اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدMulti-Dimensional mSUGRA Likelihood Maps
40
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We calculate the likelihood map in the full 7 dimensional parameter space of the minimal supersymmetric standard model (MSSM) assuming universal boundary conditions on the supersymmetry breaking terms. Simultaneous variations of m_0, A_0, M_{1/2}, tan beta, m_t, m_b and alpha_s(M_Z) are applied using a Markov chain Monte Carlo algorithm. We use measurements of b -> s gamma, (g-2)_mu and Omega_{DM} h^2 in order to constrain the model. We present likelihood distributions for some of the sparticle masses, for the branching ratio of B_s^0 -> mu^+ mu^- and for m_{stau}-m_{chi_1^0}. An upper limit of 2.10^{-8} on this branching ratio might be achieved at the Tevatron, and would rule out 29% of the currently allowed likelihood. If one allows for non thermal-neutralino components of dark matter, this fraction becomes 35%. The mass ordering allows the important cascade decay squark_L -> chi_2^0 -> slepton_R -> chi_1^0 with a likelihood of 24+/-4%. The stop coannihilation region is highly disfavoured, whereas the light Higgs region is marginally disfavoured.
قيم البحث
اقرأ أيضاً
We perform a likelihood analysis of the constraints from accelerator experiments and astrophysical observations on supersymmetric (SUSY) models with SU(5) boundary conditions on soft SUSY-breaking parameters at the GUT scale. The parameter space of t
he models studied has 7 parameters: a universal gaugino mass $m_{1/2}$, distinct masses for the scalar partners of matter fermions in five- and ten-dimensional representations of SU(5), $m_5$ and $m_{10}$, and for the $mathbf{5}$ and $mathbf{bar 5}$ Higgs representations $m_{H_u}$ and $m_{H_d}$, a universal trilinear soft SUSY-breaking parameter $A_0$, and the ratio of Higgs vevs $tan beta$. In addition to previous constraints from direct sparticle searches, low-energy and flavour observables, we incorporate constraints based on preliminary results from 13 TeV LHC searches for jets + MET events and long-lived particles, as well as the latest PandaX-II and LUX searches for direct Dark Matter detection. In addition to previously-identified mechanisms for bringing the supersymmetric relic density into the range allowed by cosmology, we identify a novel ${tilde u_R}/{tilde c_R} - tilde{chi}^0_1$ coannihilation mechanism that appears in the supersymmetric SU(5) GUT model and discuss the role of ${tilde u_tau}$ coannihilation. We find complementarity between the prospects for direct Dark Matter detection and SUSY searches at the LHC.
We perform a likelihood analysis of the minimal Anomaly-Mediated Supersymmetry Breaking (mAMSB) model using constraints from cosmology and accelerator experiments. We find that a wino-like or a Higgsino-like neutralino LSP, $m_{tilde chi^0_{1}}$, may
provide the cold dark matter (DM) with similar likelihood. The upper limit on the DM density from Planck and other experiments enforces $m_{tilde chi^0_{1}} lesssim 3~TeV$ after the inclusion of Sommerfeld enhancement in its annihilations. If most of the cold DM density is provided by the $tilde chi_0^1$, the measured value of the Higgs mass favours a limited range of $tan beta sim 5$ (or for $mu > 0$, $tan beta sim 45$) but the scalar mass $m_0$ is poorly constrained. In the wino-LSP case, $m_{3/2}$ is constrained to about $900~TeV$ and ${m_{tilde chi^0_{1}}}$ to $2.9pm0.1~TeV$, whereas in the Higgsino-LSP case $m_{3/2}$ has just a lower limit $gtrsim 650TeV$ ($gtrsim 480TeV$) and $m_{tilde chi^0_{1}}$ is constrained to $1.12 ~(1.13) pm0.02~TeV$ in the $mu>0$ ($mu<0$) scenario. In neither case can the anomalous magnetic moment of the muon, ${(g-2)_mu}$, be improved significantly relative to its Standard Model (SM) value, nor do flavour measurements constrain the model significantly, and there are poor prospects for discovering supersymmetric particles at the LHC, {though there} are some prospects for direct DM detection. On the other hand, if the ${m_{tilde chi^0_{1}}}$ contributes only a fraction of the cold DM density, {future LHC $E_T$-based searches for gluinos, squarks and heavier chargino and neutralino states as well as disappearing track searches in the wino-like LSP region will be relevant}, and interference effects enable ${rm BR}(B_{s, d} to mu^+mu^-)$ to agree with the data better than in the SM in the case of wino-like DM with $mu > 0$.
