352 research outputs found
Nonminimal supersymmetric standard model with lepton number violation
We carry out a detailed analysis of the nonminimal supersymmetric standard
model with lepton number violation. The model contains a unique trilinear
lepton number violating term in the superpotential which can give rise to
neutrino masses at the tree level. We search for the gauged discrete symmetries
realized by cyclic groups which preserve the structure of the associated
trilinear superpotential of this model, and which satisfy the constraints of
the anomaly cancellation. The implications of this trilinear lepton number
violating term in the superpotential and the associated soft supersymmetry
breaking term on the phenomenology of the light neutrino masses and mixing is
studied in detail. We evaluate the tree and loop level contributions to the
neutrino mass matrix in this model. We search for possible suppression
mechanism which could explain large hierarchies and maximal mixing angles.Comment: Latex file, 43 pages, 2 figure
Probing SO(10) symmetry breaking patterns through sfermion mass relations
We consider supersymmetric SO(10) grand unification where the unified gauge
group can break to the Standard Model gauge group through different chains. The
breaking of SO(10) necessarily involves the reduction of the rank, and
consequent generation of non-universal supersymmetry breaking scalar mass
terms. We derive squark and slepton mass relations, taking into account these
non-universal contributions to the sfermion masses, which can help distinguish
between the different chains through which the SO(10) gauge group breaks to the
Standard Model gauge group. We then study some implications of these
non-universal supersymmetry breaking scalar masses for the low energy
phenomenology.Comment: 13 pages, latex using revtex4, contains 2 figures, replaced with
version accepted for publicatio
Squark and slepton masses as probes of supersymmetric SO(10) unification
We carry out an analysis of the non-universal supersymmetry breaking scalar
masses arising in SO(10) supersymmetric unification. By considering patterns of
squark and slepton masses, we derive a set of sum rules for the sfermion masses
which are independent of the manner in which SO(10) breaks to the Standard
Model gauge group via its SU(5) subgroups. The phenomenology arising from such
non-universality is unaffected by the symmetry breaking pattern, so long as the
breaking occurs via any of the SU(5) subgroups of the SO(10) group.Comment: 15 pages using RevTe
Defects in coding joint formation in vivo in developing ATM-deficient B and T lymphocytes
Ataxia-telangiectasia mutated (ATM)–deficient lymphocytes exhibit defects in coding joint formation during V(D)J recombination in vitro. Similar defects in vivo should affect both T and B cell development, yet the lymphoid phenotypes of ATM deficiency are more pronounced in the T cell compartment. In this regard, ATM-deficient mice exhibit a preferential T lymphopenia and have an increased incidence of nontransformed and transformed T cells with T cell receptor α/δ locus translocations. We demonstrate that there is an increase in the accumulation of unrepaired coding ends during different steps of antigen receptor gene assembly at both the immunoglobulin and T cell receptor loci in developing ATM-deficient B and T lymphocytes. Furthermore, we show that the frequency of ATM-deficient αβ T cells with translocations involving the T cell receptor α/δ locus is directly related to the number of T cell receptor α rearrangements that these cells can make during development. Collectively, these findings demonstrate that ATM deficiency leads to broad defects in coding joint formation in developing B and T lymphocytes in vivo, and they provide a potential molecular explanation as to why the developmental impact of these defects could be more pronounced in the T cell compartment
The Minimal Solution to the mu/B_mu Problem in Gauge Mediation
We provide a minimal solution to the mu/B_mu problem in the gauge mediated
supersymmetry breaking by introducing a Standard Model singlet filed S with a
mass around the messenger scale which couples to the Higgs and messenger
fields. This singlet is nearly supersymmetric and acquires a relatively small
Vacuum Expectation Value (VEV) from its radiatively generated tadpole term.
