspects of the MSSM, NMSSM, generalized NMSSM and GMSB scenarios shall be reviewed, then the little Higgs, composite Higgs and the Higgsless models shall be compared. Finally, a broad overview will be given on where we stand at the end of 2011. (author)

  2. The renormalization of the electroweak standard model

    International Nuclear Information System (INIS)

    Boehm, M.; Spiesberger, H.; Hollik, W.

    1984-03-01

    A renormalization scheme for the electroweak standard model is presented in which the electric charge and the masses of the gauge bosons, Higgs particle and fermions are used as physical parameters. The photon is treated such that quantum electrodynamics is contained in the usual form. Field renormalization respecting the gauge symmetry gives finite Green functions. The Ward identities between the Green functions of the unphysical sector allow a renormalization that maintains the simple pole structure of the propagators. Explicit results for the renormalization self energies and vertex functions are given. They can be directly used as building blocks for the evaluation of l-loop radiative corrections. (orig.)

  3. Flipped SU(5) times U(1) in superconformal models

    Energy Technology Data Exchange (ETDEWEB)

    Bailin, D.; Katechou, E.K. (Sussex Univ., Brighton (United Kingdom). School of Mathematical and Physical Sciences); Love, A. (London Univ. (United Kingdom))

    1992-01-10

    This paper reports that flipped SU(5) {times} U(1) models are constructed in the framework of tensoring of N = 2 superconformal minimal models quotiented by discrete symmetries. Spontaneous breaking of flipped SU(5) {times} U(1) and extra U(1) factors in the gauge group along F-flat directions of the effective potential is studied.

  4. SU(2) x U(1) x U'(1) models which are slightly different from the Weinberg-Salam model

    International Nuclear Information System (INIS)

    Gao, C.; Wu, D.

    1981-01-01

    We discuss SU(2) x U(1) x U'(1) models by a uniform formula which is convenient for their comparison with the standard Weinberg-Salam model. As examples, we give three interesting models which are based on different grand unification models. In one model, U'(1) does not contribute to the electromagnetic interaction; in the other two, both U(1) and U'(1) do contribute to the electromagnetic interaction. Also, the first two models can approach the standard Weinberg-Salam model as close as one wants; but the third model has limitations on it

  5. Electroweak vacuum stability in classically conformal B - L extension of the standard model

    Energy Technology Data Exchange (ETDEWEB)

    Das, Arindam; Okada, Nobuchika; Papapietro, Nathan [University of Alabama, Department of Physics and Astronomy, Alabama (United States)

    2017-02-15

    We consider the minimal U(1){sub B-L} extension of the standard model (SM) with the classically conformal invariance, where an anomaly-free U(1){sub B-L} gauge symmetry is introduced along with three generations of right-handed neutrinos and a U(1){sub B-L} Higgs field. Because of the classically conformal symmetry, all dimensional parameters are forbidden. The B - L gauge symmetry is radiatively broken through the Coleman-Weinberg mechanism, generating the mass for the U(1){sub B-L} gauge boson (Z{sup '} boson) and the right-handed neutrinos. Through a small negative coupling between the SM Higgs doublet and the B - L Higgs field, the negative mass term for the SM Higgs doublet is generated and the electroweak symmetry is broken. In this model context, we investigate the electroweak vacuum instability problem in the SM. It is well known that in the classically conformal U(1){sub B-L} extension of the SM, the electroweak vacuum remains unstable in the renormalization group analysis at the one-loop level. In this paper, we extend the analysis to the two-loop level, and perform parameter scans. We identify a parameter region which not only solve the vacuum instability problem, but also satisfy the recent ATLAS and CMS bounds from search for Z{sup '} boson resonance at the LHC Run-2. Considering self-energy corrections to the SM Higgs doublet through the right-handed neutrinos and the Z{sup '} boson, we derive the naturalness bound on the model parameters to realize the electroweak scale without fine-tunings. (orig.)

  6. Nonminimal quartic inflation in classically conformal U(1 ) X extended standard model

    Science.gov (United States)

    Oda, Satsuki; Okada, Nobuchika; Raut, Digesh; Takahashi, Dai-suke

    2018-03-01

    We propose quartic inflation with nonminimal gravitational coupling in the context of the classically conformal U(1 ) X extension of the standard model (SM). In this model, the U(1 ) X gauge symmetry is radiatively broken through the Coleman-Weinberg mechanism, by which the U(1 ) X gauge boson (Z' boson) and the right-handed Majorana neutrinos acquire their masses. We consider their masses in the range of O (10 GeV )-O (10 TeV ) , which are accessible to high-energy collider experiments. The radiative U(1 ) X gauge symmetry breaking also generates a negative mass squared for the SM Higgs doublet, and the electroweak symmetry breaking occurs subsequently. We identify the U(1 ) X Higgs field with inflaton and calculate the inflationary predictions. Because of the Coleman-Weinberg mechanism, the inflaton quartic coupling during inflation, which determines the inflationary predictions, is correlated to the U(1 ) X gauge coupling. With this correlation, we investigate complementarities between the inflationary predictions and the current constraint from the Z' boson resonance search at the LHC Run 2 as well as the prospect of the search for the Z' boson and the right-handed neutrinos at the future collider experiments.

  7. Parity violations in electron-nucleon scattering and the SU(2)sub(L)xSU(2)sub(R)xU(1)sub(L+R) electroweak symmetry

    International Nuclear Information System (INIS)

    Rajpoot, S.

    1981-07-01

    The SU(2)sub(L) x SU(2)sub(R) x U(1)sub(L+R) model of electroweak interactions is described with the most general gauge couplings gsub(L), gsub(R) and gsub(L+R). The case in which neutrino neutral current interactions are identical to the standard SU(2)sub(L) x U(1)sub(L+R) model is discussed in detail. It is shown that with the weak angle lying in the experimental range sin 2 thetaSUB(w)=0.23+-0.015 and 1 2 /gsub(R) 2 <3 it is possible to explain the amount of parity violation observed at SLAC and at the same time predict values of the ''weak charge'' in bismuth to lie in the range admitted by the controversal data from different experiments. (author)

  8. Global analysis of general SU(2)xSU(2)xU(1) models with precision data

    International Nuclear Information System (INIS)

    Hsieh, Ken; Yu, Jiang-Hao; Yuan, C.-P.; Schmitz, Kai

    2010-01-01

    We present the results of a global analysis of a class of models with an extended electroweak gauge group of the form SU(2)xSU(2)xU(1), often denoted as G(221) models, which include as examples the left-right, the leptophobic, the hadrophobic, the fermiophobic, the un-unified, and the nonuniversal models. Using an effective Lagrangian approach, we compute the shifts to the coefficients in the electroweak Lagrangian due to the new heavy gauge bosons, and obtain the lower bounds on the masses of the Z ' and W ' bosons. The analysis of the electroweak parameter bounds reveals a consistent pattern of several key observables that are especially sensitive to the effects of new physics and thus dominate the overall shape of the respective parameter contours.

  9. 3-3-1 models at electroweak scale

    International Nuclear Information System (INIS)

    Dias, Alex G.; Montero, J.C.; Pleitez, V.

    2006-01-01

    We show that in 3-3-1 models there exist a natural relation among the SU(3) L coupling constant g, the electroweak mixing angle θ W , the mass of the W, and one of the vacuum expectation values, which implies that those models can be realized at low energy scales and, in particular, even at the electroweak scale. So that, being that symmetries realized in Nature, new physics may be really just around the corner

  10. O(5)sub(L)xO(5)sub(R)xU(1)sub(V) electro-weak gauge theory and the neutrino pairing mechanism

    International Nuclear Information System (INIS)

    Samiullah, M.; Mubarak, A.

    1981-08-01

    The possibility of using the group O(5)sub(L)xO(5)sub(R)xU(1)sub(V) for unifying the weak and electromagnetic interactions is studied. We are led to an anomaly free theory. Potentially the theory has the advantage of incorporating the previous results. For example, all the results of O(5)sub(L)xU(1) studies are, as a special case, obtainable at low energies. In the process of breaking the symmetry down to Weinberg-Salam theory at the level of SU(2)sub(L)xSU(2)sub(R)xU(1)sub(V), we have employed the neutrino proposed by Mannheim. We have been able to reproduce several of the conventional electroweak aspects such as the parity violation in both the lepton and charged quark sectors, Weinberg mixing pattern in the neutral current sector while keeping the left-handed neutrinos massless. All the salient features of low energy phenomenology are shown to follow. (author)

  11. The global electroweak Standard Model fit after the Higgs discovery

    CERN Document Server

    Baak, Max

    2013-01-01

    We present an update of the global Standard Model (SM) fit to electroweak precision data under the assumption that the new particle discovered at the LHC is the SM Higgs boson. In this scenario all parameters entering the calculations of electroweak precision observalbes are known, allowing, for the first time, to over-constrain the SM at the electroweak scale and assert its validity. Within the SM the W boson mass and the effective weak mixing angle can be accurately predicted from the global fit. The results are compatible with, and exceed in precision, the direct measurements. An updated determination of the S, T and U parameters, which parametrize the oblique vacuum corrections, is given. The obtained values show good consistency with the SM expectation and no direct signs of new physics are seen. We conclude with an outlook to the global electroweak fit for a future e+e- collider.

  12. Electroweak theory and the Standard Model

    CERN Multimedia

    CERN. Geneva; Giudice, Gian Francesco

    2004-01-01

    There is a natural splitting in four sectors of the theory of the ElectroWeak (EW) Interactions, at pretty different levels of development/test. Accordingly, the 5 lectures are organized as follows, with an eye to the future: Lecture 1: The basic structure of the theory; Lecture 2: The gauge sector; Lecture 3: The flavor sector; Lecture 4: The neutrino sector; Lecture 5: The EW symmetry breaking sector.

  13. Variations of little Higgs models and their electroweak constraints

    International Nuclear Information System (INIS)

    Csaki, Csaba; Hubisz, Jay; Meade, Patrick; Kribs, Graham D.; Terning, John

    2003-01-01

    We calculate the tree-level electroweak precision constraints on a wide class of little Higgs models including variations of the littlest Higgs SU(5)/SO(5), SU(6)/Sp(6), and SU(4) 4 /SU(3) 4 models. By performing a global fit to the precision data we find that for generic regions of the parameter space the bound on the symmetry breaking scale f is several TeV, where we have kept the normalization of f constant in the different models. For example, the 'minimal' implementation of SU(6)/Sp(6) is bounded by f>3.0 TeV throughout most of the parameter space, and SU(4) 4 /SU(3) 4 is bounded by f 2 ≡f 1 2 +f 2 2 >(4.2 TeV) 2 . In certain models, such as SU(4) 4 /SU(3) 4 , a large f does not directly imply a large amount of fine-tuning since the heavy-fermion masses that contribute to the Higgs boson mass can be lowered below f for a carefully chosen set of parameters. We also find that for certain models (or variations) there exist regions of parameter space in which the bound on f can be lowered into the range 1-2 TeV. These regions are typically characterized by a small mixing between heavy and standard model gauge bosons and a small (or vanishing) coupling between heavy U(1) gauge bosons and light fermions. Whether such a region of parameter space is natural or not is ultimately contingent on the UV completion

  14. Electroweak Physics

    OpenAIRE

    Erler, Jens; Langacker, Paul

    2008-01-01

    The results of high precision weak neutral current (WNC), Z-pole, and high energy collider electroweak experiments have been the primary prediction and test of electroweak unification. The electroweak program is briefly reviewed from a historical perspective. The current status and the implications for the standard model and beyond are discussed.

  15. B-meson anomalies and Higgs physics in flavored U(1)' model

    Science.gov (United States)

    Bian, Ligong; Lee, Hyun Min; Park, Chan Beom

    2018-04-01

    We consider a simple extension of the Standard Model with flavor-dependent U(1)', that has been proposed to explain some of B-meson anomalies recently reported at LHCb. The U(1)' charge is chosen as a linear combination of anomaly-free B_3-L_3 and L_μ -L_τ . In this model, the flavor structure in the SM is restricted due to flavor-dependent U(1)' charges, in particular, quark mixings are induced by a small vacuum expectation value of the extra Higgs doublet. As a result, it is natural to get sizable flavor-violating Yukawa couplings of heavy Higgs bosons involving the bottom quark. In this article, we focus on the phenomenology of the Higgs sector of the model including extra Higgs doublet and singlet scalars. We impose various bounds on the extended Higgs sector from Higgs and electroweak precision data, B-meson mixings and decays as well as unitarity and stability bounds, then discuss the productions and decays of heavy Higgs bosons at the LHC.

  16. The U(1) Higgs model in an external electromagnetic field

    International Nuclear Information System (INIS)

    Damgaard, P.H.; Heller, U.M.

    1988-01-01

    An external electromagnetic field is coupled to the lattice-regularized U(1) Higgs model. We study the phase diagram of this model by both analytical and numerical techniques for different values of the external field strength tensor. The results are compared with expectations based on the analogy with superconducting systems, as described by the phenomenological Ginzburg-Landau theory. (orig.)

  17. A model with isospin doublet U(1)D gauge symmetry

    Science.gov (United States)

    Nomura, Takaaki; Okada, Hiroshi

    2018-05-01

    We propose a model with an extra isospin doublet U(1)D gauge symmetry, in which we introduce several extra fermions with odd parity under a discrete Z2 symmetry in order to cancel the gauge anomalies out. A remarkable issue is that we impose nonzero U(1)D charge to the Standard Model Higgs, and it gives the most stringent constraint to the vacuum expectation value of a scalar field breaking the U(1)D symmetry that is severer than the LEP bound. We then explore relic density of a Majorana dark matter candidate without conflict of constraints from lepton flavor violating processes. A global analysis is carried out to search for parameters which can accommodate with the observed data.

  18. The electroweak phase transition in minimal supergravity models

    CERN Document Server

    Nanopoulos, Dimitri V

    1994-01-01

    We have explored the electroweak phase transition in minimal supergravity models by extending previous analysis of the one-loop Higgs potential to include finite temperature effects. Minimal supergravity is characterized by two higgs doublets at the electroweak scale, gauge coupling unification, and universal soft-SUSY breaking at the unification scale. We have searched for the allowed parameter space that avoids washout of baryon number via unsuppressed anomalous Electroweak sphaleron processes after the phase transition. This requirement imposes strong constraints on the Higgs sector. With respect to weak scale baryogenesis, we find that the generic MSSM is {\\it not} phenomenologically acceptable, and show that the additional experimental and consistency constraints of minimal supergravity restricts the mass of the lightest CP-even Higgs even further to $m_h\\lsim 32\\GeV$ (at one loop), also in conflict with experiment. Thus, if supergravity is to allow for baryogenesis via any other mechanism above the weak...

  19. Systematics of quark mass matrices in the standard electroweak model

    International Nuclear Information System (INIS)

    Frampton, P.H.; Jarlskog, C.; Stockholm Univ.

    1985-01-01

    It is shown that the quark mass matrices in the standard electroweak model satisfy the empirical relation M = M' + O(lambda 2 ), where M(M') refers to the mass matrix of the charge 2/3 (-1/3) quarks normalized to the largest eigenvalue, msub(t) (msub(b)), and lambda = Vsub(us) approx.= 0.22. (orig.)

  20. State of electroweak interactions

    International Nuclear Information System (INIS)

    Lane, K.

    1984-01-01

    I assess what we know and what we do not know about the electroweak interactions. In particular, I argue that existing data on the electroweak parameters rho, sin 2 theta/sub w/ and G/sub F/ and on the recently discovered W +- and Z 0 allow us reasonably to conclude that: (1) the W +- and Z 0 truly are the elementary massive gauge bosons of SU(2) x U(1) and not the composite bosons of a new strong interaction, and (2) the electroweak scalar sector consists of weak doublets only. The most important thing we do not know is everything else about the electroweak scalar sector. In the hope of soon shedding light on this issue, a new method of searching for electroweak scalars in existing p-barp colliders is proposed. The basis of this method is that the branching ratio of W +- to decay to a charged plus a neutral scalar (expected in non-minimal SU(2) x U(1) models) can be as large as 1-2%, with detectable rates up to scalar masses of approx.35 GeV

  1. Electroweak symmetry breaking in supersymmetric gauge-Higgs unification models

    International Nuclear Information System (INIS)

    Choi, Kiwoon; Jeong, Kwang-Sik; Okumura, Ken-ichi; Haba, Naoyuki; Shimizu, Yasuhiro; Yamaguchi, Masahiro

    2004-01-01

    We examine the Higgs mass parameters and electroweak symmetry breaking in supersymmetric orbifold field theories in which the 4-dimensional Higgs fields originate from higher-dimensional gauge supermultiplets. It is noted that such gauge-Higgs unification leads to a specific boundary condition on the Higgs mass parameters at the compactification scale, which is independent of the details of supersymmetry breaking mechanism. With this boundary condition, phenomenologically viable parameter space of the model is severely constrained by the condition of electroweak symmetry breaking for supersymmetry breaking scenarios which can be realized naturally in orbifold field theories. For instance, if it is assumed that the 4-dimensional effective theory is the minimal supersymmetric standard model with supersymmetry breaking parameters induced by the Scherk-Schwarz mechanism, a correct electroweak symmetry breaking can not be achieved for reasonable range of parameters of the model, even when one includes additional contributions to the Higgs mass parameters from the auxiliary component of 4-dimensional conformal compensator. However if there exists a supersymmetry breaking mediated by brane superfields, sizable portion of the parameter space can give a correct electroweak symmetry breaking. (author)

  2. Z-Z' mass hierarchy in a supersymmetric model with a secluded U(1)'-breaking sector

    International Nuclear Information System (INIS)

    Erler, Jens; Langacker, Paul; Li Tianjun

    2002-01-01

    We consider the Z ' /Z mass hierarchy in a supersymmetric model in which the U(1) ' is broken in a secluded sector coupled to the ordinary sector only by gauge and possibly soft terms. A large mass hierarchy can be achieved while maintaining the normal sparticle spectra if there is a direction in which the tree level potential becomes flat when a particular Yukawa coupling vanishes. We describe the conditions needed for the desired breaking pattern, to avoid unwanted global symmetries, and for an acceptable effective μ parameter. The electroweak breaking is dominated by A terms rather than scalar masses, leading to tan β≅1. The spectrum of the symmetry breaking sector is displayed. There is significant mixing between the MSSM particles and new standard model singlets, for both the Higgs scalars and the neutralinos. A larger Yukawa coupling for the effective μ parameter is allowed than in the NMSSM because of the U(1) ' contribution to the running from a high scale. The upper bound on the tree-level mass of the lightest CP even Higgs doublet mass is about cx174 GeV, where c is of order unity, but the actual mass eigenvalues are generally smaller because of singlet mixing

  3. CP violation and electroweak baryogenesis in the Standard Model

    Directory of Open Access Journals (Sweden)

    Brauner Tomáš

    2014-04-01

    Full Text Available One of the major unresolved problems in current physics is understanding the origin of the observed asymmetry between matter and antimatter in the Universe. It has become a common lore to claim that the Standard Model of particle physics cannot produce sufficient asymmetry to explain the observation. Our results suggest that this conclusion can be alleviated in the so-called cold electroweak baryogenesis scenario. On the Standard Model side, we continue the program initiated by Smit eight years ago; one derives the effective CP-violating action for the Standard Model bosons and uses the resulting effective theory in numerical simulations. We address a disagreement between two previous computations performed effectively at zero temperature, and demonstrate that it is very important to include temperature effects properly. Our conclusion is that the cold electroweak baryogenesis scenario within the Standard Model is tightly constrained, yet producing enough baryon asymmetry using just known physics still seems possible.

  4. Electroweak interactions

    International Nuclear Information System (INIS)

    Bjorken, J.D.

    1980-10-01

    A point of view of the electroweak interaction is presented. It begins phenomenologically and moves in stages toward the conventional gauge theory formalism containing elementary scalar Higgs-fields and then beyond. The purpose in so doing is that the success of the standard SU(2) x U(1) theory in accounting for low energy phenomena need not automatically imply success at high energies. It is deemed unlikely by most theorists that the predicted W +- or Z 0 does not exist or does not have the mass and/or couplings anticipated in the standard model. However, the odds that the standard predictions will work are not 100%. Therefore there is some reason to look at the subject as one would were he forced by a wrong experimental outcome - to go back to fundamentals and ascertain what is the minimal amount of theory necessary to account for the data

  5. Precision Electroweak Measurements and Constraints on the Standard Model

    CERN Document Server

    ,

    2010-01-01

    This note presents constraints on Standard Model parameters using published and preliminary precision electroweak results measured at the electron-positron colliders LEP and SLC. The results are compared with precise electroweak measurements from other experiments, notably CDF and DØ at the Tevatron. Constraints on the input parameters of the Standard Model are derived from the combined set of results obtained in high-$Q^2$ interactions, and used to predict results in low-$Q^2$ experiments, such as atomic parity violation, Møller scattering, and neutrino-nucleon scattering. The main changes with respect to the experimental results presented in 2009 are new combinations of results on the width of the W boson and the mass of the top quark.

  6. Implications of Anomalous U(1) Symmetry in Unified Models the Flipped SU(5) x U(1) Paradigm

    CERN Document Server

    Ellis, Jonathan Richard; Rizos, J; Ellis, John

    2000-01-01

    A generic feature of string-derived models is the appearance of an anomalousAbelian U(1)_A symmetry which, among other properties, constrains the Yukawacouplings and distinguishes the three families from each other. In this paper,we discuss in a model-independent way the general constraints imposed by such aU(1)_A symmetry on fermion masses, R-violating couplings and proton-decayoperators in a generic flipped SU(5) x U(1)' model. We construct all possibleviable fermion mass textures and give various examples of effective low-energymodels which are distinguished from each other by their different predictionsfor B-, L- and R-violating effects. We pay particular attention to predictionsfor neutrino masses, in the light of the recent Super-Kamiokande data.

  7. Supersymmetric U(1)' model with multiple dark matters

    International Nuclear Information System (INIS)

    Hur, Taeil; Lee, Hye-Sung; Nasri, Salah

    2008-01-01

    We consider a scenario where a supersymmetric model has multiple dark matter particles. Adding a U(1) ' gauge symmetry is a well-motivated extension of the minimal supersymmetric standard model (MSSM). It can cure the problems of the MSSM such as the μ problem or the proton decay problem with high-dimensional lepton number and baryon number violating operators which R parity allows. An extra parity (U parity) may arise as a residual discrete symmetry after U(1) ' gauge symmetry is spontaneously broken. The lightest U-parity particle (LUP) is stable under the new parity becoming a new dark matter candidate. Up to three massive particles can be stable in the presence of the R parity and the U parity. We numerically illustrate that multiple stable particles in our model can satisfy both constraints from the relic density and the direct detection, thus providing a specific scenario where a supersymmetric model has well-motivated multiple dark matters consistent with experimental constraints. The scenario provides new possibilities in the present and upcoming dark matter searches in the direct detection and collider experiments

  8. The hierarchy problem of the electroweak standard model revisited

    International Nuclear Information System (INIS)

    Jegerlehner, Fred

    2013-05-01

    A careful renormalization group analysis of the electroweak Standard Model reveals that there is no hierarchy problem in the SM. In the broken phase a light Higgs turns out to be natural as it is self-protected and self-tuned by the Higgs mechanism. It means that the scalar Higgs needs not be protected by any extra symmetry, specifically super symmetry, in order not to be much heavier than the other SM particles which are protected by gauge- or chiral-symmetry. Thus the existence of quadratic cutoff effects in the SM cannot motivate the need for a super symmetric extensions of the SM, but in contrast plays an important role in triggering the electroweak phase transition and in shaping the Higgs potential in the early universe to drive inflation as supported by observation.

  9. The hierarchy problem of the electroweak standard model revisited

    Energy Technology Data Exchange (ETDEWEB)

    Jegerlehner, Fred [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2013-05-15

    A careful renormalization group analysis of the electroweak Standard Model reveals that there is no hierarchy problem in the SM. In the broken phase a light Higgs turns out to be natural as it is self-protected and self-tuned by the Higgs mechanism. It means that the scalar Higgs needs not be protected by any extra symmetry, specifically super symmetry, in order not to be much heavier than the other SM particles which are protected by gauge- or chiral-symmetry. Thus the existence of quadratic cutoff effects in the SM cannot motivate the need for a super symmetric extensions of the SM, but in contrast plays an important role in triggering the electroweak phase transition and in shaping the Higgs potential in the early universe to drive inflation as supported by observation.

  10. Implications of hidden gauged U (1 ) model for B anomalies

    Science.gov (United States)

    Fuyuto, Kaori; Li, Hao-Lin; Yu, Jiang-Hao

    2018-06-01

    We propose a hidden gauged U (1 )H Z' model to explain deviations from the standard model (SM) values in lepton flavor universality known as RK and RD anomalies. The Z' only interacts with the SM fermions via their mixing with vectorlike doublet fermions after the U (1 )H symmetry breaking, which leads to b →s μ μ transition through the Z' at tree level. Moreover, introducing an additional mediator, inert-Higgs doublet, yields b →c τ ν process via charged scalar contribution at tree level. Using flavio package, we scrutinize adequate sizes of the relevant Wilson coefficients to these two processes by taking various flavor observables into account. It is found that significant mixing between the vectorlike and the second generation leptons is needed for the RK anomaly. A possible explanation of the RD anomaly can also be simultaneously addressed in a motivated situation, where a single scalar operator plays a dominant role, by the successful model parameters for the RK anomaly.

  11. Electroweak amplitudes in chiral quark models

    International Nuclear Information System (INIS)

    Fiolhais, Manuel

    2004-01-01

    After referring to some basic features of chiral models for baryons, with quarks and mesons, we describe how to construct model states representing physical baryons. We consider soliton models such as the Linear Sigma Model or the Chromodielectric Model, and bag models such as the Cloudy Bag Model. These models are solved approximately using variational approaches whose starting point is a mean-field description. We go beyond the mean-field description by introducing quantum fluctuations in the mesonic degrees of freedom. This is achieved, in a first step, by using a quantum state to represent meson clouds and, secondly, by performing an angular momentum and isospin projection from the mean-field state (actually a coherent state). Model states for baryons (nucleon, Delta, Roper) constructed in this way are used to determine several physical properties. I this seminar we paid a particular attention to the nucleon-delta electromagnetic and weak transition, presenting the model predictions for the electromagnetic and axial amplitudes

  12. Vector condensate model of electroweak interactions

    International Nuclear Information System (INIS)

    Cynolter, G.; Pocsik, G.

    1997-01-01

    Motivated by the fact that the Higgs is not seen, a new version of the standard model is proposed where the scalar doublet is replaced by a vector doublet and its neutral member forms a nonvanishing condensate. Gauge fields are coupled to the new vector fields B in a gauge invariant way leading to mass terms for the gauge fields by condensation. The model is presented and some implications are discussed. (K.A.)

  13. Electroweak symmetry breaking beyond the Standard Model

    Indian Academy of Sciences (India)

    words, now that the gauge symmetry is established with a significant ..... picture, the Higgs is some kind of a composite bound state emerging from a strongly .... (i) Little Higgs vs. composite: Little Higgs models were introduced to solve the little ...

  14. Large (g-2)$_{\\mu}$ in SU(5) x U(1) supergravity models

    CERN Document Server

    López, J L; Wang, X

    1994-01-01

    We compute the supersymmetric contribution to the anomalous magnetic moment of the muon within the context of $SU(5)\\times U(1)$ supergravity models. The largest possible contributions to $a^{susy}_\\mu$ occur for the largest allowed values of $\\tan\\beta$ and can easily exceed the present experimentally allowed range, even after the LEP lower bounds on the sparticle masses are imposed. Such $\\tan\\beta$ enhancement implies that $a^{susy}_\\mu$ can greatly exceed both the electroweak contribution ($\\approx1.95\\times10^{-9}$) and the present hadronic uncertainty ($\\approx\\pm1.75\\times10^{-9}$). Therefore, the new E821 Brookhaven experiment (with an expected accuracy of $0.4\\times10^{-9}$) should explore a large fraction (if not all) of the parameter space of these models, corresponding to slepton, chargino, and squarks masses as high as 200, 300, and 1000 GeV respectively. Moreover, contrary to popular belief, the $a^{susy}_\\mu$ contribution can have either sign, depending on the sign of the Higgs mixing parameter...

  15. Explaining the Higgs decays at the LHC with an extended electroweak model

    International Nuclear Information System (INIS)

    Alves, Alexandre; Ramirez Barreto, E.; Dias, A.G.; Pires, S.C.A. de; Rodrigues da Silva, P.S.; Queiroz, Farinaldo S.

    2013-01-01

    We show that the observed enhancement in the diphoton decays of the recently discovered new boson at the LHC, which we assume to be a Higgs boson, can be naturally explained by a new doublet of charged vector bosons from extended electroweak models with SU(3) C x SU(3) L x U(1) X symmetry. These models are also rather economical in explaining the measured signal strengths, within the current experimental errors, demanding fewer assumptions and less parameters tuning. Our results show a good agreement between the theoretical expected sensitivity to a 126-125 GeV Higgs boson, and the experimental significance observed in the diphoton channel at the 8 TeV LHC. Effects of an invisible decay channel for the Higgs boson are also taken into account, in order to anticipate a possible confirmation of deficits in the branching ratios into ZZ * , WW * , bottom quarks, and tau leptons. (orig.)

  16. First Order Electroweak Phase Transition from (Non)Conformal Extensions of the Standard Model

    DEFF Research Database (Denmark)

    Sannino, Francesco; Virkajärvi, Jussi

    2015-01-01

    We analyse and compare the finite-temperature electroweak phase transition properties of classically (non)conformal extensions of the Standard Model. In the classically conformal scenarios the breaking of the electroweak symmetry is generated radiatively. The models feature new scalars coupled co...... the associated models are testable at the upcoming Large Hadron Collider run two experiments....

  17. Electroweak phase transition in two Higgs doublet models

    International Nuclear Information System (INIS)

    Cline, J.M.; Lemieux, P.

    1997-01-01

    We reexamine the strength of the first-order phase transition in the electroweak theory supplemented by an extra Higgs doublet. The finite-temperature effective potential V eff is computed to one-loop order, including the summation of ring diagrams, to study the ratio φ c /T c of the Higgs field VEV to the critical temperature. We make a number of improvements over previous treatments, including a consistent treatment of Goldstone bosons in V eff , an accurate analytic approximation to V eff valid for any mass-to-temperature ratios, and use of the experimentally measured top quark mass. For two-Higgs-doublet models, we identify a significant region of parameter space where φ c /T c is large enough for electroweak baryogenesis, and we argue that this identification should persist even at higher orders in perturbation theory. In the case of the minimal supersymmetric standard model, our results indicate that the extra Higgs bosons have little effect on the strength of the phase transition. copyright 1997 The American Physical Society

  18. New Models and Methods for the Electroweak Scale

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, Linda [The Ohio State Univ., Columbus, OH (United States). Dept. of Physics

    2017-09-26

    This is the Final Technical Report to the US Department of Energy for grant DE-SC0013529, New Models and Methods for the Electroweak Scale, covering the time period April 1, 2015 to March 31, 2017. The goal of this project was to maximize the understanding of fundamental weak scale physics in light of current experiments, mainly the ongoing run of the Large Hadron Collider and the space based satellite experiements searching for signals Dark Matter annihilation or decay. This research program focused on the phenomenology of supersymmetry, Higgs physics, and Dark Matter. The properties of the Higgs boson are currently being measured by the Large Hadron collider, and could be a sensitive window into new physics at the weak scale. Supersymmetry is the leading theoretical candidate to explain the natural nessof the electroweak theory, however new model space must be explored as the Large Hadron collider has disfavored much minimal model parameter space. In addition the nature of Dark Matter, the mysterious particle that makes up 25% of the mass of the universe is still unknown. This project sought to address measurements of the Higgs boson couplings to the Standard Model particles, new LHC discovery scenarios for supersymmetric particles, and new measurements of Dark Matter interactions with the Standard Model both in collider production and annihilation in space. Accomplishments include new creating tools for analyses of Dark Matter models in Dark Matter which annihilates into multiple Standard Model particles, including new visualizations of bounds for models with various Dark Matter branching ratios; benchmark studies for new discovery scenarios of Dark Matter at the Large Hardon Collider for Higgs-Dark Matter and gauge boson-Dark Matter interactions; New target analyses to detect direct decays of the Higgs boson into challenging final states like pairs of light jets, and new phenomenological analysis of non-minimal supersymmetric models, namely the set of Dirac

  19. Tests of the standard electroweak model in beta decay

    Energy Technology Data Exchange (ETDEWEB)

    Severijns, N.; Beck, M. [Universite Catholique de Louvain (UCL), Louvain-la-Neuve (Belgium); Naviliat-Cuncic, O. [Caen Univ., CNRS-ENSI, 14 (France). Lab. de Physique Corpusculaire

    2006-05-15

    We review the current status of precision measurements in allowed nuclear beta decay, including neutron decay, with emphasis on their potential to look for new physics beyond the standard electroweak model. The experimental results are interpreted in the framework of phenomenological model-independent descriptions of nuclear beta decay as well as in some specific extensions of the standard model. The values of the standard couplings and the constraints on the exotic couplings of the general beta decay Hamiltonian are updated. For the ratio between the axial and the vector couplings we obtain C{sub A},/C{sub V} = -1.26992(69) under the standard model assumptions. Particular attention is devoted to the discussion of the sensitivity and complementarity of different precision experiments in direct beta decay. The prospects and the impact of recent developments of precision tools and of high intensity low energy beams are also addressed. (author)

  20. Tests of the standard electroweak model in beta decay

    International Nuclear Information System (INIS)

    Severijns, N.; Beck, M.; Naviliat-Cuncic, O.

    2006-05-01

    We review the current status of precision measurements in allowed nuclear beta decay, including neutron decay, with emphasis on their potential to look for new physics beyond the standard electroweak model. The experimental results are interpreted in the framework of phenomenological model-independent descriptions of nuclear beta decay as well as in some specific extensions of the standard model. The values of the standard couplings and the constraints on the exotic couplings of the general beta decay Hamiltonian are updated. For the ratio between the axial and the vector couplings we obtain C A ,/C V = -1.26992(69) under the standard model assumptions. Particular attention is devoted to the discussion of the sensitivity and complementarity of different precision experiments in direct beta decay. The prospects and the impact of recent developments of precision tools and of high intensity low energy beams are also addressed. (author)

  1. Dark matter contribution to b → sμ+μ- anomaly in local U(1) Lμ -Lτ model

    Science.gov (United States)

    Baek, Seungwon

    2018-06-01

    We propose a local U(1) Lμ -Lτ model to explain b → sμ+μ- anomaly observed at the LHCb and Belle experiments. The model also has a natural dark matter candidate N. We introduce SU(2)L-doublet colored scalar q ˜ to mediate b → s transition at one-loop level. The U(1) Lμ -Lτ gauge symmetry is broken spontaneously by the scalar S. All the new particles are charged under U(1) Lμ -Lτ. We can obtain C9μ , NP ∼ - 1 to solve the b → sμ+μ- anomaly and can explain the correct dark matter relic density of the universe, ΩDMh2 ≈ 0.12, simultaneously, while evading constraints from electroweak precision tests, neutrino trident experiments and other quark flavor-changing loop processes such as b → sγ and Bs -B‾s mixing. Our model can be tested by searching for Z‧ and new colored scalar at the LHC and B →K* ν ν ‾ process at Belle-II.

  2. The hadronic standard model for strong and electroweak interactions

    International Nuclear Information System (INIS)

    Raczka, R.

    1993-01-01

    We propose a new model for strong and electro-weak interactions. First, we review various QCD predictions for hadron-hadron and lepton-hadron processes. We indicate that the present formulation of strong interactions in the frame work of Quantum Chromodynamics encounters serious conceptual and numerical difficulties in a reliable description of hadron-hadron and lepton-hadron interactions. Next we propose to replace the strong sector of Standard Model based on unobserved quarks and gluons by the strong sector based on the set of the observed baryons and mesons determined by the spontaneously broken SU(6) gauge field theory model. We analyse various properties of this model such as asymptotic freedom, Reggeization of gauge bosons and fundamental fermions, baryon-baryon and meson-baryon high energy scattering, generation of Λ-polarization in inclusive processes and others. Finally we extend this model by electro-weak sector. We demonstrate a remarkable lepton and hadron anomaly cancellation and we analyse a series of important lepton-hadron and hadron-hadron processes such as e + + e - → hadrons, e + + e - → W + + W - , e + + e - → p + anti-p, e + p → e + p and p + anti-p → p + anti-p processes. We obtained a series of interesting new predictions in this model especially for processes with polarized particles. We estimated the value of the strong coupling constant α(M z ) and we predicted the top baryon mass M Λ t ≅ 240 GeV. Since in our model the proton, neutron, Λ-particles, vector mesons like ρ, ω, φ, J/ψ ect. and leptons are elementary most of experimentally analysed lepton-hadron and hadron-hadron processes in LEP1, LEP2, LEAR, HERA, HERMES, LHC and SSC experiments may be relatively easily analysed in our model. (author). 252 refs, 65 figs, 1 tab

  3. Dispersion Relations for Electroweak Observables in Composite Higgs Models

    CERN Document Server

    Contino, Roberto

    2015-12-14

    We derive dispersion relations for the electroweak oblique observables measured at LEP in the context of $SO(5)/SO(4)$ composite Higgs models. It is shown how these relations can be used and must be modified when modeling the spectral functions through a low-energy effective description of the strong dynamics. The dispersion relation for the parameter $\\epsilon_3$ is then used to estimate the contribution from spin-1 resonances at the 1-loop level. Finally, it is shown that the sign of the contribution to the $\\hat S$ parameter from the lowest-lying spin-1 states is not necessarily positive definite, but depends on the energy scale at which the asymptotic behavior of current correlators is attained.

  4. Electroweak symmetry breaking in supersymmetric models with heavy scalar superpartners

    International Nuclear Information System (INIS)

    Chankowski, Piotr H.; Falkowski, Adam; Pokorski, Stefan; Wagner, Jakub

    2004-01-01

    We propose a novel mechanism of electroweak symmetry breaking in supersymmetric models, as the one recently discussed by Birkedal, Chacko and Gaillard, in which the Standard Model Higgs doublet is a pseudo-Goldstone boson of some global symmetry. The Higgs mass parameter is generated at one-loop level by two different, moderately fine-tuned sources of the global symmetry breaking. The mechanism works for scalar superpartner masses of order 10 TeV, but gauginos can be light. The scale at which supersymmetry breaking is mediated to the visible sector has to be low, of order 100 TeV. Fine-tuning in the scalar potential is at least two orders of magnitude smaller than in the MSSM with similar soft scalar masses. The physical Higgs boson mass is (for tanβ >> 1) in the range 120-135 GeV

  5. Dark Matter candidate in Inert Doublet Model with additional local gauge symmetry U (1)

    International Nuclear Information System (INIS)

    Gaitán, R.; De Oca, J.H. Montes; Garcés, E. A.; Cabral-Rosetti, L. G.

    2016-01-01

    We consider the Inert Doublet Model (IDM) with an additional local gauge symmetry U (1) and a complex singlet scalar to break the symmetry U (1). The continuous symmetry U (1) is introduced to control the CP-conserving interaction instead of some discrete symmetries as usually. We present the mass spectrum for neutral scalar and gauge bosons and the values of the charges under U (1) for which the model could have a candidate to dark matter. (paper)

  6. Electroweak Physics

    OpenAIRE

    Hollik, W.

    2005-01-01

    The status of precision electroweak measurements as of summer 2002 is reviewed. The recent results on the anomalous magnetic moment of the muon and on neutrino-nucleon scattering are discussed. Precision results on the electroweak interaction obtained by the experiments at the SLC, LEP and TEVATRON colliders are presented. The experimental results are compared with the predictions of the minimal Standard Model and are used to constrain its parameters, including the mass of the Higgs boson. Th...

  7. Aspects of radiative electroweak breaking in supergravity models

    International Nuclear Information System (INIS)

    Kelley, S.; Lopez, J.L.; Nanopoulos, D.V.; Pois, H.; Yuan, K.

    1993-01-01

    We discuss several aspects of state-of-the-art calculations of radiative electroweak symmetry breaking in supergravity models. These models have a five-dimensional parameter space in contrast with the 21-dimensional one of the MSSM. We examine the Higgs one-loop effective potential V 1 =V 0 +ΔV, in particular how its renormalization-scale (Q) independence is affected by the approximation used to calculate ΔV and by the presence of a Higgs-field-independent term which makes V 1 (0)≠0. We show that the latter must be subtracted out to achieve Q-independence. We also discuss our own approach to the exploration of the five-dimensional parameter space and the fine-tuning constraints within this approach. We apply our methods to the determination of the allowed region in parameter space of two models which we argue to be the prototypes for conventional (SSM) and string (SISM) unified models. To this end we impose the electroweak breaking constraint by minimizing the one-loop effective potential and study the shifts in μ and B relative to the values obtained using the tree-level potential. These shifts are most significant for small values of μ and B, and induce corresponding shifts on the lightest μ- and/or B-dependent particle masses, i.e., those of the lightest stau, neutralino, chargino, and Higgs boson states. Finally, we discuss the predictions for the squark, slepton, and one-loop corrected Higgs boson masses. (orig.)

  8. Survey of composite particle models of electroweak interaction

    International Nuclear Information System (INIS)

    Suzuki, Mahiko.

    1992-05-01

    Models of composite weak bosons, the top-condensate model of electroweak interaction and related models we surveyed. Composite weak bosons must be tightly bound with a high compositeness scale in order to generate approximate puge symmetry dynamically. However, naturalness argument suggests that the compositeness scale is low at least in toy models. In the top-condensate model, where a composite Higgs doublet is formed with a very high scale, the prediction of the model is insensitive to details of the model and almost model-independent Actually, the numerical prediction of the t-quark and Higgs boson masses does not test compositeness of the Higgs boson nor condensation of the t-quark field. To illustrate the point, a composite t R -quark model is discussed which leads to the same numerical prediction as the top-condensate model. However, different constraints an imposed on the structure of the Higgs sector, depending on which particles are composite. The attempt to account the large t-b mass splitting by the high compositeness scale of the top-condensate model is reinterpreted in terms of fine tuning of more than one vacuum expectation value. It is difficult to lower, without a fourth generation, the t-quark mass in the composite particle models in general because the Yukawa coupling of the i-quark to the Higgs boson, t2 /4π = 0.1 for m t = 200 GeV, is too small for a coupling of a composite particle

  9. Gaugino radiative decay in an anomalous U(1)' model

    International Nuclear Information System (INIS)

    Lionetto, Andrea; Racioppi, Antonio

    2010-01-01

    We study the neutralino radiative decay into the lightest supersymmetric particle (LSP) in the framework of a minimal anomalous U(1) ' extension of the MSSM. It turns out that in a suitable decoupling limit the axino, which is present in the Stueckelberg multiplet, is the LSP. We compute the branching ratio (BR) for the decay of a neutralino into an axino and a photon. We find that in a wide region of the parameter space, the BR is higher than 93% in contrast with the typical value (≤1%) in the CMSSM.

  10. The hadronic standard model for strong and electroweak interactions

    Energy Technology Data Exchange (ETDEWEB)

    Raczka, R. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)

    1993-12-31

    We propose a new model for strong and electro-weak interactions. First, we review various QCD predictions for hadron-hadron and lepton-hadron processes. We indicate that the present formulation of strong interactions in the frame work of Quantum Chromodynamics encounters serious conceptual and numerical difficulties in a reliable description of hadron-hadron and lepton-hadron interactions. Next we propose to replace the strong sector of Standard Model based on unobserved quarks and gluons by the strong sector based on the set of the observed baryons and mesons determined by the spontaneously broken SU(6) gauge field theory model. We analyse various properties of this model such as asymptotic freedom, Reggeization of gauge bosons and fundamental fermions, baryon-baryon and meson-baryon high energy scattering, generation of {Lambda}-polarization in inclusive processes and others. Finally we extend this model by electro-weak sector. We demonstrate a remarkable lepton and hadron anomaly cancellation and we analyse a series of important lepton-hadron and hadron-hadron processes such as e{sup +} + e{sup -} {yields} hadrons, e{sup +} + e{sup -} {yields} W{sup +} + W{sup -}, e{sup +} + e{sup -} {yields} p + anti-p, e + p {yields} e + p and p + anti-p {yields} p + anti-p processes. We obtained a series of interesting new predictions in this model especially for processes with polarized particles. We estimated the value of the strong coupling constant {alpha}(M{sub z}) and we predicted the top baryon mass M{sub {Lambda}{sub t}} {approx_equal} 240 GeV. Since in our model the proton, neutron, {Lambda}-particles, vector mesons like {rho}, {omega}, {phi}, J/{psi} ect. and leptons are elementary most of experimentally analysed lepton-hadron and hadron-hadron processes in LEP1, LEP2, LEAR, HERA, HERMES, LHC and SSC experiments may be relatively easily analysed in our model. (author). 252 refs, 65 figs, 1 tab.

  11. The hadronic standard model for strong and electroweak interactions

    Energy Technology Data Exchange (ETDEWEB)

    Raczka, R [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)

    1994-12-31

    We propose a new model for strong and electro-weak interactions. First, we review various QCD predictions for hadron-hadron and lepton-hadron processes. We indicate that the present formulation of strong interactions in the frame work of Quantum Chromodynamics encounters serious conceptual and numerical difficulties in a reliable description of hadron-hadron and lepton-hadron interactions. Next we propose to replace the strong sector of Standard Model based on unobserved quarks and gluons by the strong sector based on the set of the observed baryons and mesons determined by the spontaneously broken SU(6) gauge field theory model. We analyse various properties of this model such as asymptotic freedom, Reggeization of gauge bosons and fundamental fermions, baryon-baryon and meson-baryon high energy scattering, generation of {Lambda}-polarization in inclusive processes and others. Finally we extend this model by electro-weak sector. We demonstrate a remarkable lepton and hadron anomaly cancellation and we analyse a series of important lepton-hadron and hadron-hadron processes such as e{sup +} + e{sup -} {yields} hadrons, e{sup +} + e{sup -} {yields} W{sup +} + W{sup -}, e{sup +} + e{sup -} {yields} p + anti-p, e + p {yields} e + p and p + anti-p {yields} p + anti-p processes. We obtained a series of interesting new predictions in this model especially for processes with polarized particles. We estimated the value of the strong coupling constant {alpha}(M{sub z}) and we predicted the top baryon mass M{sub {Lambda}{sub t}} {approx_equal} 240 GeV. Since in our model the proton, neutron, {Lambda}-particles, vector mesons like {rho}, {omega}, {phi}, J/{psi} ect. and leptons are elementary most of experimentally analysed lepton-hadron and hadron-hadron processes in LEP1, LEP2, LEAR, HERA, HERMES, LHC and SSC experiments may be relatively easily analysed in our model. (author). 252 refs, 65 figs, 1 tab.

  12. Electroweak baryogenesis in extensions of the standard model

    Energy Technology Data Exchange (ETDEWEB)

    Fromme, L.

    2006-07-07

    We investigate the generation of the baryon asymmetry in two extensions of the Standard Model; these are the {phi}{sup 6} and the two-Higgs-doublet model. Analyzing the thermal potential in the presence of CP violation, we find a strong first order phase transition for a wide range of parameters in both models. We compute the relevant bubble wall properties which then enter the transport equations. In non-supersymmetric models electroweak baryogenesis is dominated by top transport, which we treat in the WKB approximation. We calculate the CP-violating source terms starting from the Dirac equation. We show how to resolve discrepancies between this treatment and the computation in the Schwinger-Keldysh formalism. Furthermore, we keep inelastic scatterings of quarks and W bosons at a finite rate, which considerably affects the amount of the generated baryon asymmetry depending on the bubble wall velocity. In addition, we improve the transport equations by novel source terms which are generated by CP-conserving perturbations in the plasma. It turns out that their effect is relatively small. Both models under consideration predict a baryon to entropy ratio close to the observed value for a large part of the parameter space without being in conflict with constraints on electric dipole moments. (orig.)

  13. Electroweak baryogenesis in extensions of the standard model

    International Nuclear Information System (INIS)

    Fromme, L.

    2006-01-01

    We investigate the generation of the baryon asymmetry in two extensions of the Standard Model; these are the Φ 6 and the two-Higgs-doublet model. Analyzing the thermal potential in the presence of CP violation, we find a strong first order phase transition for a wide range of parameters in both models. We compute the relevant bubble wall properties which then enter the transport equations. In non-supersymmetric models electroweak baryogenesis is dominated by top transport, which we treat in the WKB approximation. We calculate the CP-violating source terms starting from the Dirac equation. We show how to resolve discrepancies between this treatment and the computation in the Schwinger-Keldysh formalism. Furthermore, we keep inelastic scatterings of quarks and W bosons at a finite rate, which considerably affects the amount of the generated baryon asymmetry depending on the bubble wall velocity. In addition, we improve the transport equations by novel source terms which are generated by CP-conserving perturbations in the plasma. It turns out that their effect is relatively small. Both models under consideration predict a baryon to entropy ratio close to the observed value for a large part of the parameter space without being in conflict with constraints on electric dipole moments. (orig.)

  14. The electroweak phase transition in models with gauge singlets

    International Nuclear Information System (INIS)

    Ahriche, A.

    2007-01-01

    A strong first order phase transition is needed for generating the baryon asymmetry; and also to save it during the electroweak phase transition (EWPT). However this condition is not fulfilled within the Standard Model (SM), but in its extensions. It is widely believed that the existence of singlet scalars in some Standard Model extensions can easily make the EWPT strongly first order. In this work, we will examine the strength of the EWPT in the simplest extension of the SM with a real gauge singlet using the sphaleron energy at the critical temperature. We find that the phase transition is stronger by adding a singlet; and also that the criterion for a strong phase transition Ω(T c )/T c >or similar 1, where Ω = (v 2 + (x - x 0 ) 2 ) ( 1)/(2) and x(x 0 ) is the singlet vacuum expectation value in the broken (symmetric) phase, is not valid for models containing singlets, even though often used in the literature. The usual condition v c /T c >or similar 1 is more meaningful, and it is satisfied for the major part of the parameter space for physically allowed Higgs masses. Then it is convenient to study the EWPT in models with singlets that couple only to the Higgs doublets, by replacing the singlets by their vevs. (orig.)

  15. The electroweak phase transition in models with gauge singlets

    Energy Technology Data Exchange (ETDEWEB)

    Ahriche, A.

    2007-04-18

    A strong first order phase transition is needed for generating the baryon asymmetry; and also to save it during the electroweak phase transition (EWPT). However this condition is not fulfilled within the Standard Model (SM), but in its extensions. It is widely believed that the existence of singlet scalars in some Standard Model extensions can easily make the EWPT strongly first order. In this work, we will examine the strength of the EWPT in the simplest extension of the SM with a real gauge singlet using the sphaleron energy at the critical temperature. We find that the phase transition is stronger by adding a singlet; and also that the criterion for a strong phase transition {omega}(T{sub c})/T{sub c} >or similar 1, where {omega} = (v{sup 2} + (x - x{sub 0}){sup 2}){sup (}1)/(2) and x(x{sub 0}) is the singlet vacuum expectation value in the broken (symmetric) phase, is not valid for models containing singlets, even though often used in the literature. The usual condition v{sub c}/T{sub c} >or similar 1 is more meaningful, and it is satisfied for the major part of the parameter space for physically allowed Higgs masses. Then it is convenient to study the EWPT in models with singlets that couple only to the Higgs doublets, by replacing the singlets by their vevs. (orig.)

  16. Revisiting the Global Electroweak Fit of the Standard Model and Beyond with Gfitter

    CERN Document Server

    Flächer, Henning; Haller, J; Höcker, A; Mönig, K; Stelzer, J

    2009-01-01

    The global fit of the Standard Model to electroweak precision data, routinely performed by the LEP electroweak working group and others, demonstrated impressively the predictive power of electroweak unification and quantum loop corrections. We have revisited this fit in view of (i) the development of the new generic fitting package, Gfitter, allowing flexible and efficient model testing in high-energy physics, (ii) the insertion of constraints from direct Higgs searches at LEP and the Tevatron, and (iii) a more thorough statistical interpretation of the results. Gfitter is a modular fitting toolkit, which features predictive theoretical models as independent plugins, and a statistical analysis of the fit results using toy Monte Carlo techniques. The state-of-the-art electroweak Standard Model is fully implemented, as well as generic extensions to it. Theoretical uncertainties are explicitly included in the fit through scale parameters varying within given error ranges. This paper introduces the Gfitter projec...

  17. Electroweak phase transition in an extension of the standard model with scalar color octet

    International Nuclear Information System (INIS)

    Ham, S. W.; Shim, Seong-A; Oh, S. K.

    2010-01-01

    In an extension of the standard model with a scalar color octet, the possibility of the strongly first-order electroweak phase transition is studied by examining the finite-temperature effective Higgs potential at the one-loop level. It is found that there are wide regions in the parameter space that allow the strongly first-order electroweak phase transition, where the Higgs boson mass is larger than the experimental lower bound of 115 GeV, and the masses of the scalar color octet is around 200 GeV. The parameter regions may be explored at the LHC with respect to the electroweak phase transition.

  18. Electroweak precision observables in the minimal supersymmetric standard model

    International Nuclear Information System (INIS)

    Heinemeyer, S.; Hollik, W.; Weiglein, G.

    2006-01-01

    The current status of electroweak precision observables in the Minimal Supersymmetric Standard Model (MSSM) is reviewed. We focus in particular on the W boson mass, M W , the effective leptonic weak mixing angle, sin 2 θ eff , the anomalous magnetic moment of the muon (g-2) μ , and the lightest CP-even MSSM Higgs boson mass, m h . We summarize the current experimental situation and the status of the theoretical evaluations. An estimate of the current theoretical uncertainties from unknown higher-order corrections and from the experimental errors of the input parameters is given. We discuss future prospects for both the experimental accuracies and the precision of the theoretical predictions. Confronting the precision data with the theory predictions within the unconstrained MSSM and within specific SUSY-breaking scenarios, we analyse how well the data are described by the theory. The mSUGRA scenario with cosmological constraints yields a very good fit to the data, showing a clear preference for a relatively light mass scale of the SUSY particles. The constraints on the parameter space from the precision data are discussed, and it is shown that the prospective accuracy at the next generation of colliders will enhance the sensitivity of the precision tests very significantly

  19. Electroweak baryogenesis

    International Nuclear Information System (INIS)

    Trodden, Mark

    1999-01-01

    Contrary to naive cosmological expectations, all evidence suggests that the universe contains an abundance of matter over antimatter. This article reviews the currently popular scenario in which testable physics, present in the standard model of electroweak interactions and its modest extensions, is responsible for this fundamental cosmological datum. A pedagogical explanation of the motivations and physics behind electroweak baryogenesis is provided, and analytical approaches, numerical studies, up to date developments, and open questions in the field are also discussed. (c) 1999 The American Physical Society

  20. Naturally light neutrinos in the flipped SU(5)xU(1) superstring model

    Energy Technology Data Exchange (ETDEWEB)

    Antoniadis, I.; Rizos, J. (Centre de Physique Theorique, Ecole Polytechnique, 91 - Palaiseau (France)); Tamvakis, K. (Physics Dept., Univ. Ioannina (Greece))

    1992-04-16

    We analyze the SU(5)xU(1)'xU(1){sup 4}xSO(10)xSU(4) superstring model, taking into account non-renormalizable superpotential interactions up to sixth order, and find that all neutrinos stay naturally light within the experimental mass bounds. (orig.).

