Fri·May 17, 2019Friday·May 17, 2019

1. 01*

   Finite size effect on thermodynamics of hadron gas in high-multiplicity events of proton-proton collisions at the LHC

   Nachiketa Sarkar🇮🇳 · Paramita Deb🇮🇳 · Premomoy Ghosh🇮🇳

   Multiple Reflection Expansion (MRE) formalism has been applied to hadron resonance gas (HRG) model to study the finite-size effect on thermodynamics of small systems of hadron gas at the chemical freeze-out temperature in high-multiplicity events of proton-proton (pp) colisions at the LHC. Comparison with larger systems of heavy-ion (AA) collisions helps in undersanding the usefulness of the effect on small systems. Thermodynamic properties of these systems at the chemical freeze-out, with and without system-size effect, are contrasted with those for infinite hadronic phase of strongly interacting matter at ideal thermodynamic limit, as provided by LQCD calculations. On introduction of finite size effect, the small hadronic systems produced in high-multiplicity pp events, unlike those in AA collisions, remain away from ideal thermodynamic limit. Knudsen number estimations validate the findings.

   hep-ph5 citations
2. 02*

   Effective Field Theory after a New-Physics Discovery

   Matthias König🇨🇭

   After the discovery of a new resonance, its couplings to the Standard Model (SM) need to be described by the means of an effective theory, appropriately constructed to separate its mass scale from the mass scales associated with the SM decay products. At the example of a scalar resonance transforming as a singlet under the SM gauge group, we construct the operator basis for such a theory using the language of Soft-Collinear Effective Theory (SCET) and perform the resummation of the leading Sudakov logarithms.

   hep-ph1 citation
3. 03*

   $TeV$-Scale Resonant Leptogenesis with New Scaling Ansatz on Neutrino Dirac Mass Matrix from $A_4$ Flavor Symmetry

   H. B. Benaoum🇦🇪 · S. H. Shaglel🇦🇪

   We propose a new scaling ansatz in the neutrino Dirac mass matrix to explain the low energy neutrino oscillations data, baryon number asymmetry and neutrinoless double beta decay. In this work, a full reconstruction of the neutrino Dirac mass matrix has been realized from the low energy neutrino oscillations data based on type-I seesaw mechanism. A concrete model based on $A_4$ flavor symmetry has been considered to generate such a neutrino Dirac mass matrix and imposes a relation between the two scaling factors. In this model, the right-handed Heavy Majorana neutrino masses are quasi-degenerate at TeV mass scales. Extensive numerical analysis studies have been carried out to constrain the parameter space of the model from the low energy neutrino oscillations data. It has been found that the parameter space of the Dirac mass matrix elements lies near or below the MeV region and the scaling factor $|{\kappa }_1|$ has to be less than 10. Furthermore, we have examined the possibility for simultaneous explanation of both neutrino oscillations data and the observed baryon number asymmetry in the Universe. Such an analysis gives further restrictions on the parameter space of the model, thereby explaining the correct neutrino data as well as the baryon number asymmetry via a resonant leptogenesis scenario. Finally, we show that the allowed space for the effective Majorana neutrino mass $m_{ee}$ is also constrained in order to account for the observed baryon asymmetry.

