DOCSLIB.ORG

Diphoton Excess at 750 Gev: Gluon–Gluon Fusion Or Quark–Antiquark Annihilation?

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Diphoton Excess at 750 Gev: Gluon–Gluon Fusion Or Quark–Antiquark Annihilation? Diphoton excess at 750 GeV: gluon–gluon fusion or quark–antiquark annihilation? The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Gao, Jun, Hao Zhang, and Hua Xing Zhu. “Diphoton Excess at 750 GeV: Gluon–gluon Fusion or Quark–antiquark Annihilation?” The European Physical Journal C 76.6 (2016): n. pag. As Published http://dx.doi.org/10.1140/epjc/s10052-016-4200-z Publisher Springer Berlin Heidelberg Version Final published version Citable link http://hdl.handle.net/1721.1/103629 Terms of Use Creative Commons Attribution Detailed Terms http://creativecommons.org/licenses/by/4.0/ Eur. Phys. J. C (2016) 76:348 DOI 10.1140/epjc/s10052-016-4200-z Regular Article - Theoretical Physics Diphoton excess at 750 GeV: gluon–gluon fusion or quark–antiquark annihilation? Jun Gao1,a, Hao Zhang2,b, Hua Xing Zhu3,c 1 High Energy Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA 2 Department of Physics, University of California, Santa Barbara, Santa Barbara, CA 93106, USA 3 Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA Received: 19 May 2016 / Accepted: 10 June 2016 © The Author(s) 2016. This article is published with open access at Springerlink.com Abstract Recently, ATLAS and CMS collaborations 19,26–30,32–34,38,41–45,48–57,59,63,65–69,71,72,75– reported an excess in the measurement of diphoton events, 80,83–87,89,90,93–109,115–128,130–133,136,139–141]. which can be explained by a new resonance with a mass While the models proposed vary significantly, there are some around 750 GeV. In this work, we explored the possibility common features shared by most of them. Due to the quan- of identifying if the hypothetical new resonance is produced tum number of photon pair, most of the proposals suggest through gluon–gluon fusion or quark–antiquark annihilation, that the excess is either due to gluon–gluon fusion or quark– or tagging the beam. Three different observables for beam antiquark annihilation. Different production mechanisms tagging, namely the rapidity and transverse-momentum dis- can lead to very different UV models. Knowing the actual tribution of the diphoton, and one tagged bottom-jet cross production mechanism responsible for the potential excess section, are proposed. Combining the information gained is of great importance for understanding the underlying from these observables, a clear distinction of the production theory. Unfortunately, very little can be said from the current mechanism for the diphoton resonance is promising. data, except some considerations based on the consistency of experimental data from the LHC Run 1 and Run 2. In this work, we shall study the following problem: if 1 Introduction the diphoton excess persists in future data, and the existence of a new resonance is established, is it possible to distin- Very recently, both ATLAS and CMS collaborations pre- guish different production mechanisms with enough amount sented new results from LHC Run 2. Although most of the of data? One can compare this question with the more fre- measurements can still be fit in the Standard Model (SM) quently asked question, namely, how to tell whether an ener- framework nicely, some intriguing excesses are reported. getic hadronic jet in the final state is due to a quark or a Of particular interest is the diphoton excess around 750 gluon produced from hard scattering. This is also known GeV seen by both collaborations. The ATLAS collaboration as the quark and gluon jet tagging problem; see e.g. Refs. reported an excess above the standard model (SM) dipho- [31,91,92,114].1 One can view the question of differentiat- ton background with a local (global) significance of 3.9 (2.3) ing the gg fusion and qq¯ annihilation mechanism as a final- σ [3]. The CMS collaboration, with a little less integrated state-to-initial-state crossing of the quark and gluon jet tag- luminosity, also reported an excess at 760 GeV with a local ging problem. For this reason we will call it the quark and (global) significance of 2.6 (a little less than 1.2) σ [2]. gluon beam tagging problem in this work, or beam tagging Though further data is required to establish the exis- for short. While our current work in the beam tagging prob- tence of a new resonance or other beyond the SM (BSM) lem was motivated by the diphoton excess, we believe that mechanism responsible for the diphoton excess, significant our results will be useful even if the excess disappear after theoretical efforts have been made to explain the possible more data is accumulated, because a bump might eventually diphoton excess in various BSM scenarios [4–9,11–13,15– show up at a different place and/or in a different channel. a e-mail: [email protected] 1 A somewhat related discussion has also been made in the literature b e-mail: [email protected] of the color content of BSM resonance production [14,138], and the c e-mail: [email protected] tagging of initial-state radiation [112]. 