A
bstract
A multi-TeV muon collider proves to be very efficient not only for the search for new heavy neutral particles, but also for the discovery of charged bosons of the
W
′ type. We find that, by ...analyzing the associated production with a Standard Model W, charged resonances can be probed directly up to multi-TeV mass values close to the collision energy, and for very small couplings with the SM fermions, of the order of 10
−
3
− 10
−
4
times the SM weak coupling. Additionally, charged bound states of WIMP Minimal Dark Matter, specifically a Majorana fermionic 5-plet, can be discovered with low statistics by running above the kinematic threshold, at a center-of-mass energy just slightly above the mass of the MDM bound state. This opens up a very interesting possibility for the discovery of WIMPs, complementary to the search for the resonant production of the neutral MDM bound state component, which relies on an on-peak search. For 5-plet MDM, indeed, the proposed search strategy is more efficient than the WIMP searches based on mono-X, missing-mass and disappearing tracks signatures.
We review the present status and the future prospects for the measurements of the Higgs Yukawa couplings to light quarks and charm. A special focus is given to new proposed off-shell probes, which ...offer promising and complementary opportunities to test light quark Yukawas in triboson final states. Additionally, a new off-shell strategy to test the charm Yukawa coupling in the final state with two bosons plus a charm and a jet is considered. First estimates for the HL-LHC and the FCC-hh sensitivities on the channel are presented, showing encouraging results.
A
bstract
A possible composite nature of the Higgs could be revealed at the early stage of the LHC, by analyzing the channels where the Higgs is produced from the decay of a heavy fermion. The Higgs ...production from a singly-produced heavy bottom, in particular, proves to be a promising channel. For a value λ = 3 of the Higgs coupling to a heavy bottom, for example, we find that, considering a 125 GeV Higgs which decays into a pair of
b
-quarks, a discovery is possible at the 8 TeV LHC with 30 fb
−1
if the heavy bottom is lighter than roughly 530 GeV (while an observation is possible for heavy bottom masses up to ≃ 650 GeV). Such a relatively light heavy bottom is realistic in composite Higgs models of the type considered and, up to now, experimentally allowed. At
TeV the LHC sensitivity on the channel increases significantly. With λ = 3 a discovery can occur, with 100 fb
−1
, for heavy bottom masses up to ≃ 1040 GeV. In the case the heavy bottom was as light as ≃ 500 GeV, the 14 TeV LHC would be sensitive to the measure of the λ coupling in basically the full range λ
>
1 predicted by the theory.
A
bstract
The hypothesis that Dark Matter is one electroweak multiplet leads to predictive candidates with multi-TeV masses that can form electroweak bound states. Bound states with the same quantum ...numbers as electroweak vectors are found to be especially interesting, as they can be produced resonantly with large cross sections at lepton colliders. Such bound states exist e.g. if DM is an automatically stable fermionic weak 5-plet with mass
M ≈
14 TeV such that the DM abundance is reproduced thermally. In this model, a muon collider could resolve three such bound states. Production rates are so large that details of DM spectroscopy can be probed with larger statistics: we compute the characteristic pattern of single and multiple
γ
lines.
A
bstract
We discuss as accurately as possible the cross section of quasi-elastic scattering of electron (anti-)neutrinos on nucleons, also known as inverse beta decay in the case of antineutrinos. ...We focus on the moderate energy range from a few MeV up to hundreds of MeV, which includes neutrinos from reactors and supernovae. We assess the uncertainty on the cross section, which is relevant to experimental advances and increasingly large statistical samples. We estimate the effects of second-class currents, showing that they are small and negligible for current applications.
Light quark Yukawas in triboson final states Falkowski, Adam; Ganguly, Sanmay; Gras, Phillippe ...
The journal of high energy physics,
04/2021, Letnik:
2021, Številka:
4
Journal Article
Recenzirano
Odprti dostop
A
bstract
Triple heavy vector boson production,
pp → VVV
(
V
=
W, Z
), has recently been observed for the first time. We propose that precision measurements of this process provide an excellent probe ...of the first generation light quark Yukawa couplings. Modified quark interactions with the off-shell Higgs in this process lead to a rapid growth of the partonic cross sections with energy, which manifests in an enhanced
p
T
distribution of the final state leptons and quarks. We quantify this effect and estimate the present and future 2
σ
sensitivity to the up, down, and strange Yukawas. In particular, we find that HL-LHC can reach
O
400
sensitivity to the down Yukawa relative to the Standard Model value, improving the current sensitivity in this process by a factor of 10, and which can be further improved to
O
30
at FCC-hh. This is competitive with and complementary to constraints from global fits and other on-shell probes of the first generation Yukawas. The triboson sensitivity at HL-LHC corresponds to probing dimension-6 SMEFT operators suppressed by an
O
1
TeV scale, similarly to other LHC Higgs probes.
