Search results for " phenomenology"
showing 10 items of 3693 documents
Momentum distributions of cosmic relics: Improved analysis
2022
We solve coupled momentum-dependent Boltzmann equations for the phase space distribution of cosmic relic particles, without resorting to approximations of assuming kinetic equilibrium or neglecting backscattering or elastic interactions. Our method is amendable to precision numerical computations. To test it, we consider two benchmark models where the momentum dependence of dark matter distribution function is potentially important: a real singlet scalar extension near the Higgs resonance and a sterile neutrino dark matter model with a singlet scalar mediator. The singlet scalar example shows that the kinetic equilibrium may hold surprisingly well even near sharp resonances. However, the in…
Self-interacting dark matter and cosmology of a light scalar mediator
2015
We consider a fermionic dark matter candidate interacting via a scalar mediator coupled with the Standard Model through a Higgs portal. We consider general setting including both scalar and pseudoscalar interactions between the scalar and fermion, and illustrate the relevant features for dark matter abundance, direct search limits and collider constraints. The case where dark matter has a self-interaction strength $\left\langle \sigma_V \right\rangle/m_\psi \sim 0.1-1 \,\mathrm{cm}^2/\mathrm{g}$ is strongly constrained, in particular by the Big Bang Nucleosynthesis. We show that these constraints can be alleviated by introducing a new light sterile neutrino $N$. The allowed region for the e…
Orbital angular momentum parton distributions in quark models
1999
At the low energy, {\sl hadronic}, scale we calculate Orbital Angular Momentum (OAM) twist-two parton distributions for the relativistic MIT bag model and for non-relativistic quark models. We reach the scale of the data by leading order evolution in perturbative QCD. We confirm that the contribution of quarks and gluons OAM to the nucleon spin grows with $Q^2$, and it can be relevant at the experimental scale, even if it is negligible at the hadronic scale, irrespective of the model used. The sign and shape of the quark OAM distribution at high $Q^2$ may depend strongly on the relative size of the OAM and spin distributions at the hadronic scale. Sizeable quark OAM distributions at the had…
Cubic color charge correlator in a proton made of three quarks and a gluon
2022
The three point correlation function of color charge densities is evaluated explicitly in light cone gauge for a proton on the light cone. This includes both $C$-conjugation even and odd contributions. We account for perturbative corrections to the three-quark light cone wave function due to the emission of an internal gluon which is not required to be soft. We verify the Ward identity as well as the cancellation of UV divergences in the sum of all diagrams so that the correlator is independent of the renormalization scale. It does, however, exhibit the well known soft and collinear singularities. The expressions derived here provide the $C$-odd contribution to the initial conditions for hi…
Stronger C -odd color charge correlations in the proton at higher energy
2023
The non-forward eikonal scattering matrix for dipole-proton scattering at high energy obtains an imaginary part due to a $C$-odd three gluon exchange. We present numerical estimates for the perturbative Odderon amplitude as a function of dipole size, impact parameter, their relative azimuthal angle, and light-cone momentum cutoff $x$. The proton is approximated as $\psi_\mathrm{qqq}|qqq\rangle + \psi_\mathrm{qqqg}|qqqg\rangle$, where $\psi_\mathrm{qqq}$ is a non-perturbative three quark model wave function while the gluon emission is computed in light-cone perturbation theory. We find that the Odderon amplitude increases as $x$ decreases from 0.1 to 0.01. At yet lower $x$, the reversal of t…
Review of proton and nuclear shape fluctuations at high energy
2020
Determining the inner structure of protons and nuclei in terms of their fundamental constituents has been one of the main tasks of high energy nuclear and particle physics experiments. This quest started as a mapping of the (average) parton densities as a function of longitudinal momentum fraction and resolution scale. Recently, the field has progressed to more differential imaging, where one important development is the description of the event-by-event quantum fluctuations in the wave function of the colliding hadron. In this Review, recent developments on the extraction of proton and nuclear transverse geometry with event-by-event fluctuations from collider experiments at high energy is …
Highly occupied gauge theories in 2 + 1 dimensions : a self-similar attractor
2019
Motivated by the boost-invariant Glasma state in the initial stages in heavy-ion collisions, we perform classical-statistical simulations of SU(2) gauge theory in 2+1 dimensional space-time both with and without a scalar field in the adjoint representation. We show that irrespective of the details of the initial condition, the far-from-equilibrium evolution of these highly occupied systems approaches a unique universal attractor at high momenta that is the same for the gauge and scalar sectors. We extract the scaling exponents and the form of the distribution function close to this non-thermal fixed point. We find that the dynamics are governed by an energy cascade to higher momenta with sc…
Reduction and solipsism : Husserl's method of reduction and solipsism critique presented against it
2017
Työssäni tutkin Hursserlin reduktion metodia, joka on hänen kehittämänsä suuntauksen, transsendentaalisen fenomenologian, tutkimusmenetelmä. Vastaan kysymykseen, viekö reduktion metodi välttämättä solipsismiin vai ei. Lähtökohtanani on reduktion metodia vastaan esitetty ulkoinen ja sisäinen solipsismi-kritiikki. Vastaan erityisesti Hubert L. Dreyfusin esittämään ulkoiseen kritiikkiin, jonka mukaan Husserlin transsendentaalis-fenomenologinen tutkimus ajautuu välttämättä tilanteeseen, jossa ei voida esittää objektiivisia väittämiä. Analysoin myös Husserl-tutkimuksen keskusteluissa esiintyvää sisäistä kritiikkiä, jonka mukaan reduktion metodi on ongelmallinen tutkittaessa yhteisöllisyyttä ja k…
The myth of cognitive agency: subpersonal thinking as a cyclically recurring loss of mental autonomy
2013
This metatheoretical paper investigates mind wandering from the perspective of philosophy of mind. It has two central claims. The first is that, on a conceptual level, mind wandering can be fruitfully described as a specific form of mental autonomy loss. The second is that, given empirical constraints, most of what we call “conscious thought” is better analyzed as a subpersonal process that more often than not lacks crucial properties traditionally taken to be the hallmark of personal-level cognition - such as mental agency, explicit, consciously experienced goal-directedness, or availability for veto control. I claim that for roughly two thirds of our conscious life-time we do not possess …
The myth of cognitive agency: subpersonal thinking as a cyclically recurring loss of mental autonomy
2018
This metatheoretical paper investigates mind wandering from the perspective of philosophy of mind. It has two central claims. The first is that, on a conceptual level, mind wandering can be fruitfully described as a specific form of mental autonomy loss. The second is that, given empirical constraints, most of what we call “conscious thought” is better analyzed as a subpersonal process that more often than not lacks crucial properties traditionally taken to be the hallmark of personal-level cognition - such as mental agency, explicit, consciously experienced goal-directedness, or availability for veto control. I claim that for roughly two thirds of our conscious life-time we do not possess …