   hep-phInt.J.Mod.Phys.A(2020)·1 citation
4. 04*

   Measuring Higgs self couplings in the presence of VVH and VVHH at the ILC

   Satendra Kumar🇮🇳 · Poulose Poulose🇮🇳 · Rafiqul Rahaman🇮🇳 · Ritesh K. Singh🇮🇳

   The recent discovery of a Higgs boson at the LHC, while establishing the Higgs mechanism as the way of electroweak symmetry breaking, started an era of precision measurements involving the Higgs boson. In an effective Lagrangian framework, we consider the $e^{+}{e}^{-}\to ZHH$ process at the ILC running at a centre of mass energy of 500 GeV to investigate the effect of the $ZZH$ and $ZZHH$ couplings on the sensitivity of $HHH$ coupling in this process. Our results show that the sensitivity of the trilinear Higgs self couplings on this process has somewhat strong dependence on the Higgs-gauge boson couplings. Single and two parameter reach of the ILC with an integrated luminosity of 1000 fb${}^{-1}$ are obtained on all the effective couplings indicating how these limits are affected by the presence of anomalous $ZZH$ and $ZZHH$ couplings. The kinematic distributions studied to understand the effect of the anomalous couplings, again, show a strong influence of $Z$-$H$ couplings on the dependence of these distributions on $HHH$ coupling. Similar results are indicated in the case of the process, $e^{+}{e}^{-}\to \nu \bar{\nu }HH$, considered at a centre of mass energy of 2 TeV, where the cross section is large enough. The effect of $WWH$ and $WWHH$ couplings on the sensitivity of $HHH$ coupling is clearly established through our analyses in this process.

   hep-phhep-exInt.J.Mod.Phys.A(2019)·10 citations
5. 05*

   Vector hidden-bottom tetraquark candidate: $Y(10750)$

   Zhi-Gang Wang🇨🇳

   In this article, we take the scalar diquark and antidiquark operators as the basic constituents, construct the $C{\gamma }_5\otimes {\overleftrightarrow{\partial }}_{\mu }\otimes {\gamma }_{5}C$ type tetraquark current to study the $Y(10750)$ with the QCD sum rules. The predicted mass $M_Y=10.75\pm 0.10\mathrm{GeV}$ and width ${\Gamma }_Y=33.60_{-9.45}^{+16.64}\mathrm{MeV}$ support assigning the $Y(10750)$ to be the diquark-antidiquark type vector hidden-bottom tetraquark state, which has a relative P-wave between the diquark and antidiquark constituents.

   hep-phCPC(2019)·49 citations
6. 06*

   BSM WW production with a jet veto

   Luke Arpino🇬🇧 · Andrea Banfi🇬🇧 · Sebastian Jäger🇬🇧 · Nikolas Kauer🇬🇧

   We consider the impact on WW production of the unique dimension-six operator coupling gluons to the Higgs field. In order to study this process, we have to appropriately model the effect of a veto on additional jets. This requires the resummation of large logarithms of the ratio of the maximum jet transverse momentum and the invariant mass of the W boson pair. We have performed such resummation at the appropriate accuracy for the Standard Model (SM) background and for a signal beyond the SM (BSM), and devised a simple method to interface jet-veto resummations with fixed-order event generators. This resulted in the fast numerical code MCFM-RE, the Resummation Edition of the fixed-order code MCFM. We compared our resummed predictions with parton-shower event generators and assessed the size of effects, such as limited detector acceptances, hadronisation and the underlying event, that were not included in our resummation. We have then used the code to compare the sensitivity of WW and ZZ production at the HL-LHC to the considered higher-dimension operator. We have found that WW can provide complementary sensitivity with respect to ZZ, provided one is able to control theory uncertainties at the percent-level. Our method is general and can be applied to the production of any colour singlet, both within and beyond the SM.

   hep-phJHEP(2019)·19 citations
7. 07*

   Hadroproduction of open heavy flavour for PDF analyses

   Ilkka Helenius🇫🇮 · Hannu Paukkunen🇫🇮

   Due to the large masses of the charm and bottom quarks, their production cross sections are calculable within the perturbative QCD. This makes the heavy-quark mesons important observables in high-energy collisions of protons and nuclei. However, the available calculations for heavy-flavored-meson hadroproduction have been somewhat problematic in reliably describing the cross sections across the full kinematic range from zero to very high $p_{\mathrm{T}}$. This has put some question marks on the robustness of LHC heavy-flavored-meson measurements in studying the partonic structure of the colliding hadrons and nuclei. Here, we introduce SACOT-$m_{\mathrm{T}}$ - a novel scheme for open heavy-flavour hadroproduction within the general-mass variable-flavour-number formalism that solves this problem. The introduced scheme is an analogue of the SACOT-$\chi$ scheme often used for deeply-inelastic scattering in global analyses of PDFs.

   hep-phPoS(2019)·0 citations
8. 08*

   Monte-Carlo sensitivity study for sterile neutrino search with ${}^{144}$Ce - ${}^{144}$Pr source and liquid scintillation detectors of various geometries

