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.
CP Studies and Non-Standard Higgs Physics
DEFF Research Database (Denmark)
Kraml, S.; Accomando, E.; G. Akeroyd, A.
2006-01-01
There are many possibilities for new physics beyond the Standard Model that feature non-standard Higgs sectors. These may introduce new sources of CP violation, and there may be mixing between multiple Higgs bosons or other new scalar bosons. Alternatively, the Higgs may be a composite state...... which go beyond the Standard Model and its minimal, CP-conserving supersymmetric extension: two-Higgs-doublet models and minimal supersymmetric models with CP violation, supersymmetric models with an extra singlet, models with extra gauge groups or Higgs triplets, Little Higgs models, models in extra...
CP Studies and Non-Standard Higgs Physics
DEFF Research Database (Denmark)
Kraml, S.; Accomando, E.; G. Akeroyd, A.
2006-01-01
There are many possibilities for new physics beyond the Standard Model that feature non-standard Higgs sectors. These may introduce new sources of CP violation, and there may be mixing between multiple Higgs bosons or other new scalar bosons. Alternatively, the Higgs may be a composite state, or ...
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...
Indian Academy of Sciences (India)
S Dasu
2004-02-01
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 parameter measurements are discussed. Emphasis is placed on recent investigations of Higgs produced in association with top quarks and in vector boson fusion channels. These results indicate that Higgs sector can be explored in many channels within a couple of years of LHC operation i.e., $\\mathcal{L}=30$ fb-1. Complete coverage including measurements of Higgs parameters can be carried out with full LHC program.
Holzner, André G.
2016-12-01
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.
AUTHOR|(SzGeCERN)613844
2016-01-01
The Compact Linear Collider CLIC is an option for a future multi-TeV electron-positron collider, offering the potential for a rich precision physics programme, combined with sensitivity to a wide range of new phenomena. The CLIC physics potential for measurements of the 125 GeV Higgs boson has been studied using full detector simulations for several centre-of-mass energies. The presented results provide crucial input to the energy staging strategy for the CLIC accelerator. The complete physics program for measurements of accessible Higgs boson couplings is presented in this talk. All measurements available at a given centre-of-mass energy were included in combined fits. Operation at a few hundred GeV allows the couplings and width of the Higgs boson to be determined in a model-independent manner through the study of the Higgsstrahlung and WW-fusion processes. At a lepton collider, the measurement of the Higgsstrahlung cross section using the recoil mass technique sets the absolute scale for all Higgs coupling...
Lukić, Strahinja
2016-01-01
The Compact Linear Collider CLIC is an option for a future multi-TeV electron-positron collider, offering the potential for a rich precision physics programme, combined with sensitivity to a wide range of new phenomena. The CLIC physics potential for measurements of the 125 GeV Higgs boson has been studied using full detector simulations for several centre-of-mass energies. The presented results provide crucial input to the energy staging strategy for the CLIC accelerator. The complete physics program for measurements of accessible Higgs boson couplings is presented in this contribution. The ultimate measurement precision is reached when all measurements available at a given centre-of-mass energy are included in combined fits. Operation at a few hundred GeV allows the couplings and width of the Higgs boson to be determined in a model-independent manner through the study of the Higgsstrahlung and WW-fusion processes. At a lepton collider, the measurement of the Higgsstrahlung cross section using the recoil mas...
Donato, Silvio
2017-01-01
The discovery of the Standard Model Higgs boson performed by the CMS and ATLAS collaborations during the LHC Run 1 has been an important success. This document is a short review of the search for the Higgs boson performed by the CMS collaboration during the LHC Run 1 and Run 2. In the first part, after a brief description of the Higgs boson production and decay channels, the Run-1 results are presented emphasizing the possible hints of New Physics. The main part of this document is devoted to the search for the Higgs boson with the 13 TeV data collected by the CMS experiment in 2015 and 2016, including the Standard Model searches as well as the Beyond Standard Model searches, such as the search for additional Higgs bosons and for resonant and non-resonant double Higgs boson production.
Indian Academy of Sciences (India)
Abdelhak Djouadi
2012-10-01
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 discussed, with some focus on the main production mechanism, the gluon–gluon fusion process, and the main Higgs decay modes and the experimental detection channels are discussed. Then the case of the minimal supersymmetric extension of the Standard Model is briefly surveyed. In the last section, the prospects for determining the fundamental properties of the Higgs particles are reviewed, once they have been experimentally observed.
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
Future prospects of Higgs Physics at CMS
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.
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.
Reece, Matthew
2016-01-01
I give an overview of the physics potential at possible future $e^+ e^-$ colliders, including the ILC, FCC-ee, and CEPC. The goal is to explain some of the measurements that can be done in the context of electroweak precision tests and Higgs couplings, to compare some of the options under consideration, and to put the measurements in context by summarizing their implications for some new physics scenarios. This is a writeup of a plenary talk at the Hong Kong University of Science and Technology Jockey Club Institute for Advanced Study Program on High Energy Physics Conference, January 18--21, 2016. Some previously unpublished electroweak precision results for FCC-ee and CEPC are included.
Milutinovic-Dumbelovic, Gordana
2017-01-01
The Compact Linear Collider (CLIC) is an option for a future electron-positron collider operating at centre-of-mass energies from a few hundred GeV up to 3 TeV. This paper discusses the Higgs and BSM physics reach of CLIC operating in several energy stages. The presented results are based on physics benchmark analyses using full detector simulations, several of which have been completed recently. The initial stage of operation near the top quark pair production threshold allows to study Higgs boson production in the Higgsstrahlung and WW-fusion processes, resulting in model-independent determinations of the Higgs couplings. High-energy operation, here assumed at 1.4 and 3 TeV, gives access to rarer Higgs decays and production processes such as double Higgs production, which is sensitive to the Higgs self-coupling. In the second part of this paper, examples for direct and indirect new physics searches are given. In both cases, the achievable sensitivities generally rise with the centre-of-mass energy.
LHC Higgs physics beyond the Standard Model
Energy Technology Data Exchange (ETDEWEB)
Spannowsky, M.
2007-09-22
The Large Hadron Collider (LHC) at CERN will be able to perform proton collisions at a much higher center-of-mass energy and luminosity than any other collider. Its main purpose is to detect the Higgs boson, the last unobserved particle of the Standard Model, explaining the riddle of the origin of mass. Studies have shown, that for the whole allowed region of the Higgs mass processes exist to detect the Higgs at the LHC. However, the Standard Model cannot be a theory of everything and is not able to provide a complete understanding of physics. It is at most an effective theory up to a presently unknown energy scale. Hence, extensions of the Standard Model are necessary which can affect the Higgs-boson signals. We discuss these effects in two popular extensions of the Standard Model: the Minimal Supersymmetric Standard Model (MSSM) and the Standard Model with four generations (SM4G). Constraints on these models come predominantly from flavor physics and electroweak precision measurements. We show, that the SM4G is still viable and that a fourth generation has strong impact on decay and production processes of the Higgs boson. Furthermore, we study the charged Higgs boson in the MSSM, yielding a clear signal for physics beyond the Standard Model. For small tan {beta} in minimal flavor violation (MFV) no processes for the detection of a charged Higgs boson do exist at the LHC. However, MFV is just motivated by the experimental agreement of results from flavor physics with Standard Model predictions, but not by any basic theoretical consideration. In this thesis, we calculate charged Higgs boson production cross sections beyond the assumption of MFV, where a large number of free parameters is present in the MSSM. We find that the soft-breaking parameters which enhance the charged-Higgs boson production most are just bound to large values, e.g. by rare B-meson decays. Although the charged-Higgs boson cross sections beyond MFV turn out to be sizeable, only a detailed
Sakurai Prize: The Future of Higgs Physics
Dawson, Sally
2017-01-01
The discovery of the Higgs boson relied critically on precision calculations. The quantum contributions from the Higgs boson to the W and top quark masses suggested long before the Higgs discovery that a Standard Model Higgs boson should have a mass in the 100-200 GeV range. The experimental extraction of Higgs properties requires normalization to the predicted Higgs production and decay rates, for which higher order corrections are also essential. As Higgs physics becomes a mature subject, more and more precise calculations will be required. If there is new physics at high scales, it will contribute to the predictions and precision Higgs physics will be a window to beyond the Standard Model physics.
Energy Technology Data Exchange (ETDEWEB)
Margaroli, Fabrizio
2014-09-15
We show the latest results from the CDF and D0 collaborations on the study of the Higgs boson, stemming from the analysis of the entire Tevatron Run\\,II dataset. Combining the results of many individual analyses, most of which use the full data set available, an excess with a significance of approximately three standard deviations with respect to the Standard Model hypothesis is observed at a Higgs boson mass of 125\\,GeV/$c^2$. The Tevatron unique environment allows in addition to study for the first time the spin-parity hypothesis of the Higgs boson in events where it decays to quarks. Within the current experimental uncertainties, the newly discovered boson behaves as expected by the SM in the fermionic sector.
Linear Collider Physics Resource Book for Snowmass 2001, 2 Higgs and Supersymmetry Studies
Abe, T.; Asner, David Mark; Baer, H.; Bagger, Jonathan A.; Balazs, Csaba; Baltay, C.; Barker, T.; Barklow, T.; Barron, J.; Baur, Ulrich J.; Beach, R.; Bellwied, R.; Bigi, Ikaros I.Y.; Blochinger, C.; Boege, S.; Bolton, T.; Bower, G.; Brau, James E.; Breidenbach, Martin; Brodsky, Stanley J.; Burke, David L.; Burrows, Philip N.; Butler, Joel N.; Chakraborty, Dhiman; Cheng, Hsin-Chia; Chertok, Maxwell Benjamin; Choi, Seong-Youl; Cinabro, David; Corcella, Gennaro; Cordero, R.K.; Danielson, N.; Davoudiasl, Hooman; Dawson, S.; Denner, Ansgar; Derwent, P.; Diaz, Marco Aurelio; Dima, M.; Dittmaier, Stefan; Dixit, M.; Dixon, Lance J.; Dobrescu, Bogdan A.; Doncheski, M.A.; Duckwitz, M.; Dunn, J.; Early, J.; Erler, Jens; Feng, Jonathan L.; Ferretti, C.; Fisk, H.Eugene; Fraas, H.; Freitas, A.; Frey, R.; Gerdes, David W.; Gibbons, L.; Godbole, R.; Godfrey, S.; Goodman, E.; Gopalakrishna, Shrihari; Graf, N.; Grannis, Paul D.; Gronberg, Jeffrey Baton; Gunion, John F.; Haber, Howard E.; Han, Tao; Hawkings, Richard; Hearty, Christopher; Heinemeyer, Sven; Hertzbach, Stanley S.; Heusch, Clemens A.; Hewett, JoAnne L.; Hikasa, K.; Hiller, G.; Hoang, Andre H.; Hollebeek, Robert; Iwasaki, M.; Jacobsen, Robert Gibbs; Jaros, John Alan; Juste, A.; Kadyk, John A.; Kalinowski, J.; Kalyniak, P.; Kamon, Teruki; Karlen, Dean; Keller, L; Koltick, D.; Kribs, Graham D.; Kronfeld, Andreas Samuel; Leike, A.; Logan, Heather E.; Lykken, Joseph D.; Macesanu, Cosmin; Magill, Stephen R.; Marciano, William Joseph; Markiewicz, Thomas W.; Martin, S.; Maruyama, T.; Matchev, Konstantin Tzvetanov; Monig, Klaus; Montgomery, Hugh E.; Moortgat-Pick, Gudrid A.; Moreau, G.; Mrenna, Stephen; Murakami, Brandon; Murayama, Hitoshi; Nauenberg, Uriel; Neal, H.; Newman, B.; Nojiri, Mihoko M.; Orr, Lynne H.; Paige, F.; Para, A.; Pathak, S.; Peskin, Michael E.; Plehn, Tilman; Porter, F.; Potter, C.; Prescott, C.; Rainwater, David Landry; Raubenheimer, Tor O.; Repond, J.; Riles, Keith; Rizzo, Thomas Gerard; Ronan, Michael T.; Rosenberg, L.; Rosner, Jonathan L.; Roth, M.; Rowson, Peter C.; Schumm, Bruce Andrew; Seppala, L.; Seryi, Andrei; Siegrist, J.; Sinev, N.; Skulina, K.; Sterner, K.L.; Stewart, I.; Su, S.; Tata, Xerxes Ramyar; Telnov, Valery I.; Teubner, Thomas; Tkaczyk, S.; Turcot, Andre S.; van Bibber, Karl A.; Van Kooten, Rick J.; Vega, R.; Wackeroth, Doreen; Wagner, D.; Waite, Anthony P.; Walkowiak, Wolfgang; Weiglein, Georg; Wells, James Daniel; Wester, William Carl, III; Williams, B.; Wilson, G.; Wilson, R.; Winn, D.; Woods, M.; Wudka, J.; Yakovlev, Oleg I.; Yamamoto, H.; Yang, Hai Jun
2001-01-01
This Resource Book reviews the physics opportunities of a next-generation e+e- linear collider and discusses options for the experimental program. Part 2 reviews the possible experiments on Higgs bosons and supersymmetric particles that can be done at a linear collider.
Higgs physics at the Large Hadron Collider
Indian Academy of Sciences (India)
Rohini M Godbole
2011-05-01
In this talk I shall begin by summarizing the importance of the Higgs physics studies at the Large Hadron Collider (LHC). 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 the LHC. I have added to the writeup, recent experimental results from the LHC which have become available since the time of the workshop.
Higgs Physics at the Large Hadron Collider
Godbole, Rohini M
2011-01-01
In this talk I will begin by summarising the importance of the Higgs physics studies at the LHC. I will 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 the LHC. In addition to the material covered in the presented talk, I have included in the writeup, a critical appraisal of the theoretical uncertainties in the Higgs cross-sections at the Tevatron as well as a discussion of the recent experimental results from the LHC which have become available since the time of the workshop.
Higgs boson physics at the LHC
Ocariz, Jose; The ATLAS collaboration
2016-01-01
The experimental status on Higgs boson physics is reviewed. Results from both ATLAS and CMS, using data collected in LHC run 1, are presented. First preliminary results from data collected in 2015 at 13 TeV are also presented. Prospects for Higgs physics with Run 2 and beyond are discussed.
Results from CMS on Higgs boson physics
Azzurri, Paolo
2017-01-01
A selection of measurements and results of Higgs physics obtained by the CMS experiment are presented, obtained with proton collision data collected in 2015 and 2016 at the center-of-mass energy of 13 TeV.
Higgs Physics at the CLIC Electron-Positron Linear Collider
Abramowicz, H; Afanaciev, K; Tehrani, N Alipour; Balázs, C; Benhammou, Y; Benoit, M; Bilki, B; Blaising, J -J; Boland, M J; Boronat, M; Borysov, O; Božović-Jelisavčić, I; Buckland, M; Bugiel, S; Burrows, P N; Charles, T K; Daniluk, W; Dannheim, D; Dasgupta, R; Demarteau, M; Gutierrez, M A Díaz; Eigen, G; Elsener, K; Felzmann, U; Firlej, M; Firu, E; Fiutowski, T; Fuster, J; Gabriel, M; Gaede, F; García, I; Ghenescu, V; Goldstein, J; Green, S; Grefe, C; Hauschild, M; Hawkes, C; Hynds, D; Idzik, M; Kačarević, G; Kalinowski, J; Kananov, S; Klempt, W; Kopec, M; Krawczyk, M; Krupa, B; Kucharczyk, M; Kulis, S; Laštovička, T; Lesiak, T; Levy, A; Levy, I; Linssen, L; Lukić, S; Maier, A A; Makarenko, V; Marshall, J S; Mei, K; Milutinović-Dumbelović, G; Moroń, J; Moszczyński, A; Moya, D; Münker, R M; Münnich, A; Neagu, A T; Nikiforou, N; Nikolopoulos, K; Nürnberg, A; Pandurović, M; Pawlik, B; Codina, E Perez; Peric, I; Petric, M; Pitters, F; Poss, S G; Preda, T; Protopopescu, D; Rassool, R; Redford, S; Repond, J; Robson, A; Roloff, P; Ros, E; Rosenblat, O; Ruiz-Jimeno, A; Sailer, A; Schlatter, D; Schulte, D; Shumeiko, N; Sicking, E; Simon, F; Simoniello, R; Sopicki, P; Stapnes, S; Ström, R; Strube, J; Świentek, K P; Szalay, M; Tesař, M; Thomson, M A; Trenado, J; Uggerhøj, U I; van der Kolk, N; van der Kraaij, E; Pinto, M Vicente Barreto; Vila, I; Gonzalez, M Vogel; Vos, M; Vossebeld, J; Watson, M; Watson, N; Weber, M A; Weerts, H; Wells, J D; Weuste, L; Winter, A; Wojtoń, T; Xia, L; Xu, B; Żarnecki, A F; Zawiejski, L; Zgura, I -S
2016-01-01
The Compact Linear Collider (CLIC) is an option for a future e+e- collider operating at centre-of-mass energies up to 3 TeV, providing sensitivity to a wide range of new physics phenomena and precision physics measurements at the energy frontier. This paper presents the Higgs physics reach of CLIC operating in three energy stages, sqrt(s) = 350 GeV, 1.4 TeV and 3 TeV. The initial stage of operation allows the study of Higgs boson production in Higgsstrahlung (e+e- -> ZH) and WW-fusion (e+e- -> Hnunu), resulting in precise measurements of the production cross sections, the Higgs total decay width Gamma_H, and model-independent determinations of the Higgs couplings. Operation at sqrt(s) > 1 TeV provides high-statistics samples of Higgs bosons produced through WW-fusion, enabling tight constraints on the Higgs boson couplings. Studies of the rarer processes e+e- -> ttH and e+e- -> HHnunu would allow measurements of the top Yukawa coupling and the Higgs boson self-coupling. This paper presents detailed studies of...
ATLAS Higgs Physics Prospects at the High Luminosity LHC
Koffas, Thomas; The ATLAS collaboration
2016-01-01
The High-Luminosity Large Hadron Collider will provide an unprecedented opportunity to study the properties of the Higgs boson and eventually probe for new physics beyond the Standard Model. The large anticipated data sample will allow for more precise investigations of topics already studied with earlier data samples, as well as for studies of processes that are accessible only with the much larger statistics. Rates and signal strengths will be measured for a variety of Higgs-boson production and decay modes, allowing extraction of the Higgs boson couplings. Particular final states will allow differential cross-sections to be measured for all production modes, and for studies of the Higgs width and CP properties, as well as the tensor structure of its coupling to bosons. An important part of the High-Luminosity LHC experimental program will be investigations of the Higgs self-coupling, which is accessible via studies of di-Higgs production. In this note the projections of the ATLAS physics reach in the Higgs...
Slected topics im HIggs physics at the LHC
Indian Academy of Sciences (India)
J R Forsjaw
2004-12-01
In the talk I discuss a few selected topics in Higgs phenomenology at the LHC. After some brief remarks on the standard model Higgs I turn to more novel possiblities, discussing a heavy Higgs scenario, a light Higgs scenario and a no Higgs scenario. In the case of the light HIggs, I discuss briefly the physics opportunities afforded if it becomes possible to detect low angle scattered protons at the LHC
Chang, Ngee-Pong
In the Standard Model, there is the single Higgs field, ϕ, which gives rise to constituent quark and lepton masses. The Yukawa coupling is a highly complex set of 3×3 matrices, resulting in many textures of quark and lepton masses. In this talk, I present a model which transfers the complexity of the Yukawa coupling matrices to a family of Higgs fields, so that the Yukawa coupling itself becomes a simple interaction. In the context of this Enriched Standard Model, we introduce a new r-symmetry in the extended SU(2)L × U(1)Y × U(1)R model and show how the 125 GeV and 750 GeV resonances may be identified with H and H', the key members of the Higgs family, with H being in every way identifed with the SM Higgs. There are interesting consequences of their 2γ decay widths.
Chang, Ngee-Pong
2016-01-01
In the Standard Model, there is the single Higgs field, $\\phi$, which gives rise to constituent quark and lepton masses. The Yukawa coupling is a highly complex set of $3 \\times 3$ matrices, resulting in many textures of quark and lepton masses. In this talk, I present a model which transfers the complexity of the Yukawa coupling matrices to a family of Higgs fields, so that the Yukawa coupling itself becomes a simple interaction. In the context of this Enriched Standard Model, we introduce a new $r$-symmetry in the extended $SU(2)_L \\times U(1)_Y \\times U(1)_R$ model and show how the $125 \\;GeV$ and $750 \\;GeV$ resonances may be identified with $H$ and $H'$, the key members of the Higgs family, with $H$ being in every way identifed with the SM Higgs. There are interesting consequences of their $2 \\gamma$ decay widths.
Higgs Physics at the CLIC Electron-Positron Linear Collider
Roloff, Philipp Gerhard
2016-01-01
The Compact Linear Collider (CLIC) is an option for a future $e^+e^-$ collider operating at centre-of-mass energies up to 3 TeV, providing sensitivity to a wide range of new physics phenomena and precision physics measurements at the energy frontier. This paper presents the Higgs physics reach of CLIC operating in three energy stages, $\\sqrt{s} =$ 350 GeV, 1.4 TeV and 3 TeV. The initial stage of operation allows the study of Higgs boson production in Higgsstrahlung ($e^+e^-\\to ZH$) and $WW$-fusion ($e^+e^-\\to H\
Higgs hunters win Physics World award
Johnston, Hamish
2013-01-01
The 2012 Physics World Breakthrough of the Year has been awarded to the ATLAS and CMS collaborations at CERN's Large Hadron Collider for their joint discovery of a Higgs-like particle with a mass of about 125 GeV/c2.
Higgs and new physics at high energy
Sánchez, Carlos A Solans
2014-01-01
The observation of a new particle in the search for the Standard Model (SM) Higgs boson at the LHC, reported by the ATLAS and CMS collaborations, is a milestone in the quest to understand electroweak symmetry breaking. The evidence at the level of 5 $\\sigma$ for a Higgs boson-like particle has been published by both experiments after a preliminary analysis of the data from the LHC Run-I. Precision measurements of the new particle are of critical importance. This document reviews the mass and spin measurement, the couplings scale factor measurements and the limits on new physics derived from these results.
Higgs boson mass and new physics
Energy Technology Data Exchange (ETDEWEB)
Bezrukov, Fedor [Connecticut Univ., Storrs, CT (United States). Dept. of Physics; Brookhaven National Lab., Upton, NY (United States). RIKEN-BNL Research Center; Kalmykov, Mikhail Yu.; Kniehl, Bernd A. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Shaposhnikov, Mikhail [Ecole Polytechnique Federale de Lausanne (Switzerland). Inst. de Theorie des Phenomenes Physiques
2012-05-15
We discuss the lower Higgs boson mass bounds which come from the absolute stability of the Standard Model (SM) vacuum and from the Higgs inflation, as well as the prediction of the Higgs boson mass coming from asymptotic safety of the SM. We account for the 3-loop renormalization group evolution of the couplings of the Standard Model and for a part of two-loop corrections that involve the QCD coupling {alpha}{sub s} to initial conditions for their running. This is one step above the current state of the art procedure (''one-loop matching-two-loop running''). This results in reduction of the theoretical uncertainties in the Higgs boson mass bounds and predictions, associated with the Standard Model physics, to 1-2 GeV. We find that with the account of existing experimental uncertainties in the mass of the top quark and {alpha}{sub s} (taken at 2{sigma} level) the bound reads M{sub H} {>=} M{sub min} (equality corresponds to the asymptotic safety prediction), where M{sub min}=129{+-}6 GeV. We argue that the discovery of the SM Higgs boson in this range would be in agreement with the hypothesis of the absence of new energy scales between the Fermi and Planck scales, whereas the coincidence of M{sub H} with M{sub min} would suggest that the electroweak scale is determined by Planck physics. In order to clarify the relation between the Fermi and Planck scale a construction of an electron-positron or muon collider with a center of mass energy {proportional_to}200+200 GeV (Higgs and t-quark factory) would be needed.
StDenis, R; The ATLAS collaboration
2014-01-01
The discovery of a new boson with the ATLAS detector at the LHC proton-proton collider is confirmed using the full data set collected at centre-of-mass energies of 7 and 8 TeV. The spin and parity properties of the boson are consistent with that of a scalar particle with positive parity. Comparison of the $J^{P}=0^+$ hypothesis to alternatives $J^{P} = 0^-,1^{+},1^-,2^+$ result in exclusion of these other choices at 97.8\\%, 99.97\\%, 99.7\\%, and 99.3\\% CL. The Higgs-boson Mass is $m_H = 125.5 \\pm 0.2 {\\rm (stat.)} ^{+0.5}_{-0.5} {\\rm (syst.)}$ \\GeV. Evidence for production of the Higgs boson by vector boson fusion is obtained in a model-independent approach by comparing the signal strengths $\\mu$ of vector boson fusion and production associated with a vector boson to to that for gluon fusion including associated production of top quark pairs: $\\mu_{\\rm VBF+VH}/\\mu_{\\rm ggF+ttH}= 1.4 ^{+0.4}_{-0.3} \\rm{(stat.)} ^{+0.6}_{-0.4} \\rm{(syst.)}$ which is 3.3 Gaussian standard deviations from zero.
(No) Eternal Inflation and Precision Higgs Physics
Arkani-Hamed, Nima; Senatore, Leonardo; Villadoro, Giovanni
2008-01-01
Even if nothing but a light Higgs is observed at the LHC, suggesting that the Standard Model is unmodified up to scales far above the weak scale, Higgs physics can yield surprises of fundamental significance for cosmology. As has long been known, the Standard Model vacuum may be metastable for low enough Higgs mass, but a specific value of the decay rate holds special significance: for a very narrow window of parameters, our Universe has not yet decayed but the current inflationary period can not be future eternal. Determining whether we are in this window requires exquisite but achievable experimental precision, with a measurement of the Higgs mass to 0.1 GeV at the LHC, the top mass to 60 MeV at a linear collider, as well as an improved determination of alpha_s by an order of magnitude on the lattice. If the parameters are observed to lie in this special range, particle physics will establish that the future of our Universe is a global big crunch, without harboring pockets of eternal inflation, strongly sug...
Probing New Physics Scales from Higgs and Electroweak Observables at $e^+ e^-$ Higgs Factory
Ge, Shao-Feng; Xiao, Rui-Qing
2016-01-01
New physics beyond the standard model (SM) can be formulated via dimension-6 effective operators, whose coefficients (cutoffs) characterize the scales of new physics. We study the probe of new physics scales from the electroweak precision observables (EWPO) and the Higgs observables (HO) at the future $e^+e^-$ Higgs Factory (such as CEPC). To optimize constraints of new physics from all available observables, we establish a scheme-independent approach. With this formulation, we treat the SM electroweak parameters and the coefficients of dimension-6 operators on equal footing, which can be fitted simultaneously by the same $\\chi^2$ function. As deviations from the SM are generally small, we can expand the new physics parameters up to linear order and perform an analytical $\\chi^2$ fit to derive the potential reach of the new physics scales. We find that the HO (from both Higgs produnction and decay rates) can probe the new physics scales up to 10TeV (and to 40TeV for the case of gluon-involved operator $\\mathc...
Higgs Physics at Future Colliders recent theoretical developments
Djouadi, A
2004-01-01
I review the physics of the Higgs sector in the Standard Model and its minimal supersymmetric extension, the MSSM. I will discuss the prospects for discovering the Higgs particles at the upgraded Tevatron, at the Large Hadron Collider, and at a future high--energy $e^+e^-$ linear collider with centre--of--mass energy in the 350--800 GeV range, as well as the possibilities for studying their fundamental properties. Some emphasis will be put on the theoretical developments which occurred in the last two years.
Higgs physics at future colliders: Recent theoretical developments
Indian Academy of Sciences (India)
Abdelhak Djouadi
2004-02-01
I review the physics of the Higgs sector in the standard model and its minimal supersymmetric extension, the MSSM. I will discuss the prospects for discovering the Higgs particles at the ungraded Tevatron, at the large hadron collider, and at a future high-energy $e^{+}e^{-}$ linear collider with centre-of-mass energy in the 350-800 GeV range, as well as the possibilities for studying their fundamental properties. Some emphasis will be put on the theoretical developments which occurred in the last two years.
Weakly-Coupled Higgs Bosons and Precision Electroweak Physics
Energy Technology Data Exchange (ETDEWEB)
Rowson, Peter C.
2003-06-02
We examine the prospects for discovering and elucidating the weakly-coupled Higgs sector at future collider experiments. The Higgs search consists of three phases: (i) discovery of a Higgs candidate, (ii) verification of the Higgs interpretation of the signal, and (iii) precision measurements of Higgs sector properties. The discovery of one Higgs boson with Standard Model properties is not sufficient to expose the underlying structure of the electroweak symmetry breaking dynamics. It is critical to search for evidence for a non-minimal Higgs sector and/or new physics associated with electroweak symmetry breaking dynamics. An improvement in precision electroweak data at future colliders can play a useful role in confirming the theoretical interpretation of the Higgs search results.
Higgs and new physics at high energy
Solans, CA; The ATLAS collaboration
2014-01-01
The observation of a new particle in the search for the Standard Model (SM) Higgs boson at the LHC, reported by the ATLAS and CMS collab- orations, is a milestone in the quest to understand electroweak symmetry breaking. The evidence for a Higgs boson-like particle has been pub- lished at the level of 5 σ by both experiments after preliminary analysis of the data from the LHC Run-I. Precision measurements of the new particle are of critical importance. This document reviews the mass and spin mea- surement, the couplings scale factor measurements using a state-of-the-art framework and the limits on new physics derived from these results.
Lines of Constant Physics in a Five-Dimensional Gauge-Higgs Unification Scenario
Alberti, Maurizio; Knechtli, Francesco; Moir, Graham
2016-01-01
We report on the progress in the study of a five-dimensional SU(2) Gauge-Higgs Unification model. In this non-perturbative study, the Higgs mechanism is triggered by the spontaneous breaking of a global symmetry. In the same region of the phase diagram, we observe both dimensional reduction and the ratio of Higgs and Z boson masses to take the value known from experiment. We present the first results on the construction of a line of constant physics in this region, including the prediction for the mass scale of the first excited states of the Higgs and gauge bosons.
TASI 2013 lectures on Higgs physics within and beyond the Standard Model
Logan, Heather E
2014-01-01
These lectures start with a detailed pedagogical introduction to electroweak symmetry breaking in the Standard Model, including gauge boson and fermion mass generation and the resulting predictions for Higgs boson interactions. I then survey Higgs boson decays and production mechanisms at hadron and e+e- colliders. I finish with two case studies of Higgs physics beyond the Standard Model: two-Higgs-doublet models, which I use to illustrate the concept of minimal flavor violation, and models with isospin-triplet scalar(s), which I use to illustrate the concept of custodial symmetry.
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.
ATLAS Higgs Physics Prospects at the High Luminosity LHC
Koffas, Thomas; The ATLAS collaboration
2016-01-01
The Higgs physics prospects at the high-luminosity LHC are presented, assuming an energy of sqrt(s) = 14 TeV and a data sample of 3000 fb-1. In particular, the ultimate precision attainable on the couplings measurements of the 125 GeV particle with elementary fermions and bosons is discussed, as well as perspectives on the search for the Standard Model di-Higgs production, which could lead to the measurement of the Higgs boson self-coupling.
Effective gauge-Higgs operators analysis of new physics associated with the Higgs boson
Chang, We-Fu; Pan, Wei-Ping; Xu, Fanrong
2013-08-01
We study the new physics related to the recently discovered 125 GeV Higgs by employing an important subset of the standard model (SM) gauge-invariant dimension-6 operators constructed by the SM Higgs and gauge fields. Explicitly, we perform a model-independent study on the production and decays of the Higgs, the electric dipole moments (EDMs) of the neutron and the electron, and we take into account the anomalous magnetic dipole moments of the muon and electron as well. We find that, even if all Higgs decay channels agree with the SM predictions, the SM theoretical uncertainties provide a lot of room to host new phyiscs associated with the 125 GeV boson. A linear relation is revealed in our numerical study that μZZ≃μWW and 0.6≲μZZ,WW≲1.4 at 95% C.L. with or without the EDM constraints. The neutron and electron EDMs severely constrain the relevant Wilson coefficients. Therefore the CP-violating components in the h→WW, ZZ channels are too small, ˜O(10-5), to be detected at the LHC. However, we point out that, even though the parity of the 125 GeV boson has been largely determined to be even in the h→ZZ channel, one should pay special attention to the potentially large CP violation in the h→γγ and h→γZ channels. This should be seriously checked in the future spin correlation experiments.
Higgs diphoton rate enhancement from supersymmetric physics beyond the MSSM
Berg, Marcus; Ghilencea, D.M.; Petersson, Christoffer
2013-01-01
We show that supersymmetric "new physics" beyond the MSSM can naturally accommodate a Higgs mass near 126 GeV and enhance the signal rate in the Higgs to diphoton channel, while the signal rates in all the other Higgs decay channels coincide with Standard Model expectations, except possibly the Higgs to Z-photon channel. The "new physics" that corrects the relevant Higgs couplings can be captured by two supersymmetric effective operators. We provide a simple example of an underlying model in which these operators are simultaneously generated. The scale of "new physics" that generates these operators can be around 5 TeV or larger, and outside the reach of the LHC.
Higgs Working Group Report of the Snowmass 2013 Community Planning Study
Dawson, S; Logan, H; Qian, J; Tully, C; Van Kooten, R; Ajaib, A; Anastassov, A; Anderson, I; Bake, O; Barger, V; Barklow, T; Batell, B; Battaglia, M; Berge, S; Blondel, A; Bolognesi, S; Brau, J; Brownson, E; Cahill-Rowley, M; Calancha-Paredes, C; Chen, C -Y; Chou, W; Clare, R; Cline, D; Craig, N; Cranmer, K; de Gruttola, M; Elagin, A; Essig, R; Everett, L; Feng, E; Fujii, K; Gainer, J; Gao, Y; Gogoladze, I; Gori, S; Goncalo, R; Graf, N; Grojean, C; Guindon, S; Han, T; Hanson, G; Harnik, R; Heinemann, B; Heinemeyer, S; Heintz, U; Hewett, J; Ilchenko, Y; Ismail, A; Jain, V; Janot, P; Kawada, S; Kehoe, R; Klute, M; Kotwal, A; Krueger, K; Kukartsev, G; Kumar, K; Kunkle, J; Lewis, I; Li, Y; Linssen, L; Lipeles, E; Lipton, R; Liss, T; List, J; Liu, T; Liu, Z; Low, I; Ma, T; Mackenzie, P; Mellado, B; Melnikov, K; Moortgat-Pick, G; Mourou, G; Narain, M; Nielsen, J; Okada, N; Okawa, H; Olsen, J; Onyisi, P; Parashar, N; Peskin, M; Petriello, F; Plehn, T; Pollard, C; Potter, C; Prokofiev, K; Rauch, M; Rizzo, T; Robens, T; Rodriguez, V; Roloff, P; Ruiz, R; Sanz, V; Sayre, J; Shafi, Q; Shaughnessy, G; Sher, M; Simon, F; Solyak, N; Stupak, J; Su, S; Tanabe, T; Tajima, T; Telnov, V; Tian, J; Thomas, S; Thomson, M; Un, C; Velasco, M; Wagner, C; Wang, S; Whitbeck, A; Yao, W; Yokoya, H; Zenz, S; Zerwas, D; Zhang, Y; Zhou, Y
2013-01-01
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 $C\\!P$-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).
The Higgs Physics Programme at the International Linear Collider
Sefkow, Felix
2014-01-01
The talk summarises the case for Higgs physics in $e^+e^-$ collisions and explains how Higgs parameters can be extracted in a model-independent way at the International Linear Collider (ILC). The expected precision will be discussed in the context of projections for the experiments at the Large Hadron Collider (LHC).
A Model of Neutrino and Higgs Physics at the Electroweak Scale
Aranda, Alfredo; Diaz-Cruz, J Lorenzo
2008-01-01
We present and explore the Higgs physics of a model that in addition to the Standard Model fields includes a lepton number violating singlet scalar field. Based on the fact that the only experimental data we have so far for physics beyond the Standard Model is that of neutrino physics, we impose a constraint for any addition not to introduce new higher scales. As such, we introduce right-handed neutrinos with an Electroweak Scale mass. We study the Higgs decay $H \\to \
New Physics and novel Higgs signals
Díaz-Cruz, J L
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-> tau mu or with rare top decays.
Electroweak symmetry breaking and Higgs physics. Basic concepts
Energy Technology Data Exchange (ETDEWEB)
Gomez-Bock, G.; Noriega-Papaqui, R.; Pedraza, I. [Benemerita Univ. Auton. de Puebla, Pue (Mexico). Inst. de Fisica ' ' LRT' ' ; Mondragon, M. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Fisica; Muehlleitner, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)]|[Laboratoire d' Annecy-le-Vieux Physique Theorique, LAPTH, Annecy-le-Vieux (France); Spira, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Zerwas, P.M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2005-09-01
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 symmetry breaking. In addition to the theoretical basis, the present experimental status of Higgs physics and implications for future experiments at the LHC and e{sup +}e{sup -} 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.)
Duru, Firdevs
2007-01-01
This thesis consists of two main parts: R&D; studies done on the Compact Muon Solenoid (CMS) Hadronic Calorimeter (HCAL) and physics simulations on the Higgs boson for a Minimal Supersymmetric Standard Model (MSSM) and a Standard Model (SM) channel. In the first part, the air core light guides used in the read-out system of the Hadronic Forward (HF) calorimeter and the reflective materials used in them are studied. Then, tests and simulations were performed to find the most efficient way to collect Cerenkov light from the quartz plates, which are proposed as a substitute for the scintillator tiles in the Hadronic Endcap (HE) calorimeter due to radiation damage problems. In the second part physics simulations and their results are presented. The MSSM channel H/A[arrow right]ττ [arrow right]l l v v v v is studied to investigate the jet and missing transverse energy (MET) reconstruction of the CMS detector. The effects of the jet and MET corrections on the Higgs boson mass reconstruction are investigated. ...
New Physics Searches with Higgs-photon associated production at the Higgs Factory
Ren, Hong-Yu
2015-01-01
The Higgs factory is designed for precise measurement of Higgs characters and search for new physics. In this paper we propose that $e^+e^- \\to \\gamma h$ process could be a useful channel for new physics, which is normally expressed model independently by effective field theory. We calculate the cross section in both the Standard Model and effective field theory approach, and find that the new physics effects of $\\gamma h$ have only two degrees of freedom, much fewer than the Higgsstrahlung process. This point could be used to reduce the degeneracies of Wilson coefficients. We also calculated for the first time the 2$\\sigma$ bounds of $\\gamma h$ at the Higgs factory, and prove that $\\gamma h$ is more sensitive to some dimension-6 operators than the current experimental data. In the optimistic scenario new physics effects may be observed at the CEPC or FCC-ee after the first couple of years of their run.
Lilith: a tool for constraining new physics from Higgs measurements
Bernon, Jérémy; Dumont, Béranger
2015-09-01
The properties of the observed Higgs boson with mass around 125 GeV can be affected in a variety of ways by new physics beyond the Standard Model (SM). The wealth of experimental results, targeting the different combinations for the production and decay of a Higgs boson, makes it a non-trivial task to assess the patibility of a non-SM-like Higgs boson with all available results. In this paper we present Lilith, a new public tool for constraining new physics from signal strength measurements performed at the LHC and the Tevatron. Lilith is a Python library that can also be used in C and C++/ ROOT programs. The Higgs likelihood is based on experimental results stored in an easily extensible XML database, and is evaluated from the user input, given in XML format in terms of reduced couplings or signal strengths.The results of Lilith can be used to constrain a wide class of new physics scenarios.
Lilith: a tool for constraining new physics from Higgs measurements
Bernon, Jeremy
2015-01-01
The properties of the observed Higgs boson with mass around 125 GeV can be affected in a variety of ways by new physics beyond the Standard Model (SM). The wealth of experimental results, targeting the different combinations for the production and decay of a Higgs boson, makes it a non-trivial task to assess the compatibility of a non-SM-like Higgs boson with all available results. In this paper we present Lilith, a new public tool for constraining new physics from signal strength measurements performed at the LHC and the Tevatron. Lilith is a Python library that can also be used in C and C++/ROOT programs. The Higgs likelihood is based on experimental results stored in an easily extensible XML database, and is evaluated from the user input, given in XML format in terms of reduced couplings or signal strengths. The results of Lilith can be used to constrain a wide class of new physics scenarios.
Kiiskinen, A P
2004-01-01
This thesis describes direct searches for pair production of charged Higgs bosons performed in the data collected by the DELPHI detector at the LEP collider at CERN. In addition, the possibilities to discover and study heavy charged Higgs bosons at possible future high-energy linear colliders are presented. The existence of charged Higgs bosons is predicted by many extensions of the Standard Model. A possible discovery of these particles would be a solid proof for physics beyond the Standard Model. Discovery of charged Higgs bosons, and measurement of their properties, would also provide useful information about the structure of the more general theory. New analysis methods were developed for the searches performed at LEP. A large, previously unexplored, mass range for cover but no evidence for the existence of the charged Higgs bosons was found. This allowed setting new lower mass limits for the charged Higgs boson within the framework of general two Higgs doublet models. Results have been interpreted and pr...
Fox-Wolfram Moments in Higgs Physics
Bernaciak, Catherine; Butter, Anja; Plehn, Tilman
2012-01-01
Geometric correlations between jets as part of hard processes or in addition to hard processes are key ingredients to many LHC analyses. Fox--Wolfram moments systematically describe these correlations in terms of spherical harmonics. These moments, either computed from the tagging jets or from all jets in each event, can significantly improve Higgs searches in weak boson fusion. Applications of Fox--Wolfram moments in LHC analyses obviously surpass jets as analysis objects as well as Higgs searches in terms of analyses.
Higgs and Dark Matter Physics in the Type-II Two-Higgs-Doublet Model inspired by E_6 GUT
Ko, P; Yu, Chaehyun
2015-01-01
We study Higgs and dark matter physics in the type-II two-Higgs-doublet model (2HDM) with an extra U(1)_H gauge symmetry, inspired by the E_6 grand unified theory (GUT). From the viewpoint of the bottom-up approach, the additional U(1)_H gauge symmetry plays a crucial role in avoiding the tree-level flavor changing neutral currents mediated by neutral Higgs bosons in general 2HDMs. In the model with U(1)_H gauge symmetry, which has Type-II Yukawa couplings, we have to introduce additional chiral fermions that are charged under the U(1)_H gauge symmetry as well as under the Standard-Model (SM) gauge symmetry in order to cancel chiral gauge anomalies. For the U(1)_H charge assignment and the extra matters, we adopt the ones inspired by the E_6 GUT: the extra quark-like and lepton-like fermions with the non-trivial U(1)_H charges. We discuss their contributions to the physical observables, such as the measurements of Higgs physics and electro-weak interactions, and investigate the consistency with the experiment...
Recent results from Higgs boson physics at the LHC
Canelli, Florencia
2016-01-01
Results on Higgs boson physics with proton-proton collision data at √ s = 13 TeV collected by the ATLAS and CMS detectors at the Large Hadron Collider corresponding to an integrated lu- minosity up to 15 fb − 1 taken during 2015 and part of 2016 are presented. Standard Model Higgs boson measurements in different production and decay channels such as H → γγ , ZZ , WW , μ μ , b ̄ b , as well as Beyond-Standard-Model searches for first indications of an extended Higgs boson sector, are summarized. Measurements of the fiducial and differential cross sections for Higgs boson production in the H → γγ and H → ZZ ∗ → 4 l channels are also included.
Prospects for Precision Higgs Physics at Linear Colliders
Simon, Frank
2012-01-01
A linear e+e- collider provides excellent possibilities for precision measurements of the properties of the Higgs boson. At energies close to the Z-Higgs threshold, the Higgs boson can be studied in recoil against a Z boson, to obtain not only a precision mass measurement but also direct measurements of the branching ratios for most decay modes, including possible decay to invisible species. At higher energies, the Higgs boson coupling to top quarks and the Higgs boson self-coupling can also be measured. At energies approaching 1 TeV and above, the rising cross section for Higgs production in WW fusion allows the measurement of very small branching ratios, including the branching ratio to muon pairs. These experiments make it possible to determine the complete profile of the Higgs boson in a model-independent way. The prospects for these measurements are summarized, based on the results of detailed simulation studies performed within the frameworks of the CLIC conceptual design report and the ILC technical de...
Higgs physics programme at the High-Luminosity LHC with ATLAS
Jezequel, Stephane; The ATLAS collaboration
2017-01-01
From the mid-2020s, the Large Hadron Collider will run as High Luminosity LHC (HL-LHC) with a centre of mass energy of 14 TeV and an instantaneous luminosity of 5-7 x 10^34 cm^-2 s^-1. It aims to collect a total integrated luminosity of 3000 fb-1 by about 2037. The unprecedented amount of data collected by the upgraded ATLAS detector at the HL-LHC will be used to make precision measurements of the 125 GeV Higgs boson. In addition final states including Higgs bosons can be used to probe for beyond-the-Standard-Model physics and for search for rare processes. Observation of di-Higgs production, pp—>HH, can be used to constrain the parameter lambda in the Higgs potential and is one of the key physics drivers for the HL-LHC programme. However due to the small predicted cross section for HH production many final states must be considered to gain sensitivity to di-Higgs production at the HL-LHC. In this talk we present the studies on the prospects for precision measurements of the Higgs boson and searches for rar...
The Physics Landscape after the Higgs Discovery at the LHC
Ellis, John
2015-01-01
What is the Higgs boson telling us? What else is there, maybe supersymmetry and/or dark matter? How do we find it? These are now the big questions in collider physics that I discuss in this talk, from a personal point of view.
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.
Higgs Inflation, Seesaw Physics and Fermion Dark Matter
Okada, Nobuchika
2015-01-01
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 $n_s \\simeq 0.968$, the tensor-to-scalar ratio $r \\simeq 0.003$, and the running of the spectral index $\\alpha=dn_s/d \\ln k \\simeq -5.2 \\times 10^{-4}$ for the number of e-folds $N_0=60$ ($n_s \\simeq 0.962$, $r \\simeq 0.004$, and $\\alpha \\simeq -7.5 \\times 10^{-4}$ for $N_0=50$). The fairly low value of $r \\simeq 0.003$ predicted in this class of models means that the ongoing space and land based experiments are not expected to observe gravity waves generated ...
Prospects of LHC Higgs Physics at the end of Run III
Chen, Xin; The ATLAS collaboration
2016-01-01
The talk discusses the expected status of Higgs physics at the end of Run III. The current status is briefly included, and the expected Higgs reach after HL-LHC are also summarized/presented for some channels.
Lilith: a tool for constraining new physics from Higgs measurements
Energy Technology Data Exchange (ETDEWEB)
Bernon, Jeremy [Universite Grenoble-Alpes, CNRS/IN2P3, Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France); Dumont, Beranger [Universite Grenoble-Alpes, CNRS/IN2P3, Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France); Institute for Basic Science (IBS), Center for Theoretical Physics of the Universe, Daejeon (Korea, Republic of)
2015-09-15
The properties of the observed Higgs boson with mass around 125 GeV can be affected in a variety of ways by new physics beyond the Standard Model (SM). The wealth of experimental results, targeting the different combinations for the production and decay of a Higgs boson, makes it a non-trivial task to assess the compatibility of a non-SM-like Higgs boson with all available results. In this paper we present Lilith, a new public tool for constraining new physics from signal strength measurements performed at the LHC and the Tevatron. Lilith is a Python library that can also be used in C and C++/ROOT programs. The Higgs likelihood is based on experimental results stored in an easily extensible XML database, and is evaluated from the user input, given in XML format in terms of reduced couplings or signal strengths.The results of Lilith can be used to constrain a wide class of new physics scenarios. (orig.)
2013 Aspen Winter Conference on particle physics: Higgs Quo Vadis
2013-01-01
By winter of 2013, the ATLAS and CMS experiments at the LHC will establish their discovery of a new Higgs-like particle with a mass around 125 GeV. The new data will shed light on its properties. Many fundamental questions in Physics will start to get their answer. The 2013 Aspen Winter Conference on particle physics will bring together experimentalists and theorists, creating an ideal environment to present and discuss the implications of the Higgs discovery in the framework of the Standrad Model and beyond. The conference will be formulated to encourage close collaborations and active exchange of information, which is crucial for making progress on this central topic of particle physics.
New Physics Models Facing Lepton Flavor Violating Higgs Decays
Košnik, Nejc
2015-01-01
We speculate about the possible interpretations of the recently observed excess in the $h \\to \\tau \\mu$ decay. We derive a robust lower bound on the Higgs boson coupling strength to a tau and a muon, even in presence of the most general new physics affecting other Higgs properties. Then we reevaluate complementary indirect constraints coming from low energy observables as well as from theoretical considerations. In particular, the tentative signal should lead to $\\tau \\to \\mu \\gamma$ at rates which could be observed at Belle II. In turn we show that, barring fine-tuned cancellations, the effect can be accommodated within models with an extended scalar sector. These general conclusions are demonstrated in explicit new physics models. Finally we show how, given the $h \\to \\tau \\mu$ signal, the current and future searches for $\\mu \\to e \\gamma$ and $\\mu \\to e$ nuclear conversions unambiguously constrain the allowed rates for $h \\to \\tau e$.
Colloquium on the 2013 Nobel Prize in Physics Awarded to Francois Englert and Peter Higgs
Mannheim, Philip D
2015-01-01
In 2013 the Nobel Prize in Physics was awarded to Francois Englert and Peter Higgs for their development in 1964 of 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 observed at the Large Hadron Collider after an almost half a century search. In this talk we review the work of these Nobel recipients and discuss its implications.
Anatomizing Exotic Production of the Higgs Boson
Energy Technology Data Exchange (ETDEWEB)
Yu, Felix [Fermilab
2014-07-10
We discuss exotic production modes of the Higgs boson and how their phenomenology can be probed in current Higgs analyses. We highlight the importance of differential distributions in disentangling standard production mechanisms from exotic modes. We present two model benchmarks for exotic Higgs production arising from chargino-neutralino production and study their impact on the current Higgs dataset. As a corollary, we emphasize that current Higgs coupling fits do not fully explore the space of new physics deviations possible in Higgs data.
Higgs and New Physics at ATLAS and CMS
Giagu, Stefano; The ATLAS collaboration
2017-01-01
Results of the search for new physics effects in proton-proton collision data at s = 13 TeV collected by the ATLAS and CMS detectors at the Large Hadron Collider are presented. Standard Model Higgs boson measurements in different production and decay channels, as well as direct Beyond-Standard-Model searches in several experimental signatures, based on data taken during the 2015 and part of 2016 runs are summarised.
The search and discovery of the Higgs boson a brief introduction to particle physics
Flores Castillo, Luis Roberto
2015-01-01
This book provides a general description of the search for and discovery of the Higgs boson (particle) at CERN's Large Hadron Collider. The goal is to provide a relatively brief overview of the issues, instruments and techniques relevant for this search; written by a physicist who was directly involved. The Higgs boson may be the one particle that was studied the most before its discovery and the story from postulation in 1964 to detection in 2012 is a fascinating one. The story is told here while detailing the fundamentals of particle physics.
Unitarity implications of diboson resonance in the TeV region for Higgs physics
DEFF Research Database (Denmark)
Cacciapaglia, Giacomo; Frandsen, Mads T.
2015-01-01
We investigate the implications of a putative new resonance in the TeV region coupled to the weak bosons. By studying perturbative unitarity in longitudinal WW scattering, we find that a weakly coupled spin-1 resonance, that explains the ATLAS diboson excesses, is allowed with a SM-like Higgs....... On the other hand, larger values of the resonance couplings, preferred in models of strong dynamics, would imply either sizeable reduction of the Higgs couplings or new physics, beyond the diboson resonance, at a few TeV....
Higgs Couplings and their Implications for New Physics Scales
Muhlleitner, M
2015-01-01
In view of the absence of any direct sign of New Physics (NP) at the LHC, the precise investigation of the Higgs properties becomes more and more important in our quest for physics beyond the Standard Model (SM). Coupling measurements play here an important role and not only complement the reach of the LHC but, depending on the physics scenarios, also allow for tests of NP scales beyond the ones accessible at present colliders. In this context, various representative scenarios beyond the SM will be reviewed.
Studying Higgs bosons by top pair production at photon colliders
Asakawa, E
2004-01-01
We study the effect of heavy neutral Higgs bosons on the top pair production process at photon linear colliders.The interference patterns betwenn the resonant Higgs production amplitudes and the continuum QED amplitudes are examined. The patterns are sensitive to the phase of the photon-photon-Higgs vertex which is a good probe of new charged particles.
Curiel, A M; Temes, D; Curiel, Ana M.; Herrero, Maria J.; Temes, David
2003-01-01
We consider a plausible scenario in the Minimal Supersymmetric Standard Model (MSSM) where all the genuine supersymmetric (SUSY) particles are heavier than the electroweak scale. In this situation, indirect searches via their radiative corrections to low energy observables are complementary to direct searches, and they can be crucial if the SUSY masses are at the TeV energy range. We summarize the most relevant heavy SUSY radiative effects in Higgs boson physics and emphasize those that manifest a non-decoupling behaviour. We focus, in particular, on the SUSY-QCD non-decoupling effects in fermionic Higgs decays, flavour changing Higgs decays and Yukawa couplings. Some of their phenomenological implications at future colliders are also studied.
Rodríguez, Arturo
2016-01-01
The FCC project as well as the Pythia + Delphes analysis within the FCC software are introduced. The ROOT analysis carried out to reconstruct main observables, such the invariant mass of the bb system, transverse mass and momentum of the W boson together with the lepton pT and distribution is explained. The resulting reconstructed invariant mass of the bb system showed a peak near the 125 GeV in correspondence with the Higgs boson. Future steps towards estimating the physics potential of the FCC-hh machine in this channel are discussed.
Higgs and flavour as doors to new physics
Sala, Filippo
2015-01-01
A natural solution to the hierarchy problem of the Fermi scale motivates signals of New Physics at current and near future experiments. After a critical synthesis of this general motivation, we concentrate our attention on the interplay between LHC searches for new resonances, and precision measurements of both Higgs couplings and flavour violating observables. We do so for i) the Higgs sectors of the NMSSM and MSSM, as paradigmatic examples of theories providing extra scalars, and for ii) CKM-like flavour symmetries, with a focus on U(2)^3. This article is mainly based on several papers by the author, but it also reviews other recent related results. Its goal is to provide a synthetic - yet comprehensive orientation on these subjects, at the dawn of several (ATLAS and CMS, LHCb, NA62 etc.) coming experimental results.
