共查询到20条相似文献,搜索用时 31 毫秒
1.
T. Fukuyama A. Ilakovac T. Kikuchi 《The European Physical Journal C - Particles and Fields》2008,56(1):125-146
We consider the leptonic and semileptonic (SL) lepton-flavor violating (LFV) decays of the charged leptons in the minimal
supersymmetric standard model (MSSM) with right-handed neutrinos. The parameters of the MSSM model are determined in the framework
of the minimal supersymmetric SO(10) GUT model assuming the minimal supergravity model of supersymmetry breaking. The free
parameters of the model are constrained adopting the WMAP cold dark matter constraint and adjusting the neutrino oscillation
data. So constrained, the SO(10) GUT model gives a definite prediction for the Dirac-neutrino Yukawa matrix, which induces
all LFV effects in the MSSM model through renormalization group equations of soft SUSY breaking parameters. A very detailed
numerical analysis has been made to define numerically all MSSM parameters necessary for the evaluation of the LFV amplitudes.
The basic LFV amplitudes in MSSM were rederived and improved. The formalism for the evaluation of all SL LFV amplitudes is
given. Numerical results for dominant SL LFV branching ratios, the anomalous magnetic moment of the muon and the ℓ→ℓ’γ branching
ratios are given. 相似文献
2.
We study the neutralino sector of the Minimal Non-minimal Supersymmetric Standard Model (MNSSM) where the μ problem of the Minimal Supersymmetric Standard Model (MSSM) is solved without accompanying problems related with the appearance of domain walls. In the MNSSM as in the MSSM the lightest neutralino can be the absolutely stable lightest supersymmetric particle (LSP) providing a good candidate for the cold dark matter component of the Universe. In contrast with the MSSM the allowed range of the mass of the lightest neutralino in the MNSSM is limited. We establish the theoretical upper bound on the lightest neutralino mass in the framework of this model and obtain an approximate solution for this mass. 相似文献
3.
Francesco Fucito Andrea Lionetto Andrea Mammarella Antonio Racioppi 《The European Physical Journal C - Particles and Fields》2010,69(3-4):455-465
We study a possible dark matter candidate in the framework of a minimal anomalous U(1)′ extension of the MSSM. It turns out that in a suitable decoupling limit the Stückelino, the fermionic degree of freedom of the Stückelberg multiplet, is the lightest supersymmetric particle (LSP). We compute the relic density of this particle including coannihilations with the next to lightest supersymmetric particle (NLSP) and with the next to next to lightest supersymmetric particle (NNLSP), which are assumed to be almost degenerate in mass. This assumption is needed in order to satisfy the stringent limits that the Wilkinson Microwave Anisotropy Probe (WMAP) puts on the relic density. We find that the WMAP constraints can be satisfied by different NLSP and NNLSP configurations as a function of the mass gap with the LSP. These results hold in the parameter space region where the model remains perturbative. 相似文献
4.
A. Arbey M. Battaglia F. Mahmoudi 《The European Physical Journal C - Particles and Fields》2012,72(1):1847
We study the implications of LHC searches on SUSY particle spectra using flat scans of the 19-parameter pMSSM phase space.
We apply constraints from flavour physics, g
μ
−2, dark matter and earlier LEP and Tevatron searches. The sensitivity of the LHC SUSY searches with jets, leptons and missing
energy is assessed by reproducing with fast simulation the recent CMS analyses after validation on benchmark points. We present
results in terms of the fraction of pMSSM points compatible with all the constraints which are excluded by the LHC searches
with 1 fb−1 and 15 fb−1 as a function of the mass of strongly and weakly interacting SUSY particles. We also discuss the suppression of Higgs production
cross sections for the MSSM points not excluded and contrast the region of parameter space tested by the LHC data with the
constraints from dark matter direct detection experiments. 相似文献
5.
M. Battaglia A. De Roeck J. Ellis F. Gianotti K. A. Olive L. Pape 《The European Physical Journal C - Particles and Fields》2004,33(2):273-296
We update a previously-proposed set of supersymmetric benchmark scenarios, taking into account the precise constraints on the cold dark matter density obtained by combining WMAP and other cosmological data, as well as the LEP and
constraints. We assume that R parity is conserved and work within the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking scalar and gaugino masses m0 and m1/2. In most cases, the relic density calculated for the previous benchmarks may be brought within the WMAP range by reducing slightly m0, but in two cases more substantial changes in m0 and m1/2 are made. Since the WMAP constraint reduces the effective dimensionality of the CMSSM parameter space, one may study phenomenology along WMAP lines in the (m1/2, m0) plane that have acceptable amounts of dark matter. We discuss the production, decays and detectability of sparticles along these lines, at the LHC and at linear e + e- colliders in the sub- and multi-TeV ranges, stressing the complementarity of hadron and lepton colliders, and with particular emphasis on the neutralino sector. Finally, we preview the accuracy with which one might be able to predict the density of supersymmetric cold dark matter using collider measurements.Received: 2 September 2003, Published online: 4 February 2004 相似文献
6.
