Energy Technology Data Exchange (ETDEWEB)
Barbieri, Riccardo [Institute of Theoretical Studies, ETH Zurich,CH-8092 Zurich (Switzerland); Scuola Normale Superiore,Piazza dei Cavalieri 7, 56126 Pisa (Italy); Hall, Lawrence J.; Harigaya, Keisuke [Department of Physics, University of California,Berkeley, California 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory,Berkeley, California 94720 (United States)
2016-11-29
In a Mirror Twin World with a maximally symmetric Higgs sector the little hierarchy of the Standard Model can be significantly mitigated, perhaps displacing the cutoff scale above the LHC reach. We show that consistency with observations requires that the Z{sub 2} parity exchanging the Standard Model with its mirror be broken in the Yukawa couplings. A minimal such effective field theory, with this sole Z{sub 2} breaking, can generate the Z{sub 2} breaking in the Higgs sector necessary for the Twin Higgs mechanism. The theory has constrained and correlated signals in Higgs decays, direct Dark Matter Detection and Dark Radiation, all within reach of foreseen experiments, over a region of parameter space where the fine-tuning for the electroweak scale is 10-50%. For dark matter, both mirror neutrons and a variety of self-interacting mirror atoms are considered. Neutrino mass signals and the effects of a possible additional Z{sub 2} breaking from the vacuum expectation values of B−L breaking fields are also discussed.
Geller, Michael; Telem, Ofri
2015-05-15
We present the first realization of a "twin Higgs" model as a holographic composite Higgs model. Uniquely among composite Higgs models, the Higgs potential is protected by a new standard model (SM) singlet elementary "mirror" sector at the sigma model scale f and not by the composite states at m_{KK}, naturally allowing for m_{KK} beyond the LHC reach. As a result, naturalness in our model cannot be constrained by the LHC, but may be probed by precision Higgs measurements at future lepton colliders, and by direct searches for Kaluza-Klein excitations at a 100 TeV collider.
Geller, Michael; Telem, Ofri
2015-05-01
We present the first realization of a "twin Higgs" model as a holographic composite Higgs model. Uniquely among composite Higgs models, the Higgs potential is protected by a new standard model (SM) singlet elementary "mirror" sector at the sigma model scale f and not by the composite states at mKK , naturally allowing for mKK beyond the LHC reach. As a result, naturalness in our model cannot be constrained by the LHC, but may be probed by precision Higgs measurements at future lepton colliders, and by direct searches for Kaluza-Klein excitations at a 100 TeV collider.
Twin Higgs Asymmetric Dark Matter.
García García, Isabel; Lasenby, Robert; March-Russell, John
2015-09-18
We study asymmetric dark matter (ADM) in the context of the minimal (fraternal) twin Higgs solution to the little hierarchy problem, with a twin sector with gauged SU(3)^{'}×SU(2)^{'}, a twin Higgs doublet, and only third-generation twin fermions. Naturalness requires the QCD^{'} scale Λ_{QCD}^{'}≃0.5-20 GeV, and that t^{'} is heavy. We focus on the light b^{'} quark regime, m_{b^{'}}≲Λ_{QCD}^{'}, where QCD^{'} is characterized by a single scale Λ_{QCD}^{'} with no light pions. A twin baryon number asymmetry leads to a successful dark matter (DM) candidate: the spin-3/2 twin baryon, Δ^{'}∼b^{'}b^{'}b^{'}, with a dynamically determined mass (∼5Λ_{QCD}^{'}) in the preferred range for the DM-to-baryon ratio Ω_{DM}/Ω_{baryon}≃5. Gauging the U(1)^{'} group leads to twin atoms (Δ^{'}-τ^{'}[over ¯] bound states) that are successful ADM candidates in significant regions of parameter space, sometimes with observable changes to DM halo properties. Direct detection signatures satisfy current bounds, at times modified by dark form factors.
Asymptotically Free Natural Supersymmetric Twin Higgs Model
Badziak, Marcin; Harigaya, Keisuke
2018-05-01
Twin Higgs (TH) models explain the absence of new colored particles responsible for natural electroweak symmetry breaking (EWSB). All known ultraviolet completions of TH models require some nonperturbative dynamics below the Planck scale. We propose a supersymmetric model in which the TH mechanism is introduced by a new asymptotically free gauge interaction. The model features natural EWSB for squarks and gluino heavier than 2 TeV even if supersymmetry breaking is mediated around the Planck scale, and has interesting flavor phenomenology including the top quark decay into the Higgs boson and the up quark which may be discovered at the LHC.
Doubling down on naturalness with a supersymmetric twin Higgs
International Nuclear Information System (INIS)
Craig, Nathaniel; Howe, Kiel
2014-01-01
We show that naturalness of the weak scale can be comfortably reconciled with both LHC null results and observed Higgs properties provided the double protection of supersymmetry and the twin Higgs mechanism. This double protection radically alters conventional signs of naturalness at the LHC while respecting gauge coupling unification and precision electroweak limits. We find the measured Higgs mass, couplings, and percent-level naturalness of the weak scale are compatible with stops at ∼3.5 TeV and higgsinos at ∼1 TeV. The primary signs of naturalness in this scenario include modifications of Higgs couplings, a modest invisible Higgs width, resonant Higgs pair production, and an invisibly-decaying heavy Higgs
Doubling down on naturalness with a supersymmetric twin Higgs
Craig, Nathaniel; Howe, Kiel
2014-03-01
We show that naturalness of the weak scale can be comfortably reconciled with both LHC null results and observed Higgs properties provided the double protection of supersymmetry and the twin Higgs mechanism. This double protection radically alters conventional signs of naturalness at the LHC while respecting gauge coupling unification and precision electroweak limits. We find the measured Higgs mass, couplings, and percent-level naturalness of the weak scale are compatible with stops at ~ 3.5 TeV and higgsinos at ~ 1 TeV. The primary signs of naturalness in this scenario include modifications of Higgs couplings, a modest invisible Higgs width, resonant Higgs pair production, and an invisibly-decaying heavy Higgs.
Topological Higgs mechanism with ordinary Higgs mechanism
International Nuclear Information System (INIS)
Oda Ichiro; Yahikozawa Shigeaki.
1989-12-01
Topological Higgs mechanism in higher dimensions is analyzed when ordinary Higgs potential exists. It is shown that if one-form B-field becomes massive by the ordinary Higgs mechanism, another D-2 form C-field also becomes massive through topological term in addition to the topological mass generation by the topological Higgs mechanism. Moreover we investigate this mechanism in three dimensional theories, that is to say, Chern-Simons theory and more general theory. (author). 10 refs
Exotic quarks in Twin Higgs models
Energy Technology Data Exchange (ETDEWEB)
Cheng, Hsin-Chia [Department of Physics, University of California, Davis,One Shields Avenue, Davis, CA 95616 (United States); Jung, Sunghoon [School of Physics, Korea Institute for Advanced Study,85 Hoegiro, Dongdaemun-gu, Seoul 130-722 (Korea, Republic of); SLAC National Accelerator Laboratory,2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Salvioni, Ennio [Department of Physics, University of California, Davis,One Shields Avenue, Davis, CA 95616 (United States); Tsai, Yuhsin [Department of Physics, University of California, Davis,One Shields Avenue, Davis, CA 95616 (United States); Maryland Center for Fundamental Physics,Department of Physics, University of Maryland,College Park, MD 20742 (United States)
2016-03-14
The Twin Higgs model provides a natural theory for the electroweak symmetry breaking without the need of new particles carrying the standard model gauge charges below a few TeV. In the low energy theory, the only probe comes from the mixing of the Higgs fields in the standard model and twin sectors. However, an ultraviolet completion is required below ∼ 10 TeV to remove residual logarithmic divergences. In non-supersymmetric completions, new exotic fermions charged under both the standard model and twin gauge symmetries have to be present to accompany the top quark, thus providing a high energy probe of the model. Some of them carry standard model color, and may therefore be copiously produced at current or future hadron colliders. Once produced, these exotic quarks can decay into a top together with twin sector particles. If the twin sector particles escape the detection, we have the irreducible stop-like signals. On the other hand, some twin sector particles may decay back into the standard model particles with long lifetimes, giving spectacular displaced vertex signals in combination with the prompt top quarks. This happens in the Fraternal Twin Higgs scenario with typical parameters, and sometimes is even necessary for cosmological reasons. We study the potential displaced vertex signals from the decays of the twin bottomonia, twin glueballs, and twin leptons in the Fraternal Twin Higgs scenario. Depending on the details of the twin sector, the exotic quarks may be probed up to ∼ 2.5 TeV at the LHC and beyond 10 TeV at a future 100 TeV collider, providing a strong test of this class of ultraviolet completions.
A tale of twin Higgs: natural twin two Higgs doublet models
International Nuclear Information System (INIS)
Yu, Jiang-Hao
2016-01-01
In original twin Higgs model, vacuum misalignment between electroweak and new physics scales is realized by adding explicit ℤ 2 breaking term. Introducing additional twin Higgs could accommodate spontaneous ℤ 2 breaking, which explains origin of this misalignment. We introduce a class of twin two Higgs doublet models with most general scalar potential, and discuss general conditions which trigger electroweak and ℤ 2 symmetry breaking. Various scenarios on realising the vacuum misalignment are systematically discussed in a natural composite two Higgs double model framework: explicit ℤ 2 breaking, radiative ℤ 2 breaking, tadpole-induced ℤ 2 breaking, and quartic-induced ℤ 2 breaking. We investigate the Higgs mass spectra and Higgs phenomenology in these scenarios.
A tale of twin Higgs: natural twin two Higgs doublet models
Energy Technology Data Exchange (ETDEWEB)
Yu, Jiang-Hao [Amherst Center for Fundamental Interactions, Department of Physics,University of Massachusetts Amherst,710 North Pleasant St., Amherst, MA 01002 (United States)
2016-12-28
In original twin Higgs model, vacuum misalignment between electroweak and new physics scales is realized by adding explicit ℤ{sub 2} breaking term. Introducing additional twin Higgs could accommodate spontaneous ℤ{sub 2} breaking, which explains origin of this misalignment. We introduce a class of twin two Higgs doublet models with most general scalar potential, and discuss general conditions which trigger electroweak and ℤ{sub 2} symmetry breaking. Various scenarios on realising the vacuum misalignment are systematically discussed in a natural composite two Higgs double model framework: explicit ℤ{sub 2} breaking, radiative ℤ{sub 2} breaking, tadpole-induced ℤ{sub 2} breaking, and quartic-induced ℤ{sub 2} breaking. We investigate the Higgs mass spectra and Higgs phenomenology in these scenarios.
The spontaneous ℤ_2 breaking Twin Higgs
International Nuclear Information System (INIS)
Beauchesne, Hugues; Earl, Kevin; Grégoire, Thomas
2016-01-01
The Twin Higgs model seeks to address the little hierarchy problem by making the Higgs a pseudo-Goldstone of a global SU(4) symmetry that is spontaneously broken to SU(3). Gauge and Yukawa couplings, which explicitly break SU(4), enjoy a discrete ℤ_2 symmetry that accidentally maintains SU(4) at the quadratic level and therefore keeps the Higgs light. Contrary to most beyond the Standard Model theories, the quadratically divergent corrections to the Higgs mass are cancelled by a mirror sector, which is uncharged under the Standard Model groups. However, the Twin Higgs with an exact ℤ_2 symmetry leads to equal vevs in the Standard Model and mirror sectors, which is phenomenologically unviable. An explicit ℤ_2 breaking potential must then be introduced and tuned against the SU(4) breaking terms to produce a hierarchy of vevs between the two sectors. This leads to a moderate but non-negligible tuning. We propose a model to alleviate this tuning, without the need for an explicit ℤ_2 breaking sector. The model consists of two SU(4) fundamental Higgses, one whose vacuum preserves ℤ_2 and one whose vacuum breaks it. As the interactions between the two Higgses are turned on, the ℤ_2 breaking is transmitted from the broken to the unbroken sector and a small hierarchy of vevs is naturally produced. The presence of an effective tadpole and feedback between the two Higgses lead to a sizable improvement of the tuning. The resulting Higgs boson is naturally very Standard Model like.
Testing the scalar sector of the twin Higgs model at colliders
Chacko, Zackaria; Kilic, Can; Najjari, Saereh; Verhaaren, Christopher B.
2018-03-01
We consider mirror twin Higgs models in which the breaking of the global symmetry is realized linearly. In this scenario, the radial mode in the Higgs potential is present in the spectrum and constitutes a second portal between the twin and SM sectors. We show that a study of the properties of this particle at colliders, when combined with precision measurements of the light Higgs, can be used to overdetermine the form of the scalar potential, thereby confirming that it possesses an enhanced global symmetry as dictated by the twin Higgs mechanism. We find that, although the reach of the LHC for this state is limited, future linear colliders will be able to explore a significant part of the preferred parameter space, allowing the possibility of directly testing the twin Higgs framework.
Cosmology in Mirror Twin Higgs and neutrino masses
Chacko, Zackaria; Craig, Nathaniel; Fox, Patrick J.; Harnik, Roni
2017-07-01
We explore a simple solution to the cosmological challenges of the original Mirror Twin Higgs (MTH) model that leads to interesting implications for experiment. We consider theories in which both the standard model and mirror neutrinos acquire masses through the familiar seesaw mechanism, but with a low right-handed neutrino mass scale of order a few GeV. In these νMTH models, the right-handed neutrinos leave the thermal bath while still relativistic. As the universe expands, these particles eventually become nonrelativistic, and come to dominate the energy density of the universe before decaying. Decays to standard model states are preferred, with the result that the visible sector is left at a higher temperature than the twin sector. Consequently the contribution of the twin sector to the radiation density in the early universe is suppressed, allowing the current bounds on this scenario to be satisfied. However, the energy density in twin radiation remains large enough to be discovered in future cosmic microwave background experiments. In addition, the twin neutrinos are significantly heavier than their standard model counterparts, resulting in a sizable contribution to the overall mass density in neutrinos that can be detected in upcoming experiments designed to probe the large scale structure of the universe.
The RG-improved Twin Higgs effective potential at NNLL
Energy Technology Data Exchange (ETDEWEB)
Greco, Davide; Mimouni, Kin [Institut de Théorie des Phénomènes Physiques, EPFL,Route de la Sorge, Lausanne, CH-1015 (Switzerland)
2016-11-18
We present the Renormalization Group improvement of the Twin Higgs effective potential at cubic order in logarithmic accuracy. We first introduce a model-independent low-energy effective Lagrangian that captures both the pseudo-Nambu-Goldstone boson nature of the Higgs field and the twin light degrees of freedom charged under a copy of the Standard Model. We then apply the background field method to systematically re-sum all the one loop diagrams contributing to the potential. We show how this technique can be efficient to implicitly renormalize the higher-dimensional operators in the twin sector without classifying all of them. A prediction for the Higgs mass in the Twin Higgs model is derived and found to be of the order of M{sub H}∼120 GeV with an ultraviolet cut-off m{sub ∗}∼10–20 TeV. Irrespective of any possible ultraviolet completion of the low-energy Lagrangian, the infrared degrees of freedom alone are therefore enough to account for the observed value of the Higgs mass through running effects.
Precision tests and fine tuning in twin Higgs models
Contino, Roberto; Greco, Davide; Mahbubani, Rakhi; Rattazzi, Riccardo; Torre, Riccardo
2017-11-01
We analyze the parametric structure of twin Higgs (TH) theories and assess the gain in fine tuning which they enable compared to extensions of the standard model with colored top partners. Estimates show that, at least in the simplest realizations of the TH idea, the separation between the mass of new colored particles and the electroweak scale is controlled by the coupling strength of the underlying UV theory, and that a parametric gain is achieved only for strongly-coupled dynamics. Motivated by this consideration we focus on one of these simple realizations, namely composite TH theories, and study how well such constructions can reproduce electroweak precision data. The most important effect of the twin states is found to be the infrared contribution to the Higgs quartic coupling, while direct corrections to electroweak observables are subleading and negligible. We perform a careful fit to the electroweak data including the leading-logarithmic corrections to the Higgs quartic up to three loops. Our analysis shows that agreement with electroweak precision tests can be achieved with only a moderate amount of tuning, in the range 5%-10%, in theories where colored states have mass of order 3-5 TeV and are thus out of reach of the LHC. For these levels of tuning, larger masses are excluded by a perturbativity bound, which makes these theories possibly discoverable, hence falsifiable, at a future 100 TeV collider.
International Nuclear Information System (INIS)
Yao-Bei, Liu; Hong-Mei, Han; Xue-Lei, Wang
2008-01-01
The Higgs-strahlung process e + e - → ZH and the double Higgs-strahlung process e + e - → ZHH are very important for studying Higgs boson properties and the Higgs self-coupling in the high-energy e + e - collider (ILC). We calculate the contributions of the left-right twin Higgs (LRTH) model to these processes and find that, in the favorable parameter spaces, the LRTH model can generate significant corrections to the production cross-section of these processes. We expect that the possible signals of the LRTH model can be detected via these processes in the future ILC experiments. (authors)
Effective theory of flavor for Minimal Mirror Twin Higgs
Barbieri, Riccardo; Hall, Lawrence J.; Harigaya, Keisuke
2017-10-01
We consider two copies of the Standard Model, interchanged by an exact parity symmetry, P. The observed fermion mass hierarchy is described by suppression factors ɛ^{n_i} for charged fermion i, as can arise in Froggatt-Nielsen and extra-dimensional theories of flavor. The corresponding flavor factors in the mirror sector are ɛ^' {n}_i} , so that spontaneous breaking of the parity P arises from a single parameter ɛ'/ɛ, yielding a tightly constrained version of Minimal Mirror Twin Higgs, introduced in our previous paper. Models are studied for simple values of n i , including in particular one with SU(5)-compatibility, that describe the observed fermion mass hierarchy. The entire mirror quark and charged lepton spectrum is broadly predicted in terms of ɛ'/ɛ, as are the mirror QCD scale and the decoupling temperature between the two sectors. Helium-, hydrogen- and neutron-like mirror dark matter candidates are constrained by self-scattering and relic ionization. In each case, the allowed parameter space can be fully probed by proposed direct detection experiments. Correlated predictions are made as well for the Higgs signal strength and the amount of dark radiation.
A Philosophical Look at the Higgs Mechanism
Friederich, Simon
2014-01-01
On the occasion of the recent experimental detection of a Higgs-type particle at the Large Hadron Collider at CERN, the paper reviews philosophical aspects of the Higgs mechanism as the presently preferred account of the generation of particle masses in the Standard Model of elementary particle
Unveiling the Higgs mechanism to students
International Nuclear Information System (INIS)
Organtini, Giovanni
2012-01-01
In this paper we outline a lecture given to undergraduate students to explain why physicists are so interested in the Higgs boson. The lecture was conceived for students not yet familiar with advanced physics and is suitable for those studying several other disciplines. The Higgs mechanism is introduced through semi-classical arguments mimicking basic field-theory concepts, assuming the validity of a symmetry principle in the expression of the energy of particles in a classical field. The lecture is divided into two parts. The first, suitable even for high-school students, shows how the mass of a particle results from a dynamical effect caused by interaction between a massless particle and a field (as in the Higgs mechanism). The audience for the second, much more technical part consists mainly of teachers and university students from disciplines other than physics. (paper)
Turning on gravity with the Higgs mechanism
International Nuclear Information System (INIS)
Alexander, Stephon; Barrow, John D; Magueijo, João
2016-01-01
We investigate how a Higgs mechanism could be responsible for the emergence of gravity in extensions of Einstein theory, with a suitable low energy limit. In this scenario, at high energies, symmetry restoration could ‘turn off’ gravity, with dramatic implications for cosmology and quantum gravity. The sense in which gravity is muted depends on the details of the implementation. In the most extreme case gravity’s dynamical degrees of freedom would only be unleashed after the Higgs field acquires a non-trivial vacuum expectation value, with gravity reduced to a topological field theory in the symmetric phase. We might also identify the Higgs and the Brans–Dicke fields in such a way that in the unbroken phase Newton’s constant vanishes, decoupling matter and gravity. We discuss the broad implications of these scenarios. (letter)
Gauge field copies and Higgs mechanism
International Nuclear Information System (INIS)
Gleiser, M.
1982-07-01
From the algebric classification of the possible solutions of the necessary and sufficient condition for the existence of gauge field copies in two possible classes the Higgs mechanism for the potential obtained from the difference between two copied potentials is applied. It is shown that for class I 'electric type' it is possible to construct a vector field that satisfies an electromagnetic wave equation. For class I 'magnetic type', a vector field that satisfies a non-linear equation as a consequence of the non-abelianity of the theory, is obtained. It is shown that for class II it's not possible to apply the Higgs mechanism. A possible physical interpretation for the 'gauge field copies' phenomenon, is obtained. (author) [pt
Remarks on Higgs mechanism for gravitons
International Nuclear Information System (INIS)
Oda, Ichiro
2010-01-01
We construct two kinds of model exhibiting Higgs mechanism for gravitons in potentials of scalar fields. One class of the model is based on a potential which is a generic function of the induced internal metric H AB , and the other involves a potential which is a generic function of the usual metric tensor g μν and the induced curved metric Y μν . In the both models, we derive conditions on the scalar potential in such a way that gravitons acquire mass in a flat Minkowski space-time without non-unitary propagating modes in the process of spontaneous symmetry breaking of diffeomorphisms through the condensation of scalar fields. We solve the conditions and find a general solution for the potential. As an interesting specific solution, we present a simple potential for which the Higgs mechanism for gravitons holds in any value of cosmological constant.
Single top partner production at lepton colliders in the left-right twin Higgs model
Jiang, Xingyu; Han, Jinzhong; Hou, Biaofeng; Yu, Chunxu
2018-04-01
In the framework of the left-right twin Higgs (LRTH) model, we investigate the single top partner production at lepton colliders. We calculate the production cross-sections of the processes e‑γ → ν ebT¯, e‑e+ → W‑b¯T (W+bT¯) and γγ → W‑b¯T (W+bT¯) at s = 2.0 TeV, and display some typical differential distributions of the final state particles.
Lepton number violating signals of the top quark partners in the left-right twin Higgs model
International Nuclear Information System (INIS)
Goh, Hock-Seng; Krenke, Christopher A.
2010-01-01
We study the collider signatures of the left-right twin Higgs model in the case that the right-handed neutrino mass is less than the mass of the right-handed gauge boson. In this scenario, new leptonic decay chains open up, allowing the particles which cancel the one-loop quadratic divergences of the Higgs, the right-handed gauge bosons and top-partners, to be discovered. Half of these events contain same-sign leptons without missing energy, which have no genuine standard model background and for which the backgrounds are purely instrumental. These signals may be used to complement other collider searches and, in certain regions of parameter space, may be the only way to observe the particles responsible for natural electroweak symmetry breaking in the left-right twin Higgs model.
Higgs bosons and other mechanisms of mass generation
International Nuclear Information System (INIS)
Konopleva, N. P.
1997-01-01
There are two problems under discuss here: 1) are Higgs bosons really necessary for the gauge field mass generation or not, and 2) why are Higgs bosons invisible in the elementary particles experiments? It is shown that in the frame of the classical Lagrangian gauge fields theory the transition from the usual variational problem to isoperimetric one permits us to conserve the local gauge invariance on the solutions of the massive gauge field theory equations. Hence in the massive gauge field theory we can have on the field equation solutions not only the conservation laws corresponding with the first Noether's theorem but Noether's identities corresponding with the second Noether's theorem also. Therefore the alternative renormalization procedure can exist which does not demand of Higgs bosons appearance in the massive gauge field theory for its renormalizability. The interpretation of Higgs mechanism as the phase transition mechanism is discussed. From this point of view the inexplicable absence of the individual Higgs bosons could be the result of the fact that the massive gauge field is the complex system of the massless gauge fields interacting with the condensate of Higgs bosons and quantum vortices in it. In this case the gauge field obtains the mass when the phase transition happens and after that the individual Higgs bosons can not be eliminated from the complex system
Higgs boson production and decay at e+e− colliders as a probe of the Left–Right twin Higgs model
Directory of Open Access Journals (Sweden)
Jinzhong Han
2015-07-01
Full Text Available In the framework of the Left–Right twin Higgs (LRTH model, we consider the constrains from the latest search for high-mass dilepton resonances at the LHC and find that the heavy neutral boson ZH is excluded with mass below 2.76 TeV. Under these constrains, we study the Higgs–Gauge coupling production processes e+e−→ZH, e+e−→νeνe¯H and e+e−→e+e−H, top quark Yukawa coupling production process e+e−→tt¯H, Higgs self-couplings production processes e+e−→ZHH and e+e−→νeνe¯HH at e+e− colliders. Besides, we study the major decay modes of the Higgs boson, namely h→ff¯(f=b,c,τ, VV⁎(V=W,Z, gg, γγ. We find that the LRTH effects are sizable so that the Higgs boson processes at e+e− collider can be a sensitive probe for the LRTH model.
Abelian Higgs mechanism in the Schroedinger picture
International Nuclear Information System (INIS)
Kim, S.K.; Namgung, W.; Soh, K.S.; Yee, J.H.
1990-01-01
We have studied symmetry-breaking phenomena in scalar electrodynamics by evaluating the effective potential at one-loop order in the Schroedinger picture. Contributions to the effective potential by the Higgs particle and the transverse and longitudinal components of a photon are compared with other previous works, and they are found to be consistent
Conformal (WEYL) invariance and Higgs mechanism
International Nuclear Information System (INIS)
Zhao Shucheng.
1991-10-01
A massive Yang-Mills field theory with conformal invariance and gauge invariance is proposed. It involves gravitational and various gauge interactions, in which all the mass terms appear as a uniform form of interaction m(x) KΦ(x). When the conformal symmetry is broken spontaneously and gravitation is ignored, the Higgs field emerges naturally, where the imaginary mass μ can be described as a background curvature. (author). 7 refs
The Higgs mechanism and the origin of mass
Djouadi, Abdelhak
2012-06-01
The Higgs mechanism plays a key role in the physics of elementary particles: in the context of the Standard Model, the theory which describes in a unified framework the electromagnetic, weak and strong nuclear interactions, it allows for the generation of particle masses while preserving the fundamental symmetries of the theory. This mechanism predicts the existence of a new type of particle, the scalar Higgs boson, with unique characteristics. The detection of this particle and the study of its fundamental properties is a major goal of high-energy particle colliders, such as the CERN Large Hadron Collider or LHC.
Higgs mechanism and the added-mass effect.
Krishnaswami, Govind S; Phatak, Sachin S
2015-04-08
In the Higgs mechanism, mediators of the weak force acquire masses by interacting with the Higgs condensate, leading to a vector boson mass matrix. On the other hand, a rigid body accelerated through an inviscid, incompressible and irrotational fluid feels an opposing force linearly related to its acceleration, via an added-mass tensor. We uncover a striking physical analogy between the two effects and propose a dictionary relating them. The correspondence turns the gauge Lie algebra into the space of directions in which the body can move, encodes the pattern of gauge symmetry breaking in the shape of an associated body and relates symmetries of the body to those of the scalar vacuum manifold. The new viewpoint is illustrated with numerous examples, and raises interesting questions, notably on the fluid analogues of the broken symmetry and Higgs particle, and the field-theoretic analogue of the added mass of a composite body.
The Higgs mechanism in a covariant-gauge formalism
International Nuclear Information System (INIS)
Yokoyama, Kan-ichi; Kubo, Reijiro.
1975-02-01
In a covariant-gauge formalism for gauge fields the Higgs mechanism is investigated under a spontaneous breakdown of gauge invariance. It is shown that the Goldstone bosons are in general described by a dipole-ghost field and can be consistently eliminated from the physical state-vector space by supplementary conditions. By an asymptotic condition for the relevant fields, field equations and commutators of asymptotic fields are determined. A renormalization problem and an aspect concerning gauge transformations are also discussed. (auth.)
Dynamic Analysis of Hammer Mechanism "Twin Hammer" of Impact Wrench
Konečný, M.; Slavík, J.
This paper describes function of the hammer mechanism "Twin hammer" the impact wrench, calculation of dynamic forces exerted on the mechanism and determining the contact pressures between the parts of the mechanism. The modelling of parts was performed in system Pro ENGINEER—standard. The simulation and finding dynamic forces was performed in advanced module Pro ENGINEER—mechanism design and finding contacts pressures in modul Pro ENGENEER—mechanica.
Constructing neutron stars with a gravitational Higgs mechanism
Franchini, Nicola; Coates, Andrew; Sotiriou, Thomas P.
2018-03-01
In scalar-tensor theories, spontaneous scalarization is a phase transition that can occur in ultradense environments such as neutron stars. The scalar field develops a nontrivial configuration once the stars exceeds a compactness threshold. We recently pointed out that, if the scalar exhibits some additional coupling to matter, it could give rise to significantly different microphysics in these environments. In this work we study, at the nonperturbative level, a toy model in which the photon is given a large mass when spontaneous scalarization occurs. Our results demonstrate clearly the effectiveness of spontaneous scalarization as a Higgs-like mechanism in neutron stars.
Symmetry realization via a dynamical inverse Higgs mechanism
Rothstein, Ira Z.; Shrivastava, Prashant
2018-05-01
The Ward identities associated with spontaneously broken symmetries can be saturated by Goldstone bosons. However, when space-time symmetries are broken, the number of Goldstone bosons necessary to non-linearly realize the symmetry can be less than the number of broken generators. The loss of Goldstones may be due to a redundancy or the generation of a gap. In either case the associated Goldstone may be removed from the spectrum. This phenomena is called an Inverse Higgs Mechanism (IHM) and its appearance has a well defined mathematical condition. However, there are cases when a Goldstone boson associated with a broken generator does not appear in the low energy theory despite the lack of the existence of an associated IHM. In this paper we will show that in such cases the relevant broken symmetry can be realized, without the aid of an associated Goldstone, if there exists a proper set of operator constraints, which we call a Dynamical Inverse Higgs Mechanism (DIHM). We consider the spontaneous breaking of boosts, rotations and conformal transformations in the context of Fermi liquids, finding three possible paths to symmetry realization: pure Goldstones, no Goldstones and DIHM, or some mixture thereof. We show that in the two dimensional degenerate electron system the DIHM route is the only consistent way to realize spontaneously broken boosts and dilatations, while in three dimensions these symmetries could just as well be realized via the inclusion of non-derivatively coupled Goldstone bosons. We present the action, including the leading order non-linearities, for the rotational Goldstone (angulon), and discuss the constraint associated with the possible DIHM that would need to be imposed to remove it from the spectrum. Finally we discuss the conditions under which Goldstone bosons are non-derivatively coupled, a necessary condition for the existence of a Dynamical Inverse Higgs Constraint (DIHC), generalizing the results for Vishwanath and Wantanabe.
Higgs seesaw mechanism as a source for dark energy.
Krauss, Lawrence M; Dent, James B
2013-08-09
Motivated by the seesaw mechanism for neutrinos which naturally generates small neutrino masses, we explore how a small grand-unified-theory-scale mixing between the standard model Higgs boson and an otherwise massless hidden sector scalar can naturally generate a small mass and vacuum expectation value for the new scalar which produces a false vacuum energy density contribution comparable to that of the observed dark energy dominating the current expansion of the Universe. This provides a simple and natural mechanism for producing the correct scale for dark energy, even if it does not address the long-standing question of why much larger dark energy contributions are not produced from the visible sector. The new scalar produces no discernible signatures in existing terrestrial experiments so that one may have to rely on other cosmological tests of this idea.
A non-perturbative argument for the non-abelian Higgs mechanism
Energy Technology Data Exchange (ETDEWEB)
De Palma, G. [Scuola Normale Superiore, Pisa (Italy); INFN, Sezione di Pisa, Pisa (Italy); Strocchi, F., E-mail: franco.strocchi@sns.it [INFN, Sezione di Pisa, Pisa (Italy)
2013-09-15
The evasion of massless Goldstone bosons by the non-abelian Higgs mechanism is proved by a non-perturbative argument in the local BRST gauge. -- Highlights: •The perturbative explanation of the Higgs mechanism (HM) is not under mathematical control. •We offer a non-perturbative proof of the absence of Goldstone bosons from the non-abelian HM. •Our non-perturbative proof in the BRST gauge avoids a mean field ansatz and expansion.
A non-perturbative argument for the non-abelian Higgs mechanism
International Nuclear Information System (INIS)
De Palma, G.; Strocchi, F.
2013-01-01
The evasion of massless Goldstone bosons by the non-abelian Higgs mechanism is proved by a non-perturbative argument in the local BRST gauge. -- Highlights: •The perturbative explanation of the Higgs mechanism (HM) is not under mathematical control. •We offer a non-perturbative proof of the absence of Goldstone bosons from the non-abelian HM. •Our non-perturbative proof in the BRST gauge avoids a mean field ansatz and expansion
Dynamical symmetry breaking as an alternative for Higg's mechanics
International Nuclear Information System (INIS)
Shellard, R.C.
1979-01-01
The effective action of a theory where dynamical symmetry breaking occurs is expanded in terms of loops, producing a Ginzburg-Landau-like Lagrangian reproducing fenomenologically the Higg's potencial. (L.C.) [pt
Lorentz-violating alternative to the Higgs mechanism?
International Nuclear Information System (INIS)
Alexandre, Jean; Mavromatos, Nick E.
2011-01-01
We consider a four-dimensional field-theory model with two massless fermions, coupled to an Abelian vector field without flavor mixing, and to another Abelian vector field with flavor mixing. Both Abelian vectors have a Lorentz-violating kinetic term, introducing a Lorentz-violation mass scale M, from which fermions and the flavor-mixing vector get their dynamical masses, whereas the vector coupled without flavor mixing remains massless. When the two coupling constants have similar values in order of magnitude, a mass hierarchy pattern emerges, in which one fermion is very light compared to the other, while the vector mass is of the order of the heavy fermion mass. The work presented here may be considered as a Lorentz-symmetry-violating alternative to the Higgs mechanism, in the sense that no scalar particle (fundamental or composite) is necessary for the generation of the vector-meson mass. However, the model is not realistic given that, as a result of Lorentz violation, the maximal (light-cone) speed seen by the fermions is smaller than that of the massless gauge boson (which equals the speed of light in vacuo) by an amount which is unacceptably large to be compatible with the current tests of Lorentz invariance, unless the gauge couplings assume unnaturally small values. Possible ways out of this phenomenological drawback are briefly discussed, postponing a detailed construction of more realistic models for future work.
Higgs mechanism in light-front quantized field theory
Energy Technology Data Exchange (ETDEWEB)
Srivastava, P P
1993-12-31
The spontaneous symmetry breaking of continuous symmetry in light-front quantized scalar field theory is studied following the standard Dirac procedure for constrained dynamical systems. A non-local constraint is found to follow. The values of the constant backgrounds fields (zero modes) at the tree level, as a consequence, are shown to given by minimizing the light-front energy. The zero modes are shown to commute with the non-zero ones and the isovector built from them is seen to characterize a (non-perturbative) vacuum state and the corresponding physical sector. The infinite degeneracy of the vacuum is described by the continuum of the allowed orientations of this background isovector in the isospin space. The symmetry generators in the quantized field theory annihilate the vacuum is contrast to the case of equal-time quantization. Not all of them are conserved and the conserved ones determine the surviving symmetry of the quantum theory Lagrangian. The criteria for determining the background isovector and the counting of the number of Goldstone bosons goes as in the equal-time case. A demonstration in favour of the absence of Goldstone bosons in two dimensions is also found. Finally, is extended to an understanding of the Higgs mechanism in light-front frame. (author). 13 refs.
A Lorentz-Violating Alternative to Higgs Mechanism?
Alexandre, Jean
2011-01-01
We consider a four-dimensional field-theory model with two massless fermions, coupled to an Abelian vector field without flavour mixing, and to another Abelian vector field with flavour mixing. Both Abelian vectors have a Lorentz-violating kinetic term, introducing a Lorentz-violation mass scale $M$, from which fermions and the flavour-mixing vector get their dynamical masses, whereas the vector coupled without flavour mixing remains massless. When the two coupling constants have similar values in order of magnitude, a mass hierarchy pattern emerges, in which one fermion is very light compared to the other, whilst the vector mass is larger than the mass of the heavy fermion. The work presented here may be considered as a Lorentz-symmetry-Violating alternative to the Higgs mechanism, in the sense that no scalar particle (fundamental or composite) is necessary for the generation of the vector-meson mass. However, the model is not realistic given that, as a result of Lorentz Violation, the maximal (light-cone) s...
Higgs mechanism in light-front quantized field theory
International Nuclear Information System (INIS)
Srivastava, P.P.
1992-01-01
The spontaneous symmetry breaking of continuous symmetry in light-front quantized scalar field theory is studied following the standard Dirac procedure for constrained dynamical systems. A non-local constraint is found to follow. The values of the constant backgrounds fields (zero modes) at the tree level, as a consequence, are shown to given by minimizing the light-front energy. The zero modes are shown to commute with the non-zero ones and the isovector built from them is seen to characterize a (non-perturbative) vacuum state and the corresponding physical sector. The infinite degeneracy of the vacuum is described by the continuum of the allowed orientations of this background isovector in the isospin space. The symmetry generators in the quantized field theory annihilate the vacuum is contrast to the case of equal-time quantization. Not all of them are conserved and the conserved ones determine the surviving symmetry of the quantum theory Lagrangian. The criteria for determining the background isovector and the counting of the number of Goldstone bosons goes as in the equal-time case. A demonstration in favour of the absence of Goldstone bosons in two dimensions is also found. Finally, is extended to an understanding of the Higgs mechanism in light-front frame. (author). 13 refs
Phenomenology of Higgs particles
International Nuclear Information System (INIS)
Jarlskog, C.; Stockholm Univ.
1985-01-01
These lecture notes are organized as follows: 1. Introduction, 2. Interactions and decay modes of the Standard Higgs phisub(O), 3. Nonstandard Higgs multiplets, 4. Upper limits on the Higgs mass, 5. Lower limits on the Higgs mass, 6. Production mechanisms for the Standard Higgs, 7. Outlook. (orig.)
Lightest Higgs boson mass in split supersymmetry with the seesaw mechanism
International Nuclear Information System (INIS)
Cao Junjie; Yang Jinmin
2005-01-01
In the minimal supersymmetric standard model extended by including right-handed neutrinos with seesaw mechanism, the neutrino Yukaka couplings can be as large as the top-quark Yukawa couplings and thus the neutrino/sneutrino may cause sizable effects in Higgs boson self-energy loops. Our explicit one-loop calculations show that the neutrino/sneutrino effects may have an opposite sign to top/stop effects and thus lighten the lightest Higgs boson. If the soft-breaking mass of the right-handed neutrino is very large (at the order of Majorana mass scale), such as in the split-supersymmetry (SUSY) scenario, the effects can lower the lightest Higgs boson mass by a few tens of GeV. So the Higgs mass bound of about 150 GeV in split-SUSY may be lowered significantly if right-handed neutrinos come into play with seesaw mechanism
Spontaneous symmetry breaking in local gauge quantum field theory; the Higgs mechanism
International Nuclear Information System (INIS)
Strocchi, F.
1977-01-01
Spontaneous symmetry breakings in indefinite metric quantum field theories are analyzed and a generalization of the Goldstone theorem is proved. The case of local gauge quantum field theories is discussed in detail and a characterization is given of the occurrence of the Higgs mechanism versus the Goldstone mechanism. The Higgs phenomenon is explained on general grounds without the introduction of the so-called Higgs fields. The basic property is the relation between the local internal symmetry group and the local group of gauge transformations of the second kind. Spontaneous symmetry breaking of c-number gauge transformations of the second kind is shown to always occur if there are charged local fields. The implications about the absence of mass gap in the Wightman functions and the occurrence of massless particles associated with the unbroken generators in the Higgs phenomenon are discussed. (orig.) [de
Detwinning mechanisms for growth twins in face-centered cubic metals
Energy Technology Data Exchange (ETDEWEB)
Wang, J., E-mail: wangj6@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Li, N.; Anderoglu, O. [Department of Mechanical Engineering, Materials Science and Engineering Program, Texas A and M University, College Station, TX 77843-3123 (United States); Zhang, X., E-mail: zhangx@tamu.edu [Department of Mechanical Engineering, Materials Science and Engineering Program, Texas A and M University, College Station, TX 77843-3123 (United States); Misra, A. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Huang, J.Y. [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Hirth, J.P. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2010-04-15
Using in situ transmission electron microscopy, we studied the stability of growth twins. We observed the rapid migration of incoherent twin boundaries (ITBs), indicating that nanotwins are unstable. Topological analysis and atomistic simulations are adopted to explore detwinning mechanisms. The results show that: (i) the detwinning process is accomplished via the collective glide of multiple twinning dislocations that form an ITB; (ii) detwinning can easily occur for thin twins, and the driving force is mainly attributed to a variation of the excess energy of a coherent twin boundary; (iii) shear stresses enable ITBs to migrate easily, causing the motion of coherent twin boundaries; and (iv) the migration velocity depends on stacking fault energy. The results imply that detwinning becomes the dominant deformation mechanism for growth twins of the order of a few nanometers thick.
International Nuclear Information System (INIS)
Yang, Z.Q.; Chisholm, M.F.; He, L.L.; Pennycook, S.J.; Ye, H.Q.
2012-01-01
We report experimental investigations on interactions/reactions between dislocations and twin boundaries in Al. The absorption of screw dislocations via cross-slip and the production of stair-rods via reactions with non-screw dislocations were verified by atomic resolution imaging. Importantly, the resulting partial dislocations moving along twin boundaries can produce secondary sessile defects. These immobile defects act as obstacles to other dislocations and also serve to pin the twin boundaries. These findings show the atomic-level dynamics of the dislocation–twin boundary processes and the unique strengthening mechanism of twin boundaries in face-centered cubic metals.
Particle currents on a CP violating Higgs background and the spontaneous baryogenesis mechanism
International Nuclear Information System (INIS)
Comelli, D.; Riotto, A.
1995-04-01
We compute the particle currents induced on a bubble wall background at finite temperature in a model with CP violation in the Higgs sector. Using a field theory approach we show that fermionic currents arise at one loop, so that a suppression factor OMIKRON (h t φ/πT) 2 with respect to previous computations is found. The contributions to the Higgs currents are also derived and their relevancy for the spontaneous baryogenesis mechanism is discussed. (orig.)
Intrinsically aligned chemo-mechanical functionalization of twin cantilever structures
International Nuclear Information System (INIS)
Toffoli, V; Esch, F; Melli, M; Pozzato, A; Tormen, M; Lazzarino, M; Cataruzza, F; Carrato, S; Scoles, G
2008-01-01
Mechanical oscillators became a main focus of research in recent years for potential applications in biomolecule detectors. We recently demonstrated the feasibility of a scheme based on twin cantilevers with a sensitivity down to the single molecule. This approach is extremely promising under the condition that the two terminals of the device can be functionalized with high selectivity and nanometric accuracy by linker molecules. Here we demonstrate a chemo-mechanical method to achieve the intrinsically aligned functionalization of two silicon surfaces, which can be separated by a gap controllable with nanometric precision. The chemical binding of the target molecules in the selected position is obtained through a cycloaddition reaction which exploits the reactivity of the freshly cleaved surfaces that form when the cantilever gap is created. The general validity of this approach is shown by the use in different chemical environments of two compounds with different reactive functional groups.
Liu, L.; Wang, J.; Gong, S. K.; Mao, S. X.
2011-04-01
We have observed a new deformation-twinning mechanism using the high resolution transmission electron microscope in polycrystalline Ag films, zero-strain twinning via nucleation, and the migration of a Σ3{112} incoherent twin boundary (ITB). This twinning mechanism produces a near zero macroscopic strain because the net Burgers vectors either equal zero or are equivalent to a Shockley partial dislocation. This observation provides new insight into the understanding of deformation twinning and confirms a previous hypothesis: detwinning could be accomplished via the nucleation and migration of Σ3{112} ITBs. The zero-strain twinning mechanism may be unique to low staking fault energy metals with implications for their deformation behavior.
Shterner, Vadim; Timokhina, Ilana B.; Rollett, Anthony D.; Beladi, Hossein
2018-04-01
In the current study, the dependence of mechanical twinning on grain orientation and grain boundary characteristics was investigated using quasi in-situ tensile testing. The grains of three main orientations (i.e., , , and parallel to the tensile axis (TA)) and certain characteristics of grain boundaries (i.e., the misorientation angle and the inclination angle between the grain boundary plane normal and the TA) were examined. Among the different orientations, and were the most and the least favored orientations for the formation of mechanical twins, respectively. The orientation was intermediate for twinning. The annealing twin boundaries appeared to be the most favorable grain boundaries for the nucleation of mechanical twinning. No dependence was found for the inclination angle of annealing twin boundaries, but the orientation of grains on either side of the annealing twin boundary exhibited a pronounced effect on the propensity for mechanical twinning. Annealing twin boundaries adjacent to high Taylor factor grains exhibited a pronounced tendency for twinning regardless of their inclination angle. In general, grain orientation has a significant influence on twinning on a specific grain boundary.
Particle masses without the Higgs mechanism and supersymmetry
International Nuclear Information System (INIS)
Winterberg, F
2012-01-01
The non-observation of the Higgs boson and supersymmetry in the most recent high-energy physics data suggests considering the conjectured Planck mass plasma as a potential alternative. In it supersymmetry is replaced by the assumption that the vacuum of space is densely filled in equal numbers with positive and negative Planck mass particles, and the Higgs field by the gravitational field of interacting large positive with likewise large negative mass quasiparticles of the Planck mass plasma, giving these positive-negative mass configurations a small positive gravitational field mass. From this configuration the Dirac equation can be derived, with the fermions of the standard model composed of large positive and negative masses. (paper)
International Nuclear Information System (INIS)
Guo Zhanying; Yang Guang; Yang Bingfang
2013-01-01
The left-right twin Higgs model contains a new vector-like heavy top quark, which mixes with the SM-like top quark. In this work, we studied the single vector-like top partner production via process e - γ → νeT-barb at the International Linear Collider. We calculated the production cross section at tree level and displayed the relevant differential distributions. The result shows that there will be 125 events produced each year with √s=2 TeV and the integrated luminosity Script Lint ≈ 500 fb -1 , and the b-quark tagging and the relevant missing energy cut will be helpful to detect this new effect. (authors)
The standard model as a low-energy effective theory. What is triggering the Higgs mechanism?
Energy Technology Data Exchange (ETDEWEB)
Jegerlehner, Fred [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Humboldt Univ., Berlin (Germany). Inst. fuer Physik
2013-04-15
The discovery of the Higgs by ATLAS and CMS at the LHC not only provided the last missing building block of the electroweak Standard Model, the mass of the Higgs has been found to have a very peculiar value about 125 GeV, which is such that vacuum stability is extending up to the Planck scale. This may have much deeper drawback than anticipated so far. The impact on the running of the SM gauge, Yukawa and Higgs couplings up to the Planck scale has been discussed in several articles recently. Here we consider the impact on the running masses and we discuss the role of quadratic divergences within the Standard Model. The change of sign of the coefficient of the quadratically divergent terms showing up at about {mu}{sub 0}{proportional_to}7 x 10{sup 16} GeV may be understood as a first order phase transition restoring the symmetric phase, while its large negative values at lower scales triggers the Higgs mechanism, running parameters evolve in such a way that the symmetry is restored two orders of magnitude before the Planck scale. Thus, the electroweak phase transition takes place at the scale {mu}{sub 0} and not at the electroweak scale {upsilon}{proportional_to}250 GeV. The SM Higgs system and its phase transition could play a key role for the inflation of the early universe. Also baryogenesis has to be reconsidered under the aspect that perturbative arguments surprisingly work up to the Planck scale.
The Born-Infeld vortices induced from a generalized Higgs mechanism.
Han, Xiaosen
2016-04-01
We construct self-dual Born-Infeld vortices induced from a generalized Higgs mechanism. Two specific models of the theory are of focused interest where the Higgs potential is either of a | ϕ | 4 - or | ϕ | 6 -type. For the | ϕ | 4 -model, we obtain a sharp existence and uniqueness theorem for doubly periodic and planar vortices. For doubly periodic solutions, a necessary and sufficient condition for the existence is explicitly derived in terms of the vortex number, the Born-Infeld parameter, and the size of the periodic lattice domain. For the | ϕ | 6 -model, we show that both topological and non-topological vortices are present. This new phenomenon distinguishes the model from the classical Born-Infeld-Higgs theory studied earlier in the literature. A series of results regarding doubly periodic, topological, and non-topological vortices in the | ϕ | 6 -model are also established.
On the mechanism of twin formation in Fe-Mn-C TWIP steels
International Nuclear Information System (INIS)
Idrissi, H.; Renard, K.; Ryelandt, L.; Schryvers, D.; Jacques, P.J.
2010-01-01
Although it is well known that Fe-Mn-C TWIP steels exhibit high work-hardening rates, the elementary twinning mechanisms controlling the plastic deformation of these steels have still not been characterized. The aim of the present study is to analyse the extended defects related to the twinning occurrence using transmission electron microscopy. Based on these observations, the very early stage of twin nucleation can be attributed to the pole mechanism with deviation proposed by Cohen and Weertman or to the model of Miura, Takamura and Narita, while the twin growth is controlled by the pole mechanism proposed by Venables. High densities of sessile Frank dislocations are observed within the twins at the early stage of deformation, which can affect the growth and the stability of the twins, but also the strength of these twins and their interactions with the gliding dislocations present in the matrix. This experimental evidence is discussed and compared to recent results in order to relate the defects analysis to the macroscopic behaviour of this category of material.
Mechanical twinning and texture evolution in severely deformed Ti-6Al-4V at high temperatures
International Nuclear Information System (INIS)
Yapici, Guney Guven; Karaman, Ibrahim; Luo Zhiping
2006-01-01
We have investigated the deformation behavior and texture evolution of two-phase Ti-6Al-4V subjected to severe plastic deformation using equal channel angular extrusion (ECAE) at a high temperature (∼0.55T m ). Significant deformation twinning activity was observed after one and two ECAE passes in a 90 deg, die at 800 deg. C. Twinning activity at such a high temperature is a first-time observation in this material and is attributed to the high strain and stress levels imposed during ECAE. High stress levels and the stress state can affect the separation of twinning partials considerably. Resolved shear stress magnitudes on twin partials were found to be high during the ECAE process that helps the nucleation of mechanical twinning. The twinning mode was identified as the {101-bar 1} type using electron diffraction patterns which is one of the twinning modes observed in Ti at temperatures above 350 deg. C. Although only one twinning variant was mainly evident after one pass, multiple twin variants of the same mode were observed after the second pass with a significant increase in twin volume fraction. ECAE processing aligned the basal planes of the hexagonal close-packed α phase, initially having a random texture, with the ECAE shear plane. Texture evolution during ECAE was successfully predicted using a viscoplastic self-consistent crystal plasticity framework capturing the effect of the observed twinning mode on texture. Mechanical twins formed during ECAE and grain refinement led to a noteworthy improvement in flow stresses under tension and compression at room temperature. A strong directional anisotropy in yield strengths was also evident which cannot be explained only by crystallographic texture. It was speculated that the asymmetry of critical resolved shear stresses of deformation modes and the processing-induced deformation structure should play a role. With the supporting evidence from our previous works on the severe plastic deformation of other
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.
International Nuclear Information System (INIS)
Ito, K.R.
1975-01-01
The Schwinger model is considered in the Landau-gauge formalism of quantum electrodynamics. This model can be solved exactly on the assumption of no radiative corrections to the anomaly. It is found that the photon obtains a non-zero mass through the Higgs mechanism. In this case, the would-be Nambu-Goldstone boson is an associated boson which is constructed from a pair of two-component massless fermions. This would-be Nambu-Goldstone boson appears as a result of the spontaneous breaking of the gauge invariance of the first kind, and it becomes unphysical through the Higgs mechanism. However, as all the fermions themselves decouple from photons, they cannot appear as real particles in our world. (author)
International Nuclear Information System (INIS)
Rindani, Saurabh D.
2002-07-01
Higgs physics is at present poised at an interesting juncture, when a light Higgs boson of the standard model (henceforth to be referred to as SM), a spin-zero particle which would signal spontaneous gauge symmetry breaking in the simplest form, has not been seen until the conclusion of experiments at LEP and LEP2 electron-positron collider at CERN, Geneva. From a theoretical point of view, the developments until the present time are complex and interesting. While some of the basic principles underlying spontaneous symmetry breaking of gauge symmetry and the Higgs mechanism are now commonly known, the actual realization of this mechanism in nature is still a subject of investigation. The mass of the SM Higgs boson is an unknown parameter and the phenomenology is sensitively dependent on the mass. Thus the properties and discovery strategies for the Higgs vary greatly depending on the supposed mass, and the phenomenology rapidly gets complex as the range of the Higgs mass is increased. Branching rations for various channels and the total decay width are shown as a function of the Higgs mass. We can get the total width of the Higgs by adding up all the decay channels. Up to masses of about 140 GeV, the Higgs is very narrow, Γ(H) H ∼ 200 GeV. The width cannot be measured directly in the intermediate mass region at LHC or e + e - colliders. However, it could be measured at μ + μ - colliders. Above a mass of about 250 GeV, the state is wide enough to be observable, in general. Above the two-vector-boson threshold, the width is Γ(H) ∼ 1/2m H 3 (TeV). For m H ∼ 1 TeV, Γ H ∼ 1/2 TeV. (author)
Energy Technology Data Exchange (ETDEWEB)
Katz, Andrey [Theory Division, CERN,CH-1211 Geneva 23 (Switzerland); Département de Physique Théorique and Center for Astroparticle Physics (CAP),Université de Genève,24 quai Ansermet, CH-1211 Genève 4 (Switzerland); Mariotti, Alberto [Theoretische Natuurkunde and IIHE/ELEM, Vrije Universiteit Brussel,and International Solvay Institutes,Pleinlaan 2, B-1050 Brussels (Belgium); Pokorski, Stefan [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw,ul. Pasteura 5, PL-02-093 Warsaw (Poland); Redigolo, Diego [Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University,Tel-Aviv 69978 (Israel); Department of Particle Physics and Astrophysics, Weizmann Institute of Science,Rehovot 7610001 (Israel); Ziegler, Robert [Institute for Theoretical Particle Physics (TTP), Karlsruhe Institute of Technology,Engesserstraße 7, D-76128 Karlsruhe (Germany)
2017-01-31
We investigate the general structure of mirror symmetry breaking in the Twin Higgs scenario. We show, using the IR effective theory, that a significant gain in fine tuning can be achieved if the symmetry is broken hardly. We emphasize that weakly coupled UV completions can naturally accommodate this scenario. We analyze SUSY UV completions and present a simple Twin SUSY model with a tuning of around 10% and colored superpartners as heavy as 2 TeV. The collider signatures of general Twin SUSY models are discussed with a focus on the extended Higgs sectors.
