HEP Phenomenology·hep-ph
13 papers—10 primary·3 cross-listed·reconstructed*
We study a Light Shinning Through the wall type setup with microwave cavities, where the regeneration cavity has a moving boundary condition oscillating harmonically. We find a parametric resonance that could enhance the probability conversion between Weakly Interacting Slim Particles and photons by several orders of magnitude.
Matthew R. Buckley🇺🇸 · David Feld🇺🇸
Any form of dark matter which was in thermal equilibrium with the Standard Model in the early Universe must have some annihilation mechanism in order to avoid overclosure. In general, such models are now constrained by the negative experimental results from colliders, direct detection, and indirect detection, all of which are capable of probing interactions at the approximate strength suggested by a thermal cross section. It is timely to consider what scenarios of thermal dark matter which are still viable. In this paper we consider a class of dark matter models which is designed to avoid many of the current constraints: Majorana dark matter coupling to the Standard Model through leptophilic singlet scalars and pseudoscalars. We show that requiring realistic electroweak symmetry breaking generically forces the mediators to couple with quarks, allowing these models to be constrained by the current experimental data. We find that -- barring fine-tuning -- this type of thermal dark matter is excluded by a combination of direct and indirect detection for masses below GeV. Heavier dark matter is still viable, but in principle visible via its indirect detection signature.
Tatsuo Kobayashi🇯🇵 · Shohei Uemura🇯🇵 · Junji Yamamoto🇯🇵
We investigate the axion inflation model derived by poly-instanton effects in type II superstring theories. Poly-instanton effects are instanton effects corrected by another instanton and it can generate the modulus-axion potential with the double exponential function. Although the axion has a period of small value, this potential can have a flat region because its derivatives are exponentially suppressed by non-perturbative effects. From the view point of the cosmic inflation, such potential is interesting. In this paper, we numerically study the possibilities for realizing the cosmic inflation. We also study their spectral index and other cosmological observables, numerically.
Michal Czakon🇩🇪 · David Heymes🇬🇧 · Alexander Mitov🇬🇧 · Davide Pagani🇩🇪 · Ioannis Tsinikos🇧🇪 · Marco Zaro🇫🇷
In this work we present for the first time predictions for top-quark pair differential distributions at the LHC at NNLO QCD accuracy and including EW corrections. For the latter we include not only contributions of , but also those of order and . Besides providing phenomenological predictions for all main differential distributions with stable top quarks, we also study the following issues. 1) The effect of the photon PDF on top-pair spectra: we find it to be strongly dependent on the PDF set used -- especially for the top distribution. 2) The difference between the additive and multiplicative approaches for combining QCD and EW corrections: with our scale choice, we find relatively small differences between the central predictions, but reduced scale dependence within the multiplicative approach. 3) The potential effect from the radiation of heavy bosons on inclusive top-pair spectra: we find it to be, typically, negligible.
M. Sruthilaya🇮🇳 · Rukmani Mohanta🇮🇳 · Sudhanwa Patra🇮🇳
We demonstrate how a class of non-supersymmetric GUT with asymmetric left-right theory and Pati-Salam theory as intermediate symmetry breaking steps leads to successful gauge coupling unification satisfying proton decay constraints. The motivation behind this work is two fold: firstly to study the renormalization group evolution equations for gauge couplings by keeping right-handed neutral gauge boson around LHC energy range leading interesting dilepton searches at collider while fixing charge partner of the gauge boson at very high scale; secondly to explain neutrino masses and associated lepton number violating process like neutrinoless double beta decay in three possible cases depending on how breaks down to SM. We include one extra fermion singlet per generation in order to implement gauged extended seesaw where light neutrino mass is governed by natural type-II seesaw mechanism whereas type-I seesaw contribution is exactly canceled out. Since light neutrino mass formula is independent of Dirac neutrino mass matrix, the value of Dirac neutrino mass is taken to be up-type quark mass matrix which is a characteristics of Pati-Salam symmetry relating quarks with leptons. We present analytic relation for effective Majorana mass parameter and corresponding half-life arising from new physics contributions due to purely left-handed currents through exchange of heavy right-handed neutrinos and sterile neutrinos. We numerically estimate effective Majorana mass parameter and half-life vs. lightest neutrino mass and derive lower bound on lightest neutrino mass by saturating with experimental bounds like GERDA Phase-II, KamLANDZen and EXO.