   A.V. Derbin🇷🇺 · I.S. Drachnev🇷🇺 · I.S. Lomskaya🇷🇺 · V.N. Muratova🇷🇺 · N.V. Pilipenko🇷🇺 · D.A. Semenov🇷🇺 · E.V. Unzhakov🇷🇺

   Expected energy spectra calculations for large volume liquid scintillation detectors to inverse $\beta$-decay for antineutrinos produced by ${}^{144}$Ce -- ${}^{144}$Pr artificial source have been performed. The calculations were carried out through Monte-Carlo method within GEANT4.10 framework and were purposed to search for neutrino oscillation to sterile eigenstate with mass about 1 eV. The analysis of relative sensitivity to oscillation parameters for different detector shapes has been performed.

   hep-phhep-ex0 citations
9. 09*

   Consistent treatment of charm production in higher-orders at tree-level within $k_T$-factorization approach

   Rafal Maciula🇵🇱 · Antoni Szczurek🇵🇱

   We discuss production of $c\bar{c}$-pairs within $k_T$-factorization approach (off-shell initial partons) with unintegrated parton distribution functions (uPDFs). We present a consistent prescription which merges the standard leading-order (LO) $k_T$-factorization calculations for this process with tree-level next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) matrix elements. For the first time we include in this framework 2 $\to$ 3 and 2 $\to$ 4 processes with extra partonic emissions for single particle distributions as well as for correlation observables. The use of the KMR uPDF leads to a good description of the existing charm ($D$-meson) data already at the leading-order. On the other hand, a new Parton-Branching (PB) uPDF strongly underestimates the same experimental data. A direct inclusion of the higher-orders at tree-level leads to an overestimation of the data, especially for the KMR uPDF. This suggests a significant double-counting. We propose a simple method how to avoid the double-counting. Our procedure leads to a much better description of the experimental data when including the higher-order contributions. Then with the KMR uPDF we get similar results (both for single particle and correlation observables) as for the standard calculations of the 2 $\to$ 2 processes. For the PB uPDF inclusion of the higher-orders considerably improves description of the experimental data. We conclude that the LO calculation with the KMR uPDF effectively includes the higher-orders which is not the case for the PB uPDF.

   hep-phhep-exPRD(2019)·34 citations
10. 10*

    Coherent and incoherent vector meson electroproduction in the future electron-ion colliders: the hot-spot predictions

    M. Krelina🇨🇱 · V. P. Goncalves🇧🇷 · J. Cepila🇨🇿

    One of the more promising observables to probe the high energy regime of the QCD dynamics in the future Electron-Ion Colliders (EIC) is the exclusive vector meson production cross section in coherent and incoherent interactions. Such processes measure the average spatial distribution of gluons in the target as well the fluctuations and correlations in the gluon density. In this paper we present a comprehensive analysis of the energy, photon virtuality, atomic number and momentum transfer dependencies of the coherent and incoherent cross sections considering two different models for the nuclear profile function. In particular, we present the predictions of the hot-spot model, which assumes the presence of subnucleonic degrees of freedom and an energy-dependent profile. Our results indicate that the analysis of the ratio between the incoherent and coherent cross sections and the momentum transfer distributions in the future EIC can be useful to constrain the description of the hadronic structure at high energies.

    hep-phnucl-thNPA(2019)·24 citations
11. 11*

    Parton energy loss in pp collisions at very high multiplicity

    Aditya Nath Mishra🇲🇽 · Guy Paić

    We present the results for the evolution of transverse momentum spectra for the jetty and underlying parts of events as a function of multiplicity in pp collisions at 13 TeV measured at midrapidity ($\left|\eta \right|<0.8$) using PYTHIA8 event generator. The main characteristic of the approach is that it reaches to extreme multiplicities not yet explored by the experiments. We demonstrate that the behavior of both the underlying and hard components are affected by the multiplicity of the events i.e. the energy density. The behavior of the spectra at very high multiplicities suggests that the partons suffer energy loss compensated by an increase in the multiplicity of events.

    hep-ph7 citations
12. 12*

    A factorization theorem connecting the light-cone distribution amplitudes of heavy-flavor mesons in QCD and HQET

