Exotic Effects in Cosmic Rays and Experiments at LHC

1. Exotic Effects in Cosmic Rays and Experiments at LHC L.I.Sarycheva Skobeltsyn Institute of Nuclear Physics Department of Physics Lomonosov Moscow State University 15 Lomonosov, Moscow, Russia, Aug 2011

2. Groups: Exotic Abstract:Some possible ways are considered to search in experiments at LHC for "exotic" phenomena, observed in cosmic rays. Such effects include: so called Centauros  fluctuations in the ratio electromagnetic/hadronic component in individual collisions, the alignment in azimuthal direction of energetically distinguished objects (particles, clusters) and the unusual energy transfer into the depth of absorber. 15 Lomonosov, Moscow, Russia, Aug 2011

3. 1.Introduction The exotic phenomena, reported from cosmic ray experiments, are associated with such observation as: * almost total energy transfer to hadronic component while energetic photons are practically absent  so called Centauro events  observed for the first time in 1973 by Japanese physicists [1] and later on addressed in the number of publications [2, 3] (fig. 1); * apparent alignment of energetically distinguished objects (secondary particles or particle clusters) along certain azimuthal directions [4-7] (fig. 2-4); * the unusual energy transfer into the depth of absorber (fig. 5, 6) was observed in 1972 by MSU physicists [9]. The analysis of this effect revealed other unusual properties associated with the same group of events, which allow consistent explanation assuming the production of a massive (~10 GeV/c2), stable (~1010 sec) particle with interaction length in the dense matter substantially larger that of regular hadrons (fig. 7, 8). We have analyzed the conditions for observation of such phenomena in experiments at Large Hadronic Collider (LHC). The results will be published in [8]. 15 Lomonosov, Moscow, Russia, Aug 2011

4. 2. Centauros. h = 50 m, 1000 m One of the first exotic phenomena, observed in the 80s years of the bygone age, was an event registered in a calorimeter type detector [1, 2]. The characteristic of this event was the anomalous ratio charged/neutral secondary hadrons emerged from the collision of high energy cosmic ray particle with the carbon nucleus. According to the principle of isotopic invariance, the number of pions with the charge 0, +1, and 1 should be equal. The event registered by Japanese physicists contained only charged pions, while neutral pions were absent. This event was named Centaurus. Other experiments using similar technique and performed by different collaborations (Collaboration PAMIR, Japanese-Brazilian Collaboration, etc.) were focused on search for such events [1, 2, 3]. Fig. 1. Illustration of Centauro-event. 15 Lomonosov, Moscow, Russia, Aug 2011

5. 3. Alignment of energetically distinguished objects Another exotic phenomenon observed in cosmic ray experiments is the coplanar production of high energy particles, which was called the “alignment”. The apparent alignment in the transverse plane of energetically distinguished centers (EDC) in the gamma-hadron families was observed experimentally by the PAMIR-Chacaltaya collaboration when analyzing the families which satisfy the criteria E 0.5 PeVand N 3. These families appear in roentgen-emulsion chambers placed under the carbon or lead absorber, revealing three, four, five EDCs located very close to a straight line. It was found that the fraction of such events, relative to the total number of the registered events, increases with increasing E and the hadron multiplicity in the family N 3 (Fig. 2). In Fig. 3 is shown distribution of EDC in individual events. Number of EDC Fig. 2. Shown in the figure is the fraction of events with alignment EDC, relative to the number of EDC in each family. 15 Lomonosov, Moscow, Russia, Aug 2011

6. 3. Alignment of energetically distinguished objects Fig. 3. a) target diagram for 9 EDC (energetically distinguished centers) found in a super-family Pb-20 in PAMIR experiment with deep lead-emulsion chamber, 5 = 0.94 (events with alignment of 5 EDC); b) diagram *(*) in the center-of-mass for the same event as it should appear in collider experiment; the EDCs (particles) are numbered in order of decreasing energy. The energies of EDC: 15 Lomonosov, Moscow, Russia, Aug 2011

