We define benchmark models for SUSY searches at the LHC, including the CMSSM, NUHM, mGMSB, mAMSB, MM-AMSB and p19MSSM, as well as models with R-parity violation and the NMSSM. Within the parameter ...spaces of these models, we propose benchmark subspaces, including planes, lines and points along them. The planes may be useful for presenting results of the experimental searches in different SUSY scenarios, while the specific benchmark points may serve for more detailed detector performance tests and comparisons. We also describe algorithms for defining suitable benchmark points along the proposed lines in the parameter spaces, and we define a few benchmark points motivated by recent fits to existing experimental data.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
General NMSSM signatures at the LHC Dreiner, H. K.; Staub, F.; Vicente, A.
Physical review. D, Particles, fields, gravitation, and cosmology,
02/2013, Letnik:
87, Številka:
3
Journal Article, Web Resource
Recenzirano
Odprti dostop
We study the possible LHC collider signatures in the next-to-minimal supersymmetric standard model. The general next-to-minimal supersymmetric standard model consists of 29 supersymmetric particles ...which can be mass ordered in 29! Asymptotically = to 9 x 10 super(30) ways. To reduce the number of hierarchies to a more manageable amount we assume a degeneracy of the sfermions of the first two generations with the same quantum numbers. Further assumptions about the neutralino and chargino masses leave 15 unrelated parameters. We check all 15! approximate 10 super(12) relevant mass orderings for the dominant decay chains and the corresponding collider signatures at the LHC. As preferred signatures, we consider charged leptons, missing transverse momentum, jets, and W, Z or Higgs bosons. We present the results for three different choices of the singlet to Higgs coupling lambda: (a) small, O(lambda) < O(Y sub(tau)), (b) large, O(lambda) Asymptotically = to O(Y sub(top), Y sub(b), Y sub(tau)), and (c) dominant, O(lambda) > O(Y sub(top)). We compare these three scenarios with the MSSM expectations as well as among each other. We also mention a possible mass hierarchy leading to seven jets plus one lepton signatures at the LHC and comment briefly on the consequence of possible R-parity violation.
We present the possibility of calculating the quark flavor changing neutral current decays Bs0→ℓℓ̄ and Bd0→ℓℓ̄ for a large variety of supersymmetric models. For this purpose, the complete one-loop ...calculation has been implemented in a generic form in the Mathematica package SARAH. This information is used by SARAH to generate Fortran source code for SPheno for a numerical evaluation of these processes in a given model. We comment also on the possibility to use this setup for non-supersymmetric models.
Program title: SARAH
Catalogue identifier: AEIB_v2_1
Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEIB_v2_1.html
Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland
Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html
No. of lines in distributed program, including test data, etc.: 467777
No. of bytes in distributed program, including test data, etc.: 3927691
Distribution format: tar.gz
Programming language: Mathematica, Fortran.
Computer: All computers which can run Mathematica and SPheno.
Operating system: Linux, MacOS.
Classification: 11.1, 11.6.
Catalogue identifier of previous version: AEIB_v2_0
Journal reference of previous version: Comput. Phys. Comm. 184 (2013) 1792
Does the new version supercede the previous version?: Yes, the new version includes all known features of previous versions but provides also the new features mentioned below.
Nature of problem:
Models beyond the SM can have new contributions to the decays of neutral B-mesons. For a precise prediction of the corresponding branching ratios a full 1-loop calculation including all possible wave, penguin and box diagrams is necessary. This usually requires a big effort and public codes for these calculations so far only support a few selected models.
Solution method:
The implementation of a new model in SARAH is easy and straightforward. In addition, SARAH is already delivered with many different supersymmetric and a few non-supersymmetric models. As a first step, SARAH derives the analytical expressions for masses, interactions and renormalization group equations for the given model. Furthermore, SARAH checks for all possible tree- and 1-loop diagrams which can contribute to the B-meson decays into two leptons. This information is exported to Fortran source code which can afterwards be compiled with SPheno. This generates a fully functional spectrum generator: besides the mass spectrum, sparticle and Higgs decays the new SPheno modules also calculate precision observables like the B-meson decays based on the parameters chosen by the user.
Reasons for new version:
The possible decays of neutral B-mesons into two leptons are constraining models beyond the Standard Model. SARAH allows, in the new version, the production of SPheno source code to calculate those decays at full 1-loop for a large variety of models.
Summary of revisions:
Full 1-loop calculation of Bs,d0→ℓℓ̄ for any model which can be implemented in SARAH.
Restrictions:
SARAH can only calculate the renormalization group equations for a supersymmetric model. Hence, for a non-supersymmetric model it is not possible to calculate the running parameters which enter the calculation. These have to be provided by the user as input. In addition, the effects of chiral resummation as well as next-to-leading order QCD corrections known for the MSSM are not included.
