Wed·Jan 20, 2021Wednesday·January 20, 2021

1. 01*

   Understanding the $K^{\ast }/K$ ratio in heavy ion collisions

   C. Le Roux🇧🇷 · F. S. Navarra🇧🇷 · L. M. Abreu🇧🇷

   We study the $K^{\ast }$ meson dissociation in heavy ion collisions during the hadron gas phase. We use the production and absorption cross sections of the $K^{\ast }$ and $K$ mesons in a hadron gas, which were calculated in a previous work. We compute the time evolution of the $K^{\ast }$ abundance and the $K^{\ast }/K$ ratio during the hadron gas phase. Assuming a Bjorken type cooling and using an empirical relation between the freeze-out temperature and the central multiplicity density, we are able to write $K^{\ast }/K$ as a function of ($dN/d\eta (\eta =0)$). The obtained function is in very good agreement with recent experimental data.

   hep-phPLB(2021)·23 citations
2. 02*

   Thermodynamical phases in a PNJL model at zero temperature

   Odilon A. Mattos🇧🇷 · Tobias Frederico🇧🇷 · Odilon Lourenço🇧🇷

   The confinement/deconfinement transition described the Polyakov-Nambu-Jona-Lasinio (PNJL) model is extended to be operative at zero temperature regime. In this study, the scalar and vector channel interaction strengths of the original PNJL model are modified by introducing a dependence on the traced Polyakov loop. In such a way the effective interactions depend on the quark phase and in turn provides a backreaction of the quarks to the gluonic sector, also at zero temperature. On general grounds from quantum chromodynamics this is an expected feature. The thermodynamics of the extended model (PNJL0) is studied in detail. It presents along with a suitable choice of the Polyakov potential, a first order confined/deconfined quark phase transition even at $T=0$. We also show that the vector channel plays an important role in order to allow $\Phi \ne 0$ solutions for the PNJL0 model. Furthermore, the sensitivity of the combined quarkyonic and deconfinement phases to the vector interaction strength and the proposed parametrization of the Polyakov-loop potential at $T=0$ allowed to set a window for the bulk values of the relevant parameters.

   hep-phEPJC(2021)·14 citations
3. 03*

   Implementing Asymmetric Dark Matter and Dark Electroweak Baryogenesis in a Mirror Two-Higgs-Doublet Model

   Alexander C. Ritter🇦🇺 · Raymond R. Volkas🇦🇺

   Models of asymmetric dark matter (ADM) seek to explain the apparent coincidence between the present-day mass densities of visible and dark matter, ${\Omega }_{\mathrm{DM}}\simeq 5{\Omega }_{\mathrm{VM}}$. However, most ADM models only relate the number densities of visible and dark matter without motivating the similar particle masses. We expand upon a recent work that obtained a natural mass relationship in a mirror matter ADM model with two Higgs doublets in each sector, by looking to implement dark electroweak baryogenesis as the means of asymmetry generation. We explore two aspects of the mechanism: the nature of the dark electroweak phase transition, and the transfer of particle asymmetries between the sectors by the use of portal interactions. We find that both aspects can be implemented successfully for various regions of the parameter space. We also analyse one portal interaction -- the neutron portal -- in greater detail, in order to satisfy the observational constraints on dark radiation.

   hep-phPRD(2021)·22 citations
4. 04*

   Central elastic scattering

   S.M. Troshin🇷🇺 · N.E. Tyurin🇷🇺

   We comment on phase selection of the scattering amplitude, emphasizing that the elastic overlap function should have a central impact parameter profile at high energies and highlighting the role of the reflective scattering mode at the LHC energies. Emerging problems with the use of peripheral impact parameter dependence of the elastic overlap function are explicitly indicated. Their solution is an elimination of the phases connected to peripheral form of the elastic overlap function. Contrary, we adhere to a relative peripheral form of the {\it inelastic} overlap function with an additional new feature of a maximum at nonzero value of the impact parameter at the highest energies. Phenomenologically, the dynamics of hadron scattering is motivated by a hadron structure with a hard central core presence.