Umberto D'Alesio🇮🇹 · Francesco Murgia🇮🇹 · Cristian Pisano🇮🇹 · Pieter Taels🇧🇪
We present a study of transverse single-spin asymmetries (SSAs) in and within the framework of the generalized parton model (GPM), which includes both spin and transverse momentum effects, and show how they can provide useful information on the still almost unknown gluon Sivers function. Moreover, by adopting a modified version of this model, named color gauge invariant (CGI) GPM, we analyze the impact of the initial- and final-state interactions on our predictions. As a consequence, we find that these two processes are sensitive to different gluon Sivers functions, which can be expressed as linear combinations of two distinct, universal gluon distributions. We therefore define proper observables which could allow for a separate extraction of these two independent Sivers functions. At the same time, we show how it would be possible to discriminate between the GPM and the CGI-GPM approaches by comparing the corresponding estimates of SSAs with present and future experimental results at RHIC.
Rhorry Gauld🇨🇭 · Juan Rojo🇳🇱 · Emma Slade🇬🇧
We review the constraints on the small-x gluon PDF that can be derived by exploiting the forward D meson production data from the LHCb experiment at and 13 TeV. We then discuss the phenomenological implications of the resulting improved small-x gluon for ultra-high energy astrophysics, in particular neutrino telescopes, as well as for the proposed Future Circular Collider (FCC) with TeV. We illustrate how at the FCC even electroweak scale cross-sections can become sensitive to the small-x region of the quark and gluon PDFs, and then demonstrate how the addition of the LHCb heavy meson production measurements leads to a reduction of PDF uncertainties for various benchmark cross-sections.
Arghya Choudhury🇬🇧 · Kamila Kowalska🇵🇱 · Leszek Roszkowski🇵🇱 · Enrico Maria Sessolo🇵🇱 · Andrew J. Williams🇵🇱
Using the existing simplified model framework, we build several dark matter models which have suppressed spin-independent scattering cross section. We show that the scattering cross section can vanish due to interference effects with models obtained by simple combinations of simplified models. For weakly interacting massive particle (WIMP) masses 10 GeV, collider limits are usually much weaker than the direct detection limits coming from LUX or XENON100. However, for our model combinations, LHC analyses are more competitive for some parts of the parameter space. The regions with direct detection blind spots can be strongly constrained from the complementary use of several Large Hadron Collider (LHC) searches like mono-jet, jets + missing transverse energy, heavy vector resonance searches, etc. We evaluate the strongest limits for combinations of scalar + vector, "squark" + vector, and scalar + "squark" mediator, and present the LHC 14 TeV projections.
A. N. Ioannisian🇦🇲 · A.Yu. Smirnov🇩🇪
Attenuation effect is the effect of weakening of contributions to the oscillation signal from remote structures of matter density profile. The effect is a consequence of integration over the neutrino energy within the energy resolution interval. Structures of a density profile situated at distances larger than the attenuation length, , are not "seen". We show that the origins of attenuation are (i) averaging of oscillations in certain layer(s) of matter, (ii) smallness of matter effect: , where is the matter potential, and (iii) specific initial and final states on neutrinos. We elaborate on the graphic description of the attenuation which allows us to compute explicitly the effects in the order for various density profiles and oscillation channels. The attenuation in the case of partial averaging is described. The effect is crucial for interpretation of oscillation data and for the oscillation tomography of the Earth with low energy (solar, supernova, atmospheric, {\it etc.}) neutrinos.
