130,445 research outputs found
Holographic Goldstino
No full textWe find the fingerprints of the Goldstino associated to spontaneous supersymmetry breaking in a prototype holographic model for a strongly coupled field theory. The Goldstino massless pole arises in two-point correlators of the supercurrent, due to contact terms in supersymmetry Ward identities. We show how these contact terms are obtained from the holographic renormalization of the gravitino sector, independently of the details of the bulk background solution. For completeness, we prove the existence of a family of such solutions in a simple supergravity model.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
A new experiment on
No full textIn these proceedings, we present new data for the p + 19F reaction, obtained for the 19F(p, α0)16Ogs and 19F(p, απ)16O6.05 channels. The experiment was performed at the Singletron accelerator in Catania, with proton beam energies in the 1.1-1.3 and 1.6-1.7 MeV energy regions. This allowed us to provide new data for the απ channel around 1.3 MeV projectile energy and to shed light on the ambiguities existing between previous data sets in the absolute value and in the peak shape of a particular resonance, in the α0 channel, at around 1.6 MeV projectile energy
Fusing vectors into scalars at high energy lepton colliders
No full textWe study vector boson fusion production of new scalar singlets at high energy lepton colliders. We find that CLIC has the potential to test single production cross-sections of a few tens of attobarns in di-Higgs and di-boson final states. In models with a sizeable singlet-Higgs mixing, these values correspond to a precision in Higgs couplings of order 0.1% or better. We compare our sensitivities with those of the LHC and interpret our results in well-motivated models like the Twin Higgs, the NMSSM and axion-like particles. Looking forward to even higher energy machines, we show that the reach of muon colliders like LEMMA or MAP overcomes the one of future hadron machines like FCC-hh. We finally study the pair production of the new scalar singlets via an off-shell Higgs. This process does not vanish for small mixings and will constitute a crucial probe of models generating a first order electro-weak phase transition
The supercooling window at weak and strong coupling
No full textSupercooled first order phase transitions are typical of theories where conformal symmetry is predominantly spontaneously broken. In these theories the fate of the flat scalar direction is highly sensitive to the size and the scaling dimension of the explicit breaking deformations. For a given deformation, the coupling must lie in a particular region to realize a supercooled first order phase transition. We identify the supercooling window in weakly coupled theories and derive a fully analytical understanding of its boundaries. Mapping these boundaries allows us to identify the deformations enlarging the supercooling window and to characterize their dynamics analytically. For completeness we also discuss strongly coupled conformal field theories with an holographic dual, where the complete characterization of the supercooling window is challenged by calculability issues
Unveiling dark fifth forces with linear cosmology
No full textWe initiate the exploration of the cosmology of dark fifth forces: new forces
acting solely on Dark Matter. We focus on long range interactions which lead to
an effective violation of the Equivalence Principle on cosmological scales
today. At the microscopic level, the dark fifth force can be realized by a
light scalar with mass smaller than the Hubble constant today () coupled to Dark Matter. We study the behavior of the
background cosmology and linear perturbations in such a Universe. At the
background level, the new force modifies the evolution of the Dark Matter
energy density and thus the Hubble flow. At linear order, it modifies the
growth of matter perturbations and generates relative density and velocity
perturbations between Dark Matter and baryons that grow over time. We derive
constraints from current CMB and BAO data, bounding the strength of the dark
fifth force to be less than a percent of gravity. These are the strongest
constraints to date. We present potential implications of this scenario for the
Hubble tension and discuss how our results are modified if the light scalar
mediator accounts for the observed density of the Dark Energy. Finally, we
comment on the interplay between our constraints and searches for violations of
the Equivalence Principle in the visible sector.Comment: 54 pages, 15 figures. v2: revision of Section 6, now including atomic
clock constraints; added Table 1 summarizing the main results; extended
discussion of BAO; added several references. Matches version to appear in
JCAP. v3: fixed some incorrect equations, all results and figures unaffected.
