Mon·Jun 11, 2018Monday·June 11, 2018

1. 01*

   Probing new physics with high-multiplicity events: UHE neutrinos at air-shower detector arrays

   Yongsoo Jho🇰🇷 · Seong Chan Park🇰🇷

   Semi-classical processes such as production and decay of electroweak sphaleron in the Standard Model and also microscopic black hole in low scale gravity scenario typically involve large number of particles in final states. These large multiplicities can be distinctively seen in collisions of Ultra-high-energy (UHE) neutrinos with $E_{\nu }\ge 10^9\text{GeV}$ and nucleons in the atmosphere of the Earth. Focusing on air-shower detector array experiments including Telescope Array Experiment (TA), Pierre-Auger Observatory (Auger), we propose strategic ways to discover and analyze such events.

   hep-phPRD(2021)·11 citations
2. 02*

   Factorization of the soft gluon divergence from the dipole picture deep inelastic scattering cross sections at next-to-leading order

   B. Ducloué🇫🇷 · H. Hänninen🇫🇮 · T. Lappi🇫🇮 · Y. Zhu🇩🇪

   We use a factorization scheme analogous to one proposed for single inclusive forward hadron production to factorize the soft gluon divergence present in the deep inelastic scattering cross sections in the dipole picture at next-to-leading order (NLO). We show numerically that in this carefully constructed scheme it is possible to obtain meaningful results for the DIS cross sections at NLO, and so we are able to quantitatively study the recently derived NLO corrections to the DIS cross sections. We find that the NLO corrections can be significant and sensitive to the details of the factorization scheme used for the resummation of the large logarithms into the BK evolution equation. In the case of an approximative factorization scheme we observe a problematic behavior of the DIS cross sections similar to what has been seen with analogously factorized single inclusive cross sections.

   hep-phnucl-thPoS(2018)·0 citations
3. 03*

   The $10^{-3}$ eV Frontier in Neutrinoless Double Beta Decay

   J. T. Penedo🇮🇹 · S. T. Petcov🇮🇹

   The observation of neutrinoless double beta decay would allow to establish lepton number violation and the Majorana nature of neutrinos. The rate of this process in the case of 3-neutrino mixing is controlled by the neutrinoless double beta decay effective Majorana mass $|⟨m⟩|$. For a neutrino mass spectrum with normal ordering, which is favoured over the spectrum with inverted ordering by recent global fits, $|⟨m⟩|$ can be significantly suppressed. Taking into account updated data on the neutrino oscillation parameters, we investigate the conditions under which $|⟨m⟩|$ in the case of spectrum with normal ordering exceeds $10^{-3}(5\times 10^{-3})$ eV: $|⟨m⟩{|}_{\text{NO}}>10^{-3}(5\times 10^{-3})$ eV. We analyse first the generic case with unconstrained leptonic CP violation Majorana phases. We show, in particular, that if the sum of neutrino masses is found to satisfy $\Sigma >0.10$ eV, then $|⟨m⟩{|}_{\text{NO}}>5\times 10^{-3}$ eV for any values of the Majorana phases. We consider also cases where the values for these phases are either CP conserving or are in line with predictive schemes combining flavour and generalised CP symmetries.

   hep-phPLB(2018)·45 citations
4. 04*

   pp forward elastic scattering amplitudes at 7 and 8 TeV

   A. K. Kohara🇧🇷 · E. Ferreira🇧🇷 · T. Kodama🇧🇷 · M. Rangel🇧🇷

   We analyse the recent LHC data at 7 and 8 TeV for pp elastic scattering with special attention for the structure of the real part, which is shown to be crucial to describe the differential cross section in the forward region. We determine accurately the position of the zero of the real amplitude, which corresponds to the zero of a theorem by A. Martin.

   hep-ph0 citations
5. 05*

   Thermomagnetic properties and Bjorken expansion of hot QCD matter in a strong magnetic field

   Shubhalaxmi Rath🇮🇳 · Binoy Krishna Patra🇮🇳

   In this work we have studied the effects of an external strong magnetic field on the thermodynamic and magnetic properties of a hot QCD matter and then explored these effects on the subsequent hydrodynamic expansion of the said matter once produced in the ultrarelativistic heavy ion collisions. For that purpose, we have computed the quark and gluon self-energies up to one loop in the strong magnetic field, using the HTL approximation with two hard scales - temperature and magnetic field, which in turn compute the effective propagators for quarks and gluons, respectively. Hence the quark and gluon contributions to the free energy are obtained from the respective propagators and finally derive the equation of state (EOS) by calculating the pressure and energy density. We have found that the speed of sound is enhanced due to the presence of strong magnetic field and this effect will be later exploited in the hydrodynamics. Thereafter the magnetic properties are studied from the free energy of the matter, where the magnetization is found to increase linearly with the magnetic field, thus hints the paramagnetic behavior. The temperature dependence of the magnetization is also studied, where the magnetization is found to increase slowly with the temperature. Finally, to see how a strong magnetic field could affect the hydrodynamic evolution, we have revisited the Bjorken boost-invariant picture with our paramagnetic EOS as an input in the equation of motion for the energy-momentum conservation. We have noticed that the energy density evolves faster than in the absence of strong magnetic field, i.e. cooling becomes faster, which could have implications on the heavy-ion phenomenology. As mentioned earlier, this observation can be understood by the enhancement of the speed of sound.