  1. Baryon number generation in a flipped SU(5) x U(1) model

    International Nuclear Information System (INIS)

    Campbell, B.; Hagelin, J.; Nanopoulos, D.V.; Olive, K.A.

    1988-01-01

    We consider the possibilities for generating a baryon asymmetry in the early universe in a flipped SU(5) x U(1) model inspired by the superstring. Depending on the temperature of the radiation background after inflation we can distinguish between two scenarios for baryogenesis: (1) After reheating the original SU(5) x U(1) symmetry is restored, or there was no inflation at all; (2) reheating after inflation is rather weak and SU(5) x U(1) is broken. In either case the asymmetry is generated by the out-of-equilibrium decays of a massive SU(3) x SU(2) x U(1) singlet field φ m . In the flipped SU(5) x U(1) model, gauge symmetry breaking is triggered by strong coupling phenomena, and is in general accompanied by the production of entropy. We examine constraints on the reheating temperature and the strong coupling scale in each of the scenarios. (orig.)

  2. The electroweak theory

    International Nuclear Information System (INIS)

    Chris Quigg

    2001-01-01

    After a short essay on the current state of particle physics, the author reviews the antecedents of the modern picture of the weak and electromagnetic interactions and then undertakes a brief survey of the SU(2) L (circle-times) U(1) Y electroweak theory. The authors reviews the features of electroweak phenomenology at tree level and beyond, presents an introduction to the Higgs boson and the 1-TeV scale, and examines arguments for enlarging the electroweak theory. The author concludes with a brief look at low-scale gravity

  3. Matrix models from localization of five-dimensional supersymmetric noncommutative U(1) gauge theory

    International Nuclear Information System (INIS)

    Lee, Bum-Hoon; Ro, Daeho; Yang, Hyun Seok

    2017-01-01

    We study localization of five-dimensional supersymmetric U(1) gauge theory on S 3 ×ℝ θ 2 where ℝ θ 2 is a noncommutative (NC) plane. The theory can be isomorphically mapped to three-dimensional supersymmetric U(N→∞) gauge theory on S 3 using the matrix representation on a separable Hilbert space on which NC fields linearly act. Therefore the NC space ℝ θ 2 allows for a flexible path to derive matrix models via localization from a higher-dimensional supersymmetric NC U(1) gauge theory. The result shows a rich duality between NC U(1) gauge theories and large N matrix models in various dimensions.

  4. Electroweak chiral Lagrangian from a natural topcolor-assisted technicolor model

    International Nuclear Information System (INIS)

    Lang Junyi; Jiang Shaozhou; Wang Qing

    2009-01-01

    Based on previous studies on computing coefficients of the electroweak chiral Lagrangian from C. T. Hill's schematic topcolor-assisted technicolor model, we generalize the calculation to K. Lane's prototype natural topcolor-assisted technicolor model. We find that typical features of the model are qualitatively similar to those of Hill's, but Lane's model prefers a smaller technicolor group and the Z ' mass must be smaller than 400 GeV. Furthermore, the S parameter is around the order of +1, mainly due to the existence of three doublets of techniquarks. We obtain the values for all coefficients of the electroweak chiral Lagrangian up to the order p 4 . Apart from large negative four-fermion coupling values, the extended technicolor impacts on the electroweak chiral Lagrangian coefficients are small, since the techniquark self energy, which determines these coefficients, in general receives almost no influence from the extended technicolor induced four-fermion interactions except for its large momentum tail.

  5. Spin Tests of 1/20-Scale Models of the Chance Vought Revised XF6U-1 and F6U-1 Airplanes, TED No. NACA 2390

    Science.gov (United States)

    Klinar, Walter J.; Berman, Theodore

    1948-01-01

    An investigation has been conducted in the Langley 20-foot free-spinning tunnel on the 1/20-scale model of the Chance Vought XF6U-1 airplane altered to represent the XF6U-1 airplane as it will be spin-tested in flight, and also altered to represent the F6U-1 airplane as it will be produced for service use. Spin tests were made to determine the effects of control settings and movements at the normal loading. The results show that the spins obtained on the revised XF6U-1 airplane will be oscillatory in roll and yaw and that recoveries by rudder reversal will be rapid. Model test results indicate that the F6U-1 airplane will probably not spin. Inasmuch as the results of this investigation show that the new designs are as good as or better than the original XF6U-1 design in regard to spin recovery, it is felt that the conclusions and recommendations reached for the original design can be applied to the new designs for all loading conditions.

  6. Dark matter and electroweak phase transition in the mixed scalar dark matter model

    Science.gov (United States)

    Liu, Xuewen; Bian, Ligong

    2018-03-01

    We study the electroweak phase transition in the framework of the scalar singlet-doublet mixed dark matter model, in which the particle dark matter candidate is the lightest neutral Higgs that comprises the C P -even component of the inert doublet and a singlet scalar. The dark matter can be dominated by the inert doublet or singlet scalar depending on the mixing. We present several benchmark models to investigate the two situations after imposing several theoretical and experimental constraints. An additional singlet scalar and the inert doublet drive the electroweak phase transition to be strongly first order. A strong first-order electroweak phase transition and a viable dark matter candidate can be accomplished in two benchmark models simultaneously, for which a proper mass splitting among the neutral and charged Higgs masses is needed.

  7. Gauge Group Contraction of Electroweak Model and its Natural Energy Limits

    Directory of Open Access Journals (Sweden)

    Nikolai A. Gromov

    2015-09-01

    Full Text Available The low and higher energy limits of the Electroweak Model are obtained from first principles of gauge theory. Both limits are given by the same contraction of the gauge group, but for the different consistent rescalings of the field space. Mathematical contraction parameter in both cases is interpreted as energy. The very weak neutrino-matter interaction is explained by zero tending contraction parameter, which depends on neutrino energy. The second consistent rescaling corresponds to the higher energy limit of the Electroweak Model. At the infinite energy all particles lose masses, electroweak interactions become long-range and are mediated by the neutral currents. The limit model represents the development of the early Universe from the Big Bang up to the end of the first second.

  8. Natural limits of electroweak model as contraction of its gauge group

    International Nuclear Information System (INIS)

    Gromov, N A

    2015-01-01

    The low and higher energy limits of the electroweak model are obtained from the first principles of gauge theory. Both limits are given by the same contraction of the gauge group, but for the different consistent rescalings of the field space. Mathematical contraction parameter in both cases is interpreted as energy. Very weak neutrino–matter interactions are explained by zero tending contraction parameter, which depends on neutrino energy. The second consistent rescaling corresponds to the higher energy limit of the electroweak model. At the infinite energy all particles lose mass, electroweak interactions become long-range and are mediated by neutral currents. The limit model represents the development of the early Universe from the big bang up to the end of the first second. (paper)

  9. Exploring the supersymmetric U(1 ) B -L×U(1 ) R model with dark matter, muon g - 2 , and Z' mass limits

    Science.gov (United States)

    Frank, Mariana; Özdal, Özer

    2018-01-01

    We study the low scale predictions of the supersymmetric standard model extended by U (1 )B -L×U (1 )R symmetry, obtained from S O (10 ) breaking via a left-right supersymmetric model, imposing universal boundary conditions. Two singlet Higgs fields are responsible for the radiative U (1 )B -L×U (1 )R symmetry breaking, and a singlet fermion S is introduced to generate neutrino masses through an inverse seesaw mechanism. The lightest neutralino or sneutrino emerge as dark matter candidates, with different low scale implications. We find that the composition of the neutralino lightest supersymmetric particle (LSP) changes considerably depending on the neutralino LSP mass, from roughly half U (1 )R bino, half minimal supersymmetric model (MSSM) bino, to a singlet higgsino, or completely dominated by the MSSM higgsino. The sneutrino LSP is statistically much less likely, and when it occurs it is a 50-50 mixture of right-handed sneutrino and the scalar S ˜. Most of the solutions consistent with the relic density constraint survive the XENON 1T exclusion curve for both LSP cases. We compare the two scenarios and investigate parameter space points and find consistency with the muon anomalous magnetic moment only at the edge of a 2 σ deviation from the measured value. However, we find that the sneutrino LSP solutions could be ruled out completely by the strict reinforcement of the recent Z' mass bounds. We finally discuss collider prospects for testing the model.

  10. Prediction of the Cabibbo angle in the vector model for electroweak interactions

    International Nuclear Information System (INIS)

    Reifler, F.; Morris, R.

    1985-01-01

    In a recent paper we presented a vector model for the electroweak interactions which is similar to the Weinberg--Salam model but differs in the following features. (1) In the vector model all fermion wave functions are bispinors or equivalently isotropic Yang--Mills triplets (as opposed to a state vector composed of a spinor and bispinors in the Weinberg--Salam model). Particles are distinguished by their Higgs fields. (2) The vector model predicts that sin 2 theta/sub W/ = 1/4 , where theta/sub W/ is the Weinberg angle. (3) The vector model accounts for conservation of lepton number, electric charge, and baryon number. (4) In the vector model an antiparticle is characterized by opposite lepton number, electric charge, and baryon number; yet both particles and antiparticles propagate forward in time with positive energies. In this paper we extend the vector theory to include interactions between fermions and the gauge bosons mediating the electroweak force. We model the bosons as Yang--Mills fields with their own Higgs fields. We further propose a specific configuration of Higgs fields for the u,d,s, and c quarks. With these features, the model accounts for electroweak transitions of quarks and leptons and predicts that cos theta/sub C/ = 0.9744, where theta/sub C/ is the Cabibbo angle. We further show that the vector model accounts for the intrinsic parity of particles and antiparticles, and parity violations and CPT invariance for electroweak interactions

  11. Phenomenology of an SU(2)×SU(2)×U(1) model with lepton-flavour non-universality

    Energy Technology Data Exchange (ETDEWEB)

    Boucenna, Sofiane M. [Laboratori Nazionali di Frascati, INFN,Via Enrico Fermi 40, 100044 Frascati (Italy); Celis, Alejandro [Arnold Sommerfeld Center for Theoretical Physics, Fakultät für Physik,Ludwig-Maximilians-Universität München,Theresienstrasse 37, 80333 München (Germany); Fuentes-Martín, Javier; Vicente, Avelino [Instituto de Física Corpuscular, Universitat de València - CSIC,E-46071 València (Spain); Virto, Javier [Albert Einstein Center for Fundamental Physics,Institute for Theoretical Physics, University of Bern,CH-3012 Bern (Switzerland)

    2016-12-14

    We investigate a gauge extension of the Standard Model in light of the observed hints of lepton universality violation in b→cℓν and b→sℓ{sup +}ℓ{sup −} decays at BaBar, Belle and LHCb. The model consists of an extended gauge group SU(2){sub 1}×SU(2){sub 2}×U(1){sub Y} which breaks spontaneously around the TeV scale to the electroweak gauge group. Fermion mixing effects with vector-like fermions give rise to potentially large new physics contributions in flavour transitions mediated by W{sup ′} and Z{sup ′} bosons. This model can ease tensions in B-physics data while satisfying stringent bounds from flavour physics, and electroweak precision data. Possible ways to test the proposed new physics scenario with upcoming experimental measurements are discussed. Among other predictions, the ratios R{sub M}=Γ(B→Mμ{sup +}μ{sup −})/Γ(B→Me{sup +}e{sup −}), with M=K{sup ∗},ϕ, are found to be reduced with respect to the Standard Model expectation R{sub M}≃1.

  12. Gfitter - Revisiting the global electroweak fit of the Standard Model and beyond

    Energy Technology Data Exchange (ETDEWEB)

    Flaecher, H.; Hoecker, A. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Goebel, M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)]|[Hamburg Univ. (Germany). Inst. fuer Experimentalphysik; Haller, J. [Hamburg Univ. (Germany). Inst. fuer Experimentalphysik; Moenig, K.; Stelzer, J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2008-11-15

    The global fit of the Standard Model to electroweak precision data, routinely performed by the LEP electroweak working group and others, demonstrated impressively the predictive power of electroweak unification and quantum loop corrections. We have revisited this fit in view of (i) the development of the new generic fitting package, Gfitter, allowing flexible and efficient model testing in high-energy physics, (ii) the insertion of constraints from direct Higgs searches at LEP and the Tevatron, and (iii) a more thorough statistical interpretation of the results. Gfitter is a modular fitting toolkit, which features predictive theoretical models as independent plugins, and a statistical analysis of the fit results using toy Monte Carlo techniques. The state-of-the-art electroweak Standard Model is fully implemented, as well as generic extensions to it. Theoretical uncertainties are explicitly included in the fit through scale parameters varying within given error ranges. This paper introduces the Gfitter project, and presents state-of-the-art results for the global electroweak fit in the Standard Model, and for a model with an extended Higgs sector (2HDM). Numerical and graphical results for fits with and without including the constraints from the direct Higgs searches at LEP and Tevatron are given. Perspectives for future colliders are analysed and discussed. Including the direct Higgs searches, we find M{sub H}=116.4{sup +18.3}{sub -1.3} GeV, and the 2{sigma} and 3{sigma} allowed regions [114,145] GeV and [[113,168] and [180,225

  13. Electromagnetic mass differences in the SU(3) x U(1) gauge model

    International Nuclear Information System (INIS)

    Maharana, K.; Sastry, C.V.

    1975-01-01

    In this note we point out that the electromagnetic mass differences of the pion and kaon in the SU(3) times U(1) model are the same as in Weinberg's model except for the differences in the masses of the gauge bosons

  14. Dark Gauge U(1) symmetry for an alternative left-right model

    Science.gov (United States)

    Kownacki, Corey; Ma, Ernest; Pollard, Nicholas; Popov, Oleg; Zakeri, Mohammadreza

    2018-02-01

    An alternative left-right model of quarks and leptons, where the SU(2)_R lepton doublet (ν ,l)_R is replaced with (n,l)_R so that n_R is not the Dirac mass partner of ν _L, has been known since 1987. Previous versions assumed a global U(1)_S symmetry to allow n to be identified as a dark-matter fermion. We propose here a gauge extension by the addition of extra fermions to render the model free of gauge anomalies, and just one singlet scalar to break U(1)_S. This results in two layers of dark matter, one hidden behind the other.

  15. Higgs phenomenology in the minimal S U (3 )L×U (1 )X model

    Science.gov (United States)

    Okada, Hiroshi; Okada, Nobuchika; Orikasa, Yuta; Yagyu, Kei

    2016-07-01

    We investigate the phenomenology of a model based on the S U (3 )c×S U (3 )L×U (1 )X gauge theory, the so-called 331 model. In particular, we focus on the Higgs sector of the model which is composed of three S U (3 )L triplet Higgs fields and is the minimal form for realizing a phenomenologically acceptable scenario. After the spontaneous symmetry breaking S U (3 )L×U (1 )X→S U (2 )L×U (1 )Y , our Higgs sector effectively becomes that with two S U (2 )L doublet scalar fields, in which the first- and the second-generation quarks couple to a different Higgs doublet from that which couples to the third-generation quarks. This structure causes the flavor-changing neutral current mediated by Higgs bosons at the tree level. By taking an alignment limit of the mass matrix for the C P -even Higgs bosons, which is naturally realized in the case with the breaking scale of S U (3 )L×U (1 )X much larger than that of S U (2 )L×U (1 )Y, we can avoid current constraints from flavor experiments such as the B0-B¯ 0 mixing even for the Higgs bosons masses that are O (100 ) GeV . In this allowed parameter space, we clarify that a characteristic deviation in quark Yukawa couplings of the Standard Model-like Higgs boson is predicted, which has a different pattern from that seen in two Higgs doublet models with a softly broken Z2 symmetry. We also find that the flavor-violating decay modes of the extra Higgs boson, e.g., H /A →t c and H±→t s , can be dominant, and they yield the important signature to distinguish our model from the two Higgs doublet models.

  16. Deep-inelastic lepton scattering in an SU(3) x U(1) gauge model

    International Nuclear Information System (INIS)

    Maharana, K.; Sastry, C.V.

    1976-01-01

    Linear relations and sum rules for deep-inelastic lepton scattering are derived in the light-cone algebra approach from a set of weak, neutral, and electromagnetic currents based on an SU(3) x U(1) gauge model proposed by Schechter and Ueda

  17. Duality in the U(1) Higgs model with an external field

    International Nuclear Information System (INIS)

    Damgaard, P.H.

    1988-07-01

    An external electromagnetic field is coupled to the lattice U(1) Higgs model in a Villain form. Duality transformations are then used to express the partition function in terms of an effective Lagrangian of topological excitations and their couplings to the external field. Consequences for the phase diagram are derived. (orig.)

  18. Electroweak baryogenesis with primordial hypermagnetic fields

    International Nuclear Information System (INIS)

    Ayala, Alejandro; Pallares, Gabriel; Besprosvany, Jaime; Piccinelli, Gabriella

    2002-01-01

    Primordial magnetic fields, independently of their origin, could have had a significant influence over several physical processes that took place during the evolution of the early universe, in particular baryogenesis. Recall that for temperatures above the electroweak phase transition (T > 100 GeV), the symmetry of the standard model corresponded to the U(1)y hypercharge group, instead of the U(1)em electromagnetic group and are therefore properly called hypermagnetic fields. In this work, we show that during a first order electroweak phase transition, the presence of hypermagnetic fields produces an axial charge segregation in the reflection and transmission of fermions off the true vacuum bubbles. We also comment on the possible consequences that these processes have for the generation of baryon number during the phase transition

  19. Flipped SU(5)xU(1){sub X} models from F-theory

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Jing [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Li Tianjun, E-mail: tjli@physics.rutgers.ed [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States); Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China); Nanopoulos, Dimitri V. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States); Astroparticle Physics Group, Houston Advanced Research Center (HARC), Mitchell Campus, Woodlands, TX 77381 (United States); Academy of Athens, Division of Natural Sciences, 28 Panepistimiou Avenue, Athens 10679 (Greece); Xie Dan [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States)

    2010-05-01

    We systematically construct flipped SU(5)xU(1){sub X} models without and with bulk vector-like particles from F-theory. To realize the decoupling scenario, we introduce sets of vector-like particles in complete SU(5)xU(1) multiplets at the TeV scale, or at the intermediate scale, or at the TeV scale and high scale. To avoid the Landau pole problem for the gauge couplings, we can only introduce five sets of vector-like particles around the TeV scale. These vector-like particles can couple to the Standard Model singlet fields, and obtain suitable masses by Higgs mechanism. We study gauge coupling unification in detail. We show that the U(1){sub X} flux contributions to the gauge couplings preserve the SU(5)xU(1){sub X} gauge coupling unification. We calculate the SU(3){sub C}xSU(2){sub L} unification scales, and the SU(5)xU(1){sub X} unification scales and unified couplings. In most of our models, the high-scale or bulk vector-like particles can be considered as string-scale threshold corrections since their masses are close to the string scale. Furthermore, we discuss the phenomenological consequences of our models. In particular, in the models with TeV-scale vector-like particles, the vector-like particles can be observed at the Large Hadron Collider, the proton decay is within the reach of the future Hyper-Kamiokande experiment, the lightest CP-even Higgs boson mass can be increased, the hybrid inflation can be naturally realized, and the correct cosmic primordial density fluctuations can be generated.

  20. Semilocal and electroweak strings

    NARCIS (Netherlands)

    Achucarro, A; Vachaspati, T

    We review a class of non-topological defects in the standard electroweak model, and their implications. Starting with the semilocal string, which provides a counterexample to many well-known properties of topological vortices, we discuss electroweak strings and their stability with and without

  1. Zee-Babu type model with U (1 )Lμ-Lτ gauge symmetry

    Science.gov (United States)

    Nomura, Takaaki; Okada, Hiroshi

    2018-05-01

    We extend the Zee-Babu model, introducing local U (1 )Lμ-Lτ symmetry with several singly charged bosons. We find a predictive neutrino mass texture in a simple hypothesis in which mixings among singly charged bosons are negligible. Also, lepton-flavor violations are less constrained compared with the original model. Then, we explore the testability of the model, focusing on doubly charged boson physics at the LHC and the International Linear Collider.

  2. Right-handed neutrino dark matter in a U(1) extension of the Standard Model

    Science.gov (United States)

    Cox, Peter; Han, Chengcheng; Yanagida, Tsutomu T.

    2018-01-01

    We consider minimal U(1) extensions of the Standard Model in which one of the right-handed neutrinos is charged under the new gauge symmetry and plays the role of dark matter. In particular, we perform a detailed phenomenological study for the case of a U(1)(B‑L)3 flavoured B‑L symmetry. If perturbativity is required up to high-scales, we find an upper bound on the dark matter mass of mχlesssim2 TeV, significantly stronger than that obtained in simplified models. Furthermore, if the U(1)(B‑L)3 breaking scalar has significant mixing with the SM Higgs, there are already strong constraints from direct detection. On the other hand, there remains significant viable parameter space in the case of small mixing, which may be probed in the future via LHC Z' searches and indirect detection. We also comment on more general anomaly-free symmetries consistent with a TeV-scale RH neutrino dark matter candidate, and show that if two heavy RH neutrinos for leptogenesis are also required, one is naturally led to a single-parameter class of U(1) symmetries.

  3. Gravitational waves from the first order electroweak phase transition in the Z3 symmetric singlet scalar model*

    Directory of Open Access Journals (Sweden)

    Matsui Toshinori

    2018-01-01

    Full Text Available Among various scenarios of baryon asymmetry of the Universe, electroweak baryogenesis is directly connected with physics of the Higgs sector. We discuss spectra of gravitational waves which are originated by the strongly first order phase transition at the electroweak symmetry breaking, which is required for a successful scenario of electroweak baryogenesis. In the Z3 symmetric singlet scalar model, the significant gravitational waves are caused by the multi-step phase transition. We show that the model can be tested by measuring the characteristic spectra of the gravitational waves at future interferometers such as LISA and DECIGO.

  4. Substrantiation of the Weinberg angle value in 6-dimensional model of gravi-electroweak interactions

    International Nuclear Information System (INIS)

    Vladimirov, Yu.S.; Miroshnik, A.O.

    1988-01-01

    The 6-dimensional geometric theory combining the general relativity theory with the model of electroweak Weinberg-Salam interactions is suggested. The metric process of charged W ± -boson introduction when giving up the condition of metrics cylindricity according to additional coordinates is used. Mass mechanism of the Higgs type leads to correct relation between W ± - and Z-bozon masses. Total correspondence with the Weinberg-Salam model is shown. The value of the Weinberg angle is found theoretically

  5. Electroweak corrections

    International Nuclear Information System (INIS)

    Beenakker, W.J.P.

    1989-01-01

    The prospect of high accuracy measurements investigating the weak interactions, which are expected to take place at the electron-positron storage ring LEP at CERN and the linear collider SCL at SLAC, offers the possibility to study also the weak quantum effects. In order to distinguish if the measured weak quantum effects lie within the margins set by the standard model and those bearing traces of new physics one had to go beyond the lowest order and also include electroweak radiative corrections (EWRC) in theoretical calculations. These higher-order corrections also can offer the possibility of getting information about two particles present in the Glashow-Salam-Weinberg model (GSW), but not discovered up till now, the top quark and the Higgs boson. In ch. 2 the GSW standard model of electroweak interactions is described. In ch. 3 some special techniques are described for determination of integrals which are responsible for numerical instabilities caused by large canceling terms encountered in the calculation of EWRC effects, and methods necessary to get hold of the extensive algebra typical for EWRC. In ch. 4 various aspects related to EWRC effects are discussed, in particular the dependence of the unknown model parameters which are the masses of the top quark and the Higgs boson. The processes which are discussed are production of heavy fermions from electron-positron annihilation and those of the fermionic decay of the Z gauge boson. (H.W.). 106 refs.; 30 figs.; 6 tabs.; schemes

  6. Long-distance properties of frozen U(1) Higgs and axially U(1)-gauged four-Fermi models in 1 + 1 dimensions

    International Nuclear Information System (INIS)

    Yamamoto, Hisashi.

    1993-07-01

    We study the long-distance relevance of vortices (instantons) in an N-component axially U(1)-gauged four-Fermi theory in 1 + 1 dimensions, in which a naive use of 1/N expansion predicts the dynamical Higgs phenomenon. Its general effective lagrangian is found to be a frozen U(1) Higgs model with the gauge-field mass term proportional to an anomaly parameter (b). The dual-transformed versions of the effective theory are represented by sine-Gordon systems and recursion-relation analyses are performed. The results suggest that in the gauge-invariant scheme (b = 0) vortices are always relevant at long distances, while in non-invariant schemes (b > 0) there exists a critical N above which the long-distance behavior is dominated by a free massless scalar field. (author)

  7. Electroweak Results from CMS

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    We present recent CMS measurements on electroweak boson production including single, double, and triple boson final states. Electroweak processes span many orders of magnitude in production cross section. Measurements of high-rate processes provide stringent tests of the standard model. In addition, rare triboson proceses and final states produced through vector boson scattering are newly accessible with the large integrated luminosity provided by the LHC. If new physics lies just beyond the reach of the LHC, its effects may manifest as enhancements to the high energy kinematics in mulitboson production. We present limits on new physics signatures using an effective field theory which models these modifications as modifications of electroweak gauge couplings. Since electroweak measurements will continue to benefit from the increasing integrated luminosity provided by the LHC, the future prospects of electroweak physics are discussed.

  8. Nuclear matter saturation in a U(1) circle-times chiral model

    International Nuclear Information System (INIS)

    Lin, Wei

    1989-01-01

    The mean-field approximation in the U(1) circle-times chiral model for nuclear matter maturation is reviewed. Results show that it cannot be the correct saturation mechanism. It is argued that in this chiral model, other than the fact the ω mass can depend on the density of nuclear matter, saturation is still quite like the Walecka picture. 16 refs., 3 figs

  9. Slavnov and Gaudin-Korepin Formulas for Models without U(1) Symmetry: the Twisted XXX Chain

    Science.gov (United States)

    Belliard, Samuel; Pimenta, Rodrigo A.

    2015-12-01

    We consider the XXX spin-1/2 Heisenberg chain on the circle with an arbitrary twist. We characterize its spectral problem using the modified algebraic Bethe anstaz and study the scalar product between the Bethe vector and its dual. We obtain modified Slavnov and Gaudin-Korepin formulas for the model. Thus we provide a first example of such formulas for quantum integrable models without U(1) symmetry characterized by an inhomogenous Baxter T-Q equation.

  10. New scotogenic model of neutrino mass with U(1){sub D} gauge interaction

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Ernest [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Picek, Ivica; Radovčić, Branimir [Department of Physics, Faculty of Science, University of Zagreb, P.O.B. 331, HR-10002 Zagreb (Croatia)

    2013-11-04

    We propose a new realization of the one-loop radiative model of neutrino mass generated by dark matter (scotogenic), where the particles in the loop have an additional U(1){sub D} gauge symmetry, which may be exact or broken to Z{sub 2}. This model is relevant to a number of astrophysical observations, including AMS-02 and the dark-matter distribution in dwarf galactic halos.

  11. The flipped SU(5)xU(1) string model revamped

    Energy Technology Data Exchange (ETDEWEB)

    Antoniadis, I.; Ellis, J.; Hagelin, J.S.; Nanopoulos, D.V. (European Organization for Nuclear Research, Geneva (Switzerland))

    1989-11-02

    We present a refined version of our three-generation flipped SU(5)xU(1) string model with the following properties. The complete massless spectrum is derived and shown to be free of all gauge and mixed anomalies apart from a single anomalous U(1). The imaginary part of the dilaton supermultiplet is eaten by the anomalous U(1) gauge boson, and the corresponding D-term is cancelled by large VEVs for singlet fields that break surplus U(1) gauge factors, leaving a supersymmetric vacuum with an SU(5)xU(1) visible gauge group and an SO(10)xSO(6) hidden gauge group. There are sufficient Higgs multiplets to break the visible gauge symmetry down to the standard model in an essentially unique way. All trilinear superpotential couplings have been calculated and there are in particular some giving m{sub t}, m{sub b}, m{sub tau}ne0. A renormalization group analysis shows that m{sub t}<190 GeV and m{sub b}{approx equal}3m{sub tau}. Light Higgs doublets are split automatically from heavy Higgs triplets, leaving no residual dimension-five operators for baryon decay, and the baryon lifetime tau{sub B} {approx equal} 2x10{sup 34{plus minus}2} yr. There are no tree-level flavour-changing neutral currents, but muyieldsegamma may occur at a detectable level: B(muyieldsegamma){proportional to} 10{sup -11}-10{sup -14}. (orig.).

  12. Electroweak monopoles and the electroweak phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Arunasalam, Suntharan; Kobakhidze, Archil [The University of Sydney, ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, Sydney, NSW (Australia)

    2017-07-15

    We consider an isolated electroweak monopole solution within the Standard Model with a nonlinear Born-Infeld extension of the hypercharge gauge field. Monopole (and dyon) solutions in such an extension are regular and their masses are predicted to be proportional to the Born-Infeld mass parameter. We argue that cosmological production of electroweak monopoles may delay the electroweak phase transition and make it more strongly first order for monopole masses M >or similar 9.3 . 10{sup 3} TeV, while the nucleosynthesis constraints on the abundance of relic monopoles impose the bound M electroweak phase transition. (orig.)

  13. Geometrical origin of tricritical points of various U(1) lattice models

    International Nuclear Information System (INIS)

    Janke, W.; Kleiert, H.

    1989-01-01

    The authors review the dual relationship between various compact U(1) lattice models and Abelian Higgs models, the latter being the disorder field theories of line-like topological excitations in the system. The authors point out that the predicted first-order transitions in the Abelian Higgs models (Coleman-Weinberg mechanism) are, in three dimensions, in contradiction with direct numerical investigations in the compact U(1) formulation since these yield continuous transitions in the major part of the phase diagram. In four dimensions, there are indications from Monte Carlo data for a similar situation. Concentrating on the strong-coupling expansion in terms of geometrical objects, surfaces or lines, with certain statistical weights, the authors present semi-quantitative arguments explaining the observed cross-over from first-order to continuous transitions by the balance between the lowest two weights (2:1 ratio) of these geometrical objects

  14. Testable flipped SU(5)xU(1){sub X} models

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Jing [Institute of Theoretical Science, University of Oregon, Eugene, OR 97403 (United States); Li Tianjun [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States) and Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100080 (China) and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States)]. E-mail: tjli@physics.rutgers.edu; Nanopoulos, Dimitri V. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States); Astroparticle Physics Group, Houston Advanced Research Center (HARC), Mitchell Campus, Woodlands, TX 77381 (United States); Academy of Athens, Division of Natural Sciences, 28 Panepistimiou Avenue, Athens 10679 (Greece)

    2007-06-11

    The little hierarchy between the GUT scale and the string scale may give us some hints that can be tested at the LHC. To achieve string-scale gauge coupling unification, we introduce additional vector-like particles. We require that these vector-like particles be standard, form complete GUT multiplets, and have masses around the TeV scale or close to the string scale. Interestingly, only the flipped SU(5)xU(1){sub X} models can work elegantly. We consider all possible sets of vector-like particles with masses around the TeV scale. And we introduce vector-like particles with masses close to the string scale which can mimic the string-scale threshold corrections. We emphasize that all of these vector-like particles can be obtained in the interesting flipped SU(5)xU(1){sub X} string models from the four-dimensional free fermionic string construction. Assuming the low-energy supersymmetry, high-scale supersymmetry, and split supersymmetry, we show that the string-scale gauge coupling unification can indeed be achieved in the flipped SU(5)xU(1){sub X} models. These models can be tested at the LHC by observing simple sets of vector-like particles at the TeV scale. Moreover, we discuss a simple flipped SU(5)xU(1){sub X} model with string-scale gauge coupling unification and high-scale supersymmetry by introducing only one pair of the vector-like particles at the TeV scale, and we predict the corresponding Higgs boson masses. Also, we briefly comment on the string-scale gauge coupling unification in the model with low-energy supersymmetry by introducing only one pair of the vector-like particles at the intermediate scale. And we briefly comment on the mixings among the SM fermions and the corresponding extra vector-like particles.

  15. Z{sup ′}, Higgses and heavy neutrinos in U(1){sup ′} models: from the LHC to the GUT scale

    Energy Technology Data Exchange (ETDEWEB)

    Accomando, Elena [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Corianò, Claudio [STAG Research Centre and Mathematical Sciences, University of Southampton,Highfield, Southampton SO17 1BJ (United Kingdom); Dipartimento di Matematica e Fisica “Ennio De Giorgi”, Università del Salento and INFN-Lecce, Via Arnesano, 73100 Lecce (Italy); Rose, Luigi Delle; Fiaschi, Juri [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Marzo, Carlo [Dipartimento di Matematica e Fisica “Ennio De Giorgi”, Università del Salento and INFN-Lecce, Via Arnesano, 73100 Lecce (Italy); Moretti, Stefano [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom)

    2016-07-18

    We study a class of non-exotic minimal U(1){sup ′} extensions of the Standard Model, which includes all scenarios that are anomaly-free with the ordinary fermion content augmented by one Right-Handed neutrino per generation, wherein the new Abelian gauge group is spontaneously broken by the non-zero Vacuum Expectation Value of an additional Higgs singlet field, in turn providing mass to a Z{sup ′} state. By adopting the B−L example, whose results can be recast into those pertaining to the whole aforementioned class, and allowing for both scalar and gauge mixing, we first extract the surviving parameter space in presence of up-to-date theoretical and experimental constraints. Over the corresponding parameter configurations, we then delineate the high energy behaviour of such constructs in terms of their stability and perturbativity. Finally, we highlight key production and decay channels of the new states entering the spectra of this class of models, i.e., heavy neutrinos, a second Higgs state and the Z{sup ′}, which are amenable to experimental investigation at the Large Hadron Collider. We therefore set the stage to establish a direct link between measurements obtainable at the Electro-Weak scale and the dynamics of the underlying model up to those where a Grand Unification Theory embedding a U(1){sup ′} can be realised.

  16. Precision electroweak tests of the minimal and flipped SU(5) supergravity models

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, J.L.; Nanopoulos, D.V.; Park, G.T.; Pois, H.; Yuan, K. (Center for Theoretical Physics, Department of Physics, Texas A M University, College Station, Texas 77843-4242 (United States) Astroparticle Physics Group, Houston Advanced Research Center (HARC), The Woodlands, Texas 77381 (United States))

    1993-10-01

    We explore the one-loop electroweak radiative corrections in the minimal SU(5) and the no-scale flipped SU(5) supergravity models via explicit calculation of vacuum polarization contributions to the [epsilon][sub 1,2,3] parameters. Experimentally, [epsilon][sub 1,2,3] are obtained from a global fit to the CERN LEP observables, and [ital M][sub [ital W

  17. Retracing the phenomenology of the flipped SU(5)xU(1) superstring model

    Energy Technology Data Exchange (ETDEWEB)

    Rizos, J.; Tamvakis, K. (Ioannina Univ. (Greece). Dept. of Physics)

    1990-11-22

    We study in detail gauge symmetry breaking in the SU(5)xU(1)'xU(1){sup 4}xSO(10)xSO(6) superstring model, solving the D- and F-flatness conditions and taking into account quartic and quintic superpotential terms. We find that, to this order, the model describes two massive generations of quarks and leptons as well as a massless generation expected to receive naturally suppressed masses from higher order non-renormalizable terms. We show that D-flatness restricts the number of massless isodoublets to four. We also extract an inequality relating the top quark mass to M{sub W}. (orig.).

  18. Dark gauge U(1) symmetry for an alternative left-right model

    Energy Technology Data Exchange (ETDEWEB)

    Kownacki, Corey; Ma, Ernest; Pollard, Nicholas; Popov, Oleg; Zakeri, Mohammadreza [University of California, Department of Physics and Astronomy, Riverside, CA (United States)

    2018-02-15

    An alternative left-right model of quarks and leptons, where the SU(2){sub R} lepton doublet (ν, l){sub R} is replaced with (n, l){sub R} so that n{sub R} is not the Dirac mass partner of ν{sub L}, has been known since 1987. Previous versions assumed a global U(1){sub S} symmetry to allow n to be identified as a dark-matter fermion. We propose here a gauge extension by the addition of extra fermions to render the model free of gauge anomalies, and just one singlet scalar to break U(1){sub S}. This results in two layers of dark matter, one hidden behind the other. (orig.)

  19. Phenomenological implications of the flipped SU(5) x U(1) superstring model

    Energy Technology Data Exchange (ETDEWEB)

    Tamvakis, K. (Physics Dept., Univ. of Ioannina (Greece))

    1991-07-01

    We study in detail gauge symmetry breaking in the SU(5)xU(1)'xU(1){sup 4}xSO(10)xSO(6) superstring model, solving the D and F-flatness conditions and taking into account quartic and quintic superpotential terms. We find that, to this order, the model describes two massive generations of quarks and leptons as well as a massless generation expected to receive naturally suppressed masses from higher order non-renormalizable terms. D and F-flatness restricts the number of massless isodoublets to four. We solve the coupled renormalization group equations for the gauge and Yukawa couplings in the two-loop approximation and obtain the top-quark mass as a function of two parameters of the model which could be chosen to be ratios of singlet v.e.v's associated with the surplus (U(1)){sup 4} breaking. We obtain a heavy top-quark with 150GeV {<=} m{sub 1} < 200GeV, for most part of the parameter space, while lower values are possible only in a very small extermal region. We also compute the allowed range of unification parameters (M{sub x}, sin{sup 2} {theta}{sub w}, {alpha}{sub 3}(M{sub w})) in the presence of a heavy top quark. (orig.).

  20. Strongest experimental constraints on SU(5)×U(1) supergravity models

    Science.gov (United States)

    Lopez, Jorge L.; Nanopoulos, D. V.; Park, Gye T.; Zichichi, A.

    1994-01-01

    We consider a class of well-motivated string-inspired flipped SU(5) supergravity models which include four supersymmetry-breaking scenarios: no-scale, strict no-scale, dilaton, and special dilaton, such that only three parameters are needed to describe all new phenomena (mt,tanβ,mg~). We show that the CERN LEP precise measurements of the electroweak parameters in the form of the ɛ1 variable and the CLEO II allowed range for B(b-->sγ) are at present the most important experimental constraints on this class of models. For mt>~155 (165) GeV, the ɛ1 constraint [at 90 (95)% C.L.] requires the presence of light charginos (m+/-χ1360 GeV, mq~sγ) constraint excludes a significant fraction of the otherwise allowed region in the (m+/-χ1,tanβ) plane (irrespective of the magnitude of the chargino mass), while future experimental improvements will result in decisive tests of these models. In light of the ɛ1 constraint, we conclude that the outlook for chargino and selectron detection at LEP II and at DESY HERA is quite favorable in this class of models.

  1. Resolutions of Cn/Zn orbifolds, their U(1) bundles, and applications to string model building

    International Nuclear Information System (INIS)

    Nibbelink, Stefan Groot; Trapletti, Michele; Walter, Martin G.A.

    2007-01-01

    We describe blowups of C n /Z n orbifolds as complex line bundles over CP n-1 . We construct some gauge bundles on these resolutions. Apart from the standard embedding, we describe U(1) bundles and an SU(n-1) bundle. Both blowups and their gauge bundles are given explicitly. We investigate ten dimensional SO(32) super Yang-Mills theory coupled to supergravity on these backgrounds. The integrated Bianchi identity implies that there are only a finite number of U(1) bundle models. We describe how the orbifold gauge shift vector can be read off from the gauge background. In this way we can assert that in the blow down limit these models correspond to heterotic C 2 /Z 2 and C 3 /Z 3 orbifold models. (Only the Z 3 model with unbroken gauge group SO(32) cannot be reconstructed in blowup without torsion.) This is confirmed by computing the charged chiral spectra on the resolutions. The construction of these blowup models implies that the mismatch between type-I and heterotic models on T 6 /Z 3 does not signal a complication of S-duality, but rather a problem of type-I model building itself: The standard type-I orbifold model building only allows for a single model on this orbifold, while the blowup models give five different models in blow down

  2. Mixed Mediation of Supersymmetry Breaking in Models with Anomalous U(1) Gauge Symmetry

    International Nuclear Information System (INIS)

    Choi, Kiwoon

    2010-01-01

    There can be various built-in sources of supersymmetry breaking in models with anomalous U(1) gauge symmetry, e.g. the U(1) D-term, the F-components of the modulus superfield required for the Green-Schwarz anomaly cancellation mechanism and the chiral matter superfields required to cancel the Fayet-Iliopoulos term, and finally the supergravity auxiliary component which can be parameterized by the F-component of chiral compensator. The relative strength between these supersymmetry breaking sources depends crucially on the characteristics of D-flat direction and also on how the D-flat direction is stabilized at a vacuum with nearly vanishing cosmological constant. We examine the possible pattern of the mediation of supersymmetry breaking in models with anomalous U(1) gauge symmetry, and find that various different mixed mediation scenarios can be realized, including the mirage mediation which corresponds to a mixed modulus-anomaly mediation, D-term domination giving a split sparticle spectrum, and also a mixed gauge-D-term mediation scenario.

  3. Precision electroweak measurements

    International Nuclear Information System (INIS)

    Demarteau, M.

    1996-11-01

    Recent electroweak precision measurements fro e + e - and p anti p colliders are presented. Some emphasis is placed on the recent developments in the heavy flavor sector. The measurements are compared to predictions from the Standard Model of electroweak interactions. All results are found to be consistent with the Standard Model. The indirect constraint on the top quark mass from all measurements is in excellent agreement with the direct m t measurements. Using the world's electroweak data in conjunction with the current measurement of the top quark mass, the constraints on the Higgs' mass are discussed

  4. Neutrino mass, leptogenesis and FIMP dark matter in a U(1){sub B-L} model

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Anirban; Khan, Sarif [Harish-Chandra Research Institute, Allahabad (India); Homi Bhabha National Institute, Training School Complex, Mumbai (India); Choubey, Sandhya [Harish-Chandra Research Institute, Allahabad (India); Homi Bhabha National Institute, Training School Complex, Mumbai (India); AlbaNova University Center, Department of Theoretical Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Stockholm (Sweden)

    2017-12-15

    The Standard Model (SM) is inadequate to explain the origin of tiny neutrino masses, the dark matter (DM) relic abundance and the baryon asymmetry of the Universe. In this work, to address all three puzzles, we extend the SM by a local U(1){sub B-L} gauge symmetry, three right-handed (RH) neutrinos for the cancellation of gauge anomalies and two complex scalars having non-zero U(1){sub B-L} charges. All the newly added particles become massive after the breaking of the U(1){sub B-L} symmetry by the vacuum expectation value (VEV) of one of the scalar fields φ{sub H}. The other scalar field, φ{sub DM}, which does not have any VEV, becomes automatically stable and can be a viable DM candidate. Neutrino masses are generated using the Type-I seesaw mechanism, while the required lepton asymmetry to reproduce the observed baryon asymmetry can be attained from the CP violating out of equilibrium decays of the RH neutrinos in TeV scale. More importantly within this framework, we study in detail the production of DM via the freeze-in mechanism considering all possible annihilation and decay processes. Finally, we find a situation when DM is dominantly produced from the annihilation of the RH neutrinos, which are at the same time also responsible for neutrino mass generation and leptogenesis. (orig.)

  5. Neutrino mass, leptogenesis and FIMP dark matter in a U(1)_{B-L} model

    Science.gov (United States)

    Biswas, Anirban; Choubey, Sandhya; Khan, Sarif

    2017-12-01

    The Standard Model (SM) is inadequate to explain the origin of tiny neutrino masses, the dark matter (DM) relic abundance and the baryon asymmetry of the Universe. In this work, to address all three puzzles, we extend the SM by a local U(1)_{B-L} gauge symmetry, three right-handed (RH) neutrinos for the cancellation of gauge anomalies and two complex scalars having non-zero U(1)_{B-L} charges. All the newly added particles become massive after the breaking of the U(1)_{B-L} symmetry by the vacuum expectation value (VEV) of one of the scalar fields φ _H. The other scalar field, φ _DM, which does not have any VEV, becomes automatically stable and can be a viable DM candidate. Neutrino masses are generated using the Type-I seesaw mechanism, while the required lepton asymmetry to reproduce the observed baryon asymmetry can be attained from the CP violating out of equilibrium decays of the RH neutrinos in TeV scale. More importantly within this framework, we study in detail the production of DM via the freeze-in mechanism considering all possible annihilation and decay processes. Finally, we find a situation when DM is dominantly produced from the annihilation of the RH neutrinos, which are at the same time also responsible for neutrino mass generation and leptogenesis.

  6. CP violation for electroweak baryogenesis from mixing of standard model and heavy vector quarks

    International Nuclear Information System (INIS)

    McDonald, J.

    1996-01-01

    It is known that the CP violation in the minimal standard model is insufficient to explain the observed baryon asymmetry of the Universe in the context electroweak baryogenesis. In this paper we consider the possibility that the additional CP violation required could originate in the mixing of the standard model quarks and heavy vector quark pairs. We consider the baryon asymmetry in the context of the spontaneous baryogenesis scenario. It is shown that, in general, the CP-violating phase entering the mass matrix of the standard model and heavy vector quarks must be space dependent in order to produce a baryon asymmetry, suggesting that the additional CP violation must be spontaneous in nature. This is true for the case of the simplest models which mix the standard model and heavy vector quarks. We derive a charge potential term for the model by diagonalizing the quark mass matrix in the presence of the electroweak bubble wall, which turns out to be quite different from the fermionic hypercharge potentials usually considered in spontaneous baryogenesis models, and obtain the rate of baryon number generation within the wall. We find, for the particular example where the standard model quarks mix with weak-isodoublet heavy vector quarks via the expectation value of a gauge singlet scalar, that we can account for the observed baryon asymmetry with conservative estimates for the uncertain parameters of electroweak baryogenesis, provided that the heavy vector quarks are not heavier than a few hundred GeV and that the coupling of the standard model quarks to the heavy vector quarks and gauge singlet scalars is not much smaller than order of 1, corresponding to a mixing angle of the heavy vector quarks and standard model quarks not much smaller than order of 10 -1 . copyright 1996 The American Physical Society

  7. Constraints from proton decay in the flipped SU(5)xU(1) superstring model

    Energy Technology Data Exchange (ETDEWEB)

    Leontaris, G.K.; Tamvakis, K. (Ioannina Univ. (Greece). Theoretical Physics Div.)

    1991-05-16

    We discuss the constraints the emerge from the existence of dimension-5 baryon-violating operators in the flipped SU(5) x U(1) superstring model. These are constraints on matter field assignments and on singlet VEV values. Although baryon-violating dimension-5 operators that appear as quintic non-renormalizable terms vanish as has been proven before and as we verify here, effective dimension-5 operators resulting from Higgs exchange put non-trivial but feasible constraints on the model. Constraints are also extracted from the presence of higher order non-renormalizable terms that generate such operators which do not a priori vanish. (orig.).

  8. Loop calculations for the non-commutative U*(1) gauge field model with oscillator term

    International Nuclear Information System (INIS)

    Blaschke, Daniel N.; Grosse, Harald; Kronberger, Erwin; Schweda, Manfred; Wohlgenannt, Michael

    2010-01-01

    Motivated by the success of the non-commutative scalar Grosse-Wulkenhaar model, a non-commutative U * (1) gauge field theory including an oscillator-like term in the action has been put forward in (Blaschke et al. in Europhys. Lett. 79:61002, 2007). The aim of the current work is to analyze whether that action can lead to a fully renormalizable gauge model on non-commutative Euclidean space. In a first step, explicit one-loop graph computations are hence presented, and their results as well as necessary modifications of the action are successively discussed. (orig.)

  9. Continuons left-right symmetrical model of electroweak interactions

    International Nuclear Information System (INIS)

    Boyarkin, O.M.

    1993-01-01

    The left-right model (LR) is suggested which is characterized by the orientation angle of the SU(2) R generator in the group space. This model reproduces all the known LR models. The production processes of gauge bosons at electron-positron and hardon colliders are investigated

  10. On some dynamical properties of the subconstituent models of electroweak interactions

    International Nuclear Information System (INIS)

    Narison, S.

    1982-01-01

    We determine the order of magnitude value of the haplon vacuum condensate and the W-W' level spacing using spectral function sum rules for the electroweak constituent models of quantum haplo-dynamics (QHD). We also discuss some consequences of the QHD model with massive haplons. We conclude that the haplons of QHD which bind the W-boson are very similar to the u,d quarks of QCD. The models with massive haplons would imply the existence of exotic light pseudoscalar bosons. Some implications of these exotic particles for low-energy phenomenology are discussed

  11. A dual resonance model for high energy electroweak reactions

    International Nuclear Information System (INIS)

    Picard, Jean-Francois

    1995-01-01

    The aim of this work is to propose an original model for the weak interaction at high energy (about 1 TeV) that is inspired from resonance dual models established for hadron physics. The first chapter details the basis and assumptions of the standard model. The second chapter deals with various scenarios that go beyond the standard model and that involve a strong interaction and a perturbative approach to assess coupling. The third chapter is dedicated to the main teachings of hadron physics concerning resonances, the model of Regge poles and the concept of duality. We present our new model in the fourth chapter, we build a scenario in which standard fermions and the 3 massive gauge bosons would have a sub-structure alike that of hadrons. In order to give non-null values to the width of resonances we use the K matrix method, we describe this method in the last chapter and we apply it for the computation of the width of the Z 0 boson. Our model predicts a large spectra of states particularly with the 143-up-lets of ff-bar states. The K matrix method has allowed us to compute amplitudes for helicity, then to collapse them in amplitudes invariant with SU(2) and to project these amplitudes in partial waves of helicity. For most resonances partial widths are very low compared to their mass

  12. One-loop analysis of the electroweak breaking in supersymmetric models and the fine-tuning problem

    CERN Document Server

    De Carlos, B

    1993-01-01

    We examine the electroweak breaking mechanism in the minimal supersymmetric standard model (MSSM) using the {\\em complete} one-loop effective potential $V_1$. First, we study what is the region of the whole MSSM parameter space (i.e. $M_{1/2},m_o,\\mu,...$) that leads to a succesful $SU(2)\\times U(1)$ breaking with an acceptable top quark mass. In doing this it is observed that all the one-loop corrections to $V_1$ (even the apparently small ones) must be taken into account in order to get reliable results. We find that the allowed region of parameters is considerably enhanced with respect to former "improved" tree level results. Next, we study the fine-tuning problem associated with the high sensitivity of $M_Z$ to $h_t$ (the top Yukawa coupling). Again, we find that this fine-tuning is appreciably smaller once the one-loop effects are considered than in previous tree level calculations. Finally, we explore the ambiguities and limitations of the ordinary criterion to estimate the degree of fine-tuning. As a r...

  13. Automation of electroweak NLO corrections in general models

    Energy Technology Data Exchange (ETDEWEB)

    Lang, Jean-Nicolas [Universitaet Wuerzburg (Germany)

    2016-07-01

    I discuss the automation of generation of scattering amplitudes in general quantum field theories at next-to-leading order in perturbation theory. The work is based on Recola, a highly efficient one-loop amplitude generator for the Standard Model, which I have extended so that it can deal with general quantum field theories. Internally, Recola computes off-shell currents and for new models new rules for off-shell currents emerge which are derived from the Feynman rules. My work relies on the UFO format which can be obtained by a suited model builder, e.g. FeynRules. I have developed tools to derive the necessary counterterm structures and to perform the renormalization within Recola in an automated way. I describe the procedure using the example of the two-Higgs-doublet model.

  14. A radiative neutrino mass model in light of DAMPE excess with hidden gauged U(1) symmetry

    Science.gov (United States)

    Nomura, Takaaki; Okada, Hiroshi; Wu, Peiwen

    2018-05-01

    We propose a one-loop induced neutrino mass model with hidden U(1) gauge symmetry, in which we successfully involve a bosonic dark matter (DM) candidate propagating inside a loop diagram in neutrino mass generation to explain the e+e‑ excess recently reported by the DArk Matter Particle Explorer (DAMPE) experiment. In our scenario dark matter annihilates into four leptons through Z' boson as DM DM → Z' Z' (Z' → l+ l‑) and Z' decays into leptons via one-loop effect. We then investigate branching ratios of Z' taking into account lepton flavor violations and neutrino oscillation data.

  15. Hidden U (1 ) gauge symmetry realizing a neutrinophilic two-Higgs-doublet model with dark matter

    Science.gov (United States)

    Nomura, Takaaki; Okada, Hiroshi

    2018-04-01

    We propose a neutrinophilic two-Higgs-doublet model with hidden local U (1 ) symmetry, where active neutrinos are Dirac type, and a fermionic dark matter (DM) candidate is naturally induced as a result of remnant symmetry even after the spontaneous symmetry breaking. In addition, a physical Goldstone boson arises as a consequence of two types of gauge singlet bosons and contributes to the DM phenomenologies as well as an additional neutral gauge boson. Then, we analyze the relic density of DM within the safe range of direct detection searches and show the allowed region of dark matter mass.

  16. Strongest experimental constraints on SU(5)xU(1) supergravity models

    International Nuclear Information System (INIS)

    Lopez, J.L.; Nanopoulos, D.V.; Park, G.T.; Zichichi, A.

    1994-01-01

    We consider a class of well-motivated string-inspired flipped SU(5) supergravity models which include four supersymmetry-breaking scenarios: no-scale, strict no-scale, dilaton, and special dilaton, such that only three parameters are needed to describe all new phenomena (m t ,tanβ,m g ). We show that the CERN LEP precise measurements of the electroweak parameters in the form of the ε 1 variable and the CLEO II allowed range for B(b→sγ) are at present the most important experimental constraints on this class of models. For m t approx-gt 155 (165) GeV, the ε 1 constraint [at 90 (95)% C.L.] requires the presence of light charginos (m χ1 ± approx-lt 50--100 GeV depending on m t ). Since all sparticle masses are proportional to m g , m χ1 ± approx-lt 100 GeV implies m χ1 0 approx-lt 55 GeV, m χ2 0 approx-lt 100 GeV, m g approx-lt 360 GeV, m q approx-lt 350 (365) GeV, m e R approx-lt 80 (125) GeV, m e L approx-lt 120 (155) GeV, and m n u approx-lt 100 (140) GeV in the no-scale (dilaton) flipped SU(5) supergravity model. The B(b→sγ) constraint excludes a significant fraction of the otherwise allowed region in the (m χ1 ± ,tanβ) plane (irrespective of the magnitude of the chargino mass), while future experimental improvements will result in decisive tests of these models

  17. Stability of the electroweak ground state in the Standard Model and its extensions

    International Nuclear Information System (INIS)

    Di Luzio, Luca; Isidori, Gino; Ridolfi, Giovanni

    2016-01-01

    We review the formalism by which the tunnelling probability of an unstable ground state can be computed in quantum field theory, with special reference to the Standard Model of electroweak interactions. We describe in some detail the approximations implicitly adopted in such calculation. Particular attention is devoted to the role of scale invariance, and to the different implications of scale-invariance violations due to quantum effects and possible new degrees of freedom. We show that new interactions characterized by a new energy scale, close to the Planck mass, do not invalidate the main conclusions about the stability of the Standard Model ground state derived in absence of such terms.

