1,721,068 research outputs found
Gender issues in fundamental physics: A bibliometric analysis
No full textI analyze bibliometric data about fundamental physics worldwide from 1970 to now, extracting quantitative data about gender issues. I do not find significant gender differences in hiring rates, hiring timing, career gaps and slowdowns, abandonment rates, citation, and self-citation patterns. Furthermore, various bibliometric indicators (number of fractionally counted papers, citations, etc.) exhibit a productivity gap at hiring moments, at career level, and without integrating over careers. The gap persists after accounting for confounding factors and manifests as an increasing fraction of male authors going from average to top authors in terms of bibliometric indices, with a quantitative shape that can be fitted by higher male variability
Dark Matter interpretation of the neutron decay anomaly
No full textWe add to the Standard Model a new fermion χ with minimal baryon number 1/3. Neutron decay n → χχχ into non-relativistic χ can account for the neutron decay anomaly, compatibly with bounds from neutron stars. χ can be Dark Matter, and its cosmological abundance can be generated by freeze-in dominated at T ∼ mn. The associated processes n → χχχγ, hydrogen decay H → χχχν(γ) and DM-induced neutron disappearance χ ̄ n → χχ(γ) have rates below experimental bounds and can be of interest for future experiments
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No full textCosmological constant: Relaxation vs multiverse
Full text linkWe consider a scalar field with a bottom-less potential, such as g3φ, finding that cosmologies unavoidably end up with a crunch, late enough to be compatible with observations if g≲1.2H02/3MPl1/3. If rebounces avoid singularities, the multiverse acquires new features; in particular probabilities avoid some of the usual ambiguities. If rebounces change the vacuum energy by a small enough amount, this dynamics selects a small vacuum energy and becomes the most likely source of universes with anthropically small cosmological constant. Its probability distribution could avoid the gap by 2 orders of magnitude that seems left by standard anthropic selection
Relaxing the Higgs mass and its vacuum energy by living at the top of the potential
No full textWe consider an ultralight scalar coupled to the Higgs in the presence of heavier new physics. In the electroweak broken phase the Higgs gives a tree-level contribution to the light-scalar potential, while new physics contributes at loop level. Thereby, the theory has a cosmologically metastable phase where the light scalar is around the top of its potential, and the Higgs is a loop factor lighter than new physics. Such regions with precarious naturalness are anthropically and environmentally selected, as regions with heavier Higgs crunch quickly. We expect observable effects of rolling in the dark-energy equation of state. Furthermore, vacuum energies up to the weak scale can be canceled down to anthropically small values
Electron and muon electric dipoles in supersymmetric scenarios
No full textWe study if a sizeable muon electric dipole can arise in supersymmetric frameworks able to account for the tight experimental bounds on sfermion masses, like an appropriate flavor symmetry, or like a flavor-blind mechanism of SUSY breaking (in presence of radiative corrections charchteristic of GUT models, or due to Yukawa couplings of neutrinos in see-saw models). In some cases it is possible to evade the naive scaling d_mu/d_e = m_mu/m_e and obtain a d_mu as large as 10^{-22--23} e cm. In most cases d_mu is around 10^{-24--25} e cm and (d_mu/d_e)/(m_mu/m_e) is only slightly different from one: this ratio contains interesting informations on the source of the dipoles and on the texture of the lepton Yukawa matrix. We also update GUT predictions for mu --> e gamma and related processes.We study if a sizeable muon electric dipole can arise in supersymmetric frameworks able to account for the tight experimental bounds on sfermion masses, like an appropriate flavor symmetry, or like a flavor-blind mechanism of SUSY breaking (in presence of radiative corrections charchteristic of GUT models, or due to Yukawa couplings of neutrinos in see-saw models). In some cases it is possible to evade the naive scaling and obtain a as large as e cm. In most cases is around e cm and ()/() is only slightly different from one: this ratio contains interesting informations on the source of the dipoles and on the texture of the lepton Yukawa matrix. We also update GUT predictions for and related processes.We study if a sizeable muon electric dipole can arise in supersymmetric frameworks able to account for the tight experimental bounds on sfermion masses, like an appropriate flavor symmetry, or like a flavor-blind mechanism of SUSY breaking (in presence of radiative corrections charchteristic of GUT models, or due to Yukawa couplings of neutrinos in see-saw models). In some cases it is possible to evade the naive scaling and obtain a as large as e cm. In most cases is around e cm and ()/() is only slightly different from one: this ratio contains interesting informations on the source of the dipoles and on the texture of the lepton Yukawa matrix. We also update GUT predictions for and related processes.We study if a sizeable muon electric dipole can arise in supersymmetric frameworks able to account for the tight experimental bounds on sfermion masses, like an appropriate flavor symmetry, or like a flavor-blind mechanism of SUSY breaking (in presence of radiative corrections charchteristic of GUT models, or due to Yukawa couplings of neutrinos in see-saw models). In some cases it is possible to evade the naive scaling d μ / d e = m μ / m e and obtain a d μ as large as 10 −22÷23 e cm . In most cases d μ is around 10 −24÷25 e cm and ( d μ / d e )/( m μ / m e ) is only slightly different from one: this ratio contains interesting informations on the source of the dipoles and on the texture of the lepton Yukawa matrix. We also update GUT predictions for μ → eγ and related processes
Electric dipole moments from Yukawa phases in supersymmetric theories
No full textWe study quark and electron EDMs generated by Yukawa couplings in supersymmetric models with different gauge groups, using the EDM properties under flavour transformations. In the MSSM (or if soft terms are mediated below the unification scale) the one-loop contributions to the neutron EDM are smaller than in previous computations based on numerical methods, although increasing as tan(3) beta. A neutron EDM close to the experimental limits can be generated in SU(5), if tan beta is large, through the u-quark EDM d(u), proportional to tan(4) beta. This effect has to be taken into account also in SO(10) with large tan beta, where d(u) is comparable to the d quark EDM, proportional to tan beta. (C) 1997 Elsevier Science B.V
Minimal Dark Matter bound states at future colliders
No full textThe 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
The collider landscape: which collider for establishing the SM instability?
Full text linkCapabilities of future colliders are usually discussed assuming specific hypothetical new physics. We consider the opposite possibility: that no new physics is accessible, and we want to learn if the unnatural Standard Model is part of a vast landscape. We argue that a main step in this direction would be establishing the possible instability scale of the Higgs potential. This primarily needs reducing the uncertainty on the strong coupling and on the top quark mass. We show that the top quark mass can be measured well enough via a tt ̄ threshold scan with low 1033 cm−2sec−1 luminosity, that seems achievable at a ‘small’ e+e− collider in the LEP tunnel, or at a muon collider demonstrator
Towards leptogenesis at NLO: The right-handed neutrino interaction rate
No full textWe compute quantum and thermal corrections to the right-handed neutrino interaction rate in the early universe at next-to-leading order in all the relevant SM couplings (gauge, top Yukawa and higgs couplings). Previous computations considered 2 -> 2 scatterings, finding infra-red divergences. The KLN theorem demands that infra-red divergences cancel in the full result: after adding 1 -> 3 and one-loop virtual corrections that enter at the same order we find a simple result
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