Precision Higgs Physics, Effective Field Theory, and Dark Matter
Henning, Brian Quinn
The recent discovery of the Higgs boson calls for detailed studies of its properties. As precision measurements are indirect probes of new physics, the appropriate theoretical framework is effective field theory. In the first part of this thesis, we present a practical three-step procedure of using the Standard Model effective field theory (SM EFT) to connect ultraviolet (UV) models of new physics with weak scale precision observables. With this procedure, one can interpret precision measurements as constraints on the UV model concerned. We give a detailed explanation for calculating the effective action up to one-loop order in a manifestly gauge covariant fashion. The covariant derivative expansion dramatically simplifies the process of matching a UV model with the SM EFT, and also makes available a universal formalism that is easy to use for a variety of UV models. A few general aspects of renormalization group running effects and choosing operator bases are discussed. Finally, we provide mapping results between the bosonic sector of the SM EFT and a complete set of precision electroweak and Higgs observables to which present and near future experiments are sensitive. With a detailed understanding of how to use the SM EFT, we then turn to applications and study in detail two well-motivated test cases. The first is singlet scalar field that enables the first-order electroweak phase transition for baryogenesis; the second example is due to scalar tops in the MSSM. We find both Higgs and electroweak measurements are sensitive probes of these cases. The second part of this thesis centers around dark matter, and consists of two studies. In the first, we examine the effects of relic dark matter annihilations on big bang nucleosynthesis (BBN). The magnitude of these effects scale simply with the dark matter mass and annihilation cross-section, which we derive. Estimates based on these scaling behaviors indicate that BBN severely constrains hadronic and radiative dark
A ball pool model to illustrate Higgs physics to the public
Organtini, Giovanni
2017-03-01
A simple model is presented to explain Higgs boson physics to the grand public. The model consists of a children’s ball pool representing a Universe filled with a certain amount of the Higgs field. The model is suitable for usage as a hands-on tool in scientific exhibits and provides a clear explanation of almost all the aspects of the physics of the Higgs field interaction with other particles.
A model of neutrino and Higgs physics at the electroweak scale
Energy Technology Data Exchange (ETDEWEB)
Aranda, Alfredo [Dual CP Institute of High Energy Physics (Mexico); Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima (Mexico)], E-mail: fefo@ucol.mx; Blanno, Omar [Facultad de Ciencias Fisico-Matematicas, BUAP Apdo. Postal 1364, C.P. 72000 Puebla, Pue (Mexico)], E-mail: pos00625@alumnos.fcfm.buap.mx; Diaz-Cruz, J. Lorenzo [Dual CP Institute of High Energy Physics (Mexico); Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima (Mexico); Facultad de Ciencias Fisico-Matematicas, BUAP Apdo. Postal 1364, C.P. 72000 Puebla, Pue (Mexico)], E-mail: lorenzo.diaz@fcfm.buap.mx
2008-02-14
We present and explore the Higgs physics of a model that in addition to the Standard Model fields includes a lepton number violating singlet scalar field. Based on the fact that the only experimental data we have so far for physics beyond the Standard Model is that of neutrino physics, we impose a constraint for any addition not to introduce new higher scales. As such, we introduce right-handed neutrinos with an electroweak scale mass. We study the Higgs decay H{yields}{nu}{nu} and show that it leads to different signatures compared to those in the Standard Model, making it possible to detect them and to probe the nature of their couplings.
Beyond the Standard Model Higgs Physics using the ATLAS Experiment
Keller, J; The ATLAS collaboration
2013-01-01
The discovery of a Higgs-like boson with a mass of about 125 GeV 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, we outline the current results from the ATLAS Experiment regarding Beyond the Standard Model (BSM) Higgs hypothesis tests. 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.
A Ball Pool Model to Illustrate Higgs Physics to the Public
Organtini, Giovanni
2017-01-01
A simple model is presented to explain Higgs boson physics to the grand public. The model consists of a children's ball pool representing a Universe filled with a certain amount of the Higgs field. The model is suitable for usage as a hands-on tool in scientific exhibits and provides a clear explanation of almost all the aspects of the physics of…
Precise predictions for Higgs physics in the next-to-minimal supersymmetric standard model (NMSSM)
Energy Technology Data Exchange (ETDEWEB)
Drechsel, Peter
2016-08-15
Within this thesis a precise mass-prediction for the Higgs fields of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) is obtained with Feynman-diagrammatic methods. The results are studied numerically for sample scenarios that are in agreement with current New Physics searches at the LHC. Furthermore a comparison between the obtained results and different calculations is performed as a first step in order to obtain an estimation for the theoretical uncertainties of the Higgs-mass prediction in the NMSSM. The precise mass-prediction includes the full NMSSM one-loop corrections supplemented with the dominant and sub-dominant two-loop corrections within the Minimal Supersymmetric Standard Model (MSSM). These include contributions at the orders O(α{sub t}α{sub s}, α{sub b}α{sub s}, α{sub t}{sup 2}, α{sub t}α{sub b}), as well as a resummation of leading and subleading logarithms from the top/scalar top sector. Higher-order corrections are essential for the NMSSM in order to provide a Higgs particle that is consistent with the available data, including the observed neutral, CP-even Higgs field with a mass of about 125 GeV. We explored the validity of the applied approximation at the two-loop level and found that it is reliable for a wide range of scenarios within the NMSSM. This is especially true for the mass of the observed (MS)SM-like Higgs field. The result of this work will be included in a future extension of the program FeynHiggs. We also compared our results with the program NMSSMCalc that also performs a Feynman-diagrammatic calculation of the Higgs-masses with a slightly different renormalization scheme. The comparison reveals that for the mass of the (MS)SM-like Higgs field the genuine NMSSM-effects induced by the choice of the renormalization scheme are by far minor compared to similar effects observed in the MSSM.
Higgs windows to new physics through d = 6 operators: Constraints and one-loop anomalous dimensions
Elias-Miro, J; Masso, E; Pomarol, A
2013-01-01
The leading contributions from heavy new physics to Higgs processes can be captured in a model-independent way by dimension-six operators in an effective Lagrangian approach. We present a complete analysis of how these contributions affect Higgs couplings. Under certain well-motivated assumptions, we find that 8 CP-even plus 3 CP-odd Wilson coefficients parametrize the main impact in Higgs physics, as all other coefficients are constrained by non-Higgs SM measurements. We calculate the most relevant anomalous dimensions for these Wilson coefficients, which describe operator mixing from the heavy scale down to the electroweak scale. This allows us to find the leading-log corrections to the predictions for the Higgs couplings in specific models, such as the MSSM or composite Higgs, which we find to be significant in certain cases.
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 induced FCNC as a source of new physics in $b\\to s $ transitions
Joshipura, Anjan S
2009-01-01
The observations in the $B_{s}$ sector suggest the existence of some new physics contribution to the $B_S-\\bar{B}_s$ mixing. We study the implications of a hypothesis that this contribution is generated by the Higgs induced flavour changing neutral currents. We concentrate on the specific $b\\to s$ transition which is described by two complex FCNC parameters $F_{23}$ and $F_{32}$ and parameters in the Higgs sector. Model independent constraints on these parameters are derived from the $B_S-\\bar{B}_s$ mixing and are used to predict the branching ratios for $\\bar{B}_s\\to \\mu^+\\mu^-$ and $\\bar{B}_d\\to \\bar{K}\\mu^+\\mu^-$ numerically by considering general variations in the Higgs parameters assuming that Higgs sector conserves CP. Taking the results on $B_{s}^0-\\bar{B}_{s}^0$ mixing derived by the global analysis of UTfit group as a guide we present the general constraints on $F_{23}^*F_{32}$ in terms of the pseudo-scalar mass $M_A$. The former is required to be in the range $\\sim (1-5) \\times 10^{-11} M_A^2 {\\rm G...
News from LHC: Recent Results on Higgs Physics
Straessner, A; The ATLAS collaboration
2014-01-01
The ATLAS and CMS experiments at the LHC have measured detailed properties of the SM-like Higgs boson discovered in 2012. Results on Higgs boson mass, width, spin and coupling determinations are presented. The parameters observed are furthermore interpreted in extensions to the Standard Model. Searches for additional Higgs bosons predicted in the general 2 Higgs Doublet Model (2HDM) and the Minimal Supersymmetric Standard Model (MSSM) are reported.
The Higgs mechanism and superconductivity: A case study of formal analogies
Fraser, Doreen; Koberinski, Adam
2016-08-01
Following the experimental discovery of the Higgs boson, physicists explained the discovery to the public by appealing to analogies with condensed matter physics. The historical root of these analogies is the analogies to models of superconductivity that inspired the introduction of spontaneous symmetry breaking (SSB) into particle physics in the early 1960s. We offer a historical and philosophical analysis of the analogies between the Higgs model of the electroweak (EW) interaction and the Ginsburg-Landau (GL) and Bardeen-Cooper-Schrieffer (BCS) models of superconductivity, respectively. The conclusion of our analysis is that both sets of analogies are purely formal in virtue of the fact that they are accompanied by substantial physical disanalogies. In particular, the formal analogies do not map the temporal, causal, or modal structures of SSB in superconductivity to temporal, causal, or modal structures in the Higgs model. These substantial physical disanalogies mean that analogies to models of superconductivity cannot supply the basis for the physical interpretation of EW SSB; however, an appreciation of the contrast between the physical interpretations of SSB in superconductivity and the Higgs model does help to clarify some foundational issues. Unlike SSB in superconductivity, SSB in the Higgs sector of the Standard Model (without the addition of new physics) is neither a temporal nor a causal process. We discuss the implications for the 'eating' metaphor for mass gain in the Higgs model. Furthermore, the distinction between the phenomenological GL model and the dynamical BCS model does not carry over to EW models, which clarifies the desiderata for the so-called 'dynamical' models of EW SSB (e.g., minimal technicolor). Finally, the development of the Higgs model is an illuminating case study for philosophers of science because it illustrates how purely formal analogies can play a fruitful heuristic role in physics.
Prospects of LHC Higgs Physics at the end of Run III
Chen, Xin; The ATLAS collaboration
2017-01-01
The document is prepared for the LCWS2016 conference proceedings. The expected status of Higgs physics at the end of Run-3 is presented. The current Run-2 status is briefly reviewed, and the expected Higgs reach after the HL-LHC period is also summarized for some channels.
Top quark and Higgs physics in standard model extensions
Energy Technology Data Exchange (ETDEWEB)
Gonzalez, Patrick Jose
2012-05-25
In this thesis we have studied several extensions of the SM and their implications on the strength and structure of the tbW vertex, on the production and decays of pseudoscalar and heavy Higgs scalars at the LHC, and the effects that models with a fourth generation have on electroweak precision observables. Apart from the SM with a fourth generation of chiral fermions, the extensions we studied all feature an extended electroweak symmetry breaking (EWSB) sector. In the case of the type-II 2HDM and the MSSM, the extended EWSB sector consists of elementary Higgs fields. In the case of Topcolor assisted Technicolor (TC2), which is a model of dynamical EWSB, the scalar and pseudoscalar fields are composite. By scanning over the phenomenologically and theoretically allowed regions of the respective parameters spaces, we determined the largest possible cross sections σ(pp→φ→VV{sup '}) where VV{sup p}rime element of {W"+W"-, ZZγγ, Zγ} for both the heavy scalar and pseudoscalar states in the above models. We found that non-SUSY models with an extended Higgs sector and only three generations, namely the type-II 2HDM and the TC2, still allow for observable pseudoscalar cross sections σ(pp → A → VV') at the LHC. In particular for the final states W{sup +}W{sup -} and γγ. In the MSSM, the discovery of the pseudoscalar A through its decays into electroweak gauge bosons is very unlikely. However, scalar cross sections σ(pp→H→W{sup +}W{sup -}) can still be of observable size at the LHC in large parts of the MSSM parameter space. SM extensions with an extended EWSB sector and four chiral generations are strongly disfavoured; direct Higgs boson searches exclude large parts of the parameter space and it is challenging to bring such an extension into accordance with electroweak precision data. On the other hand, models with additional vector-like quarks and an extended Higgs sector are still viable. The SM with four chiral generations is (still) not
Prospecting for new physics in the Higgs and flavor sectors
Energy Technology Data Exchange (ETDEWEB)
Bishara, Fady [Univ. of Cincinnati, OH (United States)
2015-05-01
We explore two directions in beyond the standard model physics: dark matter model building and probing new sources of CP violation. In dark matter model building, we consider two scenarios where the stability of dark matter derives from the flavor symmetries of the standard model. The first model contains a flavor singlet dark matter candidate whose couplings to the visible sector are proportional to the flavor breaking parameters. This leads to a metastable dark matter with TeV scale mediators. In the second model, we consider a fully gauged SU(3)^{3} flavor model with a flavor triplet dark matter. Consequently, the dark matter multiplet is charged while the standard model fields are neutral under a remnant Z_{3} which ensures dark matter stability. We show that a Dirac fermion dark matter with radiative splitting in the multiplet must have a mass in the range [0:5; 5] TeV in order to satisfy all experimental constraints. We then turn our attention to Higgs portal dark matter and investigate the possibility of obtaining bounds on the up, down, and strange quark Yukawa couplings. If Higgs portal dark matter is discovered, we find that direct detection rates are insensitive to vanishing light quark Yukawa couplings. We then review flavor models and give the expected enhancement or suppression of the Yukawa couplings in those models. Finally, in the last two chapters, we develop techniques for probing CP violation in the Higgs coupling to photons and in rare radiative decays of B mesons. While theoretically clean, we find that these methods are not practical with current and planned detectors. However, these techniques can be useful with a dedicated detector (e.g., a gaseous TPC). In the case of radiative B meson decay B^{0} → (K* → Kππ) γ, the techniques we develop also allow the extraction of the photon polarization fraction which is sensitive to new physics contributions since, in the standard model, the right(left) handed
Beyond-the-Standard-Model Higgs physics using the ATLAS experiment
Vanadia, M
2016-01-01
The ATLAS and CMS experiments at the Large Hadron Collider discovered a new particle, with a mass of 125GeV and properties compatible with that predicted for the Higgs boson by the Standard Model. Understanding if this particle is part of a larger and more complex Higgs sector is one of the major challenges for particle physics experiments. In this report, an overview on latest results obtained on LHC Run-1 data by the ATLAS experiment on Beyond-the-Standard- Model Higgs searches is presented. Searches for new physics in the Higgs sector are presented and interpreted in well-motivated theoretical frameworks, including the two-Higgs-doublet Models and the Minimal and Next-to-Minimal Supersymmetric Standard Model.
From Higgs measurements to constraints on new physics with Lilith
Bernon, Jeremy
2015-01-01
The properties of the observed Higgs boson with mass around 125 GeV are constrained by a wealth of experimental results targeting different combinations for the production and decay of a Higgs boson. In order to assess the compatibility of a non-Standard Model-like Higgs boson with all available results, we present Lilith, a new public tool that makes use of signal strength measurements performed at the LHC and the Tevatron.
Invisible Decays in Higgs Pair Production
Banerjee, Shankha; Spannowsky, Michael
2016-01-01
Observation of Higgs pair production is an important long term objective of the LHC physics program as it will shed light on the scalar potential of the Higgs field and the nature of electroweak symmetry breaking. While numerous studies have examined the impact of new physics on di-Higgs production, little attention has been given to the well-motivated possibility of exotic Higgs decays in this channel. Here we investigate the consequences of exotic invisible Higgs decays in di-Higgs production. We outline a search sensitive to such invisible decays in the $b\\bar b+{\
Latest Higgs Physics results from the ATLAS experiment
Buzatu, Adrian; The ATLAS collaboration
2016-01-01
The presentation will include the last results from the run 1 of the LHC related to the Higgs (125 GeV) boson, and new results from the run-2 at 13 TeV, mostly on the searches for higher mass Higgs bosons, as predicted by several Beyond-Standard-Model theories.
Higgs Branching Ratio Study in CEPC
Institute of Scientific and Technical Information of China (English)
HU; Shou-yang; LIANG; Hao; ZHOU; Jing; LI; Xiao-mei; LI; Xing-long; ZHOU; Shu-hua
2015-01-01
Higgs branching ratio(BR)measurement is one of the important issue of the Circular Electron Positron Collider(CEPC)project,which is strongly related to the coupling strength with particles and reveal their mass generation mechanism.The Large Hadron Collider(LHC)has discovered the Higgs boson in 2012,CEPC can confirm whether that is the standard model(SM)
Electroweak Precision Observables, New Physics and the Nature of a 126 GeV Higgs Boson
Ciuchini, Marco; Mishima, Satoshi; Silvestrini, Luca
2013-01-01
We perform the fit of electroweak precision observables within the Standard Model with a 126 GeV Higgs boson, compare the results with the theoretical predictions and discuss the impact of recent experimental and theoretical improvements. We introduce New Physics contributions in a model-independent way and fit for the S, T and U parameters, for the $\\epsilon_{1,2,3,b}$ ones, for modified $Zb\\bar{b}$ couplings and for a modified Higgs coupling to vector bosons. We point out that composite Higgs models are very strongly constrained. Finally, we compute the bounds on dimension-six operators relevant for the electroweak fit.
Testing Higgs coupling precision and new physics scales at lepton colliders
Ge, Shao-Feng; He, Hong-Jian; Xiao, Rui-Qing
2016-10-01
The next-generation lepton colliders, such as CEPC, FCC-ee, and ILC will make precision measurement of the Higgs boson properties. We first extract the Higgs coupling precision from Higgs observables at CEPC to illustrate the potential of future lepton colliders. Depending on the related event rates, the precision can reach percentage level for most couplings. Then, we try to estimate the new physics scales that can be indirectly probed with Higgs and electroweak precision observables. The Higgs observables, together with the existing electroweak precision observables, can probe new physics up to 10 TeV (40 TeV for the gluon-related operator 𝒪g) at 95% C.L. Including the Z/W mass measurements and Z-pole observables at CEPC further pushes the limit up to 35 TeV. Although Z-pole running is originally for the purpose of machine calibration, it can be as important as the Higgs observables for probing the new physics scales indirectly. The indirect probe of new physics scales at lepton colliders can mainly cover the energy range to be explored by the following hadron colliders of pp (50-100 TeV), such as SPPC and FCC-hh.
Warped extra dimensions. Flavor, precision tests and Higgs physics
Energy Technology Data Exchange (ETDEWEB)
Goertz, Florian
2011-07-01
In this thesis, the phenomenology of the Randall-Sundrum setup is investigated. In this context models with and without an enlarged SU(2){sub L} x SU(2){sub R} x U(1){sub X} x P{sub LR} gauge symmetry, which removes corrections to the T parameter and to the Zb{sub L}b{sub L} coupling, are compared with each other. The Kaluza-Klein decomposition is formulated within the mass basis, which allows for a clear understanding of various model-specific features. A complete discussion of tree-level flavor-changing effects is presented. Exact expressions for five dimensional propagators are derived, including Yukawa interactions that mediate flavor-off-diagonal transitions. The symmetry that reduces the corrections to the left-handed Zbb coupling is analyzed in detail. In the literature, Randall-Sundrum models have been used to address the measured anomaly in the tt forward-backward asymmetry. However, it is shown that this is not possible within a natural approach to flavor. The rare decays t{yields}cZ and t{yields}ch are investigated, where in particular the latter could be observed at the LHC. A calculation of {gamma}{sup B}{sub s12} in the presence of new physics is presented. It is shown that the Randall-Sundrum setup allows for an improved agreement with measurements of A{sup s}{sub SL}, S{sub {psi}}{sub {phi}}, and {delta}{gamma}{sub s}. For the first time, a complete one-loop calculation of all relevant Higgs-boson production and decay channels in the custodial Randall-Sundrum setup is performed, revealing a sensitivity to large new-physics scales at the LHC.
Prospects On Standard Model And Higgs Physics At The HL-LHC
AUTHOR|(INSPIRE)INSPIRE-00221160; The ATLAS collaboration
2016-01-01
The luminosity upgrade of LHC, HL-LHC, will provide a large statistics data set that allows precision measurements of the 125 GeV Higgs boson properties. In particular, couplings to elementary fermions and bosons will be measured at the level of a few \\% accuracy. Searches for Higgs boson pair production and BSM effects in the vector boson scattering, of primary importance in the investigations of the electroweak symmetry breaking mechanism, also represent crucial point in the HL-LHC physics programme.
Identifying new physics contributions in the Higgs sector at linear + - colliders
Indian Academy of Sciences (India)
Santosh Kumar Rai
2007-11-01
Loop-driven decay modes of the Higgs are sensitive to new physics contributions because of new particles in the loops. To highlight this we look at the dilepton-dijet signal in the dominant Higgs production channel at a linear + - collider. We show that by taking a simple ratio between cross-sections of two different final states such contributions can be very easily identified.
Constraints on B and Higgs physics in minimal low energy supersymmetric models
Energy Technology Data Exchange (ETDEWEB)
Carena, Marcela; /Fermilab; Menon, A.; /Argonne /Chicago U., EFI; Noriega-Papaqui, R.; /Fermilab /Puebla U., Inst. Fis.; Szynkman, A.; /Fermilab /Montreal U. /La Plata U.; Wagner, C.E.M.; /Argonne /Chicago U., EFI
2006-03-01
We study the implications of minimal flavor violating low energy supersymmetry scenarios for the search of new physics in the B and Higgs sectors at the Tevatron collider and the LHC. We show that the already stringent Tevatron bound on the decay rate B{sub s} {yields} {mu}{sup +}{mu}{sup -} sets strong constraints on the possibility of generating large corrections to the mass difference {Delta} M{sub s} of the B{sub s} eigenstates. We also show that the B{sub s} {yields} {mu}{sup +}{mu}{sup -} bound together with the constraint on the branching ratio of the rare decay b {yields} s{gamma} has strong implications for the search of light, non-standard Higgs bosons at hadron colliders. In doing this, we demonstrate that the former expressions derived for the analysis of the double penguin contributions in the Kaon sector need to be corrected by additional terms for a realistic analysis of these effects. We also study a specific non-minimal flavor violating scenario, where there are flavor changing gluino-squark-quark interactions, governed by the CKM matrix elements, and show that the B and Higgs physics constraints are similar to the ones in the minimal flavor violating case. Finally we show that, in scenarios like electroweak baryogenesis which have light stops and charginos, there may be enhanced effects on the B and K mixing parameters, without any significant effect on the rate of B{sub s} {yields} {mu}{sup +}{mu}{sup -}.
ATLAS Higgs and Supersymmetry Physics Prospects at the High-Luminosity LHC
Venturi, Nicola; The ATLAS collaboration
2017-01-01
The Higgs physics prospects at the high-luminosity LHC are presented, assuming an energy of sqrt(s) = 14 TeV and a data sample of 3000-4000 fb-1. In particular, the ultimate precision attainable on the couplings measurements of the 125 GeV Higgs boson with SM fermions and bosons is discussed, as well as perspectives on the search for the Standard Model di-Higgs production, which could lead to the measurement of the Higgs boson self-coupling. Scenarios of SUSY sparticle production, among others, have been used as benchmark to drive the design of the component upgrades, and to evaluate the sensitivity of the upgraded accelerator and detector. This talk will also overview the expected sensitivity that the ATLAS experiment will have to SUSY sparticle production with 3000 fb-1 pf proton-proton collisions collected at a centre of mass energy of 14 TeV.
Search of New Physics with Boosted Higgs Boson in Hadronic Final States with ATLAS Detector
Zeng, Qi
The discovery of a Higgs boson at the Large Hadron Collider (LHC) confirms the validity of the Standard Model (SM) in the description of particle interactions at electroweak scale. However, radioactive corrections to the Higgs mass drives its value to the model's validity limit, indicating either extreme fine-tuning or the presence of new physics at higher energy scale. Since 2015, the LHC starts its Run 2 journey with unprecedented center of mass energy of 13 TeV. Along with increase in luminosity, this greatly extends the sensitivity of ATLAS experiment to heavy new particles at TeV scale. In particular, many new physics models beyond the Standard Model manifest themselves through significant coupling to the Higgs boson in decays of new particles to a Higgs boson and other SM particles. In this work, two searches for resonances decaying to either pair of Higgs bosons or a Higgs boson associated with another SM vector boson in all hadronic final states are presented using data collected by ATLAS during Run 2...
TOP AND HIGGS PHYSICS AT THE HADRON COLLIDERS
Energy Technology Data Exchange (ETDEWEB)
Jabeen, Shabnam
2013-10-20
This review summarizes the recent results for top quark and Higgs boson measurements from experiments at Tevatron, a proton–antiproton collider at a center-of-mass energy of √ s =1 . 96 TeV, and the Large Hadron Collider, a proton–proton collider at a center- of-mass energy of √ s = 7 TeV. These results include the discovery of a Higgs-like boson and measurement of its various properties, and measurements in the top quark sector, e.g. top quark mass, spin, charge asymmetry and production of single top quark.
New physics in resonant production of Higgs boson pairs
Barger, Vernon; Jackson, C B; Peterson, Andrea; Shaughnessy, Gabe
2014-01-01
We advocate a search for an extended scalar sector at the LHC via $hh$ production, where $h$ is the 125 GeV Higgs boson. A resonance feature in the $hh$ invariant mass is a smoking gun of an $s$-channel heavy Higgs resonance, $H$. With one $h$ decaying to two photons and the other decaying to $b$-quarks, the resonant signal may be discoverable above the $hh$ continuum background for $M_H<$ 1 TeV. The product of the scalar and top Yukawa couplings can be measured to better than $10-20\\%$ accuracy, and its sign can be inferred from the $hh$ lineshape via interference effects.
Quantum chromodynamics effects in electroweak and Higgs physics
Indian Academy of Sciences (India)
Frank Petriello
2012-10-01
Several examples of the often intricate effects of higher-order quantum chromodynamics (QCD) corrections on predictions for hadron-collider observables, are discussed, using the production of electroweak gauge boson and the Standard Model Higgs boson as examples. Particular attention is given to the interplay of QCD effects and experimental cuts, and to the use of scale variations as estimates of theoretical uncertainties.
Latest Higgs Physics Results with the ATLAS detector
Orestano, Domizia; The ATLAS collaboration
2015-01-01
This report presents the investigations on the recently discovered scalar boson by the ATLAS experiment at the CERN Large Hadron Collider. The latest results fully exploit the data collected during LHC Run 1 to measure the properties of the new boson and within the current sensitivity confirm the identification of this particle with the Higgs boson of the Standard Model.
Latest Higgs Physics results from the ATLAS experiment
De Groot, Nicolo; The ATLAS collaboration
2017-01-01
Since the discovery in 2012, many measurements have been made on the production and prop- erties of the 125 GeV Higgs boson. The latest result from ATLAS will be presented, including recent results from run-1 at 8 TeV and some obtained in run-2 at 13 TeV.
The Higgs Particle: A Useful Analogy for Physics Classrooms
Cid, Xabier; Cid, Ramon
2010-01-01
In November 2009, the largest experiment in history was restarted. Its prime target is the Higgs particle--the last remaining undiscovered piece of our current theory of matter. We present a very simple way to introduce this topic to senior secondary school students, using a comparison with the refractive index of light.
Impact of flavor and Higgs physics on theories beyond the standard model
Energy Technology Data Exchange (ETDEWEB)
Casagrande, Sandro
2013-02-13
Quantum effects of physics beyond the Standard Model receive strong indirect constraints from precisely measured collider observables. In the conceptual part of this thesis, we apply the generic relations between particle interactions in perturbatively unitary theories to calculate one-loop amplitudes for flavor physics. We provide template results applicable for any model of this class. We also investigate example models that are partly and such that are not perturbatively unitary: the Littlest Higgs model and Randall-Sundrum models. The latter have a unique coupling structure, which we cover exhaustively. We find strong constraints on the Randall-Sundrum models and numerically compare those from flavor, electroweak precision, and Higgs physics by performing detailed parameter scans. We observe interesting correlations between flavor observables, and we find that constraints from Higgs production and decays are already competitive.
Telnov, V I
2013-01-01
Over the past two decades, the high energy physics community has been actively discussing and developing a number of post-LHC collider projects; however, none of them have been approved due to high costs and the uncertainty in post-LHC physics scenarios. There have been great expectations of rich new physics in the 0.1-1 TeV mass region: the Higgs boson (one or several), supersymmetry, or perhaps new particles from the dark-matter family. It has been the general consensus that the best machine for the detailed study of new physics to be discovered at the LHC would be an energy-frontier linear e+e- collider. Physicists held their breath waiting for the results from the LHC. In summer 2012, two LHC detectors, ATLAS and CMS, announced the discovery of a Higgs boson with the mass of 126 GeV and (still) nothing else. The absence of new physics in the region below 1 TeV has changed the post-LHC collider R&D priorities and triggered a zoo of project proposals for the precision study of the 126 GeV Higgs boson, p...
Higgs Physics at future Linear Colliders - A Case for precise Vertexing
Simon, Frank
2014-01-01
The discovery of a Higgs boson by the experiments at the LHC marks a major breakthrough in particle physics, with far-reaching consequences for our understanding of the fundamental principles of our Universe. To fully explore this unique particle, experiments at high-energy electron-positron colliders are being planned, providing substantial added benefit over the capabilities of the LHC alone, such as model-independent measurements of couplings, constraints on invisible decays and precise measurements of the self-coupling. This contribution summarizes the Higgs physics program at such future facilities, highlighting in particular also the role of precise vertexing in achieving the ambitious goals of these experiments.
New Physics Opportunities in the Boosted Di-Higgs-Boson Plus Missing Transverse Energy Signature
Kang, Zhaofeng; Ko, P.; Li, Jinmian
2016-04-01
The Higgs field in the standard model may couple to new physics sectors related to dark matter and/or massive neutrinos. In this Letter we propose a novel signature, the boosted di-Higgs-boson plus ET (which is either a dark matter or neutrino), to probe those new physics sectors. In a large class of models, in particular, the supersymmetric standard models and low scale seesaw mechanisms, this signature can play a key role. The signature has a clear background, and at the √{s }=14 TeV high luminosity LHC, we can probe it with a production rate as low as ˜0.1 fb . We apply it to benchmark models, supersymmetry in the bino-Higgsino limit, the canonical seesaw model, and the little Higgs model, finding that the masses of the Higgsino, right-handed neutrino, and heavy vector boson can be probed up to ˜500 , 650, and 900 GeV, respectively.
Simplified Models for Higgs Physics: Singlet Scalar and Vector-like Quark Phenomenology
Dolan, Matthew J; Krämer, M; Rizzo, T G
2016-01-01
Simplified models provide a useful tool to conduct the search and exploration of physics beyond the Standard Model in a model-independent fashion. In this work we consider the complementarity of indirect searches for new physics in Higgs couplings and distributions with direct searches for new particles, using a simplified model which includes a new singlet scalar resonance and vector-like fermions that can mix with the SM top-quark. We fit this model to the combined ATLAS and CMS 125 GeV Higgs production and coupling measurements and other precision electroweak constraints, and explore in detail the effects of the new matter content upon Higgs production and kinematics. We highlight some novel features and decay modes of the top partner phenomenology, and discuss prospects for Run II.
Simplified models for Higgs physics: singlet scalar and vector-like quark phenomenology
Dolan, Matthew J.; Hewett, J. L.; Krämer, M.; Rizzo, T. G.
2016-07-01
Simplified models provide a useful tool to conduct the search and exploration of physics beyond the Standard Model in a model-independent fashion. In this work we consider the complementarity of indirect searches for new physics in Higgs couplings and distributions with direct searches for new particles, using a simplified model which includes a new singlet scalar resonance and vector-like fermions that can mix with the SM top-quark. We fit this model to the combined ATLAS and CMS 125 GeV Higgs production and coupling measurements and other precision electroweak constraints, and explore in detail the effects of the new matter content upon Higgs production and kinematics. We highlight some novel features and decay modes of the top partner phenomenology, and discuss prospects for Run II.
New physics in resonant production of Higgs boson pairs.
Barger, Vernon; Everett, Lisa L; Jackson, C B; Peterson, Andrea D; Shaughnessy, Gabe
2015-01-09
We advocate a search for an extended scalar sector at the LHC via hh production, where h is the 125 GeV Higgs boson. A resonance feature in the hh invariant mass is a smoking gun of an s-channel heavy Higgs resonance, H. With one h decaying to two photons and the other decaying to b quarks, the resonant signal may be discoverable above the hh continuum background for M(H)<1 TeV. The product of the scalar and top Yukawa couplings can be measured to better than 10%-20% accuracy, and its sign can be inferred from the hh line shape via interference effects.
HIGGS PHYSICS WITH A GAMMA GAMMA COLLIDER BASED ON CLIC 1*.
Energy Technology Data Exchange (ETDEWEB)
ASNER,D.; BURKHARDT,H.; DE ROECK,A.; ELLIS,J.; GRONBERG,J.; HEINEMEYER,S.; SCHMITT,M.; SCHULTE,D.; VELASCO,M.; ZIMMERMAN,F.
2001-11-01
We present the machine parameters and physics capabilities of the CLIC Higgs Experiment (CLICHE), a low-energy {gamma}{gamma} collider based on CLIC 1, the demonstration project for the higher-energy two-beam accelerator CLIC. CLICHE is conceived as a factory capable of producing around 20,000 light Higgs bosons per year. We discuss the requirements for the CLIC 1 beams and a laser backscattering system capable of producing a {gamma}{gamma} total (peak) luminosity of 2.0 (0.36) x 10{sup 34} cm{sup -2} s{sup -1} with E{sub CM}({gamma}{gamma}) 115 GeV. We show how CLICHE could be used to measure accurately the mass, {bar b}b, WW and {gamma}{gamma} decays of a light Higgs boson. We illustrate how these measurements may distinguish between the Standard Model Higgs boson and those in supersymmetric and more general two-Higgs-doublet models, complementing the measurements to be made with other accelerators. We also comment on other prospects in {gamma}{gamma} and e{sup -}{gamma} physics with CLICHE.
HIGGS PHYSICS WITH A GAMMA GAMMA COLLIDER BASED ON CLIC 1*.
Energy Technology Data Exchange (ETDEWEB)
ASNER,D.; BURKHARDT,H.; DE ROECK,A.; ELLIS,J.; GRONBERG,J.; HEINEMEYER,S.; SCHMITT,M.; SCHULTE,D.; VELASCO,M.; ZIMMERMAN,F.
2001-11-01
We present the machine parameters and physics capabilities of the CLIC Higgs Experiment (CLICHE), a low-energy {gamma}{gamma} collider based on CLIC 1, the demonstration project for the higher-energy two-beam accelerator CLIC. CLICHE is conceived as a factory capable of producing around 20,000 light Higgs bosons per year. We discuss the requirements for the CLIC 1 beams and a laser backscattering system capable of producing a {gamma}{gamma} total (peak) luminosity of 2.0 (0.36) x 10{sup 34} cm{sup -2} s{sup -1} with E{sub CM}({gamma}{gamma}) 115 GeV. We show how CLICHE could be used to measure accurately the mass, {bar b}b, WW and {gamma}{gamma} decays of a light Higgs boson. We illustrate how these measurements may distinguish between the Standard Model Higgs boson and those in supersymmetric and more general two-Higgs-doublet models, complementing the measurements to be made with other accelerators. We also comment on other prospects in {gamma}{gamma} and e{sup -}{gamma} physics with CLICHE.
Higgs Boson Studies at the Tevatron
Aaltonen, T.; Abbott, B.; Acharya, B.S.; Adams, M.; Adams, T.; Alexeev, G.D.; Alkhazov, G.; Alton, A.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Askew, A.; Atkins, S.; Auerbach, B.; Augsten, K.; Aurisano, A.; Avila, C.; Azfar, F.; Badaud, F.; Badgett, W.; Bae, T.; Bagby, L.; Baldin, B.; Bandurin, D.V.; Banerjee, S.; Barbaro-Galtieri, A.; Barberis, E.; Baringer, P.; Barnes, V.E.; Barnett, B.A.; Barria, P.; Bartlett, J.F.; Bartos, P.; Bassler, U.; Bauce, M.; Bazterra, V.; Bean, A.; Bedeschi, F.; Begalli, M.; Behari, S.; Bellantoni, L.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Beri, S.B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besancon, M.; Beuselinck, R.; Bhat, P.C.; Bhatia, S.; Bhatnagar, V.; Bhatti, A.; Bland, K.R.; Blazey, G.; Blessing, S.; Bloom, K.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Boehnlein, A.; Boline, D.; Boos, E.E.; Borissov, G.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brandt, A.; Brandt, O.; Brigliadori, L.; Brock, R.; Bromberg, C.; Bross, A.; Brown, D.; Brucken, E.; Budagov, J.; Bu, X.B.; Budd, H.S.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Burkett, K.; Busetto, G.; Bussey, P.; Buszello, C.P.; Butti, P.; Buzatu, A.; Calamba, A.; Camacho-Perez, E.; Camarda, S.; Campanelli, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Casal, B.; Casarsa, M.; Casey, B.C.K.; Castilla-Valdez, H.; Castro, A.; Catastini, P.; Caughron, S.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chakrabarti, S.; Chakraborty, D.; Chan, K.M.; Chandra, A.; Chapon, E.; Chen, G.; Chen, Y.C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Cho, K.; Cho, S.W.; Choi, S.; Chokheli, D.; Choudhary, B.; Cihangir, S.; Ciocci, M.A.; Claes, D.; Clark, A.; Clarke, C.; Clutter, J.; Convery, M.E.; Conway, J.; Cooke, M.; Cooper, W.E.; Corbo, M.; Corcoran, M.; Cordelli, M.; Couderc, F.; Cousinou, M.C.; Cox, C.A.; Cox, D.J.; Cremonesi, M.; Cruz, D.; Cuevas, J.; Culbertson, R.; Cutts, D.; d'Ascenzo, N.; Das, A.; Datta, M.; Davies, G.; de Barbaro, P.; de Jong, S., J.; De La Cruz-Burelo, E.; Deliot, F.; Demina, R.; Demortier, L.; Deninno, M.; Denisov, D.; Denisov, S.P.; d'Errico, M.; Desai, S.; Deterre, C.; DeVaughan, K.; Devoto, F.; Di Canto, A.; Di Ruzza, B.; Diehl, H.T.; Diesburg, M.; Ding, P.F.; Dittmann, J.R.; Dominguez, A.; Donati, S.; D'Onofrio, M.; Dorigo, M.; Driutti, A.; Dubey, A.; Dudko, L.V.; Duperrin, A.; Dutt, S.; Dyshkant, A.; Eads, M.; Ebina, K.; Edgar, R.; Edmunds, D.; Elagin, A.; Ellison, J.; Elvira, V.D.; Enari, Y.; Erbacher, R.; Errede, S.; Esham, B.; Eusebi, R.; Evans, H.; Evdokimov, V.N.; Facini, G.; Farrington, S.; Faure, A.; Feng, L.; Ferbel, T.; Fernandez Ramos, J.P.; Fiedler, F.; Field, R.; Filthaut, F.; Fisher, W.; Fisk, H.E.; Flanagan, G.; Forrest, R.; Fortner, M.; Fox, H.; Franklin, M.; Freeman, J.C.; Frisch, H.; Fuess, S.; Funakoshi, Y.; Garcia-Bellido, A.; Garcia-Gonzalez, J.A.; Garcia-Guerra, G.A.; Garfinkel, A.F.; Garosi, P.; Gavrilov, V.; Geng, W.; Gerber, C.E.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Gibson, K.; Ginsburg, C.M.; Ginther, G.; Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Golossanov, A.; Golovanov, G.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; Gonzalez Lopez, O.; Gorelov, I.; Goshaw, A.T.; Goulianos, K.; Gramellini, E.; Grannis, P.D.; Greder, S.; Greenlee, H.; Grenier, G.; Grinstein, S.; Gris, Ph.; Grivaz, J.F.; Grohsjean, A.; Grosso-Pilcher, C.; Group, R.C.; Grunendahl, S.; Grunewald, M.W.; Guillemin, T.; Guimaraes da Costa, J.; Gutierrez, G.; Gutierrez, P.; Hahn, S.R.; Haley, J.; Han, J.Y.; Han, L.; Happacher, F.; Hara, K.; Harder, K.; Hare, M.; Harel, A.; Harr, R.F.; Harrington-Taber, T.; Hatakeyama, K.; Hauptman, J.M.; Hays, C.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinrich, J.; Heinson, A.P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herndon, M.; Herner, K.; Hesketh, G.; Hildreth, M.D.; Hirosky, R.; Hoang, T.; Hobbs, J.D.; Hocker, A.; Hoeneisen, B.; Hogan, J.; Hohlfeld, M.; Hong, Z.; Hopkins, W.; Hou, S.; Howley, I.; Hubacek, Z.; Hughes, R.E.; Husemann, U.; Hussein, M.; Huston, J.; Hynek, V.; Iashvili, I.; Ilchenko, Y.; Illingworth, R.; Introzzi, G.; Iori, M.; Ito, A.S.; Ivanov, A.; Jabeen, S.; Jaffre, M.; James, E.; Jang, D.; Jayasinghe, A.; Jayatilaka, B.; Jeon, E.J.; Jeong, M.S.; Jesik, R.; Jiang, P.; Jindariani, S.; Johns, K.; Johnson, E.; Johnson, M.; Jonckheere, A.; Jones, M.; Jonsson, P.; Joo, K.K.; Joshi, J.; Jun, S.Y.; Jung, A.W.; Junk, T.R.; Juste, A.; Kajfasz, E.; Kambeitz, M.; Kamon, T.; Karchin, P.E.; Karmanov, D.; Kasmi, A.; Kato, Y.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Ketchum, W.; Keung, J.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y.N.; Kilminster, B.; Kim, D.H.; Kim, H.S.; Kim, J.E.; Kim, M.J.; Kim, S.B.; Kim, S.H.; Kim, Y.J.; Kim, Y.K.; Kimura, N.; Kirby, M.; Kiselevich, I.; Knoepfel, K.; Kohli, J.M.; Kondo, K.; Kong, D.J.; Konigsberg, J.; Kotwal, A.V.; Kozelov, A.V.; Kraus, J.; Kreps, M.; Kroll, J.; Kruse, M.; Kuhr, T.; Kumar, A.; Kupco, A.; Kurata, M.; Kurca, T.; Kuzmin, V.A.; Laasanen, A.T.; Lammel, S.; Lammers, S.; Lancaster, M.; Lannon, K.; Latino, G.; Lebrun, P.; Lee, Hyeon-Seung; Lee, Hyun Su; Lee, J.S.; Lee, S.W.; Lee, W.M.; Lei, X.; Lellouch, J.; Leo, S.; Leone, S.; Lewis, J.D.; Li, D.; Li, D.; Li, H.; Li, L.; Li, Q.Z.; Lim, J.K.; Limosani, A.; Lincoln, D.; Linnemann, J.; Lipaev, V.V.; Lipeles, E.; Lipton, R.; Lister, A.; Liu, H.; Liu, H.; Liu, Q.; Liu, T.; Liu, Y.; Lobodenko, A.; Lockwitz, S.; Loginov, A.; Lokajicek, M.; Lopes de Sa, R.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Luna-Garcia, R.; Lungu, G.; Lyon, A.L.; Lys, J.; Lysak, R.; Maciel, A.K.A.; Madar, R.; Madrak, R.; Maestro, P.; Magana-Villalba, R.; Malik, S.; Malik, S.; Malyshev, V.L.; Manca, G.; Manousakis-Katsikakis, A.; Mansour, J.; Margaroli, F.; Marino, P.; Martinez, M.; Martinez-Ortega, J.; Matera, K.; Mattson, M.E.; Mazzacane, A.; Mazzanti, P.; McCarthy, R.; McGivern, C.L.; McNulty, R.; Mehta, A.; Mehtala, P.; Meijer, M.M.; Melnitchouk, A.; Menezes, D.; Mercadante, P.G.; Merkin, M.; Mesropian, C.; Meyer, A.; Meyer, J.; Miao, T.; Miconi, F.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Mondal, N.K.; Moon, C.S.; Moore, R.; Morello, M.J.; Mukherjee, A.; Mulhearn, M.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nagy, E.; Naimuddin, M.; Nakano, I.; Napier, A.; Narain, M.; Nayyar, R.; Neal, H.A.; Negret, J.P.; Nett, J.; Neu, C.; Neustroev, P.; Nguyen, H.T.; Nigmanov, T.; Nodulman, L.; Noh, S.Y.; Norniella, O.; Nunnemann, T.; Oakes, L.; Oh, S.H.; Oh, Y.D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Orduna, J.; Ortolan, L.; Osman, N.; Osta, J.; Padilla, M.; Pagliarone, C.; Pal, A.; Palencia, E.; Palni, P.; Papadimitriou, V.; Parashar, N.; Parihar, V.; Park, S.K.; Parker, W.; Partridge, R.; Parua, N.; Patwa, A.; Pauletta, G.; Paulini, M.; Paus, C.; Penning, B.; Perfilov, M.; Peters, Y.; Petridis, K.; Petrillo, G.; Petroff, P.; Phillips, T.J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pleier, M.A.; Podesta-Lerma, P.L.M.; Podstavkov, V.M.; Pondrom, L.; Popov, A.V.; Poprocki, S.; Potamianos, K.; Pranko, A.; Prewitt, M.; Price, D.; Prokopenko, N.; Prokoshin, F.; Ptohos, F.; Punzi, G.; Qian, J.; Quadt, A.; Quinn, B.; Rangel, M.S.; Ranjan, N.; Ratoff, P.N.; Razumov, I.; Redondo Fernandez, I.; Renton, P.; Rescigno, M.; Rimondi, F.; Ripp-Baudot, I.; Ristori, L.; Rizatdinova, F.; Robson, A.; Rodriguez, T.; Rolli, S.; Rominsky, M.; Ronzani, M.; Roser, R.; Rosner, J.L.; Ross, A.; Royon, C.; Rubinov, P.; Ruchti, R.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Sajot, G.; Sakumoto, W.K.; Sakurai, Y.; Salcido, P.; Sanchez-Hernandez, A.; Sanders, M.P.; Santi, L.; Santos, A.S.; Sato, K.; Savage, G.; Saveliev, V.; Savoy-Navarro, A.; Sawyer, L.; Scanlon, T.; Schamberger, R.D.; Scheglov, Y.; Schellman, H.; Schlabach, P.; Schmidt, E.E.; Schwanenberger, C.; Schwarz, T.; Schwienhorst, R.; Scodellaro, L.; Scuri, F.; Seidel, S.; Seiya, Y.; Sekaric, J.; Semenov, A.; Severini, H.; Sforza, F.; Shabalina, E.; Shalhout, S.Z.; Shary, V.; Shaw, S.; Shchukin, A.A.; Shears, T.; Shepard, P.F.; Shimojima, M.; Shivpuri, R.K.; Shochet, M.; Shreyber-Tecker, I.; Simak, V.; Simonenko, A.; Sinervo, P.; Skubic, P.; Slattery, P.; Sliwa, K.; Smirnov, D.; Smith, J.R.; Smith, K.J.; Snider, F.D.; Snow, G.R.; Snow, J.; Snyder, S.; Soldner-Rembold, S.; Song, H.; Sonnenschein, L.; Sorin, V.; Soustruznik, K.; Stancari, M.; St. Denis, R.; Stark, J.; Stelzer, B.; Stelzer-Chilton, O.; Stentz, D.; Stoyanova, D.A.; Strauss, M.; Strologas, J.; Sudo, Y.; Sukhanov, A.; Suslov, I.; Suter, L.; Svoisky, P.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng, P.K.; Thom, J.; Thomson, E.; Thukral, V.; Titov, M.; Toback, D.; Tokar, S.; Tokmenin, V.V.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Tsai, Y.T.; Tsybychev, D.; Tuchming, B.; Tully, C.; Ukegawa, F.; Uozumi, S.; Uvarov, L.; Uvarov, S.; Uzunyan, S.; Van Kooten, R.; Van Leeuwen, W.M.; Varelas, N.; Varnes, E.W.; Vasilyev, I.A.; Vazquez, F.; Velev, G.; Vellidis, C.; Verkheev, A.Y.; Vernieri, C.; Vertogradov, L.S.; Verzocchi, M.; Vesterinen, M.; Vidal, M.; Vilanova, D.; Vilar, R.; Vizan, J.; Vogel, M.; Vokac, P.; Volpi, G.; Wagner, P.; Wahl, H.D.; Wallny, R.; Wang, S.M.; Wang, M.H.L.S.; Wang, R.J.; Warburton, A.; Warchol, J.; Waters, D.; Watts, G.; Wayne, M.; Weichert, J.; Welty-Rieger, L.; Wester, W.C., III; White, A.; Whiteson, D.; Wicke, D.; Wicklund, A.B.; Wilbur, S.; Williams, H.H.; Williams, M.R.J.; Wilson, G.W.; Wilson, J.S.; Wilson, P.; Winer, B.L.; Wittich, P.; Wobisch, M.; Wolbers, S.; Wolfe, H.; Wood, D.R.; Wright, T.; Wu, X.; Wu, Z.; Wyatt, T.R.; Xie, Y.; Yamada, R.; Yamamoto, K.; Yamato, D.; Yang, S.; Yang, T.; Yang, U.K.; Yang, Y.C.; Yao, W.M.; Yasuda, T.; Yatsunenko, Y.A.; Ye, W.; Ye, Z.; Yeh, G.P.; Yi, K.; Yin, H.; Yip, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Youn, S.W.; Yu, G.B.; Yu, I.; Yu, J.M.; Zanetti, A.; Zeng, Y.; Zennamo, J.; Zhao, T.G.; Zhou, B.; Zhou, C.; Zhu, J.; Zielinski, M.; Zieminska, D.; Zivkovic, L.; Zucchelli, S.
2013-09-17
We combine searches by the CDF and D0 Collaborations for the standard model Higgs boson with mass in the range 90--200 GeV/c^2 produced in the gluon-gluon fusion, WH, ZH, ttbarH, and vector boson fusion processes, and decaying in the H->bbbar, H->W^+W^-, H->ZZ, H->\\tau^+\\tau^-, and H->\\gamma \\gamma\\ modes. The data correspond to integrated luminosities of up to 10 fb^-1 and were collected at the Fermilab Tevatron in ppbar collisions at sqrt(s)=1.96 TeV. The searches are also interpreted in the context of fermiophobic and fourth generation models. We observe a significant excess of events in the mass range between 115 and 140 GeV/c^2. The local significance corresponds to 3.1 standard deviations at m_H=125 GeV/c^2, consistent with the mass of the Higgs boson observed at the LHC. Furthermore, we separately combine searches for H->bbbar, H->W^+W^-, H->\\tau^+\\tau^-, and H->\\gamma \\gamma. The observed signal strengths in all channels are consistent with the presence of a standard model Higgs boson with a mass of 1...