  18. Stability of the electroweak ground state in the Standard Model and its extensions

    Energy Technology Data Exchange (ETDEWEB)

    Di Luzio, Luca, E-mail: diluzio@ge.infn.it [Dipartimento di Fisica, Università di Genova and INFN, Sezione di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); Isidori, Gino [Department of Physics, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Ridolfi, Giovanni [Dipartimento di Fisica, Università di Genova and INFN, Sezione di Genova, Via Dodecaneso 33, I-16146 Genova (Italy)

    2016-02-10

    We review the formalism by which the tunnelling probability of an unstable ground state can be computed in quantum field theory, with special reference to the Standard Model of electroweak interactions. We describe in some detail the approximations implicitly adopted in such calculation. Particular attention is devoted to the role of scale invariance, and to the different implications of scale-invariance violations due to quantum effects and possible new degrees of freedom. We show that new interactions characterized by a new energy scale, close to the Planck mass, do not invalidate the main conclusions about the stability of the Standard Model ground state derived in absence of such terms.

  19. Stability of the electroweak ground state in the Standard Model and its extensions

    Directory of Open Access Journals (Sweden)

    Luca Di Luzio

    2016-02-01

    Full Text Available We review the formalism by which the tunnelling probability of an unstable ground state can be computed in quantum field theory, with special reference to the Standard Model of electroweak interactions. We describe in some detail the approximations implicitly adopted in such calculation. Particular attention is devoted to the role of scale invariance, and to the different implications of scale-invariance violations due to quantum effects and possible new degrees of freedom. We show that new interactions characterized by a new energy scale, close to the Planck mass, do not invalidate the main conclusions about the stability of the Standard Model ground state derived in absence of such terms.

  20. The Sommerfeld enhancement in the scotogenic model with large electroweak scalar multiplets

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, Talal Ahmed [Department of Physics, University of Dhaka, P.O. Box 1000, Dhaka (Bangladesh); Nasri, Salah, E-mail: talal@du.ac.bd, E-mail: snasri@uaeu.ac.ae [Department of Physics, UAE University, P.O. Box 17551, Al-Ain (United Arab Emirates)

    2017-01-01

    We investigate the Sommerfeld enhancement (SE) in the generalized scotogenic model with large electroweak multiplets. We focus on scalar dark matter (DM) candidate of the model and compare DM annihilation cross sections to WW , ZZ , γγ and γ Z at present day in the galactic halo for scalar doublet and its immediate generalization, the quartet in their respective viable regions of parameter space. We find that larger multiplet has sizable Sommerfeld enhanced annihilation cross section compared to the doublet and because of that it is more likely to be constrained by the current H.E.S.S. results and future CTA sensitivity limits.

  1. Developments in standard model: electroweak theory/phenomenology

    International Nuclear Information System (INIS)

    Deshpande, N.G.

    1986-01-01

    The authors review new developments in four topics. Higgs detection D in the intermediate mass range (100 GeV 2M/sub W/) is discussed in detail. It is found that the backgrounds are a serious problem in hadronic colliders except for purely leptonic signals, which unfortunately have low event rates. Recent work on topological solutions to standard model, with new states in TeV range are discussed. Large rate of BB vector production at SSC may allow determination of rare modes of B decay. The fourth topic concerns the feasibility of detecting Horizontal gauge bosons at SSC. 17 references, 9 figures

  2. The neutralino sector in the U(1)-extended supersymmetric standard model

    Energy Technology Data Exchange (ETDEWEB)

    Choi, S.Y. [Chonbuk National Univ., Jeonju (Korea). Dept. of Physics and RIPC]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Haber, H.E. [California Univ., Santa Cruz, CA (United States). SCIPP; Kalinowski, J. [Warsaw Univ. (Poland). Inst. of Theoretical Physics; Zerwas, P.M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[California Univ., Santa Cruz, CA (United States). SCIPP

    2006-12-15

    Motivated by grand unified theories and string theories we analyze the general structure of the neutralino sector in the USSM, an extension of the Minimal Supersymmetric Standard Model that involves a broken extra U(1) gauge symmetry. This supersymmetric U(1)-extended model includes an Abelian gauge superfield and a Higgs singlet superfield in addition to the standard gauge and Higgs superfields of the MSSM. The interactions between the MSSM fields and the new fields are in general weak and the mixing is small, so that the coupling of the two subsystems can be treated perturbatively. As a result, the mass spectrum and mixing matrix in the neutralino sector can be analyzed analytically and the structure of this 6-state system is under good theoretical control. We describe the decay modes of the new states and the impact of this extension on decays of the original MSSM neutralinos, including radiative transitions in cross-over zones. Production channels in cascade decays at the LHC and pair production at e{sup +}e{sup -} colliders are also discussed. (orig.)

  3. Tadpole-induced electroweak symmetry breaking and pNGB Higgs models

    Energy Technology Data Exchange (ETDEWEB)

    Harnik, Roni; Howe, Kiel; Kearney, John [Theoretical Physics Department, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)

    2017-03-22

    We investigate induced electroweak symmetry breaking (EWSB) in models in which the Higgs is a pseudo-Nambu-Goldstone boson (pNGB). In pNGB Higgs models, Higgs properties and precision electroweak measurements imply a hierarchy between the EWSB and global symmetry-breaking scales, v{sub H}≪f{sub H}. When the pNGB potential is generated radiatively, this hierarchy requires fine-tuning to a degree of at least ∼v{sub H}{sup 2}/f{sub H}{sup 2}. We show that if Higgs EWSB is induced by a tadpole arising from an auxiliary sector at scale f{sub Σ}≪v{sub H}, this tuning is significantly ameliorated or can even be removed. We present explicit examples both in Composite Higgs models based on SO(5)/SO(4) and in Twin Higgs models. For the Twin case, the result is a fully natural model with f{sub H}∼1 TeV and the lightest colored top partners at 2 TeV. These models also have an appealing mechanism to generate the scales of the auxiliary sector and Higgs EWSB directly from the scale f{sub H}, with a natural hierarchy f{sub Σ}≪v{sub H}≪f{sub H}∼TeV. The framework predicts modified Higgs coupling as well as new Higgs and vector states at LHC13.

  4. Electroweak evolution equations

    International Nuclear Information System (INIS)

    Ciafaloni, Paolo; Comelli, Denis

    2005-01-01

    Enlarging a previous analysis, where only fermions and transverse gauge bosons were taken into account, we write down infrared-collinear evolution equations for the Standard Model of electroweak interactions computing the full set of splitting functions. Due to the presence of double logs which are characteristic of electroweak interactions (Bloch-Nordsieck violation), new infrared singular splitting functions have to be introduced. We also include corrections related to the third generation Yukawa couplings

  5. Electroweak penguins at LHCb

    CERN Document Server

    AUTHOR|(CDS)2073177

    2016-01-01

    Electroweak penguin decays are flavour-changing neutral current processes, and are highly suppressed in the Stan- dard Model. They can only proceed via loop diagrams. Such decays may receive contributions from New Physics and change their decay behaviours like decay rate and angular distribution. Studying the properties of these decays thus provides a powerful method to probe for New Physics. In this contribution the most recent LHCb results on electroweak penguin decays are reported.

  6. Electroweak penguins at LHCb

    Science.gov (United States)

    He, Jibo; LHCb Collaboration

    2016-04-01

    Electroweak penguin decays are flavour-changing neutral current processes, and are highly suppressed in the Standard Model. They can only proceed via loop diagrams. Such decays may receive contributions from New Physics and change their decay behaviours like decay rate and angular distribution. Studying the properties of these decays thus provides a powerful method to probe for New Physics. In this contribution the most recent LHCb results on electroweak penguin decays are reported.

  7. b → s transitions in family-dependent U(1)(prime) models

    International Nuclear Information System (INIS)

    Barger, V.; Everett, L.; Jiang, J.; Langacker, P.; Liu, T.; Wagner, C.E.M.

    2009-01-01

    We analyze flavor-changing-neutral-current (FCNC) effects in the b → s transitions that are induced by family non-universal U(1)(prime) gauge symmetries. After systematically developing the necessary formalism, we present a correlated analysis for the ΔB = 1,2 processes. We adopt a model-independent approach in which we only require family-universal charges for the first and second generations and small fermion mixing angles. We analyze the constraints on the resulting parameter space from B s -(bar B) mixing and the time-dependent CP asymmetries of the penguin-dominated B d → (π,φ, η(prime), ρ,ω,f0)K S decays. Our results indicate that the currently observed discrepancies in some of these modes with respect to the Standard Model predictions can be consistently accommodated within this general class of models.

  8. Electroweak penguin decays as probes of physics beyond the Standard Model

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    Electroweak penguin decays are sensitive to new, virtual particles and therefore offer a unique window on any physics beyond the Standard Model. In the B sector, penguin decays such as B0->K*0mu+mu- give a number of measurable quantities which can be precisely predicted by theory. The LHCb experiment has made the world's most precise measurements of this and several other related decays. These measurements give constraints on any new physics phenomena contributing to the relevant loop processes at mass scales well in excess of those that can be accessed by direct searches. The recent experimental progress of such measurements will be presented.

  9. Low temperature electroweak phase transition in the Standard Model with hidden scale invariance

    Directory of Open Access Journals (Sweden)

    Suntharan Arunasalam

    2018-01-01

    Full Text Available We discuss a cosmological phase transition within the Standard Model which incorporates spontaneously broken scale invariance as a low-energy theory. In addition to the Standard Model fields, the minimal model involves a light dilaton, which acquires a large vacuum expectation value (VEV through the mechanism of dimensional transmutation. Under the assumption of the cancellation of the vacuum energy, the dilaton develops a very small mass at 2-loop order. As a result, a flat direction is present in the classical dilaton-Higgs potential at zero temperature while the quantum potential admits two (almost degenerate local minima with unbroken and broken electroweak symmetry. We found that the cosmological electroweak phase transition in this model can only be triggered by a QCD chiral symmetry breaking phase transition at low temperatures, T≲132 MeV. Furthermore, unlike the standard case, the universe settles into the chiral symmetry breaking vacuum via a first-order phase transition which gives rise to a stochastic gravitational background with a peak frequency ∼10−8 Hz as well as triggers the production of approximately solar mass primordial black holes. The observation of these signatures of cosmological phase transitions together with the detection of a light dilaton would provide a strong hint of the fundamental role of scale invariance in particle physics.

  10. Discriminative phenomenological features of scale invariant models for electroweak symmetry breaking

    Directory of Open Access Journals (Sweden)

    Katsuya Hashino

    2016-01-01

    Full Text Available Classical scale invariance (CSI may be one of the solutions for the hierarchy problem. Realistic models for electroweak symmetry breaking based on CSI require extended scalar sectors without mass terms, and the electroweak symmetry is broken dynamically at the quantum level by the Coleman–Weinberg mechanism. We discuss discriminative features of these models. First, using the experimental value of the mass of the discovered Higgs boson h(125, we obtain an upper bound on the mass of the lightest additional scalar boson (≃543 GeV, which does not depend on its isospin and hypercharge. Second, a discriminative prediction on the Higgs-photon–photon coupling is given as a function of the number of charged scalar bosons, by which we can narrow down possible models using current and future data for the di-photon decay of h(125. Finally, for the triple Higgs boson coupling a large deviation (∼+70% from the SM prediction is universally predicted, which is independent of masses, quantum numbers and even the number of additional scalars. These models based on CSI can be well tested at LHC Run II and at future lepton colliders.

  11. Horizontal, anomalous U(1) symmetry for the more minimal supersymmetric standard model

    International Nuclear Information System (INIS)

    Nelson, A.E.; Wright, D.

    1997-01-01

    We construct explicit examples with a horizontal, open-quotes anomalousclose quotes U(1) gauge group, which, in a supersymmetric extension of the standard model, reproduce qualitative features of the fermion spectrum and CKM matrix, and suppress FCNC and proton decay rates without the imposition of global symmetries. We review the motivation for such open-quotes moreclose quotes minimal supersymmetric standard models and their predictions for the sparticle spectrum. There is a mass hierarchy in the scalar sector which is the inverse of the fermion mass hierarchy. We show in detail why ΔS=2 FCNCs are greatly suppressed when compared with naive estimates for nondegenerate squarks. copyright 1997 The American Physical Society

  12. The U(1)-Higgs model: critical behaviour in the confining-Higgs region

    International Nuclear Information System (INIS)

    Alonso, J.L.; Azcoiti, V.; Campos, I.; Ciria, J.C.; Cruz, A.; Iniguez, D.; Lesmes, F.; Piedrafita, C.; Rivero, A.; Tarancon, A.; Badoni, D.; Fernandez, L.A.; Munoz Sudupe, A.; Ruiz-Lorenzo, J.J.; Gonzalez-Arroyo, A.; Martinez, P.; Pech, J.; Tellez, P.

    1993-01-01

    We study numerically the critical properties of the U(1)-Higgs lattice model, with fixed Higgs modulus, in the region of small gauge coupling where the Higgs and confining phases merge. We find evidence for a first-order transition line that ends in a second-order point. By means of a rotation in parameter space we introduce thermodynamic magnitudes and critical exponents in close resemblance with simple models that show analogous critical behaviour. The measured data allow us to fit the critical exponents finding values in agreement with the mean-field prediction. The location of the critical point and the slope of the first-order line are accurately measured. (orig.)

  13. Oblique S and T constraints on electroweak strongly-coupled models with a light Higgs

    Energy Technology Data Exchange (ETDEWEB)

    Pich, A. [Departament de Física Teòrica, IFIC, Universitat de València - CSIC,Apt. Correus 22085, E-46071 València (Spain); Rosell, I. [Departament de Física Teòrica, IFIC, Universitat de València - CSIC,Apt. Correus 22085, E-46071 València (Spain); Departamento de Ciencias Físicas, Matemáticas y de la Computación,Universidad CEU Cardenal Herrera,c/ Sant Bartomeu 55, E-46115 Alfara del Patriarca, València (Spain); Sanz-Ciller, J.J. [Departamento de Física Teórica, Instituto de Física Teórica,Universidad Autónoma de Madrid - CSIC,c/ Nicolás Cabrera 13-15, E-28049 Cantoblanco, Madrid (Spain)

    2014-01-28

    Using a general effective Lagrangian implementing the chiral symmetry breaking SU(2){sub L}⊗SU(2){sub R}→SU(2){sub L+R}, we present a one-loop calculation of the oblique S and T parameters within electroweak strongly-coupled models with a light scalar. Imposing a proper ultraviolet behaviour, we determine S and T at next-to-leading order in terms of a few resonance parameters. The constraints from the global fit to electroweak precision data force the massive vector and axial-vector states to be heavy, with masses above the TeV scale, and suggest that the W{sup +}W{sup −} and ZZ couplings of the Higgs-like scalar should be close to the Standard Model value. Our findings are generic, since they only rely on soft requirements on the short-distance properties of the underlying strongly-coupled theory, which are widely satisfied in more specific scenarios.

  14. Study of higher order cumulant expansion of U(1) lattice gauge model at finite temperature

    International Nuclear Information System (INIS)

    Zheng Xite; Lei Chunhong; Li Yuliang; Chen Hong

    1993-01-01

    The order parameter, Polyakov line , of the U(1) gauge model on N σ 3 x N τ (N τ = 1) lattice by using the cumulant expansion is calculated to the 5-th order. The emphasis is put on the behaviour of the cumulant expansion in the intermediate coupling region. The necessity of higher order expansion is clarified from the connection between the cumulant expansion and the correlation length. The variational parameter in the n-th order calculation is determined by the requirement that corrections of the n-th order expansion to the zeroth order expansion finish. The agreement with the Monte Carlo simulation is obtained not only in the weak and strong coupling regions, but also in the intermediate coupling region except in the very vicinity of the phase transition point

  15. The factorized F-matrices for arbitrary U(1)(N-1) integrable vertex models

    International Nuclear Information System (INIS)

    Martins, M.J.; Pimenta, R.A.; Zuparic, M.

    2012-01-01

    We discuss the F-matrices associated to the R-matrix of a general N-state vertex model whose statistical configurations encode N-1U(1) symmetries. The factorization condition is shown for arbitrary weights being based only on the unitarity property and the Yang-Baxter relation satisfied by the R-matrix. Focusing on the N=3 case we are able to conjecture the structure of some relevant twisted monodromy matrix elements for general weights. We apply this result providing the algebraic expressions of the domain wall partition functions built up in terms of the creation and annihilation monodromy fields. For N=3 we also exhibit a R-matrix whose weights lie on a del Pezzo surface and have a rather general structure.

  16. Constraints on abelian extensions of the Standard Model from two-loop vacuum stability and U(1){sub B−L}

    Energy Technology Data Exchange (ETDEWEB)

    Corianò, Claudio [STAG Research Centre and Mathematical Sciences,University of Southampton, Southampton SO17 1BJ (United Kingdom); Dipartimento di Matematica e Fisica “Ennio De Giorgi' ,Università del Salento and INFN - Sezione di Lecce,Via Arnesano, 73100 Lecce (Italy); Rose, Luigi Delle; Marzo, Carlo [Dipartimento di Matematica e Fisica “Ennio De Giorgi' ,Università del Salento and INFN - Sezione di Lecce,Via Arnesano, 73100 Lecce (Italy)

    2016-02-19

    We present a renormalization group study of the scalar potential in a minimal U(1){sub B−L} extension of the Standard Model involving one extra heavier Higgs and three heavy right-handed neutrinos with family universal B-L charge assignments. We implement a type-I seesaw for the masses of the light neutrinos of the Standard Model. In particular, compared to a previous study, we perform a two-loop extension of the evolution, showing that two-loop effects are essential for the study of the stability of the scalar potential up to the Planck scale. The analysis includes the contribution of the kinetic mixing between the two abelian gauge groups, which is radiatively generated by the evolution, and the one-loop matching conditions at the electroweak scale. By requiring the stability of the potential up to the Planck mass, significant constraints on the masses of the heavy neutrinos, on the gauge couplings and the mixing in the Higgs sector are identified.

  17. 2004-2005 Academic Training Programme: Electroweak Theory and the Standard Model

    CERN Multimedia

    Françoise Benz

    2004-01-01

    6, 7, 8, 9 and 10 December LECTURE SERIES 6, 7, 8, 9, 10 December from 11:00 to 12:00 - Main Auditorium, bldg. 500 on 6, 7, 8, 10 December, TH Auditorium, bldg. 4 3-006 on 9 December Electroweak Theory and the Standard Model R. BARBIERI / CERN-PH-TH There is a natural splitting in four sectors of the theory of the ElectroWeak (EW) Interactions, at pretty different levels of development /test. Accordingly, the 5 lectures are organized as follows, with an eye to the future: Lecture 1: The basic structure of the theory; Lecture 2: The gauge sector; Lecture 3: The flavor sector; Lecture 4: The neutrino sector; Lecture 5: The EW symmetry breaking sector. Transparencies available at: http://agenda.cern.ch/fullAgenda.php?ida=a042577 ENSEIGNEMENT ACADEMIQUE ACADEMIC TRAINING Françoise Benz 73127 academic.training@cern.ch If you wish to participate in one of the following courses, please discuss with your supervisor and apply electronically directly from the course description pages that can ...

  18. 2004-2005 Academic Training Programme: Electroweak Theory and the Standard Model

    CERN Multimedia

    Françoise Benz

    2004-01-01

    6, 7, 8, 9 and 10 December LECTURE SERIES 6, 7, 8, 9, 10 December from 11:00 to 12:00 - Main Auditorium, bldg. 500 on 6, 7, 8, 10 December, TH Auditorium, bldg. 4 3-006 on 9 December Electroweak Theory and the Standard Model R. BARBIERI / CERN-PH-TH There is a natural splitting in four sectors of the theory of the ElectroWeak (EW) Interactions, at pretty different levels of development /test. Accordingly, the 5 lectures are organized as follows, with an eye to the future: Lecture 1: The basic structure of the theory; Lecture 2: The gauge sector; Lecture 3: The flavor sector; Lecture 4: The neutrino sector; Lecture 5: The EW symmetry breaking sector. ENSEIGNEMENT ACADEMIQUE ACADEMIC TRAINING Françoise Benz 73127 academic.training@cern.ch Si vous désirez participer à l'un des cours suivants, veuillez en discuter avec votre superviseur et vous inscrire électroniquement en direct depuis les pages de description des cours dans le Web que vous trouvez &ag...

  19. A model of neutrino and Higgs physics at the electroweak scale

    International Nuclear Information System (INIS)

    Aranda, Alfredo; Blanno, Omar; Diaz-Cruz, J. Lorenzo

    2008-01-01

    We present and explore the Higgs physics of a model that in addition to the Standard Model fields includes a lepton number violating singlet scalar field. Based on the fact that the only experimental data we have so far for physics beyond the Standard Model is that of neutrino physics, we impose a constraint for any addition not to introduce new higher scales. As such, we introduce right-handed neutrinos with an electroweak scale mass. We study the Higgs decay H→νν and show that it leads to different signatures compared to those in the Standard Model, making it possible to detect them and to probe the nature of their couplings

  20. Minimal anomalous U(1) theories and collider phenomenology

    Science.gov (United States)

    Ekstedt, Andreas; Enberg, Rikard; Ingelman, Gunnar; Löfgren, Johan; Mandal, Tanumoy

    2018-02-01

    We study the collider phenomenology of a neutral gauge boson Z ' arising in minimal but anomalous U(1) extensions of the Standard Model (SM). To retain gauge invariance of physical observables, we consider cancellation of gauge anomalies through the Green-Schwarz mechanism. We categorize a wide class of U(1) extensions in terms of the new U(1) charges of the left-handed quarks and leptons and the Higgs doublet. We derive constraints on some benchmark models using electroweak precision constraints and the latest 13 TeV LHC dilepton and dijet resonance search data. We calculate the decay rates of the exotic and rare one-loop Z ' decays to ZZ and Z-photon modes, which are the unique signatures of our framework. If observed, these decays could hint at anomaly cancellation through the Green-Schwarz mechanism. We also discuss the possible observation of such signatures at the LHC and at future ILC colliders.

  1. Algebraic Bethe ansatz for U(1) invariant integrable models: Compact and non-compact applications

    International Nuclear Information System (INIS)

    Martins, M.J.; Melo, C.S.

    2009-01-01

    We apply the algebraic Bethe ansatz developed in our previous paper [C.S. Melo, M.J. Martins, Nucl. Phys. B 806 (2009) 567] to three different families of U(1) integrable vertex models with arbitrary N bond states. These statistical mechanics systems are based on the higher spin representations of the quantum group U q [SU(2)] for both generic and non-generic values of q as well as on the non-compact discrete representation of the SL(2,R) algebra. We present for all these models the explicit expressions for both the on-shell and the off-shell properties associated to the respective transfer matrices eigenvalue problems. The amplitudes governing the vectors not parallel to the Bethe states are shown to factorize in terms of elementary building blocks functions. The results for the non-compact SL(2,R) model are argued to be derived from those obtained for the compact systems by taking suitable N→∞ limits. This permits us to study the properties of the non-compact SL(2,R) model starting from systems with finite degrees of freedom.

  2. Algebraic Bethe ansatz for U(1) invariant integrable models: Compact and non-compact applications

    Science.gov (United States)

    Martins, M. J.; Melo, C. S.

    2009-10-01

    We apply the algebraic Bethe ansatz developed in our previous paper [C.S. Melo, M.J. Martins, Nucl. Phys. B 806 (2009) 567] to three different families of U(1) integrable vertex models with arbitrary N bond states. These statistical mechanics systems are based on the higher spin representations of the quantum group U[SU(2)] for both generic and non-generic values of q as well as on the non-compact discrete representation of the SL(2,R) algebra. We present for all these models the explicit expressions for both the on-shell and the off-shell properties associated to the respective transfer matrices eigenvalue problems. The amplitudes governing the vectors not parallel to the Bethe states are shown to factorize in terms of elementary building blocks functions. The results for the non-compact SL(2,R) model are argued to be derived from those obtained for the compact systems by taking suitable N→∞ limits. This permits us to study the properties of the non-compact SL(2,R) model starting from systems with finite degrees of freedom.

  3. Enhancement of neutral tc transitions in the model of dynamical breaking of electroweak symmetry

    International Nuclear Information System (INIS)

    Arbuzov, B.A.; Osipov, M.Yu.

    1999-01-01

    The problem of possible deviations from the standard model is considered in the framework of a variant of dynamical electroweak symmetry breaking. It comes clear, that the parameters of the theory, being obtained earlier and describing deviations from standard model in Z → b-barb decay, are also consistent with the existence of a nontrivial solution for vertex t-bar (Z, γ)c. The occurrence of this solution leads to a significant enhancement in neutral flavor changing transition t → c. The intensity of this transition is connected with the c-quark mass, that leads to estimates of probabilities of exotic decays t → c(Z, γ) and of the cross section of a single t-quark production in process e + e - → tc-bar, which threshold is already overcome at LEP2. The model is shown to be consistent with the totality of the existing data, the predictions allow its unambiguous check [ru

  4. An introduction to relativistic processes and the standard model of electroweak interactions

    CERN Document Server

    Becchi, Carlo Maria

    2006-01-01

    These notes are designed as a guide-line for a course in Elementary Particle Physics for undergraduate students. The purpose is providing a rigorous and self-contained presentation of the theoretical framework and of the phenomenological aspects of the physics of interactions among fundamental constituents of matter. The first part of the volume is devoted to the description of scattering processes in the context of relativistic quantum field theory. The use of the semi-classical approximation allows us to illustrate the relevant computation techniques in a reasonably small amount of space. Our approach to relativistic processes is original in many respects. The second part contains a detailed description of the construction of the standard model of electroweak interactions, with special attention to the mechanism of particle mass generation. The extension of the standard model to include neutrino masses is also described. We have included a number of detailed computations of cross sections and decay rates of...

  5. Radiatively Generating the Higgs Potential and Electroweak Scale via the Seesaw Mechanism.

    Science.gov (United States)

    Brivio, Ilaria; Trott, Michael

    2017-10-06

    The minimal seesaw scenario can radiatively generate the Higgs potential to induce electroweak symmetry breaking while supplying an origin of the Higgs vacuum expectation value from an underlying Majorana scale. If the Higgs potential and (derived) electroweak scale have this origin, the heavy SU(3)×SU(2)×U(1)_{Y} singlet states are expected to reside at m_{N}∼10-500  PeV for couplings |ω|∼10^{-4.5}-10^{-6} between the Majorana sector and the standard model. In this framework, the usual challenge of the electroweak scale hierarchy problem with a classically assumed potential is absent as the electroweak scale is not a fundamental scale. The new challenge is the need to generate or accommodate PeV Majorana mass scales while simultaneously suppressing tree-level contributions to the potential in ultraviolet models.

  6. Fundamental composite electroweak dynamics

    DEFF Research Database (Denmark)

    Arbey, Alexandre; Cacciapaglia, Giacomo; Cai, Haiying

    2017-01-01

    Using the recent joint results from the ATLAS and CMS collaborations on the Higgs boson, we determine the current status of composite electroweak dynamics models based on the expected scalar sector. Our analysis can be used as a minimal template for a wider class of models between the two limitin...... space at the effective Lagrangian level. We show that a wide class of models of fundamental composite electroweak dynamics are still compatible with the present constraints. The results are relevant for the ongoing and future searches at the Large Hadron Collider....

  7. A family-universal anomalous U(1) in string models as the origin of supersymmetry breaking and squark degeneracy

    International Nuclear Information System (INIS)

    Faraggi, A.E.; Pati, J.C.

    1997-12-01

    Recently a promising mechanism for supersymmetry breaking that utilizes both an anomalous U(1) gauge symmetry and an effective mass term m ∼ 1TeV of certain relevant fields has been proposed. In this paper we examine whether such a mechanism can emerge in superstring derived free fermionic models. We observe that certain three generation string solutions, though not all, lead to an anomalous U(1) which couples universally to all three families. The advantages of this three-family universality of U(1) A , compared to the two-family case, proposed in earlier works, in yielding squark degeneracy, while avoiding radiative breaking of color and charge, are noted. The root cause of the flavor universality of U(1) A is the cyclic permutation symmetry that characterizes the Z 2 x Z 2 orbifold compactification with standard embedding, realized in the free fermionic models by the NAHE set. It is shown that nonrenormalizable terms which contain hidden-sector condensates, generate the required suppression of the relevant mass term m, compared to the Planck scale. While the D-term of the family universal U(1) A leads to squark degeneracy, those of the family dependent U(1)'s, remarkably enough, are found to vanish for the solutions considered, owing to minimization of the potential

  8. Commutator of the quark mass matrices in the standard electroweak model and a measure of maximal CP-violation

    International Nuclear Information System (INIS)

    Jarlskog, C.

    1985-06-01

    The structure of the quark mass matrices in the Standard Electroweak Model is investigated. The commutator of the quark mass matrices is found to provide a conventional independent measure of CP-violation. The question of maximal CP-violation is discussed. The present experimental data indicate that CP is nowhere maximally violated. (author)

  9. Collective modes of the Nambu--Jona-Lasinio model with an external U(1) gauge field

    International Nuclear Information System (INIS)

    Klevansky, S.P.; Jaenicke, J.; Lemmer, R.H.

    1991-01-01

    The effect of external color fields on the collective modes of the SU L (2)xSU R (2) chiral flavor version of the Nambu--Jona-Lasinio model is studied analytically in a U(1) approximation to the gauge fields. We show that the scalar and pseudoscalar modes respond differently to external chromomagnetic and -electric fields. In the former case, in which chiral asymmetry is enhanced, the modes remain well separated and vary slowly with the field, while in the latter case the scalar mode drops rapidly to become degenerate with the pseudoscalar mode in the chiral limit. In this regime, both modes are weakly coupled to quark matter, and the pseudoscalar pion mode in particular survives as a well-defined excitation as it enters the pair continuum. The Goldberger-Treiman relation, which is shown to hold in the presence of external fields, is responsible for this behavior. Chromoelectric and -magnetic polarizabilities are seen to be equal and opposite with absolute values β σ =2.0α s and β π =0.03α s for the scalar and pseudoscalar modes respectively

  10. Electroweak symmetry breaking and collider signatures in the next-to-minimal composite Higgs model

    Science.gov (United States)

    Niehoff, Christoph; Stangl, Peter; Straub, David M.

    2017-04-01

    We conduct a detailed numerical analysis of the composite pseudo-Nambu-Goldstone Higgs model based on the next-to-minimal coset SO(6)/SO(5) ≅ SU(4)/Sp(4), featuring an additional SM singlet scalar in the spectrum, which we allow to mix with the Higgs boson. We identify regions in parameter space compatible with all current exper-imental constraints, including radiative electroweak symmetry breaking, flavour physics, and direct searches at colliders. We find the additional scalar, with a mass predicted to be below a TeV, to be virtually unconstrained by current LHC data, but potentially in reach of run 2 searches. Promising indirect searches include rare semi-leptonic B decays, CP violation in B s mixing, and the electric dipole moment of the neutron.

  11. A bag model calculation of the electroweak s → dγ loop

    International Nuclear Information System (INIS)

    Eeg, J.O.; Ruud, J.Aa.

    1990-10-01

    The CP-conservering electroweak transitions s → dγ have been considered. In order to include confinement effects below the charm scale, the loop calculations within the bag model were performed. According to the calculations, confinement effects are rather important and give amplitudes three orders of magnitude larger than those obtained from the free quark loop, which is ∼eG F m c 2 /M W 2 . Moreover, the amplitude is of the same order of magnitude as the perturbative two-loop amplitude ∼eG F α s ln(m c /μ). For the decay mode Ω - → γΞ - , a branching ratio 4.4 x 10 -5 was obtained. Other radiative decays of strange baryons are known to be dominated by pole diagrams. 14 refs., 1 fig

  12. Electroweak symmetry breaking and collider signatures in the next-to-minimal composite Higgs model

    Energy Technology Data Exchange (ETDEWEB)

    Niehoff, Christoph; Stangl, Peter; Straub, David M. [Excellence Cluster Universe, TUM,Boltzmannstr. 2, 85748 Garching (Germany)

    2017-04-20

    We conduct a detailed numerical analysis of the composite pseudo-Nambu-Goldstone Higgs model based on the next-to-minimal coset SO(6)/SO(5)≅SU(4)/Sp(4), featuring an additional SM singlet scalar in the spectrum, which we allow to mix with the Higgs boson. We identify regions in parameter space compatible with all current experimental constraints, including radiative electroweak symmetry breaking, flavour physics, and direct searches at colliders. We find the additional scalar, with a mass predicted to be below a TeV, to be virtually unconstrained by current LHC data, but potentially in reach of run 2 searches. Promising indirect searches include rare semi-leptonic B decays, C P violation in B{sub s} mixing, and the electric dipole moment of the neutron.

  13. Boson-fermion mass splittings in four-dimensional heterotic string models with anomalous U(1) gauge groups

    International Nuclear Information System (INIS)

    Yamaguchi, Masahiro; Yamamoto, Hisashi; Onogi, Tetsuya

    1989-01-01

    In four-dimensional heterotic string models with anomalous U(1) gauge groups, space-time supersymmetry (SUSY) breaks down spontaneously at one loop. In this paper, the Ward-Takahashi identity of broken SUSY in one-loop two-point amplitudes is investigated in all generalities. The boson-fermion mass splitting of any supersymmetric pair in an arbitrary model is proportional to the product of the D-term expectation value (the sum of (chirality)x(U(1) charge) of massless fermions in the model) and the U(1) charge of the external particle. In order to give a better understanding of the results, we present some examples of the mass splittings in a simple Z 3 orbifold model. (orig.)

  14. Multi-parameter variational calculations for the (2+1)-dimensional U(1) lattice gauge theory and the XY model

    International Nuclear Information System (INIS)

    Heys, D.W.; Stump, D.R.

    1987-01-01

    Variational calculations are described that use multi-parameter trial wave functions for the U(1) lattice gauge theory in two space dimensions, and for the XY model. The trial functions are constructed as the exponential of a linear combination of states from the strong-coupling basis of the model, with the coefficients treated as variational parameters. The expectation of the hamiltonian is computed by the Monte Carlo method, using a reweighting technique to evaluate expectation values in finite patches of the parameter space. The trial function for the U(1) gauge theory involves six variational parameters, and its weak-coupling behaviour is in reasonable agreement with theoretical expectations. (orig.)

  15. Phenomenological constraints imposed by the hidden sector in the flipped SU(5)xU(1) superstring model

    Energy Technology Data Exchange (ETDEWEB)

    Leontaris, G.K.; Rizos, J.; Tamvakis, K. (Ioannina Univ. (Greece). Theoretical Physics Div.)

    1990-06-28

    We calculate the trilinear superpotential of the hidden sector of the three generation flipped SU(5)xU(1)xU(1){sup 4}xSO(10)xSU(4) superstring model. We perform a renormalization group analysis of the model taking into account the hidden sector. We find that, in all relevant cases, fractionally charged tetraplets of the hidden SO(6) gauge group are confined at a high scale. Nevertheless, their contribution to the observable U(1) gauge coupling evolution results in a drastic reduction of the available freedom in the values of a{sub 3}(m{sub w}), sin{sup 2}{theta}{sub w} and M{sub x} that allow superunification. (orig.).

  16. Higher-spin cluster algorithms: the Heisenberg spin and U(1) quantum link models

    Energy Technology Data Exchange (ETDEWEB)

    Chudnovsky, V

    2000-03-01

    I discuss here how the highly-efficient spin-1/2 cluster algorithm for the Heisenberg antiferromagnet may be extended to higher-dimensional representations; some numerical results are provided. The same extensions can be used for the U(1) flux cluster algorithm, but have not yielded signals of the desired Coulomb phase of the system.

  17. Higher-spin cluster algorithms: the Heisenberg spin and U(1) quantum link models

    International Nuclear Information System (INIS)

    Chudnovsky, V.

    2000-01-01

    I discuss here how the highly-efficient spin-1/2 cluster algorithm for the Heisenberg antiferromagnet may be extended to higher-dimensional representations; some numerical results are provided. The same extensions can be used for the U(1) flux cluster algorithm, but have not yielded signals of the desired Coulomb phase of the system

  18. A composite model of electroweak interactions and its manifestation at current collider energies

    International Nuclear Information System (INIS)

    Craigie, N.S.

    1984-05-01

    We present a preon model based on an ASF confining gauge theory, which has as a low energy effective Lagrangian, an electroweak gauge theory very close to the standard model. However, it is predicted that there are some specific and necessary deviations from the Glashow-Salam-Weinberg model. In this preon model, we assume a spontaneous breakdown (or an induced breakdown) of the left-right symmetry, which prevents spin-one composites made up of right-handed fermions propagating well below the composite scale of order 1 TeV. A consequence of this assumption is shown to be the existence of a pion-like scalar, in addition to the Higgs particle of the standard model. Such a particle - it is further claimed - can give rise to single photon events, through a large branching ratio into the channel π → Z γ or if lighter than the Z through Z → π(→νν-bar) + γ. The model also predicts a signal very similar to the associated gluino production one of supersymmetric grand unified theories. (author)

  19. Dark U (1)

    International Nuclear Information System (INIS)

    Chang, Chia-Feng; Ma, Ernest; Yuan, Tzu-Chiang

    2015-01-01

    In this talk we will explore the possibility of adding a local U(1) dark sector to the standard model with the Higgs boson as a portal connecting the visible standard model sector and the dark one. We will discuss existing experimental constraint on the model parameters from the invisible width of Higgs decay. Implications of such a dark U(1) sector on phenomenology at the Large Hardon Collider will be addressed. In particular, detailed results for the non-standard signals of multi-lepton-jets that arise from this simple dark sector will be presented. (paper)

  20. Electroweak chiral Lagrangian from the topcolor-assisted technicolor model with nontrivial technicolor fermion condensation and walking

    International Nuclear Information System (INIS)

    Ge Fengjun; Jiang Shaozhou; Wang Qing

    2011-01-01

    The electroweak chiral Lagrangian for the topcolor-assisted technicolor model proposed by K. Lane, which uses nontrivial patterns of techniquark condensation and walking, was investigated in this study. We found that the features of the model are qualitatively similar to those of Lane's previous natural topcolor-assisted technicolor prototype model, but there is no limit on the upper bound of the Z ' mass. We discuss the phase structure and possible walking behavior of the model. We obtained the values of all coefficients of the electroweak chiral Lagrangian up to an order of p 4 . We show that although the walking effect reduces the S parameter to half its original value, it maintains an order of 2. Moreover, a special hypercharge arrangement is needed to achieve further reductions in its value.

  1. Gauge symmetry breaking in the hidden sector of the flipped SU(5)xU(1) superstring model

    Energy Technology Data Exchange (ETDEWEB)

    Antoniadis, I.; Rizos, J. (Centre de Physique Theorique, Ecole Polytechnique, 91 - Palaiseau (France)); Tamvakis, K. (Theoretical Physics Div., Univ. Ioannina (Greece))

    1992-03-26

    We analyze the SU(5)xU(1)'xU(1){sup 4}xSO(10)xSU(4) superstring model with a spontaneously broken hidden sector down to SO(7)xSO(5) taking into account non-renormalizable superpotential terms up to eight order. As a result of the hidden sector breaking the 'exotic' states get a mass and the 'observable' spectrum is composed of the standard three families. In addition, Cabibbo mixing arises at sixth order and an improved fermion mass hierarchy emerges. (orig.).

  2. Z → bb-bar probability and asymmetry in a model of dynamical electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Arbuzov, B.A.; Osipov, M.Yu.

    1997-01-01

    The deviations from the standard model in the probability of Z → bb-bar decay and in the forward-backward asymmetry in the reaction e + e - → bb-bar are studied in the framework of the model of dynamical electroweak symmetry breaking, the basic point of which is the existence of a triple anomalous W-boson vertex in a region of momenta restricted by a cutoff. A set of equations for additional terms in the W b t-bar vertex is obtained and its solution to the process Z → bb-bar is applied. It is shown that it is possible to obtain a consistent description of both deviations, which is quite nontrivial because these effects are not simply correlated. The necessary value of the anomalous W interaction coupling, λ = -0.22 ± 0.01, is consistent with existing limitations and leads to definite predictions, e.g., for pair W production in e + e - collisions at LEP 200

  3. Constructive tensorial group field theory I: The {U(1)} -{T^4_3} model

    Science.gov (United States)

    Lahoche, Vincent

    2018-05-01

    The loop vertex expansion (LVE) is a constructive technique using canonical combinatorial tools. It works well for quantum field theories without renormalization, which is the case of the field theory studied in this paper. Tensorial group field theories (TGFTs) are a new class of field theories proposed to quantize gravity. This paper is devoted to a very simple TGFT for rank three tensors with U(1) group and quartic interactions, hence nicknamed -. It has no ultraviolet divergence, and we show, with the LVE, that it is Borel summable in its coupling constant.

  4. Strong Electroweak Symmetry Breaking

    CERN Document Server

    Grinstein, Benjamin

    2011-01-01

    Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...

  5. The complete electroweak effect and perfection of Bhabha scattering in the standard model

    International Nuclear Information System (INIS)

    Shi Chengye; Fang Zhenyun; Chen Xuewen

    2013-01-01

    In this paper, we make a close and systematic research on Bhabha scattering in the electroweak unification of the standard model (SM). In concrete research methods we make the quantum field theory of perturbation theory in a new computing mode -renormalization chain propagation theory, and do an application to the Bhabha scattering calculation research. In SM, in order to consider complete electrical weak effect about Bhabha scattering internal process, we seek out the complex renormalization mixing-loop chain propagators constituted by photon y and intermediate boson Z 0 , and then calculate the Bhabha scattering cross section about this kind of propagator by transfer complete electrical weak reaction. Within the observed errors, the calculation results are in good agreement with the experimental values. Also, the main research results not only confirm the action of the particle reaction accuracy by SM theory for describing the electrical weak effect; but also suggests the SM theory may be a per ect theory and that the theory prophecy's Higgs 'mysterious particles' (which is of particular concern in the field of academic) have the large possibility to be eventually found. (authors)

  6. Some new contributions to neutrinoless double β-decay in an SU(2)xU(1) model

    International Nuclear Information System (INIS)

    Escobar, C.O.

    1982-11-01

    An SU(2) x U(1) model having both Dirac and Majorana mass terms for the neutrinos, with an extended Higgs sector without natural flavor conservation is considered. Under these conditions, it is shown that for a certain range of the mass parameters of the model, some new contributions become important for the neutrinoless double β-decay (ββ)oν. (Author) [pt

  7. Tests of the electroweak standard model and measurement of the weak mixing angle with the ATLAS detector

    CERN Document Server

    Goebel, Martin; Mnich, Joachim; Schleper, Peter

    In this thesis the global Standard Model (SM) fit to the electroweak precision observables is revisited with respect to newest experimental results. Various consistency checks are performed showing no significant deviation from the SM. The Higgs boson mass is estimated by the electroweak fit to be MH = 94+30−24 GeV without any information from direct Higgs searches at LEP, Tevatron, and the LHC and the result is MH = 125+8−10 GeV when including the direct Higgs mass constraints. The strong coupling constant is extracted at fourth perturbative order as αs(M2Z) = 0.1194 ± 0.0028 (exp) ± 0.0001 (theo). From the fit including the direct Higgs constraints the effective weak mixing angle is determined indirectly to be sin2 θleff = 0.23147+0.00012−0.00010. For the W mass the value of MW = 80.360+0.012−0.011 GeV is obtained indirectly from the fit including the direct Higgs constraints. The electroweak precision data is also exploited to constrain new physics models by using the concept of oblique paramet...

  8. Flavor physics in the Randall-Sundrum model I. Theoretical setup and electroweak precision tests

    International Nuclear Information System (INIS)

    Casagrande, S.; Goertz, F.; Haisch, U.; Neubert, M.; Pfoh, T.

    2008-01-01

    A complete discussion of tree-level flavor-changing effects in the Randall-Sundrum (RS) model with brane-localized Higgs sector and bulk gauge and matter fields is presented. The bulk equations of motion for the gauge and fermion fields, supplemented by boundary conditions taking into account the couplings to the Higgs sector, are solved exactly. For gauge fields the Kaluza-Klein (KK) decomposition is performed in a covariant R ξ gauge. For fermions the mixing between different generations is included in a completely general way. The hierarchies observed in the fermion spectrum and the quark mixing matrix are explained naturally in terms of anarchic five-dimensional Yukawa matrices and wave-function overlap integrals. Detailed studies of the flavor-changing couplings of the Higgs boson and of gauge bosons and their KK excitations are performed, including in particular the couplings of the standard W ± and Z 0 bosons. A careful analysis of electroweak precision observables including the S and T parameters and the Z 0 b b-bar couplings shows that the simplest RS model containing only Standard Model particles and their KK excitations is consistent with all experimental bounds for a KK scale as low as a few TeV, if one allows for a heavy Higgs boson (m h ∼ ± bosons, tree-level flavor-changing neutral current couplings of the Z 0 and Higgs bosons, the rare decays t → c(u)Z 0 and t → c(u)h, and the flavor mixing among KK fermions. The results obtained in this work form the basis for general calculations of flavor-changing processes in the RS model and its extensions.

  9. Calculation of the top quark mass in the flipped SU(5)xU(1) superstring model

    Energy Technology Data Exchange (ETDEWEB)

    Leontaris, G.K.; Rizos, J.; Tamvakis, K. (Ioannina Univ. (Greece). Dept. of Physics)

    1990-11-08

    We present a complete renormalization group calculation of the top-quark mass in the SU(5)xU(1) superstring model. We solve the coupled renormalization group equations for the gauge and Yukawa couplings in the two-loop approximation and obtain the top-quark mass as a function of two parameters of the model which could be chosen to be ratios of singlet VEVs associated with the surplus (U(1)){sup 4} breaking. We obtain a heavy top-quark with 150 GeV{le}m{sub t}<200 GeV, for most part of the parameter space, while lower values are possible only in a very small extremal region. We also compute the allowed range of unification parameters (M{sub x}, sin{sup 2}{theta}{sub w}, {alpha}{sub 3}(M{sub W})) in the presence of a heavy top-quark. (orig.).

  10. SU(n)c x SU(m)L x U(1)N generalizations of the standard model

    International Nuclear Information System (INIS)

    Pleitez, V.

    1993-01-01

    Generalizations of the Standard Model which are based on the gauge symmetry SU(n) c x SU(m) L x U(1) N are considered. Although the most interesting possibility occurs when n = 3, it will be considered also the cases n = 4,5, both with m = 3,4. It will also be given possible grand unification scenarios. (author). 18 refs

  11. Electroweak Physics at the LHC

    CERN Document Server

    Sommer, Philip; The ATLAS collaboration

    2018-01-01

    With the large integrated luminosities recorded at the LHC and the excellent understanding of the LHC detectors, it is possible to measure electroweak observables to the highest precision. A review of the measurement of the $W$ boson mass by the ATLAS Collaboration as well as a new measurement of the electroweak mixing angle with the CMS detector are presented. Special emphasis is put on a discussion of the modelling uncertainties and the potential of the latest low-$\\mu$ runs, recorded at the end of 2017 by both collaboration. In addition, the latest measurements of multi-boson final states as well as the electroweak production of single gauge bosons at 13 TeV are summarised. The study of these processes can be used to constrain anomalous gauge couplings in an effective field theory approach, allowing to bridge tests of the electroweak sector of the Standard Models also to Higgs boson production.

  12. Electroweak Physics at the LHC

    CERN Document Server

    Sommer, Philip; The ATLAS collaboration

    2018-01-01

    With the high integrated luminosities recorded at the LHC and the very good understanding of the LHC detectors, it is possible to measure electroweak observables to the highest precision. In this talk, we review the measurement of the W boson mass by the ATLAS Collaboration as well as the new measurement of the electroweak mixing angle with the CMS detector. Special focus is drawn on a discussion of the modeling uncertainties and the physics potential of the latest low-mu runs, recorded at the end of 2017 by both collaboration. In addition, we will present the latest measurements of multi-boson final states as well as the electroweak production of single gauge bosons at 13 TeV. The study of these processes can be used to constrain anomalous gauge couplings in an effective field theory approach, allowing to bridge tests of the electroweak sector of the Standard Models also to the Higgs-boson production.

  13. FIMP and muon (g−2) in a U(1){sub L{sub μ−L{sub τ}}} model

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Anirban [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019 (India); Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India); Choubey, Sandhya [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019 (India); Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India); Department of Theoretical Physics, School of Engineering Sciences, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm (Sweden); Khan, Sarif [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019 (India); Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India)

    2017-02-23

    The tightening of the constraints on the standard thermal WIMP scenario has forced physicists to propose alternative dark matter (DM) models. One of the most popular alternate explanations of the origin of DM is the non-thermal production of DM via freeze-in. In this scenario the DM never attains thermal equilibrium with the thermal soup because of its feeble coupling strength (∼ 10{sup −12}) with the other particles in the thermal bath and is generally called the Feebly Interacting Massive Particle (FIMP). In this work, we present a gauged U(1){sub L{sub μ−L{sub τ}}} extension of the Standard Model (SM) which has a scalar FIMP DM candidate and can consistently explain the DM relic density bound. In addition, the spontaneous breaking of the U(1){sub L{sub μ−L{sub τ}}} gauge symmetry gives an extra massive neutral gauge boson Z{sub μτ} which can explain the muon (g−2) data through its additional one-loop contribution to the process. Lastly, presence of three right-handed neutrinos enable the model to successfully explain the small neutrino masses via the Type-I seesaw mechanism. The presence of the spontaneously broken U(1){sub L{sub μ−L{sub τ}}} gives a particular structure to the light neutrino mass matrix which can explain the peculiar mixing pattern of the light neutrinos.

  14. Light U(1) gauge boson coupled to baryon number

    International Nuclear Information System (INIS)

    Carone, C.D.; Murayama, Hitoshi

    1995-06-01

    The authors discuss the phenomenology of a light U(1) gauge boson, γ B , that couples only to baryon number. Gauging baryon number at high energies can prevent dangerous baryon-number violating operators that may be generated by Planck scale physics. However, they assume at low energies that the new U(1) gauge symmetry is spontaneously broken and that the γ B mass m B is smaller than m z . They show for m Υ B z that the γB coupling α B can be as large as ∼ 0.1 without conflicting with the current experimental constraints. The authors argue that α B ∼ 0.1 is large enough to produce visible collider signatures and that evidence for the γ B could be hidden in existing LEP data. They show that there are realistic models in which mixing between the γ B and the electroweak gauge bosons occurs only as a radiative effect and does not lead to conflict with precision electroweak measurements. Such mixing may nevertheless provide a leptonic signal for models of this type at an upgraded Tevatron

  15. Electroweak phase transition in the economical 3-3-1 model

    Energy Technology Data Exchange (ETDEWEB)

    Phong, Vo Quoc; Van, Vo Thanh; Minh, Le Hoang [Ho Chi Minh City University of Science, Department of Theoretical Physics, Ho Chi Minh City (Viet Nam); Long, Hoang Ngoc [Vietnamese Academy of Science and Technology, Institute of Physics, Hanoi (Viet Nam)

    2015-07-15

    We consider the EWPT in the economical 3-3-1 (E331) model. Our analysis shows that the EWPT in the model is a sequence of two first-order phase transitions, SU(3) → SU(2) at the TeV scale and SU(2) → U(1) at the 100 GeV scale. The EWPT SU(3) → SU(2) is triggered by the new bosons and the exotic quarks; its strength is about 1-13 if the mass ranges of these new particles are 10{sup 2}-10{sup 3} GeV. The EWPT SU(2) → U(1) is strengthened by only the new bosons; its strength is about 1-1.15 if the mass parts of H{sub 1}{sup 0}, H{sub 2}{sup ±} and Y{sup ±} are in the ranges 10-10{sup 2} GeV. The contributions of H{sub 1}{sup 0} and H{sub 2}{sup ±} to the strengths of both EWPTs may make them sufficiently strong to provide large deviations from thermal equilibrium and B violation necessary for baryogenesis. (orig.)

  16. A Combination of Preliminary Electroweak Measurements and Constraints on the Standard Model

    DEFF Research Database (Denmark)

    Hansen, Jørgen Beck

    2001-01-01

    This note presents a combination of published and preliminary electroweak results from the four LEP collaborations and the SLD collaboration which were prepared for the 2000 summer conferences. Averages from Z0 resonance results are derived for hadronic and leptonic cross sections, the leptonic f...

  17. Baryogenesis at the electroweak scale

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, A [Saha Inst. of Nuclear Physics, Calcutta (India); Mallik, S [Saha Inst. of Nuclear Physics, Calcutta (India)

    1995-10-01

    The generation of the baryon asymmetry of the universe is considered in the standard model of the electroweak theory with simple extensions of the Higgs sector. The propagation of quarks of masses up to about 5 GeV are considered, taking into account their markedly different dispersion relations due to propagation through the hot electroweak plasma. It is shown that the contribution of the b quark to the baryon asymmetry can be comparable to that for the t quark considered earlier. (orig.)

  18. Baryogenesis at the electroweak scale

    International Nuclear Information System (INIS)

    Kundu, A.; Mallik, S.

    1995-01-01

    The generation of the baryon asymmetry of the universe is considered in the standard model of the electroweak theory with simple extensions of the Higgs sector. The propagation of quarks of masses up to about 5 GeV are considered, taking into account their markedly different dispersion relations due to propagation through the hot electroweak plasma. It is shown that the contribution of the b quark to the baryon asymmetry can be comparable to that for the t quark considered earlier. (orig.)

  19. Quantum transport and electroweak baryogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Konstandin, Thomas

    2013-02-15

    We review the mechanism of electroweak baryogenesis. The main focus of the review lies on the development of quantum transport equations from first principles in the Kadanoff-Baym framework. We emphasize the importance of the semi-classical force that leads to reliable predictions in most cases. Besides, we discuss the status of electroweak baryogenesis in the light of recent electric dipole moment probes and collider experiments in a variety of models.

  20. Quantum transport and electroweak baryogenesis

    International Nuclear Information System (INIS)

    Konstandin, Thomas

    2013-02-01

    We review the mechanism of electroweak baryogenesis. The main focus of the review lies on the development of quantum transport equations from first principles in the Kadanoff-Baym framework. We emphasize the importance of the semi-classical force that leads to reliable predictions in most cases. Besides, we discuss the status of electroweak baryogenesis in the light of recent electric dipole moment probes and collider experiments in a variety of models.

  1. Electroweak physics at LEP2

    CERN Document Server

    Hemingway, Richard J

    2002-01-01

    On 2 November 2000 the LEP machine was finally closed after 12 years of glorious running. With the 4 operating detectors, ALEPH, DELPHI, L3, and OPAL, an enormous wealth of new data at the highest centre- of-mass energies has been recorded. These lectures will focus on aspects of electroweak physics within the energy span of LEP2, namely 130-209 GeV. All current data are in very good agreement with the electroweak standard model. (50 refs).

  2. Tests of the electroweak standard model and measurement of the weak mixing angle with the ATLAS detector

    International Nuclear Information System (INIS)

    Goebel, M.