In mSUGRA models the lightest supersymmetric particle (assumed to be the lightest neutralino) provides an excellent cold dark matter (CDM) candidate. The supersymmetric parameter space is significantly reduced, if the limits on the CDM relic density,
obtained from WMAP data, are used. Assuming a vanishing trilinear scalar coupling A0 and fixed values of tan(beta), these limits result in narrow lines of allowed regions in the m0-m12 plane, the so called WMAP strips. In this analysis the trilinear coupling A0 has been varied within +/-4TeV resulting in largely extended areas in the m0-m12 plane which are no longer excluded.
We use MasterCode to perform a frequentist analysis of the constraints on a phenomenological MSSM model with 11 parameters, the pMSSM11, including constraints from ~ 36/fb of LHC data at 13 TeV and PICO, XENON1T and PandaX-II searches for dark matter
scattering, as well as previous accelerator and astrophysical measurements, presenting fits both with and without the $(g-2)_{mu}$ constraint. The pMSSM11 is specified by the following parameters: 3 gaugino masses $M_{1,2,3}$, a common mass for the first-and second-generation squarks $m_{tilde{q}}$ and a distinct third-generation squark mass $m_{tilde{q}_3}$, a common mass for the first-and second-generation sleptons $m_{tilde l}$ and a distinct third-generation slepton mass $m_{tilde tau}$, a common trilinear mixing parameter $A$, the Higgs mixing parameter $mu$, the pseudoscalar Higgs mass $M_A$ and $tanbeta$. In the fit including $(g-2)_{mu}$, a Bino-like $tildechi^0_1$ is preferred, whereas a Higgsino-like $tilde chi^0_1$ is favoured when the $(g-2)_{mu}$ constraint is dropped. We identify the mechanisms that operate in different regions of the pMSSM11 parameter space to bring the relic density of the lightest neutralino, $tildechi^0_1$, into the range indicated by cosmological data. In the fit including $(g-2)_{mu}$, coannihilations with $tilde chi^0_2$ and the Wino-like $tildechi^{pm}_1$ or with nearly-degenerate first- and second-generation sleptons are favoured, whereas coannihilations with the $tilde chi^0_2$ and the Higgsino-like $tildechi^{pm}_1$ or with first- and second-generation squarks may be important when the $(g-2)_{mu}$ constraint is dropped. Prospects remain for discovering strongly-interacting sparticles at the LHC as well as for discovering electroweakly-interacting sparticles at a future linear $e^+ e^-$ collider such as the ILC or CLIC.
We describe a likelihood analysis using MasterCode of variants of the MSSM in which the soft supersymmetry-breaking parameters are assumed to have universal values at some scale $M_{in}$ below the supersymmetric grand unification scale $M_{GUT}$, as
can occur in mirage mediation and other models. In addition to $M_{in}$, such `sub-GUT models have the 4 parameters of the CMSSM, namely a common gaugino mass $m_{1/2}$, a common soft supersymmetry-breaking scalar mass $m_0$, a common trilinear mixing parameter $A$ and the ratio of MSSM Higgs vevs $tanbeta$, assuming that the Higgs mixing parameter $mu > 0$. We take into account constraints on strongly- and electroweakly-interacting sparticles from $sim 36$/fb of LHC data at 13 TeV and the LUX and 2017 PICO, XENON1T and PandaX-II searches for dark matter scattering, in addition to the previous LHC and dark matter constraints as well as full sets of flavour and electroweak constraints. We find a preference for $M_{in} sim 10^5$ to $10^9$ GeV, with $M_{in} sim M_{GUT}$ disfavoured by $Delta chi^2 sim 3$ due to the ${rm BR}(B_{s, d} to mu^+mu^-)$ constraint. The lower limits on strongly-interacting sparticles are largely determined by LHC searches, and similar to those in the CMSSM. We find a preference for the LSP to be a Bino or Higgsino with $tilde{chi^0_1} sim 1$ TeV, with annihilation via heavy Higgs bosons $H/A$ and stop coannihilation, or chargino coannihilation, bringing the cold dark matter density into the cosmological range. We find that spin-independent dark matter scattering is likely to be within reach of the planned LUX-Zeplin and XENONnT experiments. We probe the impact of the $(g-2)_mu$ constraint, finding similar results whether or not it is included.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