7. 3. Alignment of energetically distinguished objects The spatial distribution of the most energetic clusters in the transverse (xy)-plane for a few generated events along with the corresponding values of N are presented in Fig. 4. The alignment parameter N, for N EDCs is: Here ijk is the angle between two vectors (rk – rj) and (rk – ri) (for the central spot r = 0). This parameter characterises the location of N points along a straight line and varies from 1/(N  1) to 1. For instance, in the case of a symmetrical, close to the most probable random configuration of three points in a plane (the equilateral triangle) 3 = 0.5. The case of perfect alignment corresponds to N = 1, when all points lie exactly along a straight line, while for an isotropic distribution N< 0. Fig. 4. Samples of EDC distributions for PYTHIA simulated events with Ethr = 10 PeV and 4 > 0.8. The size of spots is proportional to their energy (except for the central EDC which is not to scale). 15 Lomonosov, Moscow, Russia, Aug 2011

8. 4. Heavy stable particle There is one more exotic phenomenon observed in cosmic ray experiments with multilayer calorimeters (fig. 5) – the unusual energy transfer into the depth of absorber (fig. 6). The analysis of this effect revealed other unusual properties associated with the same group of events, which allow consistent explanation assuming the production of a massive (M ~10 GeV/c2), stable ( ~1010 sec) particle with interaction length in the dense matter substantially larger that of regular hadrons [9, 10] (fig. 7, 8). If such particle exists it will most likely avoid observation in accelerator experiments with standard trigger criteria which typically reject long living secondaries (i.e. too remote decay vertices). The results of analysis are shown in fig. 7, 8. 15 Lomonosov, Moscow, Russia, Aug 2011

9. 4. Heavy stable particle Fig. 6. Typical cascade with two “humps” of ionization, and its different interpretations. Fig. 5. Multilayer calorimeter. 15 Lomonosov, Moscow, Russia, Aug 2011

10. 4. Heavy stable particle The average cascades for regular hadronic events (dashed) and T events (solid). Numbers near cascade curve  energy in GeV. The correlation function W(T) N N T h W(T) N(x) Fig. 7. W(T). Fig. 8. N(x). 15 Lomonosov, Moscow, Russia, Aug 2011

11. 5. Discussion and Conclusions[6-11] 1. Centauros * The analysis of the data on Centauros, first of all of the observation conditions in cosmic ray experiments, shows that the basic indicator of such phenomenon in experiments at LHC should be the fluctuations in individual events of hadron to photon ratio as a function of energy transfer in interaction, i.e. from q2 = tat any values of rapidity  and azimuthal angle . 2. Alignment * The phenomenon of alignment indicates that the secondaries are produced within a certain azimuthal plane (the coplanar production). Until now, no satisfactory and unambiguous explanation of the alignment phenomenon was found, in spite of repeated attempts to offer its reasonable interpretation. References to the relevant publications may be found in [6]. * We also analyzed the conditions for observation of alignment phenomenon. In cosmic ray experiment, the location (altitude) of generation point and the distances between the EDCs are the most substantial variables for the interpretation of events with apparent alignment, which determine where these events should be sought for (e.g., as applied to the CMS experiment at LHC). 15 Lomonosov, Moscow, Russia, Aug 2011

12. 5. Discussion and Conclusions At energies s = 5.514, assuming the generation point in cosmic experiment located h = 1000 m above the detector, the alignment would reveal itself at LHC in the forward rapidity region: rmin < ri i < max = ln(r0/rmin)  4.95, (1) ri < rmax  i > min = ln(r0/rmax)  2.25,(2) where r0 = 2h/e0 = 2hmp/s, where 0 = 9.55 is the center-of-mass rapidity in lab, i is the particle rapidity in the center-of-mass, and ri is the radial coordinate of the particle in the detector (emulsion). At LHC, the strong azimuthal anisotropy of the energy flow (almost the whole energy deposit along one radial direction) will in this case be observed for all the events depositing the energy above certain threshold in the rapidity region (1)-(2). Note, that at present there are no models or theories expecting such azimuthal anisotropy for s  4 TeV and h  1000 m. The calculations made using Monte-Carlo generator PYTHIA [6]. 15 Lomonosov, Moscow, Russia, Aug 2011

13. 5. Discussion and Conclusions 3. Heavy stable particle The unusual energy transfer into the depth of absorber was observed in different cosmic experiments and in accelerator experiment at Fermilab with ionization calorimeter [11] and has no explanation. Fig. 9. Calibration at Fermilab of ionization calorimeter (x ~10 int) with 300 GeV protons compared to MC [11]. 15 Lomonosov, Moscow, Russia, Aug 2011