    2011-09-01

    In this thesis the global Standard Model (SM) fit to the electroweak precision observables is revisted with respect to newest experimental results. Various consistency checks are performed showing no significant deviation from the SM. The Higgs boson mass is estimated by the electroweak fit to be M H =94 -24 +30 GeV without any information from direct Higgs searches at LEP, Tevatron, and the LHC and the result is M H =125 -10 +8 GeV when including the direct Higgs mass constraints. The strong coupling constant is extracted at fourth perturbative order as α s (M Z 2 )=0.1194±0.0028(exp)±0.0001 (theo). From the fit including the direct Higgs constraints the effective weak mixing angle is determined indirectly to be sin 2 θ l eff =0.23147 -0.00010 +0.00012 . For the W mass the value of M W =80.360 -0.011 +0.012 GeV is obtained indirectly from the fit including the direct Higgs constraints. The electroweak precision data is also exploited to constrain new physics models by using the concept of oblique parameters. In this thesis the following models are investigated: models with a sequential fourth fermion generation, the inert-Higgs doublet model, the littlest Higgs model with T-parity conservation, and models with large extra dimensions. In contrast to the SM, in these models heavy Higgs bosons are in agreement with the electroweak precision data. The forward-backward asymmetry as a function of the invariant mass is measured for pp→ Z/γ * →e + e - events collected with the ATLAS detector at the LHC. The data taken in 2010 at a center-of-mass energy of √(s)=7 TeV corresponding to an integrated luminosity of 37.4 pb -1 is analyzed. The measured forward-backward asymmetry is in agreement with the SM expectation. From the measured forward-backward asymmetry the effective weak mixing angle is extracted as sin 2 θ l eff =0.2204±.0071(stat) -0.0044 +0.0039 (syst). The impact of unparticles and large extra dimensions on the forward-backward asymmetry at large

  3. Tests of the electroweak standard model and measurement of the weak mixing angle with the ATLAS detector

    Energy Technology Data Exchange (ETDEWEB)

    Goebel, M.

    2011-09-15

    In this thesis the global Standard Model (SM) fit to the electroweak precision observables is revisted with respect to newest experimental results. Various consistency checks are performed showing no significant deviation from the SM. The Higgs boson mass is estimated by the electroweak fit to be M{sub H}=94{sub -24}{sup +30} GeV without any information from direct Higgs searches at LEP, Tevatron, and the LHC and the result is M{sub H}=125{sub -10}{sup +8} GeV when including the direct Higgs mass constraints. The strong coupling constant is extracted at fourth perturbative order as {alpha}{sub s}(M{sub Z}{sup 2})=0.1194{+-}0.0028(exp){+-}0.0001 (theo). From the fit including the direct Higgs constraints the effective weak mixing angle is determined indirectly to be sin{sup 2} {theta}{sup l}{sub eff}=0.23147{sub -0.00010}{sup +0.00012}. For the W mass the value of M{sub W}=80.360{sub -0.011}{sup +0.012} GeV is obtained indirectly from the fit including the direct Higgs constraints. The electroweak precision data is also exploited to constrain new physics models by using the concept of oblique parameters. In this thesis the following models are investigated: models with a sequential fourth fermion generation, the inert-Higgs doublet model, the littlest Higgs model with T-parity conservation, and models with large extra dimensions. In contrast to the SM, in these models heavy Higgs bosons are in agreement with the electroweak precision data. The forward-backward asymmetry as a function of the invariant mass is measured for pp{yields} Z/{gamma}{sup *}{yields}e{sup +}e{sup -} events collected with the ATLAS detector at the LHC. The data taken in 2010 at a center-of-mass energy of {radical}(s)=7 TeV corresponding to an integrated luminosity of 37.4 pb{sup -1} is analyzed. The measured forward-backward asymmetry is in agreement with the SM expectation. From the measured forward-backward asymmetry the effective weak mixing angle is extracted as sin{sup 2} {theta}{sup l

  4. Electroweak penguin B decays

    CERN Document Server

    Nikodem, Thomas

    2016-01-01

    Flavour Changing Neutral Currents (FCNC) are sensitive probes for physics beyond the Standard Model (SM), so-called New Physics. An example of a FCNC is the $b \\to s$ quark transition described by the electroweak penguin Feynman diagram shown in Figure 1. In the SM such FCNC are only allowed with a loop structure (as e:g: shown in the figure) and not by tree level processes. In the loops heavy particles appear virtually and do not need to be on shell. Therefore also not yet discovered heavy particles with up to a mass $\\mathcal{O}$(TeV) could virtually contribute significantly to observables. Several recent measurements of electroweak penguin B decays exhibit interesting tensions with SM predictions, most prominently in the angular observable $P'_5$ 5 of the decay $B^0 \\to K^{*0} \\mu^+ \\mu^1$[1], which triggered a lot of discussion in the theory community [2]-[14].

  5. Neutrino masses in the flipped SU(5) x U(1) and the SU(4) x O(4) GUT models

    Energy Technology Data Exchange (ETDEWEB)

    Ranfone, S.; Papageorgiu, E.

    1992-03-01

    We classify the different neutrino-mass pattern arising in string-inspired Grand Universal Theory (GUT) and supersymmetric GUT models based on the flipped SU(5)xU(1) and the SU(4)xO(4) gauge groups. Phenomenologically interesting spectra are obtained through the interplay of the two seesaw mechanisms present, with typical neutrino masses {approx}10{sup -3} eV in the supersymmetric GUT models and of order 0.1 - 10 KeV in the ordinary GUTs. (author).

  6. A minimal spontaneous CP violation model with small neutrino mass and SU(2) x U(1) x Z3 symmetry

    International Nuclear Information System (INIS)

    Geng, C.Q.; Ng, J.N.

    1988-04-01

    It is shown that spontaneous CP violation and natural flavor conservation can occur in the SU(2) L x U(1) Y model based on two Higgs doublet and one Higgs singlet fields with a Z 3 discrete symmetry. Physical CP nonconservation is purely due to scalar-pseudoscalar mixings. In order for this to be a major source of CP violation a light spin-O boson of mass less than 10 GeV is required. The see-saw mechanism can be implemented to generate small neutrino masses. The model implies a relatively large electric dipole moment for charged leptons and small value for ε'/ε

  7. Unanswered Questions in the Electroweak Theory

    Energy Technology Data Exchange (ETDEWEB)

    Quigg, Chris

    2009-11-01

    This article is devoted to the status of the electroweak theory on the eve of experimentation at CERN's Large Hadron Collider. A compact summary of the logic and structure of the electroweak theory precedes an examination of what experimental tests have established so far. The outstanding unconfirmed prediction of the electroweak theory is the existence of the Higgs boson, a weakly interacting spin-zero particle that is the agent of electroweak symmetry breaking, the giver of mass to the weak gauge bosons, the quarks, and the leptons. General arguments imply that the Higgs boson or other new physics is required on the TeV energy scale. Indirect constraints from global analyses of electroweak measurements suggest that the mass of the standard-model Higgs boson is less than 200 GeV. Once its mass is assumed, the properties of the Higgs boson follow from the electroweak theory, and these inform the search for the Higgs boson. Alternative mechanisms for electroweak symmetry breaking are reviewed, and the importance of electroweak symmetry breaking is illuminated by considering a world without a specific mechanism to hide the electroweak symmetry. For all its triumphs, the electroweak theory has many shortcomings.

  8. Unanswered Questions in the Electroweak Theory

    International Nuclear Information System (INIS)

    Quigg, Chris

    2009-01-01

    This article is devoted to the status of the electroweak theory on the eve of experimentation at CERN's Large Hadron Collider. A compact summary of the logic and structure of the electroweak theory precedes an examination of what experimental tests have established so far. The outstanding unconfirmed prediction of the electroweak theory is the existence of the Higgs boson, a weakly interacting spin-zero particle that is the agent of electroweak symmetry breaking, the giver of mass to the weak gauge bosons, the quarks, and the leptons. General arguments imply that the Higgs boson or other new physics is required on the TeV energy scale. Indirect constraints from global analyses of electroweak measurements suggest that the mass of the standard-model Higgs boson is less than 200 GeV. Once its mass is assumed, the properties of the Higgs boson follow from the electroweak theory, and these inform the search for the Higgs boson. Alternative mechanisms for electroweak symmetry breaking are reviewed, and the importance of electroweak symmetry breaking is illuminated by considering a world without a specific mechanism to hide the electroweak symmetry. For all its triumphs, the electroweak theory has many shortcomings.

  9. Freeze-in production of sterile neutrino dark matter in U(1){sub B−L} model

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Anirban; Gupta, Aritra [Harish-Chandra Research Institute,Chhatnag Road, Jhunsi, Allahabad 211 019 (India)

    2016-09-27

    With the advent of new and more sensitive direct detection experiments, scope for a thermal WIMP explanation of dark matter (DM) has become extremely constricted. The non-observation of thermal WIMP in these experiments has put a strong upper bound on WIMP-nucleon scattering cross section and within a few years it is likely to overlap with the coherent neutrino-nucleon cross section. Hence in all probability, DM may have some non-thermal origin. In this work we explore in detail this possibility of a non-thermal sterile neutrino DM within the framework of U(1){sub B−L} model. The U(1){sub B−L} model on the other hand is a well-motivated and minimal way of extending the standard model so that it can explain the neutrino masses via Type-I see-saw mechanism. We have shown, besides explaining the neutrino mass, it can also accommodate a non-thermal sterile neutrino DM with correct relic density. In contrast with the existing literature, we have found that W{sup ±} decay can also be a dominant production mode of the sterile neutrino DM. To obtain the comoving number density of dark matter, we have solved here a coupled set of Boltzmann equations considering all possible decay as well as annihilation production modes of the sterile neutrino dark matter. The framework developed here though has been done for a U(1){sub B−L} model, can be applied quite generally for any models with an extra neutral gauge boson and a fermionic non-thermal dark matter.

  10. Freedom in electroweak symmetry breaking and mass matrix of fermions in dimensional deconstruction model

    International Nuclear Information System (INIS)

    Nojiri, Shin'ichi; Odintsov, Sergei D.; Sugamoto, Akio

    2004-01-01

    There exists a freedom in a class of four-dimensional electroweak theories proposed by Arkani-Hamed et al. relying on deconstruction and Coleman-Weinberg mechanism. The freedom comes from the winding modes of the link variable (Wilson operator) connecting non-nearest neighbours in the discrete fifth dimension. Using this freedom, dynamical breaking of SU(2) gauge symmetry, mass hierarchy patterns of fermions and Cabbibo-Kobayashi-Maskawa matrix may be obtained

  11. Electro-weak theory

    International Nuclear Information System (INIS)

    Deshpande, N.G.

    1980-01-01

    By electro-weak theory is meant the unified field theory that describes both weak and electro-magnetic interactions. The development of a unified electro-weak theory is certainly the most dramatic achievement in theoretical physics to occur in the second half of this century. It puts weak interactions on the same sound theoretical footing as quantum elecrodynamics. Many theorists have contributed to this development, which culminated in the works of Glashow, Weinberg and Salam, who were jointly awarded the 1979 Nobel Prize in physics. Some of the important ideas that contributed to this development are the theory of beta decay formulated by Fermi, Parity violation suggested by Lee and Yang, and incorporated into immensely successful V-A theory of weak interactions by Sudarshan and Marshak. At the same time ideas of gauge invariance were applied to weak interaction by Schwinger, Bludman and Glashow. Weinberg and Salam then went one step further and wrote a theory that is renormalizable, i.e., all higher order corrections are finite, no mean feat for a quantum field theory. The theory had to await the development of the quark model of hadrons for its completion. A description of the electro-weak theory is given

  12. Phenomenology of the hierarchical lepton mass spectrum in the flipped SU(5)xU(1) string model

    Energy Technology Data Exchange (ETDEWEB)

    Leontaris, G.K.; Nanopoulos, D.V.

    1988-09-29

    A detailed phenomenological analysis of the lepton mass matrices and their implications in the low energy theory are discussed, within the recently proposed SU(5)xU(1) string model. The unification scale is highly constrained while the Yukawa couplings lie in a natural region. The flavour changing decays ..mu.. -> e..gamma.., ..mu.. -> 3e, ..mu.. -> e are highly suppressed while the depletion in the flux of muon neutrinos reported by the Kamiokande is explained through ..nu../sub ..mu../ reversible ..nu../sub tau/ oscillations.

  13. Neutrinophilic two Higgs doublet model with dark matter under an alternative U(1)_{B-L} gauge symmetry

    Science.gov (United States)

    Nomura, Takaaki; Okada, Hiroshi

    2018-03-01

    We propose a Dirac type active neutrino with rank two mass matrix and a Majorana fermion dark matter candidate with an alternative local U(1)_{B-L} extension of neutrinophilic two Higgs doublet model. Our dark matter candidate can be stabilized due to charge assignment under the gauge symmetry without imposing extra discrete Z_2 symmetry and the relic density is obtained from an Z' boson exchanging process. Taking into account collider constraints on the Z' boson mass and coupling, we estimate the relic density.

  14. Gauge vs. gravity mediation in models with anomalous U(1)'s

    International Nuclear Information System (INIS)

    Dudas, E.; Mambrini, Y.; Romagnoni, A.; Trapletti, M.; Pokorski, S.

    2009-01-01

    In an attempt to implement gauge mediation in string theory, we study string effective supergravity models of supersymmetry breaking, containing anomalous gauge factors. We discuss subtleties related to gauge invariance and the stabilization of the Green-Schwarz moduli, which set non-trivial constraints on the transmission of supersymmetry breaking to MSSM via gauge interactions. Given those constraints, it is difficult to obtain the dominance of gauge mediation over gravity mediation. Furthermore, generically the gauge contributions to soft terms contain additional non-standard terms coming from D-term contributions. Motivated by this, we study the phenomenology of recently proposed hybrid models, where gravity and gauge mediations compete at the GUT scale, and show that such a scenario can respect WMAP constraints and would be easily testable at LHC.

  15. Dimensional reduction of U(1) x SU(2) Chern-Simons bosonization: Application to the t - J model

    International Nuclear Information System (INIS)

    Marchetti, P.A.

    1996-09-01

    We perform a dimensional reduction of the U(1) x SU(2) Chern-Simons bosonization and apply it to the t - J model, relevant for high T c superconductors. This procedure yields a decomposition of the electron field into a product of two ''semionic'' fields, i.e. fields obeying Abelian braid statistics with statistics parameter θ = 1/4, one carrying the charge and the other the spin degrees of freedom. A mean field theory is then shown to reproduce correctly the large distance behaviour of the correlation functions of the 1D t - J model at >> J. This result shows that to capture the essential physical properties of the model one needs a specific ''semionic'' form of spin-charge separation. (author). 31 refs

  16. Constructive tensorial group field theory II: the {U(1)-T^4_4} model

    Science.gov (United States)

    Lahoche, Vincent

    2018-05-01

    In this paper, we continue our program of non-pertubative constructions of tensorial group field theories (TGFT). We prove analyticity and Borel summability in a suitable domain of the coupling constant of the simplest super-renormalizable TGFT which contains some ultraviolet divergencies, namely the color-symmetric quartic melonic rank-four model with Abelian gauge invariance, nicknamed . We use a multiscale loop vertex expansion. It is an extension of the loop vertex expansion (the basic constructive technique for non-local theories) which is required for theories that involve non-trivial renormalization.

  17. Anomalous U(1) models in four and five dimensions and their anomaly poles

    International Nuclear Information System (INIS)

    Armillis, Roberta; Coriano, Claudio; Delle Rose, Luigi; Guzzi, Marco

    2009-01-01

    We analyze the role played by anomaly poles in an anomalous gauge theory by discussing their signature in the corresponding off-shell effective action. The origin of these contributions, in the most general kinematical case, is elucidated by performing a complete analysis of the anomaly vertex at perturbative level. We use two independent (but equivalent) representations: the Rosenberg representation and the longitudinal/transverse (L/T) parameterization, used in recent studies of g-2 of the muon and in the proof of non-renormalization theorems of the anomaly vertex. The poles extracted from the L/T parameterization do not couple in the infrared for generic anomalous vertices, as in Rosenberg, but we show that they are responsible for the violations of unitarity in the UV region, using a class of pole-dominated amplitudes. We conclude that consistent formulations of anomalous models require necessarily the cancellation of these polar contributions. Establishing the UV significance of these terms provides a natural bridge between the anomalous effective action and its completion by a nonlocal theory. Some additional difficulties with unitarity of the mechanism of inflow in extra dimensional models with an anomalous theory on the brane, due to the presence of anomaly poles, are also pointed out.

  18. Mixing angles in SU(2)/sub L/ x U(1) gauge model

    International Nuclear Information System (INIS)

    Nandi, S.; Tanaka, K.

    1979-01-01

    Exact expressions for the mixing parameters are obtained in terms of mass ratios in the standard Weinberg-Salam model with permutation symmetry S 3 for six quarks. The CP-violating phase is ignored, and there are no arbitrary parameters except for the quark masses. In the lowest order, the angles defined by Kobayashi-Maskawa are sin theta/sub 1/ = sin theta/sub c/ = (m/sub d//m/sub d/ + m/sub s/)/sup 1/2/, sin theta 3 = -sin theta/sub 3/ = -m 2 /sub s//m 2 /sub b/, and m/sub t/m/sub s/ greater than or equal to m/sub c/m/sub b/ = 7.2 GeV 2 or m/sub t/ greater than or equal to 24 GeV for m/sub s/ = 0.3 GeV

  19. Phenomenology of the SU(3)cxSU(3)LxU(1)X model with exotic charged leptons

    International Nuclear Information System (INIS)

    Salazar, Juan C.; Ponce, William A.; Gutierrez, Diego A.

    2007-01-01

    A phenomenological analysis of the three-family model based on the local gauge group SU(3) c xSU(3) L xU(1) X with exotic charged leptons, is carried out. Instead of using the minimal scalar sector able to break the symmetry in a proper way, we introduce an alternative set of four Higgs scalar triplets, which combined with an anomaly-free discrete symmetry, produce quark and charged lepton mass spectrum without hierarchies in the Yukawa coupling constants. We also embed the structure into a simple gauge group and show some conditions to achieve a low energy gauge coupling unification, avoiding possible conflict with proton decay bounds. By using experimental results from the CERN-LEP, SLAC linear collider, and atomic parity violation data, we update constraints on several parameters of the model

  20. Phenomenology of the SU(3)c x SU(3)L x U(1)X model with right-handed neutrinos

    International Nuclear Information System (INIS)

    Gutierrez, D.A.; Ponce, W.A.; Sanchez, L.A.

    2006-01-01

    A phenomenological analysis of the three-family model based on the local gauge group SU(3) c x SU(3) L x U(1) X with right-handed neutrinos is carried out. Instead of using the minimal scalar sector able to break the symmetry in a proper way, we introduce an alternative set of four Higgs scalar triplets, which combined with an anomaly-free discrete symmetry, produces a quark mass spectrum without hierarchies in the Yukawa coupling constants. We also embed the structure into a simple gauge group and show some conditions for achieving a low energy gauge coupling unification, avoiding possible conflict with proton decay bounds. By using experimental results from the CERN-LEP, SLAC linear collider, and atomic parity violation data, we update constraints on several parameters of the model. (orig.)

  1. Phenomenology of U(1){sub F} extension of inert-doublet model with exotic scalars and leptons

    Energy Technology Data Exchange (ETDEWEB)

    Dhargyal, Lobsang [Harish-Chandra Research Institute, HBNI, Allahabad (India)

    2018-02-15

    In this work we will extend the inert-doublet model (IDM) by adding a new U(1){sub F} gauge symmetry to it, under which, a Z{sub 2} even scalar (φ{sub 2}) and Z{sub 2} odd right handed component of two exotic charged leptons (F{sub eR}, F{sub μR}), are charged. We also add one Z{sub 2} even real scalar (φ{sub 1}) and one complex scalar (φ), three neutral Majorana right handed fermions (N{sub 1}, N{sub 2}, N{sub 3}), two left handed components of the exotic charged leptons (F{sub eL}, F{sub μL}) as well as F{sub τ} are all odd under the Z{sub 2}, all of which are not charged under the U(1){sub F}. With these new particles added to the IDM, we have a model which can give two scalar DM candidates, together they can explain the present DM relic density as well as the muon (g-2) anomaly simultaneously. Also in this model the neutrino masses are generated at one loop level. One of the most peculiar feature of this model is that non-trivial solution to the axial gauge anomaly free conditions lead to the prediction of a stable very heavy partner to the electron (F{sub e}), whose present collider limit (13 TeV LHC) on its mass should be around m{sub F{sub e}} ≥ few TeV. (orig.)

  2. The Electroweak Fit of the Standard Model after the Discovery of a New Boson at the LHC

    CERN Document Server

    Baak, M.

    2012-11-03

    In view of the discovery of a new boson by the ATLAS and CMS Collaborations at the LHC, we present an update of the global Standard Model (SM) fit to electroweak precision data. Assuming the new particle to be the SM Higgs boson, all fundamental parameters of the SM are known allowing, for the first time, to overconstrain the SM at the electroweak scale and assert its validity. Including the effects of radiative corrections and the experimental and theoretical uncertainties, the global fit exhibits a p-value of 0.07. The mass measurements by ATLAS and CMS agree within 1.3sigma with the indirect determination M_H=(94 +25 -22) GeV. Within the SM the W boson mass and the effective weak mixing angle can be accurately predicted to be M_W=(80.359 +- 0.011) GeV and sin^2(theta_eff^ell)=(0.23150 +- 0.00010) from the global fit. These results are compatible with, and exceed in precision, the direct measurements. For the indirect determination of the top quark mass we find m_t=(175.8 +2.7 -2.4) GeV, in agreement with t...

  3. The electroweak fit of the standard model after the discovery of a new boson at the LHC

    International Nuclear Information System (INIS)

    Baak, M.; Hoecker, A.; Schott, M.; Goebel, M.; Kennedy, D.; Moenig, K.; Haller, J.; Kogler, R.; Stelzer, J.

    2012-09-01

    In view of the discovery of a new boson by the ATLAS and CMS Collaborations at the LHC, we present an update of the global Standard Model (SM) fit to electroweak precision data. Assuming the new particle to be the SM Higgs boson, all fundamental parameters of the SM are known allowing, for the first time, to overconstrain the SM at the electroweak scale and assert its validity. Including the effects of radiative corrections and the experimental and theoretical uncertainties, the global fit exhibits a p-value of 0.07. The mass measurements by ATLAS and CMS agree within 1.3σ with the indirect determination M H =94 +25 -22 GeV. Within the SM the W boson mass and the effective weak mixing angle can be accurately predicted to be M W =80.359±0.011 GeV and sin 2 θ l eff =0.23150±0.00010 from the global fit. These results are compatible with, and exceed in precision, the direct measurements. For the indirect determination of the top quark mass we find m t =175.8 +2.7 -2.4 GeV, in agreement with the kinematic and cross-section based measurements.

  4. Electroweak physics with LEP

    International Nuclear Information System (INIS)

    Davier, M.

    1992-03-01

    The present status of electroweak physics at LEP is presented. The LEP machine and the detectors are described. The decays of Z neutral bosons in both leptonic and hadronic channels are studied. Neutral and charged sector are investigated, and a precise test of the Standard Model is given. Higgs boson searches and τ decay measurements are also described as well as quark mixing and B 0 B-bar 0 oscillations. All the seven contributions are individually indexed and abstracted for the INIS database. (K.A.) 100 refs

  5. Novel SM-like Higgs decay into displaced heavy neutrino pairs in U(1){sup ′} models

    Energy Technology Data Exchange (ETDEWEB)

    Accomando, Elena [School of Physics and Astronomy, University of Southampton,Highfield, Southampton SO17 1BJ (United Kingdom); Rose, Luigi Delle; Moretti, Stefano [School of Physics and Astronomy, University of Southampton,Highfield, Southampton SO17 1BJ (United Kingdom); Particle Physics Department, Rutherford Appleton Laboratory,Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Olaiya, Emmanuel; Shepherd-Themistocleous, Claire H. [Particle Physics Department, Rutherford Appleton Laboratory,Chilton, Didcot, Oxon OX11 0QX (United Kingdom)

    2017-04-13

    We examine the observability of heavy neutrino (ν{sub h}) signatures of a U(1){sup ′} enlarged Standard Model (SM) encompassing three heavy Majorana neutrinos alongside the known light neutrino states at the the Large Hadron Collider (LHC). We show that heavy neutrinos can be rather long-lived particles producing distinctive displaced vertices that can be accessed in the CERN LHC detectors. We concentrate here on the gluon fusion production mechanism gg→H{sub 1,2}→ν{sub h}ν{sub h}, where H{sub 1} is the discovered SM-like Higgs and H{sub 2} is a heavier state, yielding displaced leptons following ν{sub h} decays into weak gauge bosons. Using data collected by the end of the LHC Run 2, these signatures would prove to be accessible with negligibly small background.

  6. Stable SUSY breaking model with O(10) eV gravitino from combined D-term gauge mediation and U(1)' mediation

    International Nuclear Information System (INIS)

    Nakayama, Yu

    2008-01-01

    We show a calculable example of stable supersymmetry (SUSY) breaking models with O(10) eV gravitino mass based on the combination of D-term gauge mediation and U(1)' mediation. A potential problem of the negative mass squared for the SUSY standard model (SSM) sfermions in the D-term gauge mediation is solved by the contribution from the U(1)' mediation. On the other hand, the splitting between the SSM gauginos and sfermions in the U(1)' mediation is circumvented by the contributions from the D-term gauge mediation. Since the U(1)' mediation does not introduce any new SUSY vacua, we achieve a completely stable model under thermal effects. Our model, therefore, has no cosmological difficulty

  7. Strong coupling electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Barklow, T.L.; Burdman, G.; Chivukula, R.S.

    1997-04-01

    The authors review models of electroweak symmetry breaking due to new strong interactions at the TeV energy scale and discuss the prospects for their experimental tests. They emphasize the direct observation of the new interactions through high-energy scattering of vector bosons. They also discuss indirect probes of the new interactions and exotic particles predicted by specific theoretical models

  8. Strong coupling electroweak symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Barklow, T.L. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Burdman, G. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics; Chivukula, R.S. [Boston Univ., MA (United States). Dept. of Physics

    1997-04-01

    The authors review models of electroweak symmetry breaking due to new strong interactions at the TeV energy scale and discuss the prospects for their experimental tests. They emphasize the direct observation of the new interactions through high-energy scattering of vector bosons. They also discuss indirect probes of the new interactions and exotic particles predicted by specific theoretical models.

  9. TRISTAN electroweak working group report

    International Nuclear Information System (INIS)

    Hagiwara, K.

    1995-01-01

    Model-independent measurements of quantities sensitive to the electroweak physics at TRISTAN energies are proposed for the processes e + e - → e + e - , μ + μ - , τ + τ - , hadrons and heavy-quark (charm- and bottom-quark) jets. Factorization of the scattering amplitudes into the part which is sensitive to short-distance electroweak physics and the rest which is sensitive to long-distance QED and QCD corrections is made, and uncertainties in the latter are studied quantitatively by using existing programs. Electroweak observables are then chosen for each processes such that the uncertainty from the long-distance physics is small and that they can be updated when we reach a better understanding of the QED and QCD corrections. The new scheme will make the data from high luminosity TRISTAN experiments useful for particle physicists of the present as well as those of the future generation. (author)

  10. An introduction to relativistic processes and the standard model of electroweak interactions

    CERN Document Server

    Becchi, Carlo Maria

    2014-01-01

    These lectures are meant to be a reference and handbook for an introductory course in Theoretical Particle Physics, suitable for advanced undergraduates or beginning graduate students. Their purpose is to reconcile theoretical rigour and completeness with a careful analysis of more phenomenological aspects of the physics. They aim at filling the gap between quantum field theory textbooks and purely phenomenological treatments of fundamental interactions. The first part provides an introduction to scattering in relativistic quantum field theory. Thanks to an original approach to relativistic processes, the relevant computational techniques are derived cleanly and simply in the semi-classical approximation. The second part contains a detailed presentation of the gauge theory of electroweak interactions with particular focus to the processes of greatest phenomenological interest. The main novelties of the present second edition are a more complete discussion of relativistic scattering theory and an expansion of ...

  11. An electroweak basis for neutrinoless double β decay

    Science.gov (United States)

    Graesser, Michael L.

    2017-08-01

    A discovery of neutrinoless double- β decay would be profound, providing the first direct experimental evidence of Δ L = 2 lepton number violating processes. While a natural explanation is provided by an effective Majorana neutrino mass, other new physics interpretations should be carefully evaluated. At low-energies such new physics could man-ifest itself in the form of color and SU(2) L × U(1) Y invariant higher dimension operators. Here we determine a complete set of electroweak invariant dimension-9 operators, and our analysis supersedes those that only impose U(1) em invariance. Imposing electroweak invariance implies: 1) a significantly reduced set of leading order operators compared to only imposing U(1) em invariance; and 2) other collider signatures. Prior to imposing electroweak invariance we find a minimal basis of 24 dimension-9 operators, which is reduced to 11 electroweak invariant operators at leading order in the expansion in the Higgs vacuum expectation value. We set up a systematic analysis of the hadronic realization of the 4-quark operators using chiral perturbation theory, and apply it to determine which of these operators have long-distance pion enhancements at leading order in the chiral expansion. We also find at dimension-11 and dimension-13 the electroweak invariant operators that after electroweak symmetry breaking produce the remaining Δ L = 2 operators that would appear at dimension-9 if only U(1) em is imposed.

  12. Testing Left-Right extensions of the standard model of electroweak interactions with double-beta decay and LHC measurements

    Science.gov (United States)

    Civitarese, O.; Suhonen, J.; Zuber, K.

    2015-07-01

    The minimal extension of the standard model of electroweak interactions allows for massive neutrinos, a massive right-handed boson WR, and a left-right mixing angle ζ. While an estimate of the light (electron) neutrino can be extracted from the non-observation of the neutrinoless double beta decay, the limits on the mixing angle and the mass of the righthanded (RH) boson may be extracted from a combined analysis of the double beta decay measurements (GERDA, EXO-200 and KamLAND-Zen collaborations) and ATLAS data on the two-jets two-leptons signals following the excitation of a virtual RH boson mediated by a heavy-mass neutrino. In this work we shall compare results of both types of experiments, and show that the estimates are not in tension.

  13. Black hole physics from two-dimensional dilaton gravity based on the SL(2,R)/U(1) coset model

    International Nuclear Information System (INIS)

    Nojiri, S.; Oda, I.

    1994-01-01

    We analyze the quantum two-dimensional dilaton gravity model, which is described by the SL(2,R)/U(1) gauged Wess-Zumino-Witten model deformed by a (1,1) operator. We show that the curvature singularity does not appear when the central charge c matter of the matter fields is given by 22 matter matter matter ∝δ(x + -x 0 + ), create a kind of wormholes, i.e., causally disconnected regions. Most of the quantum information in past null infinity is lost in future null infinity but the lost information would be carried by the wormholes. We also discuss the problem of defining the mass of quantum black holes. On the basis of the argument by Regge and Teitelboim, we show that the ADM mass measured by the observer who lives in one of the asymptotically flat regions is finite and does not vanish in general. On the other hand, the Bondi mass is ill defined in this model. Instead of the Bondi mass, we consider the mass measured by observers who live in an asymptotically flat region at first. A class of observers finds the mass of the black hole created by a shock wave changes as the observers' proper time goes by, i.e., they observe Hawking radiation. The measured mass vanishes after the infinite proper time and the black hole evaporates completely. Therefore the total Hawking radiation is positive even when N<24

  14. STANFORD (SLAC): Precision electroweak result

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    Precision testing of the electroweak sector of the Standard Model has intensified with the recent publication* of results from the SLD collaboration's 1993 run on the Stanford Linear Collider, SLC. Using a highly polarized electron beam colliding with an unpolarized positron beam, SLD physicists measured the left-right asymmetry at the Z boson resonance with dramatically improved accuracy over 1992

  15. Spin and precision electroweak physics

    Energy Technology Data Exchange (ETDEWEB)

    Marciano, W.J. [Brookhaven National Lab., Upton, NY (United States)

    1994-12-01

    A perspective on fundamental parameters and precision tests of the Standard Model is given. Weak neutral current reactions are discussed with emphasis on those processes involving (polarized) electrons. The role of electroweak radiative corrections in determining the top quark mass and probing for {open_quotes}new physics{close_quotes} is described.

  16. Spin and precision electroweak physics

    International Nuclear Information System (INIS)

    Marciano, W.J.

    1993-01-01

    A perspective on fundamental parameters and precision tests of the Standard Model is given. Weak neutral current reactions are discussed with emphasis on those processes involving (polarized) electrons. The role of electroweak radiative corrections in determining the top quark mass and probing for ''new physics'' is described

  17. Upper bounds on Higgs and top quark masses in the flipped SU(5)xU(1) superstring model

    Energy Technology Data Exchange (ETDEWEB)

    Durand, L.; Lopez, J.L.

    1989-02-02

    In this letter, we use a simplified method to calculate high-energy unitarity constraints on grand unified broken supersymmetric models. We apply the method to the ''flipped'' SU(5)xU(1) superstring model, obtain the constraints at a grand unified mass scale M/sub G/=4x10/sup 16/ GeV, and then use the renormalization group equations to evolve the constraints to the low-energy mass scale M/sub W/. We find upper bounds on the low-energy superpotential parameters which in turn imply absolute upper bounds on the top quark mass, m/sub t/< or approx.200 GeV, and on the lightest neutral Higgs boson mass, Msub(H/sub 1//sup 0/)< or approx.155 GeV. We also obtain an upper bound on Msub(H/sub 1//sup 0/) as a function of m/sub t/ which shows that for favored values of the ratio of Higgs vacuum expectation values Msub(H/sub 1//sup 0/)< or approx.125 GeV.

  18. Neutrino mixing and R{sub K} anomaly in U(1){sub X} models: a bottom-up approach

    Energy Technology Data Exchange (ETDEWEB)

    Bhatia, Disha; Chakraborty, Sabyasachi; Dighe, Amol [Tata Institute of Fundamental Research,Mumbai 400005 (India)

    2017-03-22

    We identify a class of U(1){sub X} models which can explain the R{sub K} anomaly and the neutrino mixing pattern, by using a bottom-up approach. The different X-charges of lepton generations account for the lepton universality violation required to explain R{sub K}. In addition to the three right-handed neutrinos needed for the Type-I seesaw mechanism, these minimal models only introduce an additional doublet Higgs and a singlet scalar. While the former helps in reproducing the quark mixing structure, the latter gives masses to neutrinos and the new gauge boson Z{sup ′}. Our bottom-up approach determines the X-charges of all particles using theoretical consistency and experimental constraints. We find the parameter space allowed by the constraints from neutral meson mixing, rare b→s decays and direct collider searches for Z{sup ′}. Such a Z{sup ′} may be observable at the ongoing run of the Large Hadron Collider with a few hundred fb{sup −1} of integrated luminosity.

  19. A modification of projective spacetime by finite self-interaction models of virtual leptons and quarks and the electroweak GWS standard model

    International Nuclear Information System (INIS)

    Scheurich, H.

    1986-01-01

    From the projective Dirac equation in a six-dimensional Kleinian space R(3, 3) are derived finite-rotation-group models as self-interaction models of virtual leptons and quarks. The quaternion group underlying them is considered as a substructure group of projective spacetime. A finite hyperspherical carrier of the self-interaction models is embedded into projective spacetime by means of the Planck length L 0 = (hG/c 3 )/sup 1/2/ as a physical unit length. The corresponding modification of metrics in the Planck domain becomes apparent to be equivalent to the role of the Higgs field in the electroweak GWS standard model. (author)

  20. Electroweak precision observables and Higgs-boson signal strengths in the Standard Model and beyond: present and future

    Energy Technology Data Exchange (ETDEWEB)

    Blas, J. de [INFN, Sezione di Roma,Piazzale A. Moro 2, I-00185 Rome (Italy); Ciuchini, M. [INFN, Sezione di Roma Tre,Via della Vasca Navale 84, I-00146 Roma (Italy); Franco, E. [INFN, Sezione di Roma,Piazzale A. Moro 2, I-00185 Rome (Italy); Mishima, S. [Theory Center, Institute of Particle and Nuclear Studies (IPNS),High Energy Accelerator Research Organization (KEK),1-1 Oho, Tsukuba, 305-0801 (Japan); Pierini, M. [CERN,Geneva (Switzerland); Reina, L. [Physics Department, Florida State University,77 Chieftan Way, Tallahassee, FL 32306-4350 (United States); Kavli Institute for Theoretical Physics, University of California,Kohn Hall, Santa Barbara, CA 93106-4030 (United States); Silvestrini, L. [INFN, Sezione di Roma,Piazzale A. Moro 2, I-00185 Rome (Italy)

    2016-12-27

    We present results from a state-of-the-art fit of electroweak precision observables and Higgs-boson signal-strength measurements performed using 7 and 8 TeV data from the Large Hadron Collider. Based on the HEPfit package, our study updates the traditional fit of electroweak precision observables and extends it to include Higgs-boson measurements. As a result we obtain constraints on new physics corrections to both electroweak observables and Higgs-boson couplings. We present the projected accuracy of the fit taking into account the expected sensitivities at future colliders.

  1. Electroweak splitting functions and high energy showering

    Science.gov (United States)

    Chen, Junmou; Han, Tao; Tweedie, Brock

    2017-11-01

    We derive the electroweak (EW) collinear splitting functions for the Standard Model, including the massive fermions, gauge bosons and the Higgs boson. We first present the splitting functions in the limit of unbroken SU(2) L × U(1) Y and discuss their general features in the collinear and soft-collinear regimes. These are the leading contributions at a splitting scale ( k T ) far above the EW scale ( v). We then systematically incorporate EW symmetry breaking (EWSB), which leads to the emergence of additional "ultra-collinear" splitting phenomena and naive violations of the Goldstone-boson Equivalence Theorem. We suggest a particularly convenient choice of non-covariant gauge (dubbed "Goldstone Equivalence Gauge") that disentangles the effects of Goldstone bosons and gauge fields in the presence of EWSB, and allows trivial book-keeping of leading power corrections in v/ k T . We implement a comprehensive, practical EW showering scheme based on these splitting functions using a Sudakov evolution formalism. Novel features in the implementation include a complete accounting of ultra-collinear effects, matching between shower and decay, kinematic back-reaction corrections in multi-stage showers, and mixed-state evolution of neutral bosons ( γ/ Z/ h) using density-matrices. We employ the EW showering formalism to study a number of important physical processes at O (1-10 TeV) energies. They include (a) electroweak partons in the initial state as the basis for vector-boson-fusion; (b) the emergence of "weak jets" such as those initiated by transverse gauge bosons, with individual splitting probabilities as large as O (35%); (c) EW showers initiated by top quarks, including Higgs bosons in the final state; (d) the occurrence of O (1) interference effects within EW showers involving the neutral bosons; and (e) EW corrections to new physics processes, as illustrated by production of a heavy vector boson ( W ') and the subsequent showering of its decay products.

  2. Electroweak interactions in nuclei

    International Nuclear Information System (INIS)

    Henley, E.M.

    1984-06-01

    Topics include: introduction to electroweak theory; the Weinberg-Salam theory for leptons; the Weinberg-Salam theory for hadrons-the GIM mechanism; electron scattering as a probe of the electroweak interaction (observation of PV, the weak interaction for nucleons, and parity violation in atoms); and time reversed invariance and electric dipole moments of nucleons, nuclei, and atoms. 52 references

  3. Gravitationally coupled electroweak monopole

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Y.M., E-mail: ymcho7@konkuk.ac.kr [Administration Building 310-4, Konkuk University, Seoul 143-701 (Korea, Republic of); School of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Kimm, Kyoungtae [Faculty of Liberal Education, Seoul National University, Seoul 151-747 (Korea, Republic of); Yoon, J.H. [Department of Physics, College of Natural Sciences, Konkuk University, Seoul 143-701 (Korea, Republic of)

    2016-10-10

    We present a family of gravitationally coupled electroweak monopole solutions in Einstein–Weinberg–Salam theory. Our result confirms the existence of globally regular gravitating electroweak monopole which changes to the magnetically charged black hole as the Higgs vacuum value approaches to the Planck scale. Moreover, our solutions could provide a more accurate description of the monopole stars and magnetically charged black holes.

  4. Introduction to gauge theories of electroweak interactions

    International Nuclear Information System (INIS)

    Ecker, G.

    1982-01-01

    The author presents an introduction to electroweak gauge theories. Emphasis is placed on the properties of a general gauge theory. The standard model is discussed as the simplest example to illustrate these properties. (G.T.H.)

  5. Membrane-bound human orphan cytochrome P450 2U1: Sequence singularities, construction of a full 3D model, and substrate docking.

    Science.gov (United States)

    Ducassou, Lionel; Dhers, Laura; Jonasson, Gabriella; Pietrancosta, Nicolas; Boucher, Jean-Luc; Mansuy, Daniel; André, François

    2017-09-01

    Human cytochrome P450 2U1 (CYP2U1) is an orphan CYP that exhibits several distinctive characteristics among the 57 human CYPs with a highly conserved sequence in almost all living organisms. We compared its protein sequence with those of the 57 human CYPs and constructed a 3D structure of a full-length CYP2U1 model bound to a POPC membrane. We also performed docking experiments of arachidonic acid (AA) and N-arachidonoylserotonin (AS) in this model. The protein sequence of CYP2U1 displayed two unique characteristics when compared to those of the human CYPs, the presence of a longer N-terminal region upstream of the putative trans-membrane helix (TMH) containing 8 proline residues, and of an insert of about 20 amino acids containing 5 arginine residues between helices A' and A. Its N-terminal part upstream of TMH involved an additional short terminal helix, in a manner similar to what was reported in the crystal structure of Saccharomyces cerevisiae CYP51. Our model also showed a specific interaction between the charged residues of insert AA' and phosphate groups of lipid polar heads, suggesting a possible role of this insert in substrate recruitment. Docking of AA and AS in this model showed these substrates in channel 2ac, with the terminal alkyl chain of AA or the indole ring of AS close to the heme, in agreement with the reported CYP2U1-catalyzed AA and AS hydroxylation regioselectivities. This model should be useful to find new endogenous or exogenous CYP2U1 substrates and to interpret the regioselectivity of their hydroxylation. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  6. Electroweak phase transitions

    International Nuclear Information System (INIS)

    Anderson, G.W.

    1991-01-01

    An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles and completes at a temperature where the order parameter, left-angle φ right-angle T is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially function of left-angle φ right-angle T . In very minimal extensions of the standard model it is quite easy to increase left-angle φ right-angle T so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value left-angle φ right-angle = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state left-angle φ right-angle = 246 GeV unstable. The requirement that the state left-angle φ right-angle = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field

  7. Electron electric dipole moment in mirror fermion model with electroweak scale non-sterile right-handed neutrinos

    Directory of Open Access Journals (Sweden)

    Chia-Feng Chang

    2018-03-01

    Full Text Available The electric dipole moment of the electron is studied in detail in an extended mirror fermion model with the following unique features of (a right-handed neutrinos are non-sterile and have masses at the electroweak scale, and (b a horizontal symmetry of the tetrahedral group is used in the lepton and scalar sectors. We study the constraint on the parameter space of the model imposed by the latest ACME experimental limit on electron electric dipole moment. Other low energy experimental observables such as the anomalous magnetic dipole moment of the muon, charged lepton flavor violating processes like muon decays into electron plus photon and muon-to-electron conversion in titanium, gold and lead are also considered in our analysis for comparison. In addition to the well-known CP violating Dirac and Majorana phases in the neutrino mixing matrix, the dependence of additional phases of the new Yukawa couplings in the model is studied in detail for all these low energy observables.

  8. Electron electric dipole moment in mirror fermion model with electroweak scale non-sterile right-handed neutrinos

    Science.gov (United States)

    Chang, Chia-Feng; Hung, P. Q.; Nugroho, Chrisna Setyo; Tran, Van Que; Yuan, Tzu-Chiang

    2018-03-01

    The electric dipole moment of the electron is studied in detail in an extended mirror fermion model with the following unique features of (a) right-handed neutrinos are non-sterile and have masses at the electroweak scale, and (b) a horizontal symmetry of the tetrahedral group is used in the lepton and scalar sectors. We study the constraint on the parameter space of the model imposed by the latest ACME experimental limit on electron electric dipole moment. Other low energy experimental observables such as the anomalous magnetic dipole moment of the muon, charged lepton flavor violating processes like muon decays into electron plus photon and muon-to-electron conversion in titanium, gold and lead are also considered in our analysis for comparison. In addition to the well-known CP violating Dirac and Majorana phases in the neutrino mixing matrix, the dependence of additional phases of the new Yukawa couplings in the model is studied in detail for all these low energy observables.

  9. Precision electroweak physics at LEP

    Energy Technology Data Exchange (ETDEWEB)

    Mannelli, M.

    1994-12-01

    Copious event statistics, a precise understanding of the LEP energy scale, and a favorable experimental situation at the Z{sup 0} resonance have allowed the LEP experiments to provide both dramatic confirmation of the Standard Model of strong and electroweak interactions and to place substantially improved constraints on the parameters of the model. The author concentrates on those measurements relevant to the electroweak sector. It will be seen that the precision of these measurements probes sensitively the structure of the Standard Model at the one-loop level, where the calculation of the observables measured at LEP is affected by the value chosen for the top quark mass. One finds that the LEP measurements are consistent with the Standard Model, but only if the mass of the top quark is measured to be within a restricted range of about 20 GeV.

  10. Self-interacting dark matter and Higgs bosons in the SU(3)C x SU(3)L x U(1)N model with right-handed neutrinos

    International Nuclear Information System (INIS)

    Hoang Ngoc Long; Nguyen Quynh Lan

    2003-05-01

    We show that the SU(3) C x SU(3) L x U(1) N (3-3-1) model with right-handed neutrinos can provide candidates for self-interacting dark matter, namely they are the CP-even and odd Higgs bosons. These dark matters are stable without imposing of new symmetry and should be weak-interacting. (author)

  11. Non-negligible electroweak penguin effects

    International Nuclear Information System (INIS)

    Guo Libo; Li Xingyi

    1999-01-01

    Starting from the leading logarithmic low energy effective Hamiltonian and the Bauer-Stech-Wirbe (BSW) model, the authors calculate the electroweak penguin effects in the two-body hadronic pure penguin processes of B-meson. In the case of B→PP and PV decay, the authors find that the processes involving external penguin diagrams receive large contribution from electroweak penguin effects which can even play dominant role

  12. Algebra of strong and electroweak interactions

    International Nuclear Information System (INIS)

    Bolokhov, S.V.; Vladimirov, Yu.S.

    2004-01-01

    The algebraic approach to describing the electroweak and strong interactions is considered within the frames of the binary geometrophysics, based on the principles of the Fokker-Feynman direct interparticle interaction theories of the Kaluza-Klein multidimensional geometrical models and the physical structures theory. It is shown that in this approach the electroweak and strong elementary particles interaction through the intermediate vector bosons, are characterized by the subtypes of the algebraic classification of the complex 3 x 3-matrices [ru

  13. A practical introduction to electroweak radiative corrections

    International Nuclear Information System (INIS)

    Drees, M.

    1991-05-01

    This is a brief introduction into electroweak radiative corrections within the Standard Model, with the emphasis on performing actual calculations. To this end, a complete set of expressions is given that allows the computation of the ρ parameter, the W mass, and Z→fanti f decays for massless fermions, where the anti Manti S scheme has been used. I conclude with an assessment of what we have learned so far from electroweak precision experiments, and a brief outlook. (orig.)

  14. U(1) problem

    Energy Technology Data Exchange (ETDEWEB)

    McDougall, N.A. (Oxford Univ. (UK). Dept. of Theoretical Physics)

    1984-08-23

    The resolution of the U(1) problem requires the quark condensates to have a specific THETA dependence. We show that the required THETA dependence arises naturally upon application of the index theorem during the calculation of the dynamically generated quark mass.

  15. Electroweak baryogenesis and low energy supersymmetry

    CERN Document Server

    Carena, M S; Riotto, Antonio; Vilja, I; Wagner, C E M

    1997-01-01

    Electroweak baryogenesis is an interesting theoretical scenario, which demands physics beyond the Standard Model at energy scales of the order of the weak boson masses. It has been recently emphasized that, in the presence of light stops, the electroweak phase transition can be strongly first order, opening the window for electroweak baryogenesis in the MSSM. For the realization of this scenario, the Higgs boson must be light, at the reach of the LEP2 collider. In this article, we compute the baryon asymmetry assuming the presence of non-trivial CP violating phases in the parameters associated with the left-right stop mixing term and the Higgsino mass $\\mu$. We conclude that a phase $|\\sin \\phi_{\\mu}| > 0.01$ and Higgsino and gaugino mass parameters $|\\mu| \\simeq M_2$, and of the order of the electroweak scale, are necessary in order to generate the observed baryon asymmetry.

  16. Electroweak form factors

    International Nuclear Information System (INIS)

    Singh, S.K.

    2002-01-01

    The present status of electroweak nucleon form factors and the N - Δ transition form factors is reviewed. Particularly the determination of dipole mass M A in the axial vector form factor is discussed

  17. Phenomenological analysis of supersymmetric σ-models on coset spaces SO(10)/U(5) and E6/[SO(10)xU(1)

    International Nuclear Information System (INIS)

    Nyawelo, T.S.

    2004-12-01

    We discuss some phenomenological aspects of gauged supersymmetric σ-models on homogeneous coset-spaces E 6 /[SO(10)xU(1)] and SO(10)/U(5) which are some of the most interesting for phenomenology. We investigate in detail the vacuum configurations of these models, and study the resulting consequences for supersymmetry breaking and breaking of the internal symmetry. Some supersymmetric minima for both models with gauged full isometry groups E 6 and SO(10) are physically problematic as the Kaehler metric becomes singular ad hence the kinetic terms of the Goldstone boson multiplets vanish. This leads us to introduce recently proposed soft supersymmetry-breaking mass terms which displace the minimum away from the singulax point. A non-singular Kaehler metric breaks the linear subgroup SO(10)xU(1) of the E 6 model spontaneously. The particle spectrum of all these different models is computed. (author)

  18. Emergent Electroweak Symmetry Breaking with Composite W, Z Bosons

    CERN Document Server

    Cui, Yanou; Wells, James D

    2009-01-01

    We present a model of electroweak symmetry breaking in a warped extra dimension where electroweak symmetry is broken at the UV (or Planck) scale. An underlying conformal symmetry is broken at the IR (or TeV) scale generating masses for the electroweak gauge bosons without invoking a Higgs mechanism. By the AdS/CFT correspondence the W,Z bosons are identified as composite states of a strongly-coupled gauge theory, suggesting that electroweak symmetry breaking is an emergent phenomenon at the IR scale. The model satisfies electroweak precision tests with reasonable fits to the S and T parameter. In particular the T parameter is sufficiently suppressed since the model naturally admits a custodial SU(2) symmetry. The composite nature of the W,Z-bosons provide a novel possibility of unitarizing WW scattering via form factor suppression. Constraints from LEP and the Tevatron as well as discovery opportunities at the LHC are discussed for these composite electroweak gauge bosons.

  19. Electroweak interactions on the lattice

    International Nuclear Information System (INIS)

    Kieu, T.D.

    1994-07-01

    It is shown that the lattice fermion doubling phenomenon is connected to the chiral anomaly which is unique to the electroweak interactions. The chiral anomaly is the breaking of chiral gauge symmetry at the quantum level due to the quantum fluctuations. Such breaking, however, is undesirable and to be avoided. The preservation of gauge symmetry imposes stringent constraints on acceptable chiral gauge theory. It is argued that the constraints are unnecessary because the conventional quantization of chiral gauge theory has missed out some crucial contributions of the chiral interactions. The corrected quantization yields consistent theory in which there is no gauge anomaly and in which various mass terms can be introduced with neither the loss of gauge invariance nor the need for the Higgs mechanism. The new quantization also provide a solution to the difficulty of how to model the electroweak interactions on the lattice. 9 refs. 1 fig

  20. Electroweak bubble wall speed limit

    Energy Technology Data Exchange (ETDEWEB)

    Bödeker, Dietrich [Fakultät für Physik, Universität Bielefeld, 33501 Bielefeld (Germany); Moore, Guy D., E-mail: bodeker@physik.uni-bielefeld.de, E-mail: guymoore@ikp.physik.tu-darmstadt.de [Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 2, 64289 Darmstadt (Germany)

    2017-05-01

    In extensions of the Standard Model with extra scalars, the electroweak phase transition can be very strong, and the bubble walls can be highly relativistic. We revisit our previous argument that electroweak bubble walls can 'run away,' that is, achieve extreme ultrarelativistic velocities γ ∼ 10{sup 14}. We show that, when particles cross the bubble wall, they can emit transition radiation. Wall-frame soft processes, though suppressed by a power of the coupling α, have a significance enhanced by the γ-factor of the wall, limiting wall velocities to γ ∼ 1/α. Though the bubble walls can move at almost the speed of light, they carry an infinitesimal share of the plasma's energy.

  1. Lepton-mediated electroweak baryogenesis

    International Nuclear Information System (INIS)

    Chung, Daniel J. H.; Garbrecht, Bjorn; Ramsey-Musolf, Michael J.; Tulin, Sean

    2010-01-01

    We investigate the impact of the tau and bottom Yukawa couplings on the transport dynamics for electroweak baryogenesis in supersymmetric extensions of the standard model. Although it has generally been assumed in the literature that all Yukawa interactions except those involving the top quark are negligible, we find that the tau and bottom Yukawa interaction rates are too fast to be neglected. We identify an illustrative 'lepton-mediated electroweak baryogenesis' scenario in which the baryon asymmetry is induced mainly through the presence of a left-handed leptonic charge. We derive analytic formulas for the computation of the baryon asymmetry that, in light of these effects, are qualitatively different from those in the established literature. In this scenario, for fixed CP-violating phases, the baryon asymmetry has opposite sign compared to that calculated using established formulas.

  2. ɛ '/ ɛ anomaly and neutron EDM in SU(2) L × SU(2) R × U(1) B- L model with charge symmetry

    Science.gov (United States)

    Haba, Naoyuki; Umeeda, Hiroyuki; Yamada, Toshifumi

    2018-05-01

    The Standard Model prediction for ɛ '/ ɛ based on recent lattice QCD results exhibits a tension with the experimental data. We solve this tension through W R + gauge boson exchange in the SU(2) L × SU(2) R × U(1) B- L model with `charge symmetry', whose theoretical motivation is to attribute the chiral structure of the Standard Model to the spontaneous breaking of SU(2) R × U(1) B- L gauge group and charge symmetry. We show that {M_W}{_R}study a correlation between ɛ ' /ɛ and the neutron EDM. We confirm that the model can solve the ɛ ' /ɛ anomaly without conflicting the current bound on the neutron EDM, and further reveal that almost all parameter regions in which the ɛ ' /ɛ anomaly is explained will be covered by future neutron EDM searches, which leads us to anticipate the discovery of the neutron EDM.

  3. Sign of the neutron-proton mass difference in an SU(2)xU(1) supersymmetric toy model: A possible scenario for solving the old puzzle

    International Nuclear Information System (INIS)

    Desai, B.R.; Xu, G.

    1990-01-01

    Based on the idea that electromagnetism is responsible for mass differences within isotopic multiplets (e.g., pointlike neutron and proton or u and d quarks), we generalize an SU(2)xU(1) model in a toy field theory of vectors to a supersymmetric model and investigate the finite mass difference within the isotopic doublet. It is found that under soft-supersymmetry breaking, a positive n-p mass difference can be obtained under reasonable assumptions for the parameters involved

  4. Higgs-boson contributions to gauge-boson mass shifts in extended electroweak models

    International Nuclear Information System (INIS)

    Moore, S.R.

