The Pragmatic Approach to the Gauge Hierarchy Problem
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SUSY After LHC8: a Brief Overview
EPJ Web of Conferences 60, 18001 (2013) DOI: 10.1051/epjconf/20136018001 © Owned by the authors, published by EDP Sciences, 2013 SUSY after LHC8: a brief overview Enrico Bertuzzo1;a 1Institut de Physique Théorique, CEA-Saclay, F-91191 Gif-sur-Yvette Cedex, France. Abstract. With the 8 TeV LHC run now concluded, the first consequences of the experimental results on the supersymmetric parameter space can be drawn. On one hand, the negative direct searches place more and more stringent bounds on the mass of supersymmetric particles; on the other hand, the discovery of a 125 GeV Higgs boson points toward a quite heavy spectrum for the squarks of the third generation, at least in the minimal supersymmetric model. In this note I will briefly recap how this constitutes a problem for the naturalness of supersymmetric models, as well as the current experimental situation. Moreover, I will point out possible non minimal models in which the naturalness issue can be at least soften. 1 Introduction: the Hierarchy problem, much larger, as expected from the previous considerations. once more This is the well known Hierarchy Problem. Inspection of Eqs. (1-2) shows possible ways to evade After the discovery of a scalar particle with mass around the problem: we can either assume a very low cut-off ΛNP, 125 GeV and properties closely resembling those of the or we can try to cancel all the large contributions adding Standard Model (SM) Higgs boson [1, 2], the long stand- new particles with suitably chosen couplings. The first ing problem of the stability of fundamental scalar masses way has been pursued in the last years in models of Com- has become more acute than ever. -
Hunting for Supersymmetry and Dark Matter at the Electroweak Scale
HUNTING FOR SUPERSYMMETRY AND DARK MATTER AT THE ELECTROWEAK SCALE By SEBASTIAN MACALUSO A dissertation submitted to the School of Graduate Studies Rutgers, The State University of New Jersey In partial fulfillment of the requirements For the degree of Doctor of Philosophy Graduate Program in Physics and Astronomy Written under the direction of David Shih And approved by New Brunswick, New Jersey October, 2018 ABSTRACT OF THE DISSERTATION Hunting for Supersymmetry and Dark Matter at the Electroweak Scale By SEBASTIAN MACALUSO Dissertation Director: Professor David Shih In this thesis, we study models of physics beyond the Standard Model (SM) at the electroweak scale and their phenomenology, motivated by naturalness and the nature of dark matter. Moreover, we introduce analyses and techniques relevant in searches at the Large Hadron Collider (LHC). We start by applying computer vision with deep learning to build a boosted top jets tagger at the LHC that outperforms previous state-of-the-art classifiers by a factor of ∼ 2{3 or more in background rejection, over a wide range of tagging efficiencies. Next, we define a cut and count based analysis for supersymmetric top quarks at LHC Run II capable of probing the line in the mass plane where there is just enough phase space to produce an on-shell top quark from the stop decay. We also implement a comprehensive reinterpretation of the 13 TeV ATLAS and CMS searches with the first ∼ 15 fb−1 of data and derive constraints on various simplified models of natural supersymmetry. We discuss how these constraints affect the fine-tuning of the electroweak scale. -
SUSY Phenomenology Circa 2020