   hep-phPLB(2021)·7 citations
5. 05*

   Equal-time kinetic equations in a rotational field

   Shile Chen🇨🇳 · Ziyue Wang🇨🇳 · Pengfei Zhuang🇨🇳

   We investigate quantum kinetic theory for a massive fermion system under a rotational field. From the Dirac equation in curved space we derive the complete set of kinetic equations for the spin components of the covariant and equal-time Wigner functions. While the particles are no longer on a mass shell in general case due to the rotation-spin coupling, there are always only two independent components, which can be taken as the number and spin densities. With the help from the off-shell constraint we obtain the closed transport equations for the two independent components in classical limit and at quantum level. The classical rotation-orbital coupling controls the dynamical evolution of the number density, but the quantum rotation-spin coupling explicitly changes the spin density.

   hep-phCPC(2022)·7 citations
6. 06*

   Modelling of top quark decays in $t\bar{t}\gamma$ production at the LHC

   Malgorzata Worek🇩🇪

   In this proceedings we briefly report on the state-of-the-art NLO QCD computation for the $pp\to t\bar{t}\gamma$ process in the di-lepton channel. We describe higher-order corrections to the $e^{+}{\nu }_e{\mu }^{-}{\bar{\nu }}_{\mu }b\bar{b}\gamma$ final state at the LHC with $\sqrt{s}=13$ TeV. Off-shell top quarks, double-, single- as well as non-resonant top-quark contributions along with all interference effects are consistently incorporated at the matrix element level. Results are presented in the form of fiducial integrated and differential cross sections. The impact of top quark modelling is scrutinised by an explicit comparison with the results in the narrow-width approximation. Both types of predictions are now available in the HELAC-NLO framework.

   hep-ph0 citations
7. 07*

   Time Evolution of Lepton Number Carried by Majorana Neutrinos

   Apriadi Salim Adam🇮🇩 · Nicholas J. Benoit🇯🇵 · Yuta Kawamura🇯🇵 · Yamato Matsuo🇯🇵 · Takuya Morozumi🇯🇵 · Yusuke Shimizu🇯🇵 · Yuya Tokunaga🇯🇵 · Naoya Toyota🇯🇵

   We revisit the time evolution of the lepton family number for a SU(2) doublet consisting of a neutrino and a charged lepton. The lepton family number is defined through the weak basis of the SU(2) doublet, where the charged lepton mass matrix is real and diagonal. The lepton family number carried by the neutrino is defined by the left-handed current of the neutrino family. For this work we assume the neutrinos have Majorana mass. This Majorana mass term is switched on at time $t=0$ and the lepton family number is evolved. Since the operator in the flavor eigenstate is continuously connected to that of the mass eigenstate, the creation and annihilation operators for the two eigenstates are related to each other. We compute the time evolution of all lepton family numbers by choosing a specific initial flavor eigenstate for a neutrino. The evolution is studied for relativistic and nonrelativistic neutrinos. The nonrelativistic region is of particular interest for the Cosmic Neutrino Background predicted from big bang models. In that region we find the lepton family numbers are sensitive to Majorana and Dirac phases, the absolute mass, and mass hierarchy of neutrinos.

   hep-phhep-exPTEP(2021)·8 citations
8. 08*

   Charming ALPs

   Adrian Carmona🇪🇸 · Christiane Scherb🇩🇪 · Pedro Schwaller🇩🇪

   Axion-like particles (ALPs) are ubiquitous in models of new physics explaining some of the most pressing puzzles of the Standard Model. However, until relatively recently, little attention has been paid to its interplay with flavour. In this work, we study in detail the phenomenology of ALPs that exclusively interact with up-type quarks at the tree-level, which arise in some well-motivated ultra-violet completions such as QCD-like dark sectors or Froggatt-Nielsen type models of flavour. Our study is performed in the low-energy effective theory to highlight the key features of these scenarios in a model independent way. We derive all the existing constraints on these models and demonstrate how upcoming experiments at fixed-target facilities and the LHC can probe a vast region of the parameter space, which is currently not excluded by cosmological and astrophysical bounds. We also emphasize how a future measurement of the currently unavailable meson decay $D\to \pi +\mathrm{invisible}$ could complement these upcoming searches and help to probe a large unexplored region of their parameter space.

