HEP Phenomenology·hep-ph

Fri·Feb 21, 2020Friday·February 21, 2020

17 papers—9 primary·8 cross-listed·reconstructed*

01*
Origin of single transverse-spin asymmetries in high-energy collisions
Justin Cammarota🇺🇸 · Leonard Gamberg🇺🇸 · Zhong-Bo Kang🇺🇸 · Joshua A. Miller🇺🇸 · Daniel Pitonyak🇺🇸 · Alexei Prokudin🇺🇸 · Ted C. Rogers🇺🇸 · Nobuo Sato🇺🇸
In this paper we perform the first simultaneous QCD global analysis of data from semi-inclusive deep inelastic scattering, Drell-Yan, $e^{+} e^{-}$ annihilation into hadron pairs, and proton-proton collisions. Consequently, we are able to extract a universal set of non-perturbative functions that describes the observed asymmetries in these reactions. The outcome of our analysis indicates single transverse-spin asymmetries in high-energy collisions have a common origin. Furthermore, we achieve the first phenomenological agreement with lattice QCD on the up and down quark tensor charges.
hep-phhep-exhep-latnucl-ex+1PRD(2020)·169 citations
02*
Understanding long-range near-side ridge correlations in p $-$ p collisions using rope hadronization at LHC energies
Pritam Chakraborty🇮🇳 · Sadhana Dash🇮🇳
The observation of long range ridge-like structure in the near-side region of the two particle $Δ η - Δ ϕ$ correlations as measured by LHC experiments in high multiplicity p $-$ p collisions indicated towards the presence of collective effects which are similar to that observed in p $-$ A(nucleon-nucleus) and A $-$ A (nucleus-nucleus) collisions. The two particle correlation between the charged particles in $Δ η - Δ ϕ$ for p $-$ p collisions at $s$ = 7 TeV and 13 TeV is studied using Pythia 8 event generator within the framework of final-state partonic color reconnection effects as well as the microscopic rope hadronization model. The rope hadronization relies on the formation of ropes due to overlapping of strings in high multiplicity events followed by string shoving. A near side ridge-like structure which is qualitatively similar to the observed ridge in data was observed for high-multiplicity events when the mechanism of rope hadronization (with shoving) was enabled.
hep-phhep-exnucl-exnucl-thPRC(2020)·7 citations
03*
Role of the triangle mechanism in the $Λ_{b} \to Λ_{c} π^{-} f_{0} (980)$ reaction
Shuntaro Sakai🇨🇳
We investigate the $Λ_{b} \to Λ_{c} π^{-} f_{0} (980)$ production with a $f_{0} (980)$ decay into $π^{+} π^{-}$ via the $K^{* 0} K^{-} K^{+}$ and $K^{*-} K^{0} K ˉ^{0}$ triangle loops. These loops produce a peak around 1.42 GeV in the $π^{-} f_{0} (980)$ invariant mass distribution, which is the same mechanism as the one considered to explain the $a_{1} (1420)$ peak. In the $π^{+} π^{-}$ distribution obtained by fixing the $π^{-} f_{0} (980)$ invariant mass to some values, a clear peak of $f_{0} (980)$ is seen, and the $π^{-} f_{0} (980)$ distribution has a peak around $M_{π^{-} f_{0}} = 1.42$ GeV, which is caused by the triangle mechanism of the $K^{*} K ˉ K$ loop. The branching ratio of $Λ_{b} \to Λ_{c} π^{-} f_{0} (980)$ with $f_{0} (980) \to π^{+} π^{-}$ by the triangle mechanism, obtained by integrating the $π^{-} f_{0} (980)$ distribution from 1 to 1.6 GeV, is estimated to be the order $1 0^{- 4}$ . Future measurements of the $Λ_{b} \to Λ_{c} π^{-} f_{0} (980)$ branching ratio and the $π^{-} f_{0} (980)$ invariant mass distribution predicted in this work would give further clues to clarify the nature of the $a_{1} (1420)$ peak.
hep-phPRD(2020)·11 citations
04*
Numerical approach to the semiclassical method of pair production for arbitrary spins and photon polarization
Tobias N. Wistisen🇩🇪
In this paper we show how to recast the results of the semiclassical method of Baier, Katkov & Strakhovenko for pair production, including the possibility of specifying all the spin states and photon polarization, in a form that is suitable for numerical implementation. In this case, a new type of integral appears in addition to the ones required for the radiation emission process. We compare the resulting formulas with those obtained for a short pulse plane wave external field by using the Volkov state. We investigate the applicability of the local constant field approximation for the proposed upcoming experiments at FACET II at SLAC and LUXE at DESY. Finally, we provide results on the dependence of the pair production rate on the relative polarization between a linearly polarized laser pulse and a linearly polarized incoming high energy photon. We observe that even in the somewhat intermediate intensity regime of these experiments, there is roughly a factor of $2$ difference between the pair production rates corresponding to the two relative photon polarizations, which is of interest in light of the vacuum birefringence of QED.
