Searches for superparticles at the LHC by application of computer simulation

The analys of recent experimental data received from LHC (CMS) restricts the range of MSSM parameters to the new five parameters. Using computer programs SOFTSUSY, SDECAY and PYTHIA the mass spectrum, partial width and production cross sections of superpatners are calculated. In the context of Minim...

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Veröffentlicht in:	Вопросы атомной науки и техники
Datum:	2013
Hauptverfasser:	Obikhod, T.V., Malyuta, Yu.M.
Format:	Artikel
Sprache:	English
Veröffentlicht:	Національний науковий центр «Харківський фізико-технічний інститут» НАН України 2013
Schlagworte:	Ядерная физика и элементарные частицы α
Online Zugang:	https://nasplib.isofts.kiev.ua/handle/123456789/111856
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spelling	Obikhod, T.V. Malyuta, Yu.M. 2017-01-15T11:52:19Z 2017-01-15T11:52:19Z 2013 Searches for superparticles at the LHC by application of computer simulation / T.V. Obikhod, Yu.M. Malyuta // Вопросы атомной науки и техники. — 2013. — № 3. — С. 147-150. — Бібліогр.: 10 назв. — англ. 1562-6016 PACS: 11.25.-w, 12.60.Jv, 02.10.Ws https://nasplib.isofts.kiev.ua/handle/123456789/111856 The analys of recent experimental data received from LHC (CMS) restricts the range of MSSM parameters to the new five parameters. Using computer programs SOFTSUSY, SDECAY and PYTHIA the mass spectrum, partial width and production cross sections of superpatners are calculated. In the context of Minimal Supersymmetric Standard Model histograms of mass distributions for superpartners qR and g are constructed. Аналiз останнiх експериментальних даних, отриманих на LHC, обмежив простiр MSSM параметрiв до нових п’яти параметрiв. Шляхом застосування комп’ютерних програм SOFTSUSY, SDECAY i PYTHIA розраховано маси, ширини розпадiв i перерiзи народження суперчастинок. У контекстi мiнiмальної суперсиметричної стандартної моделi побудованi гiстограми розподiлу мас суперчастинок qR и g. Анализ последних экспериментальных данных, полученных на LHC, ограничил пространство MSSM параметров до новых пяти параметров. Путем применения компьютерных программ SOFTSUSY, SDECAY и PYTHIA посчитаны массы, ширины распадов и сечения рождения суперчастиц. В контексте минимальной суперсимметричной стандартной модели построены гистограммы распределения масс суперчастиц qR и g. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Ядерная физика и элементарные частицы α Searches for superparticles at the LHC by application of computer simulation Пошуки суперчастинок на LHC шляхом застосування комп’ютерного симулювання Поиски суперчастиц на LHC путем применения компьютерного симулирования Article published earlier
institution	Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection	DSpace DC
title	Searches for superparticles at the LHC by application of computer simulation
spellingShingle	Searches for superparticles at the LHC by application of computer simulation Obikhod, T.V. Malyuta, Yu.M. Ядерная физика и элементарные частицы α
title_short	Searches for superparticles at the LHC by application of computer simulation
title_full	Searches for superparticles at the LHC by application of computer simulation
title_fullStr	Searches for superparticles at the LHC by application of computer simulation
title_full_unstemmed	Searches for superparticles at the LHC by application of computer simulation
title_sort	searches for superparticles at the lhc by application of computer simulation
author	Obikhod, T.V. Malyuta, Yu.M.
author_facet	Obikhod, T.V. Malyuta, Yu.M.