We study the complementarity between dark matter experiments (direct detection and indirect detection) and accelerator experiments
(the CERN LHC and a =1 TeV e+e- linear collider) within the framework of the constrained minimal supersymmetric standard model (MSSM). We show how non-universality
in the scalar and gaugino sectors can affect the experimental prospects to discover the supersymmetric particles. The future
experiments will explore a large part of the parameter space of the MSSM favored by the Wilkinson Microwave Anisotropy Probe
(WMAP) constraint on the relic density, but there still exist some regions beyond reach for certain extreme (fine tuned) values
of the supersymmetric parameters. Whereas the focus point region characterized by heavy scalars will be easily probed by experiments
searching for dark matter, the regions with heavy gauginos and light sfermions will be accessible more easily by collider
experiments. More information on both supersymmetry and astrophysics parameters can thus be obtained by combining the different
signals. 相似文献
7.
We calculate the cosmic microwave background (CMB) anisotropy spectrum in models with millicharged particles of electric charge q~10?6?10?1 in units of electron charge. We find that a large region of the parameter space for the millicharged particles exists where their effect on the CMB spectrum is similar to the effect of baryons. Using WMAP data on the CMB anisotropy and assuming the Big Bang nucleosynthesis value for the baryon abundance, we find that only a small fraction of cold dark matter, Ωmcp<0.007 (at 95% CL), may consist of millicharged particles with the parameters (charge and mass) from this region. This bound significantly narrows the allowed range of the parameters of millicharged particles. In models without paraphotons, millicharged particles are now excluded as a dark matter candidate. We also speculate that recent observation of 511-keV γ rays from the Galactic bulge may be an indication that a (small) fraction of cold dark matter is comprised of millicharged particles. 相似文献
8.
S. Heinemeyer V. A. Khoze M. G. Ryskin M. Tasevsky G. Weiglein 《The European Physical Journal C - Particles and Fields》2011,71(5):1649
We investigate the prospects for Central Exclusive Diffractive (CED) production of BSM Higgs bosons at the LHC using forward
proton detectors installed at 220 m and 420 m distance around ATLAS and/or CMS. We update a previous analysis for the MSSM
taking into account improvements in the theoretical calculations and the most recent exclusion bounds from the Tevatron. We
extend the MSSM analysis to new benchmark scenarios that are in agreement with the cold dark matter relic abundance and other
precision measurements. We analyze the exclusive production of Higgs bosons in a model with a fourth generation of fermions.
Finally, we comment on the determination of Higgs spin–parity and coupling structures at the LHC and show that the forward
proton mode could provide crucial information on the CP\mathcal{CP} properties of the Higgs bosons. 相似文献
9.
The eternal inflation scenario predicts that our observable Universe resides inside a single bubble embedded in a vast inflating multiverse. We present the first observational tests of eternal inflation, performing a search for cosmological signatures of collisions with other bubble universes in cosmic microwave background data from the WMAP satellite. We conclude that the WMAP 7-year data do not warrant augmenting the cold dark matter model with a cosmological constant with bubble collisions, constraining the average number of detectable bubble collisions on the full sky N(s) < 1.6 at 68% C.L. Data from the Planck satellite can be used to more definitively test the bubble-collision hypothesis. 相似文献
10.
We examine the present and future XENON limits on the neutralino dark matter in split supersymmetry (split-SUSY). Through a scan over the parameter space under the current constraints from collider experiments and the WMAP measurement of the dark matter relic density, we find that in the allowed parameter space a large part has been excluded by the present XENON100 limits and a further largish part can be covered by the future exposure (6000 kg day). In case of unobservation of dark matter with such an exposure in the future, the lightest neutralino will remain bino-like and its annihilation is mainly through exchanging the SM-like Higgs boson in order to get the required relic density. 相似文献
11.
Katri Huitu Ritva Kinnunen Jari Laamanen Sami Lehti Sourov Roy Tapio Salminen 《The European Physical Journal C - Particles and Fields》2008,58(4):591-608
In grand-unified theories (GUT), non-universal boundary conditions for the gaugino masses may arise at the unification scale
and may affect the observability of the neutral MSSM Higgs bosons (h/H/A) at the LHC. The implications of such non-universal gaugino masses are investigated for Higgs boson production in the SUSY
cascade decay chain
,
,
,
produced in pp interactions. In the singlet representation with universal gaugino masses only the light Higgs boson can be produced in this
cascade with the parameter region of interest for us, while with non-universal gaugino masses heavy neutral MSSM Higgs boson
production may dominate. The allowed parameter space in the light of the WMAP constraints on the cold dark-matter relic density
is investigated in the above scenarios for gaugino mass parameters. We also demonstrate that combination of representations
can give the required amount of dark matter in any point of the parameter space. In the non-universal case we show that heavy
Higgs bosons can be detected in the cascade studied in parameter regions with the WMAP preferred neutralino relic density. 相似文献
12.