hep-phphysics.plasm-phPRD(2020)·23 citations
05*
Flavoured CP-asymmetry at the effective neutrino mass floor
Nimmala Narendra (1)🇮🇳 · Narendra Sahu (1)🇮🇳 · S. Uma Sankar (2) ((1) Department of Physics, Indian Institute of Technology Hyderabad, (2) Department of Physics, Indian Institute of Technology Bombay)🇮🇳
Both neutrinoless double beta decay and leptogenesis require neutrinos to be Majorana fermions. A relation between these two phenomena can be derived once the mechanism of neutrino mass generation is specified. We first derive the constraints on the Majorana phases by minimising the effective neutrino mass in neutrinoless double beta decay with respect to the smallest mass among the light neutrinos. Given these phases, we derive a lower bound on $M_{1}$ (the mass of the lightest of the heavy neutrinos) in the framework of Type-I seesaw mechanism, subject to the constraint that the CP asymmetry required for adequate leptogenesis is larger than $1 0^{- 8}$ . We find that $M_{1} \geq 1 0^{10} (1 0^{9})$ GeV for the case of Normal (Inverted) hierarchy. We extend our analysis to the case when one of the heavy neutrinos decouples (two right handed neutrino models). In this case we find $M_{1} \geq 1 0^{10} (1 0^{11})$ GeV for the case of Normal (Inverted) hierarchy.
hep-phNPB(2021)·3 citations
06*
Comment on A dark matter interpretation of excesses in multiple direct detection experiments [arXiv:2002.06937]
Alan E. Robinson🇨🇦 · Émile Michaud🇨🇦
In their recent preprint [arXiv:2002.06937], Kurinsky, Baxter, Kahn, and Krnjaic assume an unphysical ionization yield for plasmon excitations in order to claim a possible dark matter signal. Their proposed signal is not possible based on known physics, but their proposed detection method warrants further investigation.
hep-phastro-ph.COcond-mat.mtrl-scihep-ex+16 citations
07*
Single photon production in ppBar collision in the collinear and kt-factorisation framework and investigation of their differences
Mohammad Mousavi🇮🇷
The cross section of the single photon in ppBar collision is calculated. There are many subprocesses, for example the LO and NLO collisions, leading to the single photon. The LO collisions, the one of which (Compton scattering) is strongly dependent on the gluon distribution function, are investigated. Both the off-shell (k_t dependent) and on-shell partons are considered in the diffusions, and their differences are discussed. The unintegrated parton distribution functions (UPDFs), used for the off-shell partons, are calculated by the Martin-Ryskin-Watt (MRW) method. In the case of the on-shell partons, the integrated parton distribution functions (PDFs), are obtained by MMHT 2014 LO PDFs which are determined experimentally. To investigate the accuracy of the theoretical results, they are compared with the experimental data that are taken by the DØ and CDF collaborations at Fermilab Tevatron.
hep-phhep-ex0 citations
08*
Precision predictions for scalar leptoquark pair-production at hadron colliders
Christoph Borschensky🇩🇪 · Benjamin Fuks🇫🇷 · Anna Kulesza🇩🇪 · Daniel Schwartländer🇩🇪
We revisit scalar leptoquark pair-production at hadron colliders and significantly improve the level of precision of the cross section calculations. Apart from QCD contributions, we include lepton t-channel exchange diagrams that turn out to be relevant in the light of the recent B-anomalies. We evaluate all contributions at next-to-leading-order accuracy in QCD and resum, in the threshold regime, soft-gluon radiation at next-to-next-to-leading logarithmic accuracy. Our predictions consist hence in the most precise leptoquark cross section calculations available to date, and are necessary for the best exploitation of leptoquark searches at the LHC.
