221 research outputs found
Electroweak vacuum stability and finite quadratic radiative corrections
If the Standard Model (SM) is an effective theory, as currently believed, it
is valid up to some energy scale to which the Higgs vacuum
expectation value is sensitive throughout radiative quadratic terms. The latter
ones destabilize the electroweak vacuum and generate the SM hierarchy problem.
For a given perturbative Ultraviolet (UV) completion, the SM cutoff can be
computed in terms of fundamental parameters. If the UV mass spectrum involves
several scales the cutoff is not unique and each SM sector has its own UV
cutoff . We have performed this calculation assuming the Minimal
Supersymmetric Standard Model (MSSM) is the SM UV completion. As a result, from
the SM point of view, the quadratic corrections to the Higgs mass are
equivalent to finite threshold contributions. For the measured values of the
top quark and Higgs masses, and depending on the values of the different
cutoffs , these contributions can cancel even at renormalization
scales as low as multi-TeV, unlike the case of a single cutoff where the
cancellation only occurs at Planckian energies, a result originally obtained by
Veltman. From the MSSM point of view, the requirement of stability of the
electroweak minimum under radiative corrections is incorporated into the
matching conditions and provides an extra constraint on the Focus Point
solution to the little hierarchy problem in the MSSM. These matching conditions
can be employed for precise calculations of the Higgs sector in scenarios with
heavy supersymmetric fields.Comment: 36 pages, 5 figures; v2: logarithm corrections included, figures
improved, references adde
Radion dynamics, heavy Kaluza-Klein resonances and gravitational waves
We study the confinement/deconfinement phase transition of the radion field
in a warped model with a polynomial bulk potential. The backreaction of the
radion on the metric is taken into account by using the superpotential
formalism, while the radion effective potential is obtained from a novel
formulation which can incorporate the backreaction. The phase transition leads
to a stochastic gravitational wave background that depends on the energy scale
of the first Kaluza-Klein resonance, . This work completes
previous studies in the following aspects: i) we detail the evaluation of the
radion spectrum; ii) we report on the mismatches between the thick wall
approximation and the numerical bounce solution; iii) we include a suppression
factor in the spectrum of sound waves accounting for their finite lifetime;
and, iv) we update the bound on in view of the O3 LIGO and
Virgo data. We find that the forthcoming gravitational wave interferometers can
probe scenarios where TeV, while the O3-run
bounds rule out warped models with TeV exhibiting an extremely strong confinement/deconfinement
phase transition.Comment: 16 pages, 7 figures; v2 extended version: added references and Figs.
2, 3, 5 and 7 (lower panels), Figs. 6 and 7 (upper panels) updated, extended
discussion in Secs. 3.3, 4, 5 and 6. Talk given by E.Megias at the 9th
International Conference on New Frontiers in Physics (ICNFP 2020), 4 Sep - 2
Oct 2020, Kolymbari, Crete, Greec
Gravitational imprints from heavy Kaluza-Klein resonances
We systematically study the holographic phase transition of the radion field in a five-dimensional warped model which includes a scalar potential with a powerlike behavior. We consider Kaluza-Klein (KK) resonances with masses m KK at the TeV scale or beyond. The backreaction of the radion field on the gravitational metric is taken into account by using the superpotential formalism. The confinement/deconfinement first order phase transition leads to a gravitational wave stochastic background which mainly depends on the scale m KK and the number of colors, N , in the dual theory. Its power spectrum peaks at a frequency that depends on the amount of tuning required in the electroweak sector. It turns out that the present and forthcoming gravitational wave observatories can probe scenarios where the KK resonances are very heavy. Current aLIGO data already rule out vector boson KK resonances with masses in the interval m KK ∼ ( 1 – 10 ) × 10 5     TeV . Future gravitational experiments will be sensitive to resonances with masses m KK ≲ 10 5     TeV (LISA), 10 8     TeV (aLIGO Design) and 10 9     TeV (ET). Finally, we also find that the big bang nucleosynthesis bound in the frequency spectrum turns into a lower bound for the nucleation temperature as T n ≳ 10 − 4 √ N m KK .publishedVersio
Pulsar Timing Array Stochastic Background from light Kaluza-Klein resonances
We investigate the potential of the warped-extradimension framework as an
explanation for the recently observed stochastic gravitational background at
nHz frequencies in pulsar timing arrays (PTA). Our analysis reveals that the
PTA data can be effectively accommodated by a first-order phase transition
triggered by a radion at the MeV-GeV scale feebly coupled to the Standard