Consequently, both mu and B_mu parameters receive the tree-level and one-loop
contributions, which are comparable due to the small S VEV. Because there
exists a proper cancellation in such two kinds of contributions to B_mu, we can
have a viable Higgs sector for electroweak symmetry breaking.Comment: 15 pages, 2 figures, version published on JHE
Production and Two-photon Decay of the MSSM Scalar Higgs Bosons at the LHC
We consider the production and two-photon decay of the -even Higgs bosons
( and ) of the Minimal Supersymmetric Standard Model (MSSM) at the
Large Hadron Collider. We study in detail the dependence of the cross section
on various parameters of the MSSM, especially the dependence on the mixing
effects in the squark sector due to the Higgs bilinear parameter and the
soft supersymmetry breaking parameter . We find that the cross section for
the production of these Higgs bosons has a significant dependence on the
parameters which determine the chiral mixing in the squark sector. The cross
section times the two-photon branching ratio of is of the order of
15--25~fb in much of the parameter space that remains after imposing the
present experimental constraints. For the the two-photon branching ratio
is only significant if the is light, but then the cross section times the
branching ratio may exceed 200~fb. The QCD corrections due to quark loop
contributions are known to increase the cross section by 50\%. We find the
dependence of the cross section on the gluon distribution function used to be
rather insignificant.Comment: 16 pages, LaTex, plus 9 uuencoded figures attached Full ps file
available at ftp://vsfys1.fi.uib.no/anonymous/pub/ as nordita-9548.ps or
nordita-9548.ps-gz or via http://vsfys1.fi.uib.no/thpubl/publications.htm
Early rise in brain damage markers and high ICOS expression in CD4+ and CD8+ T cells during checkpoint inhibitor-induced encephalomyelitis
We report a case of rapid eradication of melanoma brain metastases and simultaneous near-fatal encephalomyelitis following double immune checkpoint blockade. Brain damage marker S-100B and C reactive protein increased before symptoms or signs of encephalomyelitis and peaked when the patient fell into a coma. At that point, additional brain damage markers and peripheral T cell phenotype was analyzed. The analyses were repeated four times during the patient’s recovery. Axonal damage marker neurofilament light polypeptide (NFL) and astrocytic damage marker glial fibrillar acidic protein (GFAP) were very high in blood and cerebrospinal fluid and gradually normalized after immunosuppression and intensive care. The costimulatory receptor inducible T cell costimulatory receptor (ICOS) was expressed on a high proportion of CD4+ and CD8+T cells as encephalomyelitis symptoms peaked and then gradually decreased in parallel with clinical improvement. Both single and double immune checkpoint inhibitor-treated melanoma patients with other serious immune-related adverse events (irAE) (n=9) also expressed ICOS on a significantly higher proportion of CD4+ and CD8+T cells compared with controls without irAE (n=12). In conclusion, our results suggest a potential role for ICOS on CD4+ and CD8+T cells in mediating encephalomyelitis and other serious irAE. In addition, brain damage markers in blood could facilitate early diagnosis of encephalitis
Zeroing In On the Top Quark, LSP and Scalar Higgs Masses
We estimate the top quark, lightest sparticle (LSP) and scalar higgs masses
within a supersymmetric grand unified framework in which and the electroweak symmetry is radiatively broken. The requirement
that the calculated quark mass lie close to its measured value, together
with the cosmological constraint , fixes the top quark
mass to be . The LSP (of bino purity
has mass . In the scalar
higgs sector the CP-odd scalar mass . With
, as suggested by the decay , we find and .Comment: 14 pages in plain LaTeX, BA-93-25, PRL-TH-93/
Higgs and SUSY searches at future colliders
In this talk, I discuss some aspects of Higgs searches at future colliders,
particularly comparing and contrasting the capabilities of LHC and Next Linear
Collider (NLC), including the aspects of Higgs searches in supersymmetric
theories. After this, I will discuss how the search and study of sparticles
other than the Higgs can give information about the parameters of the Minimal
Supersymmetric Standard Model (MSSM).Comment: 20 pages, 12 figures, laTeX, requires pramana.sty,ias.sty added. In
the Proceedings of XII DAE symposium, Chandigarh, December 199
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