SUSY phenomenology circa 2020 Howie Baer (baer at ou dot edu), Pheno2020 University of Oklahoma May 4, 2020 m(higgs) finetuned in SM for cuto↵ m(weak) • 120 cosmological constant 10− expected • 10 ✓¯ 10− (strong CP/QCD) • ⇠ ``The appearance of fine- tuning in a scientific theory is like a cry of distress from nature, complaining that something needs to be better explained’’ virtual Pitt PACC meeting 1 SUSY phenomenology of 20th century mediation: gravity (mSUGRA/CMSSM), gauge, anomaly • naturalness: sparticles 100 GeV scale • ⇠ dark matter: WIMP/neutralino via stau-co, A-funnel or FP • 2 21 century experiments meet 20th century theory m = 125.18 0.16 GeV • h ± m > 2.1 TeV • g˜ m˜ > 1.1 TeV • t1 no sign of WIMPs (via DD) • These values/limits lead to impression that Weak Scale SUSY largely excluded except for few remote regions of p-space 3 21 century physics 1. discrete R-symmetries: mu-problem,p-decay, R-parity, gravity-safe global PQ symmetry 2. naturalness: BG, HS, EW 3. DM: need axion for strong CP, SUSY mu-problem: mainly DFSZ axion plus higgsino-like WIMP 4. string landscape: solves CC problem, role in hierarchy problem? Yes 4 SUSY mu problem: The SUSY preserving mu-parameter is usually tuned within spectrum calculator computer codes and otherwise ignored. But more basically, it should be ~m(Planck), or else in string theory=0 (no arbitrary mass scales) But: phenomenologically, need mu~m(weak)~100-300 GeV (practical naturalness: independent contributions to observables should be of order of or less than the measured value). -
Exploring Supersymmetry and Naturalness in Light of New Experimental Data
Exploring supersymmetry and naturalness in light of new experimental data by Kevin Earl A thesis submitted to the Faculty of Graduate and Postdoctoral Affairs in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physics Department of Physics Carleton University Ottawa-Carleton Institute for Physics Ottawa, Canada August 27, 2019 Copyright ⃝c 2019 Kevin Earl Abstract This thesis investigates extensions of the Standard Model (SM) that are based on either supersymmetry or the Twin Higgs model. New experimental data, primar- ily collected at the Large Hadron Collider (LHC), play an important role in these investigations. Specifically, we examine the following five cases. We first consider Mini-Split models of supersymmetry. These types ofmod- els can be generated by both anomaly and gauge mediation and we examine both cases. LHC searches are used to constrain the relevant parameter spaces, and future prospects at LHC 14 and a 100 TeV proton proton collider are investigated. Next, we study a scenario where Higgsino neutralinos and charginos are pair produced at the LHC and promptly decay due to the baryonic R-parity violating superpotential operator λ00U cDcDc. More precisely, we examine this phenomenology 00 in the case of a single non-zero λ3jk coupling. By recasting an experimental search, we derive novel constraints on this scenario. We then introduce an R-symmetric model of supersymmetry where the R- symmetry can be identified with baryon number. This allows the operator λ00U cDcDc in the superpotential without breaking baryon number. However, the R-symmetry will be broken by at least anomaly mediation and this reintroduces baryon number violation. -
Supersymmetric Dark Matter Candidates in Light of Constraints from Collider and Astroparticle Observables
THESE` Pour obtenir le grade de DOCTEUR DE L’UNIVERSITE´ DE GRENOBLE Specialit´ e´ : Physique Theorique´ Arretˆ e´ ministeriel´ : 7 aoutˆ 2006 Present´ ee´ par Jonathan DA SILVA These` dirigee´ par Genevieve` BELANGER´ prepar´ ee´ au sein du Laboratoire d’Annecy-le-Vieux de Physique Theorique´ (LAPTh) et de l’Ecole´ Doctorale de Physique de Grenoble Supersymmetric Dark Matter candidates in light of constraints from collider and astroparticle observables These` soutenue publiquement le 3 juillet 2013, devant le jury compose´ de : arXiv:1312.0257v1 [hep-ph] 1 Dec 2013 Dr. Rohini GODBOLE Professeur, CHEP Bangalore, Inde, Presidente´ Dr. Farvah Nazila MAHMOUDI Maˆıtre de Conferences,´ LPC Clermont, Rapporteur Dr. Ulrich ELLWANGER Professeur, LPT Orsay, Rapporteur Dr. Celine´ BŒHM Charge´ de recherche, Durham University, Royaume-Uni, Examinatrice Dr. Anupam MAZUMDAR Professeur, Lancaster University, Royaume-Uni, Examinateur Dr. Genevieve` BELANGER´ Directeur de Recherche, LAPTh, Directeur de these` A meus av´os. Contents Acknowledgements - Remerciements vii List of Figures xi List of Tables xvii List of Abbreviations xix List of Publications xxiii Introduction1 I Status of particle physics and cosmology ... and beyond5 1 From the infinitely small : the Standard Model of particle physics ...7 1.1 Building of the model : gauge sector . .8 1.2 Matter sector . 10 1.2.1 Leptons . 10 1.2.2 Quarks . 12 1.3 The Higgs mechanism . 13 1.4 Full standard picture . 16 1.5 Successes of the SM . 18 1.6 SM issues . 19 1.6.1 Theoretical problems . 19 1.6.2 Experimental discrepancies . 20 1.6.3 Cosmological connexion . 22 2 ... To the infinitely large : the Lambda Cold Dark Matter model 23 2.1 Theoretical framework . -