123 348 Page 2 of 11 Eur. Phys. J. C (2016) 76:348 An important feature of the beam tagging problem is that There could also be effective operators with a pseudo scalar. most of the QCD radiations from the initial-state partons are But their long distance behavior is in-distinguishable from in the forward direction, and therefore are hard to make use the scalar case. Also the scalar has to couple to photon in of. This is contrasted with final-state jet tagging, in which the order to be able to decay to diphoton. But that is irrelevant information of QCD radiations in the jet play crucial role in to most of our discussion. identifying the partonic origin of the jet. This feature makes Thanks to QCD factorization, the hadronic production the beam tagging problem difficult. Based on the consider- cross section for S can be written as ation of general properties of initial-state QCD radiations, 1 (i) dx (i) σ = τ (τ/ ) ¯ ( ) + ( ↔ ¯) σˆ , we explore different observables which are useful for the 0 fi/N1 x fi/N x i i 0 τ x 2 beam tagging problem. First of all, we consider the rapid- (2) ity distribution of the diphoton system. It is well known from Drell–Yan production that for the qq¯ initial state, contribution τ = 2/ 2 where MS ECM. The operator in Eq. (1) leads to the from valence quark and sea quark can have different shape in following partonic cross section to the scalar production: rapidity distribution. Using this information, we find that it is possible to distinguish the valence-quark scattering from 2 (g) π αs sea-quark or gluon scattering. Second, we consider the trans- σˆ = , 0 ( 2 − ) π 16 Nc 1 3 g verse momentum (QT) distribution of the diphoton system. π v 2 It is well known that the QT distribution of a color neutral σˆ (q) = . 0 (3) system exhibits a Sudakov peak at low QT due to initial-state 2Nc q MS QCD radiation. Interestingly, the strength of initial-state radi- ation differs for quark or gluon induced hard scattering and 2.1 Rapidity distribution leads to substantial difference in the position of the Sudakov peak. Using this information, it is possible to distinguish It is well known that for W and Z boson production in the SM, light-quark scattering from bottom-quark or gluon scatter- contributions from different partonic channels have different ing. Lastly, to further differentiate bottom-quark induced or shapes in rapidity distribution of the boson. Valence-quark gluon induced scattering, we consider tagging a b-quark jet contributions have a double shoulder structure while the sea- in the final state. quark contributions peak in the central region due to differ- The paper is organized as follows: In Sect. 2.1 we study ent slopes of the parton distribution functions (PDFs) with the rapidity distribution of the diphoton system, and pro- respect to Bjorken x. The results are similar for a resonance pose using centrality ratio, defined as ratio of cross section of 750 GeV produced at 13 TeV LHC. One way to quantify in central rapidity region and the total cross section, to dis- the shape of rapidity distribution is to use the centrality ratio, criminate production mechanism due to valence-quark scat- which is defined as ratio of cross sections in central rapidity tering from sea-quark or gluon scattering. In Sect. 2.2 we region |y| < ycut and the total cross sections. In Fig. 1 we study the transverse-momentum distribution of the diphoton show the centrality ratio as a function of ycut for a 750 GeV system, and propose the ratio of cumulative cross section resonance produced through different parton combinations in two different transverse-momentum bins to discriminate at leading order (LO). The hatched bands show the corre- light-quark scattering from bottom-quark or gluon scatter- sponding 68 % confidence level (C.L.) PDF uncertainties ing. In Sect. 2.3, we study b-tagged cross section to further as calculated according to the PDF4LHC recommendation discriminate bottom-quark scattering from gluon scattering. [39], which are small especially for the valence-quark con- We conclude in Sect. 3. tributions. The ratios approach one when ycut approaches the endpoint of the rapidity distribution ∼2.8. As expected the valence-quark contributions have smaller values for the ratio than the ones from gluon or bottom quarks. The ratios are 2 Three methods for the beam tagging problem very close for gluon and bottom-quark or other sea-quark contributions, since the sea-quark PDFs are mostly driven We consider the following effective operators with an addi- by the gluon through DGLAP evolution.