Higgs boson studies at the Tevatron
Aaltonen, T.; Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Agnew, J. P.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Askew, A.; Atkins, S.; Auerbach, B.; Augsten, K.; Aurisano, A.; Avila, C.; Azfar, F.; Badaud, F.; Badgett, W.; Bae, T.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barbaro-Galtieri, A.; Barberis, E.; Baringer, P.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartlett, J. F.; Bartos, P.; Bassler, U.; Bauce, M.; Bazterra, V.; Bean, A.; Bedeschi, F.; Begalli, M.; Behari, S.; Bellantoni, L.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besançon, M.; Beuselinck, R.; Bhat, P. C.; Bhatia, S.; Bhatnagar, V.; Bhatti, A.; Bland, K. R.; Blazey, G.; Blessing, S.; Bloom, K.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Boehnlein, A.; Boline, D.; Boos, E. E.; Borissov, G.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brandt, A.; Brandt, O.; Brigliadori, L.; Brock, R.; Bromberg, C.; Bross, A.; Brown, D.; Brucken, E.; Budagov, J.; Bu, X. B.; Budd, H. S.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Burkett, K.; Busetto, G.; Bussey, P.; Buszello, C. P.; Butti, P.; Buzatu, A.; Calamba, A.; Camacho-Pérez, E.; Camarda, S.; Campanelli, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Casal, B.; Casarsa, M.; Casey, B. C. K.; Castilla-Valdez, H.; Castro, A.; Catastini, P.; Caughron, S.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chakrabarti, S.; Chan, K. M.; Chandra, A.; Chapon, E.; Chen, G.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Cho, K.; Cho, S. W.; Choi, S.; Chokheli, D.; Choudhary, B.; Cihangir, S.; Ciocci, M. A.; Claes, D.; Clark, A.; Clarke, C.; Clutter, J.; Convery, M. E.; Conway, J.; Cooke, M.; Cooper, W. E.; Corbo, M.; Corcoran, M.; Cordelli, M.; Couderc, F.; Cousinou, M.-C.; Cox, C. A.; Cox, D. J.; Cremonesi, M.; Cruz, D.; Cuevas, J.; Culbertson, R.; Cutts, D.; d'Ascenzo, N.; Das, A.; Datta, M.; Davies, G.; De Barbaro, P.; de Jong, S. J.; De La Cruz-Burelo, E.; Déliot, F.; Demina, R.; Demortier, L.; Deninno, M.; Denisov, D.; Denisov, S. P.; d'Errico, M.; Desai, S.; Deterre, C.; DeVaughan, K.; Devoto, F.; Di Canto, A.; Di Ruzza, B.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; Dittmann, J. R.; Dominguez, A.; Donati, S.; D'Onofrio, M.; Dorigo, M.; Driutti, A.; Dubey, A.; Dudko, L. V.; Duperrin, A.; Dutt, S.; Eads, M.; Ebina, K.; Edgar, R.; Edmunds, D.; Elagin, A.; Ellison, J.; Elvira, V. D.; Enari, Y.; Erbacher, R.; Errede, S.; Esham, B.; Eusebi, R.; Evans, H.; Evdokimov, V. N.; Facini, G.; Farrington, S.; Fauré, A.; Feng, L.; Ferbel, T.; Fernández Ramos, J. P.; Fiedler, F.; Field, R.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Flanagan, G.; Forrest, R.; Fortner, M.; Fox, H.; Franklin, M.; Freeman, J. C.; Frisch, H.; Fuess, S.; Funakoshi, Y.; Garcia-Bellido, A.; García-González, J. A.; Garfinkel, A. F.; Garosi, P.; Gavrilov, V.; Geng, W.; Gerber, C. E.; Gerberich, H.; Gerchtein, E.; Gershtein, Y.; Giagu, S.; Giakoumopoulou, V.; Gibson, K.; Ginsburg, C. M.; Ginther, G.; Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Golossanov, A.; Golovanov, G.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González López, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gramellini, E.; Grannis, P. D.; Greder, S.; Greenlee, H.; Grenier, G.; Grinstein, S.; Gris, Ph.; Grivaz, J.-F.; Grohsjean, A.; Grosso-Pilcher, C.; Group, R. C.; Grünendahl, S.; Grünewald, M. W.; Guillemin, T.; Guimaraes da Costa, J.; Gutierrez, G.; Gutierrez, P.; Hahn, S. R.; Haley, J.; Han, J. Y.; Han, L.; Happacher, F.; Hara, K.; Harder, K.; Hare, M.; Harel, A.; Harr, R. F.; Harrington-Taber, T.; Hatakeyama, K.; Hauptman, J. M.; Hays, C.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinrich, J.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herndon, M.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hocker, A.; Hoeneisen, B.; Hogan, J.; Hohlfeld, M.; Holzbauer, J. L.; Hong, Z.; Hopkins, W.; Hou, S.; Howley, I.; Hubacek, Z.; Hughes, R. E.; Husemann, U.; Hussein, M.; Huston, J.; Hynek, V.; Iashvili, I.; Ilchenko, Y.; Illingworth, R.; Introzzi, G.; Iori, M.; Ito, A. S.; Ivanov, A.; Jabeen, S.; Jaffré, M.; James, E.; Jang, D.; Jayasinghe, A.; Jayatilaka, B.; Jeon, E. J.; Jeong, M. S.; Jesik, R.; Jiang, P.; Jindariani, S.; Johns, K.; Johnson, E.; Johnson, M.; Jonckheere, A.; Jones, M.; Jonsson, P.; Joo, K. K.; Joshi, J.; Jun, S. Y.; Jung, A. W.; Junk, T. R.; Juste, A.; Kajfasz, E.; Kambeitz, M.; Kamon, T.; Karchin, P. E.; Karmanov, D.; Kasmi, A.; Kato, Y.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Ketchum, W.; Keung, J.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. J.; Kim, Y. K.; Kimura, N.; Kirby, M.; Kiselevich, I.; Knoepfel, K.; Kohli, J. M.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kozelov, A. V.; Kraus, J.; Kreps, M.; Kroll, J.; Kruse, M.; Kuhr, T.; Kumar, A.; Kupco, A.; Kurata, M.; Kurča, T.; Kuzmin, V. A.; Laasanen, A. T.; Lammel, S.; Lammers, S.; Lancaster, M.; Lannon, K.; Latino, G.; Lebrun, P.; Lee, H. S.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Lee, W. M.; Lei, X.; Lellouch, J.; Leo, S.; Leone, S.; Lewis, J. D.; Li, D.; Li, H.; Li, L.; Li, Q. Z.; Lim, J. K.; Limosani, A.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipeles, E.; Lipton, R.; Lister, A.; Liu, H.; Liu, H.; Liu, Q.; Liu, T.; Liu, Y.; Lobodenko, A.; Lockwitz, S.; Loginov, A.; Lokajicek, M.; Lopes de Sa, R.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Luna-Garcia, R.; Lungu, G.; Lyon, A. L.; Lys, J.; Lysak, R.; Maciel, A. K. A.; Madar, R.; Madrak, R.; Maestro, P.; Magaña-Villalba, R.; Malik, S.; Malik, S.; Malyshev, V. L.; Manca, G.; Manousakis-Katsikakis, A.; Mansour, J.; Margaroli, F.; Marino, P.; Martínez, M.; Martínez-Ortega, J.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McCarthy, R.; McGivern, C. L.; McNulty, R.; Mehta, A.; Mehtala, P.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Mesropian, C.; Meyer, A.; Meyer, J.; Miao, T.; Miconi, F.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Mondal, N. K.; Moon, C. S.; Moore, R.; Morello, M. J.; Mukherjee, A.; Mulhearn, M.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nagy, E.; Nakano, I.; Napier, A.; Narain, M.; Nayyar, R.; Neal, H. A.; Negret, J. P.; Nett, J.; Neu, C.; Neustroev, P.; Nguyen, H. T.; Nigmanov, T.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Nunnemann, T.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Orduna, J.; Ortolan, L.; Osman, N.; Osta, J.; Pagliarone, C.; Pal, A.; Palencia, E.; Palni, P.; Papadimitriou, V.; Parashar, N.; Parihar, V.; Park, S. K.; Parker, W.; Partridge, R.; Parua, N.; Patwa, A.; Pauletta, G.; Paulini, M.; Paus, C.; Penning, B.; Perfilov, M.; Peters, Y.; Petridis, K.; Petrillo, G.; Pétroff, P.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pleier, M.-A.; Podstavkov, V. M.; Pondrom, L.; Popov, A. V.; Poprocki, S.; Potamianos, K.; Pranko, A.; Prewitt, M.; Price, D.; Prokopenko, N.; Prokoshin, F.; Ptohos, F.; Punzi, G.; Qian, J.; Quadt, A.; Quinn, B.; Ranjan, N.; Ratoff, P. N.; Razumov, I.; Redondo Fernández, I.; Renton, P.; Rescigno, M.; Rimondi, F.; Ripp-Baudot, I.; Ristori, L.; Rizatdinova, F.; Robson, A.; Rodriguez, T.; Rolli, S.; Rominsky, M.; Ronzani, M.; Roser, R.; Rosner, J. L.; Ross, A.; Royon, C.; Rubinov, P.; Ruchti, R.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Sajot, G.; Sakumoto, W. K.; Sakurai, Y.; Sánchez-Hernández, A.; Sanders, M. P.; Santi, L.; Santos, A. S.; Sato, K.; Savage, G.; Saveliev, V.; Savoy-Navarro, A.; Sawyer, L.; Scanlon, T.; Schamberger, R. D.; Scheglov, Y.; Schellman, H.; Schlabach, P.; Schmidt, E. E.; Schwanenberger, C.; Schwarz, T.; Schwienhorst, R.; Scodellaro, L.; Scuri, F.; Seidel, S.; Seiya, Y.; Sekaric, J.; Semenov, A.; Severini, H.; Sforza, F.; Shabalina, E.; Shalhout, S. Z.; Shary, V.; Shaw, S.; Shchukin, A. A.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.; Shreyber-Tecker, I.; Simak, V.; Simonenko, A.; Sinervo, P.; Skubic, P.; Slattery, P.; Sliwa, K.; Smirnov, D.; Smith, J. R.; Snider, F. D.; Snow, G. R.; Snow, J.; Snyder, S.; Söldner-Rembold, S.; Song, H.; Sonnenschein, L.; Sorin, V.; Soustruznik, K.; Stancari, M.; St. Denis, R.; Stark, J.; Stelzer, B.; Stelzer-Chilton, O.; Stentz, D.; Stoyanova, D. A.; Strauss, M.; Strologas, J.; Sudo, Y.; Sukhanov, A.; Suslov, I.; Suter, L.; Svoisky, P.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thomson, E.; Thukral, V.; Titov, M.; Toback, D.; Tokar, S.; Tokmenin, V. V.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Tsai, Y.-T.; Tsybychev, D.; Tuchming, B.; Tully, C.; Ukegawa, F.; Uozumi, S.; Uvarov, L.; Uvarov, S.; Uzunyan, S.; Van Kooten, R.; van Leeuwen, W. M.; Varelas, N.; Varnes, E. W.; Vasilyev, I. A.; Vázquez, F.; Velev, G.; Vellidis, C.; Verkheev, A. Y.; Vernieri, C.; Vertogradov, L. S.; Verzocchi, M.; Vesterinen, M.; Vidal, M.; Vilanova, D.; Vilar, R.; Vizán, J.; Vogel, M.; Vokac, P.; Volpi, G.; Wagner, P.; Wahl, H. D.; Wallny, R.; Wang, S. M.; Wang, M. H. L. S.; Wang, R.-J.; Warburton, A.; Warchol, J.; Waters, D.; Watts, G.; Wayne, M.; Weichert, J.; Welty-Rieger, L.; Wester, W. C., III; Whiteson, D.; Wicklund, A. B.; Wilbur, S.; Williams, H. H.; Williams, M. R. J.; Wilson, G. W.; Wilson, J. S.; Wilson, P.; Winer, B. L.; Wittich, P.; Wobisch, M.; Wolbers, S.; Wolfe, H.; Wood, D. R.; Wright, T.; Wu, X.; Wu, Z.; Wyatt, T. R.; Xie, Y.; Yamada, R.; Yamamoto, K.; Yamato, D.; Yang, S.; Yang, T.; Yang, U. K.; Yang, Y. C.; Yao, W.-M.; Yasuda, T.; Yatsunenko, Y. A.; Ye, W.; Ye, Z.; Yeh, G. P.; Yi, K.; Yin, H.; Yip, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Youn, S. W.; Yu, G. B.; Yu, I.; Yu, J. M.; Zanetti, A.; Zeng, Y.; Zennamo, J.; Zhao, T. G.; Zhou, B.; Zhou, C.; Zhu, J.; Zielinski, M.; Zieminska, D.; Zivkovic, L.; Zucchelli, S.
2013-09-01
We combine searches by the CDF and D0 Collaborations for the standard model Higgs boson with mass in the range 90-200GeV/c2 produced in the gluon-gluon fusion, WH, ZH, tt¯H, and vector boson fusion processes, and decaying in the H→bb¯, H→W+W-, H→ZZ, H→τ+τ-, and H→γγ modes. The data correspond to integrated luminosities of up to 10fb-1 and were collected at the Fermilab Tevatron in pp¯ collisions at s=1.96TeV. The searches are also interpreted in the context of fermiophobic and fourth generation models. We observe a significant excess of events in the mass range between 115 and 140GeV/c2. The local significance corresponds to 3.0 standard deviations at mH=125GeV/c2, consistent with the mass of the Higgs boson observed at the LHC, and we expect a local significance of 1.9 standard deviations. We separately combine searches for H→bb¯, H→W+W-, H→τ+τ-, and H→γγ. The observed signal strengths in all channels are consistent with the presence of a standard model Higgs boson with a mass of 125GeV/c2.
What Precision Electroweak Physics Says About the SU(6)/Sp(6) Little Higgs
Gregoire, T; Wacker, J G; Wacker, Jay G.
2003-01-01
We we study precision electroweak constraints on the close cousin of the Littlest Higgs, the SU(6)/Sp(6) model. We identify a near-oblique limit in which the heavy W' and B' decouple from the light fermions, and then calculate oblique corrections, including one-loop contributions from the extended top sector and the two Higgs doublets. We find regions of parameter space that give acceptably small precision electroweak corrections and only mild fine tuning in the Higgs potential, and also find that the mass of the lightest Higgs boson is relatively unconstrained by precision electroweak data. The fermions from the extended top sector can be as light as 1 TeV, and the W' can be as light as 1.8 TeV. We include an independent breaking scale for the B', which can still have a mass as low as a few hundred GeV.
Study of associated production of W-Higgs boson with the ATLAS detector
AUTHOR|(INSPIRE)INSPIRE-00235896
On the 4$^{th}$ of July 2012 both the ATLAS and CMS experiments announced the observation of a new particle in the search for the Standard Model Higgs boson. This observation contributes to the assignment of the Nobel Prize in Physics 2013 to P. Higgs and F. Englert ``for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN's Large Hadron Collider'' (http://www.nobelprize.org/nobel\\_prizes/physics/). After the discovery, the effort was focused on the study of the properties of the observed particle with data acquired in 2011 and 2012 years. The main goal of this thesis is to present a study of one of the Standard Model (SM) Higgs boson production mechanisms allowed at the Large Hadron Collider (LHC). The presented analysis is focused on the Higgs boson produced in association with a vector boson W and a $H...
Implications Of The Higgs Discovery On Physics Beyond The Standard Model
Das, Dipankar
2015-01-01
In this thesis, we investigate the implications of the LHC Higgs data on different BSM scenarios. Since the data seem to agree with the SM expectations, any nonstandard couplings will be strongly constrained. First we investigate, in a model independent way, the constraints on the nonstandard Higgs couplings with the fermions and the vector bosons in view of high energy unitarity and the measured value of the Higgs to diphoton signal strength. Then we concentrate on a particular BSM scenario, namely, the two Higgs-doublet models (2HDMs). Consistency of the Higgs data with the corresponding SM predictions strongly motivates us to work in the {\\em alignment limit}. In this limit, including the informations of Higgs mass and its SM-like nature, we find many new constraints on the nonstandard masses and $\\tan\\beta$. We also study the constraints on the charged scalar mass arising from the $h\\to \\gamma\\gamma$ signal strength measurements and observe that the charged scalar does not necessarily decouple from the di...
High performance computing system in the framework of the Higgs boson studies
Belyaev, Nikita; The ATLAS collaboration; Velikhov, Vasily; Konoplich, Rostislav
2017-01-01
The Higgs boson physics is one of the most important and promising fields of study in the modern high energy physics. It is important to notice, that GRID computing resources become strictly limited due to increasing amount of statistics, required for physics analyses and unprecedented LHC performance. One of the possibilities to address the shortfall of computing resources is the usage of computer institutes' clusters, commercial computing resources and supercomputers. To perform precision measurements of the Higgs boson properties in these realities, it is also highly required to have effective instruments to simulate kinematic distributions of signal events. In this talk we give a brief description of the modern distribution reconstruction method called Morphing and perform few efficiency tests to demonstrate its potential. These studies have been performed on the WLCG and Kurchatov Institute’s Data Processing Center, including Tier-1 GRID site and supercomputer as well. We also analyze the CPU efficienc...
Allen, Roland E
2013-01-01
The particle recently discovered by the CMS and ATLAS collaborations at CERN is almost certainly a Higgs boson, fulfilling a quest that can be traced back to three seminal high energy papers of 1964, but which is intimately connected to ideas in other areas of physics that go back much further. One might oversimplify the history of the features which (i) give mass to the W and Z particles that mediate the weak nuclear interaction, (ii) effectively break gauge invariance, (iii) eliminate physically unacceptable Nambu-Goldstone bosons, and (iv) give mass to fermions (like the electron) by collectively calling them the London-Anderson-Englert-Brout-Higgs-Guralnik-Hagen-Kibble-Weinberg mechanism. More important are the implications for the future: a Higgs boson appears to point toward supersymmetry, since new physics is required to protect its mass from enormous quantum corrections, while the discovery of neutrino masses seems to point toward grand unification of the nongravitational forces.
ELECTROWEAK PHYSICS AND PRECISION STUDIES.
Energy Technology Data Exchange (ETDEWEB)
MARCIANO, W.
2005-10-24
The utility of precision electroweak measurements for predicting the Standard Model Higgs mass via quantum loop effects is discussed. Current values of m{sub W}, sin{sup 2} {theta}{sub W}(m{sub Z}){sub {ovr MS}} and m{sub t} imply a relatively light Higgs which is below the direct experimental bound but possibly consistent with Supersymmetry expectations. The existence of Supersymmetry is further suggested by a 2{sigma} discrepancy between experiment and theory for the muon anomalous magnetic moment. Constraints from precision studies on other types of ''New Physics'' are also briefly described.
Status of searches for Higgs and physics beyond the standard model at CDF
Energy Technology Data Exchange (ETDEWEB)
Tsybychev, D.; /Florida U.
2004-12-01
This article presents selected experimental results on searches for Higgs and physics beyond the standard model (BSM) at the Collider Detector at Fermilab (CDF). The results are based on about 350 pb{sup -1} of proton-antiproton collisions data at {radical}s = 1.96 TeV, collected during Run II of the Tevatron. No evidence of signal was found and limits on the production cross section of various physics processes BSM are derived.
Signals of CP Violation Beyond the MSSM in Higgs and Flavor Physics
Altmannshofer, Wolfgang; Gori, Stefania; de la Puente, Alejandro
2011-01-01
We study an extension of the Higgs sector of the Minimal Supersymmetric Standard Model (MSSM), considering the effects of new degrees of freedom at the TeV scale, and allowing for sources of CP violation beyond the MSSM (BMSSM). We analyze the impact of the BMSSM sources of CP violation on the Higgs collider phenomenology and on low energy flavor and CP violating observables. We identify distinct Higgs collider signatures that cannot be realized, either in the case without CP violating phases or in the CP violating MSSM, and investigate the prospects to probe them at the Tevatron and the LHC. The most striking benchmark scenario has three neutral Higgs bosons that all decay dominantly into W boson pairs and that are well within the reach of the 7 TeV LHC run. On the other hand, we also present scenarios with three Higgs bosons that have masses M_Hi > 150 GeV and decay dominantly into b bbar. Such scenarios are much more challenging to probe and can even lie completely outside the reach of the 7 TeV LHC run. W...
Your Higgs number - how fundamental physics is connected to technology and societal revolutions
Lidström, Suzy; Allen, Roland E.
2015-03-01
Fundamental physics, as exemplified by the recently discovered Higgs boson, often appears to be completely disconnected from practical applications and ordinary human life. But this is not really the case, because science, technology, and human affairs are profoundly integrated in ways that are not immediately obvious. We illustrate this by defining a ``Higgs number'' through overlapping activities. Following three different paths, which end respectively in applications of the World Wide Web, digital photography, and modern electronic devices, we find that most people have a Higgs number of no greater than 3. Specific examples chosen for illustration, with their assigned Higgs numbers, are: LHC experimentalists employing the Worldwide Computing Grid (0) - Timothy Berners-Lee (1) - Marissa Mayer, of Google and Yahoo, and Sheryl Sandberg, of Facebook (2) - users of all web-based enterprises (3). CMS and ATLAS experimentalists (0) - particle detector developers (1) - inventors of CCDs and active-pixel sensors (2) - users of digital cameras and camcorders (3). Philip Anderson (0) - John Bardeen (1) - Jack Kilby (2) - users of personal computers, mobile phones, and all other modern electronic devices (3).
Dark matter physics in neutrino specific two Higgs doublet model
Baek, Seungwon
2016-01-01
Although the seesaw mechanism is a natural explanation for the small neutrino masses, there are cases when the Majorana mass terms for the right-handed neutrinos are not allowed due to symmetry. In that case, if neutrino-specific Higgs doublet is introduced, neutrinos become Dirac particles and their small masses can be explained by its small VEV. We show that the same symmetry, which we assume a global $U(1)_X$, can also be used to explain the stability of dark matter. In our model, a new singlet scalar breaks the global symmetry spontaneously down to a discrete $Z_2$ symmetry. The dark matter particle, lightest $Z_2$-odd fermion, is stabilized. We discuss the phenomenology of dark matter: relic density, direct detection, and indirect detection. We find that the relic density can be explained by a novel Goldstone boson channel or by resonance channel. In the most region of parameter space considered, the direct detections is suppressed well below the current experimental bound. Our model can be further teste...
Towards the ultimate SM fit to close in on Higgs physics
Energy Technology Data Exchange (ETDEWEB)
Pomarol, Alex [Departament de Física, Universitat Autònoma de Barcelona,08193 Bellaterra, Barcelona (Spain); Riva, Francesco [Institut de Théorie des Phénomènes Physiques, EPFL,1015 Lausanne (Switzerland)
2014-01-27
With the discovery of the Higgs at the LHC, experiments have finally addressed all aspects of the Standard Model (SM). At this stage, it is important to understand which windows for beyond the SM (BSM) physics are still open, and which are instead tightly closed. We address this question by parametrizing BSM effects with dimension-six operators and performing a global fit to the SM. We separate operators into different groups constrained at different levels, and provide independent bounds on their Wilson coefficients taking into account only the relevant experiments. Our analysis allows to assert in a model-independent way where BSM effects can appear in Higgs physics. In particular, we show that deviations from the SM in the differential distributions of h→Vf-barf are related to other observables, such as triple gauge-boson couplings, and are then already constrained by present data. On the contrary, BR(h→Zγ) can still hide large deviations from the SM.
2014-09-01
A scientific session of the Physical Sciences Division of the Russian Academy of Sciences (RAS) "Physics at the Large Hadron Collider. Higgs boson" was held in the conference hall of the Lebedev Physical Institute, RAS, on 26 February 2014. The agenda of the session, announced on the website http://www.gpad.ac.ru of the Physical Sciences Division, RAS, listed the following reports: (1) Boos E E (Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow) "Standard Model and predictions for the Higgs boson"; (2) Zaytsev A M (National Research Center Kurchatov Institute, Moscow) "ATLAS experiment. The Higgs boson and the Standard Model"; (3) Lanyov A V (Joint Institute for Nuclear Research, Dubna, Moscow region) "CMS collaboration results: Higgs boson and search for new physics"; (4) Kazakov D I (Joint Institute for Nuclear Research, Dubna, Moscow region) "The Higgs boson has been found: what is next?" Papers written on the basis of oral reports 1, 3, and 4 are published below. An extensive review of the topic in item 2 will be published in an upcoming issue of Physics-Uspekhi. • Standard Model and predictions for the Higgs boson, E E Boos Physics-Uspekhi, 2014, Volume 57, Number 9, Pages 912-923 • CMS collaboration results: Higgs boson and search for new physics, A V Lanyov Physics-Uspekhi, 2014, Volume 57, Number 9, Pages 923-930 • The Higgs boson is found: what is next?, D I Kazakov Physics-Uspekhi, 2014, Volume 57, Number 9, Pages 930-942
Higgs couplings and new signals from Flavon-Higgs mixing effects within multi-scalar models
Diaz-Cruz, J. Lorenzo; Saldaña-Salazar, Ulises J.
2016-12-01
Testing the properties of the Higgs particle discovered at the LHC and searching for new physics signals, are some of the most important tasks of Particle Physics today. Current measurements of the Higgs couplings to fermions and gauge bosons, seem consistent with the Standard Model, and when taken as a function of the particle mass, should lay on a single line. However, in models with an extended Higgs sector the diagonal Higgs couplings to up-quarks, down-quarks and charged leptons, could lay on different lines, while non-diagonal flavor-violating Higgs couplings could appear too. We describe these possibilities within the context of multi-Higgs doublet models that employ the Froggatt-Nielsen (FN) mechanism to generate the Yukawa hierarchies. Furthermore, one of the doublets can be chosen to be of the inert type, which provides a viable dark matter candidate. The mixing of the Higgs doublets with the flavon field, can provide plenty of interesting signals, including: i) small corrections to the couplings of the SM-like Higgs, ii) exotic signals from the flavon fields, iii) new signatures from the heavy Higgs bosons. These aspects are studied within a specific model with 3 + 1 Higgs doublets and a singlet FN field. Constraints on the model are derived from the study of K and D mixing and the Higgs search at the LHC. For last, the implications from the latter aforementioned constraints to the FCNC top decay t → ch are presented too.
New Physics Opportunities in the Boosted Di-Higgs-Boson Plus Missing Transverse Energy Signature.
Kang, Zhaofeng; Ko, P; Li, Jinmian
2016-04-01
The Higgs field in the standard model may couple to new physics sectors related to dark matter and/or massive neutrinos. In this Letter we propose a novel signature, the boosted di-Higgs-boson plus E_{T} (which is either a dark matter or neutrino), to probe those new physics sectors. In a large class of models, in particular, the supersymmetric standard models and low scale seesaw mechanisms, this signature can play a key role. The signature has a clear background, and at the sqrt[s]=14 TeV high luminosity LHC, we can probe it with a production rate as low as ∼0.1 fb. We apply it to benchmark models, supersymmetry in the bino-Higgsino limit, the canonical seesaw model, and the little Higgs model, finding that the masses of the Higgsino, right-handed neutrino, and heavy vector boson can be probed up to ∼500, 650, and 900 GeV, respectively.
Drawing physics 2600 year of discovery from Thales to Higgs
Lemons, Don S
2017-01-01
Humans have been trying to understand the physical universe since antiquity. Aristotle had one vision (the realm of the celestial spheres is perfect), and Einstein another (all motion is relativistic). More often than not, these different understandings begin with a simple drawing, a pre-mathematical picture of reality. Such drawings are a humble but effective tool of the physicist's craft, part of the tradition of thinking, teaching, and learning passed down through the centuries. This book uses drawings to help explain fifty-one key ideas of physics accessibly and engagingly. Don Lemons, a professor of physics and author of several physics books, pairs short, elegantly written essays with simple drawings that together convey important concepts from the history of physical science. Lemons proceeds chronologically, beginning with Thales' discovery of triangulation, the Pythagorean monocord, and Archimedes' explanation of balance. He continues through Leonardo's description of -earthshine- (the ghostly glow b...
The Higgs Particle: what is it, and why did it lead to a Nobel Prize in Physics?
2013-01-01
Back in 1964, the theoretical physicists Francois Englert and Robert Brout, as well as Peter Higgs, suggested an explanation for the fact that most elementary particles - such as the electron - have a mass. This scenario predicted a new particle, which has been observed experimentally only just now at CERN (the European Organization for Nuclear Research). This discovery led to the Physics Nobel Prize 2013. Here we sketch in simple terms the concept of the Higgs mechanism, and its importance i...
The ATLAS collaboration
2009-01-01
The discovery of a charged Higgs boson would be tangible proof of physics beyond the Standard Model. This note presents the ATLAS potential for discovering a charged Higgs boson, utilizing five different final states of the signal arising from the three dominating fermionic decay modes of the charged Higgs boson. The search covers the region below the top quark mass, taking into account the present experimental constraints, the transition region with a charged Higgs boson mass of the order of the top quark mass, and the high-mass region with a charged Higgs boson mass up to 600 GeV. All studies are performed with a realistic simulation of the detector response including all three trigger levels and taking into account all dominant systematic uncertainties. Results are given in terms of discovery and exclusion contours for each channel individually and for all channels combined, showing that the ATLAS experiment is capable of detecting the charged Higgs boson in a significant fraction of the (tan beta , mH+-) ...
Brivio, I.; Éboli, O. J. P.; Gavela, M. B.; Gonzalez-García, M. C.; Merlo, L.; Rigolin, S.
2014-12-01
We analyze the leading effective operators which induce a quartic momentum dependence in the Higgs propagator, for a linear and for a non-linear realization of electroweak symmetry breaking. Their specific study is relevant for the understanding of the ultraviolet sensitivity to new physics. Two methods of analysis are applied, trading the Lagrangian coupling by: i) a "ghost" scalar, after the Lee-Wick procedure; ii) other effective operators via the equations of motion. The two paths are shown to lead to the same effective Lagrangian at first order in the operator coefficients. It follows a modification of the Higgs potential and of the fermionic couplings in the linear realization, while in the non-linear one anomalous quartic gauge couplings, Higgs-gauge couplings and gauge-fermion interactions are induced in addition. Finally, all LHC Higgs and other data presently available are used to constrain the operator coefficients; the future impact of pp → 4 leptons data via off-shell Higgs exchange and of vector boson fusion data is considered as well. For completeness, a summary of pure-gauge and gauge-Higgs signals exclusive to non-linear dynamics at leading-order is included.
p-adic description of Higgs mechanism; 5, new physics
Pitkänen, M
1994-01-01
TGD suggests the existence of two new branches of physics, namely M_{89} hadron physics and M_{127} leptohadron physics. Leptons and U type quarks are predicted to have light colored excitations. The anomalous production of e^+e^- pairs in heavy ion collisions sup- ports the existence of light leptomeson but there are objections against light exotics. a) Asymptotic freedom in the standard sense might be lost: the recently identified exotic color bosons however save the situation. b) Z^0 decay width seems to exclude light exotics. The solution of the problem relies on p-adic probability concept. The real counterpart (\\sum_jP(ito j))_R for the sum of p-adic probabi- lities differs from the sum \\sum_j P(i toj)_R for the real counter- parts of p-adic probabilities. Interpretation:(\\sum_jP(i to j))_R is used, when only a common signature for final states is used. \\sum_j(P(i to j)_R is used, when each final state is monitored separately. The total decay rate of Z^0 to unmonitored exotic leptons is sensitive to the ...
Bos(d)-(-B)os(d) Mixing and New Physics Effects in a Top Quark Two-Higgs Doublet Model
Institute of Scientific and Technical Information of China (English)
L(U) Lin-Xia; XIAO Zhen-Jun
2007-01-01
We calculate the new physics contributions to the neutral B0d and B0s meson mass splitting △Md and △Ms induced by the box diagrams involving the charged-Higgs bosons in the top quark two-Higgs doublet model (T2HDM).Using the precision data, we obtain the bounds on the parameter space of the T2HDM: (a) For fixed MH = 400 Ge V and δ = [0°,60°], the upper bound on tanβ is tanβ≤ 30 after the inclusion of major theoretical uncertainties; (b) For the case of tanβ≤ 20, a light charged Higgs boson with a mass around 300 Ge V is allowed; and (c) The bounds on tanβ and MH are strongly correlated: a smaller (larger) tanβ means a lighter (heavier) charged Higgs boson.
Invisible decays in Higgs boson pair production
Banerjee, Shankha; Batell, Brian; Spannowsky, Michael
2017-02-01
Observation of Higgs pair production is an important long term objective of the LHC physics program as it will shed light on the scalar potential of the Higgs field and the nature of electroweak symmetry breaking. While numerous studies have examined the impact of new physics on di-Higgs production, little attention has been given to the well-motivated possibility of exotic Higgs decays in this channel. Here we investigate the consequences of exotic invisible Higgs decays in di-Higgs production. We outline a search sensitive to such invisible decays in the b b ¯+ ET channel. We demonstrate that probing invisible branching ratios of order 10% during the LHC's high-luminosity run will be challenging, but in resonance enhanced di-Higgs production, this final state can become crucial to establish the existence of physics beyond the Standard Model at collider energies. We also briefly discuss the outlook for other exotic Higgs decay modes and the potential to observe such exotic decays in the di-Higgs channel.
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.
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.)
Fermion masses and Higgs physics in grand unified theories
Energy Technology Data Exchange (ETDEWEB)
Bhatti, Abdul Aziz
2010-03-12
The Standard model of particle physics is a very successful theory of strong weak and electromagnetic interactions. This theory is perturbative at sufficiently high energies and renormalizable thus it describes these interactions at quantum level. However it has a number of limitations, one being the fact that it has 28 free parameters assuming massive neutrinos. Within the Standard model these parameters can not be explained, however they can be accommodated in the standard theory. Particularly the masses of the fermions are not predicted by the theory. The existence of the neutrino masses can be regarded as the first glimpse of the physics beyond the standard model. In this thesis we have described the quark and lepton masses and mixings in context of non-SUSY SO(10) and four zero texture (FZT). In the four zero texture case the fermion masses and mixing can be related. We have made some predictions using tribimaximal mixing, the near tribimaximal (TBM) mixing and the triminimal parameterization. Our results show that under the TBM the neutrinos have normal, but weak hierarchy. Under near tribimaximal mixing and the triminimal parameterization we find that the neutrino masses in general increase, if the value of solar angle increases from its TBM value and vice versa. It appears that the neutrinos become more and more degenerate for solar angle values higher than TBM value and hierarchical for lower values of solar angle. We also briefly discuss neutrino parameters in the SUSY SO(10) theories. An overview of SUSY SO(10) theories and proton decay is also presented. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Bardeen, William A.; /Fermilab
2008-05-01
I discuss the Standard Model of Elementary Particle Physics and potential for discoveries of the physics responsible for electroweak symmetry breaking. I review the ideas leading to development of the Brout-Englert-Higgs mechanism that now forms the basis for the conventional Standard Model. I discuss various issues that challenge application of the Standard Model to the known physics of elementary particles. I examine alternatives to the Standard Model that address these issues and may lead to new discoveries at the LHC that go Beyond Higgs.
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.
Composite Taus and Higgs Decays
Carmona, Adrian
2013-01-01
In this talk, we describe the effects of extended fermion sectors, respecting custodial symmetry, on Higgs production and decay. The resulting protection for the Z->b_L b_L and Z->\\tau_R \\tau_R decays allows for potentially interesting signals in Higgs physics, while maintaining the good agreement of the Standard Model with precision tests. The setups can be motivated as the low energy effective theories of the composite Higgs models MCHM_5 and MCHM_10, where the spectra can be identified with the light custodians present in these theories. We will show that these describe the relevant physics in the fermion sectors in a simplified and transparent way. In contrast to previous studies of composite models, the impact of a realistic lepton sector on the Higgs decays is taken into account.
Study of Higgs boson properties in H->ZZ(*)->4l decay channel with ATLAS
Prokofiev, Kirill; The ATLAS collaboration
2017-01-01
After the discovery of the Higgs boson, the precision measurements of its properties and comparison of results to those predicted by the Standard Model (SM) became the crucial part of the LHC physics programme. Potential observation of deviations may lead to the discovery of a new physics beyond the Standard Model (BSM). In this contribution, the results of analyses of the Higgs boson properties in H->ZZ*->4l decay channel are presented. The measurements of Higgs SM couplings, fiducial and differential cross sections with 36.1 fb -1 of data collected by ATLAS at sqrt s = 13 TeV are shown. The observed limits on BSM tensor structure of Higgs couplings to SM bosons and fermions are also discussed.
OVERVIEW OF HIGGS BOSON STUDIES AT THE TEVATRON
Energy Technology Data Exchange (ETDEWEB)
Zivkovic, Lidija [Institute of Physics, Zemun, Serbia
2014-05-01
The CDF and D0 experiments at the Tevatron p¯p Collider collected data between 2002 and 2011, accumulating up to 10 fb-1 of data. During that time, an extensive search for the standard model Higgs boson was performed. Combined results from the searches for the standard model Higgs boson with the final dataset are presented, together with results on the Higgs boson couplings and spin and parity.
Studies of Higgs bosons decaying to fermions with CMS
Salerno, Daniel Nicholas
2016-01-01
This note reviews the latest results of searches for a Higgs boson decaying to fermions, including both Standard Model (SM) searches from Run I at $\\sqrt{s}=8$ TeV and Run II at $\\sqrt{s}=13$ TeV and di-Higgs boson production from Run II. The measurements of the Higgs boson coupling to fermions from Run I of the LHC, both in final states and initial states are also presented.
Higgs v Hawking: a battle of the heavyweights that has shaken the world of theoretical physics
Connor, S
2002-01-01
Stephen Hawking was accused yesterday of receiving instant credibility because of his celebrity status. His accuser was Professor Peter Higgs, who predicted the existence of the elementary particle, the Higgs Boson, in the 1960s (1 page).
Physical masses and the vacuum expectation value of the Higgs field
Cheng, Hung; S. P. Li
1996-01-01
By using the Ward-Takahashi identities in the Landau gauge, we derive exact relations between particle masses and the vacuum expectation value of the Higgs field in the Abelian gauge field theory with a Higgs meson.
Impact of on the CMSSM and its Implication on Higgs Physics at the LHC%Bs→μ+μ-对LHC寻找Higgs粒子的影响
Institute of Scientific and Technical Information of China (English)
田亚芳; 张海花; 李东玮; 曹俊杰
2012-01-01
研究在各种实验限制下CMSSM参数空间,尤其是以双比率R形式探讨B,→μ+μ-的限制,并讨论了该参数空间的唯象学性质.得出在30fb1积分亮度下,LHC只能发现一个与标准模型Higgs粒子性质非常相似的粒子(即通常文献所言Lone Higgs Scenario)这一重要结论.%The research investigates various experimental constraints,especially that from the decay,on the parameter space of the CMSSM. The characteristics of the surviving parameters and study their implications on Higgs physics are revealed. After considering the constraints,it is impossible to discover the Higgs bosons other than the SM-like Higgs boson at the LHC for 30 fb-1 integrated luminosity.
Pimenta, Jean Jûnio Mendes; Natti, Érica Regina Takano; Natti, Paulo Laerte
2013-01-01
The Higgs boson was predicted in 1964 by British physicist Peter Higgs. The Higgs is the key to explain the origin of the mass of other elementary particles of Nature. However, only with the coming into operation of the LHC, in 2008, there were technological conditions to search for the Higgs boson. Recently, a major international effort conducted at CERN, by means of ATLAS and CMS experiments, has enabled the observation of a new bosonic particle in the region of 125 GeVs. In this paper, by means of known mechanisms of symmetry breaking that occur in the BCS theory of superconductivity and in the theory of nuclear pairing, we discuss the Higgs mechanism in the Standard Model. Finally, we present the current state of research looking for the Higgs boson and the alternative theories and extensions of the Standard Model for the elementary particle physics. Keywords: Higgs boson, BCS theory, nuclear pairing, Higgs mechanism, Standard Model.
Enhancing the public impact of the Higgs discovery and other fundamental physics research
Lidstrom, Suzy; Read, Alex; Parke, Stephen; Allen, Roland; Goldfarb, Steven; Mehlhase, Sascha; Ekelof, Tord; Walker, Alan
2014-03-01
The recent experimental discovery of a Higgs boson by the ATLAS and CMS collaborations at the LHC, together with the awarding of the 2013 Nobel Prize for its theoretical prediction, has presented an exceptional opportunity for public outreach regarding the goals and importance of fundamental research in physics. We discuss novel avenues for further extending this outreach in all areas. These range from tutorial papers addressing students and teachers to internet resources and presentations to unconventional, but captivating, educational materials such as musical videos and LEGO models. Interaction with active scientists can be particularly stimulating. We account how this was encouraged (by means such as badges inviting questions from the public) during Nobel week and afterwards. The 2013 Nobel Prize in Physics explained Physica Scripta, Royal Swedish Academy of Sciences.
Trilogy of LHC Higgs Cross Section Working Group
Tanaka, R; The ATLAS collaboration
2013-01-01
Slide shown at Aspen 2013 - Higgs Quo Vadis, March 10-15, 2013, Aspen, CO, USA. The activity of LHC Higgs Cross Section Woking Group was reported putting emphasis on current theoretical issues in Higgs physics towards precision Higgs measurements.
Brivio, I; Gavela, M B; Gonzalez-Garcia, M C; Merlo, L; Rigolin, S
2014-01-01
We analyze the leading effective operators which induce a quartic momentum dependence in the Higgs propagator, for a linear and for a non-linear realization of electroweak symmetry breaking. Their specific study is relevant for the understanding of the ultraviolet sensitivity to new physics. Two methods of analysis are applied, trading the Lagrangian coupling by: i) a "ghost" scalar, after the Lee-Wick procedure; ii) other effective operators via the equations of motion. The two paths are shown to lead to the same effective Lagrangian at first order in the operator coefficients. It follows a modification of the Higgs potential and of the fermionic couplings in the linear realization, while in the non-linear one anomalous quartic gauge couplings, Higgs-gauge couplings and gauge-fermion interactions are induced in addition. Finally, all LHC Higgs and other data presently available are used to constrain the operator coefficients; the future impact of $pp\\rightarrow\\text{4 leptons}$ data via off-shell Higgs excha...
Approximate N^3LO Higgs-boson production cross section using physical-kernel constraints
de Florian, D; Moch, S; Vogt, A
2014-01-01
The single-logarithmic enhancement of the physical kernel for Higgs production by gluon-gluon fusion in the heavy top-quark limit is employed to derive the leading so far unknown contributions, ln^{5,4,3}(1-z), to the N^3LO coefficient function in the threshold expansion. Also using knowledge from Higgs-exchange DIS to estimate the remaining terms not vanishing for z = m_H^2/s^hat -> 1, these results are combined with the recently completed soft + virtual contributions to provide an uncertainty band for the complete N^3LO correction. For the 2008 MSTW parton distributions these N^3LO contributions increase the cross section at 14 TeV by (10 +- 2)% and (3 +- 2.5)% for the standard choices mu_R = m_H and mu_R = m_H/2 of the renormalization scale. The remaining uncertainty arising from the hard-scattering cross sections can be quantified as no more than 5%, which is smaller than that due to the strong coupling and the parton distributions.
Energy Technology Data Exchange (ETDEWEB)
Butterworth, Jon [University College, London (United Kingdom). Fachbereich Physik und Astronomie
2015-11-01
The discovery of the Higgs boson made headlines around the world. Two scientists, Peter Higgs and Francois Englert, whose theories predicted its existence, shared a Nobel Prize. The discovery was the culmination of the largest experiment ever run, the ATLAS and CMS experiments at CERN's Large Hadron Collider. But what really is a Higgs boson and what does it do? How was it found? And how has its discovery changed our understanding of the fundamental laws of nature? And what did it feel like to be part of it? Jon Butterworth is one of the leading physicists at CERN and this book is the first popular inside account of the hunt for the Higgs. It is a story of incredible scientific collaboration, inspiring technological innovation and ground-breaking science. It is also the story of what happens when the world's most expensive experiment blows up, of neutrinos that may or may not travel faster than light, and the reality of life in an underground bunker in Switzerland. This book will also leave you with a working knowledge of the new physics and what the discovery of the Higgs particle means for how we define the laws of nature. It will take you to the cutting edge of modern scientific thinking.
UV complete composite Higgs models
Agugliaro, Alessandro; Becciolini, Diego; De Curtis, Stefania; Redi, Michele
2016-01-01
We study confining gauge theories with fermions vectorial under the SM that produce a Higgs doublet as a Nambu-Goldstone boson. The vacuum misalignment required to break the electro-weak symmetry is induced by an elementary Higgs doublet with Yukawa couplings to the new fermions. The physical Higgs is a linear combination of elementary and composite Higgses while the SM fermions remain elementary. The full theory is renormalizable and the SM Yukawa couplings are generated from the ones of the elementary Higgs allowing to eliminate all flavour problems but with interesting effects for Electric Dipole Moments of SM particles. We also discuss how ideas on the relaxation of the electro-weak scale could be realised within this framework.
LHC physics of extra gauge bosons in the 4D Composite Higgs Model
Directory of Open Access Journals (Sweden)
Barducci D.
2013-11-01
Full Text Available We study the phenomenology of both the Neutral Current (NC and Charged Current (CC Drell-Yan (DY processes at the Large Hadron Collider (LHC within a 4 Dimensional realization of a Composite Higgs model with partial compositness by estimating the integrated and differential event rates and taking into account the possible impact of the extra fermions present in the spectrum. We show that, in certain regions of the parameters space, the multiple neutral resonances present in the model can be distinguishable and experimentally accessible in the invariant or transverse mass distributions.
Photon collider Higgs factories
Telnov, V I
2014-01-01
The discovery of the Higgs boson (and still nothing else) have triggered appearance of many proposals of Higgs factories for precision measurement of the Higgs properties. Among them there are several projects of photon colliders (PC) without e+e- in addition to PLC based on e+e- linear colliders ILC and CLIC. In this paper, following a brief discussion of Higgs factories physics program I give an overview of photon colliders based on linear colliders ILC and CLIC, and of the recently proposed photon-collider Higgs factories with no e+e- collision option based on recirculation linacs in ring tunnels.
Directory of Open Access Journals (Sweden)
FENG Chaojun
2014-08-01
Full Text Available Higgs is the only scalar particle that already observed up to now.In the standard model of particle physics,Higgs plays a very important role.On the other hand,inflation is also driven by scalar field called inflaton.Higgs boson can not be the inflaton since the large hierarchy energy scale of the mass between inflaton and itself.However,by using some indirectly method,inflaton could be another aspect of the Higgs boson.In this paper,the authors review some Higgs inflation models and discuss the role of the cosmological constant during inflation.
The FP420 R&D Project: Higgs and New Physics with forward protons at the LHC
Albrow, M.G.; Arneodo, Michele; Atoian, G.; Barlow, R.; Beaumont, W.; Bonnet, L.; Brandt, A.; Bussey, P.; Buttar, C.; Butterworth, J.M.; Carter, M.; Cox, B.E.; Dattola, D.; Da Via, C.; de Favereau, J.; D'Enterria, David; De Remigis, P.; De Roeck, Albert; De Wolf, Eddi A.; Duarte, P.; Ellis, John R.; Florins, B.; Forshaw, J.R.; Freestone, J.; Goulianos, Konstantin A.; Gronberg, J.; Grothe, M.; Gunion, J.F.; Hasi, J.; Heinemeyer, S.; Hollar, Jonathan J.; Houston, S.; Issakov, V.; Jones, Roger M.; Kelly, M.; Kenney, C.; Khoze, V.A.; Kolya, S.; Konstantinidis, N.; Kowalski, H.; Lanni, F.; Larsen, H.E.; Liu, S.L.; Lyapine, A.; Loebinger, Frederick K.; Marshall, R.; Martin, A.D.; Monk, James William; Nasteva, Irina; Nemegeer, P.; Obertino, M.M.; Orava, R.; O'Shea, V.; Pal, A.; Parker, S.; Pater, J.; Perrot, A.L.; Pierzchala, T.; Pilkington, A.D.; Pinfold, James L.; Piotrzkowski, Krzysztof; Plano, W.; Poblaguev, A.; Popov, V.; Potter, K.M.; Radeka, V.; Rescia, S.; Roncarolo, F.; Rostovtsev, A.; Rouby, X.; Ruspa, M.; Ryskin, M.G.; Santoro, A.; Schul, N.; Sellers, G.; Solano, A.; Spivey, S.; Stirling, W.J.; Swoboda, D.; Tasevsky, M.; Thompson, R.; Tsang, T.; Van Mechelen, P.; Vilela Pereira, A.; Watts, S.J.; Warren, M.R.M.; Weiglein, G.; Wengler, T.; White, Sebastian N.; Winter, B.; Yao, Y.; Zaborov, D.; Zampieri, A.; Zeller, M.; Zhokin, A.
2009-01-01
We present the FP420 R&D project, which has been studying the key aspects of the development and installation of a silicon tracker and fast-timing detectors in the LHC tunnel at 420 m from the interaction points of the ATLAS and CMS experiments. These detectors would measure precisely very forward protons in conjunction with the corresponding central detectors as a means to study Standard Model (SM) physics, and to search for and characterise New Physics signals. This report includes a detailed description of the physics case for the detector and, in particular, for the measurement of Central Exclusive Production, pp --> p + phi + p, in which the outgoing protons remain intact and the central system phi may be a single particle such as a SM or MSSM Higgs boson. Other physics topics discussed are gamma-gamma and gamma-p interactions, and diffractive processes. The report includes a detailed study of the trigger strategy, acceptance, reconstruction efficiencies, and expected yields for a particular p p --> ...
The FP420 R&D Project: Higgs and New Physics with forward protons at the LHC
Albrow, M G; Arneodo, Michele; Atoian, G; Barlow, R; Beaumont, W; Bonnet, L; Brandt, A; Bussey, P; Buttar, C; Butterworth, J M; Carter, M; Cox, B E; Dattola, D; Da Via, C; de Favereau, J; D'Enterria, David; De Remigis, P; De Roeck, Albert; De Wolf, Eddi A; Duarte, P; Ellis, John R.; Florins, B; Forshaw, J R; Freestone, J; Goulianos, Konstantin A; Gronberg, J; Grothe, M; Gunion, J F; Hasi, J; Heinemeyer, S; Hollar, Jonathan J; Houston, S; Issakov, V; Jones, Roger M; Kelly, M; Kenney, C; Khoze, V A; Kolya, S; Konstantinidis, N; Kowalski, H; Lanni, F; Larsen, H E; Liu, S L; Lyapine, A; Loebinger, Frederick K; Marshall, R; Martin, A D; Monk, James William; Nasteva, Irina; Nemegeer, P; Obertino, M M; Orava, R; O'Shea, V; Pal, A; Parker, S; Pater, J; Perrot, A L; Pierzchala, T; Pilkington, A D; Pinfold, James L; Piotrzkowski, Krzysztof; Plano, W; Poblaguev, A; Popov, V; Potter, K M; Radeka, V; Rescia, S; Roncarolo, F; Rostovtsev, A; Rouby, X; Ruspa, M; Ryskin, M G; Santoro, A; Schul, N; Sellers, G; Solano, A; Spivey, S; Stirling, W J; Swoboda, D; Tasevsky, M; Thompson, R; Tsang, T; Van Mechelen, P; Vilela Pereira, A; Watts, S J; Warren, M R M; Weiglein, G; Wengler, T; White, Sebastian N; Winter, B; Yao, Y; Zaborov, D; Zampieri, A; Zeller, M; Zhokin, A
2009-01-01
We present the FP420 R&D project, which has been studying the key aspects of the development and installation of a silicon tracker and fast-timing detectors in the LHC tunnel at 420 m from the interaction points of the ATLAS and CMS experiments. These detectors would measure precisely very forward protons in conjunction with the corresponding central detectors as a means to study Standard Model (SM) physics, and to search for and characterise New Physics signals. This report includes a detailed description of the physics case for the detector and, in particular, for the measurement of Central Exclusive Production, pp --> p + phi + p, in which the outgoing protons remain intact and the central system phi may be a single particle such as a SM or MSSM Higgs boson. Other physics topics discussed are gamma-gamma and gamma-p interactions, and diffractive processes. The report includes a detailed study of the trigger strategy, acceptance, reconstruction efficiencies, and expected yields for a particular p p --> ...
Probing Charged Higgs Boson Couplings at the FCC-hh Collider
Cakir, I T; Saygin, H; Senol, A; Cakir, O
2015-01-01
Many of the new physics models predicts a light Higgs boson similar to the Higgs boson of the Standard Model (SM) and also extra scalar bosons. Beyond the search channels for a SM Higgs boson, the future collider experiments will explore additional channels that are specific to extended Higgs sectors. We study the charged Higgs boson production within the framework of two Higgs doublet models (THDM) in the proton-proton collisions at the FCC-hh collider. With an integrated luminosity of 500 fb$^{-1}$ at very high energy frontier, we obtain a significant coverage of the parameter space and distinguish the charged Higgs-top-bottom interaction within the THDM or other new physics models with charged Higgs boson mass up to 1 TeV.
Beyond the discovery Higgs results from CMS
AUTHOR|(CDS)2051212
2015-01-01
The observation of a Higgs boson at a mass near 125 GeV in the year 2012 has been a milestone for elementary particle physics. Since this fundamental discovery, the CMS collaboration has scrutinized the complete Run I dataset in depth, and studied the properties of the observed state in full detail. This includes investigations of more elusive production and decay modes, as well as searches for first indications of an extended Higgs sector, which would represent very likely a promising gateway to new physics. This presentation summarizes recent Higgs results from the CMS experiment.
Study Of Boosted W-Jets And Higgs-Jets With the SiFCC Detector
Energy Technology Data Exchange (ETDEWEB)
Yu, Shin-Shan [Taiwan, Natl. Central U.; Chekanov, Sergei [Argonne; Gray, Lindsey [Fermilab; Kotwal, Ashutosh [Duke U.; Sen, Sourav [Duke U.; Tran, Nhan Viet [Fermilab
2016-11-04
We study the detector performance in the reconstruction of hadronically-decaying W bosons and Higgs bosons at very high energy proton colliders using a full GEANT4 simulation of the SiFCC detector. The W and Higgs bosons carry transverse momentum in the multi-TeV range, which results in collimated decay products that are reconstructed as a single jet. We present a measurement of the energy response and resolution of boosted W-jets and Higgs-jets and show the separation of two sub-jets within the boosted boson jet.
Beyond-the-Standard Model Higgs Physics using the ATLAS Experiment
Truong, Loan
2016-11-01
Recent searches for the Higgs boson in the context of beyond the Standard Model performed by the ATLAS experiment are presented: high mass Higgs boson searches, lepton flavour violating Higgs decay, NMSSM, constraint from the search for three photons. The interpretation based on the measurements of Higgs couplings is shown, along with the constraint on the Higgs boson invisible decays. The search for invisible decays of a Higgs boson produced in association with a Z boson was performed with both √s = 7 and 8 TeV while the rest were performed using the √s = 8 TeV data of proton-proton collisions collected by the ATLAS experiment. No significant excess of data over the predicted background is observed and limits are placed in certain quantities depending on the searches.
Beyond-the-Standard Model Higgs Physics using the ATLAS Experiment
Directory of Open Access Journals (Sweden)
Truong Loan
2016-01-01
Full Text Available Recent searches for the Higgs boson in the context of beyond the Standard Model performed by the ATLAS experiment are presented: high mass Higgs boson searches, lepton flavour violating Higgs decay, NMSSM, constraint from the search for three photons. The interpretation based on the measurements of Higgs couplings is shown, along with the constraint on the Higgs boson invisible decays. The search for invisible decays of a Higgs boson produced in association with a Z boson was performed with both √s = 7 and 8 TeV while the rest were performed using the √s = 8 TeV data of proton-proton collisions collected by the ATLAS experiment. No significant excess of data over the predicted background is observed and limits are placed in certain quantities depending on the searches.
New physics effects in the Higgs trilinear self-coupling through one-loop radiative corrections
Moyotl, A; Castilla-Valdez, H; Pérez, M A
2016-01-01
We compute the one-loop corrections to the triple Higgs self-interaction $hhh$ in the framework of the Standard Model (SM), the Two Higgs Doublet Model type III (THDM-III) and the Littlest Higgs Model with T parity (LHBM+T). Our results are compared with previous results for the SM. In particular, we find that an imaginary part for the $\\lambda_{hhh}$ form factor is induced when one of the Higgs boson legs is off-mass shell with 4-momentum magnitude higher than the Higgs boson mass. This contribution is sensitive to virtual effects of the Higgs self-interaction, that induces a radiative correction to the $hhh$ coupling of order 11%. However, the radiative corrections associated to the new degrees of freedom of the THDM-III and the LHBM+T are rather smaller and comparable to the $W^\\pm$ and $Z^0$ gauge bosons one-loop corrections.
Ferri, F.; CMS Collaboration
2016-04-01
The precise determination of the mass, the width and the couplings of the particle discovered in 2012 with a mass around 125 GeV is of capital importance to clarify the nature of such a particle, in particular to establish precisely if it is a Standard Model Higgs boson. In several new physics scenarios, in fact, the Higgs boson may behave differently with respect to the Standard Model one, or may not be unique, i.e. there can be more than one Higgs boson. In order to achieve the precision needed to discriminate between different models, the energy resolution, the scale uncertainty and the position resolution for electrons and photons are required to be as good as possible. The CMS scintillating lead-tungstate electromagnetic calorimeter (ECAL) was built as a precise tool with an exceptional energy resolution and a very good position resolution that improved over the years with the knowledge of the detector. Moreover, thanks to the fact that most of the lead-tungstate scintillation light is emitted in about 25 ns, the ECAL can be used to accurately determine the time of flight of photons. We present the current performance of the CMS ECAL, with a special emphasis on the impact on the measurement of the properties of the Higgs boson and on searches for new physics.