    1985-10-01

    In the minimal standard model, the difference between the tree-level and one-loop-corrected predictions for the gauge-boson masses, known as the mass shifts, are of the order of 4%. The dominant contribution is from light-fermion loops. The Higgs-dependent terms are small, even if the Higgs boson is heavy. We have analyzed the mass shifts for models with a more complicated Higgs sector. We use the on-shell renormalization scheme, in which the parameters of the theory are the physical masses and couplings. We have considered the 2-doublet, n-doublet, triplet and doublet-triplet models. We have found that the Z-boson mass prediction has a strong dependence on the charged-Higgs mass. In the limit that the charged Higgs is much heavier than the gauge bosons, the Higgs-dependent terms become significant, and may even cancel the light-fermion terms. In the models with a Higgs triplet, there is also a strong dependence on the neutral-Higgs masses, although this contribution tends to be suppressed in realistic models. The W-boson mass shift does not have a strong Higgs dependence. If we use the Z mass as input in determining the parameters of the theory, a scenario which will become attractive as the mass of the Z is accurately measured in the next few years, we find that the W-boson mass shift exhibits the same sort of behavior, differing from the minimal model for the case of the charged Higgs being heavy. We have found that when radiative corrections are taken into account, models with extended Higgs sectors may differ significantly from the minimal standard model in their predictions for the gauge-boson masses. Thus, an accurate measurement of the masses will help shed light on the structure of the Higgs sector. 68 refs

  5. On the origin of mass and the electroweak mass spectrum without Higgs

    International Nuclear Information System (INIS)

    Souza, Manoelito Martins de

    1994-01-01

    Full text: In a Causality Preserving Manifold Formalism, (CPMF), which is based on a model of spacetime with geometric and strict implementation of causality, masses are consequences of the spacetime symmetries. The mass spectrum of a set of non Abelian fields is solely determined from its Lagrangian kinematics term, in a way independent of any kind of interactions and without any extra field (no Higgs, no Yukawa coupling). The origin and meaning of mass in this formalism is discussed and then illustrated with the vector boson sector of the standard SU(2)x U(1) electroweak theory. (author)

  6. On the origin of mass and the electroweak mass spectrum without Higgs

    International Nuclear Information System (INIS)

    Souza, Manoelita Martins

    1995-01-01

    In a Causality Preserving Manifold Formalism (CPMF), which is based on a new model of spacetime, masses are consequences of spacetime structure symmetries. The mass spectrum of a set of non Abelian fields is solely determined from its Lagrangian kinematic term, in a way independent of any kind of interactions and without any extra field (no Higgs, no Yukawa couplings etc). After a brief review about this CPMF, the origin and meaning of mass is discussed and then illustrated with the vector boson sector of the SU(2) x U(1) electroweak theory. (author)

  7. Higgs-boson contributions to gauge-boson mass shifts in extended electroweak models

    International Nuclear Information System (INIS)

    Moore, S.R.

    1985-01-01

    The author analyzed the mass shifts for models with a more complicated Higgs sector. He uses the on-shell renormalization scheme, in which the parameters of the theory are the physical masses and couplings. The author has considered the 2-doublet, n-doublet, triplet and doublet-triplet models. He has found that the Z-boson mass prediction has a strong dependence on the charged-Higgs mass. In the limit that the charged Higgs is much heavier than the gauge bosons, the Higgs-dependent terms become significant, and may even cancel the light-fermion terms. If the author uses the Z mass as input in determining the parameters of the theory, a scenario which will become attractive as the mass of the Z is accurately measured in the next few years, it is found that the W-boson mass shift exhibits the same sort of behavior, differing from the minimal model for the case of the charged Higgs being heavy. The author has found that when the radiative corrections are taken into account, models with extended Higgs sectors may differ significantly from the minimal standard model in this predictions for the gauge-boson masses. Thus, an accurate measurement of the masses will help shed light on the structure of the Higgs sector

  8. LHC phenomenology and higher order electroweak corrections in supersymmetric models with and without R-parity

    Energy Technology Data Exchange (ETDEWEB)

    Liebler, Stefan Rainer

    2011-09-15

    The standard model of particle physics lacks on some shortcomings from experimental as well as from theoretical point of view: There is no approved mechanism for the generation of masses of the fundamental particles, in particular also not for the light, but massive neutrinos. In addition the standard model does not provide an explanation for the observance of dark matter in the universe. Moreover the gauge couplings of the three forces in the standard model do not unify, implying that a fundamental theory combining all forces can not be formulated. Within this thesis we address supersymmetric models as answers to these various questions, but instead of focusing on the most simple supersymmetrization of the standard model, we consider basic extensions, namely the next-to-minimal supersymmetric standard model (NMSSM), which contains an additional singlet field, and R-parity violating models. Using lepton number violating terms in the context of bilinear R-parity violation and the {mu}{nu}SSM we are able to explain neutrino physics intrinsically supersymmetric, since those terms induce a mixing between the neutralinos and the neutrinos. This thesis works out the phenomenology of the supersymmetric models under consideration and tries to point out differences to the well-known features of the simplest supersymmetric realization of the standard model. In case of the R-parity violating models the decays of the light neutralinos can result in displaced vertices. In combination with a light singlet state these displaced vertices might offer a rich phenomenology like non-standard Higgs decays into a pair of singlinos decaying with displaced vertices. Within this thesis we present some calculations at next order of perturbation theory, since one-loop corrections provide possibly large contributions to the tree-level masses and decay widths. We are using an on-shell renormalization scheme to calculate the masses of neutralinos and charginos including the neutrinos and

  9. LHC phenomenology and higher order electroweak corrections in supersymmetric models with and without R-parity

    International Nuclear Information System (INIS)

    Liebler, Stefan Rainer

    2011-09-01

    The standard model of particle physics lacks on some shortcomings from experimental as well as from theoretical point of view: There is no approved mechanism for the generation of masses of the fundamental particles, in particular also not for the light, but massive neutrinos. In addition the standard model does not provide an explanation for the observance of dark matter in the universe. Moreover the gauge couplings of the three forces in the standard model do not unify, implying that a fundamental theory combining all forces can not be formulated. Within this thesis we address supersymmetric models as answers to these various questions, but instead of focusing on the most simple supersymmetrization of the standard model, we consider basic extensions, namely the next-to-minimal supersymmetric standard model (NMSSM), which contains an additional singlet field, and R-parity violating models. Using lepton number violating terms in the context of bilinear R-parity violation and the μνSSM we are able to explain neutrino physics intrinsically supersymmetric, since those terms induce a mixing between the neutralinos and the neutrinos. This thesis works out the phenomenology of the supersymmetric models under consideration and tries to point out differences to the well-known features of the simplest supersymmetric realization of the standard model. In case of the R-parity violating models the decays of the light neutralinos can result in displaced vertices. In combination with a light singlet state these displaced vertices might offer a rich phenomenology like non-standard Higgs decays into a pair of singlinos decaying with displaced vertices. Within this thesis we present some calculations at next order of perturbation theory, since one-loop corrections provide possibly large contributions to the tree-level masses and decay widths. We are using an on-shell renormalization scheme to calculate the masses of neutralinos and charginos including the neutrinos and leptons in

  10. Cancellation of leading divergences in left-right electroweak model and heavy particles

    International Nuclear Information System (INIS)

    Andrianov, A.A.; Romanenko, N.V.

    1997-01-01

    The fine-tuning principles are analyzed in search for estimation of heavy-particle masses in the left-right symmetric model. The modification of Veltman condition based on the hypothesis of the compression between fermion and boson energies within the left-right model multiples is proposed. The hypothesis is supplied with the requirement of the stability under rescaling. With regard to these requirements the necessity of existence of right-handed Majorana neutrinos with masses of order of right-handed gauge bosons is shown and estimations on the top-quark which are in a good agreement with the experimental value are obtained

  11. Breaking of electroweak symmetry: origin and effects

    International Nuclear Information System (INIS)

    Delaunay, C.

    2008-10-01

    The Higgs boson appears as the corner stone of high energy physics, it might be the cause of the excess of matter that led to the formation of the structures of the universe and it seems that it drives the breaking of the electroweak symmetry. Moreover, when the stability at low energies of the Higgs boson is assured by an extra space dimension, it appears that this extra dimension can explain most issues in the flavor physics that are not understood by the standard model. The first chapter presents the main tools of effective field theories, the role of experimental data in the construction of theories valid beyond the standard model is discussed. The second chapter focuses on the electroweak baryogenesis that allows the testing of new physics via the electroweak phase transition. We detail the calculation of a Higgs potential at finite temperature. We follow the dynamics of the phase transition including nucleation an supercooling. Finally we investigate the prospects of gravity wave detection to see the effects of a strong electroweak phase transition. The 2 last chapters are dedicated to the physics of extra-dimension. The properties of the dynamics of scalar, vector fields with a 1/2 spin plunged in a 5 d. Anti de Sitter geometry are reviewed. We present a model of lepton masses and mixings based on the A 4 non-Abelian discrete symmetry. It is shown that this model does not contradict the tests of electroweak precision. (A.C.)

  12. Finite energy electroweak dyon

    Energy Technology Data Exchange (ETDEWEB)

    Kimm, Kyoungtae [Seoul National University, Faculty of Liberal Education, Seoul (Korea, Republic of); Yoon, J.H. [Konkuk University, Department of Physics, College of Natural Sciences, Seoul (Korea, Republic of); Cho, Y.M. [Konkuk University, Administration Building 310-4, Seoul (Korea, Republic of); Seoul National University, School of Physics and Astronomy, Seoul (Korea, Republic of)

    2015-02-01

    The latest MoEDAL experiment at LHC to detect the electroweak monopole makes the theoretical prediction of the monopole mass an urgent issue. We discuss three different ways to estimate the mass of the electroweak monopole. We first present the dimensional and scaling arguments which indicate the monopole mass to be around 4 to 10 TeV. To justify this we construct finite energy analytic dyon solutions which could be viewed as the regularized Cho-Maison dyon, modifying the coupling strength at short distance. Our result demonstrates that a genuine electroweak monopole whose mass scale is much smaller than the grand unification scale can exist, which can actually be detected at the present LHC. (orig.)

  13. Electroweak Higgs boson production in the standard model effective field theory beyond leading order in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Degrande, Celine [CERN, Theory Division, Geneva 23 (Switzerland); Fuks, Benjamin [Sorbonne Universites, UPMC Univ. Paris 06, Paris (France); CNRS, Paris (France); Mawatari, Kentarou [Universite Grenoble-Alpes, Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France); Vrije Universiteit Brussel, Theoretische Natuurkunde and IIHE/ELEM, International Solvay Institutes, Brussels (Belgium); Mimasu, Ken [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom); Universite catholique de Louvain, Centre for Cosmology, Particle Physics and Phenomenology (CP3), Louvain-la-Neuve (Belgium); Sanz, Veronica [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom)

    2017-04-15

    We study the impact of dimension-six operators of the standard model effective field theory relevant for vector-boson fusion and associated Higgs boson production at the LHC. We present predictions at the next-to-leading order accuracy in QCD that include matching to parton showers and that rely on fully automated simulations. We show the importance of the subsequent reduction of the theoretical uncertainties in improving the possible discrimination between effective field theory and standard model results, and we demonstrate that the range of the Wilson coefficient values allowed by a global fit to LEP and LHC Run I data can be further constrained by LHC Run II future results. (orig.)

  14. Simulating the electroweak phase transition in the SU(2) Higgs model

    International Nuclear Information System (INIS)

    Fodor, Z.; Hein, J.; Jansen, K.; Jaster, A.; Montvay, I.

    1994-09-01

    Numerical simulations are performed to study the finite temperature phase transition in the SU(2) Higgs model on the lattice. In the presently investigated range of the Higgs boson mass, below 50 GeV, the phase transition turns out to be of first order and its strength is rapidly decreasing with increasing Higgs boson mass. In order to control the systematic errors, we also perform studies of scaling violations and of finite volume effects. (orig.)

  15. Electroweak radiative B-decays as a test of the Standard Model and beyond

    International Nuclear Information System (INIS)

    Tayduganov, A.

    2011-10-01

    Recently the radiative B-decay to strange axial-vector mesons, B → K 1 (1270)γ, was observed with a rather large branching ratio. This process is particularly interesting as the subsequent K 1 -decay into its three-body final state allows us to determine the polarization of the photon, which is mostly left(right)-handed for B-bar(B) in the Standard Model while various new physics models predict additional right(left)-handed components. In this thesis, a new method is proposed to determine the polarization, exploiting the full Dalitz plot distribution, which seems to reduce significantly the statistical errors on the polarization parameter λ γ measurement. This polarization measurement requires, however a detailed knowledge of the K 1 → Kππ strong interaction decays, namely, the complex pattern of various partial wave amplitudes into the several possible quasi-two-body channels as well as their relative phases. A number of experiments have been done to extract all these information while there remain various problems in the previous studies. In this thesis, we investigate the details of these problems. As a theoretical tool, we use the 3 P 0 quark-pair-creation model in order to improve our understanding of strong K 1 -decays. Finally we try to estimate some theoretical uncertainties: in particular, the one coming from the uncertainty on the K 1 mixing angle, and the effect of a possible 'off-set' phase in strong decay S-waves. According to our estimations, the systematic errors are found to be of the order of σ λ γ (th) ≤ 20%. On the other hand, we discuss the sensitivity of the future experiments, namely the SuperB factories and LHCb, to λ γ . Naively estimating the annual signal yields, we found the statistical error of the new method to be σ λ γ (stat) ≤ 10% which turns out to be reduced by a factor 2 with respect to using the simple angular distribution. We also discuss a comparison to the other methods of the polarization measurement using

  16. Electroweak interaction parameters

    International Nuclear Information System (INIS)

    Marciano, W.J.

    1984-01-01

    After a presentation of the experimentally determined parameters of the standard SU(3) x SU(2) x U(1) model the author discusses the definition of the Weinberg angle. Then masses and widths of the intermediate vector bosons are considered in the framework of the Weinberg-Salam theory with radiative corrections. Furthermore the radiative decays of these bosons are discussed. Then the relations between the masses of the Higgs boson and the top quark are considered. Thereafter grand unification is briefly discussed with special regards to the SU(5) prediction of some observable parameters. Finally some speculations are made concerning the observation of radiative decays in the UA1 experiments. (HSI)

  17. Search for physics beyond the standard electroweak model with the WITCH experiment

    CERN Document Server

    Van Gorp, Simon

    A measurement of the $\\beta$-neutrino angular correlation coefficient $a$ yields information on possible exotic couplings in the weak interaction. To this end the energy distribution of the recoiling daughter nucleus after $\\beta$-decay, which depends on $a$, is measured precisely. Any deviation of the measured distribution with the one expected from the Standard Model can reveal new physics. If no deviation is found stringent limits can be set on the possible presence of different types of new physics beyond the Standard Model. The WITCH experiment, located at ISOLDE, CERN aims to determine $a$ with a final precision below 1%. $\\\\$ Ion bunches are created with REXTRAP and injected in the WITCH setup. The energy of these ion bunches is pulsed down in the Pulsed Drift Tube section, prior to the capture of the ions in the first of two Penning traps. The motion of the radioactive ions is cooled before the transfer to a second Penning trap, the decay trap, which acts as the scattering-free sou...

  18. Split NMSSM with electroweak baryogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Demidov, S.V.; Gorbunov, D.S. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary prospect 7a, Moscow 117312 (Russian Federation); Moscow Institute of Physics and Technology,Institutsky per. 9, Dolgoprudny 141700 (Russian Federation); Kirpichnikov, D.V. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary prospect 7a, Moscow 117312 (Russian Federation)

    2016-11-24

    In light of the Higgs boson discovery and other results of the LHC we reconsider generation of the baryon asymmetry in the split Supersymmetry model with an additional singlet superfield in the Higgs sector (non-minimal split SUSY). We find that successful baryogenesis during the first order electroweak phase transition is possible within a phenomenologically viable part of the model parameter space. We discuss several phenomenological consequences of this scenario, namely, predictions for the electric dipole moments of electron and neutron and collider signatures of light charginos and neutralinos.

  19. Electroweak processes at Run 2

    CERN Document Server

    Spalla, Margherita; Sestini, Lorenzo

    2016-01-01

    We present a summary of the studies of the electroweak sector of the Standard Model at LHC after the first year of data taking of Run2, focusing on possible results to be achieved with the analysis of full 2015 and 2016 data. We discuss the measurements of W and Z boson production, with particular attention to the precision determination of basic Standard Model parameters, and the study of multi-boson interactions through the analysis of boson-boson final states. This work is the result of the collaboration between scientists from the ATLAS, CMS and LHCb experiments.

  20. One loop electro-weak radiative corrections in the standard model

    International Nuclear Information System (INIS)

    Kalyniak, P.; Sundaresan, M.K.

    1987-01-01

    This paper reports on the effect of radiative corrections in the standard model. A sensitive test of the three gauge boson vertices is expected to come from the work in LEPII in which the reaction e + e - → W + W - can occur. Two calculations of radiative corrections to the reaction e + e - → W + W - exist at present. The results of the calculations although very similar disagree with one another as to the actual magnitude of the correction. Some of the reasons for the disagreement are understood. However, due to the reasons mentioned below, another look must be taken at these lengthy calculations to resolve the differences between the two previous calculations. This is what is being done in the present work. There are a number of reasons why we must take another look at the calculation of the radiative corrections. The previous calculations were carried out before the UA1, UA2 data on W and Z bosons were obtained. Experimental groups require a computer program which can readily calculate the radiative corrections ab initio for various experimental conditions. The normalization of sin 2 θ w in the previous calculations was done in a way which is not convenient for use in the experimental work. It would be desirable to have the analytical expressions for the corrections available so that the renormalization scheme dependence of the corrections could be studied

  1. Neutrino masses in the flipped SU(5)xU(1) and the SU(4)xO(4) GUT models

    Energy Technology Data Exchange (ETDEWEB)

    Papageorgiu, E.; Ranfone, S. (Rutherford Appleton Lab., Chilton (United Kingdom))

    1992-05-21

    We classify the different neutrino-mass patterns arising in string-inspired GUT and supersymmetric GUT models based on the flipped SU(5)xU(1) and the SU(4)xO(4) gauge groups. Phenomenologically interesting spectra are obtained through the interplay of the two seesaw mechanisms present, with typical neutrino masses {proportional to}10{sup -3} eV in the supersymmetric GUT models and of order 0.1-10 keV in the ordinary GUTs. (orig.).

  2. The electroweak polarization asymmetry: A guided tour

    International Nuclear Information System (INIS)

    Kennedy, D.C.

    1988-10-01

    A comprehensive review is provided of the electroweak polarization asymmetry at the Z 0 , a highly accurate measure of the Z 0 coupling to fermions. Its significance as a precision test of the Standard Model is explored in detail. Emphasized are the role of electroweak symmetry-breaking and radiative corrections; the non-decoupling of new physics beyond the Z 0 ; and the testing of extensions of the Standard Model, such as supersymmetry, technicolor, new generations of fermions, grand unification, and new gauge forces. Also discussed are the relationship of the polarization asymmetry to other electroweak observables and its superiority to other Z 0 asymmetries. Experimental issues are briefly presented, stressing the importance of polarization at the SLC and LEP e + e - colliders. 42 refs., 13 figs., 2 tabs

  3. What's new with the electroweak phase transition?

    CERN Document Server

    Laine, M.

    1999-01-01

    We review the status of non-perturbative lattice studies of the electroweak phase transition. In the Standard Model, the complete phase diagram has been reliably determined, and the conclusion is that there is no phase transition at all for the experimentally allowed Higgs masses. In the Minimal Supersymmetric Standard Model (MSSM), in contrast, there can be a strong first order transition allowing for baryogenesis. Finally, we point out possibilities for future simulations, such as the problem of CP-violation at the MSSM electroweak phase boundary.

  4. ELECTROWEAK PHYSICS AND PRECISION STUDIES

    International Nuclear Information System (INIS)

    MARCIANO, W.

    2005-01-01

    The utility of precision electroweak measurements for predicting the Standard Model Higgs mass via quantum loop effects is discussed. Current values of m W , sin 2 θ W (m Z ) # ovr MS# and m t imply a relatively light Higgs which is below the direct experimental bound but possibly consistent with Supersymmetry expectations. The existence of Supersymmetry is further suggested by a 2σ discrepancy between experiment and theory for the muon anomalous magnetic moment. Constraints from precision studies on other types of ''New Physics'' are also briefly described

  5. Electroweak precision measurements in CMS

    CERN Document Server

    Dordevic, Milos

    2017-01-01

    An overview of recent results on electroweak precision measurements from the CMS Collaboration is presented. Studies of the weak boson differential transverse momentum spectra, Z boson angular coefficients, forward-backward asymmetry of Drell-Yan lepton pairs and charge asymmetry of W boson production are made in comparison to the state-of-the-art Monte Carlo generators and theoretical predictions. The results show a good agreement with the Standard Model. As a proof of principle for future W mass measurements, a W-like analysis of the Z boson mass is performed.

  6. Higgs Phase in a Gauge U(1 Non-Linear CP1-Model. Two Species of BPS Vortices and Their Zero Modes

    Directory of Open Access Journals (Sweden)

    Alberto Alonso-Izquierdo

    2016-09-01

    Full Text Available In this paper, zero modes of fluctuation are dissected around the two species of BPS vortices existing in the critical Higgs phase, where the scalar and vector meson masses are equal, of a gauged U ( 1 nonlinear CP 1 -model. If 2 π n , n ∈ Z , is the quantized magnetic flux of the two species of BPS vortex solutions, 2 n linearly-independent vortex zero modes for each species are found and described. The existence of two species of moduli spaces of dimension 2 n of these stringy topological defects is thus locally shown.

  7. Vacuum expectation values of Higgs scalars in a SU(2)/sub L/ x SU(2)/sub R/ x U(1) gauge model

    International Nuclear Information System (INIS)

    Kitazoe, T.; Mainland, G.B.; Tanaka, K.

    1979-01-01

    We determine the vacuum expectation values of the Higgs scalars within the framework of a six-quark SU(2)/sub L/ x SU(2)/sub R/ x U(1) gauge model after the imposition of discrete symmetries that are necessary in order to express the Cabibbo angle in terms of quark mass ratios and phases of the vacuum expectation values. We find both real and complex solutions for the vacuum expectation values depending on the relative values of the parameters in the Higgs potential

  8. Vacuum expectation values of Higgs scalars in a SU(2)/sub L/ X SU(2)/sub R/ X U(1) gauge model

    International Nuclear Information System (INIS)

    Kitazoe, T.; Mainland, G.B.; Tanaka, K.

    1978-01-01

    The vacuum expectation values of the Higgs scalars are determined within the framework of a six quark SU(2)/sub L/ x SU(2)/sub R/ x U(1) gauge model after the imposition of discrete symmetrics that are necessary in order to express the Cabibbo angle in terms of quark mass ratios and phases of the vacuum expectation values. Both real and complex solutions are found for the vacuum expectation values depending on the relative values of the parameters in the Higgs potential

  9. Opening the window for electroweak baryogenesis

    CERN Document Server

    Carena, M S; Wagner, C E M

    1996-01-01

    We perform an analysis of the behaviour of the electroweak phase transition in the Minimal Supersymmetric Standard Model, in the presence of light stops. We show that, in previously unexplored regions of parameter space, the order parameter v(T_c)/T_c can become significantly larger than one, for values of the Higgs and supersymmetric particle masses consistent with the present experimental bounds. This implies that baryon number can be efficiently generated at the electroweak phase transition. As a by-product of this study, we present an analysis of the problem of colour breaking minima at zero and finite temperature, and we use it to investigate the region of parameter space preferred by the best fit to the present precision electroweak measurement data, in which the left-handed stops are much heavier than the right-handed ones.

  10. S- and T-matrices for the super U(1,1) WZW model application to surgery and 3-manifolds invariants based on the Alexander-Conway polynomial

    International Nuclear Information System (INIS)

    Rozansky, L.; Saleur, H.

    1993-01-01

    We carry on (in a self-contained fashion) the study of the Alexander-Conway invariant from the quantum field theory point of view started earlier. We investigate for that purpose various aspects of WZW models on supergroups. We first discuss in details S- and T-matrices for the U(1,1) super WZW model and obtain, for the level k an integer, new finite-dimensional representations of the modular group. These have the remarkable property that some of the S-matrix elements are infinite (we show how to properly handle such divergences). Moreover, typical and atypical representations as well as indecomposable blocks are mixed: Truncation to maximally atypical representations, as advocated in some recent papers, is not consistent. Using our approach, multivariable Alexander invariants for links in S 3 can now be fully computed by surgery. Examples of torus and cable knots are discussed. Consistency with classical results provides independent checks of the solution of the U(1,1) WZW model. The main topological application of this work is the computation of Alexander invariants for 3-manifolds and more generally for links in 3-manifolds. Invariants of 3-manifolds themselves seem to depend trivially on the level k, but still contain interesting topological information. For Seifer manifolds for instance, they essentially coincide with the order (number of elements) of the first homology group. Examples of invariants of links in 3-manifolds are given. They exhibit interesting arithmetic properties. (orig.)

  11. Electroweak interactions at LEP

    International Nuclear Information System (INIS)

    Borgia, B.

    1991-01-01

    Electroweak interaction at LEP are a subject based on a wealth of data, given the success of the CERN e + e - storage ring. The author will report on the results from the four experiments, ALEPH, DELPHI, L3 and OPAL after the analysis of about 1/2 of the data collected in 1989 and 1990. The review will cover the electroweak aspects of the process e + e - → Z* → f bar f where the fermions can be either quarks or leptons. The analysis of experimental data is based on the determination of the cross section integrated on the solid angle and on the asymmetry of forward-backward leptons in the final state. In this game the knowledge of the center mass energy is fundamental as the determination of the luminosity by which the event rate is normalized to compute the absolute cross section. Therefore a specific attention is given to these subjects

  12. Torons, chiral symmetry breaking and U(1) problem in σ-model and in gauge theories. Part 1

    International Nuclear Information System (INIS)

    Zhitnitskij, A.R.

    1989-01-01

    A novel class of self-dual solutions in σ-models and in SU(2) gauge theories is considered. The solution is defined on manifold with boundary, it has topological charge Q=1/2. The contribution of the corresponding fluctuations and toron configurations to chiral condensate is calculated. This contribution has finite nonzero value. The APS (Atiyah, Patodi, Singer) theorem for a manifold with a boundary is discussed for the O(3) σ model. The necessity of imposing non-local boundary conditions for the Dirac operator is explained. 30 refs.; 4 figs

  13. Electroweak unification and tree unitarity

    International Nuclear Information System (INIS)

    Horejsi, J.

    1993-01-01

    The monograph is an unconventional introduction into the theory of unification of weak and electromagnetic interactions, which is conceptually different from the exposition presented in standard textbooks. A detailed explanation is given of the way to the standard model of electroweak interactions which is based on a straightforward application of the requirement of renormalizability of the perturbation series expansion. The procedure to derive the model is interesting as it demonstrates the necessity of introducing vector bosons and Yang-Mills type interactions and at least one elementary scalar boson to obtain a renormalizable theory of weak and electromagnetic interactions. The book is divided into 5 chapters: introduction, problems encountered in a Fermi type theory, the intermediate vector boson, electrodynamics of vector bosons, tree unitarity, and electroweak interactions. Each chapter is completed with exercise problems to be solved by the reader. The text is supplemented with a number of appendices. The monograph is aimed at undergraduate and postgraduate students as well as at physicists interested in the theory of elementary particles. (Z.J.)

  14. U (1 ) -symmetric infinite projected entangled-pair states study of the spin-1/2 square J1-J2 Heisenberg model

    Science.gov (United States)

    Haghshenas, R.; Sheng, D. N.

    2018-05-01

    We develop an improved variant of U (1 ) -symmetric infinite projected entangled-pair states (iPEPS) ansatz to investigate the ground-state phase diagram of the spin-1 /2 square J1-J2 Heisenberg model. In order to improve the accuracy of the ansatz, we discuss a simple strategy to select automatically relevant symmetric sectors and also introduce an optimization method to treat second-neighbor interactions more efficiently. We show that variational ground-state energies of the model obtained by the U (1 ) -symmetric iPEPS ansatz (for a fixed bond dimension D ) set a better upper bound, improving previous tensor-network-based results. By studying the finite-D scaling of the magnetically order parameter, we find a Néel phase for J2/J1place at J2c2/J1=0.610 (2 ) to the conventional Stripe phase. We compare our results with earlier DMRG and PEPS studies and suggest future directions for resolving remaining issues.

  15. Baryogenesis at the electroweak scale

    International Nuclear Information System (INIS)

    Dine, M.; Huet, P.; Singleton, R. Jr.

    1992-01-01

    We explore some issues involved in generating the baryon asymmetry at the electroweak scale. A simple two-dimensional model is analyzed which illustrates the role of the effective action in computing the asymmetry. We stress the fact that baryon production ceases at a very small value of the Higgs field; as a result, certain two-Higgs models which have been studied recently cannot produce sufficient asymmetry, while quite generally models with only doublets can barely produce the observed baryon density; models with gauge singlets are more promising. We also review limits on Higgs masses coming from the requirement that the baryon asymmetry not be wiped out after the phase transition. We note that there are a variety of uncertainties in these calculations, and that even in models with a single Higgs doublet one cannot rule out a Higgs mass below 55 GeV. (orig.)

  16. Estimation of standard model backgrounds to the search for electroweak production of supersymmetry in events with at least two tau leptons in the final state

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Sebastian

    2013-11-04

    This thesis presents a search for Supersymmetry in events with at least two hadronically decaying tau leptons and missing transverse energy. The analysis is focused on the electro-weak production of gaugino pairs. Electroweak production processes for SUSY particles are promising candidates for the discovery of Supersymmetry with R-parity conservation at hadron-hadron colliders. For the analysis a sample of proton-proton collisions at a center of mass energy of √(s)=8 TeV with an integrated luminosity of ∫ L dt=20.3 fb{sup -1} is used. The collisions have been recorded with the ATLAS detector at the LHC in the year 2012. In two different selections the Standard Model predictions are compared with the observations. The observation of 6 events in the first selection and 14 in the second does not deviate significantly from the Standard Model with an expectation of 11 events in the first selection and 17 in the second. These results are interpreted in a phenomenological Minimal Supersymmetric Standard Model and in simplified models. For a simplified model with a chargino-neutralino pair production scenario the parameter space for masses of the lightest neutralino up to 100 GeV and up to 350 GeV for the lightest chargino mass can be excluded. For a simplified model with chargino pair production processes the parameter space for the lightest neutralino mass up to 30-50 GeV in a range for the lightest chargino mass of 170-330 GeV can be excluded. This thesis is focused on the estimation techniques of Standard Model background processes. Different methods for the estimation of the background originating from Z-boson and top-quark decays are investigated.

  17. Rare B-meson decays in SU(2)LxSU(2)RxU(1) model

    International Nuclear Information System (INIS)

    Asatryan, H.M.; Ioannissian, A.N.

    1989-01-01

    Rare B-meson decays are investigated in the left-right synmmetric models. The scalar particle contribution to the amplitude of the b → s γ decay is calculated. It is shown that this contribution can be essential even for the scalar particles masses of about several TeV. The effects due to the left-right symmetry and scalar particles can be detected by measuring the photon polarization in the decay B → K * γ. 9 refs.; 1 fig.; 1 tab

  18. CMS results in Electroweak Physics

    CERN Multimedia

    CERN. Geneva

    2011-01-01

    We present the results of electroweak studies performed using data collected in 2010 at a center-of-mass energy of 7 TeV by the CMS experiment at the LHC. Besides their intrinsic interest as unique samples to calibrate and understand the CMS detector response to leptons, jets and missing energy, events containing W and Z bosons appear as dominant components in many Higgs seaches and in most of the searches beyond the Standard Model, either as signal or as background. In addition, the excellent level of theoretical and experimental understanding of these processes allows electroweak tests at the LHC at an unprecendented level of precision. CMS uses a wide range of final states to measure cross sections, asymmetries, polarizations and differential distributions in general. The current integrated luminosity is already sufficient to perform not just inclusive measurements using W and Z decays into muons and electrons, but also precise studies of associated jet production and final states containing taus, as well...

  19. Torons, chiral symmetry breaking and U(1) problem in σ-model and gauge theories. Part 2

    International Nuclear Information System (INIS)

    Zhitnitskij, A.R.

    1989-01-01

    The main point of this work is the physical consenquences of the existence of fractional charge in the σ-models and espesially in the physically interesting theory QCD. It is shown that the corresponding fluctuations ensure spontaneous breaking of the chiral symmetry and give a nonzero contribution to the chiral condensate. Toron solution is determined on the manifold with boundary. In this case many questions arise such as: global boundary conditions, the stability of the solution, self-adjointness of Dirac operator, single-valuedness of the physical values and so on. These questions are interconnected and turn out to be self cobsistent only for the special choice of the topological number (Q=1/2 for SU(2)). It is shown that in the Dirac's spectrum of the quarks the gap between zero and the continuum is absent. 50 refs.; 10 figs

  20. Non linear realizations of SU(2) x U(1) in the MSSM model independent analysis and g - 2 of W bosons

    CERN Document Server

    Ferrara, Sergio; Porrati, Massimo; Ferrara, Sergio; Masiero, Antonio; Porrati, Massimo

    1993-01-01

    We perform a model-independent analysis of the spontaneously broken phase of an $SU(2)\\times U(1)$ supersymmetric gauge theory, by using a non-linear parametrization of the Goldstone sector of the theory. The non-linear variables correspond to an $SL(2,C)$ superfield matrix in terms of which a non-linear Lagrangian can be constructed, and the pattern of supersymmetry breaking investigated. The supersymmetric order parameter is the V.E.V. of the neutral pseudo-Goldstone boson. Some applications of this technique are considered, in relation to the minimal supersymmetric standard model, and to determine the $g-2$ of the $W$-bosons in the limit of large top mass.

  1. Towards a natural theory of electroweak interactions

    Science.gov (United States)

    Dobrescu, Bogdan A.

    1998-01-01

    I study theories of electroweak symmetry breaking that may describe naturally the electromagnetic and weak interactions of the elementary particles observed so far (quarks, leptons and gauge bosons). These theories should explain why the energy scale at which the electroweak symmetry is spontaneously broken (246 GeV), called the 'electroweak scale', is seventeen orders of magnitude smaller than the 'Planck scale', which is associated with the quantum origin of gravity. I discuss first theories where the electroweak symmetry is broken by the dynamics of new strong interactions, naturally producing the hierarchy between the Planck scale and the electroweak scale. I show that in a realistic class of models of this type, the new gauge bosons needed for generating the mass of the heaviest quark have couplings which require a careful adjustment in order to be compatible with experimental data. In the case where the strong dynamics produces a composite spinless particle ('Higgs boson') whose interactions break the electroweak symmetry, I derive an upper bound of 460 GeV on the Higgs boson mass from experimental constraints on processes sensitive to new physics. I also discuss a different type of theory that explains the hierarchy of energy scales, based on a special symmetry, called supersymmetry, which requires the existence of new particles ('superpartners'). No superpartners have been seen in experiments. Therefore, if they exist, they must have masses larger than the particles known so far, implying that supersymmetry is not exact. In the simplest models, supersymmetry breaking is transmitted to the superpartners by standard gauge interactions. I show that all known models of this type are likely to be unacceptable because they do not admit a stable and phenomenologically viable ground state of the universe ('vacuum'). I then construct modified versions of these models that permit viable stable vacua. Also, I present a new model in which supersymmetry breaking is

  2. Lower bound on the electroweak wall velocity from hydrodynamic instability

    Energy Technology Data Exchange (ETDEWEB)

    Mégevand, Ariel; Membiela, Federico Agustín; Sánchez, Alejandro D., E-mail: megevand@mdp.edu.ar, E-mail: membiela@mdp.edu.ar, E-mail: sanchez@mdp.edu.ar [IFIMAR (CONICET-UNMdP), Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Deán Funes (7600) 3350 Mar del Plata (Argentina)

    2015-03-01

    The subsonic expansion of bubbles in a strongly first-order electroweak phase transition is a convenient scenario for electroweak baryogenesis. For most extensions of the Standard Model, stationary subsonic solutions (i.e., deflagrations) exist for the propagation of phase transition fronts. However, deflagrations are known to be hydrodynamically unstable for wall velocities below a certain critical value. We calculate this critical velocity for several extensions of the Standard Model and compare with an estimation of the wall velocity. In general, we find a region in parameter space which gives stable deflagrations as well as favorable conditions for electroweak baryogenesis.

  3. Lower bound on the electroweak wall velocity from hydrodynamic instability

    International Nuclear Information System (INIS)

    Mégevand, Ariel; Membiela, Federico Agustín; Sánchez, Alejandro D.

    2015-01-01

    The subsonic expansion of bubbles in a strongly first-order electroweak phase transition is a convenient scenario for electroweak baryogenesis. For most extensions of the Standard Model, stationary subsonic solutions (i.e., deflagrations) exist for the propagation of phase transition fronts. However, deflagrations are known to be hydrodynamically unstable for wall velocities below a certain critical value. We calculate this critical velocity for several extensions of the Standard Model and compare with an estimation of the wall velocity. In general, we find a region in parameter space which gives stable deflagrations as well as favorable conditions for electroweak baryogenesis

  4. Lower bound on the electroweak wall velocity from hydrodynamic instability

    Energy Technology Data Exchange (ETDEWEB)

    Mégevand, Ariel; Membiela, Federico Agustín; Sánchez, Alejandro D. [IFIMAR (CONICET-UNMdP), Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Deán Funes (7600) 3350 Mar del Plata (Argentina)

    2015-03-27

    The subsonic expansion of bubbles in a strongly first-order electroweak phase transition is a convenient scenario for electroweak baryogenesis. For most extensions of the Standard Model, stationary subsonic solutions (i.e., deflagrations) exist for the propagation of phase transition fronts. However, deflagrations are known to be hydrodynamically unstable for wall velocities below a certain critical value. We calculate this critical velocity for several extensions of the Standard Model and compare with an estimation of the wall velocity. In general, we find a region in parameter space which gives stable deflagrations as well as favorable conditions for electroweak baryogenesis.

  5. Electroweak precision tests

    International Nuclear Information System (INIS)

    Monteil, St.

    2009-12-01

    This document aims at summarizing a dozen of years of the author's research in High Energy Physics, in particular dealing with precision tests of the electroweak theory. Parity violating asymmetries measurements at LEP with the ALEPH detector together with global consistency checks of the Kobayashi-Maskawa paradigm within the CKM-fitter group are gathered in the first part of the document. The second part deals with the unpublished instrumental work about the design, tests, productions and commissioning of the elements of the Pre-Shower detector of the LHCb spectrometer at LHC. Physics perspectives with LHCb are eventually discussed as a conclusion. (author)

  6. Electroweak form factors of the Skyrmion

    International Nuclear Information System (INIS)

    Braaten, E.; Sze-Man Tse; Willcox, C.

    1986-01-01

    The electroweak form factors of baryons are studied in the semiclassical approximation to the Skyrme model. General expressions for the form factors are given for arbitrary choices of the Skyrme-model Lagrangian. They are applied to the original two-parameter Skyrme model to compute the electric, magnetic, and axial-vector form factors of the nucleon and the electromagnetic nucleon-Δ transition form factors. The dependence of the form factors on the momentum transfer is compared with phenomenological dipole parametrizations

  7. Electroweak probes with ATLAS

    CERN Document Server

    Milov, Alexander; The ATLAS collaboration

    2018-01-01

    Measuring electroweak bosons in relativistic heavy ion collisions at high energy provide an opportunity to understand temporal evolution of the quark-gluon plasma created in such collisions by constraining the initial state of the interaction. Due to lack of colour charges the bosons and or particles produced in their leptonic decays are unaffected by the quark-gluon plasma and therefore preserve the information about the very early stage of the collision when they were born. This singles EW bosons as a unique and very interesting class of observables in HI collisions. The ATLAS experiment at LHC measures production of electroweak bosons in $pp$, $p$+Pb and Pb+Pb collisions systems. A review of the existing results is given in this proceeding that includes studies made with isolated photons to constraint kinematic properties and flavour composition of associated jets, measurements of $W$ and $Z$ bosons used to estimate nuclear modification of PDF and the production rates of the bosons used to verify geometric...

  8. Energy helps accuracy: electroweak precision tests at hadron colliders

    CERN Document Server

    Farina, Marco

    2017-09-10

    We show that high energy measurements of Drell-Yan at the LHC can serve as electroweak precision tests. Dimension-6 operators, from the Standard Model Effective Field Theory, modify the high energy behavior of electroweak gauge boson propagators. Existing measurements of the dilepton invariant mass spectrum, from neutral current Drell-Yan at 8 TeV, have comparable sensitivity to LEP. We propose measuring the transverse mass spectrum of charged current Drell-Yan, which can surpass LEP already with 8 TeV data. The 13 TeV LHC will elevate electroweak tests to a new precision frontier.

  9. Energy helps accuracy: Electroweak precision tests at hadron colliders

    Directory of Open Access Journals (Sweden)

    Marco Farina

    2017-09-01

    Full Text Available We show that high energy measurements of Drell–Yan at the LHC can serve as electroweak precision tests. Dimension-6 operators, from the Standard Model Effective Field Theory, modify the high energy behavior of electroweak gauge boson propagators. Existing measurements of the dilepton invariant mass spectrum, from neutral current Drell–Yan at 8 TeV, have comparable sensitivity to LEP. We propose measuring the transverse mass spectrum of charged current Drell–Yan, which can surpass LEP already with 8 TeV data. The 13 TeV LHC will elevate electroweak tests to a new precision frontier.

  10. Bino-driven electroweak baryogenesis with highly suppressed electric dipole moments

    Energy Technology Data Exchange (ETDEWEB)

    Li Yingchuan [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)], E-mail: yli@physics.wisc.edu; Profumo, Stefano [Department of Physics and Santa Cruz Institute for Particle Physics, University of California, 1156 High St., Santa Cruz, CA 95064 (United States)], E-mail: profumo@scipp.ucsc.edu; Ramsey-Musolf, Michael [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States)], E-mail: mjrm@physics.wisc.edu

    2009-03-09

    It is conventional wisdom that successful electroweak baryogenesis in the Minimal Supersymmetric extension of the Standard Model (MSSM) is in tension with the non-observation of electric dipole moments (EDMs), since the level of CP-violation responsible for electroweak baryogenesis is believed to generate unavoidably large EDMs. We show that CP-violation in the bino-Higgsino sector of the MSSM can account for successful electroweak baryogenesis without inducing large EDMs. This observation weakens the correlation between electroweak baryogenesis and EDMs, and makes the bino-driven electroweak baryogenesis scenario the least constrained by EDM limits. Taking this observation together with the requirement of a strongly first-order electroweak phase transition, we argue that a bino-driven scenario with a light stop is the most phenomenologically viable MSSM electroweak baryogenesis scenario.

  11. Bino-driven electroweak baryogenesis with highly suppressed electric dipole moments

    International Nuclear Information System (INIS)

    Li Yingchuan; Profumo, Stefano; Ramsey-Musolf, Michael

    2009-01-01

    It is conventional wisdom that successful electroweak baryogenesis in the Minimal Supersymmetric extension of the Standard Model (MSSM) is in tension with the non-observation of electric dipole moments (EDMs), since the level of CP-violation responsible for electroweak baryogenesis is believed to generate unavoidably large EDMs. We show that CP-violation in the bino-Higgsino sector of the MSSM can account for successful electroweak baryogenesis without inducing large EDMs. This observation weakens the correlation between electroweak baryogenesis and EDMs, and makes the bino-driven electroweak baryogenesis scenario the least constrained by EDM limits. Taking this observation together with the requirement of a strongly first-order electroweak phase transition, we argue that a bino-driven scenario with a light stop is the most phenomenologically viable MSSM electroweak baryogenesis scenario

  12. Study of electroweak gauge boson scattering in the WZ channel with the ATLAS detector at the Large Hadron Collider

    Energy Technology Data Exchange (ETDEWEB)

    Socher, Felix

    2016-07-15

    The Standard Model of particle physics is a very well tested gauge theory describing the strong, weak and electromagnetic interactions between elementary particles through the exchange of force carriers called gauge bosons. Its high predictive power stems from its ability to derive the properties of the interactions it describes from fundamental symmetries of nature. Yet, it is not a final theory as there are several phenomena it cannot explain. Furthermore, not all of its predictions have been studied with sufficient precision, e.g. the properties of the newly discovered Higgs boson. Therefore, further probing of the Standard Model is necessary and may result in finding possible indications for new physics. The non-abelian SU(2){sub L} x U(1){sub Y} symmetry group determines the properties of the electromagnetic and weak interactions giving rise to self-couplings between the electroweak gauge bosons, i.e. the massive W and Z boson, and the massless photon, via triple and quartic gauge couplings. Studies carried out over the past 20 years at various particle accelerator experiments have shed light on the structure of the triple gauge couplings but few results on quartic gauge couplings are available. The electroweak self-couplings are intertwined with the electroweak symmetry breaking and thus the Higgs boson through the scattering of massive electroweak gauge bosons. Both the W and Z boson couple to the Higgs boson and may interact with each other by exchanging it. Theory predictions yield physical results at high energies only if either both the self-couplings and Higgs boson properties are as described by the Standard Model or if they deviate from its predictions and contributions from new physics are present to render the calculations finite. This makes electroweak gauge boson scattering a powerful tool to probe the Standard Model and search for possible effects of new physics. The small cross section of massive electroweak gauge boson scattering necessitates

  13. Study of electroweak gauge boson scattering in the WZ channel with the ATLAS detector at the Large Hadron Collider

    International Nuclear Information System (INIS)

    Socher, Felix

    2016-01-01

    The Standard Model of particle physics is a very well tested gauge theory describing the strong, weak and electromagnetic interactions between elementary particles through the exchange of force carriers called gauge bosons. Its high predictive power stems from its ability to derive the properties of the interactions it describes from fundamental symmetries of nature. Yet, it is not a final theory as there are several phenomena it cannot explain. Furthermore, not all of its predictions have been studied with sufficient precision, e.g. the properties of the newly discovered Higgs boson. Therefore, further probing of the Standard Model is necessary and may result in finding possible indications for new physics. The non-abelian SU(2)_L x U(1)_Y symmetry group determines the properties of the electromagnetic and weak interactions giving rise to self-couplings between the electroweak gauge bosons, i.e. the massive W and Z boson, and the massless photon, via triple and quartic gauge couplings. Studies carried out over the past 20 years at various particle accelerator experiments have shed light on the structure of the triple gauge couplings but few results on quartic gauge couplings are available. The electroweak self-couplings are intertwined with the electroweak symmetry breaking and thus the Higgs boson through the scattering of massive electroweak gauge bosons. Both the W and Z boson couple to the Higgs boson and may interact with each other by exchanging it. Theory predictions yield physical results at high energies only if either both the self-couplings and Higgs boson properties are as described by the Standard Model or if they deviate from its predictions and contributions from new physics are present to render the calculations finite. This makes electroweak gauge boson scattering a powerful tool to probe the Standard Model and search for possible effects of new physics. The small cross section of massive electroweak gauge boson scattering necessitates high centre

  14. Flavor universal dynamical electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Burdman, G.; Evans, N.

    1999-01-01

    The top condensate seesaw mechanism of Dobrescu and Hill allows electroweak symmetry to be broken while deferring the problem of flavor to an electroweak singlet, massive sector. We provide an extended version of the singlet sector that naturally accommodates realistic masses for all the standard model fermions, which play an equal role in breaking electroweak symmetry. The models result in a relatively light composite Higgs sector with masses typically in the range of (400 - 700) GeV. In more complete models the dynamics will presumably be driven by a broken gauged family or flavor symmetry group. As an example of the higher scale dynamics a fully dynamical model of the quark sector with a GIM mechanism is presented, based on an earlier top condensation model of King using broken family gauge symmetry interactions (that model was itself based on a technicolor model of Georgi). The crucial extra ingredient is a reinterpretation of the condensates that form when several gauge groups become strong close to the same scale. A related technicolor model of Randall which naturally includes the leptons too may also be adapted to this scenario. We discuss the low energy constraints on the massive gauge bosons and scalars of these models as well as their phenomenology at the TeV scale. copyright 1999 The American Physical Society

  15. Predictions for the neutrino parameters in the minimal gauged U(1){sub L{sub μ-L{sub τ}}} model

    Energy Technology Data Exchange (ETDEWEB)

    Asai, Kento; Nagata, Natsumi [University of Tokyo, Department of Physics, Bunkyo-ku, Tokyo (Japan); Hamaguchi, Koichi [University of Tokyo, Department of Physics, Bunkyo-ku, Tokyo (Japan); University of Tokyo, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), Kashiwa (Japan)

    2017-11-15

    We study the structure of the neutrino-mass matrix in the minimal gauged U(1){sub L{sub μ-L{sub τ}}} model, where three right-handed neutrinos are added to the Standard Model in order to obtain non-zero masses for the active neutrinos. Because of the U(1){sub L{sub μ-L{sub τ}}} gauge symmetry, the structure of both Dirac and Majorana mass terms of neutrinos is tightly restricted. In particular, the inverse of the neutrino-mass matrix has zeros in the (μ,μ) and (τ,τ) components, namely, this model offers a symmetric realization of the so-called two-zero-minor structure in the neutrino-mass matrix. Due to these constraints, all the CP phases - the Dirac CP phase δ and the Majorana CP phases α{sub 2} and α{sub 3} - as well as the mass eigenvalues of the light neutrinos m{sub i} are uniquely determined as functions of the neutrino mixing angles θ{sub 12}, θ{sub 23}, and θ{sub 13}, and the squared mass differences Δm{sub 21}{sup 2} and Δm{sub 31}{sup 2}. We find that this model predicts the Dirac CP phase δ to be δ ≅ 1.59π-1.70π (1.54π-1.78π), the sum of the neutrino masses to be sum {sub i}m{sub i} ≅ 0.14-0.22 eV (0.12-0.40 eV), and the effective mass for the neutrinoless double-beta decay to be left angle m{sub ββ} right angle ≅ 0.024-0.055 eV (0.017-0.12 eV) at 1σ (2σ) level, which are totally consistent with the current experimental limits. These predictions can soon be tested in future neutrino experiments. Implications for leptogenesis are also discussed. (orig.)

  16. A demonstration that electroweak theory can violate parity automatically (leptonic case)

    Science.gov (United States)

    Furey, C.

    2018-02-01

    We bring to light an electroweak model which has been reappearing in the literature under various guises.1-5 In this model, weak isospin is shown to act automatically on states of only a single chirality (left). This is achieved by building the model exclusively from the raising and lowering operators of the Clifford algebra ℂl(4). That is, states constructed from these ladder operators mimic the behaviour of left- and right-handed electrons and neutrinos under unitary ladder operator symmetry. This ladder operator symmetry is found to be generated uniquely by su(2)L and u(1)Y. Crucially, the model demonstrates how parity can be maximally violated, without the usual step of introducing extra gauge and extra Higgs bosons, or ad hoc projectors.

  17. A (critical) overview of electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Csaki, Csaba

    2010-01-01

    This presentation discusses the following points: The standard Higgs, big vs. little hierarchy; Electroweak Symmetry Breaking in supersymmetry and little hierarchy of Minimal Supersymmetric Standard Model (MSSM): Buried Higgs, Bigger quartic (D-terms, Next-to-Minimal Supersymmetric Standard Model (NMSSM), fat Higgs,..); Strong dynamics and related models: Technicolor, Monopole condensate, Warped extra dimensions, Realistic RS, Higgs-less, Composite Higgs, Little Higgs. In summary, we do not understand how Higgs is light and still no trace of new physics. In Supersymmetry (SUSY) it calls for extension of MSSM. In strong dynamics models: electroweak penguin (EWP) usually issue (Warped extra dimension - composite Higgs, Higgs-less, Little Higgs, Technicolor, monopole condensation,..). None of them is fully convincing but LHC should settle these

  18. Introduction to gauge theories of electroweak interactions

    International Nuclear Information System (INIS)

    Ecker, G.

    1982-01-01

    Intended as a lecture for physicists who are not familiar with the sophisticated theoretical models in particle physics. Starting with the standard gauge model of electromagnetic, weak and strong interactions the recent developments of a unified gauge theory of electroweak interactions are shown. Shortcomings in the unitarity problem of the V-A fermi theory of charged intermediate vector bosons. Presented are the spontaneous symmetry breaking in quantum mechanics, the abelian higgs model as an example of a spontaneously broken gauge field theory, the minimal gauge group of electroweak interactions, the fermion mass generation. Further on the anomalies in quantum field theory are discussed and the radiative corrections to the vector boson masses are considered. (H.B.)

  19. Longitudinal Trim and Tumble Characteristics of a 0.057-Scale Model of the Chance Vought XF7U-1 Airplane, TED NO. NACA DE311

    Science.gov (United States)

    Bryant, Robert L.

    1948-01-01

    Based on results of longitudinal trim and tumble tests of a 0.057-scale model of the Chance Vought XF7U-1 airplane, the following conclusions regarding the trim and tumble characteristics of the airplane have been drawn: 1. The airplane will not trim at any unusual or uncontrolled angles of attack. 2. The airplane will not tumble with the center of gravity located forward of 24 percent of the mean aerodynamic chord. When the center of gravity is located at 24 percent of the mean aerodynamic chord and slats are extended and elevators are deflected full up, the airplane may tumble if given an external positive pitching moment. 3. The tumbling motion obtained will be readily terminated by deflecting the elevators full down so as to oppose the rotation. 4. The accelerations encountered during an established tumble may be dangerous to the pilot and, therefore, action should be taken to terminate a tumble immediately upon its inception. 5. Simultaneous opening of two wing-tip parachutes having diameters of 4 feet or larger and having drag coefficients of approximately 0.7 will effectively terminate the tumble. 6. Model results indicate that the pilot will not be struck by the airplane if it becomes necessary to leave the airplane during a tumble. The pilot may require aid from an ejection-seat arrangement.

  20. Flavor changing neutral currents, CP violation, and implications for some rare decays in a SU(4)L x U(1)X extension of the standard model

    International Nuclear Information System (INIS)

    Jaramillo, Alejandro; Sanchez, Luis A.

    2011-01-01

    Extensions of the standard model with gauge symmetry SU(3) c x SU(4) L x U(1) X (3-4-1 extensions) where anomaly cancellation takes place between the fermion families (three-family models) predict the existence of two new heavy neutral gauge bosons which transmit flavor changing neutral currents at tree level. In this work, in the context of a three-family 3-4-1 extension which does not contain particles with exotic electric charges, we study the constraints coming from neutral meson mixing on the parameters of the extension associated to tree-level flavor changing neutral current effects. Taking into account experimental measurements of observables related to K and B meson mixing and including new CP-violating phases, we study the resulting bounds for angles and phases in the mixing matrix for the down-quark sector, as well as the implications of these bounds for the modifications in the amplitudes of the clean rare decays K + →π + νν, K L →π 0 νν, K L →π 0 l + l - (l=e, μ) and B d/s →μ + μ - .