    Saadi Ishaq🇨🇳 · Yu Jia🇨🇳 · Xiaonu Xiong🇨🇳 · De-Shan Yang🇨🇳

    The light-cone distribution amplitude (LCDA) of a heavy-light meson defined in heavy quark effective theory (HQET), is a fundamental nonperturbative input to account for innumerable $B$ meson exclusive decay and production processes. On the other hand, the conventional heavy-flavored meson LCDA defined in QCD, also ubiquitously enters the factorization formula for hard exclusive $B$ production processes. Inspired by the observation that these two LCDAs exhibit the identical infrared behaviors, yet differ in the ultraviolet scale of order $m_b$ or greater, we propose a novel factorization theorem for the heavy-light mesons, that the LCDA defined in QCD can be further expressed as a convolution between the LCDA in HQET and a perturbatively calculable coefficient function thanks to asymptotic freedom. This refactorization program can be invoked to fully disentangle the effects from three disparate scales $Q$, $m_b$ and ${\Lambda }_{\mathrm{QCD}}$ for a hard exclusive $B$ production process, particularly to facilitate the resummation of logarithms of type $\ln Q/m_b$ and $\ln m_b/{\Lambda }_{\mathrm{QCD}}$ in a systematic fashion.

    hep-phPRL(2020)·21 citations
13. 13*

    Dark Matter Targets for Axion-like Particle Searches

    Nikita Blinov🇺🇸 · Matthew J. Dolan🇦🇺 · Patrick Draper🇺🇸 · Jonathan Kozaczuk🇺🇸

    Many existing and proposed experiments targeting QCD axion dark matter (DM) can also search for a broad class of axion-like particles (ALPs). We analyze the experimental sensitivities to electromagnetically-coupled ALP DM in different cosmological scenarios with the relic abundance set by the misalignment mechanism. We obtain benchmark DM targets for the standard thermal cosmology, a pre-nucleosynthesis period of early matter domination, and a period of kination. These targets are theoretically simple and assume $\mathcal{O}(1)$ misalignment angles, avoiding fine-tuning of the initial conditions. We find that some experiments will have sensitivity to these ALP DM targets before they are sensitive to the QCD axion, and others can potentially reach interesting targets below the QCD band. The ALP DM abundance also depends on the origin of the ALP mass. Temperature-dependent masses that are generated by strong dynamics (as for the QCD axion) correspond to DM candidates with smaller decay constants, resulting in even better detection prospects.

    hep-phastro-ph.COPRD(2019)·78 citations
14. 14*

    Hadron structure in high-energy collisions

    Karol Kovarik🇩🇪 · Pavel M. Nadolsky🇺🇸 · Davison E. Soper🇺🇸

    Parton distribution functions (PDFs) describe the structure of hadrons as composed of quarks and gluons. They are needed to make predictions for short-distance processes in high-energy collisions and are determined by fitting to cross section data. We review definitions of the PDFs and their relations to high-energy cross sections. We focus on the PDFs in protons, but also discuss PDFs in nuclei. We review in some detail the standard statistical treatment needed to fit the PDFs to data using the Hessian method. We discuss tests that can be used to critically examine whether the assumptions are indeed valid. We also present some ideas of what one can do in the case that the tests indicate that the assumptions fail.

    hep-phRMP(2020)·152 citations
15. 15*

    Perturbative Corrections to Heavy Quark-Diquark Symmetry Predictions for Doubly Heavy Baryon Hyperfine Splittings