14. 5. Discussion and Conclusions Our explanation * The analysis of this effect in MSU experiment [9] revealed other unusual properties associated with the same group of events, which allow consistent explanation assuming the production of a massive (M ~10 GeV/c2), stable ( ~1010 sec) particle with interaction length in the dense matter substantially larger that of regular hadrons [9, 10] (fig. 7, 8). * If such particle exists it will most likely avoid observation in accelerator experiments with standard trigger criteria which typically reject long living secondaries (i.e. too remote decay vertices). To study this effect ( ~1010 sec) at accelerator, a specialized experiment is required. At LHC: too large energy (too long decay path). 15 Lomonosov, Moscow, Russia, Aug 2011

15. Acknowledgements I am grateful to A.I.Demianov, A.K.Managadze, I.P.Lokhtin and A.M.Snigirev who participated in the work, and also to N.P.Karpinskaya and A.S.Proskuryakov who helped in preparation of this report. Thank you. 15 Lomonosov, Moscow, Russia, Aug 2011

16. References [1] Japan-Brasil Collaboration: Conference Papers, Denver Conference of Cosmic-rays, 3 (1973), pp. 2210, 2219 and 2227. [2] Brasil-Japan Emulsion Chamber Collaboration. 14th International Cosmic Ray Conference. Conference papers, v. 7, Munchen, Germany, 1975, p. 2393. [3] A.Borisov et al., PAMIR Collaboration, Phys. Lett. B, 1987, v. 190, No. 1, 2, p. 225-233. [4] Иваненко И.П., Копенкин В.В., Манагадзе А.К., Ракобольская И.В., Письма в ЖЭТФ, 1992, т. 56, №4, С, с. 192-196. [5] V.V.Kopenkin, A.K.Managadze, I.V.Rakobolskaya, T.M.Roganova, Phys. Rev. D, 1995, v. 52, No. 5, p. 2766-2774. [6] A. De Roeck, I.P.Lokhtin, A.K.Managadze, L.I.Sarycheva, A.M.Snigirev. Proceeding of 13th International Conference on Elastic and Diffractive Scattering (Blois Workshop). Moving Forward into the LHC Era, 2009, talk of A.M.Snigirev, CERN – Geneva, edited by M.Deile, D.d’Enterria, A. De Roeck. [7] И.П.Лохтин, А.К.Манагадзе, Л.И.Сарычева, А.М.Снигирев. Изв. РАН, сер. физ., т. 75, №3, с. 418-420. [8] A. De Roeck, I.P.Lokhtin, A.K.Managadze, L.I.Sarycheva, A.M.Snigirev, CMS ridge versus Pamir alignment (in press). [9] А.И.Аношин, Г.Л.Башинджагян, Л.И.Бельзер, А.И.Демьянов, В.С.Мурзин, Л.И.Сарычева, Н.Б.Синев, Письма в ЖЭТФ, 1972, т. 15, вып. 1, с. 10-13. [10] А.И.Демьянов, В.С.Мурзин, Л.И.Сарычева, Ядерно-каскадный процесс в плотном веществе. – М: Наука, 1977 – 204 c. [11] Gustafson H.R., Jones L.W. and Longo M., ICRC 1975 (Munchen), v. 9, p. 3239. [12] И.В.Ракобольская и др. Особенности взаимодействий адронов космических лучей сверхвысоких энергий. – М: Изд-во МГУ, 2000 – 256 с. 15 Lomonosov, Moscow, Russia, Aug 2011

17. BACKUP SLIDES 15 Lomonosov, Moscow, Russia, Aug 2011

18. Fig. 10. The typical energy deposition in the centre-of-mass system for alignment events in the laboratory frame. 15 Lomonosov, Moscow, Russia, Aug 2011

19. Fig. 11. The alignment degree PN as a function of cluster number N = Ncat h = 50 m and s = 14 TeV in linear (a) and logarithmic (b) scales. The solid curve is the result (coincident with one at h = 1000 m) without restriction on the minimum value of process hardness pminThard, the dotted curve – at pminThard = 300 GeV, the dashed curve – at pminThard = 3 TeV. Points () with errors are experimental data from [4,5,6]. 15 Lomonosov, Moscow, Russia, Aug 2011