  1. Concepts of electroweak symmetry breaking and Higgs physics

    International Nuclear Information System (INIS)

    Gomez-Bock, M.; Zerwas, P.M.; RWTH Aachen; Univ. Paris- Sud, Orsay

    2007-12-01

    We present an introduction to the basic concepts of electroweak symmetry breaking and Higgs physics within the Standard Model and its supersymmetric extensions. A brief overview will also be given on alternative mechanisms of electroweak symmetry breaking. In addition to the theoretical basis, the present experimental status of Higgs physics and prospects at the Tevatron, the LHC and e + e - linear colliders are discussed. (orig.)

  2. Concepts of electroweak symmetry breaking and Higgs physics

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Bock, M. [Benemerita Univ., Puebla (Mexico). Inst. de Fisica; Mondragon, M. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Fisica; Muehlleitner, M. [Laboratoire d' Annecy-Le-Vieux de Physique Theorique, 74 (France)]|[CERN - European Organization for Nuclear Research, Geneva (Switzerland). Theory Div.; Spira, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Zerwas, P.M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[RWTH Aachen (Germany). Inst. Theor. Physik E]|[Univ. Paris- Sud, Orsay (France). Laboratoire de Physique Theorique

    2007-12-15

    We present an introduction to the basic concepts of electroweak symmetry breaking and Higgs physics within the Standard Model and its supersymmetric extensions. A brief overview will also be given on alternative mechanisms of electroweak symmetry breaking. In addition to the theoretical basis, the present experimental status of Higgs physics and prospects at the Tevatron, the LHC and e{sup +}e{sup -} linear colliders are discussed. (orig.)

  3. Probing neutrino and Higgs sectors in SU(2){sub 1} x SU(2){sub 2} x U(1){sub Y} model with lepton-flavor non-universality

    Energy Technology Data Exchange (ETDEWEB)

    Hue, L.T. [Duy Tan University, Institute of Research and Development, Da Nang City (Viet Nam); Vietnam Academy of Science and Technology, Institute of Physics, Hanoi (Viet Nam); Arbuzov, A.B. [Joint Institute for Nuclear Researches, Bogoliubov Laboratory for Theoretical Physics, Dubna (Russian Federation); Ngan, N.T.K. [Cantho University, Department of Physics, Cantho (Viet Nam); Vietnam Academy of Science and Technology, Graduate University of Science and Technology, Hanoi (Viet Nam); Long, H.N. [Ton Duc Thang University, Theoretical Particle Physics and Cosmology Research Group, Ho Chi Minh City (Viet Nam); Ton Duc Thang University, Faculty of Applied Sciences, Ho Chi Minh City (Viet Nam)

    2017-05-15

    The neutrino and Higgs sectors in the SU(2){sub 1} x SU(2){sub 2} x U(1){sub Y} model with lepton-flavor non-universality are discussed. We show that active neutrinos can get Majorana masses from radiative corrections, after adding only new singly charged Higgs bosons. The mechanism for the generation of neutrino masses is the same as in the Zee models. This also gives a hint to solving the dark matter problem based on similar ways discussed recently in many radiative neutrino mass models with dark matter. Except the active neutrinos, the appearance of singly charged Higgs bosons and dark matter does not affect significantly the physical spectrum of all particles in the original model. We indicate this point by investigating the Higgs sector in both cases before and after singly charged scalars are added into it. Many interesting properties of physical Higgs bosons, which were not shown previously, are explored. In particular, the mass matrices of charged and CP-odd Higgs fields are proportional to the coefficient of triple Higgs coupling μ. The mass eigenstates and eigenvalues in the CP-even Higgs sector are also presented. All couplings of the SM-like Higgs boson to normal fermions and gauge bosons are different from the SM predictions by a factor c{sub h}, which must satisfy the recent global fit of experimental data, namely 0.995 < vertical stroke c{sub h} vertical stroke < 1. We have analyzed a more general diagonalization of gauge boson mass matrices, then we show that the ratio of the tangents of the W-W{sup '} and Z-Z{sup '} mixing angles is exactly the cosine of the Weinberg angle, implying that number of parameters is reduced by 1. Signals of new physics from decays of new heavy fermions and Higgs bosons at LHC and constraints of their masses are also discussed. (orig.)

  4. D-term contributions and CEDM constraints in E6 × SU(2)F × U(1)A SUSY GUT model

    Science.gov (United States)

    Shigekami, Yoshihiro

    2017-11-01

    We focus on E6 × SU(2)F × U(1)A supersymmetric (SUSY) grand unified theory (GUT) model. In this model, realistic Yukawa hierarchies and mixings are realized by introducing all allowed interactions with 𝓞(1) coefficients. Moreover, we can take stop mass is smaller than the other sfermion masses. This type of spectrum called by natural SUSY type sfermion mass spectrum can suppress the SUSY contributions to flavor changing neutral current (FCNC) and stabilize weak scale at the same time. However, light stop predicts large up quark CEDM and stop contributions are not decoupled. Since there is Kobayashi-Maskawa phase, stop contributions to the up quark CEDM is severely constrained even if all SUSY breaking parameters and Higgsino mass parameter μ are real. In this model, real up Yukawa couplings are realized at the GUT scale because of spontaneous CP violation. Therefore CEDM bounds are satisfied, although up Yukawa couplings are complex at the SUSY scale through the renormalization equation group effects. We calculated the CEDMs and found that EDM constraints can be satisfied even if stop mass is 𝓞(1) TeV. In addition, we investigate the size of D-terms in this model. Since these D-term contributions is flavor dependent, the degeneracy of sfermion mass spectrum is destroyed and the size of D-term is strongly constrained by FCNCs when SUSY breaking scale is the weak scale. However, SUSY breaking scale is larger than 1 TeV in order to obtain 125 GeV Higgs mass, and therefore sizable D-term contribution is allowed. Furthermore, we obtained the non-trivial prediction for the difference of squared sfermion mass.

  5. Probing neutrino and Higgs sectors in { SU(2) }_1 × { SU(2) }_2 × { U(1) }_Y model with lepton-flavor non-universality

    Science.gov (United States)

    Hue, L. T.; Arbuzov, A. B.; Ngan, N. T. K.; Long, H. N.

    2017-05-01

    The neutrino and Higgs sectors in the { SU(2) }_1 × { SU(2) }_2 × { U(1) }_Y model with lepton-flavor non-universality are discussed. We show that active neutrinos can get Majorana masses from radiative corrections, after adding only new singly charged Higgs bosons. The mechanism for the generation of neutrino masses is the same as in the Zee models. This also gives a hint to solving the dark matter problem based on similar ways discussed recently in many radiative neutrino mass models with dark matter. Except the active neutrinos, the appearance of singly charged Higgs bosons and dark matter does not affect significantly the physical spectrum of all particles in the original model. We indicate this point by investigating the Higgs sector in both cases before and after singly charged scalars are added into it. Many interesting properties of physical Higgs bosons, which were not shown previously, are explored. In particular, the mass matrices of charged and CP-odd Higgs fields are proportional to the coefficient of triple Higgs coupling μ . The mass eigenstates and eigenvalues in the CP-even Higgs sector are also presented. All couplings of the SM-like Higgs boson to normal fermions and gauge bosons are different from the SM predictions by a factor c_h, which must satisfy the recent global fit of experimental data, namely 0.995<|c_h|<1. We have analyzed a more general diagonalization of gauge boson mass matrices, then we show that the ratio of the tangents of the W-W' and Z-Z' mixing angles is exactly the cosine of the Weinberg angle, implying that number of parameters is reduced by 1. Signals of new physics from decays of new heavy fermions and Higgs bosons at LHC and constraints of their masses are also discussed.

  6. Hyperscaling violation and electroweak symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Elander, Daniel, E-mail: pelander@purdue.edu [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907-2036 (United States); Lawrance, Robert; Piai, Maurizio [Department of Physics, College of Science, Swansea University, Singleton Park, Swansea, Wales (United Kingdom)

    2015-08-15

    We consider a class of simplified models of dynamical electroweak symmetry breaking built in terms of their five-dimensional weakly-coupled gravity duals, in the spirit of bottom-up holography. The sigma-model consists of two abelian gauge bosons and one real, non-charged scalar field coupled to gravity in five dimensions. The scalar potential is a simple exponential function of the scalar field. The background metric resulting from solving the classical equations of motion exhibits hyperscaling violation, at least at asymptotically large values of the radial direction. We study the spectrum of scalar composite states of the putative dual field theory by fluctuating the sigma-model scalars and gravity, and discuss in which cases we find a parametrically light scalar state in the spectrum. We model the spontaneous breaking of the (weakly coupled) gauge symmetry to the diagonal subgroup by the choice of IR boundary conditions. We compute the mass spectrum of spin-1 states, and the precision electroweak parameter S as a function of the hyperscaling coefficient. We find a general bound on the mass of the lightest spin-1 resonance, by requiring that the indirect bounds on the precision parameters be satisfied, that implies that precision electroweak physics excludes the possibility of a techni-rho meson with mass lighter than several TeV.

  7. Topological excitations in U(1) -invariant theories

    International Nuclear Information System (INIS)

    Savit, R.

    1977-01-01

    A class of U(1) -invariant theories in d dimensions is introduced on a lattice. These theories are labeled by a simplex number s, with 1 < or = s < d. The case with s = 1 is the X-Y model; and s = 2 gives compact photodynamics. An exact duality transformation is applied to show that the U(1) -invariant theory in d dimensions with simplex number s is the same as a similar theory in d dimensions but which is Z /sub infinity/-invariant and has simplex number s = d-s. This dual theory describes the topological excitations of the original theory. These excitations are of dimension s - 1

  8. PRECISION ELECTROWEAK MEASUREMENTS AND THE HIGGS MASS

    International Nuclear Information System (INIS)

    MARCIANO, W.J.

    2004-01-01

    The utility of precision electroweak measurements for predicting the Standard Model Higgs mass via quantum loop effects is discussed. Current constraints from m w and sin 2 θ w (m z ) ovr MS imply a relatively light Higgs ∼< 154 GeV which is consistent with Supersymmetry expectations. The existence of Supersymmetry is further suggested by a discrepancy between experiment and theory for the muon anomalous magnetic moment. Constraints from precision studies on other types of ''New Physics'' are also briefly described

  9. On stability of electroweak vacuum during inflation

    Energy Technology Data Exchange (ETDEWEB)

    Shkerin, A., E-mail: andrey.shkerin@epfl.ch [Institut de Théorie des Phénomènes Physiques, EPFL, CH-1015 Lausanne (Switzerland); Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, 117312 Moscow (Russian Federation); Sibiryakov, S. [Institut de Théorie des Phénomènes Physiques, EPFL, CH-1015 Lausanne (Switzerland); Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, 117312 Moscow (Russian Federation); CERN Theory Division, CH-1211 Geneva 23 (Switzerland)

    2015-06-30

    We study Coleman–De Luccia tunneling of the Standard Model Higgs field during inflation in the case when the electroweak vacuum is metastable. We verify that the tunneling rate is exponentially suppressed. The main contribution to the suppression is the same as in flat space–time. We analytically estimate the corrections due to the expansion of the universe and an effective mass term in the Higgs potential that can be present at inflation.

  10. On stability of electroweak vacuum during inflation

    International Nuclear Information System (INIS)

    Shkerin, A.; Sibiryakov, S.

    2015-01-01

    We study Coleman–De Luccia tunneling of the Standard Model Higgs field during inflation in the case when the electroweak vacuum is metastable. We verify that the tunneling rate is exponentially suppressed. The main contribution to the suppression is the same as in flat space–time. We analytically estimate the corrections due to the expansion of the universe and an effective mass term in the Higgs potential that can be present at inflation

  11. On stability of electroweak vacuum during inflation

    CERN Document Server

    Shkerin, Andrey

    2015-01-01

    We study Coleman-De Luccia tunneling of the Standard Model Higgs field during inflation in the case when the electroweak vacuum is metastable. We verify that the tunneling rate is exponentially suppressed. The main contribution to the suppression is the same as in flat space-time. We analytically estimate the corrections due to the expansion of the universe and an effective mass term in the Higgs potential that can be present at inflation.

  12. Electroweak physics and electron scattering

    International Nuclear Information System (INIS)

    Henley, E.M.; Hwang, W.Y.P.

    1988-01-01

    The electroweak theory is developed and applied to electron scattering from nucleons and light nuclei. It is shown that these scatterings can be used to test the standard theory and probe structure effects. 33 refs., 5 figs

  13. Peccei-Quinn invariant singlet extended SUSY with anomalous U(1) gauge symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Im, Sang Hui; Seo, Min-Seok [Center for Theoretical Physics of the Universe, Institute for Basic Science (IBS),Daejeon 305-811 (Korea, Republic of)

    2015-05-13

    Recent discovery of the SM-like Higgs boson with m{sub h}≃125 GeV motivates an extension of the minimal supersymmetric standard model (MSSM), which involves a singlet Higgs superfield with a sizable Yukawa coupling to the doublet Higgs superfields. We examine such singlet-extended SUSY models with a Peccei-Quinn (PQ) symmetry that originates from an anomalous U(1){sub A} gauge symmetry. We focus on the specific scheme that the PQ symmetry is spontaneously broken at an intermediate scale v{sub PQ}∼√(m{sub SUSY}M{sub Pl}) by an interplay between Planck scale suppressed operators and tachyonic soft scalar mass m{sub SUSY}∼√(D{sub A}) induced dominantly by the U(1){sub A}D-term D{sub A}. This scheme also results in spontaneous SUSY breaking in the PQ sector, generating the gaugino masses M{sub 1/2}∼√(D{sub A}) when it is transmitted to the MSSM sector by the conventional gauge mediation mechanism. As a result, the MSSM soft parameters in this scheme are induced mostly by the U(1){sub A}D-term and the gauge mediated SUSY breaking from the PQ sector, so that the sparticle masses can be near the present experimental bounds without causing the SUSY flavor problem. The scheme is severely constrained by the condition that a phenomenologically viable form of the low energy operators of the singlet and doublet Higgs superfields is generated by the PQ breaking sector in a way similar to the Kim-Nilles solution of the μ problem, and the resulting Higgs mass parameters allow the electroweak symmetry breaking with small tan β. We find two minimal models with two singlet Higgs superfields, satisfying this condition with a relatively simple form of the PQ breaking sector, and briefly discuss some phenomenological aspects of the model.

  14. Search for electroweak production of supersymmetric states in Non-Universal Higgs Mass model with two extra parameters compressed scenario with the ATLAS detector

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00529728

    The ATLAS and CMS collaborations announced the discovery of the Higgs boson in July 2012, completing the particle content of the Standard Model. Although the Standard Model is a great triumph, it is not considered to be the complete theory of particle physics. Several new theories have been proposed which seek to move beyond the Standard Model. Among the newly-developed theories, Supersymmetry (SUSY) is one of the most promising ones. SUSY predicts the existence of supersymmetric partner particles and it is one of the best-motivated extensions of the space-time symmetry of particle interactions. There are supersymmetric partner particles associated with each SM particles in which the spin differs by 1/2. This dissertation focuses on a search for electroweak production of supersymmetric particles with compressed mass spectra in the final states with exactly two low-momentum leptons and missing transverse momentum. The proton-proton collision data is recorded by the ATLAS detector at the Large Hadron Collider i...

  15. Holographic theories of electroweak symmetry breaking without a Higgs Boson

    International Nuclear Information System (INIS)

    Burdman, Gustavo; Nomura, Yasunori

    2003-01-01

    Recently, realistic theories of electroweak symmetry breaking have been constructed in which the electroweak symmetry is broken by boundary conditions imposed at a boundary of higher dimensional spacetime. These theories have equivalent 4D dual descriptions, in which the electroweak symmetry is dynamically broken by non-trivial infrared dynamics of some gauge interaction, whose gauge coupling (tilde g) and size N satisfy (tilde g) 2 N ∼> 16π 2 . Such theories allow one to calculate electroweak radiative corrections, including the oblique parameters S, T and U, as long as (tilde g) 2 N/16π 2 and N are sufficiently larger than unity. We study how the duality between the 4D and 5D theories manifests itself in the computation of various physical quantities. In particular, we calculate the electroweak oblique parameters in a warped 5D theory where the electroweak symmetry is broken by boundary conditions at the infrared brane. We show that the value of S obtained in the minimal theory exceeds the experimental bound if the theory is in a weakly coupled regime. This requires either an extension of the minimal model or departure from weak coupling. A particularly interesting scenario is obtained if the gauge couplings in the 5D theory take the largest possible values--the value suggested by naive dimensional analysis. We argue that such a theory can provide a potentially consistent picture for dynamical electroweak symmetry breaking: corrections to the electroweak observables are sufficiently small while realistic fermion masses are obtained without conflicting with bounds from flavor violation. The theory contains only the standard model quarks, leptons and gauge bosons below ≅2 TeV, except for a possible light scalar associated with the radius of the extra dimension. At ≅2 TeV increasingly broad string resonances appear. An analysis of top-quark phenomenology and flavor violation is also presented, which is applicable to both the weakly-coupled and strongly

  16. Electroweak results from the tevatron

    International Nuclear Information System (INIS)

    Wood, D.

    1997-01-01

    Electroweak results are presented from the CDF and DO experiments based on data collected in recent runs of the Fermilab Tevatron Collider. The measurements include the mass and width of the W boson, the production cross sections of the W and Z bosons, and the W charge asymmetry. Additional results come from studies of events with pairs of electroweak gauge bosons and include limits on anomalous couplings

  17. Electroweak results from the tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Wood, D. [Fermi National Accelerator Laboratory, Batavia, IL (United States)

    1997-01-01

    Electroweak results are presented from the CDF and DO experiments based on data collected in recent runs of the Fermilab Tevatron Collider. The measurements include the mass and width of the W boson, the production cross sections of the W and Z bosons, and the W charge asymmetry. Additional results come from studies of events with pairs of electroweak gauge bosons and include limits on anomalous couplings.

  18. Electroweak boson production at LHCb

    CERN Document Server

    Sestini, Lorenzo

    2018-01-01

    The LHCb experiment offers a complementary phase space to ATLAS and CMS to study electroweak processes, thanks to the forward acceptance and the large bandwidth of the trigger allowing low energy thresholds. For this reason electroweak measurements at LHCb can provide unique constraints to the Parton Distribution Functions. Moreover these measurements can be used to validate reconstruction techniques. In these proceedings the latest measurements on W and Z bosons production performed during the LHC Run I and Run II data taking are presented.

  19. Gauged U(1) clockwork theory

    Science.gov (United States)

    Lee, Hyun Min

    2018-03-01

    We consider the gauged U (1) clockwork theory with a product of multiple gauge groups and discuss the continuum limit of the theory to a massless gauged U (1) with linear dilaton background in five dimensions. The localization of the lightest state of gauge fields on a site in the theory space naturally leads to exponentially small effective couplings of external matter fields localized away from the site. We discuss the implications of our general discussion with some examples, such as mediators of dark matter interactions, flavor-changing B-meson decays as well as D-term SUSY breaking.

  20. 3.5 keV X-ray line signal from dark matter decay in local U(1){sub B−L} extension of Zee-Babu model

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Seungwon [School of Physics and Open KIAS Center, KIAS,85 Hoegiro Dongdaemun-gu, Seoul 130-722 (Korea, Republic of)

    2015-08-06

    We consider a local U(1){sub B−L} extension of Zee-Babu model to explain the recently observed 3.5 keV X-ray line signal. The model has three Standard model (SM)-singlet Dirac fermions with different U(1){sub B−L} charges. A complex scalar field charged under U(1){sub B−L} is introduced to break the U(1){sub B−L} symmetry. After U(1){sub B−L} symmetry breaking a remnant discrete symmetry stabilizes the lightest state of the Dirac fermions, which can be a stable dark matter (DM). The second lightest state, if mass splitting with the stable DM is about 3.5 keV, decays dominantly to the stable DM and 3.5 keV photon through two-loop diagrams, explaining the X-ray line signal. Two-loop suppression of the decay amplitude makes its lifetime much longer than the age of the universe and it can be a decaying DM candidate in large parameter region. We also introduce a real scalar field which is singlet under both the SM and U(1){sub B−L} and can explain the current relic abundance of the Dirac fermionic DMs. If the mixing with the SM Higgs boson is small, it does not contribute to DM direct detection. The main contribution to the scattering of DM off atomic nuclei comes from the exchange of U(1){sub B−L} gauge boson, Z{sup ′}, and is suppressed below current experimental bound when Z{sup ′} mass is heavy (≳10 TeV). If the singlet scalar mass is about 0.1–10 MeV, DM self-interaction can be large enough to solve small scale structure problems in simulations with the cold DM, such as, the core-vs-cusp problem and too-big-to-fail problem.

  1. Indirect Probe of Electroweak-Interacting Particles at Future Lepton Colliders

    International Nuclear Information System (INIS)

    Harigaya, Keisuke

    2015-04-01

    Various types of electroweak-interacting particles, which have non-trivial charges under the SU(2) L x U(1) Y gauge symmetry, appear in various extensions of the Standard Model. These particles are good targets of future lepton colliders, such as the International Linear Collider (ILC), the Compact LInear Collider (CLIC) and the Future Circular Collider of electrons and positrons (FCC-ee). An advantage of the experiments is that, even if their beam energies are below the threshold of the production of the new particles, quantum effects of the particles can be detected through high precision measurements. We estimate the capability of future lepton colliders to probe electroweak-interacting particles through the quantum effects, with particular focus on the wino, the Higgsino and the so-called minimal dark matters, and found that a particle whose mass is greater than the beam energy by 100-1000 GeV is detectable by measuring di-fermion production cross sections with O(0.1)% accuracy. In addition, with the use of the same analysis, we also discuss the sensitivity of the future colliders to model independent higher dimensional operators, and found that the cutoff scales corresponding to the operators can be probed up to a few ten TeV.

  2. Indirect probe of electroweak-interacting particles at future lepton colliders

    International Nuclear Information System (INIS)

    Harigaya, Keisuke; Ichikawa, Koji; Kundu, Anirban; Matsumoto, Shigeki; Shirai, Satoshi

    2015-01-01

    Various types of electroweak-interacting particles, which have non-trivial charges under the SU(2)_L×U(1)_Y gauge symmetry, appear in various extensions of the Standard Model. These particles are good targets of future lepton colliders, such as the International Linear Collider (ILC), the Compact LInear Collider (CLIC) and the Future Circular Collider of electrons and positrons (FCC-ee). An advantage of the experiments is that, even if their beam energies are below the threshold of the production of the new particles, quantum effects of the particles can be detected through high precision measurements. We estimate the capability of future lepton colliders to probe electroweak-interacting particles through the quantum effects, with particular focus on the wino, the Higgsino and the so-called minimal dark matters, and found that a particle whose mass is greater than the beam energy by 100–1000 GeV is detectable by measuring di-fermion production cross sections with O(0.1)% accuracy. In addition, with the use of the same analysis, we also discuss the sensitivity of the future colliders to model independent higher dimensional operators, and found that the cutoff scales corresponding to the operators can be probed up to a few ten TeV.

  3. On the U(1) problem

    International Nuclear Information System (INIS)

    McDougall, N.A.

    1984-01-01

    The resolution of the U(1) problem requires the quark condensates to have a specific THETA dependence. We show that the required THETA dependence arises naturally upon application of the index theorem during the calculation of the dynamically generated quark mass. (orig.)

  4. On-shell gauge-parameter independence of contributions to electroweak quark self-energies

    International Nuclear Information System (INIS)

    Ahmady, M.R.; Elias, V.; Mendel, R.R.; Scadron, M.D.; Steele, T.

    1989-01-01

    We allow an external condensate to enter standard SU(2) x U(1) electroweak theory via the vacuum expectation value , as in QCD sum-rule applications. For a given flavor, we then find that any gauge-parameter dependence of quark self-energies on the ''mass shell'' is eliminated provided that the mass shell is made to coincide with both the expansion-parameter mass occurring in the operator-product expansion of and the standard electroweak mass acquired via the Yukawa coupling to the usual scalar vacuum expectation value of spontaneous symmetry breaking. This result indicates that if the QCD-generated order parameter and associated dynamical mass(es) m/sub q//sup dyn/ are utilized as external input parameters in electroweak calculations involving hadrons, then new corrections must be introduced into the q-barqW and q-barqZ vertices in order to preserve SU(2) x U(1) Ward identities

  5. R2SM: a package for the analytic computation of the R2 Rational terms in the Standard Model of the Electroweak interactions

    International Nuclear Information System (INIS)

    Garzelli, M.V.

    2011-01-01

    The analytical package written in FORM presented in this paper allows the computation of the complete set of Feynman Rules producing the Rational terms of kind R 2 contributing to the virtual part of NLO corrections in the Standard Model of the Electroweak interactions. Building block topologies filled by means of generic scalars, vectors and fermions, allowing to build these Feynman Rules in terms of specific elementary particles, are explicitly given in the R ξ gauge class, together with the automatic dressing procedure to obtain the Feynman Rules from them. The results in more specific gauges, like the 't Hooft Feynman one, follow as particular cases, in both the HV and the FDH dimensional regularization schemes. As a check on our formulas, the gauge independence of the total Rational contribution (R 1 +R 2 ) to renormalized S-matrix elements is verified by considering the specific example of the H →γγ decay process at 1-loop. This package can be of interest for people aiming at a better understanding of the nature of the Rational terms. It is organized in a modular way, allowing a further use of some its files even in different contexts. Furthermore, it can be considered as a first seed in the effort towards a complete automation of the process of the analytical calculation of the R 2 effective vertices, given the Lagrangian of a generic gauge theory of particle interactions. (orig.)

  6. The serendipity of electroweak baryogenesis

    Science.gov (United States)

    Servant, Géraldine

    2018-01-01

    The origin of the matter-antimatter asymmetry of the universe remains unexplained in the Standard Model (SM) of particle physics. The origin of the flavour structure is another major puzzle of the theory. In this article, we report on recent work attempting to link the two themes through the appealing framework of electroweak (EW) baryogenesis. We show that Yukawa couplings of SM fermions can be the source of CP violation for EW baryogenesis if they vary at the same time as the Higgs is acquiring its vacuum expectation value, offering new avenues for EW baryogenesis. The advantage of this approach is that it circumvents the usual severe bounds from electric dipole moments. These ideas apply if the mechanism explaining the flavour structure of the SM is connected to EW symmetry breaking, as motivated for instance in Randall-Sundrum or Composite Higgs models. We compute the resulting baryon asymmetry for different configurations of the Yukawa coupling variation across the bubble wall and show that it can naturally be of the right order. This article is part of the Theo Murphy meeting issue `Higgs cosmology'.

  7. The serendipity of electroweak baryogenesis.

    Science.gov (United States)

    Servant, Géraldine

    2018-03-06

    The origin of the matter-antimatter asymmetry of the universe remains unexplained in the Standard Model (SM) of particle physics. The origin of the flavour structure is another major puzzle of the theory. In this article, we report on recent work attempting to link the two themes through the appealing framework of electroweak (EW) baryogenesis. We show that Yukawa couplings of SM fermions can be the source of CP violation for EW baryogenesis if they vary at the same time as the Higgs is acquiring its vacuum expectation value, offering new avenues for EW baryogenesis. The advantage of this approach is that it circumvents the usual severe bounds from electric dipole moments. These ideas apply if the mechanism explaining the flavour structure of the SM is connected to EW symmetry breaking, as motivated for instance in Randall-Sundrum or Composite Higgs models. We compute the resulting baryon asymmetry for different configurations of the Yukawa coupling variation across the bubble wall and show that it can naturally be of the right order.This article is part of the Theo Murphy meeting issue 'Higgs cosmology'. © 2018 The Author(s).

  8. Constraints on the minimal N=1 supergravity theory from electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Giudice, G.F.; Ridolfi, G.

    1988-01-01

    We reanalyze the constraints on the minimal N=1 supergravity extension of the standard model arising from the requirement of a correct spontaneous breakdown of the electroweak symmetry. Driven by recent experimental results, we devote special attention to the case of a top quark much heavier than the conventional choice of 40 GeV, used in previous analyses. Our results are stated in a space of phenomenologically meaningful parameters, providing a direct comparison between the constraints from SU(2) x U(1) breaking and the predictions for supersymmetric particle production. Moreover, an upper bound for the ratio of the two Higgs vacuum expectation values is given, for any value of the top quark mass. (orig.)

  9. Precision electroweak physics at the Tevatron

    International Nuclear Information System (INIS)

    James, Eric B.

    2006-01-01

    An overview of Tevatron electroweak measurements performed by the CDF and Dφ experiments is presented. The current status and future prospects for high precision measurements of electroweak parameters and detailed studies of boson production are highlighted. (author)

  10. Supersymmetric electro-weak effects on gsub(μ)-2

    International Nuclear Information System (INIS)

    Yuan, T.C.; Arnowitt, R.; Chamseddine, A.H.; Nath, P.

    1984-01-01

    A model independent analysis of the supersymmetric electroweak contribution to gsub(μ)-2 is discussed within the framework of N=1 Supergravity unified theory. A detailed comparison with existing experiment of two models (R.G. and T.B.) is carried out. The supersymmetric electro-weak contributions are found to be characteristically different and generally larger than the electro-weak contributions of the standard theory, and in many cases significantly larger. Effects of the hidden sector and the photino mass dependence of gsub(μ)-2 are also investigated. Present data already eliminates some choices of parameters. Reduction of existing experimental errors by a factor of 3 will make contact with most R.G. models and by a factor of 10 with most T.B. models. (orig.)

  11. Electroweak Symmetry Breaking (3/3)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    The focus of the lectures will be on the role of the Higgs boson in the mechanism of electroweak symmetry breaking, both in the Standard Model and in models of New Physics. In particular, I will discuss how a determination of its couplings to matter and gauge fields can give important information on the nature and origin of the Higgs boson. I will thus review the picture on Higgs couplings implied by the current experimental data and examine further interesting processes that can be measured in the future.

  12. Electroweak Symmetry Breaking (2/3)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    The focus of the lectures will be on the role of the Higgs boson in the mechanism of electroweak symmetry breaking, both in the Standard Model and in models of New Physics. In particular, I will discuss how a determination of its couplings to matter and gauge fields can give important information on the nature and origin of the Higgs boson. I will thus review the picture on Higgs couplings implied by the current experimental data and examine further interesting processes that can be measured in the future.

  13. Electroweak Symmetry Breaking (1/3)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    The focus of the lectures will be on the role of the Higgs boson in the mechanism of electroweak symmetry breaking, both in the Standard Model and in models of New Physics. In particular, I will discuss how a determination of its couplings to matter and gauge fields can give important information on the nature and origin of the Higgs boson. I will thus review the picture on Higgs couplings implied by the current experimental data and examine further interesting processes that can be measured in the future.

  14. Vector coherent state representations of SO5 contains SU2 + SU2 contains U1 + U1 and SO5 contains U1 + U1

    International Nuclear Information System (INIS)

    Pan Feng

    1991-01-01

    VCS representations of SO 5 contains SU 2 + SU 2 contains U 1 + U 1 and SO 5 contains U 1 + U 1 are discussed. Reduced matrix elements for SO 5 contains SU 2 + SU 2 are derived. The multiplicity of a weight for SO 5 is determined by using the K-matrix technique

  15. Electroweak results from hadron colliders

    International Nuclear Information System (INIS)

    Demarteau, Marcel

    1997-01-01

    A review of recent electroweak results from hadron colliders is given. Properties of the W ± and Z 0 gauge bosons using final states containing electrons and muons based on large integrated luminosities are presented. The emphasis is placed on the measurement of the mass of the W boson and the measurement of trilinear gauge boson couplings

  16. Electroweak physics from D0

    International Nuclear Information System (INIS)

    Roe, N.A.

    1993-05-01

    The D0 detector was recently commissioned at the Tevatron p bar p collider and is presently taking data. Preliminary results from D0 are presented on properties of the W and Z electroweak gauge bosons, using final states containing electrons and muons

  17. Constraining Lorentz Violation in Electroweak Physics

    Science.gov (United States)

    Lehnert, Ralf

    2018-01-01

    For practical reasons, the majority of past Lorentz tests has involved stable or quasistable particles, such as photons, neutrinos, electrons, protons, and neutrons. Similar efforts in the electroweak sector have only recently taken shape. Within this context, Lorentz-violation searches in the Standard-Model Extension’s Z-Boson sector will be discussed. It is argued that existing precision data on polarized electron-electron scattering can be employed to extract the first conservative two-sided limits on Lorentz breakdown in this sector at the level of 10-7.

  18. On neutrino and charged lepton masses and mixings: a view from the electroweak-scale right-handed neutrino model

    Energy Technology Data Exchange (ETDEWEB)

    Hung, P.Q.; Le, Trinh [Department of Physics, University of Virginia,Charlottesville, VA 22904-4714 (United States)

    2015-09-01

    We present a model of neutrino masses within the framework of the EW-ν{sub R} model in which the experimentally desired form of the PMNS matrix is obtained by applying an A{sub 4} symmetry to the Higgs singlet sector responsible for the neutrino Dirac mass matrix. This mechanism naturally avoids potential conflict with the LHC data which severely constrains the Higgs sector, in particular the Higgs doublets. Moreover, by making a simple ansa{sup ¨}tz we extract M{sub l}M{sub l}{sup †} for the charged lepton sector. A similar ansa{sup ¨}tz is proposed for the quark sector. The sources of masses for the neutrinos are entirely different from those for the charged leptons and for the quarks and this might explain why U{sub PMNS} is very different from V{sub CKM}.

  19. Supersymmetric contribution to the electroweak ρ parameter

    International Nuclear Information System (INIS)

    Drees, M.; Hagiwara, K.

    1990-01-01

    Contributions to the electroweak ρ parameter, the ratio of the neutral- and charged-current strengths at zero-momentum transfer, are studied in the minimal extension of the standard model (SM) with softly broken supersymmetry. The effects of the extended Higgs sector, the gaugino-Higgsino sector, the light-squark--slepton sector and that of the stop-sbottom sector are studied separately, and the role of the custodial SU(2) V symmetry in each sector is clarified. The stop-sbottom sector is found to give potentially a most significant contribution to δρ which can double the standard-model contribution from the top-bottom sector, whereas all the remaining sectors contribute to δρ at the level of at most a few x10 -3 . In the supergravity model with radiative electroweak gauge symmetry breaking there are no extra sources of the SU(2) V breaking at the grand unification scale other than those present already in the SM, and the resulting δρ is found to be significantly smaller than in the general case. Constraints on the allowed range of δρ in the supergravity models are given by taking account of existing and prospective experimental mass limits of additional particles at CERN LEP and Sp bar pS and Fermilab Tevatron

  20. Electroweak symmetry breaking: Higgs/whatever

    International Nuclear Information System (INIS)

    Chanowitz, M.S.

    1990-01-01

    In these two lectures the author discusses electroweak symmetry breaking from a general perspective, stressing properties that are model independent and follow just from the assumption that the electroweak interactions are described by a spontaneously broken gauge theory. This means he assumes the Higgs mechanism though not necessarily the existence of Higgs bosons. The first lecture presents the general framework of a spontaneously broken gauge theory: (1) the Higgs mechanism sui generis, with or without Higgs boson(s) and (2) the implications of symmetry and unitarity for the mass scale and interaction strength of the new physics that the Higgs mechanism requires. In addition he reviews a softer theoretical argument based on the naturalness problem which leads to a prejudice against Higgs bosons unless they are supersymmetric. This is a prejudice, not a theorem, and it could be overturned in the future by a clever new idea. In the second lecture he illustrates the general framework by reviewing some specific models: (1) the Weinberg-Salam model of the Higgs sector; (2) the minimal supersymmetric extension of the Weinberg-Salam model; and (3) technicolor as an example of the Higgs mechanism without Higgs bosons. He concludes the second lecture with a discussion of strong WW scattering that must occur if L SB lives above 1 TeV. In particular he describes some of the experimental signals and backgrounds at the SSC. 57 refs., 12 figs

  1. Combined QCD and electroweak analysis of HERA data

    Energy Technology Data Exchange (ETDEWEB)

    Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max-Planck-Institute for Physics, Munich (Germany); Abt, I. [Max-Planck-Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science; Collaboration: ZEUS Collaboration; and others

    2016-03-15

    A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarisation of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.

  2. Studying the Electroweak Sector with the ATLAS Detector

    CERN Document Server

    Bittrich, Carsten; The ATLAS collaboration

    2018-01-01

    The large integrated luminosities that are available at the LHC, allow to test the gauge structure of the electroweak sector of the Standard Model to highest precision. In this talk, we review the latest results of the ATLAS collaboration involving di-boson and multiboson final states as well as the corresponding limits on anomalous gauge couplings. Moreover, we discuss the electroweak production of vector boson at 13 TeV. Another approach to test the consistency of the electroweak sector is via precision measurements. ATLAS has recently published a measurement of the tau-polarization in Z events as well as a three dimensional cross-section measurement of the Drell-Yan process. The latter allows for the extraction of the forward-backward asymmetry that can be interpreted as a measurement of the weak mixing angle. Both results will be presented and discussed.

  3. Combined QCD and electroweak analysis of HERA data

    International Nuclear Information System (INIS)

    Abramowicz, H.; Abt, I.; Adamczyk, L.

    2016-03-01

    A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarisation of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.

  4. Combined QCD and electroweak analysis of HERA data

    CERN Document Server

    Abramowicz, H; Adamczyk, L; Adamus, M; Antonelli, S; Aushev, V; Behnke, O; Behrens, U; Bertolin, A; Bloch, I; Boos, EG; Brock, I; Brook, NH; Brugnera, R; Bruni, A; Bussey, PJ; Caldwell, A; Capua, M; Catterall, CD; Chwastowski, J; Ciborowski, J; Ciesielski, R; Cooper-Sarkar, AM; Corradi, M; Dementiev, RK; Devenish, RCE; Dusini, S; Foster, B; Gach, G; Gallo, E; Garfagnini, A; Geiser, A; Gizhko, A; Gladilin, LK; Golubkov, Yu A; Grzelak, G; Guzik, M; Hain, W; Hochman, D; Hori, R; Ibrahim, ZA; Iga, Y; Ishitsuka, M; Januschek, F; Jomhari, NZ; Kadenko, I; Kananov, S; Karshon, U; Kaur, P; Kisielewska, D; Klanner, R; Klein, U; Korzhavina, IA; Kotański, A; Kötz, U; Kovalchuk, N; Kowalski, H; Krupa, B; Kuprash, O; Kuze, M; Levchenko, BB; Levy, A; Limentani, S; Lisovyi, M; Lobodzinska, E; Löhr, B; Lohrmann, E; Longhin, A; Lontkovskyi, D; Lukina, OYu; Makarenko, I; Malka, J; Mohamad Idris, F; Mohammad Nasir, N; Myronenko, V; Nagano, K; Nobe, T; Nowak, RJ; Onishchuk, Yu; Paul, E; Perlański, W; Pokrovskiy, NS; Przybycien, M; Roloff, P; Ruspa, M; Saxon, DH; Schioppa, M; Schneekloth, U; Schörner-Sadenius, T; Shcheglova, LM; Shevchenko, R; Shkola, O; Shyrma, Yu; Singh, I; Skillicorn, IO; Słomiński, W; Solano, A; Stanco, L; Stefaniuk, N; Stern, A; Stopa, P; Sztuk-Dambietz, J; Tassi, E; Tokushuku, K; Tomaszewska, J; Tsurugai, T; Turcato, M; Turkot, O; Tymieniecka, T; Verbytskyi, A; Wan Abdullah, WAT; Wichmann, K; Wing, M; Yamada, S; Yamazaki, Y; Zakharchuk, N; Żarnecki, AF; Zawiejski, L; Zenaiev, O; Zhautykov, BO; Zotkin, DS; Bhadra, S; Gwenlan, C; Hlushchenko, O; Polini, A; Mastroberardino, A

    2016-05-03

    A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarisation of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.

  5. Testing the electroweak model using semileptonic decays of b quarks in the L3 detector at LEP

    International Nuclear Information System (INIS)

    Hebert, M.

    1992-01-01

    The partial decay width Γ bbar b for Z 0 → b bar b, the forward-backward asymmetry A bbar b , and the B 0 -bar B 0 mixing parameter χ B are determined using a sample of 430K hadronic Z 0 decay events collected by the L3 detector at LEP during 1990 and 1991. The partial width Γ cbar c and asymmetry A cbar c for charm are also determined. Heavy quarks are tagged via their semileptonic decays into high momentum and high p perpendicular muons or electrons. The decay lepton's charge is used to determine the charge of the parent quark. An unbinned, maximum-likelihood fit to the two-dimensional p and p perpendicular distributions in single-lepton events and the four-dimensional p and p perpendicular distributions for dilepton events yields the values Γ bbar b = 382 ± 3 (stat) ± (sys) GeV; Γ cbar c = 293 ± 10 (stat) ± 98 (sys) GeV A bbar b = 0.090 ± 0.015 (stat) ± 0.007 (sys); A cbar c = 0.083 ± 0.038 (stat) ± 0.027 (sys) and χ B = 0.124 ± 0.017 (stat) ± 0.010 (sys). All of these values are seen to be consistent with Standard Model expectations

  6. Towards a nonequilibrium quantum field theory approach to electroweak baryogenesis

    International Nuclear Information System (INIS)

    Riotto, A.

    1996-01-01

    We propose a general method to compute CP violating observables from extensions of the standard model in the context of electroweak baryogenesis. It is an alternative to the one recently developed by Huet and Nelson and relies on a nonequilibrium quantum field theory approach. The method is valid for all shapes and sizes of the bubble wall expanding in the thermal bath during a first-order electroweak phase transition. The quantum physics of CP violation and its suppression coming from the incoherent nature of thermal processes are also made explicit. copyright 1996 The American Physical Society

  7. On stability of the electroweak vacuum and the Higgs portal

    International Nuclear Information System (INIS)

    Lebedev, Oleg

    2012-03-01

    In the Standard Model (SM), the Higgs mass around 125 GeV implies that the electroweak vacuum is metastable since the quartic Higgs coupling turns negative at high energies. I point out that an arbitrarily small mixing of the Higgs with a heavy singlet can make the electroweak vacuum completely stable. This is due to a tree level correction to the Higgs mass, which survives in the zero--mixing/heavy--singlet limit. Such a situation is experimentally indistinguishable from the SM, unless the Higgs self--coupling can be measured. As a result, Higgs inflation and its variants can still be viable.

  8. Production of electroweak bosons at hadron colliders: theoretical aspects

    CERN Document Server

    Mangano, Michelangelo L.

    2016-01-01

    Since the W and Z discovery, hadron colliders have provided a fertile ground, in which continuously improving measurements and theoretical predictions allow to precisely determine the gauge boson properties, and to probe the dynamics of electroweak and strong interactions. This article will review, from a theoretical perspective, the role played by the study, at hadron colliders, of electroweak boson production properties, from the better understanding of the proton structure, to the discovery and studies of the top quark and of the Higgs, to the searches for new phenomena beyond the Standard Model.

  9. On stability of the electroweak vacuum and the Higgs portal

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, Oleg

    2012-03-15

    In the Standard Model (SM), the Higgs mass around 125 GeV implies that the electroweak vacuum is metastable since the quartic Higgs coupling turns negative at high energies. I point out that an arbitrarily small mixing of the Higgs with a heavy singlet can make the electroweak vacuum completely stable. This is due to a tree level correction to the Higgs mass, which survives in the zero--mixing/heavy--singlet limit. Such a situation is experimentally indistinguishable from the SM, unless the Higgs self--coupling can be measured. As a result, Higgs inflation and its variants can still be viable.

  10. Towards Reviving Electroweak Baryogenesis with a Fourth Generation

    Directory of Open Access Journals (Sweden)

    Wei-Shu Hou

    2013-01-01

    universe. However, it does not work within the standard model due to two reasons: (1 the strength of CP violation from the Kobayashi-Maskawa mechanism with three generations is too small; (2 the electroweak phase transition is not first order for the experimentally allowed Higgs boson mass. We discuss possibilities to solve these problems by introducing a fourth generation of fermions and how electroweak baryogenesis might be revived. We also discuss briefly the recent observation of a Higgs-like boson with mass around 125 GeV, which puts the fourth generation in a difficult situation, and the possible way out.

  11. Phenomenology of induced electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Chang, Spencer; Galloway, Jamison; Luty, Markus A.; Salvioni, Ennio; Tsai, Yuhsin

    2015-01-01

    We study the phenomenology of models of electroweak symmetry breaking where the Higgs potential is destabilized by a tadpole arising from the coupling to an “auxiliary” Higgs sector. The auxiliary Higgs sector can be either perturbative or strongly coupled, similar to technicolor models. Since electroweak symmetry breaking is driven by a tadpole, the cubic and quartic Higgs couplings can naturally be significantly smaller than their values in the standard model. The theoretical motivation for these models is that they can explain the 125 GeV Higgs mass in supersymmetry without fine-tuning. The auxiliary Higgs sector contains additional Higgs states that cannot decouple from standard model particles, so these models predict a rich phenomenology of Higgs physics beyond the standard model. In this paper we analyze a large number of direct and indirect constraints on these models. We present the current constraints after the 8 TeV run of the LHC, and give projections for the sensitivity of the upcoming 14 TeV run. We find that the strongest constraints come from the direct searches A 0 →Zh, A 0 →tt-bar, with weaker constraints from Higgs coupling fits. For strongly-coupled models, additional constraints come from ρ + →WZ where ρ + is a vector resonance. Our overall conclusion is that a significant parameter space for such models is currently open, allowing values of the Higgs cubic coupling down to 0.4 times the standard model value for weakly coupled models and vanishing cubic coupling for strongly coupled models. The upcoming 14 TeV run of the LHC will stringently test this scenario and we identify several new searches with discovery potential for this class of models.

  12. SU(5) x U(1) phenomenology: Theorems on neutral-current analysis

    International Nuclear Information System (INIS)

    Zee, A.; Kim, J.E.

    1980-01-01

    We embed the SU(5) unified theory of Georgi and Glashow in a U(5) theory. This may result from the breaking of an SU(N), N>5, theory or of a GL(5,c) theory. At low energy this leads to an SU(2) x U(1) x U(1) electroweak theory. We show that, with a suitable choice of Higgs representations, the predictions of this theory for neutral-current experiments are characterized by three parameters. For appropriate values of these parameters, the predictions are practically indistinguishable from the standard SU(2) x U(1) theory. Certain theorems on the analysis of neutral-current interactions are proved. (Section V is independent for readers who are interested only in the theorems.) More accurate neutral-current measurement might answer the question of whether SU(5) x U(1) is relevant. Possible verification of the present electroweak theory can result from (roughly) an order suppression relative to the standard prediction on the asymmetries in e + e - → μ + μ - and discovery of two Z bosons around 90 --100 GeV. GL(n,c) gauge theories are formulated in the Appendix

  13. Enabling electroweak baryogenesis through dark matter

    International Nuclear Information System (INIS)

    Lewicki, Marek; Rindler-Daller, Tanja; Wells, James D.

    2016-01-01

    We study the impact on electroweak baryogenesis from a swifter cosmological expansion induced by dark matter. We detail the experimental bounds that one can place on models that realize it, and we investigate the modifications of these bounds that result from a non-standard cosmological history. The modifications can be sizeable if the expansion rate of the Universe increases by several orders of magnitude. We illustrate the impact through the example of scalar field dark matter, which can alter the cosmological history enough to enable a strong-enough first-order phase transition in the Standard Model when it is supplemented by a dimension six operator directly modifying the Higgs boson potential. We show that due to the modified cosmological history, electroweak baryogenesis can be realized, while keeping deviations of the triple Higgs coupling below HL-LHC sensitivies. The required scale of new physics to effectuate a strong-enough first order phase transition can change by as much as twenty percent as the expansion rate increases by six orders of magnitude.

  14. Electroweak Baryogenesis in R-symmetric Supersymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Fok, R.; Kribs, Graham D.; Martin, Adam; Tsai, Yuhsin

    2013-03-01

    We demonstrate that electroweak baryogenesis can occur in a supersymmetric model with an exact R-symmetry. The minimal R-symmetric supersymmetric model contains chiral superfields in the adjoint representation, giving Dirac gaugino masses, and an additional set of "R-partner" Higgs superfields, giving R-symmetric \\mu-terms. New superpotential couplings between the adjoints and the Higgs fields can simultaneously increase the strength of the electroweak phase transition and provide additional tree-level contributions to the lightest Higgs mass. Notably, no light stop is present in this framework, and in fact, we require both stops to be above a few TeV to provide sufficient radiative corrections to the lightest Higgs mass to bring it up to 125 GeV. Large CP-violating phases in the gaugino/higgsino sector allow us to match the baryon asymmetry of the Universe with no constraints from electric dipole moments due to R-symmetry. We briefly discuss some of the more interesting phenomenology, particularly of the of the lightest CP-odd scalar.

  15. Fit to Electroweak Precision Data

    International Nuclear Information System (INIS)

    Erler, Jens

    2006-01-01

    A brief review of electroweak precision data from LEP, SLC, the Tevatron, and low energies is presented. The global fit to all data including the most recent results on the masses of the top quark and the W boson reinforces the preference for a relatively light Higgs boson. I will also give an outlook on future developments at the Tevatron Run II, CEBAF, the LHC, and the ILC

  16. Precision measurements of electroweak parameters

    CERN Document Server

    Savin, Alexander

    2017-01-01

    A set of selected precise measurements of the SM parameters from the LHC experiments is discussed. Results on W-mass measurement and forward-backward asymmetry in production of the Drell--Yan events in both dielectron and dimuon decay channels are presented together with results on the effective mixing angle measurements. Electroweak production of the vector bosons in association with two jets is discussed.

  17. LHCb: Electroweak studies at LHCb

    CERN Multimedia

    Salustino Guimaraes, V

    2012-01-01

    Results on the measurement of the $W^{\\pm}$ and $Z^{0}$ cross-sections are presented using final state leptons with pseudorapidities between 2 and 4.5. Due to its acceptance, LHCb can probe a regime of low low-x electroweak boson production, where parton distribution functions are not well constrained. We summarize the $W^{\\pm}$ measurements performed in the decay $\\mu^{\\pm}\

  18. Quantum chromodynamics effects in electroweak and Higgs physics

    Indian Academy of Sciences (India)

    Several examples of the often intricate effects of higher-order quantum chromodynamics (QCD) corrections on predictions for hadron-collider observables, are discussed, using the production of electroweak gauge boson and the Standard Model Higgs boson as examples. Particular attention is given to the interplay of QCD ...

  19. Measurement of Electroweak Top Quark Production at {D\\O}

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Yun-Tse [Univ. of Rochester, NY (United States)

    2013-01-01

    We present a new model-independent measurement of the electroweak single top-quark production cross section in proton-antiproton (p- $\\bar{p}$) collisions at √s = 1.96 TeV in 9.7 fb-1 of integrated luminosity collected with the DØ detector.

  20. Global U(1 ) Y⊗BRST symmetry and the LSS theorem: Ward-Takahashi identities governing Green's functions, on-shell T -matrix elements, and the effective potential in the scalar sector of the spontaneously broken extended Abelian Higgs model

    Science.gov (United States)

    Lynn, Bryan W.; Starkman, Glenn D.

    2017-09-01

    The weak-scale U (1 )Y Abelian Higgs model (AHM) is the simplest spontaneous symmetry breaking (SSB) gauge theory: a scalar ϕ =1/√{2 }(H +i π )≡1/√{2 }H ˜ei π ˜/⟨H ⟩ and a vector Aμ. The extended AHM (E-AHM) adds certain heavy (MΦ2,Mψ2˜MHeavy2≫⟨H ⟩2˜mWeak2 ) spin S =0 scalars Φ and S =1/2 fermions ψ . In Lorenz gauge, ∂μAμ=0 , the SSB AHM (and E-AHM) has a global U (1 )Y conserved physical current, but no conserved charge. As shown by T. W. B. Kibble, the Goldstone theorem applies, so π ˜ is a massless derivatively coupled Nambu-Goldstone boson (NGB). Proof of all-loop-orders renormalizability and unitarity for the SSB case is tricky because the Becchi-Rouet-Stora-Tyutin (BRST)-invariant Lagrangian is not U (1 )Y symmetric. Nevertheless, Slavnov-Taylor identities guarantee that on-shell T-matrix elements of physical states Aμ,ϕ , Φ , ψ (but not ghosts ω , η ¯ ) are independent of anomaly-free local U (1 )Y gauge transformations. We observe here that they are therefore also independent of the usual anomaly-free U (1 )Y global/rigid transformations. It follows that the associated global current, which is classically conserved only up to gauge-fixing terms, is exactly conserved for amplitudes of physical states in the AHM and E-AHM. We identify corresponding "undeformed" [i.e. with full global U (1 )Y symmetry] Ward-Takahashi identities (WTI). The proof of renormalizability and unitarity, which relies on BRST invariance, is undisturbed. In Lorenz gauge, two towers of "1-soft-pion" SSB global WTI govern the ϕ -sector, and represent a new global U (1 )Y⊗BRST symmetry not of the Lagrangian but of the physics. The first gives relations among off-shell Green's functions, yielding powerful constraints on the all-loop-orders ϕ -sector SSB E-AHM low-energy effective Lagrangian and an additional global shift symmetry for the NGB: π ˜→π ˜+⟨H ⟩θ . A second tower, governing on-shell T-matrix elements, replaces the old Adler

  1. Tests of the electroweak theory at LEP

    International Nuclear Information System (INIS)

    Schaile, D.

    1994-01-01

    LEP offers a rich choice of tests of the electroweak theory such as the measurement of hadronic and leptonic cross sections, leptonic forward-backward asymmetries, τ polarization asymmetries, partial widths and forward-backward asymmetries of heavy quark flavours, of the inclusive q anti q charge asymmetry and of final state radiation in hadronic events. We discuss experimental aspects of these measurements and their theoretical parametrization and summarize the results available so far. We present several analyses which reveal specific aspects of the results, such as their constraints on Standard Model parameters and on new particles, the sensitivity to deviations from the Standard Model multiplet structure and an analysis in a framework which provides a model independent search for new physics. (orig.)

  2. Strong electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Panico, G.

    2014-01-01

    In the view of the recent LHC discovery of an Higgs-like scalar particle, I review the phenomenological aspects of the Composite Higgs scenarios which can be used to probe this class of models, namely the distortion of the Higgs couplings and the presence of new resonances. (author)

  3. Natural cold baryogenesis from strongly interacting electroweak symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Konstandin, Thomas; Servant, Géraldine, E-mail: tkonstan@cern.ch, E-mail: geraldine.servant@cern.ch [CERN Physics Department, Theory Division, CH-1211 Geneva 23 (Switzerland)

    2011-07-01

    The mechanism of ''cold electroweak baryogenesis'' has been so far unpopular because its proposal has relied on the ad-hoc assumption of a period of hybrid inflation at the electroweak scale with the Higgs acting as the waterfall field. We argue here that cold baryogenesis can be naturally realized without the need to introduce any slow-roll potential. Our point is that composite Higgs models where electroweak symmetry breaking arises via a strongly first-order phase transition provide a well-motivated framework for cold baryogenesis. In this case, reheating proceeds by bubble collisions and we argue that this can induce changes in Chern-Simons number, which in the presence of new sources of CP violation commonly lead to baryogenesis. We illustrate this mechanism using as a source of CP violation an effective dimension-six operator which is free from EDM constraints, another advantage of cold baryogenesis compared to the standard theory of electroweak baryogenesis. Our results are general as they do not rely on any particular UV completion but only on a stage of supercooling ended by a first-order phase transition in the evolution of the universe, which can be natural if there is nearly conformal dynamics at the TeV scale. Besides, baryon-number violation originates from the Standard Model only.