Adventures of the coupled Yang-Mills oscillators: II. YM-Higgs quantum mechanics
International Nuclear Information System (INIS)
Matinyan, Sergei G; Mueller, Berndt
2006-01-01
We continue our study of the quantum mechanical motion in the x 2 y 2 potentials for n = 2, 3, which arise in the spatially homogeneous limit of the Yang-Mills (YM) equations. In the present paper, we develop a new approach to the calculation of the partition function Z(t) beyond the Thomas-Fermi (TF) approximation by adding a harmonic (Higgs) potential and taking the limit v → 0, where v is the vacuum expectation value of the Higgs field. Using the Wigner-Kirkwood method to calculate higher-order corrections in ℎ, we show that the limit v → 0 leads to power-like singularities of the type v -n , which reflect the possibility of escape of the particle along the channels in the classical limit. We show how these singularities can be eliminated by taking into account the quantum fluctuations dictated by the form of the potential
Development of pulsating twin jets mechanism for mixing flow heat transfer analysis.
Gitan, Ali Ahmed; Zulkifli, Rozli; Abdullah, Shahrir; Sopian, Kamaruzzaman
2014-01-01
Pulsating twin jets mechanism (PTJM) was developed in the present work to study the effect of pulsating twin jets mixing region on the enhancement of heat transfer. Controllable characteristics twin pulsed jets were the main objective of our design. The variable nozzle-nozzle distance was considered to study the effect of two jets interaction at the mixing region. Also, the phase change between the frequencies of twin jets was taken into account to develop PTJM. All of these factors in addition to the ability of producing high velocity pulsed jet led to more appropriate design for a comprehensive study of multijet impingement heat transfer problems. The performance of PTJM was verified by measuring the pulse profile at frequency of 20 Hz, where equal velocity peak of around 64 m/s for both jets was obtained. Moreover, the jet velocity profile at different pulsation frequencies was tested to verify system performance, so the results revealed reasonable velocity profile configuration. Furthermore, the effect of pulsation frequency on surface temperature of flat hot plate in the midpoint between twin jets was studied experimentally. Noticeable enhancement in heat transfer was obtained with the increasing of pulsation frequency.
The Nobel Prize winner in physics 2013--Peter Higgs
International Nuclear Information System (INIS)
Liu Jinyan
2014-01-01
Peter Higgs is a famous English physicist who was known for his works on Higgs mechanism and Higgs particle. He won the 2013 Noble Prize in physics. This paper briefly outlines his life, the proposition of Higgs mechanism and the origin of the name of Higgs particle. The discovery of Higgs particle is also given here. (author)
Hierarchical ZnO with twinned structure: Morphology evolution, formation mechanism and properties
International Nuclear Information System (INIS)
Shi, Ruixia; Song, Xueling; Li, Jia; Yang, Ping
2015-01-01
Various hierarchical ZnO architectures constructed by twinned structures have been synthesized via a trisodium citrate assisted hydrothermal method on a large scale. The probable formation mechanisms of hierarchical ZnO structures with twinned structure were proposed and discussed. The hierarchical ZnO with twinned structures are composed of two hemispheres with a center concave junction to join them together at their waists. The ZnO microspheres with rough surfaces were obtained when the concentration of trisodium citrate is 0.1 M. However, the football-like microspheres consisted of hexagonal nanosheets were formed when adding glycerol into the water, which should be attributed to the slower nucleation and growth rate of nanocrystals. The hamburger-like ZnO with different aspect ratio and nonuniform ZnO microspheres were generated due to the different quantity of initial nuclei and growth units when simply modulating the concentration of trisodium citrate. The surface area of football-like ZnO is about 3.51 times of microspheres composed of irregular particles. However their photocatalytic performances are similar under UV light irradiation, which indicates that pore sizes of the sample have more important influences on the photocatalytic activity. - Highlights: • Hierarchical ZnO constructed by twinned structures have been synthesized. • The formation mechanisms of ZnO with twinned structure were discussed. • Football-like microspheres were obtained due to the slower nucleation and growth. • Hamburger-like ZnO was formed due to the amount of initial nuclei and growth units. • Pore sizes have important effects on the photocatalytic activity of sample
Hierarchical ZnO with twinned structure: Morphology evolution, formation mechanism and properties
Energy Technology Data Exchange (ETDEWEB)
Shi, Ruixia; Song, Xueling; Li, Jia; Yang, Ping, E-mail: mse_yangp@ujn.edu.cn
2015-04-15
Various hierarchical ZnO architectures constructed by twinned structures have been synthesized via a trisodium citrate assisted hydrothermal method on a large scale. The probable formation mechanisms of hierarchical ZnO structures with twinned structure were proposed and discussed. The hierarchical ZnO with twinned structures are composed of two hemispheres with a center concave junction to join them together at their waists. The ZnO microspheres with rough surfaces were obtained when the concentration of trisodium citrate is 0.1 M. However, the football-like microspheres consisted of hexagonal nanosheets were formed when adding glycerol into the water, which should be attributed to the slower nucleation and growth rate of nanocrystals. The hamburger-like ZnO with different aspect ratio and nonuniform ZnO microspheres were generated due to the different quantity of initial nuclei and growth units when simply modulating the concentration of trisodium citrate. The surface area of football-like ZnO is about 3.51 times of microspheres composed of irregular particles. However their photocatalytic performances are similar under UV light irradiation, which indicates that pore sizes of the sample have more important influences on the photocatalytic activity. - Highlights: • Hierarchical ZnO constructed by twinned structures have been synthesized. • The formation mechanisms of ZnO with twinned structure were discussed. • Football-like microspheres were obtained due to the slower nucleation and growth. • Hamburger-like ZnO was formed due to the amount of initial nuclei and growth units. • Pore sizes have important effects on the photocatalytic activity of sample.
Massive gravity in de Sitter space via the gravitational Higgs mechanism
International Nuclear Information System (INIS)
Iglesias, Alberto; Kakushadze, Zurab
2010-01-01
In this paper we discuss massive gravity in de Sitter space via the gravitational Higgs mechanism, which provides a nonlinear definition thereof. The Higgs scalars are described by a nonlinear sigma model, which includes higher derivative terms required to obtain the Fierz-Pauli mass term. Using the aforesaid nonperturbative definition, we address the appearance of an enhanced local symmetry and a null norm state in the linearized massive gravity in de Sitter space at the special value of the graviton mass to the Hubble parameter ratio. By studying full nonperturbative equations of motion, we argue that there is no enhanced symmetry in the full nonlinear theory. We then argue that in the full nonlinear theory no null norm state is expected to arise at the aforesaid special value. This suggests that no ghost might be present for lower graviton mass values and the full nonlinear theory might be unitary for all values of the graviton mass and the Hubble parameter with no van Dam-Veltman-Zakharov discontinuity. We argue that this is indeed the case by studying the full nonlinear Hamiltonian for the relevant conformal and helicity-0 longitudinal modes. In particular, we argue that no negative norm state is present in the full nonlinear theory.
Self-ligating vs conventional twin brackets during en-masse space closure with sliding mechanics.
Miles, Peter G
2007-08-01
The aim of this study was to compare the rate of en-masse space closure with sliding mechanics between passive self-ligating SmartClip brackets (3M Unitek, Monrovia, Calif) and conventional twin brackets ligated with stainless steel ligatures. Nineteen patients including 20 arches participated in this prospective trial with 0.018-in slot brackets. All patients had first premolar extractions in at least 1 arch, with the second premolar and the first molar distal to the extraction site bonded with SmartClip brackets on 1 side and conventional twin brackets on the other. The sides were alternated with each consecutive patient. Space closure was achieved on 0.016 x 0.022-in stainless steel wires with nickel-titanium coil springs activated 6 to 9 mm. The patients were recalled every 5 weeks until 1 side had closed. The distances from the mesial aspect of the canine bracket to the distal aspect of the first molar bracket were recorded before and after space closure, and an average rate of space closure per month was calculated. Thirteen patients completed the trial (14 arches); the median rates of tooth movement for the SmartClip bracket side (1.1 mm per month) and the conventional twin bracket side (1.2 mm per month) were not significantly different (P = .86). There was no significant difference in the rate of en-masse space closure between passive SmartClip brackets and conventional twin brackets tied with stainless steel ligatures.
Cohen, Timothy; Giudice, Gian F.; Mccullough, Matthew
2018-05-15
We introduce the Hyperbolic Higgs, a novel solution to the little hierarchy problem that features Standard Model neutral scalar top partners. At one-loop order, the protection from ultraviolet sensitivity is due to an accidental non-compact symmetry of the Higgs potential that emerges in the infrared. Once the general features of the effective description are detailed, a completion that relies on a five dimensional supersymmetric framework is provided. Novel phenomenology is compared and contrasted with the Twin Higgs scenario.
Energy Technology Data Exchange (ETDEWEB)
Ito, K R [Kyoto Univ. (Japan). Research Inst. for Mathematical Sciences
1975-03-01
The Schwinger model is considered in the Landau-gauge formalism of quantum electrodynamics. This model can be solved exactly on the assumption of no radiative corrections to the anomaly. It is found that the photon obtains a non-zero mass through the Higgs mechanism. In this case, the would-be Nambu-Goldstone boson is an associated boson which is constructed from a pair of two-component massless fermions. This would-be Nambu-Goldstone boson appears as a result of the spontaneous breaking of the gauge invariance of the first kind, and it becomes unphysical through the Higgs mechanism. However, as all the fermions themselves decouple from photons, they cannot appear as real particles in our world.
Does the Higgs mechanism favour electron-electron bound states in Maxwell-Chern-Simons QED3?
International Nuclear Information System (INIS)
Belich, Humberto; Helayeel-Neto, Jose Abdalla; Ferreira Junior, Manoel Messias
2000-01-01
Full text follows: We show that low-energy electron-electron bound states appear in the Maxwell-Chern-Simons (MCS) planar QED. In spite of the repulsive interaction mediated by the MCS gauge field, a net attractive interaction stems due to the Higgs mechanism through an Yukawa-type interaction. The spontaneous breaking of a local U(1)-symmetry is realized by a γ 6 -type potential. We conclude, by using the Schroedinger equation associated to the net attractive scattering potential, that electron-electron bound states arise in the model. Therefore, the Higgs mechanism overcomes the difficulties found out by Girotti et al. (Phys. Rev. Lett. 69 (1992) 2623) in searching for bound states in the MCS planar QED. (author)
International Nuclear Information System (INIS)
Boyanovsky, D.; Holman, R.; Hutasoit, Jimmy A.
2009-01-01
Motivated by slow-roll inflationary cosmology we study a scalar unparticle weakly coupled to a Higgs field in the broken symmetry phase. The mixing between the unparticle and the Higgs field results in a seesaw type matrix and the mixing angles feature a Mikheyev-Smirnov-Wolfenstein (MSW) effect as a consequence of the unparticle field being noncanonical. We find two (MSW) resonances for small and large spacelike momenta. The unparticlelike mode features a nearly flat potential with spinodal instabilities and a large expectation value. An effective potential for the unparticlelike field is generated from the Higgs potential, but with couplings suppressed by a large power of the small seesaw ratio. The dispersion relation for the Higgs-like mode features an imaginary part even at ''tree level'' as a consequence of the fact that the unparticle field describes a multiparticle continuum. Mixed unparticle-Higgs propagators reveal the possibility of oscillations, albeit with short coherence lengths. The results are generalized to the case in which the unparticle features a mass gap, in which case a low energy MSW resonance may occur for lightlike momenta depending on the scales. Unparticle-Higgs mixing leads to an effective unparticle potential of the new-inflation form. Slow-roll variables are suppressed by seesaw ratios and the anomalous dimensions and favor a red spectrum of scalar perturbations consistent with cosmic microwave background data.
Boyanovsky, D.; Holman, R.; Hutasoit, Jimmy A.
2009-04-01
Motivated by slow-roll inflationary cosmology we study a scalar unparticle weakly coupled to a Higgs field in the broken symmetry phase. The mixing between the unparticle and the Higgs field results in a seesaw type matrix and the mixing angles feature a Mikheyev-Smirnov-Wolfenstein (MSW) effect as a consequence of the unparticle field being noncanonical. We find two (MSW) resonances for small and large spacelike momenta. The unparticlelike mode features a nearly flat potential with spinodal instabilities and a large expectation value. An effective potential for the unparticlelike field is generated from the Higgs potential, but with couplings suppressed by a large power of the small seesaw ratio. The dispersion relation for the Higgs-like mode features an imaginary part even at “tree level” as a consequence of the fact that the unparticle field describes a multiparticle continuum. Mixed unparticle-Higgs propagators reveal the possibility of oscillations, albeit with short coherence lengths. The results are generalized to the case in which the unparticle features a mass gap, in which case a low energy MSW resonance may occur for lightlike momenta depending on the scales. Unparticle-Higgs mixing leads to an effective unparticle potential of the new-inflation form. Slow-roll variables are suppressed by seesaw ratios and the anomalous dimensions and favor a red spectrum of scalar perturbations consistent with cosmic microwave background data.
International Nuclear Information System (INIS)
Zhang, Yanqiu; Jiang, Shuyong; Zhu, Xiaoming; Zhao, Yanan
2016-01-01
Molecular dynamics simulation was performed to investigate dislocation mechanism of void growth at twin boundary (TB) of nanotwinned nickel. Simulation results show that the deformation of nanotwinned nickel containing a void at TB is dominated by the slip involving both leading and trailing partials, where the trailing partials are the dissociation products of stair-rod dislocations formed by the leading partials. The growth of a void at TB is attributed to the successive emission of the leading partials followed by trailing partials as well as the escape of these partial dislocations from the void surface. - Highlights: • Dislocation mechanism of void growth at TB of nanotwinned nickel is investigated. • Deformation of the nanotwinned nickel is dominated by leading and trailing partials. • Growth of void at TB is caused by successive emission and escape of these partials.
Kinetic mechanism of V-shaped twinning in 3C/4H-SiC heteroepitaxy
Energy Technology Data Exchange (ETDEWEB)
Xin, Bin; Zhang, Yu-Ming; Jia, Ren-Xu, E-mail: rxjia@mail.xidian.edu.cn [School of Microelectronics, Xidian University, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi' an 710071 (China); Wu, Hong-Ming [Graduate Institute of Electronics Engineering, National Taiwan University, 10617 Taipei, Taiwan (China); Feng, Zhe Chuan [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 10617 Taipei, Taiwan and Laboratory of Optoelectronic Materials and Detection Technology, Guangxi Key Laboratory for the Relativistic Astrophysics, College of Physics Science and Technology, Guangxi University, Nanning 530004 (China); Lin, Hao-Hsiung [Graduate Institute of Electronics Engineering, National Taiwan University, 10617 Taipei, Taiwan and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 10617 Taipei, Taiwan (China)
2016-05-15
The authors investigated the kinetic mechanism of V-shaped twinning in 3C/4H-SiC heteroepitaxy. A fourfold V-shaped twinning complex was found, and its interface was measured with high-resolution transmission electron microscopy (HRTEM). Two linear coherent boundaries and a nonlinear incoherent boundary (also called the double-position boundary) were observed. On the basis of the HRTEM results, the authors proposed an adatom migration growth model, in which the activation barrier at the coherent boundary is much lower than that at the incoherent boundary. From a kinetic perspective, adatoms are prone to migrate to the side of the boundary with the lower potential energy if they have sufficient thermal energy to overcome the activation barrier. In the case of a coherent boundary, the growth rates of the domains either side of the boundary can be balanced through the intermigration of adatoms, leading to a linear boundary. Conversely, it is difficult for adatoms to migrate across an incoherent boundary, which results in asynchronous growth rates and a nonlinear boundary.
Radiatively Generating the Higgs Potential and Electroweak Scale via the Seesaw Mechanism.
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.
Mechanical properties of PA6/PP compatibilized nanocomposites using a twin screw extruder
De Almeida, M. F.; Correia, Aldina; e Silva, Eliana Costa; Lopes, I. Cristina
2017-11-01
In this article, a new approach to study the compatibilization effect of organophilic clays in PA6/PP polymer blends through experimental results of mechanical tests is presented. This study focus on the description of the interphase in compatibilization by addition of the organoclays C15A and C30B into the polymer PA6/PP blend by melt compounding using a Twin Screw Extruder. The experimental results variations are studied, by addition of the organoclays in uncompatibilized polymer blend, using non-parametric analysis of variance (Kruskal-Wallis Test). For all the experimental results, significant differences are identified between the types of polymer blends. It was observed the compatibilization effect of both organophilic clays, being the differences most evident in the presence of PP modified.
International Nuclear Information System (INIS)
Jandin, G.; Liao, H.; Feng, Z.Q.; Coddet, C.
2003-01-01
An experimental design matrix was set up in which carbon steel coatings were deposited with a twin wire arc spray gun (TAFA 9000 TM ), using either compressed air or nitrogen as spraying gas. The coating's mechanical properties were studied. Some correlations were made between these properties, spraying conditions and the microstructure of the deposits. Young's modulus was estimated by the single beam method using finite element modeling. Results show that direct relationships do exist between spray conditions, oxide content in the coating and microhardness. Young's modulus of the coatings depends on the lamella thickness and the oxide content. When increasing the compressed air flow rate, Young's modulus increases at first because smaller particles and finer lamellae were made and it decreases later because of a higher oxide content. The increase of nitrogen flow rate lowers the oxide content and increases Young's modulus
Chang Y.K.; Martinez-Bustos F.; Park T.S.; Kokini J.L.
1999-01-01
The influence of specific mechanical energy (SME) on cornmeal viscosity during the twin-screw extrusion at feed moisture contents of 25 and 30% and screw speeds in the range from 100 to 500 rpm was measured. Cornmeal was extruded in a co-rotating, intermeshing twin-screw coupled to a slit die rheometer. One approach to the on-line rheological measurement is to use a slit die with the extruder. In the present work it was show that shear viscosity decreased as a function of SME. The viscosity o...
Using neutron diffraction to examine the onset of mechanical twinning in calcite rocks
Covey-Crump, S. J.; Schofield, P. F.; Oliver, E. C.
2017-07-01
Experimental calibration of the calcite twin piezometer is complicated by the difficulty of establishing the stresses at which the twins observed in the final deformation microstructures actually formed. In principle, this difficulty may be circumvented if the deformation experiments are performed in a polychromatic neutron beam-line because this allows the elastic strain (and hence stress) in differently oriented grains to be simultaneously monitored from diffraction patterns collected as the experiment is proceeding. To test this idea small strain (marble (grain size 150 μm) and Solnhofen limestone (5 μm) at temperatures of 20°-600 °C using the ENGIN-X instrument at the ISIS neutron facility, UK. At the lowest temperatures (25 °C Carrara; 200 °C Solnhofen) the deformation response was purely elastic up to the greatest stresses applied (60 MPa Carrara; 175 MPa Solnhofen). The sign of the calcite elastic stiffness component c14 is confirmed to be positive when the obverse setting of the calcite rhombohedral lattice in hexagonal axes is used. In the Carrara marble samples deformed at higher temperatures, elastic twinning was initiated at small stresses (<15 MPa) in grains oriented such that the Schmid factor for twinning was positive on more than one e-twin system. At greater stresses (65 MPa at 200 °C decreasing to 41 MPa at 500 °C) there was an abrupt onset of permanent twinning in grains with large Schmid factors for twinning on any one e-twin system. No twinning was observed in the Solnhofen limestone samples deformed at 200° or 400 °C at applied stresses of <180 MPa. These results highlight the potential of this approach for detecting the onset of twinning and provide, through experiments on samples with different microstructures, a strategy for systematically investigating the effects of microstructural variables on crystallographically-controlled inelastic processes.
Smoking-gun signatures for little Higgs models
International Nuclear Information System (INIS)
Han, Tao
2004-01-01
The little Higgs idea is a new way to solve the 'little hierarchy' problem by protecting the Higgs mass from quadratically divergent one-loop corrections. After a general introduction, I first describe the Littlest Higgs model to illustrate the little Higgs idea. I then present certain phenomenological signatures of two classes of little Higgs theories for future colliders. I emphasize to test the cancellation mechanism and how to distinguish different little Higgs models. (author)
Kinetic model for mechanical twinning and its application for intensive loading of metals
Directory of Open Access Journals (Sweden)
Mayer Alexander
2015-01-01
Full Text Available In this report, we present our twinning model intended for simulation of the dynamic deformation of metals with low values of the stacking fault energy, as well as the results of application of the model to numerical simulation of intensive loading of metals. Generation of a twin is described as an appearance of a stacking fault with size more than some critical value, while growth of a twin is considered as a cooperative movement of partial dislocation along the stacking fault. The twin nucleation rate is expressed through the energy released due to annihilation of dislocations. Movement of partial dislocations in the course of twin growth passes under the action of elastic stress field and phonon drag. The surface energy of the growing twin continuously increases which leads to the appearance of an additional force. Application of this model allows us to investigate plastic response of metals at various dynamic loading conditions and initial defect structures. Influence of twinning at Taylor rod compaction experiments is analyzed including formation of the shape of the lateral surface.
Yao, Maoqing; Sheng, Chunyang; Ge, Mingyuan; Chi, Chun-Yung; Cong, Sen; Nakano, Aiichiro; Dapkus, P Daniel; Zhou, Chongwu
2016-02-23
Monolithic integration of III-V semiconductors with Si has been pursued for some time in the semiconductor industry. However, the mismatch of lattice constants and thermal expansion coefficients represents a large technological challenge for the heteroepitaxial growth. Nanowires, due to their small lateral dimension, can relieve strain and mitigate dislocation formation to allow single-crystal III-V materials to be grown on Si. Here, we report a facile five-step heteroepitaxial growth of GaAs nanowires on Si using selective area growth (SAG) in metalorganic chemical vapor deposition, and we further report an in-depth study on the twin formation mechanism. Rotational twin defects were observed in the nanowire structures and showed strong dependence on the growth condition and nanowire size. We adopt a model of faceted growth to demonstrate the formation of twins during growth, which is well supported by both a transmission electron microscopy study and simulation based on nucleation energetics. Our study has led to twin-free segments in the length up to 80 nm, a significant improvement compared to previous work using SAG. The achievements may open up opportunities for future functional III-V-on-Si heterostructure devices.
Once again about the role of gluonic mechanism in interaction of light Higgs boson with hadrons
International Nuclear Information System (INIS)
Voloshin, M.V.
1985-01-01
Low-energy theorems of QCD are employed to show that the coupling to gluons enchances hadronic decays of a light (Msub(H) + μ - branching ratio is heavily suppressed. A simple low-energy theorem as derived for production amplitude of light H which also enables to evaluate non-perturbative contribution to the amplitude. By a method analogous to bremsstrahlung calculation the branching ratio of γ decay into a light Higgs plus hadrons is evaluated to be of the order of 3x10 -5 if the coupling of H to b-quark is described by the standard minimum model
Higgs mechanism and cosmological constant in N = 1 supergravity with inflaton in a vector multiplet
Energy Technology Data Exchange (ETDEWEB)
Aldabergenov, Yermek [Tokyo Metropolitan University, Department of Physics, Tokyo (Japan); Ketov, Sergei V. [Tokyo Metropolitan University, Department of Physics, Tokyo (Japan); The University of Tokyo, Kavli Institute for the Physics and Mathematics of the Universe (IPMU), Chiba (Japan); Tomsk Polytechnic University, Institute of Physics and Technology, Tomsk (Russian Federation)
2017-04-15
The N = 1 supergravity models of cosmological inflation with an inflaton belonging to a massive vector multiplet and spontaneous SUSY breaking after inflation are reformulated as the supersymmetric U(1) gauge theories of a massless vector superfield interacting with the Higgs and Polonyi chiral superfields, all coupled to supergravity. The U(1) gauge sector is identified with the U(1) gauge fields of the super-GUT coupled to supergravity, whose gauge group has a U(1) factor. A positive cosmological constant (dark energy) is included. The scalar potential is calculated, and its de Sitter vacuum solution is found to be stable. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Passarino, Giampiero [Universita di Torino, Dipartimento di Fisica Teorica, Turin (Italy); INFN, Sezione di Torino, Turin (Italy)
2014-05-15
Higgs Computed Axial Tomography, an excerpt. The Higgs boson lineshape (..and the devil hath power to assume a pleasing shape, Hamlet, Act II, scene 2) is analyzed for the gg → ZZ process, with special emphasis on the off-shell tail which shows up for large values of the Higgs virtuality. The effect of including background and interference is also discussed. The main focus of this work is on residual theoretical uncertainties, discussing how much-improved constraint on the Higgs intrinsic width can be revealed by an improved approach to analysis. (orig.)
International Nuclear Information System (INIS)
Passarino, Giampiero
2014-01-01
Higgs Computed Axial Tomography, an excerpt. The Higgs boson lineshape (..and the devil hath power to assume a pleasing shape, Hamlet, Act II, scene 2) is analyzed for the gg → ZZ process, with special emphasis on the off-shell tail which shows up for large values of the Higgs virtuality. The effect of including background and interference is also discussed. The main focus of this work is on residual theoretical uncertainties, discussing how much-improved constraint on the Higgs intrinsic width can be revealed by an improved approach to analysis. (orig.)
Higgs Particle: The Origin of Mass
Okada, Yasuhiro
2007-01-01
The Higgs particle is a new elementary particle predicted in the Standard Model of the elementary particle physics. It plays a special role in the theory of mass generation of quarks, leptons, and gauge bosons. In this article, theoretical issues on the Higgs mechanism are first discussed, and then experimental prospects on the Higgs particle study at the future collider experiments, LHC and ILC, are reviewed. The Higgs coupling determination is an essential step to establish the mass generat...
Indian Academy of Sciences (India)
The theoretical aspects of the physics of Higgs bosons are reviewed focussing on the elements that are relevant for the production and detection at present hadron colliders. After briefly summarizing the basics of electroweak symmetry breaking in the Standard Model, the Higgs production at the LHC and at the Tevatron is ...
Anencephaly with incomplete twinning (diprosopus).
Riccardi, V M; Bergmann, C A
1977-10-01
A case of diprosopus with anencephaly is presented. It is suggested that such concurrence of neural tube defects and incomplete twinning corroborates the notion that a single pathogenetic mechanism may be common to both neural tube defects and monozygotic twinning.
International Nuclear Information System (INIS)
Sohn, Seok Su; Choi, Kayoung; Kwak, Jai-Hyun; Kim, Nack J.; Lee, Sunghak
2014-01-01
The need for lightweight materials has been an important issue in automotive industries to reduce greenhouse gas emission and to improve fuel efficiency. In addition, automotive steels require an excellent combination of strength and ductility to sustain automotive structures and to achieve complex shapes, but the traditional approach to obtain a reduction in weight from down-gauged steels with high strength has many limitations. Here, we present a new ferrite–austenite duplex lightweight steel containing a low-density element, Al; this steel exhibits tensile elongation up to 77% as well as high tensile strength (734 MPa). The enhanced properties are attributed to the simultaneous formation of deformation-induced martensites and deformation twins and the additional plasticity due to deformation twinning in austenite grains having optimal mechanical stability. The present work gives a promise for automotive applications requiring excellent properties as well as reduced specific weight
Energy Technology Data Exchange (ETDEWEB)
Wang, X.L.; Li, L.; Mei, W.; Wang, W.L.; Sun, J., E-mail: jsun@sjtu.edu.cn
2015-09-15
Tensile properties and deformation microstructures of a series of binary β Ti–16–22V alloys have been investigated. The results show that the plastic deformation mode changes from the plate-like stress-induced ω phase transformation with a special habit plane of (− 5052){sub ω}//(3 − 3 − 2){sub β} to (332)<113> type deformation twinning with increasing the content of vanadium in the β Ti–16–22 wt.% V alloys. The plate-like stress-induced ω phase has a special orientation relationship with the β phase matrix, i.e., [110]{sub β}//[− 12 − 10]{sub ω}, (3 − 3 − 2){sub β}//(− 5052){sub ω} and (− 55 − 4){sub β}//(30 − 31){sub ω}. The alloys plastically deformed by stress-induced ω phase transformation exhibit relatively higher yield strength than those deformed via (332)<113> type deformation twinning. It can be concluded that the stability of β phase plays a significant role in plastic deformation mode, i.e., stress-induced ω phase transformation or (332)<113> type deformation twinning, which governs the mechanical property of the β Ti–16–22 wt.% V alloys. - Highlights: • Tensile properties and deformed microstructures of β Ti–16–22V alloys were studied. • Stress-induced ω phase transformation and (332)<113> twinning occur in the alloys. • Stability of β phase plays a significant role in plastic deformation mode. • Plastic deformation mode governs the mechanical property of the alloys.
DEFF Research Database (Denmark)
Leffers, Torben
1970-01-01
The author presents his final comments on the discussion between himself and Heye and Wasserman (see abstrs. A11834 and A11835 of 1970) which arose from the latter authors' paper on mechanical twinning (see abstr. A19815 of 1969). The validity of the twinning theory for the brass-type rolling...... texture is questioned for two reasons: There is no convincing crystallographic model explaining how the formation of the brass-type texture by combined twinning and slip should work in theory, and there are experimental results indicating that it should not work in practice...
Energy Technology Data Exchange (ETDEWEB)
Sabat, R.K. [Department of Materials Engineering, IISc, Bangalore 560012 (India); Panda, D. [Department of Metallurgical & Materials Engineering, NIT, Rourkela 769008 (India); Sahoo, S.K., E-mail: sursahoo@gmail.com [Department of Metallurgical & Materials Engineering, NIT, Rourkela 769008 (India)
2017-04-15
Pure magnesium was subjected to plastic deformation through CSM (continuous stiffness measurement) indentation followed by annealing at 200 °C for 30 min. Nucleation of no new grains was observed neither at the twin–twin intersections nor at the multiple twin variants of a grain after annealing. Significant growth of off-basal twin orientation compared to basal twin orientation was observed in the sample after annealing and is attributed to the partial coherent nature of twin boundary in the later case. Further, growth of twins was independent of the strain distribution between parent and twinned grains. - Highlights: • An ‘ex situ’ EBSD of pure Mg during annealing was investigated. • Nucleation of no new grains was observed. • Significant growth of off-basal twin orientation was observed. • Growth of twins may be attributed to the partial coherent nature of twin boundary.
Czech Academy of Sciences Publication Activity Database
Máthis, K.; Horváth, Klaudia; Farkas, Gergely; Choe, H.; Shin, K. S.; Vinogradov, A.
2018-01-01
Roč. 11, č. 2 (2018), č. článku 200. ISSN 1996-1944 R&D Projects: GA ČR GB14-36566G; GA MŠk EF16_013/0001794 Institutional support: RVO:61389005 Keywords : magnesium * twin roll casting * neutron diffraction * acoustic emission * twinning * yield strength Subject RIV: JL - Materials Fatigue, Friction Mechanics OBOR OECD: Audio engineering, reliability analysis Impact factor: 2.654, year: 2016
Vector Higgs-portal dark matter and the invisible Higgs
International Nuclear Information System (INIS)
Lebedev, Oleg; Lee, Hyun Min; Mambrini, Yann
2011-11-01
The Higgs sector of the Standard Model offers a unique probe of the hidden sector. In this work, we explore the possibility of renormalizable Higgs couplings to the hidden sector vector fields which can constitute dark matter (DM). Abelian gauge sectors with minimal field content, necessary to render the gauge fields massive, have a natural Z 2 parity. This symmetry ensures stability of the vector fields making them viable dark matter candidates, while evading the usual electroweak constraints. We illustrate this idea with the Stueckelberg and Higgs mechanisms. Vector DM is consistent with the WMAP, XENON100, and LHC constraints, while it can affect significantly the invisible Higgs decay. Due to the enhanced branching ratio for the Higgs decay into the longitudinal components of the vector field, the vector Higgs portal provides an efficient way to hide the Higgs at the LHC. This could be the reason why the latest combined ATLAS/CMS data did not bring evidence for the existence of the Higgs boson. (orig.)
Vector Higgs-portal dark matter and the invisible Higgs
Energy Technology Data Exchange (ETDEWEB)
Lebedev, Oleg [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Lee, Hyun Min [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Mambrini, Yann [Paris-Sud Univ., 91 - Orsay (France). Lab. de Physique Theorique
2011-11-15
The Higgs sector of the Standard Model offers a unique probe of the hidden sector. In this work, we explore the possibility of renormalizable Higgs couplings to the hidden sector vector fields which can constitute dark matter (DM). Abelian gauge sectors with minimal field content, necessary to render the gauge fields massive, have a natural Z{sub 2} parity. This symmetry ensures stability of the vector fields making them viable dark matter candidates, while evading the usual electroweak constraints. We illustrate this idea with the Stueckelberg and Higgs mechanisms. Vector DM is consistent with the WMAP, XENON100, and LHC constraints, while it can affect significantly the invisible Higgs decay. Due to the enhanced branching ratio for the Higgs decay into the longitudinal components of the vector field, the vector Higgs portal provides an efficient way to hide the Higgs at the LHC. This could be the reason why the latest combined ATLAS/CMS data did not bring evidence for the existence of the Higgs boson. (orig.)
Vector Higgs portal dark matter and the invisible Higgs
International Nuclear Information System (INIS)
Lebedev, Oleg; Lee, Hyun Min; Mambrini, Yann
2012-01-01
The Higgs sector of the Standard Model offers a unique probe of the hidden sector. In this work, we explore the possibility of renormalizable Higgs couplings to the hidden sector vector fields which can constitute dark matter (DM). Abelian gauge sectors with minimal field content, necessary to render the gauge fields massive, have a natural Z 2 parity. This symmetry ensures stability of the vector fields making them viable dark matter candidates, while evading the usual electroweak constraints. We illustrate this idea with the Stückelberg and Higgs mechanisms. Vector DM is consistent with the WMAP, XENON100, and LHC constraints, while it can affect significantly the invisible Higgs decay. Due to the enhanced branching ratio for the Higgs decay into the longitudinal components of the vector field, the vector Higgs portal provides an efficient way to hide the Higgs at the LHC. This could be the reason why the latest combined ATLAS/CMS data did not bring evidence for the existence of the Higgs boson.
DEFF Research Database (Denmark)
Sannino, Francesco
2013-01-01
has been challenged by the discovery of a not-so-heavy Higgs-like state. I will therefore review the recent discovery \\cite{Foadi:2012bb} that the standard model top-induced radiative corrections naturally reduce the intrinsic non-perturbative mass of the composite Higgs state towards the desired...... via first principle lattice simulations with encouraging results. The new findings show that the recent naive claims made about new strong dynamics at the electroweak scale being disfavoured by the discovery of a not-so-heavy composite Higgs are unwarranted. I will then introduce the more speculative......I discuss the impact of the discovery of a Higgs-like state on composite dynamics starting by critically examining the reasons in favour of either an elementary or composite nature of this state. Accepting the standard model interpretation I re-address the standard model vacuum stability within...
International Nuclear Information System (INIS)
Hanninger, Guilherme Nunes
2012-01-01
Full text: The Standard Model of particle physics (SM) has been extremely successful describing the elementary particles and their interactions. It also features a theory describing the origin of particle masses: the 'Higgs mechanism', which postulates the existence of a new particle called the 'Higgs boson'. In 2011 and 2012, tantalising hints of the Higgs boson were reported by the experiments at the Large Hadron Collider (LHC). The results of the search for the Standard Model Higgs Boson with the ATLAS detector in proton-proton collisions at the LHC at 7 and 8 TeV center-of-mass energies are presented. A large number of the Higgs Boson decay channels, such as photon, tau, W and Z pairs, as well as for combined channels in the mass range from 110 GeV to 600 GeV are reviewed and discussed. The combined upper limits on the production cross section as a function of the Higgs Boson mass are derived. Practical methods to estimate the backgrounds using control samples in real data are discussed. Validation of some of the data driven background estimation methods using the early 7 TeV ATLAS data at the LHC is also presented. In addition, searches for Higgs Bosons in scenarios beyond the Standard Model (BSM) lead to improved constraints on the Higgs sector of BSM theories such as Supersymmetry. (author)
Brunet, S
2014-01-01
ATLAS Higgs poster targeted to general public, explaining the Brout-Englert-Higgs mechanism and why it is important. It also explains the role of the Higgs Boson, how we look for it, the journey of the discovery and what comes after the discovery. Also available in French (http://cds.cern.ch/record/1697501). Don’t hesitate to use it in your institute’s corridors and in your outreach events! The poster is in A0 format. You can click on the image to download the high-quality .pdf version and print it at your favorite printshop. For any questions or comments you can contact atlas-outreach-coordination@cern.ch.
Indian Academy of Sciences (India)
The large hadron collider (LHC) and its detectors, ATLAS and CMS, are being built to study TeV scale physics, and to fully understand the electroweak symmetry breaking mechanism. The Monte-Carlo simulation results for the standard model and minimal super symmetric standard model Higgs boson searches and ...
Energy Technology Data Exchange (ETDEWEB)
Das, Sanjeev, E-mail: sanjeevdas80@gmail.com [The EPSRC Centre ‐ LiME, BCAST, Brunel University, Uxbridge UB8 3PH (United Kingdom); Barekar, N.S. [The EPSRC Centre ‐ LiME, BCAST, Brunel University, Uxbridge UB8 3PH (United Kingdom); El Fakir, Omer; Wang, Liliang [Department of Mechanical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Prasada Rao, A.K.; Patel, J.B.; Kotadia, H.R.; Bhagurkar, A. [The EPSRC Centre ‐ LiME, BCAST, Brunel University, Uxbridge UB8 3PH (United Kingdom); Dear, John P. [Department of Mechanical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Fan, Z. [The EPSRC Centre ‐ LiME, BCAST, Brunel University, Uxbridge UB8 3PH (United Kingdom)
2015-01-03
In the present investigation, magnesium strips were produced by twin roll casting (TRC) and melt conditioned twin roll casting (MC-TRC) processes. Detailed optical microscopy studies were carried out on as-cast and homogenized TRC and MC-TRC strips. The results showed uniform, fine and equiaxed grain structure was observed for MC-TRC samples in as-cast condition. Whereas, coarse columnar grains with centreline segregation were observed in the case of as-cast TRC samples. The solidification mechanisms for TRC and MC-TRC have been found completely divergent. The homogenized TRC and MC-TRC samples were subjected to tensile test at elevated temperature (250–400 °C). At 250 °C, MC-TRC sample showed significant improvement in strength and ductility. However, at higher temperatures the tensile properties were almost comparable, despite of TRC samples having larger grains compared to MC-TRC samples. The mechanism of deformation has been explained by detailed fractures surface and sub-surface analysis carried out by scanning electron and optical microscopy. Homogenized MC-TRC samples were formed (hot stamping) into engineering component without any trace of crack on its surface. Whereas, TRC samples cracked in several places during hot stamping process.
Charlemaine, Christiane
2006-12-31
This paper explores the deep roots of closeness that twins share in their youngest age and their effect on their destiny at the adult age. Psychologists believe the bond between twins begins in utero and develops throughout the twins' lives. The four patterns of twinship described show that the twin bond is determined by the quality of parenting that twins receive in their infancy and early childhood. Common problems of adult twins bring about difficulties to adapt in a non-twin world. The nature versus nurture controversy has taken on new life focusing on inter-twin differences and the importance of parent-child interaction as fundamental to the growth and development of personality.
Lenstra, Arjen K.; Weger, De; Benjamin, M. M.
2005-01-01
We introduce Twin RSA, pairs of RSA moduli (n, n+ 2), and formulate several questions related to it. Our main questions are: is Twin RSA secure, and what is it good for? © Springer-Verlag Berlin Heidelberg 2005.
Itoh, K; Imai, Y; Obayashi, C; Hayashi, Y; Hanioka, K; Itoh, H
1993-06-01
The anatomical and pathological features of two pairs of dicephalic conjoined twins (case 1 and 2) are described. Both twins showed duplicitas lateralis representing diprosopus dipus dibrachius. There were two complete heads on two necks, one thorax, one abdomen and externally normal two arms and two legs. Case 1 showed dicephalus with anencephaly, two vertebral columns and two spinal cords, which converged from the thoracic region distally. The esophagus, stomachs and partial small intestines were duplicated, which fused at yolk sac (with Meckel's diverticulum). The heart was incompletely fused. The lungs and trachea were doubled. Two spinal cords were fused from the thoracic region caudally and showed myelomeningocele and Arnold-Chiari malformation in case 2. Two larynxes and two thracheas connected with the incompletely fused three lobes of lungs. The conjoined lungs were hypoplastic. The heart was single, showing ventral septal defect, transposition of great arteries, two cuspid aortic valves and preductal aortic coarctation. The duplicated esophagi were conjoined in Y-shape and single stomach, duodenum, intestine and colon were found. There were pairs of kidneys, adrenal glands and ureters and single female genitalia in both cases. These findings indicate that the craniocaudal paleoaxes were separated in the cranial region and converted or fused under the thoracic region like a Y-shape. Further development defects and deformations might be important factors to form malformations in these case.
The Higgs Portal and Cosmology
Energy Technology Data Exchange (ETDEWEB)
Assamagan, Ketevi [Brookhaven National Lab. (BNL), Upton, NY (United States); Chen, Chien-Yi [Perimeter Inst. for Theoretical Physics, Waterloo, ON (Canada); Univ. of Victoria, BC (Canada); Chou, John Paul [Rutgers Univ., Piscataway, NJ (United States); Curtin, David [Univ. of Maryland, College Park, MD (United States); Fedderke, Michael A. [Univ. of Chicago, IL (United States); Gershtein, Yuri [Rutgers Univ., Piscataway, NJ (United States); He, Xiao-Gang [Shanghai Jiao Tong Univ. (China); Klute, Markus [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Kozaczuk, Jonathon [TRIUMF, Vancouver, BC (Canada); Kotwal, Ashutosh [Duke Univ., Durham, NC (United States); Lowette, Steven [Vrije Univ., Brussels (Belgium); No, Jose Miguel [Univ. of Sussex, Brighton (United Kingdom); Plehn, Tilman [Heidelberg Univ. (Germany); Qian, Jianming [Univ. of Michigan, Ann Arbor, MI (United States); Ramsey-Musolf, Michael [Univ. of Massachusetts, Amherst, MA (United States); Safonov, Alexei [Texas A & M Univ., College Station, TX (United States); Shelton, Jessie [Univ. of Illinois, Urbana-Champaign, IL (United States); Spannowsky, Michael [Durham Univ. (United Kingdom); Su, Shufang [Univ. of Arizona, Tucson, AZ (United States); Walker, Devin G. E. [Univ. of Washington, Seattle, WA (United States); Willocq, Stephane [Univ. of Massachusetts, Amherst, MA (United States); Winslow, Peter [Univ. of Massachusetts, Amherst, MA (United States)
2016-04-18
Higgs portal interactions provide a simple mechanism for addressing two open problems in cosmology: dark matter and the baryon asymmetry. In the latter instance, Higgs portal interactions may contain the ingredients for a strong first-order electroweak phase transition as well as new CP-violating interactions as needed for electroweak baryogenesis. These interactions may also allow for a viable dark matter candidate. We survey the opportunities for probing the Higgs portal as it relates to these questions in cosmology at the LHC and possible future colliders.
Pomarol, Alex
2016-01-01
With the discovery of the Higgs, we have access to a plethora of new physical processes that allow us to further test the SM and beyond. We show a convenient way to parametrize these physics using an effective theory for Higgs couplings, discussing the importance of the basis selection, predictions from a SM effective field theory, and possible ways to measure these couplings with special attention to the high-energy regime. Predictions from the MSSM and MCHM, with the comparison with data, are also provided.
Grojean, C.
2016-01-01
The cause of the screening of the weak interactions at long distances puzzled the high-energy community for more nearly half a century. With the discovery of the Higgs boson a new era started with direct experimental information on the physics behind the breaking of the electroweak symmetry. This breaking plays a fundamental role in our understanding of particle physics and sits at the high-energy frontier beyond which we expect new physics that supersedes the Standard Model. The Higgs boson (inclusive and differential) production and decay rates offer a new way to probe this frontier.
International Nuclear Information System (INIS)
Mirzadeh, H.; Roostaei, M.; Parsa, M.H.; Mahmudi, R.
2015-01-01
Highlights: • Hot deformation behavior and dynamic recrystallization of GZ31 magnesium alloy. • Deducing the operative deformation mechanisms by constitutive analysis. • Viscous glide as the rate controlling step during hot working of GZ31 alloy. • Characterization of the effect of mechanical twinning on constitutive relations. - Abstract: The flow behavior of the Mg–3Gd–1Zn (GZ31) magnesium alloy during hot working was critically analyzed and dislocation glide in the form of a viscous drag process (viscous glide) was identified as the rate controlling mechanism due to interaction of rare earth Gd atoms with the moving dislocations. Mechanical twinning was shown to significantly affect the level of flow stress at high Zener–Hollomon parameters, i.e. low forming temperatures and high strain rates. Moreover, dynamic recrystallization (DRX) was found to be another responsible phenomenon for deviation of constitutive equations from the theoretical ones, namely the deformation activation energy based on diffusivity and the pre-defined Garofalo’s type hyperbolic sine power, during high-temperature thermomechanical processing of this creep resistant light alloy
Phenomenology of the Higgs boson
International Nuclear Information System (INIS)
Ali, A.
1981-09-01
The phenomenology of the standard Weinberg-Salam Higgs boson is reviewed with particular emphasis on production mechanisms in high energy e + e - and hadron-hadron collisions. The production processes relevant for the ISABELLE and TEVATRON energies are discussed and their backgrounds estimated. It is argued that the toponium production and radiative decay provides the most hopeful reaction to detect a Higgs in both the e + e - and the hadron-hadron machines. (orig.)
Smoking-gun signatures of little Higgs models
Energy Technology Data Exchange (ETDEWEB)
Han Tao [Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States); Institute of Theoretical Physics, Academia Sinica, Beijing 100080 (China); Logan, Heather E. [Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States); Wang, L.-T. [Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States); Jefferson Laboratory of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)
2006-01-15
Little Higgs models predict new gauge bosons, fermions and scalars at the TeV scale that stabilize the Higgs mass against quadratically divergent one-loop radiative corrections. We categorize the many little Higgs models into two classes based on the structure of the extended electroweak gauge group and examine the experimental signatures that identify the little Higgs mechanism in addition to those that identify the particular little Higgs model. We find that by examining the properties of the new heavy fermion(s) at the LHC, one can distinguish the structure of the top quark mass generation mechanism and test the little Higgs mechanism in the top sector. Similarly, by studying the couplings of the new gauge bosons to the light Higgs boson and to the Standard Model fermions, one can confirm the little Higgs mechanism and determine the structure of the extended electroweak gauge group.
Higgs Particle: The Origin of Mass
Okada, Yasuhiro
2007-11-01
The Higgs particle is a new elementary particle predicted in the Standard Model of the elementary particle physics. It plays a special role in the theory of mass generation of quarks, leptons, and gauge bosons. In this article, theoretical issues on the Higgs mechanism are first discussed, and then experimental prospects on the Higgs particle study at the future collider experiments, LHC and ILC, are reviewed. The Higgs coupling determination is an essential step to establish the mass generation mechanism, which could lead to a deeper understanding of particle physics.
Higgs particle. The origin of mass
International Nuclear Information System (INIS)
Okada, Yasuhiro
2007-01-01
The Higgs particle is a new elementary particle predicted in the Standard Model of the elementary particle physics. It plays a special role in the theory of mass generation of quarks, leptons, and gauge bosons. In this article, theoretical issues on the Higgs mechanism are first discussed, and then experimental prospects on the Higgs particle study at the future collider experiments. LHC and ILC, are reviewed. The Higgs coupling determination is an essential step to establish the mass generation mechanism, which could lead to a deeper understanding of particle physics. (author)
Rajantie, Arttu
2018-03-06
The discovery of the Higgs boson in 2012 and other results from the Large Hadron Collider have confirmed the standard model of particle physics as the correct theory of elementary particles and their interactions up to energies of several TeV. Remarkably, the theory may even remain valid all the way to the Planck scale of quantum gravity, and therefore it provides a solid theoretical basis for describing the early Universe. Furthermore, the Higgs field itself has unique properties that may have allowed it to play a central role in the evolution of the Universe, from inflation to cosmological phase transitions and the origin of both baryonic and dark matter, and possibly to determine its ultimate fate through the electroweak vacuum instability. These connections between particle physics and cosmology have given rise to a new and growing field of Higgs cosmology, which promises to shed new light on some of the most puzzling questions about the Universe as new data from particle physics experiments and cosmological observations become available.This article is part of the Theo Murphy meeting issue 'Higgs cosmology'. © 2018 The Author(s).
Rajantie, Arttu
2018-01-01
The discovery of the Higgs boson in 2012 and other results from the Large Hadron Collider have confirmed the standard model of particle physics as the correct theory of elementary particles and their interactions up to energies of several TeV. Remarkably, the theory may even remain valid all the way to the Planck scale of quantum gravity, and therefore it provides a solid theoretical basis for describing the early Universe. Furthermore, the Higgs field itself has unique properties that may have allowed it to play a central role in the evolution of the Universe, from inflation to cosmological phase transitions and the origin of both baryonic and dark matter, and possibly to determine its ultimate fate through the electroweak vacuum instability. These connections between particle physics and cosmology have given rise to a new and growing field of Higgs cosmology, which promises to shed new light on some of the most puzzling questions about the Universe as new data from particle physics experiments and cosmological observations become available. This article is part of the Theo Murphy meeting issue `Higgs cosmology'.
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
Baryogenesis via Elementary Goldstone Higgs Relaxation
DEFF Research Database (Denmark)
Gertov, Helene; Pearce, Lauren; Sannino, Francesco
2016-01-01
We extend the relaxation mechanism to the Elementary Goldstone Higgs framework. Besides studying the allowed parameter space of the theory we add the minimal ingredients needed for the framework to be phenomenologically viable. The very nature of the extended Higgs sector allows to consider very ...... but radiatively generated, it is possible to generate the observed matter-antimatter asymmetry via the relaxation mechanism....
Veltman, Martinus J. G.
1986-01-01
Reports recent findings related to the particle Higgs boson and examines its possible contribution to the standard mode of elementary processes. Critically explores the strengths and uncertainties of the Higgs boson and proposed Higgs field. (ML)
CHANG, Y. K.; MARTINEZ-BUSTOS, F.; PARK, T. S.; KOKINI, J .L.
1999-01-01
The influence of specific mechanical energy (SME) on cornmeal viscosity during the twin-screw extrusion at feed moisture contents of 25 and 30% and screw speeds in the range from 100 to 500 rpm was measured. Cornmeal was extruded in a co-rotating, intermeshing twin-screw coupled to a slit die rheometer. One approach to the on-line rheological measurement is to use a slit die with the extruder. In the present work it was show that shear viscosity decreased as a function of SME. The viscosity o...
Collider signatures of flavorful Higgs bosons
International Nuclear Information System (INIS)
Altmannshofer, Wolfgang; Eby, Joshua; Gori, Stefania; Lotito, Matteo
2016-01-01
Motivated by our limited knowledge of the Higgs couplings to the first two generation fermions, we analyze the collider phenomenology of a class of two Higgs doublet models (2HDMs) with a nonstandard Yukawa sector. One Higgs doublet is mainly responsible for the masses of the weak gauge bosons and the third-generation fermions, while the second Higgs doublet provides mass for the lighter fermion generations. The characteristic collider signatures of this setup differ significantly from well-studied 2HDMs with natural flavor conservation, flavor alignment, or minimal flavor violation. New production mechanisms for the heavy scalar, pseudoscalar, and charged Higgs involving second-generation quarks can become dominant. The most interesting decay modes include H/A → cc,tc,μμ,τμ and H"± → cb,cs,μν. As a result, searches for low-mass dimuon resonances are currently among the best probes of the heavy Higgs bosons in this setup.
Zhao, Yan; Zhang, Weina; Liu, Xin; Liu, Zhenyu; Wang, Guodong
2016-12-01
In the present work, twin-roll strip casting was carried out to fabricate thin strip of a Mn-N alloyed lean duplex stainless steel with the composition of Fe-19Cr-6Mn-0.4N, in which internal pore defects had been effectively avoided as compared to conventional cast ingots. The solidification structure observed by optical microscope indicated that fine Widmannstatten structure and coarse-equiaxed crystals had been formed in the surface and center, respectively, with no columnar crystal structures through the surface to center of the cast strip. By applying hot rolling and cold rolling, thin sheets with the thickness of 0.5 mm were fabricated from the cast strips, and no edge cracks were formed during the rolling processes. With an annealing treatment at 1323 K (1050 °C) for 5 minutes after cold rolling, the volume fractions of ferrite and austenite were measured to be approximately equal, and the distribution of alloying elements in the strip was further homogenized. The cold-rolled and annealed sheet exhibited an excellent combination of strength and ductility, with the ultimate tensile strength and elongation having been measured to be 1000 MPa and 65 pct, respectively. The microstructural evolution during deformation was investigated by XRD, EBSD, and TEM, indicating that ferrite and austenite had different deformation mechanisms. The deformation of ferrite phase was dominated by dislocation slipping, and the deformation of austenite phase was mainly controlled by martensitic transformation in the sequence of γ→ ɛ-martensite→ α'-martensite, leading to the improvement of strength and plasticity by the so-called transformation-induced plasticity (TRIP) effect. By contrast, lean duplex stainless steels of Fe-21Cr-6Mn-0.5N and Fe-23Cr-7Mn-0.6N fabricated by twin-roll strip casting did not show TRIP effects and exhibited lower strength and elongation as compared to Fe-19Cr-6Mn-0.4N.