Little Higgs and Custodial SU(2)
Chang, S; Chang, Spencer; Wacker, Jay G.
2004-01-01
In this note we present a little Higgs model that has custodial SU(2) as an approximate symmetry. This theory is a simple modification of the ``Minimal Moose'' with SO(5) global symmetries protecting the Higgs mass. This allows for a simple limit where TeV physics makes small contributions to precision electroweak observables. The spectrum of particles and their couplings to Standard Model fields are studied in detail. At low energies this model has two Higgs doublets and it favours a light Higgs from precision electroweak bounds, though for different reasons than in the Standard Model. The limit on the breaking scale, f, is roughly 700 GeV, with a top partner of 2 TeV, W' and $B'$ of 2.5 TeV, and heavy Higgs partners of 2 TeV. These particles are easily accessible at hadron colliders.
Resonant mono Higgs at the LHC
Basso, Lorenzo
2015-01-01
In recent years, the production of a SM particle with large missing transverse momentum, dubbed mono-X searches, have gained increasing attention. After the discovery of the Higgs boson in 2012, the run-II of the LHC will now scrutinise its properties, looking for BSM physics. In particular, one could search for mono-Higgs signals, that are typically studied in models addressing dark matter. However, this signal can appear also in models addressing the neutrino masses, if additional heavier neutrinos with masses at the electroweak scale are present. The latter will couple to the SM neutrinos and the Higgs boson, yielding a type of mono-Higgs signal not considered for dark matter: the resonant production of a Higgs boson and missing energy. In this paper, we address the LHC exclusion power of the latter with dedicated detector simulations, and reinterpret it in a benchmark model for neutrino mass generation.
Lafaye, R
2002-01-01
This proceeding is an overview of ATLAS capabilities on Higgs studies. After a short introduction on LEP and Tevatron searches on this subject, the ATLAS potential on a standard model and a supersymmetric Higgs discovery are summarized. Last, a section presents the Higgs parameters measurement that will be possible at LHC. (6 refs).
Searching heavier Higgs boson via di-Higgs production at LHC Run-2
Directory of Open Access Journals (Sweden)
Lan-Chun Lü
2016-04-01
Full Text Available The discovery of a light Higgs particle h0(125 GeV opens up new prospect for searching heavier Higgs boson(s at the LHC Run-2, which will unambiguously point to new physics beyond the standard model (SM. We study the detection of a heavier neutral Higgs boson H0 via di-Higgs production channel at the LHC (14 TeV, H0→h0h0→WW⁎γγ. This directly probes the Hhh cubic Higgs interaction, which exists in most extensions of the SM Higgs sector. For the decay products of final states WW⁎, we include both pure leptonic mode WW⁎→ℓν¯ℓ¯ν and semi-leptonic mode WW⁎→qq¯′ℓν. We analyze signals and backgrounds by performing fast detector simulation for the full process pp→H→hh→WW⁎γγ→ℓν¯ℓ¯νγγ and pp→H→hh→WW⁎γγ→ℓνqq¯′γγ, over the mass range MH=250–600 GeV. For generic two-Higgs-doublet models (2HDM, we present the discovery reach of the heavier Higgs boson at the LHC Run-2, and compare it with the current Higgs global fit of the 2HDM parameter space.
Searching heavier Higgs boson via di-Higgs production at LHC Run-2
Lü, Lan-Chun; Du, Chun; Fang, Yaquan; He, Hong-Jian; Zhang, Huijun
2016-04-01
The discovery of a light Higgs particle h0 (125 GeV) opens up new prospect for searching heavier Higgs boson(s) at the LHC Run-2, which will unambiguously point to new physics beyond the standard model (SM). We study the detection of a heavier neutral Higgs boson H0 via di-Higgs production channel at the LHC (14 TeV), H0 →h0h0 → WW* γγ. This directly probes the Hhh cubic Higgs interaction, which exists in most extensions of the SM Higgs sector. For the decay products of final states WW*, we include both pure leptonic mode WW* → ℓ ν bar ℓ bar ν and semi-leptonic mode WW* → qqbar‧ ℓν. We analyze signals and backgrounds by performing fast detector simulation for the full process pp → H → hh → WW* γγ → ℓ ν bar ℓ bar νγγ and pp → H → hh → WW* γγ → ℓνqqbar‧ γγ, over the mass range MH = 250- 600 GeV. For generic two-Higgs-doublet models (2HDM), we present the discovery reach of the heavier Higgs boson at the LHC Run-2, and compare it with the current Higgs global fit of the 2HDM parameter space.
The theoretical physics ecosystem behind the discovery of the Higgs boson
Wells, James D
2016-01-01
The discovery of the Higgs boson in 2012 was one of the most significant developments of science in the last half century. A simplified history has Peter Higgs positing it in the mid-1960s followed by a long wait while experimentalists progressively turned up collider energies until it appeared several decades later. However, in order for both the hypothesis and the experimental discovery to occur, a vast and complex theory ecosystem had to thrive in the years before Higgs's hypothesis and in the years that followed, building up to its discovery. It is further claimed that the Higgs boson hypothesis was an immoderate speculation, and therefore faith in theory argumentation and speculation was mandatory for the discovery program to proceed and reach its fulfillment. The Higgs boson could not have been discovered experimentally by accident.
Beyond-the-Standard Model Higgs Physics using the ATLAS Experiment
AUTHOR|(INSPIRE)INSPIRE-00444174; The ATLAS collaboration
2015-01-01
Some recent searches for the Higgs boson in the context of beyond the Standard Model, performed by the ATLAS experiment are presented: high mass Higgs boson searches, lepton flavour violating Higgs decay, NMSSM, con- straint from the search for three photons. The interpretation based on the measurements of Higgs couplings are shown, along with the constraint on the Higgs boson invisible decays. Except the latter has some part using both full √s = 7 TeV and √s = 8 TeV data, the rest are performed with the √s = 8 TeV data of proton-proton collisions collected by the ATLAS experiment. No sig- nificant excess of data over the predicted background is observed in all those searches. Limits are placed in certain quantities depending on the searches.
Annual Workshop: Higgs Couplings 2016
2016-01-01
Higgs Couplings 2016 is this year's installment of an annual workshop devoted to new experimental and theoretical results on the Higgs boson. The 2016 workshop will present the latest results from the LHC run 2 on the Higgs boson mass, spin/parity, and couplings and will present new theoretical work devoted to the measurement of Higgs parameters and possibilities for exotic Higgs decays. The workshop will provide an opportunity for critical discussion of the current strategies for studying the Higgs boson at the LHC and the next steps in the LHC program. The workshop will also include discussion of the longer-term Higgs boson program at future facilities.
Comparing Constraints from Dark Matter Studies to Invisible Higgs Searches at CMS
Mccusker, Daniel
2016-01-01
Evidence for dark matter constitutes a strong motivation for searches for physics beyond the Standard Model (BSM). Current dark matter experiments strongly constrain the regions of parameter space in which dark matter particles might reside. These constraints guide searches for dark matter through production channels at collider experiments, e.g. at the Large Hadron Collider (LHC). Using MadDM and MadGraph software, we conduct computational analyses on a simple Higgs portal model, in which a Standard Model (SM) Higgs boson decays to two scalar dark matter particles. We synthesize existing experimental constraints, from relic density and direct detection data, with estimates of the Higgs to invisible decay branching ratios at the LHC. We find a region of dark matter particle mass and Yukawa coupling values which may fall within the future plans for the detection capability of the HL-LHC.
Post-ACME2013 CP-violation in Higgs Physics and Electroweak Baryogenesis
Bian, Ligong; Shu, Jing
2014-01-01
We present a class of cancellation mechanisms to suppress the total contributions of Barr-Zee diagrams to the electron electric dipole moment (eEDM). This class of mechanisms are of particular significance after the new eEDM upper limit, which strongly constrains the allowed magnitude of CP-violation in Higgs couplings and hence the feasibility of electroweak baryogenesis (EWBG), were released by the ACME collaboration in 2013. We point out: if both the CP-odd Higgs-photon-photon ($Z$ boson) and the CP-odd Higgs-electron-positron couplings are turned on, a cancellation may occur either between the contributions of a CP-mixing Higgs boson, with the other Higgs bosons being decoupled, or between the contributions of a CP-even and a CP-odd Higgs bosons. With the assistance of the cancellation mechanisms, a large CP-phase in Higgs couplings with viable electroweak baryogenesis (EWBG) is still allowed. The reopened parameter regions would be probed by the future neutron, mercury EDM measurements, and direct measur...
Tests of Higgs and Top Effective Interactions
Díaz-Cruz, J L; Toscano, J J
1997-01-01
We study the possibility to detect heavy physics effects in the interactions of Higgs bosons and the top quark at future colliders using the effective Lagrangian approach. The modification of the interactions may enhance the production of Higgs bosons at hadron colliders through the mechanisms of gluon fusion and associated production with a W boson or $t\\bar{t}$ pairs. The most promising signature is through the decay of the Higgs boson into two photons, whose branching ratio is also enhanced in this approach. As a consequence of our analysis we get a bound on the chromomagnetic dipole moment of the top quark.
Three-Higgs-doublet models: symmetries, potentials and Higgs boson masses
Energy Technology Data Exchange (ETDEWEB)
Keus, Venus [School of Physics and Astronomy, University of Southampton,Southampton, SO17 1BJ (United Kingdom); Department of Physics, Royal Holloway, University of London,Egham Hill, Egham TW20 0EX (United Kingdom); Particle Physics Department, Rutherford Appleton Laboratory,Chilton, Didcot, Oxon OX11 0QX (United Kingdom); King, Stephen F. [School of Physics and Astronomy, University of Southampton,Southampton, SO17 1BJ (United Kingdom); Moretti, Stefano [School of Physics and Astronomy, University of Southampton,Southampton, SO17 1BJ (United Kingdom); Particle Physics Department, Rutherford Appleton Laboratory,Chilton, Didcot, Oxon OX11 0QX (United Kingdom)
2014-01-13
We catalogue and study three-Higgs-doublet models in terms of all possible allowed symmetries (continuous and discrete, Abelian and non-Abelian), where such symmetries may be identified as flavour symmetries of quarks and leptons. We analyse the potential in each case, and derive the conditions under which the vacuum alignments (0,0,v), (0,v,v) and (v,v,v) are minima of the potential. For the alignment (0,0,v), relevant for dark matter models, we calculate the corresponding physical Higgs boson mass spectrum. Motivated by supersymmetry, we extend the analysis to the case of three up-type Higgs doublets and three down-type Higgs doublets (six doublets in total). Many of the results are also applicable to flavon models where the three Higgs doublets are replaced by three electroweak singlets.
Effects of the anomalous Higgs couplings on the Higgs boson production at the Large Hadron Collider
Kanemura, Shinya
2008-01-01
We study the impact of dimension-six operators on single- and double-Higgs production via gluon fusion at the Large Hadron Collider (LHC). If the top-Yukawa coupling is modified by some new physics whose scale is of the TeV scale, its effect changes the cross sections of single-Higgs production $gg\\to H$ and double-Higgs production $gg\\to HH$ through the top-loop diagram. In particular, double-Higgs production can receive significant enhancement from the effective top-Yukawa coupling and the new dimension-five coupling $t{\\bar t}HH$ which are induced by the dimension-six operator. Comparing these results to the forthcoming data at the LHC, one can extract information of the dimension-six operators relevant to the top quark and the Higgs boson.
Tools for charged Higgs bosons
Energy Technology Data Exchange (ETDEWEB)
Staal, Oscar
2010-12-15
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.)
The symmetry and simplicity of the laws of physics and the Higgs boson
Maldacena, Juan
2014-01-01
We describe the theoretical ideas, developed between the 1950s-1970s, which led to the prediction of the Higgs boson, the particle that was discovered in 2012. The forces of nature are based on symmetry principles. We explain the nature of these symmetries through an economic analogy. We also discuss the Higgs mechanism, which is necessary to avoid some of the naive consequences of these symmetries, and to explain various features of elementary particles.
Ballesteros, Guillermo; Ringwald, Andreas; Tamarit, Carlos
2016-01-01
We present a minimal extension of the Standard Model (SM) providing a consistent picture of particle physics from the electroweak scale to the Planck scale and of cosmology from inflation until today. Three right-handed neutrinos $N_i$, a new color triplet $Q$ and a complex SM-singlet scalar $\\sigma$, whose vacuum expectation value $v_\\sigma \\sim 10^{11}$ GeV breaks lepton number and a Peccei-Quinn symmetry simultaneously, are added to the SM. At low energies, the model reduces to the SM, augmented by seesaw generated neutrino masses and mixing, plus the axion. The latter solves the strong CP problem and accounts for the cold dark matter in the Universe. The inflaton is comprised by a mixture of $\\sigma$ and the SM Higgs and reheating of the Universe after inflation proceeds via the Higgs portal. Baryogenesis occurs via thermal leptogenesis. Thus, five fundamental problems of particle physics and cosmology are solved at one stroke in this unified Standard Model - Axion - Seesaw - Higgs portal inflation (SMASH...
Ballesteros, Guillermo; Redondo, Javier; Ringwald, Andreas; Tamarit, Carlos
2017-08-01
We present a minimal extension of the Standard Model (SM) providing a consistent picture of particle physics from the electroweak scale to the Planck scale and of cosmology from inflation until today. Three right-handed neutrinos Ni, a new color triplet Q and a complex SM-singlet scalar σ, whose vacuum expectation value vσ ~ 1011 GeV breaks lepton number and a Peccei-Quinn symmetry simultaneously, are added to the SM. At low energies, the model reduces to the SM, augmented by seesaw generated neutrino masses and mixing, plus the axion. The latter solves the strong CP problem and accounts for the cold dark matter in the Universe. The inflaton is comprised by a mixture of σ and the SM Higgs, and reheating of the Universe after inflation proceeds via the Higgs portal. Baryogenesis occurs via thermal leptogenesis. Thus, five fundamental problems of particle physics and cosmology are solved at one stroke in this unified Standard Model—axion—seesaw—Higgs portal inflation (SMASH) model. It can be probed decisively by upcoming cosmic microwave background and axion dark matter experiments.
An effective lagrangian description of charged Higgs decays H^+ -> Wg, WZ and Wh
Díaz-Cruz, J L; Toscano, J J
2001-01-01
Charged Higgs decays are discussed within an effective lagrangian extension of the two-higgs doublet model, assuming new physics appearing in the Higgs sector of this model. Low energy constrains are used to imposse bounds on certain dimension -six operators that describe the modified charged Higgs interactions. These bounds are used then to study the decays H^+ -> Wg, WZ and Wh, which can have branching ratios of order 10^-5, 10^-1 and O(1), respectively; thse modes are thus sensitive probes of the symmetries of the Higgs sector that could be tested at future colliders.
Dynamical restoration of ZN symmetry in SU(N) + Higgs theories
Biswal, Minati; Digal, Sanatan; Saumia, P. S.
2016-09-01
We study the ZN symmetry in SU (N) + Higgs theories with the Higgs field in the fundamental representation. The distributions of the Polyakov loop show that the ZN symmetry is explicitly broken in the Higgs phase. On the other hand inside the Higgs symmetric phase the Polyakov loop distributions and other physical observables exhibit the ZN symmetry. This effective realization of the ZN symmetry in the theory changes the nature of the confinement-deconfinement transition. We argue that the ZN symmetry will lead to time independent topological defect solutions in the Higgs symmetric deconfined phase which will play important role at high temperatures.
Dynamical Restoration of Z_N Symmetry in SU(N)+Higgs Theories
Biswal, Minati; Saumia, P S
2015-01-01
We study the Z_N symmetry in SU(N)+Higgs theories with the Higgs field in the fundamental representation. The distributions of the Polyakov loop show that the Z_N symmetry is explicitly broken in the Higgs phase. On the other hand, inside the Higgs symmetric phase the Polyakov loop distributions and other physical observables exhibit the Z_N symmetry. This effective restoration of the Z_N symmetry changes the nature of the confinement-deconfinenement transition. We argue that the Z_N symmetry will lead to time independent topological defect solutions in the Higgs symmetric deconfined phase which will play important role at high temperatures.
The Half-composite Two Higgs Doublet Model and the Relaxion
Antipin, Oleg
2015-01-01
We study a new confining gauge theory with fermions in a vectorial representation under the SM gauge group that allows for Yukawa interactions with the Higgs. If the fermion masses are smaller than the confinement scale this realizes a type I two Higgs doublet model where a composite Higgs mixes with the elementary Higgs. This class of models interpolates between an elementary and a composite Higgs and has interesting phenomenology with potentially observables effects in collider physics, EDMs and SM couplings but very weak bounds from indirect searches. The very same framework can be used to realize the cosmological relaxation of the electro-weak scale recently discussed in the literature.
The half-composite two Higgs doublet model and the relaxion
Antipin, Oleg; Redi, Michele
2015-12-01
We study a new confining gauge theory with fermions in a vectorial representation under the SM gauge group that allows for Yukawa interactions with the Higgs. If the fermion masses are smaller than the confinement scale this realizes a type I two Higgs doublet model where a composite Higgs mixes with the elementary Higgs. This class of models interpolates between an elementary and a composite Higgs and has interesting phenomenology with potentially observable effects in collider physics, EDMs and SM couplings but very weak bounds from indirect searches. The very same framework can be used to realize the cosmological relaxation of the electro-weak scale recently discussed in the literature.
Kawabata, S; Sumino, Y; Yokoya, H
2013-01-01
We propose a new method to measure various physical parameters, using characteristic weight functions. This method needs only lepton energy distribution and ideally does not depend on the velocity of the parent particle. We demonstrate an application of this method by simulating a reconstruction of the Higgs boson mass in the H-> WW -> lnu lnu decay mode at the LHC. We show that systematic errors are suppressed compared to statistical errors. In the vector boson fusion channel, the statistical accuracy of the mass determination is estimated to be +12% and -14% at an integrated luminosity of 100fb^{-1}, assuming the Higgs mass to be 125GeV and root{s}=14TeV.
WPHACT 1.0 - A program for $WW$, Higgs and 4 fermion physics at $e^+ e^-$ colliders
Accomando, E; Accomando, Elena; Ballestrero, Alessandro
1996-01-01
WPHACT (W W and Higgs Physics with PHACT) is a MC program and unweighted event generator which computes all Standard Model processes with four fermion in the final state at $e^+ e^-$ colliders. It is based on an helicity amplitude method which allows precise and fast evaluations of the matrix elements both for massless and massive fermions. Fermion masses for $b$ quarks are exactly taken into account. QED initial state and Coulomb corrections are evaluated, while QCD final state corrections are included in an approximate formulation. Cuts can be easily introduced and distributions for any variable at parton level can be implemented. The contributions to the processes of neutral Standard Model or Susy Higgs can be included. Anomalous couplings effects for the triple coupling can be computed. An interface to hadronization is provided and Jetset can be directly called from the program.
Light A physics in the lepton-specific two-Higgs doublet model
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
We examine various direct and indirect constraints on the lepton-specific two-Higgs doublet model and discuss its phenomenology at colliders in the allowed parameter space.The constraints we consider come from the precision electroweak data,the direct search for Higgs boson,the muon anomalous magnetic moment,as well as some theoretical consistency requirements.We find that in the allowed parameter space the CP-odd Higgs boson A is rather light (m A < 30 GeV with 95% possibility),which is composed dominantly by the leptonic Higgs and decays dominantly into τ + τ;while the SM-like Higgs boson h (responsible largely for electroweak symmetry breaking) decays dominantly in the mode h → AA → 4τ with a large decay width,which will make the Higgs discovery more difficult at the LHC.Whereas,this scenario predicts rare Z decays Z → AAA and Z →τ + τA with their branching ratios ranging from 10-8 to 10-and 10-5 to 10-4 respectively,which may be accessible at the GigaZ option of the ILC.
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...
Brod, Joachim
2016-01-01
I review new developments in Higgs physics, with a focus on Yukawa couplings in and beyond the standard model. In particular, I discuss different methods of measuring the light Yukawas, new sources of CP violation in the Higgs sector, and lepton flavor violation.
Ciuchini, Marco; Mishima, Satoshi; Pierini, Maurizio; Reina, Laura; Silvestrini, Luca
2014-01-01
We present updated global fits of the Standard Model and beyond to electroweak precision data, taking into account recent progress in theoretical calculations and experimental measurements. From the fits, we derive model-independent constraints on new physics by introducing oblique and epsilon parameters, and modified $Zb\\bar{b}$ and $HVV$ couplings. Furthermore, we also perform fits of the scale factors of the Higgs-boson couplings to observed signal strengths of the Higgs boson.
The Nobel Prize winner in physics 2013--Peter Higgs%2013年诺贝尔物理学奖获得者--彼得·希格斯
Institute of Scientific and Technical Information of China (English)
刘金岩
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 discov-ery of Higgs particle is also given here.%彼得·希格斯(Peter Higgs)是英国著名的理论物理学家，因是希格斯机制的主要贡献人之一及以其名字命名的希格斯粒子而闻名于世。彼得·希格斯与弗朗索瓦·恩格勒(Francois Englert)共同获得了2013年诺贝尔物理学奖。文章简要介绍了彼得·希格斯的生平，希格斯机制的提出以及希格斯粒子命名的由来。此外，文章还简要回顾了希格斯粒子的发现过程。
Detector optimization studies and light Higgs decay into muons at CLIC
Energy Technology Data Exchange (ETDEWEB)
Grefe, Christian
2013-09-15
The Compact Linear Collider (CLIC) is a concept for a future e{sup +}e{sup -} linear collider with a center-of-mass energy of up to 3 TeV. The design of a CLIC experiment is driven by the requirements related to the physics goals, as well as by the experimental conditions. For example, the short time between two bunch crossings of 0.5 ns and the backgrounds due to beamstrahlung have direct impact on the design of a CLIC experiment. The Silicon Detector (SiD) is one of the concepts currently being discussed as a possible detector for the International Linear Collider (ILC). In this thesis we develop a modified version of the SiD simulation model for CLIC, taking into account the specific experimental conditions. In addition, we developed a software tool to investigate the impact of beam-related backgrounds on the detector by overlaying events from different simulated event samples. Moreover, we present full simulation studies, determining the performance of the calorimeter and tracking systems. We show that the track reconstruction in the all-silicon tracker of SiD is robust in the presence of the backgrounds at CLIC. Furthermore, we investigate tungsten as a dense absorber material for the hadronic calorimeter, which allows for the construction of a compact hadronic calorimeter that fulfills the requirements on the energy resolution and shower containment without a significant increase of the coil radius. Finally, the measurement of the decays of light Higgs bosons into two muons is studied in full simulation. We find that with an integrated luminosity of 2 ab{sup -1}, corresponding to 4 years of data taking at CLIC, the respective Higgs branching ratio can be determined with a statistical uncertainty of approximately 15%.
Energy Technology Data Exchange (ETDEWEB)
Knochel, Alexander
2016-07-01
The following topics are dealt with: The development of the Standard Model on the base of relativity theory, quantum theory, and the detection of new particles, the physics of the Standard Model, the production of new particles with the LHC, the importance of the discovery of a Higgs boson for our picture of the world. (HSI)
Ferri, Federico
2014-01-01
The precise determination of the mass, the width and the couplings of the particle discovered in 2012 around 125 GeV is of capital importance to clarify the nature of such a particle, in particular to establish precisely if it is a Standard Higgs boson. In several new physics scenarios, in fact, a Higgs boson may behave differently with respect to the Standard one, or may not be unique, i.e. there can be more than one Higgs boson. In order to achieve the precision needed to discriminate between different models, the energy resolution, the scale uncertainty and the position resolution for electrons and photons are required to be as good as possible. The CMS scintillating lead-tungstate electromagnetic calorimeter (ECAL) was built as a precise tool with an exceptional energy resolution and a very good position resolution that improved over the years with the knowledge of the detector. Moreover, thanks to the fact that most of the lead-tungstate scintillation light is emitted in about 25 ns, ECAL can be used to ...
Multi-Higgs Mass Spectrum in Gauge-Higgs Unification
Kojima, Kentaro; Yamashita, Toshifumi
2008-01-01
We study an SU(2) supersymmetric gauge model in a framework of gauge-Higgs unification. Multi-Higgs spectrum appears in the model at low energy. We develop a useful perturbative approximation scheme for evaluating effective potential to study the multi-Higgs mass spectrum. We find that both tree-massless and massive Higgs scalars obtain mass corrections of similar size from finite parts of the loop effects. The corrections modify multi-Higgs mass spectrum, and hence, the loop effects are significant in view of future verifications of the gauge-Higgs unification scenario in high-energy experiments.
Schlaffer, Matthias; Takeuchi, Michihisa; Weiler, Andreas; Wymant, Chris
2014-01-01
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 $H\\to 2\\ell+\\mathbf{p}\\!\\!/_T$ via $H\\to \\tau\\tau$ and $H\\to WW^*$ could be performed and demonstrate that it offers a compelling alternative to the $t\\bar t H$ channel. We discuss the sensitivity to new physics in the most challenging scenario of an exactly SM-like inclusive Higgs cross-section.
Energy Technology Data Exchange (ETDEWEB)
Schlaffer, Matthias [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Spannowsky, Michael [Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenology; Takeuchi, Michihisa [King' s College London (United Kingdom). Theoretical Physics and Cosmology Group; Weiler, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); European Organization for Nuclear Research (CERN), Geneva (Switzerland); Wymant, Chris [Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenology; Laboratoire d' Annecy-le-Vieux de Physique Theorique, Annecy-le-Vieux (France)
2014-05-15
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{sub T} via H→ττ and H→WW{sup *} 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.
Standard Model and Higgs Physics at the HL-LHC with ATLAS and CMS
AUTHOR|(INSPIRE)INSPIRE-00195228; The ATLAS collaboration
2016-01-01
The current LHC experimental program is scheduled to last until the end of 2023 and to result in a total data sample of about 300~fb$^{-1}$ at a $pp$ centre-of-mass energy close to the design value of 14~TeV. This will be followed by a high-luminosity phase in which the LHC instantaneous luminosity will be increased by a factor of up to 7.5 times the design value of $1\\times 10^{34}{\\rm cm}^{-2}{\\rm s}^{-1}$, with the goal of accumulating a total dataset of about 3000~fb$^{-1}$ over about a ten-year run period. This will require significant upgrades to both the accelerator infrastructure, and the detectors, which were not designed to operate under these conditions. The large anticipated data sample will allow for more precise investigations of topics already studied with the 300~fb$^{-1}$ data sample, as well as for studies of processes that are accessible only with the much larger statistics. There will be a particular focus on investigations of the properties of the Higgs boson, which was discovered in 2012...
Lattice study of the Higgs-Yukawa model in and beyond the standard model
Energy Technology Data Exchange (ETDEWEB)
Chu, David Y.J.; Lin, C.J. David [National Chiao-Tung Univ., Hsinchu (China); Jansen, Karl [DESY Zeuthen (Germany). NIC; Knippschild, Bastian [HISKP, Bonn (Germany); Nagai, Kei-Ichi [Nagoya Univ. (Japan). Kobayashi-Maskawa Inst.; Nagy, Attila [Humboldt Univ. Berlin (Germany); DESY Zeuthen (Germany). NIC
2015-11-15
We derive finite-size scaling formulae for four-dimensional Higgs-Yukawa models near the Gaussian fixed point. These formulae will play an essential role in future, detailed investigation of such models. In particular, they can be used to determine the nature of the observed phase transitions, and confirm or rule out the possibility of having non-trivial fixed points in the Higgs-Yukawa models. Our scaling formula for Binder's cumulant is tested against lattice simulations carried out at weak couplings, and good agreement is found. As a separate project, we also present preliminary results from our study of a chirally-invariant Higgs-Yukawa model including a dimension-six operator at finite temperature. Our work provides first indications of first-order temperature-induced phase transitions near the infinite cutoff limit in this model.
Higgs production and decay in the little Higgs model
Dib, C; Rosenfeld, R.; Zerwekh, A.
2003-01-01
We analyse the consequences of the little Higgs model for double Higgs boson production at the LHC and for the partial decay width of the Higgs into two photons. In particular, we study the sensitivity of these processes in terms of the parameters of the model. We find that the little Higgs model contributions are proportional to (v/f)^4 and hence do not change significantly either single or double Higgs production at hadron colliders or the partial decay width of the Higgs into two photons a...
Particle Physics after the Higgs-Boson Discovery: Opportunities for the Large Hadron Collider
Quigg, Chris
2015-01-01
The first run of the Large Hadron Collider at CERN brought the discovery of the Higgs boson, an apparently elementary scalar particle with a mass of 125 GeV, the avatar of the mechanism that hides the electroweak symmetry. A new round of experimentation is beginning, with the energy of the proton--proton colliding beams raised to 6.5 TeV per beam, from 4 TeV at the end of the first run. This article summarizes what we have learned about the Higgs boson, and calls attention to some issues that will be among our central concerns in the near future.
Higgs production at hadron colliders as a probe of new physics
Díaz-Cruz, J L
2000-01-01
The coupling of Higgs with gauge bosons can receive non-decoupling corrections due to heavy quanta. Deviation from the SM predictions are described by a set of parameters e_V, which can be related to the parameters S,T. The Higgs production by gluon fusion can be used to probe e_g, whereas its decays into WW can probe e_W. The resulting bounds may imply the exclusion of heavy particles, such as additional standard or mirror families, chiral colored sextets and octet quarks. Within the MSSM, we also find that gluon fusion is a sensitive probe for the spectrum of squark masses.
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...
Planck Scale Physics, Gravi-Weak Unification and the Higgs Inflation
Laperashvili, L V; Sidharth, B G
2015-01-01
Starting with a theory of the discrete space-time at the Planck scale, we developed a Gravi-Weak Unification (GWU) - a $Spin(4,4)$-invariant model unified gravity with weak $SU(2)$ gauge and Higgs fields in the visible and invisible sectors of the Universe. Considering the Gravi-Weak symmetry breaking, we showed that the obtained sub-algebras contain the self-dual left-handed gravity in the OW, and the anti-self-dual right-handed gravity in the MW. Finally, at the low energy limit, we have only the Standard Model (SM) and the Einstein-Hilbert's gravity. The Froggatt-Nielsen's prediction of the top-quark and Higgs masses was given in the assumption that there exist two degenerate vacua in the SM. This prediction was improved by the next order calculations. We have developed a model of the Higgs Inflation using the GWU action. According to this inflationary model, a scalar field (inflaton) starts trapped from the "false vacuum" of the Universe at the Higgs field's VEV $v_2 \\sim 10^{18}$ GeV. The interaction bet...
$\\tau$- and $\\mu$-physics in a general two Higgs doublet model with $\\mu-\\tau$ flavor violation
Omura, Yuji; Tobe, Kazuhiro
2015-01-01
Motivated by the recent CMS excess in a flavor violating Higgs decay $h \\rightarrow \\mu \\tau$ as well as the anomaly of muon anomalous magnetic moment (muon g-2), we consider a scenario where both the excess in $h \\rightarrow \\mu \\tau$ and the anomaly of muon g-2 are explained by the $\\mu-\\tau$ flavor violation in a general two Higgs doublet model. We study various processes involving $\\mu$ and $\\tau$, and then discuss the typical predictions and constraints in this scenario. Especially, we find that the prediction of $\\tau \\rightarrow \\mu \\gamma$ can be within the reach of the Belle II experiment. We also show that the lepton non-universality between $\\tau \\rightarrow \\mu \
Schmaltz, M; Schmaltz, Martin; Tucker-Smith, David
2005-01-01
Recently there has been renewed interest in the possibility that the Higgs particle of the Standard Model is a pseudo-Nambu-Goldstone boson. This development was spurred by the observation that if certain global symmetries are broken only by the interplay between two or more coupling constants, then the Higgs mass-squared is free from quadratic divergences at one loop. This "collective symmetry" breaking is the essential ingredient in little Higgs theories, which are weakly coupled extensions of the Standard Model with little or no fine tuning, describing physics up to an energy scale ~10 TeV. Here we give a pedagogical introduction to little Higgs theories. We review their structure and phenomenology, focusing mainly on the SU(3) theory, the Minimal Moose, and the Littlest Higgs as concrete examples.
Energy Technology Data Exchange (ETDEWEB)
Schlaffer, Matthias [DESY, Hamburg (Germany); Spannowsky, Michael [Durham University, Department of Physics, Institute for Particle Physics Phenomenology, Durham (United Kingdom); Takeuchi, Michihisa [King' s College London, Theoretical Physics and Cosmology Group, Department of Physics, London (United Kingdom); Weiler, Andreas [DESY, Hamburg (Germany); CERN, Theory Division, Physics Department, Geneva 23 (Switzerland); Wymant, Chris [Durham University, Department of Physics, Institute for Particle Physics Phenomenology, Durham (United Kingdom); Laboratoire d' Annecy-le-Vieux de Physique Theorique, 9 Chemin de Bellevue, 74940, Annecy-le-Vieux (France); Imperial College London, Department of Infectious Disease Epidemiology, London (United Kingdom)
2014-10-15
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{sub 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 newphysics in the most challenging scenario of an exactly SM-like inclusive Higgs cross section. (orig.)
Abdullah, Wan Ahmad Tajuddin Wan
2012-01-01
A Higgs-compatible boson has been observed at the LHC at CERN. We briefly review the role of the Higgs in particle physics and describe some of the current challenges in understanding the fundamental structure of the universe. Is there supersymmetry and is it instrumental in uniting gravity with the other three fundamental forces? What makes up dark matter and dark energy? We also report on the efforts in experimental particle physics by Malaysian collaborators to answer some of these questions.
New Physics Effects on Rare Decays B+u→π+e+e-, ρ+e+e- in a Top Quark Two-Higgs-Doublet Model
Institute of Scientific and Technical Information of China (English)
SONG Hai-Zhen; L(U) Lin-Xia; LU Gong-Ru
2008-01-01
Using the form factors from light-cone sum rules,we study the branching ratios and forward-backward asymmetries (FBAs) of the exclusive decays B+u→π+e+e- and B+u→ρ+e+e- (e = e,μ) in the standard model (SM) and the top quark two-Higgs-doublet model (T2HDM).From the numerical results,we find that the new physics contributions cannot provide very large enhancement to the branching ratios and the theoretical predictions are in good agreement with the SM ones.The T2HDM effects on FBAs of these decays are small.Precision measurements of the dilepton invariant mass distributions,especially in the lower dilepton mass region,and the FBAs in the decays B+u→π+(ρ+)e+e- will greatly help in discriminating among the SM and the new physics models.
Energy Technology Data Exchange (ETDEWEB)
Martin, Travis A.W., E-mail: tmartin@triumf.ca; Puente, Alejandro de la, E-mail: adelapue@triumf.ca
2013-12-18
We present a novel new method for incorporating dark matter into little Higgs models in a way that can be applied to many existing models without introducing T-parity, while simultaneously alleviating precision constraints arising from heavy gauge bosons. The low energy scalar potential of these dark little Higgs models is similar to, and can draw upon existing phenomenological studies of, inert doublet models. Furthermore, we apply this method to modify the littlest Higgs model to create the next to littlest Higgs model, and describe details of the dark matter candidate and its contribution to the relic density.
Higgs Boson and New Physics Searches in Events with Same-sign Lepton Pairs at the LHC
Nuti, Francesco
The physics of elementary particles is well described by the Standard Model of particle physics. This theory predicts with great accuracy the electroweak and strong interactions of elementary particles. The introduction of the Brout-Englert-Higgs mechanism in Standard Model has also given justification to the non-null mass of the elementary particles. This mechanism has been validated by the discovery of the Higgs boson and the measurement of its properties. Despite the enormous and broad success of the Standard Model, a few observations cannot be explained by this theory. For instance, neutrino oscillations would require the neutrinos to have non-null mass in contrast with the Standard Model prediction. Several solutions to this problem have been proposed, but none has been validated yet. Some of these theories have additional modes to produce lepton pairs with same electric charge (same-sign lepton pairs). This production is also expected to be enhanced in other theories beyond the Standard Model. The focus...
Studies with Muons in ATLAS: TileCal Level-2 Trigger and MSSM Higgs Discovery Reach
Ruiz Martínez, A; Valls Ferrer, J A
2009-01-01
This thesis was carried out in the years previous to the LHC start-up, i.e. during the ATLAS detector commissioning phase. It contains an introductory part about the detector and its expected physics performance and two main parts about the development of a Level-2 trigger for muons and a study of the MSSM Higgs discovery reach with simulated data, which are briefly described below. The first part of the thesis is devoted to TileMuId, the muon identication algorithm based on TileCal whose main goal is to be used as a Level-2 trigger of low-$p_{\\text{T}}$ muons. A second version of TileMuId (ROD-based) has been implemented to run in the TileCal ROD DSPs. This involved developments in the DSP firmware and in the Athena framework, described in the document. In addition, studies of the algorithm performance in terms of efficiency and fraction of fakes have been done. Developments and studies to match the TileCal muon candidates with the Inner Detector tracks (provided by ID reconstruction algorithms) have been pe...
Search for additional Higgs bosons
Meyer, Jochen; The ATLAS collaboration
2017-01-01
The Standard Model of particle physics is one of the most well-established theories in physics. However, it has some flaws which cannot be explained without physics beyond the Standard Model. Most of the theoretically explored extensions which provide potential solutions include further Higgs bosons in addition to the discovered resonance with the mass of about 125 GeV. This talk summarizes current efforts carried out by the ATLAS and CMS collaborations targeting at the discovery of further resonances. A variety of observables in multiple final states is studied and interpreted in terms of additional Higgs bosons predicted by selected models. Those additional bosons are not necessarily neutral, but could also be charged.
Probing new physics in Higgs couplings to fermions using an angular analysis
Directory of Open Access Journals (Sweden)
Bhubanjyoti Bhattacharya
2014-09-01
Full Text Available The standard-model Higgs boson couples to quarks through a parity-even scalar Hqq¯ coupling. We show that the rare Higgs decay H→VZ, where V is a vector quarkonium state such as J/ψ (cc¯ or ϒ(1S (bb¯, can be used to search for the presence of a parity-odd pseudoscalar Hqq¯ coupling. Since both V and Z can decay to a pair of charged leptons, this presents an experimentally-clean channel that can be observed at the high-luminosity LHC or a future hadron collider. The P-even and P-odd Hqq¯ couplings can be measured by analyzing the angular distribution of the final-state leptons.
Collider Phenomenology of Higgs Bosons in Left-Right Symmetric Randall-Sundrum Models
Lillie, Benjamin Huntington
2005-01-01
We study the corrections to Higgs physics in a model of a single warped extra dimension with all fields except the Higgs in the bulk, and a gauge symmetry extended to $SU(2)_L\\times SU(2)_R \\times U(1)_{B-L}$. We find that generically the Higgs coupling to electroweak gauge boson pairs is suppressed, the coupling to gluons is enhanced, and the coupling to photons is often suppressed, but can be enhanced.
The Custodial Randall-Sundrum Model: From Precision Tests to Higgs Physics
Casagrande, Sandro; Haisch, Uli; Neubert, Matthias; Pfoh, Torsten
2010-01-01
We reexamine the Randall-Sundrum (RS) model with enlarged gauge symmetry SU(2)_L x SU(2)_R x U(1)_X x P_LR in the presence of a brane-localized Higgs sector. In contrast to the existing literature, we perform the Kaluza-Klein (KK) decomposition within the mass basis, which avoids the truncation of the KK towers. Expanding the low-energy spectrum as well as the gauge couplings in powers of the Higgs vacuum expectation value, we obtain analytic formulas which allow for a deep understanding of the model-specific protection mechanisms of the T parameter and the left-handed Z-boson couplings. In particular, in the latter case we explain which contributions escape protection and identify them with the irreducible sources of P_LR symmetry breaking. We furthermore show explicitly that no protection mechanism is present in the charged-current sector confirming existing model-independent findings. The main focus of the phenomenological part of our work is a detailed discussion of Higgs-boson couplings and their impact ...
Non-decoupling SUSY in LFV Higgs decays: a window to new physics at the LHC
Arana-Catania, M; Herrero, M J
2013-01-01
The recent discovery of a SM-like Higgs boson at the LHC, with a mass around 125-126 GeV, together with the absence of results in the direct searches for supersymmetry, is pushing the SUSY scale ($m_\\text{SUSY}$) into the multi-TeV range. This discouraging situation from a low-energy SUSY point of view has its counterpart in indirect SUSY observables which present a non-decoupling behavior with $m_\\text{SUSY}$. This is the case of the one-loop lepton flavor violating Higgs decay rates induced by SUSY, which may remain constant or even increase as $m_\\text{SUSY}$ grows, depending on the class of intergenerational mixing in the slepton sector which are taken into account ($LL$, $LR$, $RL$ or $RR$). In this work we focus on the LFV decays of the three neutral MSSM Higgs bosons $h$, $H$, $A \\to \\tau \\mu$, considering the four types of slepton mixing ($\\delta_{23}^{LL}$, $\\delta_{23}^{LR}$, $\\delta_{23}^{RL}$, $\\delta_{23}^{RR}$), and show that all the three channels could be measurable at the LHC, being $h \\to \\t...
Tau lepton identification and studies of associated Higgs boson production with the ATLAS detector
Pingel, Almut Maria
In this thesis two main topics are presented: the identification of hadronic tau decays and a search for Higgs bosons that decay to tau leptons and are produced in association with a Z boson. In 2012, the ATLAS detector at the LHC recorded 20 fb1 of data at a centre-of-mass energy of 8 TeV. Many studies on Standard Model (SM) processes, as well as searches for physics beyond the SM were carried out, which all rely on a good particle identification. This thesis focuses on the identification of hadronically decaying tau leptons. Multivariate techniques are used to reject backgrounds that mimic the tau signature in the detector and are falsely reconstructed as tau leptons. The focus is on the optimisation of the algorithm using boosted decision trees (BDT). The method is prepared for the 2012 data taking period and made robust against run conditions with many simultaneous protonproton interactions per bunch crossing (pile-up). Furthermore, the dependence of the identification method on the tau momentum is s...
The Higgs boson resonance width from a chiral Higgs-Yukawa model on the lattice
Gerhold, Philipp; Jansen, Karl; Kallarackal, Jim
2012-04-01
The Higgs boson is a central part of the electroweak theory and is crucial to generate masses for quarks, leptons and the weak gauge bosons. We use a 4-dimensional Euclidean lattice formulation of the Higgs-Yukawa sector of the electroweak model to compute physical quantities in the path integral approach which is evaluated by means of Monte Carlo simulations thus allowing for fully non-perturbative calculations. The chiral symmetry of the model is incorporated by using the Neuberger overlap Dirac operator. The here considered Higgs-Yukawa model does not involve the weak gauge bosons and furthermore, only a degenerate doublet of top- and bottom quarks are incorporated. The goal of this work is to study the resonance properties of the Higgs boson and its sensitivity to the strength of the quartic self-coupling.
The Higgs boson resonance width from a chiral Higgs-Yukawa model on the lattice
Energy Technology Data Exchange (ETDEWEB)
Gerhold, Philipp [NIC, DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Humboldt-Universitaet zu Berlin, Institut fuer Physik, Newtonstr. 15, D-12489 Berlin (Germany); Jansen, Karl, E-mail: Karl.Jansen@desy.de [NIC, DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Kallarackal, Jim [NIC, DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Humboldt-Universitaet zu Berlin, Institut fuer Physik, Newtonstr. 15, D-12489 Berlin (Germany)
2012-04-20
The Higgs boson is a central part of the electroweak theory and is crucial to generate masses for quarks, leptons and the weak gauge bosons. We use a 4-dimensional Euclidean lattice formulation of the Higgs-Yukawa sector of the electroweak model to compute physical quantities in the path integral approach which is evaluated by means of Monte Carlo simulations thus allowing for fully non-perturbative calculations. The chiral symmetry of the model is incorporated by using the Neuberger overlap Dirac operator. The here considered Higgs-Yukawa model does not involve the weak gauge bosons and furthermore, only a degenerate doublet of top- and bottom quarks are incorporated. The goal of this work is to study the resonance properties of the Higgs boson and its sensitivity to the strength of the quartic self-coupling.
The Higgs boson resonance width from a chiral Higgs-Yukawa model on the lattice
Energy Technology Data Exchange (ETDEWEB)
Gerhold, Philipp; Kallarackal, Jim [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2011-11-15
The Higgs boson is a central part of the electroweak theory and is crucial to generate masses for quarks, leptons and the weak gauge bosons. We use a 4-dimensional Euclidean lattice formulation of the Higgs-Yukawa sector of the electroweak model to compute physical quantities in the path integral approach which is evaluated by means of Monte Carlo simulations thus allowing for fully non perturbative calculations. The chiral symmetry of the model is incorporated by using the Neuberger overlap Dirac operator. The here considered Higgs-Yukawa model does not involve the weak gauge bosons and furthermore, only a degenerate doublet of top- and bottom quarks are incorporated. The goal of this work is to study the resonance properties of the Higgs boson and its sensitivity to the strength of the quartic self coupling. (orig.)
The Higgs boson resonance width from a chiral Higgs-Yukawa model on the lattice
Gerhold, Philipp; Kallarackal, Jim
2011-01-01
The Higgs boson is a central part of the electroweak theory and is crucial to generate masses for quarks, leptons and the weak gauge bosons. We use a 4-dimensional Euclidean lattice formulation of the Higgs-Yukawa sector of the electroweak model to compute physical quantities in the path integral approach which is evaluated by means of Monte Carlo simulations thus allowing for fully non perturbative calculations. The chiral symmetry of the model is incorporated by using the Neuberger overlap Dirac operator. The here considered Higgs-Yukawa model does not involve the weak gauge bosons and furthermore, only a degenerate doublet of top- and bottom quarks are incorporated. The goal of this work is to study the resonance properties of the Higgs boson and its sensitivity to the strength of the quartic self coupling.
Phenomenology of the Higgs effective Lagrangian via FEYNRULES
Energy Technology Data Exchange (ETDEWEB)
Alloul, Adam [Groupe de Recherche de Physique des Hautes Énergies (GRPHE), Université de Haute-Alsace, IUT Colmar, 34 rue du Grillenbreit BP 50568, 68008 Colmar Cedex (France); Fuks, Benjamin [Theory Division, Physics Department, CERN, CH-1211 Geneva 23 (Switzerland); Institut Pluridisciplinaire Hubert Curien/Département Recherches Subatomiques,Université de Strasbourg/CNRS-IN2P3, 23 rue du Loess, F-67037 Strasbourg (France); Sanz, Verónica [Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom)
2014-04-16
The Higgs discovery and the lack of any other hint for new physics favor a description of non-standard Higgs physics in terms of an effective field theory. We present an implementation of a general Higgs effective Lagrangian containing operators up to dimension six in the framework of FEYNRULES and provide details on the translation between the mass and interaction bases, in particular for three- and four-point interaction vertices involving Higgs and gauge bosons. We illustrate the strengths of this implementation by using the UFO interface of FEYNRULES capable to generate model files that can be understood by the MADGRAPH 5 event generator and that have the specificity to contain all interaction vertices, without any restriction on the number of external legs or on the complexity of the Lorentz structures. We then investigate several new physics effects in total rates and differential distributions for different Higgs production modes, including gluon fusion, associated production with a gauge boson and di-Higgs production. We finally study contact interactions of gauge and Higgs bosons to fermions.
Study of the associated production of Higgs boson with a single top quark
Das, Pallabi
2017-01-01
The study of the production of single top quark in association with the Higgs boson at LHC with CMS experiment is presented. Characteristics of the signal and major backgrounds are studied in the multi-leptonic final state, specifically, same-sign dimuon channel. Discrimination between the signal and background processes is done using the multi-variate analysis technique in ROOT framework. Results from preliminary simulation studies at proton-proton collision energy of 13 TeV are discussed briefly.
Selbach, Karoline Elfriede
The Higgs mechanism is the last piece of the SM to be discovered which is responsible for giving mass to the electroweak $W^{\\pm}$ and $Z$ bosons. Experimental evidence for the Higgs boson is therefore important and is currently explored at the Large Hadron Collider (LHC) at CERN. The ATLAS experiment (A Toroidal LHC ApparatuS) is analysing a wide range of physics processes from collisions produced by the LHC at a centre-of-mass energy of 7-8$\\,$TeV and a peak luminosity of $7.73\\times10^{33}\\,\\mathrm{cm^{-2}s^{-1}}$. This thesis concentrates on the discovery and mass measurement of the Higgs boson. The analysis using the $H\\rightarrow ZZ^{(*)}\\rightarrow4 \\ell$ channel is presented, where $\\ell$ denotes electrons or muons. Statistical methods with non-parametric models are successfully cross-checked with parametric models. The per-event errors studied to improve the mass determination decreases the total mass uncertainty by $9\\%$. The other main focus is the performance of the initial, and possible upgraded...
Usefulness of effective field theory for boosted Higgs production
Energy Technology Data Exchange (ETDEWEB)
Dawson, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Lewis, I. M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Zeng, Mao [Stony Brook Univ., Stony Brook, NY (United States)
2015-04-07
The Higgs + jet channel at the LHC is sensitive to the effects of new physics both in the total rate and in the transverse momentum distribution at high _{pT}. We examine the production process using an effective field theory (EFT) language and discussing the possibility of determining the nature of the underlying high-scale physics from boosted Higgs production. The effects of heavy color triplet scalars and top partner fermions with TeV scale masses are considered as examples and Higgs-gluon couplings of dimension-5 and dimension-7 are included in the EFT. As a byproduct of our study, we examine the region of validity of the EFT. Dimension-7 contributions in realistic new physics models give effects in the high _{pT} tail of the Higgs signal which are so tiny that they are likely to be unobservable.
Energy Technology Data Exchange (ETDEWEB)
Bechtle, P.; Weiglein, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Brein, O. [Freiburg Univ. (Germany). Physikalisches Inst.; Heinemeyer, S. [Instituto de Fisica de Cantabria (CSIC-UC), Santander (Spain); Williams, K.E. [Bonn Univ. (Germany). Bethe Center for Theoretical Physics
2011-03-15
HiggsBounds 2.0.0 is a computer code which tests both neutral and charged Higgs sectors of arbitrary models against the current exclusion bounds from the Higgs searches at LEP and the Tevatron. As input, it requires a selection of model predictions, such as Higgs masses, branching ratios, effective couplings and total decay widths. HiggsBounds 2.0.0 then uses the expected and observed topological cross section limits from the Higgs searches to determine whether a given parameter scenario of a model is excluded at the 95% C.L. by those searches. Version 2.0.0 represents a significant extension of the code since its first release (1.0.0). It includes now 28/53 LEP/Tevatron Higgs search analyses, compared to the 11/22 in the first release, of which many of the ones from the Tevatron are replaced by updates. As a major extension, the code allows now the predictions for (singly) charged Higgs bosons to be confronted with LEP and Tevatron searches. Furthermore, the newly included analyses contain LEP searches for neutral Higgs bosons (H) decaying invisibly or into (non flavour tagged) hadrons as well as decay-mode independent searches for neutral Higgs bosons, LEP searches via the production modes {tau}{sup +}{tau}{sup -}H and b anti bH, and Tevatron searches via t anti tH. Also, all Tevatron results presented at the ICHEP'10 are included in version 2.0.0. As physics applications of HiggsBounds 2.0.0 we study the allowed Higgs mass range for model scenarios with invisible Higgs decays and we obtain exclusion results for the scalar sector of the Randall-Sundrum model using up-to-date LEP and Tevatron direct search results. (orig.)
ISR effects for resonant Higgs production at future lepton colliders
Greco, Mario; Liu, Zhen
2016-01-01
We study the effects of the initial state radiation on the $s$-channel Higgs boson resonant production at $\\mu^+\\mu^-$ and $e^+e^-$ colliders by convoluting with the beam energy spread profile of the collider and the Breit-Wigner resonance profile of the signal. We assess their impact on both the Higgs signal and SM backgrounds for the leading decay channels $h\\rightarrow b\\bar b,\\ WW^*$. Our study improves the existing analyses of the proposed future resonant Higgs factories and provides further guidance for the accelerator designs with respect to the physical goals.
ISR effects for resonant Higgs production at future lepton colliders
Greco, Mario; Han, Tao; Liu, Zhen
2016-12-01
We study the effects of the initial state radiation on the s-channel Higgs boson resonant production at μ+μ- and e+e- colliders by convoluting with the beam energy spread profile of the collider and the Breit-Wigner resonance profile of the signal. We assess their impact on both the Higgs signal and SM backgrounds for the leading decay channels h → b b bar , WW*. Our study improves the existing analyses of the proposed future resonant Higgs factories and provides further guidance for the accelerator designs with respect to the physical goals.
Triggering Standard Model Higgs processes in the ATLAS experiment
Pérez-Réale, V
2004-01-01
The search for the Higgs boson is a major physics goal of the future Large Hadron Collider. The potential to trigger on Standard Model Higgs boson with electrons or photons in the final state has been studied for the low mass range $m_{H}<2 m_{Z}$ for the ATLAS experiment at the LHC. Analyses for the $H \\to ZZ^{*}$, $H \\to \\gamma \\gamma$ and $H \\to WW^{*}$ decay modes have been studied using a realistic simulation of the expected detector performance for both the start--up and the design luminosity scenarios. The results obtained demonstrate that the ATLAS trigger is efficiently selecting Higgs candidates for these discovery channels.
The Gauge-Higgs Legacy of the LHC Run I
Butter, Anja; Gonzalez-Fraile, J; Gonzalez-Garcia, M C; Plehn, Tilman
2016-01-01
The effective Lagrangian expansion provides a framework to study effects of new physics at the electroweak scale. To make full use of LHC data in constraining higher-dimensional operators we need to include both the Higgs and the electroweak gauge sector in our study. We first present an analysis of the relevant di-boson production LHC results to update constraints on triple gauge boson couplings. Our bounds are several times stronger than those obtained from LEP data. Next, we show how in combination with Higgs measurements the triple gauge vertices lead to a significant improvement in the entire set of operators, including operators describing Higgs couplings.