hep-phhep-exPRD(2020)·72 citations
09*
Electroweak baryogenesis and electron EDM in the B-LSSM
Jin-Lei Yang🇨🇳 · Tai-Fu Feng🇨🇳 · Hai-Bin Zhang🇨🇳
Electroweak baryogenesis (EWB) and electric dipole moment (EDM) have close relation with the new physics beyond the standard model (SM), because the SM CP-violating (CPV) interactions are not sufficient to provide the baryon asymmetry of the universe by many orders of magnitude, and the theoretical predictions for the EDM of electron ( $d_{e}$ ) in the SM are too tiny to be detected in near future. In this work, we explore the CPV effects on EWB and the electron EDM in the minimal supersymmetric extension (MSSM) of the SM with local $B - L$ gauge symmetry (B-LSSM). And the two-step transition via tree-effects in this model is discussed. Including two-loop corrections to $d_{e}$ and considering the constrains from updated experimental data, the numerical results show that the B-LSSM can account for the observed baryon asymmetry. In addition, when the cancellation between different contributions to $d_{e}$ takes place, the region favored by EWB can be compatible with the corresponding EDM bound.
hep-phEPJC(2020)·19 citations
10*
Determining the Neutrino Lifetime from Cosmology
Zackaria Chacko🇺🇸 · Abhish Dev🇺🇸 · Peizhi Du🇺🇸 · Vivian Poulin🇫🇷 · Yuhsin Tsai🇺🇸
We explore the cosmological signals of theories in which the neutrinos decay into invisible dark radiation after becoming non-relativistic. We show that in this scenario, near-future large scale structure measurements from the Euclid satellite, when combined with cosmic microwave background data from Planck, may allow an independent determination of both the lifetime of the neutrinos and the sum of their masses. These parameters can be independently determined because the Euclid data will cover a range of redshifts, allowing the growth of structure over time to be tracked. If neutrinos are stable on cosmological timescales, these observations can improve the lower limit on the neutrino lifetime by seven orders of magnitude, from $O (10)$ years to $2 \times 1 0^{8}$ years ( $95%$ C.L.), without significantly affecting the measurement of neutrino mass. On the other hand, if neutrinos decay after becoming non-relativistic but on timescales less than $O (100)$ million years, these observations may allow, not just the first measurement of the sum of neutrino masses, but also the determination of the neutrino lifetime from cosmology.
↳ astro-ph.COhep-phPRD(2021)·62 citations
11*
Recent results on Light Flavor from STAR
Jie Zhao (for the STAR collaboration)🇺🇸
These proceedings present an overview of the recent results on light flavor by the STAR experiment at RHIC.
↳ nucl-exhep-exhep-phnucl-thSpringer Proc.Phys.(2020)·0 citations
12*
Consequences of neutrino self interactions for weak decoupling and big bang nucleosynthesis
E. Grohs🇺🇸 · George M. Fuller🇺🇸 · Manibrata Sen🇺🇸
We calculate and discuss the implications of neutrino self-interactions for the physics of weak decoupling and big bang nucleosynthesis (BBN) in the early universe. In such neutrino-sector extensions of the standard model, neutrinos may not free-stream, yet can stay thermally coupled to one another. Nevertheless, the neutrinos exchange energy and entropy with the photon, electron-positron, and baryon component of the early universe only through the ordinary weak interaction. We examine the effects of neutrino self-interaction for the primordial helium and deuterium abundances and $N_{eff}$ , a measure of relativistic energy density at photon decoupling. These quantities are determined in, or may be influenced by, the physics in the weak decoupling epoch. Self interacting neutrinos have been invoked to address a number of anomalies, including as a possible means of ameliorating tension in the Hubble parameter. Our calculations show that surprisingly subtle changes in BBN accompany some of these neutrino self-interaction schemes. Such minute signals require high-precision measurements, making deuterium the best abundance for BBN constraints in the models explored here.
↳ astro-ph.COhep-phJCAP(2020)·42 citations
13*
Atmospheric neutrinos in a next-generation xenon dark matter experiment
Jayden L. Newstead🇺🇸 · Rafael F. Lang🇺🇸 · Louis E. Strigari🇺🇸
We study the sensitivity of future xenon- and argon-based dark matter and neutrino detection experiments to low-energy atmospheric neutrinos. Not accounting for experimental backgrounds, the primary obstacle for identifying nuclear recoils induced by atmospheric neutrinos is the tail of the electron recoil distribution due to $pp$ solar neutrinos. We use the NEST code to model the solar and atmospheric neutrino signals in a xenon detector and find that an exposure of 700 tonne-years will produce a $5 σ$ detection of atmospheric neutrinos. We explore the effect of different detector properties and find that a sufficiently long electron lifetime is essential to the success of such a measurement.