The planned upgrade of the CMS detector for the High Luminosity LHC allows to find tracks in the silicon tracker for every single LHC collision and use them in the first level (hardware) trigger decision. So far, studies by CMS collaboration concentrated on the maintaining the overall trigger performance in the punishing pile up environment. We argue that the potential capabilities of the track trigger are much wider, and may offer groundbreaking opportunities for new physics searches. As an example, and to facilitate community discussion, we use a simple toy simulation to study rare Higgs decays into new particles with lifetime of order of a few mm.
Ya Lu🇨🇳 · Chen Chen🇧🇷 · Craig D. Roberts🇺🇸 · Jorge Segovia🇩🇪 · Shu-Sheng Xu🇨🇳 · Hong-Shi Zong🇨🇳
We describe a calculation of the spectrum of flavour-SU(3) octet and decuplet baryons, their parity partners, and the radial excitations of these systems, made using a symmetry-preserving treatment of a vector-vector contact interaction as the foundation for the relevant few-body equations. Dynamical chiral symmetry breaking generates nonpointlike diquarks within these baryons and hence, using the contact interaction, flavour-antitriplet scalar, pseudoscalar and vector, and flavour-sextet axial-vector quark-quark correlations can all play an active role. The model yields reasonable masses for all systems studied, and Faddeev amplitudes for ground states and associated parity partners that sketch a realistic picture of their internal structure: ground-state, even parity baryons are constituted, almost exclusively, from like-parity diquark correlations; but orbital angular momentum plays an important role in the rest-frame wave functions of odd-parity baryons, whose Faddeev amplitudes are dominated by odd-parity diquarks.
Asier Lopez-Eiguren🇪🇸 · Joanes Lizarraga🇪🇸 · Mark Hindmarsh🇫🇮 · Jon Urrestilla🇪🇸
We present the first CMB power spectra from numerical simulations of the global O(N) linear -model with N = 2,3, which have global strings and monopoles as topological defects. In order to compute the CMB power spectra we compute the unequal time correlators (UETCs) of the energy-momentum tensor, showing that they fall off at high wave number faster than naive estimates based on the geometry of the defects, indicating non-trivial (anti-)correlations between the defects and the surrounding Goldstone boson field. We obtain source functions for Einstein-Boltzmann solvers from the UETCs, using a recent method that improves the modelling at the radiation- matter transition. We show that the interpolation function that mimics the transition is similar to other defect models, but not identical, confirming the non-universality of the interpolation function. The CMB power spectra for global strings and monopoles have the same overall shape as those obtained using the non-linear -model approximation, which is well captured by a large-N calculation. However, the amplitudes are larger than the large-N calculation predict, and in the case of global strings much larger: a factor of 20 at the peak. Finally we compare the CMB power spectra with the latest CMB data to put limits on the allowed contribution to the temperature power spectrum at multipole = 10 of 1.7% for global strings and 2.4% for global monopoles. These limits correspond to symmetry-breaking scales of 2.9x1015 GeV (6.3x1014 GeV with the expected logarithmic scaling of the effective string tension between the simulation time and decoupling) and 6.4x1015 GeV respectively. The bound on global strings is a significant one for the ultra-light axion scenario with axion masses ma 10-28 eV. These upper limits indicate that gravitational wave from global topological defects will not be observable at the GW observatory LISA.
Daniel Kapec🇺🇸 · Malcolm Perry🇬🇧 · Ana-Maria Raclariu🇺🇸 · Andrew Strominger🇺🇸
Recently it has been shown that the vacuum state in QED is infinitely degenerate. Moreover a transition among the degenerate vacua is induced in any nontrivial scattering process and determined from the associated soft factor. Conventional computations of scattering amplitudes in QED do not account for this vacuum degeneracy and therefore always give zero. This vanishing of all conventional QED amplitudes is usually attributed to infrared divergences. Here we show that if these vacuum transitions are properly accounted for, the resulting amplitudes are nonzero and infrared finite. Our construction of finite amplitudes is mathematically equivalent to, and amounts to a physical reinterpretation of, the 1970 construction of Faddeev and Kulish.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.