Load more

Recommended publications
  • LHC 750 Gev Diphoton Excess in a Radiative Seesaw Model Arxiv
    CTPU-15-29 KIAS-P15067 UT-HET-110 LHC 750 GeV Diphoton excess in a radiative seesaw model Shinya Kanemura, a Kenji Nishiwaki, b Hiroshi Okada, c Yuta Orikasa, d Seong Chan Park, e Ryoutaro Watanabe f a Department of Physics, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan b;d;e School of Physics, Korea Institute for Advanced Study, Seoul 02455, Republic of Korea c Physics Division, National Center for Theoretical Sciences, National Tsing-Hua University, Hsinchu 30013, Taiwan d Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea e Department of Physics and IPAP, Yonsei University, Seoul 03722, Republic of Korea f Center for Theoretical Physics of the Universe, Institute for Basic Science (IBS), Daejeon, 34051, Republic of Korea 26 October 2019 Abstract We investigate a possibility for explaining the recently announced 750 GeV diphoton excess by the ATLAS and the CMS experiments at the CERN LHC in a model with multiple doubly charged particles, which was originally suggested for explaining tiny neutrino masses through a three-loop effect in a natural way. The enhanced radiatively generated effective coupling of a new singlet scalar arXiv:1512.09048v2 [hep-ph] 16 Oct 2016 S with diphoton with multiple charged particles in the loop enlarges the production rate of S in pp S + X via photon fusion process and also the decay width Γ(S γγ) even without assuming a ! ! tree level production mechanism. We provide detailed analysis on the cases with or without allowing the mixing between S and the standard model Higgs doublet.
    [Show full text]
  • The 750 Gev Diphoton Excess at the LHC and Dark Matter Constraints
    Available online at www.sciencedirect.com ScienceDirect Nuclear Physics B 909 (2016) 43–64 www.elsevier.com/locate/nuclphysb The 750 GeV diphoton excess at the LHC and dark matter constraints ∗ Xiao-Jun Bi a, Qian-Fei Xiang a, Peng-Fei Yin a, , Zhao-Huan Yu b a Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China b ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, The University of Melbourne, Victoria 3010, Australia Received 30 March 2016; accepted 26 April 2016 Available online 29 April 2016 Editor: Hong-Jian He Abstract The recent reported 750 GeV diphoton excess at the 13 TeV LHC is explained in the framework of effective field theory assuming the diphoton resonance is a scalar (pseudoscalar) particle. It is found that the large production rate and the broad width of this resonance are hard to be simultaneously explained if only visible final states are considered. Therefore an invisible decay channel to dark matter (DM) is strongly favored by the diphoton resonance with a broad width, given a large coupling of the new scalar to DM. We set constraints on the parameter space in this scenario using the results from LHC Run 1, DM relic density, and DM direct and indirect detection experiments. We find that the DM searches can exclude a large portion of the parameter regions accounting for the diphoton excess with a broad width. © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
    [Show full text]
  • 750 Gev Diphotons from a D3-Brane
    750 GeV Diphotons from a D3-brane Jonathan J. Heckman1;2;3∗ 1Department of Physics, University of North Carolina, Chapel Hill, NC 27599, USA 2Department of Physics, Columbia University, New York, NY 10027, USA 3CUNY Graduate Center, Initiative for the Theoretical Sciences, New York, NY 10016, USA Abstract Motivated by the recently reported diphoton excess at 750 GeV observed by both CMS and ATLAS, we study string-based particle physics models which can accommodate this signal. Quite remarkably, although Grand Unified Theories in F-theory tend to impose tight restrictions on candidate extra sectors, the case of a probe D3-brane near an E-type Yukawa point naturally leads to a class of strongly coupled models capable of accommodating the observed signature. In these models, the visible sector is realized by intersecting 7-branes, and the 750 GeV resonance is a scalar modulus associated with motion of the D3-brane in the direction transverse to the Standard Model 7-branes. Integrating out heavy 3 − 7 arXiv:1512.06773v3 [hep-ph] 27 Apr 2016 string messenger states leads to dimension five operators for gluon fusion production and diphoton decays. Due to the unified structure of interactions, these models also predict that there should be additional decay channels to ZZ and Zγ. We also comment on models with distorted unification, where both the production mechanism and decay channels can differ. December 2015 ∗e-mail: [email protected] 1 Introduction Recently, the LHC experiments CMS and ATLAS have both announced tentative evidence for a diphoton excess with a resonant mass near 750 GeV [1,2].