Two Notions of Naturalness
For almost 40 years, the requirement that models of BSM physics be natural has heavily inuenced model-building in high-energy physics. Porter Williams (University of Pittsburgh) Two notions of naturalness February 28, 2018 1 / 60 The expectation of a natural solution to the hierarchy problem was probably the most popular argument for expecting new particles at the LHC. Porter Williams (University of Pittsburgh) Two notions of naturalness February 28, 2018 2 / 60 The Standard Model reigns supreme. As of today, the LHC has discovered no evidence for SUSY or any other mechanism for naturally stabilizing the weak scale. Porter Williams (University of Pittsburgh) Two notions of naturalness February 28, 2018 4 / 60 As of today, the LHC has discovered no evidence for SUSY or any other mechanism for naturally stabilizing the weak scale. The Standard Model reigns supreme. Porter Williams (University of Pittsburgh) Two notions of naturalness February 28, 2018 4 / 60 This has left many people in the HEP community unsure about how to proceed. Porter Williams (University of Pittsburgh) Two notions of naturalness February 28, 2018 5 / 60 Now What? Aspen 2013 - Higgs Quo Vadis Nathan Seiberg IAS TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AAAAAA AA If neither supersymmetry nor any other sort of natural solution...appears in the data...[t]his would...give theorists a strong incentive to take the ideas of the multiverse more seriously. – Nima Arkani-Hamed (2012) Porter Williams (University of Pittsburgh) Two notions of naturalness February 28, 2018 8 / 60 If the electroweak symmetry breaking scale is anthropically xed, then we can give up the decades long search for a natural solution to the hierarchy problem. -
Cosmological Constant in SUGRA Models with Degenerate Vacua
universe Article Cosmological Constant in SUGRA Models with Degenerate Vacua Colin Froggatt 1, Holger Nielsen 2, Roman Nevzorov 3,* and Anthony Thomas 4 1 School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK; [email protected] 2 The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen, Denmark; [email protected] 3 NRC Kurchatov Institute—ITEP, 117218 Moscow, Russia 4 ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, Department of Physics, The University of Adelaide, Adelaide, SA 5005, Australia; [email protected] * Correspondence: [email protected] Received: 20 September 2019; Accepted: 17 October 2019; Published: 22 October 2019 Abstract: The extrapolation of couplings up to the Planck scale within the standard model (SM) indicates that the Higgs effective potential can have two almost degenerate vacua, which were predicted by the multiple point principle (MPP). The application of the MPP to (N = 1) supergravity (SUGRA) implies that the SUGRA scalar potential of the hidden sector possesses at least two exactly degenerate minima. The first minimum is associated with the physical phase in which we live. In the second supersymmetric (SUSY) Minkowski vacuum, the local SUSY may be broken dynamically, inducing a tiny vacuum energy density. In this paper, we consider the no-scale-inspired SUGRA model in which the MPP conditions are fulfilled without any extra fine-tuning at the tree-level. Assuming that at high energies, the couplings in both phases are identical, one can estimate the dark energy density in these vacua. Using the two-loop renormalization group (RG) equations, we find that the measured value of the cosmological constant can be reproduced if the SUSY breaking scale MS in the physical phase is of the order of 100 TeV. -
A Complete Model of Low-Scale Gauge Mediation