topic	Ядерная физика и элементарные частицы α
topic_facet	Ядерная физика и элементарные частицы α
publishDate	2013
language	English
container_title	Вопросы атомной науки и техники
publisher	Національний науковий центр «Харківський фізико-технічний інститут» НАН України
format	Article
title_alt	Пошуки суперчастинок на LHC шляхом застосування комп’ютерного симулювання Поиски суперчастиц на LHC путем применения компьютерного симулирования
description	The analys of recent experimental data received from LHC (CMS) restricts the range of MSSM parameters to the new five parameters. Using computer programs SOFTSUSY, SDECAY and PYTHIA the mass spectrum, partial width and production cross sections of superpatners are calculated. In the context of Minimal Supersymmetric Standard Model histograms of mass distributions for superpartners qR and g are constructed. Аналiз останнiх експериментальних даних, отриманих на LHC, обмежив простiр MSSM параметрiв до нових п’яти параметрiв. Шляхом застосування комп’ютерних програм SOFTSUSY, SDECAY i PYTHIA розраховано маси, ширини розпадiв i перерiзи народження суперчастинок. У контекстi мiнiмальної суперсиметричної стандартної моделi побудованi гiстограми розподiлу мас суперчастинок qR и g. Анализ последних экспериментальных данных, полученных на LHC, ограничил пространство MSSM параметров до новых пяти параметров. Путем применения компьютерных программ SOFTSUSY, SDECAY и PYTHIA посчитаны массы, ширины распадов и сечения рождения суперчастиц. В контексте минимальной суперсимметричной стандартной модели построены гистограммы распределения масс суперчастиц qR и g.
issn	1562-6016
url	https://nasplib.isofts.kiev.ua/handle/123456789/111856
citation_txt	Searches for superparticles at the LHC by application of computer simulation / T.V. Obikhod, Yu.M. Malyuta // Вопросы атомной науки и техники. — 2013. — № 3. — С. 147-150. — Бібліогр.: 10 назв. — англ.
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first_indexed	2025-11-25T12:17:19Z
last_indexed	2025-11-25T12:17:19Z
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fulltext	SEARCHES FOR SUPERPARTICLES AT THE LHC BY APPLICATION OF COMPUTER SIMULATION T.V. Obikhod ∗, Yu.M. Malyuta Institute for Nuclear Research, NAS of Ukraine 03680 Kiev, Ukraine (Received February 6, 2012) The analys of recent experimental data received from LHC (CMS) restricts the range of MSSM parameters to the new five parameters. Using computer programs SOFTSUSY, SDECAY and PYTHIA the mass spectrum, partial width and production cross sections of superpatners are calculated. In the context of Minimal Supersymmetric Standard Model histograms of mass distributions for superpartners q̃R and g̃ are constructed. PACS: 11.25.-w, 12.60.Jv, 02.10.Ws 1. INTRODUCTION The searches for new physics at the LHC moti- vated the necessary tools for building Grand Uni- fication Theory (GUT) models in F-theory [1]. It is known that Minimal Supersymmetric Standard Model (MSSM) [2] through its connection to string theory improves the Standard Model (SM). There are several problems of SM, connected with our experi- mental knowledge and with some theoretical aspects: 1) there is the neutrino mass problem - the SM predicts neutrinos having zero mass, whereas we have experimental evidence for massive neutrinos; 2) SM field theory which include gravity ends up being non-renormalizable without predictions below the Planck scale; 3) SM has 19 free parameters to be determined experimentally; 4) the hierarchy problem; 5) the unification problem. These problems can be decided with the help of MSSM model. In this model each particle, for ex- ample fermion, has its superpartner - boson with ap- propriate masses and couplings. MSSM includes new symmetry called R-parity. This gives us some usefull phenomenological results: • the lightest sparticle, LSP must be stable and than it would be an excellent candidate for dark mat- ter; • the LSP interacts very weakly with matter; • supersymmetric particles are produced in pairs; • all supersymmetric particles are unstable and decay. 