Ellis John Luo Feng Olive Keith A. Sandick Pearl 《The European Physical Journal C - Particles and Fields》2013,73(4):1-16
The recent discovery of a new boson at the LHC, which resembles a SM-like Higgs boson with m h =125 GeV, is starting to provide strong guidelines into SUSY model building. For instance, the identification of such a state with the lightest CP-even Higgs boson of the MSSM (h 0), requires large values of tanβ and/or heavy sfermions. One outcome of this result is the possibility to solve the SUSY flavor and CP problems by decoupling, which points towards some realization of Split-inspired SUSY scenarios, in which scalars are much heavier than gauginos and higgsinos. However, we argue here that the remaining Higgs bosons of the MSSM (H 0, A 0, H ±) do not have to be as heavy as the sfermions, and having them with masses near the EW scale does not pose any conflict with current MSSM constraints. We discuss then some SUSY scenarios with heavy sfermions, from a bottom-up approach, which contain the full Higgs sector, as well as a possible dark matter candidate, with masses near the EW scale, and identify distinctive signals from these scenarios that could be searched at the LHC. 相似文献
13.
In regions of large tanbeta and small mAlpha, searches for heavy neutral minimal supersymmetric standard model (MSSM) Higgs bosons at the Tevatron are promising. At the same time, rates in direct dark matter experiments, such as CDMS, are enhanced in the case of large tanbeta and small mAlpha. As a result, there is a natural interplay between the heavy, neutral Higgs searches at the Tevatron and the region of parameter space explored by CDMS. We show that if the lightest neutralino makes up the dark matter of our universe, current limits from CDMS strongly constrain the prospects of heavy, neutral MSSM Higgs discovery at the Tevatron unless |mu| greater or approximately 400 GeV. The limits of CDMS projected for 2007 will increase this constraint to |mu| greater or approximately 800 GeV. If CDMS does observe neutralinos in the near future, however, it will make the discovery of Higgs bosons at the Tevatron far more likely. 相似文献
14.
The LHC is putting bounds on the Higgs boson mass. In this Letter we use those bounds to constrain the minimal supersymmetric standard model (MSSM) parameter space using the fact that, in supersymmetry, the Higgs mass is a function of the masses of sparticles, and therefore an upper bound on the Higgs mass translates into an upper bound for the masses for superpartners. We show that, although current bounds do not constrain the MSSM parameter space from above, once the Higgs mass bound improves big regions of this parameter space will be excluded, putting upper bounds on supersymmetry (SUSY) masses. On the other hand, for the case of split-SUSY we show that, for moderate or large tanβ, the present bounds on the Higgs mass imply that the common mass for scalars cannot be greater than 10(11) GeV. We show how these bounds will evolve as LHC continues to improve the limits on the Higgs mass. 相似文献
15.
H. V. Klapdor-Kleingrothaus M. Hirsch 《Zeitschrift für Physik A Hadrons and Nuclei》1997,359(4):361-372
The physics potential of GENIUS, a recently proposed double beta decay and dark matter experiment is discussed. The experiment will allow to probe neutrino masses down to 10?(2–3) eV. GENIUS will test the structure of the neutrino mass matrix, and therefore implicitly neutrino oscillation parameters comparable or superior in sensitivity to the best proposed dedicated terrestrial neutrino oscillation experiments. If the 10-3 eV level is reached, GENIUS will even allow to test the large angle MSW solution of the solar neutrino problem. Even in its first stage GENIUS will confirm or rule out degenerate or inverted neutrino mass scenarios, which have been widely discussed in the literature as a possible solution to current hints on finite neutrino masses and also test the νe ? νμ hypothesis of the atmospheric neutrino problem. GENIUS would contribute to the search for R-parity violating SUSY and right-handed W-bosons on a scale similar or superior to LHC. In addition, GENIUS would largely improve the current 0νββ decay searches for R-parity conserving SUSY and leptoquarks. Concerning cold dark matter (CDM) search, the low background anticipated for GENIUS would, for the first time ever, allow to cover the complete MSSM neutralino parameter space, making GENIUS competitive to LHC in SUSY discovery. If GENIUS could find SUSY CDM as a by-product it would confirm that R-parity must be conserved exactly. GENIUS will thus be a major tool for future non-accelerator particle physics. 相似文献
16.