   ↳ hep-thcond-mat.stat-mechhep-phnucl-thEPJA(2019)·26 citations
6. 06*

   'Running' under tight constraints in pionless effective field theory

   Jun-Jun Lü🇨🇳 · Ji-Feng Yang🇨🇳

   The contents of renormalization group invariance and equations under tight constraints are explored and demonstrated with closed-form on-shell $T$ matrices of pionless effective field theory for nuclear forces right within the effective field theory philosophy. The 'running' couplings under such tight constraints are presented in ${}^1{S}_0$ and uncoupled $P$ channels up to truncation order $\mathcal{O}(Q^4)$. Some linear relations are exposed and in turn employed in the pursuit of nonperturbative 'running' solutions which serves as an alternative choice without resorting to special prescription and additional operations or treatments. The utility of such 'running' behaviors inherent in the closed-form $T$-matrices of pionless effective field theory is remarked and a number of important issues related to effective field theory constructed with various truncations are interpreted or discussed from the underlying theory perspective.

   ↳ nucl-thhep-phIJMPE(2021)·1 citation
7. 07*

   Reheating constraints on Tachyon Inflation

   Akhilesh Nautiyal🇮🇳

   Tachyon inflation is one of the most attractive models of noncannonical inflation motivated by string theory. In this work we revisit the constraints on tachyon inflation with inverse $\cosh$ potential and exponential potential considering reheating, Although the phase of reheating is not well understood, it can be parameterized in terms of reheating temperature $T_{re}$, number of e-folds during reheating $N_{re}$ and effective equation of state during reheating $w_{re}$, which can be related to the parameters of the tachyon potential, spectral index $n_s$ and tensor-to-scalar ratio $r$. For various reheating scenarios there is a finite range of $w_{re}$ and the reheating temperature should be above electroweak scale. By imposing these conditions, we find that both the inverse $\cosh$ potential and exponential potential are disfavored by Planck observations. We also find that $w_{re}$ for both these potentials should be close to $1$ to satisfy Planck-2015 joint constraints on $n_s$ and $r$.

   ↳ astro-ph.COhep-phhep-thPRD(2018)·22 citations
8. 08*

   Searches for New Particles Including Dark Matter with Atomic, Molecular and Optical Systems

   Yevgeny V. Stadnik🇩🇪 · Victor V. Flambaum🇦🇺

   New particles can manifest their effects in many settings, ranging from effects on sub-atomic to galactic length scales. The nature of these effects depends on the specific particles and their non-gravitational interactions. In this chapter, we give a brief overview of how atomic, molecular and optical systems can be used to search for new particles. To illustrate the basic principles behind these methods, we focus on the simplest class of particles, namely new spinless bosons.

   ↳ physics.atom-phhep-ph18 citations
9. 09*

   Machine Learning CICY Threefolds

   Kieran Bull🇬🇧 · Yang-Hui He🇬🇧 · Vishnu Jejjala🇿🇦 · Challenger Mishra🇬🇧

   The latest techniques from Neural Networks and Support Vector Machines (SVM) are used to investigate geometric properties of Complete Intersection Calabi-Yau (CICY) threefolds, a class of manifolds that facilitate string model building. An advanced neural network classifier and SVM are employed to (1) learn Hodge numbers and report a remarkable improvement over previous efforts, (2) query for favourability, and (3) predict discrete symmetries, a highly imbalanced problem to which both Synthetic Minority Oversampling Technique (SMOTE) and permutations of the CICY matrix are used to decrease the class imbalance and improve performance. In each case study, we employ a genetic algorithm to optimise the hyperparameters of the neural network. We demonstrate that our approach provides quick diagnostic tools capable of shortlisting quasi-realistic string models based on compactification over smooth CICYs and further supports the paradigm that classes of problems in algebraic geometry can be machine learned.