Updated with latest experimental constraints from MICROSCOPE and atomic
clock
Nuclear structure effects on over-barrier fusion reactions investigated with a new phenomenological model
No full textWe investigate the occurrence of nuclear structure effects in the cross section of heavy-ion fusion reactions at energies above the Coulomb barrier. To this end, we initially develop a universal phenomenological model capable to reproduce, with an unprecedented accuracy, all previously published experimental fusion excitation functions with a few parameters. The new model, which foresees exclusively charge, mass, and energy of the colliding systems, shows a clear saturation of the critical angular momentum and avoids analytical non-regularities. The predictions of the newly developed model are then inspected to pin down residual discrepancies with the data, which could be ascribed to the structure of the colliding systems. In this framework, we obtain the following findings: (1) for the first time, we suggest an anomaly in the optimum value of the fusion cross section for systems having nearly-zero fusion Q-values; (2) we point out the occurrence of shell closure effects in the fusion of light systems; (3) we suggest that shell effects are washed-out at relative velocities vrel≳0.07c; (4) in the higher energy part of the fusion excitation function, the cross section for colliding systems involving fluorine or neon isotopes impinging on 2p3/2-1f5/2 nuclei is suppressed, possibly due to the occurrence of α-clustering effects enhancing α-transfer reactions
R -Axion at Colliders
No full textWe study the effective theory of a generic class of hidden sectors where supersymmetry is broken together with an approximate R-symmetry at low energy. The light spectrum contains the gravitino and the pseudo-Nambu-Goldstone boson of the R-symmetry, the R-axion. We derive new model-independent constraints on the R-axion decay constant for R-axion masses ranging from GeV to TeV, which are of relevance for hadron colliders, lepton colliders, and B factories. The current bounds allow for the exciting possibility that the first sign of supersymmetry will be the R-axion. We point out its most distinctive signals, providing a new experimental handle on the properties of the hidden sector and a solid motivation for searches of axionlike particles
Closing the window on WIMP Dark Matter
No full textWe study scenarios where Dark Matter is a weakly interacting particle (WIMP) embedded in an ElectroWeak multiplet. In particular, we consider real SU(2) representations with zero hypercharge, that automatically avoid direct detection constraints from tree-level Z-exchange. We compute for the first time all the calculable thermal masses for scalar and fermionic WIMPs, including Sommerfeld enhancement and bound states formation at leading order in gauge boson exchange and emission. WIMP masses of few hundred TeV are shown to be compatible both with s-wave unitarity of the annihilation cross-section, and perturbativity. We also provide theory uncertainties on the masses for all multiplets, which are shown to be significant for large SU(2) multiplets. We then outline a strategy to probe these scenarios at future experiments. Electroweak 3-plets and 5-plets have masses up to about 16 TeV and can efficiently be probed at a high energy muon collider. We study various experimental signatures, such as single and double gauge boson emission with missing energy, and disappearing tracks, and determine the collider energy and luminosity required to probe the thermal Dark Matter masses. Larger multiplets are out of reach of any realistic future collider, but can be tested in future γ-ray telescopes and possibly in large-exposure liquid Xenon experiments
Erratum to: New axion searches at flavor factories
No full textWe correct here a mistake in the numerical prefactor of eq. (2.5) of the paper
New axion searches at flavor factories
No full textWe assess the impact of searches at flavor factories for new neutral resonances that couple to both photons and gluons. These are well motivated by “heavy axion” solutions of the strong CP problem and by frameworks addressing both Dark Matter and the Higgs hierarchy problem. We use LHCb public diphoton data around the Bs mass to derive the current best limit on these resonances for masses between 4.9 and 6.3 GeV. We estimate that a future LHCb dedicated search would test an axion decay constant of O(TeV) for axion masses in the few-to-tens of GeV, being fully complementary to the low mass ATLAS and CMS searches. We also derive the impact of BABAR searches based on ϒ decays and the future Belle-II reach.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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