A
bstract
We study the collider phenomenology of the lightest Kaluza-Klein excitation of the gluon,
G
*, in theories with a warped extra dimension. We do so by means of a two-site effective ...lagrangian which includes only the lowest-lying spin-1 and spin-1/2 resonances. We point out the importance of the decays of
G
* to one SM plus one heavy fermion, that were overlooked in the previous literature. It turns out that, when kinematically allowed, such heavy-light decays are powerful channels for discovering the
G
*. In particular, we present a parton-level Montecarlo analysis of the final state
W tb
that follows from the decay of
G
* to one SM top or bottom quark plus its heavy partner. We find that at
and with 10fb
−1
of integrated luminosity, the LHC can discover a KK gluon with mass in the range
M
G*
= (1
.
8 − 2
.
2) TeV if its coupling to a pair of light quarks is
. The same process is also competitive for the discovery of the top and bottom partners as well. We find, for example, that the LHC at
can discover a 1 TeV KK bottom quark with an integrated luminosity of (5
.
3 − 0
.
61) fb
−1
for
.
Collider tests of (composite) diphoton resonances Molinaro, Emiliano; Sannino, Francesco; Vignaroli, Natascia
Nuclear physics. B,
October 2016, 2016-10-00, 2016-10-01, Letnik:
911, Številka:
C
Journal Article
Recenzirano
Odprti dostop
We analyze the Large Hadron Collider sensitivity to new pseudoscalar resonances decaying into diphoton with masses up to scales of few TeVs. We focus on minimal scenarios where the production ...mechanisms involve either photon or top-mediated gluon fusion, partially motivated by the tantalizing excess around 750 GeV reported by ATLAS and CMS. The two scenarios lead respectively to a narrow and a wide resonance. We first provide a model-independent analysis via effective operators and then introduce minimal models of composite dynamics where the diphoton channel is characterized by their topological sector. The relevant state here is the pseudoscalar associated with the axial anomaly of the new composite dynamics. If the Standard Model top mass is generated via four-fermion operators the coupling of this state to the top remarkably explains the wide-width resonance reported by ATLAS. Beyond the excess, our analysis paves the way to test dynamical electroweak symmetry breaking via topological sectors.
A
bstract
We explore a new mechanism for reproducing the Dark Matter (DM) abundance: scatterings of one DM particle on light Standard Model particles. Strong bounds on its decays can be satisfied if ...DM undergoes freeze-in and has a mass around or below the pion mass. This happens, for example, in theories with a right-handed neutrino interacting with charged fermions through a leptoquark exchange. These leptoquarks can be linked to the ones motivated by the
B
-physics anomalies if assumptions about the flavour structure are made. DM signals are unusual, with interesting possibilities for direct and indirect detection. Achieving thermal freeze-out instead requires models with more than one DM flavour, and couplings parametrically smaller than what needed by the usual pair annihilations.
A
bstract
We critically analyze the body of results that hints to the existence of New Physics from possible violations of lepton universality observed by the LHCb experiment in the
μ/e
ratios
R
K
...and
R
K
∗
to the
g −
2 lepton anomalies. The analysis begins with a theoretical, in depth, study of the
μ/e
ratios
R
K
and
R
K
∗
as well as the process
B
s
→ μ
+
μ
−
. Here we consider the impact of complex Wilson coefficients and derive constraints on their imaginary and real parts. We then move to a comprehensive comparison with experimental results. We show that, by fitting a single Wilson coefficient, the deviations from the Standard Model are at the 4
.
7
σ
level when including only the hadronic insensitive observables while it increases to 6
.
1
σ
when including also the hadronic sensitive ones. When switching on all relevant Wilson coefficients and combining both hadronic sensitive and insensitive data into the fit, the deviation from the Standard Model peaks at 7
.
2
σ
and decreases at the 4
.
9
σ
level if we assume that the central values of
R
K
and
R
K
∗
are taken to be unity. We further estimate other unaccounted for SM contributions and show that their inclusion still requires New Physics to fit the data. We then introduce the
g −
2 lepton anomalies as well as the most recent
W
-mass results. Different theoretical models are considered that can explain the discrepancies from the Standard Model. In the final part of our work we estimate the impact of the forthcoming data from LHCb (coming from LHC Run3) and Belle II, when it will have accumulated about 5
ab
−
1
.
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