   hep-phhep-exJHEP(2021)·60 citations
9. 09*

   Combined Constraints on First Generation Leptoquarks

   Andreas Crivellin · Dario Müller · Luc Schnell

   In this article we perform a combined analysis of low energy precision constraints and LHC searches for leptoquarks which couple to first generation fermions. Considering all ten leptoquark representations, five scalar and five vector ones, we study at the precision frontier the constraints from $K\to \pi \nu \nu$, $K\to \pi e^{+}{e}^{-}$, $K^0-{\bar{K}}^0$ and $D^0-{\bar{D}}^0$ mixing, as well as from experiments searching for parity violation (APV and QWEAK). We include LHC searches for $s$-channel single resonant production, pair production and Drell-Yan-like signatures of leptoquarks. Interestingly, we find that the recent non-resonant di-lepton analysis of ATLAS provides stronger bounds than the resonant searches recasted so far to constrain $t$-channel production of leptoquarks. Taking into account all these bounds, we observe that none of the leptoquark representations can address the so-called "Cabibbo angle anomaly" via a direct contribution to super-allowed beta decays.

   hep-phhep-exnucl-exnucl-thPhys. Rev. D 103, 115023 (2021)
10. 10*

    A unified hoop conjecture for black holes and horizonless compact stars

    Yan Peng🇨🇳

    We propose a unified version of hoop conjecture valid for various black holes and horizonless compact stars. This conjecture is expressed by the mass to circumference ratio $4\pi M_{in}/C⩽1$, where C is the circumference of the smallest ring that can engulf the object in all azimuthal directions and $M_{in}$ is the mass within the engulfing sphere.

    ↳ gr-qchep-phhep-th2 citations
11. 11*

    Low-Redshift Constraints on Covariant Canonical Gauge Theory of Gravity

    David Benisty🇮🇱 · David Vasak🇩🇪 · Johannes Kirsch🇩🇪 · Jurgen Struckmeier🇩🇪

    Constraints on the Covariant Canonical Gauge Gravity (CCGG) theory from low-redshift cosmology are studied. The formulation extends Einstein's theory of General Relativity (GR) by a quadratic Riemann-Cartan term in the Lagrangian, controlled by a "deformation" parameter. In the Friedman universe this leads to an additional geometrical stress energy and promotes, due to the necessary presence of torsion, the cosmological constant to a time-dependent function. The MCMC analysis of the combined data sets of Type Ia Supernovae, Cosmic Chronometers and Baryon Acoustic Oscillations yields a fit that is well comparable with the $\Lambda$CDM results. The modifications implied in the CCGG approach turn out to be subdominant in the low-redshift cosmology. However, a non-zero spatial curvature and deformation parameter are shown to be consistent with observations.

    ↳ gr-qcastro-ph.COhep-phEPJC(2021)·7 citations
12. 12*

    Double peaks of gravitational wave spectrum induced from inflection point inflation

    Tie-Jun Gao🇨🇳 · Xiu-Yi Yang🇨🇳

    We investigate the possibility to induce double peaks of gravitational wave(GW) spectrum from primordial scalar perturbations in inflationary models with three inflection points.Where the inflection points can be generated from a polynomial potential or generated from Higgs like ${\varphi }^4$ potential with the running of quartic coupling.In such models, the inflection point at large scales predicts the scalar spectral index and tensor-to-scalar ratio consistent with current CMB constraints, and the other two inflection points generate two large peaks in the scalar power spectrum at small scales, which can induce GWs with double peaks energy spectrum. We find that for some choices parameters the double peaks spectrum can be detected by future GW detectors, and one of the peaks around $f\simeq 10^{-9}\sim 10^{-8}$Hz can also explain the recent NANOGrav signal. Moreover, the peaks of power spectrum allow for the generation of primordial black holes, which account for a significant fraction of dark matter.

    ↳ astro-ph.COhep-phEPJC(2021)·24 citations
13. 13*

    Stokes phenomenon and gravitational particle production -- How to evaluate it in practice

    Soichiro Hashiba🇯🇵 · Yusuke Yamada🇯🇵

    We revisit gravitational particle production from the Stokes phenomenon viewpoint, which helps us make a systematic way to understand asymptotic behavior of mode functions in time-dependent background. One of our purposes of this work is to make the method more practical for evaluation of non-perturbative particle production rate. In particular, with several examples of time-dependent backgrounds, we introduce some approximation methods that make the analysis more practical. Specifically, we consider particle production in simple expanding backgrounds, preheating after $R^2$ inflation, and a transition model with smoothly changing mass. As we find several technical issues in analyzing the Stokes phenomenon of each example, we discuss how to simplify the problems while showing the accuracy of analytic estimation under the approximations we make.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2021)·37 citations
14. 14*

    On a classical solution to the Abelian Higgs model

    Noureddine Mohammedi🇫🇷

    A particular solution to the equations of motion of the Abelian Higgs model is given. The solution involves the Jacobi elliptic functions as well as the Heun functions.