Higgs Precision Measurements with ATLAS
Boumediene, Djamel Eddine; The ATLAS collaboration
2017-01-01
After the discovery of the Higgs boson, precise measurements of its properties are of particular importance to understand the true nature of the found particle, which could be the Standard Model predicted Higgs, or indeed offering to be a portal for new physics beyond the Standard Model. In this talk measurement of the mass, cross sections and the couplings of the Higgs boson in bosonic and fermionic decay channels with the ATLAS detector will be presented and compared with Standard Model predictions.
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.
The Radiative Z2 Breaking Twin Higgs
Yu, Jiang-Hao
2016-01-01
In twin Higgs model, the Higgs boson mass is protected by a $Z_2$ symmetry. The $Z_2$ symmetry needs to be broken either explicitly or spontaneously to obtain misalignment between electroweak and new physics vacua. We propose a novel $Z_2$ breaking mechanism, in which the $Z_2$ is spontaneously broken by radiative corrections to the Higgs potential. Two twin Higgses with different vacua are needed, and vacuum misalignment is realized by opposite but comparable contributions from gauge and Yukawa interactions to the potential. Due to fully radiative symmetry breaking, the Higgs sector is completely determined by twin Higgs vacuum, Yukawa and gauge couplings. There are eight pseudo-Goldstone bosons: the Higgs boson, inert doublet Higgs, and three twin scalars. We show the 125 GeV Higgs mass and constraints from Higgs coupling measurements could be satisfied.
Unveiling the Higgs mechanism to students
Organtini, Giovanni
2012-09-01
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.
2013-01-01
Christmas lecture (in French, with simultaneous interpreting into English): "From the Higgs boson to the search for new physics: the prospects for the LHC programme at CERN", by Philippe Bloch. Globe of Science and Innovation Route de Meyrin, 1211 Genève Monday 16 December 2013 at 8:30 p.m. The discovery of the Higgs boson, which was the subject of this year's Nobel prize for physics, has brought us the missing piece of the Standard Model of particle physics. However, many observations (such as the predominance of matter over antimatter in the Universe, the existence of dark matter observed by cosmologists and even the fact that the Higgs boson has a relatively small mass) underline that our knowledge of the structure of matter and its interactions is incomplete. A wide-ranging programme of research spanning several decades to come thus awaits us at the LHC. Philippe Bloch will begin his lecture by giving us the latest news on the Higg...
Energy Technology Data Exchange (ETDEWEB)
El Naschie, M.S
2004-12-01
A careful counting routine of all experimentally confirmed elementary particles plus the theoretically conjectured ones needed for a sound formulation of a mathematically consistent field theory is undertaken within a minimal N=1 super symmetric extension of the standard model of high energy physics. The number arrived at is subsequently linked to certain massless on shell representations connected to the quantized gravity interaction. Finally with the help of number theoretical arguments arising from a rigorous application of the formalism of transfinite Heterotic super string and E-infinity theory, we show that the proposed scheme would lack mathematical consistency and elegant simplicity unless we retain a postulated triplet which is logically identified as the H{sup +}, H{sup -} and H{sup 0} Higgs particles. Connections to the 11 dimensional M theory and Harari's extended 'sub-quarks' theory is also discussed.
Vector-like top/bottom-quark partners and Higgs physics at the LHC.
Angelescu, Andrei; Djouadi, Abdelhak; Moreau, Grégory
Vector-like quarks (VLQ) that are partners of the heavy top and bottom quarks are predicted in many extensions of the standard model (SM). We explore the possibility that these states could explain not only the long-standing anomaly in the forward-backward asymmetry in b-quark production at LEP, [Formula: see text], but also the more recent [Formula: see text]2[Formula: see text] deviation of the cross section for the associated Higgs production with top-quark pairs at the LHC, [Formula: see text]. Introducing three illustrative models for VLQs with different representations under the SM gauge group, we show that the two anomalies can be resolved while satisfying all other theoretical and experimental constraints. In this case, the three different models predict VLQ states in the 1-2 TeV mass range that can be soon probed at the LHC. In a second step, we discuss the sensitivity on the VLQ masses and couplings that could be obtained by means of a percent level accuracy in the measurement of ratios of partial Higgs decay widths, in particular [Formula: see text] and [Formula: see text]. We show that top and bottom VL partners with masses up to [Formula: see text]5 TeV and exotic VLQs with masses in the 10 TeV range can be probed at the high-luminosity LHC.
Vector-like top/bottom quark partners and Higgs physics at the LHC
Angelescu, Andrei; Moreau, Grégory
2015-01-01
Vector-like quarks (VLQs) that are partners of the heavy top and bottom quarks are predicted in many extensions of the Standard Model (SM). We explore the possibility that these states could explain not only the longstanding anomaly in the forward-backward asymmetry in $b$-quark production at LEP, $A_{\\rm FB}^b $, but also the more recent $\\sim 2\\sigma$ deviation of the cross section for the associated Higgs production with top quark pairs at the LHC, $\\sigma(pp\\to t\\bar t H)$. Introducing three illustrative models for VLQs with different representations under the SM gauge group, we show that the two anomalies can be resolved while satisfying all other theoretical and experimental constraints. In this case, the three different models predict VLQ states in the $1-2$ TeV mass range that can be soon probed at the LHC. In a second step, we discuss the sensitivity on the VLQ masses and couplings that could be obtained by means of a percent level accuracy in the measurement of ratios of partial Higgs decay widths, ...
Vector-like top/bottom-quark partners and Higgs physics at the LHC
Energy Technology Data Exchange (ETDEWEB)
Angelescu, Andrei; Djouadi, Abdelhak; Moreau, Gregory [Universite Paris-Sud 11 and CNRS, Laboratoire de Physique Theorique, Orsay (France)
2016-02-15
Vector-like quarks (VLQ) that are partners of the heavy top and bottom quarks are predicted in many extensions of the standard model (SM).We explore the possibility that these states could explain not only the long-standing anomaly in the forward–backward asymmetry in b-quark production at LEP, A{sup b}{sub FB}, but also the more recent ∝2σ deviation of the cross section for the associated Higgs production with top-quark pairs at the LHC, σ(pp → t anti tH). Introducing three illustrative models for VLQs with different representations under the SM gauge group, we show that the two anomalies can be resolved while satisfying all other theoretical and experimental constraints. In this case, the three different models predict VLQ states in the 1-2 TeV mass range that can be soon probed at the LHC. In a second step, we discuss the sensitivity on the VLQ masses and couplings that could be obtained by means of a percent level accuracy in the measurement of ratios of partial Higgs decay widths, in particular Γ(H → γγ)/Γ(H → ZZ*) and Γ(H → b anti b)/Γ(H → WW*). We show that top and bottom VL partners with masses up to ∝5 TeV and exotic VLQs with masses in the 10 TeV range can be probed at the highluminosity LHC. (orig.)
A gateway to new physics: direct measurement of the top Yukawa coupling to the Higgs boson
Bruscino, Nello; Wermes, Norbert
The top quark has the largest Yukawa coupling in the Standard Model, is the main contribution to the Higgs mass $m_H$ corrections and defines the evolution of the Higgs effective potential with the energy, together with $m_H$. It can be directly measured through the associated production process $pp \\to t\\bar{t}H$. Two searches for this process are described in this thesis, using data collected with the ATLAS detector at the Large Hadron Collider. The fully hadronic analysis is performed with data corresponding to an integrated luminosity of $20.3\\,\\text{fb}^{-1}$ at a centre-of-mass energy of $\\sqrt{s}=8\\,\\text{TeV}$ and uses a boosted decision tree algorithm to discriminate between signal and background: the dominant multijet background is estimated using a data-driven method. An upper limit of $6.4$ ($5.4$) times the Standard Model cross section is observed (expected) at 95% confidence level and a best-fit value of $1.6 \\pm 2.6$ for the signal strength $\\mu_{t\\bar{t}H}=\\sigma_{t\\bar{t}H}^\\text{obs}/\\sigma...
Study of the Higgs Production in bosonic decays channels with the CMS detector
INSPIRE-00024826
2013-01-01
The latest results on the standard model Higgs boson studies in bosonic decays from the CMS experiment are reported. The analysis use pp collisions data recorded by the CMS detector at the LHC, corresponding to integrated luminosities up to 5.1 fb 1 (19.6 fb 1 ) at p s = 7 (8) TeV. The observation of a new boson at a mass near 126 GeV is conrmed and some of its properties are shown
Electroweak Corrections for the Study of the Higgs Potential at the LC
Boudjema, F; Ishikawa, T; Kaneko, T; Kato, K; Kurihara, Y; Shimizu, Y; Yasui, Y
2005-01-01
The full electroweak radiative correction is calculated for the process ee--> nunubarHH which is a window for the study of the Higgs potential at the future linear collider. The calculation is done by using GRACE, the automated system for the calculation of Feynman diagrams. The magnitude of the weak correction in the G-mu scheme is small in the high energy region where this process dominates over the ZHH production.
Search for the Higgs and Z Boson decays to $\\phi\\gamma$ and $\\rho\\gamma$
Owen, Rhys Edward; The ATLAS collaboration
2017-01-01
A lot of progress on the study of the properties of the Higgs boson has been made since its discovery, however little is still known about the Higgs boson couplings to light quarks. Direct measurements of the Higgs boson decays to pairs of light-quarks are challenging due to the overwhelming hadronic backgrounds. A new window to experimentally access these couplings opens through the search for Higgs boson decays to a meson and a photon, and gives the possibility to search for new physics in this sector. The latest results from the ATLAS experiment on this front are presented and discussed.
A study of the measurement precision of the Higgs boson decaying into tau pairs at the ILC
Energy Technology Data Exchange (ETDEWEB)
Kawada, Shin-ichi, E-mail: s-kawada@huhep.org [Advanced Sciences of Matter (AdSM), Hiroshima University, 1-3-1, Kagamiyama, 739-8530, Higashi-Hiroshima, Hiroshima (Japan); Fujii, Keisuke [High Energy Accelerator Research Organization (KEK), 1-1, Oho, 305-0801, Tsukuba, Ibaraki (Japan); Suehara, Taikan [Graduate School of Science, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, 812-8581, Fukuoka (Japan); Takahashi, Tohru [Advanced Sciences of Matter (AdSM), Hiroshima University, 1-3-1, Kagamiyama, 739-8530, Higashi-Hiroshima, Hiroshima (Japan); Tanabe, Tomohiko [International Center for Elementary Particle Physics (ICEPP), The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-0033, Tokyo (Japan)
2015-12-28
We evaluate the measurement precision of the production cross section times the branching ratio of the Higgs boson decaying into tau lepton pairs at the International Linear Collider (ILC). We analyze various final states associated with the main production mechanisms of the Higgs boson, the Higgs-strahlung and WW-fusion processes. The statistical precision of the production cross section times the branching ratio is estimated to be 2.6 and 6.9 % for the Higgs-strahlung and WW-fusion processes, respectively, with the nominal integrated luminosities assumed in the ILC Technical Design Report; the precision improves to 1.0 and 3.4 % with the running scenario including possible luminosity upgrades. The study provides a reference performance of the ILC for future phenomenological analyses.
Atkins, Michael
2010-01-01
We discuss models where the Higgs boson of the electroweak standard model plays the role of the inflaton. We focus on the question of the violation of perturbative unitarity due to the coupling of the Higgs boson either to the Ricci scalar or to the Einstein tensor and discuss the background dependence of the unitarity bounds. Our conclusion is that the simplest model which restricts itself to the standard model Higgs boson without introducing further degrees of freedom has a serious problem. However, in the asymptotically safe gravity scenario, the Higgs boson of the standard model could be the inflaton and no physics beyond the standard model is required to explain both inflation and the spontaneous breaking of the electroweak symmetry of the standard model.
Higgs Pair Production at the LHC and ILC from general potential
Haba, Naoyuki; Mimura, Yukihiro; Tsedenbaljir, Enkhbat
2013-01-01
Higgs cubic coupling plays a crucial role to probe an origin of electroweak symmetry breaking. It is expected that the cubic coupling is measured by Higgs pair production at the LHC and ILC, and the deviations from the standard model can be extracted from the Higgs pair production process, and those can give us a hint of new physics beyond the standard model. We consider a general potential that achieves the suitable electroweak symmetry breaking. As one of the interesting models, we suggest a non-perturbative Higgs model in which a run-away type of potential is used. In the model, the cross sections of pair production at the LHC is enlarged compared to the standard model. We also study the Higgs pair production induced by a non-canonical kinetic term of Higgs fields which will be important to search the pair-production at the ILC.
Indian Academy of Sciences (India)
AYYAZ ALI; MUHAMMAD ASAD IQBAL; SYED TAUSEEF MOHYUD-DIN
2016-11-01
In this article, a variety of solitary wave solutions are found for some nonlinear equations. In mathematical physics, we studied two complex systems, the Maccari system and the coupled Higgs field equation. We construct sufficient exact solutions for nonlinear evolution equations. To study travelling wave solutions, we used a fractional complex transform to convert the particular partial differential equation of fractional order into the corresponding partial differential equation and the rational exp$(−\\psi(\\eta)$)-expansion method is implemented tofind exact solutions of nonlinear equation. We find hyperbolic, trigonometric, rational and exponential function solutions using the above equation. The results of various studies show that the suggested method is very effectiveand can be used as an alternative for finding exact solutions of nonlinear equations in mathematical physics. A comparative study with the other methods gives validity to the technique and shows that the method providesadditional solutions. Graphical representations along with the numerical data reinforce the efficacy of the procedure used. The specified idea is very effective, pragmatic for partial differential equations of fractional order andcould be protracted to other physical phenomena.
Eysermans, Jan
2016-01-01
In this talk an overview is given of the possible searches of the Charged Higgs Boson during run 2 of the LHC data taking period. The Charged Higgs boson emerges in several (minimal) Standard Model (SM) extensions such as the 2 Doublet Higgs Model, which predicts 5 physical Higgs bosons, consistent with the SM Higgs boson. Based on the main production and decay modes, the possible intermediate and final state particles are predicted for a Charged Higgs mass higher than the top quark mass ($m_{H^{\\pm}} > m_t$). In particular, the dominant H to tau nu and H to tb channels are discussed in more detail together with their associated background.
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.
Christopher Hill
2013-01-01
Since the last CMS Bulletin, the CMS Physics Analysis Groups have completed more than 70 new analyses, many of which are based on the complete Run 1 dataset. In parallel the Snowmass whitepaper on projected discovery potential of CMS for HL-LHC has been completed, while the ECFA HL-LHC future physics studies has been summarised in a report and nine published benchmark analyses. Run 1 summary studies on b-tag and jet identification, quark-gluon discrimination and boosted topologies have been documented in BTV-13-001 and JME-13-002/005/006, respectively. The new tracking alignment and performance papers are being prepared for submission as well. The Higgs analysis group produced several new results including the search for ttH with H decaying to ZZ, WW, ττ+bb (HIG-13-019/020) where an excess of ~2.5σ is observed in the like-sign di-muon channel, and new searches for high-mass Higgs bosons (HIG-13-022). Search for invisible Higgs decays have also been performed both using the associ...
Implications of the Higgs discovery on minimal dark matter
Klasen, M
2014-01-01
The existence of dark matter provides compelling evidence for physics beyond the Standard Model. Minimal extensions of the Standard Model with additional scalars or fermions allow to explain the observed dark matter relic density in an economic way. We analyse several of these possibilities like the inert Higgs and radiative seesaw models in the light of the recent Higgs discovery and study prospects for the direct and indirect detection of dark matter in these models.
Leptonic Charged Higgs Decays in the Zee Model
Sierra, D A; Restrepo, Diego
2006-01-01
We consider the version of the Zee model where both Higgs doublets couple to leptons. Within this framework we study charged Higgs decays. We focus on a model with minimal number of parameters consistent with experimental neutrino data. Using constraints from neutrino physics we (i) discuss the reconstruction of the parameter space of the model using the leptonic decay patterns of both of the two charged Higgses, $h_{1,2}^{+}\\to \\ell_{j}^{+}\
Vices and Virtues of Higgs EFTs at Large Energy
Biekoetter, Anke; Kraemer, Michael; Liu, Da; Riva, Francesco
2014-01-01
We study constraints on new physics from Higgs production at the LHC in the context of an effective field theory (EFT), focusing on Higgs searches in $HV$ ($V=W,Z$) associated production which are particularly sensitive to the high-energy behavior of certain dimension-6 operators. We show that analyses of these searches are generally dominated by a kinematic region where the generic EFT expansion breaks down, and establish under which conditions they can nevertheless be meaningful. For example, constraints from these searches on the Wilson coefficients of operators whose effects grow with energy can be established in scenarios where a particular combination of fermions and the Higgs are composite and strongly coupled: then, bounds from Higgs physics at high energy are complementary to LEP1 and competitive with LEP2.
Energy Technology Data Exchange (ETDEWEB)
King, Stephen F. [School of Physics and Astronomy, University of Southampton (United Kingdom); Muehlleitner, Margarete; Walz, Kathrin [Institute for Theoretical Physics, Karlsruhe Institute of Technology (Germany); Nevzorov, Roman [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation)
2013-07-01
The Higgs sector of the Next-to Minimal Supersymmetric Extension of the Standard Model (NMSSM) features five neutral Higgs bosons. Compared to the MSSM it is extended by one additional complex singlet field. The discovery of a Higgs-like boson at the LHC last summer opens up the exciting possibility to consider the idea that this might actually be one of the NMSSM Higgs bosons. We study the phenomenology of the NMSSM Higgs sector requiring the presence of a CP-even Higgs boson with a mass close to 126 GeV. To this end we perform a parameter scan and investigate the observable Higgs cross sections into the final states γγ, WW, ZZ, bb and ττ. Our focus is on an enhanced rate into γγ. We discuss where such an enhancement can originate from and study the correlations between the different channels. Our scenarios feature light stop masses, which leads to low fine-tuning, and comply nicely with the LHC results.
AUTHOR|(CDS)2051327
2016-01-01
CERN, the European Laboratory for particle physics, regularly makes the news. What kind of research happens at this international laboratory and how does it impact people's daily lives? Why is the discovery of the Higgs boson so important? Particle physics describes all matter found on Earth, in stars and all galaxies but it also tries to go beyond what is known to describe dark matter, a form of matter five times more prevalent than the known, regular matter. How do we know this mysterious dark matter exists and is there a chance it will be discovered soon? About sixty countries contributed to the construction of the gigantic Large Hadron Collider (LHC) at CERN and its immense detectors. Dive in to discover how international teams of researchers work together to push scientific knowledge forward. Here is a book written for every person who wishes to learn a little more about particle physics, without requiring prior scientific knowledge. It starts from the basics to build a solid understanding of current res...
The case of the composite Higgs: The model as a "Rosetta stone" in contemporary high-energy physics
Borrelli, Arianna
2012-08-01
This paper analyses the practice of model-building "beyond the Standard Model" in contemporary high-energy physics and argues that its epistemic function can be grasped by regarding models as mediating between the phenomenology of the Standard Model and a number of "theoretical cores" of hybrid character, in which mathematical structures are combined with verbal narratives ("stories") and analogies referring back to empirical results in other fields ("empirical references"). Borrowing a metaphor from a physics research paper, model-building is likened to the search for a Rosetta stone, whose significance does not lie in its immediate content, but rather in the chance it offers to glimpse at and manipulate the components of hybrid theoretical constructs. I shall argue that the rise of hybrid theoretical constructs was prompted by the increasing use of nonrigorous mathematical heuristics in high-energy physics. Support for my theses will be offered in form of a historical-philosophical analysis of the emergence and development of the theoretical core centring on the notion that the Higgs boson is a composite particle. I will follow the heterogeneous elements which would eventually come to form this core from their individual emergence in the 1960s and 1970s, through their collective life as a theoretical core from 1979 until the present day.
Higgs Vacuum Stability and Modified Chaotic Inflation
Saha, Abhijit Kumar
2016-01-01
The issue of electroweak vacuum stability is studied in presence of a scalar field which participates in modifying the minimal chaotic inflation model. It is shown that the threshold effect on the Higgs quartic coupling originating from the Higgs-inflaton sector interaction can essentially make the electroweak vacuum stable upto the Planck scale. On the other hand we observe that the new physics parameters in this combined framework are enough to provide deviation from the minimal chaotic inflation predictions so as to keep it consistent with recent observation by Planck 2015.
PRECISION ELECTROWEAK MEASUREMENTS AND THE HIGGS MASS.
Energy Technology Data Exchange (ETDEWEB)
MARCIANO, W.J.
2004-08-02
The utility of precision electroweak measurements for predicting the Standard Model Higgs mass via quantum loop effects is discussed. Current constraints from m{sub w} and sin{sup 2} {theta}{sub w} (m{sub z}){sub {ovr MS}} imply a relatively light Higgs {approx}< 154 GeV which is consistent with Supersymmetry expectations. The existence of Supersymmetry is further suggested by a discrepancy between experiment and theory for the muon anomalous magnetic moment. Constraints from precision studies on other types of ''New Physics'' are also briefly described.
L3 physics at the Z resonance and a search for the Higgs particle
Energy Technology Data Exchange (ETDEWEB)
Coan, T.A.; Kinnison, W.W.; Kapustinsky, J.; Shukla, J. [Los Alamos National Lab., NM (United States). Physics Div.
1997-07-01
This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory. Electroweak interactions were studied using the L3 Detector on the Large Electron-Positron Collider (LEP) at the European Center for Nuclear Study (CERN). The specific physics studied utilized the Silicon Microvertex Detector (SMD) of L3, which Los Alamos had previously played a major role in proposing, designing, constructing, and commissioning. This detector enabled L3 to investigate short-lived mesons containing b-quarks.
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.)
Two Higgs doublet models augmented by a scalar colour octet
Cheng, Li; Valencia, German
2016-09-01
The LHC is now studying in detail the couplings of the Higgs boson in order to determine if there is new physics. Many recent studies have examined the available fits to Higgs couplings from the perspective of constraining two Higgs doublet models (2HDM). In this paper we extend those studies to include constraints on the one loop couplings of the Higgs to gluons and photons. These couplings are particularly sensitive to the existence of new coloured particles that are hard to detect otherwise and we use them to constrain a 2HDM augmented with a colour-octet scalar, a possibility motivated by minimal flavour violation. We first study theoretical constraints on this model and then compare them with LHC measurements.
Two Higgs doublet models augmented by a scalar color octet
Cheng, Li
2016-01-01
The LHC is now studying in detail the couplings of the Higgs boson in order to determine if there is new physics. Many recent studies have examined the available fits to Higgs couplings from the perspective of constraining two Higgs doublet models (2HDM). In this paper we extend those studies to include constraints on the one loop couplings of the Higgs to gluons and photons. These couplings are particularly sensitive to the existence of new colored particles that are hard to detect otherwise and we use them to constrain a 2HDM augmented with a color-octet scalar, a possibility motivated by minimal flavor violation. We first study theoretical constraints on this model and then compare them with LHC measurements.
Higgs, di-Higgs and tri-Higgs production via SUSY processes at the LHC with 14 TeV
Energy Technology Data Exchange (ETDEWEB)
Beekveld, Melissa van [Institute for Mathematics, Astrophysics and Particle Physics, Faculty of Science,Radboud University Nijmegen,Mailbox 79, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands); Nikhef,Science Park, Amsterdam (Netherlands); Beenakker, Wim [Institute for Mathematics, Astrophysics and Particle Physics, Faculty of Science,Radboud University Nijmegen,Mailbox 79, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands); Nikhef,Science Park, Amsterdam (Netherlands); Institute of Physics, University of Amsterdam,Science Park 904, 1018 XE Amsterdam (Netherlands); Caron, Sascha; Castelijn, Remco; Lanfermann, Marie; Struebig, Antonia [Institute for Mathematics, Astrophysics and Particle Physics, Faculty of Science,Radboud University Nijmegen,Mailbox 79, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands); Nikhef,Science Park, Amsterdam (Netherlands)
2015-05-08
We have systematically investigated the production of a Higgs boson with a mass of about 125 GeV in the decays of supersymmetric particles within the phenomenological MSSM (pMSSM). We find regions of parameter space that are consistent with all world data and that predict a sizeable rate of anomalous Higgs, di-Higgs and even tri-Higgs events at the 14 TeV LHC. All relevant SUSY production processes are investigated. We find that Higgs bosons can be produced in a large variety of SUSY processes, resulting in a large range of different detector signatures containing missing transverse momentum. Such Higgs events are outstanding signatures for new physics already for the early 14 TeV LHC data. SUSY processes are also important to interprete deviations found in upcoming Standard Model Higgs and di-Higgs production measurements.
Gregoire, T; 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.
A Historical Profile of the Higgs Boson
Ellis, John; Nanopoulos, V
2016-01-01
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 production in e+ e−, and pp collisions, in particular. Until recently, the most sensitive searches for the Higgs boson were at LEP between 1989 and 2000, which were complemented by searches at the Fermilab Tevatron. Then the LHC experiments ATLAS and CMS entered the hunt, announcing on July 4, 2012 the discovery of a "Higgs-like" particle with a mass of about 125 GeV. This identification has been supported by subsequent measurements of its spin, parity and coupling properties. It was widely anticipated that the Higgs boson would be accompanied by supersymmetry, although other options, like compositeness, were not completely excluded. So far there are no signs of any new physics, and the measured properties of the Higgs boson are consistent with the predictions of the minimal Standard Model. This article reviews some of the key historical d...
AUTHOR|(INSPIRE)INSPIRE-00334334
2017-08-02
Our current understanding of matter and its interactions is summarised in the Standard Model (SM) of particle physics. Many experiments have tested the predictions of the SM with great success, but others have brought our ignorance into focus by showing us there are new phenomena that we can not describe within the framework of the SM. These include the experimental observations of neutrino masses and dark matter, which confirms there must be new physics. What this new physics may look like at colliders motivates the original work in this thesis, which comprises three studies: the prospects of future electron-positron colliders in testing a model with an extended Higgs sector with a scalar triplet, doublet and singlet; the discovery potential at the Large Hadron Collider (LHC) of a non-minimal Supersymmetric model via conventional sparticle searches and via searches for displaced vertices; and the experimental search for long-lived massive particles via a displaced vertex signature using data of proton-proton...
Machet, Martina
In this document two analyses of the properties of the Higgs boson in the diphoton decay channel with the CMS experiment at the LHC (Large Hadron Collider) are presented. The document starts with a theoretical introduction of the Standard Model and the Higgs boson physics, followed by a detailed description of the CMS detector. Then, photon reconstruction and identication algorithms are presented, with a particular focus on the dierences between the rst and the second run of the LHC, where the rst run (Run 1) took place from 2010 to 2012 with a centre-of-mass energy of 7 and then 8 TeV, while the second run (Run 2) started in 2015 with a centre-of-mass energy of 13 TeV. Per- formances of Run 1 and Run 2 reconstructions from the photon identication point of view are compared. Then the photon identication algorithm for the H → γγ analysis optimised for Run 2 is presented. To do that a multivariate analysis method is used. Performances of the photon identication at 13 TeV are nally studied and a data-simulat...
Higgs Inflation and General Initial Conditions
Zeynizadeh, Sarang
2015-01-01
Higgs field of particle physics can play the role of the inflaton in the early universe, if it is non-minimally coupled to gravity. The Higgs inflation scenario predicts a small tensor to scalar ratio: $r\\simeq 0.003$. Although this value is consistent with the upper bound $r < 0.12$ given by BICEP2/Keck Array and Planck data, but it is not at their maximum likelihood point: $r\\simeq 0.05$. Inflationary observables depend not only on the inflationary models, but also depend on the initial conditions of inflation. Changing initial state of inflation can improve the value of $r$. In this work, we study the Higgs inflation model under general initial conditions and show that there is a subset of these general initial conditions which leads to enhancement of $r$. Then we show that this region of parameter space is consistent with non-Gaussianity bound.
Beauty and charm to study new physics at future linear colliders
Energy Technology Data Exchange (ETDEWEB)
Battaglia, M. [Santa Cruz Institute of Particle Physics, University of California at Santa Cruz, CA 95064 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); CERN, DG Department, CH-1211 Geneva (Switzerland)
2011-01-15
The b and c hadrons are instrumental to the identification and study of the Higgs sector and new physics at a future lepton collider. This paper reviews highlights of b and c physics for the linear collider programs and the directions of ongoing R and D on pixellated silicon sensors for its vertex tracker.
The Higgs boson resonance from a chiral Higgs-Yukawa model on the lattice
Energy Technology Data Exchange (ETDEWEB)
Kallarackal, Jim
2011-04-28
Despite the fact that the standard model of particle physics has been confirmed in many high energy experiments, the existence of the Higgs boson is not assured. The Higgs boson is a central part of the electroweak theory and is crucial to generate masses for fermions and the weak gauge bosons. The goal of this work is to set limits on the mass and the decay width of the Higgs boson. The basis to compute the physical quantities is the path integral which is here evaluated by means of Monte Carlo simulations thus allowing for fully non perturbative calculations. A polynomial hybrid Monte Carlo algorithm is used to incorporate dynamical fermions. The chiral symmetry of the electroweak model is incorporated by using the Neuberger overlap operator. Here, the standard model is considered in the limit of a Higgs-Yukawa sector which does not contain the weak gauge bosons and only a degenerate doublet of top- and bottom quarks are incorporated. Results from lattice perturbation theory up to one loop of the Higgs boson propagator are compared with those obtained from Monte Carlo simulations at three different values of the Yukawa coupling. At all values of the investigated couplings, the perturbative results agree very well with the Monte Carlo data. A main focus of this work is the investigation of the resonance parameters of the Higgs boson. The resonance width and the resonance mass are investigated at weak and at large quartic couplings. The parameters of the model are chosen such that the Higgs boson can decay into any even number of Goldstone bosons. Thus, the Higgs boson does not appear as an asymptotic stable state but as a resonance. In all considered cases the Higgs boson resonance width lies below 10% of the resonance mass. The obtained resonance mass is compared with the mass obtained from the Higgs boson propagator. The results agree perfectly at all values of the quartic coupling considered. Finally, the effect of a heavy fourth generation of fermions on the
Kanemura, Shinya; Machida, Naoki; Odori, Shinya; Shindou, Tetsuo
2016-01-01
In the composite Higgs models, originally proposed by Georgi and Kaplan, the Higgs boson is a pseudo Nambu-Goldstone boson (pNGB) of spontaneous breaking of a global symmetry. In the minimal version of such models, global SO(5) symmetry is spontaneously broken to SO(4), and the pNGBs form an isospin doublet field, which corresponds to the Higgs doublet in the Standard Model (SM). Predicted coupling constants of the Higgs boson can in general deviate from the SM predictions, depending on the compositeness parameter. The deviation pattern is determined also by the detail of the matter sector. We comprehensively study how the model can be tested via measuring single and double production processes of the Higgs boson at LHC and future electron-positron colliders. The possibility to distinguish the matter sector among the minimal composite Higgs models is also discussed. In addition, we point out differences in the cross section of double Higgs boson production from the prediction in other new physics models.
Lenzi, Bruno; Nicolaidou, Rosy
2010-01-01
The central subject of this thesis is the evaluation of the discovery potential of the Higgs boson through its decay into four leptons (electrons and muons) in the ATLAS experiment installed at the Large Hadron Collider (LHC). The LHC was designed to accelerate proton beams at a center of mass energy of 14~TeV and started its physics program with 7~TeV collisions in the beginning of 2010. An inclusive analysis involving all the production modes and an exclusive one aiming at production through vector boson fusion (VBF), studied for the first time in the collaboration, are presented. Both are capable of discovering the Higgs boson after a few years of LHC operation, with integrated luminosities of 30~fb$^{-1}$. The first one covers most part of a Higgs mass window from 130 to 500~GeV. The second one concentrates on masses around 180~GeV and above, exploiting the presence of high energy jets with large separations in pseudo-rapidity to increase the signal over background ratio. An important part of the document...
Exotic Decays of the 125 GeV Higgs Boson at Future $e^+e^-$ Lepton Colliders
Energy Technology Data Exchange (ETDEWEB)
Liu, Zhen [Fermilab; Wang, Lian-Tao [Chicago U., EFI; Zhang, Hao [Beijing, Inst. High Energy Phys.
2016-12-29
Discovery of unexpected properties of the Higgs boson offers an intriguing opportunity of shedding light on some of the most profound puzzles in particle physics. The Beyond Standard Model (BSM) decays of the Higgs boson could reveal new physics in a direct manner. Future electron-positron lepton colliders operating as Higgs factories, including CEPC, FCC-ee and ILC, with the advantages of a clean collider environment and large statistics, could greatly enhance the sensitivity in searching for these BSM decays. In this work, we perform a general study of Higgs exotic decays at future $e^+e^-$ lepton colliders, focusing on the Higgs decays with hadronic final states and/or missing energy, which are very challenging for the High-Luminosity program of the Large Hadron Collider (HL-LHC). We show that with simple selection cuts, $O(10^{-3}\\sim10^{-5})$ limits on the Higgs exotic decay branching fractions can be achieved using the leptonic decaying spectator $Z$ boson in the associated production mode $e^+e^-\\rightarrow Z H$. We further discuss the interplay between the detector performance and Higgs exotic decay, and other possibilities of exotic decays. Our work is a first step in a comprehensive study of Higgs exotic decays at future lepton colliders, which is a key ingredient of Higgs physics that deserves further investigation.
Studies of the ATLAS potential for Higgs self-coupling measurements at a High Luminosity LHC
ATLAS, Collaboration; The ATLAS collaboration
2013-01-01
Studies are presented on the prospects of measuring the Higgs trilinear self-coupling λHHH in 3,000 fb−1 of 14 TeV proton-proton collisions at the HL-LHC. Two channels are discussed: H(→ bb)H(→ W+W−) and H(→ bb)H(→ γγ). Generator-level Monte Carlo events are used to perform these studies, with parameterised efficiencies and smearings applied to approximate the expected detector performance under HL-LHC conditions.
Gauge turbulence, topological defect dynamics, and condensation in Higgs models
Gasenzer, Thomas; Pawlowski, Jan M; Sexty, Dénes
2013-01-01
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 appear in the gauge field which 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, signalled 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 r...
BMSSM Higgs Bosons at the Tevatron and the LHC
Energy Technology Data Exchange (ETDEWEB)
Carena, Marcela; /Fermilab /Chicago U., EFI; Ponton, Eduardo; /Columbia U.; Zurita, Jose; /Zurich U.
2010-05-01
We study extensions of the Minimal Supersymmetric Standard Model (MSSM) with new degrees of freedom that couple sizably to the MSSM Higgs sector and lie in the TeV range. After integrating out the physics at the TeV scale, the resulting Higgs spectrum can significantly differ from typical supersymmetric scenarios, thereby providing a window Beyond the MSSM (BMSSM). Taking into account current LEP and Tevatron constraints, we perform an in-depth analysis of the Higgs collider phenomenology and explore distinctive characteristics of our scenario with respect to both the Standard Model and the MSSM. We propose benchmark scenarios to illustrate specific features of BMSSM Higgs searches at the Tevatron and the LHC.
Different Higgs models and the number of Higgs particles
Energy Technology Data Exchange (ETDEWEB)
Marek-Crnjac, L. [University of Maribor, Faculty of Mechanical Engineering, Smetanova ulica 17, SI-2000 Maribor (Slovenia)] e-mail: fs.taj06@uni-mb.si
2006-02-01
In this short paper we discuss some interesting Higgs models. It is concluded that the most likely scheme for the Higgs particles consists of five physical Higgs particles. These are two charged H{sup +}, H{sup -} and three neutrals h {sup 0}, H{sup 0}, A{sup 0}. Further more the most probably total number of elementary particles for each model is calculated [El Naschie MS. Experimental and theoretical arguments for the number of the mass of the Higgs particles. Chaos, Solitons and Fractals 2005;23:1091-8; El Naschie MS. Determining the mass of the Higgs and the electroweak bosons. Chaos, Solitons and Fractals 2005;24:899-905; El Naschie MS. On 366 kissing spheres in 10 dimensions, 528 P-Brane states in 11 dimensions and the 60 elementary particles of the standard model. Chaos, Solitons and Fractals 2005;24:447-57].
Baglio, Julien; Nierste, Ulrich; Wiebusch, Martin
2014-01-01
The search for additional Higgs particles and the exact measurements of Higgs (self-)couplings is a major goal of future collider experiments. In this paper we investigate the possible sizes of new physics signals in these searches in the context of the $CP$-conserving two-Higgs doublet model of type II. Using current constraints from flavour, electroweak precision, and Higgs signal strength data, we determine the allowed sizes of the triple Higgs couplings and the branching fractions of the heavy Higgs bosons into lighter Higgs bosons. Identifying the observed Higgs resonance with the light $CP$-even 2HDM Higgs boson $h$, we find that the $hhh$ coupling cannot exceed its SM value, but can be reduced by a factor of 0.56 at the 2 $\\sigma$ level. The branching fractions of the heavy neutral Higgs bosons $H$ and $A$ into two-fermion or two-vector-boson final states can be reduced by factors of 0.4 and 0.01, respectively, if decays into lighter Higgs boson are possible and if the mass of the decaying Higgs is bel...
Study of the Associated Production of $t\\bar{t}$ and Higgs with the ATLAS Detector
Ojeda, Martina Laura
2015-01-01
The observation of the production cross-section of a top-antitop pair in association with the Higgs boson ($t\\bar{t}H$) with the ATLAS detector is one of the highest priorities in the physics plan at 13 TeV energies. MultiVariate Analysis techniques are planned to be implemented in the $t\\bar{t}H$ multi-lepton channel during Run 2 data analysis as an improvement to the "cut and count" method used in Run 1. In this work, the Boosted Decision Trees and Neural Network algorithms are tested in $t\\bar{t}H$ final states with two leptons with same sign electric charge and adjusted in order to obtain better sensitivity and higher separation power between signal and background compared to the counting experiment from Run 1.
On Higgs-exchange DIS, physical evolution kernels and fourth-order splitting functions at large x
Energy Technology Data Exchange (ETDEWEB)
Soar, G.; Vogt, A. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Vermaseren, J.A.M. [NIKHEF, Amsterdam (Netherlands)
2009-12-15
We present the coefficient functions for deep-inelastic scattering (DIS) via the exchange of a scalar {phi} directly coupling only to gluons, such as the Higgs boson in the limit of a very heavy top quark and n{sub f} effectively massless light flavours, to the third order in perturbative QCD. The two-loop results are employed to construct the next-to-next-to-leading order physical evolution kernels for the system (F{sub 2},F{sub {phi}}) of flavour-singlet structure functions. The practical relevance of these kernels as an alternative to MS factorization is bedevilled by artificial double logarithms at small values of the scaling variable x, where the large top-mass limit ceases to be appropriate. However, they show an only single-logarithmic enhancement at large x. Conjecturing that this feature persists to the next order also in the present singlet case, the three-loop coefficient functions facilitate exact predictions (backed up by their particular colour structure) of the double-logarithmic contributions to the fourth-order singlet splitting functions, i.e., of the terms (1-x){sup a} ln{sup k}(1-x) with k=4,5,6 and k=3,4,5, respectively, for the off-diagonal and diagonal quantities to all powers a in (1-x). (orig.)
Searching Heavier Higgs Boson via $H \\to hh \\to WW^*\\gamma\\gamma$ at LHC Run-2
Lü, Lan-Chun; Fang, Yaquan; He, Hong-Jian; Zhang, Huijun
2015-01-01
The LHC discovery of a light Higgs particle $h^0$ (125GeV) opens up new prospect for searching heavier Higgs boson(s) at the LHC Run-2, which will unambiguously point to new physics beyond the standard model (SM). We study the detection of a heavier neutral Higgs boson $H^0$ via di-Higgs production channel at the LHC (14TeV), $H^0 \\to h^0h^0 \\to WW^*\\gamma\\gamma$. This directly probes the $Hhh$ cubic Higgs interaction, which exists in most extensions of the SM Higgs sector. For the decay products of final states $WW^*$, we include both pure leptonic mode $WW^* \\to \\ell\\bar{\
Study of the Higgs CP properties in the ττ decay channel with the CMS experiment
Energy Technology Data Exchange (ETDEWEB)
Cherepanov, Vladimir; Fluegge, Guenter; Kargoll, Bastian; Lohmann, Wolfgang; Nehrkorn, Alexander; Nugent, Ian M.; Pistone, Claudia; Stahl, Achim; Zotz, Alexander [III. Physikalisches Institut B, RWTH Aachen University, D-52056 Aachen (Germany)
2016-07-01
In 2012 the discovery of a Higgs boson with mass of 125 GeV was announced by the ATLAS and CMS collaborations. Since then, efforts were focused on the measurement of its properties and thus the complete determination of the nature of this particle. We study the CP quantum numbers of the Higgs boson in its decay into tau lepton pairs. Our approach uses the distribution of the signed angle φ{sup *}{sub CP} between the decay planes of the tau leptons, which is sensitive to the Higgs CP properties. At the generator level we observe the expected discrimination power between CP-even and CP-odd states, and the results are presented. The sensitivity of our observable is also being investigated at the reconstruction level, and results are presented as well.
Detecting a Higgs Pseudoscalar with a Z Boson at the LHC
Kao, C; Orr, L H; Kao, Chung; Lovelace, Geoffrey; Orr, Lynne
2003-01-01
We have adopted two Higgs doublet models to study the production of a Higgs pseudoscalar ($A^0$) in association with a $Z$ gauge boson from gluon fusion ($gg \\to ZA^0$) at the CERN Large Hadron Collider. The prospects for the discovery of $ZA^0 \\to \\ell \\bar{\\ell} b\\bar{b}$ are investigated with physics backgrounds and realistic cuts. Promising results are found for $m_A \\alt 260$ GeV in two Higgs doublet models when the heavier Higgs scalar ($H^0$) can decay into a $Z$ boson and a Higgs pseudoscalar ($A^0$). Although the cross section of $gg \\to ZA^0$ is usually small in the minimal supersymmetric standard model, it can be significantly enhanced in general two Higgs doublet models. This discovery channel might provide an opportunity to search for a Higgs scalar and a Higgs pseudoscalar simultaneously at the LHC and could lead to new physics beyond the Standard Model and the minimal supersymmetric model.
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 ...
3-dimensional lattice studies of the electroweak phase transition at M$_{Higgs}$ $\\appprox$ 70 GeV
Gürtler, M; Kripfganz, J; Perlt, H; Schiller, A
1996-01-01
We study the electroweak phase transition by lattice simulations of an effective 3--dimensional theory, for a Higgs mass of about 70 GeV. Exploiting, among others, a variant of the equal weight criterion of phase equilibrium, we obtain transition temperature, latent heat and surface tension, and compare with M_H approx 35 GeV. In the broken phase masses and Higgs condensates are compared to perturbation theory. For the symmetric phase, bound state masses and the static force are determined.
Energy Technology Data Exchange (ETDEWEB)
Koenneker, Carsten; Beckers, Mike (comps.)
2016-07-01
The following topics are dealt with: Future particle accelerators, possible surprising results from LHC experiments, the reality in quantum field theory, possibilities for studies of te string theory by means of the LHC, the structure of quarks, supersymmetry in crisis, the search for ultralight particles, new physics with neutrinos, the application of neutrino properties for cosmology, the paradoxon of the proton radius, the internal structure of the neutron. (HSI)
Search for Higgs boson in beyond standard model scenarios at large hadron collider
Indian Academy of Sciences (India)
Kajari Mazumdar; on behalf of the ATLAS and CMS Collaborations
2007-11-01
The principal physics motivation of the LHC experiments is to search for the Higgs boson and to probe the physics of TeV energy scale. Potential of discovery for Higgs bosons in various scenarios beyond standard model have been estimated for both CMS and ATLAS experiments through detailed detector simulations. Main results from the recently published studies of CMS collaboration are only included in this write-up.
Study of Dynamical Chiral Symmetry Breaking in (2 + 1 Dimensional Abelian Higgs Model
Directory of Open Access Journals (Sweden)
Jian-Feng Li
2010-04-01
Full Text Available In this paper, we study the dynamical mass generation in the Abelian Higgs model in 2 + 1 dimensions. Instead of adopting the approximations in [Jiang H et al., J. Phys. A 41 2008 255402.], we numerically solve the coupled Dyson–Schwinger Equations (DSEs for the fermion and gauge boson propagators using a specific truncation for the fermion-photon vertex ansatz and compare our results with the corresponding ones in the above mentioned paper. It is found that the results quoted in the above paper remain qualitatively unaffected by refining the truncation scheme of the DSEs, although there exist large quantitative differences between the results presented in the above paper and ours. In addition, our numerical results show that the critical number of fermion flavor Nc decreases steeply with the the gauge boson mass ma (or the ratio of the Higgs mass mh to the gauge boson mass ma, r = mh/ma increasing. It is thus easier to generate a finite fermion mass by the mechanism of DCSB for a small ratio r for a given ma.
Resummation prescriptions and ambiguities in SCET vs. direct QCD: Higgs production as a case study
Bonvini, Marco; Ridolfi, Giovanni; Rottoli, Luca
2014-01-01
We perform a comparison of soft-gluon resummation in SCET vs. direct QCD (dQCD), using Higgs boson production in gluon fusion as a case study, with the goal of tracing the quantitative impact of each source of difference between the two approaches. We show that saddle-point methods enable a direct quantitative comparison despite the fact that the scale which is resummed in the two approaches is not the same. As a byproduct, we put in one-to-one analytic correspondence various features of either approach: specifically, we show how the SCET method for treating the Landau pole can be implemented in dQCD, and how the resummation of the optimal partonic scale of dQCD can be implemented in SCET. We conclude that the main quantitative difference comes from power-suppressed subleading contributions, which could in fact be freely tuned in either approach, and not really characteristic of either. This conclusion holds for Higgs production in gluon fusion, but it is in fact generic for processes with similar kinematics....
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.
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.
Effective Theory of Higgs Sector Vacuum States
Egana-Ugrinovic, Daniel
2015-01-01
The effective field theory description for modifications of Standard Model-like Higgs boson interactions arising from tree-level mixing with heavy Higgs sector vacuum states without conserved quantum numbers is presented. An expansion in terms of effective operator dimension based on powers of the heavy mass scale rather than operator dimension is utilized to systematically organize interactions within the effective theory. Vacuum states arising from electroweak singlet extensions of the Higgs sector yield at leading order only two effective dimension-six operators. One of these uniformly dilutes all the interactions of a single physical Higgs boson as compared with Standard Model expectations, while the combination of the two operators give more general modifications of all remaining interactions with two or more physical Higgs bosons. Vacuum states arising from an additional electroweak doublet yield three types of effective dimension-six operators that modify physical Higgs boson couplings to fermion pairs...
Improving Higgs coupling measurements through ZZ Fusion at the ILC
Han, Tao; Qian, Zhuoni; Sayre, Joshua
2015-01-01
We evaluate the $e^- e^+ \\to e^- e^+ +h $ process through the $ZZ$ fusion channel at the International Linear Collider (ILC) operating at $500$ GeV and $1$ TeV center of mass energies. We perform realistic simulations on the signal process and background processes. With judicious kinematic cuts, we find that the inclusive cross section can be measured to $2.9\\%$ after combining the $500$ GeV at $500 ~\\text{fb}^{-1}$ and $1$ TeV at $1~ \\text{ab}^{-1}$ runs. A multivariate log-likelihood analysis further improves the precision of the cross section measurement to $2.3\\%$. We discuss the overall improvement to model-independent Higgs width and coupling determinations and demonstrate the use of different channels in distinguishing new physics effects in Higgs physics. Our study demonstrates the importance of the $ZZ$ fusion channel to Higgs precision physics, which has often been neglected in the literature.
Universality test of the charged Higgs boson couplings at the LHC and at B factories
Cornell, Alan S; Gaur, Naveen; Itoh, Hideo; Klasen, Michael; Okada, Yasuhiro
2009-01-01
Many extensions of the Standard Model (SM) of particle physics predict the existence of charged Higgs bosons. In the Minimal Supersymmetric SM (MSSM) the charged Higgs boson's couplings to fermions are proportional to tan(beta) and the fermionic mass factors, and these could be substantial at large tan(beta) and/or for heavy fermions. For this reason one may be able to observe the effect of a charged Higgs boson at the LHC and at B-factories. In this work we perform a study of the charged Higgs boson couplings at the LHC and at B-factories for a large range of tan(beta). We further argue that, for an illustrative parameter space, by combining four possible measurements at the LHC and at B-factories one can perform universality tests of the charged Higgs boson couplings to quarks.
Most wanted particle the inside story of the hunt for the Higgs, the heart of the future of physics
Butterworth, Jon
2015-01-01
The discovery of the Higgs boson has brought us a giant step closer to understanding how our universe works. But before the Higgs was found, its existence was hotly debated. Even Peter Higgs, who first pictured it, did not expect to see proof within his lifetime. The quest to find the Higgs would ultimately require perhaps the most ambitious experiment in human history. Jon Butterworth was there—a leading physicist on the ATLAS project at the Large Hadron Collider in Geneva, Switzerland. In Most Wanted Particle, he gives us the first insider account of the hunt for the Higgs, and of life at the collider itself—the world’s largest and most powerful particle accelerator, 17 miles long, 20 stories underground, and designed to “replay” the original Big Bang by smashing subatomic particles at nearly the speed of light. Writing with clarity and humor, Butterworth revels as much in the hard science—which he carefully reconstructs for readers of all levels—as in the messiness, uncertainty, and humanne...
Study of Higgs boson production in fermionic decay channels at the LHC
Jain, V; The ATLAS collaboration
2014-01-01
I will present results from ATLAS and CMS on the fermionic decays of the Higgs boson at the 26th Recontres de Blois. The talk includes results for Higgs to mumu, tautau, VH(bb) and ttH. This is a 15' talk in a parallel session.
Constraining the Higgs boson mass: A non-perturbative lattice study
Jansen, Karl; Nagy, Attila
2012-01-01
We present non-perturbatively obtained results for upper and lower Higgs boson mass bounds using a chiral invariant lattice formulation of the Higgs-Yukawa sector of the standard model. We determine the mass bounds both, for a standard model top quark mass and for a possible fourth quark generation with masses up to 700GeV.
Analysis of the phase structure in extended Higgs models
Energy Technology Data Exchange (ETDEWEB)
Seniuch, M.
2006-07-07
We study the generation of the baryon asymmetry in the context of electroweak baryogenesis in two different extensions of the Standard Model. First, we consider an effective theory, in which the Standard Model is augmented by an additional dimension-six Higgs operator. The effects of new physics beyond a cut-off scale are parameterized by this operator. The second model is the two-Higgs-doublet model, whose particle spectrum is extended by two further neutral and two charged heavy Higgs bosons. In both cases we focus on the properties of the electroweak phase transition, especially on its strength and the profile of the nucleating bubbles. After reviewing some general aspects of the electroweak phase transition and baryogenesis we derive the respective thermal effective potentials to one-loop order. We systematically study the parameter spaces, using numerical methods, and compute the strength of the phase transition and the wall thickness as a function of the Higgs masses. We find a strong first order transition for a light Higgs state with a mass up to about 200 GeV. In case of the dimension-six model the cut-off scale has to stay between 500 and 850 GeV, in the two-Higgs-doublet model one needs at least one heavy Higgs mass of 300 GeV. The wall thickness varies for both theories in the range roughly from two to fifteen, in units of the inverse critical temperature. We also estimate the size of the electron and neutron electric dipole moments, since new sources of CP violation give rise to them. In wide ranges of the parameter space we are not in conflict with the experimental bounds. Finally the baryon asymmetry, which is predicted by these models, is related to the Higgs mass and the other appropriate input parameters. In both models the measured baryon asymmetry can be achieved for natural values of the model parameters. (orig.)
Unitarity and Dark Matter in the Private Higgs Model
Jackson, C B
2008-01-01
The extremely large hierarchy observed in the fermion mass spectrum remains as one of the most puzzling and unresolved issues in particle physics. In a recent proposal, however, it was demonstrated that by introducing one Higgs doublet (or Private Higgs) per fermion this hierarchy could be made natural by making the Yukawa couplings between each fermion and its respective Higgs boson of order unity. Among the interesting predictions of the Private Higgs scenario is a variety of scalars which could be probed at future collider experiments and a possible dark matter candidate. In this paper, we study perturbative unitarity in this model and show that, in general, the extended scalar sector of the Private Higgs model tends to soften the constraints on the Standard Model-like Higgs boson mass. We then calculate the annihilation cross sections of dark matter in this model and find that one can easily account for the observed density of dark matter in the Universe with relatively natural values of the model's param...
Disentangling a dynamical Higgs
Brivio, I; Éboli, O J P; Gavela, M B; Gonzalez-Fraile, J; Gonzalez-Garcia, M C; Merlo, L; Rigolin, S
2013-01-01
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 $SU(2)_L\\times U(1)_Y$ 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 pure 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. Furthermo...
The hidden symmetry and Mr. Higgs!
Papachristou, C J
2014-01-01
Written in non-technical language, this review article explains the significance of the Higgs field and the associated Higgs boson in High-Energy Physics. The connection of symmetry with particle interactions and their unification is also discussed in this context. The presentation is informal and physical concepts are demonstrated through metaphors from everyday experience.
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.
Studies of Higgs boson production in the four-lepton final state at sqrt(s) = 13 TeV
Cheng, Tongguang
2016-01-01
Studies of Higgs boson production are presented using the $\\mathrm{H}\\rightarrow\\mathrm{Z}\\mathrm{Z}\\rightarrow4\\ell$ ($\\ell=\\mathrm{e},\\mu$) decay channel. These studies are performed using a data sample corresponding to an integrated luminosity of $2.8~\\mathrm{fb}^{-1}$ of pp collisions at a center-of-mass energy of $13~\\mathrm{TeV}$ collected by the CMS experiment at the LHC during 2015. The observed significance for the standard model Higgs boson with $m_{\\mathrm{H}}=125.09~\\mathrm{GeV}$ is $2.5\\sigma$, where the expected significance is $3.4\\sigma$. The model independent fiducial cross section is measured to be $\\sigma_{\\mathrm{fid.}}=2.48^{+1.48}_{-1.14}(\\mathrm{stat. \\oplus sys.})^{+0.01}_{-0.04}(\\mathrm{model~dep.})~\\mathrm{fb}$. In addition, a search for an additional Higgs boson is performed for a range of masses up to 1 TeV and with various widths, and no significant excess is observed. The results of this search are interpreted in the context of the two Higgs doublet model.