    [Show full text]
  • The 750 Gev Diphoton Excess As a First Light on Supersymmetry Breaking
    Physics Letters B 759 (2016) 159–165 Contents lists available at ScienceDirect Physics Letters B www.elsevier.com/locate/physletb The 750 GeV diphoton excess as a first light on supersymmetry breaking ∗ J.A. Casas a, J.R. Espinosa b,c, , J.M. Moreno a a Instituto de Física Teórica, IFT-UAM/CSIC, Nicolás Cabrera 13, UAM Cantoblanco, 28049 Madrid, Spain b Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology (BIST), Campus UAB, E-08193, Bellaterra (Barcelona), Spain c ICREA, Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain a r t i c l e i n f o a b s t r a c t Article history: One of the most exciting explanations advanced for the recent diphoton excess found by ATLAS and Received 15 February 2016 CMS is in terms of sgoldstino decays: a signal of low-energy supersymmetry-breaking scenarios. The Received in revised form 27 April 2016 sgoldstino, a scalar, couples directly to gluons and photons, with strength related to gaugino masses, that Accepted 21 May 2016 can be of the right magnitude to explain the excess. However, fitting the suggested resonance width, Available online 25 May 2016 45 GeV, is not so easy. In this paper we explore efficient possibilities to enhance the sgoldstino Editor: G.F. Giudice width, via the decay into two Higgses, two Higgsinos and through mixing between the sgoldstino and the Higgs boson. In addition, we present an alternative and more efficient mechanism to generate a mass splitting between the scalar and pseudoscalar components of the sgoldstino, which has been suggested as an interesting alternative explanation to the apparent width of the resonance.
    [Show full text]
  • Dorigo Cms Results.Pdf
    HEP-Chile 2016, Valparaiso Jan 7th New Results of the CMS Experiment Tommaso Dorigo INFN, Sezione di Padova Contents The CMS experiment and the 2015 run – The LHC and CMS – The Run 1 legacy – Preparations for Run 2 Standard model physics results – Toward the Higgs rediscovery – W, Z, top, B physics measurements New Physics searches – SUSY searches – Resonances, resonances, and more resonances – One much discussed candidate for 2016 Concluding remarks The CMS Collaboration 1700 physicists, 700 students, 950 engineers/technicians, 180 institutions from 43 countries 10k CPU cores, 2M lines of code The CMS Detector Muon system: Drift tubes (170k wires), RPC, Cathode Strip Ch.(200k wires) Silicon tracker: 66M pixel channels 9.6M strips, 210 m2 ECAL: 76k PbWO4 crystals HCAL: 15k scint/brass ch. The CMS Detector • CMS: A Compact Muon Solenoid • Actually much more than that: – a redundant, all-silicon tracking (210 m2) – a 4-Tesla solenoid for high-resolution momentum measurements – a Lead-tungstate crystal calorimeter for high- resolution EM shower measurements – hermetic hadron An all-purpose electronic eye for calorimetry subatomic physics – redundant muon coverage up to |η|<2.4 What to remember from Run 1 In Run 1 (2011-2012) the CMS experiment has published 447 articles based on data from 7- and 8- TeV pp collisions and heavy ion collisions This has resulted in the discovery of the Higgs boson, a new baryon, a few Y states, as well as in scores of other results, and notably the extension of lower limits on the mass of new particles and rate