    ↳ hep-thhep-ph1 citation
15. 15*

    Measurement of Branching Fraction and Search for $CP$ Violation in $B\to \varphi \varphi K$

    S. Mohanty🇮🇳 · A. B. Kaliyar🇮🇳 · V. Gaur🇺🇸 · G. B. Mohanty🇮🇳 · I. Adachi🇯🇵 · K. Adamczyk🇵🇱 · H. Aihara🇯🇵 · S. Al Said🇸🇦 · D. M. Asner🇺🇸 · H. Atmacan🇺🇸 · V. Aulchenko🇷🇺 · T. Aushev🇷🇺 and 174 other authors

    We report the measurement of branching fractions and $CP$-violation asymmetries in $B\to \varphi \varphi K$ decays based on a $711{\mathrm{fb}}^{-1}$ data sample containing $772\times 10^6$ $B\bar{B}$ events. The data were recorded at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. For $B^{+}\to \varphi \varphi K^{+}$, the branching fraction and $CP$-violation asymmetry measured below the ${\eta }_c$ threshold ($m_{\varphi \varphi }<2.85\mathrm{GeV}/c^2$) are $[3.43_{-0.46}^{+0.48}(\mathrm{stat})\pm 0.22(\mathrm{syst})]\times 10^{-6}$ and $-0.02\pm 0.11(\mathrm{stat})\pm 0.01(\mathrm{syst})$, respectively. Similarly, the branching fraction obtained for $B^0\to \varphi \varphi K^0$ below the ${\eta }_c$ threshold is $[3.02_{-0.66}^{+0.75}(\mathrm{stat})\pm 0.20(\mathrm{syst})]\times 10^{-6}$. We also measure the $CP$-violation asymmetry for $B^{+}\to \varphi \varphi K^{+}$ within the ${\eta }_c$ region ($m_{\varphi \varphi }\in [2.94,3.02]\mathrm{GeV}/c^2$) to be $+0.12\pm 0.12(\mathrm{stat})\pm 0.01(\mathrm{syst})$.

    ↳ hep-exhep-phPRD(2021)·0 citations
16. 16*

    Primordial Black Holes in the Excursion Set Theory

    Encieh Erfani🇮🇷 · Hamed Kameli🇮🇷 · Shant Baghram🇮🇷

    We study primordial black holes (PBHs) formation in the excursion set theory (EST) in a vast range of PBHs masses with and without confirmed constraints on their abundance. In this work, we introduce a new concept of the first touch in the context of EST for PBHs formation. This new framework takes into account the earlier horizon reentry of smaller masses. Our study shows that in the EST, it is possible to produce PBHs in different mass range, with enhanced power spectrum, which could make up all dark matter. We also show that in a broad blue-tilted power spectrum, the production of PBHs is dominated by smaller masses. Our analysis put an upper limit $\sim$0.1 on the amplitude of the curvature power spectrum at length scales relevant for PBHs formation.

    ↳ astro-ph.COhep-phMNRAS(2021)·11 citations
17. 17*

    5 Reasons to expect an 8 MeV line in the SN 1987A neutrino spectrum

    R. Ehrlich🇺🇸

    Evidence was previously reported for an 8 MeV neutrino line associated with SN 1987A based on an analysis of 997 events recorded in the Kamiokande-II detector on the day of the supernova. That claimed line, however, occurred at the peak of the background spectrum, and both had a similar shape, making the claim tenuous at best. Here the claim is buttressed by providing five reasons to expect such an 8 MeV neutrino line. A final section of the paper concerns the ongoing KATRIN experiment to find the neutrino mass, which might provide additional support for the line, should it validate a controversial 3 + 3 model of the neutrino masses, including a tachyonic (m2 < 0) mass.

    ↳ astro-ph.HEastro-ph.SRhep-phLHEP(2021)·1 citation

* 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.