Agrawal, Arpana; Silberg, Judy L.; Lynskey, Michael T.; Maes, Hermine H.; Eaves, Lindon J.
2009-01-01
Using twins assessed during adolescence (Virginia Twin Study of Adolescent Behavioral Development: 8–17 years) and followed up in early adulthood (Young Adult Follow-Up, 18–27 years), we tested 13 genetically informative models of co-occurrence, adapted for the inclusion of covariates. Models were fit, in Mx, to data at both assessments allowing for a comparison of the mechanisms that underlie the lifetime co-occurrence of cannabis and tobacco use in adolescence and early adulthood. Both cannabis and tobacco use were influenced by additive genetic (38–81%) and non-shared environmental factors with the possible role of non-shared environment in the adolescent assessment only. Causation models, where liability to use cannabis exerted a causal influence on the liability to use tobacco fit the adolescent data best, while the reverse causation model (tobacco causes cannabis) fit the early adult data best. Both causation models (cannabis to tobacco and tobacco to cannabis) and the correlated liabilities model fit data from the adolescent and young adult assessments well. Genetic correlations (0.59–0.74) were moderate. Therefore, the relationship between cannabis and tobacco use is fairly similar during adolescence and early adulthood with reciprocal influences across the two psychoactive substances. However, our study could not exclude the possibility that ‘gateways’ and ‘reverse gateways’, particularly within a genetic context, exist, such that predisposition to using one substance (cannabis or tobacco) modifies predisposition to using the other. Given the high addictive potential of nicotine and the ubiquitous nature of cannabis use, this is a public health concern worthy of considerable attention. PMID:20047801
Higgs Mass Textures in Flipped SU(5)
Ellis, Jonathan Richard; Rizos, J; Ellis, John
1999-01-01
We analyze the Higgs doublet-triplet mass splitting problem in the version of flipped SU(5) derived from string theory. Analyzing non-renormalizable terms up to tenth order in the superpotential, we identify a pattern of field vev's that keeps one pair of electroweak Higgs doublets light, while all other Higgs doublets and all Higgs triplets are kept heavy, with the aid of the economical missing-doublet mechanism found in the field-theoretical version of flipped SU(5). The solution predicts that second-generation charge -1/3 quarks and charged leptons are much lighter than those in the third generation.
The hunt for the Higgs particle
CERN. Geneva
2007-01-01
With the advent of the LHC, the hunt for the Higgs boson enters its crucial phase. These three lectures will review: the Higgs mechanism; its implementation in the minimal Standard Model; possible alternatives with and without elementary scalar fields; the presently available information on electroweak gauge symmetry breaking and the Higgs particle; the properties of the Higgs boson(s) in the Standard Model and its supersymmetric extensions; the strategies for direct searches at colliders, with emphasis on the LHC, and comments on the possible scenarios that may emerge.
Hwang, Joong-Ki; Son, Il-Heon; Yoo, Jang-Yong; Zargaran, A.; Kim, Nack J.
2015-09-01
The effect of reduction of area (RA), 10%, 20%, and 30%, during wire drawing on the inhomogeneities in microstructure and mechanical properties along the radial direction of Fe-Mn-Al-C twinning-induced plasticity steel has been investigated. After wire drawing, the deformation texture developed into the major and minor duplex fiber texture. However, the texture became more pronounced in both center and surface areas as the RA per pass increased. It also shows that a larger RA per pass resulted in a higher yield strength and smaller elongation than a smaller RA per pass at all strain levels. Although inhomogeneities in microstructure and mechanical properties along the radial direction decreased with increasing RA per pass, there existed an optimum RA per pass for maximum drawing limit. Insufficient penetration of strain from surface to center at small RA per pass (e.g., 10%) and high friction and unsound metal flow at large RA per pass (e.g., 30%) all resulted in heterogeneous microstructure and mechanical properties along the radial direction of drawn wire. On the other hand, 20% RA per pass improved the drawing limit by about 30% as compared to the 10% and 30% RAs per pass.
Energy Technology Data Exchange (ETDEWEB)
Ali, A; Aydin, Z Z [Hamburg Univ. (Germany, F.R.). 2. Inst. fuer Theoretische Physik
1979-01-01
The authors evaluate weak mass mixing among the neutral heavy mesons with a bottom (Q=-1/3) or top (Q=+2/3) quark and CP violation in this framework of six quark V-A models. It is argued that bottom and top mesons may distinguish the Higgs exchange mechanism of CP violation from a complex phase in the quark mass matrix, if bottom and top quark masses are sufficiently different. Estimates of weak mixing and CP violating effects for e/sup +/e/sup -/ experiments at PETRA, PEP and CESR energies are presented.
DEFF Research Database (Denmark)
Sperling, Lene; Tabor, A
2001-01-01
Determination of chorionicity is one of the most important issues in the management of twin pregnancy. Modern ultrasound equipment has made it possible to accurately assess placentation already in the first trimester with the lambda sign. With regard to prenatal diagnosis, it is important to know...... for clinicians caring for twin pregnancies....
Axion and PVLAS Collaboration data in a little Higgs model
International Nuclear Information System (INIS)
Fukuyama, Takeshi; Kikuchi, Tatsuru
2006-01-01
Little Higgs models may provide a solution to the gauge hierarchy problem in the mass of the Higgs boson. In this framework the Higgs boson arises as the pseudo-Nambu-Goldstone (PNG) boson. We show that the lepton triplet introduced in a little Higgs model explains a small mass parameter in the double see-saw mechanism for neutrino masses, and it can also gives an explanation for the axionlike particle recently reported by PVLAS collaboration
Character Profile of the Higgs boson
AUTHOR|(INSPIRE)INSPIRE-00386479; Bentvelsen, Stan; Ferrari, Pamela
Elementary particle physics describes and measures the properties of the smallest, most fundamental particles that make up the universe. The Standard Model of elementary particle physics provides a fundamental description of particles, their dynamics and interactions. The particles embedded into the theory are, a priori, massless, while observed particles have mass. In order to explain the origin of the elementary particle masses, the Brout-Englert-Higgs mechanism is introduced. The mechanism introduces the existence of one real scalar field, with the Higgs boson as excitation, however it does not predict its mass. To verify that the Higgs mechanism is the origin of elementary particle masses is one of the main goals of the Large Hadron Collider (LHC) programs at CERN. Higgs physics at the ATLAS detector has reached an exciting new phase of precision measurements, but the analyses are still mostly set up for conducting searches. The research shown in this thesis has provided measurements in the Higgs sector, ...
Unal, G
2006-01-01
This is a review of Higgs physics at LHC. The topics covered are the search of the Standard Model Higgs boson (with emphasis on the low mass region), the measurements of the Higgs boson properties (mass, width, spin, CP and couplings) and the Higgs sector of the MSSM.
Discovering uncolored naturalness in exotic Higgs decays
International Nuclear Information System (INIS)
Curtin, David; Verhaaren, Christopher B.
2015-01-01
Solutions to the hierarchy problem usually require top partners. In standard SUSY or composite Higgs theories, the partners carry SM color and are becoming increasingly constrained by LHC searches. However, theories like Folded SUSY (FS), Twin Higgs (TH) and Quirky Little Higgs (QLH) introduce uncolored top partners, which can be SM singlets or carry electroweak charge. Their small production cross section left doubt as to whether the LHC can effectively probe such scenarios. Typically, these partners are charged under their own mirror color gauge group. In FS and QLH, the absence of light mirror matter allows glueballs to form at the bottom of the mirror spectrum. This is also the case in some TH realizations. The Higgs can decay to these mirror glueballs, with the glueballs decaying into SM particles with potentially observable lifetimes. We undertake the first detailed study of this glueball signature and quantitatively demonstrate the discovery potential of uncolored naturalness via exotic Higgs decays at the LHC and a potential future 100 TeV collider. Our findings indicate that mirror glueballs are the smoking gun signature of natural FS and QLH type theories, in analogy to tree-level Higgs coupling shifts for the TH. We show that glueball masses in the ∼10–60 GeV mass range are theoretically preferred. Careful treatment of lifetime, mirror-hadronization and nonperturbative uncertainties is required to perform meaningful collider studies. We outline several new search strategies for exotic Higgs decays of the form h→XX→4f at the LHC, with X having lifetimes in the 10μm to km range. We find that FS stops can be probed with masses up to 600 (1100) GeV at the LHC with 300 (3000) fb −1 of data, and TH top partners could be accessible with masses up to 900 (1500) GeV. This makes exotic Higgs decays the prime discovery channel for uncolored naturalness at the LHC.
International Nuclear Information System (INIS)
Chen, Xin
2016-01-01
The updated Higgs measurements in various search channels with ATLAS Run 1 data are reviewed. Both the Standard Model (SM) Higgs results, such as H → γγ, ZZ, WW, ττ, μμ, bb-bar, and Beyond Standard Model (BSM) results, such as the charged Higgs, Higgs invisible decay and tensor couplings, are summarized. Prospects for future Higgs searches are briefly discussed
International Nuclear Information System (INIS)
Zhang, Guoqing; Yuan, Hua; Jiao, Dongling; Li, Zhou; Zhang, Yong; Liu, Zhongwu
2012-01-01
Spray formed T15 high speed steel (HSS) billets were deposited using a state-of-the-art twin-atomiser spray forming facility. The effects of post thermo-mechanical processing (hot isostatic pressing and hot forging) and heat treatment on the microstructure and mechanical properties were investigated. As-deposited billet has a density over 99.3% of the theoretical value and no measurable macro-segregation was observed. The microstructure consists of the equiaxed grains with mean size of ∼18 μm and MC- and M 6 C-type carbides non-uniformly distributed inside the grains and along the grain boundaries. After optimal thermo-mechanical processing and heat treatment, the microstructure was composed of equiaxed fine tempered martensites, and refined M 6 C and MC spherical carbides particles uniformly distributed along the grain boundaries and inside the grains. The hardness reached HRC68 after thermo-mechanical processing, and the corresponding impact toughness and bending strength reached 27 J/cm 2 and 4600 MPa respectively. Although HIP cannot increase the bending strength significantly, it can effectively improve the impact toughness through refining and globurizing carbides.
Epigenetic Epidemiology of Complex Diseases Using Twins
DEFF Research Database (Denmark)
Tan, Qihua
2013-01-01
through multiple epigenetic mechanisms. This paper reviews the new developments in using twins to study disease-related epigenetic alterations, links them to lifetime environmental exposure with a focus on the discordant twin design and proposes novel data-analytical approaches with the aim of promoting...... a more efficient use of twins in epigenetic studies of complex human diseases....
Asner, D.M.; Calancha, C.; Fujii, K.; Graf, N.; Haber, H.E.; Ishikawa, A.; Kanemura, S.; Kawada, S.; Kurata, M.; Miyamoto, A.; Neal, H.; Ono, H.; Potter, C.; Strube, J.; Suehara, T.; Tanabe, T.; Tian, J.; Tsumura, J.; Watanuki, S.; Weiglein, G.; Yagyu, K.; Yokoya, H.
2013-01-01
The ILC Higgs White Paper is a review of Higgs Boson theory and experiment at the International Linear Collider (ILC). Theory topics include the Standard Model Higgs, the two-Higgs doublet model, alternative approaches to electroweak symmetry breaking, and precision goals for Higgs boson experiments. Experimental topics include the measurement of the Higgs cross section times branching ratio for various Higgs decay modes at ILC center of mass energies of 250, 500, and 1000 GeV, and the extraction of Higgs couplings and the total Higgs width from these measurements. Luminosity scenarios based on the ILC TDR machine design are used throughout. The gamma-gamma collider option at the ILC is also discussed.
Higgs inflation and the cosmological constant
Energy Technology Data Exchange (ETDEWEB)
Jegerlehner, Fred [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2014-02-15
The Higgs not only induces the masses of all SM particles, the Higgs, given its special mass value, is the natural candidate for the inflaton and in fact is ruling the evolution of the early universe, by providing the necessary dark energy which remains the dominant energy density. SM running couplings not only allow us to extrapolate SM physics up to the Planck scale, but equally important they are triggering the Higgs mechanism. This is possible by the fact that the bare mass term in the Higgs potential changes sign at about μ{sub 0}≅1.40 x 10{sup 16} GeV and in the symmetric phase is enhanced by quadratic terms in the Planck mass. Such a huge Higgs mass term is able to play a key role in triggering inflation in the early universe. In this article we extend our previous investigation by working out the details of a Higgs inflation scenario. We show how different terms contributing to the Higgs Lagrangian are affecting inflation. Given the SM and its extrapolation to scales μ>μ{sub 0} we find a calculable cosmological constant V(0) which is weakly scale dependent and actually remains large during inflation. This is different to the Higgs fluctuation field dependent ΔV(φ), which decays exponentially during inflation, and actually would not provide a sufficient amount of inflation. The fluctuation field has a different effective mass which shifts the bare Higgs transition point to a lower value μ'{sub 0} ≅7.7 x 10{sup 14} GeV. The vacuum energy V(0) being proportional to M{sub Pl}{sup 4} has a coefficient which vanishes near the Higgs transition point, such that the bare and the renormalized cosmological constant match at this point. The role of the Higgs in reheating and baryogenesis is emphasized.
Exciting the Vacuum: Possible Manifestations of the Higgs Particle at the LHC
International Nuclear Information System (INIS)
Kaplan, David
2009-01-01
The Higgs boson is the particle most anticipated at the LHC. However, there is currently no leading theory of electroweak symmetry breaking (and the 'Higgs mechanism'). The many possibilities suggest many ways the Higgs could appear in the detectors, some of which require non-standard search methods. I will review the current state of beyond the standard model physics and the implication for Higgs physics. I then discuss some non-standard Higgs decays and suggest (perhaps naive) new experimental strategies for detecting the Higgs in such cases. In some models, while part of the new physics at the weak scale would be visible, the Higgs would be nearly impossible to detect.
Roberts, Alex
2016-08-01
Recently, a new framework for describing the multiverse has been proposed which is based on the principles of quantum mechanics. The framework allows for well-defined predictions, both regarding global properties of the universe and outcomes of particular experiments, according to a single probability formula. This provides complete unification of the eternally inflating multiverse and many worlds in quantum mechanics. We elucidate how cosmological parameters can be calculated in this framework, and study the probability distribution for the value of the cosmological constant. We consider both positive and negative values, and find that the observed value is consistent with the calculated distribution at an order of magnitude level. In particular, in contrast to the case of earlier measure proposals, our framework prefers a positive cosmological constant over a negative one. These results depend only moderately on how we model galaxy formation and life evolution therein. We explore supersymmetric theories in which the Higgs mass is boosted by the non-decoupling D-terms of an extended U(1) X gauge symmetry, defined here to be a general linear combination of hypercharge, baryon number, and lepton number. Crucially, the gauge coupling, gX, is bounded from below to accommodate the Higgs mass, while the quarks and leptons are required by gauge invariance to carry non-zero charge under U(1)X. This induces an irreducible rate, sigmaBR, for pp → X → ll relevant to existing and future resonance searches, and gives rise to higher dimension operators that are stringently constrained by precision electroweak measurements. Combined, these bounds define a maximally allowed region in the space of observables, (sigmaBR, mX), outside of which is excluded by naturalness and experimental limits. If natural supersymmetry utilizes non-decoupling D-terms, then the associated X boson can only be observed within this window, providing a model independent 'litmus test' for this broad
Higgs bosons in extra dimensions
Quiros, Mariano
2015-05-01
In this paper, motivated by the recent discovery of a Higgs-like boson at the Large Hadron Collider (LHC) with a mass mH≃125 GeV, we review different models where the hierarchy problem is solved by means of a warped extra dimension. In the Randall-Sundrum (RS) model electroweak observables provide very strong bounds on the mass of KK modes which motivates extensions to overcome this problem. Two extensions are briefly discussed. One particular extension is based on the deformation of the metric such that it strongly departs from the AdS5 structure in the IR region while it goes asymptotically to AdS5 in the UV brane. This model has the IR brane close to a naked metric singularity (which is outside the physical interval) characteristic of soft-walls constructions. The proximity of the singularity provides a strong wave function renormalization for the Higgs field which suppresses the T and S parameters. The second class of considered extensions are based on the introduction of an extra gauge group in the bulk such that the custodial SU(2)R symmetry is gauged and protects the T parameter. By further enlarging the bulk gauge symmetry one can find models where the Higgs is identified with the fifth component of gauge fields and for which the Higgs potential along with the Higgs mass can be dynamically determined by the Coleman-Weinberg mechanism.
Higgs particles in the standard model and supersymmetric theories
International Nuclear Information System (INIS)
Muehlleitner, M.M.
2000-08-01
This thesis presents a theoretical analysis of the properties of the Higgs bosons in the standard model (SM) and the minimal supersymmetric extension (MSSM), which can be investigated at the LHC and e + e - linear colliders. The final goal is the reconstruction of the Higgs potential and thus the verification of the Higgs mechanism. MSSM Higgs boson production processes at future γγ colliders are calculated in several decay channels. Heavy scalar and pseudoscalar Higgs bosons can be discovered in the bb final state in the investigated mass range 200 to 800 GeV for moderate and large values of tanβ. The τ + τ - channel provides a heavy Higgs boson discovery potential for large values of tanβ. Several mechanisms that can be exploited at e + e - linear colliders for the measurement of the lifetime of a SM Higgs boson in the intermediate mass range are analysed. In the WW mode, the lifetime of Higgs scalars with masses below ∝160 GeV can be determined with an error less than 10%. The reconstruction of the Higgs potential requires the measurement of the Higgs self-couplings. The SM and MSSM trilinear Higgs self-couplings are accessible in double and triple Higgs production. A theoretical analysis is presented in the relevant channels at the LHC and e + e - linear colliders. For high luminosities, the SM trilinear Higgs self-coupling can be measured with an accuracy of 20% at a 500 GeV e + e - linear collider. The MSSM coupling among three light Higgs bosons has to be extracted from continuum production. The other trilinear Higgs couplings are measurable in a restricted range of the MSSM parameter space. At the LHC, the Hhh coupling can be probed in resonant decays. (orig.)
Mechanism of the 2016 giant twin glacier collapse in Aru range, Tibet
Gilbert, A.; Leinss, S.; Kääb, A.; Kargel, J. S.; Yao, T.; Gascoin, S.; Leonard, G. J.; Berthier, E.; Karki, A.
2017-12-01
In northwestern Tibet (34.0°N, 82.2°E) near lake Aru Co, the entire ablation area of two unnamed glaciers (Aru-1 and Aru-2) suddenly collapsed on 17 July 2016 and 21 September 2016 and transformed into a mass flow that ran out over a distance of over several km, killing nine people. These two events are unique and defined a new kind of glacier behavior almost never observed before. The only similar event currently documented is the 2002 Kolka Glacier mass flow (Caucasus Mountains). Using remote sensing observations and 3D thermo-mechanical modeling of the two glaciers, we reconstructed glacier thermal regime, thickness, basal friction evolution and ice damaging state prior to the collapse. We show that frictional change leading to the collapse occurred in the temperate areas of a polythermal structure that is likely close to equilibrium with the local climate. The collapses were driven by a fast and sustained friction change in the temperate part of the glacier for which the glacier shape was not able to adjust due to the cold-based parts providing strong resisting force to sliding. This led to high stresses on the cold margins of the glacier where ice deformation became partially accommodated by fracturing until the final collapse occurred. Field investigations reveal that those two glaciers are flowing on a soft and fine-grained sedimentary lithology prone to landslide activity in the presence of water. This suggests that fast friction change in the temperate part of the glacier is linked to shear strength weakening in the sediment and till underneath the glacier in response to increasing water pore pressure at the glacier base. The Kolka Glacier mass flow also occurred on pyroclastic rocks well known for their landslide activities. This suggests that the three gigantic glacier collapses documented to date involve specific bedrock lithology where failure is driven by shear strength weakening in the glacier till in a landslide-like process. Contrary to a
Energy Technology Data Exchange (ETDEWEB)
Holzner, André G., E-mail: andre.georg.holzner@cern.ch [University of California at San Diego (United States); Collaboration: on behalf of the CMS collaboration
2016-12-15
This article reviews recent measurements of the properties of the standard model (SM) Higgs boson using data recorded with the CMS detector at the LHC: its mass, width and couplings to other SM particles. We also summarise highlights from searches for new physical phenomena in the Higgs sector as they are proposed in many extensions of the SM: flavour violating and invisible decay modes, resonances decaying into Higgs bosons and searches for additional Higgs bosons.
Smart, Ben; The ATLAS collaboration
2017-01-01
The High-Luminosity LHC will prove a challenging environment to work in, with for example $=200$ expected. It will however also provide great opportunities for advancing studies of the Higgs boson. The ATLAS detector will be upgraded, and Higgs prospects analyses have been performed to assess the reach of ATLAS Higgs studies in the HL-LHC era. These analyses are presented, as are Run-2 ATLAS di-Higgs analyses for comparison.
Higgs physics as a proble of new physics
International Nuclear Information System (INIS)
KANEMURA, S.
2014-01-01
The discovery of the Higgs boson at the LHC has opened the door to clarifying the mechanism of electroweak symmetry breaking and the origin of particle masses. The Higgs sector in the SM is the simplest possible one but is not based on a fundamental theoretical principle, so that there is also the possibility of non-minimal Higgs sectors. While the standard model is not in contradiction with current LHC data within the errors, many extended Higgs sectors can also reproduce these data. An extended Higgs sector often appears in new physics models beyond the standard model, so that this allows to determine new physics from the Higgs sector. In this talk, we discuss various aspects of extended Higgs sectors, in particular their phenomenological properties and testability at future experiments, as the International Linear Collider.
Gunion, John F; Haber, Howard E; Kane, Gordon L
1989-01-01
The Higgs Hunter's Guide is a definitive and comprehensive guide to the physics of Higgs bosons. In particular, it discusses the extended Higgs sectors required by those recent theoretical approaches that go beyond the Standard Model, including supersymmetry and superstring-inspired models.
International Nuclear Information System (INIS)
Mack, C; Sathyanarayana, S; Weiss, P; Mikonsaari, I; Hübner, C; Henning, F; Elsner, P
2012-01-01
1, 3 and 5 wt.% multi walled carbon nanotubes (MWCNT) reinforced polycarbonate (PC) composites were processed in a twin-screw extruder (L/D=52) with two different screw speeds, throughputs and screw configurations. Extruded strands were characterized for dispersion and measurement of electrical resistivities while the pelletized extrudates were injection molded to produce samples for mechanical and further electrical property measurements. The absolute resistance of the melt was recorded with an online melt resistance setup developed by our group. The volume resistivity of pure PC (10 17 Ω.m) was lowered to 10 4 − 10 5 Ω.m on an injection molded PC-1 wt. % MWCNT composite. 3 wt.% MWCNT incorporated composites showed volume resistivity less than 1 Ω.m independent of process conditions. At lower filler contents the volume resistivity of injection molded samples were higher than those observed on the extruded strands and this effect diminished with increasing MWCNT loadings; owing to the loss of CNT network contacts due to shear induced filler orientation and core-skin effects. The quality of dispersion was exceptional for all filler concentrations at any process condition owing to the affinity of MWCNT towards PC due to the lower interfacial energy difference between the reactants and high polarity of PC. The modulus and strength of the composites increased with filler addition, however at 5 wt.% filler loading the strength of the composites processed with lower SMEs was less than that observed on the 1 wt.% MWCNT reinforced PC composite. The elongation of the composites at maximum tensile strength were comparable to that of neat PC except for composites with 5 wt.% MWCNT loading processed with lower SMEs. Composites with identical filler loadings which were processed with higher SMEs showed higher notched impact strength values principally because of the ability of very well dispersed filler fractions to inhibit crack propagation. The significance of the
Standard model Higgs physics at colliders
International Nuclear Information System (INIS)
Rosca, A.
2007-01-01
In this report we briefly review the experimental status and prospects to verify the Higgs mechanism of spontaneous symmetry breaking. The focus is on the most relevant aspects of the phenomenology of the Standard Model Higgs boson at current (Tevatron) and future (Large Hadron Collider, LHC and International Linear Collider, ILC) particle colliders. We review the Standard Model searches: searches at the Tevatron, the program planned at the LHC and prospects at the ILC. Emphasis is put on what follows after a candidate discovery at the LHC: the various measurements which are necessary to precisely determine what the properties of this Higgs candidate are. (author)
2016-01-01
A subject of major importance in fundamental physics is the investigation of the origin of Electroweak Symmetry Breaking. The mechanism of mass generation through the spontaneous breaking of a gauge symmetry is called the Brout-Englert-Higgs mechanism and is associated with the appearance of a physical scalar boson. The discovery announced at CERN on 4th July 2012 by the ATLAS and CMS Collaborations of a boson at a mass close to 125 GeV/c2, compatible with this scalar boson of the Standard Model, the so-called Higgs boson, mainly in γγ, ZZ and WW decay modes, with compatible evidence also found at Fermilab in the bb mode, changed the landscape. This important discovery was acknowledged as decisive for the attribution of the 2013 Nobel Prize in Physics awarded jointly to François Englert and Peter Higgs . This 7th workshop of the "Higgs Hunting" series organized in Paris on August 31 - September 2, 2016 will discuss the developments of LHC run 2 analyses, detailed studies of the new boson and possible de...
Directory of Open Access Journals (Sweden)
Magalas L.B.
2015-06-01
Full Text Available In this work, we present a novel Hilbert-twin method to compute an envelope and the logarithmic decrement, δ, from exponentially damped time-invariant harmonic strain signals embedded in noise. The results obtained from five computing methods: (1 the parametric OMI (Optimization in Multiple Intervals method, two interpolated discrete Fourier transform-based (IpDFT methods: (2 the Yoshida-Magalas (YM method and (3 the classic Yoshida (Y method, (4 the novel Hilbert-twin (H-twin method based on the Hilbert transform, and (5 the conventional Hilbert transform (HT method are analyzed and compared. The fundamental feature of the Hilbert-twin method is the efficient elimination of intrinsic asymmetrical oscillations of the envelope, aHT (t, obtained from the discrete Hilbert transform of analyzed signals. Excellent performance in estimation of the logarithmic decrement from the Hilbert-twin method is comparable to that of the OMI and YM for the low- and high-damping levels. The Hilbert-twin method proved to be robust and effective in computing the logarithmic decrement and the resonant frequency of exponentially damped free decaying signals embedded in experimental noise. The Hilbert-twin method is also appropriate to detect nonlinearities in mechanical loss measurements of metals and alloys.
DEFF Research Database (Denmark)
Giardino, P. P.; Kannike, K.; Masina, I.
2014-01-01
We perform a state-of-the-art global fit to all Higgs data. We synthesise them into a 'universal' form, which allows to easily test any desired model. We apply the proposed methodology to extract from data the Higgs branching ratios, production cross sections, couplings and to analyse composite...... Higgs models, models with extra Higgs doublets, supersymmetry, extra particles in the loops, anomalous top couplings, and invisible Higgs decays into Dark Matter. Best fit regions lie around the Standard Model predictions and are well approximated by our 'universal' fit. Latest data exclude the dilaton...... as an alternative to the Higgs, and disfavour fits with negative Yukawa couplings. We derive for the first time the SM Higgs boson mass from the measured rates, rather than from the peak positions, obtaining M-h = 124.4 +/- 1.6 GeV....
Giudice, Gian F
2011-01-01
We consider a simple extension of the Standard Model Higgs inflation with one new real scalar field which preserves unitarity up to the Planck scale. The new scalar field (called sigma) completes in the ultraviolet the theory of Higgs inflation by linearizing the Higgs kinetic term in the Einstein frame, just as the non-linear sigma model is unitarized into its linear version. The unitarity cutoff of the effective theory, obtained by integrating out the sigma field, varies with the background value of the Higgs field. In our setup, both the Higgs field and the sigma field participate in the inflationary dynamics, following the flat direction of the potential. We obtain the same slow-roll parameters and spectral index as in the original Higgs inflation but we find that the Hubble rate during inflation depends not only on the Higgs self-coupling, but also on the unknown couplings of the sigma field.
International Nuclear Information System (INIS)
Giudice, Gian F.; Lee, Hyun Min
2011-01-01
We consider a simple extension of the Standard Model Higgs inflation with one new real scalar field which preserves unitarity up to the Planck scale. The new scalar field (called sigma) completes in the ultraviolet the theory of Higgs inflation by linearizing the Higgs kinetic term in the Einstein frame, just as the non-linear sigma model is unitarized into its linear version. The unitarity cutoff of the effective theory, obtained by integrating out the sigma field, varies with the background value of the Higgs field. In our setup, both the Higgs field and the sigma field participate in the inflationary dynamics, following the flat direction of the potential. We obtain the same slow-roll parameters and spectral index as in the original Higgs inflation but we find that the Hubble rate during inflation depends not only on the Higgs self-coupling, but also on the unknown couplings of the sigma field.
Higgs Production in a Warped Extra Dimension
Energy Technology Data Exchange (ETDEWEB)
Carena, Marcela [Chicago U., EFI; Casagrande, Sandro [Munich, Tech. U., Universe; Goertz, Florian [Zurich, ETH; Haisch, Ulrich [Oxford U., Theor. Phys.; Neubert, Matthias [Mainz U., Inst. Phys.
2012-04-01
Measurements of the Higgs-boson production cross section at the LHC are an important tool for studying electroweak symmetry breaking at the quantum level, since the main production mechanism gg-->h is loop-suppressed in the Standard Model (SM). Higgs production in extra-dimensional extensions of the SM is sensitive to the Kaluza-Klein (KK) excitations of the quarks, which can be exchanged as virtual particles in the loop. In the context of the minimal Randall-Sundrum (RS) model with bulk fields and a brane-localized Higgs sector, we derive closed analytical expressions for the gluon-gluon fusion process, finding that the effect of the infinite tower of virtual KK states can be described in terms of a simple function of the fundamental (5D) Yukawa matrices. Given a specific RS model, this will allow one to easily constrain the parameter space, once a Higgs signal has been established. We explain that discrepancies between existing calculations of Higgs production in RS models are related to the non-commutativity of two limits: taking the number of KK states to infinity and removing the regulator on the Higgs-boson profile, which is required in an intermediate step to make the relevant overlap integrals well defined. Even though the one-loop gg-->h amplitude is finite in RS scenarios with a brane-localized Higgs sector, it is important to introduce a consistent ultraviolet regulator in order to obtain the correct result.
A theoretical limit on the Higgs mass
International Nuclear Information System (INIS)
Temiraliev, A.T.
2007-01-01
Full text: The standard model of particle physics, which describes masses through the Higgs mechanism, contains parameters - such as particle masses - whose origins are still unknown and which cannot be exactly predicted, but whose values are constrained through their interactions. In particular, the masses of the top quark and W boson constrain the mass of the long-hypothesized, but thus far not observed, Higgs boson. Several more or less precise arguments can set the upper limit for a standard model Higgs particle. All of them follows the line that the standard model breaks down of the Higgs mass is pushed too far upwards. The theoretical bounds will be reviewed. With gauge-top quark Yukawa coupling unification the standard model Higgs boson mass is estimated to be about 135 GeV. In the article will be consider an approximation of 4-fermion interactions. And as a result, the most likely Higgs mass is 150 GeV. The upper limit on the Higgs mass at the 90 % confidence level is about 250 GeV
Discovery of the Higgs boson and beyond
International Nuclear Information System (INIS)
Godbole, Rohini
2014-01-01
This talk is about the Higgs mechanism, the theoretical discovery of which, was awarded the 2013 Nobel Prize. It also discusses the discovery of the Higgs boson at the large hadron collider which provided the experimental proof that made the Nobel prize possible. It covers the implications of these for the quest of unravelling the fundamental laws of nature which seem to govern both, the behavior of the ultra small (subatomic particles) and the ultra large (the cosmos)
Little Higgs models and T parity
International Nuclear Information System (INIS)
Perelstein, Maxim
2006-01-01
Little Higgs models are an interesting extension of the standard model at the TeV scale. They provide a simple and attractive mechanism of electroweak symmetry breaking. We review one of the simplest models of this class, the littlest Higgs model, and its extension with T parity. The model with T parity satisfies precision electroweak constraints without fine-tuning, contains an attractive dark matter candidate, and leads to interesting phenomenology at the Large Hadron Collider (LHC). (author)
Probing the Higgs vacuum with general relativity
Mannheim, Philip D.; Kazanas, Demosthenes
1991-01-01
It is shown that the structure of the Higgs vacuum can be revealed in gravitational experiments which probe the Schwarzschild geometry to only one order in MG/r beyond that needed for the classical tests of general relativity. The possibility that deviations from the conventional geometry are at least theoretically conceivable is explored. The deviations obtained provide a diagnostic test for searching for the existence of macroscopic scalar fields and open up the possiblity for further exploring the Higgs mechanism.
Effective action and cluster properties of the abelian Higgs model
Energy Technology Data Exchange (ETDEWEB)
Balaban, T; Imbrie, J Z; Jaffe, A
1988-02-01
We continue our program to establish the Higgs mechanism and mass gap for the abelian Higgs model in two and three dimensions. We develop a multiscale cluster expansion for the high frequency modes of the theory, within a framework of iterated renormalization group transformations. The expansions yield decoupling properties needed for a proof of exponential decay of correlations. The result of this analysis is a gauge invariant unit lattice theory with a deep Higgs potential of the shape required to exhibit the Higgs mechanism.
Radiative corrections to the triple Higgs coupling in the inert Higgs doublet model
International Nuclear Information System (INIS)
Arhrib, Abdesslam; Benbrik, Rachid; Falaki, Jaouad El; Jueid, Adil
2015-01-01
We investigate the implication of the recent discovery of a Higgs-like particle in the first phase of the LHC Run 1 on the Inert Higgs Doublet Model (IHDM). The determination of the Higgs couplings to SM particles and its intrinsic properties will get improved during the new LHC Run 2 starting this year. The new LHC Run 2 would also shade some light on the triple Higgs coupling. Such measurement is very important in order to establish the details of the electroweak symmetry breaking mechanism. Given the importance of the Higgs couplings both at the LHC and e + e − Linear Collider machines, accurate theoretical predictions are required. We study the radiative corrections to the triple Higgs coupling hhh and to hZZ, hWW couplings in the context of the IHDM. By combining several theoretical and experimental constraints on parameter space, we show that extra particles might modify the triple Higgs coupling near threshold regions. Finally, we discuss the effect of these corrections on the double Higgs production signal at the e + e − LC and show that they can be rather important.
DEFF Research Database (Denmark)
Duan, Haiping; Ning, Feng; Zhang, Dongfeng
2013-01-01
In 1998, the Qingdao Twin Registry was initiated as the main part of the Chinese National Twin Registry. By 2005, a total of 10,655 twin pairs had been recruited. Since then new twin cohorts have been sampled, with one longitudinal cohort of adolescent twins selected to explore determinants of me...
Frequently Asked Questions: The Higgs!
CERN Bulletin
2012-01-01
Why have we tried so hard to find the Higgs particle? How does the Higgs mechanism work? What is the difference in physics between strong evidence and a discovery? Why do physicists speak in terms of "sigmas"? Find out here! Why have we tried so hard to find the Higgs particle? Because it could be the answer to the question: how does Nature decide whether or not to assign mass to particles? All the fundamental particles making up matter – the electron, the quarks, etc. – have masses. Moreover, quantum physics requires that forces are also carried by particles. The W and Z particles that carry the weak force responsible for radioactivity must also have masses, whereas the photon, the carrier of the electromagnetic force, has no mass at all. This is the root of the “Higgs problem”: how to give masses to the fundamental particles and break the symmetry between the massive W and Z and the massless photon? Just assigning masses by hand...
Molecular dynamics simulation of deformation twin in rocksalt vanadium nitride
International Nuclear Information System (INIS)
Fu, Tao; Peng, Xianghe; Zhao, Yinbo; Li, Tengfei; Li, Qibin; Wang, Zhongchang
2016-01-01
We perform molecular dynamics simulation of nano-indentation with a cylindrical indenter to investigate the formation mechanism of deformation twin in vanadium nitride (VN) with a rocksalt structure. We find that the deformation twins occur during the loading stage, and subsequently conduct a systematic analysis of nucleation, propagation and thickening of a deformation twin. We find that the nucleation of a partial dislocation and its propagation to form a stacking fault are premise of deformation twin formation. The sequential nucleation and propagation of partial dislocation on adjacent parallel {111} planes are found to cause the thickening of the deformation twin. Moreover, the deformation twins can exist in VN at room temperature. - Highlights: • MD simulations of indentation are performed to study the deformation twin in VN. • The deformation twins can occur in VN during the loading stage. • The nucleation, propagation and thickening of a deformation twin are analyzed. • The deformation twins can exist in VN at room temperature.
Fetal growth disorders in twin gestations.
LENUS (Irish Health Repository)
Breathnach, Fionnuala M
2012-06-01
Twin growth is frequently mismatched. This review serves to explore the pathophysiologic mechanisms that underlie growth aberrations in twin gestations, the prenatal recognition of abnormal twin growth, and the critical importance of stratifying management of abnormal twin growth by chorionicity. Although poor in utero growth of both twins may reflect maternal factors resulting in global uteroplacental dysfunction, discordant twin growth may be attributed to differences in genetic potential between co-twins, placental dysfunction confined to one placenta only, or one placental territory within a shared placenta. In addition, twin-twin transfusion syndrome represents a distinct entity of which discordant growth is a common feature. Discordant growth is recognized as an independent risk factor for adverse perinatal outcome. Intertwin birth weight disparity of 18% or more should be considered to represent a discordance threshold, which serves as an independent risk factor for adverse perinatal outcome. At this cutoff, perinatal morbidity is found to increase both for the larger and the smaller twin within a discordant pair. There remains uncertainty surrounding the sonographic parameters that are most predictive of discordance. Although heightening of fetal surveillance in the face of discordant twin growth follows the principles applied to singleton gestations complicated by fetal growth restriction, the timing of intervention is largely influenced by chorionicity.
Partially natural Two Higgs Doublet Models
Energy Technology Data Exchange (ETDEWEB)
Draper, Patrick [Department of Physics, University of California,Broida Hall, Santa Barbara, CA 93106 (United States); Haber, Howard E. [Santa Cruz Institute for Particle Physics, University of California,1156 High Street, Santa Cruz, CA 95064 (United States); Kavli Institute for Theoretical Physics, University of California,Kohn Hall, Santa Barbara, CA 93106 (United States); Ruderman, Joshua T. [Center for Cosmology and Particle Physics, Department of Physics, New York University,4 Washington Pl. New York, NY 10003 (United States)
2016-06-21
It is possible that the electroweak scale is low due to the fine-tuning of microscopic parameters, which can result from selection effects. The experimental discovery of new light fundamental scalars other than the Standard Model Higgs boson would seem to disfavor this possibility, since generically such states imply parametrically worse fine-tuning with no compelling connection to selection effects. We discuss counterexamples where the Higgs boson is light because of fine-tuning, and a second scalar doublet is light because a discrete symmetry relates its mass to the mass of the Standard Model Higgs boson. Our examples require new vectorlike fermions at the electroweak scale, and the models possess a rich electroweak vacuum structure. The mechanism that we discuss does not protect a small CP-odd Higgs mass in split or high-scale supersymmetry-breaking scenarios of the MSSM due to an incompatibility between the discrete symmetries and holomorphy.
International Nuclear Information System (INIS)
Wang Yinong; Kang, Suk Bong; Cho, Jaehyung
2011-01-01
Research highlights: → This work, taking AM30 + 0.2Ca alloy as experimental material, will provide some new information as follows: one is microstructural difference between twin roll cast and ingot cast AM31-0.2Ca alloy. The other is the comparison of tensile properties after warm rolling and annealing. Suggesting the possibility of the development of wrought magnesium alloy sheets by strip casting. - Abstract: Microstructural evolution and mechanical properties of twin roll cast (TRC) Mg-3.3 wt.%Al-0.8 wt.%Mn-0.2 wt.%Ca (AM31 + 0.2Ca) alloy strip during warm rolling and subsequent annealing were investigated in this paper. The as-TRC alloy strip shows columnar dendrites in surface and equiaxed dendrites in center regions, as well as finely dispersed primary Al 8 Mn 5 particles on interdendritic boundaries which result in the beneficial effect on microstructural refinement of strip casting. The warm rolled sheets show intensively deformed band or shear band structures, as well as finely and homogeneously dispersed Al-Mn particles. No evident dynamic recrystallization (DRX) takes place during warm rolling process, which is more likely attributed to the finely dispersed particle and high solid solution of Al and Mn atoms in α-Mg matrix. After annealing at 350 deg. C for 1 h, the warm rolled TRC sheets show fine equiaxed grains around 7.8 μm in average size. It has been shown that the present TRC alloy sheet has superior tensile strength and comparative elongation compared to commercial ingot cast (IC) one, suggesting the possibility of the development of wrought magnesium alloy sheets by twin roll strip casting processing. The microstructural evolution during warm rolling and subsequent annealing as well as the resulting tensile properties were analyzed and discussed.
International Nuclear Information System (INIS)
Dawson, S.; Haber, H.E.; Rindani, S.D.
1989-05-01
This is the summary report of the Higgs Boson Working Group. We discuss a variety of search techniques for a Higgs boson which is lighter than the Z. The processes K → πH, η prime → ηH,Υ → Hγ and e + e - → ZH are examined with particular attention paid to theoretical uncertainties in the calculations. We also briefly examine new features of Higgs phenomenology in a model which contains Higgs triplets as well as the usual doublet of scalar fields. 33 refs., 6 figs., 1 tab
The Effective Chiral Lagrangian for a Light Dynamical "Higgs Particle"
Alonso, R.; Merlo, L.; Rigolin, S.; Yepes, J.
2013-01-01
We generalize the basis of CP-even chiral effective operators describing a dynamical Higgs sector, to the case in which the Higgs-like particle is light. Gauge and gauge-Higgs operators are considered up to mass dimension five. This analysis completes the tool needed to explore at leading order the connection between linear realizations of the electroweak symmetry breaking mechanism - whose extreme case is the Standard Model - and non-linear realizations with a light Higgs-like particle present. It may also provide a model-independent guideline to explore which exotic gauge-Higgs couplings may be expected, and their relative strength to Higgsless observable amplitudes. With respect to fermions, the analysis is reduced by nature to the consideration of those flavour-conserving operators that can be written in terms of pure-gauge or gauge-Higgs ones via the equations of motion, but for the standard Yukawa-type couplings.
Composite Higgs Models and the tt-bar H Channel
International Nuclear Information System (INIS)
Carmona, A.; Chala, M.; Santiago, J.
2012-01-01
Despite its suppressed couplings to Standard Model particles, a composite Higgs with mass m H = 125 GeV and a moderate degree of compositeness can be consistent with current Higgs searches, including a sizable enhancement in the H → γγ channel. Heavy resonances common to many composite Higgs models can mediate new Higgs production mechanisms. In particular, the tt-bar H channel can be accessible at the LHC in these models through the exchange of colored vector and fermion resonances. In this case, the tt-bar H channel is not a direct measure of the top Yukawa coupling. (authors)
Baryogenesis and Dark Matter through a Higgs Asymmetry
Servant, Geraldine
2013-01-01
In addition to explaining the masses of elementary particles, the Higgs boson may have far-reaching implications for the generation of the matter content in the Universe. For instance, the Higgs plays a key role in two main theories of baryogenesis, namely electroweak baryogenesis and leptogenesis. In this letter, we propose a new cosmological scenario where the Higgs chemical potential mediates asymmetries between visible and dark matter sectors, either generating a baryon asymmetry from a dark matter asymmetry or vice-versa. We illustrate this mechanism with a simple model with two new fermions coupled to the Higgs and discuss associated signatures.
Baryogenesis and dark matter through a Higgs asymmetry.
Servant, Géraldine; Tulin, Sean
2013-10-11
In addition to explaining the masses of elementary particles, the Higgs boson may have far-reaching implications for the generation of the matter content in the Universe. For instance, the Higgs boson plays a key role in two main theories of baryogenesis, namely, electroweak baryogenesis and leptogenesis. In this Letter, we propose a new cosmological scenario where the Higgs chemical potential mediates asymmetries between visible and dark matter sectors, either generating a baryon asymmetry from a dark matter asymmetry or vice versa. We illustrate this mechanism with a simple model with two new fermions coupled to the Higgs boson and discuss the associated signatures.
Segal, Nancy L
2016-08-01
The interrelatedness between twin research and the arts is explored via a new play about a famous case. In the 1960s, identical twin David Bruce Reimer was accidentally castrated as an infant during circumcision to correct a urinary problem. The decision to raise him as a girl, and the consequences of that decision, are explored in the new theatrical production of Boy. Other examples of the arts mirroring science, and vice versa, are described. Next, brief reviews and summaries of twin research on sexual orientation, 1860s' knowledge of placental arrangements and twinning mechanisms, and genes underlying multiple birth conception and fertility related measures are provided. This article concludes with a look at twins on college campuses and the identification of individuals by their brain waves. A correction and clarification regarding my article on the Brazilian Twin Registry in the last issue of THG (Segal, 2016) is also provided.
Directory of Open Access Journals (Sweden)
Y. K. CHANG
1999-09-01
Full Text Available The influence of specific mechanical energy (SME on cornmeal viscosity during the twin-screw extrusion at feed moisture contents of 25 and 30% and screw speeds in the range from 100 to 500 rpm was measured. Cornmeal was extruded in a co-rotating, intermeshing twin-screw coupled to a slit die rheometer. One approach to the on-line rheological measurement is to use a slit die with the extruder. In the present work it was show that shear viscosity decreased as a function of SME. The viscosity of cornmeal at the exit die was influenced by screw speed, rate of total mass flow, mass temperature inside the extruder and SME. An increase in screw speed resulted in an increase in SME and a decrease in viscosity. A reduction in slit die height and an increase in screw speed and mass temperature led to a remarkable macromolecular degradation of the starch, as evidenced by the decrease in viscosity.
Salam-Weinberg symmetry breaking with superheavy Higgs particles
International Nuclear Information System (INIS)
Misra, S.P.
1986-09-01
We discuss here the possibility of the breaking of the Salam-Weinberg symmetry by Higgs particles which are superheavy. The symmetry-breaking is associated with a nonzero vacuum expectation value of fermion condensates. This mechanism, if operative in nature, will imply the absence of Higgs particles at the weak scale. (author)
Perspectives of SM Higgs measurements at the LHC
Indian Academy of Sciences (India)
learned at the LHC about the production and decays of a SM Higgs boson. 2. The 'well' known. Recent LHC Higgs cross-section estimates for the different production mechanisms can be found in [8]. By far the largest contribution to the cross-section comes from the gluon– gluon fusion process to top quarks [9], which is ...
2008-01-01
Quantum physicists think they know the answer. Probabilistic calculations reveal than the data provided by previous experiments has been miscalculated and that the Higgs boson has in fact been discovered. Weird! The Higgs boson is the only particle predicted by the Standard Model that hasn't been discovered yet.
Stefania Pandolfi
2016-01-01
CERN celebrated the fourth anniversary of the historical Higgs boson announcement with special pizzas. 400 pizzas were served on Higgs pizza day in Restaurant 1 at CERN to celebrate the fourth anniversary of the announcement of the discovery of the Higgs Boson (Image: Maximilien Brice/ CERN) What do the Higgs boson and a pizza have in common? Pierluigi Paolucci, INFN and CMS collaboration member, together with INFN president Fernando Ferroni found out the answer one day in Naples: the pizza in front of them looked exactly like a Higgs boson event display. A special recipe was then created in collaboration with the chef of the historic “Ettore” pizzeria in the St. Lucia area of Naples, and two pizzas were designed to resemble two Higgs boson decay channel event displays. The “Higgs Boson Pizza Day” was held on Monday, 4 July 2016, on the fourth anniversary of the announcement of the discovery of the Higgs boso...
International Nuclear Information System (INIS)
Jersak, J.
1986-01-01
This year has brought a sudden interest in lattice Higgs models. After five years of only modest activity we now have many new results obtained both by analytic and Monte Carlo methods. This talk is a review of the present state of lattice Higgs models with particular emphasis on the recent development
Pseudo-Goldstone Higgs Doublets from Non-Vectorlike Grand Unified Higgs Sector
Hernández, A E Cárcamo
2016-01-01
We present a novel way of realizing the pseudo-Nambu-Goldstone boson mechanism for the doublet-triplet splitting in supersymmetric grand unified theories. The global symmetries of the Higgs sector are attributed to a non-vectorlike Higgs content, which is consistent with unbroken supersymmetry in a scenario with flat extra dimensions and branes. We also show how in such a model one can naturally obtain a realistic pattern for the Standard Model fermion masses and mixings.
Modeling acardiac twin pregnancies
de Groot, Rosa; van den Wijngaard, Jeroen P. H. M.; Umur, Asli; Beek, Johan F.; Nikkels, Peter G. J.; van Gemert, Martin J. C.
2007-01-01
Acardiac twin pregnancies are a rare but severe complication of monochorionic twinning, where the acardiac twin lacks cardiac function but nevertheless grows during pregnancy because it is perfused by the pump twin through a set of placental arterioarterial and venovenous anastomoses. Because the
Energy Technology Data Exchange (ETDEWEB)
Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kobayashi, Tsutomu [Kyoto Univ. (Japan). Hakubi Center; Kyoto Univ. (Japan). Dept. of Physics; Takahashi, Tomo [Saga Univ. (Japan). Dept. of Physics; Yamaguchi, Masahide [Tokyo Institute of Technology (Japan). Dept. of Physics; Yokoyama, Jun' ichi [Tokyo Univ. (JP). Research Center for the Early Universe (RESCEU); Tokyo Univ., Chiba (JP). Inst. for the Physics and Mathematics of the Universe (IPMU)
2012-03-15
We study Higgs inflation in the context of generalized G-inflation, i.e., the most general single-field inflation model with second-order field equations. The four variants of Higgs inflation proposed so far in the literature can be accommodated at one time in our framework. We also propose yet another class of Higgs inflation, the running Einstein inflation model, that can naturally arise from the generalized G-inflation framework. As a result, five Higgs inflation models in all should be discussed on an equal footing. Concise formulas for primordial fluctuations in these generalized Higgs inflation models are provided, which will be helpful to determine which model is favored from the future experiments and observations such as the Large Hadron Collider and the Planck satellite.
Energy Technology Data Exchange (ETDEWEB)
Duerr, Michael; Grohsjean, Alexander; Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Schwanenberger, Christian [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Penning, Bjoern [Bristol Univ. (United Kingdom). H.H. Wills Physics Lab.
2017-05-15
We discuss a novel signature of dark matter production at the LHC resulting from the emission of an additional Higgs boson in the dark sector. The presence of such a dark Higgs boson is motivated simultaneously by the need to generate the masses of the particles in the dark sector and the possibility to relax constraints from the dark matter relic abundance by opening up a new annihilation channel. If the dark Higgs boson decays into Standard Model states via a small mixing with the Standard Model Higgs boson, one obtains characteristic large-radius jets in association with missing transverse momentum that can be used to efficiently discriminate signal from backgrounds. We present the sensitivities achievable in LHC searches for dark Higgs bosons with already collected data and demonstrate that such searches can probe large regions of parameter space that are inaccessible to conventional mono-jet or di-jet searches.
Strongly interacting Higgs bosons
International Nuclear Information System (INIS)
Appelquist, T.; Bernard, C.
1980-01-01
The sensitivity of present-energy weak interactions to a strongly interacting heavy-Higgs-boson sector is discussed. The gauged nonlinear sigma model, which is the limit of the linear model as the Higgs-boson mass goes to infinity, is used to organize and catalogue all possible heavy-Higgs-boson effects. As long as the SU(2)/sub L/ x SU(2)/sub R/ symmetry of the Higgs sector is preserved, these effects are found to be small, of the order of the square of the gauge coupling times logarithms (but not powers) of the Higgs-boson mass divided by the W mass. We work in the context of a simplified model with gauge group SU(2)/sub L/; the extension to SU(2)/sub L/ x U(1) is briefly discussed
International Nuclear Information System (INIS)
Schlaffer, Matthias; Spannowsky, Michael; Wymant, Chris
2014-05-01
The inclusive Higgs production rate through gluon fusion has been measured to be in agreement with the Standard Model (SM). We show that even if the inclusive Higgs production rate is very SM-like, a precise determination of the boosted Higgs transverse momentum shape offers the opportunity to see effects of natural new physics. These measurements are generically motivated by effective field theory arguments and specifically in extensions of the SM with a natural weak scale, like composite Higgs models and natural supersymmetry. We show in detail how a measurement at high transverse momentum of H→2l+p T via H→ττ and H→WW * could be performed and demonstrate that it offers a compelling alternative to the t anti tH channel. We discuss the sensitivity to new physics in the most challenging scenario of an exactly SM-like inclusive Higgs cross-section.
International Nuclear Information System (INIS)
Duerr, Michael; Grohsjean, Alexander; Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Schwanenberger, Christian; Penning, Bjoern
2017-05-01
We discuss a novel signature of dark matter production at the LHC resulting from the emission of an additional Higgs boson in the dark sector. The presence of such a dark Higgs boson is motivated simultaneously by the need to generate the masses of the particles in the dark sector and the possibility to relax constraints from the dark matter relic abundance by opening up a new annihilation channel. If the dark Higgs boson decays into Standard Model states via a small mixing with the Standard Model Higgs boson, one obtains characteristic large-radius jets in association with missing transverse momentum that can be used to efficiently discriminate signal from backgrounds. We present the sensitivities achievable in LHC searches for dark Higgs bosons with already collected data and demonstrate that such searches can probe large regions of parameter space that are inaccessible to conventional mono-jet or di-jet searches.