    Thomas Mehen🇺🇸 · Abhishek Mohapatra🇺🇸

    Doubly heavy baryons $\left(QQq\right)$ and singly heavy antimesons $\left(\bar{Q}q\right)$ are related by the heavy quark-diquark (HQDQ) symmetry because in the $m_Q\to \infty$ limit, the light degrees of freedom in both the hadrons are expected to be in identical configurations. Hyperfine splittings of the ground states in both systems are nonvanishing at $O(1/m_Q)$ in the heavy quark mass expansion and HQDQ symmetry relates the hyperfine splittings in the two sectors. In this paper, working within the framework of Non-Relativistic QCD (NRQCD), we point out the existence of an operator that couples four heavy quark fields to the chromomagnetic field with a coefficient that is enhanced by a factor from Coulomb exchange. This operator gives a correction to doubly heavy baryon hyperfine splittings that scales as $1/m_Q^2\times {\alpha }_S/r$, where $r$ is the separation between the heavy quarks in the diquark. This correction can be calculated analytically in the extreme heavy quark limit in which the potential between the quarks in the diquark is Coulombic. In this limit, the correction is $O({\alpha }_s^2/m_Q)$ and comes with a small coefficient. For values of ${\alpha }_s$ relevant to doubly charm and doubly bottom systems, the correction to the hyperfine splittings in doubly heavy baryons is only a few percent or smaller. We also argue that nonperturbative corrections to the prediction for the hyperfine splittings are suppressed by ${\Lambda }_{\mathrm{QCD}}^2/m_Q^2$ rather than ${\Lambda }_{\mathrm{QCD}}/m_Q$. Corrections should be $\approx 10\%$ in the charm sector and smaller in heavier systems.

    hep-phPRD(2019)·15 citations
16. 16*

    Magnetogenesis from a rotating scalar: à la scalar chiral magnetic effect

    Kohei Kamada🇯🇵 · Chang Sub Shin🇰🇷

    The chiral magnetic effect (CME) is a phenomenon in which an electric current is induced parallel to an external magnetic field in the presence of chiral asymmetry in a fermionic system. In this paper, we show that the electric current induced by the dynamics of a pseudo-scalar field which anomalously couples to electromagnetic fields can be interpreted as closely analogous to the CME. In particular, the velocity of the pseudo-scalar field, which is the phase of a complex scalar, indicates that the system carries a global U(1) number asymmetry as the source of the induced current. We demonstrate that an initial kick to the phase-field velocity and an anomalous coupling between the phase-field and gauge fields are naturally provided, in a set-up such as the Affleck-Dine mechanism. The resulting asymmetry carried by the Affleck-Dine field can give rise to instability in the (electro)magnetic field. Cosmological consequences of this mechanism are also investigated.

    hep-phastro-ph.COhep-thJHEP(2020)·17 citations
17. 17*

    Heavy resonances (W', Z', jets) in ATLAS and CMS in Run 2

    Alberto Zucchetta (on behalf of the ATLAS and CMS Collaborations)🇨🇭

    An overview of the searches for heavy resonances that decay to leptons or quarks is presented. The results are based on the data collected by the ATLAS and CMS experiments in proton-proton collisions at $\sqrt{s}=13\text{TeV}$, and include for the first time the entire LHC Run 2 data set.

    ↳ hep-exhep-ph3 citations
18. 18*

    The onset of $\Lambda \Lambda$ hypernuclear binding

    L. Contessi🇮🇱 · M. Schäfer🇨🇿 · N. Barnea🇮🇱 · A. Gal🇮🇱 · J. Mareš🇨🇿

    Binding energies of light, $A\le 6$, $\Lambda \Lambda$ hypernuclei are calculated using the stochastic variational method in a pionless effective field theory (EFT) approach at leading order with the purpose of assessing critically the onset of binding in the strangeness S=-2 hadronic sector. The EFT input in this sector consists of (i) a $\Lambda \Lambda$ contact term constrained by the $\Lambda \Lambda$ scattering length $a_{\Lambda \Lambda }$, using a range of values compatible with $\Lambda \Lambda$ correlations observed in relativistic heavy ion collisions, and (ii) a $\Lambda \Lambda N$ contact term constrained by the only available $A\le 6$ $\Lambda \Lambda$ hypernucler binding energy datum of ${}_{\Lambda \Lambda }^6$He. The recently debated neutral three-body and four-body systems ${}_{\Lambda \Lambda }^3$n and ${}_{\Lambda \Lambda }^4$n are found unbound by a wide margin. A relatively large value of $|a_{\Lambda \Lambda }|\gtrsim 1.5$ fm is needed to bind ${}_{\Lambda \Lambda }^4$H, thereby questioning its particle stability. In contrast, the particle stability of the $A=5$ $\Lambda \Lambda$ hypernuclear isodoublet ${}_{\Lambda \Lambda }^5$H--${}_{\Lambda \Lambda }^5$He is robust, with $\Lambda$ separation energy of order 1 MeV.