  4. Natural cold baryogenesis from strongly interacting electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Konstandin, Thomas; Servant, Géraldine

    2011-01-01

    The mechanism of ''cold electroweak baryogenesis'' has been so far unpopular because its proposal has relied on the ad-hoc assumption of a period of hybrid inflation at the electroweak scale with the Higgs acting as the waterfall field. We argue here that cold baryogenesis can be naturally realized without the need to introduce any slow-roll potential. Our point is that composite Higgs models where electroweak symmetry breaking arises via a strongly first-order phase transition provide a well-motivated framework for cold baryogenesis. In this case, reheating proceeds by bubble collisions and we argue that this can induce changes in Chern-Simons number, which in the presence of new sources of CP violation commonly lead to baryogenesis. We illustrate this mechanism using as a source of CP violation an effective dimension-six operator which is free from EDM constraints, another advantage of cold baryogenesis compared to the standard theory of electroweak baryogenesis. Our results are general as they do not rely on any particular UV completion but only on a stage of supercooling ended by a first-order phase transition in the evolution of the universe, which can be natural if there is nearly conformal dynamics at the TeV scale. Besides, baryon-number violation originates from the Standard Model only

  5. Higgsless theory of electroweak symmetry breaking from warped space

    International Nuclear Information System (INIS)

    Nomura, Yasunori

    2003-01-01

    We study a theory of electroweak symmetry breaking without a Higgs boson, recently suggested by Csaki et al. The theory is formulated in 5D warped space with the gauge bosons and matter fields propagating in the bulk. In the 4D dual picture, the theory appears as the standard model without a Higgs field, but with an extra gauge group G which becomes strong at the TeV scale. The strong dynamics of G breaks the electroweak symmetry, giving the masses for the W and Z bosons and the quarks and leptons. We study corrections in 5D which are logarithmically enhanced by the large mass ratio between the Planck and weak scales, and show that they do not destroy the structure of the electroweak gauge sector at the leading order. We introduce a new parameter, the ratio between the two bulk gauge couplings, into the theory and find that it allows us to control the scale of new physics. We also present a potentially realistic theory accommodating quarks and leptons and discuss its implications, including the violation of universality in the W and Z boson couplings to matter and the spectrum of the Kaluza-Klein excitations of the gauge bosons. The theory reproduces many successful features of the standard model, although some cancellations may still be needed to satisfy constraints from the precision electroweak data. (author)

  6. Electroweak vacuum geometry

    International Nuclear Information System (INIS)

    Lepora, N.; Kibble, T.

    1999-01-01

    We analyse symmetry breaking in the Weinberg-Salam model paying particular attention to the underlying geometry of the theory. In this context we find two natural metrics upon the vacuum manifold: an isotropic metric associated with the scalar sector, and a squashed metric associated with the gauge sector. Physically, the interplay between these metrics gives rise to many of the non-perturbative features of Weinberg-Salam theory. (author)

  7. Supersymmetric U boson and the old U(1) problem

    International Nuclear Information System (INIS)

    Kim, B.R.

    1983-01-01

    In the supersymmetric SU(3)xSU(2)xU(1)xUsup(')(1) model the new gauge group Usup(')(1) enforces the introduction of mirror fermions. In this note we address the inverse question. If one starts with SU(3)xSU(2)xU(1) including mirror fermions, what physical arguments other than the supersymmetric require the introduction of a new gauge group Usup(')(1). It turns out that the old U(1) problem is closely related with this question. Further we give an estimate for the upper bound for the parameter of the supersymmetric U boson r and x. (orig.)

  8. Thermal equilibrium during the electroweak phase transition

    International Nuclear Information System (INIS)

    Tetradis, N.

    1991-12-01

    The effective potential for the standard model develops a barrier, at temperatures around the electroweak scale, which separates the minimum at zero field and a deeper non-zero minimum. This could create out of equilibrium conditions by inducing the localization of the Higgs field in a metastable state around zero. In this picture vacuum decay would occur through bubble nucleation. I show that there is an upper bound on the Higgs mass for the above scenario to be realized. The barrier must be high enough to prevent thermal fluctuations of the Higgs expectation value from establishing thermal equilibrium between the two minima. The upper bound is estimated to be lower than the experimental lower limit. This is also imposes constraints on extensions of the standard model constructed in order to generate a strongly first order phase transition. (orig.)

  9. Electroweak baryogenesis, large Yukawas and dark matter

    International Nuclear Information System (INIS)

    Provenza, Alessio; Quiros, Mariano; Ullio, Piero

    2005-01-01

    It has recently been shown that the electroweak baryogenesis mechanism is feasible in Standard Model extensions containing extra fermions with large Yukawa couplings. We show here that the lightest of these fermionic fields can naturally be a good candidate for cold dark matter. We find regions in the parameter space where the thermal relic abundance of this particle is compatible with the dark matter density of the Universe as determined by the WMAP experiment. We study direct and indirect dark matter detection for this model and compare with current experimental limits and prospects for upcoming experiments. We find, contrary to the standard lore, that indirect detection searches are more promising than direct ones, and they already exclude part of the parameter space

  10. Electroweak interactions in a relativistic Fermi gas

    International Nuclear Information System (INIS)

    Vantournhout, K.; Jachowicz, N.; Ryckebusch, J.

    2006-01-01

    We present a relativistic model for computing the neutrino mean free path in neutron matter. In this model, neutron matter is described as a noninteracting Fermi gas in β equilibrium. We present results for the neutrino mean free path for temperatures of 0 to 50 MeV and a broad range of neutrino energies. We show that relativistic effects cause a considerable enhancement of neutrino-scattering cross sections in neutron matter. The influence of the Q 2 dependence in the electroweak form factors and the inclusion of a weak-magnetic term in the hadron current is discussed. The weak-magnetic term in the hadron current is at the origin of some selective spin dependence for the nucleons that are subject to neutrino interactions

  11. Electroweak symmetry breaking: Higgs/whatever

    International Nuclear Information System (INIS)

    Chanowitz, M.S.

    1989-01-01

    In the first of these two lectures the Higgs mechanism is reviewed in its most general form, which does not necessarily require the existence of Higgs bosons. The general consequences of the hypothesis that electroweak symmetry breaking is due to the Higgs mechanism are deduced just from gauge invariance and unitarity. In the second lecture the general properties are illustrated with three specific models: the Weinberg-Salam model, its minimal supersymmetric extension, and technicolor. The second lecture concludes with a discussion of the experiment signals for strong WW scattering, whose presence or absence will allow us to determine whether the symmetry breaking sector lies above or below 1 TeV. 57 refs

  12. Superconductivity in dense electroweak system

    International Nuclear Information System (INIS)

    Ferrer, E.J.; De La Incera, V.; Shabad, A.E.

    1988-01-01

    The spectrum of fermions in the presence of the W-boson-condensed electro-weak liquid is obtained and nonvanishing spatial component of the fermionic polarization operator is calculated for zero 4-momentum. The manifestation of the Meissner effect is studied. The London penetration depthλ/sub L/ is calculated in the limit of small W-condensate amplitude. The possibility of a special phenomenon of partial magnetic screening due to the mixing angle dependence on the leptonic density is discussed in connection with the magnetic mass problem

  13. History of electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Kibble, T W B

    2015-01-01

    In this talk, I recall the history of the development of the unified electroweak theory, incorporating the symmetry-breaking Higgs mechanism, as I saw it from my standpoint as a member of Abdus Salam's group at Imperial College. I start by describing the state of physics in the years after the Second World War, explain how the goal of a unified gauge theory of weak and electromagnetic interactions emerged, the obstacles encountered, in particular the Goldstone theorem, and how they were overcome, followed by a brief account of more recent history, culminating in the historic discovery of the Higgs boson in 2012. (paper)

  14. Numerical tests of the electroweak phase transition and thermodynamics of the electroweak plasma

    CERN Document Server

    Csikor, Ferenc; Hein, J; Jaster, A; Montvay, István

    1996-01-01

    The finite temperature phase transition in the SU(2) Higgs model at a Higgs boson mass M_H \\simeq 34 GeV is studied in numerical simulations on four-dimensional lattices with time-like extensions up to L_t=5. The effects of the finite volume and finite lattice spacing on masses and couplings are studied in detail. The errors due to uncertainties in the critical hopping parameter are estimated. The thermodynamics of the electroweak plasma near the phase transition is investigated by determining the relation between energy density and pressure.

  15. Natural Cold Baryogenesis from Strongly Interacting Electroweak Symmetry Breaking

    CERN Document Server

    Konstandin, Thomas

    2011-01-01

    The mechanism of "cold electroweak baryogenesis" has been so far unpopular because its proposal has relied on the ad-hoc assumption of a period of hybrid inflation at the electroweak scale with the Higgs acting as the waterfall field. We argue here that cold baryogenesis can be naturally realized without the need to introduce any slow-roll potential. Our point is that composite Higgs models where electroweak symmetry breaking arises via a strongly first-order phase transition provide a well-motivated framework for cold baryogenesis. In this case, reheating proceeds by bubble collisions and we argue that this can induce changes in Chern-Simons number, which in the presence of new sources of CP violation commonly lead to baryogenesis. We illustrate this mechanism using as a source of CP violation an effective dimension-six operator which is free from EDM constraints, another advantage of cold baryogenesis compared to the standard theory of electroweak baryogenesis. Our results are general as they do not rely on...

  16. Precision electroweak heavy flavor results from LEP and SLC

    International Nuclear Information System (INIS)

    Brown, D.

    1993-11-01

    The traditional Electroweak measurements made at Z factories using undifferentiated hadronic and leptonic Z decays will soon be reaching their asymptotic limits in precision. Consequently, much attention has recently been focused on extracting electroweak parameters from hadronic decays differentiated through heavy flavor tagging. This paper gives an overview of the various techniques used at LEP and SLC to tag heavy flavors. The measurements of the forward backward asymmetries and the partial widths for Z→b anti b and Z→c anti c decays are briefly described. The most recent results for these are presented, and are interpreted within the framework of the Standard Model. The precision of the electroweak parameters extracted from these measurements is shown to be comparable to that from other techniques. Assembling all the LEP electroweak data, constraints on the top and Higgs masses are found. The heavy flavor results, and in particular the new, very accurate Z→b anti b partial width measurements, are shown to play a key role in these limits. (orig.)

  17. Dimensional reduction of the Standard Model coupled to a new singlet scalar field

    Energy Technology Data Exchange (ETDEWEB)

    Brauner, Tomáš [Faculty of Science and Technology, University of Stavanger,N-4036 Stavanger (Norway); Tenkanen, Tuomas V.I. [Department of Physics and Helsinki Institute of Physics,P.O. Box 64, FI-00014 University of Helsinki (Finland); Tranberg, Anders [Faculty of Science and Technology, University of Stavanger,N-4036 Stavanger (Norway); Vuorinen, Aleksi [Department of Physics and Helsinki Institute of Physics,P.O. Box 64, FI-00014 University of Helsinki (Finland); Weir, David J. [Faculty of Science and Technology, University of Stavanger,N-4036 Stavanger (Norway); Department of Physics and Helsinki Institute of Physics,P.O. Box 64, FI-00014 University of Helsinki (Finland)

    2017-03-01

    We derive an effective dimensionally reduced theory for the Standard Model augmented by a real singlet scalar. We treat the singlet as a superheavy field and integrate it out, leaving an effective theory involving only the Higgs and SU(2){sub L}×U(1){sub Y} gauge fields, identical to the one studied previously for the Standard Model. This opens up the possibility of efficiently computing the order and strength of the electroweak phase transition, numerically and nonperturbatively, in this extension of the Standard Model. Understanding the phase diagram is crucial for models of electroweak baryogenesis and for studying the production of gravitational waves at thermal phase transitions.

  18. QCD-Electroweak First-Order Phase Transition in a Supercooled Universe

    Science.gov (United States)

    Iso, Satoshi; Serpico, Pasquale D.; Shimada, Kengo

    2017-10-01

    If the electroweak sector of the standard model is described by classically conformal dynamics, the early Universe evolution can be substantially altered. It is already known that—contrarily to the standard model case—a first-order electroweak phase transition may occur. Here we show that, depending on the model parameters, a dramatically different scenario may happen: A first-order, six massless quark QCD phase transition occurs first, which then triggers the electroweak symmetry breaking. We derive the necessary conditions for this dynamics to occur, using the specific example of the classically conformal B -L model. In particular, relatively light weakly coupled particles are predicted, with implications for collider searches. This scenario is also potentially rich in cosmological consequences, such as renewed possibilities for electroweak baryogenesis, altered dark matter production, and gravitational wave production, as we briefly comment upon.

  19. QCD-Electroweak First-Order Phase Transition in a Supercooled Universe.

    Science.gov (United States)

    Iso, Satoshi; Serpico, Pasquale D; Shimada, Kengo

    2017-10-06

    If the electroweak sector of the standard model is described by classically conformal dynamics, the early Universe evolution can be substantially altered. It is already known that-contrarily to the standard model case-a first-order electroweak phase transition may occur. Here we show that, depending on the model parameters, a dramatically different scenario may happen: A first-order, six massless quark QCD phase transition occurs first, which then triggers the electroweak symmetry breaking. We derive the necessary conditions for this dynamics to occur, using the specific example of the classically conformal B-L model. In particular, relatively light weakly coupled particles are predicted, with implications for collider searches. This scenario is also potentially rich in cosmological consequences, such as renewed possibilities for electroweak baryogenesis, altered dark matter production, and gravitational wave production, as we briefly comment upon.

  20. Precision experiments in electroweak interactions

    International Nuclear Information System (INIS)

    Swartz, M.L.

    1990-03-01

    The electroweak theory of Glashow, Weinberg, and Salam (GWS) has become one of the twin pillars upon which our understanding of all particle physics phenomena rests. It is a brilliant achievement that qualitatively and quantitatively describes all of the vast quantity of experimental data that have been accumulated over some forty years. Note that the word quantitatively must be qualified. The low energy limiting cases of the GWS theory, Quantum Electrodynamics and the V-A Theory of Weak Interactions, have withstood rigorous testing. The high energy synthesis of these ideas, the GWS theory, has not yet been subjected to comparably precise scrutiny. The recent operation of a new generation of proton-antiproton (p bar p) and electron-positron (e + e - ) colliders has made it possible to produce and study large samples of the electroweak gauge bosons W ± and Z 0 . We expect that these facilities will enable very precise tests of the GWS theory to be performed in the near future. In keeping with the theme of this Institute, Physics at the 100 GeV Mass Scale, these lectures will explore the current status and the near-future prospects of these experiments

  1. Electroweak scale physics & exotic searches at LHCb

    CERN Document Server

    Lupton, Olli

    2018-01-01

    The LHCb detector is a single-arm forward spectrometer covering the pseudorapidity range 2–5 that is principally designed for the study of b- and c-hadrons, but which is well-suited to a wide variety of electroweak scale measurements and exotic searches that are highly complementary to other experiments at the LHC and elsewhere. Several features of the detector that are crucial for the core flavour physics programme, such as excellent vertex and momentum resolution, and a powerful trigger system, contribute to excellent jet tagging performance and sensitivity to low mass exotic states. LHCb operates at a substantially lower instantaneous luminosity than the general purpose detectors at the LHC, ATLAS and CMS, which results in a clean, low pile-up environment in which to search for physics beyond the Standard Model (SM).

  2. Metastable electroweak vacuum. Implications for inflation

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, Oleg; Westphal, Alexander [DESY Theory Group, Hamburg (Germany)

    2012-10-15

    Within the Standard Model, the current Higgs and top quark data favor metastability of the electroweak vacuum, although the uncertainties are still significant. The true vacuum is many orders of magnitude deeper than ours and the barrier separating the two is tiny compared to the depth of the well. This raises a cosmological question: how did the Higgs field get trapped in the shallow minimum and why did it stay there during inflation? The Higgs initial conditions before inflation must be fine-tuned to about one part in 10{sup 8} in order for the Higgs field to end up in the right vacuum. In this note, we show that these problems can be resolved if there is a small positive coupling between the Higgs and the inflaton.

  3. Electroweak Precision Measurements with the ATLAS Detector

    CERN Document Server

    Zhang, Zhiqing; The ATLAS collaboration

    2018-01-01

    With the high integrated luminosities recorded at the LHC and the very good understanding of the ATLAS detector, it is possible to measure electroweak observables to the highest precision. In this talk, we review the measurement of the W boson mass using data, collected at 7 TeV. Special focus is drawn on a discussion of the modeling uncertainties and the physics potential of the latest low-mu runs, recorded at a center of mass energy of 5 and 13 TeV at the end of 2017. The talk will also review the measurement of the triple differential Drell-Yan cross-section at 8 TeV, which can be used to extract the weak mixing angle. We conclude with a presentation of the tau polarization, measured in Z->tautau using 20.3/fb of proton proton collision data collected at a center of mass energy of 8 TeV.

  4. Metastable electroweak vacuum. Implications for inflation

    International Nuclear Information System (INIS)

    Lebedev, Oleg; Westphal, Alexander

    2012-10-01

    Within the Standard Model, the current Higgs and top quark data favor metastability of the electroweak vacuum, although the uncertainties are still significant. The true vacuum is many orders of magnitude deeper than ours and the barrier separating the two is tiny compared to the depth of the well. This raises a cosmological question: how did the Higgs field get trapped in the shallow minimum and why did it stay there during inflation? The Higgs initial conditions before inflation must be fine-tuned to about one part in 10 8 in order for the Higgs field to end up in the right vacuum. In this note, we show that these problems can be resolved if there is a small positive coupling between the Higgs and the inflaton.

  5. Metastable cosmic strings in realistic models

    International Nuclear Information System (INIS)

    Holman, R.

    1992-01-01

    The stability of the electroweak Z-string is investigated at high temperatures. The results show that, while finite temperature corrections can improve the stability of the Z-string, their effect is not strong enough to stabilize the Z-string in the standard electroweak model. Consequently, the Z-string will be unstable even under the conditions present during the electroweak phase transition. Phenomenologically viable models based on the gauge group SU(2) L x SU(2) R x U(1) B-L are then considered, and it is shown that metastable strings exist and are stable to small perturbations for a large region of the parameter space for these models. It is also shown that these strings are superconducting with bosonic charge carriers. The string superconductivity may be able to stabilize segments and loops against dynamical contraction. Possible implications of these strings for cosmology are discussed

  6. Electroweak symmetry breaking from a holographic fourth generation

    International Nuclear Information System (INIS)

    Burdman, Gustavo; Rold, Leandro Da

    2007-01-01

    We consider a model with four generations of standard model fermions propagating in an extra dimension with an AdS background metric. We show that if the zero modes of the fourth generation are highly localized towards the infrared brane, it is possible to break the electroweak symmetry via their condensation, partly driven by their interactions with the Kaluza-Klein excitations of the gauge bosons, as well as by the presence of bulk higher-dimensional operators. This dynamical mechanism results in a composite Higgs, which is highly localized and generally heavy. The localization of fermions in the five-dimensional bulk naturally leads to the standard model Yukawa couplings via the action of the bulk higher-dimensional operators, which are suppressed by the Planck scale. We obtain the spectrum of the model and explore some of its phenomenological consequences, both for electroweak precision constraints as well as at the Large Hadron Collider

  7. On the Possible Links Between Electroweak Symmetry Breaking and Dark Matter

    International Nuclear Information System (INIS)

    Hambye, Thomas; Tytgat, Michel H. G.

    2009-01-01

    The mechanism behind electroweak symmetry breaking (EWSB) and the nature of dark matter (DM) are currently very important issues in particle physics. Usually, in most models, these two issues are not or poorly connected. However, since a natural dark matter candidate is a weakly interacting massive particle or WIMP, with mass around the electroweak scale, it is clearly of interest to investigate the possibility that DM and EWSB are closely related. In the context of a very simple extension of the Standard Model, the Inert Doublet Model, we show that dark matter could play a crucial role in the breaking of the electroweak symmetry. In this model, dark matter is the lightest component of an inert scalar doublet which can induce dynamically electroweak symmetry breaking at one loop level. Moreover, in a large fraction of the parameter space of this model, the mass of the dark matter particle is essentially determined by the electroweak scale, so that the fact that the WIMP DM mass is around the electroweak scale is not a coincidence.

  8. On the nature of the electroweak phase sition and its cosmological consequences

    International Nuclear Information System (INIS)

    Servant, Geraldine

    2011-01-01

    Full text: The Large Hadron Collider will take experiments into a new energy domain beyond the standard model of strong and electroweak interactions. As the LHC will unveil the mysteries of the electroweak symmetry breaking, this will also have far-reaching implications for cosmology. This concerns in particular the fundamental question of the matter-antimatter asymmetry of the Universe. One of the best-motivated mechanism for generating the baryon asymmetry of the universe relies on a first-order electroweak phase transition. I will present some well-motivated extensions of the standard model that naturally lead to a first-order phase transition. Interestingly, this has strong implications for gravity wave physics. I will discuss how a gravity wave detector and space interferometer such as Lisa, which would turn out to be a completely independent window on the electroweak scale, could complement the information provided by the LHC. (author)

  9. Searches for electroweak production of supersymmetric gauginos and sleptons with the ATLAS detector

    CERN Document Server

    Carra, Sonia; The ATLAS collaboration

    2018-01-01

    Supersymmetry is one of the most motivated Standard Model extensions. Despite the meticulous search during the LHC Run I, there is no evidence supporting this theory. Starting from 2015, LHC is performing a second data taking run with a higher center of mass energy (13 TeV), providing a great occasion for the search of beyond the Standard Model physics. An important sector is the direct production of supersymmetric electroweak particles, such as sleptons and charginos. Electroweak production cross section is lower compared to strong production, but searches performed by the ATLAS and CMS experiments during LHC Run 2 excluded squark and gluinos with masses up to 2 TeV, making electroweak production an increasingly promising probe for SUSY signals at the LHC. Results obtained with the 2015-2016 ATLAS detector data will be presented. Direct production of electroweak particles like sleptons, charginos and neutralinos, with different signatures, will be considered. A good sensitivity is obtained in the signal regi...

  10. A strong electroweak phase transition from the inflaton field

    Energy Technology Data Exchange (ETDEWEB)

    Tenkanen, Tommi; Tuominen, Kimmo [Department of Physics, University of Helsinki, P.O. Box 64, FI-00014, Helsinki (Finland); Helsinki Institute of Physics, P.O. Box 64, FI-00014, Helsinki (Finland); Vaskonen, Ville [Helsinki Institute of Physics, P.O. Box 64, FI-00014, Helsinki (Finland); Department of Physics, University of Jyvaskyla, P.O.Box 35 (YFL), FI-40014 University of Jyvaskyla (Finland)

    2016-09-22

    We study a singlet scalar extension of the Standard Model. The singlet scalar is coupled non-minimally to gravity and assumed to drive inflation, and also couple sufficiently strongly with the SM Higgs field in order to provide for a strong first order electroweak phase transition. Requiring the model to describe inflation successfully, be compatible with the LHC data, and yield a strong first order electroweak phase transition, we identify the regions of the parameter space where the model is viable. We also include a singlet fermion with scalar coupling to the singlet scalar to probe the sensitivity of the constraints on additional degrees of freedom and their couplings in the singlet sector. We also comment on the general feasibility of these fields to act as dark matter.

  11. Singlet Higgs phenomenology and the electroweak phase transition

    International Nuclear Information System (INIS)

    Profumo, Stefano; Ramsey-Musolf, Michael J.; Shaughnessy, Gabe

    2007-01-01

    We study the phenomenology of gauge singlet extensions of the Standard Model scalar sector and their implications for the electroweak phase transition. We determine the conditions on the scalar potential parameters that lead to a strong first order phase transition as needed to produce the observed baryon asymmetry of the universe. We analyze the constraints on the potential parameters derived from Higgs boson searches at LEP and electroweak precision observables. For models that satisfy these constraints and that produce a strong first order phase transition, we discuss the prospective signatures in future Higgs studies at the Large Hadron Collider and a Linear Collider. We argue that such studies will provide powerful probes of phase transition dynamics in models with an extended scalar sector

  12. Tests of electroweak interactions at CERN's LEP Collider

    Science.gov (United States)

    Fearnley, T. A.

    1995-08-01

    Precision measurements of electroweak interactions at the Z0 energy are performed at four experiments at the Large Electron Positron (LEP) Collider at CERN in Geneva, Switzerland. The large amount of data obtained from 1989 until today allows detailed comparisons with the predictions made by the Standard Model. Within the experimental errors the agreement with the Standard Model is good. Fits to the LEP data allow an indirect determination of the mass of the top quark: Mt=173+12+18-13-20 GeV, assuming a Higgs boson mass of 300 GeV. The first errors reflect the experimental errors (systematic and statistical) on the measurements. The second errors correspond to the variation of the central value when varying the Higgs mass between 60 and 1000 GeV. This paper reviews the results of the measurements of electroweak interactions, and compares the results with predictions made by the Standard Model.

  13. Top down electroweak dipole operators

    Science.gov (United States)

    Fuyuto, Kaori; Ramsey-Musolf, Michael

    2018-06-01

    We derive present constraints on, and prospective sensitivity to, the electric dipole moment (EDM) of the top quark (dt) implied by searches for the EDMs of the electron and nucleons. Above the electroweak scale v, the dt arises from two gauge invariant operators generated at a scale Λ ≫ v that also mix with the light fermion EDMs under renormalization group evolution at two-loop order. Bounds on the EDMs of first generation fermion systems thus imply bounds on |dt |. Working in the leading log-squared approximation, we find that the present upper bound on |dt | is 10-19 e cm for Λ = 1 TeV, except in regions of finely tuned cancellations that allow for |dt | to be up to fifty times larger. Future de and dn probes may yield an order of magnitude increase in dt sensitivity, while inclusion of a prospective proton EDM search may lead to an additional increase in reach.

  14. Seesaw induced electroweak scale, the hierarchy problem and sub-eV neutrino masses

    International Nuclear Information System (INIS)

    Atwood, D.; Bar-Shalom, S.; Soni, A.

    2006-01-01

    We describe a model for the scalar sector where all interactions occur either at an ultra-high scale, Λ U ∝10 16 -10 19 GeV, or at an intermediate scale, Λ I =10 9 -10 11 GeV. The interaction of physics on these two scales results in an SU(2) Higgs condensate at the electroweak (EW) scale, Λ EW , through a seesaw-like Higgs mechanism, Λ EW ∝Λ I 2 /Λ U , while the breaking of the SM SU(2) x U(1) gauge symmetry occurs at the intermediate scale Λ I . The EW scale is, therefore, not fundamental but is naturally generated in terms of ultra-high energy phenomena and so the hierarchy problem is alleviated. We show that the class of such ''seesaw Higgs'' models predict the existence of sub-eV neutrino masses which are generated through a ''two-step'' seesaw mechanism in terms of the same two ultra-high scales: m ν ∝Λ I 4 /Λ U 3 ∝Λ EW 2 /Λ U . The neutrinos can be either Dirac or Majorana, depending on the structure of the scalar potential. We also show that our seesaw Higgs model can be naturally embedded in theories with tiny extra dimensions of size R∝Λ U -1 ∝10 -16 fm, where the seesaw induced EW scale arises from a violation of a symmetry at a distant brane; in particular, in the scenario presented there are seven tiny extra dimensions. (orig.)

  15. The Price of an Electroweak Monopole

    CERN Document Server

    Ellis, John; You, Tevong

    2016-01-01

    In a recent paper, Cho, Kim and Yoon (CKY) have proposed a version of the SU(2) $\\times$ U(1) Standard Model with finite-energy monopole and dyon solutions. The CKY model postulates that the effective U(1) gauge coupling $\\to \\infty$ very rapidly as the Englert-Brout-Higgs vacuum expectation value $\\to 0$, but in a way that is incompatible with LHC measurements of the Higgs boson $H \\to \\gamma \\gamma$ decay rate. We construct generalizations of the CKY model that are compatible with the $H \\to \\gamma \\gamma$ constraint, and calculate the corresponding values of the monopole and dyon masses. We find that the monopole mass could be $< 5.5$ TeV, so that it could be pair-produced at the LHC and accessible to the MoEDAL experiment.

  16. Investigation of the Spin and Recovery Characteristics of a 0.057-Scale Model of the Modified Chance Vought XF7U-1 Airplane. TED No. NACA DE 311

    Science.gov (United States)

    Berman, Theodore; Pumphrey, Norman E.

    1950-01-01

    An investigation has been conducted in the Langley 20-foot free-spinning tunnel to determine the spin and recovery characteristics of a 0.057-scale model of the modified Chance Vought XF7U-1 airplane. The primary change in the design from that previously tested was a revision of the twin vertical tails. Tests were also made to determine the effect of installation of external wing tanks. The results indicated that the revision in the vertical tails did not greatly alter the spin and recovery characteristics of the model and recovery by normal use of controls (fill rapid rudder reversal followed approximately one-half turn later by movement of the stick forward of neutral) was satisfactory. Adding the external wing tanks to cause the recovery characteristics to become critical and border on an unsatisfactory condition; however, it was shown that satisfactory recovery could be obtained by jettisoning the tanks, followed by normal recovery technique.

  17. Implications of the discovery of a Higgs triplet on electroweak right-handed neutrinos

    International Nuclear Information System (INIS)

    Aranda, Alfredo; Hernandez-Sanchez, J.; Hung, P.Q.

    2008-01-01

    Electroweak scale active right-handed neutrinos such as those proposed in a recent model necessitate the enlargement of the SM Higgs sector to include Higgs triplets with doubly charged scalars. The search for and constraints on such Higgs sector has implications not only on the nature of the electroweak symmetry breaking but also on the possibility of testing the seesaw mechanism at colliders such as the LHC and the ILC.

  18. The role of electroweak penguin and magnetic dipole QCD penguin on hadronic b Quark Decays

    Directory of Open Access Journals (Sweden)

    H Mehrban

    2010-03-01

    Full Text Available This research, works with the effective Hamiltonian and the quark model. Using, the decay rates of matter-antimatter of b quark was investigated. We described the effective Hamiltonian theory which was applied to the calculation of current-current (Q1,2, QCD penguin (Q3,…,6, magnetic dipole (Q8 and electroweak penguin (Q7,…,10 decay rates. The gluonic penguin structure of hadronic decays b→qkg→qkqiqj was studied through the Wilson coefficients of the effective Hamiltonian. The branching ratios of the Tree-Level, effective Hamiltonian, effective Hamiltonian including electroweak penguin, effective Hamiltonian including magnetic dipole and the effective Hamiltonian including electroweak penguin and magnetic dipole b quark decays b→qiqkqj, qi{u,c}, qk{d,s}, qj{u,c} have been calculated. It was shown that, the electroweak penguin and magnetic dipole contributions in b quark decays are small and current-current operators are dominated.

  19. Searches for electroweak production of higgsinos with ATLAS

    CERN Document Server

    El Kosseifi, Rima; The ATLAS collaboration

    2018-01-01

    Searches for light higgsinos are motivated by "natural" SUSY models. Three new ATLAS electroweak higgsinos searches results, with 36.1 fb-1 pp collision data at √s= 13 TeV are presented in this talk. Both, the interpretations in SUSY scenarios assuming GMSB (with Gravitino the LSP) and the "Compressed SUSY" searches( with Higgsino the LSP) are covered. No significant excess over expected SM background seen, exclusion limits surpassing the LEP limits are set.

  20. Electroweak contributions to SUSY particle production processes at the LHC

    International Nuclear Information System (INIS)

    Mirabella, Edoardo

    2009-01-01

    In this thesis we have computed the electroweak contributions of O(α s α), O(α 2 ) and O(α s 2 ) to three different classes of processes leading to the hadronic production of the SUSY partners of quarks and gluons, i.e. squarks and gluinos. The theoretical framework is the Minimal Supersymmetric extension of the Standard Model, the MSSM. The three processes are gluino pair production, diagonal squark-antisquark and associated squark-gluino production.

  1. New strong interactions above the electroweak scale

    International Nuclear Information System (INIS)

    White, A.R.

    1994-01-01

    Theoretical arguments for a new higher-color quark sector, based on Pomeron physics in QCD, are briefly described. The electroweak symmetry-breaking, Strong CP conservation, and electroweak scale CP violation, that is naturally produced by this sector is also outlined. A further consequence is that above the electroweak scale there will be a radical change in the strong interaction. Electroweak states, in particular multiple W's and Z's, and new, semi-stable, very massive, baryons, will be commonly produced. The possible correlation of expected phenomena with a wide range of observed Cosmic Ray effects at and above the primary spectrum knee is described. Related phenomena that might be seen in the highest energy hard scattering events at the Fermilab Tevatron, some of which could be confused with top production, are also briefly discussed

  2. Fractional winding numbers and the U(1) problem

    International Nuclear Information System (INIS)

    Rothe, K.D.; Swieca, J.A.; Pontificia Univ. Catolica do Rio de Janeiro

    1980-06-01

    The effective Lagrangian description of gauge theories with spontaneous mass generation is simulated by considering the chiral Gross-Neveu model embedded in a two-dimensional U(1) gauge theory. It is shown that in this hybrid model the non-vanishing expectation value of psi psi is due to the contribution of instanton configurations with fractional winding. (Author) [pt

  3. An electroweak enigma: Hyperon radiative decays

    Energy Technology Data Exchange (ETDEWEB)

    Vorobyov, A., (spokesperson); /St. Petersburg, INP; Jastrzembski, E.; Lach, J.; Marriner, J.; /Fermilab; Golovtsov, V.; Krivshich, A.; Schegelsky, V.; Smirnov, N.; Terentiev, N.K.; Uvarov, L.; /St. Petersburg, INP; McCliment, E.; Newsom, C.; Norbeck, E.; /Iowa U.; Cooper, P.S.; /Yale U.

    1985-04-03

    The main thrust of this experiment will be to measure the asymmetry parameter for the electroweak decay {Sigma}{sup +} {yields} p{gamma} and verify its branching ratio. As a secondary goal they will measure, or set new upper limits for, the branching ratio of the electroweak decay {Xi}{sup -} {yields} {Sigma}{sup -}{gamma}. Since the {Xi}{sup -} are expected to be polarized, information on the asymmetry parameter may also be available.

  4. Electroweak boson production with jets at CMS

    CERN Document Server

    Hortiangtham, Apichart

    2017-01-01

    The production of electroweak bosons (W, Z or gamma) in association with jets is a stringent test of perturbative QCD and is a background process in searches for new physics. Total and differential cross-section measurements of electroweak bosons produced in association with jets (and heavy flavour quarks) in proton-proton collisions are presented. The data have been recorded with the CMS detector at the LHC and are compared to the predictions of event generators and theoretical calculations.

  5. Electroweak measurements with the ATLAS detector

    CERN Document Server

    Krasnopevtsev, Dimitriy; The ATLAS collaboration

    2015-01-01

    Electroweak measurements with the ATLAS detector -First Run 2 measurements of electroweak processes -Run 1 measurements of SM parameters, i.e. W mass and weak mixing angle -Recent Run 1 measurements of di- and multi-boson production cross-sections as well as vector boson fusion and scattering processes at 8 TeV -Recent Run 1 measurements of exclusive di-lepton and WW production

  6. Two Higgs doublets in SO(10) model

    International Nuclear Information System (INIS)

    Asatryan, G.M.

    1989-01-01

    An SO(10) grand unification model is suggested with two light Higgs doublets, whose vacuum expectation values are connected with the SU(2) L xU(1) Y electroweak group breaking. Taking into account the naturality condition associated with absence of flavor changing neutral currents, a certain form of the quark mass matrices. As a result, the proton lifetime in the SO(10) model turns to be strongly restrained

  7. Toward verification of electroweak baryogenesis by electric dipole moments

    International Nuclear Information System (INIS)

    Fuyuto, Kaori; Hisano, Junji; Senaha, Eibun

    2016-01-01

    We study general aspects of the CP-violating effects on the baryon asymmetry of the Universe (BAU) and electric dipole moments (EDMs) in models extended by an extra Higgs doublet and a singlet, together with electroweak-interacting fermions. In particular, the emphasis is on the structure of the CP-violating interactions and dependences of the BAU and EDMs on masses of the relevant particles. In a concrete mode, we investigate a relationship between the BAU and the electron EDM for a typical parameter set. As long as the BAU-related CP violation predominantly exists, the electron EDM has a strong power in probing electroweak baryogenesis. However, once a BAU-unrelated CP violation comes into play, the direct correlation between the BAU and electron EDM can be lost. Even in such a case, we point out that verifiability of the scenario still remains with the help of Higgs physics.

  8. Electroweak Phase Transition and Baryogenesis in the nMSSM

    CERN Document Server

    Huber, S J; Prokopec, T; Schmidt, M G; Huber, Stephan J.; Konstandin, Thomas; Prokopec, Tomislav; Schmidt, Michael G.

    2006-01-01

    We analyze the nMSSM with CP violation in the singlet sector. We study the static and dynamical properties of the electroweak phase transition. We conclude that electroweak baryogenesis in this model is generic in the sense that if the present limits on the mass spectrum are applied, no severe additional tuning is required to obtain a strong first-order phase transition and to generate a sufficient baryon asymmetry. For this we determine the shape of the nucleating bubbles, including the profiles of CP-violating phases. The baryon asymmetry is calculated using the advanced transport theory to first and second order in gradient expansion presented recently. Still, first and second generation sfermions must be heavy to avoid large electric dipole moments.

  9. Top and Higgs masses from dynamical electroweak symmetry breaking

    International Nuclear Information System (INIS)

    Kahana, D.E.

    1993-01-01

    The standard model of electroweak interactions, with the gauge and Higgs bosons appearing as composites, is derived from a Nambu-Jona-Lasinio-type four-fermion interaction, assumed to be valid above a high scale μ. Simple relationships are found for the composite boson top quark mass ratios and for the weak angle. Assuming three generations and a 'desert' hypothesis, these relationships are evolved with the full renormalization group down to present experimental energies, yielding predictions for the top quark and Higgs-boson masses, near 155 GeV for the former and near 140 GeV for the latter. In this fashion, fermion-antifermion condensates can be shown to yield a top mass consistent with that indicated from electroweak loop corrections for LEP data. (author) 23 refs

  10. Toward verification of electroweak baryogenesis by electric dipole moments

    Energy Technology Data Exchange (ETDEWEB)

    Fuyuto, Kaori, E-mail: fuyuto@th.phys.nagoya-u.ac.jp [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Hisano, Junji, E-mail: hisano@eken.phys.nagoya-u.ac.jp [Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University, Nagoya 464-8602 (Japan); Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Kavli IPMU (WPI), University of Tokyo, Kashiwa, Chiba 277-8584 (Japan); Senaha, Eibun, E-mail: senaha@ncu.edu.tw [Department of Physics and Center for Mathematics and Theoretical Physics, National Central University, Taoyuan, 32001, Taiwan (China)

    2016-04-10

    We study general aspects of the CP-violating effects on the baryon asymmetry of the Universe (BAU) and electric dipole moments (EDMs) in models extended by an extra Higgs doublet and a singlet, together with electroweak-interacting fermions. In particular, the emphasis is on the structure of the CP-violating interactions and dependences of the BAU and EDMs on masses of the relevant particles. In a concrete mode, we investigate a relationship between the BAU and the electron EDM for a typical parameter set. As long as the BAU-related CP violation predominantly exists, the electron EDM has a strong power in probing electroweak baryogenesis. However, once a BAU-unrelated CP violation comes into play, the direct correlation between the BAU and electron EDM can be lost. Even in such a case, we point out that verifiability of the scenario still remains with the help of Higgs physics.

  11. Gravitational waves from the electroweak phase transition

    International Nuclear Information System (INIS)

    Leitao, Leonardo; Mégevand, Ariel; Sánchez, Alejandro D.

    2012-01-01

    We study the generation of gravitational waves in the electroweak phase transition. We consider a few extensions of the Standard Model, namely, the addition of scalar singlets, the minimal supersymmetric extension, and the addition of TeV fermions. For each model we consider the complete dynamics of the phase transition. In particular, we estimate the friction force acting on bubble walls, and we take into account the fact that they can propagate either as detonations or as deflagrations preceded by shock fronts, or they can run away. We compute the peak frequency and peak intensity of the gravitational radiation generated by bubble collisions and turbulence. We discuss the detectability by proposed spaceborne detectors. For the models we considered, runaway walls require significant fine tuning of the parameters, and the gravitational wave signal from bubble collisions is generally much weaker than that from turbulence. Although the predicted signal is in most cases rather low for the sensitivity of LISA, models with strongly coupled extra scalars reach this sensitivity for frequencies f ∼ 10 −4 Hz, and give intensities as high as h 2 Ω GW ∼ 10 −8

  12. A few words about resonances in the electroweak effective Lagrangian

    Energy Technology Data Exchange (ETDEWEB)

    Rosell, Ignasi [Departamento de Ciencias Físicas, Matemáticas y de la Computación, Universidad CEU Cardenal Herrera, c/ Sant Bartomeu 55, 46115 Alfara del Patriarca, València (Spain); Pich, Antonio; Santos, Joaquín [Departament de Física Teòrica, IFIC, Universitat de València – CSIC, Apt. Correus 22085, 46071 València (Spain); Sanz-Cillero, Juan José [Departamento de Física Teórica and Instituto Física Teórica, IFT-UAM/CSIC, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2016-01-22

    Contrary to a widely spread believe, we have demonstrated that strongly coupled electroweak models including both a light Higgs-like boson and massive spin-1 resonances are not in conflict with experimental constraints on the oblique S and T parameters. We use an effective Lagrangian implementing the chiral symmetry breaking SU (2){sub L} ⊗ SU (2){sub R} → SU (2){sub L+R} that contains the Standard Model gauge bosons coupled to the electroweak Goldstones, one Higgs-like scalar state h with mass m{sub h} = 126 GeV and the lightest vector and axial-vector resonance multiplets V and A. We have considered the one-loop calculation of S and T in order to study the viability of these strongly-coupled scenarios, being short-distance constraints and dispersive relations the main ingredients of the calculation. Once we have constrained the resonance parameters, we do a first approach to the determination of the low energy constants of the electroweak effective theory at low energies (without resonances). We show this determination in the case of the purely Higgsless bosonic Lagrangian.

  13. BREM5 electroweak Monte Carlo

    International Nuclear Information System (INIS)

    Kennedy, D.C. II.

    1987-01-01

    This is an update on the progress of the BREMMUS Monte Carlo simulator, particularly in its current incarnation, BREM5. The present report is intended only as a follow-up to the Mark II/Granlibakken proceedings, and those proceedings should be consulted for a complete description of the capabilities and goals of the BREMMUS program. The new BREM5 program improves on the previous version of BREMMUS, BREM2, in a number of important ways. In BREM2, the internal loop (oblique) corrections were not treated in consistent fashion, a deficiency that led to renormalization scheme-dependence; i.e., physical results, such as cross sections, were dependent on the method used to eliminate infinities from the theory. Of course, this problem cannot be tolerated in a Monte Carlo designed for experimental use. BREM5 incorporates a new way of treating the oblique corrections, as explained in the Granlibakken proceedings, that guarantees renormalization scheme-independence and dramatically simplifies the organization and calculation of radiative corrections. This technique is to be presented in full detail in a forthcoming paper. BREM5 is, at this point, the only Monte Carlo to contain the entire set of one-loop corrections to electroweak four-fermion processes and renormalization scheme-independence. 3 figures

  14. Fermions on the electroweak string

    CERN Document Server

    Moreno, J M; Quirós, Mariano; Moreno, J M; Oaknin, D H; Quiros, M

    1995-01-01

    We construct a simple class of exact solutions of the electroweak theory including the naked Z--string and fermion fields. It consists in the Z--string configuration (\\phi,Z_\\theta), the {\\it time} and z components of the neutral gauge bosons (Z_{0,3},A_{0,3}) and a fermion condensate (lepton or quark) zero mode. The Z--string is not altered (no feed back from the rest of fields on the Z--string) while fermion condensates are zero modes of the Dirac equation in the presence of the Z--string background (no feed back from the {\\it time} and z components of the neutral gauge bosons on the fermion fields). For the case of the n--vortex Z--string the number of zero modes found for charged leptons and quarks is (according to previous results by Jackiw and Rossi) equal to |n|, while for (massless) neutrinos is |n|-1. The presence of fermion fields in its core make the obtained configuration a superconducting string, but their presence (as well as that of Z_{0,3},A_{0,3}) does not enhance the stability of the Z--stri...

  15. F-GUTs with Mordell-Weil U(1)'s

    CERN Document Server

    Antoniadis, I

    2014-01-01

    In this note we study the constraints on F-theory GUTs with extra $U(1)$'s in the context of elliptic fibrations with rational sections. We consider the simplest case of one abelian factor (Mordell-Weil rank one) and investigate the conditions that are induced on the coefficients of its Tate form. Converting the equation representing the generic hypersurface $P_{112}$ to this Tate's form we find that the presence of a U(1), already in this local description, is consistent with the exceptional ${\\cal E}_6$ and ${\\cal E}_7$ non-abelian singularities. We briefly comment on a viable ${\\cal E}_6\\times U(1)$ effective F-theory model.

  16. Interactions between $U(1)$ Cosmic Strings: An Analytical Study

    OpenAIRE

    Bettencourt, L. M. A.; Rivers, R. J.

    1994-01-01

    We derive analytic expressions for the interaction energy between two general $U(1)$ cosmic strings as the function of their relative orientation and the ratio of the coupling constants in the model. The results are relevant to the statistic description of strings away from critical coupling and shed some light on the mechanisms involved in string formation and the evolution of string networks.

  17. U(1) mediation of flux supersymmetry breaking

    Science.gov (United States)

    Grimm, Thomas W.; Klemm, Albrecht

    2008-10-01

    We study the mediation of supersymmetry breaking triggered by background fluxes in Type II string compactifications with Script N = 1 supersymmetry. The mediation arises due to an U(1) vector multiplet coupling to both a hidden supersymmetry breaking flux sector and a visible D-brane sector. The required internal manifolds can be constructed by non-Kähler resolutions of singular Calabi-Yau manifolds. The effective action encoding the U(1) coupling is then determined in terms of the global topological properties of the internal space. We investigate suitable local geometries for the hidden and visible sector in detail. This includes a systematic study of orientifold symmetries of del Pezzo surfaces realized in compact geometries after geometric transition. We construct compact examples admitting the key properties to realize flux supersymmetry breaking and U(1) mediation. Their toric realization allows us to analyze the geometry of curve classes and confirm the topological connection between the hidden and visible sector.

  18. U(1) mediation of flux supersymmetry breaking

    International Nuclear Information System (INIS)

    Grimm, Thomas W.; Klemm, Albrecht

    2008-01-01

    We study the mediation of supersymmetry breaking triggered by background fluxes in Type II string compactifications with N = 1 supersymmetry. The mediation arises due to an U(1) vector multiplet coupling to both a hidden supersymmetry breaking flux sector and a visible D-brane sector. The required internal manifolds can be constructed by non-Kaehler resolutions of singular Calabi-Yau manifolds. The effective action encoding the U(1) coupling is then determined in terms of the global topological properties of the internal space. We investigate suitable local geometries for the hidden and visible sector in detail. This includes a systematic study of orientifold symmetries of del Pezzo surfaces realized in compact geometries after geometric transition. We construct compact examples admitting the key properties to realize flux supersymmetry breaking and U(1) mediation. Their toric realization allows us to analyze the geometry of curve classes and confirm the topological connection between the hidden and visible sector.

  19. Studying the Electroweak Sector with the ATLAS Detector

    CERN Document Server

    Spalla, Margherita; The ATLAS collaboration

    2018-01-01

    (as received from the Speaker Committee. W mass removed from the presentation later on, as discussed in separate talk.) The large integrated luminosities that are available at the LHC, allow to test the gauge structure of the electroweak sector of the Standard Model to highest precision. In this talk, we review the latest results of the ATLAS collaboration involving di-boson and multiboson final states, the electroweak production of vector bosons as well as their constraints of effective field theory operators. Another approach to test the consistency of the electroweak sector is via precision measurements. ATLAS has published a first high precision measurement of the W boson mass, a first measurement of the tau-polarization in Z events as well as a three dimensional cross-section measurement of the Drell-Yan process. The latter allows for the extraction of the forward-backward asymmetry that can be interpreted as a measurement of the weak mixing angle. These results will be presented and discussed.

  20. Nonperturbative QCD corrections to electroweak observables

    Energy Technology Data Exchange (ETDEWEB)

    Dru B Renner, Xu Feng, Karl Jansen, Marcus Petschlies

    2011-12-01

    Nonperturbative QCD corrections are important to many low-energy electroweak observables, for example the muon magnetic moment. However, hadronic corrections also play a significant role at much higher energies due to their impact on the running of standard model parameters, such as the electromagnetic coupling. Currently, these hadronic contributions are accounted for by a combination of experimental measurements and phenomenological modeling but ideally should be calculated from first principles. Recent developments indicate that many of the most important hadronic corrections may be feasibly calculated using lattice QCD methods. To illustrate this, we will examine the lattice computation of the leading-order QCD corrections to the muon magnetic moment, paying particular attention to a recently developed method but also reviewing the results from other calculations. We will then continue with several examples that demonstrate the potential impact of the new approach: the leading-order corrections to the electron and tau magnetic moments, the running of the electromagnetic coupling, and a class of the next-to-leading-order corrections for the muon magnetic moment. Along the way, we will mention applications to the Adler function, the determination of the strong coupling constant and QCD corrections to muonic-hydrogen.

  1. Nonperturbative QCD corrections to electroweak observables

    Energy Technology Data Exchange (ETDEWEB)

    Renner, Dru B. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Feng, Xu [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Petschlies, Marcus [The Cyprus Institute, Nicosia (Cyprus)

    2012-06-15

    Nonperturbative QCD corrections are important to many low-energy electroweak observables, for example the muon magnetic moment. However, hadronic corrections also play a significant role at much higher energies due to their impact on the running of standard model parameters, such as the electromagnetic coupling. Currently, these hadronic contributions are accounted for by a combination of experimental measurements, effective field theory techniques and phenomenological modeling but ideally should be calculated from first principles. Recent developments indicate that many of the most important hadronic corrections may be feasibly calculated using lattice QCD methods. To illustrate this, we examine the lattice computation of the leading-order QCD corrections to the muon magnetic moment, paying particular attention to a recently developed method but also reviewing the results from other calculations. We then continue with several examples that demonstrate the potential impact of the new approach: the leading-order corrections to the electron and tau magnetic moments, the running of the electromagnetic coupling, and a class of the next-to-leading-order corrections for the muon magnetic moment. Along the way, we mention applications to the Adler function, which can be used to determine the strong coupling constant, and QCD corrections to muonic-hydrogen.

  2. Light sterile neutrinos, dark matter, and new resonances in a U(1) extension of the MSSM

    Science.gov (United States)

    Hebbar, A.; Lazarides, G.; Shafi, Q.

    2017-09-01

    We present ψ'MSSM, a model based on a U(1) ψ' extension of the minimal supersymmetric standard model. The gauge symmetry U(1)ψ', also known as U(1)N,is a linear combination of the U(1) χ and U(1)ψ subgroups of E6. The model predicts the existence of three sterile neutrinos with masses ≲0.1 eV , if the U(1)ψ' breaking scale is of order 10 TeV. Their contribution to the effective number of neutrinos at nucleosynthesis is Δ Nν≃0.29. The model can provide a variety of possible cold dark matter candidates including the lightest sterile sneutrino. If the U(1) ψ' breaking scale is increased to 1 03 TeV , the sterile neutrinos, which are stable on account of a Z2symmetry, become viable warm dark matter candidates. The observed value of the standard model Higgs boson mass can be obtained with relatively light stop quarks thanks to the D-term contribution from U(1)ψ'. The model predicts diquark and diphoton resonances which may be found at an updated LHC. The well-known μ problem is resolved and the observed baryon asymmetry of the universe can be generated via leptogenesis. The breaking of U(1)ψ' produces superconducting strings that may be present in our galaxy. A U(1) R symmetry plays a key role in keeping the proton stable and providing the light sterile neutrinos.

  3. Neutrino helicity flips via electroweak interactions

    International Nuclear Information System (INIS)

    Gaemers, K.J.F.; Gandhi, R.; Lattimer, J.M.; Department of Earth and Space Sciences, State University of New York, Stony Brook, New York 11794)

    1989-01-01

    Electroweak mechanisms via which neutrinos may flip helicity are examined in detail. Exact and approximate expressions for a variety of flip processes relevant in astrophysics and cosmology, mediated by W, Z, and γ exchange, including their interference, are derived for both Dirac and Majorana neutrinos (with emphasis on the former). It is shown that in general flip and nonflip cross sections differ by more than just a multiplicative factor of m/sub ν/ 2 /4E/sub ν/ 2 contrary to what might be expected and that this additional dependence on helicities can be significant. It is also shown that within the context of the standard model with massive neutrinos, for νe yields νe scattering, σ/sub Z//sup flip//σ/sub γ//sup flip/ ∼ 10 4 , independent of particle masses and energies to a good approximation. As an application, using some general considerations and the fact that the observed bar nu/sub e/ burst from SN 1987A lasted several seconds, these weak-interaction flip cross sections are used to rule out μ and tau neutrino masses above 30 keV. Finally, some other consequences for astrophysics in general and supernovae in particular are briefly discussed

  4. Electroweak vacuum stability in the Higgs-Dilaton theory

    Energy Technology Data Exchange (ETDEWEB)

    Shkerin, A. [Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL),CH-1015, Lausanne (Switzerland); Institute for Nuclear Research of the Russian Academy of Sciences,60th October Anniversary prospect 7a, 117312, Moscow (Russian Federation)

    2017-05-30

    We study the stability of the Electroweak (EW) vacuum in a scale-invariant extension of the Standard Model and General Relativity, known as a Higgs-Dilaton theory. The safety of the EW vacuum against possible transition towards another vacuum is a necessary condition for the model to be phenomenologically acceptable. We find that, within a wide range of parameters of the theory, the decay rate is significantly suppressed compared to that of the Standard Model. We also discuss properties of a tunneling solution that are specific to the Higgs-Dilaton theory.

  5. Deletion of SNURF/SNRPN U1B and U1B* upstream exons in a ...

    Indian Academy of Sciences (India)

    RESEARCH ARTICLE. Deletion of SNURF/SNRPN U1B and U1B* upstream exons in a child ... whereby genes are expressed in a parent-of-origin dependent manner. One of the ... lity, neurodevelopmental delay, features of attention deficit hyperactivity .... Received 16 December 2015; accepted 8 January 2016. Unedited ...