Unusual features:
This is the first public tool which allows a full 1-loop calculation of B-meson decays in more complicated models than the minimal or next-to-minimal supersymmetric standard model. Any new contribution in a renormalizable model stemming from an extended matter content or gauge sector is taken into account.
Running time:
Measured CPU time for the evaluation of the MSSM using a Lenovo Thinkpad X220 with i7 processor (2.53 GHz). Calculating the complete Lagrangian: 9 s. Calculating all vertices: 51 s. Output of the UFO model files: 49 s.
A
bstract
In order to accommodate the observed Higgs boson mass in the CMSSM, the stops must either be very heavy or the mixing in the stop sector must be very large. Lower stop masses, possibly more ...accessible at the LHC, still give the correct Higgs mass only if the trilinear stop mixing parameter |
A
t
| is in the multi-TeV range. Recently it has been shown that such large stop mixing leads to an unstable electroweak vacuum which spontaneously breaks charge or color. In this work we therefore go beyond the CMSSM and investigate the effects of including baryon number violating operators
λ
′
′
U
¯
D
¯
D
¯
on the stop and Higgs sectors. We find that for
λ
′
′
≃
O
0.3
light stop masses as low as 220 GeV are consistent with the observed Higgs mass as well as flavour constraints while allowing for a stable vacuum. The light stop in this scenario is often the lightest supersymmetric particle. We furthermore discuss the importance of the one-loop corrections involving
R
-parity violating couplings for a valid prediction of the light stop masses.
A
bstract
Using the example of selected decays driven by R-parity-violating supersymmetric operators, we demonstrate how strong final-state interactions can be controlled quantitatively with high ...precision, thus allowing for a more accurate extraction of effective parameters from data. In our examples we focus on the lepton-flavor-violating decays
τ → μπ
+
π
−
.
InR-parityviolationthesecanariseduetotheproductoftwocouplings. We find bounds that are an order of magnitude stronger than previous ones.
We analyze the impact of electron and positron beam polarization on radiative neutralino production at the international linear collider (ILC). We focus on three different mSUGRA scenarios in turn at ...the Higgs strahlung threshold, the top pair production threshold, and at
500 GeV. In these scenarios at the corresponding
, radiative neutralino production is the only supersymmetric production mechanism that is kinematically allowed. The heavier neutralinos and charginos as well as the sleptons, squarks and gluinos are too heavy to be pair produced. We calculate the signal cross section and also the standard model background from radiative neutrino production. For our scenarios, we obtain significances larger than 10 and signal to background ratios between 2% and 5%, if we have electron beam polarization
–0.8 and positron beam polarization
–0.3. If we have electron beam polarization of
, then the signal is observable with
but both the significance and the signal to background ratio are significantly improved for
.
From the LHC to future colliders De Roeck, A; Ellis, J; Grojean, C ...
The European physical journal. C, Particles and fields,
04/2010, Letnik:
66, Številka:
3-4
Journal Article
Recenzirano
Odprti dostop
Discoveries at the LHC will soon set the physics agenda for future colliders. This report of a CERN Theory Institute includes the summaries of Working Groups that reviewed the physics goals and ...prospects of LHC running with 10 to 300 fb−1 of integrated luminosity, of the proposed sLHC luminosity upgrade, of the ILC, of CLIC, of the LHeC and of a muon collider. The four Working Groups considered possible scenarios for the first 10 fb−1 of data at the LHC in which (i) a state with properties that are compatible with a Higgs boson is discovered, (ii) no such state is discovered either because the Higgs properties are such that it is difficult to detect or because no Higgs boson exists, (iii) a missing-energy signal beyond the Standard Model is discovered as in some supersymmetric models, and (iv) some other exotic signature of new physics is discovered. In the contexts of these scenarios, the Working Groups reviewed the capabilities of the future colliders to study in more detail whatever new physics may be discovered by the LHC. Their reports provide the particle physics community with some tools for reviewing the scientific priorities for future colliders after the LHC produces its first harvest of new physics from multi-TeV collisions.
A
bstract
If SUSY is discovered at the LHC, the task will immediately turn to determining the model of SUSY breaking. Here, we employ a Mixed Modulus-Anomaly Mediated SUSY Breaking (MMAMSB) model ...with very similar LHC phenomenology to the more conventionally studied Constrained Minimal SUSY Model (CMSSM) and minimal Anomaly Mediated SUSY Breaking (mAMSB) models. We then study whether the models can be distinguished and measured. If we only fit to the various mass edges and mass end-points from cascade decay chains that are normally studied, a unique determination and measurement of the model is problematic without substantial amounts of LHC data. However, if event rate information is included, we can quickly distinguish and measure the correct SUSY model and exclude alternatives.
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