    [Show full text]
  • What Is the Γγ Resonance at 750 Gev? Arxiv:1512.04933V3 [Hep-Ph
    CERN-PH-TH/2015-302 IFUP-TH/2015 What is the γγ resonance at 750 GeV? Roberto Franceschinia, Gian F. Giudicea, Jernej F. Kamenika;b;c, Matthew McCullougha, Alex Pomarola;d, Riccardo Rattazzie, Michele Redif , Francesco Rivaa, Alessandro Strumiaa;g, Riccardo Torree a CERN, Theory Division, Geneva, Switzerland b JoˇzefStefan Institute, Jamova 39, 1000 Ljubljana, Slovenia c Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia d Dept. de F´ısica and IFAE-BIST, Universitat Aut`onomade Barcelona, 08193 Bellaterra, Barcelona, Spain e Institut de Th´eoriedes Ph´enom`enesPhysiques, EPFL, CH{1015 Lausanne, Switzerland f INFN, Sezione di Firenze, Via G. Sansone, 1, I-50019 Sesto Fiorentino, Italy g Dipartimento di Fisica dell’Universit`adi Pisa and INFN, Italy Abstract Run 2 LHC data show hints of a new resonance in the diphoton distri- bution at an invariant mass of 750 GeV. We analyse the data in terms of a new boson, extracting information on its properties and exploring theoretical interpretations. Scenarios covered include a narrow reso- arXiv:1512.04933v3 [hep-ph] 19 Feb 2016 nance and, as preliminary indications suggest, a wider resonance. If the width indications persist, the new particle is likely to belong to a strongly-interacting sector. We also show how compatibility between Run 1 and Run 2 data is improved by postulating the existence of an additional heavy particle, whose decays are possibly related to dark matter. Contents 1 Introduction2 2 Phenomenological analysis3 2.1 An s-channel resonance coupled to gluons and photons . .4 2.2 An s-channel resonance coupled to b quarks and photons .
    [Show full text]
  • Interpreting 750 Gev Diphoton Excess in Plain NMSSM
    Lawrence Berkeley National Laboratory Recent Work Title Interpreting 750 GeV diphoton excess in plain NMSSM Permalink https://escholarship.org/uc/item/6f1412ch Journal Physics Letters B, 760 ISSN 0370-2693 Authors Badziak, Marcin Olechowski, Marek Pokorski, Stefan et al. Publication Date 2016-09-01 DOI 10.1016/j.physletb.2016.06.057 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Physics Letters B 760 (2016) 228–235 Contents lists available at ScienceDirect Physics Letters B www.elsevier.com/locate/physletb Interpreting 750 GeV diphoton excess in plain NMSSM ∗ Marcin Badziak a,b, Marek Olechowski a, Stefan Pokorski a, Kazuki Sakurai c, a Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, PL-02-093 Warsaw, Poland b Berkeley Center for Theoretical Physics, Department of Physics, and Theoretical Physics Group, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA c Institute for Particle Physics Phenomenology, Department of Physics, University of Durham, Science Laboratories, South Road, Durham, DH1 3LE, UK a r t i c l e i n f o a b s t r a c t Article history: NMSSM has enough ingredients to explain the diphoton excess at 750 GeV: singlet-like (pseudo) scalar Received 23 March 2016 (a) s and higgsinos as heavy vector-like fermions. We consider the production of the 750 GeV singlet-like Received in revised form 21 June 2016 pseudo scalar a from a decay of the doublet-like pseudo scalar A, and the subsequent decay of a into Accepted 24 June 2016 two photons via higgsino loop.
