18 research outputs found
Corrections to di-Higgs boson production with light stops and modified Higgs couplings
The Higgs pair production in gluon fusion is a sensitive probe of
beyond-Standard Model (BSM) phenomena and its detection is a major goal for the
LHC and higher energy hadron collider experiments. In this work we reanalyze
the possible modifications of the Higgs pair production cross section within
low energy supersymmetry models. We show that the supersymmetric contributions
to the Higgs pair production cross section are strongly correlated with the
ones of the single Higgs production in the gluon fusion channel. Motivated by
the analysis of ATLAS and CMS Higgs production data, we show that the scalar
superpartners' contributions may lead to significant modification of the
di-Higgs production rate and invariant mass distribution with respect to the SM
predictions. We also analyze the combined effects on the di-Higgs production
rate of a modification of the Higgs trilinear and top-quark Yukawa couplings in
the presence of light stops. In particular, we show that due to the destructive
interference of the triangle and box amplitude contributions to the di-Higgs
production cross section, even a small modification of the top-quark Yukawa
coupling can lead to a significant increase of the di-Higgs production rate.Comment: 33 pages, 13 figures v2: minor improvements, PRD versio
Exploring Extended Scalar Sectors with Di-Higgs Signals: A Higgs EFT Perspective
We consider extended scalar sectors of the Standard Model as
ultraviolet-complete motivations for studying the effective Higgs
self-interaction operators of the Standard Model effective field theory. We
investigate all motivated heavy scalar models which generate the dimension-6
effective operator, , at tree level and proceed to identify the full set
of tree-level dimension-six operators by integrating out the heavy scalars. Of
seven models which generate at tree level only two, quadruplets of
hypercharge and , generate only this operator. Next we perform
global fits to constrain relevant Wilson coefficients from the LHC single Higgs
measurements as well as the electroweak oblique parameters and . We find
that the parameter puts very strong constraints on the Wilson coefficient
of the operator in the triplet and quadruplet models, while the singlet
and doublet models could still have Higgs self-couplings which deviate
significantly from the standard model prediction. To determine the extent to
which the operator could be constrained, we study the dihiggs
signatures at the future 100 TeV collider and explore future sensitivity of
this operator. Projected onto the Higgs potential parameters of the extended
scalar sectors, with ab luminosity data we will be able to explore
the Higgs potential parameters in all seven models.Comment: 25 pages, 11 figures, 6 tables; version 3: match the JHEP published
versio
Probing the Electroweak Phase Transition at the LHC
We study the correlation between the value of the triple Higgs coupling and
the nature of the electroweak phase transition. We use an effective potential
approach, including higher order, non-renormalizable terms coming from
integrating out new physics. We show that if only the dimension six operators
are considered, large positive deviations of the triple Higgs coupling from its
Standard Model (SM) value are predicted in the regions of parameter space
consistent with a strong first order electroweak phase transition (SFOEPT). We
also show that at higher orders sizable and negative deviations of the triple
Higgs coupling may be obtained, and the sign of the corrections tends to be
correlated with the order of the phase transition. We also consider a singlet
extension of the SM, which allows us to establish the connection with the
effective field theory (EFT) approach and analyze the limits of its validity.
Furthermore, we study how to probe the triple Higgs coupling from the double
Higgs production at the LHC. We show that selective cuts in the invariant mass
of the two Higgs bosons should be used, to maximize the sensitivity for values
of the triple Higgs coupling significantly different from the Standard Model
one.Comment: 43 pages, 4 figure
Heating Neutron Stars with Inelastic Dark Matter and Relativistic Targets
The dense environment of neutron stars makes them an excellent target for
probing dark matter interactions with the Standard Model. We study neutron star
heating from capture of inelastic dark matter, which can evade direct detection
constraints. We investigate kinematics of the inelastic scattering process
between quasirelativistic dark matter particles and ultrarelativistic targets
in neutron stars, and derive analytical expressions for the maximal mass gap
allowed for the scattering to occur. We implement them into a fully
relativistic formalism for calculating the capture rate and apply it to various
scenarios of inelastic dark matter. The projected constraints from neutron
stars can systematically surpass those from terrestrial searches, including
direct detection and collider experiments. Neutron stars can also be sensitive
to the parameter space of inelastic self-interacting dark matter. Our results
indicate that extreme astrophysical environments, such as neutron stars, are an
important target for searching dark matter.Comment: 25 pages, 6 figure
Saptarshi’s visit to different Nakshatras:
Summary In several ancient Indian texts a mention is made of the movement of the Saptarshi constellation (Big Bear or Big Dipper) in the sky, visiting each nakshatras for 100 years. Saptarshi is said to visit a nakshatra if the nakshatra is in the middle of the stars in the first part of Saptarshi. Since astronomical objects except planets are more or less stationary in the sky, this is generally considered a fanciful statement devoid of astronomical meaning. We show that this may not be so. We show that the visit of Saptarshi to different nakshatras may be a very significant astronomical observation. The transition is not a constant of time since it depends on the proximity of the Saptarshi to the North Pole, which changes due to Earth"s precession and relative sizes of different nakshatras. We show that since 8000 BC, Saptarshi has visited 5 different nakshatras and for one of them, the transition happening in the span of roughly 100 years. We show that this interpretation allows dating of this belief which is consistent with other evidences of the Harappan civilisation and date different Saptarshi Era with calendar dates
Physics Potential of a 2540 Km Baseline Superbeam Experiment
We study the physics potential of a neutrino superbeam experiment with a 2540
km baseline. We assume a neutrino beam similar to the NuMI beam in medium
energy configuration. We consider a 100 kton totally active scintillator
detector at a 7 mr off-axis location. We find that such a configuration has
outstanding hierarchy discriminating capability. In conjunction with the data
from the present reactor neutrino experiments, it can determine the neutrino
mass hierarchy at 3 sigma level in less than 5 years, if sin^2(2*theta13) >
0.01, running in the neutrino mode alone. As a stand alone experiment, with a 5
year neutrino run and a 5 year anti-neutrino run, it can determine non-zero
theta13 at 3 sigma level if sin^2(2*theta13) > 7*10^{-3} and hierarchy at 3
sigma level if sin^2(2*theta13) > 8*10^{-3}. This data can also distinguish
deltaCP = pi/2 from the CP conserving values of 0 and pi, for sin^2(2*theta13)
> 0.02.Comment: 16 pages, 7 figures and 1 table: Published versio
Probing the electroweak phase transition at the LHC
We study the correlation between the value of the triple Higgs coupling and the nature of the electroweak phase transition. We use an effective potential approach, including higher order, nonrenormalizable terms coming from integrating out new physics.We show that if only the dimension six operators are considered, large positive deviations of the triple Higgs coupling from its standard model (SM) value are predicted in the regions of parameter space consistent with a strong first order electroweak phase transition. We also show that at higher orders sizable and negative deviations of the triple Higgs coupling may be obtained, and the sign of the corrections tends to be correlated with the order of the phase transition. We also consider a singlet extension of the SM, which allows us to establish the connection with the effective field theory approach and analyze the limits of its validity. Furthermore, we study how to probe the triple Higgs coupling from the double Higgs production at the LHC.We show that selective cuts in the invariant mass of the two Higgs bosons should be used, to maximize the sensitivity for values of the triple Higgs coupling significantly different from the standard model one