154 research outputs found
Supersymmetric Dark Matter after LHC Run 1
Different mechanisms operate in various regions of the MSSM parameter space
to bring the relic density of the lightest neutralino, neutralino_1, assumed
here to be the LSP and thus the Dark Matter (DM) particle, into the range
allowed by astrophysics and cosmology. These mechanisms include coannihilation
with some nearly-degenerate next-to-lightest supersymmetric particle (NLSP)
such as the lighter stau (stau_1), stop (stop_1) or chargino (chargino_1),
resonant annihilation via direct-channel heavy Higgs bosons H/A, the light
Higgs boson h or the Z boson, and enhanced annihilation via a larger Higgsino
component of the LSP in the focus-point region. These mechanisms typically
select lower-dimensional subspaces in MSSM scenarios such as the CMSSM, NUHM1,
NUHM2 and pMSSM10. We analyze how future LHC and direct DM searches can
complement each other in the exploration of the different DM mechanisms within
these scenarios. We find that the stau_1 coannihilation regions of the CMSSM,
NUHM1, NUHM2 can largely be explored at the LHC via searches for missing E_T
events and long-lived charged particles, whereas their H/A funnel, focus-point
and chargino_1 coannihilation regions can largely be explored by the LZ and
Darwin DM direct detection experiments. We find that the dominant DM mechanism
in our pMSSM10 analysis is chargino_1 coannihilation: {parts of its parameter
space can be explored by the LHC, and a larger portion by future direct DM
searches.Comment: 21 pages, 8 figure
The pMSSM10 after LHC Run 1
We present a frequentist analysis of the parameter space of the pMSSM10, in
which the following 10 soft SUSY-breaking parameters are specified
independently at the mean scalar top mass scale Msusy = Sqrt[M_stop1 M_stop2]:
the gaugino masses M_{1,2,3}, the 1st-and 2nd-generation squark masses M_squ1 =
M_squ2, the third-generation squark mass M_squ3, a common slepton mass M_slep
and a common trilinear mixing parameter A, the Higgs mixing parameter mu, the
pseudoscalar Higgs mass M_A and tan beta. We use the MultiNest sampling
algorithm with 1.2 x 10^9 points to sample the pMSSM10 parameter space. A
dedicated study shows that the sensitivities to strongly-interacting SUSY
masses of ATLAS and CMS searches for jets, leptons + MET signals depend only
weakly on many of the other pMSSM10 parameters. With the aid of the Atom and
Scorpion codes, we also implement the LHC searches for EW-interacting
sparticles and light stops, so as to confront the pMSSM10 parameter space with
all relevant SUSY searches. In addition, our analysis includes Higgs mass and
rate measurements using the HiggsSignals code, SUSY Higgs exclusion bounds, the
measurements B-physics observables, EW precision observables, the CDM density
and searches for spin-independent DM scattering. We show that the pMSSM10 is
able to provide a SUSY interpretation of (g-2)_mu, unlike the CMSSM, NUHM1 and
NUHM2. As a result, we find (omitting Higgs rates) that the minimum chi^2/dof =
20.5/18 in the pMSSM10, corresponding to a chi^2 probability of 30.8 %, to be
compared with chi^2/dof = 32.8/24 (31.1/23) (30.3/22) in the CMSSM (NUHM1)
(NUHM2). We display 1-dimensional likelihood functions for SUSY masses, and
show that they may be significantly lighter in the pMSSM10 than in the CMSSM,
NUHM1 and NUHM2. We discuss the discovery potential of future LHC runs, e+e-
colliders and direct detection experiments.Comment: 47 pages, 29 figure
Slepton pair production in the POWHEG BOX
We present an implementation for slepton pair production at hadron colliders
in the POWHEG BOX, a framework for combining next-to-leading order QCD
calculations with parton-shower Monte-Carlo programs. Our code provides a SUSY
Les Houches Accord interface for setting the supersymmetric input parameters.
Decays of the sleptons and parton-shower effects are simulated with PYTHIA.
Focussing on a representative point in the supersymmetric parameter space we
show results for kinematic distributions that can be observed experimentally.
While next-to-leading order QCD corrections are sizable for all distributions,
the parton shower affects the color-neutral particles only marginally.
Pronounced parton-shower effects are found for jet distributions.Comment: 10 pages, 4 figure
On the NLO QCD corrections to the production of the heaviest neutral Higgs scalar in the MSSM
We present a calculation of the two-loop top-stop-gluino contributions to
Higgs production via gluon fusion in the MSSM. By means of an asymptotic
expansion in the heavy particle masses, we obtain explicit and compact analytic
formulae that are valid when the Higgs and the top quark are lighter than stops
and gluino, without assuming a specific hierarchy between the Higgs mass and
the top mass. Being applicable to the heaviest Higgs scalar in a significant
region of the MSSM parameter space, our results complement earlier ones
obtained with a Taylor expansion in the Higgs mass, and can be easily
implemented in computer codes to provide an efficient and accurate
determination of the Higgs production cross section.Comment: 18 pages, 4 figure
Top-mass effects in differential Higgs production through gluon fusion at order \alpha_s^4
Effects from a finite top quark mass on differential distributions in the
Higgs+jet production cross section through gluon fusion are studied at
next-to-leading order in the strong coupling, i.e. . Terms
formally subleading in are calculated, and their influence on the
transverse momentum and rapidity distribution of the Higgs boson are evaluated.