Prepared for submission to JHEP RUNHETC-2012-13 A Complete Model of Low-Scale Gauge Mediation Nathaniel Craig,a;b Simon Knapen,a David Shih,a Yue Zhaoa aDepartment of Physics, Rutgers University Piscataway, NJ 08854 bSchool of Natural Sciences, Institute for Advanced Study Princeton, NJ 08540 Abstract: Recent signs of a Standard Model-like Higgs at 125 GeV point towards large A-terms in the MSSM. This presents special challenges for gauge mediation, which by itself predicts vanishing A- terms at the messenger scale. In this paper, we review the general problems that arise when extending gauge mediation to achieve large A-terms, and the mechanisms that exist to overcome them. Using these mechanisms, we construct weakly-coupled models of low-scale gauge mediation with extended Higgs-messenger couplings that generate large A-terms at the messenger scale and viable µ/Bµ-terms. Our models are simple, economical, and complete realizations of supersymmetry at the weak scale. Keywords: Beyond Standard Model, Supersymmetry arXiv:1206.4086v2 [hep-ph] 19 Dec 2012 Contents 1 Introduction 1 2 Generalities 4 2 2.1 The µ-Bµ and A-mH problems4 2.2 A general mechanism for a solution7 2 2.3 The little A-mH problem7 3 Models 8 3.1 Warmup: an MSSM module for large A-terms8 3.2 The complete NMSSM model for A, µ, and Bµ 10 3.3 Examples 11 4 EWSB and Other Constraints 12 4.1 EWSB in the MSSM with large A-terms 13 4.2 EWSB in the NMSSM 14 4.3 Stop and slepton tachyons 17 4.4 Implications of the constraints 19 5 Spectrum and Phenomenology 19 5.1 Models with 5 + 5¯ messengers 19 5.2 Models with 10 + 10 messengers 22 5.3 Phenomenology 22 6 Conclusions 25 A General Formulas 26 B Physics Above the Messenger Scale 28 1 Introduction The latest results from ATLAS and CMS exclude the Standard Model (SM) Higgs except in the narrow range of mh 122 127 GeV, and show intriguing hints of an excess at mh 125 GeV [1,2]. -
Ten Lectures on the Electroweak Interactions
Ten Lectures on the ElectroWeak Interactions Riccardo Barbieri Scuola Normale Superiore and INFN, Piazza dei Cavalieri 7, I-56126 Pisa, Italy Abstract Elementary particle physics is the quadrant of nature whose laws can be written in a few lines with absolute precision and the greatest empirical adequacy. If this is the case, as I believe it is, it must be possible and is probably useful to introduce the students and the interested readers to the entire subject in a compact way. This is the main aim of these Lectures. Preface Elementary particle physics is the quadrant of nature whose laws can be written in a few lines with absolute precision and the greatest empirical adequacy. If this is the case, as I believe it is, it must be possible and is probably useful to introduce the students and the interested readers to the entire subject in a compact way. This is the main aim of these Lectures. The Standard Model is the reference theory for particle physics, including the fact that one often explicitly refers to Beyond the Standard Model physics. Although maybe practical, I have never liked the distinction between Standard Model and Beyond the Standard Model physics. These lectures are certainly mostly about the Standard Model, minimally extended to include neutrino masses. As such, I avoid discussing explicitly any proposal that goes beyond the Standard Model, none of which has received yet any clear experimental confirmation. Nevertheless most of the Lectures are given with an open eye to a possible evolution of the theory of the ElectroWeak Interactions. -
Neutrino Masses from Tev Scale New Physics -- Tests of Neutrino Masses at the LHC
Neutrino Masses from TeV Scale New Physics -- Tests of Neutrino Masses at the LHC Mu-Chun Chen, University of California at Irvine GGI What’s Nu?, June 26, 2012 Theoretical Challenges (i) Absolute mass scale: Why mν << mu,d,e? • seesaw mechanism: most appealing scenario ⇒ MajoranaSeesaw model has been previously shown [11] to induce a non-unitary leptonic mixing matrix. In this work we will explicitly analyze the issue for the other types of Seesaw • UV completions of Weinberg operators HHLL models. φ φ µ ‣ Type-I seesaw: exchange of singlet fermions φ φ ∆ φ φ Minkowski, 1977; Yanagida, 1979; NR ΣR † Y † Y Glashow, 1979; YN N ∆ YΣ Σ Gell-mann, Ramond, Slansky,1979; NR: SU(3)c x SU(2)w x U(1)Y ~(1,1,0) Mohapatra, Senjanovic, 