    ↳ nucl-thhep-phnucl-exPLB(2019)·31 citations
19. 19*

    Nonclassical primordial gravitational waves from the initial entangled state

    Sugumi Kanno🇯🇵

    The nonclassicality of primordial gravitational waves (PGWs) is characterized in terms of sub-Poissonian graviton statistics. The sub-Poissonian statistics are realized when quantum states are squeezed coherent states. In the presence of matter fields, the Universe experiences the squeezed coherent state during inflation. The condition to realize the sub-Poissonian graviton statistics is translated into the frequency range of gravitational waves. If the initial state is the Bunch-Davies vacuum, there is another necessary condition between phases of squeezing and coherent parameters. Here, we extend the initial state to entangled states. We consider $\alpha$-vacua as the initial entangled state that are more general de Sitter invariant vacua than the Bunch-Davies vacuum. We find that, unlike the Bunch-Davies vacuum, PGWs generated in the initial entangled state become sub-Poissonian without requiring the condition between the phases.

    ↳ hep-thgr-qchep-phquant-phPRD(2019)·40 citations
20. 20*

    First Results from ABRACADABRA-10cm: A Search for Low-Mass Axion Dark Matter

    Chiara P. Salemi🇺🇸

    The presence of dark matter provides some of the most tangible evidence for the existence of physics beyond the Standard Model. One compelling dark matter candidate is the axion, a light boson that was originally postulated as a solution to another outstanding issue, the strong CP problem in QCD. ABRACADABRA is an experimental program to search for sub-$\mu$eV axion and axion-like dark matter. It searches for axion-induced modifications to Maxwell's equations with a toroidal magnet and SQUID magnetometer. This contribution will present the first results from the prototype detector, ABRACADABRA-10cm.

    ↳ hep-exhep-ph20 citations
21. 21*

    Quantizing a solitonic string

    M. Shifman🇺🇸 · A. Yung🇺🇸

    Quite often the zero mode dynamics on solitonic vortices are described by a non-conformal effective world-sheet sigma model (WSSM). We address the problem of solitonic string quantization in this case. As well-known, only crfitical strings with superconformal WSSMs are self-consistent in ultra-violet (UV) domain. Thus, we look for the appropriate UV completion of the low-energy non-conformal WSSM. We ague that for the solitonic strings supported in well-defined bulk theories the UV complete WSSM has a UV fixed point which can be used for string quantization. As an example, we consider BPS non-Abelian vortices supported by four-dimensional (4D) \ntwo SQCD with the gauge group U$(N)$ and $N_f$ quark multiplets where $N_f\ge N$. In addition to translational moduli the non-Abelian vortex under consideration carries orientational and size moduli. Their low-energy dynamics are described by a two-dimensional \ntwot supersymmetric weighted model, namely, $\mathbb{WCP}(N,N_f-N)$. Given our UV completion of this WSSM we find its UV fixed point. The latter defines a superconformal WSSM. We observe two cases in which this conformal WSSM, combined with the free theory for four translational moduli, has ten-dimensional target space required for superstrings to be critical.

    ↳ hep-thhep-phJHEP(2019)·0 citations
22. 22*

    Weak Gravity Conjecture, Black Hole Entropy, and Modular Invariance

    Lars Aalsma🇳🇱 · Alex Cole🇺🇸 · Gary Shiu🇺🇸

    In recent literature, it has been argued that a mild form of the Weak Gravity Conjecture (WGC) is satisfied by wide classes of effective field theories in which higher-derivative corrections can be shown to shift the charge-to-mass ratios of extremal black holes to larger values. However, this mild form does not directly constrain low-energy physics because the black holes satisfying the WGC have masses above the cutoff of the effective theory. In this note, we point out that in string theory modular invariance can connect a light superextremal state to heavy superextremal states; the latter collapse into black holes at small string coupling. In the context of heterotic string theory, we show that these states are black holes that have ${\alpha }^{\prime }$-exact charge-to-mass ratios exceeding the classical extremality bound. This suggests that modular invariance of the string partition function can be used to relate the existence of a light superextremal particle to the positive shift in charge-to-mass ratio of extremal black holes.

    ↳ hep-thgr-qchep-phJHEP(2019)·43 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.