Model. Remarkably, this outcome remains robust irrespective of the specific
details of the warped extradimension embedding, providing a foundation for
future investigations aiming to develop concrete extradimension descriptions of
Nature. We also demonstrate that many existing embeddings are not viable, as
their radion and graviton phenomenology clash with a MeV-GeV scale radion. As a
possible way-out, we sketch a promising solution involving multiple branes,
wherein the light radion, graviton, and ensuing light resonances remain
consistent with collider bounds and gravity tests.Comment: 14 pages, 3 figure
Gravitational imprints from heavy Kaluza-Klein resonances
We systematically study the holographic phase transition of the radion field in a five-dimensional warped model which includes a scalar potential with a powerlike behavior. We consider Kaluza-Klein (KK) resonances with masses mKK at the TeV scale or beyond. The backreaction of the radion field on the gravitational metric is taken into account by using the superpotential formalism. The confinement/deconfinement first order phase transition leads to a gravitational wave stochastic background which mainly depends on the scale mKK and the number of colors, N, in the dual theory. Its power spectrum peaks at a frequency that depends on the amount of tuning required in the electroweak sector. It turns out that the present and forthcoming gravitational wave observatories can probe scenarios where the KK resonances are very heavy. Current aLIGO data already rule out vector boson KK resonances with masses in the interval mKK ∼ ð1–10Þ × 105 TeV. Future gravitational experiments will be sensitive to resonances with masses mKK ≲ 105 TeV (LISA), 108 TeV (aLIGO Design) and 109 TeV (ET). Finally, we also find that the big bang nucleosynthesis bound in the frequency spectrum turns into a lower bound for the nucleation temperature as Tn ≳ 10−4nSpanish MINEICO
FIS2017-85053-C2-1-P
FPA2017-88915-PFEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento 2014-2020 Operational Programme
A-FQM-178-UGR18Junta de Andalucia
FQM-225European Union (EU)
SOMM17/6105/UGRGerman Research Foundation (DFG)
RYC-2016-20678Catalan Government
2017SGR1069evero Ochoa Excellence Program of MINEICO
SEV2016-058
The Effective Theory of the Light Stop Scenario
Electroweak baryogenesis in the minimal supersymmetric extension of the
Standard Model may be realized within the light stop scenario, where the
right-handed stop mass remains close to the top-quark mass to allow for a
sufficiently strong first order electroweak phase transition. All other
supersymmetric scalars are much heavier to comply with the present bounds on
the Higgs mass and the electron and neutron electric dipole moments. Heavy
third generation scalars render it necessary to resum large logarithm
contributions to perform a trustable Higgs mass calculation. We have studied
the one--loop RGE improved effective theory below the heavy scalar mass scale
and obtained reliable values of the Higgs mass. Moreover, assuming a common
mass for all heavy scalar particles, and values of all gaugino
masses and the Higgsino mass parameter about the weak scale, and imposing gauge
coupling unification, a two-loop calculation yields values of the mass in the interval between three TeV and six hundred TeV. Furthermore for a
stop mass around the top quark mass, this translates into an upper bound on the
Higgs mass of about 150 GeV. The Higgs mass bound becomes even stronger, of
about 129 GeV, for the range of stop and gaugino masses consistent with
electroweak baryogenesis. The collider phenomenology implications of this
scenario are discussed in some detail.Comment: 28 pages, 13 figures, uses axodraw.sty; v2: To appear in JHE
Poly(ADP-ribosyl)ation is involved in the epigenetic control of TET1 gene transcription
TET enzymes are the epigenetic factors involved in the formation of the Sixth DNA base 5-hydroxymethylcytosine, whose deregulation has been associated with tumorigenesis. In particular, TET1 acts as tumor suppressor preventing cell proliferation and tumor metastasis and it has frequently been found down-regulated in cancer. Thus, considering the importance of a tight control of TET1 expression, the epigenetic mechanisms involved in the transcriptional regulation of TET1 gene are here investigated. The involvement of poly(ADP-ribosyl)ation in the control of DNA and histone methylation on TET1 gene was examined. PARP activity is able to positively regulate TET1 expression maintaining a permissive chromatin state characterized by DNA hypomethylation of TET1 CpG island as well as high levels of H3K4 trimethylation. These epigenetic modifications were affected by PAR depletion causing TET1 downregulation and in turn reduced recruitment of TET1 protein on HOXA9 target gene. In conclusion, this work shows that PARP activity is a transcriptional regulator of TET1 gene through the control of epigenetic events and it suggests that deregulation of these mechanisms could account for TET1 repression in cancer
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