Fu, Liming; Shan, Mokun; Zhang, Daoda; Wang, Huanrong; Wang, Wei; Shan, Aidang
2017-05-01
The microstructures and deformation behavior were studied in a high-temperature annealed high-manganese dual-phase (28 vol pct δ-ferrite and 72 vol pct γ-austenite) transformation-induced plasticity/twinning-induced plasticity (TRIP/TWIP) steel. The results showed that the steel exhibits a special Lüders-like yielding phenomenon at room temperature (RT) and 348 K (75 °C), while it shows continuous yielding at 423 K, 573 K and 673 K (150 °C, 300 °C and 400 °C) deformation. A significant TRIP effect takes place during Lüders-like deformation at RT and 348 K (75 °C) temperatures. Semiquantitative analysis of the TRIP effect on the Lüders-like yield phenomenon proves that a softening effect of the strain energy consumption of strain-induced transformation is mainly responsible for this Lüders-like phenomenon. The TWIP mechanism dominates the 423 K (150 °C) deformation process, while the dislocation glide controls the plasticity at 573 K (300 °C) deformation. The delta-ferrite, as a hard phase in annealed dual-phase steel, greatly affects the mechanical stability of austenite due to the heterogeneous strain distribution between the two phases during deformation. A delta-ferrite-aided TRIP effect, i.e., martensite transformation induced by localized strain concentration of the hard delta-ferrite, is proposed to explain this kind of Lüders-like phenomenon. Moreover, the tensile curve at RT exhibits an upward curved behavior in the middle deformation stage, which is principally attributed to the deformation twinning of austenite retained after Lüders-like deformation. The combination of the TRIP effect during Lüders-like deformation and the subsequent TWIP effect greatly enhances the ductility in this annealed high-manganese dual-phase TRIP/TWIP steel.
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
Owen, Mark
2009-09-01
The Higgs boson is essential to achieve electroweak symmetry breaking in the Standard Model. Results on searches for the Higgs boson using data collected in pbar p collisions at √ s = 1.96 {TeV} with the DØ detector at the Fermilab Teva-tron collider are presented. The data, corresponding to integrated luminosities between 1 fb-1 and 2 fb-1 show no excess above the expected backgrounds and as such upper limits on the production cross section of Higgs bosons are set at the 95% confidence level.
International Nuclear Information System (INIS)
Yu, Ha-Young; Lee, Sang-Min; Nam, Jae-Hoon; Lee, Seung-Joon; Fabrègue, Damien; Park, Myeong-heom; Tsuji, Nobuhiro; Lee, Young-Kook
2017-01-01
The objective of the present study was to elucidate the complicated interrelationship between necking, post-uniform elongation (e_p_u), strain rate sensitivity (SRS), fracture mechanism and Al concentration in Fe-18Mn-0.6C-xAl twinning-induced plasticity steels. Many tensile tests were conducted for in- and ex-situ observations of necking, fracture surfaces, crack propagation and the density and size of micro-voids with the assistance of a high-speed camera and X-ray tomographic equipment. The addition of Al increased e_p_u, SRS and reduction ratios in dimension of the neck part of tensile specimens, and also changed fracture mode from quasi-cleavage to ductile fracture at the edge part. The quasi-cleavage surface of Al-free specimen was induced by edge and side cracks occurring along grain boundary junctions and twin boundaries within the edges and side surfaces where local deformation bands meet. The ductile-fracture surface of 1.5 %Al-added specimen was formed by the coalescence of micro-voids. While the side-to-middle crack propagation occurred in Al-free and 1 %Al-added specimens due to side cracks, the middle-to-side crack propagation was observed in 1.5 %Al-added specimen. The Al-free specimen had the larger size of the 20 largest voids compared to the 1.5 %Al-added specimen despite its lower void density and local strain due to the accelerated growth of voids near the tips of side cracks. Evaluating the negligible e_p_u of Al-free specimen by SRS is not deemed to be reasonable due to its inappreciable necking and side cracks. The improvement of e_p_u in 1.5 %Al-added specimen is primarily due to disappearance of edge and side cracks.
Energy Technology Data Exchange (ETDEWEB)
Lebedev, Oleg [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Lee, Hyun Min [European Organization for Nuclear Research (CERN), Geneva (Switzerland)
2011-05-15
The Higgs sector of the Standard Model offers a unique opportunity to probe the hidden sector. The Higgs squared operator is the only dimension two operator which is Lorentz and gauge invariant. It can therefore couple both to scalar curvature and the hidden sector at the dim-4 level. We consider the possibility that a combination of the Higgs and a singlet from the hidden sector plays the role of inflaton, due to their large couplings to gravity. This implies that the quartic couplings satisfy certain constraints which leads to distinct low energy phenomenology, including Higgs signals at the LHC. We also address the unitarity issues and show that our analysis survives the unitarization procedure. (orig.)
Partially composite Higgs models
DEFF Research Database (Denmark)
Alanne, Tommi; Buarque Franzosi, Diogo; Frandsen, Mads T.
2018-01-01
We study the phenomenology of partially composite-Higgs models where electroweak symmetry breaking is dynamically induced, and the Higgs is a mixture of a composite and an elementary state. The models considered have explicit realizations in terms of gauge-Yukawa theories with new strongly...... interacting fermions coupled to elementary scalars and allow for a very SM-like Higgs state. We study constraints on their parameter spaces from vacuum stability and perturbativity as well as from LHC results and find that requiring vacuum stability up to the compositeness scale already imposes relevant...... constraints. A small part of parameter space around the classically conformal limit is stable up to the Planck scale. This is however already strongly disfavored by LHC results. in different limits, the models realize both (partially) composite-Higgs and (bosonic) technicolor models and a dynamical extension...
Parker, Andy
1996-01-01
The Higgs boson is the most mysterious of all the fundamental particles. It accounts for how other particles acquired mass just after the beginning of the Universe. LEP-2 and the LHC at CERN will hunt it down between them
Lebedev, Oleg
2011-01-01
The Higgs sector of the Standard Model offers a unique opportunity to probe the hidden sector. The Higgs squared operator is the only dimension two operator which is Lorentz and gauge invariant. It can therefore couple both to scalar curvature and the hidden sector at the dim--4 level. We consider the possibility that a combination of the Higgs and a singlet from the hidden sector plays the role of inflaton, due to their large couplings to gravity. This implies that the quartic couplings satisfy certain constraints which leads to distinct low energy phenomenology, including Higgs signals at the LHC. We also address the unitarity issues and show that our analysis survives the unitarization procedure.
From photons to Higgs a story of light
Han, Moo-Young
2014-01-01
This book presents a brief introduction to the quantum field theory of the Standard Model for quarks and leptons. With minimal use of mathematics, it covers the basics of quantum field theory, local gauge field theory, spontaneous symmetry breaking mechanism, the Higgs mechanism and quantum chromodynamics. From the time when the first edition was published until today, the field of particle physics has seen some major break-through with the possible discovery of Higgs particle, also known as the Higgs boson. In the second edition, the famous Higgs mechanism is included to explain the symmetry breaking in the Standard Model and the origin of mass, and all of this is explained in high-school level algebra. Aimed at both scientists and non-specialists, it requires only some rudimentary knowledge of the Lagrangian and Hamiltonian formulation of Newtonian mechanics as well as a basic understanding of the special theory of relativity and quantum mechanics to enjoy this book.
The mobility of growth twins synthesized by sputtering: Tailoring the twin thickness
International Nuclear Information System (INIS)
Velasco, Leonardo; Hodge, Andrea M.
2016-01-01
The current work presents a protean twin thickness contour zone map that illustrates how the nucleation and the mobility of twin boundaries affects the twin thickness of sputtered films. The twin thickness contour zone map can be used as a versatile guide to synthesize fully nanotwinned films with tailored twin thicknesses in materials with a wide range of stacking fault energies. The nucleation and mobility of twin boundaries was studied in four Cu alloys of different compositions (Cu-6wt.%Al, Cu-4wt.%Al, Cu-2wt.%Al, and Cu-10wt.%Ni), having stacking fault energies ranging from 6 mJ/m 2 to 60 mJ/m 2 . The films were synthesized by magnetron sputtering and characterized by transmission electron microscopy, where the twin thickness varied from 2 nm to 35 nm. Our experimental results show that it is possible to control the twin thickness. Three main mechanisms are explained to describe twin nucleation and twin boundary mobility, which are correlated to the interplay of specific sputtering conditions and the deposition temperature.
Dezso, Horvath
2017-01-01
A részecskefizika általánosan elfogadott és az elmúlt 40 év alatt sokszorosan igazolt elmélete, a standard modell valamennyi alkatrészét sikerült megfigyelni és tanulmányozni a Higgs-bozon kivételével. A CERN nagy hadronütköztetője (LHC), a világ legnagyobb részecskegyorsítója is elsősorban a Higgs-részecske kimutatására épült. 2012 közepére az LHC két óriási mérőberendezése, a sok ezer fizikus részvételével épült CMS és ATLAS megfigyelt egy - a Higgs-bozon elméletileg megjósolt tulajdonságaival rendelkező - új részecskét. A könyv áttekinti a standard modell elméletét és a Higgs-részecske feltételezett tulajdonságait, majd összefoglalja az LHC Higgs-keresési eredményeit és a hozzájuk vezető utat. Függelékben ismerteti a könyvben előforduló fizikusok életrajzát és bizonyos fizikai fogalmak részletesebb leírását. A 2013-as fizikai Nobel-díjat Peter Higgs és François Englert kapták megosztva a Higgs-mechanizmus és a Higgs-bozon elmé...
Hawkes, N
1999-01-01
A conference in the US has suggested that the mass of the Higgs boson may not be as large as previously thought. It may be within the reach of the Tevatron at Fermilab if it operates for longer than the planned two years. If so, the LHC designed specifically to find the Higgs boson may be beaten to the discovery before it is even built (1/2 page).
Higgs Boson Properties in the Standard Model and its Supersymmetric Extensions
Ellis, Jonathan Richard; Zwirner, F; Ellis, John; Ridolfi, Giovanni; Zwirner, Fabio
2007-01-01
We review the realization of the Brout-Englert-Higgs mechanism in the electroweak theory and describe the experimental and theoretical constraints on the mass of the single Higgs boson expected in the minimal Standard Model. We also discuss the couplings of this Higgs boson and its possible decay modes as functions of its unknown mass. We then review the structure of the Higgs sector in the minimal supersymmetric extension of the Standard Model (MSSM), noting the importance of loop corrections to the masses of its five physical Higgs bosons. Finally, we discuss some non-minimal models.
Higgs boson properties in the Standard Model and its supersymmetric extensions
International Nuclear Information System (INIS)
Ellis, J.; Ridolfi, G.; Zwirner, F.
2007-01-01
We review the realization of the Brout-Englert-Higgs mechanism in the electroweak theory and describe the experimental and theoretical constraints on the mass of the single Higgs boson expected in the minimal Standard Model. We also discuss the couplings of this Higgs boson and its possible decay modes as functions of its unknown mass. We then review the structure of the Higgs sector in the minimal supersymmetric extension of the Standard Model (MSSM), noting the importance of loop corrections to the masses of its 5 physical Higgs bosons. Finally, we discuss some non-minimal models. (authors)
Higgs production and decay in models of a warped extra dimension with a bulk Higgs
International Nuclear Information System (INIS)
Archer, Paul R.; Carena, Marcela; Carmona, Adrian; Neubert, Matthias
2015-01-01
Warped extra-dimension models in which the Higgs boson is allowed to propagate in the bulk of a compact AdS 5 space are conjectured to be dual to models featuring a partially composite Higgs boson. They offer a framework with which to investigate the implications of changing the scaling dimension of the Higgs operator, which can be used to reduce the constraints from electroweak precision data. In the context of such models, we calculate the cross section for Higgs production in gluon fusion and the H → γγ decay rate and show that they are finite (at one-loop order) as a consequence of gauge invariance. The extended scalar sector comprising the Kaluza-Klein excitations of the Standard Model scalars is constructed in detail. The largest effects are due to virtual KK fermions, whose contributions to the cross section and decay rate introduce a quadratic sensitivity to the maximum allowed value y * of the random complex entries of the 5D anarchic Yukawa matrices. We find an enhancement of the gluon-fusion cross section and a reduction of the H → γγ rate as well as of the tree-level Higgs couplings to fermions and electroweak gauge bosons. As a result, we perform a detailed study of the correlated signal strengths for different production mechanisms and decay channels as functions of y * , the mass scale of Kaluza-Klein resonances and the scaling dimension of the composite Higgs operator
Academic training: The Hunt for the Higgs Particle
2007-01-01
2006-2007 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 27, 28 February, 1st March, from 11:00 to 12:00 Main Auditorium, bldg. 500 The Hunt for the Higgs Particle F. ZWIRNER, University and INFN, Padova, Italy With the advent of the LHC, the hunt for the Higgs boson is entering its crucial phase. These three lectures will review: the Higgs mechanism; its implementation in the minimal Standard Model; possible alternatives with and without elementary scalar fields; the presently available information on electroweak gauge symmetry breaking and the Higgs particle; the properties of the Higgs boson(s) in the Standard Model and its supersymmetric extensions; the strategies for direct searches at colliders, with emphasis on the LHC, and comments on the possible scenarios that may emerge.
Higgs portal valleys, stability and inflation
Ballesteros, Guillermo
2015-01-01
The measured values of the Higgs and top quark masses imply that the Standard Model potential is very likely to be unstable at large Higgs values. This is particularly problematic during inflation, which sources large perturbations of the Higgs. The instability could be cured by a threshold effect induced by a scalar with a large vacuum expectation value and directly connected to the Standard Model through a Higgs portal coupling. However, we find that in a minimal model in which the scalar generates inflation, this mechanism does not stabilize the potential because the mass required for inflation is beyond the instability scale. This conclusion does not change if the Higgs has a direct weak coupling to the scalar curvature. On the other hand, if the potential is absolutely stable, successful inflation in agreement with current CMB data can occur along a valley of the potential with a Mexican hat profile. We revisit the stability conditions, independently of inflation, and clarify that the threshold effect ca...
AUTHOR|(CDS)2073690
2016-01-01
The Compact Linear Collider (CLIC) is an attractive option for a future multi-TeV linear electron-positron collider, offering the potential for a rich precision physics programme, combined with sensitivity to a wide range of new phenomena. The physics reach of CLIC has been studied in the context of three distinct centre-of-mass energies, √s = 350 GeV, 1.4 TeV and 3.0 TeV. This staged scenario provides an excellent environment for precise studies of the properties of the 126 GeV Higgs boson. Operation at √s = 350 GeV allows, on the one hand, for a determination of the couplings and width of the Higgs boson in a model-independent manner through the study of the Higgsstrahlung process, and on the other hand, for a study of Higgs bosons produced in W+W− fusion for the most common Higgs decay modes. Operation at higher centre-of-mass energies, √s = 1.4 TeV and 3 TeV, provides high statistics W+W− fusion samples allowing for high precision measurements of many Higgs couplings and a study of rare Higgs de...
International Nuclear Information System (INIS)
Tonini, Marco
2014-11-01
This thesis discusses the consistency of different Little Higgs models with the collected collider data as of the summer of 2013. Moreover, future prospects for possible discoveries and mass measurement methods of new physics signals at the foreseen LHC run II with increased center-of-mass energy are presented. Little Higgs models belong to a class of extensions of the Standard Higgs model, predicting a strong interaction regime at a compositeness scale Λ=4πf approximate global symmetry spontaneously broken at the scale f. A natural hierarchy between the compositeness and the electroweak scale is introduced by the Collective Symmetry Breaking mechanism: one-loop diagrams generating the Higgs mass term are forced to be at most logarithmically sensitive to Λ. A naturally light Higgs boson can thus be accommodated, consistently with a perturbative theory until a scale of order 10 TeV. We have probed the parameter space of three prominent examples of Little Higgs models, namely the Simplest Little Higgs model, the Littlest Higgs model, and the Littlest Higgs model with T-parity, against electroweak precision observables and the collected LHC data concerning both Higgs properties and direct searches for new particles, with √(s)=7,8 TeV and up to 25 fb -1 of integrated luminosity. Lower bounds on the scale f are set, within a certain degree of confidence level, which allow to draw conclusions on the ''naturalness'' of the different models. Optimisations of the existing direct searches setups, assuming a Little Higgs signal, as well as dedicated mass measurement methods designed for the foreseen LHC runs with √(s)=13,14 TeV are thoroughly discussed and proposed in this thesis. Special attention will be dedicated to final states including either a large or negligible fraction of missing transverse momentum. In particular, we will propose a dedicated collider search tailored for the discovery and mass measurement of a top partner, exploiting jet
Higgs Boson Properties and Search for Additional Resonances
AUTHOR|(INSPIRE)INSPIRE-00435709
The Higgs boson was predicted by the Standard Model of particle physics and jointly discovered by the CMS and ATLAS experiments at LHC, in 2012. Following its discovery, the property measurements of the Higgs boson and the search for additional resonances become important research goals. The Standard Model is not the complete theory and leaves many questions unanswered, therefore it is important to search for any evidence of new physics beyond the SM. This thesis will briefly introduce the theoretical motivation for the Higgs boson, the production and decay mechanisms of the Higgs boson, and the methods used for analysis of the Higgs boson properties. The spin-1 and spin-2 Higgs hypotheses are tested in H->ZZ->4l channel, using the data recorded by CMS in Run1 of LHC. The exotic spin models were excluded and the Higgs boson is shown to agree with the Standard Model prediction of spin-0. The search for high-mass Higgs-like resonance is performed in H->ZZ->4l and H->ZZ->2l2q channels, using data recorded by CMS...
Higgs as a holographic pseudo-Goldstone boson
International Nuclear Information System (INIS)
Contino, Roberto; Nomura, Yasunori; Pomarol, Alex
2003-01-01
The AdS/CFT correspondence allows one to relate 4D strongly coupled theories to weakly coupled theories in 5D AdS. We use this correspondence to study a scenario in which the Higgs appears as a composite pseudo-Goldstone boson (PGB) of a strongly coupled theory. We show how a non-linearly realized global symmetry protects the Higgs mass and guarantees the absence of quadratic divergences at any loop order. The gauge and Yukawa interactions for the PGB Higgs are simple to introduce in the 5D AdS theory, and their one-loop contributions to the Higgs potential are calculated using perturbation theory. These contributions are finite, giving a squared-mass to the Higgs which is one-loop smaller than the mass of the first Kaluza-Klein state. We also show that if the symmetry breaking is caused by boundary conditions in the extra dimension, the PGB Higgs corresponds to the fifth component of the bulk gauge boson. To make the model fully realistic, a tree-level Higgs quartic coupling must be induced. We present a possible mechanism to generate it and discuss the conditions under which an unwanted large Higgs mass term is avoided
SM Higgs decay branching ratios and total Higgs width
Daniel Denegri
2001-01-01
Upper: Higgs decay ratios as a function of Higgs mass. The largest branching ratio is not necessarily the most usefull one. The most usefull ones are gamma gamma bbar ZZ and WW as in those modes latter signal to background ratios can be achieved. Lower: Total Higgs decay width versus Higgs mass. At low masses the natural width is extremely small, thus observability depends on instrumental resolution primarily.
Monochorionic twin pregnancies
Hack, K.E.A.
2008-01-01
Following widespread application of assisted reproductive technology modalities and the increased age of motherhood, the incidence of twin gestations has increased markedly. Twins are either monozygotic or dizygotic. Dizygotic (i.e. fraternal) twins result from the fertilization of two different
Working Group Report: Higgs Boson
Energy Technology Data Exchange (ETDEWEB)
Dawson, Sally; Gritsan, Andrei; Logan, Heather; Qian, Jianming; Tully, Chris; Van Kooten, Rick [et al.
2013-10-30
This report summarizes the work of the Energy Frontier Higgs Boson working group of the 2013 Community Summer Study (Snowmass). We identify the key elements of a precision Higgs physics program and document the physics potential of future experimental facilities as elucidated during the Snowmass study. We study Higgs couplings to gauge boson and fermion pairs, double Higgs production for the Higgs self-coupling, its quantum numbers and $CP$-mixing in Higgs couplings, the Higgs mass and total width, and prospects for direct searches for additional Higgs bosons in extensions of the Standard Model. Our report includes projections of measurement capabilities from detailed studies of the Compact Linear Collider (CLIC), a Gamma-Gamma Collider, the International Linear Collider (ILC), the Large Hadron Collider High-Luminosity Upgrade (HL-LHC), Very Large Hadron Colliders up to 100 TeV (VLHC), a Muon Collider, and a Triple-Large Electron Positron Collider (TLEP).
Higgs boson transverse momentum distribution
CERN. Geneva
2018-01-01
I will review the recent progress in understanding Higgs boson transverse momentum distribution focusing on effects that go beyond the point-like approximation for the Higgs-glue interaction vertex.
Tools for charged Higgs bosons
International Nuclear Information System (INIS)
Staal, Oscar
2010-12-01
We review the status of publicly available software tools applicable to charged Higgs physics. A selection of codes are highlighted in more detail, focusing on new developments that have taken place since the previous charged Higgs workshop in 2008. We conclude that phenomenologists now have the tools ready to face the LHC data. A new web page collecting charged Higgs resources is presented. (orig.)
Finite-Temperature Higgs Potentials
International Nuclear Information System (INIS)
Dolgopolov, M.V.; Gurskaya, A.V.; Rykova, E.N.
2016-01-01
In the present article we consider the short description of the “Finite-Temperature Higgs Potentials” program for calculating loop integrals at vanishing external momenta and applications for extended Higgs potentials reconstructions. Here we collect the analytic forms of the relevant loop integrals for our work in reconstruction of the effective Higgs potential parameters in extended models (MSSM, NMSSM and etc.)
Colas, Paul
2003-01-01
The Higgs boson was theoretically created about 40 years ago by a Scott Peter Higgs who wanted to explain why some particles get a mass. Since then the Higgs boson has taken consistency and has become an important point of the standard model theory. Its experimental discovery would be a milestone of modern physics. The search for the Higgs boson is an international challenge that takes place around 2 huge machines: the Tevatron near Chicago and the LHC (large hadron collider) that is being built in CERN. The Tevatron is in fact the upgrading of an old particle accelerator, it is a proton collider and its narrow range of energy is compensated by a low background noise. On the other hand the LHC will begin operating only in 2007 and its full power will be reached a few years later, the energy available to create particles will be then 7 times higher than for the Tevatron. Both machines have chance of succeeding by being the first to detect the Higgs boson. Time plays in favor of the Tevatron but in any case if ...
New theory for crack-tip twinning in fcc metals
Andric, Predrag; Curtin, W. A.
2018-04-01
Dislocation emission from a crack tip is a necessary mechanism for crack tip blunting and toughening. In fcc metals under Mode I loading, a first partial dislocation is emitted, followed either by a trailing partial dislocation ("ductile" behaviour) or a twinning partial dislocation ("quasi-brittle"). The twinning tendency is usually estimated using the Tadmor and Hai extension of the Rice theory. Extensive molecular statics simulations reveal that the predictions of the critical stress intensity factor for crack tip twinning are always systematically lower (20-35%) than observed. Analyses of the energy change during nucleation reveal that twin partial emission is not accompanied by creation of a surface step while emission of the trailing partial creates a step. The absence of the step during twinning motivates a modified model for twinning nucleation that accounts for the fact that nucleation does not occur directly at the crack tip. Predictions of the modified theory are in excellent agreement with all simulations that show twinning. Emission of the trailing partial dislocation, including the step creation, is predicted using a model recently introduced to accurately predict the first partial emission and shows why twinning is preferred. A second mode of twinning is found wherein the crack first advances by cleavage and then emits the twinning partial at the new crack tip; this mode dominates for emission beyond the first twinning partial. These new theories resolve all the discrepancies between the Tadmor twinning analysis and simulations, and have various implications for fracture behaviour and transitions.
Intragranular twinning, detwinning, and twinning-like lattice reorientation in magnesium alloys
International Nuclear Information System (INIS)
Wu, Wei; Gao, Yanfei; Li, Nan; Parish, Chad M.; Liu, Wenjun; Liaw, Peter K.; An, Ke
2016-01-01
Deformation twinning plays a critical role on improving metals or alloys ductility, especially for hexagonal close-packed materials with low symmetry crystal structure. A rolled Mg alloy was selected as a model system to investigate the extension twinning behaviors and characteristics of parent-twin interactions by nondestructive in situ 3D synchrotron X-ray microbeam diffraction. Besides twinning-detwinning process, the “twinning-like” lattice reorientation process was captured within an individual grain inside a bulk material during the strain reversal. The distributions of parent, twin, and reorientated grains and sub-micron level strain variation across the twin boundary are revealed. A theoretical calculation of the lattice strain confirms that the internal strain distribution in parent and twinned grains correlates with the experimental setup, grain orientation of parent, twin, and surrounding grains, as well as the strain path changes. The study suggests a novel deformation mechanism within the hexagonal close-packed structure that cannot be determined from surface-based characterization methods.
Physical analysis of some features of the gauge theories with Higgs sectors
International Nuclear Information System (INIS)
Beshtoev, Kh.M.
1995-01-01
A physical analysis of some features of the gauge theories with Higgs sectors is made. It is shown that we should assume gauge transformations in the fermion and Higgs sectors to be different (i.e., to have different charges) in order to remove contradictions arising in gauge theories with Higgs sectors. Then, the Higgs mechanism can be interpreted as some mechanism of gauge field shielding. In such a mechanism fermions remain without masses. The conclusion is made that in the standard theory of the development of the Universe, monopoles cannot survive at low temperatures. 15 refs
ATLAS discovery potential of the Standard Model Higgs boson
Weiser, C; The ATLAS collaboration
2009-01-01
The Standard Model of elementary particles is remarkably succesful in describing experimental data. The Higgs mechanism as the origin of electroweak symmetry breaking and mass generation, however, has not yet been confirmed experimentally. The search for the Higgs boson is thus one of the most important tasks of the ATLAS experiment at the Large Hadron Collider (LHC). This talk will present an overview of the potential of the ATLAS detector for the discovery of the Standard Model Higgs boson. Different production processes and decay channels -to cover a wide mass range- will be discussed.
ATLAS Discovery Potential of the Standard Model Higgs Boson
Weiser, C; The ATLAS collaboration
2010-01-01
The Standard Model of elementary particles is remarkably succesful in describing experimental data. The Higgs mechanism as the origin of electroweak symmetry breaking and mass generation, however, has not yet been confirmed experimentally. The search for the Higgs boson is thus one of the most important tasks of the ATLAS experiment at the Large Hadron Collider (LHC). This talk will present an overview of the potential of the ATLAS detector for the discovery of the Standard Model Higgs boson. Different production processes and decay channels -to cover a wide mass range- will be discussed.
Hemmer, Sabine
2018-01-01
Poster di ATLAS sul bosone di Higgs indirizzato al pubblico generico, che spiega il meccanismo di Brout-Englert-Higgs e la sua importanza. Spiega anche il ruolo del Bosone di Higgs, come viene cercato, il percorso della sua scoperta e cosa viene dopo la scoperta. Disponibile anche in Francese (http://cds.cern.ch/record/1697501) e Inglese (http://cds.cern.ch/record/1697389). Non esitate a utilizzarlo nelle sedi dei vostri Istituti e negli eventi divulgativi! Il poster è in formato A0. Cliccate sull'immagine per scaricare il .pdf ad alta qualità e stamparlo dove preferite. Per qualisasi domanda o commento potete contattare atlas-outreach-coordination@cern.ch
CERN. Geneva
2011-01-01
The excellent performances of the LHC in the 2011 run are setting the grounds for the final chase of the Higgs boson. The CMS experiment is recording high quality data that are being thoroughly scrutinized. Several decay channels are investigated to probe the entire possible Higgs mass spectrum, from 110 to 600 GeV/c^2. The study of the first 1.5/fb of collected data places already tight limits and excludes large fractions of the Higgs mass range, leaving however still open the search in the theoretically favored low mass region. In this seminar we will report on the diverse CMS analyses that yield to such results describing the experimental challenges that each had to meet.
Segal, Nancy L
2017-12-01
Findings from twin studies of musical interests and talent are reviewed as a backdrop to the lives and careers of twin jazz musicians, Peter and Will Anderson. The Anderson twins exemplify many aspects of twin research, namely their matched musical abilities, shared musical interests, and common career. This overview is followed by reviews of studies and case reports of bereavement in families who have lost a preterm multiple birth infant, the conception of conjoined twins following in vitro fertilization (IVF), depression in fathers of twins, and twin-to-twin transfusion incidence in monochorionic-diamniotic IVF twin pairs. Twins highlighted in the media include high-achieving identical female twins with nearly identical academic standing, tennis star Roger Federer's two sets of identical twin children, surgical separation of craniopagus conjoined twins, and the rare delivery of twins to a 23-year-old giant panda.
CERN. Geneva
2015-01-01
After reviewing the nice properties of Higgs inflation and some of its problems, I will discuss a simple unitarization of the scenario that is genuinely weakly coupled up to Planckian energies. A large non-minimal coupling between the Higgs and the Ricci curvature is induced dynamically at intermediate energies, as a simple ratio of mass scales. Inflationary dynamics is not dominated by the Higgs field, but 'Higgs inflation' arises as an approximate 'mirage' picture of the true dynamics. I will speculate on the generality of this phenomenon and show that, if Higgs-inflation arises as an effective description, the details of the UV completion are necessary to extract robust quantitative predictions.
Energy Technology Data Exchange (ETDEWEB)
Anon.
1986-03-15
The unified theory of electromagnetism and the weak nuclear force, crowned with the discovery at CERN in 1983 of the W and Z bosons which carry the weak nuclear force, is one of the great triumphs of modern physics. But the picture is not yet complete. An essential but still elusive ingredient is the so-called 'Higgs boson' (after Edinburgh theorist Peter Higgs), responsible for the vital symmetry breaking in the theory. This gives the carriers of the weak force mass, while the photon, the carrier of electromagnetism, is massless.
Character Profile of the Higgs boson
Brenner, Lydia; Verkerke, Wouter; Bentvelsen, Stan; Ferrari, Pamela
2017-01-01
Elementary particle physics describes and measures the properties of the smallest, most fundamental particles that make up the universe. The Standard Model of elementary particle physics provides a fundamental description of particles, their dynamics and interactions. The particles embedded into the theory are, a priori, massless, while observed particles have mass. In order to explain the origin of the elementary particle masses, the Brout-Englert-Higgs mechanism is introduced. The mechanism...
Character profile of the Higgs boson
Brenner, L.
2017-01-01
Elementary particle physics describes and measures the properties of the smallest, most fundamental particles that make up the universe. The Standard Model of elementary particle physics provides a fundamental description of particles, their dynamics and interactions. The particles embedded into the theory are, a priori, massless, while observed particles have mass. In order to explain the origin of the elementary particle masses, the Brout-Englert-Higgs mechanism is introduced. The mechanism...
Search for Multiphoton Signatures of a Higgs Boson
Energy Technology Data Exchange (ETDEWEB)
Atramentov, Oleksiy Vladimirovich [Iowa State Univ., Ames, IA (United States)
2006-07-01
In this thesis we describe a search for a fermiophobic Higgs boson in 3γ+X events. The study has been performed on 0.83 fb^{-1} of data collected with the D0 detector that resides at one of the interaction regions of the Tevatron collider, the world's highest energy accelerator. This study was motivated by a fairly recent phenomenological paper [33] where it was noticed that in certain class of models (2HDM Type I and THM) the multi-photon final states like this one become detectable at the luminosity that has been collected by the D0 experiment by 2006. The mechanism that permits such final state becomes available when the conventional higgs production mechanism (higgs strahlung) are suppressed. This leads to the fact that Higgs boson with mass (m_{hf} < 90 GeV/c^{2}) lower than the current limit has not been excluded.
Strong crystal size effect on deformation twinning
DEFF Research Database (Denmark)
Yu, Qian; Shan, Zhi-Wei; Li, Ju
2010-01-01
plasticity. Accompanying the transition in deformation mechanism, the maximum flow stress of the submicrometre-sized pillars was observed to saturate at a value close to titanium’s ideal strength9, 10. We develop a ‘stimulated slip’ model to explain the strong size dependence of deformation twinning......Deformation twinning1, 2, 3, 4, 5, 6 in crystals is a highly coherent inelastic shearing process that controls the mechanical behaviour of many materials, but its origin and spatio-temporal features are shrouded in mystery. Using micro-compression and in situ nano-compression experiments, here we...... find that the stress required for deformation twinning increases drastically with decreasing sample size of a titanium alloy single crystal7, 8, until the sample size is reduced to one micrometre, below which the deformation twinning is entirely replaced by less correlated, ordinary dislocation...
Higgs naturalness and dark matter stability by scale invariance
Directory of Open Access Journals (Sweden)
Jun Guo
2015-09-01
Full Text Available Extending the spacetime symmetries of standard model (SM by scale invariance (SI may address the Higgs naturalness problem. In this article we attempt to embed accidental dark matter (DM into SISM, requiring that the symmetry protecting DM stability is accidental due to the model structure rather than imposed by hand. In this framework, if the light SM-like Higgs boson is the pseudo Goldstone boson of SI spontaneously breaking, we can even pine down the model, two-Higgs-doublets plus a real singlet: The singlet is the DM candidate and the extra Higgs doublet triggers electroweak symmetry breaking via the Coleman–Weinberg mechanism; Moreover, it dominates DM dynamics. We study spontaneously breaking of SI using the Gillard–Weinberg approach and find that the second doublet should acquire vacuum expectation value near the weak scale. Moreover, its components should acquire masses around 380 GeV except for a light CP-odd Higgs boson. Based on these features, we explore viable ways to achieve the correct relic density of DM, facing stringent constraints from direct detections of DM. For instance, DM annihilates into bb¯ near the SM-like Higgs boson pole, or into a pair of CP-odd Higgs boson with mass above that pole.
New results on Higgs boson physics from the ATLAS experiment
CERN. Geneva
2018-01-01
The ATLAS Collaboration has recently released several results that shed more light on the nature of the Higgs boson particle and the BEH mechanism. A selection of these Higgs boson results, including some results based on up to 80 fb-1of integrated luminosity collected at a centre-of-mass energy of 13 TeV with the ATLAS experiment at the LHC, will be presented.
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.)
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.)
Hein, Till
2005-01-01
CERN's physicists are worried by a great question: does the universe remain stable? Why does the world exist? To answer, they look for the infinitely small and are trying to find the "key": the hypothetical Higgs-boson (4½ pages)
Disentangling a dynamical Higgs
International Nuclear Information System (INIS)
Brivio, I.; Corbett, T.; Éboli, O.J.P.; Gavela, M.B.; Gonzalez-Fraile, J.; Gonzalez-Garcia, M.C.; Merlo, L.; Rigolin, S.
2014-01-01
The pattern of deviations from Standard Model predictions and couplings is different for theories of new physics based on a non-linear realization of the SU(2) L ×U(1) Y gauge symmetry breaking and those assuming a linear realization. We clarify this issue in a model-independent way via its effective Lagrangian formulation in the presence of a light Higgs particle, up to first order in the expansions: dimension-six operators for the linear expansion and four derivatives for the non-linear one. Complete sets of gauge and gauge-Higgs operators are considered, implementing the renormalization procedure and deriving the Feynman rules for the non-linear expansion. We establish the theoretical relation and the differences in physics impact between the two expansions. Promising discriminating signals include the decorrelation in the non-linear case of signals correlated in the linear one: some pure gauge versus gauge-Higgs couplings and also between couplings with the same number of Higgs legs. Furthermore, anomalous signals expected at first order in the non-linear realization may appear only at higher orders of the linear one, and vice versa. We analyze in detail the impact of both type of discriminating signals on LHC physics
Bellazzini, Brando; Hubisz, Jay; Lee, Seung J.; Serra, Javi; Terning, John
2016-01-01
The appearance of the light Higgs boson at the LHC is difficult to explain, particularly in light of naturalness arguments in quantum field theory. However light scalars can appear in condensed matter systems when parameters (like the amount of doping) are tuned to a critical point. At zero temperature these quantum critical points are directly analogous to the finely tuned standard model. In this paper we explore a class of models with a Higgs near a quantum critical point that exhibits non-mean-field behavior. We discuss the parametrization of the effects of a Higgs emerging from such a critical point in terms of form factors, and present two simple realistic scenarios based on either generalized free fields or a 5D dual in AdS space. For both of these models we consider the processes $gg\\to ZZ$ and $gg\\to hh$, which can be used to gain information about the Higgs scaling dimension and IR transition scale from the experimental data.
Bellazzini, Brando; Csáki, Csaba; Hubisz, Jay; Lee, Seung J.; Serra, Javi; Terning, John
2016-10-01
The appearance of the light Higgs boson at the LHC is difficult to explain, particularly in light of naturalness arguments in quantum field theory. However, light scalars can appear in condensed matter systems when parameters (like the amount of doping) are tuned to a critical point. At zero temperature these quantum critical points are directly analogous to the finely tuned standard model. In this paper, we explore a class of models with a Higgs near a quantum critical point that exhibits non-mean-field behavior. We discuss the parametrization of the effects of a Higgs emerging from such a critical point in terms of form factors, and present two simple realistic scenarios based on either generalized free fields or a 5D dual in anti-de Sitter space. For both of these models, we consider the processes g g →Z Z and g g →h h , which can be used to gain information about the Higgs scaling dimension and IR transition scale from the experimental data.
Disentangling a dynamical Higgs
Energy Technology Data Exchange (ETDEWEB)
Brivio, I. [Departamento de Física Teórica and Instituto de Física Teórica, IFT-UAM/CSIC,Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid (Spain); Corbett, T. [C.N. Yang Institute for Theoretical Physics and Department of Physics and Astronomy,SUNY at Stony Brook, Stony Brook, NY 11794-3840 (United States); Éboli, O.J.P. [Instituto de Física, Universidade de São Paulo,C.P. 66318, 05315-970, São Paulo SP (Brazil); Gavela, M.B. [Departamento de Física Teórica and Instituto de Física Teórica, IFT-UAM/CSIC,Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid (Spain); Gonzalez-Fraile, J. [Departament d’Estructura i Constituents de la Matèria and ICC-UB, Universitat de Barcelona,647 Diagonal, E-08028 Barcelona (Spain); Gonzalez-Garcia, M.C. [Institució Catalana de Recerca i Estudis Avançats (ICREA),Passeig Lluís Companys, 23, E-08010 Barcelona (Spain); Departament d’Estructura i Constituents de la Matèria and ICC-UB, Universitat de Barcelona,647 Diagonal, E-08028 Barcelona (Spain); C.N. Yang Institute for Theoretical Physics and Department of Physics and Astronomy,SUNY at Stony Brook, Stony Brook, NY 11794-3840 (United States); Merlo, L. [Departamento de Física Teórica and Instituto de Física Teórica, IFT-UAM/CSIC,Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid (Spain); Rigolin, S. [Dipartimento di Fisica e Astronomia “G. Galilei”, Università di Padova and INFN, Sezione di Padova, Via Marzolo 8, I-35131 Padua (Italy)
2014-03-05
The pattern of deviations from Standard Model predictions and couplings is different for theories of new physics based on a non-linear realization of the SU(2){sub L}×U(1){sub Y} gauge symmetry breaking and those assuming a linear realization. We clarify this issue in a model-independent way via its effective Lagrangian formulation in the presence of a light Higgs particle, up to first order in the expansions: dimension-six operators for the linear expansion and four derivatives for the non-linear one. Complete sets of gauge and gauge-Higgs operators are considered, implementing the renormalization procedure and deriving the Feynman rules for the non-linear expansion. We establish the theoretical relation and the differences in physics impact between the two expansions. Promising discriminating signals include the decorrelation in the non-linear case of signals correlated in the linear one: some pure gauge versus gauge-Higgs couplings and also between couplings with the same number of Higgs legs. Furthermore, anomalous signals expected at first order in the non-linear realization may appear only at higher orders of the linear one, and vice versa. We analyze in detail the impact of both type of discriminating signals on LHC physics.
Perinatal hepatic infarction in twin-twin transfusion.
LENUS (Irish Health Repository)
O'Sullivan, M J
2012-02-03
We report a case of a twin pregnancy which was complicated by a twin-twin transfusion in which the recipient twin was noted to have an intra-abdominal echogenic mass. This twin died at two days of age of hepatic infarction. The donor twin was healthy at birth, at thirty weeks\\' gestation, and did not have any subsequent problems. Fetal intra-abdominal echogenicity may be a marker of hepatic infarction.
Higgs mass from neutrino-messenger mixing
International Nuclear Information System (INIS)
Byakti, Pritibhajan; Khosa, Charanjit K.; Mummidi, V.S.; Vempati, Sudhir K.
2017-01-01
The discovery of the Higgs particle at 125 GeV has put strong constraints on minimal messenger models of gauge mediation, pushing the stop masses into the multi-TeV regime. Extensions of these models with matter-messenger mixing terms have been proposed to generate a large trilinear parameter, A t , relaxing these constraints. The detailed survey of these models (DOI: 10.1007/JHEP05(2013)055; 10.1007/JHEP08(2013)093 ) so far considered messenger mixings with only MSSM superfields. In the present work, we extend the survey to MSSM with inverse-seesaw mechanism. The neutrino-sneutrino corrections to the Higgs mass in the inverse seesaw model are not significant in the minimal gauge mediation model, unless one considers messenger-matter interaction terms. We classify all possible models with messenger-matter interactions and perform thorough numerical analysis to find out the promising models. We found that out of the 17 possible models 9 of them can lead to Higgs mass within the observed value without raising the sfermion masses significantly. The successful models have stop masses ∼1.5 TeV with small or negligible mixing and yet a light CP even Higgs at 125 GeV.
Higgs mass from neutrino-messenger mixing
Energy Technology Data Exchange (ETDEWEB)
Byakti, Pritibhajan [Center for High Energy Physics, Indian Institute of Science,C.V. Raman Ave, Bangalore 560012 (India); Department of Theoretical Physics, Indian Association for the Cultivation of Science,2A & 2B Raja S.C. Mullick Road, Kolkata 700 032 (India); Khosa, Charanjit K. [Center for High Energy Physics, Indian Institute of Science,C.V. Raman Ave, Bangalore 560012 (India); Mummidi, V.S. [Harish-Chandra Research Institute,Chhatnag Road, Jhusi, Allahabad 211019 (India); Vempati, Sudhir K. [Center for High Energy Physics, Indian Institute of Science,C.V. Raman Ave, Bangalore 560012 (India)
2017-03-06
The discovery of the Higgs particle at 125 GeV has put strong constraints on minimal messenger models of gauge mediation, pushing the stop masses into the multi-TeV regime. Extensions of these models with matter-messenger mixing terms have been proposed to generate a large trilinear parameter, A{sub t}, relaxing these constraints. The detailed survey of these models (DOI: 10.1007/JHEP05(2013)055; 10.1007/JHEP08(2013)093 ) so far considered messenger mixings with only MSSM superfields. In the present work, we extend the survey to MSSM with inverse-seesaw mechanism. The neutrino-sneutrino corrections to the Higgs mass in the inverse seesaw model are not significant in the minimal gauge mediation model, unless one considers messenger-matter interaction terms. We classify all possible models with messenger-matter interactions and perform thorough numerical analysis to find out the promising models. We found that out of the 17 possible models 9 of them can lead to Higgs mass within the observed value without raising the sfermion masses significantly. The successful models have stop masses ∼1.5 TeV with small or negligible mixing and yet a light CP even Higgs at 125 GeV.
Ferreira, Paulo H; Oliveira, Vinicius C; Junqueira, Daniela R; Cisneros, Lígia C; Ferreira, Lucas C; Murphy, Kate; Ordoñana, Juan R; Hopper, John L; Teixeira-Salmela, Luci F
2016-12-01
The Brazilian Twin Registry (BTR) was established in 2013 and has impelled twin research in South America. The main aim of the initiative was to create a resource that would be accessible to the Brazilian scientific community as well as international researchers interested in the investigation of the contribution of genetic and environmental factors in the development of common diseases, phenotypes, and human behavior traits. The BTR is a joint effort between academic and governmental institutions from Brazil and Australia. The collaboration includes the Federal University of Minas Gerais (UFMG) in Brazil, the University of Sydney and University of Melbourne in Australia, the Australian Twin Registry, as well as the research foundations CNPq and CAPES in Brazil. The BTR is a member of the International Network of Twin Registries. Recruitment strategies used to register twins have been through participation in a longitudinal study investigating genetic and environmental factors for low back pain occurrence, and from a variety of sources including media campaigns and social networking. Currently, 291 twins are registered in the BTR, with data on demographics, zygosity, anthropometrics, and health history having been collected from 151 twins using a standardized self-reported questionnaire. Future BTR plans include the registration of thousands of Brazilian twins identified from different sources and collaborate nationally and internationally with other research groups interested on twin studies.
Conjoined (Siamese) Twins in Zambia
African Journals Online (AJOL)
year-old Zambian multiparous mother gave birth to a set of twins with two heads ... (symmetric or mirror image) but one twin attached with an incomplete foetus is known as hetropagtrs. (asymmetrical). Thoracopagus twins (joined at the chest).
Electroweak Higgs production with HiggsPO at NLO QCD
International Nuclear Information System (INIS)
Greljo, Admir; Isidori, Gino; Zhang, Hantian; Lindert, Jonas M.; Marzocca, David
2017-01-01
We present the HiggsPO UFO model for Monte Carlo event generation of electroweak VH and VBF Higgs production processes at NLO in QCD in the formalism of Higgs pseudo-observables (PO). We illustrate the use of this tool by studying the QCD corrections, matched to a parton shower, for several benchmark points in the Higgs PO parameter space. We find that, while being sizable and thus important to be considered in realistic experimental analyses, the QCD higher-order corrections largely factorize. As an additional finding, based on the NLO results, we advocate to consider 2D distributions of the two-jet azimuthal-angle difference and the leading jet p T for new physics searches in VBF Higgs production. The HiggsPO UFO model is publicly available. (orig.)
Electroweak Higgs production with HiggsPO at NLO QCD
Greljo, Admir; Isidori, Gino; Lindert, Jonas M.; Marzocca, David; Zhang, Hantian
2017-12-01
We present the HiggsPO UFO model for Monte Carlo event generation of electroweak VH and VBF Higgs production processes at NLO in QCD in the formalism of Higgs pseudo-observables (PO). We illustrate the use of this tool by studying the QCD corrections, matched to a parton shower, for several benchmark points in the Higgs PO parameter space. We find that, while being sizable and thus important to be considered in realistic experimental analyses, the QCD higher-order corrections largely factorize. As an additional finding, based on the NLO results, we advocate to consider 2D distributions of the two-jet azimuthal-angle difference and the leading jet p_T for new physics searches in VBF Higgs production. The HiggsPO UFO model is publicly available.
Electroweak Higgs production with HiggsPO at NLO QCD
Energy Technology Data Exchange (ETDEWEB)
Greljo, Admir [Universitaet Zuerich, Physik-Institut, Zurich (Switzerland); Johannes Gutenberg-Universitaet Mainz, PRISMA Cluster of Excellence and Mainz Institute for Theoretical Physics, Mainz (Germany); University of Sarajevo, Faculty of Science, Sarajevo (Bosnia and Herzegovina); Isidori, Gino; Zhang, Hantian [Universitaet Zuerich, Physik-Institut, Zurich (Switzerland); Lindert, Jonas M. [Durham University, Department of Physics, Institute for Particle Physics Phenomenology, Durham (United Kingdom); Marzocca, David [Universitaet Zuerich, Physik-Institut, Zurich (Switzerland); INFN, Sezione di Trieste(Italy); SISSA, Trieste (Italy)
2017-12-15
We present the HiggsPO UFO model for Monte Carlo event generation of electroweak VH and VBF Higgs production processes at NLO in QCD in the formalism of Higgs pseudo-observables (PO). We illustrate the use of this tool by studying the QCD corrections, matched to a parton shower, for several benchmark points in the Higgs PO parameter space. We find that, while being sizable and thus important to be considered in realistic experimental analyses, the QCD higher-order corrections largely factorize. As an additional finding, based on the NLO results, we advocate to consider 2D distributions of the two-jet azimuthal-angle difference and the leading jet p{sub T} for new physics searches in VBF Higgs production. The HiggsPO UFO model is publicly available. (orig.)
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.
Low-Data Investigation of Higgs Boson Discovery at the LHC
Scoby, Cheyne M
2006-01-01
The Standard Model (SM) remains as a complete and effective tool for understanding fundamental particles and their interactions. There is only one particle that the model predicts that has not yet been discovered. The Higgs boson is required as part of the mechanism behind electroweak symmetry breaking, and explains how the weak vector bosons, as well as the charged quarks and leptons gain mass, proportional to their coupling to the Higgs field. The SM predicts many properties of the Higgs, b...
Prospects for Higgs physics at energies up to 100 TeV.
Baglio, Julien; Djouadi, Abdelhak; Quevillon, Jérémie
2016-11-01
We summarize the prospects for Higgs boson physics at future proton-proton colliders with centre of mass (c.m.) energies up to 100 TeV. We first provide the production cross sections for the Higgs boson of the Standard Model from 13 TeV to 100 TeV, in the main production mechanisms and in subleading but important ones such as double Higgs production, triple production and associated production with two gauge bosons or with a single top quark. We then discuss the production of Higgs particles in beyond the Standard Model scenarios, starting with the one in the continuum of a pair of scalar, fermionic and vector dark matter particles in Higgs-portal models in various channels with virtual Higgs exchange. The cross sections for the production of the heavier CP-even and CP-odd neutral Higgs states and the charged Higgs states in two-Higgs doublet models, with a specific study of the case of the Minimal Supersymmetric Standard Model, are then given. The sensitivity of a 100 TeV proton machine to probe the new Higgs states is discussed and compared to that of the LHC with a c.m. energy of 14 TeV and at high luminosity.
Axionic landscape for Higgs coupling near-criticality
Cline, James M.; Espinosa, José R.
2018-02-01
The measured value of the Higgs quartic coupling λ is peculiarly close to the critical value above which the Higgs potential becomes unstable, when extrapolated to high scales by renormalization group running. It is tempting to speculate that there is an anthropic reason behind this near-criticality. We show how an axionic field can provide a landscape of vacuum states in which λ scans. These states are populated during inflation to create a multiverse with different quartic couplings, with a probability distribution P that can be computed. If P is peaked in the anthropically forbidden region of Higgs instability, then the most probable universe compatible with observers would be close to the boundary, as observed. We discuss three scenarios depending on the Higgs vacuum selection mechanism: decay by quantum tunneling, by thermal fluctuations, or by inflationary fluctuations.
Superhorizon electromagnetic field background from Higgs loops in inflation
Kaya, Ali
2018-03-01
If Higgs is a spectator scalar, i.e. if it is not directly coupled to the inflaton, superhorizon Higgs modes must have been exited during inflation. Since Higgs is unstable its decay into photons is expected to seed superhorizon photon modes. We use in-in perturbation theory to show that this naive physical expectation is indeed fulfilled via loop effects. Specifically, we calculate the first order Higgs loop correction to the magnetic field power spectrum evaluated at some late time after inflation. It turns out that this loop correction becomes much larger than the tree-level power spectrum at the superhorizon scales. This suggests a mechanism to generate cosmologically interesting superhorizon vector modes by scalar-vector interactions.
Prevention of preterm delivery in twin pregnancy
DEFF Research Database (Denmark)
Rode, Line; Tabor, Ann
2014-01-01
The incidence of twin gestation has increased markedly over the past decades, mostly because of increased use of assisted reproductive technologies. Twin pregnancies are at increased risk of preterm delivery (i.e. birth before 37 weeks of gestation). Multiple gestations therefore account for 2...... sequelae such as abnormal neurophysiological development in early childhood and underachievement in school. Several treatment modalities have been proposed in singleton high-risk pregnancies. The mechanism of initiating labour may, however, be different in singleton and twin gestations. Therefore......, it is mandatory to evaluate the proposed treatments in randomised trials of multiple gestations. In this chapter, we describe the results of trials to prevent preterm delivery in twin pregnancies....
Micromechanics of twinning in a TWIP steel
International Nuclear Information System (INIS)
Rahman, K.M.; Jones, N.G.; Dye, D.
2015-01-01
The deformation behaviour of a TWinning Induced Plasticity (TWIP) steel was studied at quasi-static strain rates using synchrotron X-ray diffraction. A {111} RD and {200} RD texture developed from the earliest stages of deformation, which could be reproduced using an elasto-plastic self consistent (EPSC) model. Evidence is found from multiple sources to suggest that twinning was occurring before macroscopic yielding. This included small deviations in the lattice strains, {111} intensity changes and peak width broadening all occurring below the macroscopic yield point. The accumulation of permanent deformation on sub-yield mechanical cycling of the material was found, which further supports the diffraction data. TEM revealed that fine deformation twins similar to those observed in heavily deformed samples formed during sub-yield cycling. It is concluded that twinning had occurred before macroscopic plastic deformation began, unlike the behaviour traditionally expected from hexagonal metals such as Mg
Micromechanics of twinning in a TWIP steel
Energy Technology Data Exchange (ETDEWEB)
Rahman, K.M., E-mail: khandaker.rahman05@imperial.ac.uk [Department of Materials, Royal School of Mines, Imperial College London, Prince Consort Road, London SW7 2BP (United Kingdom); Jones, N.G. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Dye, D. [Department of Materials, Royal School of Mines, Imperial College London, Prince Consort Road, London SW7 2BP (United Kingdom)
2015-05-21
The deformation behaviour of a TWinning Induced Plasticity (TWIP) steel was studied at quasi-static strain rates using synchrotron X-ray diffraction. A {111} RD and {200} RD texture developed from the earliest stages of deformation, which could be reproduced using an elasto-plastic self consistent (EPSC) model. Evidence is found from multiple sources to suggest that twinning was occurring before macroscopic yielding. This included small deviations in the lattice strains, {111} intensity changes and peak width broadening all occurring below the macroscopic yield point. The accumulation of permanent deformation on sub-yield mechanical cycling of the material was found, which further supports the diffraction data. TEM revealed that fine deformation twins similar to those observed in heavily deformed samples formed during sub-yield cycling. It is concluded that twinning had occurred before macroscopic plastic deformation began, unlike the behaviour traditionally expected from hexagonal metals such as Mg.