C. Beskidt W. de Boer D. I. Kazakov F. Ratnikov 《The European Physical Journal C - Particles and Fields》2012,72(10):1-8
The ATLAS and CMS experiments did not find evidence for Supersymmetry using close to 5/fb of published LHC data at a center-of-mass energy of 7 TeV. We combine these LHC data with data on $B^{0}_{s}\to \mu^{+}\mu^{-}$ (LHCb experiment), the relic density (WMAP and other cosmological data) and upper limits on the dark matter scattering cross sections on nuclei (XENON100 data). The excluded regions in the constrained Minimal Supersymmetric SM (CMSSM) lead to gluinos excluded below 1270 GeV and dark matter candidates below 220 GeV for values of the scalar masses (m 0) below 1500 GeV. For large m 0 values the limits of the gluinos and the dark matter candidate are reduced to 970 GeV and 130 GeV, respectively. If a Higgs mass of 125 GeV is imposed in the fit, the preferred SUSY region is above this excluded region, but the size of the preferred region is strongly dependent on the assumed theoretical error. 相似文献
17.
M. Carena S. Heinemeyer C. E. M. Wagner G. Weiglein 《The European Physical Journal C - Particles and Fields》2006,45(3):797-814
The Higgs boson search has shifted from LEP2 to the Tevatron and will subsequently move to the LHC. The current limits from
the Tevatron and the prospective sensitivities at the LHC are often interpreted in specific MSSM scenarios. For heavy Higgs
boson production and subsequent decay into
or τ+τ–, the present Tevatron data allow one to set limits in the MA–tan β plane for small MA and large tan β values. Similar channels have been explored for the LHC, where the discovery reach extends to higher values
of MA and smaller tan β. Searches for MSSM charged Higgs bosons, produced in top decays or in association with top quarks, have
also been investigated at the Tevatron and the LHC. We analyze the current Tevatron limits and prospective LHC sensitivities.
We discuss how robust they are with respect to variations of the other MSSM parameters and possible improvements of the theoretical
predictions for Higgs boson production and decay. It is shown that the inclusion of supersymmetric radiative corrections to
the production cross sections and decay widths leads to important modifications of the present limits on the MSSM parameter
space. The impact on the region where only the lightest MSSM Higgs boson can be detected at the LHC is also analyzed. We propose
to extend the existing benchmark scenarios by including additional values of the higgsino mass parameter μ. This affects only
slightly the search channels for a SM-like Higgs boson, while having a major impact on the searches for non-standard MSSM
Higgs bosons. 相似文献
18.
《The European Physical Journal C - Particles and Fields》2006,47(3):547-587
The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for the neutral Higgs bosons which are predicted by
the Minimal Supersymmetric standard model (MSSM). The data of the four collaborations are statistically combined and examined
for their consistency with the background hypothesis and with a possible Higgs boson signal. The combined LEP data show no
significant excess of events which would indicate the production of Higgs bosons. The search results are used to set upper
bounds on the cross-sections of various Higgs-like event topologies. The results are interpreted within the MSSM in a number
of “benchmark” models, including CP-conserving and CP-violating scenarios. These interpretations lead in all cases to large
exclusions in the MSSM parameter space. Absolute limits are set on the parameter cosβ and, in some scenarios, on the masses
of neutral Higgs bosons. 相似文献
19.
We study the implications of the recently improved upper limits on the branching ratios for the decays , expressed as . We work out the constraints that the current bound on implies on the parameters of the quark mixing matrix in the standard model (SM). Using the present profile of the unitarity
triangle, we predict this ratio to lie in the range (at 95% C.L.), with the central value . We also work out the correlations involving , the isospin-violating ratio , and the direct CP-violating asymmetry in decays in the SM, in the minimal supersymmetric extension of the SM (MSSM), and in an extension of the MSSM involving an
additional flavor-changing structure in transitions.
Received: 19 August 2002 / Published online: 18 October 2002
RID="a"
ID="a" e-mail: ali@mail.desy.de
RID="b"
ID="b" e-mail: lunghi@mail.desy.de 相似文献
20.
The recent WMAP data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate
in the flat Universe. Modern particle theories provide viable cold dark matter candidates with masses in the GeV-TeV region.
All such candidates will be called WIMPs (Weakly Interacting Massive Particles). The nature of dark matter can only be unraveled
by its direct detection in the laboratory. In this work we present some theoretical elements relevant to the direct dark matter
detection experiments, paying particular attention to directional experiments, i.e. experiments in which not only the energy
but the direction of the recoiling nucleus is observed. Since the direction of observation is fixed with respect to the Earth,
while the Earth is rotating around its axis, in a directional experiment the angle between the direction of observation and
the Sun’s direction of motion will change during the day. So, since the event rates sensitively depend on this angle, the
observed signal in such experiments will exhibit very interesting and characteristic periodic diurnal variation. 相似文献