   ↳ hep-thhep-phmath.AGstat.MLPLB(2018)·90 citations
10. 10*

    Comment on "Measurement of the $Q^2$ Dependence of the Deuteron Spin Structure Function $g_1$ and its Moments at Low $Q^2$ with CLAS"

    Vadim Lensky🇩🇪 · Franziska Hagelstein🇨🇭 · Astrid Hiller Blin🇩🇪 · Vladimir Pascalutsa🇩🇪

    We argue that the recently published CLAS results on the deuteron spin polarizability ${\gamma }_0$ [Adhikari {\it et al.}, Phys.\ Rev.\ Lett.\ {\bf 120}, 062501 (2018)], as well as their comparisons with chiral perturbation theory ($\chi$PT), are misleading. In reality, the deuteron polarizability is larger by 4 orders of magnitude, as demonstrated here by a novel calculation in pionless EFT. The CLAS paper, on the other hand, presents only a tiny correction to it, based on a partial evaluation of a sum rule for ${\gamma }_0$. The sum rule is assumed to have the same form as for the nucleon; we argue it does not. Moreover, their "test of $\chi$PT" tacitly involves assumptions which, as we demonstrate, may not be valid at the claimed accuracy.

    ↳ nucl-thhep-phnucl-ex4 citations
11. 11*

    Extended Skyrme interactions for transport model simulations of heavy-ion collisions

    Rui Wang🇨🇳 · Lie-Wen Chen🇨🇳 · Ying Zhou🇨🇳

    Based on an extended Skyrme interaction that includes the terms in relative momenta up to sixth order, corresponding to the so-called Skyrme pseudopotential up to next-to-next-to-next-to leading order (N3LO), we derive the expressions of Hamiltonian density and single nucleon potential under general non-equilibrium conditions which can be applied in transport model simulations of heavy-ion collisions induced by neutron-rich nuclei. While the conventional Skyrme interactions, which include the terms in relative momenta up to second order, predict an incorrect behavior as a function of energy for nucleon optical potential in nuclear matter, the present extended N3LO Skyrme interaction can give a nice description for the empirical nucleon optical potential. We also construct three interaction sets with different high-density behaviors of the symmetry energy, by fitting both the empirical nucleon optical potential up to energy of $1$ GeV and the empirical properties of isospin asymmetric nuclear matter. These extended N3LO Skyrme interactions will be useful in transport model simulations of heavy-ion collisions induced by neutron-rich nuclei at intermediate and high energies, and they can also be useful in nuclear structure studies within the mean-field model.

    ↳ nucl-thastro-ph.SRhep-phnucl-exPRC(2018)·32 citations
12. 12*

    Heavy sterile neutrinos in stellar core-collapse

    Tomasz Rembiasz🇪🇸 · Martin Obergaulinger🇪🇸 · Manuel Masip🇪🇸 · M. Ángeles Pérez-García🇪🇸 · Miguel-Ángel Aloy🇪🇸 · Conrado Albertus🇪🇸

    We perform spherically symmetric simulations of the core collapse of a single progenitor star of zero age main sequence mass $M_{\mathrm{ZAMS}}=15M_{\odot }$ with two models of heavy sterile neutrinos in the mass range of hundred MeV$/c^2$. According to both models, these hypothetical particles are copiously produced in the center, stream outwards a subsequently decay releasing energy into final states (including neutrinos) of the Standard Model. We find that they can lead to a successful explosion in otherwise non-exploding progenitors. Depending on their unknown parameters (e.g., mass and coupling constants with matter), we obtain either no explosion or an explosion of one of two types, i.e., through heating of gas downstream of the stalled shock wave, similarly to the standard scenario for supernova explosions or through heating of gas at higher radii that ejects matter from the outer core or the envelope while the center continues to accrete matter. In both cases, the explosion energies can be very high. We presume that this new type of explosion would produce an electromagnetic signal that significantly differs from common events because of the relative absence of heavy elements in the ejecta. The combination of core-collapse simulations and astrophysical observations may further constrain the parameters of the sterile neutrinos.

    ↳ astro-ph.HEastro-ph.SRhep-phPRD(2018)·45 citations
13. 13*

    Electronic properties of strained double-Weyl systems

    P.O. Sukhachov🇨🇦 · E.V. Gorbar🇺🇦 · I.A. Shovkovy🇺🇸 · V.A. Miransky🇨🇦

    The effects of strains on the low-energy electronic properties of double-Weyl phases are studied in solids and cold-atom optical lattices. The principal finding is that deformations do not couple, in general, to the low-energy effective Hamiltonian as a pseudoelectromagnetic gauge potential. The response of an optical lattice to strains is simpler, but still only one of several strain-induced terms in the corresponding low-energy Hamiltonian can be interpreted as a gauge potential. Most interestingly, the strains can induce a nematic order parameter that splits a double-Weyl node into a pair of Weyl nodes with the unit topological charges. The effects of deformations on the motion of wavepackets in the double-Weyl optical lattice model are studied. It is found that, even in the undeformed lattices, the wavepackets with opposite topological charges can be spatially split. Strains, however, modify their velocities in a very different way and lead to a spin polarization of the wavepackets.

    ↳ cond-mat.mes-hallhep-phAnnalen Phys.(2018)·7 citations

* 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.