International Nuclear Information System (INIS)
Hueffel, H.
1980-01-01
In the framework of the minimal SU(5) model of Georgi and Glashow the explicit couplings between the various mass eigenstate Higgs bosons and the gauge fields as well as the Higgs boson self couplings are presented. As an application bounds for the parameters of the Higgs potential and for the Higgs boson masses are derived by applying partial wave unitarity to the tree graphs of Higgs-Higgs scattering. (Auth.)
The Higgs portal above threshold
Energy Technology Data Exchange (ETDEWEB)
Craig, Nathaniel [Department of Physics, University of California,Santa Barbara, CA 93106 (United States); Lou, Hou Keong [Department of Physics, Princeton University,Princeton, NJ 08540 (United States); McCullough, Matthew [Theory Division, CERN,1211 Geneva 23 (Switzerland); Thalapillil, Arun [Department of Physics and Astronomy, Rutgers University,Piscataway, NJ 08854 (United States)
2016-02-18
The discovery of the Higgs boson opens the door to new physics interacting via the Higgs Portal, including motivated scenarios relating to baryogenesis, dark matter, and electroweak naturalness. We systematically explore the collider signatures of singlet scalars produced via the Higgs Portal at the 14 TeV LHC and a prospective 100 TeV hadron collider. We focus on the challenging regime where the scalars are too heavy to be produced in the decays of an on-shell Higgs boson, and instead are produced primarily via an off-shell Higgs. Assuming these scalars escape the detector, promising channels include missing energy in association with vector boson fusion, monojets, and top pairs. We forecast the sensitivity of searches in these channels at √s=14 & 100 TeV and compare collider reach to the motivated parameter space of singlet-assisted electroweak baryogenesis, Higgs Portal dark matter, and neutral naturalness.
Energy Technology Data Exchange (ETDEWEB)
Barbón, J.L.F.; Casas, J.A. [IFT-UAM/CSIC, Universidad Autónoma de Madrid,C/Nicolás Cabrera 13, 28049 Madrid (Spain); Elias-Miró, J. [Departament de Física/IFAE, Universitat Autònoma de Barcelona,Edifici Cn, 08193 Bellaterra, Barcelona (Spain); Espinosa, J.R. [ICREA/IFAE, Universitat Autònoma de Barcelona,Edifici Cn, 08193 Bellaterra, Barcelona (Spain)
2015-09-04
We discuss a simple unitarization of Higgs inflation that is genuinely weakly coupled up to Planckian energies. A large non-minimal coupling between the Higgs and the Ricci curvature is induced dynamically at intermediate energies, as a simple ratio of mass scales. Despite not being dominated by the Higgs field, inflationary dynamics simulates the ‘Higgs inflation’ one would get by blind extrapolation of the low-energy effective Lagrangian, at least qualitatively. Hence, Higgs inflation arises as an approximate ‘mirage’ picture of the true dynamics. We further speculate on the generality of this phenomenon and show that, if Higgs-inflation arises as an effective description, the details of the UV completion are necessary to extract robust quantitative predictions.
Heavy Higgs searches. Flavour matters
International Nuclear Information System (INIS)
Gori, Stefania; Paul, Ayan
2017-10-01
We point out that the stringent lower bounds on the masses of additional electrically neutral and charged Higgs bosons crucially depend on the flavour structure of their Yukawa interactions. We show that these bounds can easily be evaded by the introduction of flavour-changing neutral currents in the Higgs sector. As an illustration, we study the phenomenology of a two Higgs doublet model with a Yukawa texture singling out the third family of quarks and leptons. We combine constraints from low-energy flavour physics measurements, LHC measurements of the 125 GeV Higgs boson rates, and LHC searches for new heavy Higgs bosons. We propose novel LHC searches that could be performed in the coming years to unravel the existence of these new Higgs bosons.
The Higgs portal above threshold
International Nuclear Information System (INIS)
Craig, Nathaniel; Lou, Hou Keong; McCullough, Matthew; Thalapillil, Arun
2016-01-01
The discovery of the Higgs boson opens the door to new physics interacting via the Higgs Portal, including motivated scenarios relating to baryogenesis, dark matter, and electroweak naturalness. We systematically explore the collider signatures of singlet scalars produced via the Higgs Portal at the 14 TeV LHC and a prospective 100 TeV hadron collider. We focus on the challenging regime where the scalars are too heavy to be produced in the decays of an on-shell Higgs boson, and instead are produced primarily via an off-shell Higgs. Assuming these scalars escape the detector, promising channels include missing energy in association with vector boson fusion, monojets, and top pairs. We forecast the sensitivity of searches in these channels at √s=14 & 100 TeV and compare collider reach to the motivated parameter space of singlet-assisted electroweak baryogenesis, Higgs Portal dark matter, and neutral naturalness.
Heavy Higgs searches. Flavour matters
Energy Technology Data Exchange (ETDEWEB)
Gori, Stefania [Cincinnati Univ., OH (United States). Dept. of Physics; Grojean, Christophe [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Juste, Aurelio [Institut de Fisica d' Altes Energies (IFAE), Barcelona (Spain); Institucio Catalanade Recerca i Estudis Avancats (ICREA), Barcelona (Spain); Paul, Ayan [INFN, Sezione di Roma (Italy)
2017-10-15
We point out that the stringent lower bounds on the masses of additional electrically neutral and charged Higgs bosons crucially depend on the flavour structure of their Yukawa interactions. We show that these bounds can easily be evaded by the introduction of flavour-changing neutral currents in the Higgs sector. As an illustration, we study the phenomenology of a two Higgs doublet model with a Yukawa texture singling out the third family of quarks and leptons. We combine constraints from low-energy flavour physics measurements, LHC measurements of the 125 GeV Higgs boson rates, and LHC searches for new heavy Higgs bosons. We propose novel LHC searches that could be performed in the coming years to unravel the existence of these new Higgs bosons.
International Nuclear Information System (INIS)
Barbón, J.L.F.; Casas, J.A.; Elias-Miró, J.; Espinosa, J.R.
2015-01-01
We discuss a simple unitarization of Higgs inflation that is genuinely weakly coupled up to Planckian energies. A large non-minimal coupling between the Higgs and the Ricci curvature is induced dynamically at intermediate energies, as a simple ratio of mass scales. Despite not being dominated by the Higgs field, inflationary dynamics simulates the ‘Higgs inflation’ one would get by blind extrapolation of the low-energy effective Lagrangian, at least qualitatively. Hence, Higgs inflation arises as an approximate ‘mirage’ picture of the true dynamics. We further speculate on the generality of this phenomenon and show that, if Higgs-inflation arises as an effective description, the details of the UV completion are necessary to extract robust quantitative predictions.
Twin anemia polycythemia sequence
Slaghekke, Femke
2014-01-01
In this thesis we describe that Twin Anemia Polycythemia Sequence (TAPS) is a form of chronic feto-fetal transfusion in monochorionic (identical) twins based on a small amount of blood transfusion through very small anastomoses. For the antenatal diagnosis of TAPS, Middle Cerebral Artery – Peak
DEFF Research Database (Denmark)
Skytthe, Axel; Ohm Kyvik, Kirsten; Vilstrup Holm, Niels
2011-01-01
Introduction: The Danish Twin Registry is a unique source for studies of genetic, familial and environmental factors on life events, health conditions and diseases. Content: More than 85,000 twin pairs born 1870-2008 in Denmark. Validity and coverage: Four main ascertainment methods have been emp...
Light Higgs from Scalar See-Saw in Technicolor
DEFF Research Database (Denmark)
Foadi, Roshan; Frandsen, Mads Toudal
2012-01-01
We consider a TeV scale see-saw mechanism leading to light scalar resonances in models with otherwise intrinsically heavy scalars. The mechanism can provide a 125 GeV technicolor Higgs in e.g. two-scale TC models......We consider a TeV scale see-saw mechanism leading to light scalar resonances in models with otherwise intrinsically heavy scalars. The mechanism can provide a 125 GeV technicolor Higgs in e.g. two-scale TC models...
Maximally Symmetric Composite Higgs Models.
Csáki, Csaba; Ma, Teng; Shu, Jing
2017-09-29
Maximal symmetry is a novel tool for composite pseudo Goldstone boson Higgs models: it is a remnant of an enhanced global symmetry of the composite fermion sector involving a twisting with the Higgs field. Maximal symmetry has far-reaching consequences: it ensures that the Higgs potential is finite and fully calculable, and also minimizes the tuning. We present a detailed analysis of the maximally symmetric SO(5)/SO(4) model and comment on its observational consequences.
Smith, Gordon C S; Pell, Jill P; Dobbie, Richard
2002-01-01
Objective To determine whether twins born second are at increased risk of perinatal death because of complications during labour and delivery. Design Retrospective cohort study. Setting Scotland, 1992 and 1997. Participants All twin births at or after 24 weeks' gestation, excluding twin pairs in which either twin died before labour or delivery or died during or after labour and delivery because of congenital abnormality, non-immune hydrops, or twin to twin transfusion syndrome. Main outcome measure Delivery related perinatal deaths (deaths during labour or the neonatal period). Results Overall, delivery related perinatal deaths were recorded for 23 first twins only and 23 second twins only of 1438 twin pairs born before 36 weeks (preterm) by means other than planned caesarean section (P>0.99). No deaths of first twins and nine deaths of second twins (P=0.004) were recorded among the 2436 twin pairs born at or after 36 weeks (term). Discordance between first and second twins differed significantly in preterm and term births (P=0.007). Seven of nine deaths of second twins at term were due to anoxia during the birth (2.9 (95% confidence interval 1.2 to 5.9) per 1000); five of these deaths were associated with mechanical problems with the second delivery following vaginal delivery of the first twin. No deaths were recorded among 454 second twins delivered at term by planned caesarean section. Conclusions Second twins born at term are at higher risk than first twins of death due to complications of delivery. Previous studies may not have shown an increased risk because of inadequate categorisation of deaths, lack of statistical power, inappropriate analyses, and pooling of data about preterm births and term births. What is already known on this topicIt is difficult to assess the wellbeing of second twins during labourDeliveries of second twins are at increased risk of mechanical problems, such as cord prolapse and malpresentation, after vaginal delivery of first twins
μ- conversion via doubly charged Higgs scalar
International Nuclear Information System (INIS)
Picciotto, C.E.; Zahir, M.S.
1982-10-01
A new mechanism is used to calculate μ - → e + conversion in nuclei, based on the existence of a doubly charged Higgs scalar. The scalar is part of a triplet which generates the spontaneous breakdown of B-L symmetry in an extension of the standard model, as proposed by Gelmini and Roncadelli. We find a limit for conversion rates which is comparable to those of earlier calculations
Light Higgs from pole attractor
International Nuclear Information System (INIS)
Matsedonskyi, Oleksii; Montull, Marc
2017-09-01
We propose a new way of explaining the observed Higgs mass, within the cosmological relaxation framework. The key feature distinguishing it from other scanning scenarios is that the scanning field has a non-canonical kinetic term, whose role is to terminate the scan around the desired Higgs mass value. We propose a concrete realisation of this idea with two new singlet fields, one that scans the Higgs mass, and another that limits the time window in which the scan is possible. Within the provided time period, the scanning field does not significantly evolve after the Higgs field gets close to the Standard Model value, due to particle production friction.
International Nuclear Information System (INIS)
Ekspong, G.
1981-11-01
Among possible production reactions for neutral Higgs bosons it is known that e + e - →Z 0 +H 0 offers advantages of relatively high production cross section and low background from other reactions. With Z 0 decaying to two electrons, which are measured, the existence of a Higgs candidate will be seen as a peak in the missing mass spectrum. It is shown that a sufficiently good mass resolution is obtainable to make a search for Higgs feasible at LEP. In its first phase, the energy of LEP limits the search to Higgs bosons of mass around 10 GeV. (Auth.)
Higgs mass bounds from a chirally invariant lattice Higgs-Yukawa model with overlap fermions
International Nuclear Information System (INIS)
Gerhold, Philipp; Kallarackal, Jim
2008-10-01
We study the parameter dependence of the Higgs mass in a chirally invariant lattice Higgs-Yukawa model emulating the same Higgs-fermion coupling structure as in the Higgs sector of the electroweak Standard Model. Eventually, the aim is to establish upper and lower Higgs mass bounds. Here we present our preliminary results on the lower Higgs mass bound at several selected values for the cutoff and give a brief outlook towards the upper Higgs mass bound. (orig.)
The limit of the Yang-Mills-Higgs flow on Higgs bundles
Li, Jiayu; Zhang, Xi
2014-01-01
In this paper, we consider the gradient flow of the Yang-Mills-Higgs functional for Higgs pairs on a Hermitian vector bundle $(E, H_{0})$ over a compact K\\"ahler manifold $(M, \\omega )$. We study the asymptotic behavior of the Yang-Mills-Higgs flow for Higgs pairs at infinity, and show that the limiting Higgs sheaf is isomorphic to the double dual of the graded Higgs sheaves associated to the Harder-Narasimhan-Seshadri filtration of the initial Higgs bundle.
Integrating over Higgs branches
International Nuclear Information System (INIS)
Moore, G.; Shatashvili, S.
2000-01-01
We develop some useful techniques for integrating over Higgs branches in supersymmetric theories with 4 and 8 supercharges. In particular, we define a regularized volume for hyperkaehler quotients. We evaluate this volume for certain ALE and ALF spaces in terms of the hyperkaehler periods. We also reduce these volumes for a large class of hyperkaehler quotients to simpler integrals. These quotients include complex coadjoint orbits, instanton moduli spaces on R 4 and ALE manifolds, Hitchin spaces, and moduli spaces of (parabolic) Higgs bundles on Riemann surfaces. In the case of Hitchin spaces the evaluation of the volume reduces to a summation over solutions of Bethe ansatz equations for the non-linear Schroedinger system. We discuss some applications of our results. (orig.)
2001-01-01
This track is an example of real data collected from the DELPHI detector on the Large Electron-Positron (LEP) collider at CERN, which ran between 1989 and 2000. Its topology is compatible with what is expected from the associated production of a Z boson and Higgs boson of mass 113 GeV that each decay into two jets. A different pairing of the jets could lead to an interpretation compatible with the production of two Z bosons.
Indian Academy of Sciences (India)
2012-10-06
Oct 6, 2012 ... confidence level (CL) established at LEP2 [4]. ... particle is not self-consistent at high energies as it leads to ... matter and thus impact their density in the Universe today. ... s = 7 TeV LHC, lead to a K-factor KNLO ∼ 1.8 in the low Higgs mass ...... See Michael Spira, http://people.web.psi.ch/spira/proglist.html.
Energy Technology Data Exchange (ETDEWEB)
Dobrescu, Bogdan A.; Fox, Patrick J.; Kearney, John [Fermilab, Theoretical Physics Department, Batavia, IL (United States)
2017-10-15
We study models that produce a Higgs boson plus photon (h{sup 0}γ) resonance at the LHC. When the resonance is a Z{sup '} boson, decays to h{sup 0}γ occur at one loop. If the Z{sup '} boson couples at tree level to quarks, then the h{sup 0}γ branching fraction is typically of order 10{sup -5} or smaller. Nevertheless, there are models that would allow the observation of Z{sup '} → h{sup 0}γ at √(s) = 13 TeV with a cross section times branching fraction larger than 1 fb for a Z{sup '} mass in the 200-450 GeV range, and larger than 0.1 fb for a mass up to 800 GeV. The one-loop decay of the Z{sup '} into lepton pairs competes with h{sup 0}γ, even if the Z{sup '} couplings to leptons vanish at tree level. We also present a model in which a Z{sup '} boson decays into a Higgs boson and a pair of collimated photons, mimicking an h{sup 0}γ resonance. In this model, the h{sup 0}γ resonance search would be the discovery mode for a Z{sup '} as heavy as 2 TeV. When the resonance is a scalar, although decay to h{sup 0}γ is forbidden by angular momentum conservation, the h{sup 0} plus collimated photons channel is allowed. We comment on prospects of observing an h{sup 0}γ resonance through different Higgs decays, on constraints from related searches, and on models where h{sup 0} is replaced by a nonstandard Higgs boson. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Buchmueller, O. [Imperial College, London (United Kingdom). High Energy Physics Group; Cavanaugh, R. [Fermi National Accelerator Laboratory, Batavia, IL (United States); Illinois Univ, Chicago, IL (United States). Physics Dept.; Roeck, A. de [CERN, Geneva (Switzerland); Antwerp Univ., Wilrijk (BE)] (and others)
2011-12-15
Global frequentist fits to the CMSSM and NUHM1 using the MasterCode framework predicted M{sub h}{approx_equal}119 GeV in fits incorporating the (g-2){mu} constraint and {approx_equal}126 GeV without it. Recent results by ATLAS and CMS could be compatible with a Standard Model-like Higgs boson around M{sub h}{approx_equal}125 GeV. We use the previous MasterCode analysis to calculate the likelihood for a measurement of any nominal Higgs mass within the range of 115 to 130 GeV. Assuming a Higgs mass measurement at M{sub h}{approx_equal}125 GeV, we display updated global likelihood contours in the (m{sub 0},m{sub 1/2}) and other parameter planes of the CMSSM and NUHM1, and present updated likelihood functions for m{sub g}, m{sub q{sub R}}, BR(B{sub s} {yields} {mu}{sup +}{mu}{sup -}) and the spin-independent dark matter cross section {sigma}{sup SI}{sub p}. The implications of dropping (g-2){sub {mu}} from the fits are also discussed. We furthermore comment on a hypothetical measurement of M{sub h}{approx_equal}119 GeV. (orig.)
Is radiative electroweak symmetry breaking consistent with a 125 GeV Higgs mass?
Steele, T G; Wang, Zhi-Wei
2013-04-12
The mechanism of radiative electroweak symmetry breaking occurs through loop corrections, and unlike conventional symmetry breaking where the Higgs mass is a parameter, the radiatively generated Higgs mass is dynamically predicted. Padé approximations and an averaging method are developed to extend the Higgs mass predictions in radiative electroweak symmetry breaking from five- to nine-loop order in the scalar sector of the standard model, resulting in an upper bound on the Higgs mass of 141 GeV. The mass predictions are well described by a geometric series behavior, converging to an asymptotic Higgs mass of 124 GeV consistent with the recent ATLAS and CMS Collaborations observations. Similarly, we find that the Higgs self-coupling converges to λ=0.23, which is significantly larger than its conventional symmetry breaking counterpart for a 124 GeV Higgs mass. In addition to this significant enhancement of the Higgs self-coupling and HH→HH scattering, we find that Higgs decays to gauge bosons are unaltered and the scattering processes WL(+)WL(+)→HH, ZLZL→HH are also enhanced, providing signals to distinguish conventional and radiative electroweak symmetry breaking mechanisms.
Twin Pregnancy with Gastroschisis in Both Twins
Directory of Open Access Journals (Sweden)
Hui-Fen Kao
2007-12-01
Conclusion: The cause of gastroschisis is unknown, although possible exogenous causes have been studied. The diagnosis of gastroschisis in twin pregnancy is always in late gestation. Therefore, maternal serum alpha feto-protein screening and a detailed prenatal ultrasound evaluation are recommended in multifetal pregnancies.
Directory of Open Access Journals (Sweden)
Božinović Dragica
2012-01-01
Full Text Available Multiple pregnancy is a pregnancy where more than one fetus develops simultaneously in the womb, as a result of the ovulation and fertilization of more than one egg. It is relatively rare in humans and represents the rest of the phylogenetic stages. The most common are twins and they indicate the development of two fetuses in the womb. The frequency of twin pregnancies is about 1%. Multiple pregnancies belong to a group of high-risk pregnancies because of the many complications that occur during the pregnancy: higher number of premature deliveries, bleeding, early neonatal complications and higher perinatal morbidity and mortality. Such pregnancies and infants require greater supervision and monitoring. The aim of this study was to determine the percentage of baby twins born at the maternity ward of the General Hospital in Prokuplje and their morbidity and mortality. Data on the total number of deliveries, number of twins, parity and maternal age, gestational age, body weight of twins, method of delivery, Apgar score and perinatal mortality were collected and statistically analyzed by means of retrospective analysis of operative birth and neonatal protocol for 6 years (2005 of 2010. Out of 4527 mothers who gave birth 43 were pairs of twins, or 0.95% of women gave birth to twins. These babies are more likely born by Caesarean section, but delivered with slightly lower birth weight.
Liang, G
2005-01-01
The Standard Model (SM) of particle physics has been the most successful theory about fundamental particles and how they interact. In SM, the originally massless fundamental particles acquire masses in a process called the Higgs mechanism. This mechanism involves an additional particle, called the Higgs boson, whose responsibility is to break the electroweak symmetry and help those massless particles acquire masses. With the discovery of the top quark at Tevatron in 1995, the Higgs boson remains to be the only unfound fundamental particle in the Standard Model. The discovery of the Higgs boson would greatly increase our understanding of the origin of the mass. One of the most important objectives of the LHC experiment is to discover the Higgs boson. At LHC, the CMS experiment is optimized for the search of the Higgs boson over a mass range up to 1 TeV. Among all Higgs decay channels, H → ZZ → 4l is one of the most promising channels to search the SM Higgs boson at CMS. This study concentrat...
Higgs mass implications on the stability of the electroweak vacuum
Energy Technology Data Exchange (ETDEWEB)
Elias-Miro, Joan [IFAE and Dep. de Fisica, Univ. Aut. de Barcelona, 08193 Bellaterra, Barcelona (Spain); Espinosa, Jose R. [IFAE and Dep. de Fisica, Univ. Aut. de Barcelona, 08193 Bellaterra, Barcelona (Spain); ICREA, Institucio Catalana de Recerca i Estudis Avancats, Barcelona (Spain); Giudice, Gian F. [CERN, Theory Division, CH-1211 Geneva 23 (Switzerland); Isidori, Gino, E-mail: gino.isidori@lnf.infn.it [CERN, Theory Division, CH-1211 Geneva 23 (Switzerland); INFN, Laboratori Nazionali di Frascati, Via E. Fermi 40, Frascati (Italy); Riotto, Antonio [CERN, Theory Division, CH-1211 Geneva 23 (Switzerland); INFN, Sezione di Padova, Via Marzolo 8, I-35131 Padua (Italy); Strumia, Alessandro [Dipartimento di Fisica dell' Universita di Pisa and INFN (Italy); National Institute of Chemical Physics and Biophysics, Ravala 10, Tallinn (Estonia)
2012-03-19
We update instability and metastability bounds of the Standard Model electroweak vacuum in view of the recent ATLAS and CMS Higgs results. For a Higgs mass in the range 124-126 GeV, and for the current central values of the top mass and strong coupling constant, the Higgs potential develops an instability around 10{sup 11} GeV, with a lifetime much longer than the age of the Universe. However, taking into account theoretical and experimental errors, stability up to the Planck scale cannot be excluded. Stability at finite temperature implies an upper bound on the reheat temperature after inflation, which depends critically on the precise values of the Higgs and top masses. A Higgs mass in the range 124-126 GeV is compatible with very high values of the reheating temperature, without conflict with mechanisms of baryogenesis such as leptogenesis. We derive an upper bound on the mass of heavy right-handed neutrinos by requiring that their Yukawa couplings do not destabilize the Higgs potential.
Higgs mass implications on the stability of the electroweak vacuum
Elias-Miro, Joan; Giudice, Gian F; Isidori, Gino; Riotto, Antonio; Strumia, Alessandro
2012-01-01
We update instability and metastability bounds of the Standard Model electroweak vacuum in view of the recent ATLAS and CMS Higgs results. For a Higgs mass in the range 124--126 GeV, and for the current central values of the top mass and strong coupling constant, the Higgs potential develops an instability around $10^{11}$ GeV, with a lifetime much longer than the age of the Universe. However, taking into account theoretical and experimental errors, stability up to the Planck scale cannot be excluded. Stability at finite temperature implies an upper bound on the reheat temperature after inflation, which depends critically on the precise values of the Higgs and top masses. A Higgs mass in the range 124--126 GeV is compatible with very high values of the reheating temperature, without conflict with mechanisms of baryogenesis such as leptogenesis. We derive an upper bound on the mass of heavy right-handed neutrinos by requiring that their Yukawa couplings do not destabilize the Higgs potential.
Triple Higgs boson production in the linear collider
International Nuclear Information System (INIS)
Ferrera, Giancarlo; Guasch, Jaume; Lopez-Val, David; Sola, Joan
2008-01-01
Triple Higgs boson production (3H) may provide essential information to reconstruct the Higgs potential. We consider 3H-production in the International Linear Collider (ILC) both in the Minimal Supersymmetric Standard Model (MSSM) and in the general Two-Higgs-Doublet Model (2HDM). We compute the total cross-section for the various 3H final states, such as H + H - h 0 , H 0 A 0 h 0 , etc., and compare with the more traditional double Higgs (2H) boson production processes. While the cross-sections for the 2H final states lie within the same order of magnitude in both the MSSM and 2HDM, we find that for the 3H states the maximum 2HDM cross-sections, being of order 0.1 pb, are much larger than the MSSM ones which, in most cases, are of order 10 -6 pb or less. Actually, the 3H processes could be the dominant mechanism for Higgs boson production in the 2HDM. Ultimately, the origin of the remarkable enhancement of the 3H channels in the 2HDM case (for both type I and type II models) originates in the structure of the trilinear Higgs boson couplings. The extremely clean environment of the ILC should allow a relatively comfortable tagging of the three Higgs boson events. In view of the fact that the MSSM contribution is negligible, these events should manifest themselves mainly in the form of 6 heavy-quark jet final states. Some of these signatures could be spectacular, and in case of being detected would constitute strong evidence of an extended Higgs sector of non-supersymmetric origin
Hydride formation on deformation twin in zirconium alloy
Energy Technology Data Exchange (ETDEWEB)
Kim, Ju-Seong [Korea Atomic Energy Research Institute, 989-111 Daedeokdaero, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of); Kim, Sung-Dae [Korea Institute of Material Science (KIMS), 797 Changwondaero, Changwon, Gyeongnam, 642-831 (Korea, Republic of); Yoon, Jonghun, E-mail: yooncsmd@gmail.com [Department of Mechanical Engineering, Hanyang University, 1271 Sa3-dong, Sangrok-gu, Ansan-si, Gyeonggi-do, 426-791 (Korea, Republic of)
2016-12-15
Hydrides deteriorate the mechanical properties of zirconium (Zr) alloys used in nuclear reactors. Intergranular hydrides that form along grain boundaries have been extensively studied due to their detrimental effects on cracking. However, it has been little concerns on formation of Zr hydrides correlated with deformation twins which is distinctive heterogeneous nucleation site in hexagonal close-packed metals. In this paper, the heterogeneous precipitation of Zr hydrides at the twin boundaries was visualized using transmission electron microscopy. It demonstrates that intragranular hydrides in the twinned region precipitates on the rotated habit plane by the twinning and intergranular hydrides precipitate along the coherent low energy twin boundaries independent of the conventional habit planes. Interestingly, dislocations around the twin boundaries play a substantial role in the nucleation of Zr hydrides by reducing the misfit strain energy.
Twinning interactions induced amorphisation in ultrafine silicon grains
Energy Technology Data Exchange (ETDEWEB)
Cao, Y. [School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Zhang, L.C., E-mail: liangchi.zhang@unsw.edu.au [School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Zhang, Y. [School of Mechatronics Engineering, Harbin Institute of Technology (China)
2016-03-21
Detailed transmission electron microscopy analysis on a severely deformed Al-Si composite material has revealed that partial dislocation slips and deformation twinning are the major plastic deformation carriers in ultrafine silicon grains. This resembles the deformation twinning activities and mechanisms observed in nano-crystalline face-centred-cubic metallic materials. While deformation twinning and amorphisation in Si were thought unlikely to co-exist, it is observed for the first time that excessive twinning and partial dislocation interactions can lead to localised solid state amorphisation inside ultrafine silicon grains.
Learning from Higgs physics at future Higgs factories
Energy Technology Data Exchange (ETDEWEB)
Gu, Jiayin [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Chinese Academy of Sciences, Beijing (China). Center for Future High Energy Physics; Li, Honglei [Jinan Univ., Shandong (China). School of Physics and Technology; Arizona Univ., Tucson, AZ (United States). Dept. of Physics; Liu, Zhen [Fermi National Accelerator Laboratory, Batavia, IL (United States). Theoretical Physics Dept.; Su, Shufang [Arizona Univ., Tucson, AZ (United States). Dept. of Physics; Su, Wei [Arizona Univ., Tucson, AZ (United States). Dept. of Physics; Chinese Academy of Sciences, Beijing (China). Inst. of Theoretical Physics; Univ. of Chinese Academy of Sciences, Beijing (China). School of Physics
2017-09-15
Future Higgs factories can reach impressive precision on Higgs property measurements. In this paper, instead of conventional focus of Higgs precision in certain interaction bases, we explored its sensitivity to new physics models at the electron-positron colliders. In particular, we studied two categories of new physics models, Standard Model (SM) with a real scalar singlet extension, and Two Higgs Double Model (2HDM) as examples of weakly-interacting models, Minimal Composite Higgs Model (MCHM) and three typical patterns of the more general operator counting for strong interacting models as examples of strong dynamics. We performed a global fit to various Higgs search channels to obtain the 95% C.L. constraints on the model parameter space. In the SM with a singlet extension, we obtained the limits on the singlet-doublet mixing angle sinθ, as well as the more general Wilson coefficients of the induced higher dimensional operators. In the 2HDM, we analyzed tree level effects in tanβ vs. cos(β-α) plane, as well as the one-loop contributions from the heavy Higgs bosons in the alignment limit to obtain the constraints on heavy Higgs masses for different types of 2HDM. In strong dynamics models, we obtained lower limits on the strong dynamics scale. In addition, once deviations of Higgs couplings are observed, they can be used to distinguish different models. We also compared the sensitivity of various future Higgs factories, namely Circular Electron Positron Collider (CEPC), Future Circular Collider (FCC)-ee and International Linear Collider (ILC).
Learning from Higgs physics at future Higgs factories
International Nuclear Information System (INIS)
Gu, Jiayin; Chinese Academy of Sciences, Beijing; Li, Honglei; Arizona Univ., Tucson, AZ; Liu, Zhen; Su, Shufang; Su, Wei; Chinese Academy of Sciences, Beijing; Univ. of Chinese Academy of Sciences, Beijing
2017-09-01
Future Higgs factories can reach impressive precision on Higgs property measurements. In this paper, instead of conventional focus of Higgs precision in certain interaction bases, we explored its sensitivity to new physics models at the electron-positron colliders. In particular, we studied two categories of new physics models, Standard Model (SM) with a real scalar singlet extension, and Two Higgs Double Model (2HDM) as examples of weakly-interacting models, Minimal Composite Higgs Model (MCHM) and three typical patterns of the more general operator counting for strong interacting models as examples of strong dynamics. We performed a global fit to various Higgs search channels to obtain the 95% C.L. constraints on the model parameter space. In the SM with a singlet extension, we obtained the limits on the singlet-doublet mixing angle sinθ, as well as the more general Wilson coefficients of the induced higher dimensional operators. In the 2HDM, we analyzed tree level effects in tanβ vs. cos(β-α) plane, as well as the one-loop contributions from the heavy Higgs bosons in the alignment limit to obtain the constraints on heavy Higgs masses for different types of 2HDM. In strong dynamics models, we obtained lower limits on the strong dynamics scale. In addition, once deviations of Higgs couplings are observed, they can be used to distinguish different models. We also compared the sensitivity of various future Higgs factories, namely Circular Electron Positron Collider (CEPC), Future Circular Collider (FCC)-ee and International Linear Collider (ILC).
Radiative generation of the Higgs potential
International Nuclear Information System (INIS)
Chun, Eung Jin; Jung, Sunghoon; Lee, Hyun Min
2013-01-01
We consider the minimal extension of the Standard Model with U(1) B−L gauge symmetry for generating the Higgs potential radiatively. Assuming that the full scalar potential vanishes at the vacuum instability scale, we achieve the goal in terms of two free parameters, the B−L gauge coupling and the right-handed neutrino Yukawa coupling. The B−L gauge symmetry is broken spontaneously by the Coleman–Weinberg mechanism while the scale symmetry breakdown induces electroweak symmetry breaking through the radiative generation of appropriate scalar quartic couplings. We show that there is a reasonable parameter space that is consistent with a correct electroweak symmetry breaking and the observed Higgs mass
Fundamental Composite (Goldstone) Higgs Dynamics
DEFF Research Database (Denmark)
Cacciapaglia, G.; Sannino, Francesco
2014-01-01
We provide a unified description, both at the effective and fundamental Lagrangian level, of models of composite Higgs dynamics where the Higgs itself can emerge, depending on the way the electroweak symmetry is embedded, either as a pseudo-Goldstone boson or as a massive excitation of the conden...... searches of new physics at the Large Hadron Collider....
Origins of inert Higgs doublets
Directory of Open Access Journals (Sweden)
Thomas W. Kephart
2016-05-01
Full Text Available We consider beyond the standard model embedding of inert Higgs doublet fields. We argue that inert Higgs doublets can arise naturally in grand unified theories where the necessary associated Z2 symmetry can occur automatically. Several examples are discussed.
Higgs particle searches at LEP
International Nuclear Information System (INIS)
Martin, J.P.
1996-01-01
Results on searches for the Higgs particle performed by the four LEP experiments are received in the framework of the Standard Model, Two Doublet Model, and Minimal Supersymmetric Model. The combined mass lower limit for the standard Higgs boson is 66 GeV/c 2 at 95 % CL for a statistics of 14.6 Million hadronic Z decays. (authors)
Higgs Portal into Hidden Sectors
CERN. Geneva
2007-01-01
Several attractive theoretical ideas suggest the existence of one or more 'hidden sectors' consisting of standard model singlet fields, some of which may not be too heavy. There is a profound reason to think that the Higgs sector might provide the first access to these hidden sectors. This scenario could affect Higgs phenomenology in drastic ways.
Mariotti, Chiara
2017-01-01
The first measurements of the mass, the width, and the couplings of the newly discovered Higgs boson at LHC at 7 and 8 TeV center of mass energy will be reviewed. Recent results at 13 TeV center of mass energy will be presented. Finally, searches for additional Higgs bosons in models beyond the standard model will be summarised.
Standard model without Higgs particles
International Nuclear Information System (INIS)
Kovalenko, S.G.
1992-10-01
A modification of the standard model of electroweak interactions with the nonlocal Higgs sector is proposed. Proper form of nonlocality makes Higgs particles unobservable after the electroweak symmetry breaking. They appear only as a virtual state because their propagator is an entire function. We discuss some specific consequences of this approach comparing it with the conventional standard model. (author). 12 refs
International Nuclear Information System (INIS)
Dawson, S.
1988-01-01
Experimental limits on light Higgs bosons (M/sub H/ < 5 GeV) are examined. Particular attention is paid to the process K → πH. It is shown that there may be an allowed window for light Higgs bosons between about 100 and 210 MeV. 13 refs., 2 figs
Sasakian and Parabolic Higgs Bundles
Biswas, Indranil; Mj, Mahan
2018-03-01
Let M be a quasi-regular compact connected Sasakian manifold, and let N = M/ S 1 be the base projective variety. We establish an equivalence between the class of Sasakian G-Higgs bundles over M and the class of parabolic (or equivalently, ramified) G-Higgs bundles over the base N.
The minimal curvaton-Higgs model
Energy Technology Data Exchange (ETDEWEB)
Enqvist, Kari [Helsinki Univ. and Helsinki Institute of Physics (Finland). Physics Dept.; Lerner, Rose N. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Helsinki Univ. and Helsinki Institute of Physics (Finland). Physics Dept.; Takahashi, Tomo [Saga Univ. (Japan). Dept. of Physics
2013-10-15
We present the first full study of the minimal curvaton-Higgs (MCH) model, which is a minimal interpretation of the curvaton scenario with one real scalar coupled to the standard model Higgs boson. The standard model coupling allows the dynamics of the model to be determined in detail, including effects from the thermal background and from radiative corrections to the potential. The relevant mechanisms for curvaton decay are incomplete non-perturbative decay (delayed by thermal blocking), followed by decay via a dimension-5 non-renormalisable operator. To avoid spoiling the predictions of big bang nucleosynthesis, we find the ''bare'' curvaton mass to be m{sub {sigma}}{>=}8 x 10{sup 4} GeV. To match observational data from Planck there is an upper limit on the curvaton-higgs coupling g, between 10{sup -3} and 10{sup -2}, depending on the mass. This is due to interactions with the thermal background. We find that typically non-Gaussianities are small but that if f{sub NL} is observed in the near future then m{sub {sigma}}
The minimal curvaton-Higgs model
International Nuclear Information System (INIS)
Enqvist, Kari; Lerner, Rose N.; Helsinki Univ. and Helsinki Institute of Physics; Takahashi, Tomo
2013-10-01
We present the first full study of the minimal curvaton-Higgs (MCH) model, which is a minimal interpretation of the curvaton scenario with one real scalar coupled to the standard model Higgs boson. The standard model coupling allows the dynamics of the model to be determined in detail, including effects from the thermal background and from radiative corrections to the potential. The relevant mechanisms for curvaton decay are incomplete non-perturbative decay (delayed by thermal blocking), followed by decay via a dimension-5 non-renormalisable operator. To avoid spoiling the predictions of big bang nucleosynthesis, we find the ''bare'' curvaton mass to be m σ ≥8 x 10 4 GeV. To match observational data from Planck there is an upper limit on the curvaton-higgs coupling g, between 10 -3 and 10 -2 , depending on the mass. This is due to interactions with the thermal background. We find that typically non-Gaussianities are small but that if f NL is observed in the near future then m σ 9 GeV, depending on Hubble scale during inflation. In a thermal dark matter model, the lower bound on m σ can increase substantially. The parameter space may also be affected once the baryogenesis mechanism is specified.
Freeze-In Dark Matter from a sub-Higgs Mass Clockwork Sector via the Higgs Portal
Kim, Jinsu; McDonald, John
2018-01-01
The clockwork mechanism allows extremely weak interactions and small mass scales to be understood in terms the structure of a theory. A natural application of the clockwork mechanism is to the freeze-in mechanism for dark matter production. Here we consider a Higgs portal freeze-in dark matter model based on a scalar clockwork sector with a mass scale which is less than the Higgs boson mass. The dark matter scalar is the lightest scalar of the clockwork sector. Freeze-in dark matter is produc...
Rohatgi, Aashish; Vecchio, Kenneth S.; Gray, George T.
2001-01-01
The role of stacking fault energy (SFE) in deformation twinning and work hardening was systematically studied in Cu (SFE ˜78 ergs/cm2) and a series of Cu-Al solid-solution alloys (0.2, 2, 4, and 6 wt pct Al with SFE ˜75, 25, 13, and 6 ergs/cm2, respectively). The materials were deformed under quasi-static compression and at strain rates of ˜1000/s in a Split-Hopkinson pressure bar (SHPB). The quasi-static flow curves of annealed 0.2 and 2 wt pct Al alloys were found to be representative of solid-solution strengthening and well described by the Hall-Petch relation. The quasi-static flow curves of annealed 4 and 6 wt pct Al alloys showed additional strengthening at strains greater than 0.10. This additional strengthening was attributed to deformation twins and the presence of twins was confirmed by optical microscopy. The strengthening contribution of deformation twins was incorporated in a modified Hall-Petch equation (using intertwin spacing as the “effective” grain size), and the calculated strength was in agreement with the observed quasi-static flow stresses. While the work-hardening rate of the low SFE Cu-Al alloys was found to be independent of the strain rate, the work-hardening rate of Cu and the high SFE Cu-Al alloys (low Al content) increased with increasing strain rate. The different trends in the dependence of work-hardening rate on strain rate was attributed to the difference in the ease of cross-slip (and, hence, the ease of dynamic recovery) in Cu and Cu-Al alloys.
Mass generation, the cosmological constant problem, conformal symmetry, and the Higgs boson
Mannheim, Philip D.
2017-05-01
In 2013 the Nobel Prize in Physics was awarded to Francois Englert and Peter Higgs for their work in 1964 along with the late Robert Brout on the mass generation mechanism (the Higgs mechanism) in local gauge theories. This mechanism requires the existence of a massive scalar particle, the Higgs boson, and in 2012 the Higgs boson was finally discovered at the Large Hadron Collider after being sought for almost half a century. In this article we review the work that led to the discovery of the Higgs boson and discuss its implications. We approach the topic from the perspective of a dynamically generated Higgs boson that is a fermion-antifermion bound state rather than an elementary field that appears in an input Lagrangian. In particular, we emphasize the connection with the Bardeen-Cooper-Schrieffer theory of superconductivity. We identify the double-well Higgs potential not as a fundamental potential but as a mean-field effective Lagrangian with a dynamical Higgs boson being generated through a residual interaction that accompanies the mean-field Lagrangian. We discuss what we believe to be the key challenge raised by the discovery of the Higgs boson, namely determining whether it is elementary or composite, and through study of a conformal invariant field theory model as realized with critical scaling and anomalous dimensions, suggest that the width of the Higgs boson might serve as a suitable diagnostic for discriminating between an elementary Higgs boson and a composite one. We discuss the implications of Higgs boson mass generation for the cosmological constant problem, as the cosmological constant receives contributions from the very mechanism that generates the Higgs boson mass in the first place. We show that the contribution to the cosmological constant due to a composite Higgs boson is more tractable and under control than the contribution due to an elementary Higgs boson, and is potentially completely under control if there is an underlying conformal
Higgs-Mediated Electric Dipole Moments in the MSSM An Application to Baryogenesis and Higgs Searches
Pilaftsis, Apostolos
2002-01-01
We perform a comprehensive study of the dominant two- and higher-loop contributions to the Tl(205), neutron and muon electric dipole moments induced by Higgs bosons, third-generation quarks and squarks, charginos and gluinos in the Minimal Supersymmetric Standard Model (MSSM). We find that strong correlations exist among the contributing CP-violating operators, for large stop, gluino and chargino phases, and for a wide range of values of \\tan\\beta and charged Higgs-boson masses, giving rise to large suppressions of the Tl(205) and neutron electric dipole moments below their present experimental limits. Based on this observation, we discuss the constraints that the nonobservation of electric dipole moments imposes on the radiatively-generated CP-violating Higgs sector and on the mechanism of electroweak baryogenesis in the MSSM. We improve previously suggested benchmark scenarios of maximal CP violation for analyzing direct searches of CP-violating MSSM Higgs-bosons at high-energy colliders, and stress the imp...
... Ribbon Commands Skip to main content Turn off Animations Turn on Animations Our Sponsors Log in | Register Menu Log in | ... challenges with twins. He also can suggest helpful reading material or refer you to organizations that help ...
Future prospects of Higgs Physics at CMS
Marono, Miguel Vidal
2014-01-01
The Higgs boson physics reach of the CMS detector with 300(0) fb-1 of proton-proton collisions at sqrt{s} = 14 TeV is presented. Precision measurements of the Higgs boson properties, Higgs boson pair production and self-coupling, rare Higgs boson decays, and the potential for additional Higgs bosons are discussed. The Higgs boson physics reach of the CMS detector with 300(0) fb-1 of proton-proton collisions at sqrt{s} = 14 TeV is presented. Precision measurements of the Higgs boson propert...
Segal, Nancy L
2018-02-01
Highlights from the 16th International Twin Congress, held in Madrid, Spain from November 16-18, 2017, are presented. The Twin Congress, formerly held every three years, now takes place biennially with a single-day meeting organized during the off years. This meeting is the largest gathering of scientific twin researchers, medical personnel, and representatives of multiple birth organizations in the world. This overview is followed by reviews of recent twin research and commentary concerning partner aggression, ABO incompatibility in dizygotic twins, growth discordance in a monoamniotic twin pair and twin implantation. The article closes with summaries of timely topics in the media, namely a father's finding of his long-lost twin children, early results from the NASA twin experiment, twin brothers at the center of the October 2017 Las Vegas attack, retired twin airline pilots, and clips from recent films with twin-based themes.
Higgs mass in the gauge-Higgs unification
International Nuclear Information System (INIS)
Haba, Naoyuki; Takenaga, Kazunori; Yamashita, Toshifumi
2005-01-01
The gauge-Higgs unification theory identifies the zero mode of the extra-dimensional component of the gauge field as the usual Higgs doublet. Since this degree of freedom is the Wilson line phase, the Higgs does not have the mass term nor quartic coupling at the tree level. Through quantum corrections, the Higgs can take a vacuum expectation value, and its mass is induced. The radiatively induced mass tends to be small, although it can be lifted to O(100) GeV by introducing the O(10) numbers of bulk fields. Perturbation theory becomes unreliable when a large number of bulk fields are introduced. We reanalyze the Higgs mass based on useful expansion formulae for the effective potential and find that even a small number of bulk field can have the suitable heavy Higgs mass. We show that a small (large) number of bulk fields are enough (needed) when the SUSY breaking mass is large (small). We also study the case of introducing the soft SUSY breaking scalar masses in addition to the Scherk-Schwarz SUSY breaking and obtain the heavy Higgs mass due to the effect of the scalar mass
Handbook of LHC Higgs Cross Sections: 3. Higgs Properties
Energy Technology Data Exchange (ETDEWEB)
Heinemeyer, S; et al.
2013-01-01
This Report summarizes the results of the activities in 2012 and the first half of 2013 of the LHC Higgs Cross Section Working Group. The main goal of the working group was to present the state of the art of Higgs Physics at the LHC, integrating all new results that have appeared in the last few years. This report follows the first working group report Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002) and the second working group report Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002). After the discovery of a Higgs boson at the LHC in mid-2012 this report focuses on refined prediction of Standard Model (SM) Higgs phenomenology around the experimentally observed value of 125-126 GeV, refined predictions for heavy SM-like Higgs bosons as well as predictions in the Minimal Supersymmetric Standard Model and first steps to go beyond these models. The other main focus is on the extraction of the characteristics and properties of the newly discovered particle such as couplings to SM particles, spin and CP-quantum numbers etc.
Mori, T
2001-01-01
As the LEP experiments veriﬁed the gauge interactions more and more rigorously, searches for the Higgs boson, which forms the very basis of the gauge theories, were taking on more and more importance in LEP physics. How this last missing particle in the Standard Model may be discovered (or totally excluded) will be the key to new physics beyond the Standard Model. Here I briefly describe how the LEP experiments together have closed in on this God particle during their 11 year running.
Bluj, Michal Jacek
2018-01-01
In this report we review recent Higgs boson results obtained with pp collisions at $\\sqrt{s}=\\,$13 TeV recorded by the CMS detector in 2016 for an integrated luminosity of 35.9fb$^{\\text{-1}}$. The 2016 data allowed the observation of the $H \\to \\tau\\tau$ and $H \\to WW$ decays with high significance. We also present a combined measurement based on a full set of CMS analyses performed with 2016 data. These results are compatible with the standard model predictions with precision of several measurements exceeding results from combination of ATLAS and CMS data collected in 2011 and 2012.
Boklage, Charles E
2009-06-01
Common knowledge of over a century has it that monozygotic and dizygotic twinning events occur by unrelated mechanisms: monozygotic twinning 'splits' embryos, producing anomalously re-arranged embryogenic asymmetries; dizygotic twinning begins with independent ovulations yielding undisturbed parallel embryogeneses with no expectation of departures from singleton outcomes. The anomalies statistically associated with twin births are due to the re-arranged embryos of the monozygotics. Common knowledge further requires that dizygotic pairs are dichorionic; monochorionicity is exclusive to monozygotic pairs. These are fundamental certainties in the literature of twin biology. Multiple observations contradict those common knowledge understandings. The double ovulation hypothesis of dizygotic twinning is untenable. Girl-boy twins differ subtly from all other humans of either sex, absolutely not representative of all dizygotics. Embryogenesis of dizygotic twins differs from singleton development at least as much as monozygotic embryogenesis does, and in the same ways, and the differences between singletons and twins of both zygosities represent a coherent system of re-arranged embryogenic asymmetries. Dizygotic twinning and monozygotic twinning have the same list of consequences of anomalous embryogenesis. Those include an unignorable fraction of dizygotic pairs that are in fact monochorionic, plus many more sharing co-twins' cells in tissues other than a common chorion. The idea that monozygotic and dizygotic twinning events arise from the same embryogenic mechanism is the only plausible hypothesis that might explain all of the observations.
Induced gravity with Higgs potential. Elementary interactions and quantum processes
Energy Technology Data Exchange (ETDEWEB)
Bezares Roder, Nils Manuel
2010-07-01
This work is intended to first serve as introduction in fundamental subjects of physics in order to be then able to review the mechanism of symmetry breakdown and its essential character in physics. It introduces the concept of scalar-tensor theories of gravity based on Bergmann-Wagoner models with a Higgs potential. The main physical context aimed is the problem of Dark Matter and Dark Energy. On the one hand, there is gravitation. Within this context, we have Dark Matter as an especially relevant concept. This work entails the following main contributions: - General features of Einstein's theory are introduced together with generalities of the different elementary interactions of physics from which the concepts of dark sectors and Higgs Mechanism are derived. - The concept of symmetry breaking and especially the Higgs Mechanism of mass generation are discussed in their relevance for the most different subjects of physics, especially in relation to the Standard Model of elementary particle physics with elementary Higgs fields. - Scalar-Tensor Theories are introduced in order to build in them the process of Higgs Mechanism. This is then fulfilled with a theory of induced gravity with a Higgs potential which seems renormalizable according to deWitt's power counting criterion, and with mass-generating Higgs fields which only couple gravitationally as well as with Higgs fields which act analogously to cosmon fields. - Further, the energy density of the gravitational field is derived for the specific model of induced gravity from an analogy to electrodynamics. It is shown that a nonvanishing value of pressure related to the scalar field is necessary in order to reproduce standard linear solar-relativistic dynamics. Within astrophysical considerations for flat rotation curves of galaxies, a possible dark-matter behavior is concluded within spherical symmetry. The scalar field and the dark-matter profile of total energy density are derived. An analogous
Induced gravity with Higgs potential. Elementary interactions and quantum processes
International Nuclear Information System (INIS)
Bezares Roder, Nils Manuel
2010-01-01
This work is intended to first serve as introduction in fundamental subjects of physics in order to be then able to review the mechanism of symmetry breakdown and its essential character in physics. It introduces the concept of scalar-tensor theories of gravity based on Bergmann-Wagoner models with a Higgs potential. The main physical context aimed is the problem of Dark Matter and Dark Energy. On the one hand, there is gravitation. Within this context, we have Dark Matter as an especially relevant concept. This work entails the following main contributions: - General features of Einstein's theory are introduced together with generalities of the different elementary interactions of physics from which the concepts of dark sectors and Higgs Mechanism are derived. - The concept of symmetry breaking and especially the Higgs Mechanism of mass generation are discussed in their relevance for the most different subjects of physics, especially in relation to the Standard Model of elementary particle physics with elementary Higgs fields. - Scalar-Tensor Theories are introduced in order to build in them the process of Higgs Mechanism. This is then fulfilled with a theory of induced gravity with a Higgs potential which seems renormalizable according to deWitt's power counting criterion, and with mass-generating Higgs fields which only couple gravitationally as well as with Higgs fields which act analogously to cosmon fields. - Further, the energy density of the gravitational field is derived for the specific model of induced gravity from an analogy to electrodynamics. It is shown that a nonvanishing value of pressure related to the scalar field is necessary in order to reproduce standard linear solar-relativistic dynamics. Within astrophysical considerations for flat rotation curves of galaxies, a possible dark-matter behavior is concluded within spherical symmetry. The scalar field and the dark-matter profile of total energy density are derived. An analogous relation between
Deformation twinning in irradiated ferritic/martensitic steels
Wang, K.; Dai, Y.; Spätig, P.
2018-04-01
Two different ferritic/martensitic steels were tensile tested to gain insight into the mechanisms of embrittlement induced by the combined effects of displacement damage and helium after proton/neutron irradiation in SINQ, the Swiss spallation neutron source. The irradiation conditions were in the range: 15.8-19.8 dpa (displacement per atom) with 1370-1750 appm He at 245-300 °C. All the samples fractured in brittle mode with intergranular or cleavage fracture surfaces when tested at room temperature (RT) or 300 °C. After tensile test, transmission electron microscopy (TEM) was employed to investigate the deformation microstructures. TEM-lamella samples were extracted directly below the intergranular fracture surfaces or cleavage surfaces by using the focused ion beam technique. Deformation twinning was observed in irradiated specimens at high irradiation dose. Only twins with {112} plane were observed in all of the samples. The average thickness of twins is about 40 nm. Twins initiated at the fracture surface, became gradually thinner with distance away from the fracture surface and finally stopped in the matrix. Novel features such as twin-precipitate interactions, twin-grain boundary and/or twin-lath boundary interactions were observed. Twinning bands were seen to be arrested by grain boundaries or large precipitates, but could penetrate martensitic lath boundaries. Unlike the case of defect free channels, small defect-clusters, dislocation loops and dense small helium bubbles were observed inside twins.