Phenomenology of the Higgs effective Lagrangian via F eynR ules
Alloul, Adam; Fuks, Benjamin; Sanz, Verónica
2014-04-01
The Higgs discovery and the lack of any other hint for new physics favor a description of non-standard Higgs physics in terms of an effective field theory. We present an implementation of a general Higgs effective Lagrangian containing operators up to dimension six in the framework of F eynR ules and provide details on the translation between the mass and interaction bases, in particular for three- and four-point interaction vertices involving Higgs and gauge bosons. We illustrate the strengths of this implementation by using the UFO interface of F eynR ules capable to generate model files that can be understood by the M adG raph 5 event generator and that have the specificity to contain all interaction vertices, without any restriction on the number of external legs or on the complexity of the Lorentz structures. We then investigate several new physics effects in total rates and differential distributions for different Higgs production modes, including gluon fusion, associated production with a gauge boson and di-Higgs production. We finally study contact interactions of gauge and Higgs bosons to fermions.
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.
PARTICLE PHYSICS: CERN Gives Higgs Hunters Extra Month to Collect Data.
Morton, O
2000-09-22
After 11 years of banging electrons and positrons together at higher energies than any other machine in the world, CERN, the European laboratory for particle physics, had decided to shut down the Large Electron-Positron collider (LEP) and install a new machine, the Large Hadron Collider (LHC), in its 27-kilometer tunnel. In 2005, the LHC will start bashing protons together at even higher energies. But tantalizing hints of a long-sought fundamental particle have forced CERN managers to grant LEP a month's reprieve.
Higgs bosons, electroweak symmetry breaking, and the physics of the Large Hadron Collider
Energy Technology Data Exchange (ETDEWEB)
Quigg, Chris; /Fermilab /CERN
2007-02-01
The Large Hadron Collider, a 7 {circle_plus} 7 TeV proton-proton collider under construction at CERN (the European Laboratory for Particle Physics in Geneva), will take experiments squarely into a new energy domain where mysteries of the electroweak interaction will be unveiled. What marks the 1-TeV scale as an important target? Why is understanding how the electroweak symmetry is hidden important to our conception of the world around us? What expectations do we have for the agent that hides the electroweak symmetry? Why do particle physicists anticipate a great harvest of discoveries within reach of the LHC?
Minimal flavour violation and multi-Higgs models
Energy Technology Data Exchange (ETDEWEB)
Botella, F.J., E-mail: fbotella@uv.e [Departament de Fisica Teorica and IFIC, Universitat de Valencia-CSIC, E-46100, Burjassot (Spain); Branco, G.C., E-mail: gustavo.branco@cern.c [Departamento de Fisica and Centro de Fisica Teorica de Particulas (CFTP), Instituto Superior Tecnico, Av. Rovisco Pais, P-1049-001 Lisboa (Portugal); Rebelo, M.N., E-mail: margarida.rebelo@cern.c [Departamento de Fisica and Centro de Fisica Teorica de Particulas (CFTP), Instituto Superior Tecnico, Av. Rovisco Pais, P-1049-001 Lisboa (Portugal)
2010-04-12
We propose an extension of the hypothesis of Minimal Flavour Violation (MFV) to general multi-Higgs models without the assumption of Natural Flavour Conservation (NFC) in the Higgs sector. We study in detail under what conditions the neutral Higgs couplings are only functions of V{sub CKM} and propose a MFV expansion for the neutral Higgs couplings to fermions.
LEP3: A high luminosity e+e- collider in the LHC tunnel to study the Higgs boson
Blondel, A P; Koratzinos, M; Zanetti, M
2012-01-01
Recent indications from the LHC suggest that the Higgs boson might be light, within the mass range 115- 130 GeV. Such object could be studied at an e+e− collider with about 240-GeV centre-of-mass energy. A corresponding Higgs factory – ‘LEP3’ – could be installed in the LHC tunnel, reducing its cost and also allowing for a second life of the two LHC general-purpose detectors. We present preliminary accelerator and beam parameters for LEP3 [1] tailored so as to provide a peak luminosity of 1034 cm-2s-1 at each of two experiments, while respecting a number of constraints including beamstrahlung limits. At this luminosity around 20,000 Higgs events per year per experiment could be obtained for a Standard Model Higgs boson with a mass of 115-130 GeV. For the parameters considered the estimated luminosity lifetime is about 16 minutes, and the synchrotron radiation losses are 50 MW per beam. High operational efficiency requires two rings: a low emittance collider storage ring operating at constant energy,...
C. Hill
2013-01-01
The period since the last CMS bulletin has seen the end of proton collisions at a centre-of-mass energy 8 TeV, a successful proton-lead collision run at 5 TeV/nucleon, as well as a “reference” proton run at 2.76 TeV. With these final LHC Run 1 datasets in hand, CMS Physics Analysis Groups have been busy analysing these data in preparation for the winter conferences. Moreover, despite the fact that the pp run only concluded in mid-December (and there was consequently less time to complete data analyses), CMS again made a strong showing at the Rencontres de Moriond in La Thuile (EW and QCD) where nearly 40 new results were presented. The highlight of these preliminary results was the eagerly anticipated updated studies of the properties of the Higgs boson discovered in July of last year. Meanwhile, preparations for Run 2 and physics performance studies for Phase 1 and Phase 2 upgrade scenarios are ongoing. The Higgs analysis group produced updated analyses on the full Run 1 dataset (~25 f...
Constraining multi-Higgs flavour models
Energy Technology Data Exchange (ETDEWEB)
Gonzalez Felipe, R.; Silva, Joao P. [Rua Conselheiro Emidio Navarro 1, Instituto Superior de Engenharia de Lisboa-ISEL, Lisbon (Portugal); Universidade de Lisboa, Centro de Fisica Teorica de Particulas (CFTP), Instituto Superior Tecnico, Lisbon (Portugal); Ivanov, I.P. [Universite de Liege, IFPA, Liege (Belgium); Sobolev Institute of Mathematics, Novosibirsk (Russian Federation); Ghent University, Department of Physics and Astronomy, Ghent (Belgium); Nishi, C.C. [Universidade Federal do ABC-UFABC, Santo Andre, SP (Brazil); Serodio, Hugo [Universitat de Valencia-CSIC, Departament de Fisica Teorica and IFIC, Burjassot (Spain)
2014-07-15
To study a flavour model with a non-minimal Higgs sector one must first define the symmetries of the fields; then identify what types of vacua exist and how they may break the symmetries; and finally determine whether the remnant symmetries are compatible with the experimental data. Here we address all these issues in the context of flavour models with any number of Higgs doublets. We stress the importance of analysing the Higgs vacuum expectation values that are pseudo-invariant under the generators of all subgroups. It is shown that the only way of obtaining a physical CKM mixing matrix and, simultaneously, non-degenerate and non-zero quark masses is requiring the vacuum expectation values of the Higgs fields to break completely the full flavour group, except possibly for some symmetry belonging to baryon number. The application of this technique to some illustrative examples, such as the flavour groups Δ(27), A{sub 4} and S{sub 3}, is also presented. (orig.)
Anatomy of the Higgs mass spectrum
Energy Technology Data Exchange (ETDEWEB)
Hung, P.Q. [Virginia Univ., Charlottesville, VA (United States). Physics Dept.; Isidori, G. [INFN, Laboratori Nazionali di Frascati, Rome (Italy)
1996-09-01
The authors analyze the implications of a Higgs discovery on possible `new-physics` scenarios, for m{sub H} up to {approx} 700 GeV. For this purpose the authors critically review lower and upper limits on the Higgs mass in the SM and in the MSSM, respectively. Furthermore, the authors discuss the general features of possible `heavy` (m{sub H}>approx2m{sub Z}) Higgs scenarios by means of a simple heavy-fermion condensate model.
Energy Technology Data Exchange (ETDEWEB)
Manteuffel, Andreas von
2008-07-17
Theories with extended Higgs sectors such as Two-Higgs-Doublet Models (THDMs) or the Next-to-Minimal Supersymmetric Standard Model (NMSSM) allow for rich CP phenomena and involved Higgs-potential structures. Employing a gauge invariant formulation for the tree-level Higgs potential of the general THDM, we derive compact criteria for its stability, electroweak symmetry breaking, and generalised CP properties in a clear geometrical language. A new type of CP symmetry is shown to impose strong restrictions on the Lagrangian and to require at least two fermion generations for non-trivial Yukawa terms. Large regions of the NMSSM parameter space are excluded due to an instable vacuum. We present a rigorous determination of the global minimum of the tree-level potential via Groebner bases. In a second part, we investigate the colour dipole picture. This model of high energy photonproton scattering permits a very successful description of available HERA data. Nevertheless, its range of applicability is limited. We derive general bounds on ratios of deep-inelastic proton structure functions within the colour dipole picture, following exclusively from its framework and photon wave function properties. Confronting these bounds with HERA data we can further restrict the range of applicability of the colour dipole picture. Finally, we calculate Ioffe times for a specific model and find them to be too small to justify the dipole picture at large photon virtualities. (orig.)
CERN Library
2016-01-01
"Who cares about particle physics? : making sense of the Higgs boson, the Large Hadron Collider and CERN ", by Pauline Gagnon. Thursday 15 September 2016, 16:00 - 17:30 in the CERN Library (Bldg 52 1-052) *Coffee will be served at 15:30* CERN, the European Laboratory for particle physics, regularly makes the news. What kind of research happens at this international laboratory and how does it impact people's daily lives? Why is the discovery of the Higgs boson so important? Particle physics describes all matter found on Earth, in stars and all galaxies but it also tries to go beyond what is known to describe dark matter, a form of matter five times more prevalent than the known, regular matter. How do we know this mysterious dark matter exists and is there a chance it will be discovered soon? About sixty countries contributed to the construction of the gigantic Large Hadron Collider (LHC) at CERN and its immense detectors. Dive in to discover how international teams of researchers...
Exotic decays of the 125 GeV Higgs boson at future e+e- colliders
Liu, Zhen; Wang, Lian-Tao; Zhang, Hao
2017-06-01
The discovery of unexpected properties of the Higgs boson would offer an intriguing opportunity to shed light on some of the most profound puzzles in particle physics. Beyond Standard Model (BSM) decays of the Higgs boson could reveal new physics in a direct manner. Future electron-positron lepton colliders operating as Higgs factories, including CEPC, FCC-ee and ILC, with the advantages of a clean collider environment and large statistics, could greatly enhance sensitivity in searching for these BSM decays. In this work, we perform a general study of Higgs exotic decays at future e+e- lepton colliders, focusing on the Higgs decays with hadronic final states and/or missing energy, which are very challenging for the High-Luminosity program of the Large Hadron Collider (HL-LHC). We show that with simple selection cuts, (10-3-10-5) limits on the Higgs exotic decay branching fractions can be achieved using the leptonic decaying spectator Z boson in the associated production mode e+e-→ ZH. We further discuss the interplay between detector performance and Higgs exotic decays, and other possibilities of exotic decays. Our work is a first step in a comprehensive study of Higgs exotic decays at future lepton colliders, which is a key area of Higgs physics that deserves further investigation. Supported by Fermi Research Alliance, LLC (DE-AC02-07CH11359) with the U.S. Department of Energy, DOE (DE-SC0013642), IHEP(Y6515580U1), and IHEP Innovation (Y4545171Y2)
Higgs potential and hidden light Higgs scenario in two Higgs doublet models
Chang, Sanghyeon; Lee, Jong-Phil; Song, Jeonghyeon
2015-01-01
In two Higgs doublet models (2HDM), there exists an interesting possibility, the hidden light Higgs scenario, that the discovered SM-like Higgs boson is the heavier CP-even Higgs boson $H^0$ and the lighter CP-even $h^0$ has not been observed yet in any experiment. We study the current status of this scenario in Types I, II, X, and Y, through the scans of the 2HDM parameters with all relevant theoretical and experimental constraints. We employ not only the most up-to-date Higgs signal strength measurements with the feed-down effects, but also all the available LHC exclusion limits from heavy Higgs searches. Adjusting the heavier $H^0$ to the 125 GeV state while hiding the lighter $h^0$ from the LEP Higgs search prohibits the extreme decoupling limit: there exist upper bounds on the masses of the pseudoscalar $A^0$ and the charged Higgs $H^\\pm$ below about 550 GeV. In addition, the $Z_2$ symmetry, which was introduced to avoid the tree-level FCNC, is shown to be a good approximate symmetry since the soft $Z_2$...
Higgs boson mass and muon g -2 with strongly coupled vectorlike generations
Nishida, Michinobu; Yoshioka, Koichi
2016-11-01
We study the Higgs boson mass and the muon anomalous magnetic moment (the muon g -2 ) in a supersymmetric standard model with vectorlike generations. The infrared physics of the model is governed by strong renormalization-group effects of the gauge couplings. That leads to sizable extra Yukawa couplings of Higgs doublets between the second and vectorlike generations in both quark and lepton sectors. It is found with this property that there exist wide parameter regions where the Higgs boson mass and the muon g -2 are simultaneously explained.
Distinguishing a SM-like MSSM Higgs boson from SM Higgs boson at muon collider
Indian Academy of Sciences (India)
Jai Kumar Singhal; Sardar Singh; Ashok K Nagawat
2007-06-01
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 tan and 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.
The Higgs Pair Productions in The CP-violating Two-Higgs-Doublet Model
Bian, Ligong
2016-01-01
In this work, we study the SM-like Higgs pair productions in the framework of the general CP-violating two-Higgs-doublet model. Several constraints are imposed to the model sequentially, including the SM-like Higgs boson signal fits, the precise measurements of the electric dipole moments, the perturbative unitarity and stability bounds to the Higgs potential, and the most recent LHC searches for the heavy Higgs bosons. We show how are the CP-violating mixing angles related to the Higgs cubic self couplings in this setup. Afterwards, we estimate the cross sections of the future LHC/SppC searches for the Higgs pair productions, as well as other possible decay modes for the heavy Higgs bosons.
AUTHOR|(INSPIRE)INSPIRE-00392390; Saborido Silva, Juan Jose; Martinez Santos, Diego
This LHCb Thesis consists of three main parts. First, characterisation studies of Medipix3 silicon detectors using charged-particle beams in the context of the VELO upgrade: average cluster size and resolution versus threshold have been found to not change significantly between irradiated and non-irradiated assemblies, proving that Medipix3 assemblies are hard-radiation suitable for the development of Timepix3 and Velopix assemblies. Second, measurement of penguin pollution to the $CP$-violating $\\phi_s$ phase using $B_s^0{\\to}J/\\psi{\\phi}$ decays: polarisation fractions and direct CP violation have been found to be in agreement with SM predictions, while penguin pollution have been found to be small and under control. Third, a search of $A_1^0{\\to}\\mu^+\\mu^-$ decays where $A_1^0$ is the light $CP$-odd Higgs boson in the NMSSM: the analysis is not finished yet, however, it is in good shape and a sensible improvement with respect to previous estimations is expected - updates can be found in the LHCb analysis ...
Effective Physics Study Habits
Zettili, Nouredine
2011-04-01
We discuss the methods of efficient study habits and how they can be used by students to help them improve learning physics. In particular, we deal with ideas pertaining to the most effective techniques needed to help students improve their physics study skills. These ideas were developed as part of Project IMPACTSEED (IMproving Physics And Chemistry Teaching in SEcondary Education), an outreach grant funded by the Alabama Commission on Higher Education. This project is motivated by a major pressing local need: A large number of high school physics teachers teach out of field. In the presentation, focus on topics such as the skills of how to develop long term memory, how to improve concentration power, how to take class notes, how to prepare for and take exams, how to study scientific subjects such as physics. We argue that the student who conscientiously uses the methods of efficient study habits will be able to achieve higher results than the student who does not; moreover, a student equipped with the proper study skills will spend much less time to learn a subject than a student who has no good study habits. The underlying issue here is not the quantity of time allocated to the study efforts by the student, but the efficiency and quality of actions. This work is supported by the Alabama Commission on Higher Education as part of IMPACTSEED grant.
DEFF Research Database (Denmark)
Sannino, Francesco
2013-01-01
a Weyl-consistent computation. I will carefully examine the fundamental reasons why what has been discovered might not be the standard model Higgs. Dynamical electroweak breaking naturally addresses a number of the fundamental issues unsolved by the standard model interpretation. However this paradigm...
Can We Tell Students where the Higgs Boson Lies?
Chu, Z. Kwang-Hua
2010-01-01
We pedagogically introduce the search for the Higgs boson and the measurement of its properties which will be one of the primary goals of the Large Hadron Collider. Our presentation will be useful to the relevant graduate and senior undergraduate students studying physics, as well as researchers in this field. (Contains 1 figure.)
BSM Higgs searches with the ATLAS experiment
AUTHOR|(INSPIRE)INSPIRE-00172296; The ATLAS collaboration
2016-01-01
The searches for evidence of beyond the Standard Model (BSM) Higgs bosons is a crucial part of the LHC physics program. These searches are mainly driven by two approaches: directly from decays of neutral and charged Higgs bosons, indirectly by interpreting measured mass and cou- plings of light Higgs boson in extensions of the SM. This note reviews the most recent BSM Higgs boson searches performed with ATLAS at LHC using Run I and Run II proton-proton collision data. In particular, limits on new phenomena via coupling measurements, searches for charged and neutral Higgs bosons, double Higgs boson pro- duction and scalar particles decaying to γγ are presented. No significant deviations from the SM background expectations are found in any of the searches and thus the resulting exclusion limits are given.
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...
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.
Prospect Study for the Exotic Decay of the Higgs Boson to Dark Photons in the Four Muon Channel
AL-Badi, Shaymaa
2016-01-01
This report presents a prospect study for the exotic decay of the Higgs boson to four muons, via one dark photon Z_D, H→ZZ_D→4μ. This prospect study is based on a data set corresponding to an integrated luminosity of 12.8 fb^(-1) of proton-proton collisions collected by the CMS experiment during 2016 at a center-of-mass energy √s=13 TeV.
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)
Energy Technology Data Exchange (ETDEWEB)
Beckers, Mike (comp.)
2015-07-01
The following topics are dealt with: Particle accelerators of the future, expected surprises from the LHC, the reality in quantum field theory, expected LHC results in string theory, the internal structure of the quarks, supersymmetry in the crisis, the search for ultralight particles, new physics with neutrinos, the still unknown properties of the neutrinos, the proton radius, the internal structure of the neutron. (HSI)
Perspectives on Higgs Boson and Supersymmetry
Nath, Pran
2013-01-01
We review the recent discovery of the Higgs like particle at $\\sim 125$ GeV and its implications for particle physics models. Specifically the implications of the relatively high Higgs mass for the discovery of supersymmetry are discussed. Several related topics such as naturalness and supersymmetry, dark matter and unification are also discussed.
Nejad, S Mohammad Moosavi
2016-01-01
Light and heavy charged Higgs bosons are predicted by many models with an extended Higgs sector such as the two-Higgs-doublet model (2HDM). Searches for the charged Higgs bosons have been done by the ATLAS and the CMS experiments at the Large Hadron Collider (LHC) in proton-proton collision. However, a definitive search is a program that still has to be carried out so this belongs to the LHC experiments. The experimental observation of charged Higgs bosons would indicate physics beyond the Standard Model. In the present work we study the ${\\cal O}(\\alpha_s)$ correction to the energy spectrum of the inclusive bottom-flavored mesons $(X_b)$ in polarized top quark decays into a light charged Higgs boson ($m_{H^+}
Electroweak Corrections to p p →μ+μ-e+e-+X at the LHC: A Higgs Boson Background Study
Biedermann, B.; Denner, A.; Dittmaier, S.; Hofer, L.; Jäger, B.
2016-04-01
The first complete calculation of the next-to-leading-order electroweak corrections to four-lepton production at the LHC is presented, where all off-shell effects of intermediate Z bosons and photons are taken into account. Focusing on the mixed final state μ+μ-e+e-, we study differential cross sections that are particularly interesting for Higgs boson analyses. The electroweak corrections are divided into photonic and purely weak corrections. The former exhibit patterns familiar from similar W - or Z -boson production processes with very large radiative tails near resonances and kinematical shoulders. The weak corrections are of the generic size of 5% and show interesting variations, in particular, a sign change between the regions of resonant Z -pair production and the Higgs signal.
Electroweak Corrections to pp→μ^{+}μ^{-}e^{+}e^{-}+X at the LHC: A Higgs Boson Background Study.
Biedermann, B; Denner, A; Dittmaier, S; Hofer, L; Jäger, B
2016-04-22
The first complete calculation of the next-to-leading-order electroweak corrections to four-lepton production at the LHC is presented, where all off-shell effects of intermediate Z bosons and photons are taken into account. Focusing on the mixed final state μ^{+}μ^{-}e^{+}e^{-}, we study differential cross sections that are particularly interesting for Higgs boson analyses. The electroweak corrections are divided into photonic and purely weak corrections. The former exhibit patterns familiar from similar W- or Z-boson production processes with very large radiative tails near resonances and kinematical shoulders. The weak corrections are of the generic size of 5% and show interesting variations, in particular, a sign change between the regions of resonant Z-pair production and the Higgs signal.
Electroweak corrections to $pp \\to \\mu^+\\mu^-e^+e^- + X$ at the LHC -- a Higgs background study
Biedermann, B; Dittmaier, S; Hofer, L; Jäger, B
2016-01-01
The first complete calculation of the next-to-leading-order electroweak corrections to four-lepton production at the LHC is presented, where all off-shell effects of intermediate Z bosons and photons are taken into account. Focusing on the mixed final state $\\mu^+\\mu^-e^+e^-$, we study differential cross sections that are particularly interesting for Higgs-boson analyses. The electroweak corrections are divided into photonic and purely weak corrections. The former exhibit patterns familiar from similar W/Z-boson production processes with very large radiative tails near resonances and kinematical shoulders. The weak corrections are of the generic size of 5% and show interesting variations, in particular a sign change between the regions of resonant Z-pair production and the Higgs signal.
Allen, Roland E
2013-01-01
The particle recently discovered at the Large Hadron Collider near Geneva is almost certainly a Higgs boson, the long-sought completion of the Standard Model of particle physics. But this discovery, an achievement by more than six thousand scientists (including students), is actually much more than a mere capstone of the Standard Model. It instead represents a bridge from the Standard Model to exciting discoveries of the future, at higher energies or in other experiments, and to the properties of matter at very low temperatures. The mere existence of a particle with zero spin implies a need for new physics, with the most likely candidate being supersymmetry, which requires that every known particle has a superpartner yet to be discovered. And phenomena similar to the Higgs are seen in superconducting metals and superfluid gases at low temperatures, which extend down to a millionth or even a billionth of a degree Kelvin. So the discovery of a Higgs boson has a central place in our attempts both to achieve a tr...
Higgs Potential from Derivative Interactions
Quadri, A
2016-01-01
A formulation of the linear $\\sigma$ model with derivative interactions is studied. The theory is on-shell equivalent to the model with a quartic Higgs potential. The mass of the scalar mode only appears in the quadratic part and not in the interaction vertices, unlike in the ordinary formulation of the theory. Renormalization of the model is discussed. A natural non power-counting renormalizable extension of the theory is presented. The model is physically equivalent to the inclusion of a dimension six effective operator $\\partial_\\mu (\\Phi^\\dagger \\Phi) \\partial^\\mu (\\Phi^\\dagger \\Phi)$. The resulting UV divergences are arranged in a perturbation series around the power-counting renormalizable theory. UV completion of the non-power-counting renormalizable model through a symmetric deformation of the propagator of the massive physical scalar is addressed.
Higgs boson decay into four leptons at NLOPS electroweak accuracy
Boselli, Stefano; Montagna, Guido; Nicrosini, Oreste; Piccinini, Fulvio
2015-01-01
In view of precision studies of the Higgs sector at the Run II of the LHC, the improvement of the accuracy of the theoretical prediction is becoming a pressing issue. In this framework, we detail a calculation of the full Next-to-Leading Order (NLO) electroweak corrections to Higgs boson decay into four charged leptons, by considering the gold-plated channel H -> Z(*) Z(*) -> 2l 2l', l,l' = e, mu. We match the NLO corrections with a QED Parton Shower (PS), in order to simulate exclusive multiple photon emission and provide novel results at NLOPS electroweak accuracy. We compare our NLO predictions to those of the program Prophecy4f and present NLOPS phenomenological results relevant for Higgs physics studies, with particular attention to precision measurements of the Higgs boson mass, spin-parity assignment and tests of the Standard Model. Our calculation is implemented in a new code, Hto4l, which can be easily interfaced to any generator describing Higgs boson production. As an example, we provide illustrati...
Lepton flavor changing Higgs decays in the littlest Higgs model with T-parity
del Aguila, Francisco; Ametller, Lluis; Illana, Jose Ignacio; Santiago, Jose; Talavera, Pere; Vega-Morales, Roberto
2017-08-01
We calculate loop induced lepton flavor violating Higgs decays in the Littlest Higgs model with T-parity. We find that a finite amplitude is obtained only when all contributions from the T-odd lepton sector are included. This is in contrast to lepton flavor violating processes mediated by gauge bosons where the partners of the right-handed mirror leptons can be decoupled from the spectrum. These partners are necessary to cancel the divergence in the Higgs mass introduced by the mirror leptons but are otherwise unnecessary and assumed to be decoupled in previous phenomenological studies. Further-more, as we emphasize, including the partner leptons in the spectrum also introduces a new source of lepton flavor violation via their couplings to the physical pseudo-Goldstone electroweak triplet scalar. Although this extra source also affects lepton flavor changing gauge transitions, it decouples from these amplitudes in the limit of heavy mass for the partner leptons. We find that the corresponding Higgs branching ratio into taus and muons can be as large as ˜ 0.2 × 10-6 for T-odd masses of the order a few TeV, a demanding challenge even for the high luminosity LHC.
Cheung, Kingman; Lee, Jae Sik; Park, Jubin; Tseng, Po-Yan
2015-01-01
We interpret the potential observation of the 750 GeV di-photon resonance at the LHC in models, in which an $SU(2)$ isospin-singlet scalar boson mixes with the Standard Model (SM) Higgs boson through an angle $\\alpha$. Allowing the singlet scalar boson to have renormalizable couplings to vector-like leptons and quarks, we can explain the large production cross section $\\sigma(H_2) \\times B(H_2 \\to \\gamma\\gamma)$ as well as the apparent large total width of the boson without conflicts from the results obtained by previous global fits to the SM Higgs boson data.
LEP3: A High Luminosity e+e- Collider to study the Higgs Boson
Blondel, A; Assmann, R W; Butterworth, A; Janot, P; Jimenez, J M; Grojean, C; Milanese, A; Modena, M; Osborne, J A; Zimmermann, F; Piekarz, H; Oide, K; Yokoya, K; Ellis, J; Klute, M; Zanetti, M; Velasco, M; Telnov, V; Rivkin, L; Murray, B; Cai, Y
2012-01-01
The LHC experiments discovered a new particle of mass around 125 GeV, candidate for the scalar Higgs boson of the Standard Model. An e+e- collider operating close to the ZH threshold could be the tool of choice for studying this unique particle in detail. We present here the concept of a storage ring collider, which we call LEP3. Preliminary studies show that at a centre-of-mass energy of 240 GeV, near-constant luminosities of 10^34 cm^{-2}s^{-1} are possible in up to four collision points, while respecting a number of constraints including beamstrahlung. The integrated luminosity is 100fb^{-1}/y per interaction point, 20,000 e+e- --> ZH events would be produced per year and per experiment. LEP3 could also operate in multi-bunch mode at the Z resonance, with luminosities of several\\times10^35 cm^{-2}s^{-1}, yielding O(10^11) Z decays per year, as well as just above the WW threshold. The short luminosity lifetime requires the use of top-up injection, which, in turn calls for a full-energy injector. The present...
LEP3: A High Luminosity e+e- Collider to Study the Higgs Boson
Blondel, A U; Assmann, R W; Butterworth, A; Janot, P; Jimenez, J M; Grojean, C; Milanese, A; Modena, M; Osborne, J A; Zimmermann, F; Piekarz, H; Oide, K; Yokoya, K; Ellis, J; Klute, M; Zanetti, M; Velasco, M; Telnov, V; Rivkin, L; Cai, Y
2012-01-01
The LHC experiments have discovered a new particle with a mass around 125 GeV that is a strong candidate for the scalar Higgs boson expected in the Standard Model. An e+e− collider operating close to the ZH threshold (at a centre-of-mass energy of 240 GeV) could be the tool of choice for studying this unique particle in detail. We present here the concept of a storage ring collider, which we call LEP3. Preliminary studies show that at a centre-of-mass energy of 240 GeV, near-constant luminosities of 1034 cm-2s-1 are possible in up to four collision points, while respecting a number of constraints including beamstrahlung limits. With an integrated luminosity of 100fb-1 per year and per interaction point, 20,000 e+e- - ZH events would be produced per year and per experiment. LEP3 could also operate in multi-bunch mode at the Z resonance, with luminosities of several×1035cm-2s-1, yielding O(1011) Z decays per year, as well as just above the WW threshold, potentially improving our knowledge of W and Z propert...
Batell, Brian; McKeen, David; Pospelov, Maxim; Ritz, Adam
2016-01-01
An extended Higgs sector may allow for new scalar particles well below the weak scale. In this work, we present a detailed study of a light scalar $S$ with enhanced coupling to leptons, which could be responsible for the existing discrepancy between experimental and theoretical determinations of the muon anomalous magnetic moment. We present an ultraviolet completion of this model in terms of the lepton-specific two-Higgs doublet model and an additional scalar singlet. We then analyze a plethora of experimental constraints on the universal low energy model, and this UV completion, along with the sensitivity reach at future experiments. The most relevant constraints originate from muon and kaon decays, electron beam dump experiments, electroweak precision observables, rare $B_d$ and $B_s$ decays and Higgs branching fractions. The properties of the leptonic Higgs portal imply an enhanced couplings to heavy leptons, and we identify the most promising search mode for the high-luminosity electron-positron collider...
Universality test of the charged Higgs boson couplings at the LHC and at B factories
Cornell, Alan S.; Deandrea, Aldo; Gaur, Naveen; Itoh, Hideo; Klasen, Michael; Okada, Yasuhiro
2010-06-01
Many extensions of the standard model of particle physics predict the existence of charged Higgs bosons with substantial couplings to standard model particles, which would render them observable both directly at the LHC and indirectly at B-factories. For example, the charged Higgs boson couplings to fermions in two Higgs doublet models of type II are proportional to the ratio of the two Higgs doublet vacuum expectation values (tanβ) and fermionic mass factors and could thus be substantial at large tanβ and/or for heavy fermions. In this work we perform a model-independent study of the charged Higgs boson couplings at the LHC and at B-factories for large values of tanβ. We have shown that at high luminosity it is possible to measure the couplings of a charged Higgs boson to the third generation of quarks up to an accuracy of 10%. We further argue that by combining the possible measurements of the LHC and the B-factories, it is possible to perform a universality test of charged Higgs boson couplings to quarks.
Study of the Standard Model Higgs boson decaying to taus at CMS
Botta, Valeria
2017-01-01
The most recent search for the Standard Model Higgs boson decaying to a pair of $\\tau$ leptons is performed using proton-proton collision events at a centre-of-mass energy of 13~TeV, recorded by the CMS experiment at the LHC. The full 2016 dataset, corresponding to an integrated luminosity of 35.9~fb$^{-1}$, has been analysed. The Higgs boson signal in the $\\tau^{+}\\tau^{-}$ decay mode is observed with a significance of 4.9 standard deviations, to be compared to an expected significance of 4.7 standard deviations. This measurement is the first observation of the Higgs boson decay into fermions by a single experiment.
Study of the spin and parity of the Higgs boson in diboson decays with the ATLAS detector
Energy Technology Data Exchange (ETDEWEB)
Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Adelman, J.; Adomeit, S.; Adye, T.; Affolder, A. A.; Agatonovic-Jovin, T.; Agricola, J.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akerstedt, H.; Åkesson, T. P. A.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albrand, S.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Alimonti, G.; Alio, L.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Altheimer, A.; Alvarez Gonzalez, B.; Álvarez Piqueras, D.; Alviggi, M. G.; Amadio, B. T.; Amako, K.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amram, N.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anders, J. 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K.; Bulekov, O.; Bullock, D.; Burckhart, H.; Burdin, S.; Burghgrave, B.; Burke, S.; Burmeister, I.; Busato, E.; Büscher, D.; Büscher, V.; Bussey, P.; Butler, J. M.; Butt, A. I.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Buzykaev, A. R.; Cabrera Urbán, S.; Caforio, D.; Cairo, V. M.; Cakir, O.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Caloba, L. P.; Calvet, D.; Calvet, S.; Camacho Toro, R.; Camarda, S.; Camarri, P.; Cameron, D.; Caminal Armadans, R.; Campana, S.; Campanelli, M.; Campoverde, A.; Canale, V.; Canepa, A.; Cano Bret, M.; Cantero, J.; Cantrill, R.; Cao, T.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Caputo, R.; Cardarelli, R.; Cardillo, F.; Carli, T.; Carlino, G.; Carminati, L.; Caron, S.; Carquin, E.; Carrillo-Montoya, G. D.; Carter, J. R.; Carvalho, J.; Casadei, D.; Casado, M. P.; Casolino, M.; Castaneda-Miranda, E.; Castelli, A.; Castillo Gimenez, V.; Castro, N. F.; Catastini, P.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Caudron, J.; Cavaliere, V.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Ceradini, F.; Cerio, B. C.; Cerny, K.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cerv, M.; Cervelli, A.; Cetin, S. A.; Chafaq, A.; Chakraborty, D.; Chalupkova, I.; Chang, P.; Chapman, J. D.; Charlton, D. G.; Chau, C. C.; Chavez Barajas, C. A.; Cheatham, S.; Chegwidden, A.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, K.; Chen, L.; Chen, S.; Chen, X.; Chen, Y.; Cheng, H. C.; Cheng, Y.; Cheplakov, A.; Cheremushkina, E.; Cherkaoui El Moursli, R.; Chernyatin, V.; Cheu, E.; Chevalier, L.; Chiarella, V.; Childers, J. T.; Chiodini, G.; Chisholm, A. S.; Chislett, R. T.; Chitan, A.; Chizhov, M. V.; Choi, K.; Chouridou, S.; Chow, B. K. B.; Christodoulou, V.; Chromek-Burckhart, D.; Chudoba, J.; Chuinard, A. J.; Chwastowski, J. J.; Chytka, L.; Ciapetti, G.; Ciftci, A. K.; Cinca, D.; Cindro, V.; Cioara, I. A.; Ciocio, A.; Cirotto, F.; Citron, Z. H.; Ciubancan, M.; Clark, A.; Clark, B. L.; Clark, P. J.; Clarke, R. N.; Cleland, W.; Clement, C.; Coadou, Y.; Cobal, M.; Coccaro, A.; Cochran, J.; Coffey, L.; Cogan, J. G.; Cole, B.; Cole, S.; Colijn, A. P.; Collot, J.; Colombo, T.; Compostella, G.; Conde Muiño, P.; Coniavitis, E.; Connell, S. H.; Connelly, I. A.; Consonni, S. M.; Consorti, V.; Constantinescu, S.; Conta, C.; Conti, G.; Conventi, F.; Cooke, M.; Cooper, B. D.; Cooper-Sarkar, A. M.; Cornelissen, T.; Corradi, M.; Corriveau, F.; Corso-Radu, A.; Cortes-Gonzalez, A.; Cortiana, G.; Costa, G.; Costa, M. J.; Costanzo, D.; Côté, D.; Cottin, G.; Cowan, G.; Cox, B. E.; Cranmer, K.; Cree, G.; Crépé-Renaudin, S.; Crescioli, F.; Cribbs, W. A.; Crispin Ortuzar, M.; Cristinziani, M.; Croft, V.; Crosetti, G.; Cuhadar Donszelmann, T.; Cummings, J.; Curatolo, M.; Cuthbert, C.; Czirr, H.; Czodrowski, P.; D’Auria, S.; D’Onofrio, M.; Da Cunha Sargedas De Sousa, M. J.; Da Via, C.; Dabrowski, W.; Dafinca, A.; Dai, T.; Dale, O.; Dallaire, F.; Dallapiccola, C.; Dam, M.; Dandoy, J. R.; Dang, N. P.; Daniells, A. C.; Danninger, M.; Dano Hoffmann, M.; Dao, V.; Darbo, G.; Darmora, S.; Dassoulas, J.; Dattagupta, A.; Davey, W.; David, C.; Davidek, T.; Davies, E.; Davies, M.; Davison, P.; Davygora, Y.; Dawe, E.; Dawson, I.; Daya-Ishmukhametova, R. K.; De, K.; de Asmundis, R.; De Castro, S.; De Cecco, S.; De Groot, N.; de Jong, P.; De la Torre, H.; De Lorenzi, F.; De Nooij, L.; De Pedis, D.; De Salvo, A.; De Sanctis, U.; De Santo, A.; De Vivie De Regie, J. B.; Dearnaley, W. J.; Debbe, R.; Debenedetti, C.; Dedovich, D. V.; Deigaard, I.; Del Peso, J.; Del Prete, T.; Delgove, D.; Deliot, F.; Delitzsch, C. M.; Deliyergiyev, M.; Dell’Acqua, A.; Dell’Asta, L.; Dell’Orso, M.; Della Pietra, M.; della Volpe, D.; Delmastro, M.; Delsart, P. A.; Deluca, C.; DeMarco, D. A.; Demers, S.; Demichev, M.; Demilly, A.; Denisov, S. P.; Derendarz, D.; Derkaoui, J. E.; Derue, F.; Dervan, P.; Desch, K.; Deterre, C.; Deviveiros, P. O.; Dewhurst, A.; Dhaliwal, S.; Di Ciaccio, A.; Di Ciaccio, L.; Di Domenico, A.; Di Donato, C.; Di Girolamo, A.; Di Girolamo, B.; Di Mattia, A.; Di Micco, B.; Di Nardo, R.; Di Simone, A.; Di Sipio, R.; Di Valentino, D.; Diaconu, C.; Diamond, M.; Dias, F. A.; Diaz, M. A.; Diehl, E. B.; Dietrich, J.; Diglio, S.; Dimitrievska, A.; Dingfelder, J.; Dita, P.; Dita, S.; Dittus, F.; Djama, F.; Djobava, T.; Djuvsland, J. I.; do Vale, M. A. B.; Dobos, D.; Dobre, M.; Doglioni, C.; Dohmae, T.; Dolejsi, J.; Dolezal, Z.; Dolgoshein, B. A.; Donadelli, M.; Donati, S.; Dondero, P.; Donini, J.; Dopke, J.; Doria, A.; Dova, M. T.; Doyle, A. T.; Drechsler, E.; Dris, M.; Dubreuil, E.; Duchovni, E.; Duckeck, G.; Ducu, O. A.; Duda, D.; Dudarev, A.; Duflot, L.; Duguid, L.; Dührssen, M.; Dunford, M.; Duran Yildiz, H.; Düren, M.; Durglishvili, A.; Duschinger, D.; Dyndal, M.; Eckardt, C.; Ecker, K. M.; Edgar, R. C.; Edson, W.; Edwards, N. 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E.; Ferrer, A.; Ferrere, D.; Ferretti, C.; Ferretto Parodi, A.; Fiascaris, M.; Fiedler, F.; Filipčič, A.; Filipuzzi, M.; Filthaut, F.; Fincke-Keeler, M.; Finelli, K. D.; Fiolhais, M. C. N.; Fiorini, L.; Firan, A.; Fischer, A.; Fischer, C.; Fischer, J.; Fisher, W. C.; Fitzgerald, E. A.; Flaschel, N.; Fleck, I.; Fleischmann, P.; Fleischmann, S.; Fletcher, G. T.; Fletcher, G.; Fletcher, R. R. M.; Flick, T.; Floderus, A.; Flores Castillo, L. R.; Flowerdew, M. J.; Formica, A.; Forti, A.; Fournier, D.; Fox, H.; Fracchia, S.; Francavilla, P.; Franchini, M.; Francis, D.; Franconi, L.; Franklin, M.; Frate, M.; Fraternali, M.; Freeborn, D.; French, S. T.; Friedrich, F.; Froidevaux, D.; Frost, J. A.; Fukunaga, C.; Fullana Torregrosa, E.; Fulsom, B. G.; Fuster, J.; Gabaldon, C.; Gabizon, O.; Gabrielli, A.; Gabrielli, A.; Gadatsch, S.; Gadomski, S.; Gagliardi, G.; Gagnon, P.; Galea, C.; Galhardo, B.; Gallas, E. J.; Gallop, B. J.; Gallus, P.; Galster, G.; Gan, K. K.; Gao, J.; Gao, Y.; Gao, Y. 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J.; Oren, Y.; Orestano, D.; Orlando, N.; Oropeza Barrera, C.; Orr, R. S.; Osculati, B.; Ospanov, R.; Otero y Garzon, G.; Otono, H.; Ouchrif, M.; Ouellette, E. A.; Ould-Saada, F.; Ouraou, A.; Oussoren, K. P.; Ouyang, Q.; Ovcharova, A.; Owen, M.; Owen, R. E.; Ozcan, V. E.; Ozturk, N.; Pachal, K.; Pacheco Pages, A.; Padilla Aranda, C.; Pagáčová, M.; Pagan Griso, S.; Paganis, E.; Paige, F.; Pais, P.; Pajchel, K.; Palacino, G.; Palestini, S.; Palka, M.; Pallin, D.; Palma, A.; Pan, Y. B.; Panagiotopoulou, E.; Pandini, C. E.; Panduro Vazquez, J. G.; Pani, P.; Panitkin, S.; Pantea, D.; Paolozzi, L.; Papadopoulou, Th. D.; Papageorgiou, K.; Paramonov, A.; Paredes Hernandez, D.; Parker, M. A.; Parker, K. A.; Parodi, F.; Parsons, J. A.; Parzefall, U.; Pasqualucci, E.; Passaggio, S.; Pastore, F.; Pastore, Fr.; Pásztor, G.; Pataraia, S.; Patel, N. D.; Pater, J. R.; Pauly, T.; Pearce, J.; Pearson, B.; Pedersen, L. E.; Pedersen, M.; Pedraza Lopez, S.; Pedro, R.; Peleganchuk, S. V.; Pelikan, D.; Penc, O.; Peng, C.; Peng, H.; Penning, B.; Penwell, J.; Perepelitsa, D. V.; Perez Codina, E.; Pérez García-Estañ, M. T.; Perini, L.; Pernegger, H.; Perrella, S.; Peschke, R.; Peshekhonov, V. D.; Peters, K.; Peters, R. F. Y.; Petersen, B. A.; Petersen, T. C.; Petit, E.; Petridis, A.; Petridou, C.; Petrolo, E.; Petrucci, F.; Pettersson, N. E.; Pezoa, R.; Phillips, P. W.; Piacquadio, G.; Pianori, E.; Picazio, A.; Piccaro, E.; Piccinini, M.; Pickering, M. A.; Piegaia, R.; Pignotti, D. T.; Pilcher, J. E.; Pilkington, A. D.; Pina, J.; Pinamonti, M.; Pinfold, J. L.; Pingel, A.; Pinto, B.; Pires, S.; Pirumov, H.; Pitt, M.; Pizio, C.; Plazak, L.; Pleier, M. -A.; Pleskot, V.; Plotnikova, E.; Plucinski, P.; Pluth, D.; Poettgen, R.; Poggioli, L.; Pohl, D.; Polesello, G.; Poley, A.; Policicchio, A.; Polifka, R.; Polini, A.; Pollard, C. S.; Polychronakos, V.; Pommès, K.; Pontecorvo, L.; Pope, B. G.; Popeneciu, G. A.; Popovic, D. S.; Poppleton, A.; Pospisil, S.; Potamianos, K.; Potrap, I. N.; Potter, C. J.; Potter, C. T.; Poulard, G.; Poveda, J.; Pozdnyakov, V.; Pralavorio, P.; Pranko, A.; Prasad, S.; Prell, S.; Price, D.; Price, L. E.; Primavera, M.; Prince, S.; Proissl, M.; Prokofiev, K.; Prokoshin, F.; Protopapadaki, E.; Protopopescu, S.; Proudfoot, J.; Przybycien, M.; Ptacek, E.; Puddu, D.; Pueschel, E.; Puldon, D.; Purohit, M.; Puzo, P.; Qian, J.; Qin, G.; Qin, Y.; Quadt, A.; Quarrie, D. R.; Quayle, W. B.; Queitsch-Maitland, M.; Quilty, D.; Raddum, S.; Radeka, V.; Radescu, V.; Radhakrishnan, S. K.; Radloff, P.; Rados, P.; Ragusa, F.; Rahal, G.; Rajagopalan, S.; Rammensee, M.; Rangel-Smith, C.; Rauscher, F.; Rave, S.; Ravenscroft, T.; Raymond, M.; Read, A. L.; Readioff, N. P.; Rebuzzi, D. M.; Redelbach, A.; Redlinger, G.; Reece, R.; Reeves, K.; Rehnisch, L.; Reisin, H.; Relich, M.; Rembser, C.; Ren, H.; Renaud, A.; Rescigno, M.; Resconi, S.; Rezanova, O. L.; Reznicek, P.; Rezvani, R.; Richter, R.; Richter, S.; Richter-Was, E.; Ricken, O.; Ridel, M.; Rieck, P.; Riegel, C. J.; Rieger, J.; Rijssenbeek, M.; Rimoldi, A.; Rinaldi, L.; Ristić, B.; Ritsch, E.; Riu, I.; Rizatdinova, F.; Rizvi, E.; Robertson, S. H.; Robichaud-Veronneau, A.; Robinson, D.; Robinson, J. E. M.; Robson, A.; Roda, C.; Roe, S.; Røhne, O.; Rolli, S.; Romaniouk, A.; Romano, M.; Romano Saez, S. M.; Romero Adam, E.; Rompotis, N.; Ronzani, M.; Roos, L.; Ros, E.; Rosati, S.; Rosbach, K.; Rose, P.; Rosendahl, P. L.; Rosenthal, O.; Rossetti, V.; Rossi, E.; Rossi, L. P.; Rosten, R.; Rotaru, M.; Roth, I.; Rothberg, J.; Rousseau, D.; Royon, C. R.; Rozanov, A.; Rozen, Y.; Ruan, X.; Rubbo, F.; Rubinskiy, I.; Rud, V. I.; Rudolph, C.; Rudolph, M. S.; Rühr, F.; Ruiz-Martinez, A.; Rurikova, Z.; Rusakovich, N. A.; Ruschke, A.; Russell, H. L.; Rutherfoord, J. P.; Ruthmann, N.; Ryabov, Y. F.; Rybar, M.; Rybkin, G.; Ryder, N. C.; Saavedra, A. F.; Sabato, G.; Sacerdoti, S.; Saddique, A.; Sadrozinski, H. F-W.; Sadykov, R.; Safai Tehrani, F.; Saimpert, M.; Sakamoto, H.; Sakurai, Y.; Salamanna, G.; Salamon, A.; Saleem, M.; Salek, D.; Sales De Bruin, P. H.; Salihagic, D.; Salnikov, A.; Salt, J.; Salvatore, D.; Salvatore, F.; Salvucci, A.; Salzburger, A.; Sampsonidis, D.; Sanchez, A.; Sánchez, J.; Sanchez Martinez, V.; Sandaker, H.; Sandbach, R. L.; Sander, H. G.; Sanders, M. P.; Sandhoff, M.; Sandoval, C.; Sandstroem, R.; Sankey, D. P. C.; Sannino, M.; Sansoni, A.; Santoni, C.; Santonico, R.; Santos, H.; Santoyo Castillo, I.; Sapp, K.; Sapronov, A.; Saraiva, J. G.; Sarrazin, B.; Sasaki, O.; Sasaki, Y.; Sato, K.; Sauvage, G.; Sauvan, E.; Savage, G.; Savard, P.; Sawyer, C.; Sawyer, L.; Saxon, J.; Sbarra, C.; Sbrizzi, A.; Scanlon, T.; Scannicchio, D. A.; Scarcella, M.; Scarfone, V.; Schaarschmidt, J.; Schacht, P.; Schaefer, D.; Schaefer, R.; Schaeffer, J.; Schaepe, S.; Schaetzel, S.; Schäfer, U.; Schaffer, A. C.; Schaile, D.; Schamberger, R. D.; Scharf, V.; Schegelsky, V. A.; Scheirich, D.; Schernau, M.; Schiavi, C.; Schillo, C.; Schioppa, M.; Schlenker, S.; Schmidt, E.; Schmieden, K.; Schmitt, C.; Schmitt, S.; Schmitt, S.; Schneider, B.; Schnellbach, Y. J.; Schnoor, U.; Schoeffel, L.; Schoening, A.; Schoenrock, B. D.; Schopf, E.; Schorlemmer, A. L. S.; Schott, M.; Schouten, D.; Schovancova, J.; Schramm, S.; Schreyer, M.; Schroeder, C.; Schuh, N.; Schultens, M. J.; Schultz-Coulon, H. -C.; Schulz, H.; Schumacher, M.; Schumm, B. A.; Schune, Ph.; Schwanenberger, C.; Schwartzman, A.; Schwarz, T. A.; Schwegler, Ph.; Schweiger, H.; Schwemling, Ph.; Schwienhorst, R.; Schwindling, J.; Schwindt, T.; Sciacca, F. G.; Scifo, E.; Sciolla, G.; Scuri, F.; Scutti, F.; Searcy, J.; Sedov, G.; Sedykh, E.; Seema, P.; Seidel, S. C.; Seiden, A.; Seifert, F.; Seixas, J. M.; Sekhniaidze, G.; Sekhon, K.; Sekula, S. J.; Seliverstov, D. M.; Semprini-Cesari, N.; Serfon, C.; Serin, L.; Serkin, L.; Serre, T.; Sessa, M.; Seuster, R.; Severini, H.; Sfiligoj, T.; Sforza, F.; Sfyrla, A.; Shabalina, E.; Shamim, M.; Shan, L. Y.; Shang, R.; Shank, J. T.; Shapiro, M.; Shatalov, P. B.; Shaw, K.; Shaw, S. M.; Shcherbakova, A.; Shehu, C. Y.; Sherwood, P.; Shi, L.; Shimizu, S.; Shimmin, C. O.; Shimojima, M.; Shiyakova, M.; Shmeleva, A.; Shoaleh Saadi, D.; Shochet, M. J.; Shojaii, S.; Shrestha, S.; Shulga, E.; Shupe, M. A.; Shushkevich, S.; Sicho, P.; Sidebo, P. E.; Sidiropoulou, O.; Sidorov, D.; Sidoti, A.; Siegert, F.; Sijacki, Dj.; Silva, J.; Silver, Y.; Silverstein, S. B.; Simak, V.; Simard, O.; Simic, Lj.; Simion, S.; Simioni, E.; Simmons, B.; Simon, D.; Simoniello, R.; Sinervo, P.; Sinev, N. B.; Sioli, M.; Siragusa, G.; Sisakyan, A. N.; Sivoklokov, S. Yu.; Sjölin, J.; Sjursen, T. B.; Skinner, M. B.; Skottowe, H. P.; Skubic, P.; Slater, M.; Slavicek, T.; Slawinska, M.; Sliwa, K.; Smakhtin, V.; Smart, B. H.; Smestad, L.; Smirnov, S. Yu.; Smirnov, Y.; Smirnova, L. N.; Smirnova, O.; Smith, M. N. K.; Smith, R. W.; Smizanska, M.; Smolek, K.; Snesarev, A. A.; Snidero, G.; Snyder, S.; Sobie, R.; Socher, F.; Soffer, A.; Soh, D. A.; Solans, C. A.; Solar, M.; Solc, J.; Soldatov, E. Yu.; Soldevila, U.; Solodkov, A. A.; Soloshenko, A.; Solovyanov, O. V.; Solovyev, V.; Sommer, P.; Song, H. Y.; Soni, N.; Sood, A.; Sopczak, A.; Sopko, B.; Sopko, V.; Sorin, V.; Sosa, D.; Sosebee, M.; Sotiropoulou, C. L.; Soualah, R.; Soukharev, A. M.; South, D.; Sowden, B. C.; Spagnolo, S.; Spalla, M.; Spanò, F.; Spearman, W. R.; Sperlich, D.; Spettel, F.; Spighi, R.; Spigo, G.; Spiller, L. A.; Spousta, M.; Spreitzer, T.; St. Denis, R. D.; Staerz, S.; Stahlman, J.; Stamen, R.; Stamm, S.; Stanecka, E.; Stanescu, C.; Stanescu-Bellu, M.; Stanitzki, M. M.; Stapnes, S.; Starchenko, E. A.; Stark, J.; Staroba, P.; Starovoitov, P.; Staszewski, R.; Stavina, P.; Steinberg, P.; Stelzer, B.; Stelzer, H. J.; Stelzer-Chilton, O.; Stenzel, H.; Stewart, G. A.; Stillings, J. A.; Stockton, M. C.; Stoebe, M.; Stoicea, G.; Stolte, P.; Stonjek, S.; Stradling, A. R.; Straessner, A.; Stramaglia, M. E.; Strandberg, J.; Strandberg, S.; Strandlie, A.; Strauss, E.; Strauss, M.; Strizenec, P.; Ströhmer, R.; Strom, D. M.; Stroynowski, R.; Strubig, A.; Stucci, S. A.; Stugu, B.; Styles, N. A.; Su, D.; Su, J.; Subramaniam, R.; Succurro, A.; Sugaya, Y.; Suhr, C.; Suk, M.; Sulin, V. V.; Sultansoy, S.; Sumida, T.; Sun, S.; Sun, X.; Sundermann, J. E.; Suruliz, K.; Susinno, G.; Sutton, M. R.; Suzuki, S.; Svatos, M.; Swedish, S.; Swiatlowski, M.; Sykora, I.; Sykora, T.; Ta, D.; Taccini, C.; Tackmann, K.; Taenzer, J.; Taffard, A.; Tafirout, R.; Taiblum, N.; Takai, H.; Takashima, R.; Takeda, H.; Takeshita, T.; Takubo, Y.; Talby, M.; Talyshev, A. A.; Tam, J. Y. C.; Tan, K. G.; Tanaka, J.; Tanaka, R.; Tanaka, S.; Tannenwald, B. B.; Tannoury, N.; Tapprogge, S.; Tarem, S.; Tarrade, F.; Tartarelli, G. F.; Tas, P.; Tasevsky, M.; Tashiro, T.; Tassi, E.; Tavares Delgado, A.; Tayalati, Y.; Taylor, F. E.; Taylor, G. N.; Taylor, W.; Teischinger, F. A.; Teixeira Dias Castanheira, M.; Teixeira-Dias, P.; Temming, K. K.; Ten Kate, H.; Teng, P. K.; Teoh, J. J.; Tepel, F.; Terada, S.; Terashi, K.; Terron, J.; Terzo, S.; Testa, M.; Teuscher, R. J.; Theveneaux-Pelzer, T.; Thomas, J. P.; Thomas-Wilsker, J.; Thompson, E. N.; Thompson, P. D.; Thompson, R. J.; Thompson, A. S.; Thomsen, L. A.; Thomson, E.; Thomson, M.; Thun, R. P.; Tibbetts, M. J.; Ticse Torres, R. E.; Tikhomirov, V. O.; Tikhonov, Yu. A.; Timoshenko, S.; Tiouchichine, E.; Tipton, P.; Tisserant, S.; Todome, K.; Todorov, T.; Todorova-Nova, S.; Tojo, J.; Tokár, S.; Tokushuku, K.; Tollefson, K.; Tolley, E.; Tomlinson, L.; Tomoto, M.; Tompkins, L.; Toms, K.; Torrence, E.; Torres, H.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Trefzger, T.; Tremblet, L.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Tripiana, M. F.; Trischuk, W.; Trocmé, B.; Troncon, C.; Trottier-McDonald, M.; Trovatelli, M.; True, P.; Truong, L.; Trzebinski, M.; Trzupek, A.; Tsarouchas, C.; Tseng, J. C-L.; Tsiareshka, P. V.; Tsionou, D.; Tsipolitis, G.; Tsirintanis, N.; Tsiskaridze, S.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsukerman, I. I.; Tsulaia, V.; Tsuno, S.; Tsybychev, D.; Tudorache, A.; Tudorache, V.; Tuna, A. N.; Tupputi, S. A.; Turchikhin, S.; Turecek, D.; Turra, R.; Turvey, A. J.; Tuts, P. M.; Tykhonov, A.; Tylmad, M.; Tyndel, M.; Ueda, I.; Ueno, R.; Ughetto, M.; Ugland, M.; Uhlenbrock, M.; Ukegawa, F.; Unal, G.; Undrus, A.; Unel, G.; Ungaro, F. C.; Unno, Y.; Unverdorben, C.; Urban, J.; Urquijo, P.; Urrejola, P.; Usai, G.; Usanova, A.; Vacavant, L.; Vacek, V.; Vachon, B.; Valderanis, C.; Valencic, N.; Valentinetti, S.; Valero, A.; Valery, L.; Valkar, S.; Valladolid Gallego, E.; Vallecorsa, S.; Valls Ferrer, J. A.; Van Den Wollenberg, W.; Van Der Deijl, P. C.; van der Geer, R.; van der Graaf, H.; Van Der Leeuw, R.; van Eldik, N.; van Gemmeren, P.; Van Nieuwkoop, J.; van Vulpen, I.; van Woerden, M. C.; Vanadia, M.; Vandelli, W.; Vanguri, R.; Vaniachine, A.; Vannucci, F.; Vardanyan, G.; Vari, R.; Varnes, E. W.; Varol, T.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vazeille, F.; Vazquez Schroeder, T.; Veatch, J.; Veloce, L. M.; Veloso, F.; Velz, T.; Veneziano, S.; Ventura, A.; Ventura, D.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vest, A.; Vetterli, M. C.; Viazlo, O.; Vichou, I.; Vickey, T.; Vickey Boeriu, O. E.; Viehhauser, G. H. A.; Viel, S.; Vigne, R.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vivarelli, I.; Vives Vaque, F.; Vlachos, S.; Vladoiu, D.; Vlasak, M.; Vogel, M.; Vokac, P.; Volpi, G.; Volpi, M.; von der Schmitt, H.; von Radziewski, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Vykydal, Z.; Wagner, P.; Wagner, W.; Wahlberg, H.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, K.; Wang, R.; Wang, S. M.; Wang, T.; Wang, T.; Wang, X.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Warsinsky, M.; Washbrook, A.; Wasicki, C.; Watkins, P. M.; Watson, A. T.; Watson, I. J.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, S.; Weber, M. S.; Weber, S. W.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, P.; Wessels, M.; Wetter, J.; Whalen, K.; Wharton, A. M.; White, A.; White, M. J.; White, R.; White, S.; Whiteson, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wienemann, P.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, A.; Wilson, J. A.; Wingerter-Seez, I.; Winklmeier, F.; Winter, B. T.; Wittgen, M.; Wittkowski, J.; Wollstadt, S. J.; Wolter, M. W.; Wolters, H.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wozniak, K. W.; Wu, M.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xu, D.; Xu, L.; Yabsley, B.; Yacoob, S.; Yakabe, R.; Yamada, M.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yao, W-M.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yen, A. L.; Yildirim, E.; Yorita, K.; Yoshida, R.; Yoshihara, K.; Young, C.; Young, C. J. S.; Youssef, S.; Yu, D. R.; Yu, J.; Yu, J. M.; Yu, J.; Yuan, L.; Yurkewicz, A.; Yusuff, I.; Zabinski, B.; Zaidan, R.; Zaitsev, A. M.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanello, L.; Zanzi, D.; Zeitnitz, C.; Zeman, M.; Zemla, A.; Zengel, K.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, F.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, R.; Zhang, X.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhong, J.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, L.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; zur Nedden, M.; Zurzolo, G.; Zwalinski, L.