↳ astro-ph.COhep-exhep-phPRD(2021)·36 citations
14*
Anisotropic transport properties of Hadron Resonance Gas in magnetic field
Ashutosh Dash🇮🇳 · Subhasis Samanta🇵🇱 · Jayanta Dey🇮🇳 · Utsab Gangopadhyaya🇮🇳 · Sabyasachi Ghosh🇮🇳 · Victor Roy🇮🇳
An intense transient magnetic field is produced in high energy heavy-ion collisions mostly due to the spectator protons inside the two colliding nucleus. The magnetic field introduces anisotropy in the medium and hence the isotropic scalar transport coefficients become anisotropic and split into multiple components. Here we calculate the anisotropic transport coefficients shear, bulk viscosity, electrical conductivity, and the thermal diffusion coefficients for a multicomponent Hadron- Resonance-Gas (HRG) model for a non-zero magnetic field by using the Boltzmann transport equation in a relaxation time approximation (RTA). The anisotropic transport coefficient component along the magnetic field remains unaffected by the magnetic field, while perpendicular dissipation is governed by the interplay of the collisional relaxation time and the magnetic time scale, which is inverse of the cyclotron frequency. We calculate the anisotropic transport coefficients as a function of temperature and magnetic field using the HRG model. The neutral hadrons are unaffected by the Lorentz force and do not contribute to the anisotropic transports, we estimate within the HRG model the relative contribution of isotropic and anisotropic transports as a function of magnetic field and temperature. We also give an estimation of these anisotropic transport coefficients for the hadronic gas at finite baryon chemical potential.
↳ nucl-thhep-phPRD(2020)·70 citations
15*
Evolution of Cosmological Total Energy Density and Transient Periods in Cosmology
Bob Osano🇿🇦
The evolution of the Universe is traditionally examined by monitoring how its material content evolves as it expands. This model of an isolated system is expressed as the equation of motion of the bulk but segmented into different epochs. In particular, the evolution of the {\it $F r i e d mann - L e ma i^t r e - R o b er t so n - W a l k er$ } (FRLW) Universe is separated into different epochs that are characterised by the dynamics of whichever mass-energy density constituent is dominant at the time. The standard analysis of the evolution of the Universe in a particular epoch often considers the evolution of the dominant energy density only, disregarding all others. Whereas this represents the limiting case, in principle the contributions from others cannot always be ignored particularly in the vicinity of the equality of the various competing mass-energy densities or the transition periods between epochs. We examine the evolution of the total energy density rather than individual energy densities during the different epochs. We find that taking into account the contributions from the various constituents lead to a broader range of possible evolution histories which enriches the standard picture.
↳ gr-qchep-ph1 citation
16*
Constraining dark photons and their connection to 21 cm cosmology with CMB data
Kyrylo Bondarenko🇨🇭 · Josef Pradler🇦🇹 · Anastasia Sokolenko🇦🇹
In the inhomogeneous Universe, the cosmological conversion of dark photons into ordinary photons (and vice versa) may happen at a great number of resonance redshifts. This alters the CMB observed energy spectrum and degree of small-scale anisotropies. We utilize results from the EAGLE simulation to obtain the conversion probability along random line-of-sights to quantify these effects. We then apply our results to the case where dark photons are sourced by dark matter decay and their high-redshift conversion into ordinary photons modify the global 21 cm signal expected from the cosmic dawn era. Concretely, we show that a significant portion of the parameter space for which a converted population of photons in the Rayleigh-Jeans tail of the CMB explains the absorption strength observed by EDGES, is ruled out from the brightness temperature measurements of COBE/FIRAS and the CMB anisotropy measurements of Planck and SPT.
↳ astro-ph.COhep-phPLB(2020)·28 citations
17*
Gravitational microlensing by dark matter in extended structures
Djuna Croon🇨🇦 · David McKeen🇨🇦 · Nirmal Raj🇨🇦
Dark matter may be in the form of non-baryonic structures such as compact subhalos and boson stars. Structures weighing between asteroid and solar masses may be discovered via gravitational microlensing, an astronomical probe that has in the past helped constrain the population of primordial black holes and baryonic MACHOs. We investigate the non-trivial effect of the size of and density distribution within these structures on the microlensing signal, and constrain their populations using the EROS-2 and OGLE-IV surveys. Structures larger than a solar radius are generally constrained more weakly than point-like lenses, but stronger constraints may be obtained for structures with mass distributions that give rise to caustic crossings or produce larger magnifications.
↳ astro-ph.COhep-phPRD(2020)·98 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.