2. CATEGORY OF D-BRANES To construct the MSSM model from superstring the- ory we must use the notion of derived category [3]. We will give the short review of the theory of cate- gory. A category L consists of the following data: 1) A class Ob L of objects A,B, C, · · · ; 2) A family of disjoint sets of morphisms Hom(A,B) one for each ordered pair A,B of objects; 3) A family of maps Hom(A, B)×Hom(B, C) → Hom(A,C) , one for each ordered triplet A,B, C of objects. These data obey the axioms: a) If f : A → B, g : B → C, h : C → D, then composition of morphisms is associative, that is, h(gf) = (hg)f ; b) To each object B there exists a morphism 1B : B → B such that 1Bf = f , g1B = g for f : A → B and g : B → C . There are several aspects that are necessary for con- struction the category of D-branes [3]: • D-brane is associated to the locally-free sheaf; • An open string from one D-brane (sheaf E) to another D-brane (sheaf F ) is given by an element of the group Extq(E, F ) ; • the category of D-branes is the derived category of coherent sheaves D(X) ; • If X and Y are mirror Calabi-Yau threefolds then the category D(X) is equivalent to the triangu- lated category TrF(Y ) ; • D-branes on the orbifold C/G and open strings between them are described by the derived category of McKay quiver representations. We consider the derived category of distinguished tri- angles over the abelian category of McKay quivers [?]. Objects of this category are distinguished triangles ∗Corresponding author E-mail address: obikhod@kinr.kiev.ua ISSN 1562-6016. PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY, 2013, N3(85). Series: Nuclear Physics Investigations (60), p.147-150. 147 Fig.1. Triangles (numbers a, b, c and a′, b′, c′ denote orbifold charges [4] characterizing McKay quivers); morphisms of this category are morphisms of distinguished triangles. 3. PARTICLE CONTENT The moduli space of an open superstring [5] has the form Ext0(Q,Q ′ ) = C aa ′ +bb ′ +cc ′ , Ext1(Q,Q ′ ) = C 3ab ′ +3bc ′ +3ca ′ . (1) Substituting in (1) orbifold charges a = b = c = a′ = b′ = c′ = 4 (Fig. 1) and using the Langlands hypothesis [6], we obtain the realization of (1) in terms of SU(5) mul- tiplets 3× (24 + 5H + 5H + 5M + 5M + 10M + 10M ) . This result determines the particle content of the MSSM. 4. SUPERPOTENTIAL The gauge invariant MSSM superpotential takes the form WSU(5) = λd ij · 5H × 5(i) M × 10(j) M + +λu ij · 5H × 10(i) M × 10(j) M + µ · 5H × 5H , (2) where 5H and 5H are Higgs multiplets, 5(i) M and 10(j) M are multiplets of quark and lepton superpartners, λd ij , λu ij are Yukawa coupling constants and µ is the Higgs mixing parameter. 5. MASS SPECTRUM The analysis of Yukawa coupling constants, based on observational hints and theoretical considerations, al- lows to restrict the parameter space in (2) to five free parameters [7]: M0 = 450 GeV , M1/2 = 425 GeV , A0 = 0 , tanβ = 10 , sgn(µ) = +1 . (3) Using this restricted parameter set it is possible to calculate the mass spectrum of superpartners by application of the computer program SOFTSUSY [8]. This MSSM spectrum is shown in Table 1. Table 1. Mass spectrum of superpartners GeV GeV GeV ũR 974 g̃ 1006 ũL 1000 ν̃e 525 χ̃0 1 174 d̃R 972 ẽR 477 χ̃0 2 327 d̃L 1003 ẽL 531 χ̃0 3 546 c̃R 974 χ̃0 4 562 c̃L 1000 ν̃µ 525 χ̃±1 327 s̃R 972 µ̃R 477 χ̃±2 562 s̃L 1003 µ̃L 531 t̃1 741 h0 114 t̃2 947 ν̃τ 523 A0 749 b̃1 910 τ̃1 471 H0 749 b̃2 968 τ̃2 531 H± 753 6. PARTIAL WIDTHS Using the parameter set (3) it