2015-10-06
Studies of the spin, parity and tensor couplings of the Higgs boson in the H→ZZ*→4ℓ, H→WW*→eνμν and H→γγ decay processes at the LHC are presented. The investigations are based on 25fb^{-1} of pp collision data collected by the ATLAS experiment at √s=7 TeV and √s=8 TeV. The Standard Model (SM) Higgs boson hypothesis, corresponding to the quantum numbers J^{P}=0^{+}, is tested against several alternative spin scenarios, including non-SM spin-0 and spin-2 models with universal and non-universal couplings to fermions and vector bosons. All tested alternative models are excluded in favour of the SM Higgs boson hypothesis at more than 99.9 % confidence level. Using the H→ZZ*→4ℓ and H→WW*→eνμν decays, the tensor structure of the interaction between the spin-0 boson and the SM vector bosons is also investigated. The observed distributions of variables sensitive to the non-SM tensor couplings are compatible with the SM predictions and constraints on the non-SM couplings are derived.
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.
Study of MSSM heavy Higgs bosons decaying into charginos and neutralinos
Barman, Rahool K; Chakraborty, Amit; Choudhury, Arghya
2016-01-01
A multitude of searches have already been performed by the ATLAS and CMS collaborations at the LHC to probe the heavy Higgses of the Minimal Supersymmetric Standard Model (MSSM) through their decay to the Standard Model particles. In this paper, we study the decay of the MSSM heavy Higgses into neutralino and chargino pairs and estimate the maximum possible branching ratios for these `ino' modes being consistent with the present LHC data. After performing a random scan of the relevant electroweakino parameters, we impose the SM 125 GeV Higgs constraints, low energy flavour data as well as current bounds on heavy Higgses from the LHC run-I and run-II data. The present limits on the electroweakino masses and couplings are also considered in our analysis. We choose a few representative benchmark points satisfying all the above-mentioned constraints, and then perform a detailed collider simulation, including fast detector effects, and analyze all the potential SM backgrounds in order to estimate the discovery rea...
Tau Lepton Identification and Studies of Associated Higgs Boson Production with the ATLAS Detector
DEFF Research Database (Denmark)
Pingel, Almut Maria
production via a top quark-loop (gg fusion) as well as via vector boson fusion (VBF) has been observed, but no evidence for the production in association with a vector boson (VH) has been claimed yet. The thesis presents a study of this production mode, with a leptonically decaying Z boson in the final state......In this thesis two main topics are presented: the identification of hadronic tau decays and a search for Higgs bosons that decay to tau leptons and are produced in association with a Z boson. In 2012, the ATLAS detector at the LHC recorded 20 fb1 of data at a centre-of-mass energy of 8...... the fake factor method. Combining the result from the four final states τhad τhad, τeτhad, τµτhad and τeτµ, a limit is set on the cross section of the process Z(→ ee; µµ)H(→ τhadτhad). No deviation from the Standard Model is found. An upper observed (expected) limit of 8.96 (6.18 +8:94 -4.45) times the SM...
Alternatives to an Elementary Higgs
Csaki, Csaba; Terning, John
2015-01-01
We review strongly coupled and extra dimensional models of electroweak symmetry breaking. Models examined include warped extra dimensions, bulk Higgs, "little" Higgs, dilaton Higgs, composite Higgs, twin Higgs, quantum critical Higgs, and "fat" SUSY Higgs. We also discuss current bounds and future LHC searches for this class of models.
Bounds on Unparticles from the Higgs Sector
Energy Technology Data Exchange (ETDEWEB)
Fox, Patrick J.; Rajaraman, Arvind; Shirman, Yuri
2007-05-20
We study supersymmetric QCD in the conformal window as a laboratory for unparticle physics, and analyze couplings between the unparticle sector and the Higgs sector. These couplings can lead to the unparticle sector being pushed away from its scale invariant fixed point. We show that this implies that low energy experiments will not be able to see unparticle physics, and the best hope of seeing unparticles is in high energy collider experiments such as the Tevatron and the LHC. We also demonstrate how the breaking of scale invariance could be observed at these experiments.
Chen, Zhenxing; Ruan, Manqi; Wang, Dayong; Li, Gang; Jin, Shan; Ban, Yong
2016-01-01
The Circular Electron Positron Collider (CEPC) is a future Higgs factory proposed by the Chinese high energy physics community. Using Monte Carlo samples of 5 ab$^{-1}$ at 250 GeV center-of-mass energy, the benchmark luminosity of CEPC Higgs runs, model independent (MI) analyses on Higgsstrahlung ($ZH$) cross section $\\sigma_{ZH}$ and Higgs mass $m_{H}$ are performed with $ZH$ events where the $Z$ boson decays into a pair of muons. The relative precision of $\\sigma_{ZH}$ could reach 0.92\\% and the $m_{H}$ could be measured to an accuracy of 6.5 MeV. Using information from Higgs decay final states, the backgrounds could be further reduced, leading to a mass precision of 5.4 MeV. The impacts of tracker size are investigated and parameterized for these measurements. Using similar analysis technology, we analyzed the capability of CEPC in measuring the Higgs invisible decay. Using $ZH$ ($Z\\rightarrow \\mu^{+}\\mu^{-}$) events at 5 ab$^{\\rm{-1}}$, the upper limit of invisible decay cross section beyond the standard ...
Buckley, Matthew R; Schell, Torben; Takeuchi, Michihisa
2013-01-01
We show that associated production of a Higgs with a top pair can be observed in purely hadronic decays. Reconstructing the top quarks in the form of jet buckets allows us to control QCD backgrounds as well as signal combinatorics. The background can be measured from side bands in the reconstructed Higgs mass. We back up our claims with a detailed study of the QCD event simulation, both for the signal and for the backgrounds.
Energy Technology Data Exchange (ETDEWEB)
Buckley, Matthew R. [Center for Particle Astrophysics, Fermi National Accelerator Laboratory,Batavia, IL (United States); Department of Physics and Astronomy, Rutgers University,Piscataway, NJ (United States); Plehn, Tilman; Schell, Torben [Institut für Theoretische Physik, Universität Heidelberg,Heidelberg (Germany); Takeuchi, Michihisa [Theoretical Particle Physics and Cosmology Group, Department of Physics,King’s College London, London WC2R 2LS (United Kingdom)
2014-02-28
We show that associated production of a Higgs with a top pair can be observed in purely hadronic decays. Reconstructing the top quarks in the form of jet buckets allows us to control QCD backgrounds as well as signal combinatorics. The background can be measured from side bands in the reconstructed Higgs mass. We back up our claims with a detailed study of the QCD event simulation, both for the signal and for the backgrounds.
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.
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.
Handbook of LHC Higgs Cross Sections: 4. Deciphering the Nature of the Higgs Sector
de Florian, D.
2017-01-01
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 ...
Muon performance studies in ATLAS towards a search for the Standard Model Higgs boson
van der Poel, E.F.
2012-01-01
Egge van der Poel deed onderzoek naar het Higgs-boson, het missende puzzelstukje in de natuurkundige beschrijving van elementaire deeltjes. Zijn onderzoek richtte zich op de ATLAS-detector bij de Large Hedron Collider (LHC). Deze detector kan worden gebruikt om een breed scala aan natuurkundige proc
Precision studies of the Higgs boson decay channel H -> ZZ -> 4l with MEKD
Avery, Paul; Chen, Mingshui; Cheng, Tongguang; Drozdetskiy, Alexey; Gainer, James S; Korytov, Andrey; Matchev, Konstantin T; Milenovic, Predrag; Mitselmakher, Guenakh; Park, Myeonghun; Rinkevicius, Aurelijus; Snowball, Matthew
2013-01-01
The importance of the H -> ZZ* -> 4l "golden" channel has recently been proven by its major role in the discovery, by the ATLAS and CMS collaborations, of an apparently Higgs-like resonance with mass near 125 GeV. Much previous phenomenological work on this channel focuses on its use in determining the spin and CP properties of a purported Higgs boson. Significantly less attention has been paid to the logically prior question of distinguishing signal from background events in this channel, which is especially important for a 125 GeV Higgs boson. We show the advantages of using a multivariate analysis, such as the Matrix Element Method (MEM) that will be discussed here, in separating the Higgs signal from the irreducible Standard Model background. We discuss a number of issues that may arise in the use of the MEM and compare existing leading order MEM-based approaches and software. We also provide a code to calculate a kinematic discriminant, KD, based on the full leading order matrix elements, which would aid...
Study of the Higgs boson properties by combining different production and decay channels
Ran, Kunlin; The ATLAS collaboration
2017-01-01
The poster is about combined measurements of Higgs boson production cross sections and branching fractions using the $H\\rightarrow\\gamma\\gamma$ and $H\\rightarrow ZZ^*\\rightarrow4l$ decay channels, based on 36.1 $\\text{fb}^{-1}$ of proton–proton collision data recorded by the ATLAS experiment at the LHC at $\\sqrt{s}=13$ TeV.
Exclusive weak radiative Higgs decays in the standard model and beyond
Alte, Stefan; König, Matthias; Neubert, Matthias
2016-12-01
We perform a detailed study of the exclusive Higgs decays h → MZ and h → MW, where M is a pseudoscalar or vector meson, using the QCD factorization approach. We allow for the presence of new-physics effects in the form of modified Higgs couplings to gauge bosons and fermions, including the possibility of flavor-changing Higgs couplings. We show that the decays h → VZ exhibit a strong sensitivity to the effective CP-even and CP-odd hγZ couplings. When combined with a measurement of the h → γZ decay rate, this can be used to extract these couplings up to a sign ambiguity in the CP-odd coefficient. Some of the h → MW decay modes can be used to probe for flavor-violating Higgs couplings involving the top quark.
Exclusive Weak Radiative Higgs Decays in the Standard Model and Beyond
Alte, Stefan; Neubert, Matthias
2016-01-01
We perform a detailed study of the exclusive Higgs decays $h\\to MZ$ and $h\\to MW$, where $M$ is a pseudoscalar or vector meson, using the QCD factorization approach. We allow for the presence of new-physics effects in the form of modified Higgs couplings to gauge bosons and fermions, including the possibility of flavor-changing Higgs couplings. We show that the decays $h\\to VZ$ exhibit a strong sensitivity to the effective CP-even and CP-odd $h\\gamma Z$ couplings. When combined with a measurement of the $h\\to\\gamma Z$ decay rate, this can be used to extract these couplings up to a sign ambiguity in the CP-odd coefficient. Some of the $h\\to MW$ decay modes can be used to probe for flavor-violating Higgs couplings involving the top quark.
Anatomy of the Higgs fits: a first guide to statistical treatments of the theoretical uncertainties
Fichet, Sylvain
2015-01-01
The studies of the Higgs boson couplings based on the recent and upcoming LHC data open up a new window on physics beyond the Standard Model. In this paper, we propose a statistical guide to the consistent treatment of the theoretical uncertainties entering the Higgs rate fits. Both the Bayesian and frequentist approaches are systematically analysed in a unified formalism. We present analytical expressions for the marginal likelihoods, useful to implement simultaneously the experimental and theoretical uncertainties. We review the various origins of the theoretical errors (QCD, EFT, PDF, production mode contamination...). All these individual uncertainties are thoroughly combined with the help of moment-based considerations. The theoretical correlations among Higgs detection channels appear to affect the location and size of the best-fit regions in the space of Higgs couplings. We discuss the recurrent question of the shape of the prior distributions for the individual theoretical errors and find that a nearl...
The model-independent analysis for Higgs boson
Indian Academy of Sciences (India)
M D NAIMUDDIN; SHIVALI MALHOTRA
2016-09-01
The discovery of a 125 GeV particle, announced by the ATLAS and CMS Collaborations on July 04, 2012, is one of the most important events in the recent history of particle physics. This particle could be the last missing particle of the Standard Model of particle physics or it could be the beginning of the long list of particles predicted by the physics beyond the Standard Model. Before we jump to make the final conclusion about this particle, it is imperative to study all the properties of this newly discovered particle. Since the model-dependentanalyses always have this danger of being biased, we can perform a model-independent search for the Higgs boson and also check if the 125 GeV particle is indeed the Standard Model Higgs boson or a particle belonging to the physics beyond the Standard Model.
Directory of Open Access Journals (Sweden)
Chen Xin
2016-01-01
Full Text Available 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, bb̄, 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.
Higgs and SUSY searches at future colliders
Indian Academy of Sciences (India)
Rohini M Godbole
2000-04-01
In this talk, I discuss some aspects of Higgs searches at future colliders, particularly comparing and contrasting the capabilities of LHC and next linear collider (NLC), including the aspects of Higgs searches in supersymmetric theories. I will also discuss how the search and study of sparticles other than the Higgs can be used to give information about the parameters of the minimal supersymmetric Standard Model (MSSM).
Brandstetter, Johannes
2016-01-01
ATLAS and CMS analyses of the most important decay channels are outlined and measurements of Higgs boson properties are summarized and compared with standard model expectations. This report presents ATLAS and CMS analyses with LHC run 1 data taken at centre-of-mass energies of $\\sqrt{s}=7~$TeV and $\\sqrt{s}=8~$TeV as well as the latest analyses with 2015 LHC run 2 data taken at a centre-of-mass energy of $\\sqrt{s}=13~$TeV.
The Higgs particles in the MSSM
Energy Technology Data Exchange (ETDEWEB)
Djouadi, A
2004-07-01
In these lectures, I review the Higgs sector of the Minimal Supersymmetric extension of the Standard Model (MSSM). In a first part, I discuss the link between ultraviolet divergences and symmetries and briefly introduce supersymmetry and the MSSM. In section 2, the two-doublet MSSM Higgs sector will be presented and the Higgs masses and interactions will be derived. In a third part I will discuss the decay modes of the various Higgs bosons, their production at LEP2 and the main experimental constraints on the Higgs spectrum. In section 4, I discuss the prospects for discovering the Higgs particles at the upgraded Tevatron, the LHC and at a high-energy e{sup +}e{sup -} linear collider, and summarize the possibility of studying their properties. (author)
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.
de Blas, Jorge; Franco, Enrico; Mishima, Satoshi; Pierini, Maurizio; Reina, Laura; Silvestrini, Luca
2016-01-01
We present results from a state-of-the-art fit of electroweak precision observables and Higgs-boson signal-strength measurements performed using 7 and 8 TeV data from the Large Hadron Collider. Based on the HEPfit package, our study updates the traditional fit of electroweak precision observables and extends it to include Higgs-boson measurements. As a result we obtain constraints on new physics corrections to both electroweak observables and Higgs-boson couplings. We present the projected accuracy of the fit taking into account the expected sensitivities at future colliders.
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.
LHCb Exotica and Higgs searches
Lucchesi, Donatella
2016-01-01
LHCb Collaboration has the unique opportunity to search for Higgs production and new physics in regions not accessible by the other LHC experiments. The latest results obtained by exploiting final states with b and c jets with or without an isolated lepton are presented.
CMS presents new boundary of Higgs width
Katarina Anthony
2014-01-01
At last year's Moriond conference, CERN physicists announced the retirement of the "Higgs-like" particle and the arrival of "boson, Higgs boson". Now, one year later, at the same session in the same conference, physicists are back with more exciting news about the famed particle. This time: the best constraint yet of the Higgs Boson “width”, a parameter that determines the particle’s lifetime. Rencontres de Moriond 2014. As a key indicator for new physics, the Higgs “width” has long been on the LHC "to-do" list. Now less than two years post-discovery, the CMS experiment has gotten the closest yet to pinning it down, constraining the parameter to < 17 MeV with 95% confidence. This result is some two orders of magnitude better than previous limits: stronger evidence that this boson looks like the Standard Model Higgs boson. "It's been exciting to see how wel...
Erler, Jens
2012-01-01
Assuming the validity of the Standard Model, or more generally that possible physics beyond it would have only small effects on production cross sections, branching ratios and electroweak radiative corrections, I determine the mass of the Higgs boson to 124.5 +- 0.8 GeV at the 68% CL. This is arrived at by combining electroweak precision data with the results of Higgs boson searches at LEP 2, the Tevatron, and the LHC. The statistical interpretation of the method does not require a look-elsewhere effect correction.
Chasco, Matthew Ervin
The Standard Model of particle physics is a theory describing the fundamental interactions and properties of subatomic particles. A key feature is its ability to explain particle mass through the Higgs mechanism, and a by-product of this mechanism is the Higgs boson. The discovery of the Higgs boson, in 2012 at CERN, completed the Standard Model particle zoo, but observed phenomena, like dark matter, remain unexplained. The analyses presented explore proton-proton collison events resulting in a Z boson plus missing transverse energy (MET). The motivation for this is to investigate two processes: Standard Model (SM) ZZ production, and beyond Standard Model (BSM) ZH production, in particular the ZZ → �+�−νν¯ and ZH → �+�− + Hinv channels. The place-holder Hinv is for all Higgs boson decay modes resulting in undetected “invisible” particles, which may branch to new physics, like dark matter particles. The data used are from Run 1 (2011–2012) of CMS, where proton-proton collisions at 7 Te...
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......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 condensate. We show that, in general, these states mix with repercussions on the electroweak physics and phenomenology. Our results will help clarify the main differences, similarities, benefits and shortcomings of the different ways one can naturally realize a composite nature of the electroweak sector...... transforming according to the fundamental representation of the gauge group. This minimal choice enables us to use recent first principle lattice results to make the first predictions for the massive spectrum for models of composite (Goldstone) Higgs dynamics. These results are of the upmost relevance to guide...
Gelmini, Graciela B
2014-01-01
The last particle that completes the Standard Model of Elementary Particles, the most sophisticated theory of nature in human history, was discovered in 2012. Although the present formulation of the theory comes from the 1960s and 70s, it incorporates all discoveries that thousands of scientists made about elementary particles and their interactions (except for gravity) since the 1700s. Even if briefly, here we review the development of the major concepts included in the theory and explain the relevance of the new particle and the mechanism for which F. Englert and P. Higgs received the Nobel Prize in Physics 2013
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.
Status of the Charged Higgs Boson in Two Higgs Doublet Models arXiv
Arbey, A.; Stal, O.; Stefaniak, T.
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(beta) - which increases to M_H+ > 650 GeV for tan(beta) < 1. We furthermore find that in certain scenario...
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.
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.
Unwuchola, D A
2015-01-01
The Standard Model (SM) has well known deciencies, and there is clearly need for new physics beyond the SM. The particles manifesting the new physics would interact at most weakly with the SM particles, and hence they are termed dark. The Higgs boson is potentially a favourable route for the production of the dark particles. There are a large class of theories where couplings or mixings at the Higgs level leads to exotic Higgs decays, which nonetheless do not signicantly disturb the known physics below the Higgs level. This is therefore a signicant potential discovery opportunity. We present the motivation and progress made in the studies which have been carried out as part of designing the search for the exotic decay of the SM Higgs which proceeds via a dark force back to SM four leptons, H $\\to$ Z$_d$Z$_d$ $\\to$ 4l from the LHC run 1 data using the ATLAS detector.
A Study for Doubly-Charged Higgs Boson at the Tevatron
Energy Technology Data Exchange (ETDEWEB)
Baroiant, Sasha [Univ. of California, Davis, CA (United States)
2006-01-01
We search for the pair production of doubly charged Higgs particles followed by the lepton-flavor violating decay of each Higgs into electron-and-tau and muonand- tau pairs using 350 pb^{-1} of data collected by the CDF II experiment at the Fermilab Tevatron. Separate searches investigate cases where three or four finalstate leptons are detected, and the limits for each exclusive decay mode reflect the combined results of both searches. Assuming the H$±±\\atop{L}$ decays exclusively into likesign electron-and-tau pairs, we set a lower limit on its mass of 114 GeV/c^{2} at the 95 % confidence level. In the case of exclusive muon-and-tau decays, we set a lower mass limit of 112 GeV/c^{2} also at the 95% confidence level.
Computer Simulations for Top Flavor-changing Neutral Higgs Interactions
Sloan, Jackson; Kao, Chung; Jain, Rishabh; McCoy, Brent
2017-01-01
Two-Higgs-doublet models (2HDM) are natural extensions to the Standard Model (SM), and a general 2HDM allows tree-level flavor-changing neutral currents (FCNC). We choose this model for our analysis. Since the top quark is heavier than the light Higgs, t -> ch is kinematically possible, and a tch coupling is an accessible example of an FCNC. We look to FCNCs to study physics beyond the Standard Model, and, more specifically, to examine the potential for discovery of a flavor-changing neutral Higgs (FCNH) interaction at the LHC. We examine the discovery potential for the processes pp -> th -> bjjWW -> bjjlνlν + X and pp -> t t -> bjjcWW + X , using MadGraph to generate parton level calculations, Pythia for showering and hadronization, and Delphes for detector simulation. We use ROOT analysis to reconstruct the transverse mass mT (ll ,ET) . We examine these processes and present event rates and significance of the Higgs signal, including SM physics background with realistic acceptance cuts for √{ s} = 13 TeV and √{ s} = 14 TeV. This research was funded in part by NSF award PHY-1359417.
And what if the Higgs boson did not exist; Si le boson de Higgs n'existait pas
Energy Technology Data Exchange (ETDEWEB)
Cho, A.; Daninos, F.; Baruch, J.O
2008-11-15
This series of articles presents the quest for the Higgs boson at the LHC (Large Hadron Collider). Different hypothesis are studied. First the Higgs boson is discovered and nothing else: no new particles and no new decay schemes. This hypothesis would mean that there would be no need for new physics. The second hypothesis is that the Higgs boson is not discovered and no new particles has appeared, in that case quantum mechanics and relativity would be seriously questioned. The third hypothesis is that a lot of exotic particles included the Higgs boson are discovered. This hypothesis is by far the most promising because it would solve troublesome issues linked to the standard model and would open the way for more fundamental theories like supersymmetry. The Atlas detector was designed to detect and select events resulting from the decay channels of the Higgs that are shorter than 10{sup -24} seconds. Alternative models that operate without Higgs boson have been studied since long. One of the most recent relies on the existence of a fifth compacted dimension. This model implies the existence of particles similar to W and Z bosons concerning quantum features but with a higher mass: between 500 and 1000 GeV. These particles could be detected in the LHC in its second phase of operation. Scores of physicists are working on the new generation of particle accelerators. The ILC (International Linear Collider) project is based on a 31 km long linear accelerator in which electrons and positrons will collide at an energy ranging from 0.5 to 1 TeV. (A.C.)
Higgs boson studies with the ATLAS detector at the Large Hadron Collider
AUTHOR|(INSPIRE)INSPIRE-00041986; The ATLAS collaboration
2016-01-01
In July 2012 a particle with properties consistent with those of a Higgs boson was discovered by the ATLAS and CMS experiments at the LHC. In this report I summarise the results of the measurements performed by the ATLAS experiment of the properties and the searches for rare and forbidden decays of this particle using the Run 1 LHC data, before concluding with an outlook on the future perspectives.
Probes for 4th generation constituents of dark atoms in Higgs boson studies at the LHC
Khlopov, M Yu
2014-01-01
The nonbaryonic dark matter of the Universe can consist of new stable charged species, bound in heavy neutral "atoms" by ordinary Coulomb interaction. Stable $\\bar U$ (anti-$U$)quarks of 4th generation, bound in stable colorless ($\\bar U \\bar U \\bar U $) clusters, are captured by the primordial helium, produced in Big Bang Nucleosynthesis, thus forming neutral "atoms" of O-helium (OHe), a specific nuclear interacting dark matter that can provide solution for the puzzles of direct dark matter searches. However, the existence of the 4th generation quarks and leptons should influence the production and decay rates of Higgs boson and is ruled out by the experimental results of the Higgs boson searches at the LHC, if the Higgs boson coupling to 4th generation fermions with is not suppressed. Here we argue that the difference between the three known quark-lepton families and the 4th family can naturally lead to suppression of this coupling, relating the accelerator test for such a composite dark matter scenario to ...
The role of the CMS electron and photon trigger in the study of the Higgs boson and other resonances
Strebler, Thomas
2016-01-01
The Compact Muon Solenoid (CMS) experiment implements a sophisticated two-level triggering system composed of the Level-1, instrumented by custom-design hardware boards, and a software High-Level-Trigger. A new Level-1 trigger architecture with improved performance is now being used to maintain the thresholds used in LHC Run I for the more challenging conditions experienced during Run II.We present the performance of the upgraded CMS electron and photon trigger in the context of Higgs boson decays into final states with photons and electrons. The calorimeter trigger system plays a central role in achieving the ambitious physics program of Run II. The upgraded trigger uses the full granularity of the calorimeters to optimally reconstruct and calibrate the electromagnetic trigger objects. It also implements combinations of calorimeter objects to provide new Level-1 quantities such as invariant mass. Optimized software selection techniques have been developed and advanced algorithms to mitigate the impact of eve...
Higgs pair productions in the CP-violating two-Higgs-doublet model
Bian, Ligong; Chen, Ning
2016-09-01
In this work, we study the SM-like Higgs pair productions in the framework of the general CP-violating two-Higgs-doublet model. Several constraints are imposed to the model sequentially, including the SM-like Higgs boson signal fits, the precise measurements of the electric dipole moments, the perturbative unitarity and stability bounds to the Higgs potential, and the most recent LHC searches for the heavy Higgs bosons. We show how the CP-violating mixing angles are related to the Higgs cubic self couplings in this setup. Based on these constraints, we suggest benchmark models for the future high-energy collider searches for the Higgs pair productions. The e + e - colliders operating at √{s} = (500 GeV, 1 TeV) are capable of measuring the Higgs cubic self couplings of the benchmark models directly. Afterwards, we estimate the cross sections of the resonance contributions to the Higgs pair productions for the benchmark models at the future LHC and SppC/Fcc-hh runs. Other possible decay modes for the heavy Higgs bosons are also discussed.
Boosting the charged Higgs search prospects using jet substructure at the LHC
Li, Jinmian; Patrick, Riley; Sharma, Pankaj; Williams, Anthony G.
2016-11-01
Charged Higgs bosons are predicted in variety of theoretically well-motivated new physics models with extended Higgs sectors. In this study, we focus on a type-II two Higgs doublet model (2HDM-II) and consider a heavy charged Higgs with its mass ranging from 500 GeV to 1 TeV as dictated by the b → sγ constraints which render M H ± > 480 GeV. We study the dominant production mode H ± t associated production with H ± → W ± A being the dominant decay channel when the pseudoscalar A is considerably lighter. For such a heavy charged Higgs, both the decay products W ± and A are relatively boosted. In such a scenario, we apply the jet substructure analysis of tagging the fat pseudoscalar and W jets in order to eliminate the standard model background efficiently. We perform a detailed detector simulation for the signal and background processes at the 14 TeV LHC. We introduce various kinematical cuts to determine the signal significance for a number of benchmark points with charged Higgs boson mass from 500 GeV to 1 TeV in the W ± A decay channel. Finally we perform a multivariate analysis utilizing a boosted decision tree algorithm to optimize these significances.
Seesaw majoron model of neutrino mass and novel signals in Higgs boson production at LEP
Díaz, Marco A.; García-Jareño, M. A.; Restrepo, Diego A.; Valle, José W. F.
1998-08-01
We perform a careful study of the neutral scalar sector of a model which includes a singlet, a doublet, and a triplet scalar field under SU(2). This model is motivated by neutrino physics, since it is simply the most general version of the seesaw model of neutrino mass generation through spontaneous violation of lepton number. The neutral Higgs sector contains three CP-even and one massive CP-odd Higgs boson A, in addition to the massless CP-odd mojoron J. The weakly interacting majoron remains massless if the breaking of lepton number symmetry is purely spontaneous. We show that the massive CP-odd Higgs boson may invisibly decay to three majorons, as well as to a CP-even Higgs H boson plus a majoron. We consider the associated Higgs production e+e- → Z → HA followed by invisible decays A → JJJ and H → JJ and derive the corresponding limits on masses and coupling that follow from LEP I precision measurements of the invisible Z width. We also study a novel b overlinebb overlinebp T signal predicted by the model, analyze the background and perform a Monte Carlo simulation of the signal in order to illustrate the limits on Higgs boson mass, couplings and branching ratios that follow from that.
Boosting the charged Higgs search prospects using jet substructure at the LHC
Energy Technology Data Exchange (ETDEWEB)
Li, Jinmian [Center of Excellence for Particle Physics at Terascale, University of Adelaide,Adelaide, 5005 South (Australia); School of Physics, Korea Institute for Advanced Study,Seoul, 130-722 (Korea, Republic of); Patrick, Riley; Sharma, Pankaj; Williams, Anthony G. [Center of Excellence for Particle Physics at Terascale, University of Adelaide,Adelaide, 5005 South (Australia)
2016-11-28
Charged Higgs bosons are predicted in variety of theoretically well-motivated new physics models with extended Higgs sectors. In this study, we focus on a type-II two Higgs doublet model (2HDM-II) and consider a heavy charged Higgs with its mass ranging from 500 GeV to 1 TeV as dictated by the b→sγ constraints which render M{sub H{sup ±}}>480 GeV. We study the dominant production mode H{sup ±}t associated production with H{sup ±}→W{sup ±}A being the dominant decay channel when the pseudoscalar A is considerably lighter. For such a heavy charged Higgs, both the decay products W{sup ±} and A are relatively boosted. In such a scenario, we apply the jet substructure analysis of tagging the fat pseudoscalar and W jets in order to eliminate the standard model background efficiently. We perform a detailed detector simulation for the signal and background processes at the 14 TeV LHC. We introduce various kinematical cuts to determine the signal significance for a number of benchmark points with charged Higgs boson mass from 500 GeV to 1 TeV in the W{sup ±}A decay channel. Finally we perform a multivariate analysis utilizing a boosted decision tree algorithm to optimize these significances.
Seesaw Majoron Model of Neutrino Mass and Novel Signals in Higgs Boson Production at LEP
Díaz, M A; Restrepo, D A; Valle, José W F; Diaz, Marco A.; Restrepo, Diego A.
1998-01-01
We perform a careful study of the neutral scalar sector of a model which includes a singlet, a doublet, and a triplet scalar field under $SU(2)$. This model is motivated by neutrino physics, since it is simply the most general version of the seesaw model of neutrino mass generation through spontaneous violation of lepton number. The neutral Higgs sector contains three CP-even and one massive CP-odd Higgs boson $A$, in addition to the massless CP-odd majoron $J$. The weakly interacting majoron remains massless if the breaking of lepton number symmetry is purely spontaneous. We show that the massive CP-odd Higgs boson may invisibly decay to three majorons, as well as to a CP-even Higgs $H$ boson plus a majoron. We consider the associated Higgs production $e^+e^- \\to Z corresponding limits on masses and coupling that follow from LEP I precision measurements of the invisible Z width. We also study a novel $b \\bar{b} perform a Monte-Carlo simulation of the signal in order to illustrate the limits on Higgs boson ma...
Search for BSM Higgs bosons in fermion decay modes with ATLAS
Straessner, Arno; The ATLAS collaboration
2017-01-01
Many physics models beyond the Standard Model (BSM) predict an extension of the Higgs sector, like the general 2-Higgs Doublet Model (2HDM) or supersymmetric models. In case of one additional Higgs doublet, there are five physical Higgs bosons: two CP neutral states (h,H), one CP odd state (A) and two charged Higgs bosons (H±). Typically, the already observed Higgs boson is identified with the h Higgs boson, while the others are assumed to be heavy. This presentation is reporting on recent results of direct searches for heavy neutral and charged Higgs bosons by the ATLAS Collaboration, in particular analyzing direct Higgs boson decays to fermions, like $H^\\pm \\to \\tau\
Energy Technology Data Exchange (ETDEWEB)
Dobrescu, Bogdan A. [Fermilab; Fox, Patrick J. [Fermilab; Kearney, John [Fermilab
2017-05-23
We study models that produce a Higgs boson plus photon ($h^0 \\gamma$) resonance at the LHC. When the resonance is a $Z'$ boson, decays to $h^0 \\gamma$ occur at one loop. If the $Z'$ boson couples at tree-level to quarks, then the $h^0 \\gamma$ branching fraction is typically of order $10^{-5}$ or smaller. Nevertheless, there are models that would allow the observation of $Z' \\to h^0 \\gamma$ at $\\sqrt{s} = 13$ TeV with a cross section times branching fraction larger than 1 fb for a $Z'$ mass in the 200--450 GeV range, and larger than 0.1 fb for a mass up to 800 GeV. The 1-loop decay of the $Z'$ into lepton pairs competes with $h^0 \\gamma$, even if the $Z'$ couplings to leptons vanish at tree level. We also present a model in which a $Z'$ boson decays into a Higgs boson and a pair of collimated photons, mimicking an $h^0 \\gamma$ resonance. In this model, the $h^0 \\gamma$ resonance search would be the discovery mode for a $Z'$ as heavy as 2 TeV. When the resonance is a scalar, although decay to $h^0 \\gamma$ is forbidden by angular momentum conservation, the $h^0$ plus collimated photons channel is allowed. We comment on prospects of observing an $h^0 \\gamma$ resonance through different Higgs decays, on constraints from related searches, and on models where $h^0$ is replaced by a nonstandard Higgs boson.
Resonance Production of Three Neutral Supersymmetric Higgs Bosons at LHC
Cynolter, G; Pócsik, G
2000-01-01
Multiple production of Higgs particles is essential to study Higgsself-couplings at future high-energy colliders. In this paper we calculated theresonance contributions to the production of three lightest neutralsupersymmetric Higgs bosons in gluon fusion at LHC. The cross sections due totrilinear Higgs couplings is sizeable but the measurement of the quarticcoupling hhhH(h) seems to be impossible.
Higgs particles interacting via a scalar Dark Matter field
Bhattacharya, Yajnavalkya; Darewych, Jurij
2016-07-01
We study a system of two Higgs particles, interacting via a scalar Dark Matter mediating field. The variational method in the Hamiltonian formalism of QFT is used to derive relativistic wave equations for the two-Higgs system, using a truncated Fock-space trial state. Approximate solutions of the two-body equations are used to examine the existence of Higgs bound states.
Top Signatures From Composite Higgs Theories
Vignaroli, Natascia
2016-01-01
Many compelling theories to address the Higgs hierarchy problem predict strong interactions between the top and a sector of New Physics. In minimal composite Higgs models (CHM), the top interactions with a BSM strongly-interacting sector give the leading contribution to trigger the EWSB and generate a light mass for the pseudo-NG Higgs. This implies that new composite states (vector-like top-partners, composite vector resonances, new composite scalars) dominantly interact with third-generation quarks and, when produced at colliders, generate top quarks in the final state. I will indicate interesting signatures involving top quarks for CHM discovery/test at the LHC and future colliders.
S(3) flavoured Higgs model trilinear self-couplings
Barradas-Guevara, E; Jáuregui, E Rodríguez
2014-01-01
In this work a detailed analysis of the Higgs sector of the minimal $S(3)$-invariant extension of the Standard Model is performed. Considering three Higgs fields, which are SU(2) doublets, and CP invariant, we compute the exact and analytical physical Higgs boson masses in terms of the Higgs potential parameters and the scalar Higgs matrix rotation angle $\\theta_S$ and $w_3$ ($\\tan\\theta_P=\\tan\\theta_C=\\tan^{-1}\\omega_3$), related to the pseudoscalar and charged Higgs matrix rotation angles $\\theta_P$ and $\\theta_C$ respectively. Furthermore, within this model we can also write down in an explicit form the trilinear self-couplings $\\lambda_{ijk}$ in terms of the Higgs masses and two free parameters,$\\theta_S$ and $w_3$. Moreover, we show that the Higgs masses and trilinear Higgs bosons self-couplings are closely linked to the Higgs potential structure given by the discrete symmetry $S(3)$, which can be helpful to distinguish this model from other extensions. In our analysis the lightest Higgs boson mass is ta...
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...
Volume Renormalization and the Higgs
Dai, De-Chang
2014-01-01
Traditionally, Quantum Field Theory (QFT) treats particle excitations as point-like objects, which is the source of ubiquitous divergences. We demonstrate that a minimal modification of QFT with finite volume particles may cure QFT of divergences and illuminate the physics behind the mathematical construct of our theories. The method allows for a non-perturbative treatment of the free field and self-interacting theories (though extensions to all interacting field theories might be possible). In particular, non-perturbatively defined mass is finite. When applied to the standard model Higgs mechanism, the method implies that a finite range of parameters allows for creation of a well defined Higgs particle, whose Compton wavelength is larger than its physical size, in the broken symmetry phase (as small oscillations around the vacuum). This has profound consequences for Higgs production at the LHC. The parameter range in which the Higgs excitation with the mass of 125 GeV behaves as a proper particle is very res...
The Beautiful Physics of LHC Run 2
AUTHOR|(CDS)2108556
2015-01-01
Run 2 of the LHC offers some beautiful prospects for new physics, including flavour physics as well as more detailed studies of the Higgs boson and searches for new physics beyond the Standard Model (BSM). One of the possibilities for BSM physics is supersymmetry, and flavour physics plays various important r\\^oles in constraining supersymmetric models.
Bolognesi, Sara; Di Simone, Andrea
2008-01-01
An overview of recent theoretical results on the Higgs boson and its discovery strategy at ATLAS and CMS will be presented, focusing on the main Higgs analysis effective with low integrated luminosity (less than 30 fb^-1).
Dedes, Georgios
2008-01-01
In this thesis, the discovery potential of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN for the heavy neutral Higgs bosons H/A of the Min- imal Supersymmetric extension of the Standard Model of particle physics (MSSM) in the decay channels H/A → τ + τ − → e/μ + X and H/A → μ+ μ− has been studied. The ATLAS detector is designed to study the full spectrum of the physics phenomena occuring in the proton-proton collisions at 14 TeV center-of-mass energy and to provide answers to the question of the origin of particle masses and of elec- troweak symmetry breaking. For the studies, the ATLAS muon spectrometer plays an important role. The spectrometer allows for a precise muon momentum measure- ment independently of other ATLAS subdetectors. The performance of the muon spectrometer depends strongly on the performance of the muon tracking detectors, the Monitored Drift Tube Chambers (MDT). Computer programs have been developed in order to test and verify the ATLAS muon spectrometer s...
Higgs Boson Production and Weak Boson Structure
1995-01-01
The influence of the QCD structure of the weak bosons on the Higgs boson production in $e$-$p$ scattering is studied. The energy and Higgs boson mass dependence of the cross-section, following from the new contributions, is calculated.
Constraints on new phenomena through Higgs coupling measurements with the ATLAS detector
Carrillo Montoya, German David; The ATLAS collaboration
2015-01-01
The discovery of the Higgs boson opens many perspectives to explore physics beyond the Standard Model. This talk describes constraints of new physics in a number of models using the combined measurements of the coupling strength of the 125 GeV Higgs particle using the entire ATLAS run-I data. The various models presented include an additional real electroweak singlet, two Higgs doublet models, a simplified Minimal Supersymmetric Standard Model, and a Higgs portal to dark matter.
Heinemeyer, S; Passarino, G; Tanaka, R; Andersen, J R; Artoisenet, P; Bagnaschi, E A; Banfi, A; Becher, T; Bernlochner, F U; Bolognesi, S; Bolzoni, P; Boughezal, R; Buarque, D; Campbell, J; Caola, F; Carena, M; Cascioli, F; Chanon, N; Cheng, T; Choi, S Y; David, A; de Aquino, P; Degrassi, G; Del Re, D; Denner, A; van Deurzen, H; Diglio, S; Di Micco, B; Di Nardo, R; Dittmaier, S; Dührssen, M; Ellis, R K; Ferrera, G; Fidanza, N; Flechl, M; de Florian, D; Forte, S; Frederix, R; Frixione, S; Gangal, S; Gao, Y; Garzelli, M V; Gillberg, D; Govoni, P; Grazzini, M; Greiner, N; Griffiths, J; Gritsan, A V; Grojean, C; Hall, D C; Hays, C; Harlander, R; Hernandez-Pinto, R; Höche, S; Huston, J; Jubb, T; Kadastik, M; Kallweit, S; Kardos, A; Kashif, L; Kauer, N; Kim, H; Klees, R; Krämer, M; Krauss, F; Laureys, A; Laurila, S; Lehti, S; Li, Q; Liebler, S; Liu, X; Logan, E; Luisoni, G; Malberti, M; Maltoni, F; Mawatari, K; Maierhoefer, F; Mantler, H; Martin, S; Mastrolia, P; Mattelaer, O; Mazzitelli, J; Mellado, B; Melnikov, K; Meridiani, P; Miller, D J; Mirabella, E; Moch, S O; Monni, P; Moretti, N; Mück, A; Mühlleitner, M; Musella, P; Nason, P; Neu, C; Neubert, M; Oleari, C; Olsen, J; Ossola, G; Peraro, T; Peters, K; Petriello, F; Piacquadio, G; Potter, C T; Pozzorini, S; Prokofiev, K; Puljak, I; Rauch, M; Rebuzzi, D; Reina, L; Rietkerk, R; Rizzi, A; Rotstein-Habarnau, Y; Salam, G P; Sborlini, G; Schissler, F; Schönherr, M; Schulze, M; Schumacher, M; Siegert, F; Slavich, P; Smillie, J M; Stål, O; von Soden-Fraunhofen, J F; Spira, M; Stewart, I W; Tackmann, F J; Taylor, P T E; Tommasini, D; Thompson, J; Thorne, R S; Torrielli, P; Tramontano, F; Tran, N V; Trócsányi, Z; Ubiali, M; Vazquez Acosta, M; Vickey, T; Vicini, A; Waalewijn, W J; Wackeroth, D; Wagner, C; Walsh, J R; Wang, J; Weiglein, G; Whitbeck, A; Williams, C; Yu, J; Zanderighi, G; Zanetti, M; Zaro, M; Zerwas, P M; Zhang, C; Zirke, T J E; Zuberi, S
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 p...
Heinemeyer, S; Passarino, G; Tanaka, R; Andersen, J R; Artoisenet, P; Bagnaschi, E A; Banfi, A; Becher, T; Bernlochner, F U; Bolognesi, S; Bolzoni, P; Boughezal, R; Buarque, D; Campbell, J; Caola, F; Carena, M; Cascioli, F; Chanon, N; Cheng, T; Choi, S Y; David, A; de Aquino, P; Degrassi, G; Del Re, D; Denner, A; van Deurzen, H; Diglio, S; Di Micco, B; Di Nardo, R; Dittmaier, S; Dührssen, M; Ellis, R K; Ferrera, G; Fidanza, N; Flechl, M; de Florian, D; Forte, S; Frederix, R; Frixione, S; Gangal, S; Gao, Y; Garzelli, M V; Gillberg, D; Govoni, P; Grazzini, M; Greiner, N; Griffiths, J; Gritsan, A V; Grojean, C; Hall, D C; Hays, C; Harlander, R; Hernandez-Pinto, R; Höche, S; Huston, J; Jubb, T; Kadastik, M; Kallweit, S; Kardos, A; Kashif, L; Kauer, N; Kim, H; Klees, R; Krämer, M; Krauss, F; Laureys, A; Laurila, S; Lehti, S; Li, Q; Liebler, S; Liu, X; Logan, E; Luisoni, G; Malberti, M; Maltoni, F; Mawatari, K; Maierhoefer, F; Mantler, H; Martin, S; Mastrolia, P; Mattelaer, O; Mazzitelli, J; Mellado, B; Melnikov, K; Meridiani, P; Miller, D J; Mirabella, E; Moch, S O; Monni, P; Moretti, N; Mück, A; Mühlleitner, M; Musella, P; Nason, P; Neu, C; Neubert, M; Oleari, C; Olsen, J; Ossola, G; Peraro, T; Peters, K; Petriello, F; Piacquadio, G; Potter, C T; Pozzorini, S; Prokofiev, K; Puljak, I; Rauch, M; Rebuzzi, D; Reina, L; Rietkerk, R; Rizzi, A; Rotstein-Habarnau, Y; Salam, G P; Sborlini, G; Schissler, F; Schönherr, M; Schulze, M; Schumacher, M; Siegert, F; Slavich, P; Smillie, J M; Stål, O; von Soden-Fraunhofen, J F; Spira, M; Stewart, I W; Tackmann, F J; Taylor, P T E; Tommasini, D; Thompson, J; Thorne, R S; Torrielli, P; Tramontano, F; Tran, N V; Trócsányi, Z; Ubiali, M; Vazquez Acosta, M; Vickey, T; Vicini, A; Waalewijn, W J; Wackeroth, D; Wagner, C; Walsh, J R; Wang, J; Weiglein, G; Whitbeck, A; Williams, C; Yu, J; Zanderighi, G; Zanetti, M; Zaro, M; Zerwas, P M; Zhang, C; Zirke, T J E; Zuberi, S
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 p...
Ross, Ian Ackerman
2013-01-01
A study of the $pp \\rightarrow ZZ \\rightarrow \\ell\\ell\\ell\\ell$ final state is conducted using 19.6$fb^{-1}$ of 8 TeV proton-proton collisions at the LHC using the CMS detector. The Standard Model $pp \\rightarrow ZZ$ production cross section is measured to be $\\sigma(pp\\rightarrow ZZ) = 7.7^{+0.5}_{-0.5} \\textrm(stat.) ^{+0.6}_{-0.5} \\textrm{(sys.)} \\pm 0.3 \\textrm{(lumi)}~\\textrm{pb} $. Evidence of a new Higgs-like boson is observed with a significance of $6.1 \\sigma$ at 126~GeV. 95% confidence level upper limits are set on the neutral anomalous triple gauge\
Arbouch, Emmanuel Jean
2016-01-01
One of the main purposes of the high-luminosity LHC (HL-LHC) program at CERN will be to study in more detail the Higgs boson and measure its couplings. For the HL-LHC project, the ATLAS detector will have to be upgraded. The mean number of interactions per crossing will be about 200 compared to 40 in Run-2. The ATLAS detector will have to cope with this increased pile-up. In the forward-backward region, there is a proposal to insert a high-ganularity timing detector (HGTD), which could provide a new powerful trigger capability of interesting physics signal such as vector-boson-fusion (VBF) and possibility to separate pile-up from hard scatter signals.\\\\ In order to evaluate the physics potential of such upgrades, analyses are needed to determine whether the gain from HGTD in terms of geometrical acceptance, improved granularity and jet discrimination based on timing information could increase VBF signal detection efficiency and background rejection. This study is the first milestone towards assessing ultimate...
Little Higgs model effects in →
Indian Academy of Sciences (India)
S Rai Choudhury; Ashok Goyal; A S Cornell; Naveen Gaur
2007-11-01
Though the predictions of the standard model (SM) are in excellent agreement with experiments, there are still several theoretical problems associated with the Higgs sector of the SM, where it is widely believed that some new physics will take over at the TeV scale. One beyond the SM theory which resolves these problems is the Little Higgs (LH) model. In this work we have investigated the effects of the LH model on → scattering [1].
New Charged Particles from Higgs Couplings
Cohen, Andrew G
2012-01-01
The recently reported observation of a new particle with mass about 125 GeV and couplings generally resembling those of the Standard Model Higgs boson provides a potential probe of the physics of electroweak symmetry breaking. Although the current data only provides hints, we suggest a particular combination of Higgs couplings as an assay for new charged particles connected with electroweak symmetry breaking, and construct a simple model with charge 5/3 quarks as a demonstration of its use.
Improving acceptance for Higgs events at CDF
Energy Technology Data Exchange (ETDEWEB)
Sforza, Federico; /INFN, Pisa
2008-03-01
The Standard Model of elementary particles predicts the existence of the Higgs boson as the responsable of the electroweak symmetry breaking, the process by which fermions and vector bosons acquire mass. The Higgs existence is one of the most important questions in the present high energy physics research. This work concerns the search of W H associate production at the CDF II experiment (Collider Detector at Fermilab).
Liu, Bo; The ATLAS collaboration
2015-01-01
Using run-I data record by ATLAS detector, many searches on the higgs decay modes have been done. Also some properties measurement of the Higgs Boson has been done. This talk will summarise the recent result of Higgs search and measurement from ATLAS.
DEFF Research Database (Denmark)
Giardino, P. P.; Kannike, K.; Masina, I.
2014-01-01
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...
Vivarelli, I; Gennai, S; Primo workshop italiano sulla fisica di ATLAS e CMS
2003-01-01
The ATLAS and CMS discovery potential for the MSSM Higgs bosons is reviewed in this paper. The attention is focused on the direct Higgs production and on the Standard Model decay channels. After a short introduction, the most promising final states are discussed, showing that, if supersymmetry exists, its Higgs sector can be explored at LHC with an integrated luminosity of 10 fb$^{-1}$.
Csorgo, T
2013-01-01
One of the highlights of 2012 in physics is related to two papers, published by the ATLAS and the CMS Collaborations, that announced the discovery of at least one new particle in pp collisions at CERN LHC. At least one of the properties of this new particle is found to be similar to that of the Higgs boson, the last and most difficult to find building block from the Standard Model of particle physics. Physics teachers are frequently approached by their media-educated students, who inquire about the properties of the Higgs boson, but physics teachers are rarely trained to teach this elusive aspect of particle physics in elementary, middle or junior high schools. In this paper I describe a card-game, that can be considered as a hands-on and easily accessible tool that allows interested teachers, students and also motivated lay-persons to play with the properties of the newly found Higgs-like particle. This new particle was detected through its decays to directly observable, final state particles. Many of these ...