Higgs and confinement phases in the fundamental SU(2) Higgs model: Mean field analysis
International Nuclear Information System (INIS)
Damgaard, P.H.; Heller, U.M.
1985-01-01
The phase diagram of the four-dimensional SU(2) gauge-Higgs model with Higgs field in the fundamental representation is derived by mean field techniques. When the Higgs field is allowed to fluctuate in. Magnitude, the analytic connection between Higgs and confinement phases breaks down for sufficiently small values of the quark Higgs coupling, indicating that the Higgs and confinement phases for these couplings are strictly distinct phases. (orig.)
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)
Higgs-strahlung and WW fusion in e+e- collisions
International Nuclear Information System (INIS)
Kilian, W.; Kraemer, M.; Zerwas, P.M.
1995-12-01
Higgs-strahlung e + e - →ZH and WW fusion e + e - → anti νν e H are the most important mechanisms for the production of Higgs bosons in e + e - collisions at LEP2 and future e + e - linear colliders. We have calculated the cross sections and energy/angular distributions of the Higgs boson for these production mechanisms. When the Z boson decays into (electron-)neutrinos, the two production amplitude interfere. In the cross-over region between the two mechanisms the interference term is positive and of the same size as the individual cross sections, thus enhancing the production rate. (orig.)
Khoze, Valentin V.; Spannowsky, Michael
2018-01-01
We introduce and discuss two inter-related mechanisms operative in the electroweak sector of the Standard Model at high energies. Higgsplosion, the first mechanism, occurs at some critical energy in the 25 to 103 TeV range, and leads to an exponentially growing decay rate of highly energetic particles into multiple Higgs bosons. We argue that this is a well-controlled non-perturbative phenomenon in the Higgs-sector which involves the final state Higgs multiplicities n in the regime nλ ≫ 1 where λ is the Higgs self-coupling. If this mechanism is realised in nature, the cross-sections for producing ultra-high multiplicities of Higgs bosons are likely to become observable and even dominant in this energy range. At the same time, however, the apparent exponential growth of these cross-sections at even higher energies will be tamed and automatically cut-off by a related Higgspersion mechanism. As a result, and in contrast to previous studies, multi-Higgs production does not violate perturbative unitarity. Building on this approach, we then argue that the effects of Higgsplosion alter quantum corrections from very heavy states to the Higgs boson mass. Above a certain energy, which is much smaller than their masses, these states would rapidly decay into multiple Higgs bosons. The heavy states become unrealised as they decay much faster than they are formed. The loop integrals contributing to the Higgs mass will be cut off not by the masses of the heavy states, but by the characteristic loop momenta where their decay widths become comparable to their masses. Hence, the cut-off scale would be many orders of magnitude lower than the heavy mass scales themselves, thus suppressing their quantum corrections to the Higgs boson mass.
Searching for additional Higgs bosons via Higgs cascades
Gao, Christina; Luty, Markus A.; Mulhearn, Michael; Neill, Nicolás A.; Wang, Zhangqier
2018-04-01
The discovery of a 125 GeV Higgs boson at the Large Hadron Collider strongly motivates direct searches for additional Higgs bosons. In a type I two Higgs doublet model there is a large region of parameter space at tan β ≳5 that is currently unconstrained experimentally. We show that the process g g →H →A Z →Z Z h can probe this region, and can be the discovery mode for an extended Higgs sector at the LHC. We analyze 9 promising decay modes for the Z Z h state, and we find that the most sensitive final states are ℓℓℓℓb b , ℓℓj j b b , ℓℓν ν γ γ and ℓℓℓℓ+ missing energy.
Ni-Mn-Ga single crystals with very low twinning stress
International Nuclear Information System (INIS)
Straka, L; Haenninen, H; Soroka, A; Sozinov, A
2011-01-01
Twinning stress or mechanical hysteresis associated with the twin boundary motion is one of the most essential parameters which determine the actuating performance of magnetic shape memory alloys. Recent effort at AdaptaMat Ltd. to decrease the twinning stress resulted in a consistent production of Ni-Mn-Ga magnetic shape memory single crystals with the twinning stress of about 0.1 MPa, which is much lower than previously reported. In this work, the mechanical and magnetomechanical response of the developed crystals is discussed in detail and the importance of adjustment of the twin microstructure for obtaining an optimal actuating behavior is illustrated.
Higgs potential in the type II seesaw model
International Nuclear Information System (INIS)
Arhrib, A.; Benbrik, R.; Chabab, M.; Rahili, L.; Ramadan, J.; Moultaka, G.; Peyranere, M. C.
2011-01-01
The standard model Higgs sector, extended by one weak gauge triplet of scalar fields with a very small vacuum expectation value, is a very promising setting to account for neutrino masses through the so-called type II seesaw mechanism. In this paper we consider the general renormalizable doublet/triplet Higgs potential of this model. We perform a detailed study of its main dynamical features that depend on five dimensionless couplings and two mass parameters after spontaneous symmetry breaking, and highlight the implications for the Higgs phenomenology. In particular, we determine (i) the complete set of tree-level unitarity constraints on the couplings of the potential and (ii) the exact tree-level boundedness from below constraints on these couplings, valid for all directions. When combined, these constraints delineate precisely the theoretically allowed parameter space domain within our perturbative approximation. Among the seven physical Higgs states of this model, the mass of the lighter (heavier) CP even state h 0 (H 0 ) will always satisfy a theoretical upper (lower) bound that is reached for a critical value μ c of μ (the mass parameter controlling triple couplings among the doublet/triplet Higgses). Saturating the unitarity bounds, we find an upper bound m h 0 or approx. μ c and μ c . In the first regime the Higgs sector is typically very heavy, and only h 0 that becomes SM-like could be accessible to the LHC. In contrast, in the second regime, somewhat overlooked in the literature, most of the Higgs sector is light. In particular, the heaviest state H 0 becomes SM-like, the lighter states being the CP odd Higgs, the (doubly) charged Higgses, and a decoupled h 0 , possibly leading to a distinctive phenomenology at the colliders.
On the theory of twinning plane superconductivity
International Nuclear Information System (INIS)
Mishonov, T.M.
1988-01-01
The thermodynamic potential of the superconducting layer in the twinning plane (TP) vicinity for the type I superconductors is found. The corrections to the surface tension in powers of the Ginsburg-Landau parameter κ are obtained. The corresponding states law for the supercooling field for the type I twinning plane superconductivity (TPS) is obtained, as well as the critical field law for the type II TPS. A review of experimental and theoretical works on TPS and some similar systems is given. The conditions for the Berezinski-Kosterlitz-Thouless transition for the proximity effect are discussed, as well as the possible mechanisms for the conducting phase transition TPS in Nb and the pinning forces close to the twinning plane. The obtained order parameter distribution can be used for description of the superlattices from normal and superconducting metals as well. 6 figs., 44 refs
Higgs properties and decays, searches for high mass Higgs boson and di-Higgs production
Cadamuro, Luca
2018-01-01
The study of the scalar sector of the standard model of particle physics is one of the main goals of the LHC physics programme.A precise characterisation of the Higgs boson, searches for extensions of the scalar sector, and the study of Higgs boson pair production are complementary in this exploration.This document describes the status of Higgs boson physics analyses performed by the ATLAS and CMS Collaborations, focusing on the latest results from pp collisions at sqrt(s) = 13 TeV recorded in 2016, for an integrated luminosity of about 36 fb-1.
Twin-twin transfusion syndrome: etiology, severity and rational management
van Gemert, M. J.; Umur, A.; Tijssen, J. G.; Ross, M. G.
2001-01-01
The twin-twin transfusion syndrome is a serious complication of monochorionic twin pregnancies. Partly as a result of an inadequate understanding of the pathophysiology of the syndrome, there is a lack of consensus in clinical management. We sought to review the available information on the etiology
Energy Technology Data Exchange (ETDEWEB)
Duerr, Michael [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Fileviez Perez, Pavel [Case Western Reserve Univ., Cleveland, OH (United States). CERCA, Physics Dept.; Smirnov, Juri [INFN, Sezione di Firenze (Italy); Florence Univ., Sesto Fiorentino (Italy). Dept. of Physics and Astronomy
2017-04-15
We investigate the possible collider signatures of a new Higgs in simple extensions of the Standard Model where baryon number is a local symmetry spontaneously broken at the low scale. We refer to this new Higgs as ''Baryonic Higgs''. This Higgs has peculiar properties since it can decay into all Standard Model particles, the leptophobic gauge boson, and the vector-like quarks present in these theories to ensure anomaly cancellation. We investigate in detail the constraints from the γγ, Zγ, ZZ, and WW searches at the Large Hadron Collider, needed to find a lower bound on the scale at which baryon number is spontaneously broken. The di-photon channel turns out to be a very sensitive probe in the case of small scalar mixing and can severely constrain the baryonic scale. We also study the properties of the leptophobic gauge boson in order to understand the testability of these theories at the LHC.
Supersymmetric Higgs bosons and beyond
International Nuclear Information System (INIS)
Carena, Marcela; Kong, Kyoungchul; Ponton, Eduardo; Zurita, Jose
2010-01-01
We consider supersymmetric models that include particles beyond the minimal supersymmetric standard model (MSSM) with masses in the TeV range, and that couple significantly to the MSSM Higgs sector. We perform a model-independent analysis of the spectrum and couplings of the MSSM Higgs fields, based on an effective theory of the MSSM degrees of freedom. The tree-level mass of the lightest CP-even state can easily be above the LEP bound of 114 GeV, thus allowing for a relatively light spectrum of superpartners, restricted only by direct searches. The Higgs spectrum and couplings can be significantly modified compared to the MSSM ones, often allowing for interesting new decay modes. We also observe that the gluon fusion production cross section of the SM-like Higgs can be enhanced with respect to both the standard model and the MSSM.
Partially composite Goldstone Higgs boson
DEFF Research Database (Denmark)
Alanne, Tommi; Franzosi, Diogo Buarque; Frandsen, Mads T.
2017-01-01
We consider a model of dynamical electroweak symmetry breaking with a partially composite Goldstone Higgs boson. The model is based on a strongly interacting fermionic sector coupled to a fundamental scalar sector via Yukawa interactions. The SU(4)×SU(4) global symmetry of these two sectors...... is broken to a single SU(4) via Yukawa interactions. Electroweak symmetry breaking is dynamically induced by condensation due to the strong interactions in the new fermionic sector which further breaks the global symmetry SU(4)→Sp(4). The Higgs boson arises as a partially composite state which is an exact...... Goldstone boson in the limit where SM interactions are turned off. Terms breaking the SU(4) global symmetry explicitly generate a mass for the Goldstone Higgs boson. The model realizes in different limits both (partially) composite Higgs and (bosonic) technicolor models, thereby providing a convenient...
Phenomenologies of Higgs messenger models
Energy Technology Data Exchange (ETDEWEB)
Zheng Sibo; Yu Yao; Wu Xinggang [Department of Physics, Chongqing University, Chongqing 401331 (China)
2011-08-11
In this Letter, we investigate the phenomenologies of models where the Higgs sector plays the role of messengers in gauge mediation. The minimal Higgs sector and its extension are considered respectively. We find that there exist viable models when an appropriate parity is imposed. Phenomenological features in these kind of models include three sum rules for scalar masses, light gluino as well as one-loop {mu} and two-loop B{mu} terms.
International Nuclear Information System (INIS)
Aranda, A.; Balazs, C.; Diaz-Cruz, J.L.
2003-01-01
Electroweak precision measurements indicate that the standard model Higgs boson is light and that it could have already been discovered at LEP 2, or might be found at the Tevatron run 2. In the context of a TeV -1 size extra-dimensional model, we argue that the Higgs boson production rates at LEP and the Tevatron are suppressed, while they might be enhanced at the LHC or at CLIC. This is due to the possible mixing between brane and bulk components of the Higgs boson, that is, the non-trivial brane-bulk 'location' of the lightest Higgs. To parametrize this mixing, we consider two Higgs doublets, one confined to the usual space dimensions and the other propagating in the bulk. Calculating the production and decay rates for the lightest Higgs boson, we find that compared to the standard model (SM), the cross section receives a suppression well below but an enhancement close to and above the compactification scale M c . This impacts the discovery of the lightest (SM like) Higgs boson at colliders. To find a Higgs signal in this model at the Tevatron run 2 or at the LC with √s=1.5 TeV, a higher luminosity would be required than in the SM case. Meanwhile, at the LHC or at CLIC with √s∼3-5 TeV one might find highly enhanced production rates. This will enable the latter experiments to distinguish between the extra-dimensional and the SM for M c up to about 6 TeV
International Nuclear Information System (INIS)
Gregoire, Thomas; Wacker, Jay G.
2002-01-01
New theories of electroweak symmetry breaking have recently been constructed that stabilize the weak scale and do not rely upon supersymmetry. In these theories the Higgs boson is a weakly coupled pseudo-Goldstone boson. In this note we study the class of theories that can be described by theory spaces and show that the fundamental group of theory space describes all the relevant classical physics in the low energy theory. The relationship between the low energy physics and the topological properties of theory space allow a systematic method for constructing theory spaces that give any desired low energy particle content and potential. This provides us with tools for analyzing and constructing new theories of electroweak symmetry breaking. (author)
Searches for BSM Higgs Bosons with ATLAS
Navarro, Gabriela; The ATLAS collaboration
2015-01-01
The discovery of a Higgs-like boson with a mass of about 125GeV has prompted the question of whether or not this particle is part of a much larger and more complex Higgs sector than that envisioned in the Standard Model. In this talk, the current results from the ATLAS Experiment regarding Beyond-the-Standard Model (BSM) Higgs hypothesis tests are outlined. Searches for additional Higgs bosons are presented and interpreted in well-motivated BSM Higgs frameworks, such as two-Higgs-doublet Models and the Minimal Supersymmetric Standard Model.
Vacuum stability in neutrinophilic Higgs doublet model
International Nuclear Information System (INIS)
Haba, Naoyuki; Horita, Tomohiro
2011-01-01
A neutrinophilic Higgs model has tiny vacuum expectation value (VEV), which can naturally explain tiny masses of neutrinos. There is a large energy scale hierarchy between a VEV of the neutrinophilic Higgs doublet and that of usual standard model-like Higgs doublet. In this Letter we at first analyze vacuum structures of Higgs potential in both supersymmetry (SUSY) and non-SUSY neutrinophilic Higgs models, and next investigate a stability of this VEV hierarchy against radiative corrections. We will show that the VEV hierarchy is stable against radiative corrections in both Dirac neutrino and Majorana neutrino scenarios in both SUSY and non-SUSY neutrinophilic Higgs doublet models.
QCD corrections to Higgs-boson production at proton-proton colliders
International Nuclear Information System (INIS)
Graudenz, D.; Zerwas, P.M.
1992-11-01
Gluon fusion is the main production mechanism for Higgs bosons with masses up to several hundred GeV in pp collisions at LHC and SSC. We present the QCD corrections to the fusion cross section for arbitrary Higgs and top mass values: gg → H(g), gq → Hq and qanti q → Hg. The QCD corrections are positive and they increase the cross section σ(pp → H) by about a factor 1.5 to 1.7. The analysis applies to the production of Higgs particles in the Standard Model and also to the production of the CP-even Higgs particles in extensions of the Higgs sector as required for example by supersymmetric theories. (orig.)
Higgs boson production via Z, W bosons and toponium in the E6 superstring model
International Nuclear Information System (INIS)
Barger, V.; Whisnant, K.
1988-01-01
The authors examine the production of light Higgs bosons associated with electroweak symmetry-breaking in an E 6 superstring model in Z ω HZ * decays, in e + e - annihilation and in toponium decays. They find that the couplings of the lightest scalar Higgs boson H 1 0 in these models are very similar to those of the standard Higgs boson unless the pseudoscalar P 0 in the model has mass ≤ M z . Possible new modes for Higgs boson production not found in the standard model are presented. The authors give simple analytic expressions for the Higgs boson masses and mixing angles in the limit that the extra Z' gauge boson is heavy which clearly shows the production mechanisms that are favored for a given set of model parameters
The Hierarchy Problem and the Self-Localized Higgs
Burgess, C P; van Nierop, Leo
2008-01-01
We examine brane-world scenarios in which all the observed Standard Model particles reside on a brane but the Higgs is an elementary extra-dimensional scalar in the bulk. We show that, for codimension 2 branes, often-neglected interactions between the bulk Higgs and the branes cause two novel effects. First, they cause to depend only logarithmically on the UV-sensitive coefficient, m_B^2, of the mass term, m_B^2 H^*H, of the bulk potential, thus providing a new mechanism for tackling the hierarchy problem. Second, the Higgs brane couplings cause the lowest mass KK mode to localize near the brane without any need for geometrical effects like warping. We explore some preliminary implications such models have for the Higgs signature at the LHC, both in the case where the extra dimensions arise at the TeV scale, and in ADD models having Large Extra Dimensions. Novel Higgs features include couplings to fermions which are generically stronger than the Standard Model values, m_f/v, despite the fermions acquiring th...
Gauge turbulence, topological defect dynamics, and condensation in Higgs models
International Nuclear Information System (INIS)
Gasenzer, Thomas; McLerran, Larry; Pawlowski, Jan M.; Sexty, Dénes
2014-01-01
The real-time dynamics of topological defects and turbulent configurations of gauge fields for electric and magnetic confinement are studied numerically within a 2+1D Abelian Higgs model. It is shown that confinement is appearing in such systems equilibrating after a strong initial quench such as the overpopulation of the infrared modes. While the final equilibrium state does not support confinement, metastable vortex defect configurations appearing in the gauge field are found to be closely related to the appearance of physically observable confined electric and magnetic charges. These phenomena are seen to be intimately related to the approach of a non-thermal fixed point of the far-from-equilibrium dynamical evolution, signaled by universal scaling in the gauge-invariant correlation function of the Higgs field. Even when the parameters of the Higgs action do not support condensate formation in the vacuum, during this approach, transient Higgs condensation is observed. We discuss implications of these results for the far-from-equilibrium dynamics of Yang–Mills fields and potential mechanisms of how confinement and condensation in non-Abelian gauge fields can be understood in terms of the dynamics of Higgs models. These suggest that there is an interesting new class of dynamics of strong coherent turbulent gauge fields with condensates
Gauge turbulence, topological defect dynamics, and condensation in Higgs models
Energy Technology Data Exchange (ETDEWEB)
Gasenzer, Thomas [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); ExtreMe Matter Institute EMMI, GSI, Planckstraße 1, D-64291 Darmstadt (Germany); McLerran, Larry [Physics Department, Bldg. 510A, Brookhaven National Laboratory, Upton, NY 11973 (United States); RIKEN BNL Research Center, Bldg. 510A, Brookhaven National Laboratory, Upton, NY 11973 (United States); Physics Department, China Central Normal University, Wuhan (China); Pawlowski, Jan M.; Sexty, Dénes [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); ExtreMe Matter Institute EMMI, GSI, Planckstraße 1, D-64291 Darmstadt (Germany)
2014-10-15
The real-time dynamics of topological defects and turbulent configurations of gauge fields for electric and magnetic confinement are studied numerically within a 2+1D Abelian Higgs model. It is shown that confinement is appearing in such systems equilibrating after a strong initial quench such as the overpopulation of the infrared modes. While the final equilibrium state does not support confinement, metastable vortex defect configurations appearing in the gauge field are found to be closely related to the appearance of physically observable confined electric and magnetic charges. These phenomena are seen to be intimately related to the approach of a non-thermal fixed point of the far-from-equilibrium dynamical evolution, signaled by universal scaling in the gauge-invariant correlation function of the Higgs field. Even when the parameters of the Higgs action do not support condensate formation in the vacuum, during this approach, transient Higgs condensation is observed. We discuss implications of these results for the far-from-equilibrium dynamics of Yang–Mills fields and potential mechanisms of how confinement and condensation in non-Abelian gauge fields can be understood in terms of the dynamics of Higgs models. These suggest that there is an interesting new class of dynamics of strong coherent turbulent gauge fields with condensates.
Higgs inflation, seesaw physics and fermion dark matter
Directory of Open Access Journals (Sweden)
Nobuchika Okada
2015-07-01
Full Text Available We present an inflationary model in which the Standard Model Higgs doublet field with non-minimal coupling to gravity drives inflation, and the effective Higgs potential is stabilized by new physics which includes a dark matter particle and right-handed neutrinos for the seesaw mechanism. All of the new particles are fermions, so that the Higgs doublet is the unique inflaton candidate. With central values for the masses of the top quark and the Higgs boson, the renormalization group improved Higgs potential is employed to yield the scalar spectral index ns≃0.968, the tensor-to-scalar ratio r≃0.003, and the running of the spectral index α=dns/dlnk≃−5.2×10−4 for the number of e-folds N0=60 (ns≃0.962, r≃0.004, and α≃−7.5×10−4 for N0=50. The fairly low value of r≃0.003 predicted in this class of models means that the ongoing space and land based experiments are not expected to observe gravity waves generated during inflation.
Relativistic twins or sextuplets?
International Nuclear Information System (INIS)
Sheldon, Eric
2003-01-01
A recent study of the relativistic twin 'paradox' by Soni in this journal affirmed that 'A simple solution of the twin paradox also shows anomalous behaviour of rigidly connected distant clocks' but entailed a pedagogic hurdle which the present treatment aims to surmount. Two scenarios are presented: the first 'flight-plan' is akin to that depicted by Soni, with constant-velocity segments, while the second portrays an alternative mission undertaken with sustained acceleration and deceleration, illustrated quantitatively for a two-way spacecraft flight from Earth to Polaris (465.9 light years distant) and back
Relativistic twins or sextuplets?
Sheldon, E S
2003-01-01
A recent study of the relativistic twin 'paradox' by Soni in this journal affirmed that 'A simple solution of the twin paradox also shows anomalous behaviour of rigidly connected distant clocks' but entailed a pedagogic hurdle which the present treatment aims to surmount. Two scenarios are presented: the first 'flight-plan' is akin to that depicted by Soni, with constant-velocity segments, while the second portrays an alternative mission undertaken with sustained acceleration and deceleration, illustrated quantitatively for a two-way spacecraft flight from Earth to Polaris (465.9 light years distant) and back.
Energy Technology Data Exchange (ETDEWEB)
McHugh, Kieran [Great Ormond Street Hospital for Children, Department of Radiology, London (United Kingdom); Kiely, Edward M.; Spitz, Lewis [Great Ormond Street Hospital for Children, Department of Surgery, London (United Kingdom)
2006-09-15
The incidence of conjoined twins is estimated to be around 1 in 250,000 live births. There is a distinct female predominance. In this paper the imaging of conjoined twins both antenatally and postnatally is reviewed, in particular taking into consideration recent advances with multidetector CT. Accurate counselling of parents regarding the likely outcome of the pregnancy and the likelihood of successful separation is dependent on good prenatal imaging with ultrasound and MRI. Planning of postnatal surgical separation is aided by accurate preoperative imaging which, depending on the conjoined area, will encompass many imaging modalities, but often relies heavily on CT scanning. (orig.)
International Nuclear Information System (INIS)
McHugh, Kieran; Kiely, Edward M.; Spitz, Lewis
2006-01-01
The incidence of conjoined twins is estimated to be around 1 in 250,000 live births. There is a distinct female predominance. In this paper the imaging of conjoined twins both antenatally and postnatally is reviewed, in particular taking into consideration recent advances with multidetector CT. Accurate counselling of parents regarding the likely outcome of the pregnancy and the likelihood of successful separation is dependent on good prenatal imaging with ultrasound and MRI. Planning of postnatal surgical separation is aided by accurate preoperative imaging which, depending on the conjoined area, will encompass many imaging modalities, but often relies heavily on CT scanning. (orig.)
What is the probability of the Higgs boson discovery?
Energy Technology Data Exchange (ETDEWEB)
Unzicker, Alexander [Pestalozzi-Gymnasium Muenchen (Germany)
2010-07-01
The standard model of particle physics requires the existence of the Higgs boson which provides a mechanism for the appearance of masses. Its detection is one of the most important goals of high energy physics, and enormous efforts have been undertaken at Tevatron and specially at the Large Hadron Collider. But how sure can we be that the Higgs exits at all? At such controversial questions, the German philosopher Immanuel Kant recommended a bet, and nowadays this can be realized using online prediction markets like Intrade.com. Such platforms have been proven useful for giving estimates of unknown probabilities, and the application for evaluating scientific research is discussed in general.
Evading direct dark matter detection in Higgs portal models
Energy Technology Data Exchange (ETDEWEB)
Arcadi, Giorgio [Max Planck Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Gross, Christian, E-mail: christian.gross@helsinki.fi [Department of Physics and Helsinki Institute of Physics, Gustaf Hällströmin katu 2, FI-00014 Helsinki (Finland); Lebedev, Oleg [Department of Physics and Helsinki Institute of Physics, Gustaf Hällströmin katu 2, FI-00014 Helsinki (Finland); Pokorski, Stefan [Institute of Theoretical Physics, University of Warsaw, Pasteura 5, PL-02-093 Warsaw (Poland); Toma, Takashi [Physik-Department T30d, Technische Universität München, James-Franck-Straße, D-85748 Garching (Germany)
2017-06-10
Many models of Higgs portal Dark Matter (DM) find themselves under pressure from increasingly tight direct detection constraints. In the framework of gauge field DM, we study how such bounds can be relaxed while retaining the thermal WIMP paradigm. When the hidden sector gauge symmetry is broken via the Higgs mechanism, the hidden sector generally contains unstable states which are lighter than dark matter. These states provide DM with an efficient annihilation channel. As a result, the DM relic abundance and the direct detection limits are controlled by different parameters, and the two can easily be reconciled. This simple setup realizes the idea of “secluded” dark matter naturally.
Off-the-Wall Higgs in the universal Randall-Sundrum model
International Nuclear Information System (INIS)
Davoudiasl, Hooman; Lillie, Ben; Rizzo, Thomas G.
2006-01-01
We outline a consistent Randall-Sundrum (RS) framework in which a fundamental 5-dimensional Higgs doublet induces electroweak symmetry breaking (EWSB). In this framework of a warped Universal Extra Dimension, the lightest Kaluza-Klein (KK) mode of the bulk Higgs is tachyonic leading to a vacuum expectation value (vev) at the TeV scale. The consistency of this picture imposes a set of constraints on the parameters in the Higgs sector. A novel feature of our scenario is the emergence of an adjustable bulk profile for the Higgs vev. We also find a tower of non-tachyonic Higgs KK modes at the weak scale. We consider an interesting implementation of this 'Off-the-Wall Higgs' mechanism where the 5-dimensional curvature-scalar coupling alone generates the tachyonic mode responsible for EWSB. In this case, additional relations among the parameters of the Higgs and gravitational sectors are established. We discuss the experimental signatures of the bulk Higgs in general, and those of the 'Gravity-Induced' EWSB in particular
The Higgs mass derived from the U(3) Lie group
DEFF Research Database (Denmark)
Trinhammer, Ole; Bohr, Henrik; Jensen, Mogens O Stibius
2015-01-01
The Higgs mass value is derived from a Hamiltonian on the Lie group U(3) where we relate strong and electroweak energy scales. The baryon states of nucleon and delta resonances originate in specific Bloch wave degrees of freedom coupled to a Higgs mechanism which also gives rise to the usual gauge...... boson masses. The derived Higgs mass is around 125 GeV. From the same Hamiltonian, we derive the relative neutron to proton mass ratio and the N and Delta mass spectra. All compare rather well with the experimental values. We predict scarce neutral flavor baryon singlets that should be visible...... in scattering cross-sections for negative pions on protons, in photoproduction on neutrons, in neutron diffraction dissociation experiments and in invariant mass spectra of protons and negative pions in B-decays. The fundamental predictions are based on just one length scale and the fine structure constant...
Cosmological Constraints on Decoupled Dark Photons and Dark Higgs
Energy Technology Data Exchange (ETDEWEB)
Berger, Joshua [Univ. of Wisconsin, Madison, WI (United States); Jedamzik, Karsten [Univ. Montpellier II (France). Lab. Univers. et Particules de Monpellier; Walker, Devin G.E. [Univ. of Washington, Seattle, WA (United States). Dept. of Physics
2016-05-23
Any neutral boson such as a dark photon or dark Higgs that is part of a non-standard sector of particles can mix with its standard model counterpart. When very weakly mixed with the Standard Model, these particles are produced in the early Universe via the freeze-in mechanism and subsequently decay back to standard model particles. In this work, we place constraints on such mediator decays by considering bounds from Big Bang nucleosynthesis and the cosmic microwave background radiation. We find both nucleosynthesis and CMB can constrain dark photons with a kinetic mixing parameter between log ϵ ~ -10 to -17 for masses between 1 MeV and 100 GeV. Similarly, the dark Higgs mixing angle ϵ with the Standard Model Higgs is constrained between log ϵ ~ -6 to -15. Dramatic improvement on the bounds from CMB spectral distortions can be achieved with proposed experiments such as PIXIE.
Cosmological constraints on decoupled dark photons and dark Higgs
Energy Technology Data Exchange (ETDEWEB)
Berger, Joshua [Physics Department, University of Wisconsin-Madison,1150 University Ave, Madison, WI 53706 (United States); Jedamzik, Karsten [Laboratoire Univers et Particules de Montpellier, UMR5299-CNRS,Université Montpellier II,Place Eugène Bataillon, CC 72, 34095 Montpellier Cédex 05 (France); Walker, Devin G.E. [Department of Physics and Astronomy, Dartmouth College,6127 Wilder Laboratory, Hanover, NH 03755 (United States); Department of Physics, University of Washington,Box 351560, Seattle, WA 98195 (United States)
2016-11-16
Any neutral boson such as a dark photon or dark Higgs that is part of a non-standard sector of particles can mix with its standard model counterpart. When very weakly mixed with the Standard Model, these particles are produced in the early Universe via the freeze-in mechanism and subsequently decay back to standard model particles. In this work, we place constraints on such mediator decays by considering bounds from Big Bang nucleosynthesis and the cosmic microwave background radiation. We find both nucleosynthesis and CMB can constrain dark photons with a kinetic mixing parameter between log ϵ∼−10 to −17 for masses between 1 MeV and 100 GeV. Similarly, the dark Higgs mixing angle ϵ with the Standard Model Higgs is constrained between log ϵ∼−6 to −15. Dramatic improvement on the bounds from CMB spectral distortions can be achieved with proposed experiments such as PIXIE.
Vector boson fusion NNLO in QCD. SM Higgs and beyond
Energy Technology Data Exchange (ETDEWEB)
Bolzoni, Paolo [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Maltoni, Fabio; Zaro, Marco [Catholique Univ. Louvain-la-Neuve (BE). Center for Cosmology, Particle Phyics and Phenomenology (CP3); Moch, Sven-Olaf [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2011-09-15
Weak vector boson fusion provides a unique channel to directly probe the mechanism of electroweak symmetry breaking at hadron colliders. We present a method that allows to calculate total cross sections to next-to-next-to-leading order (NNLO) in QCD for an arbitrary V{sup *}V{sup *}{yields}X process, the so-called structure function approach. By discussing the case of Higgs production in detail, we estimate several classes of previously neglected contributions and we argue that such method is accurate at a precision level well above the typical residual scale and PDF uncertainties at NNLO. Predictions for cross sections at the Tevatron and the LHC are presented for a variety of cases: the Standard Model Higgs (including anomalous couplings), neutral and charged scalars in extended Higgs sectors and (fermiophobic) vector resonance production. Further results can be easily obtained through the public use of the VBF rate at NNLO code. (orig.)
Identifying new physics contributions in the Higgs sector at linear e+ ...
Indian Academy of Sciences (India)
. Introduction. Higgs boson discovery will prove to be a crucial ingredient towards understanding the mechanism of electroweak symmetry breaking. Once discovered, a major goal would be to determine its other intrinsic properties, couplings ...
The Placenta in Twin-to-Twin Transfusion Syndrome and Twin Anemia Polycythemia Sequence.
Couck, Isabel; Lewi, Liesbeth
2016-06-01
Twin-to-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS) are complications unique to monochorionic twin pregnancies and their shared circulation. Both are the result of the transfusion imbalance in the intertwin circulation. TTTS is characterized by an amniotic fluid discordance, whereas in TAPS, there is a severe discordance in hemoglobin levels. The article gives an overview of the typical features of TTTS and TAPS placentas.
Distinguishing a SM-like MSSM Higgs boson from SM Higgs boson ...
Indian Academy of Sciences (India)
We explore the possibility of distinguishing the SM-like MSSM Higgs boson from the SM Higgs boson via Higgs boson pair production at future muon collider. We study the behavior of the production cross-section in SM and MSSM with Higgs boson mass for various MSSM parameters tan and A. We observe that at fixed ...
DEFF Research Database (Denmark)
Gramkow, Ann-Maria; Aarup, Michael; Andersen, L. L. T.
2014-01-01
A 32-year-old woman with known stage-4 chronic kidney disease due to lupus nephritis presented with twin pregnancy after in vitro fertilization at a gestational age of 24 weeks + 3 days because of imminent preterm labour. Repeated ultrasound evaluations confirmed intrauterine growth restriction...
Anaesthesia for conjoined twins
African Journals Online (AJOL)
draw~ver patient system consisting of a paediatric. "Ambu" bag and "Paedivalven drawing oxygen-en- riched air through a halothane vaporiser. Oxygen was supplied from an electric oxygen concentrator which can give 2 litres of 95% oxygen per minute. This apparatus has been described I. Mter 3 minutes the Sa02 of Twin ...
Directory of Open Access Journals (Sweden)
J Gordon Millichap
2008-12-01
Full Text Available In an attempt to clarify the genetic and environmental causes of sleep terrors in childhood, reasearchers in Canada followed 390 pairs of monozygotic and dizygotic twins by assessing the frequency of sleep terrors at 18 and 30 months of age using a questionnaire administered to the biological mothers.
J Gordon Millichap
2008-01-01
In an attempt to clarify the genetic and environmental causes of sleep terrors in childhood, reasearchers in Canada followed 390 pairs of monozygotic and dizygotic twins by assessing the frequency of sleep terrors at 18 and 30 months of age using a questionnaire administered to the biological mothers.
The USC Adult Twin Cohorts: International Twin Study and California Twin Program.
Cozen, Wendy; Hwang, Amie E; Cockburn, Myles G; Hamilton, Ann S; Zadnick, John; Mack, Thomas M
2013-02-01
The study of twin subjects permits the documentation of crude heritability and may promote the identification of specific causal alleles. We believe that at the current time, the chief research advantage of twins as subjects, especially monozygotic twins, is that the commonality of their genetic and cultural identity simplifies the interpretation of biological associations. In order to study genetic and environmental determinants of cancer and chronic diseases, we developed two twin registries, maintained at the University of Southern California: The International Twin Study (ITS) and the California Twin Program (CTP). The ITS is a volunteer registry of twins with cancer and chronic disease consisting of 17,245 twin pairs affected by cancer and chronic disease, respectively, ascertained by advertising in periodicals from 1980-1991. The CTP is a population-based registry of California-born twin pairs ascertained by linking the California birth records to the State Department of Motor Vehicles. Over 51,000 individual California twins representing 36,965 pairs completed and returned 16-page questionnaires. Cancer diagnoses in the California twins are updated by regular linkage to the California Cancer Registry. Over 5,000 cancer patients are represented in the CTP. Twins from both registries have participated extensively in studies of breast cancer, melanoma, lymphoma, multiple sclerosis, systemic lupus erythematosus, diabetes mellitus type 1, mammographic density, smoking, and other traits and conditions.
Twin-twin transfusion syndrome - diagnosis and prognosis
Directory of Open Access Journals (Sweden)
Hajrić-Egić Amira
2003-01-01
Full Text Available Twin-twin transfusion syndrome is a serious complication of monozygotic, monochorionic, diamniotic twins resulting from transplacental vascular communications. In this syndrome blood is thought to be shunted from one twin - donor,who develops anaemia,growth retardation and oligoamnios, to the other twin - recipient,who becomes plethoric,macrosomic and develops polyhydroamnios. The incidence of twin-twin transfusion syndrome ranges from 5-15% of all twin pregnancies. If this condition develops in the second trimester, it is usually associated with spontaneous abortion and death of one or both fetuses before viability. Developing the syndrome in the third trimester has better perinatal outcome. Mortality rates ranging from 56%-100%, depending on gestational age and severity of the syndrome. The ultrasound criterias for diagnosis, in this study,were the presence of twins of the same sex with discordant growth, with oligohydroamnios in one twin sac and polyhydroamnios in the other one, one placenta and thin membrane between twins. The present study shows clinical course of 14 cases and value of Doppler ultrasound to analyze the usefulness of umbilical artery blood flow velocimetry for predicting the risk of twin-twin transfusion syndrome. 14 twin pregnancies with twin-twin transfusion syndrome were diagnosed during the last four years period and prospectivelly followed. 9 cases were diagnosed before the completion od 28 weeks of gestation.The mean gestational age was 21,6_+4,2 weeks at diagnosis and 23,2+_3,6 weeks at delivery. 5 cases were diagnosed after 28 weeks of gestation. The mean gestational age in this group was 29,6+_2,1 weeks at diagnosis and 33+_3,3 weeks at delivery. The survival rate in this study was 29%(8/28.9 cases ended in spontaneous abortion between 18th and 27th weeks of pregnancy (table 1 and 5 in premature labor (table 2.There were 7 intrauterine death (5 at admission and 2 few days after admission and 13 neonatal deaths
Invisible Higgs decays from Higgs-graviscalar mixing
International Nuclear Information System (INIS)
Dominici, Daniele; Gunion, John F.
2009-01-01
We recompute the invisible Higgs decay width arising from Higgs-graviscalar mixing in the Arkani-Hamed, Dimopoulos, Dvali model, comparing the original derivation in the nondiagonal mass basis to that in a diagonal mass basis. The results obtained are identical (and differ by a factor of 2 from the original calculation) but the diagonal-basis derivation is pedagogically useful for clarifying the physics of the invisible width from mixing. We emphasize that both derivations make it clear that a direct scan in energy for a process such as WW→WW mediated by Higgs plus graviscalar intermediate resonances would follow a single Breit-Wigner form with total width given by Γ tot =Γ h SM +Γ invisible . We also compute the additional contributions to the invisible width due to direct Higgs to graviscalar-pair decays. We find that the invisible width due to the latter is relatively small, unless the Higgs mass is comparable to or larger than the effective extra-dimensional Planck mass.
The search for a heavy Higgs boson
International Nuclear Information System (INIS)
Dawson, S.
1989-02-01
Theoretical limits on the mass of the Higgs boson from vacuum stability and perturbative unitarity are examined. Search techniques for heavy Higgs bosons, M/sub H/ > 200 GeV, are also reviewed. 8 refs., 5 figs
THE HIGGS WORKING GROUP: SUMMARY REPORT.
Energy Technology Data Exchange (ETDEWEB)
DAWSON, S.; ET AL.
2005-08-01
This working group has investigated Higgs boson searches at the Tevatron and the LHC. Once Higgs bosons are found their properties have to be determined. The prospects of Higgs coupling measurements at the LHC and a high-energy linear e{sup +}e{sup -} collider are discussed in detail within the Standard Model and its minimal supersymmetric extension (MSSM). Recent improvements in the theoretical knowledge of the signal and background processes are presented and taken into account. The residual uncertainties are analyzed in detail. Theoretical progress is discussed in particular for the gluon-fusion processes gg {yields} H(+j), Higgs-bremsstrahlung off bottom quarks and the weak vector-boson-fusion (VBF) processes. Following the list of open questions of the last Les Houches workshop in 2001 several background processes have been calculated at next-to-leading order, resulting in a significant reduction of the theoretical uncertainties. Further improvements have been achieved for the Higgs sectors of the MSSM and NMSSM. This report summarizes our work performed before and after the workshop in Les Houches. Part A describes the theoretical developments for signal and background processes. Part B presents recent progress in Higgs boson searches at the Tevatron collider. Part C addresses the determination of Higgs boson couplings, part D the measurement of tan {beta} and part E Higgs boson searches in the VBF processes at the LHC. Part F summarizes Higgs searches in supersymmetric Higgs decays, part G photonic Higgs decays in Higgs-strahlung processes at the LHC, while part H concentrates on MSSM Higgs bosons in the intense-coupling regime at the LHC. Part I presents progress in charged Higgs studies and part J the Higgs discovery potential in the NMSSM at the LHC. The last part K describes Higgs coupling measurements at a 1 TeV linear e{sup +}e{sup -} collider.
THE HIGGS WORKING GROUP: SUMMARY REPORT
International Nuclear Information System (INIS)
DAWSON, S.
2005-01-01
This working group has investigated Higgs boson searches at the Tevatron and the LHC. Once Higgs bosons are found their properties have to be determined. The prospects of Higgs coupling measurements at the LHC and a high-energy linear e + e - collider are discussed in detail within the Standard Model and its minimal supersymmetric extension (MSSM). Recent improvements in the theoretical knowledge of the signal and background processes are presented and taken into account. The residual uncertainties are analyzed in detail. Theoretical progress is discussed in particular for the gluon-fusion processes gg → H(+j), Higgs-bremsstrahlung off bottom quarks and the weak vector-boson-fusion (VBF) processes. Following the list of open questions of the last Les Houches workshop in 2001 several background processes have been calculated at next-to-leading order, resulting in a significant reduction of the theoretical uncertainties. Further improvements have been achieved for the Higgs sectors of the MSSM and NMSSM. This report summarizes our work performed before and after the workshop in Les Houches. Part A describes the theoretical developments for signal and background processes. Part B presents recent progress in Higgs boson searches at the Tevatron collider. Part C addresses the determination of Higgs boson couplings, part D the measurement of tan β and part E Higgs boson searches in the VBF processes at the LHC. Part F summarizes Higgs searches in supersymmetric Higgs decays, part G photonic Higgs decays in Higgs-strahlung processes at the LHC, while part H concentrates on MSSM Higgs bosons in the intense-coupling regime at the LHC. Part I presents progress in charged Higgs studies and part J the Higgs discovery potential in the NMSSM at the LHC. The last part K describes Higgs coupling measurements at a 1 TeV linear e + e - collider
International Nuclear Information System (INIS)
Franzini, P.J.
1986-04-01
Bounds from B 0 - anti B 0 mixing on charged-Higgs-boson masses and couplings in two-Higgs-doublet models are presented. These bounds are comparable to those obtained, with additional assumptions, from the neutral-K-system. The effects of the neutral Higgs bosons of these models on the spectrum and wave function of toponium are discussed. These effects could, in the future, lead to limits on, or the discovery of, these Higgs bosons. 8 refs., 3 figs
HiggsSignals. Confronting arbitrary Higgs sectors with measurements at the Tevatron and the LHC
Energy Technology Data Exchange (ETDEWEB)
Bechtle, Philip [Bonn Univ. (Germany). Physikalisches Inst.; Heinemeyer, Sven [Instituto de Fisica de Cantabria (CSIC-UC), Santander (Spain); Staal, Oscar [Stockholm Univ. (Sweden). The Oskar Klein Centre; Stefaniak, Tim [Bonn Univ. (Germany). Physikalisches Inst.; Bonn Univ. (Germany). Bethe Center for Theoretical Physics; Weiglein, Georg [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2013-05-15
HiggsSignals is a Fortran90 computer code that allows to test the compatibility of Higgs sector predictions against Higgs rates and masses measured at the LHC or the Tevatron. Arbitrary models with any number of Higgs bosons can be investigated using a model-independent input scheme based on HiggsBounds. The test is based on the calculation of a {chi}{sup 2} measure from the predictions and the measured Higgs rates and masses, with the ability of fully taking into account systematics and correlations for the signal rate predictions, luminosity and Higgs mass predictions. It features two complementary methods for the test. First, the peak-centered method, in which each observable is defined by a Higgs signal rate measured at a specific hypothetical Higgs mass, corresponding to a tentative Higgs signal. Second, the mass-centered method, where the test is evaluated by comparing the signal rate measurement to the theory prediction at the Higgs mass predicted by the model. The program allows for the simultaneous use of both methods, which is useful in testing models with multiple Higgs bosons. The code automatically combines the signal rates of multiple Higgs bosons if their signals cannot be resolved by the experimental analysis. We compare results obtained with HiggsSignals to official ATLAS and CMS results for various examples of Higgs property determinations and find very good agreement. A few examples of HiggsSignals applications are provided, going beyond the scenarios investigated by the LHC collaborations. For models with more than one Higgs boson we recommend to use HiggsSignals and HiggsBounds in parallel to exploit the full constraining power of Higgs search exclusion limits and the measurements of the signal seen at m{sub H} {approx} 125.5 GeV.
Cadée, Franka; Perdok, Hilde; Sam, Betty; de Geus, Myrte; Kweekel, Liselotte
2013-10-01
midwives need professional support from a national midwifery organisation to be able to provide the services that are by regulatory mechanisms and accreditation expected of them. Not all midwives in the world are united in a professional organisation. The aim of this project was to strengthen the midwifery organisations of Sierra Leone and the Netherlands. During the process of the project it was realised that the development of a platform of exchange at organisational level would be enhanced by introducing personal exchange between individual midwives. In response to this new insight the original project plan was adjusted by incorporating the twin2twin method. twin2twin is a feminist methodology of mutual exchange between twenty pairs of midwives from different organisations (in this case Sierra Leone and the Netherlands). The method can be distinguished by 10 specific steps. It was developed, used and (re)evaluated through focus group discussions, storytelling and written evaluations. twinning of organisations was strengthened by adding a human component to the process. With the use of the 'twin2twin' method, midwives were encouraged to invested in a professional and personal bond with their 'twin sister'. This bond was independent and went beyond the relatively short four year project period. Through personal engagement and mutual exchange of knowledge and skills, midwives empowered each other to build and strengthen their midwifery organisations both in Sierra Leone and the Netherlands. (Empowerment refers to the expansion in people's ability to make strategic life choices in a context where this ability was previously denied to them (Narayan, 2005); organisational empowerment includes processes and structures that enhance members' skills and provides them with the mutual support necessary to effect community level change (Zimmerman, 1995).). despite challenges we are convinced that twin2twin can be of additional benefit for the success of other projects
Higgs friends and counterfeits at hadron colliders
International Nuclear Information System (INIS)
Fox, Patrick J.; Tucker-Smith, David; Weiner, Neal
2011-01-01
We consider the possibility of 'Higgs counterfeits' - scalars that can be produced with cross sections comparable to the SM Higgs, and which decay with identical relative observable branching ratios, but which are nonetheless not responsible for electroweak symmetry breaking. We also consider a related scenario involving 'Higgs friends,' fields similarly produced through gg fusion processes, which would be discovered through diboson channels WW,ZZ,γγ, or even γZ, potentially with larger cross sections times branching ratios than for the Higgs. The discovery of either a Higgs friend or a Higgs counterfeit, rather than directly pointing towards the origin of the weak scale, would indicate the presence of new colored fields necessary for the sizable production cross section (and possibly new colorless but electroweakly charged states as well, in the case of the diboson decays of a Higgs friend). These particles could easily be confused for an ordinary Higgs, perhaps with an additional generation to explain the different cross section, and we emphasize the importance of vector boson fusion as a channel to distinguish a Higgs counterfeit from a true Higgs. Such fields would naturally be expected in scenarios with 'effective Z's,' where heavy states charged under the SM produce effective charges for SM fields under a new gauge force. We discuss the prospects for discovery of Higgs counterfeits, Higgs friends, and associated charged fields at the LHC.
Goldstone bosons and a dynamical Higgs field
Mooij, S.; Postma, M.
2011-01-01
Higgs inflation uses the gauge variant Higgs field as the inflaton. During inflation the Higgs field is displaced from its minimum, which results in associated Goldstone bosons that are apparently massive. Working in a minimally coupled U(1) toy model, we use the closed-time-path formalism to show
Higgs physics at the Large Hadron Collider
Indian Academy of Sciences (India)
Higgs boson; Large Hadron Collider; electroweak symmetry; spin and CP of the Higgs boson ... I shall then give a short description of the pre-LHC constraints on the Higgs mass and the theoretical predictions for the LHC along with a discussion of the current experimental results, ending with prospects in the near future at ...
Introduction to the physics of Higgs bosons
International Nuclear Information System (INIS)
Dawson, S.
1994-11-01
A basic introduction to the physics of the Standard Model Higgs boson is given. We discuss Higgs boson production in e + e - and hadronic collisions and survey search techniques at future accelerators. The Higgs bosons of the minimal SUSY model are briefly considered. Indirect limits from triviality arguments, vacuum stability and precision measurements at LEP are also presented
Higgs into the heart of imagination
Van den Bergh, Hannie
2010-01-01
Higgs is the documentary about the quest for the Higgs particle, also known as "The God Particle". It is considered the missing link in particle physics. Higgs is a film about the curiosity, the passion, and the imaginative power of silence.
Strength of the trilinear Higgs boson coupling in technicolor models
International Nuclear Information System (INIS)
Doff, A.; Natale, A.A.
2006-01-01
In the standard model of elementary particles the fermion and gauge boson masses are generated due to the interaction of these particles with elementary Higgs scalar bosons. Despite its success there are some points in the model as, for instance, the enormous range of masses between the lightest and heaviest fermions and other peculiarities that could be better explained at a deeper level. The nature of the Higgs boson is one of the most important problems in particle physics, and there are many questions that may be answered in the near future by LHC experiments, such as: Is the Higgs boson, if it exists at all, elementary or composite? What are the symmetries behind the Higgs mechanism? There are many variants for the Higgs mechanism. Our interest in this work will be focused in the models of electroweak symmetry breaking via strongly interacting theories of technicolor (TC) type. In these theories the Higgs boson is a composite of the so called technifermions, and at some extent any model where the Higgs boson is not an elementary field follows more or less the same ideas of the technicolor models. In extensions of the standard model the scalar self-couplings can be enhanced, like in the supersymmetric version. If the same happens in models of dynamical symmetry breaking, as far as we know, has not been investigated up to now, and this study is the motivation of our work. Although technicolor is a non-Abelian gauge theory it is not necessarily similar to QCD, and most of the work in this area try to find the TC dynamics dealing with the particle content of the theory in order to obtain a technifermion self-energy that does not lead to phenomenological problems as in the scheme known as walking technicolor. In this work we will consider a very general Ansatz for the technifermion self-energy, which is an essential ingredient to compute the scalar self-couplings. This Ansatz interpolates between all known forms of technifermionic self-energy. As we vary some
Segal, Nancy L
2016-06-01
The establishment of the Brazilian Twin Registry for the study of genetic, social, and cultural influences on behavior is one of eleven newly funded projects in the Department of Psychology at the University of São Paulo. These 11 interrelated projects form the core of the university's Center for Applied Research on Well-Being and Human Behavior. An overview of the planned twin research and activities to date is presented. Next, two recent twin studies are reviewed, one on the relationship between alcohol consumption and mortality, and the other on factors affecting maximal oxygen uptake. Twins cited in the media include the first identified superfecundated twins in Vietnam, adolescent twin relations, twins and triplets who work together, monozygotic twins with different skin tones and a co-twin control study that addresses the effects of space travel.
Search for the Higgs boson in H → WW → 2l2ν mode with the CMS ...
Indian Academy of Sciences (India)
2012-11-09
Nov 9, 2012 ... separated into three categories according to the event jet multiplicity: H + 0 jets, H + 1 jet, and H +2 jets. All Higgs production mechanisms are considered as part of the signal: the gluon fusion process, a Higgs boson in the final state accompanied by a W or Z boson or by a pair of top quarks, and the ...
The Higgs of the Higgs and the diphoton channel
Kannike, Kristjan
2016-07-20
LHC results do not confirm conventional natural solutions to the Higgs mass hierarchy problem, motivating alternative interpretations where a hierarchically small weak scale is generated from a dimension-less quantum dynamics. We propose weakly and strongly-coupled models where the field that breaks classical scale invariance giving mass to itself and to the Higgs is identified with a possible new resonance within the LHC reach. As an example, we identify such resonance with the 750 GeV diphoton excess recently reported by ATLAS and CMS. Such models can be extrapolated up to the Planck scale, provide Dark Matter candidates and eliminate the SM vacuum instability.
Toward a Strongly Interacting Scalar Higgs Particle
International Nuclear Information System (INIS)
Shalaby, Abouzeid M.; El-Houssieny, M.
2008-01-01
We calculate the vacuum energy of the non-Hermitian and PT symmetric (-gφ 4 ) 2+1 scalar field theory. Rather than the corresponding Hermitian theory and due to the asymptotic freedom property of the theory, the vacuum energy does not blow up for large energy scales which is a good sign to solve the hierarchy problem when using this model to break the U(1)xSU(2) symmetry in the standard model. The theory is strongly interacting and in fact, all the dimensionful parameters in the theory like mass and energy are finite even for very high energy scales. Moreover, relative to the vacuum energy for the Hermitian φ 4 theory, the vacuum energy of the non-Hermitian and PT symmetric (-gφ 4 ) 2+1 theory is tiny, which is a good sign toward the solution of the cosmological constant problem. Remarkably, these features of the non-Hermitian and PT symmetric (-gφ 4 ) 2+1 scalar field theory make it very plausible to be employed as a Higgs mechanism in the standard model instead of the problematic Hermitian Higgs mechanism
Search for the Standard Model Higgs Boson at D0 in the Final State with Two τ's and Two Jets
International Nuclear Information System (INIS)
Tschann-Grimm, Kathryn
2011-01-01
The Standard Model (SM) is a very successful description of particle physics, and its predictions have stood up to a multitude of precision experimental tests. But one of the central elements of the SM, the Higgs mechanism, has yet to be verified. The Higgs mechanism (and the associated Higgs Boson) generates electroweak symmetry breaking and consequently allows for W and Z bosons and fermions to be massive. This thesis presents a search for the SM Higgs boson at the D0 experiment using the Tevatron particle accelerator at Fermilab in the final state ττ + jet jet with 4.3 fb -1 of data. This final state is sensitive to the Higgs production mechanisms gluon-gluon fusion and vector-boson fusion, and to the Higgs produced in association with a W or Z, for Higgs masses from 100 to 200 GeV. We see no evidence for the Higgs boson, but by itself our search does not rule out the SM Higgs. When this analysis is combined with other searches at the Tevatron the Higgs can be ruled out at a 95% confidence level for the mass range from 156 to 177 GeV.