    [Show full text]
  • Characterising the 750 Gev Diphoton Excess Arxiv:1603.03421V2 [Hep
    LPSC16048 Characterising the 750 GeV diphoton excess J´er´emyBernon,a Andreas Goudelis,b Sabine Kraml,a Kentarou Mawatari,a;c Dipan Senguptaa aLaboratoire de Physique Subatomique et de Cosmologie, Universit´eGrenoble-Alpes, CNRS/IN2P3, 53 Avenue des Martyrs, F-38026 Grenoble, France bInstitute of High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, 1050 Vienna, Austria cTheoretische Natuurkunde and IIHE/ELEM, Vrije Universiteit Brussel, and Interna- tional Solvay Institutes, Pleinlaan 2, B-1050 Brussels, Belgium E-mail: [email protected], [email protected], [email protected], [email protected], [email protected] Abstract: We study kinematic distributions that may help characterise the re- cently observed excess in diphoton events at 750 GeV at the LHC Run 2. Several scenarios are considered, including spin-0 and spin-2 750 GeV resonances that de- cay directly into photon pairs as well as heavier parent resonances that undergo three-body or cascade decays. We find that combinations of the distributions of the diphoton system and the leading photon can distinguish the topology and mass spec- tra of the different scenarios, while patterns of QCD radiation can help differentiate the production mechanisms. Moreover, missing energy is a powerful discriminator for the heavy parent scenarios if they involve (effectively) invisible particles. While our study concentrates on the current excess at 750 GeV, the analysis is general and arXiv:1603.03421v2 [hep-ph] 20 May 2016 can also be
    [Show full text]
  • 750 Gev Diphoton Excess at CERN LHC from a Dark Sector Assisted
    Journal of Cosmology and Astroparticle Physics OPEN ACCESS Related content - Asymmetric dark matter models and the 750 GeV diphoton excess at CERN LHC from a LHC diphoton excess Mads T. Frandsen and Ian M. Shoemaker dark sector assisted scalar decay - Re-opening dark matter windows compatible with a diphoton excess Giorgio Arcadi, Pradipta Ghosh, Yann To cite this article: Subhaditya Bhattacharya et al JCAP06(2016)010 Mambrini et al. - Isospin-violating dark matter from a double portal Geneviève Bélanger, Andreas Goudelis, Jong-Chul Park et al. View the article online for updates and enhancements. Recent citations - Models of the LHC diphoton excesses valid up to the Planck scale Yuta Hamada et al - A flippon related singlet at the LHC II Tianjun Li et al - Re-opening dark matter windows compatible with a diphoton excess Giorgio Arcadi et al This content was downloaded from IP address 131.169.4.70 on 04/12/2017 at 22:54 ournal of Cosmology and Astroparticle Physics JAn IOP and SISSA journal 750 GeV diphoton excess at CERN LHC from a dark sector assisted scalar JCAP06(2016)010 decay Subhaditya Bhattacharya,a Sudhanwa Patra,b Nirakar Sahooc and Narendra Sahuc aDepartment of Physics, Indian Institute of Technology Guwahati, North Guwahati, Assam 781039, India bCenter of Excellence in Theoretical and Mathematical Sciences, Siksha `O' Anusandhan University, Bhubaneswar 751030, India cDepartment of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Medak 502 285, Telengana, India E-mail: [email protected], [email protected], [email protected], [email protected] Received February 2, 2016 Revised April 22, 2016 Accepted May 26, 2016 Published June 6, 2016 Abstract.