Precision Higgs boson measurement at CLIC
AUTHOR|(SzGeCERN)718111
2016-01-01
The design of the next generation collider in high energy physics will primarily focus on the possibility to achieve high precision of the measurements of interest. The necessary precision limits are set, in the first place, by the measurement of the Higgs boson but also by measurements that are sensitive to signs of New Physics. The Compact Linear Collider (CLIC) is an attractive option for a future multi-TeV linear electron-positron collider, with the potential to cover a rich physics program with high precision. In this lecture the CLIC accelerator, detector and backgrounds will be presented with emphesis on the capabilities of CLIC for precision Higgs physics.
The standard model Higgs search at the large hadron collider
Indian Academy of Sciences (India)
Satyaki Bhattacharya; on behalf of the CMS and the ATLAS Collaborations
2007-11-01
The experiments at the large hadron collider (LHC) will probe for Higgs boson in the mass range between the lower bound on the Higgs mass set by the experiments at the large electron positron collider (LEP) and the unitarity bound (∼ 1 TeV). Strategies are being developed to look for signatures of Higgs boson and measure its properties. In this paper results from full detector simulation-based studies on Higgs discovery from both ATLAS and CMS experiments at the LHC will be presented. Results of simulation studies on Higgs coupling measurement at LHC will be discussed.
Bounding the Higgs boson width through interferometry.
Dixon, Lance J; Li, Ye
2013-09-13
We study the change in the diphoton-invariant-mass distribution for Higgs boson decays to two photons, due to interference between the Higgs resonance in gluon fusion and the continuum background amplitude for gg→γγ. Previously, the apparent Higgs mass was found to shift by around 100 MeV in the standard model in the leading-order approximation, which may potentially be experimentally observable. We compute the next-to-leading-order QCD corrections to the apparent mass shift, which reduce it by about 40%. The apparent mass shift may provide a way to measure, or at least bound, the Higgs boson width at the Large Hadron Collider through "interferometry." We investigate how the shift depends on the Higgs width, in a model that maintains constant Higgs boson signal yields. At Higgs widths above 30 MeV, the mass shift is over 200 MeV and increases with the square root of the width. The apparent mass shift could be measured by comparing with the ZZ* channel, where the shift is much smaller. It might be possible to measure the shift more accurately by exploiting its strong dependence on the Higgs transverse momentum.
Anomaly mediated supersymmetric models and Higgs data from the LHC
Arbey, A; Mahmoudi, F; Tarhini, A
2013-01-01
Anomaly mediation models are well motivated supersymmetry breaking scenarios which appear as alternatives to the mSUGRA paradigm. These models are quite compelling from the theoretical point of view and it is therefore important to test if they are also viable models for phenomenology. We perform a study of these models in the light of all standard flavour, collider and dark matter constraints, including also the recent Higgs boson measurements for the mass and signal strengths in the different decay channels. The minimal AMSB scenario can satisfy in part of its parameter space the dark matter requirement but is only marginally consistent with the current Higgs boson mass value. The HyperCharge-AMSB and Mixed Moduli-AMSB scenarios can better describe present data from dark matter, flavour, low energy physics and are consistent with the measured mass of the Higgs boson. The inclusion of the preferred signal strengths for the Higgs boson decay channels shows that for tan(beta) > 5 the HC-AMSB and MM-AMSB models...
The Twin Higgs mechanism and Composite Higgs
Low, Matthew; Wang, Lian-Tao
2015-01-01
We combine the Twin Higgs mechanism with the paradigm of Composite Higgs models. In this class of models the Higgs is a pseudo-Nambu-Goldstone boson from a strongly coupled sector near the TeV scale, and it is additionally protected by a discrete symmetry due to the twin mechanism. We discuss the model building issues associated with this setup and quantify the tuning needed to achieve the correct electroweak vacuum and the Higgs mass. In contrast to standard Composite Higgs models, the lightest resonance associated with the top sector is the uncolored mirror top, while the colored top partners can be made parameterically heavier without extra tuning. In some cases, the vector resonances are predicted to lie in the multi-TeV range. We present models where the resonances - both fermions and vectors - being heavier alleviates the pressure on naturalness coming from direct searches demonstrating that theories with low tuning may survive constraints from the Large Hadron Collider.
Axion-Higgs interplay in the two Higgs-doublet model
Espriu, Domenec; Renau, Albert
2015-01-01
We study the Dine-Fischler-Srednicki (DFS) model in the light of the recent Higgs LHC results and electroweak precision data. The DFS model is a natural extension of the two-Higgs doublet model endowed with a Peccei-Quinn symmetry and leading to a physically acceptable axion. For generic couplings, the model reproduces the minimal Standard Model showing only tiny deviations (extreme decoupling scenario) whereas all additional degrees of freedom (with the exception of the axion) are very heavy. Recently, new corners of this model have been highlighted where it may exhibit enlarged global symmetries making the corresponding models technically natural (naturalness scenario). In some cases an additional Higgs could be present at the weak scale. In this case, the new light $0^+$ state would be accompanied by relatively light charged and neutral pseudoscalar Higgses. We will use the oblique corrections, particularly $\\Delta\\rho$, to constrain the mass spectrum in this case. As a final result, we also work out the n...
Fermiophobia in a Higgs Triplet Model
Akeroyd, A G; Rivera, Maximiliano A; Romero, Diego
2010-01-01
A Fermiophobic Higgs boson can arise in models with an extended Higgs sector, such as models with scalars in an isospin triplet representation. In a specific model with a scalar triplet and spontaneous violation of lepton number induced by a scalar singlet field, we show that fermiophobia is not a fine-tuned situation, unlike in Two Higgs Doublet Models. We study distinctive signals of fermiophobia which can be probed at the LHC. For the case of a small Higgs mass a characteristic signal would be a moderate B(H ->\\gamma\\gamma) accompanied by a large B(H -> JJ) (where J is a Majoron), the latter being an invisible decay. For the case of a large Higgs mass there is the possibility of dominant H -> ZZ, WW and suppressed H -> JJ decay modes. In this situation, B(H -> ZZ) is larger than B(H -> WW), which differs from the SM prediction.
Collider Signatures of Flavorful Higgs Bosons
Altmannshofer, Wolfgang; Gori, Stefania; Lotito, Matteo; Martone, Mario; Tuckler, Douglas
2016-01-01
Motivated by our limited knowledge of the Higgs couplings to first two generation fermions, we analyze the collider phenomenology of a class of two Higgs doublet models (2HDMs) with a non-standard 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, {\\mu}{\\mu}, {\\tau}{\\mu} and H+ -> cb, cs, {\\mu}{\
Higgs versus matter in the heterotic landscape
Energy Technology Data Exchange (ETDEWEB)
Buchmueller, W.; Schmidt, J.
2008-07-15
In supersymmetric extensions of the standard model there is no basic difference between Higgs and matter fields, which leads to the well known problem of potentially large baryon and lepton number violating interactions. Although these unwanted couplings can be forbidden by continuous or discrete global symmetries, a theoretical guiding principle for their choice is missing. We examine this problem for a class of vacua of the heterotic string compactified on an orbifold. As expected, in general there is no difference between Higgs and matter. However, certain vacua happen to possess unbroken matter parity and discrete R-symmetries which single out Higgs fields in the low energy effective field theory. We present a method how to identify maximal vacua in which the perturbative contribution to the {mu}-term and the expectation value of the superpotential vanish. Two vacua are studied in detail, one with two pairs of Higgs doublets and one with partial gauge-Higgs unification. (orig.)
Discovering Uncolored Naturalness in Exotic Higgs Decays
Curtin, David
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...
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.
Higgs Bosons in the Next-to-Minimal Supersymmetric Standard Model at the LHC
Ellwanger, Ulrich
2011-01-01
We review possible properties of Higgs bosons in the NMSSM, which allow to discriminate this model from the MSSM: masses of mostly Standard-Model-like Higgs bosons at or above 140 GeV, or enhanced branching fractions into two photons, or Higgs-to-Higgs decays. In the case of a Standard-Model-like Higgs boson above 140 GeV, it is necessarily accompagnied by a lighter state with a large gauge singlet component. Examples for such scenarios are presented. Available studies on Higgs-to-Higgs decay...
Hernández-Sánchez, J; Noriega-Papaqui, R; Rosado, A
2013-01-01
We discuss flavor-violating constraints and consequently possible charged Higgs boson phenomenology emerging from a four-zero Yukawa texture embedded within the Type-III 2-Higgs Doublet Model (2HDM-III). Firstly, we show in detail how we can obtain several kinds of 2HDMs when some parameters in the Yukawa texture are absent. Secondly, we present a comprehensive study of the main $B$-physics constraints on such parameters induced by flavor-changing processes, in particular on the off-diagonal terms of such a texture: i.e., from $\\mu -e$ universality in $\\tau$ decays, several leptonic B-decays ($B \\to \\tau \
Probing the Electroweak Phase Transition with Higgs Factories and Gravitational Waves
Huang, Peisi; Wang, Lian-Tao
2016-01-01
After the discovery of the Higgs boson, understanding the nature of electroweak symmetry breaking and the associated electroweak phase transition has become the most pressing question in particle physics. Answering this question is a priority for experimental studies. Data from the LHC and future lepton collider-based Higgs factories may uncover new physics coupled to the Higgs boson, which can induce the electroweak phase transition to become first order. Such a phase transition generates a stochastic background of gravitational waves, which could potentially be detected by a space-based gravitational wave interferometer. In this paper, we survey a few classes of models in which the electroweak phase transition is strongly first order. We identify the observables that would provide evidence of these models at the LHC and next-generation lepton colliders, and we assess whether the corresponding gravitational wave signal could be detected by eLISA. We find that most of the models with first order electroweak p...
Erler, J
2006-01-01
The prospects for electroweak physics at the LHC are reviewed focusing mainly on precision studies. This includes projections for measurements of the effective Z pole weak mixing angle, of top quark, W boson, and Higgs scalar properties, and new physics searches.
Gravitational Interaction of Higgs Boson and Weak Boson Scattering
Xianyu, Zhong-Zhi; He, Hong-Jian
2013-01-01
With the LHC discovery of a 125GeV Higgs-like particle, we study gravitational interaction of Higgs boson via the unique dimension-4 operator involving Higgs doublet and scalar curvature, \\xi H^\\dag H R, with nonminimal coupling \\xi. This Higgs portal term can be transformed away in Einstein frame and induces gauge-invariant effective interactions in the Higgs sector. We study the weak boson scattering in Einstein frame, and explicitly demonstrate the longitudinal-Goldstone boson equivalence theorem in the presence of \\xi coupling. With these, we derive unitarity bound on the Higgs gravitational coupling \\xi in Einstein frame, which is stronger than that inferred from the LHC Higgs measurements. We further analyze \\xi-dependent weak boson scattering cross sections at TeV scale, and study the LHC probe of \\xi coupling via weak boson scattering experiments.
How to Determine the Probability of the Higgs Boson Detection
Unzicker, Alexander
2009-01-01
The Higgs boson is the most important, though yet undiscovered ingredient of the standard model of particle physics. Its detection is therefore one of the most important goals of high energy physics that can guide future research in theoretical physics. Enormous efforts have been undertaken to prove the existence of the Higgs boson, and the physics community is excitedly awaiting the restart of the Large Hadron Collider at CERN. But how sure can we be that the Higgs exits at all? The German philosopher Immanuel Kant recommended betting at such controversial questions, and Stephen Hawking announced a $100 bet against the Higgs. But seriously, online prediction markets, which are a generalized form of betting, do provide the best possible probability estimates for future events. It is proposed that the scientific community uses this platforms for evaluation. See also an online description www.Bet-On-The-Higgs.com.
C. Hill
2013-01-01
In the period since the last CMS Bulletin, the LHC – and CMS – have entered LS1. During this time, CMS Physics Analysis Groups have performed more than 40 new analyses, many of which are based on the complete 8 TeV dataset delivered by the LHC in 2012 (and in some cases on the full Run 1 dataset). These results were shown at, and well received by, several high-profile conferences in the spring of 2013, including the inaugural meeting of the Large Hadron Collider Physics Conference (LHCP) in Barcelona, and the 26th International Symposium on Lepton Photon Interactions at High Energies (LP) in San Francisco. In parallel, there have been significant developments in preparations for Run 2 of the LHC and on “future physics” studies for both Phase 1 and Phase 2 upgrades of the CMS detector. The Higgs analysis group produced five new results for LHCP including a new H-to-bb search in VBF production (HIG-13-011), ttH with H to γ&ga...
Maximal CP violation in the Higgs sector and its effect on the $\\varrho$ parameter
Joshi, G C; Tanimoto, M; Grish C Joshi; Masahisa Matsuda; Morimitsu Tanimoto
1994-01-01
Abstract:We study the conditions of maximal CP violation in the neutral Higgs mass matrix of the two Higgs doublet model. We get fixed values of \\tan\\b and constraints on the Higgs potential parameters. Two neutral Higgs scalars are constrained to be lighter than the charged Higgs scalar and these two Higgs scalars are expected to be almost degenerate due to the smallness of the h parameter, where h is the CP violating coupling constant of the Higgs interaction. The radiative correction of the \\rho parameter from the Higgs scalar exchange is rather small and its sign negative for a wide range of Higgs masses. It follows that maximum CP violation in the two Higgs doublet model is safely allowed for the \\rho parameter without the custodial symmetry.
Capri, M A L; Gomez, A J; Guimaraes, M S; Justo, I F; Sorella, S P
2013-01-01
We present an analytical study of continuum 4d SU(2) gauge Higgs models with a single Higgs field with fixed length in either the fundamental or adjoint representation. We aim at probing the renowned predictions of Fradkin & Shenker on the phase diagram in terms of confinement versus Higgs behaviour, obtained in lattice numerical simulations. We work in the Landau version of the 't Hooft R_\\xi gauges in which case we can access potential nonperturbative physics related to the existence of the Gribov copies. In the fundamental case, we clearly show that in the perturbative regime of small gauge coupling constant g and large Higgs vacuum expectation value v, there is a Higgs phase with Yukawa gauge boson propagators without Gribov effects. For a small value of the Higgs vev v and/or large g, we enter a region with Gribov type propagators that have no physical particle interpretation: the gauge bosons are as such confined. The transition between both behaviours is found to be continuous. In the adjoint case,...
Studies of Higgs boson production in the four-lepton final state at $\\sqrt{s}=13~\\mathrm{TeV}$
CMS Collaboration
2016-01-01
Studies of Higgs boson production are presented using the $\\mathrm{H}\\rightarrow\\mathrm{Z}\\mathrm{Z}\\rightarrow4\\ell$ ($\\ell=\\mathrm{e},\\mu$) decay channel. These studies are performed using a data sample corresponding to an integrated luminosity of $2.8~\\mathrm{fb}^{-1}$ of pp collisions at a center-of-mass energy of $13~\\mathrm{TeV}$ collected by the CMS experiment at the LHC during 2015. The observed significance for the standard model Higgs boson with $m_{\\mathrm{H}}=125.09~\\mathrm{GeV}$ is $2.5\\sigma$, where the expected significance is $3.4\\sigma$. The model independent fiducial cross section is measured to be $\\sigma_{\\mathrm{fid.}}=2.48^{+1.48}_{-1.14}(\\mathrm{stat. \\oplus sys.})^{+0.01}_{-0.04}(\\mathrm{model~dep.})~\\mathrm{fb}$. In addition, a search for an additional Higgs boson is performed for a range of masses up to 1 TeV and with various widths, and no significant excess is observed. The results of this search are interpreted in the context of the two Higgs doublet model.
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.
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.
Very boosted Higgs in gluon fusion
Energy Technology Data Exchange (ETDEWEB)
Grojean, C. [Univ. Autonoma de Barcelona, Bellaterra (Spain). ICREA at IFAE; Salvioni, E. [California Univ., Davis, CA (United States). Dept. of Physics; European Organization for Nuclear Research (CERN), Geneva (Switzerland); Padova Univ. (Italy). Dipt. di Fisica e Astronomica; INFN, Sezione di Padova (Italy); Schlaffer, M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Weiler, A. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2013-12-15
The Higgs production and decay rates offer a new way to probe new physics beyond the Standard Model. While dynamics aiming at alleviating the hierarchy problem generically predict deviations in the Higgs rates, the current experimental analyses cannot resolve the long- and short-distance contributions to the gluon fusion process and thus cannot access directly the coupling between the Higgs and the top quark. We investigate the production of a boosted Higgs in association with a high-transverse momentum jet as an alternative to the t anti th channel to pin down this crucial coupling. Presented rst in the context of an effective field theory, our analysis is then applied to models of partial compositeness at the TeV scale and of natural supersymmetry.
Very boosted Higgs in gluon fusion
Energy Technology Data Exchange (ETDEWEB)
Grojean, C. [ICREA at IFAE, Universitat Autónoma de Barcelona,E-08193 Bellaterra (Spain); Salvioni, E. [Department of Physics, University of California,Davis, CA 95616 (United States); Theory Division, Physics Department, CERN,CH-1211 Geneva 23 (Switzerland); Dipartimento di Fisica e Astronomia, Università di Padova and INFN, Sezione di Padova,Via Marzolo 8, I-35131 Padova (Italy); Schlaffer, M. [DESY,Notkestrasse 85, D-22607 Hamburg (Germany); Weiler, A. [Theory Division, Physics Department, CERN,CH-1211 Geneva 23 (Switzerland); DESY,Notkestrasse 85, D-22607 Hamburg (Germany)
2014-05-06
The Higgs production and decay rates offer a new way to probe new physics beyond the Standard Model. While dynamics aiming at alleviating the hierarchy problem generically predict deviations in the Higgs rates, the current experimental analyses cannot resolve the long- and short-distance contributions to the gluon fusion process and thus cannot access directly the coupling between the Higgs and the top quark. We investigate the production of a boosted Higgs in association with a high-transverse momentum jet as an alternative to the tt-macronh channel to pin down this crucial coupling. Presented first in the context of an effective field theory, our analysis is then applied to models of partial compositeness at the TeV scale and of natural supersymmetry.
The Minimal Moose for a Little Higgs
Arkani-Hamed, N; Gregoire, T; Katz, E; Nelson, A E; Wacker, J G
2002-01-01
Recently a new class of theories of electroweak symmetry breaking have been constructed. These models, based on deconstruction and the physics of theory space, provide the first alternative to weak-scale supersymmetry with naturally light Higgs fields and perturbative new physics at the TeV scale. The Higgs is light because it is a pseudo-Goldstone boson, and the quadratically divergent contributions to the Higgs mass are cancelled by new TeV scale ``partners'' of the {\\em same} statistics. In this paper we present the minimal theory space model of electroweak symmetry breaking, with two sites and four link fields, and the minimal set of fermions. There are very few parameters and degrees of freedom beyond the Standard Model. Below a TeV, we have the Standard Model with two light Higgs doublets, and an additional complex scalar weak triplet and singlet. At the TeV scale, the new particles that cancel the 1-loop quadratic divergences in the Higgs mass are revealed. The entire Higgs potential needed for electro...
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.
Stefanidis, E
2003-01-01
The ATLAS (A Toroidal LHC ApparatuS) detector is one of the four detectors which will be installed in the new accelerator, at LHC, CERN. One of the experiments' research aims is the discovery of the Higgs particle and thus, the confirmation or not of the Standard Model. The Muon Spectrometer of the detector has special importance, because the decay channels of the Higgs particle which have muons at the final state are clear signatures of the existence of the Higgs particle. This project focuses on the Higgs decay through the channel: H->ZZ->4mu. The alignment of the muon detectors has to be very accurate, so that its contribution on the measurement of the muons' momentum, to be low compared to the intrinsic resolution of the detectors themselves. Although the alignment of the muons detectors at the barrel and the end-caps regions is well controlled, the relative alignment of the end-caps with respect to barrel is not controlled with the same accuracy. In this project, we study the influence of such misalignme...
Postinflationary vacuum instability and Higgs-inflaton couplings
Energy Technology Data Exchange (ETDEWEB)
Enqvist, Kari [University of Helsinki and Helsinki Institute of Physics,P.O. Box 64, Helsinki, FI-00014 (Finland); Karčiauskas, Mindaugas [University of Jyväskylä, Department of Physics,P.O. Box 35 (YFL), Jyväskylä, FI-40014 (Finland); Lebedev, Oleg; Rusak, Stanislav; Zatta, Marco [University of Helsinki and Helsinki Institute of Physics,P.O. Box 64, Helsinki, FI-00014 (Finland)
2016-11-11
The Higgs-inflaton coupling plays an important role in the Higgs field dynamics in the early Universe. Even a tiny coupling generated at loop level can have a dramatic effect on the fate of the electroweak vacuum. Such Higgs-inflaton interaction is present both at the trilinear and quartic levels in realistic reheating models. In this work, we examine the Higgs dynamics during the preheating epoch, focusing on the effects of the parametric and tachyonic resonances. We use lattice simulations and other numerical tools in our studies. We find that the resonances can induce large fluctuations of the Higgs field which destabilize the electroweak vacuum. Our considerations thus provide an upper bound on quartic and trilinear interactions between the Higgs and the inflaton. We conclude that there exists a favorable range of the couplings within which the Higgs field is stabilized during both inflation and preheating epochs.
Postinflationary vacuum instability and Higgs-inflaton couplings
Enqvist, Kari; Lebedev, Oleg; Rusak, Stanislav; Zatta, Marco
2016-01-01
The Higgs-inflaton coupling plays an important role in the Higgs field dynamics in the early Universe. Even a tiny coupling generated at loop level can have a dramatic effect on the fate of the electroweak vacuum. Such Higgs-inflaton interaction is present both at the trilinear and quartic levels in realistic reheating models. In this work, we examine the Higgs dynamics during the preheating epoch, focusing on the effects of the parametric and tachyonic resonances. We use lattice simulations and other numerical tools in our studies. We find that the resonances can induce large fluctuations of the Higgs field which destabilize the electroweak vacuum. Our considerations thus provide an upper bound on quartic and trilinear interactions between the Higgs and the inflaton. We conclude that there exists a favourable range of the couplings within which the Higgs field is stabilized during both inflation and preheating epochs.
Postinflationary vacuum instability and Higgs-inflaton couplings
Enqvist, Kari; Karčiauskas, Mindaugas; Lebedev, Oleg; Rusak, Stanislav; Zatta, Marco
2016-11-01
The Higgs-inflaton coupling plays an important role in the Higgs field dynamics in the early Universe. Even a tiny coupling generated at loop level can have a dramatic effect on the fate of the electroweak vacuum. Such Higgs-inflaton interaction is present both at the trilinear and quartic levels in realistic reheating models. In this work, we examine the Higgs dynamics during the preheating epoch, focusing on the effects of the parametric and tachyonic resonances. We use lattice simulations and other numerical tools in our studies. We find that the resonances can induce large fluctuations of the Higgs field which destabilize the electroweak vacuum. Our considerations thus provide an upper bound on quartic and trilinear interactions between the Higgs and the inflaton. We conclude that there exists a favorable range of the couplings within which the Higgs field is stabilized during both inflation and preheating epochs.
Beyond standard model Higgs boson searches in the ATLAS and CMS experiments
Mariotti, Chiara
2013-01-01
Searches for a Higgs boson in models beyond the Standard Model at the ATLAS and CMS experiments at the Large Hadron Collider are discussed. No sign of new physics is present in the data collected at 7 and 8 TeV proton center of mass energies. Limits on model parameters are set. Future studies at higher energy are presented.
The Higgs boson mass and SUSY spectra in 10D SYM theory with magnetized extra dimensions
Directory of Open Access Journals (Sweden)
Hiroyuki Abe
2014-11-01
Full Text Available We study the Higgs boson mass and the spectrum of supersymmetric (SUSY particles in the well-motivated particle physics model derived from a ten-dimensional supersymmetric Yang–Mills theory compactified on three factorizable tori with magnetic fluxes. This model was proposed in a previous work, where the flavor structures of the standard model including the realistic Yukawa hierarchies are obtained from non-hierarchical input parameters on the magnetized background. Assuming moduli- and anomaly-mediated contributions dominate the soft SUSY breaking terms, we study the precise SUSY spectra and analyze the Higgs boson mass in this mode, which are compared with the latest experimental data.
Energy Technology Data Exchange (ETDEWEB)
Dedes, Georgios
2008-04-22
In this thesis, the discovery potential of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN for the heavy neutral Higgs bosons H/A of theMinimal Supersymmetric extension of the Standard Model of particle physics (MSSM) in the decay channels H/A{yields}{tau}{sup +}{tau}{sup -}{yields}e/{mu}+X and H/A{yields}{mu}{sup +}{mu}{sup -} has been studied. The ATLAS detector is designed to study the full spectrum of the physics phenomena occuring in the proton-proton collisions at 14 TeV center-of-mass energy and to provide answers to the question of the origin of particle masses and of electroweak symmetry breaking. For the studies, the ATLAS muon spectrometer plays an important role. The spectrometer allows for a precise muon momentum measurement independently of other ATLAS subdetectors. The performance of the muon spectrometer depends strongly on the performance of the muon tracking detectors, the Monitored Drift Tube Chambers (MDT). Computer programs have been developed in order to test and verify the ATLAS muon spectrometer simulation, an essential ingredient for data analysis. In addition, dedicated programs for the monitoring of the quality of the data collected by the muon spectrometer have been developed and tested with data from cosmic ray muons. High-quality cosmic ray muon data have been used for the calibration of the MDT-chambers. A new calibration method, called analytical autocalibration, has been tested. The proposed method achieved the required accuracy of 20 {mu}m in the determination of the space-to-drift-time relationship of the drift tubes of the MDT chambers with only 2000 muon tracks per chamber. Reliable muon detector simulation and calibration are essential for the study of the MSSM Higgs boson decays H/A{yields}{tau}{sup +}{tau}{sup -}{yields}e/{mu}+X and H/A{yields}{mu}{sup +}{mu}{sup -} and of the corresponding background processes. The signal selection and background rejection requirements have been optimized for maximum signal
Energy Technology Data Exchange (ETDEWEB)
Potamianos, Karolos Jozef [Purdue Univ., West Lafayette, IN (United States)
2011-12-01
We study rare processes of the standard model of particle physics (SM) in events with missing transverse energy E_{T}, no leptons, and two or three jets, of which at least one is identified as originating from a $b$-quark (E_{T}+b-jets signature). We present a search for the SM Higgs boson produced in association with a $W$ or $Z$ boson when the Higgs decays into \\bbbar. We consider the scenario where $Z \\to \
CP breaking in $S(3)$ flavoured Higgs model
Barradas-Guevara, E; Rodríguez-Jáuregui, E
2015-01-01
We analyze the Higgs sector of the minimal $S(3)$-invariant extension of the Standard Model including CP violation arising from the spontaneous breaking of the electroweak symmetry. This extended Higgs sector includes three $SU(2)$ doublets Higgs fields with complex vev's provide an interesting scenario to analyze the Higgs masses spectrum, trilinear self-couplings and CP violation. We present how the spontaneous electroweak symmetry breaking coming from three $S(3)$ Higgs fields gives an interesting scenario with nine physical Higgs and three Goldstone bosons when spontaneous CP violation arises from the Higgs field $S(3)$ singlet $H_S$. Furthermore, numerical analysis of the Higgs masses and trilinear self-couplings is presented, particularly we find a physical solution for the scenario in which spontaneous CPB is provided by the single field $H_S$. The scalar Higgs $H_4^0$ is identified whose mass is 125 GeV and $\\lambda_{H_{4}^0 H_{4}^0 H_{4}^0} \\sim \\lambda_{h^0 h^0 h^0}^{SM}$ in good agreement with the ...
The Higgs Working Group: Summary report
Energy Technology Data Exchange (ETDEWEB)
D. Cavalli et al.
2004-03-18
In this working group we have investigated the prospects for Higgs boson searches at the Tevatron and LHC and, in particular, the potential of these colliders to determine the Higgs properties once these particles have been found. The analyses were done in the framework of the Standard Model (SM) and its supersymmetric extensions as the minimal (MSSM) and next-to-minimal (NMSSM) supersymmetric extensions. The work for the discovery potential of the LHC mainly concentrated on the difficult regions of previous analyses as those which are plagued by invisible Higgs decays and Higgs decays into supersymmetric particles. Moreover, the additional signatures provided by the weak vector-boson fusion process (WBF) have been addressed and found to confirm the results of previous analyses. A major experimental effort has been put onto charged Higgs boson analyses. The final outcome was a significant improvement of the discovery potential at the Tevatron and LHC than previous analyses suggested. For an accurate determination of Higgs boson couplings, the theoretical predictions for the signal and background processes have to be improved. A lot of progress has been made during and after this workshop for the gluon-fusion gg {yields} H + (0, 1, 2jets) and the associated t{bar t}H production process. A thorough study of the present theoretical uncertainties of signal and background processes has been initialized, culminating in a list of open theoretical problems. A problem of major experimental interest is the proper treatment of processes involving bottom quark densities, which is crucial for some important signal and background processes. Further theoretical improvements have been achieved for the MSSM Higgs boson masses and Higgs bosons in the NMSSM. This report summarizes our work. The first part deals with theoretical developments for the signal and background processes. The second part gives an overview of the present status of Higgs boson searches at the Tevatron. The
Search for Di-Higgs Production with the ATLAS Detector
Varol, Tulin; The ATLAS collaboration
2016-01-01
An enhanced production of two Higgs bosons would be a clear sign of beyond Standard Model physics. A search is performed for resonant and non-resonant excess production, including several decay channels of the two Higgs bosons. The analysis uses about 10 fb$^{-1}$ of $pp$ collisions at $\\sqrt{s}$ = 13 TeV.
Making sense of studying physics
Ingerman, A; Ingerman, Ake; Booth, Shirley
2004-01-01
With an investigation into how students in a physics Master of science program make sense of their whole first year study experience in one of the years following a programme reform, we try to offer insights and advice to consider when involved in similar changes. We conclude and argue that by trying to support the students' in making sense of their studying in terms of physics and empowering them in their understanding of the nature of physics and their study situation, both the potential for productive, meaningful and positive learning of physics as something which is relevant in the students life, and the way in which the students analyse and make sense of things they encounter, both physically and academically, are advanced.
Physics studies in Europe; a comparative study
Steenstrup, S; dalle Rose, LFD; Jones, WG; Tugulea, L; van Steenwijk, FJ
What are the differences and similarities between physics studies at different universities across Europe (here the definition of Europe is broad)? How much does a student have to work to obtain a degree in physics? Questions like those prompted EUPEN (European Physics Education Network) to make a
Falkowski, Adam; Urbano, Alfredo
2013-01-01
We update the experimental constraints on the parameters of the Higgs effective Lagrangian. We combine the most recent LHC Higgs data in all available search channels with electroweak precision observables from SLC, LEP-1, LEP-2, and the Tevatron. Overall, the data are well consistent with the 126 GeV particle being the Standard Model Higgs boson, apart from the slight excess in the diphoton channel. The Higgs coupling to the W and Z mass relative to the Standard Model one is constrained in the range [0.97,1.07] at 95% confidence level. Higher-order Higgs couplings to electroweak gauge bosons are also well constrained by a combination of LHC Higgs data and electroweak precision tests.
Effective field theory analysis of Higgs naturalness
Energy Technology Data Exchange (ETDEWEB)
Bar-Shalom, Shaouly [Technion-Israel Inst. of Tech., Haifa (Israel); Soni, Amarjit [Brookhaven National Lab. (BNL), Upton, NY (United States); Wudka, Jose [Univ. of California, Riverside, CA (United States)
2015-07-20
Assuming the presence of physics beyond the Standard Model ( SM) with a characteristic scale M ~ O (10) TeV, we investigate the naturalness of the Higgs sector at scales below M using an effective field theory (EFT) approach. We obtain the leading 1 -loop EFT contributions to the Higgs mass with a Wilsonian-like hard cutoff, and determine t he constraints on the corresponding operator coefficients for these effects to alleviate the little hierarchy problem up to the scale of the effective action Λ < M , a condition we denote by “EFT-naturalness”. We also determine the types of physics that can lead to EFT-naturalness and show that these types of new physics are best probed in vector-boson and multiple-Higgs production. The current experimental constraints on these coefficients are also discussed.
Unveiling the Higgs mechanism to students
Organtini, Giovanni
2012-01-01
In this paper we give the outline of a lecture given to undergraduate students aiming at understanding why physicists are so much interested in the Higgs boson. The lecture has been conceived for students not yet familiar with advanced physics and is suitable for several disciplines, other than physics. The Higgs mechanism is introduced by semi-classical arguments mimicking the 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 in two parts: the first, suitable even to high--school students, shows how the mass of a particle results as a dynamical effect due to the interaction between a massless particle and a field (as in the Higgs mechanism). The audience of the second part, much more technical, consists mainly of teachers and university students of disciplines other than physics.
Search for the standard model Higgs boson with the ATLAS detector
Orestano, D
2013-01-01
This document presents a brief overview of some of the experimental techniques employed by the ATLAS experiment at the CERN Large Hadron Collider in the search for the Higgs boson predicted by the standard model of particle physics. The data and the statistical analyses which allowed in July 2012, only few days before this presentation at the Marcel Grossman Meeting, to firmly establish the observation of a new particle, are described. The additional studies needed to check the consistency between the newly discovered particle and the Higgs boson are also discussed.
Calmet, Xavier; Kuntz, Iberê
2016-05-01
In this paper we point out that Starobinsky inflation could be induced by quantum effects due to a large non-minimal coupling of the Higgs boson to the Ricci scalar. The Higgs Starobinsky mechanism provides a solution to issues attached to large Higgs field values in the early universe which in a metastable universe would not be a viable option. We verify explicitly that these large quantum corrections do not destabilize Starobinsky's potential.
Calmet, Xavier
2016-01-01
In this paper we point out that Starobinky inflation could be induced by quantum effects due to a large non-minimal coupling of the Higgs boson to the Ricci scalar. The Higgs Starobinsky mechanism provides a solution to issues attached to large Higgs field values in the early universe which in a metastable universe would not be a viable option. We verify explicitly that these large quantum corrections do not destabilize Starobinsky's potential.
Energy Technology Data Exchange (ETDEWEB)
Calmet, Xavier; Kuntz, Ibere [University of Sussex, Physics and Astronomy, Brighton (United Kingdom)
2016-05-15
In this paper we point out that Starobinsky inflation could be induced by quantum effects due to a large non-minimal coupling of the Higgs boson to the Ricci scalar. The Higgs Starobinsky mechanism provides a solution to issues attached to large Higgs field values in the early universe which in a metastable universe would not be a viable option. We verify explicitly that these large quantum corrections do not destabilize Starobinsky's potential. (orig.)
Cross section and Higgs mass measurement with Higgsstrahlung at the CEPC
Chen, Zhen-Xing; Yang, Ying; Ruan, Man-Qi; Wang, Da-Yong; Li, Gang; Jin, Shan; Ban, Yong
2017-02-01
The Circular Electron Positron Collider (CEPC) is a future Higgs factory proposed by the Chinese high energy physics community. It will operate at a center-of-mass energy of 240–250 GeV. The CEPC will accumulate an integrated luminosity of 5 ab‑1 over ten years of operation, producing one million Higgs bosons via the Higgsstrahlung and vector boson fusion processes. This sample allows a percent or even sub-percent level determination of the Higgs boson couplings. With GEANT4-based full simulation and a dedicated fast simulation tool, we have evaluated the statistical precisions of the Higgstrahlung cross section σ ZH and the Higgs mass m H measurement at the CEPC in the Z → μ+μ‑ channel. The statistical precision of σ ZH (m H) measurement could reach 0.97% (6.9 MeV) in the model-independent analysis which uses only the information from Z boson decays. For the standard model Higgs boson, the m H precision could be improved to 5.4 MeV by including the information from Higgs decays. The impact of the TPC size on these measurements is investigated. In addition, we studied the prospect of measuring the Higgs boson decaying into invisible final states at the CEPC. With the Standard Model ZH production rate, the upper limit of could reach 1.2% at 95% confidence level. Supported by the Joint Funds of the NSFC (U1232105) and CAS Hundred Talent Program (Y3515540U1)
Baryogenesis via Elementary Goldstone Higgs Relaxation
Gertov, Helene; Pearce, Lauren; Yang, Louis
2016-01-01
We extend the relaxation mechanism to the Elementary Goldstone Higgs frame- work. 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 flat scalar potential directions along which the relaxation mechanism can be implemented. This fact translates into wider regions of applicability of the relaxation mechanism when compared to the Standard Model Higgs case. Our results show that, if the electroweak scale is not fundamental but radiatively generated, it is possible to generate the observed matter-antimatter asymmetry via the relaxation mechanism.
Extending the limits of Higgs effective theory
Biekötter, Anke; Brehmer, Johann; Plehn, Tilman
2016-09-01
Based on a vector triplet model, we study a possible failure of dimension-6 operators in describing LHC Higgs kinematics. First, we illustrate that including dimension-6 contributions squared can significantly improve the agreement between the full model and the dimension-6 approximation, both in associated Higgs production and in weak-boson-fusion Higgs production. Second, we test how a simplified model with an additional heavy scalar could improve the agreement in critical LHC observables. In weak boson fusion, we find an improvement for virtuality related observables at large energies, but at the cost of sizeable deviations in interference patterns and angular correlations.
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 ...
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 H...... 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....
Boosting the charged Higgs search prospects using jet substructure at the LHC
Li, Jinmian; Sharma, Pankaj; Williams, Anthony G
2016-01-01
Charged Higgs bosons are predicted in variety of theoretically well-motivated new physics models with extended Higgs sectors. In this study, we focus on a type-II two Higgs doublet model (2HDM-II) and consider a heavy charged Higgs with its mass ranging from 500 GeV to 1 TeV as dictated by the $b\\to s\\gamma$ constraints which render $M_{H^\\pm}>480$ GeV. We study the dominant production mode $H^\\pm t$ associated production with $H^\\pm \\to W^\\pm A$ being the dominant decay channel when the pseudoscalar $A$ is considerably lighter. For such a heavy charged Higgs, both the decay products $W^\\pm$ and $A$ are relatively boosted. In such a scenario, we apply the jet substructure analysis of tagging the fat pseudoscalar and $W$ jets in order to eliminate the standard model background efficiently. We perform a detailed detector simulation for the signal and background processes at the 14 TeV LHC. We introduce various kinematical cuts to determine the signal significance for a number of benchmark points with charged Hi...
Radiative corrections to the Triple Higgs Coupling in the Inert Higgs Doublet Model
Arhrib, Abdesslam; 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 produ...
Radiative corrections to the triple Higgs coupling in the inert Higgs doublet model
Arhrib, Abdesslam; Benbrik, Rachid; El Falaki, Jaouad; Jueid, Adil
2015-12-01
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, hW W 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.
V.Ciulli
2011-01-01
The main programme of the Physics Week held between 16th and 20th May was a series of topology-oriented workshops on di-leptons, di-photons, inclusive W, and all-hadronic final states. The goal of these workshops was to reach a common understanding for the set of objects (ID, cleaning...), the handling of pile-up, calibration, efficiency and purity determination, as well as to revisit critical common issues such as the trigger. Di-lepton workshop Most analysis groups use a di-lepton trigger or a combination of single and di-lepton triggers in 2011. Some groups need to collect leptons with as low PT as possible with strong isolation and identification requirements as for Higgs into WW at low mass, others with intermediate PT values as in Drell-Yan studies, or high PT as in the Exotica group. Electron and muon reconstruction, identification and isolation, was extensively described in the workshop. For electrons, VBTF selection cuts for low PT and HEEP cuts for high PT were discussed, as well as more complex d...
A phenomenological study on the production of Higgs bosons in the cSMCS model at the LHC
Darvishi, Neda
2016-01-01
In the present work, we intend to predict the production rates of the Higgs bosons in the simplest extension of the Standard Model (SM) by a neutral complex singlet (cSMCS). This model has an additional source of CP violation and provides strong enough first-order electroweak phase transition to generate the baryon asymmetry of universe (BAU). The scalar spectrum of the cSMCS includes three neutral Higgs particles with the lightest one considered to be the 125 GeV Higgs boson found at LHC. The SM-like Higgs boson comes mostly from the SM-like SU(2) doublet, with a small correction from the singlet. To predict the production rates of the Higgs bosons, we use a conventional effective LO QCD framework and the unintegrated parton distribution functions (UPDF) of Kimber-Martin-Ryskin (KMR). We first compute the SM Higgs production cross-section and compare the results to the existing theoretical calculations from different frameworks as well as the experimental data from the CMS and ATLAS collaborations. It is sho...
Top quark, W-boson and light Higgs
Energy Technology Data Exchange (ETDEWEB)
Parke, S.
1997-10-01
The top quark, the W-boson and the Higg boson form an interesting triptych of elementary particles. In the Standard Model knowing the mass of two of these particles, usually the top quark and W-boson, we can predict the mass of the third, the Higgs boson. Therefore in this proceedings I will primarily cover the following topics, top quark physics, W-boson mass and the light Higgs boson at the proton-antiproton collider at Fermilab, the Tevatron. Other hadron collider topics to be cover in this conference include B-physics, QCD, Electroweak Physics, and Supersymmetry.
Chasco, Matthew Ervin
The Standard Model of particle physics is a theory describing the fundamental interactions and properties of subatomic particles. A key feature is its ability to explain particle mass through the Higgs mechanism, and a by-product of this mechanism is the Higgs boson. The discovery of the Higgs boson, in 2012 at CERN, completed the Standard Model particle zoo, but observed phenomena, like dark matter, remain unexplained. The analyses presented explore proton-proton collison events resulting in a Z boson plus missing transverse energy (MET). The motivation for this is to investigate two processes: Standard Model (SM) ZZ production, and beyond Standard Model (BSM) ZH production, in particular the ZZ to 2l2nu and ZH to 2l + H(inv) channels. The place-holder H(inv) is for all Higgs boson decay modes resulting in undetected "invisible" particles, which may branch to new physics, like dark matter particles. The data used are from Run 1 (2011--2012) of CMS, where proton-proton collisions at 7 TeV and 8 TeV were delivered by the LHC. The Compact Muon Solenoid (CMS) is a general-purpose detector located along the Large Hadron Collider (LHC), which is a particle accelerator at CERN in Geneva, Switzerland. To extract these signals containing real MET from background containing fake mismeasured MET, a new "reduced MET" variable is constructed and optimized. This assists in the measurement of the ZZ production cross section. The results of the exclusive ZZ to 2l2nu cross section measurement are 201+82/-69 fb and 264+81/-64 fb from the 7 and 8 TeV portions of Run 1 data, respectively. Bayesian unfolding is used to measure a cross section of 224+68/-70 fb from the 8 TeV data. These results both agree with next-to-leading order predictions from the Standard Model. The differential cross section as a function of transverse momentum of the Z boson is also measured from unfolding, for the purpose of providing a way to compare data to new theories. To distinguish ZH to 2l + H(inv) from
Net tightens round the Higgs boson
Energy Technology Data Exchange (ETDEWEB)
Burrows, P. [Particle and Nuclear Physics Laboratory, University of Oxford, Oxford (United Kingdom)
1999-09-01
Results presented at the International Europhysics Conference on High Energy Physics in mid-July provide strong hints that the Higgs boson, one of the holy grails of particle physics, is lurking just around the corner. Over 500 physicists gathered in Tampere, Finland, armed with the latest data and hot on the trail of this elusive particle, the interactions of which are thought to be responsible for giving particles their mass. The Higgs boson is the only unobserved piece in the jigsaw puzzle of elementary particles in the Standard Model. And it now appears to be within tantalizing reach of experiments that will take place over the next few years. (UK)
Higgs Stability and the 750 GeV Diphoton Excess
Salvio, Alberto
2016-01-01
We study the implications of a possible unstable particle with mass $M_X<$ TeV for the Higgs stability, naturalness and inflation. We pay particular attention to the case $M_X\\approx$ 750 GeV, suggested by recent results of ATLAS and CMS on diphoton final states, and work within the minimal model: we add to the Standard Model field content a pseudoscalar and a vector-like charged quark. This can stabilize the electroweak vacuum without invoking new physics at very high energies, which would give an unnaturally large contribution to the Higgs mass. We also show that inflation can be obtained via a UV modification of General Relativity.
García, Isabel García; March-Russell, John
2015-01-01
Dark matter (DM) without a matter asymmetry is studied in the context of Twin Higgs (TH) theories in which the LHC naturalness problem is addressed. These possess a twin sector related to the Standard Model (SM) by a (broken) $\\mathbb{Z}_2$ symmetry, and interacting with the SM via a specific Higgs portal. We focus on the minimal realisation of the TH mechanism, the Fraternal Twin Higgs, with only a single generation of twin quarks and leptons, and $SU(3)'\\times SU(2)'$ gauge group. We show that a variety of natural twin-WIMP DM candidates are present (directly linked to the weak scale by naturalness), the simplest and most attractive being the $\\tau^\\prime$ lepton with a mass $m_{\\tau^\\prime} > m_{\\rm Higgs}/2$, although spin-1 $W^{\\prime\\pm}$ DM and multicomponent DM are also possible (twin baryons are strongly disfavoured by tuning). We consider in detail the dynamics of the possibly (meta)stable glueballs in the twin sector, the nature of the twin QCD phase transition, and possible new contributions to th...
Gaycken, Goetz; The ATLAS collaboration
2015-01-01
The wealth of data collected during the LHC Run-1 allowed many SM parameters to be measured and, most notably, lead to the discovery of the Higgs boson. This talk will summarise the most important ATLAS and CMS Run-1 results concerning the SM, including measurements of the properties of the discovered Higgs boson, assumed to be the predicted SM particle. The second part of the talk will focus on ATLAS, and present the improvements of the detector and its performance following the LS1 shutdown. The talk will finish with the first ATLAS Run-2 results at sqrt(s)=13TeV.
Search for new resonances involving Higgs, W or Z boson at CMS
Rappoccio, Salvatore
2016-01-01
Beyond the standard model theories like composite Higgs models predict resonances with large branching fractions in a Higgs boson and a vector boson with negligible branching fractions to light fermions. We present an overview of searches for new physics containing a Higgs boson and a W or Z boson in the final state, using proton-proton collision data collected with the CMS detector at the CERN LHC. For high-mass resonances decaying to intermediate bosons, the large boost for hadronic decays gives rise to one single merged jet, which can be identified through a study of its substructure consistent with the presence of two quarks, enhancing the sensitivity due to the large branching ratios for hadronic decays. B-quark identification algorithms are used in addition to identify the hadronic H decays.
Testing the Higgs Sector of the Minimal Supersymmetric Standard Model at Large Hadron Colliders
Kunszt, Zoltán
1992-01-01
We study the Higgs sector of the Minimal Supersymmetric Standard Model, in the context of proton-proton collisions at LHC and SSC energies. We assume a relatively heavy supersymmetric particle spectrum, and include recent results on one-loop radiative corrections to Higgs-boson masses and couplings. We begin by discussing present and future constraints from the LEP experiments. We then compute branching ratios and total widths for the neutral ($h,H,A$) and charged ($H^\\pm$) Higgs particles. We present total cross-sections and event rates for the important discovery channels at the LHC and SSC. Promising physics signatures are given by $h \\to \\gamma \\gamma$, $H \\to \\gamma \\gamma$ or $Z^* Z^*$ or $\\tau^+ \\tau^-$, $A \\to \\tau^+ \\tau^-$, and $t \\to b H^+$ followed by $H^+ \\to \\tau^+ \
Higgs-gluon coupling in warped extra dimensional models with brane kinetic terms
Dey, Ujjal Kumar; Ray, Tirtha Sankar
2016-01-01
Warped models with the Higgs confined to the weak brane and the gauge and matter fields accessing the AdS5 bulk provide a viable setting to address the gauge hierarchy problem. Brane kinetic terms for the bulk fields are known to ease some of the tensions of these models with precision electroweak observables and flavor constraints. We study the loop-driven Higgs coupling to the gluons that are relevant to the Higgs program at the LHC, in this scenario. We demonstrate a partial cancellation in the contribution of the fermionic Kaluza-Klein (KK) towers within such framework relatively independent of the 5D parameters. The entire dependence of this coupling on the new physics arises from the mixing between the Standard Model states and the KK excitations. We find that the present precision in measurement of these couplings can lead to a constraint on the KK scale up to 1.2 TeV at 95% confidence level.
Higgs self-coupling measurements at a 100 TeV hadron collider
Energy Technology Data Exchange (ETDEWEB)
Barr, Alan J. [Denys Wilkinson Building, Oxford (United Kingdom); Dolan, Matthew J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Englert, Christoph [Univ. of Glasgow, Glasgow (United Kingdom); Ferreira de Lima, Enoque Danilo [Univ. of Glasgow, Glasgow (United Kingdom); Durham Univ. (United Kingdom); Spannowsky, Michael [Durham Univ. (United Kingdom)
2015-02-03
An important physics goal of a possible next-generation high-energy hadron collider will be precision characterisation of the Higgs sector and electroweak symmetry breaking. A crucial part of understanding the nature of electroweak symmetry breaking is measuring the Higgs self-interactions. We study dihiggs production in proton-proton collisions at 100 TeV centre of mass energy in order to estimate the sensitivity such a machine would have to variations in the trilinear Higgs coupling around the Standard Model expectation. We focus on the bb¯γγ final state, including possible enhancements in sensitivity by exploiting dihiggs recoils against a hard jet. In conclusion, we find that it should be possible to measure the trilinear self-coupling with 40% accuracy given 3/ab and 12% with 30/ab of data.
Direct and indirect signals of natural composite Higgs models
Niehoff, Christoph; Straub, David M
2015-01-01
We present a comprehensive numerical analysis of a four-dimensional model with the Higgs as a composite pseudo-Nambu-Goldstone boson that features a calculable Higgs potential and protective custodial and flavour symmetries to reduce electroweak fine-tuning. We employ a novel numerical technique that allows us for the first time to study constraints from radiative electroweak symmetry breaking, Higgs physics, electroweak precision tests, flavour physics, and direct LHC bounds on fermion and vector boson resonances in a single framework. We consider four different flavour symmetries in the composite sector, one of which we show to not be viable anymore in view of strong precision constraints. In the other cases, all constraints can be passed with a sub-percent electroweak fine-tuning. The models can explain the excesses recently observed in $WW$, $WZ$, $Wh$ and $\\ell^+\\ell^-$ resonance searches by ATLAS and CMS and the anomalies in angular observables and branching ratios of rare semi-leptonic $B$ decays obser...
Anatomy of the Higgs fits: A first guide to statistical treatments of the theoretical uncertainties
Directory of Open Access Journals (Sweden)
Sylvain Fichet
2016-04-01
Full Text Available The studies of the Higgs boson couplings based on the recent and upcoming LHC data open up a new window on physics beyond the Standard Model. In this paper, we propose a statistical guide to the consistent treatment of the theoretical uncertainties entering the Higgs rate fits. Both the Bayesian and frequentist approaches are systematically analysed in a unified formalism. We present analytical expressions for the marginal likelihoods, useful to implement simultaneously the experimental and theoretical uncertainties. We review the various origins of the theoretical errors (QCD, EFT, PDF, production mode contamination…. All these individual uncertainties are thoroughly combined with the help of moment-based considerations. The theoretical correlations among Higgs detection channels appear to affect the location and size of the best-fit regions in the space of Higgs couplings. We discuss the recurrent question of the shape of the prior distributions for the individual theoretical errors and find that a nearly Gaussian prior arises from the error combinations. We also develop the bias approach, which is an alternative to marginalisation providing more conservative results. The statistical framework to apply the bias principle is introduced and two realisations of the bias are proposed. Finally, depending on the statistical treatment, the Standard Model prediction for the Higgs signal strengths is found to lie within either the 68% or 95% confidence level region obtained from the latest analyses of the 7 and 8 TeV LHC datasets.
The Higgs Boson at LHC and the Vacuum Stability of the Standard Model
Rojas, E A Reyes
2015-01-01
The main aim of this work is to study the conditions of absolute vacuum stability within the Standard Model (SM) by the knowledge of the behaviour of the Higgs quartic coupling up to high energy scales and using the new data on the Higgs mass given by ATLAS and CMS as an input parameter. The Higgs mass value observed by ATLAS and CMS leads to a negative value of the quartic coupling, making metastable the vacuum of the Standard Model, as it is seen by the renormalization group improved (RGI) effective potential. The stability status of SM crucially depends upon the precise values of the top and Higgs masses, a more precision determination of those masses and related uncertainties can modify drastically our conclusions about the SM stability properties. For this reason, we have computed the vacuum bubbles and the Higgs tadpole diagrams, at two-loop level of accuracy, in a renormalization scheme proposed by A. Sirlin and R. Zucchini, where the input parameters are obtained in terms of physical observables relat...
Anatomy of the Higgs fits: A first guide to statistical treatments of the theoretical uncertainties
Fichet, Sylvain; Moreau, Grégory
2016-04-01
The studies of the Higgs boson couplings based on the recent and upcoming LHC data open up a new window on physics beyond the Standard Model. In this paper, we propose a statistical guide to the consistent treatment of the theoretical uncertainties entering the Higgs rate fits. Both the Bayesian and frequentist approaches are systematically analysed in a unified formalism. We present analytical expressions for the marginal likelihoods, useful to implement simultaneously the experimental and theoretical uncertainties. We review the various origins of the theoretical errors (QCD, EFT, PDF, production mode contamination…). All these individual uncertainties are thoroughly combined with the help of moment-based considerations. The theoretical correlations among Higgs detection channels appear to affect the location and size of the best-fit regions in the space of Higgs couplings. We discuss the recurrent question of the shape of the prior distributions for the individual theoretical errors and find that a nearly Gaussian prior arises from the error combinations. We also develop the bias approach, which is an alternative to marginalisation providing more conservative results. The statistical framework to apply the bias principle is introduced and two realisations of the bias are proposed. Finally, depending on the statistical treatment, the Standard Model prediction for the Higgs signal strengths is found to lie within either the 68% or 95% confidence level region obtained from the latest analyses of the 7 and 8 TeV LHC datasets.