Energy Technology Data Exchange (ETDEWEB)
Ema, Yohei [Department of Physics, Faculty of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Karčiauskas, Mindaugas [University of Jyväskylä, Department of Physics, P.O. Box 35 (YFL), FI-40014, Jyväskylä (Finland); Lebedev, Oleg; Zatta, Marco, E-mail: ema@hep-th.phys.s.u-tokyo.ac.jp, E-mail: mindaugas.m.karciauskas@jyu.fi, E-mail: oleg.lebedev@helsinki.fi, E-mail: marco.zatta@helsinki.fi [University of Helsinki and Helsinki Institute of Physics, P.O. Box 64, FI-00014, Helsinki (Finland)
2017-06-01
Apparent metastability of the electroweak vacuum poses a number of cosmological questions. These concern evolution of the Higgs field to the current vacuum, and its stability during and after inflation. Higgs-inflaton and non-minimal Higgs-gravity interactions can make a crucial impact on these considerations potentially solving the problems. In this work, we allow for these couplings to be present simultaneously and study their interplay. We find that different combinations of the Higgs-inflaton and non-minimal Higgs-gravity couplings induce effective Higgs mass during and after inflation. This crucially affects the Higgs stability considerations during preheating. In particular, a wide range of the couplings leading to stable solutions becomes allowed.
Measurement of the top-Higgs Yukawa coupling at a Linear e+e- Collider
Gay, Arnaud
2006-01-01
Understanding the mechanism of electroweak symmetry breaking and the origin of boson and fermion masses is among the most pressing questions raised in contemporary particle physics. If these issues involve one (several) Higgs boson(s), a precise measurement of all its (their) properties will be of prime importance. Among those, the Higgs coupling to matter fermions (the Yukawa coupling). At a Linear Collider, the process e+e- -> ttH will allow in principle a direct measurement of the top-Higg...
“Electroweak symmetry breaking: to Higgs or not to Higgs” (3/3)
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.
“Electroweak symmetry breaking: to Higgs or not to Higgs” (2/3)
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.
“Electroweak symmetry breaking: to Higgs or not to Higgs” (1/3)
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.
De Curtis, Stefania; Tesi, Andrea
2012-01-01
We propose a four dimensional description of Composite Higgs Models which represents a complete framework for the physics of the Higgs as a pseudo-Nambu-Goldstone boson. Our setup captures all the relevant features of 5D models and more in general of composite Higgs models with partial compositeness. We focus on the minimal scenario where we include a single multiplet of resonances of the composite sector, as these will be the only degrees of freedom which might be accessible at the LHC. This turns out to be sufficient to compute the effective potential and derive phenomenological consequences of the theory. Moreover our simplified approach is well adapted to simulate these models at the LHC. We also consider the impact of non-minimal terms in the effective lagrangian which do not descend from a 5D theory and could be of phenomenological relevance, for example contributing to the S-parameter.
Semialigned two Higgs doublet model
Haba, Naoyuki; Umeeda, Hiroyuki; Yamada, Toshifumi
2018-02-01
In the left-right symmetric model based on S U (2 )L×S U (2 )R×U (1 )B -L gauge symmetry, there appear heavy neutral scalar particles mediating quark flavor changing neutral currents (FCNCs) at tree level. We consider a situation where such FCNCs give the only sign of the left-right model while WR gauge boson is decoupled, and name it "semialigned two Higgs doublet model" because the model resembles a two Higgs doublet model with mildly aligned Yukawa couplings to quarks. We predict a correlation among processes induced by quark FCNCs in the model, and argue that future precise calculation of meson-antimeson mixings and C P violation therein may hint at the semialigned two Higgs doublet model and the left-right model behind it.
Segal, Nancy L
2017-04-01
A January 2017 reunion of 10-year-old reared-apart Chinese twin girls was captured live on ABC's morning talk show Good Morning America, and rebroadcast on their evening news program Nightline. The twins' similarities and differences, and their participation in ongoing research will be described. This story is followed by reviews of twin research concerning genetic and environmental influences on media use, twin relations across the lifespan and the breast-feeding of opposite-sex twins. Popular interest items include twins in fashion, the second twin pair born to an internationally renowned tennis star, twin primes and twin pandas.
Geneva University: Search for the Higgs Boson at the LHC
2011-01-01
GENEVA UNIVERSITY Ecole de physique Département de physique nucléaire et corspusculaire 24, quai Ernest-Ansermet 1211 Genève 4 Tél.: (022) 379 62 73 Fax: (022) 379 69 92 Wednesday 16 November 2011 SEMINAIRE DE PHYSIQUE CORPUSCULAIRE at 17.00 hrs – Stückelberg Auditorium Search for the Higgs Boson at the LHC Prof Karl Jakobs, Université de Freiburg, Allemagne One of the prime tasks of the physics programme of the LHC is the investigation of electroweak symmetry breaking. In the Standard Model the Higgs mechanism is invoked to give masses to the electroweak gauge bosons and fermions and to restore unitarity of the theory at high energies. Although the Higgs mechanism is one of the cornerstones of the Standard Model it is experimentally not validated and the associated Higgs boson has escaped detection so far. The data accumulated at the LHC in the years 2010/11 allow already to establish tighter constraints on the allow...
Twinning anisotropy of tantalum during nanoindentation
Energy Technology Data Exchange (ETDEWEB)
Goel, Saurav, E-mail: S.GOEL@qub.ac.uk [School of Mechanical and Aerospace Engineering, Queen' s University, Belfast, BT9 5AH (United Kingdom); Beake, Ben [Micro Materials Limited, Willow House, Yale Business Village, Ellice Way, Wrexham LL13 7YL (United Kingdom); Dalton Research Institute, Manchester Metropolitan University, Manchester, M15GD (United Kingdom); Chan, Chi-Wai [School of Mechanical and Aerospace Engineering, Queen' s University, Belfast, BT9 5AH (United Kingdom); Haque Faisal, Nadimul [School of Engineering, Robert Gordon University, Garthdee Road, Aberdeen AB10 7GJ (United Kingdom); Dunne, Nicholas [School of Mechanical and Aerospace Engineering, Queen' s University, Belfast, BT9 5AH (United Kingdom)
2015-03-11
Unlike other BCC metals, the plastic deformation of nanocrystalline Tantalum (Ta) during compression is regulated by deformation twinning. Whether or not this twinning exhibits anisotropy was investigated through simulation of displacement-controlled nanoindentation test using molecular dynamics (MD) simulation. MD data was found to correlate well with the experimental data in terms of surface topography and hardness measurements. The mechanism of the transport of material was identified due to the formation and motion of prismatic dislocations loops (edge dislocations) belonging to the 1/2〈111〉 type and 〈100〉 type Burgers vector family. Further analysis of crystal defects using a fully automated dislocation extraction algorithm (DXA) illuminated formation and migration of twin boundaries on the (110) and (111) orientation but not on the (010) orientation and most importantly after retraction all the dislocations disappeared on the (110) orientation suggesting twinning to dominate dislocation nucleation in driving plasticity in tantalum. A significant finding was that the maximum shear stress (critical Tresca stress) in the deformation zone exceeded the theoretical shear strength of Ta (Shear modulus/2π~10.03 GPa) on the (010) orientation but was lower than it on the (110) and the (111) orientations. In light of this, the conventional lore of assuming the maximum shear stress being 0.465 times the mean contact pressure was found to break down at atomic scale.
In situ observations of crack arrest and bridging by nanoscale twins in copper thin films
International Nuclear Information System (INIS)
Kim, Seong-Woong; Li Xiaoyan; Gao Huajian; Kumar, Sharvan
2012-01-01
In situ tensile experiments in a transmission electron microscope revealed that micro-cracks in ultrafine grained, free-standing, thin copper foils containing nanoscale twins initiated in matrix domains separated by the twins and then arrested at twin boundaries as twin boundary sliding proceeded. The adjacent microcracks eventually coalesced through shear failure of the bridging twins. To investigate the atomic mechanism of this rarely seen nanoscale crack bridging behavior, molecular dynamics simulations were performed to show that during crack propagation twin boundaries are impinged upon by numerous dislocations from the plastically deforming matrix. These dislocations react at the interface and evolve into substantially impenetrable dislocation walls that strongly confine crack nucleation and resist crack propagation, leading to the experimentally observed crack bridging behavior. The present results raise an approach to significantly toughening polycrystalline thin films by incorporating nanoscale twin structures into individual grains that serve as crack bridging ligaments.
International Nuclear Information System (INIS)
Mueller, I.; Zak, G.
1995-01-01
The quasiplastic hysteresis occuring in shape memory alloys is associated with twinning in tension and compression, i.e. a conversion of one martensitic variant into antoher one. It shows the phenomena of internal elasticity and internal yield, heretofore studied extensively in pseudoelasticity. This paper presents experimental evidence of such phenomena and it offers partial explanation in identifying the onset of yield as an instability phenomenon due to coherency. That conjecture is motivated from a previous consideration of pseudoelasticity. (orig.)
Monozygotic twins with discordant intestinal rotation
International Nuclear Information System (INIS)
Smith, Vance L.; Nwomeh, Benedict C.; Long, Frederick
2006-01-01
Previous case reports have suggested a strong concordance of intestinal malrotation among identical twins. This has led to the recommendation that the asymptomatic twin undergo screening when malrotation is discovered in the identical sibling. We present a case of monozygotic twins in which one twin presented with intestinal malrotation with midgut volvulus while the other twin was found to have normal gastrointestinal anatomy. (orig.)
Monozygotic twins with discordant intestinal rotation
Energy Technology Data Exchange (ETDEWEB)
Smith, Vance L.; Nwomeh, Benedict C. [Ohio State University College of Medicine and Public Health, Department of Pediatric Surgery, Columbus Children' s Hospital, Columbus, OH (United States); Long, Frederick [Ohio State University College of Medicine and Public Health, Department of Radiology, Columbus Children' s Hospital, Columbus, OH (United States)
2006-04-15
Previous case reports have suggested a strong concordance of intestinal malrotation among identical twins. This has led to the recommendation that the asymptomatic twin undergo screening when malrotation is discovered in the identical sibling. We present a case of monozygotic twins in which one twin presented with intestinal malrotation with midgut volvulus while the other twin was found to have normal gastrointestinal anatomy. (orig.)
Four generations and Higgs physics
Energy Technology Data Exchange (ETDEWEB)
Kribs, Graham D. [Department of Physics and Institute of Theoretical Science, University of Oregon, Eugene (United States); Plehn, Tilman [SUPA, School of Physics, University of Edinburgh (United Kingdom); Spannowsky, Michael [Institut fuer Theoretische Physik, Universitaet Karlsruhe (Germany); Tait, Tim M.P. [HEP Division, Argonne National Laboratory (United States)
2008-07-01
A fourth generation has been considered and forgotten or discarded several times, wrongly leaving the impression that it is either ruled out or disfavored by experimental data. We revisit a fourth generation of chiral matter in the light of present electroweak precision data and deduce effects on Higgs phenomenology. We find a chiral fourth generation to be a viable model which can yield interesting signatures at the LHC, e.g. production rates are enhanced, weak-boson-fusion channels are suppressed, angular distributions are modified and Higgs pairs can be observed.
Twinning in Zircon: Not a High-Pressure Phenomenon
Jones, G. A.; Moser, D.; Shieh, S. R.; Barker, I.
2017-12-01
Microtwins in zircon are commonly found in shocked terrestrial and extraterrestrial samples and are potentially important for shock history and crater reconstruction. Twinning is easily observed with both the optical microscope and variety of electron beam techniques. Twinning as a deformation mechanism is consistent with the high strain rates generated during impact. No constitutive relationships, or even general limits on the physical conditions required for twinning in zircon are known, however. Present speculation on the critical quantity for twin formation, i.e. 10s of GPa of shock pressure (Moser et al. 2011, Timms et al., 2012), has no basis in the underlying mechanisms of twin nucleation, which are related to the motion of dislocations. This erroneous value is due to conflation of twinning sensu stricto with a phase transformation to reidite. Reidite occurs as twin-like lamellae occupying the {112} planes which are thought to be a mirror plane for twinning. We review the crystallographic theory of twinning in zircon. We then evaulate several theories on the nucleation of twins along with their necessary stresses involved. Our aim is to show that shock microtwins in zircon can be a `low pressure' shock phenomenon. This 'low pressure' hypothesis is supported by natural samples. These zircons are from the lower crust nearly 80 km from the centre of the Vredefort impact structure—the most distal zircon shock microstructures yet found in the lithosphere. Twins are present in 10% of the zircon grains greater than 50 µm in diameter. As an extensive, 'low pressure' phenomenon, twins are an easily recognized and potentially widespread record of Earth's impact history.Moser, D.E., Cupelli, C. L., Barker, I., Flowers, R. M., Mowman, J. R., Wooden, J. and Hart, R. (2011) New zircon shock phenomena and their use for dating and […] analysis of the Vredefort dome, Canadian Journal of Earth Sciences 48(2), 117-139.Timms, N.E., Reddy, S. M., Healy, D., Nemchin, A. A
International Nuclear Information System (INIS)
Low, I.; Schwaller, P.; Shaughnessy, G.; Wagner, C.E.M.
2012-01-01
Current limits from the Large Hadron Collider exclude a standard model-like Higgs mass above 150 GeV, by placing an upper bound on the Higgs production rate. We emphasize that, alternatively, the limit could be interpreted as a lower bound on the total decay width of the Higgs boson. If the invisible decay width of the Higgs is of the same order as the visible decay width, a heavy Higgs boson could be consistent with null results from current searches. We propose a method to infer the invisible decay of the Higgs by using the width of the measured h → ZZ → 4 (ell) line shape, and study the effect on the width extraction due to a reduced signal strength. Assuming the invisible decay product is the dark matter, we show that minimal models are tightly constrained by limits from Higgs searches at the LHC and direct detection experiments of dark matter, unless the relic density constraint is relaxed.
Higgs searches and prospects at CDF
International Nuclear Information System (INIS)
Pavel A Murat
2003-01-01
The Standard model of electroweak interactions (SM) has been extremely successful in describing interactions of elementary particles over the last decades. The Higgs scalar boson is one of the key elements of the SM: Higgs interactions with the other particles generate the particle masses and allow to keep the theory renormalizable at electroweak scale. All the particles predicted by the SM but the Higgs boson have already been observed experimentally and therefore search for the Higgs is one of the most important scientific goals for high energy physics. The current lower limit on the SM Higgs mass M H > 114.4 GeV at 95% CL has been established by LEP experiments. In this paper we review CDF Run I results on Higgs searches including the Higgs bosons predicted by the minimal supersymmetric extention of the Standard Model (MSSM) and discuss the Run II prospects
Higgs-Palatini inflation and unitarity
International Nuclear Information System (INIS)
Bauer, Florian; Demir, Durmus A.
2011-01-01
In the Higgs inflation scenario the Higgs field is strongly coupled to the Ricci scalar in order to drive primordial inflation. However, in its original form in pure metric formulation of gravity, the ultraviolet (UV) cutoff of the Higgs interactions and the Hubble rate are of the same magnitude, and this makes the whole inflationary evolution dependent of the unknown UV completion of the Higgs sector. This problem, the unitarity violation, plagues the Higgs inflation scenario. In this Letter we show that, in the Palatini formulation of gravitation, Higgs inflation does not suffer from unitarity violation since the UV cutoff lies parametrically much higher than the Hubble rate so that unknown UV physics does not disrupt the inflationary dynamics. Higgs-Palatini inflation, as we call it, is, therefore, UV-safe, minimal and endowed with predictive power.
The Higgs sector of gravitational gauge theories
International Nuclear Information System (INIS)
Leclerc, M.
2006-01-01
Gravitational gauge theories with de Sitter, Poincare and affine symmetry group are investigated under the aspect of the breakdown of the initial symmetry group down to the Lorentz subgroup. As opposed to the nonlinear realization approach, in the dynamical symmetry breaking procedure, the structure subgroup is not chosen arbitrarily, but is dictated by the symmetry of the groundstate of a Higgs field. We review the theory of spontaneously broken de Sitter gravity by Stelle and West and apply a similar approach to the case of the Poincare and affine groups. We will find that the Poincare case is almost trivial. The translational Higgs field reveals itself as pure gauge, i.e., it is expressed entirely in terms of the Nambu-Goldstone bosons and does not appear in the Lagrangian after the symmetry breaking. The same holds for the translational part of the affine group. The Higgs field provoking the breakdown of the general linear group leads to the determination of the Lorentzian signature of the metric in the groundstate. We show that the Higgs field remains in its groundstate, i.e., that the metric will have Lorentzian signature, unless we introduce matter fields that explicitely couple to the symmetric part of the connection. Furthermore, we present arguments that the Lorentzian signature is actually the only possible choice for physical spacetime, since the symmetry breaking mechanism works only if the stability subgroup is taken to be the Lorentz group. The other four-dimensional rotation groups are therefore ruled out not only on physical, but also on theoretical grounds. Finally, we show that some features, like the necessity of the introduction of a dilaton field, that seem artificial in the context of the affine theory, appear most natural if the gauge group is taken to be the special linear group in five dimensions. We also present an alternative model which is based on the spinor representation of the Lorentz group and is especially adopted to the
Exploring collider aspects of a neutrinophilic Higgs doublet model in multilepton channels
Huitu, Katri; Kärkkäinen, Timo J.; Mondal, Subhadeep; Rai, Santosh Kumar
2018-02-01
We consider a neutrinophilic Higgs scenario where the Standard Model is extended by one additional Higgs doublet and three generations of singlet right-handed Majorana neutrinos. Light neutrino masses are generated through mixing with the heavy neutrinos via the Type-I seesaw mechanism when the neutrinophilic Higgs gets a vacuum expectation value (VEV). The Dirac neutrino Yukawa coupling in this scenario can be sizable compared to those in the canonical Type-I seesaw mechanism owing to the small neutrinophilic Higgs VEV giving rise to interesting phenomenological consequences. We have explored various signal regions likely to provide a hint of such a scenario at the LHC as well as at future e+e- colliders. We have also highlighted the consequences of light neutrino mass hierarchies in collider phenomenology that can complement the findings of neutrino oscillation experiments.
The No-Higgs Signal: Strong WW Scattering at the LHC
Energy Technology Data Exchange (ETDEWEB)
Michael S. Chanowitz
2004-12-07
Strong WW scattering at the LHC is discussed as a manifestation of electroweak symmetry breaking in the absence of a light Higgs bosom. The general framework of the Higgs mechanism--with or without a Higgs boson--is reviewed, and unitarity is shown to fix the scale of strong WW scattering. Strong WW scattering is also shown to be a possible outcome of five-dimensional models, which do not employ the usual Higgs mechanism at the TeV scale. Precision electroweak constraints are briefly discussed. Illustrative LHC signals are reviewed for models with QCD-like dynamics, stressing the complementarity of the W{sup {+-}}Z and like-charge W{sup +}W{sup +} + W{sup -}W{sup -} channels.
Illustrations of the twin paradox
International Nuclear Information System (INIS)
Rebhan, E.
1985-01-01
In order to provide a more intuitive understanding of the twin paradox, several illustrations of this are presented. In one of these, each of the twins is equipped with a lamp whose monochromatic light can be observed by the other. In other illustrations the travelling twin uses an Einstein train instead of a space ship, all the cars of the train and all stations along the route of the train being equipped with clocks. (author)
Beyond The Standard Model Higgs Physics with Photons with the CMS Detector
Teixeira de Lima, Rafael
The experimental discovery of the Higgs boson is one of the latest successes of the Standard Model of particle physics. Although all measurements have confirmed that this newly discovered particle is the Higgs boson predicted by the Standard Model, with no deviations to suggest otherwise, the Higgs boson can guide us to new models which modify the electroweak symmetry breaking mechanism or predict new states that couple to the Higgs. Therefore, it's paramount to directly look for modifications of our current model with the help of the recently discovered particle. In this thesis, two analyses involving beyond the Standard Model physics tied to the Higgs sector will be explored. First, looking at exotic Higgs decays, an analysis searching for the final state with photons and missing transverse energy will be presented. Then, the search for Higgs pair production, both resonantly and non-resonantly (a process predicted by the Standard Model, albeit at very low rates), in the final state with two bottom quark je...
Microplastic processes developed in pure Ag with mesoscale annealing twins
International Nuclear Information System (INIS)
Al-Fadhalah, Khaled Jabr Hasan; Li, Chun-Ming; Beaudoin, A.J.; Korzekwa, D.A.; Robertson, I.M.
2008-01-01
The impact of annealing twin boundaries with a high residual defect content on the mechanical response of polycrystalline fine- and coarse-grained (2 and 20 μm) silver was investigated through transmission electron microscopy and modeling. Besides an increase in the yield strength, the fine-grained material exhibited an inflection in the stress-strain curve after initial yield. Static and dynamic TEM studies revealed that the annealing twin boundaries acted as sources of perfect dislocations, partial dislocations and deformation twins; as barriers to the propagation of these dislocations; and as annihilation sites for dislocations. With increasing strain and as the twin boundaries were penetrated by dislocations, they contributed less to the overall mechanical properties. Based on these observations, equations for the evolution of mobile and forest dislocation densities are posed, depicting boundary sources and dislocation-dislocation interactions, respectively. The deformation response is modeled by computing the aggregate response of matrix-twin composite grains in the viscoplastic self-consistent scheme, which permits consideration of compatibility and equilibrium requirements across the twin boundaries. This work highlights the significant role boundaries play in generating the dislocations that control the macroscopic mechanical response
Microplastic processes developed in pure Ag with mesoscale annealing twins
Energy Technology Data Exchange (ETDEWEB)
Al-Fadhalah, Khaled Jabr Hasan [Mechanical Engineering Department, College of Engineering and Petroleum, Kuwait University, P.O. Box 5969, Safat 13060 (Kuwait)], E-mail: fadhalah@kuc01.kuniv.edu.kw; Li, Chun-Ming [Alcan Rolled Products-Ravenswood, LLC. P.O. Box 68, Century Road, Ravenswood, WV 26164 (United States)], E-mail: chun-ming.li@alcan.com; Beaudoin, A.J. [Department of Mechanical Science and Engineering, University of Illinois, 1206 West Green Street, Urbana, IL 61801 (United States)], E-mail: abeaudoi@uiuc.edu; Korzekwa, D.A. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Robertson, I.M. [Department of Materials Science and Engineering, University of Illinois, 1304 W. Green Street, Urbana, IL 61801 (United States)], E-mail: ianr@uiuc.edu
2008-11-15
The impact of annealing twin boundaries with a high residual defect content on the mechanical response of polycrystalline fine- and coarse-grained (2 and 20 {mu}m) silver was investigated through transmission electron microscopy and modeling. Besides an increase in the yield strength, the fine-grained material exhibited an inflection in the stress-strain curve after initial yield. Static and dynamic TEM studies revealed that the annealing twin boundaries acted as sources of perfect dislocations, partial dislocations and deformation twins; as barriers to the propagation of these dislocations; and as annihilation sites for dislocations. With increasing strain and as the twin boundaries were penetrated by dislocations, they contributed less to the overall mechanical properties. Based on these observations, equations for the evolution of mobile and forest dislocation densities are posed, depicting boundary sources and dislocation-dislocation interactions, respectively. The deformation response is modeled by computing the aggregate response of matrix-twin composite grains in the viscoplastic self-consistent scheme, which permits consideration of compatibility and equilibrium requirements across the twin boundaries. This work highlights the significant role boundaries play in generating the dislocations that control the macroscopic mechanical response.
LEP Higgs boson searches beyond the standard model
Indian Academy of Sciences (India)
These include the searches for charged Higgs bosons, models with two Higgs field doublets, searches for 'fermiophobic' Higgs decay, invisible Higgs boson decays, decay-mode independent searches, and limits on Yukawa and anomalous Higgs couplings. I review the searches done by the four LEP experiments and ...
Aberrant twinning (diprosopus) associated with anencephaly.
Moerman, P; Fryns, J P; Goddeeris, P; Lauweryns, J M; Van Assche, A
1983-10-01
A case of Monocephalus diprosopus, associated with craniorachischisis and duplication of most of the foregut derivates is presented. The major part of the cardiovascular system remained single but the heart exhibited severe defects, including a complete persistent atrioventricular canal, transposition of the great arteries and atresia of the pulmonary valve. This report further supports the hypothesis that certain-types of incomplete twinning and neural tube defects may be caused by a single teratogenic mechanism.
Higgs boson: the winner takes it all?
Antonella Del Rosso
2015-01-01
Since its discovery in 2012, the Higgs boson has been in the spotlight for both experimentalists and theorists. In addition to its confirmed role in the mass mechanism, recent papers have discussed its possible role in the inflation of the universe and in the matter-antimatter imbalance. Can a single particle be responsible for everything? “Since 2012 we have known that the Higgs boson exists, but its inner properties are yet to be completely uncovered,” says Gian Giudice, a member of the CERN Theory Unit. “Precise measurements of its decay modes are still ongoing and the LHC Run 2 will be essential to understand the nature of this particle at a deeper level.” What we know is that this boson is not “yet another particle” among the hundreds that we deal with every day in physics labs. In agreement with the Standard Model theory, the recent experimental data confirms that the particle discovered by the CERN experiments is the key pa...
The origin of mass - without Higgs
Energy Technology Data Exchange (ETDEWEB)
Giese, Albrecht
2016-07-01
The detection of the ''Higgs'' boson has caused great excitement in the physical community. However, most physicists overlook the fact that the corresponding theory is in no way able to explain inertial mass. On the one hand, the theory does not provide a means to determine the mass of an individual particle. The necessary Yukawa coupling does not follow from the theory. On the other hand, cosmological investigations show that the Higgs field needed is at least 57 orders of magnitude stronger than any actual existing vacuum field. The inertial mass follows very simply from the fact that any extended object necessarily displays inertial behaviour. This is a consequence of the finiteness of the speed of light, by which binding forces propagate. If this mechanism is applied to existing particles, it yields the mass of the electron, for example, with a precision of better than 10{sup -5}, using the size of the particle. It also covers the relativistic increase of mass due to motion, and as a consequence the famous equation E=mc{sup 2}.
New ATLAS Higgs physics results
CERN. Geneva
2014-01-01
New Higgs physics results from the ATLAS experiment using the full Run-1 LHC dataset, corresponding to an integrated luminosity of approximately 25 fb-1, of proton-proton collisions at 7 TeV and 8 TeV, will be presented.
Higgs mass determination in supersymmetry
Energy Technology Data Exchange (ETDEWEB)
Vega, Javier Pardo [Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy); SISSA International School for Advanced Studies and INFN Trieste, Via Bonomea 265, 34136, Trieste (Italy); Villadoro, Giovanni [Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy)
2015-07-29
We present the state-of-the-art of the effective field theory computation of the MSSM Higgs mass, improving the existing ones by including extra threshold corrections. We show that, with this approach, the theoretical uncertainty is within 1 GeV in most of the relevant parameter space. We confirm the smaller value of the Higgs mass found in the EFT computations, which implies a slightly heavier SUSY scale. We study the large tan β region, finding that sbottom thresholds might relax the upper bound on the scale of SUSY. We present SUSYHD, a fast computer code that computes the Higgs mass and its uncertainty for any SUSY scale, from the TeV to the Planck scale, even in Split SUSY, both in the (DR)-bar and in the on-shell schemes. Finally, we apply our results to derive bounds on some well motivated SUSY models, in particular we show how the value of the Higgs mass allows to determine the complete spectrum in minimal gauge mediation.
International Nuclear Information System (INIS)
Sutherland, D.G.
2005-01-01
Most recent models assuming the Higgs boson is a pseudo-Nambu-Goldstone boson (pNGb) are motivated by the indication from Standard Model fits that its mass is = SU(3) model we use is briefly discussed. Some potential theoretical and phenomenological problems are mentioned briefly
The Higgs boson and cosmology.
Shaposhnikov, Mikhail
2015-01-13
I will discuss how the Higgs field of the Standard Model may have played an important role in cosmology, leading to the homogeneity, isotropy and flatness of the Universe; producing the quantum fluctuations that seed structure formation; triggering the radiation-dominated era of the hot Big Bang; and contributing to the processes of baryogenesis and dark matter production.
Higgs boson properties in ATLAS
Mansoulie, Bruno; The ATLAS collaboration
2017-01-01
The measurement by the ATLAS collaboration of Higgs boson properties is presented, in terms of production cross-sections, simplified template cross-sections, couplings. The measurements are based on the analysis of the H decay channels to diphoton and 4 leptons, using 36.1 fb-1 of 13 TeV data recorded in 2015 and 2016.
Shaposhnikov, Mikhail
2015-01-01
I will discuss how the Higgs field of the Standard Model may have played an important role in cosmology, leading to the homogeneity, isotropy and flatness of the Universe; producing the quantum fluctuations that seed structure formation; triggering the radiation-dominated era of the hot Big Bang; and contributing to the processes of baryogenesis and dark matter production.
The discovery and measurements of a Higgs boson.
Gianotti, F; Virdee, T S
2015-01-13
In July 2012, the ATLAS and CMS collaborations at CERN's Large Hadron Collider announced the discovery of a Higgs-like boson, a new heavy particle at a mass more than 130 times the mass of a proton. Since then, further data have revealed its properties to be strikingly similar to those of the Standard Model Higgs boson, a particle expected from the mechanism introduced almost 50 years ago by six theoreticians including British physicists Peter Higgs from Edinburgh University and Tom Kibble from Imperial College London. The discovery is the culmination of a truly remarkable scientific journey and undoubtedly the most significant scientific discovery of the twenty-first century so far. Its experimental confirmation turned out to be a monumental task requiring the creation of an accelerator and experiments of unprecedented capability and complexity, designed to discern the signatures that correspond to the Higgs boson. Thousands of scientists and engineers, in each of the ATLAS and CMS teams, came together from all four corners of the world to make this massive discovery possible.
Evidence of Higgs Boson Production through Vector Boson Fusion
AUTHOR|(INSPIRE)INSPIRE-00333580
The discovery of the Higgs boson in 2012 provided confirmation of the proposed mechanism for preserving the electroweak $SU(2) \\times U(1)$ gauge symmetry of the Standard Model of particle physics. It also heralded in a new era of precision Higgs physics. This thesis presents a measurement of the rate at which the Higgs boson is produced by vector boson fusion in the \\wwlnln decay channel. With gauge boson couplings in both the production and decay vertices, a VBF measurement in this channel is a powerful probe of the $VVH$ vertex strength. Using $4.5$~fb$^{-1}$ and $20.3$~fb$^{-1}$ of $pp$ collision data collected at respective center-of-mass energies of 7 and $8 \\tev$ in the ATLAS detector, measurements of the statistical significance and the signal strength are carried out in the Higgs mass range $100 \\leq m_H \\leq 200 \\gev$. These measurements are enhanced with a boosted decision tree that exploits the correlations between eight kinematic inputs in order to separate signal and background processes. At the...
Molecular dynamics simulation of effects of twin interfaces on Cu/Ni multilayers
International Nuclear Information System (INIS)
Fu, Tao; Peng, Xianghe; Weng, Shayuan; Zhao, Yinbo; Gao, Fengshan; Deng, Lijun; Wang, Zhongchang
2016-01-01
We perform molecular dynamics simulation of the indentation on pure Cu and Ni films and Cu/Ni multilayered films with a cylindrical indenter, aimed to investigate the effects of the cubic-on-cubic interface and hetero-twin interface on their mechanical properties. We also investigate systematically the formation of twin boundary in the pure metals and the effects of the cubic-on-cubic and hetero-twin interface on mechanical properties of the multilayers. We find that the slip of the horizontal stacking fault can release the internal stress, resulting in insignificant strengthening. The change in the crystal orientation by horizontal movement of the atoms in a layer-by-layer manner is found to initiate the movement of twin boundary, and the hetero-twin interface is beneficial to the hardening of multilayers. Moreover, we also find that increasing number of hetero-twin interfaces can harden the Cu/Ni multilayers.
Twinning structures in near-stoichiometric lithium niobate single crystals
International Nuclear Information System (INIS)
Yao, Shuhua; Chen, Yanfeng
2010-01-01
A near-stoichiometric lithium niobate single crystal has been grown by the Czochralski method in a hanging double crucible with a continuous powder supply system. Twins were found at one of the three characteristic growth ridges of the as-grown crystal. The twin structure was observed and analyzed by transmission synchrotron topography. The image shifts ΔX and ΔY in the transmission synchrotron topograph were calculated for the 3 anti 2 anti 12 and 0 anti 222 reflections based on results from high-resolution X-ray diffractometry. It is confirmed that one of the {01 anti 1 anti 2} m planes is the composition face of the twin and matrix crystals. The formation mechanism of these twins is discussed. (orig.)
EBSD characterization of twinning in cold-rolled CP-Ti
International Nuclear Information System (INIS)
Li, X.; Duan, Y.L.; Xu, G.F.; Peng, X.Y.; Dai, C.; Zhang, L.G.; Li, Z.
2013-01-01
This work presents the use of a mechanical testing system and the electron backscatter diffraction technique to study the mechanical properties and twinning systems of cold-rolled commercial purity titanium, respectively. The dependence of twinning on the matrix orientation is analyzed by the distribution map of Schmid factor. The results showed that the commercial purity titanium experienced strong strain hardening and had excellent formability during rolling. Both the (112 ¯ 2) ¯ 3 ¯ > compressive twins and (101 ¯ 2) ¯ 1 ¯ > tensile twins were dependent on the matrix orientation. The Schmid factor of a grain influenced the activation of a particular twinning system. The specific rolling deformation of commercial purity titanium controlled the number and species of twinning systems and further changed the mechanical properties. - Highlights: • CP-Ti experienced strain hardening and had excellent formability. • Twins were dependent on the matrix orientation. • Schmid factor of a grain influenced the activation of a twinning system. • Rolling deformation controlled twinning systems and mechanical properties
From monster to twin reversed arterial perfusion: a history of acardiac twins.
Obladen, Michael
2010-05-01
A human being born without heart and head, i.e., the acardius/acranius malformation, has been described since antiquity. Superstition and fear made it a mystical disorder, a sign of God's wrath. The inquisition ruled that acranic infants should not be baptized and located the soul in the brain. Acardia was not associated with twin gestation until the reports of Mery in 1720 and Winslow in 1740. In 1850, Meckel identified the pathogenetic mechanism as reversed perfusion due to large arterio-arterial and veno-venous anastomoses; he believed the heart would fail to develop or arrest during development, and the acardiac fetus would be maintained by arterial perfusion from the pump twin. In 1859, Claudius articulated that after normal initial development, the heart degenerates when reversed flow in the aorta leads to thrombosis. Today, it is assumed that both mechanisms may exist. With the advent of prenatal ultrasound diagnosis and radiofrequency ablation of the acardiac twin's circulation, it became possible to save the pump twin.
Effect of multiple Higgs fields on the phase structure of the SU(2)-Higgs model
International Nuclear Information System (INIS)
Wurtz, Mark; Steele, T. G.; Lewis, Randy
2009-01-01
The SU(2)-Higgs model, with a single Higgs field in the fundamental representation and a quartic self-interaction, has a Higgs region and a confinement region which are analytically connected in the parameter space of the theory; these regions thus represent a single phase. The effect of multiple Higgs fields on this phase structure is examined via Monte Carlo lattice simulations. For the case of N≥2 identical Higgs fields, there is no remaining analytic connection between the Higgs and confinement regions, at least when Lagrangian terms that directly couple different Higgs flavors are omitted. An explanation of this result in terms of enhancement from overlapping phase transitions is explored for N=2 by introducing an asymmetry in the hopping parameters of the Higgs fields. It is found that an enhancement of the phase transitions can still occur for a moderate (10%) asymmetry in the resulting hopping parameters.
Higher-order corrected Higgs bosons in FeynHiggs2.4
Indian Academy of Sciences (India)
treatment of loop-corrected Higgs-boson mass eigenstates as external (on-shell) or internal .... This gives rise to finite wave function normalization factors. [22]. .... The elements of Un can be interpreted as effective couplings of internal Higgs.
Distinguishing a SM-like MSSM Higgs boson from SM Higgs boson at muon collider
International Nuclear Information System (INIS)
Singhal, Jai Kumar; Singh, Sardar; Nagawat, Ashok K.
2007-01-01
We explore the possibility of distinguishing the SM-like MSSM Higgs boson from the SM Higgs boson via Higgs boson pair production at future muon collider. We study the behavior of the production cross-section in SM and MSSM with Higgs boson mass for various MSSM parameters tanβ and m A . We observe that at fixed CM energy, in the SM, the total cross-section increases with the increase in Higgs boson mass whereas this trend is reversed for the MSSM. The changes that occur for the MSSM in comparison to the SM predictions are quantified in terms of the relative percentage deviation in cross-section. The observed deviations in cross-section for different choices of Higgs boson masses suggest that the measurements of the cross-section could possibly distinguish the SM-like MSSM Higgs boson from the SM Higgs boson. (author)
Voice similarity in identical twins.
Van Gysel, W D; Vercammen, J; Debruyne, F
2001-01-01
If people are asked to discriminate visually the two individuals of a monozygotic twin (MT), they mostly get into trouble. Does this problem also exist when listening to twin voices? Twenty female and 10 male MT voices were randomly assembled with one "strange" voice to get voice trios. The listeners (10 female students in Speech and Language Pathology) were asked to label the twins (voices 1-2, 1-3 or 2-3) in two conditions: two standard sentences read aloud and a 2.5-second midsection of a sustained /a/. The proportion correctly labelled twins was for female voices 82% and 63% and for male voices 74% and 52% for the sentences and the sustained /a/ respectively, both being significantly greater than chance (33%). The acoustic analysis revealed a high intra-twin correlation for the speaking fundamental frequency (SFF) of the sentences and the fundamental frequency (F0) of the sustained /a/. So the voice pitch could have been a useful characteristic in the perceptual identification of the twins. We conclude that there is a greater perceptual resemblance between the voices of identical twins than between voices without genetic relationship. The identification however is not perfect. The voice pitch possibly contributes to the correct twin identifications.
Twin Studies of Atopic Dermatitis
DEFF Research Database (Denmark)
Elmose, Camilla; Thomsen, Simon Francis
2015-01-01
Aim. The aim of this study was to conduct a systematic review of population-based twin studies of (a) the concordance and heritability of AD and (b) the relationship between AD and asthma and, furthermore, to reinterpret findings from previous twin studies in the light of the emerging knowledge a...
Hypertensive disorders in twin pregnancy
J.G. Santema (Job); E. Koppelaar (Elin); H.C.S. Wallenburg (Henk)
1995-01-01
textabstractObjective: To compare the incidence and severity of pregnancy-induced hypertensive disorders in twin pregnancy and in singleton gestation. Study design: Case-control study in the setting of a University Hospital. Each pregnancy of a consecutive series of 187 twin pregnancies attending
Ferrobielastic twinning in irradiated quartz
International Nuclear Information System (INIS)
Shiau, S.M.
1986-01-01
Cultured quartz is usually free from electrical twinning; however, it may occur if the seed crystal is twinned or if undue applied forces are exerted on the crystal. Ferrobielastic twinning was studied optically (photoelastic effect) and electrically (piezoelectric effect). At room temperature, twins were perceptible at stresses of about 2.l5 x 10 8 N/m 2 , and crystals switched from their original states to the alternative twin states at stresses about 5.0 x 10 8 N/m 2 (called coercive stress). The decrease in coercive stress with increasing temperature was observed, and these coercive stresses become very low as temperatures reach to 300 0 C. The effects of irradiation on the twinning in quartz were also studied. The presence of defects produced by irradiation was utilized to pin the domain wall motion. Both neutrons and gamma rays were employed. The stress required to nucleate an appreciable volume of twins is about twice as high for irradiated crystals than for those unirradiated. This result demonstrated that the irradiated crystals can tolerate higher stresses. However, the coercive stress for complete switch-over was not much different for irradiated and unirradiated crystals. It appears that the defects caused by irradiation eliminate the initial twinning events but do not affect switch-over
Segal, Nancy L
2017-08-01
The late neurologist and author, Oliver Sacks, published an insightful 1986 review of Marjorie Wallace's book, The Silent Twins, in the New York Times. Taking exception to his assertion about Sir Francis Galton, I wrote a letter to the Times' editor. The letter was unpublished, but it brought a wonderful response from Sacks himself that is reproduced and examined. Next, brief reviews of twin research concerning the vanishing twin syndrome (VTS), discordant sex in a monozygotic (MZ) twin pair, and multiple pregnancy outcomes from assisted reproductive technology (ART) are presented. This section is followed by popular coverage of superfetated twins, smoking-discordant co-twins, twins in fashion, Yale University twin hockey players, and a visiting professor who was a conjoined twin.
Higgs data does not rule out a sequential fourth generation with an extended scalar sector
Das, Dipankar; Kundu, Anirban; Saha, Ipsita
2018-01-01
Contrary to common perception, we show that the current Higgs data does not eliminate the possibility of a sequential fourth generation that get their masses through the same Higgs mechanism as the first three generations. The inability to fix the sign of the bottom-quark Yukawa coupling from the available data plays a crucial role in accommodating a chiral fourth generation which is consistent with the bounds on the Higgs signal strengths. We show that effects of such a fourth generation can remain completely hidden not only in the production of the Higgs boson through gluon fusion but also to its subsequent decay to γ γ and Z γ . This, however, is feasible only if the scalar sector of the standard model is extended. We also provide a practical example illustrating how our general prescription can be embedded in a realistic model.
Electroweak symmetry breaking and mass spectra in six-dimensional gauge-Higgs grand unification
Hosotani, Yutaka; Yamatsu, Naoki
2018-02-01
The mass spectra of the standard model particles are reproduced in the SO(11) gauge-Higgs grand unification in six-dimensional warped space without introducing exotic light fermions. Light neutrino masses are explained by the gauge-Higgs seesaw mechanism. We evaluate the effective potential of the four-dimensional Higgs boson appearing as a fluctuation mode of the Aharonov-Bohm phase θ_H in the extra-dimensional space, and show that the dynamical electroweak symmetry breaking takes place with the Higgs boson mass m_H ˜ 125 GeV and θ_H ˜ 0.1. The Kaluza-Klein mass scale in the fifth dimension is approximately given by m_KK ˜ 1.230 TeV/sin θ_H.
A Computational Discriminability Analysis on Twin Fingerprints
Liu, Yu; Srihari, Sargur N.
Sharing similar genetic traits makes the investigation of twins an important study in forensics and biometrics. Fingerprints are one of the most commonly found types of forensic evidence. The similarity between twins’ prints is critical establish to the reliability of fingerprint identification. We present a quantitative analysis of the discriminability of twin fingerprints on a new data set (227 pairs of identical twins and fraternal twins) recently collected from a twin population using both level 1 and level 2 features. Although the patterns of minutiae among twins are more similar than in the general population, the similarity of fingerprints of twins is significantly different from that between genuine prints of the same finger. Twins fingerprints are discriminable with a 1.5%~1.7% higher EER than non-twins. And identical twins can be distinguished by examine fingerprint with a slightly higher error rate than fraternal twins.
Finding the Higgs boson: A status report
International Nuclear Information System (INIS)
Dawson, S.
1995-01-01
The search for the Higgs boson of the minimal Standard Model has been a major focus of experimental high energy physics for some years now. Here, the authors review the current experimental limits and discuss the prospects for finding the Higgs boson at future accelerators, such as LEPII and the LHC. They consider only the Standard Model Higgs boson. Since a null result which definitively excluded a Higgs boson below some mass scale would be extremely important, they emphasize the case where the Higgs boson is much heavier than the relevant collider energy (or where there is no Higgs boson at all). Many of the results given here are a summary of those obtained by the DPF Committee on Long Term Planning
A Historical Profile of the Higgs Boson
Energy Technology Data Exchange (ETDEWEB)
Ellis, John; Gaillard, Mary K.; Nanopoulos, Dimitri V.
2012-01-31
The Higgs boson was postulated in 1964, and phenomenological studies of its possible production and decays started in the early 1970s, followed by studies of its possible productionin e{sup +} e{sup -}, {anti p}p and pp collisions, in particular. Until recently, the most sensitive searches for the Higgs boson were at LEP between 1989 and 2000, which have been complemented bysearches at the Fermilab Tevatron. The LHC has recently entered the hunt, excluding a Higgs boson over a large range of masses and revealing a tantalizing hint in the range 119 to125 GeV, and there are good prospects that the existence or otherwise of the Higgs boson will soon be established. One of the most attractive possibilities is that the Higgs bosonis accompanied by supersymmetry, though composite options have yet to be excluded. This article reviews some of the key historical developments in Higgs physics over the past half-century.
Effective Field Theory with Two Higgs Doublets
Crivellin, Andreas; Procura, Massimiliano
2016-01-01
In this article we extend the effective field theory framework describing new physics effects to the case where the underlying low-energy theory is a Two-Higgs-Doublet model. We derive a complete set of independent operators up to dimension six assuming a $Z_2$-invariant CP-conserving Higgs potential. The effects on Higgs and gauge boson masses, mixing angles in the Higgs sector as well as couplings to fermions and gauge bosons are computed. At variance with the case of a single Higgs doublet, we find that pair production of SM-like Higgses, arising through dimension-six operators, is not fixed by fermion-fermion-Higgs couplings and can therefore be sizable.
Machine Learning wins the Higgs Challenge
Abha Eli Phoboo
2014-01-01
The winner of the four-month-long Higgs Machine Learning Challenge, launched on 12 May, is Gábor Melis from Hungary, followed closely by Tim Salimans from the Netherlands and Pierre Courtiol from France. The challenge explored the potential of advanced machine learning methods to improve the significance of the Higgs discovery. Winners of the Higgs Machine Learning Challenge: Gábor Melis and Tim Salimans (top row), Tianqi Chen and Tong He (bottom row). Participants in the Higgs Machine Learning Challenge were tasked with developing an algorithm to improve the detection of Higgs boson signal events decaying into two tau particles in a sample of simulated ATLAS data* that contains few signal and a majority of non-Higgs boson “background” events. No knowledge of particle physics was required for the challenge but skills in machine learning - the training of computers to recognise patterns in data – were essential. The Challenge, hosted by Ka...
Extended Higgs sectors in radiative neutrino models
Directory of Open Access Journals (Sweden)
Oleg Antipin
2017-05-01
Full Text Available Testable Higgs partners may be sought within the extensions of the SM Higgs sector aimed at generating neutrino masses at the loop level. We study a viability of extended Higgs sectors for two selected models of radiative neutrino masses: a one-loop mass model, providing the Higgs partner within a real triplet scalar representation, and a three-loop mass model, providing it within its two-Higgs-doublet sector. The Higgs sector in the one-loop model may remain stable and perturbative up to the Planck scale, whereas the three-loop model calls for a UV completion around 106 GeV. Additional vector-like lepton and exotic scalar fields, which are required to close one- and three-loop neutrino-mass diagrams, play a decisive role for the testability of the respective models. We constrain the parameter space of these models using LHC bounds on diboson resonances.
Graceful exit from Higgs G-inflation
Energy Technology Data Exchange (ETDEWEB)
Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kobayashi, Tsutomu [Rikkyo Univ., Tokyo (Japan). Dept. of Physics; Kunimitsu, Taro [Tokyo Univ. (Japan). Dept. of Physics; Tokyo Univ. (Japan). Research Center for the Early Universe (RESCEU); Yamaguchi, Masahide [Tokyo Institute of Technology (Japan). Dept. of Physics; Yokoyama, Jun' ichi [Tokyo Univ. (Japan). Research Center for the Early Universe (RESCEU); Tokyo Univ., Chiba (Japan). Kavli Inst. for the Physics and Mathematics of the Universe (Kavli IPMU)
2013-09-15
Higgs G-inflation is a Higgs inflation model with a generalized Galileon term added to the standard model Higgs field, which realizes inflation compatible with observations. Recently, it was claimed that the generalized Galileon term induces instabilities during the oscillation phase, and that the simplest Higgs G-inflation model inevitably suffers from this problem. In this paper, we extend the original Higgs G-inflation Lagrangian to a more general form, namely introducing a higher-order kinetic term and generalizing the form of the Galileon term, so that the Higgs field can oscillate after inflation without encountering instabilities. Moreover, it accommodates a large region of the n{sub s}-r plane, most of which is consistent with current observations, leading us to expect the detection of B-mode polarization in the cosmic microwave background in the near future.
Higgs bosons in supersymmetric models. Pt. 1
International Nuclear Information System (INIS)
Gunion, J.F.
1986-01-01
We describe the properties of Higgs bosons in a class of supersymmetric theories. We consider models in which the low-energy sector contains two weak complex doublets and perhaps one complex gauge-singlet Higgs field. Supersymmetry is assumed to be either softly or spontaneously broken, thereby imposing a number of restrictions on the Higgs boson parameters. We elucidate the Higgs boson masses and present Feynman rules for their couplings to the gauge bosons, fermions and scalars of the theory. We also present Feynman rules for vertices which are related by supersymmetry to the above couplings. Exact analytic expressions are given in two useful limits - one corresponding to the absence of the gauge-singlet Higgs field and the other corresponding to the absence of a supersymmetric Higgs mass term. (orig.)
Cosmological perturbations in the new Higgs inflation
Energy Technology Data Exchange (ETDEWEB)
Germani, Cristiano [Arnold Sommerfeld Center, Ludwig-Maximilians-University, Theresienstr, 37 80333 Muenchen (Germany); Kehagias, Alex, E-mail: cristiano.germani@lmu.de, E-mail: kehagias@central.ntua.gr [Physics Division, National Technical University of Athens, 15780 Zografou Campus, Athens (Greece)
2010-05-01
We study the cosmological perturbations created during the New Higgs inflationary phase. In the New Higgs Inflation, the Higgs boson is kinetically coupled to the Einstein tensor and only three perturbative degrees of freedom, a scalar and two tensorial (gravitational waves), propagate during Inflation. Scalar perturbations are found to match the latest WMAP-7yrs data within Standard Model Higgs parameters. Primordial gravitational waves also, although propagating with superluminal speed, are consistent with present data. Finally, we estimate the values of the parameter of the New Higgs Inflation in relation to the Higgs mass, the spectral index and amplitude of the primordial scalar perturbations showing that the unitarity bound of the theory is not violated.
The flavor of the composite pseudo-goldstone Higgs
International Nuclear Information System (INIS)
Csaki, Csaba; Weiler, Andreas; Falkowski, Adam
2008-01-01
We study the flavor structure of 5D warped models that provide a dual description of a composite pseudo-Goldstone Higgs. We first carefully re-examine the flavor constraints on the mass scale of new physics in the standard Randall-Sundrum-type scenarios, and find that the KK gluon mass should generically be heavier than about 21 TeV. We then compare the flavor structure of the composite Higgs models to those in the RS model. We find new contributions to flavor violation, which while still are suppressed by the RS-GIM mechanism, will enhance the amplitudes of flavor violations. In particular, there is a kinetic mixing term among the SM fields which (although parametrically not enhanced) will make the flavor bounds even more stringent than in RS. This together with the fact that in the pseudo-Goldstone scenario Yukawa couplings are set by a gauge coupling implies the KK gluon mass to be at least about 33 TeV. For both the RS and the composite Higgs models the flavor bounds could be stronger or weaker depending on the assumption on the value of the gluon boundary kinetic term. These strong bounds seem to imply that the fully anarchic approach to flavor in warped extra dimensions is implausible, and there have to be at least some partial flavor symmetries appearing that eliminate part of the sources for flavor violation. We also present complete expressions for the radiatively generated Higgs potential of various 5D implementations of the composite Higgs model, and comment on the 1-5 percent level tuning needed in the top sector to achieve a phenomenologically acceptable vacuum state.
Single Higgs-boson production through γγ scattering within the general 2HDM
International Nuclear Information System (INIS)
Bernal, Nicolas; Lopez-Val, David; Sola, Joan
2009-01-01
The production of a single neutral Higgs boson h through (loop-induced) γγ collisions is explored in the context of the linear colliders within the general Two-Higgs-Doublet Model (2HDM). Two different mechanisms are analyzed: on the one hand, the scattering γγ→h of two real photons in a γγ collider; on the other, the more traditional mechanism of virtual photon fusion, e + e - →e + e - γ*γ*→e + e - +h. Owing to the peculiar properties of the Higgs boson self-interactions within the general 2HDM, we find that the overall production rates can be boosted up significantly, provided the charged Higgs mass is not too heavy. For example, if M H ± ≥100 GeV and, in addition, M h 0 falls in the ballpark of the LEP bound on the SM Higgs mass up to a few hundred GeV, the cross-sections may typically render γγ→h >∼0.1-1 pb and σ(e + e - →e + e - h 0 )≤0.01 pb - in both cases well above the SM prediction. Although for M H ± >300 GeV the rates become virtually insensitive to the Higgs boson self-couplings, a significant tail of non-SM effects produced by the combined contribution of the Yukawa couplings and gauge bosons could still reveal a smoking gun.
Handbook of LHC Higgs Cross Sections: 4. Deciphering the Nature of the Higgs Sector
Energy Technology Data Exchange (ETDEWEB)
de Florian, D. [National Univ. of San Martin, Buenos Aires (Argentina); et al.