1979; ! ! ! ! Seesaw model has been previously shown [11] to induce a non-unitary leYpt∆onic mixing matrix. In this work we will explicitly analyze the issue for the ot!her types of See!saw models. Figure 1: The three generic realizations of the Seesaw mechanism, depending on the φ φ ‣ Type-II seesaw: exchange of weak triplet scalar nature of the heavy fields exchanged: SM singlet fermions (type I Seesaw) on the left, µ∆ φ φSM triplet scalars (type II Sφeesaw) and SM tripleφt fermions (type III Seesaw) on the Lazarides, 1980; Mohapatra, Senjanovic, 1980 NR right. ΣR YN† YN ∆ YΣ† YΣ SΔee:s aSU(3)w modce lxh SU(2)as beenw pxr eU(1)viousYl y~(1,3,2)shown [11] to induce a non-unitary leptonic mixing ! ! ! ! matrix. -
Pos(DSU2015)026 Would Likely Be a ) Higgsino ( M 2 > S √ Is Natural
SUSY dark matter, axions, LHC and ILC PoS(DSU2015)026 Howard Baer∗ Dep’t of Physics and Astronomy, University of Oklahoma, Norman, OK, 73019, USA E-mail: [email protected] Guided by the twin pillars of simplicity and naturalness, and upon clarification of the notion of naturalness, we find regions of highly natural SUSY with light higgsinos and highly mixed TeV- scale top squarks and gluinos with mass less than 4 TeV. The gauge hierarchy problem is solved by SUSY and the strong CP and SUSY mu problems are solved by SUSY DFSZ axions. Then the Little Hierarchy with m m3=2 is natural. Ultimately, we expect detection of both a DFSZ axion and a Higgsino-like WIMP. LHC14 can probably eke out SUSY signals in the new same- p sign diboson and jet+soft dilepton channels. The ILC with s > 2m(higgsino) would likely be a Higgsino factory and usher in the era of the superworld. The 11th International Workshop Dark Side of the Universe 2015 14-18 December 2015 Kyoto, Japan ∗Speaker. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). http://pos.sissa.it/ SUSY DM, axions, LHC, ILC Howard Baer 1. Introduction The LHC experiments Atlas and CMS have discovered a very Standard Model (SM)-like Higgs boson[1, 2] with mass mh ' 125 GeV while, at present, no sign of physics from beyond the SM occurs (aside from a slew of anomalies– especially the 750 GeV diphoton mass bump– awaiting confirmation or rejection from larger data sets). -
Naturalness, Wilsonian Renormalization, and “Fundamental Parameters” in Quantum Field Theory
TTK-19-04, ELHC 2018-005 January 2019 Naturalness, Wilsonian Renormalization, and \Fundamental Parameters" in Quantum Field Theory Joshua Rosaler and Robert Harlander Institute for Theoretical Particle Physics and Cosmology, RWTH Aachen University, D-52056 Aachen, Germany Abstract The Higgs naturalness principle served as the basis for the so far failed prediction that signatures of physics beyond the Standard Model (SM) would be discovered at the LHC. One influential formulation of the princi- ple, which prohibits fine tuning of bare Standard Model (SM) parameters, rests on the assumption that a particular set of values for these parame- ters constitute the \fundamental parameters" of the theory, and serve to mathematically define the theory. On the other hand, an old argument by Wetterich suggests that fine tuning of bare parameters merely reflects an arbitrary, inconvenient choice of expansion parameters and that the choice of parameters in an EFT is therefore arbitrary. We argue that these two interpretations of Higgs fine tuning reflect distinct ways of formulat- ing and interpreting effective field theories (EFTs) within the Wilsonian framework: the first takes an EFT to be defined by a single set of physical, fundamental bare parameters, while the second takes a Wilsonian EFT to be defined instead by a whole Wilsonian renormalization group (RG) trajectory, associated with a one-parameter class of physically equivalent parametrizations. From this latter perspective, no single parametrization constitutes the physically correct, fundamental parametrization of the the- ory, and the delicate cancellation between bare Higgs mass and quantum corrections appears as an eliminable artifact of the arbitrary, unphysical reference scale with respect to which the physical amplitudes of the the- ory are parametrized.