We find that, for the differential K-factor, the heavy-top limit is valid at
the 2-3% level as long as the transverse momentum of the Higgs remains below
about 150 GeV.Comment: 21 pages, 12 figure
Heavy-quark mass effects in Higgs boson production at the LHC
We study the impact of heavy-quark masses in Higgs boson production through
gluon fusion at the LHC. We extend previous computations of the fully
differential cross section and of the transverse momentum spectrum of the Higgs
boson by taking into account the finite top- and bottom-quark masses up to
O(alpha_S^3). We also discuss the issues arising when the heavy-quark mass is
much smaller than the Higgs mass. Our results are implemented in updated
versions of the HNNLO and HRes numerical programs.Comment: Minor modifications, results unchanged. Discussion on uncertainties
added. Version published on JHE
Direct detection of Higgs-portal dark matter at the LHC
We consider the process in which a Higgs particle is produced in association
with jets and show that monojet searches at the LHC already provide interesting
constraints on the invisible decays of a 125 GeV Higgs boson. Using the
existing monojet searches performed by CMS and ATLAS, we show the 95%
confidence level limit on the invisible Higgs decay rate is of the order of the
total Higgs production rate in the Standard Model. This limit could be
significantly improved when more data at higher center of mass energies are
collected, provided systematic errors on the Standard Model contribution to the
monojet background can be reduced. We also compare these direct constraints on
the invisible rate with indirect ones based on measuring the Higgs rates in
visible channels. In the context of Higgs portal models of dark matter, we then
discuss how the LHC limits on the invisible Higgs branching fraction impose
strong constraints on the dark matter scattering cross section on nucleons
probed in direct detection experiments.Comment: 6 pages, 3 figures; v2: references added; v3: monojet and Higgs data
updated, version published in EPJ
Quark masses in Higgs production with a jet veto
We study the impact of finite mass effects due to top and bottom loops in the jet-veto distribution for Higgs production. We discuss the appearance of non-factorizing logarithms in the region p t,veto ≳ m b . We study their numerical impact and argue that these terms can be treated as a finite remainder. We therefore detail our prescription for resumming the jet-vetoed cross section and for assessing its uncertainty in the presence of finite mass effects. Resummation for the jet-veto, including mass effects, has been implemented in the public code JetVHeto
Likelihood analysis of the pMSSM11 in light of LHC 13-TeV data
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)μ constraint. The pMSSM11 is specified by the following parameters: 3 gaugino masses M1,2,3 , a common mass for the first-and second-generation squarks mq~ and a distinct third-generation squark mass mq~3 , a common mass for the first-and second-generation sleptons mℓ~ and a distinct third-generation slepton mass mτ~ , a common trilinear mixing parameter A, the Higgs mixing parameter μ , the pseudoscalar Higgs mass MA and tanβ . In the fit including (g−2)μ , a Bino-like χ~01 is preferred, whereas a Higgsino-like χ~01 is mildly favoured when the (g−2)μ 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, χ~01 , into the range indicated by cosmological data. In the fit including (g−2)μ , coannihilations with χ~02 and the Wino-like χ~±1 or with nearly-degenerate first- and second-generation sleptons are active, whereas coannihilations with the χ~02 and the Higgsino-like χ~±1 or with first- and second-generation squarks may be important when the (g−2)μ constraint is dropped. In the two cases, we present χ2 functions in two-dimensional mass planes as well as their one-dimensional profile projections and best-fit spectra. Prospects remain for discovering strongly-interacting sparticles at the LHC, in both the scenarios with and without the (g−2)μ constraint, as well as for discovering electroweakly-interacting sparticles at a future linear e+e− collider such as the ILC or CLIC
Tandem plasmaferesi-emodialisi in bambini e giovani adulti
In pazienti che necessitino sia di plasmaferesi (PLF) che di emodialisi (ED), l'applicazione simultanea delle due metodiche, nota come tandem PLF-ED (TPE) può costituire una soluzione vantaggiosa. Tuttavia esiste scarsa esperienza circa il suo utilizzo, in particolare in età pediatrica.
Abbiamo esaminato in modo retrospettivo le sedute di TPE eseguite negli ultimi 5 anni nel nostro Centro. I trattamenti di TPE sono stati 67 in 7 pazienti, di età mediana 16.2 anni (5–34) e peso mediano di 37 kg (17.0– 59.0). Le indicazioni per TPH erano: sindrome emolitica uremica atipica da deficit di fattore H, fattore I o da mutazioni non definite, nella maggior parte delle sedute (64/67 sedute), vasculite, glomerulosclerosi focale (prima del trapianto) e iperimmunizzazione in pazienti in lista per trapianto di rene. In 66/67 trattamenti la procedura è stata completata con successo, raggiungendo i volumi di sostituzione e ultrafiltrazione desiderati. La durata della PLF è stata inferiore a quella di ED, e non ha quindi comportato un prolungamento della seduta dialitica. Un unico trattamento è stato interrotto a causa di un episodio ipotensivo, in una paziente nota per ipotensioni ricorrenti. In conclusione la TPE è una procedura sicura e ben tollerata, anche in bambini e adolescenti stabili dal punto di vista emodinamico
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