2016-10-25
This Report summarizes the results of the activities of the LHC Higgs Cross Section Working Group in the period 2014-2016. The main goal of the working group was to present the state-of-the-art of Higgs physics at the LHC, integrating all new results that have appeared in the last few years. The first part compiles the most up-to-date predictions of Higgs boson production cross sections and decay branching ratios, parton distribution functions, and off-shell Higgs boson production and interference effects. The second part discusses the recent progress in Higgs effective field theory predictions, followed by the third part on pseudo-observables, simplified template cross section and fiducial cross section measurements, which give the baseline framework for Higgs boson property measurements. The fourth part deals with the beyond the Standard Model predictions of various benchmark scenarios of Minimal Supersymmetric Standard Model, extended scalar sector, Next-to-Minimal Supersymmetric Standard Model and exotic Higgs boson decays. This report follows three previous working-group reports: Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002), Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002), and Handbook of LHC Higgs Cross Sections: 3. Higgs properties (CERN-2013-004). The current report serves as the baseline reference for Higgs physics in LHC Run 2 and beyond.
Distinguishing a SM-like MSSM Higgs boson from SM Higgs boson ...
Indian Academy of Sciences (India)
The Higgs sector of the MSSM contains two scalar doublet fields leading to five ... At tree level, the masses and couplings of the MSSM Higgs bosons ..... J F Gunion, H E Haber, G Kane and S Dawson, The Higgs Hunters Guide (Addison-.
Gravitational Waves From a Dark (Twin) Phase Transition
Schwaller, Pedro
2015-01-01
In this work, we show that a large class of models with a composite dark sector undergo a strong first order phase transition in the early universe, which could lead to a detectable gravitational wave signal. We summarise the basic conditions for a strong first order phase transition for SU(N) dark sectors with n_f flavours, calculate the gravitational wave spectrum and show that, depending on the dark confinement scale, it can be detected at eLISA or in pulsar timing array experiments. The gravitational wave signal provides a unique test of the gravitational interactions of a dark sector, and we discuss the complementarity with conventional searches for new dark sectors. The discussion includes Twin Higgs and SIMP models as well as symmetric and asymmetric composite dark matter scenarios.
International Nuclear Information System (INIS)
Yuan, Fuping; Chen, Liu; Jiang, Ping; Wu, Xiaolei
2014-01-01
Atomistic deformation mechanisms of hierarchically nano-twinned (NT) Ag under shock conditions have been investigated using a series of large-scale molecular dynamics simulations. For the same grain size d and the same spacing of primary twins λ 1 , the average flow stress behind the shock front in hierarchically NT Ag first increases with decreasing spacing of secondary twins λ 2 , achieving a maximum at a critical λ 2 , and then drops as λ 2 decreases further. Above the critical λ 2 , the deformation mechanisms are dominated by three type strengthening mechanisms: (a) partial dislocations emitted from grain boundaries (GBs) travel across other boundaries; (b) partial dislocations emitted from twin boundaries (TBs) travel across other TBs; (c) formation of tertiary twins. Below the critical λ 2 , the deformation mechanism are dominated by two softening mechanisms: (a) detwinning of secondary twins; (b) formation of new grains by cross slip of partial dislocations. Moreover, the twin-free nanocrystalline (NC) Ag is found to have lower average flow stress behind the shock front than those of all hierarchically NT Ag samples except the one with the smallest λ 2 of 0.71 nm. No apparent correlation between the spall strength and λ 2 is observed in hierarchically NT Ag, since voids always nucleate at both GBs and boundaries of the primary twins. However, twin-free NC Ag is found to have higher spall strength than hierarchically NT Ag. Voids can only nucleate from GBs for twin-free NC Ag, therefore, twin-free NC Ag has less nucleation sources along the shock direction when compared to hierarchically NT Ag, which requiring higher tensile stress to create spallation. These findings should contribute to the understandings of deformation mechanisms of hierarchically NT fcc metals under extreme deformation conditions
Therapeutic modalities of twin to twin transfusion syndrome
Directory of Open Access Journals (Sweden)
Šulović N.
2015-01-01
Full Text Available Twin to twin transfusion syndrome (TTTTS accounts for approximately 10% of monochorionic twin pregnancies and, if left untreated, is associated with high morbidity and mortality rate. A net transfusion of blood flow from one fetus (donor twin to the other (recipient twin via placental vascular anastomoses has been supposed as the major etiology of TTTTS. The donor twin becomes hypovolemic and oliguria, oligohydramnios, and a variable degree of growth restriction develop, whereas the recipient twin manifests polyuria, polyhydramnios, and hydrops in response to hypervolemia. TTTTS can be treated by either serial amniocentesis or selective fetoscopic laser coagulation of the communicating vessels. The rationale for removal of large volumes of amniotic fluid is to prevent preterm delivery secondary to polyhydramnios and to improve fetal circulation by reducing pressure on the chorionic plate. On the other hand, the goal of laser therapy is to occlude vascular anastomoses, thereby interrupting intertwin blood exchange. Although laser treatment is associated with increased survival rate and reduced neurologic complications, compared with amnioreduction, it requires highly specialized centers, whereas serial amniocentesis has the advantage of being performed worldwide. Therefore, the optimal treatment for pregnancies complicated with TTTTS is still controversial.
Signatures of Higgs dilaton and critical Higgs inflation.
García-Bellido, Juan
2018-03-06
We test the Higgs dilaton inflation model (HDM) using the latest cosmological datasets, including the cosmic microwave background temperature, polarization and lensing data from the Planck satellite (2015), the BICEP and Keck Array experiments, the type Ia supernovae from the JLA catalogue, the baryon acoustic oscillations from CMASS, LOWZ and 6dF, the weak lensing data from the CFHTLenS survey and the matter power spectrum measurements from the latest SDSS data release. We find that the values of all cosmological parameters allowed by the HDM are well within the Planck satellite (2015) constraints. In particular, we determine [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] (at 95.5% c.l.). We also place new stringent constraints on the couplings of the HDM, ξ χ Higgs inflation model, taking into account the running of both the self-coupling λ( μ ) and the non-minimal coupling to gravity ξ ( μ ). We find peaks in the curvature power spectrum at scales corresponding to the critical value μ that re-enter during the radiation era and collapse to form a broad distribution of clustered primordial black holes, which could constitute today the main component of dark matter.This article is part of the Theo Murphy meeting issue 'Higgs cosmology'. © 2018 The Author(s).
International Nuclear Information System (INIS)
Brown, N.
1990-01-01
If the standard Higgs particle is very light (≤50 MeV) then it will be sufficiently long lived that it could decay outside the detectors at LEP. This could give a signal of two final state leptons which are not back-to-back, with missing transverse momentum. We show that with suitable cuts this Higgs signal can be distinguished from backgrounds with a large enough rate that such a light Higgs will either be discovered or completely ruled out. (author)
A Brief Survey of Higgs Bundles
Zúñiga-Rojas, Ronald Alberto
2018-01-01
Considering a compact Riemann surface of genus greater than two, a Higgs~bundle is a pair composed of a holomorphic bundle over the Riemann surface, joint with an auxiliar vector field, so-called Higgs field. This theory started around thirty years ago, with Hitchin's work, when he reduced the self-duality equations from dimension four to dimension two, and so, studied those equations over Riemann surfaces. Hitchin baptized those fields as "Higgs fields" beacuse in the context of physics and ...
Stability of infinite derivative Abelian Higgs models
Ghoshal, Anish; Mazumdar, Anupam; Okada, Nobuchika; Villalba, Desmond
2018-04-01
Motivated by the stringy effects by modifying the local kinetic term of an Abelian Higgs field by the Gaussian kinetic term, we show that the Higgs field does not possess any instability; the Yukawa coupling between the scalar and the fermion, the gauge coupling, and the self interaction of the Higgs yields exponentially suppressed running at high energies, showing that such class of theory never suffers from vacuum instability. We briefly discuss its implications for the early Universe cosmology.
Improved formalism for precision Higgs coupling fits
Barklow, Tim; Fujii, Keisuke; Jung, Sunghoon; Karl, Robert; List, Jenny; Ogawa, Tomohisa; Peskin, Michael E.; Tian, Junping
2018-03-01
Future e+e- colliders give the promise of model-independent determinations of the couplings of the Higgs boson. In this paper, we present an improved formalism for extracting Higgs boson couplings from e+e- data, based on the effective field theory description of corrections to the Standard Model. We apply this formalism to give projections of Higgs coupling accuracies for stages of the International Linear Collider and for other proposed e+e- colliders.
Improved formalism for precision Higgs coupling fits
International Nuclear Information System (INIS)
Barklow, Tim; Peskin, Michael E.; Jung, Sunghoon; Tian, Junping
2017-08-01
Future e + e - colliders give the promise of model-independent determinations of the couplings of the Higgs boson. In this paper, we present an improved formalism for extracting Higgs boson couplings from e + e - data, based on the Effective Field Theory description of corrections to the Standard Model. We apply this formalism to give projections of Higgs coupling accuracies for stages of the International Linear Collider and for other proposed e + e - colliders.
Spontaneous parity violation and minimal Higgs models
International Nuclear Information System (INIS)
Chavez, H.; Martins Simoes, J.A.
2007-01-01
In this paper we present a model for the spontaneous breaking of parity with two Higgs doublets and two neutral Higgs singlets which are even and odd under D-parity. The condition υ R >>υ L can be satisfied without introducing bidoublets, and it is induced by the breaking of D-parity through the vacuum expectation value of the odd Higgs singlet. Examples of left-right symmetric and mirror fermions models in grand unified theories are presented. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Wang, S.J. [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States); Jozaghi, T. [Department of Mechanical Engineering, Texas A& M University, College Station, TX 77843 (United States); Karaman, I., E-mail: ikaraman@tamu.edu [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States); Department of Mechanical Engineering, Texas A& M University, College Station, TX 77843 (United States); Arroyave, R. [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States); Department of Mechanical Engineering, Texas A& M University, College Station, TX 77843 (United States); Chumlyakov, Y.I. [Siberian Physical Technical Institute, Tomsk State University, Tomsk 634050 (Russian Federation)
2017-05-10
We report extensive nano-twin formation in 316 stainless steel (SS) and the evolution of a hierarchical microstructure through the formation of multi-scale twin bundles after uniaxial tension with uniform elongation levels of 20%, 30%, and 40%. Multiscale characterization techniques were employed to reveal the nature of these twins. The twin density increases with the increasing strain level, however, the twin width remains the same, notably reducing the mean free path of dislocations. Concurrently, significant work hardening is observed during subsequent deformation. The deformation-induced nano-twins are thermally stable up to ~800 °C, shown by both interrupted and in-situ transmission electron microscopy experiments, above which the recrystallization takes place in the vicinity of the twins. Such favorable thermal stability of the twins in nano-twin strengthened 316 SS offers a promising approach for microstructurally engineering these materials for potential applications at elevated temperatures. The related strengthening mechanisms are discussed in the light of the mean free path of dislocations and the dislocation interactions with twin boundaries.
Gauge boson mass without a Higgs field: a simple model
International Nuclear Information System (INIS)
Nicholson, A.F.; Kennedy, D.C.
1997-02-01
A simple, anomaly-free chiral gauge theory can be perturbatively quantized and renormalized in such a way as to generate fermion and gauge boson masses. This development exploits certain freedoms inherent in choosing the unperturbed Lagrangian and in the renormalization procedure. Apart from its intrinsic interest, such a mechanism might be employed in electroweak gauge theory to generate fermion and gauge boson masses without a Higgs sector. 38 refs
Standard model fermion hierarchies with multiple Higgs doublets
International Nuclear Information System (INIS)
Solaguren-Beascoa Negre, Ana
2016-01-01
The hierarchies between the Standard Model (SM) fermion masses and mixing angles and the origin of neutrino masses are two of the biggest mysteries in particle physics. We extend the SM with new Higgs doublets to solve these issues. The lightest fermion masses and the mixing angles are generated through radiative effects, correctly reproducing the hierarchy pattern. Neutrino masses are generated in the see-saw mechanism.
Higgs decays and brane gravi-vectors
International Nuclear Information System (INIS)
Clark, T. E.; Liu Boyang; Love, S. T.; Xiong, C.; Veldhuis, T. ter
2008-01-01
Higgs boson decays in flexible brane world models with stable, massive gravi-vectors are considered. Such vectors couple bilinearly to the standard model fields through either the standard model energy-momentum tensor, the weak hypercharge field strength, or the Higgs scalar. The role of the coupling involving the extrinsic curvature is highlighted. It is found that within the presently allowed parameter space, the decay rate of the Higgs into two gravi-vectors (which would appear as an invisible Higgs decay) can be comparable to the rate for any of the standard model decay modes.
Rayan, Steven
2010-01-01
Co-Higgs bundles are Higgs bundles in the sense of Simpson, but with Higgs fields that take values in the tangent bundle instead of the cotangent bundle. Given a vector bundle on P^1, we find necessary and sufficient conditions on its Grothendieck splitting for it to admit a stable Higgs field. We characterize the rank-2, odd-degree moduli space as a universal elliptic curve with a globally-defined equation. For ranks r=2,3,4, we explicitly verify the conjectural Betti numbers emerging from t...
New Physics and novel Higgs signals
International Nuclear Information System (INIS)
Diaz-Cruz, J. Lorenzo
2003-01-01
We review some of the results of our recent work dealing with the novel type of Higgs signals that arise when one considers extensions of the standard model. We discuss first possible deviations on the Higgs couplings due to heavy particles, in the context of the MSSM and with large extra-dimensions. Then, we present several models where it is possible to induce flavor violating Higgs couplings, and probe them at future hadron colliders through the LFV Higgs decay h → τμ or with rare top decays
Strongly interacting Higgs sector without technicolor
International Nuclear Information System (INIS)
Liu Chuan; Kuti, J.
1994-12-01
Simulation results are presented on Higgs mass calculations in the spontaneously broken phase of the Higgs sector in the minimal Standard Model with a higher derviative regulator. A heavy Higgs particle is found in the TeV mass range in the presence of a complex conjugate ghost pair at higher energies. The ghost pair evades easy experimental detection. As a finite and unitary theory in the continuum, this model serves as an explicit and simple example of a strong interacting Higgs sector without technicolor. (orig.)
Light Higgs bosons in phenomenological NMSSM
Energy Technology Data Exchange (ETDEWEB)
Mahmoudi, F. [CERN, Geneva (Switzerland); Clermont Univ., CNRS/IN2P3, LPC, Clermont-Ferrand (France); Rathsman, J. [Uppsala Univ. (Sweden). High-Energy Physics; Lund Univ. (Sweden). Theoretical High Energy Physics; Staal, O. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Zeune, L. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Goettingen Univ. (Germany). II. Physikalisches Inst.
2010-12-15
We consider scenarios in the next-to-minimal supersymmetric model (NMSSM) where the CP-odd and charged Higgs bosons are very light. As we demonstrate, these can be obtained as simple deformations of existing phenomenological MSSM benchmarks scenarios with parameters defined at the weak scale. This offers a direct and meaningful comparison to the MSSM case. Applying a wide set of up-to-date constraints from both high-energy collider and flavour physics, the Higgs boson masses and couplings are studied in viable parts of parameter space. The LHC phenomenology of the light Higgs scenario for neutral and charged Higgs boson searches is discussed. (orig.)
Light Higgs bosons in phenomenological NMSSM
International Nuclear Information System (INIS)
Mahmoudi, F.; Rathsman, J.; Zeune, L.; Goettingen Univ.
2010-12-01
We consider scenarios in the next-to-minimal supersymmetric model (NMSSM) where the CP-odd and charged Higgs bosons are very light. As we demonstrate, these can be obtained as simple deformations of existing phenomenological MSSM benchmarks scenarios with parameters defined at the weak scale. This offers a direct and meaningful comparison to the MSSM case. Applying a wide set of up-to-date constraints from both high-energy collider and flavour physics, the Higgs boson masses and couplings are studied in viable parts of parameter space. The LHC phenomenology of the light Higgs scenario for neutral and charged Higgs boson searches is discussed. (orig.)
Antenatal management of twin-twin transfusion syndrome and twin anemia-polycythemia sequence.
Slaghekke, Femke; Zhao, Depeng P; Middeldorp, Johanna M; Klumper, Frans J; Haak, Monique C; Oepkes, Dick; Lopriore, Enrico
2016-08-01
Twin-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS) are severe complications in monochorionic twin pregnancies associated with high mortality and morbidity risk if left untreated. Both diseases result from imbalanced inter-twin blood transfusion through placental vascular anastomoses. This review focuses on the differences in antenatal management between TTTS and TAPS. Expert commentary: The optimal management for TTTS is fetoscopic laser coagulation of the vascular anastomoses, preferably using the Solomon technique in which the whole vascular equator is coagulated. The Solomon technique is associated with a reduction of residual anastomosis and a reduction in post-operative complications. The optimal management for TAPS is not clear and includes expectant management, intra-uterine transfusion with or without partial exchange transfusion and fetoscopic laser surgery.
Numerical simulation of Higgs models
International Nuclear Information System (INIS)
Jaster, A.
1995-10-01
The SU(2) Higgs and the Schwinger model on the lattice were analysed. Numerical simulations of the SU(2) Higgs model were performed to study the finite temperature electroweak phase transition. With the help of the multicanonical method the distribution of an order parameter at the phase transition point was measured. This was used to obtain the order of the phase transition and the value of the interface tension with the histogram method. Numerical simulations were also performed at zero temperature to perform renormalization. The measured values for the Wilson loops were used to determine the static potential and from this the renormalized gauge coupling. The Schwinger model was simulated at different gauge couplings to analyse the properties of the Kaplan-Shamir fermions. The prediction that the mass parameter gets only multiplicative renormalization was tested and verified. (orig.)
Sharma, Vivek
2016-01-01
The recent observation of the Higgs boson has been hailed as the scientific discovery of the century and led to the 2013 Nobel Prize in physics. This book describes the detailed science behind the decades-long search for this elusive particle at the Large Electron Positron Collider at CERN and at the Tevatron at Fermilab and its subsequent discovery and characterization at the Large Hadron Collider at CERN. Written by physicists who played leading roles in this epic search and discovery, this book is an authoritative and pedagogical exposition of the portrait of the Higgs boson that has emerged from a large number of experimental measurements. As the first of its kind, this book should be of interest to graduate students and researchers in particle physics.
LHCb Exotica and Higgs searches
Lucchesi, Donatella
2016-01-01
The unique phase space coverage and features of the LHCb detector at the LHC makes it an ideal environment to probe complementary New Physics parameter regions. In particular, recently developed jet tagging algorithms are ideal for searches involving $b$ and $c$ jets. This poster will review different jet-related exotica searches together with the efforts in the search for a Higgs boson decaying to a pair of heavy quarks.
Inflation and the Higgs Scalar
Energy Technology Data Exchange (ETDEWEB)
Green, Dan [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
2014-12-05
This note makes a self-contained exposition of the basic facts of big bang cosmology as they relate to inflation. The fundamental problems with that model are then explored. A simple scalar model of inflation is evaluated which provides the solution of those problems and makes predictions which will soon be definitively tested. The possibility that the recently discovered fundamental Higgs scalar field drives inflation is explored.
Barbieri, Riccardo; Kannike, Kristjan; Sala, Filippo; Tesi, Andrea
2013-01-01
Now that one has been found, the search for signs of more scalars is a primary task of current and future experiments. In the motivated hypothesis that the extra Higgs bosons of the next-to-minimal supersymmetric Standard Model (NMSSM) be the lightest new particles around, we outline a possible overall strategy to search for signs of the CP-even states. This work complements Ref. arXiv:1304.3670.
Number theory meets Higgs physics
CERN. Geneva
2014-01-01
Inspired by results from modern number theory and algebraic geometry, a lot of progress has recently been made regarding the computation of multi-loop integrals and scattering amplitudes. I will discuss various new approaches to the computation of loop integrals, and illustrate them on the first computation of a quantity at N3LO in perturbative QCD, the soft-virtual part of the inclusive Higgs-boson cross section in gluon fusion at N3LO.
ON THE OBSERVATION AND SIMULATION OF SOLAR CORONAL TWIN JETS
Energy Technology Data Exchange (ETDEWEB)
Liu, Jiajia; Wang, Yuming; Zhang, Quanhao [CAS Key Laboratory of Geospace Environment, School of Earth and Space Sciences, University of Science and Technology of China, NO. 96, Jinzhai Road, Hefei, Anhui 230026 (China); Fang, Fang [Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, 1234 Innovation Drive, Boulder, CO 80303 (United States); McIntosh, Scott W.; Fan, Yuhong [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States)
2016-02-01
We present the first observation, analysis, and modeling of solar coronal twin jets, which occurred after a preceding jet. Detailed analysis on the kinetics of the preceding jet reveals its blowout-jet nature, which resembles the one studied in Liu et al. However, the erupting process and kinetics of the twin jets appear to be different from the preceding one. Lacking detailed information on the magnetic fields in the twin jet region, we instead use a numerical simulation using a three-dimensional (3D) MHD model as described in Fang et al., and find that in the simulation a pair of twin jets form due to reconnection between the ambient open fields and a highly twisted sigmoidal magnetic flux, which is the outcome of the further evolution of the magnetic fields following the preceding blowout jet. Based on the similarity between the synthesized and observed emission, we propose this mechanism as a possible explanation for the observed twin jets. Combining our observation and simulation, we suggest that with continuous energy transport from the subsurface convection zone into the corona, solar coronal twin jets could be generated in the same fashion addressed above.
On the Observation and Simulation of Solar Coronal Twin Jets
Liu, Jiajia; Fang, Fang; Wang, Yuming; McIntosh, Scott W.; Fan, Yuhong; Zhang, Quanhao
2016-02-01
We present the first observation, analysis, and modeling of solar coronal twin jets, which occurred after a preceding jet. Detailed analysis on the kinetics of the preceding jet reveals its blowout-jet nature, which resembles the one studied in Liu et al. However, the erupting process and kinetics of the twin jets appear to be different from the preceding one. Lacking detailed information on the magnetic fields in the twin jet region, we instead use a numerical simulation using a three-dimensional (3D) MHD model as described in Fang et al., and find that in the simulation a pair of twin jets form due to reconnection between the ambient open fields and a highly twisted sigmoidal magnetic flux, which is the outcome of the further evolution of the magnetic fields following the preceding blowout jet. Based on the similarity between the synthesized and observed emission, we propose this mechanism as a possible explanation for the observed twin jets. Combining our observation and simulation, we suggest that with continuous energy transport from the subsurface convection zone into the corona, solar coronal twin jets could be generated in the same fashion addressed above.
Exploring holographic Composite Higgs models
Energy Technology Data Exchange (ETDEWEB)
Croon, Djuna [Department of Physics and Astronomy, University of Sussex,BN1 9QH Brighton (United Kingdom); Perimeter Institute for Theoretical Physics,Waterloo, ON (Canada); Dillon, Barry M.; Huber, Stephan J.; Sanz, Veronica [Department of Physics and Astronomy, University of Sussex,BN1 9QH Brighton (United Kingdom)
2016-07-13
Simple Composite Higgs models predict new vector-like fermions not too far from the electroweak scale, yet LHC limits are now sensitive to the TeV scale. Motivated by this tension, we explore the holographic dual of the minimal model, MCHM{sub 5}, to try and alleviate this tension without increasing the fine-tuning in the Higgs potential. Interestingly, we find that lowering the UV cutoff in the 5D picture allows for heavier top partners and less fine-tuning. In the 4D dual this corresponds to increasing the number of “colours” N, thus increasing the decay constant of the Goldstone Higgs. This is essentially a ‘Little Randall-Sundrum Model’, which are known to reduce some flavour and electroweak constraints. Furthermore, in anticipation of the ongoing efforts at the LHC to put bounds on the top Yukawa, we demonstrate that deviations from the SM can be suppressed or enhanced with respect to what is expected from mere symmetry arguments in 4D. We conclude that the 5D holographic realisation of the MCHM{sub 5} with a small UV cutoff is not in tension with the current experimental data.
Espinosa, J.R.; Muhlleitner, M.; Trott, M.
2012-01-01
The 8 TeV LHC Higgs search data just released indicates the existence of a scalar resonance with mass ~ 125 GeV. We examine the implications of the data reported by ATLAS, CMS and the Tevatron collaborations on understanding the properties of this scalar by performing joint fits on its couplings to other Standard Model particles. We discuss and characterize to what degree this resonance has the properties of the Standard Model (SM) Higgs, and consider what implications can be extracted for New Physics in a (mostly) model-independent fashion. We find that, if the Higgs couplings to fermions and weak vector bosons are allowed to differ from their standard values, the SM is ~ 2 sigma from the best fit point to current data. Fitting to a possible invisible decay branching ratio, we find BR_{inv} = 0.05\\pm 0.32\\ (95% C.L.) We also discuss and develop some ways of using the data in order to bound or rule out models which modify significantly the properties of this scalar resonance and apply these techniques to the ...
2008-01-01
Like his eponymous particle, Peter Higgs can be elusive. However, for the momentous occasion of the Open Days there was a chance, if you were lucky, to catch a glimpse of him. Peter Higgs marvels at the enormity of the ATLAS experiment. Taking a closer look at CMS.Visiting CERN for the first time in more than 20 years, Peter Higgs has become something of a celebrity in the world of particle physics. During his visit he showed genuine amazement at the sight of the LHC and its experiments. On seeing CMS he said, "It’s very impressive, very dramatic. I’d seen pictures of course, but they can’t compare." Surrounded for most of his stay by an entourage of physicists, the notoriously modest scientist laughs at the almost mythical quality his boson has taken on. For him though, it is just one of many aspects of physics that the CMS and ATLAS experiments can shine a light on. Besides finding ...
The nature of pseudo-twinning modes on the basis of a twin classification scheme
International Nuclear Information System (INIS)
Singh, Jung B.; Sundararaman, M.; Krishnan, M.
2011-01-01
Pseudo-twins can form in ordered structures under high stress conditions. These twins are defined by lattice sites that are at twin positions but are incorrectly occupied by different species of atoms. The present note discusses if it is possible to further classify pseudo-twins into different modes based on the nature of associated twinning elements.
Twins and Kindergarten Separation: Divergent Beliefs of Principals, Teachers, Parents, and Twins
Gordon, Lynn Melby
2015-01-01
Should principals enforce mandatory separation of twins in kindergarten? Do school separation beliefs of principals differ from those of teachers, parents of twins, and twins themselves? This survey questioned 131 elementary principals, 54 kindergarten teachers, 201 parents of twins, and 112 twins. A majority of principals (71%) believed that…
The classical twin study and beyond
Boomsma, D.I.; Busjahn, A.; Peltonen, L.
2002-01-01
Twin studies have been a valuable source of information about the genetic basis of complex traits. To maximize the potential of twin studies, large, worldwide registers of data on twins and their relatives have been established. Here, we provide an overview of the current resources for twin
Monochorionic twin pregnancies: a systematic approach to ...
African Journals Online (AJOL)
Complications unique to these pregnancies include Twin-To-Twin Transfusion Syndrome (TTTS), Twin Polycythaemia Anaemia Sequence (TAPS), Selective Intrauterine Growth Restriction (sIUGR) and death of the co-twin. Adhering to a systematic and objective approach of management, can lead to early recognition and ...
Tuning the thermal conductivity of silicon carbide by twin boundary: a molecular dynamics study
International Nuclear Information System (INIS)
Liu, Qunfeng; Wang, Liang; Shen, Shengping; Luo, Hao
2017-01-01
Silicon carbide (SiC) is a semiconductor with excellent mechanical and physical properties. We study the thermal transport in SiC by using non-equilibrium molecular dynamics simulations. The work is focused on the effects of twin boundaries and temperature on the thermal conductivity of 3C-SiC. We find that compared to perfect SiC, twinned SiC has a markedly reduced thermal conductivity when the twin boundary spacing is less than 100 nm. The Si–Si twin boundary is more effective to phonon scattering than the C–C twin boundary. We also find that the phonon scattering effect of twin boundary decreases with increasing temperature. Our findings provide insights into the thermal management of SiC-based electronic devices and thermoelectric applications. (paper)
Atomistic simulation study of deformation twinning of nanocrystalline body-centered cubic Mo
Energy Technology Data Exchange (ETDEWEB)
Tian, Xiaofeng [The College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu (China); Li, Dan, E-mail: txf8378@163.com [The College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu (China); Yu, You [College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu (China); You, Zhen Jiang [Australian School of Petroleum, University of Adelaide, SA 5005 (Australia); Li, Tongye [The National Key Laboratory of Nuclear Fuel and Materials, Nuclear Power Institute of China, Chengdu (China); Ge, Liangquan [The College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu (China)
2017-04-06
Deformation twinning of nanocrystalline body-centered cubic Mo was studied using molecular dynamics simulations, and the effects of grain sizes and temperatures on the deformation were evaluated. With small grain size, grain rotation accompanying grain growth was found to play important role in nanocrystalline Mo during tensile deformation. Additionally, grain rotation and the deformation controlled by GB-mediated processes induce to the difficulty of creating crack. Twin was formed by successive emission of twinning partials from grain boundaries in small grain size systems. However, the twin mechanisms of GB splitting and overlapping of two extended dislocations were also found in larger size grain. Twin induced crack tips were observed in our simulation, and this confirmed the results of previous molecular dynamics simulations. At higher temperatures, GB activities can be thermally activated, resulting in suppression of twinning tendency and improvement of ductility of nanocrystalline Mo.
Twinning behaviors of a rolled AZ31 magnesium alloy under multidirectional loading
Energy Technology Data Exchange (ETDEWEB)
Hou, Dewen [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Liu, Tianmo, E-mail: tmliu@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Luo, Longjing [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Lu, Liwei [College of Mechanical and Electrical Engineering, Hunan University of Science and Technology, Xiangtan 411201, Hunan (China); Chen, Huicong; Shi, Dongfeng [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China)
2017-02-15
The microstructure and texture evolution of an AZ31 magnesium rolled sheet during quasi-static compression at strain rates of 10{sup −3} s{sup −1} has been investigated by in situ electron backscattered diffraction. The influence of the initial and pre-deformed texture on the predominant deformation mechanisms during compression has been examined. It has been found that extensive grain reorientation due to (10 − 12) tensile twinning appeared when compressed along transverse direction. Tensile twin variants were observed under this loading condition, and different variants will cause an effect to the following deformation. Several twinning modes occurred with continuative loading along rolling direction. - Highlights: •Twinning behaviors were investigated through in situ multidirectional compressive tests. •Deformation behavior was affected by the twin variants. •Four types of twinning behaviors were observed during deformation process.
Generalized planar fault energies and twinning in Cu-Al alloys
Kibey, S.; Liu, J. B.; Johnson, D. D.; Sehitoglu, H.
2006-11-01
We report ab initio density functional theory calculations of generalized planar fault energies of fcc Cu -xAl (x =0, 5.0, and 8.3at.%) alloys. We investigate the effects of substitutional solute Al on the unstable intrinsic γus and twin γut stacking fault energies (SFEs). Our results reveal an increased tendency of Cu-Al to deform preferentially by twinning with increasing Al content, consistent with experiment. We attribute this mechanical behavior to appreciable lowering of the twinning barrier γut, along with the stable intrinsic and twin SFEs.
Measurement of oxygen disorder and nano-twin microstructure associated with columnar defects in YBCO
International Nuclear Information System (INIS)
Yan, Y.
1998-01-01
Studies of defects generated by high energy (>1 GeV) heavy ion irradiation in high-Tc superconductors have been performed by transmission electron microscopy (TEM). Our study shows that high dose irradiation leads to the formation of nano-twins, by which the columnar defects are connected. An analysis of the local Fourier components of the image intensity in [001] lattice images indicates that these new ''twin'' boundaries are much more diffuse than pre-existing twin boundaries in YBCO. The mechanism of the formation of nano-twin boundaries on {110} planes and their possible relation to superconducting properties are discussed
Peak effect in twinned superconductors
International Nuclear Information System (INIS)
Larkin, A.I.; Marchetti, M.C.; Vinokur, V.M.
1995-01-01
A sharp maximum in the critical current J c as a function of temperature just below the melting point of the Abrikosov flux lattice has recently been observed in both low- and high-temperature superconductors. This peak effect is strongest in twinned crystals for fields aligned with the twin planes. We propose that this peak signals the breakdown of the collective pinning regime and the crossover to strong pinning of single vortices on the twin boundaries. This crossover is very sharp and can account for the steep drop of the differential resistivity observed in experiments. copyright 1995 The American Physical Society
Difficult scenarios for NMSSM Higgs discovery at the LHC
International Nuclear Information System (INIS)
Ellwanger, Ulrich; Gunion, John F.; Hugonie, Cyril
2005-01-01
We identify scenarios not ruled out by LEP data in which NMSSM Higgs detection at the LHC will be particularly challenging. We first review the 'no-lose' theorem for Higgs discovery at the LHC that applies if Higgs bosons do not decay to other Higgs bosons - namely, with L = 300 fb -1 , there is always one or more 'standard' Higgs detection channel with at least a 5σ signal. However, we provide examples of no-Higgs-to-Higgs cases for which all the standard signals are no larger than 7σ implying that if the available L is smaller or the simulations performed by ATLAS and CMS turn out to be overly optimistic, all standard Higgs signals could fall below 5σ even in the no-Higgs-to-Higgs part of NMSSM parameter space. In the vast bulk of NMSSM parameter space, there will be Higgs-to-Higgs decays. We show that when such decays are present it is possible for all the standard detection channels to have very small significance. In most such cases, the only strongly produced Higgs boson is one with fairly SM-like couplings that decays to two lighter Higgs bosons (either a pair of the lightest CP-even Higgs bosons, or, in the largest part of parameter space, a pair of the lightest CP-odd Higgs bosons). A number of representative bench-mark scenarios of this type are delineated in detail and implications for Higgs discovery at various colliders are discussed
Proliferation of twinning in hexagonal close-packed metals: Application to magnesium
Sun, D.; Ponga, M.; Bhattacharya, K.; Ortiz, M.
2018-03-01
Plastic deformation of metallic alloys usually takes place through slip, but occasionally involves twinning. In particular, twinning is important in hexagonal close packed (HCP) materials where the easy slip systems are insufficient to accommodate arbitrary deformations. While deformation by slip mechanisms is reasonably well understood, comparatively less is known about deformation by twinning. Indeed, the identification of relevant twinning modes remains an art. In this paper, we develop a framework combining a fundamental kinematic definition of twins with large-scale atomistic calculations to predict twinning modes of crystalline materials. We apply this framework to magnesium where there are two accepted twin modes, tension and compression, but a number of anomalous observations. Remarkably, our framework shows that there is a very large number of twinning modes that are important in magnesium. Thus, in contrast to the traditional view that plastic deformation is kinematically partitioned between a few modes, our results suggest that deformation in HCP materials is the result of an energetic and kinetic competition between numerous possibilities. Consequently, our findings suggest that the commonly used models of deformation need to be extended in order to take into account a broader and richer variety of twin modes, which, in turn, opens up new avenues for improving the mechanical properties.
Status of the charged Higgs boson in two Higgs doublet models
Arbey, A.; Mahmoudi, F.; Stål, O.; Stefaniak, T.
2018-03-01
The existence of charged Higgs boson(s) is inevitable in models with two (or more) Higgs doublets. Hence, their discovery would constitute unambiguous evidence for new physics beyond the Standard Model (SM). Taking into account all relevant results from direct charged and neutral Higgs boson searches at LEP and the LHC, as well as the most recent constraints from flavour physics, we present a detailed analysis of the current phenomenological status of the charged Higgs sector in a variety of well-motivated two Higgs doublet models (2HDMs). We find that charged Higgs bosons as light as 75 GeV can still be compatible with the combined data, although this implies severely suppressed charged Higgs couplings to all fermions. In more popular models, e.g. the 2HDM of Type II, we find that flavour physics observables impose a combined lower limit on the charged Higgs mass of M_{H^± } ≳ 600 GeV - independent of tan β - which increases to M_{H^± } ≳ 650 GeV for tan β < 1. We furthermore find that in certain scenarios, the signature of a charged Higgs boson decaying into a lighter neutral Higgs boson and a W boson provides a promising experimental avenue that would greatly complement the existing LHC search programme for charged Higgs boson(s).
Trilinear Higgs couplings in the two Higgs doublet model with CP violation
International Nuclear Information System (INIS)
Osland, Per; Pandita, P. N.; Selbuz, Levent
2008-01-01
We carry out a detailed analysis of the general two Higgs doublet model with CP violation. We describe two different parametrizations of this model, and then study the Higgs boson masses and the trilinear Higgs couplings for these two parametrizations. Within a rather general model, we find that the trilinear Higgs couplings have a significant dependence on the details of the model, even when the lightest Higgs boson mass is taken to be a fixed parameter. We include radiative corrections in the one-loop effective potential approximation in our analysis of the Higgs boson masses and the Higgs trilinear couplings. The one-loop corrections to the trilinear couplings of the two Higgs doublet model also depend significantly on the details of the model, and can be rather large. We study quantitatively the trilinear Higgs couplings, and show that these couplings are typically several times larger than the corresponding standard model trilinear Higgs coupling in some regions of the parameter space. We also briefly discuss the decoupling limit of the two Higgs doublet model.
Status of the charged Higgs boson in two Higgs doublet models
International Nuclear Information System (INIS)
Arbey, A.; Mahmoudi, F.; Stefaniak, T.; Staal, O.
2018-01-01
The existence of charged Higgs boson(s) is inevitable in models with two (or more) Higgs doublets. Hence, their discovery would constitute unambiguous evidence for new physics beyond the Standard Model (SM). Taking into account all relevant results from direct charged and neutral Higgs boson searches at LEP and the LHC, as well as the most recent constraints from flavour physics, we present a detailed analysis of the current phenomenological status of the charged Higgs sector in a variety of well-motivated two Higgs doublet models (2HDMs). We find that charged Higgs bosons as light as 75 GeV can still be compatible with the combined data, although this implies severely suppressed charged Higgs couplings to all fermions. In more popular models, e.g. the 2HDM of Type II, we find that flavour physics observables impose a combined lower limit on the charged Higgs mass of M H ± > or similar 600 GeV - independent of tan β - which increases to M H ± > or similar 650 GeV for tan β < 1. We furthermore find that in certain scenarios, the signature of a charged Higgs boson decaying into a lighter neutral Higgs boson and a W boson provides a promising experimental avenue that would greatly complement the existing LHC search programme for charged Higgs boson(s). (orig.)
Recent developments in HiggsBounds and a preview of HiggsSignals
Energy Technology Data Exchange (ETDEWEB)
Bechtle, Philip; Stefaniak, Tim; Williams, Karina [Bonn Univ. (Germany). Physikalisches Inst.; Heinemeyer, Sven [Instituto de Fisica de Cantabria (CSIC-UC), Santander (Spain); Staal, Oscar [Stockholm Univ. (Sweden). Dept. of Physics; Weiglein, Georg [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Brein, Oliver
2013-01-15
We report on recent developments in the public computer code HiggsBounds, which confronts arbitrary Higgs sector predictions with 95% C.L. exclusion limits from Higgs searches at the LEP, Tevatron and LHC experiments. We discuss in detail the performance of the Standard Model (SM) likeness test as implemented in the latest version HiggsBounds-3.8.0, whose outcome decides whether a search for a SM Higgs boson can be applied to a model beyond the SM. Furthermore, we give a preview of features in the upcoming version HiggsBounds-4.0.0 and the new program HiggsSignals, which performs a {chi}{sup 2} test of Higgs sector predictions against the signal rate and mass measurements from Higgs boson analyses at the Tevatron and LHC. This is illustrated with an example where the heavier CP-even Higgs boson of the Minimal Supersymmetric Standard Model (MSSM) is considered as an explanation of the LHC Higgs signal at {approx_equal} 126 GeV.
Precision predictions for Higgs differential distributions at the LHC
Energy Technology Data Exchange (ETDEWEB)
Ebert, Markus
2017-08-15
After the discovery of a Standard-Model-like Higgs boson at the LHC a central aspect of the LHC physics program is to study the Higgs boson's couplings to Standard Model particles in detail in order to elucidate the nature of the Higgs mechanism and to search for hints of physics beyond the Standard Model. This requires precise theory predictions for both inclusive and differential Higgs cross sections. In this thesis we focus on the application of resummation techniques in the framework of Soft-Collinear Effective Theory (SCET) to obtain accurate predictions with reliable theory uncertainties for various observables. We first consider transverse momentum distributions, where the resummation of large logarithms in momentum (or distribution) space has been a long-standing open question. We show that its two-dimensional nature leads to additional difficulties not observed in one-dimensional observables such as thrust, and solving the associated renormalization group equations (RGEs) in momentum space thus requires a very careful scale setting. This is achieved using distributional scale setting, a new technique to solve differential equations such as RGEs directly in distribution space, as it allows one to treat logarithmic plus distributions like ordinary logarithms. We show that the momentum space solution fundamentally differs from the standard resummation in Fourier space by different boundary terms to all orders in perturbation theory and hence provides an interesting and complementary approach to obtain new insight into the all-order perturbative and nonperturbative structure of transverse momentum distributions. Our work lays the ground for a detailed numerical study of the momentum space resummation. We then show that in the case of a discovery of a new heavy color-singlet resonance such as a heavy Higgs boson, one can reliably and model-independently infer its production mechanism by dividing the data into two mutually exclusive jet bins. The method is
Neutral Supersymmetric Higgs Boson Searches
Energy Technology Data Exchange (ETDEWEB)
Robinson, Stephen Luke [Imperial College, London (United Kingdom)
2008-07-01
In some Supersymmetric extensions of the Standard Model, including the Minimal Supersymmetric Standard Model (MSSM), the coupling of Higgs bosons to b-quarks is enhanced. This enhancement makes the associated production of the Higgs with b-quarks an interesting search channel for the Higgs and Supersymmetry at D0. The identification of b-quarks, both online and offline, is essential to this search effort. This thesis describes the author's involvement in the development of both types of b-tagging and in the application of these techniques to the MSSM Higgs search. Work was carried out on the Level-3 trigger b-tagging algorithms. The impact parameter (IP) b-tagger was retuned and the effects of increased instantaneous luminosity on the tagger were studied. An extension of the IP-tagger to use the z-tracking information was developed. A new b-tagger using secondary vertices was developed and commissioned. A tool was developed to allow the use of large multi-run samples for trigger studies involving b-quarks. Offline, a neural network (NN) b-tagger was trained combining the existing offline lifetime based b-tagging tools. The efficiency and fake rate of the NN b-tagger were measured in data and MC. This b-tagger was internally reviewed and certified by the Collaboration and now provides the official b-tagging for all analyses using the Run IIa dataset at D0. A search was performed for neutral MSSM Higgs bosons decaying to a b{bar b} pair and produced in association with one or more b-quarks. Limits are set on the cross-section times the branching ratio for such a process. The limits were interpreted in various MSSM scenarios. This analysis uses the NN b-tagger and was the first to use this tool. The analysis also relies on triggers using the Level-3 IP b-tagging tool described previously. A likelihood discriminant was used to improve the analysis and a neural network was developed to cross-check this technique. The result of the analysis has been submitted to PRL
Can we distinguish an MSSM Higgs from a SM Higgs at a linear collider?
International Nuclear Information System (INIS)
Logan, Heather E.
2001-01-01
We study the prospects for distinguishing the CP-even Higgs boson of the minimal supersymmetric extension of the Standard Model (MSSM) from the Standard Model (SM) Higgs boson by measuring its branching ratios at an e + e - linear collider. The regions of the M A -tan β plane in which an MSSM Higgs boson can be distinguished from the SM Higgs boson depend strongly upon the supersymmetric parameters that enter the radiative corrections to the Higgs mass matrix and the Higgs couplings to fermions. In some regions of parameter space it is possible to extract the supersymmetric correction to the relation between the b quark mass and its Yukawa coupling from Higgs branching ratio measurements
Can the 125 GeV Higgs be the Little Higgs?
Energy Technology Data Exchange (ETDEWEB)
Reuter, J.; Tonini, M
2012-12-15
After the discovery of the Higgs-like boson by the LHC 2012 it is the most important task to check whether this new particle is the Standard Model Higgs boson or something else. In this paper, we study whether the 125 GeV boson could be the pseudo- Goldstone boson of Little Higgs models. We derive limits on the parameter space of several Little Higgs models (simple group and product group models, with and without T-parity), both from the experimental data from ATLAS and CMS about the different Higgs discovery channel and the electroweak precision observables. We perform a fit of several Little Higgs models to all electroweak parameters from measurements of SLC, LEP, Tevatron, and LHC. For the Higgs searches, we include all available data from the summer conferences 2012 as well as the update from December 2012.
Carena, M S; Herfurth, F; Ames, F; Audi, G; Beck, D; Blaum, K; Bollen, G; Kellerbauer, A G; Kluge, H J; Kuckein, M; Lunney, M D; Moore, R B; Oinonen, M; Rodríguez, D; Sauvan, E; Scheidenberger, C
2003-01-01
Precision electroweak data presently-favors a weakly-coupled Higgs sector as the mechanism responsible for electroweak symmetry breaking. Low-energy supersymmetry provides a natural framework for weakly-coupled elementary scalars. In this review, we summarize the theoretical properties of the Standard Model (SM) Higgs boson and the Higgs sector of the minimal super-symmetric extension of the Standard Model (MSSM). We then survey the phenomenology of the SM and MSSM Higgs bosons at the Tevatron, LHC and a future e**+e**- linear collider. We focus on the Higgs discovery potential of present and future colliders and stress the importance of precision measurements of Higgs boson properties. 459 Refs.31 The Penning trap mass spectrometer ISOLTRAP is a facility for high- precision mass measurements of short-lived radioactive nuclei installed at ISOLDE/CERN in Geneva. More than 200 masses have been measured with relative uncertainties of 1 multiplied by 10**-**7 or even close to 1 multiplied by 10**-**8 in special c...
Study of WW decay of a Higgs boson with the ALEPH and CMS detectors
AUTHOR|(CDS)2068184; Lemaitre, Vincent
The Standard Model is a mathematical description of the very nature of elementary particles and their interactions, now seen as relativistic quantum fields. A key feature of the theory is the Brout-Englert-Higgs mechanism, responsible for the spontaneous symmetry breaking of the underlying gauge symmetry, and which implies the existence of a neutral Higgs particle. Searches for the Higgs boson were conducted at the Large Electron Positron collider until 2000 and are still ongoing at the Tevatron collider, but the particle has not been not observed. In order to better constrain models with an exotic electroweak symmetry breaking sector, a search for a Higgs boson decaying into a W pair is carried out with the ALEPH detector on 453 pb-1 of data collected at center-of-mass energies up to 209 GeV. The analysis is optimized for the many topologies resulting from the six-fermion final state. A lower limit at 105.8 GeV/cÂ² on the Higgs boson mass in a fermiophobic Higgs boson scenario is obtained. The ultimate mac...
Impact of generalized Yukawa interactions on the lower Higgs-mass bound
Energy Technology Data Exchange (ETDEWEB)
Gies, Holger [Friedrich-Schiller-Universitaet Jena, Theoretisch-Physikalisches Institut, Jena (Germany); Friedrich-Schiller-Universitaet Jena, Abbe Center of Photonics, Jena (Germany); Helmholtz-Institut Jena, Jena (Germany); Sondenheimer, Rene [Friedrich-Schiller-Universitaet Jena, Theoretisch-Physikalisches Institut, Jena (Germany); Warschinke, Matthias [Friedrich-Schiller-Universitaet Jena, Theoretisch-Physikalisches Institut, Jena (Germany); Chiba University, Department of Physics, Graduate School of Science, Chiba (Japan)
2017-11-15
We investigate the impact of operators of higher canonical dimension on the lower Higgs-mass consistency bound by means of generalized Higgs-Yukawa interactions. Analogously to higher-order operators in the bare Higgs potential in an effective field theory approach, the inclusion of higher-order Yukawa interactions, e.g., φ{sup 3} anti ψψ, leads to a diminishing of the lower Higgs-mass bound and thus to a shift of the scale of new physics towards larger scales by a few orders of magnitude without introducing a metastability in the effective Higgs potential. We observe that similar renormalization group mechanisms near the weak-coupling fixed point are at work in both generalizations of the microscopic action. Thus, a combination of higher-dimensional operators with generalized Higgs as well as Yukawa interactions does not lead to an additive shift of the lower mass bound, but it relaxes the consistency bounds found recently only slightly. On the method side, we clarify the convergence properties of different projection and expansion schemes for the Yukawa potential used in the functional renormalization group literature so far. (orig.)
Low-Data Investigation of Higgs Boson Discovery at the LHC
Scoby, Cheyne M
2006-01-01
The Standard Model (SM) remains as a complete and effective tool for understanding fundamental particles and their interactions. There is only one particle that the model predicts that has not yet been discovered. The Higgs boson is required as part of the mechanism behind electroweak symmetry breaking, and explains how the weak vector bosons, as well as the charged quarks and leptons gain mass, proportional to their coupling to the Higgs field. The SM predicts many properties of the Higgs, but cannot give a precise value to its mass. Experiment and theoretical arguments have put limits on the Higgs mass to within 114.7 GeV/c2 < MH < 1000 GeV/c2. The Large Hadron Collider at CERN will provide access to a new energy regime that will offer many channels for a potential discovery of the Higgs. In the Compact Muon Solenoid (CMS) detector experiment, the “Golden mode” for Higgs discovery features decay to two Z0, with both Z0 decaying to leptonic final states. Full reconstruction analyses suffer from the...
The etiology of autistic traits in preschoolers : a population-based twin study
de Zeeuw, E.L.; van Beijsterveldt, Catharina E M; Hoekstra, Rosa A; Bartels, Meike; Boomsma, Dorret I
2017-01-01
BACKGROUND: Autism Spectrum Disorders (ASD) are highly heritable, but the exact etiological mechanisms underlying the condition are still unclear. METHODS: Using a multiple rater twin design in a large sample of general population preschool twins, this study aimed to (a) estimate the contribution of
Study of twinning behavior of powder metallurgy Ti-Si alloy by interrupted in-situ tensile tests
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Ye, X.X., E-mail: ye-xiaoxin@jwri.osaka-u.ac.jp [Joining and Welding Institute (JWRI), Osaka University (Japan); Imai, H.; Shen, J.H.; Chen, B. [Joining and Welding Institute (JWRI), Osaka University (Japan); Han, G.Q. [College of Materials Science and Engineering, Beijing University of Technology (China); Umeda, J.; Kondoh, K. [Joining and Welding Institute (JWRI), Osaka University (Japan)
2017-01-02
Twinning mechanism of powder metallurgy Ti-Si alloy was investigated by interrupted in-situ tensile tests. Extension twins {10−12}<10-1-1> in the fine-grained Ti-Si alloy were found in the uniform deformation period, but no twinning in the coarse pure Ti. Three deformation twinning nucleation mechanisms were proposed: i) local stress concentration by neighboured slip incompatibility, ii) slip/twin oriented relationship in the parent grain and iii) slip/twin transfer by high Luster-Morris oriented relationship. The interior back-stress state, grains rotation and dislocations pile-up drove the occurrence of detwinning phenomenon. Silicon-facilitation twinning verified the hypothesis that the substitutional Si solutes affected the core structures and thus the mobility of screw dislocations. Enhanced driving force and decreased energy barrier of nucleation in the micro/atomic scale were further proposed in the twinning activation. It was expected to deepen the understanding of twinning/detwinning behaviors and supply direct evidences building immature twinning mechanism. In-depth understanding about the relationship among the processing, mechanical properties and microstructure of Ti alloy was facilitated in the present work.
Higgs production as a probe of chameleon dark energy
International Nuclear Information System (INIS)
Brax, Philippe; Burrage, Clare; Davis, Anne-Christine; Seery, David; Weltman, Amanda
2010-01-01
In this paper we study various particle physics effects of a light, scalar dark energy field with chameleonlike couplings to matter. We show that a chameleon model with only matter couplings will induce a coupling to photons. In doing so, we derive the first microphysical realization of a chameleonic dark energy model coupled to the electromagnetic field strength. This analysis provides additional motivation for current and near-future tests of axionlike and chameleon particles. We find a new bound on the coupling strength of chameleons in uniformly coupled models. We also study the effect of chameleon fields on Higgs production, which is relevant for hadron colliders. These are expected to manufacture Higgs particles through weak boson fusion, or associated production with a Z or W ± . We show that, like the Tevatron, the LHC will not be able to rule out or observe chameleons through this mechanism, because gauge invariance of the low energy Lagrangian suppresses the corrections that may arise.
B¯→Xsγ with a warped bulk Higgs
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P. Moch
2016-01-01
Full Text Available We study the decay B¯→Xsγ in Randall–Sundrum models with an IR-localised bulk Higgs. The two models under consideration are a minimal model and a model with a custodial protection mechanism. We include the effects of tree- and one-loop diagrams involving 5D gluon and Higgs exchanges as well as QCD corrections arising from the evolution from the Kaluza–Klein scale to the typical scale of the decay. We find the RS corrections to the branching fraction can be sizeable for large Yukawas and moderate KK scales T; for small Yukawas the RS contribution is small enough to be invisible in current experimental data.
Fermionic effective operators and Higgs production at a linear collider
International Nuclear Information System (INIS)
Kile, Jennifer; Ramsey-Musolf, Michael J.
2007-01-01
We study the possible contributions of dimension six operators containing fermion fields to Higgs production at a 500 GeV or 1 TeV e + e - linear collider. We show that--depending on the production mechanism--the effects of such operators can be kinematically enhanced relative to standard model (SM) contributions. We determine constraints on the operator coefficients implied by existing precision electroweak measurements and the scale of neutrino mass. We find that even in the presence of such constraints, substantial deviations from SM Higgs production cross sections are possible. We compare the effects of fermionic operators with those associated with purely bosonic operators that have been previously discussed in the literature
The Vortex Oscillations and Abelian Higgs Model
International Nuclear Information System (INIS)
Karkowski, J.; Swierczynski, Z.
2000-01-01
The excitations of the vortex in Abelian Higgs model with small ratio of vector and Higgs particle masses are considered. Three main modes encountered in numerical computations are described in detail. They are also compared to analytic results obtained recently by Arodz and Hadasz in Phys. Rev. D54, 4004 (1996). (author)