is possible to calcu- late partial widths of superpartners by application of the computer program SDECAY [9]. These partial widths are shown in Tables 2, 3. Table 2. Partial widths of superpartners channel BR channel BR ũR χ̃0 1u 0.993 χ̃0 4u 0.004 χ̃0 2u 0.002 d̃R χ̃0 1d 0.993 χ̃0 4d 0.004 χ̃0 2d 0.002 c̃R χ̃0 1c 0.993 χ̃0 4c 0.004 χ̃0 2c 0.002 s̃R χ̃0 1s 0.993 χ̃0 4s 0.004 χ̃0 2s 0.002 Table 3. Partial widths of superpartners channel BR channel BR g̃ d̃Rd∗ 0.017 b̃1b ∗ 0.119 d̃∗Rd 0.017 b̃∗1b 0.119 ũRu∗ 0.015 b̃2b ∗ 0.021 ũ∗Ru 0.015 b̃∗2b 0.021 s̃Rs∗ 0.017 t̃1t ∗ 0.294 s̃∗Rs 0.017 t̃∗1t 0.294 c̃Rc∗ 0.015 c̃∗Rc 0.015 7. CROSS SECTIONS Using the parameter set (3) it is possible to calculate production cross sections of superpartners by appli- cation of the computer program PYTHIA [10]. These cross sections at center-of-mass energy √ s = 14 TeV are shown in Table 4. 148 Table 4. Cross sections of superpartners channel cross section, pb gg → g̃g̃ σg̃g̃ = 0.323 qg → d̃Rg̃ σd̃Rg̃ = 0.260 qg → ũRg̃ σũRg̃ = 0.489 qq ′ → ũRd̃R σũRd̃R = 0.132 8. RECONSTRUCTION OF MASSES To construct histograms describing mass distribu- tions for superpartners q̃R and g̃ we choose the set of parameters (3). Using this parameter set it is possible to construct histograms of mass distributions for su- perpartners by application of the computer program PYTHIA [10]. This histograms are shown in Fig. 2 and Fig. 3. Fig.2. Histogram of mass distribution for q̃R Fig.3. Histogram of mass distribution for g̃ References 1. C. Beasley, J.J. Heckman and C. Vafa. GUTs and exceptional branes in F-theory-I// arXiv:0802.3391 [hep-th]. 2. H.E. Haber. Introductory low-energy supersym- metry // arXiv: hep-ph/9306207. 3. P.S. Aspinwall. D-branes on Calabi-Yau mani- folds // arXiv: hep-th/0403166. 4. M.R. Douglas, B. Fiol and C. Römelsberger. The spectrum of BPS branes on a noncompact Calabi- Yau // JHEP. 2005, 09, p. 1-57. 5. S. Katz, T. Pantev and E. Sharpe. D-branes, orb- ifolds, and Ext groups // Nucl. Phys. 2003, v. B673, p. 263-300. 6. W. Schmid. Homogeneous complex manifolds and representations of semisimple Lie groups // Proc. Natl. Acad. Sci. USA. 1968, v. 69, p. 56-59. 7. J.J. Heckman and C. Vafa. F-theory, GUTs, and the weak scale // arXiv:0809.1098 [hep-th]. 8. B.C. Allanach. SOFTSUSY2.0: a program for calculating supersymmetric spectra // Comput. Phys. Commun. 2002, v. 143, p. 305-331. 9. M. Muhlleitner, A. Djouadi and Y. Mambrini. SDECAY: a fortran code for the decays of the supersymmetric particles in the MSSM // Com- put. Phys. Commun. 2005, v. 168, p. 46-70. 10. T. Sjöstrand, S. Mrenna and P. Skands. PYTHIA 6.4 Physics and Manual // JHEP. 2006, v. 05, p. 1-26. 149 ПОИСКИ СУПЕРЧАСТИЦ НА LHC ПУТЕМ ПРИМЕНЕНИЯ КОМПЬЮТЕРНОГО СИМУЛИРОВАНИЯ Т.В.Обиход, Ю.М.Малюта Анализ последних экспериментальных данных, полученных на LHC, ограничил пространство MSSM параметров до новых пяти параметров. Путем применения компьютерных программ SOFTSUSY, SDECAY и PYTHIA посчитаны массы, ширины распадов и сечения рождения суперчастиц. В контексте мини- мальной суперсимметричной стандартной модели построены гистограммы распределения масс супер- частиц q̃R и g̃. ПОШУКИ СУПЕРЧАСТИНОК НА LHC ШЛЯХОМ ЗАСТОСУВАННЯ КОМП’ЮТЕРНОГО СИМУЛЮВАННЯ Т.В.Обiход, Ю.М.Малюта Аналiз останнiх експериментальних даних, отриманих на LHC, обмежив простiр MSSM параметрiв до нових п’яти параметрiв. Шляхом застосування комп’ютерних програм SOFTSUSY, SDECAY i PYTHIA розраховано маси, ширини розпадiв i перерiзи народження суперчастинок. У контекстi мiнiмальної су- персиметричної стандартної моделi побудованi гiстограми розподiлу мас суперчастинок q̃R и g̃. 150

Searches for superparticles at the LHC by application of computer simulation

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