  6. Breaking of electroweak symmetry: origin and effects; Brisure de symetrie electrobaible: origine et consequence

    Energy Technology Data Exchange (ETDEWEB)

    Delaunay, C

    2008-10-15

    The Higgs boson appears as the corner stone of high energy physics, it might be the cause of the excess of matter that led to the formation of the structures of the universe and it seems that it drives the breaking of the electroweak symmetry. Moreover, when the stability at low energies of the Higgs boson is assured by an extra space dimension, it appears that this extra dimension can explain most issues in the flavor physics that are not understood by the standard model. The first chapter presents the main tools of effective field theories, the role of experimental data in the construction of theories valid beyond the standard model is discussed. The second chapter focuses on the electroweak baryogenesis that allows the testing of new physics via the electroweak phase transition. We detail the calculation of a Higgs potential at finite temperature. We follow the dynamics of the phase transition including nucleation an supercooling. Finally we investigate the prospects of gravity wave detection to see the effects of a strong electroweak phase transition. The 2 last chapters are dedicated to the physics of extra-dimension. The properties of the dynamics of scalar, vector fields with a 1/2 spin plunged in a 5 d. Anti de Sitter geometry are reviewed. We present a model of lepton masses and mixings based on the A{sub 4} non-Abelian discrete symmetry. It is shown that this model does not contradict the tests of electroweak precision. (A.C.)

  7. Workshop on electroweak symmetry breaking: proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Hinchliffe, I. (ed.)

    1984-10-01

    A theoretical workshop on electroweak symmetry breaking at the Superconducting Supercollider was held at Lawrence Berkeley Laboratory, June 4-22, 1984. The purpose of the workshop was to focus theoretical attention on the ways in which experimentation at the SSC could reveal manifestations of the phenomenon responsible for electroweak symmetry breaking. This issue represents, at present, the most compelling scientific argument for the need to explore the energy region to be made accessible by the SSC, and a major aim of the workshop was to involve a broad cross section of particle theorists in the ongoing process of sharpening the requirements for both accelerator and detector design that will ensure detection and identification of meaningful signals, whatever form the electroweak symmetry breaking phenomenon should actually take. Separate entries were prepared for the data base for the papers presented.

  8. Workshop on electroweak symmetry breaking: proceedings

    International Nuclear Information System (INIS)

    Hinchliffe, I.

    1984-10-01

    A theoretical workshop on electroweak symmetry breaking at the Superconducting Supercollider was held at Lawrence Berkeley Laboratory, June 4-22, 1984. The purpose of the workshop was to focus theoretical attention on the ways in which experimentation at the SSC could reveal manifestations of the phenomenon responsible for electroweak symmetry breaking. This issue represents, at present, the most compelling scientific argument for the need to explore the energy region to be made accessible by the SSC, and a major aim of the workshop was to involve a broad cross section of particle theorists in the ongoing process of sharpening the requirements for both accelerator and detector design that will ensure detection and identification of meaningful signals, whatever form the electroweak symmetry breaking phenomenon should actually take. Separate entries were prepared for the data base for the papers presented

  9. Recent results on Electroweak measurements from ATLAS

    Directory of Open Access Journals (Sweden)

    Benekos Nektarios Chr.

    2015-01-01

    Full Text Available ATLAS measurements of multiboson production processes involving combinations of W,Z and isolated photons are summarized. Measurements using data at 7 TeV and at 8 TeV are presented. The measurements are performed using leptonic decay modes, including the invisible decay Z → v v̅, as well as semileptonic channels. Measurements of single and diboson production in association with two forward jets is sensitive to electroweak vector boson fusion and scattering processes. An observation of the electroweak production of the Z boson and an evidence of same sign WW production are reported.

  10. Comments on the electroweak phase transition

    International Nuclear Information System (INIS)

    Dine, M.; Leigh, R.G.; Huet, P.; Linde, A.; Linde, D.

    1992-01-01

    We report on an investigation of various problems related to the theory of the electroweak phase transition. This includes a determination of the nature of the phase transition, a discussion of the possible role of higher order radiative corrections and the theory of the formation and evolution of the bubbles of the new phase. We find in particular that no dangerous linear terms appear in the effective potential. However, the strength of the first-order phase transition is 2/3 times less than what follows from the one-loop approximation. This rules out baryogenesis in the minimal version of the electroweak theory with light Higgs bosons. (orig.)

  11. Top and Electroweak Measurements at the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Bartos, P. [Comenius U.

    2016-01-01

    In this report, we summarize the latest results of the top-quark mass and electroweak measurements from the Tevatron. Since the world combination of top-quark mass measurements was done, CDF and D0 experiments improved the precision of several results. Some of them reach the relative precition below 1% for a single measurement. From the electroweak results, we report on the WW and WZ production cross section, measurements of the weak mixing angle and indirect measurements of W boson mass. The Tevatron results of the weak mixing angle are still the most precise ones of hadron colliders.

  12. Global S U (3 )C×S U (2 )L×U (1 )Y linear sigma model: Axial-vector Ward-Takahashi identities and decoupling of certain heavy BSM particles due to the Goldstone theorem

    Science.gov (United States)

    Lynn, Bryan W.; Starkman, Glenn D.

    2017-09-01

    In the S U (2 )L×S U (2 )R linear sigma model with partially conserved axial-vector currents, a tower of Ward-Takahashi identities (WTI) have long been known to give relations among 1-scalar-particle-irreducible (1 -ϕ -I ) Green's functions, and among I-scalar-particle-reducible (1 -ϕ -R ) transition-matrix (T-matrix) elements for external scalars [i.e. the Brout-Englert-Higgs (BEH) scalar H , and three pseudoscalars π →]. In this paper, we extend these WTI and the resulting relations to the S U (3 )C×S U (2 )L×U (1 )Y linear sigma model including the heaviest generation of Standard Model (SM) fermions—the ungauged (i.e. global) Standard Model SMtb τ ντ G —supplemented with the minimum necessary neutrino content—right-handed neutrinos and Yukawa-coupling-induced Dirac neutrino mass—to obtain the charge-parity (C P )-conserving νDSMtb τ ντ G , and extract powerful constraints on the effective Lagrangian: e.g. showing that they make separate tadpole renormalization unnecessary, and guarantee infrared finiteness. The crucial observation is that ultraviolet quadratic divergences (UVQD), and all other relevant operators, contribute only to mπ2, a pseudo-Nambu-Goldstone boson (NGB) mass-squared, which appears in intermediate steps of calculations. A WTI between T-matrix elements (or, in this global theory equivalently the Goldstone theorem) then enforces mπ2=0 exactly for the true NGB in the spontaneous symmetry breaking (SSB) mode of the theory. The Goldstone theorem thus causes all relevant operator contributions, originating to all-loop-orders from virtual scalars H ,π → , quarks qLc;tRc;bRc and leptons lL;ντR;τR with (c =r , w , b ), to vanish identically. We show that our regularization-scheme-independent, WTI-driven results are unchanged by the addition of certain S U (3 )C×S U (2 )L×U (1 )Y heavy (MHeavy2≫|q2|,mWeak2 ) C P -conserving matter, such as originate in certain beyond the SM (BSM) models. The global axial-vector WTI

  13. Conformal dynamics for electroweak symmetry breaking, from LHC to cosmology

    International Nuclear Information System (INIS)

    Sannino, Francesco

    2009-01-01

    Full text. I will first introduce dynamical electroweak symmetry breaking and then present how to resolve some of the long-standing problems using (near) conformal dynamics. In order to construct sensible extension of DEWSB I will then review the state-of-the-art of the phase diagram of gauge theories of fundamental interactions as function of the number of colors, flavors and matter representation. Finally I will introduce recent models known as minimal walking models and show how they lead to natural candidates of dark matter. (author)

  14. Minimal but non-minimal inflation and electroweak symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Marzola, Luca [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Institute of Physics, University of Tartu,Ravila 14c, 50411 Tartu (Estonia); Racioppi, Antonio [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia)

    2016-10-07

    We consider the most minimal scale invariant extension of the standard model that allows for successful radiative electroweak symmetry breaking and inflation. The framework involves an extra scalar singlet, that plays the rôle of the inflaton, and is compatibile with current experimental bounds owing to the non-minimal coupling of the latter to gravity. This inflationary scenario predicts a very low tensor-to-scalar ratio r≈10{sup −3}, typical of Higgs-inflation models, but in contrast yields a scalar spectral index n{sub s}≃0.97 which departs from the Starobinsky limit. We briefly discuss the collider phenomenology of the framework.

  15. Higgs mass implications on the stability of the electroweak vacuum: a NNLO analysis

    International Nuclear Information System (INIS)

    Elias-Miro, J.

    2014-01-01

    The mass range M n ≅ 124.5 - 126.5 GeV, of the discovered Higgs-like particle is a specially interesting range from the stability of the electroweak vacuum point of view. As we will show, for such mass range and assuming a Standard Model Higgs, the electroweak vacuum lies almost in between being absolutely stable up to the Planck scale and unstable, i.e. the Standard Mode effective potential presents a second minimum, deeper than the electroweak one, below the Planck scale. This observation motivates a higher order precision analysis of the Standard Model effective potential. We will review the first complete next-to-next-to-leading order analysis of the Standard Model Higgs potential made recently. Then, we will be able to conclude whether or not the SM can be consistently extrapolated up to the Planck scale. (author)

  16. More modular invariant anomalous U(1) breaking

    International Nuclear Information System (INIS)

    Gaillard, Mary K.; Giedt, Joel

    2002-01-01

    We consider the case of several scalar fields, charged under a number of U(1) factors, acquiring vacuum expectation values due to an anomalous U(1). We demonstrate how to make redefinitions at the superfield level in order to account for tree-level exchange of vector supermultiplets in the effective supergravity theory of the light fields in the supersymmetric vacuum phase. Our approach builds upon previous results that we obtained in a more elementary case. We find that the modular weights of light fields are typically shifted from their original values, allowing an interpretation in terms of the preservation of modular invariance in the effective theory. We address various subtleties in defining unitary gauge that are associated with the noncanonical Kaehler potential of modular invariant supergravity, the vacuum degeneracy, and the role of the dilaton field. We discuss the effective superpotential for the light fields and note how proton decay operators may be obtained when the heavy fields are integrated out of the theory at the tree-level. We also address how our formalism may be extended to describe the generalized Green-Schwarz mechanism for multiple anomalous U(1)'s that occur in four-dimensional Type I and Type IIB string constructions

  17. Electroweak properties of particle physics. Volume 2

    International Nuclear Information System (INIS)

    Aleksan, R.; Ellis, N.; Falvard, A.; Fayard, L.; Frere, J.M.; Kuehn, J.H.; Le Yaouanc, A.; Roudeau, P.; Wormser, G.

    1991-01-01

    The 23th GIf school was held at Ecole Polytechnique, Palaiseau, France from 16 to 20 September 1991. The subject was large: Electroweak properties of heavy quarks. The second part has been devoted to B physics at hadron machines, search for Top, Charm particle physics and Quarkonium physics

  18. Prospects on electroweak physics from the LHC

    International Nuclear Information System (INIS)

    Vikas, Pratibha

    2001-01-01

    The abundant production of gauge bosons, gauge boson pairs and top quarks at the LHC will offer the opportunity for comprehensive and challenging tests of theoretical predictions in the electroweak sector. Some issues which influence these measurements followed by prospects on some possible measurements by the ATLAS and CMS experiments at the Large Hadron Collider (LHC), at CERN are discussed. (author)

  19. Electroweak Physics in the Forward Region

    CERN Multimedia

    Sirendi, Marek

    2015-01-01

    LHCb has an active electroweak physics programme with measurements of inclusive processes such as Z and W production in leptonic final states already published. The EW working group is also branching into jet physics with completed Z+jet and Z+b-jet analyses. Recent results in this field are presented.

  20. SU(4) x U(1) gauge theory. II. CP nonconservation

    International Nuclear Information System (INIS)

    Deshpande, N.G.; Hwa, R.C.; Mannheim, P.D.

    1979-01-01

    We exploit the higher symmetry inherent in an SU(4) x U(1) gauge theory to construct a spontaneously broken theory of CP nonconservation. Higgs multiplets in the adjoint representation of SU(4) contain both even and odd CP fields; thus, requiring the simultaneous nonvanishing of the vacuum expectation values of these fields leads to CP noninvariance of the vacuum. We find that all the CP-nonconserving effects are mediated in our theory by the superheavy gauge bosons of the broken SU(4) x U(1) symmetry. In fact, the very existence of CP violation sets an upper limit on the masses of these bosons. In our model the dominant CP effect lies in the neutral kaon system and is found to arise through a direct (ΔS = 2) K 1 -K 2 transition. The model has all the features of a superweak theory, with a neutron electric dipole moment substantially smaller than 10 -24 e cm

  1. The Higgs vacuum uplifted. Revisiting the electroweak phase transition with a second Higgs doublet

    Energy Technology Data Exchange (ETDEWEB)

    Dorsch, G.C. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Huber, S.J. [Sussex Univ., Brighton (United Kingdom). Dept. of Physics and Astronomy; Mimasu, K. [Sussex Univ., Brighton (United Kingdom). Dept. of Physics and Astronomy; Louvain Univ. Catholique, Louvain-la-Neuve (Belgium). Center for Cosmology, Particle Physics and Phenomenology; No, J.M. [King' s College, London (United Kingdom). Dept. of Physics; Sussex Univ., Brighton (United Kingdom). Dept. of Physics and Astronomy

    2017-05-25

    The existence of a second Higgs doublet in Nature could lead to a cosmological first order electroweak phase transition and explain the origin of the matter-antimatter asymmetry in the Universe. We explore the parameter space of such a two-Higgs-doublet-model and show that a first order electroweak phase transition strongly correlates with a significant uplifting of the Higgs vacuum w.r.t. its Standard Model value. We then obtain the spectrum and properties of the new scalars H{sub 0}, A{sub 0} and H{sup ±} that signal such a phase transition, showing that the decay A{sub 0}→H{sub 0}Z at the LHC and a sizable deviation in the Higgs self-coupling λ{sub hhh} from its SM value are sensitive indicators of a strongly first order electroweak phase transition in the 2HDM.

  2. Study of electroweak vacuum stability from extended Higgs portal of dark matter and neutrinos

    Science.gov (United States)

    Ghosh, Purusottam; Saha, Abhijit Kumar; Sil, Arunansu

    2018-04-01

    We investigate the electroweak vacuum stability in an extended version of the Standard Model that incorporates two additional singlet scalar fields and three right-handed neutrinos. One of these extra scalars plays the role of dark matter, while the other scalar not only helps make the electroweak vacuum stable but also opens up the low-mass window of the scalar singlet dark matter (<500 GeV ). We consider the effect of large neutrino Yukawa coupling on the running of Higgs quartic coupling. We have analyzed the constraints on the model and identified the range of parameter space that is consistent with the neutrino mass, appropriate relic density, and direct search limits from the latest XENON 1T preliminary result as well as realized the stability of the electroweak vacuum up to the Planck scale.

  3. Axion inflation, proton decay, and leptogenesis in S U (5 )×U (1 )P Q

    Science.gov (United States)

    Boucenna, Sofiane M.; Shafi, Qaisar

    2018-04-01

    We implement inflation in a nonsupersymmetric S U (5 ) model based on a nonminimal coupling of the axion field to gravity. The isocurvature fluctuations are adequately suppressed, axions comprise the dark matter, proton lifetime estimates are of order 8 ×1034- 3 ×1035 yr , and the observed baryon asymmetry arises via nonthermal leptogenesis. The presence of low-scale colored scalars ensures unification of the Standard Model gauge couplings and also helps in stabilizing the electroweak vacuum.

  4. Electroweak symmetry breaking: to Higgs or not to Higgs” (3/3)

    CERN Multimedia

    CERN. Geneva

    2009-01-01

    How do elementary particles acquire their mass? What is making the photon different from the Z boson? In a word: How is electroweak symmetry broken? This is one of the pressing questions in particle physics that the LHC will answer soon. The aim of this lectures is, after briefly introducing SM physics and the conventional Higgs mechanism, to give a survey of recent attempts to go beyond a simple elementary Higgs. In particular, I will describe composite models (where the Higgs boson emerges from a strongly-interacting sector) and Higsless models. Distinctive signatures at the LHC are expected and will reveal the true nature of the electroweak symmetry sector.

  5. Electroweak symmetry breaking: to Higgs or not to Higgs” (2/3)

    CERN Multimedia

    CERN. Geneva

    2009-01-01

    How do elementary particles acquire their mass? What is making the photon different from the Z boson? In a word: How is electroweak symmetry broken? This is one of the pressing questions in particle physics that the LHC will answer soon. The aim of this lectures is, after briefly introducing SM physics and the conventional Higgs mechanism, to give a survey of recent attempts to go beyond a simple elementary Higgs. In particular, I will describe composite models (where the Higgs boson emerges from a strongly-interacting sector) and Higsless models. Distinctive signatures at the LHC are expected and will reveal the true nature of the electroweak symmetry sector.

  6. Electroweak symmetry breaking: to Higgs or not to Higgs” (1/3)

    CERN Multimedia

    CERN. Geneva

    2009-01-01

    How do elementary particles acquire their mass? What is making the photon different from the Z boson? In a word: How is electroweak symmetry broken? This is one of the pressing questions in particle physics that the LHC will answer soon. The aim of this lectures is, after briefly introducing SM physics and the conventional Higgs mechanism, to give a survey of recent attempts to go beyond a simple elementary Higgs. In particular, I will describe composite models (where the Higgs boson emerges from a strongly-interacting sector) and Higsless models. Distinctive signatures at the LHC are expected and will reveal the true nature of the electroweak symmetry sector.

  7. Extra generations and discrepancies of electroweak precision data

    OpenAIRE

    Novikov, V. A.; Okun, L. B.; Rozanov, A. N.; Vysotsky, M. I.

    2001-01-01

    It is shown that additional chiral generations are not excluded by the latest electroweak precision data if one assumes that there is no mixing with the known three generations. In the case of ``heavy extra generations'', when all four new particles are heavier than $Z$ boson, quality of the fit for the one new generation is as good as for zero new generations (Standard Model). In the case of neutral leptons with masses around 50 GeV (``partially heavy extra generations'') the minimum of $\\ch...

  8. Upper bound on the cutoff in lattice electroweak theory

    International Nuclear Information System (INIS)

    Veselov, A.I.; Zubkov, M.A.

    2008-01-01

    We investigate numerically lattice Weinberg-Salam model without fermions for realistic values of the fine structure constant and the Weinberg angle. We also analyze the data of the previous numerical investigations of lattice Electroweak theory. We have found that moving along the line of constant physics when the lattice spacing a is decreased, one should leave the physical Higgs phase of the theory at a certain value of a. Our estimate of the minimal value of the lattice spacing is a c = [430 ± 40 GeV] -1 .

  9. Electroweak contributions to SUSY particle production processes at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Mirabella, Edoardo

    2009-07-22

    In this thesis we have computed the electroweak contributions of O({alpha}{sub s}{alpha}), O({alpha}{sup 2}) and O({alpha}{sub s}{sup 2}) to three different classes of processes leading to the hadronic production of the SUSY partners of quarks and gluons, i.e. squarks and gluinos. The theoretical framework is the Minimal Supersymmetric extension of the Standard Model, the MSSM. The three processes are gluino pair production, diagonal squark-antisquark and associated squark-gluino production.

  10. After the Higgs: status and prospects of the electroweak fit of the SM and beyond -- with Gfitter

    CERN Multimedia

    CERN. Geneva

    2013-01-01

    models are also obtained, through an analysis of the so-called oblique parameters. We discuss the impact of the electroweak fit on Higgs coupling studies and vice versa. Future measurements at the Large Hadron Collider and the International Linear Collider promise to improve the experimental precision of key observables used in the fit. We present the prospects of the global electroweak fit in view of these improvements.

  11. Bounds on dark matter interactions with electroweak gauge bosons

    Energy Technology Data Exchange (ETDEWEB)

    Cotta, R. C.; Hewett, J. L.; Le, M. -P.; Rizzo, T. G.

    2013-12-01

    We investigate scenarios in which dark matter interacts with the Standard Model primarily through electroweak gauge bosons. We employ an effective field theory framework wherein the Standard Model and the dark matter particle are the only light states in order to derive model-independent bounds. Bounds on such interactions are derived from dark matter production by weak boson fusion at the LHC, indirect detection searches for the products of dark matter annihilation and from the measured invisible width of the Z 0 . We find that limits on the UV scale, Λ , reach weak scale values for most operators and values of the dark matter mass, thus probing the most natural scenarios in the weakly interacting massive particle dark matter paradigm. Our bounds suggest that light dark matter ( m χ ≲ m Z / 2 or m χ ≲ 100 – 200 GeV , depending on the operator) cannot interact only with the electroweak gauge bosons of the Standard Model, but rather requires additional operator contributions or dark sector structure to avoid overclosing the Universe.

  12. Single field inflation in supergravity with a U(1) gauge symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Heurtier, L. [Centre de Physique Théorique, École Polytechnique, CNRS, 91128 Palaiseau (France); Khalil, S.; Moursy, A., E-mail: lucien.heurtier@polytechnique.edu, E-mail: skhalil@zewailcity.edu.eg, E-mail: amoursy@zewailcity.edu.eg [Center for Fundamental Physics, Zewail City of Science and Technology, 6 October City, Cairo (Egypt)

    2015-10-01

    A single field inflation based on a supergravity model with a shift symmetry and U(1) extension of the MSSM is analyzed. We show that one of the real components of the two U(1) charged scalar fields plays the role of inflaton with an effective scalar potential similar to the ''new chaotic inflation'' scenario. Both non-anomalous and anomalous (with Fayet-Iliopoulos term) U(1) are studied. We show that the non-anomalous U(1) scenario is consistent with data of the cosmic microwave background and recent astrophysical measurements. A possible kinetic mixing between U(1) and U(1){sub B−L} is considered in order to allow for natural decay channels of the inflaton, leading to a reheating epoch. Upper limits on the reheating temperature thus turn out to favour an intermediate (∼ O(10{sup 13}) GeV) scale B−L symmetry breaking.

  13. Single field inflation in supergravity with a U(1) gauge symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Heurtier, L. [Centre de Physique Théorique, École Polytechnique, CNRS,91128 Palaiseau (France); Khalil, S. [Center for Fundamental Physics, Zewail City of Science and Technology,6 October City, Cairo (Egypt); Department of Mathematics, Faculty of Science, Ain Shams University,Cairo, 11566 (Egypt); Moursy, A. [Center for Fundamental Physics, Zewail City of Science and Technology,6 October City, Cairo (Egypt)

    2015-10-19

    A single field inflation based on a supergravity model with a shift symmetry and U(1) extension of the MSSM is analyzed. We show that one of the real components of the two U(1) charged scalar fields plays the role of inflaton with an effective scalar potential similar to the “new chaotic inflation” scenario. Both non-anomalous and anomalous (with Fayet-Iliopoulos term) U(1) are studied. We show that the non-anomalous U(1) scenario is consistent with data of the cosmic microwave background and recent astrophysical measurements. A possible kinetic mixing between U(1) and U(1){sub B−L} is considered in order to allow for natural decay channels of the inflaton, leading to a reheating epoch. Upper limits on the reheating temperature thus turn out to favour an intermediate (∼O(10{sup 13}) GeV) scale B−L symmetry breaking.

  14. Effect of Various Modifications on Drag and Longitudinal Stability and Control Characteristics at Transonic Speeds of a Model of the XF7U-1 Tailless Airplane: NACA Wing-FLow Method, TED No. NACA DE 307

    Science.gov (United States)

    Sawyer, Richard H.; Trant, James P., Jr.

    1950-01-01

    An investigation was made by the NACA wing-flow method to determine the drag, pitching-moment, lift, and angle-of-attack characteristics at transonic speeds of various configurations of a semispan model of an early configuration of the XF7U-1 tailless airplane. The results of the tests indicated that for the basic configuration with undeflected ailavator, the zero-lift drag rise occurred at a Mach number of about 0.85 and that about a five-fold increase in drag occurred through the transonic speed range. The results of the tests also indicated that the drag increment produced by -8.0 degrees deflection of the ailavator increased with increase in normal-force coefficient and was smaller at speeds above than at speeds below the drag rise. The drag increment produced by 35 degree deflection of the speed brakes varied from 0.040 to 0.074 depending on the normal-force coefficient and Mach number. These values correspond to drag coefficients of about 0.40 and 0.75 based on speed-brake frontal area. Removal of the fin produced a small positive drag increment at a given normal-force coefficient at speeds during the drag rise. A large forward shift of the neutral-point location occurred at Mach numbers above about 0.90 upon removal of the fin, and also a considerable forward shift throughout the Mach number range occurred upon deflection of the speed brakes. Ailavator ineffectiveness or reversal at low deflections, similar to that determined in previous tests of the basic configuration of the model in the Mach number range from about 0.93 to 1.0, was found for the fin-off configuration and for the model equipped with skewed (more highly sweptback) hinge-line ailavators. With the speed brakes deflected, little or no loss in the incremental pitching moment produced by deflection of the ailavator from O degrees to -8.00 degrees occurred in the Mach number range from 0.85 to 1.0 in contrast to a considerable loss found in previous tests with the speed brakes off.

  15. Kinetic Mixing of U(1)s in Heterotic Orbifolds

    CERN Document Server

    Goodsell, Mark; Ringwald, Andreas

    2012-01-01

    We study kinetic mixing between massless U(1) gauge symmetries in the bosonic formulation of heterotic orbifold compactifications. For non-prime Z_N factorisable orbifolds, we find a simple expression of the mixing in terms of the properties of the N=2 subsectors, which helps understand under what conditions mixing can occur. With this tool, we analyse Z_6-II heterotic orbifolds and find non-vanishing mixing even without including Wilson lines. We show that some semi-realistic models of the Mini-Landscape admit supersymmetric vacua with mixing between the hypercharge and an additional U(1), which can be broken at low energies. We finally discuss some phenomenologically appealing possibilities that hidden photons in heterotic orbifolds allow.

  16. Kinetic mixing of U(1)s in heterotic orbifolds

    Energy Technology Data Exchange (ETDEWEB)

    Goodsell, Mark [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Ramos-Sanchez, Saul [UNAM, Mexico (Mexico). Dept. of Theoretical Physics; Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-10-15

    We study kinetic mixing between massless U(1) gauge symmetries in the bosonic formulation of heterotic orbifold compactifications. For non-prime Z{sub N} factorisable orbifolds, we find a simple expression of the mixing in terms of the properties of the N=2 subsectors, which helps understand under what conditions mixing can occur. With this tool, we analyse Z{sub 6}-II heterotic orbifolds and find non-vanishing mixing even without including Wilson lines. We show that some semi-realistic models of the Mini-Landscape admit supersymmetric vacua with mixing between the hypercharge and an additional U(1), which can be broken at low energies. We finally discuss some phenomenologically appealing possibilities that hidden photons in heterotic orbifolds allow. (orig.)

  17. U(1) textures and Lepton Flavor Violation

    CERN Document Server

    Gómez, M E; Lola, S; Vergados, J D

    1999-01-01

    U(1) family symmetries have led to successful predictions of the fermion mass spectrum and the mixing angles of the hadronic sector. In the context of the supersymmetric unified theories, they further imply a non-trivial mass structure for the scalar partners, giving rise to new sources of flavour violation. In the present work, lepton flavour non-conserving processes are examined in the context of the MSSM augmented by a U(1) family symmetry. We calculate the mixing effects on the mu -> e gamma and tau-> mu gamma rare decays. All supersymmetric scalar masses involved in the processes are determined at low energies using two loop renormalisation group analysis and threshold corrections. Further, various novel effects are considered and found to have important impact on the branching ratios. Thus, a rather interesting result is that when the see-saw mechanism is applied in the (12X12)-sneutrino mass matrix, the mixing effects of the Dirac matrix in the effective light sneutrino sector are canceled at first ord...

  18. Exclusive radiative and electroweak b→d and b→s penguin decays at NLO

    International Nuclear Information System (INIS)

    Beneke, M.; Seidel, D.; Feldmann, T.

    2005-01-01

    We provide standard model expectations for the rare radiative decays B→K * γ, B→ργ and B→ωγ, and the electroweak penguin decays B→K * l + l - and B→ρl + l - at the next-to-leading order (NLO), extending our previous results to b→d transitions. We consider branching fractions, isospin asymmetries and direct CPasymmetries. For the electroweak penguin decays, the lepton-invariant mass spectrum and forward-backward asymmetry is also included. Radiative and electroweak penguin transitions in b→d are mainly interesting in the search for new flavor-changing neutral current interactions, but in addition the B→ργ decays provide constraints on the CKM parameters (anti ρ, anti η). The potential impact of these constraints is discussed. (orig.)

  19. Towards the theory of the electroweak phase transition

    International Nuclear Information System (INIS)

    Dine, M.; Leigh, R.G.; Huet, P.; Linde, A.; Linde, D.

    1992-01-01

    We investigate various problems related to the theory of the electroweak phase transition. This includes determination of the nature of the phase transition, discussion of the possible role of the higher-order radiative corrections, and the theory of the formation and evolution of bubbles of the new phase. We show, in particular, that no dangerous linear terms in the scalar field φ appear in the expression for the effective potential. We have found that, for the Higgs-boson mass smaller than the masses of W and Z bosons, the phase transition is of the first order. However, its strength is approximately 2/3 times less than what follows from the one-loop approximation. The phase transition occurs due to production and expansion of critical bubbles. Subcritical bubbles may be important only if the phase transition is very weakly first order. A general analytic expression for the probability of the bubble formation is obtained, which may be used for study of tunneling in a wide class of theories. The bubble-wall velocity depends on many factors, including the ratio of the mean free path of the particles to the thickness of the wall. Thin walls in the electroweak theory have a nonrelativistic velocity, whereas thick walls may be relativistic. A decrease of the cubic term by the factor 2/3 rules our baryogenesis in the minimal version of the electroweak theory. Even though we concentrate in this paper on the phase transition in this theory, most of our results can be applied to more general models as well, where baryogenesis is possible

  20. Study of Electroweak Gauge Boson Scattering in the WZ Channel with the ATLAS Detector at the Large Hadron Collider

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00355153; Kobel, Michael; Petridou, Chariclia; Kobel, Michael; Zur Nedden, Martin

    The Standard Model of particle physics is a very well tested gauge theory describing the strong, weak and electromagnetic interactions between elementary particles through the exchange of force carriers called gauge bosons. Its high predictive power stems from its ability to derive the properties of the interactions it describes from fundamental symmetries of nature. Yet, it is not a final theory as there are several phenomena it cannot explain. Furthermore, not all of its predictions have been studied with sufficient precision, e.g. the properties of the newly discovered Higgs boson. Therefore, further probing of the Standard Model is necessary and may result in finding possible indications for new physics. The non-abelian SU(2)L×U(1)Y symmetry group determines the properties of the electromagnetic and weak interactions giving rise to self-couplings between the electroweak gauge bosons, i.e. the massive W and Z boson, and the massless photon, via triple and quartic gauge couplings. Studies carried out over ...

  1. Physics Implications of Flat Directions in Free Fermionic Superstring Models; 2, Renormalization Group Analysis

    CERN Document Server

    Cleaver, G.; Espinosa, J.R.; Everett, L.L.; Langacker, P.; Wang, J.

    1999-01-01

    We continue the investigation of the physics implications of a class of flat directions for a prototype quasi-realistic free fermionic string model (CHL5), building upon the results of the previous paper in which the complete mass spectrum and effective trilinear couplings of the observable sector were calculated to all orders in the superpotential. We introduce soft supersymmetry breaking mass parameters into the model, and investigate the gauge symmetry breaking patterns and the renormalization group analysis for two representative flat directions, which leave an additional $U(1)'$ as well as the SM gauge group unbroken at the string scale. We study symmetry breaking patterns that lead to a phenomenologically acceptable $Z-Z'$ hierarchy, $M_{Z^{'}} \\sim {\\cal O}(1~{\\rm TeV})$ and $ 10^{12}~{\\rm GeV}$ for electroweak and intermediate scale $U(1)^{'}$ symmetry breaking, respectively, and the associated mass spectra after electroweak symmetry breaking. The fermion mass spectrum exhibits unrealistic features, i...

  2. Electroweak penguin contributions in charmless B→VV decays beyond leading logarithms

    International Nuclear Information System (INIS)

    Dongsheng Du; Libo Guo

    1997-01-01

    Using the next-to-leading-order, low-energy effective Hamiltonian for vertical bar ΔB vertical bar = 1, ΔC = ΔU = 0 transitions, the contributions of electroweak penguin operators in charmless B→VV decays are estimated in the standard model. We find that, for some channels, the electroweak penguin effects can enhance or reduce the QCD penguin and/or tree-level contributions by at least 20%, and can even play a dominant role in decay widths and CP-asymmetries, but the corrections to the angular distribution are negligible. (author)

  3. A determination of electroweak parameters at HERA

    Science.gov (United States)

    H1 Collaboration; Aktas, A.; Andreev, V.; Anthonis, T.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Babaev, A.; Backovic, S.; Bähr, J.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Baumgartner, S.; Becker, J.; Beckingham, M.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berger, N.; Bizot, J. C.; Boenig, M.-O.; Boudry, V.; Bracinik, J.; Brandt, G.; Brisson, V.; Brown, D. P.; Bruncko, D.; Büsser, F. W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A. J.; Caron, S.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Contreras, J. G.; Coughlan, J. A.; Cox, B. E.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Dau, W. D.; Daum, K.; de Boer, Y.; Delcourt, B.; de Roeck, A.; Desch, K.; de Wolf, E. A.; Diaconu, C.; Dodonov, V.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Erdmann, W.; Essenov, S.; Falkewicz, A.; Faulkner, P. J. W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Finke, L.; Fleischer, M.; Fleischmann, P.; Fleming, Y. H.; Flucke, G.; Fomenko, A.; Foresti, I.; Franke, G.; Frisson, T.; Gabathuler, E.; Garutti, E.; Gayler, J.; Gerlich, C.; Ghazaryan, S.; Ginzburgskaya, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Goyon, C.; Grab, C.; Greenshaw, T.; Gregori, M.; Grell, B. R.; Grindhammer, G.; Gwilliam, C.; Haidt, D.; Hajduk, L.; Hansson, M.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Henshaw, O.; Herrera, G.; Hildebrandt, M.; Hiller, K. H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hreus, T.; Hussain, S.; Ibbotson, M.; Ismail, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jönsson, L.; Johnson, D. P.; Jung, A. W.; Jung, H.; Kapichine, M.; Katzy, J.; Keller, N.; Kenyon, I. R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knies, G.; Knutsson, A.; Korbel, V.; Kostka, P.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Krüger, K.; Kückens, J.; Landon, M. P. J.; Lange, W.; Laštovička, T.; Laštovička-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; Liptaj, A.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lueders, H.; Lüke, D.; Lux, T.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marshall, R.; Martisikova, M.; Martyn, H.-U.; Maxfield, S. J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A. B.; Meyer, H.; Meyer, J.; Mikocki, S.; Milcewicz-Mika, I.; Milstead, D.; Mladenov, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J. V.; Mozer, M. U.; Müller, K.; Murín, P.; Nankov, K.; Naroska, B.; Naumann, Th.; Newman, P. R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J. E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Papadopoulou, T.; Pascaud, C.; Patel, G. D.; Peez, M.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Pitzl, D.; Plačakytė, R.; Portheault, B.; Povh, B.; Prideaux, P.; Raicevic, N.; Reimer, P.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salvaire, F.; Sankey, D. P. C.; Sauvan, E.; Schätzel, S.; Schilling, F.-P.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schöning, A.; Schultz-Coulon, H.-C.; Sedlák, K.; Sefkow, F.; Shaw-West, R. N.; Sheviakov, I.; Shtarkov, L. N.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Tchoulakov, V.; Thompson, G.; Thompson, P. D.; Tomasz, F.; Traynor, D.; Truöl, P.; Tsakov, I.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, M.; Usik, A.; Utkin, D.; Valkár, S.; Valkárová, A.; Vallée, C.; van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Veelken, C.; Vest, A.; Vinokurova, S.; Volchinski, V.; Vujicic, B.; Wacker, K.; Wagner, J.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Wigmore, C.; Wissing, Ch.; Wolf, R.; Wünsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zhu, Y. C.; Zimmermann, J.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

    2006-01-01

    Using the deep inelastic ep and ep charged and neutral current scattering cross sections previously published, a combined electroweak and QCD analysis is performed to determine electroweak parameters accounting for their correlation with parton distributions. The data used have been collected by the H1 experiment in 1994 2000 and correspond to an integrated luminosity of 117.2 pb. A measurement is obtained of the W propagator mass in charged current ep scattering. The weak mixing angle sinθ is determined in the on-mass-shell renormalisation scheme. A first measurement at HERA is made of the light quark weak couplings to the Z boson and a possible contribution of right-handed isospin components to the weak couplings is investigated.

  4. A Determination of Electroweak Parameters at HERA

    CERN Document Server

    Aktas, A.; Anthonis, T.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Babaev, A.; Backovic, S.; Bahr, J.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Baumgartner, S.; Becker, J.; Beckingham, M.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berger, N.; Bizot, J.C.; Boenig, M.-O.; Boudry, V.; Bracinik, J.; Brandt, G.; Brisson, V.; Brown, D.P.; Bruncko, D.; Busser, F.W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Caron, S.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Contreras, J.G.; Coughlan, J.A.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; de Boer, Y.; Delcourt, B.; De Roeck, A.; Desch, K.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dubak, A.; Eckerlin, Guenter; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Erdmann, W.; Essenov, S.; Falkewicz, A.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Finke, L.; Fleischer, M.; Fleischmann, P.; Fleming, Y.H.; Flucke, G.; Fomenko, A.; Foresti, I.; Franke, G.; Frisson, T.; Gabathuler, E.; Garutti, E.; Gayler, J.; Gerlich, C.; Ghazaryan, Samvel; Ginzburgskaya, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Goyon, C.; Grab, C.; Greenshaw, T.; Gregori, M.; Grell, B.R.; Grindhammer, Guenter; Gwilliam, C.; Haidt, D.; Hajduk, L.; Hansson, M.; Heinzelmann, G.; Henderson, R.C.W.; Henschel, H.; Henshaw, O.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hreus, T.; Hussain, S.; Ibbotson, M.; Ismail, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jung, Andreas Werner; Jung, H.; Kapichine, M.; Katzy, J.; Keller, N.; Kenyon, I.R.; Kiesling, Christian M.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knies, G.; Knutsson, A.; Korbel, V.; Kostka, P.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kuckens, J.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; Liptaj, A.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lueders, H.; Luke, D.; Lux, T.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marshall, R.; Martisikova, M.; Martyn, H.-U.; Maxeld, S.J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Milcewicz-Mika, I.; Milstead, D.; Mladenov, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, Matthias Ulrich; Muller, K.; Murin, P.; Nankov, K.; Naroska, B.; Naumann, Th.; Newman, Paul R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J.E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Papadopoulou, T.; Pascaud, C.; Patel, G.D.; Peez, M.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Pitzl, D.; Placakyte, R.; Portheault, B.; Povh, B.; Prideaux, P.; Raicevic, N.; Reimer, P.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salvaire, F.; Sankey, D.P.C.; Sauvan, E.; Schatzel, S.; Schilling, F.-P.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.-C.; Sedlak, K.; Sefkow, F.; Shaw-West, R.N.; Sheviakov, I.; Shtarkov, L.N.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Tchoulakov, V.; Thompson, Graham; Thompson, P.D.; Tomasz, F.; Traynor, D.; Truoel, Peter; Tsakov, I.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, Marcel; Usik, A.; Utkin, D.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Veelken, C.; Vest, A.; Vinokurova, S.; Volchinski, V.; Vujicic, B.; Wacker, K.; Wagner, J.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Wigmore, C.; Wissing, Ch.; Wolf, R.; Wunsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zhu, Y.C.; Zimmermann, J.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

    2006-01-01

    Using the deep inelastic e^+p and e^-p charged and neutral current scattering cross sections previously published, a combined electroweak and QCD analysis is performed to determine electroweak parameters accounting for their correlation with parton distributions. The data used have been collected by the H1 experiment in 1994-2000 and correspond to an integrated luminosity of 117.2 pb^{-1}. A measurement is obtained of the W propagator mass in charged current ep scattering. The weak mixing angle sin^2 theta_W is determined in the on-mass-shell renormalisation scheme. A first measurement at HERA is made of the light quark weak couplings to the Z^0 boson and a possible contribution of right-handed isospin components to the weak couplings is investigated.

  5. Electroweak vacuum stability and finite quadratic radiative corrections

    Energy Technology Data Exchange (ETDEWEB)

    Masina, Isabella [Ferrara Univ. (Italy). Dipt. di Fisica e Scienze della Terra; INFN, Sezione di Ferrara (Italy); Southern Denmark Univ., Odense (Denmark). CP3-Origins; Southern Denmark Univ., Odense (Denmark). DIAS; Nardini, Germano [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Quiros, Mariano [Institucio Catalana de Recerca i Estudis Avancats (ICREA), Barcelona (Spain); IFAE-IAB, Barcelona (Spain)

    2015-07-15

    If the Standard Model (SM) is an effective theory, as currently believed, it is valid up to some energy scale Λ to which the Higgs vacuum expectation value is sensitive throughout radiative quadratic terms. The latter ones destabilize the electroweak vacuum and generate the SM hierarchy problem. For a given perturbative Ultraviolet (UV) completion, the SM cutoff can be computed in terms of fundamental parameters. If the UV mass spectrum involves several scales the cutoff is not unique and each SM sector has its own UV cutoff Λ{sub i}. We have performed this calculation assuming the Minimal Supersymmetric Standard Model (MSSM) is the SM UV completion. As a result, from the SM point of view, the quadratic corrections to the Higgs mass are equivalent to finite threshold contributions. For the measured values of the top quark and Higgs masses, and depending on the values of the different cutoffs Λ{sub i}, these contributions can cancel even at renormalization scales as low as multi-TeV, unlike the case of a single cutoff where the cancellation only occurs at Planckian energies, a result originally obtained by Veltman. From the MSSM point of view, the requirement of stability of the electroweak minimum under radiative corrections is incorporated into the matching conditions and provides an extra constraint on the Focus Point solution to the little hierarchy problem in the MSSM. These matching conditions can be employed for precise calculations of the Higgs sector in scenarios with heavy supersymmetric fields.

  6. Probing electroweak gauge boson scattering with the ATLAS detector at the large hadron collider

    International Nuclear Information System (INIS)

    Anger, Philipp

    2014-01-01

    Electroweak gauge bosons as central components of the Standard Model of particle physics are well understood theoretically and have been studied with high precision at past and present collider experiments. The electroweak theory predicts the existence of a scattering process of these particles consisting of contributions from triple and quartic bosonic couplings as well as Higgs boson mediated interactions. These contributions are not separable in a gauge invariant way and are only unitarized in the case of a Higgs boson as it is described by the Standard Model. The process is tied to the electroweak symmetry breaking which introduces the longitudinal modes for the massive electroweak gauge bosons. A study of this interaction is also a direct verification of the local gauge symmetry as one of the fundamental axioms of the Standard Model. With the start of the Large Hadron Collider and after collecting proton-proton collision data with an integrated luminosity of 20.3 fb -1 at a center-of-mass energy of √(s)=8 TeV with the ATLAS detector, first-ever evidence for this process could be achieved in the context of this work. A study of leptonically decaying W ± W ± jj, same-electric-charge diboson production in association with two jets resulted in an observation of the electroweak W ± W ± jj production with same electric charge of the W bosons, inseparably comprising W ± W ± →W ± W ± electroweak gauge boson scattering contributions, with a significance of 3.6 standard deviations. The measured production cross section is in agreement with the Standard Model prediction. In the course of a study for leptonically decaying WZ productions, methods for background estimation, the extraction of systematic uncertainties and cross section measurements were developed. They were extended and applied to the WZjj final state whereof the purely electroweakly mediated contribution is intrinsically tied to the scattering of all Standard Model electroweak gauge bosons: W

  7. Structure functions of electroweak boson and leptons

    International Nuclear Information System (INIS)

    Slominski, W.; Szwed, J.

    1996-01-01

    The QCD structure of the electroweak bosons is reviewed and the lepton structure function is defined and calculated. The leading order splitting functions of electron into quarks are extracted, showing an important contribution from γ-Z interference. Leading logarithmic QCD evolution equations are constructed and solved in the asymptotic region where log 2 behavior of the Parton densities is observed. Possible applications with clear manifestation of ''resolved'' photon and weak bosons are discussed. 8 refs., 3 figs

  8. Electroweak Precision Measurements with the ATLAS Detector

    CERN Document Server

    Linck, Rebecca Anne; The ATLAS collaboration

    2018-01-01

    As part of its ongoing exploration into the nature of the particles produced in high energy proton-proton collisions, the ATLAS detector has been used to perform a number of new precision electroweak measurements. In this talk the recent measurements of the W-boson mass, the Drell-Yan triple-differential cross-section and the polarisation of tau leptons in Z/γ* → ττ decays will be discussed.

  9. Optimal tests for electroweak loop effects

    International Nuclear Information System (INIS)

    Aoki, Kenichi; Aoyama, Hideaki; Harvard Univ., Cambridge, MA

    1986-01-01

    A statistical analysis is given for the experimental precision necessary for establishing loop effects in the electroweak theory. Cases with three observables, gauge boson masses and the Weinberg angle, is analyzed by an optimised test. An information on the Weinberg angle with even 5% error (+-.01 in sin 2 thetasub(W)) is shown to reduce the requirement for the measurements of gauge boson masses significantly. (orig.)

  10. Electroweak measurements with the ATLAS detector

    CERN Multimedia

    CERN. Geneva

    2014-01-01

    The seminar presents an overview of the ATLAS electroweak physics programme. Recent measurements of di-boson and multi-boson production processes involving combinations of W, Z and isolated photons, associated with up to two jets, at 8 TeV proton-proton collisions are discussed. Inclusive, fiducial and differential production cross sections are presented, including vector-boson fusion and vector-boson scattering processes. These measurements allow to derive constraints on anomalous triple and quartic gauge couplings.

  11. Signatures of CP-Violating Electroweak Penguins in K and B Decays

    International Nuclear Information System (INIS)

    Schwab, Felix

    2007-01-01

    The B->πK decays with significant electroweak penguin contributions show a puzzling pattern. We explore this ''B->πK puzzle'' through a systematic strategy. The starting point, which is essentially unaffected by electroweak penguins, is the determination of the angle γ of the unitarity triangle through the CP-violating B d 0 ->π + π - , B d 0 ->π - K + asymmetries, yielding γ=(73.9 -6.5 +5.8 ) o , and the extraction of hadronic parameters through the measured B->ππ branching ratios. Using arguments related to the SU(3) flavor symmetry, we convert the hadronic B->ππ parameters into their B->πK counterparts, allowing us to predict the B->πK observables in the Standard Model. We find agreement with the data for those quantities that are only marginally affected by electroweak penguins, while this is not the case for the observables with sizeable electroweak penguin contributions. Since we may also perform a couple of internal consistency checks of our working assumptions, which are nicely satisfied for the current data, and find a small sensitivity of our results to large non-factorizable SU(3)-breaking corrections, the ''B->πK'' puzzle may be due to new physics in the electroweak penguin sector. We show that it can indeed be resolved through such a kind of new physics with a large CP-violating phase. Further insights into the electroweak penguins are provided by the B + ->π 0 K + and B d 0 ->π 0 K S CP asymmetries, and in particular through correlations with various rare K and B decays

  12. Electroweak boson production in Pb+Pb

    CERN Document Server

    Balestri, T; The ATLAS collaboration

    2013-01-01

    Lead-lead collisions at the LHC are capable of producing a system of deconfined quarks and gluons at unprecedented energy density and temperature. Partonic-level interactions and energy-loss mechanisms in the medium can be studied with the aid of electroweak bosons which carry important information about the properties of the medium. Electroweak bosons form a class of unique high-$p_{T}$ probes because their decay products do not interact with the strongly-coupled medium, providing a benchmark for a variety of other phenomena measured with strongly interacting particles. The ATLAS experiment measures isolated high-$p_{T}$ photons, W and Z bosons via different decay channels. New analyses of experimental data obtained at the LHC with lead-lead beams at $\\sqrt{s_{NN}}$ = 2.76 TeV. This talk will present a comprehensive study of the scaling properties of electroweak bosons showing linear proportionality of production rates to the nuclear thickness function; rapidity distributions W-decays directly sensitivity to...

  13. Fundamental Physics with Electroweak Probes of Nuclei

    Science.gov (United States)

    Pastore, Saori

    2018-02-01

    The past decade has witnessed tremendous progress in the theoretical and computational tools that produce our understanding of nuclei. A number of microscopic calculations of nuclear electroweak structure and reactions have successfully explained the available experimental data, yielding a complex picture of the way nuclei interact with electroweak probes. This achievement is of great interest from the pure nuclear-physics point of view. But it is of much broader interest too, because the level of accuracy and confidence reached by these calculations opens up the concrete possibility of using nuclei to address open questions in other sub-fields of physics, such as, understanding the fundamental properties of neutrinos, or the particle nature of dark matter. In this talk, I will review recent progress in microscopic calculations of electroweak properties of light nuclei, including electromagnetic moments, form factors and transitions in between lowlying nuclear states along with preliminary studies for single- and double-beta decay rates. I will illustrate the key dynamical features required to explain the available experimental data, and, if time permits, present a novel framework to calculate neutrino-nucleus cross sections for A > 12 nuclei.

  14. Complete one-loop renormalization of the Higgs-electroweak chiral Lagrangian

    Science.gov (United States)

    Buchalla, G.; Catà, O.; Celis, A.; Knecht, M.; Krause, C.

    2018-03-01

    Employing background-field method and super-heat-kernel expansion, we compute the complete one-loop renormalization of the electroweak chiral Lagrangian with a light Higgs boson. Earlier results from purely scalar fluctuations are confirmed as a special case. We also recover the one-loop renormalization of the conventional Standard Model in the appropriate limit.

  15. The Continuum Limit of a Fermion System Involving Leptons and Quarks: Strong, Electroweak and Gravitational Interactions

    OpenAIRE

    Finster, Felix

    2014-01-01

    The causal action principle is analyzed for a system of relativistic fermions composed of massive Dirac particles and neutrinos. In the continuum limit, we obtain an effective interaction described by classical gravity as well as the strong and electroweak gauge fields of the standard model.

  16. Electroweak interaction: Standard and beyond

    International Nuclear Information System (INIS)

    Harari, H.

    1987-02-01

    Several important topics within the standard model raise questions which are likely to be answered only by further theoretical understanding which goes beyond the standard model. In these lectures we present a discussion of some of these problems, including the quark masses and angles, the Higgs sector, neutrino masses, W and Z properties and possible deviations from a pointlike structure. 44 refs

  17. Dirichlet Higgs in Extra-Dimension Consistent with Electroweak Data

    International Nuclear Information System (INIS)

    Naoyuki Habay; Kin-ya Odaz; Ryo Takahashi

    2011-01-01

    We propose a simple five-dimensional extension of the Standard Model (SM) without any Higgs potential nor any extra fields. A Higgs doublet lives in the bulk of a flat line segment and its boundary condition is Dirichlet at the ends of the line, which causes the electroweak symmetry breaking without Higgs potential. The vacuum expectation value of the Higgs is induced from the Dirichlet boundary condition which is generally allowed in higher dimensional theories. The lightest physical Higgs has non-flat profile in the extra dimension even though the vacuum expectation value is flat. As a consequence, we predict a maximal top Yukawa deviation (no coupling between top and Higgs) for the brane-localized fermion and a small deviation, a multiplication of 2√2/π ≅ 0.9 to the Yukawa coupling, for the bulk fermion. The latter is consistent with the electroweak precision data within 90% C.L. for 430 GeV ≤ m KK ≤ 500 GeV. (authors)

  18. Hadronic electroweak processes in a finite volume

    International Nuclear Information System (INIS)

    Agadjanov, Andria

    2017-01-01

    In the present thesis, we study a number of hadronic electroweak processes in a finite volume. Our work is motivated by the ongoing and future lattice simulations of the strong interaction theory called quantum chromodynamics. According to the available computational resources, the numerical calculations are necessarily performed on lattices with a finite spatial extension. The first part of the thesis is based on the finite volume formalism which is a standard method to investigate the processes with the final state interactions, and in particular, the elastic hadron resonances, on the lattice. Throughout the work, we systematically apply the non-relativistic effective field theory. The great merit of this approach is that it encodes the low-energy dynamics directly in terms of the effective range expansion parameters. After a brief introduction into the subject, we formulate a framework for the extraction of the ΔNγ * as well as the B→K * transition form factors from lattice data. Both processes are of substantial phenomenological interest, including the search for physics beyond the Standard Model. Moreover, we provide a proper field-theoretical definition of the resonance matrix elements, and advocate it in comparison to the one based on the infinitely narrow width approximation. In the second part we consider certain aspects of the doubly virtual nucleon Compton scattering. The main objective of the work is to answer the question whether there is, in the Regge language, a so-called fixed pole in the process. To answer this question, the unknown subtraction function, which enters one of the dispersion relations for the invariant amplitudes, has to be determined. The external field method provides a feasible approach to tackle this problem on the lattice. Considering the nucleon in a periodic magnetic field, we derive a simple relation for the ground state energy shift up to a second order in the field strength. The obtained result encodes the value of the

  19. Hadronic electroweak processes in a finite volume

    Energy Technology Data Exchange (ETDEWEB)

    Agadjanov, Andria

    2017-11-07

    In the present thesis, we study a number of hadronic electroweak processes in a finite volume. Our work is motivated by the ongoing and future lattice simulations of the strong interaction theory called quantum chromodynamics. According to the available computational resources, the numerical calculations are necessarily performed on lattices with a finite spatial extension. The first part of the thesis is based on the finite volume formalism which is a standard method to investigate the processes with the final state interactions, and in particular, the elastic hadron resonances, on the lattice. Throughout the work, we systematically apply the non-relativistic effective field theory. The great merit of this approach is that it encodes the low-energy dynamics directly in terms of the effective range expansion parameters. After a brief introduction into the subject, we formulate a framework for the extraction of the ΔNγ{sup *} as well as the B→K{sup *} transition form factors from lattice data. Both processes are of substantial phenomenological interest, including the search for physics beyond the Standard Model. Moreover, we provide a proper field-theoretical definition of the resonance matrix elements, and advocate it in comparison to the one based on the infinitely narrow width approximation. In the second part we consider certain aspects of the doubly virtual nucleon Compton scattering. The main objective of the work is to answer the question whether there is, in the Regge language, a so-called fixed pole in the process. To answer this question, the unknown subtraction function, which enters one of the dispersion relations for the invariant amplitudes, has to be determined. The external field method provides a feasible approach to tackle this problem on the lattice. Considering the nucleon in a periodic magnetic field, we derive a simple relation for the ground state energy shift up to a second order in the field strength. The obtained result encodes the

  20. A re-interpretation of $\\sqrt{s}=8~$TeV ATLAS results on electroweak supersymmetry production to explore general gauge mediated models

    CERN Document Server

    The ATLAS collaboration

    2016-01-01

    This document determines the constraints placed by the ATLAS experiment on general gauge mediated (GGM) supersymmetric models. The GGM parameters are chosen in such a way that the constraints from the observed Higgs mass are satisfied. Three varied parameters ($\\mu$, $M_{2}$ and $\\tan\\beta$) determine the phenomenology at the LHC, featuring the lightest wino-higgsino mixture neutralinos and charginos decaying to the gravitino and $W$, $Z$, Higgs bosons or photons. Constraints from existing ATLAS searches using the full Run 1 dataset of 20.3 fb$^{-1}$ at $\\sqrt{s} =8~$TeV and targeting a variety of final states with multiple leptons or photons are evaluated. Results of different analyses are statistically combined, providing stringent limits on the three theoretical parameters.