    [Show full text]
  • The 750 Gev Diphoton Resonance As an Sgoldstino: a Reappraisal Arxiv
    The 750 GeV diphoton resonance as an sgoldstino: a reappraisal Debjyoti Bardhan a;1, Pritibhajan Byakti b;2, Diptimoy Ghosh c;3, Tarun Sharma c;4 a Department of Theoretical Physics, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400005, India. b Center for High Energy Physics, Indian Institute of Science, Bangalore 560012, India. c Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100, Israel. Abstract Among the various explanations of the possible 750 GeV diphoton resonance, the possibility of it being an sgoldstino is an attractive one, as it is related to the spontaneous breaking of global supersymmetry. We discuss this possibil- ity in this paper and point out the various theoretical issues associated with it. In particular, we indicate the difficulties of this explanation in realistic models of gauge mediated supersymmetry breaking. arXiv:1603.05251v3 [hep-ph] 11 Jun 2016 1 [email protected] 2 [email protected] 3 [email protected] 4 [email protected] Contents 1 Introduction 2 2 Generalities 4 2.1 Theoretical framework . .4 2.2 Explaining the excess . .6 3 Ordinary gauge mediation 7 3.1 Possibility of larger λ ............................. 11 3.2 Estimate of the mass of .......................... 12 S 4 Extra Ordinary Gauge Mediation 13 5 Way out? 15 5.1 D-term contribution to the gaugino mass . 16 5.2 Metastable SUSY breaking . 17 5.3 Quark anti-quark initiated production of the sgoldstino . 18 6 Conclusion 21 A Calculation of the partial decay widths 22 A.1 φ γ γ ...................................
    [Show full text]
  • JCAP06(2016)010 C Hysics P Le Ic T Ar Nirakar Sahoo B Doi:10.1088/1475-7516/2016/06/010 Strop a Sudhanwa Patra, A
    ournal of Cosmology and Astroparticle Physics JAn IOP and SISSA journal 750 GeV diphoton excess at CERN LHC from a dark sector assisted scalar JCAP06(2016)010 decay Subhaditya Bhattacharya,a Sudhanwa Patra,b Nirakar Sahooc and Narendra Sahuc aDepartment of Physics, Indian Institute of Technology Guwahati, North Guwahati, Assam 781039, India bCenter of Excellence in Theoretical and Mathematical Sciences, Siksha `O' Anusandhan University, Bhubaneswar 751030, India cDepartment of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Medak 502 285, Telengana, India E-mail: [email protected], [email protected], [email protected], [email protected] Received February 2, 2016 Revised April 22, 2016 Accepted May 26, 2016 Published June 6, 2016 Abstract. We present a simple extension of the Standard Model (SM) to explain the recent diphoton excess, reported by CMS and ATLAS at CERN LHC. The SM is extended by a dark sector including a vector-like lepton doublet and a singlet of zero electromagnetic charge, which are odd under a Z2 symmetry. The charged particle of the vector-like lepton doublet assist the additional scalar, different from SM Higgs, to decay to di-photons of invariant mass around 750 GeV and thus explaining the excess observed at LHC. The admixture of neutral component of the vector-like lepton doublet and singlet constitute the dark matter of the Universe. We show the relevant parameter space for correct relic density and direct detection of dark matter. Keywords: dark matter theory, neutrino properties, particle physics - cosmology connection ArXiv ePrint: 1601.01569 Article funded by SCOAP3.
    [Show full text]
  • Re-Examining the Significance of the 750 Gev Diphoton Excess at ATLAS Bradley J
    Re-examining the significance of the 750 GeV diphoton excess at ATLAS Bradley J. Kavanagh To cite this version: Bradley J. Kavanagh. Re-examining the significance of the 750 GeV diphoton excess at ATLAS. 2016. cea-01360364 HAL Id: cea-01360364 https://hal-cea.archives-ouvertes.fr/cea-01360364 Preprint submitted on 5 Sep 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Re-examining the significance of the 750 GeV diphoton excess at ATLAS Bradley J. Kavanagh∗ LPTHE, CNRS, UMR 7589, 4 Place Jussieu, F-75252, Paris, France and Institut de physique th´eorique,Universit´eParis Saclay, CNRS, CEA, F-91191 Gif-sur-Yvette, France The excess seen in the diphoton channel at around 750 GeV by both ATLAS and CMS has caused a great deal of excitement in the particle physics community. However, there has recently been much discussion about uncertainties in the significance of the peak seen by the ATLAS experiment. In this note, we aim to estimate this significance using a range of possible parametrisations for the smooth diphoton background. We obtain a local significance close to that reported by ATLAS and further demonstrate that the significance of the excess is not substantially reduced when more complicated background functions are considered.
    [Show full text]